CA1074181A - Descender printing system for dot matrix printer - Google Patents
Descender printing system for dot matrix printerInfo
- Publication number
- CA1074181A CA1074181A CA269,613A CA269613A CA1074181A CA 1074181 A CA1074181 A CA 1074181A CA 269613 A CA269613 A CA 269613A CA 1074181 A CA1074181 A CA 1074181A
- Authority
- CA
- Canada
- Prior art keywords
- descender
- printing
- line
- record sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J11/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, for supporting or handling copy material in sheet or web form
- B41J11/36—Blanking or long feeds; Feeding to a particular line, e.g. by rotation of platen or feed roller
- B41J11/40—Blanking or long feeds; Feeding to a particular line, e.g. by rotation of platen or feed roller specially adapted for printing musical scores
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J19/00—Character- or line-spacing mechanisms
- B41J19/18—Character-spacing or back-spacing mechanisms; Carriage return or release devices therefor
- B41J19/20—Positive-feed character-spacing mechanisms
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Character Spaces And Line Spaces In Printers (AREA)
- Record Information Processing For Printing (AREA)
- Dot-Matrix Printers And Others (AREA)
Abstract
DESCENDER PRINTING SYSTEM FOR
DOT MATRIX PRINTER
Abstract of the Invention A descender printing system for a dot matrix printer, comprising a detector for detecting code words representative of descender characters (lower case letters, punctuation, fractions, etc.) prior to printing, and shift means for actuating the line feed mechanism of the printer to advance the paper by two or more dot heights and thereby print the descender elements of such characters below the normal base line. The shift means again actuates the line feed mechanism to return the paper to its original position when the next non-descender character is to be printed.
DOT MATRIX PRINTER
Abstract of the Invention A descender printing system for a dot matrix printer, comprising a detector for detecting code words representative of descender characters (lower case letters, punctuation, fractions, etc.) prior to printing, and shift means for actuating the line feed mechanism of the printer to advance the paper by two or more dot heights and thereby print the descender elements of such characters below the normal base line. The shift means again actuates the line feed mechanism to return the paper to its original position when the next non-descender character is to be printed.
Description
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Background of the Invention In a dot matrix printer, each character i~
reproduced as a series of dots arranged in accordance with a predetermined format. One common commercial format, usually referred to as the 5 x 7 format, comprises seven horizontally extending rows of dots in five vertical columns. Usually, three blank columns are left between individual characters.
Another common f~ormat i6 a 7 ~ 9 dot array. With either format, all capital letters, all numerals, most lower case letters, and many forms of punctuation can be readlly and effectively reproduced in highly ;~ readable form.
There are a ~ariety of other characters, however, that produce substantial technical problems ln dot matrix printers~ These are the lower case letters p, ;, y, q, and g, having descender elements .
that project below the base line' of a line of type.
In this same ~ategory are some punctuation marks .. . ...
~ 20 such as commas and semi-colons~ subscripts, and, in ; some instances, portions of fractions. For these characters, referred to herein as "descender charactersl'?
the usual vertical array of print dot positions in a standard character format is inadequate because there are no print elements available to pr~nt dots : ~ .
below the base line.
~ It has been common practice, in dot matrix `: ~ :
printers, to print the descender chara~ters completely ~ abo~e the horizontal base print line~ This results 1 3Q in an appearance : ~ .
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that does not conform to ordinary practice and is ~atisfactory in many applications, particularly where appearance c~nd ease of readability are required.
~ nother known technique for printing descender characters entails the addition of two or more print rods to the printer~ located helow the vertical array used for printing the standard format. This construction materially increases the weight and inertia of the print head, which are already critical factors in a high speed printer. In addition, the cost of the print head is substantially increased, becau6e the print rods, print rod guides, and print rod actuating magnets, particularly in high speed printers, are precision mechanisms for which the cost is quike appreciable. Examples of dot matrix printers that provide additional print rods for printing descender characters are shown in ~.SO Patents ~os. 3,426,880,Fe~ruary 11, 1969, and 3,627,096, December 1~, 1971.
~ nother arrangement for printing descender characters in a dot matrix printer, one that does not use additional print rods for printing below the noxmal base line, i5 shown in U.S. Patent ~oO 3,759~3590 Sept. 18, 1973. In that device, the print head is pivoted downwardly to print each descender ; character, the downward movement of the print head being . :
equal to the height of the two printed dots. This arrangement is useful only if the printer has a large diameter platen.
Otherwise~ the displacement of the print head from the normal position for printing above the base line to the position in . .
whlch descenlder elements are printed below the hase line changes the relative spacing between the tip ends of the print rods and the platen surface, so that the top print rods are located much closer to the platen surface than the bottom print rods. Thus, in a printer having a platen of small diameter, this construct:ion results in a ~ubstantial degradation of print ~uality for the bottom portions of descander characters or in puncturing of the paper for the upper dots in such characters. Further, the cost of the precision print head is again increased.
For printers that op~rate at relatively low print rates, such as the standard telex rate of six characters per second, a large platen may not be particularly disadvantageous.
For higher speeds, however~ a large diameter platen introduces rather severe problemsO The inherently greater weight re~uired ~or a large platen imposes a requirement for higher torque on the line feed mechanism of the printer. The greater inertia of a large platen may result in an undesirable lengthening of the time required for the line feed operation. The rapid movement of the platen necessary to advance the paper from a masked position behind a ribbon or other masking portion or the printer to a viewing position, as in the text display control describad in Canadian Patent ~o. 1,011,161, May 31y 1977, m~kes a large diameter platen quite undesirable. More-over, a larye platen inherently increases the overall size of the printer, which is quita undssirable in many applications.
Summar~ of the In ention It is a principal object of the invention, there-fore, to provide a new and improved descender printing system for a dot matrix printer that effectively and inherently eliminates or minimizes the substantial technical problems of previously known systems a~ described above.
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A speclfic objec-t of the .invention i~ to provide a new, improved, ancl practical dessender printiny sy.~-tem for a high speed dot matri.x printer, us-,ng a srnaLl cliame-ter platen, with no additional print rods over and above the numher required for printing in a standardized -format.
Another object of -the invention is to provide a new and improved descender printing system for a high speed dot matrix printer that requires no modification oE the print head.
A particular object of the invention is to provide a new and improved descender printing system ~or a hiyh speed dot matrix printer in which the print head and paper are re-aligned vertically for printing each descender character by movement of the paper, with no vertical movemen-t of the print head.
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Accordingly, the invention relates to a dot matrix printer of the kind comprising.a print head, including a : plurality of print elemenks disposed in a vertical arcuate array, for printing characters on a record sheet supported .
upon a cylindrical platen in a format m x n of m horizontal column increments and n vertical row increments, a carriage for moving the print head across the record sheet in a . .
~ ~ horizontal printing direction with the lowermost printing .
element normally aligned with a horizontal base print line - on the record shee~, and control means, including a FIF0 input store, for actuating the print elemen-ts and t~e carriage n response ~o a received signal including a series of code words representative of characters to be printed and of other func tions o~ the printer. The improvement of the lnvention comprises descender decoder means, coupled to the . ~. . . . . . . . .
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input stor~, fo:r c~ecodi.ncJ cocle words r~p:r~sen~ative of descender chlracters that includ~ d~scencler component~ to be located below the base print line, prior to printing o~ suc7n desc~nder characters, and descender shift mearls, coupled to the descender decoder means, for shi~ting the record sheet upwardly through a distance L equal to p row increments, from a normal print position to a descender print position, aligning p print elements below the base print line Eor printing each descender character, where p ~n O Shi:Et rese-t m~ans are inclucled in the descender shift means, for shiftincJ the record sheet downwardly throuyh distance L ~rom the descender print position to the normal pri~t position, after completion of printing of a descender character, to permit printing a sub.se~uent character entirely above the base line.
~ Brief Des~ription of the ~rawinqs . FigO 1 is a simplified plan view of a high speed dot matrix printer of a kind i.n which the descender printing system of the present invention may be incorporated to particu-lar advantage;
. FigO 2 is a detail sec~ional elevation view of a : ~ :, , .
~ part of the printer taken approximately along line 2-2 in . ~ ,~ . .
: Figs, 3A through 3K illustrate a numbex of dif~erent . characters, mostly descender characters, printed by the printer o Figs~ 1 and 2;
FigO 4 is a block diagram of a control system for the printer of FigsO 1 and 2, incorporating the control : elements of a descender printing s~stem constxucted in accordance : .: `with~one embodiment of the present invention; and :~: ~ Fig. 5 is a block diagram of a.preferred embodiment o~ the present i~vention~
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~L~ = IC~h~ ~z~ L~e~err~d ~'~m~o i.~n~nt~_ E~i.g~. 1 and 2 il:l.ustrate a high speed dot rnatri~
printer 10 in which -the descender character printiny systeM
of the present invention can be employed to substantial advantage; printer 10 produces characters in the dot matrix forms illustrated in Figs. 3~-3K. Printer 10 comprises a base 11 wi-th two vertical Erc~me members 12 and 13 a~fixed to itC
opposike sides. A pla-ten 14 ls m~unted upon a rotatable shaft 15 that extends between the two side frarne ~embers 1 10 and 13. A knob 16 is mounted on one end of shaft 15 to provide for manual rotation of platen 14.
Two carriage gui~le rails 17A and 17B are mounted at the front oE printer 10, extending t.ransversely of the prin-ter between Erame members 12 and 13, parallel to platen 14.
print head carriage 18 is slidably mounted on guide rail5 17A and 17B
and is connected to the ends o-E a carriage positioning belt 19. Preferably, belt 19 is a toothed belt of the kind known as a timing belt. The right hand side of belt 19 extends : around a drive sprocket 21 mounted upon a shaft 22 that ,~
projects upwardly from the printer base 11. The opposite side of belt 19 engages another sprocket 23 mounted upon a vertical shaft 24 at the left hand side of base 11.
The sprocket shaft 22 is connected to a pulley (not shownj that is engaged by.a drive belt 25~ Drive bel-t 25 ext~nds around a drive sprocXet 26 mounted upon the sha-Et of a reversible stepping motor 28 used as a carriage drive motor.
he carriage drive motor 28 is a re~ersible motor -that rotates thro~gh a discrete angle each time an electrical signal pulse s:applied to the motor windings. Printer 10 may include two 0 margin control switches 31 and 33 mounted on base 11 in , : ., ,, : , .
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position to be actuated by carriage 18 (E'ig. 2). Switch31 is located at the left-hand side of printer 10 and switch 33 is located at the right~hand side of the printer.
Printer 10 also includes a line feed motor 34 mounted in the rear left-hand corner of base 11. Motor 34 is a reversible stepping motor similar to the carriage drive motor 28. A drive connection is provided between motor 34 and platen 14, comprising a drive sprockek 35 mounted on the output shaft of motor 34 in engagement with a belt 36 that also engages a driven sprocket 37 mounted on platen ~haft 15.
~ roll of paper record sheet matarial 41 is mounted at the rear of the printer 10 (not shown)~ The paper record sheet 41 extends around the platen 14 as shown in Fig. 2, and under a bail bar 54 (Fig. 1) that maintains the paper in contact with the platen. The portion 42 of the record sheet 41 that projects upwardly from platen 14 (Fig. 2) is the portion on which data has previously been recorded by the printer.
; A plurality of prink head magnets 51 are mounted upon the print head carriage 18 (Figs. 1 and 2). In one typical construction, a total of saven print head magnets 51 : ' :
ara employed, as shown in Canadian Patent No. ~62,124, February ~` 4, 1975. Each of the print head magnets 51 affords a drive means for axial movement of an individual print rod 52.
Th~s ~nds of the print rods 52 terminate in a vertical arcuate array spaced a small, uniform distanca d from platen 14 ~FigO 2~ at a printing station 53 (Figr 1) that traverses the platen longitudinallx as the print head carxiage 18 moves alony the guide rails as described hereinafter.
It will be recognized that details of a number of the , ~ .
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mechanical linkages in printer 10 ~ave been omitted as unnecessary for an understanding of the present invention;
these may include a return spring for the return of print head carriage 18 to the le~t-hand margin o the printer and a clutch to release the carriage drive for a carriage return movement. The preferred construction for carriage 18, magnets 51, and print rods 52 is illustrated in detail in Ca~adian Patent No. 962,124, February 4, 1975 Impact-sensitive paper may be utilized as the recordiny sheet 41 in printer 10. On the other hand, in many applications this relatively e~pensive paper may not be deslrable. For such applications, printer 10 may be equipped with a ribbon 55 that extends through printing station 53 (Fig. 1) between platen 14 and the tip ends of print rods 52.
The ends o ribbon 55 are taken up on two spools 56 and 57.
If a ribbon is employed, an appropriate mechanism for advanc-ing ribbon 55 to present fresh lengths o~ the ribbon for successive imprints is incorporated in printer 10, but has not been shown in the drawings.
; 20 The basic construction fox printer 10, as described above, is already known in the art, so that only a brief description o~ the mechanical operation of the printer is necessary in this specification. Before printer 10 is placed - i .
'J in operation, as noted above, the paper record sheet 41 is extended around platen 14, between the platen and the outer ends of the print rods 52. The starting position for the print head carriage 18 is at ~e left-hand end o~ its travel on rails 17A,17B~ nearthe left-hand margin switch 310 For the first character to be imprinted, such as the character ', ~.,.
"P" illustrated in FigO 3A, carriage 18 advances a given \
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number oE discrete steps ~rom leEt to ricJh-t, the carr:ia~e being driven ~y its positioning beLt 19 throucJ'h -the drive affordecl by motor 28, drive belt 25, alld sproc'~et 21. In the illustrated ernbodimen-t, eig'ht discrete s-teps are used for each character. During the first three steps or incremental column movements o~ carriage 18, no impression is made on paper 41. In the next five steps of the carriage, a complete character is imprinted by selective actuation of prin-t rods 52. Of course, a differen-t format cou].d 'be employed, depending upon the requirements oE t'he symbols to be printed and other factors not critical to the present :invention.
As shown in Fig. 3A, -the initial advancing movement of carriage 18 leaves three blank columns 61, 62 and 63 preceding -the first printed character. In the next column 64~ all seven of the print rods 52 (shown a-t positions 52~-52G in Fig. 3A) are driven into impact with the record sheet, producing seven ver-tical dot impressions 59. On the ne~t incremental step 65 in the advancing movement of carriage 18, only two dot impressions 59 are formed~ one by print element 52A and the other by print rod 52D. This action is repeated in the next two columns 66 and 67. In the eiyhth step for : . , carrlage 18, the print rods 52B and S2C are actuated, producing dot impressions in the final column 68. This .: ~
results in the formation o~ the letter llp!' as illustrated in Fig. 3A. In~this'same manner, a complete line of data symbols letkers, numbers, or other symbols) is imprinted across the paper recorcl sheet 41 on platen 14, with carriage 18 moving from le~t to right (Fig. 1) a total of eight s-teps -Eor each ndividual symbol.
Figs. 3B through 3K illustrate additional characters , ::
10 ' -` ~ ` , `~' . ` ` ' ` ' ' ' , , ' ` I ' ' ~nd syI~ol~ that printex 10 ma~ be required to reproduce.
Flg. 3B illustrates -the lower case lette~ "p" as it would be reproduced by ~nown printers having no p~ovision ~or printing descender elements below -the hor:izon-tal print base line 80. This let-ter, .in the form shown in Fig. 3B, is not always recognizable, in ~ rapid scan, because i-t i5 not located in the usual positi.on. Descender characters printed in the manner illustrated by E'ig. 3B thus deyrade the readability of the printecl data~
E'igs. 3C through 3K il:Lustr~te various descencler characters as prin-ted by printer 10 when eqw.pped with the descender printing system of the present invenklon. To print these characters, the paper 41 (FigO 2) is advanced in the direction o:E the arrows A (Fiys. 2 and 3C) to realign the paper with the print head, so that the print elements 52 occupy the vertical positions 52A'-52G' as shown in Fig. 3C.
: With this realignment for descender printing, th~ base line .
80 on paper 41 is raised ahove the print rods at positions ~ ::
52F' and 52G'. Irhis makes possible the printing of all of : the descender characters (Fiys 3C-3K) with no need for additional print elements in printer 10~ The descender .
printing system is described in greater detail hereinafter.
At the end of any complete movement of eight column ;- increments for carriage 18, whether or nok that movement includes:prin.ting of a data symbol, the carriage may be retuxned to the left-hand limit of its travel to begin the ; : printing of.a new line of text on the paper 41. The carriage : return operation may be initiated by a carriage return code word in an input signal to control printer 10, or by engage-.ment of:carriage 1~ with the ri~ht hand limit switch 33.
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That is, switch 33 can be employecl to actua-te t'n~ carria~
return and line :Eeecl mechanis~s ~f pri.n-ter 10 on a manda-tor~
basis to return the carriaye to the ini.tia]. le:-t-ha.nd position for the beyinning of a new line and to feed t~e paper web 41 around platen 14. Before printiny o e a new line of text is initiated, the line ~eed drive motor 34 rotates platen 14 through a number of incremental steps, by means o the drive connection 35-37, ali.gning a :Er~h llne segment of the record sheet 41 with carriage 18. Other non-print function codes may be included in the received siynal to control other printer operations.
Fig. 4 ls a block diagram o:E a basic control s~stem 70 for printer 10, The input stage o control system 70 . comprises an inpu-t logic circuit 73 to which an input signal j~ is supplied, either from a keyboard .or from an in~ut transmission line. The output of logic circuit 73 comprises a series of data output circuits 74 and a load signal circuit .~ 75, all coupled to the input level o an input clata store 76.
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~ Data store 76 could be constructed with a single storaye level ~ . , for recording ~ust one code word representative o~ a single data symbol:or of a single non-print unction or the printer.
Preferably, however, data store 76 includes a plurality o~
storage levels, capable of recording a su~stantial number of ~.
1~ ~
:code words.
The output of data store 76 is coupled, by a plurality o data output circuits 77, to the input o a p~int control and character ge~erator unit 79. A print clock control , ~ , connection 78 is also provided, be-tween data store 76 and the~inpu-t of the prin-t control~character generator uni-t 79 , ~ 30 to affoxd a means for inter-relating the timing of unit 79 ~ ~ .
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oper~tions with thoqe in data sto~l 76. rrhere ~re seven output circuits 82 Erom unit 79 to a. print head driver circuit unit 81~ Th~ print head driver circui-ts 81, in turn, include an equal number of output circuits 80, individuall~ connec-ted to t-he print head maynets 51 of carriage 18.
The printer control system 70, Fig. 4, also includes appropriate non-print function detecto.r circuits incoxporated in a decoder circult unit 83. Each of the outputs 77 from data store 76 is connected to an inpuk or function decoder 83. Decoder 83 has a carriage re-turn output circuit 84 that is connected to the input o a carriage actuator unit 85.
The carriaye actuator unit 85 also receives a step signal input from the print control and character yenerator unit 79~ through a circuit ~6. Carriage actuator unit 85 has four outputs that are coupled to a set oE carriage driver circuits 87, in turn.coupled to the carriage drive motor 28.
The left-hand switch 31 and the xight-hand switch 33, if , present, are aLso connected to the carriage dxivex circuits 87. ~ .
: A line feed output 91 fxom the non~print function :
decode~ uni.t 83 is connect:ed to the input of a line feed actuator 920 Actuator 92 has four output circuits, connected through line feed driver circuits 93 to the line feed drive motox 34.
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Printer contxol 70, as-thus fax described, is :
genexally conventional in constxuction and organization~
-~ : An input signal including a sequence of code words repxe-: . .
sentati~e both of symbo~s to be printed and of non~print 30: ~ fuDctions for pxlnter 10 IFi~s. 1,2) is applied to the input ; i.:
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loyic c.ircuit 73 (]?ig. ~ rhc source o~ the input sicJnal may be ei.-ther a keyboard or a transrn:ission ].ine. Input logic circuit 73 detects the proper star-t-s-top sequence of the encoded data ancl converts -the data from serial to parallel form. For each received code word, a plurality o~
parallel ou-tput signal pulses and a load pulse are applied to the inpu-t of data store 76 to recorcl the code word in the data store. No other exte:rnal ope:rating sicJnals are re~uired for the lnput lo~ic 73 in normal operation of 5ystem 70.
Data s-tore 76 records each code word as received;
; the data store may be a convent.ional shift register memory with internal transfer between sequential storage levels, or a conventional RAM device. In eit~er case, it functions as a FIF0 storaye unit~
At the beyinning of each prin-t cycle, a print clock control signal is developed, and is applied to ~he print control logic circuits in unit 79 to activate internal timing logic t~at applies a column count signal to the integral character generator. The same print timing arrangement supplies a step timing signal to the carriage actuator 85, ~ .
through circuit 86. For a non-print code word, identified by the decoder circuits 83, the character generator in unit 79 is inhibited by an appropriate signal supplied -thereto through circuit 88.
Prlor to each cycle o~ the printer, the next code wo~d in~data store 76 is sampled by the decoder circuits .in unit 83. In this manner, carriage return and line feed codes are detected, producing suitable ~ontrol signals ~ ~supplied to carriage actuator 85 and line feed actuator 92 ::
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for control of these printer operatio~s. The inputs to the carriage driver circuits 87 ~rom the carriage position sensing switches 31 and 33 are utilized for internal logic resetting functions. Thus, the basic operation of control system 70 is essentially similar to the system described in detail in Canadian Patent NOD 9~5,475, April 16, 1974, to which referencs may be made for further details of a practical printer control system.
Control syst~m 70, however, incorporates a descender contro~ logic unit 101 having a number of different inputs.
one input is the step signal, on line 86, from print control 79O ~nother input 102 to the descender control logic 101 is derived from a descender character decoder 103 coupled to the output of data store 76. ~nother input may be the line feed signal on line 91, derived from the non-print function decoder unit 83; the nor.mal line feed connection of line 91 to actuator 92 may be omitted. ~dditional inputs to logic unit 101 may be provided from other parts of the overall control system 70, depending upon the specific circuits utilized in the overall printer control. Descender control , 101 further includes two output circuits 105 and 106 connected to line fead actuator 92. Additional outputs for logic unit 101 may also be requirad. The output connections 105 and 106 are^ employed to supply a descender positioning signal and a ':
reset signal to the record sheet shift maans comprising line feed actuator 92, driving circuit~ 93~ line fead drive motor 34, and the ~ne chanical linkage 35-37 to the platen 14~
In operation, whenever a code word for a descender charactex is stored in the output of data store 76, this .
condition is detected by the descender detector 103, and an ~7~
output signal is applied to control 101 on line 102.
Control 101 supplles a descender posltloning signal to line feed actua-tor 92 to actuate the line feed driver circuits 93 and enercJize line feed drive motor 34. ~o-tor 34, throuyh the drive connection 35-37, rotates platen 14 throuyh one or more increments of movement, thereby advanclny record sheet 41 vertically to a position at which lowermos-t print elements 52 are below the base line 80 (Fig~ 3C). In a typical s~stem, the paper record sheet 41 is advancecl by a distance L precise~ly equal to the total heiyht oE two of the printing row incremen-ts represented by the dots 59. This applies to a 5 x 7 matrix format as shown in E'igs 3A-3K. For any ma-trix of n vertical printiny elements, printing in a format of m x n, where m is the number of column increments, the distance h is equal to vertical row increments, and ~ is substantially smaller than n. With a 7 x 9 format it may be desirable -to shift paper 41 thxough a vertical distance L equal to the height of three , ~ print dots to achieve the best proportions between descender :
and non-descender characters. Thus/ n = 9 and _ = 7; for this ~ ~20 format ~ - 3.
`~ Subse~uently, when printin~ o a descender character is complete, a reset signal is generated in control unit 101 and supplied to line feed actuator 92 to again actuate the record sheet shift mechanism and move the record sheet 41 back into its original printing position for printing of the next character in the text. Reset ma~ be triggered by thé~step signal (line 86) for the next character. OE course, reset should not be effected if the next character is a , descender character; in such circumstance, the reset is ; precluded by a new descender character identification signal , ,, .
from cl~cocler 103. In this manner, the ~ext contilluity is maintain~d and the format of -the pr:inted -text :is pre.served as s'hown in Figs. 3C-3:K.
As will be apparent from -the foregoiny clescription, the addition of the descender printing s~stem comprising logic control unit 101 ancl its connections to contxol s~s-tem 70 ~Fiy. 4) does no-t in-terfere with normal continuous opera-tion of the printer and does not in'hibit the speed of continuous operation, provided platen 14 can ~e rapidly shifted to move paper ~1 to and from the posi.-tion re~uired to print the descender cllaracters (Figs. 3C-3~). With a large platen, however, this requirement.becomes difficult or even impossible to achieve in an economically feasible printer. Platen 14 should be small in diameter and light . in weight to allow motor 34 to shift the platen between its descender and non-descendex printing positions within less than three and pref.erably less than one column step inter~al.
For a tan-charac-ter-per-secon~ machine, using a 5 x 7 format with 8 columns per character, as shown, this is a shift.
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' 20 interval t of 0.0125 second or less. For a 30 cps printer, the shift interval is preferably ~00417 second or less.
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of course, the diameter of platen 14 cannot be reduced ndefinitely; the platen diameter D must exceed the overall helght EI of the dot matri~ format (see Fig. 2).' A good :working relation~ keeping t'he platen diameter to a minimum size, is to maintain . 6H'-,~ D ~ 2H.
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With the descender printing system o~ the invention, there is :no distort.ion or disturbance in the prin-ted text and the ~control is fully automatic, requiring no mechanical changes . : .
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in -the pxinter. The log:i.c un.il 101 can be full~ constructed from solicl sl;ate circ-~itry, and hence :is quite capable o~' lon~--term opera-tl.on with little or no specia]. maintenance or expense, and is xelatively simple and economic in construc-tion.
For some composite characters, such as -the fractions shown in Figs. 3J and 3K, a part of the character may appear in the uppermost rows of the stancLard format and a partl~ay extend .into the bottom rows of the descender format. These composite characters can be printed accurately if the transition time between normal and descender printiny positions, for record sheet ~1, is made sub5tantially less than the time required to advance the platen horizonta].ly by one column increment, since the actual pxinting stroke of the print rods 52 is only a minor fraction of the total column ~` time. Of course, the characters must be limited to dots, .
in each column, in only as many adjacent vertical row positions :
as there are print rods 52.
Specific circuitry to implement the addition of descender control 101 and desc~nder decoder 103 to control system 70 may be relativeIy simple. Decoder 103 is a conventional circuit constructed to identify those received code words representative of the descender characters and to supply appropriate identification signals -to control l01.
A series o A~D gates and NOR gates, appropriate to the transmission code, will suf~ice.
CorltroL 101 may be cons-tructed in TTL logic in a manner~essentially similar to the logic circuits disclosed in ~he text display system of U~S~ Patent No. 3,8~4,395, .
~ 30 makiny due allowance for different input signals and for -the : ~
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O nece.ssity for rapicl ~ctuation of the platen throuyh a small distance :instead o the delay~d cactuation through a much larger distanc~ as provided in that patent~ The text , ~/,.S, . display of~Pat~nt NoO 30844, 395 and the descender p:rinting system of the present invention can be read:ily combined in a given printer.
Fig. 5 illustrates, in block diayram forrn, a general printer control system :L50 incorporatiny a pre~errecl embodimen-t of the present invention. The transmission line input stage 73' of system 150 includes a line interface circuit 151 to which a telegraph input signal is supplied on line 152~ The input signal may be encoded in accordance with the standard eleven-unit ASCII code or the conventional se~en and one-half unit Baudot code; other permutation codes can be employed with appropriate modifications in the control system to interpret the codeO
; ~ ~ The output of line relay 151 is connected to à
uni~ersal asynchronous receive/transmit (UART) lnput-output . logic circuit 153~ For example, U~RT circuit 153 may comprise a MOS/LSI unit as manufactured b~ SMC Microsystems Corporation, Model COM2502/~I or COM2017/~I, suitably programmed for data woxd length, parity mode and number of stop bits to conform to the requirements oE the data input signal supplied -Erom line 152 through inter~ace circuit 151. ~ basic timing signal is supplied to the UART circuit 153 from a crystal-controlled , :. ~ : - : . . - ;
oscillator 154v - The UART device 153 has a data output connectio~
155 to a main control logic unit 157; there is also a control .output 156 from the main control logic unit back to U~T
device 153. Unit 157 comprises a rniniprocessor or ~ o~
micro~ornputer ac; a central ~rocesC;iny unit (CPU), ~ith suitable auxi.Liary circuits sucll as an lnpu-t MuLtiplexer and output registers, progra~ned to carry out the descender print control operations of the present invention as well as the many other functions necessary to control printer 10.
The main logic unit 157 has outpwt and input connections 158 and 159 to a character yenerator 161O Chaxacter generator 161 ma~ be O:e conventional construction; for ex~mple, the character gençrator may compx:ise two type 8316 read-onl~
memory (ROM) devices proyra~med in accordanc~ with the de.sired type font and input data codeO There is also a local data input circuit 162 to logic unit 157 from a ke~board 163, ~or local operation of prin-ter 10 and for transmission-mode operation of the printex.
Control system 150 includes a fi,rst-in first-out (FIFO) input storage register 76. Storage registex 76 has an input connection 1~5 from logic unit 157 and' an output circuit 166 back to the main logic unitO A conventional shi-Et ~ ~ .
~, register may be emplo~ed Eor device 76; as illustrated, ~:~ ; 20 howeverO storage registér 76 is a random access memory (RAM) programmed for ~IFO operation. ~y way of example, storage , . .
register 76 may comprise two type 2112 RAM devices~
The:main lo~ic unit 157 has an output 168 to a : .
single-column storage register 167 in turn'connected to the ,print~head driver circuits 81. 5tore 167 afEords se~en output :` circuits, one for each of the printing rods 52 of printer!l0 (FigO 1), each output is individually connectcd to one of ' :: seven print magnet driver circuits in unit 81. Each print : magnet driver clrcuit is connected to an individual magnet , 30 or soIenoid 51 for actuating one of the print rods 52 (see FigO 1).
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O ~not~r ou-tput 173 fronl the ma:irl corltrol :Loyic un:it 157 extends to a stcpper motor store 17~. T~le store 174 includes a carriage motor storage register connected ~y an output 175 to the carriage motor driver circuits 87 and a line feed storaye reyister connected b~ an output 177 to the line feed motor driver circuits 93~ The carriage motor driver unit 87 has four outputs individually connectcd to ~our motor windings in the carriaye dxive step motor 2~. Siynals from dxiver unit 87 to motor 28 determine khe directi.on o-~ rotation of the motor and control the number o~ steps through which the carxiaye drive motor is driven in any yiven operational sequence~
Similarly, four outputs from the line ~eed motor driver unit 93 to line feed motor 34 supply actuatiny signals to the line eed motor to drive shaft 15 and platen 14, clockwise or counterclockwise, through oxdinary line feed operations, : descender print operations, and any other operations requiring platen rotationO
~ n considering the general operation of control system 150, it may first be assumed that printer 10 is ~eing operated as a receiver responsive to an input signal supplied . to the UART circuit~153 ~xom line 152 through interface circuit 1510 In the UART circuit, each received code word . is converted from series to parallel form and transmitted to the~main cont.rol logic unit 157 as generally indicated by ne 1550 The overall synchronization of operation~ in control system 150 is ef~ected by clock signals from :, : : ~ .
osclllator 154 0 .
The main logic control unit 157 records -the received data .in the input storage reg.ister 164. The recorded : 30 .code words are read from R~M 164 by the main contro]. logic ~", ~
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un.it 157 and supplied to character cJeneratox 16L, which inter-prets eclch code woxd with respect to machine function and supplies machine contro:L slgnals back to the main control loyic unitO ROM 161 also stores the proyrarn for the mini-processor of logic unit 157~ For the printing o an~
individual character, print ~nac~neL- control signals based on the signals from character yenexator 1.61 are supplied ~y the main control logic 157 to store 1.67, in the appropriate se~uence, and then applied to the print magnet drivers 81 for selec-tive eneryization of the pxint maynets 51. Steppiny of the print head 18 through the required sequence of column steps for reproduction of each charactex is effected by stepping signaIs supplied to store 174 from logic unit 157 and applied to motor 28 through the carriage motor driver .
unit 870 Wehnever a code word fox a descender character is read from RAM 76 and decoded in charactex yenerator 161, appropriate signals are supplied from.the m~ln logic uni-t 157 to stepper motor store to actuate line feed driver ~mit 93 and cause motor 3~ to step platen 14 and shift the record sheet 42 upwardLy a distance L of ~ row increments (FigO 2~.
Th-ls, or printing a descender character, the record sheet in ~he printer is shifted to the descender print position (see FigO 3C). If the next code word decoded in character generator 161 is another descender character, the platen and :
. record sheet remain in the.descender print position. If the : next code word is a regular character (not a descender-charactex), in the next print cycle the record sheet.42 is : :shi~ted back downwardly through distance L ~FigsO 2,3) from the descender print position to the normal print position~
i ~ - 22 -.
The descender decoder 103 and descender l.ogic control 101 of Fig. 4 are thus incorporated in the main logic control unit 157 in the preferred embodiment of Fig. 5.
For a detailed disclosure of suitable operating circuits for the miniprocessor embodiment of Fig. 5, including an operating program for logic unit 157t reference may be made to the comprehensive disclosure in U.S~ Patent No. 3,990,559, ~ovember 9, 1976. In that disclosure, the miniprocessor for logic unit 157 comprises a type 8008 CPU; other mini-processor devicest such as the type 8080, can also be employed.
FOr operation of printer 10 with control system 150 as a transmitter, an illpU't signal is supplied from keyboar~
163 to the main control logic unit 157. Operation of the prinker proceeds in the same manner as described above^ the code words of the input signal are recorded se$uentially in RAM 76 and read out in the same sequence for pri.nter actuation.
The signals from key~oard 163 are also supplied fxom loyic unit 157 to UART 153 and from UART 153 to a transmission line 181 ; through a relay transmitter circuit 182.
: 20 The descender pri~ting system of the invention often requires no modification of the :-.~echanical portion of ~: the printer, in a machine ha~ing a small, low-iner~ia platen and having a reversible stepping motor or liXe reversible dri~e used for line feed. The drive ratio betwee~ the line . -feed motor c~d the platen may require some adjustment to . ~ assure movement of platen 14 thro~gh the desired distance L
in an integral number of steps of motor 34, but this can be readily accomplished by appropriate selection of sprockets 35 and 370 The descender printing system has been successfully app:lied to pr.inters operating at print rates well above 30 cps with clear, sharp copy resultincJO ~lthoucJh de.~,cribed in connection with a printer using mechanica:L impact print ele.ments (rods 52), the me-thod and control appara-tus of the invention may also be utilized in a pri.nter employincJ thermal printing elementsO
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, . . .
Background of the Invention In a dot matrix printer, each character i~
reproduced as a series of dots arranged in accordance with a predetermined format. One common commercial format, usually referred to as the 5 x 7 format, comprises seven horizontally extending rows of dots in five vertical columns. Usually, three blank columns are left between individual characters.
Another common f~ormat i6 a 7 ~ 9 dot array. With either format, all capital letters, all numerals, most lower case letters, and many forms of punctuation can be readlly and effectively reproduced in highly ;~ readable form.
There are a ~ariety of other characters, however, that produce substantial technical problems ln dot matrix printers~ These are the lower case letters p, ;, y, q, and g, having descender elements .
that project below the base line' of a line of type.
In this same ~ategory are some punctuation marks .. . ...
~ 20 such as commas and semi-colons~ subscripts, and, in ; some instances, portions of fractions. For these characters, referred to herein as "descender charactersl'?
the usual vertical array of print dot positions in a standard character format is inadequate because there are no print elements available to pr~nt dots : ~ .
below the base line.
~ It has been common practice, in dot matrix `: ~ :
printers, to print the descender chara~ters completely ~ abo~e the horizontal base print line~ This results 1 3Q in an appearance : ~ .
: :
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that does not conform to ordinary practice and is ~atisfactory in many applications, particularly where appearance c~nd ease of readability are required.
~ nother known technique for printing descender characters entails the addition of two or more print rods to the printer~ located helow the vertical array used for printing the standard format. This construction materially increases the weight and inertia of the print head, which are already critical factors in a high speed printer. In addition, the cost of the print head is substantially increased, becau6e the print rods, print rod guides, and print rod actuating magnets, particularly in high speed printers, are precision mechanisms for which the cost is quike appreciable. Examples of dot matrix printers that provide additional print rods for printing descender characters are shown in ~.SO Patents ~os. 3,426,880,Fe~ruary 11, 1969, and 3,627,096, December 1~, 1971.
~ nother arrangement for printing descender characters in a dot matrix printer, one that does not use additional print rods for printing below the noxmal base line, i5 shown in U.S. Patent ~oO 3,759~3590 Sept. 18, 1973. In that device, the print head is pivoted downwardly to print each descender ; character, the downward movement of the print head being . :
equal to the height of the two printed dots. This arrangement is useful only if the printer has a large diameter platen.
Otherwise~ the displacement of the print head from the normal position for printing above the base line to the position in . .
whlch descenlder elements are printed below the hase line changes the relative spacing between the tip ends of the print rods and the platen surface, so that the top print rods are located much closer to the platen surface than the bottom print rods. Thus, in a printer having a platen of small diameter, this construct:ion results in a ~ubstantial degradation of print ~uality for the bottom portions of descander characters or in puncturing of the paper for the upper dots in such characters. Further, the cost of the precision print head is again increased.
For printers that op~rate at relatively low print rates, such as the standard telex rate of six characters per second, a large platen may not be particularly disadvantageous.
For higher speeds, however~ a large diameter platen introduces rather severe problemsO The inherently greater weight re~uired ~or a large platen imposes a requirement for higher torque on the line feed mechanism of the printer. The greater inertia of a large platen may result in an undesirable lengthening of the time required for the line feed operation. The rapid movement of the platen necessary to advance the paper from a masked position behind a ribbon or other masking portion or the printer to a viewing position, as in the text display control describad in Canadian Patent ~o. 1,011,161, May 31y 1977, m~kes a large diameter platen quite undesirable. More-over, a larye platen inherently increases the overall size of the printer, which is quita undssirable in many applications.
Summar~ of the In ention It is a principal object of the invention, there-fore, to provide a new and improved descender printing system for a dot matrix printer that effectively and inherently eliminates or minimizes the substantial technical problems of previously known systems a~ described above.
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A speclfic objec-t of the .invention i~ to provide a new, improved, ancl practical dessender printiny sy.~-tem for a high speed dot matri.x printer, us-,ng a srnaLl cliame-ter platen, with no additional print rods over and above the numher required for printing in a standardized -format.
Another object of -the invention is to provide a new and improved descender printing system for a high speed dot matrix printer that requires no modification oE the print head.
A particular object of the invention is to provide a new and improved descender printing system ~or a hiyh speed dot matrix printer in which the print head and paper are re-aligned vertically for printing each descender character by movement of the paper, with no vertical movemen-t of the print head.
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Accordingly, the invention relates to a dot matrix printer of the kind comprising.a print head, including a : plurality of print elemenks disposed in a vertical arcuate array, for printing characters on a record sheet supported .
upon a cylindrical platen in a format m x n of m horizontal column increments and n vertical row increments, a carriage for moving the print head across the record sheet in a . .
~ ~ horizontal printing direction with the lowermost printing .
element normally aligned with a horizontal base print line - on the record shee~, and control means, including a FIF0 input store, for actuating the print elemen-ts and t~e carriage n response ~o a received signal including a series of code words representative of characters to be printed and of other func tions o~ the printer. The improvement of the lnvention comprises descender decoder means, coupled to the . ~. . . . . . . . .
~, . . .
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input stor~, fo:r c~ecodi.ncJ cocle words r~p:r~sen~ative of descender chlracters that includ~ d~scencler component~ to be located below the base print line, prior to printing o~ suc7n desc~nder characters, and descender shift mearls, coupled to the descender decoder means, for shi~ting the record sheet upwardly through a distance L equal to p row increments, from a normal print position to a descender print position, aligning p print elements below the base print line Eor printing each descender character, where p ~n O Shi:Et rese-t m~ans are inclucled in the descender shift means, for shiftincJ the record sheet downwardly throuyh distance L ~rom the descender print position to the normal pri~t position, after completion of printing of a descender character, to permit printing a sub.se~uent character entirely above the base line.
~ Brief Des~ription of the ~rawinqs . FigO 1 is a simplified plan view of a high speed dot matrix printer of a kind i.n which the descender printing system of the present invention may be incorporated to particu-lar advantage;
. FigO 2 is a detail sec~ional elevation view of a : ~ :, , .
~ part of the printer taken approximately along line 2-2 in . ~ ,~ . .
: Figs, 3A through 3K illustrate a numbex of dif~erent . characters, mostly descender characters, printed by the printer o Figs~ 1 and 2;
FigO 4 is a block diagram of a control system for the printer of FigsO 1 and 2, incorporating the control : elements of a descender printing s~stem constxucted in accordance : .: `with~one embodiment of the present invention; and :~: ~ Fig. 5 is a block diagram of a.preferred embodiment o~ the present i~vention~
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~L~ = IC~h~ ~z~ L~e~err~d ~'~m~o i.~n~nt~_ E~i.g~. 1 and 2 il:l.ustrate a high speed dot rnatri~
printer 10 in which -the descender character printiny systeM
of the present invention can be employed to substantial advantage; printer 10 produces characters in the dot matrix forms illustrated in Figs. 3~-3K. Printer 10 comprises a base 11 wi-th two vertical Erc~me members 12 and 13 a~fixed to itC
opposike sides. A pla-ten 14 ls m~unted upon a rotatable shaft 15 that extends between the two side frarne ~embers 1 10 and 13. A knob 16 is mounted on one end of shaft 15 to provide for manual rotation of platen 14.
Two carriage gui~le rails 17A and 17B are mounted at the front oE printer 10, extending t.ransversely of the prin-ter between Erame members 12 and 13, parallel to platen 14.
print head carriage 18 is slidably mounted on guide rail5 17A and 17B
and is connected to the ends o-E a carriage positioning belt 19. Preferably, belt 19 is a toothed belt of the kind known as a timing belt. The right hand side of belt 19 extends : around a drive sprocket 21 mounted upon a shaft 22 that ,~
projects upwardly from the printer base 11. The opposite side of belt 19 engages another sprocket 23 mounted upon a vertical shaft 24 at the left hand side of base 11.
The sprocket shaft 22 is connected to a pulley (not shownj that is engaged by.a drive belt 25~ Drive bel-t 25 ext~nds around a drive sprocXet 26 mounted upon the sha-Et of a reversible stepping motor 28 used as a carriage drive motor.
he carriage drive motor 28 is a re~ersible motor -that rotates thro~gh a discrete angle each time an electrical signal pulse s:applied to the motor windings. Printer 10 may include two 0 margin control switches 31 and 33 mounted on base 11 in , : ., ,, : , .
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position to be actuated by carriage 18 (E'ig. 2). Switch31 is located at the left-hand side of printer 10 and switch 33 is located at the right~hand side of the printer.
Printer 10 also includes a line feed motor 34 mounted in the rear left-hand corner of base 11. Motor 34 is a reversible stepping motor similar to the carriage drive motor 28. A drive connection is provided between motor 34 and platen 14, comprising a drive sprockek 35 mounted on the output shaft of motor 34 in engagement with a belt 36 that also engages a driven sprocket 37 mounted on platen ~haft 15.
~ roll of paper record sheet matarial 41 is mounted at the rear of the printer 10 (not shown)~ The paper record sheet 41 extends around the platen 14 as shown in Fig. 2, and under a bail bar 54 (Fig. 1) that maintains the paper in contact with the platen. The portion 42 of the record sheet 41 that projects upwardly from platen 14 (Fig. 2) is the portion on which data has previously been recorded by the printer.
; A plurality of prink head magnets 51 are mounted upon the print head carriage 18 (Figs. 1 and 2). In one typical construction, a total of saven print head magnets 51 : ' :
ara employed, as shown in Canadian Patent No. ~62,124, February ~` 4, 1975. Each of the print head magnets 51 affords a drive means for axial movement of an individual print rod 52.
Th~s ~nds of the print rods 52 terminate in a vertical arcuate array spaced a small, uniform distanca d from platen 14 ~FigO 2~ at a printing station 53 (Figr 1) that traverses the platen longitudinallx as the print head carxiage 18 moves alony the guide rails as described hereinafter.
It will be recognized that details of a number of the , ~ .
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mechanical linkages in printer 10 ~ave been omitted as unnecessary for an understanding of the present invention;
these may include a return spring for the return of print head carriage 18 to the le~t-hand margin o the printer and a clutch to release the carriage drive for a carriage return movement. The preferred construction for carriage 18, magnets 51, and print rods 52 is illustrated in detail in Ca~adian Patent No. 962,124, February 4, 1975 Impact-sensitive paper may be utilized as the recordiny sheet 41 in printer 10. On the other hand, in many applications this relatively e~pensive paper may not be deslrable. For such applications, printer 10 may be equipped with a ribbon 55 that extends through printing station 53 (Fig. 1) between platen 14 and the tip ends of print rods 52.
The ends o ribbon 55 are taken up on two spools 56 and 57.
If a ribbon is employed, an appropriate mechanism for advanc-ing ribbon 55 to present fresh lengths o~ the ribbon for successive imprints is incorporated in printer 10, but has not been shown in the drawings.
; 20 The basic construction fox printer 10, as described above, is already known in the art, so that only a brief description o~ the mechanical operation of the printer is necessary in this specification. Before printer 10 is placed - i .
'J in operation, as noted above, the paper record sheet 41 is extended around platen 14, between the platen and the outer ends of the print rods 52. The starting position for the print head carriage 18 is at ~e left-hand end o~ its travel on rails 17A,17B~ nearthe left-hand margin switch 310 For the first character to be imprinted, such as the character ', ~.,.
"P" illustrated in FigO 3A, carriage 18 advances a given \
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number oE discrete steps ~rom leEt to ricJh-t, the carr:ia~e being driven ~y its positioning beLt 19 throucJ'h -the drive affordecl by motor 28, drive belt 25, alld sproc'~et 21. In the illustrated ernbodimen-t, eig'ht discrete s-teps are used for each character. During the first three steps or incremental column movements o~ carriage 18, no impression is made on paper 41. In the next five steps of the carriage, a complete character is imprinted by selective actuation of prin-t rods 52. Of course, a differen-t format cou].d 'be employed, depending upon the requirements oE t'he symbols to be printed and other factors not critical to the present :invention.
As shown in Fig. 3A, -the initial advancing movement of carriage 18 leaves three blank columns 61, 62 and 63 preceding -the first printed character. In the next column 64~ all seven of the print rods 52 (shown a-t positions 52~-52G in Fig. 3A) are driven into impact with the record sheet, producing seven ver-tical dot impressions 59. On the ne~t incremental step 65 in the advancing movement of carriage 18, only two dot impressions 59 are formed~ one by print element 52A and the other by print rod 52D. This action is repeated in the next two columns 66 and 67. In the eiyhth step for : . , carrlage 18, the print rods 52B and S2C are actuated, producing dot impressions in the final column 68. This .: ~
results in the formation o~ the letter llp!' as illustrated in Fig. 3A. In~this'same manner, a complete line of data symbols letkers, numbers, or other symbols) is imprinted across the paper recorcl sheet 41 on platen 14, with carriage 18 moving from le~t to right (Fig. 1) a total of eight s-teps -Eor each ndividual symbol.
Figs. 3B through 3K illustrate additional characters , ::
10 ' -` ~ ` , `~' . ` ` ' ` ' ' ' , , ' ` I ' ' ~nd syI~ol~ that printex 10 ma~ be required to reproduce.
Flg. 3B illustrates -the lower case lette~ "p" as it would be reproduced by ~nown printers having no p~ovision ~or printing descender elements below -the hor:izon-tal print base line 80. This let-ter, .in the form shown in Fig. 3B, is not always recognizable, in ~ rapid scan, because i-t i5 not located in the usual positi.on. Descender characters printed in the manner illustrated by E'ig. 3B thus deyrade the readability of the printecl data~
E'igs. 3C through 3K il:Lustr~te various descencler characters as prin-ted by printer 10 when eqw.pped with the descender printing system of the present invenklon. To print these characters, the paper 41 (FigO 2) is advanced in the direction o:E the arrows A (Fiys. 2 and 3C) to realign the paper with the print head, so that the print elements 52 occupy the vertical positions 52A'-52G' as shown in Fig. 3C.
: With this realignment for descender printing, th~ base line .
80 on paper 41 is raised ahove the print rods at positions ~ ::
52F' and 52G'. Irhis makes possible the printing of all of : the descender characters (Fiys 3C-3K) with no need for additional print elements in printer 10~ The descender .
printing system is described in greater detail hereinafter.
At the end of any complete movement of eight column ;- increments for carriage 18, whether or nok that movement includes:prin.ting of a data symbol, the carriage may be retuxned to the left-hand limit of its travel to begin the ; : printing of.a new line of text on the paper 41. The carriage : return operation may be initiated by a carriage return code word in an input signal to control printer 10, or by engage-.ment of:carriage 1~ with the ri~ht hand limit switch 33.
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That is, switch 33 can be employecl to actua-te t'n~ carria~
return and line :Eeecl mechanis~s ~f pri.n-ter 10 on a manda-tor~
basis to return the carriaye to the ini.tia]. le:-t-ha.nd position for the beyinning of a new line and to feed t~e paper web 41 around platen 14. Before printiny o e a new line of text is initiated, the line ~eed drive motor 34 rotates platen 14 through a number of incremental steps, by means o the drive connection 35-37, ali.gning a :Er~h llne segment of the record sheet 41 with carriage 18. Other non-print function codes may be included in the received siynal to control other printer operations.
Fig. 4 ls a block diagram o:E a basic control s~stem 70 for printer 10, The input stage o control system 70 . comprises an inpu-t logic circuit 73 to which an input signal j~ is supplied, either from a keyboard .or from an in~ut transmission line. The output of logic circuit 73 comprises a series of data output circuits 74 and a load signal circuit .~ 75, all coupled to the input level o an input clata store 76.
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~ Data store 76 could be constructed with a single storaye level ~ . , for recording ~ust one code word representative o~ a single data symbol:or of a single non-print unction or the printer.
Preferably, however, data store 76 includes a plurality o~
storage levels, capable of recording a su~stantial number of ~.
1~ ~
:code words.
The output of data store 76 is coupled, by a plurality o data output circuits 77, to the input o a p~int control and character ge~erator unit 79. A print clock control , ~ , connection 78 is also provided, be-tween data store 76 and the~inpu-t of the prin-t control~character generator uni-t 79 , ~ 30 to affoxd a means for inter-relating the timing of unit 79 ~ ~ .
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oper~tions with thoqe in data sto~l 76. rrhere ~re seven output circuits 82 Erom unit 79 to a. print head driver circuit unit 81~ Th~ print head driver circui-ts 81, in turn, include an equal number of output circuits 80, individuall~ connec-ted to t-he print head maynets 51 of carriage 18.
The printer control system 70, Fig. 4, also includes appropriate non-print function detecto.r circuits incoxporated in a decoder circult unit 83. Each of the outputs 77 from data store 76 is connected to an inpuk or function decoder 83. Decoder 83 has a carriage re-turn output circuit 84 that is connected to the input o a carriage actuator unit 85.
The carriaye actuator unit 85 also receives a step signal input from the print control and character yenerator unit 79~ through a circuit ~6. Carriage actuator unit 85 has four outputs that are coupled to a set oE carriage driver circuits 87, in turn.coupled to the carriage drive motor 28.
The left-hand switch 31 and the xight-hand switch 33, if , present, are aLso connected to the carriage dxivex circuits 87. ~ .
: A line feed output 91 fxom the non~print function :
decode~ uni.t 83 is connect:ed to the input of a line feed actuator 920 Actuator 92 has four output circuits, connected through line feed driver circuits 93 to the line feed drive motox 34.
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Printer contxol 70, as-thus fax described, is :
genexally conventional in constxuction and organization~
-~ : An input signal including a sequence of code words repxe-: . .
sentati~e both of symbo~s to be printed and of non~print 30: ~ fuDctions for pxlnter 10 IFi~s. 1,2) is applied to the input ; i.:
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loyic c.ircuit 73 (]?ig. ~ rhc source o~ the input sicJnal may be ei.-ther a keyboard or a transrn:ission ].ine. Input logic circuit 73 detects the proper star-t-s-top sequence of the encoded data ancl converts -the data from serial to parallel form. For each received code word, a plurality o~
parallel ou-tput signal pulses and a load pulse are applied to the inpu-t of data store 76 to recorcl the code word in the data store. No other exte:rnal ope:rating sicJnals are re~uired for the lnput lo~ic 73 in normal operation of 5ystem 70.
Data s-tore 76 records each code word as received;
; the data store may be a convent.ional shift register memory with internal transfer between sequential storage levels, or a conventional RAM device. In eit~er case, it functions as a FIF0 storaye unit~
At the beyinning of each prin-t cycle, a print clock control signal is developed, and is applied to ~he print control logic circuits in unit 79 to activate internal timing logic t~at applies a column count signal to the integral character generator. The same print timing arrangement supplies a step timing signal to the carriage actuator 85, ~ .
through circuit 86. For a non-print code word, identified by the decoder circuits 83, the character generator in unit 79 is inhibited by an appropriate signal supplied -thereto through circuit 88.
Prlor to each cycle o~ the printer, the next code wo~d in~data store 76 is sampled by the decoder circuits .in unit 83. In this manner, carriage return and line feed codes are detected, producing suitable ~ontrol signals ~ ~supplied to carriage actuator 85 and line feed actuator 92 ::
~ 14 -~7~
for control of these printer operatio~s. The inputs to the carriage driver circuits 87 ~rom the carriage position sensing switches 31 and 33 are utilized for internal logic resetting functions. Thus, the basic operation of control system 70 is essentially similar to the system described in detail in Canadian Patent NOD 9~5,475, April 16, 1974, to which referencs may be made for further details of a practical printer control system.
Control syst~m 70, however, incorporates a descender contro~ logic unit 101 having a number of different inputs.
one input is the step signal, on line 86, from print control 79O ~nother input 102 to the descender control logic 101 is derived from a descender character decoder 103 coupled to the output of data store 76. ~nother input may be the line feed signal on line 91, derived from the non-print function decoder unit 83; the nor.mal line feed connection of line 91 to actuator 92 may be omitted. ~dditional inputs to logic unit 101 may be provided from other parts of the overall control system 70, depending upon the specific circuits utilized in the overall printer control. Descender control , 101 further includes two output circuits 105 and 106 connected to line fead actuator 92. Additional outputs for logic unit 101 may also be requirad. The output connections 105 and 106 are^ employed to supply a descender positioning signal and a ':
reset signal to the record sheet shift maans comprising line feed actuator 92, driving circuit~ 93~ line fead drive motor 34, and the ~ne chanical linkage 35-37 to the platen 14~
In operation, whenever a code word for a descender charactex is stored in the output of data store 76, this .
condition is detected by the descender detector 103, and an ~7~
output signal is applied to control 101 on line 102.
Control 101 supplles a descender posltloning signal to line feed actua-tor 92 to actuate the line feed driver circuits 93 and enercJize line feed drive motor 34. ~o-tor 34, throuyh the drive connection 35-37, rotates platen 14 throuyh one or more increments of movement, thereby advanclny record sheet 41 vertically to a position at which lowermos-t print elements 52 are below the base line 80 (Fig~ 3C). In a typical s~stem, the paper record sheet 41 is advancecl by a distance L precise~ly equal to the total heiyht oE two of the printing row incremen-ts represented by the dots 59. This applies to a 5 x 7 matrix format as shown in E'igs 3A-3K. For any ma-trix of n vertical printiny elements, printing in a format of m x n, where m is the number of column increments, the distance h is equal to vertical row increments, and ~ is substantially smaller than n. With a 7 x 9 format it may be desirable -to shift paper 41 thxough a vertical distance L equal to the height of three , ~ print dots to achieve the best proportions between descender :
and non-descender characters. Thus/ n = 9 and _ = 7; for this ~ ~20 format ~ - 3.
`~ Subse~uently, when printin~ o a descender character is complete, a reset signal is generated in control unit 101 and supplied to line feed actuator 92 to again actuate the record sheet shift mechanism and move the record sheet 41 back into its original printing position for printing of the next character in the text. Reset ma~ be triggered by thé~step signal (line 86) for the next character. OE course, reset should not be effected if the next character is a , descender character; in such circumstance, the reset is ; precluded by a new descender character identification signal , ,, .
from cl~cocler 103. In this manner, the ~ext contilluity is maintain~d and the format of -the pr:inted -text :is pre.served as s'hown in Figs. 3C-3:K.
As will be apparent from -the foregoiny clescription, the addition of the descender printing s~stem comprising logic control unit 101 ancl its connections to contxol s~s-tem 70 ~Fiy. 4) does no-t in-terfere with normal continuous opera-tion of the printer and does not in'hibit the speed of continuous operation, provided platen 14 can ~e rapidly shifted to move paper ~1 to and from the posi.-tion re~uired to print the descender cllaracters (Figs. 3C-3~). With a large platen, however, this requirement.becomes difficult or even impossible to achieve in an economically feasible printer. Platen 14 should be small in diameter and light . in weight to allow motor 34 to shift the platen between its descender and non-descendex printing positions within less than three and pref.erably less than one column step inter~al.
For a tan-charac-ter-per-secon~ machine, using a 5 x 7 format with 8 columns per character, as shown, this is a shift.
: ~ .
' 20 interval t of 0.0125 second or less. For a 30 cps printer, the shift interval is preferably ~00417 second or less.
~ :
of course, the diameter of platen 14 cannot be reduced ndefinitely; the platen diameter D must exceed the overall helght EI of the dot matri~ format (see Fig. 2).' A good :working relation~ keeping t'he platen diameter to a minimum size, is to maintain . 6H'-,~ D ~ 2H.
;~ :
With the descender printing system o~ the invention, there is :no distort.ion or disturbance in the prin-ted text and the ~control is fully automatic, requiring no mechanical changes . : .
:
f~ 17 -. .
~3'7~
in -the pxinter. The log:i.c un.il 101 can be full~ constructed from solicl sl;ate circ-~itry, and hence :is quite capable o~' lon~--term opera-tl.on with little or no specia]. maintenance or expense, and is xelatively simple and economic in construc-tion.
For some composite characters, such as -the fractions shown in Figs. 3J and 3K, a part of the character may appear in the uppermost rows of the stancLard format and a partl~ay extend .into the bottom rows of the descender format. These composite characters can be printed accurately if the transition time between normal and descender printiny positions, for record sheet ~1, is made sub5tantially less than the time required to advance the platen horizonta].ly by one column increment, since the actual pxinting stroke of the print rods 52 is only a minor fraction of the total column ~` time. Of course, the characters must be limited to dots, .
in each column, in only as many adjacent vertical row positions :
as there are print rods 52.
Specific circuitry to implement the addition of descender control 101 and desc~nder decoder 103 to control system 70 may be relativeIy simple. Decoder 103 is a conventional circuit constructed to identify those received code words representative of the descender characters and to supply appropriate identification signals -to control l01.
A series o A~D gates and NOR gates, appropriate to the transmission code, will suf~ice.
CorltroL 101 may be cons-tructed in TTL logic in a manner~essentially similar to the logic circuits disclosed in ~he text display system of U~S~ Patent No. 3,8~4,395, .
~ 30 makiny due allowance for different input signals and for -the : ~
,~ ~: ~: , ;:
~(~7~
O nece.ssity for rapicl ~ctuation of the platen throuyh a small distance :instead o the delay~d cactuation through a much larger distanc~ as provided in that patent~ The text , ~/,.S, . display of~Pat~nt NoO 30844, 395 and the descender p:rinting system of the present invention can be read:ily combined in a given printer.
Fig. 5 illustrates, in block diayram forrn, a general printer control system :L50 incorporatiny a pre~errecl embodimen-t of the present invention. The transmission line input stage 73' of system 150 includes a line interface circuit 151 to which a telegraph input signal is supplied on line 152~ The input signal may be encoded in accordance with the standard eleven-unit ASCII code or the conventional se~en and one-half unit Baudot code; other permutation codes can be employed with appropriate modifications in the control system to interpret the codeO
; ~ ~ The output of line relay 151 is connected to à
uni~ersal asynchronous receive/transmit (UART) lnput-output . logic circuit 153~ For example, U~RT circuit 153 may comprise a MOS/LSI unit as manufactured b~ SMC Microsystems Corporation, Model COM2502/~I or COM2017/~I, suitably programmed for data woxd length, parity mode and number of stop bits to conform to the requirements oE the data input signal supplied -Erom line 152 through inter~ace circuit 151. ~ basic timing signal is supplied to the UART circuit 153 from a crystal-controlled , :. ~ : - : . . - ;
oscillator 154v - The UART device 153 has a data output connectio~
155 to a main control logic unit 157; there is also a control .output 156 from the main control logic unit back to U~T
device 153. Unit 157 comprises a rniniprocessor or ~ o~
micro~ornputer ac; a central ~rocesC;iny unit (CPU), ~ith suitable auxi.Liary circuits sucll as an lnpu-t MuLtiplexer and output registers, progra~ned to carry out the descender print control operations of the present invention as well as the many other functions necessary to control printer 10.
The main logic unit 157 has outpwt and input connections 158 and 159 to a character yenerator 161O Chaxacter generator 161 ma~ be O:e conventional construction; for ex~mple, the character gençrator may compx:ise two type 8316 read-onl~
memory (ROM) devices proyra~med in accordanc~ with the de.sired type font and input data codeO There is also a local data input circuit 162 to logic unit 157 from a ke~board 163, ~or local operation of prin-ter 10 and for transmission-mode operation of the printex.
Control system 150 includes a fi,rst-in first-out (FIFO) input storage register 76. Storage registex 76 has an input connection 1~5 from logic unit 157 and' an output circuit 166 back to the main logic unitO A conventional shi-Et ~ ~ .
~, register may be emplo~ed Eor device 76; as illustrated, ~:~ ; 20 howeverO storage registér 76 is a random access memory (RAM) programmed for ~IFO operation. ~y way of example, storage , . .
register 76 may comprise two type 2112 RAM devices~
The:main lo~ic unit 157 has an output 168 to a : .
single-column storage register 167 in turn'connected to the ,print~head driver circuits 81. 5tore 167 afEords se~en output :` circuits, one for each of the printing rods 52 of printer!l0 (FigO 1), each output is individually connectcd to one of ' :: seven print magnet driver circuits in unit 81. Each print : magnet driver clrcuit is connected to an individual magnet , 30 or soIenoid 51 for actuating one of the print rods 52 (see FigO 1).
i - 20 -.i : ...................... .
,: ~ . ,, . . :
O ~not~r ou-tput 173 fronl the ma:irl corltrol :Loyic un:it 157 extends to a stcpper motor store 17~. T~le store 174 includes a carriage motor storage register connected ~y an output 175 to the carriage motor driver circuits 87 and a line feed storaye reyister connected b~ an output 177 to the line feed motor driver circuits 93~ The carriage motor driver unit 87 has four outputs individually connectcd to ~our motor windings in the carriaye dxive step motor 2~. Siynals from dxiver unit 87 to motor 28 determine khe directi.on o-~ rotation of the motor and control the number o~ steps through which the carxiaye drive motor is driven in any yiven operational sequence~
Similarly, four outputs from the line ~eed motor driver unit 93 to line feed motor 34 supply actuatiny signals to the line eed motor to drive shaft 15 and platen 14, clockwise or counterclockwise, through oxdinary line feed operations, : descender print operations, and any other operations requiring platen rotationO
~ n considering the general operation of control system 150, it may first be assumed that printer 10 is ~eing operated as a receiver responsive to an input signal supplied . to the UART circuit~153 ~xom line 152 through interface circuit 1510 In the UART circuit, each received code word . is converted from series to parallel form and transmitted to the~main cont.rol logic unit 157 as generally indicated by ne 1550 The overall synchronization of operation~ in control system 150 is ef~ected by clock signals from :, : : ~ .
osclllator 154 0 .
The main logic control unit 157 records -the received data .in the input storage reg.ister 164. The recorded : 30 .code words are read from R~M 164 by the main contro]. logic ~", ~
:f ` ~ , .
,.: '. . ' ., ', . ' . . ' ' . . ' '. .
~7~
un.it 157 and supplied to character cJeneratox 16L, which inter-prets eclch code woxd with respect to machine function and supplies machine contro:L slgnals back to the main control loyic unitO ROM 161 also stores the proyrarn for the mini-processor of logic unit 157~ For the printing o an~
individual character, print ~nac~neL- control signals based on the signals from character yenexator 1.61 are supplied ~y the main control logic 157 to store 1.67, in the appropriate se~uence, and then applied to the print magnet drivers 81 for selec-tive eneryization of the pxint maynets 51. Steppiny of the print head 18 through the required sequence of column steps for reproduction of each charactex is effected by stepping signaIs supplied to store 174 from logic unit 157 and applied to motor 28 through the carriage motor driver .
unit 870 Wehnever a code word fox a descender character is read from RAM 76 and decoded in charactex yenerator 161, appropriate signals are supplied from.the m~ln logic uni-t 157 to stepper motor store to actuate line feed driver ~mit 93 and cause motor 3~ to step platen 14 and shift the record sheet 42 upwardLy a distance L of ~ row increments (FigO 2~.
Th-ls, or printing a descender character, the record sheet in ~he printer is shifted to the descender print position (see FigO 3C). If the next code word decoded in character generator 161 is another descender character, the platen and :
. record sheet remain in the.descender print position. If the : next code word is a regular character (not a descender-charactex), in the next print cycle the record sheet.42 is : :shi~ted back downwardly through distance L ~FigsO 2,3) from the descender print position to the normal print position~
i ~ - 22 -.
The descender decoder 103 and descender l.ogic control 101 of Fig. 4 are thus incorporated in the main logic control unit 157 in the preferred embodiment of Fig. 5.
For a detailed disclosure of suitable operating circuits for the miniprocessor embodiment of Fig. 5, including an operating program for logic unit 157t reference may be made to the comprehensive disclosure in U.S~ Patent No. 3,990,559, ~ovember 9, 1976. In that disclosure, the miniprocessor for logic unit 157 comprises a type 8008 CPU; other mini-processor devicest such as the type 8080, can also be employed.
FOr operation of printer 10 with control system 150 as a transmitter, an illpU't signal is supplied from keyboar~
163 to the main control logic unit 157. Operation of the prinker proceeds in the same manner as described above^ the code words of the input signal are recorded se$uentially in RAM 76 and read out in the same sequence for pri.nter actuation.
The signals from key~oard 163 are also supplied fxom loyic unit 157 to UART 153 and from UART 153 to a transmission line 181 ; through a relay transmitter circuit 182.
: 20 The descender pri~ting system of the invention often requires no modification of the :-.~echanical portion of ~: the printer, in a machine ha~ing a small, low-iner~ia platen and having a reversible stepping motor or liXe reversible dri~e used for line feed. The drive ratio betwee~ the line . -feed motor c~d the platen may require some adjustment to . ~ assure movement of platen 14 thro~gh the desired distance L
in an integral number of steps of motor 34, but this can be readily accomplished by appropriate selection of sprockets 35 and 370 The descender printing system has been successfully app:lied to pr.inters operating at print rates well above 30 cps with clear, sharp copy resultincJO ~lthoucJh de.~,cribed in connection with a printer using mechanica:L impact print ele.ments (rods 52), the me-thod and control appara-tus of the invention may also be utilized in a pri.nter employincJ thermal printing elementsO
. , , .
.:, .
, :
. ~ , i '~: .
~' ~ 20 , ::
:~
.:
. ::
~ 30 , ~ . , , . , . , -, , : .. . . .
, . . .
Claims (7)
1. In a dot matrix printer of the kind comprising a print head, including a plurality of print elements disposed in a vertical array, for printing characters on a record sheet supported upon a platen in a format m x n of m horizontal column increments and n vertical row increments, a carriage for moving the print head across the record sheet in a horizontal pointing direction with the lowermost printing element normally aligned with a horizontal base print line on the record sheet, and control means, including a FIFO
input store, for actuating the print elements and the carriage in response to a received signal including a series of code words representative of characters to be printed and of other functions of the printer, the improvement comprising:
descender decoder means for decoding code words representative of descender characters that include descender components to be located below the base print line, prior to printing;
descender shift means, coupled to the descender decoder means, for shifting the record sheet upwardly through a distance L equal to p row increments, from a normal print position to a descender print position, thereby aligning print elements below the base print line for printing each descender character, where p<n;
and shift reset means, included in the descender shift means, for shifting the record sheet downwardly through distance L from the descender print position to the normal print position, after completion of printing of a descender character, to permit printing a subsequent character entirely above the base line.
input store, for actuating the print elements and the carriage in response to a received signal including a series of code words representative of characters to be printed and of other functions of the printer, the improvement comprising:
descender decoder means for decoding code words representative of descender characters that include descender components to be located below the base print line, prior to printing;
descender shift means, coupled to the descender decoder means, for shifting the record sheet upwardly through a distance L equal to p row increments, from a normal print position to a descender print position, thereby aligning print elements below the base print line for printing each descender character, where p<n;
and shift reset means, included in the descender shift means, for shifting the record sheet downwardly through distance L from the descender print position to the normal print position, after completion of printing of a descender character, to permit printing a subsequent character entirely above the base line.
2. A dot matrix printer, according to Claim 1, including a line feed mechanism for advancing the record sheet upwardly by a given integral number of line feed increments to present a fresh line segment of the record sheet for recording a new line, in which the descender shift means is coupled to the line feed mechanism, and in which the distance L is equal to an integral number of line feed increments substantially smaller than the number of increments employed for a line feed movement.
3. A dot matrix printer according to Claim 2 in which the line feed mechanism comprises a reversible stepping motor.
4. A dot matrix printer according to Claim 1 in which the platen diameter D is within the range 6H > D > 2H, where H is the overall height of the printing element array.
5. A dot matrix printer according to Claim 4 in which there are just n print elements, in which the carriage moves through a plurality of column steps in printing each character, and in which the transition time between the normal and descender print positions is substantially less than the time required to move the platen horizontally by one column step.
6. The method of printing, utilizing a dot matrix printer of the kind comprising a print head including a plurality of print elements disposed in a vertical array, for printing characters on a record sheet supported upon cylindrical platen in a format m x n of m column increments and n row increments, a carriage for moving the print head across the record sheet in a horizontal printing direction with the lowermost printing element normally aligned with a horizontal base print line on the record sheet, and control means, including a FIFO input store, for actuating the print elements and the carriage in response to a received signal including a series of code words representative of characters to be printed and of other functions of the printer, comprising the following steps:
A. monitoring the code words to detect each code word representative of a descender character that includes a descender component to be located below the base print line, prior to printing;
B. shifting the record sheet upwardly through a distance L equal to p row increments, from a normal print position to a descender print position, to align p print elements of the print head below the base print line for printing each descender character, where p < n; and C. shifting the record sheet downwardly through distance L from the descender print position to the normal print position, after completion of printing of a descender character, to permit printing a subsequent character entirely above the base line.
A. monitoring the code words to detect each code word representative of a descender character that includes a descender component to be located below the base print line, prior to printing;
B. shifting the record sheet upwardly through a distance L equal to p row increments, from a normal print position to a descender print position, to align p print elements of the print head below the base print line for printing each descender character, where p < n; and C. shifting the record sheet downwardly through distance L from the descender print position to the normal print position, after completion of printing of a descender character, to permit printing a subsequent character entirely above the base line.
7. The method of printing, according to claim 6, utilizing a printer which includes a line feed mechanism connected to the platen and a line feed actuator for controlling actuation of the line feed mechanism, for advancing the record sheet upwardly by a given integral number of line feed increments to present a fresh line segment of the record sheet for recording a new line, in which the line feed mechanism is employed to perform steps B and C, and in which the distance L is equal to an integral number of line feed increments.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/675,566 US4037705A (en) | 1975-10-20 | 1976-04-09 | Descender printing system for dot matrix printer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1074181A true CA1074181A (en) | 1980-03-25 |
Family
ID=24711047
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA269,613A Expired CA1074181A (en) | 1976-04-09 | 1977-01-13 | Descender printing system for dot matrix printer |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS52125028A (en) |
| AU (1) | AU499703B2 (en) |
| CA (1) | CA1074181A (en) |
| DE (1) | DE2715792C3 (en) |
| FR (1) | FR2347198A1 (en) |
| GB (1) | GB1566024A (en) |
| IT (1) | IT1077965B (en) |
| NL (1) | NL7701341A (en) |
| SE (1) | SE7700339L (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5520523A (en) * | 1978-07-28 | 1980-02-14 | Toshiba Corp | Processing system for underline printing |
| JPS5845068A (en) * | 1981-09-10 | 1983-03-16 | Tokyo Electric Co Ltd | Dot type printer |
| US4721401A (en) * | 1986-10-14 | 1988-01-26 | International Business Machines Corporation | Printhead control |
| US5121688A (en) * | 1988-08-19 | 1992-06-16 | Presstek, Inc. | Spark-discharge recording head with position sensor and control for imaging lithographic printing plates |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3565229A (en) * | 1968-06-17 | 1971-02-23 | Music Reprographics Ltd | Line spacing means for music typewriters |
| US3627096A (en) * | 1969-04-25 | 1971-12-14 | Ibm | Wire printing method |
| DE2108006C3 (en) * | 1971-02-19 | 1974-12-12 | Walther-Bueromaschinen Gmbh, 7921 Gerstetten | Mosaic wire print head |
| BE795861A (en) * | 1972-02-25 | 1973-08-23 | Xerox Corp | PAPER DISPENSER SYSTEM FOR HIGH SPEED PRINTING MACHINE |
| JPS566032B2 (en) * | 1973-07-05 | 1981-02-09 | ||
| JPS5117812A (en) * | 1974-07-31 | 1976-02-13 | Matsushita Electric Ind Co Ltd | INJISOCHI |
-
1977
- 1977-01-13 SE SE7700339A patent/SE7700339L/en unknown
- 1977-01-13 CA CA269,613A patent/CA1074181A/en not_active Expired
- 1977-01-14 AU AU21326/77A patent/AU499703B2/en not_active Expired
- 1977-01-27 IT IT47817/77A patent/IT1077965B/en active
- 1977-01-28 GB GB3702/77A patent/GB1566024A/en not_active Expired
- 1977-01-31 FR FR7702660A patent/FR2347198A1/en not_active Withdrawn
- 1977-02-09 NL NL7701341A patent/NL7701341A/en not_active Application Discontinuation
- 1977-04-07 DE DE2715792A patent/DE2715792C3/en not_active Expired
- 1977-04-08 JP JP3961177A patent/JPS52125028A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB1566024A (en) | 1980-04-30 |
| JPS52125028A (en) | 1977-10-20 |
| DE2715792B2 (en) | 1980-05-22 |
| IT1077965B (en) | 1985-05-08 |
| DE2715792C3 (en) | 1981-01-29 |
| NL7701341A (en) | 1977-10-11 |
| FR2347198A1 (en) | 1977-11-04 |
| SE7700339L (en) | 1977-10-10 |
| DE2715792A1 (en) | 1977-10-27 |
| AU2132677A (en) | 1978-07-20 |
| AU499703B2 (en) | 1979-04-26 |
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