US3838250A

US3838250A - Control for a matrix printing assembly

Info

Publication number: US3838250A
Application number: US00321177A
Authority: US
Inventors: D Nesbitt; H Naas; J Sutherland
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1973-01-05
Filing date: 1973-01-05
Publication date: 1974-09-24
Anticipated expiration: 1991-09-24
Also published as: JPS49103534A; GB1459816A; FR2213170A1; JPS5637589B2; DE2400444A1; CA1022466A; IT1006738B; NL7317440A; DE2400444C2; FR2213170B3

Abstract

A control for a matrix printing assembly to determine the character and spacing thereof in a data terminal comprising the combination of a mechanical linear strobe and an electronic timing circuit accurately controlling and positioning the stroke of each rod or stylus of the matrix printer.

Description

United States Patent 1 1 1111 3,838,250

Naas et al. Sept. 24, 1974 CONTROL FOR A MATRIX PRINTING 3,356,021 12/1967 May et al. 235/619 R ASSEMBLY 23328 2/1332]; Perkins et a]. 197/187 Inventors: g g f- N f g gm la g 3:703:94) 11/1972 Howard etal. 197/19 u eran; ae esl, 0 f8 kl 11 f l'f. o e ey a 0 Cal Primary ExaminerStuart N. Hecker Asslgneer The Smger p y, New York, Attorney, Agent, or Firm-E. L. Bell; 1. R. Dwyer; A.

W. Kozak [22] Filed: Jan. 5, 1973 [21] Appl. N0.: 321,177 57 ABSTRACT A control for a matrix printing assembly to determine 235/61'9 197/187 the character and spacing thereof in a data terminal [581 d 9 comprising the combination of a mechanical linear le 0 earc 5/6] 6 1 9 strobe and an electronic timing circuit accurately controlling and positioning the stroke of each rod or sty- [56] References Cited lus of the matrix printer.

UNITED STATES PATENTS Allen 197/19 15 Claims, 10 Drawing Figures Pmamanww 3.838.250

SHEEIZOF 7 b Me 645 7 7 K c 2 66a If: (a v s- 12-1 n |:1 n u n LEFT mo one mam 69 HOME FRUIT new POSITION PRmr new HOME P05|T|0N LEFT mam" Posmoea CHANNEL on v I c or? 1 F cmuua. on

CHAUUEL O Lmmmue STOP mun-me wk,

CONTROL FOR A MATRIX PRINTING ASSEMBLY CROSS-REFERENCES TO RELATED APPLICATIONS US. application entitled A data Terminal With Dual Three-Station Printing" of Howard R. Cederberg and Charles W. Wiedeman, filed Jan. 5, 1973 as Ser. No. 321,176; and U.S. application entitled An Assembly for Spooling an Audit Trail in a Data Terminal of James G. Savage and Arnold L. Hawkins, filed Jan. 5, 1973, as Ser. No. 321,196.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to the means for positioning and controlling a matrix type printer and is particularly directed to the means of positioning and controlling a matrix printer in data terminals commonly known as electronic cash registers.

2. Description of the Prior Art Conventional matrix printers have a plurality of wires, each individually moved by a magnetic actuator, usually against a return spring, to impact a record medium to print a character, one wire imprinting one spot or dot of the character at a time. Such matrix printers use either seven or 35 such wires positioned in aligned configuration at the point of impact and are individually and sequentially strobed so as to print the character.

Heretofore, the strobing of each wire, the positioning of the entire character on the media, and the spacing between characters to form lines and columns of printed matter have been effected by electronic circuitry, usually timing devices or counters of some type. Unfortunately, however, experience has shown that reliance upon electronic circuitry, alone, has not been satisfactory and skewing of the printed characters, especially columns of printed matter, has resulted.

SUMMARY OF THE INVENTION This invention combines the mechanical and electronic aspects of a linear strobe bar and electronic circuitry cooperating in combination to precisely position and print characters on a record media for a point-ofsale data terminal. The linear strobe bar, accurately positioned on the data terminal, contains a plurality of slots of a selected size and location which cooperate with sensing devices movable with the matrix printer of the data terminal so that as the printer moves transverse the recording media, the sensing devices, according to the selected slot and required character, enable the electronic circuitry to strobe the wires of the matrix printers to print the character as required by the input to the data terminal. The circuitry and slots on the mechanical strobe bar are designed to provide a correct spacing of the characters for the appropriate rows and columns to be printed on the record media as the latters drive incrementally moves the media in the data terminal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a portion of a data terminal skeletonized and with the cover removed to illustrate the carriage for the matrix printers with the linear strobe bar positioned to position and control the spacing of the characters in rows and columns on the record media;

FIG. 2 is a schematized exploded view of the sensing devices mounted to move with the carriage relative to the linear strobe bar;

FIG. 3A is a plan view of the strobe bar enlarged as compared to FIG. 2 to show the details thereof;

FIG. 3B is a timing diagram for each of the light sensors in relation to the linear strobe bar channels;

FIG. 4 is a schematic spacing and timing sketch illustrating the 9 X 7 printing matrix and nonprint space.

FIGS. 5A and 5B are simplified block diagrams of the electronic circuitry which coordinates with the linear strobe bar and enables the printout on paper media regardless of direction of carriage motion.

FIGS. 6A, 6B, and 6C illustrate various logic and timing functions of the system.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, the data terminal 10 (with cover removed for purposes of clarity) is shown as comprising, overall, a carriage l2 movable laterally with respect to a frame 14, a work level surface 16 having three

print stations

18, 20 and 22, and an appropriate keyboard 24. The three

print stations

18, 20 and 22 are, respectively, a receipt station where the customers receipt is printed (if a receipt is required), an audit station where the storekeepers record (audit trail) of all transactions are printed, and a form station where the customers order form or bill of sale is printed, if required.

By this arrangement, the carriage 12, will move, not only from the printing position shown, viz., at the audit station and receipt station, but to the form station and audit station as well as traversing each pair of stations so that appropriate rows and columns of data entered into the data terminal at the keyboard 24 is appropriately printed out. The carriage 12 is mounted on a pair of bars 26 and 28 to hold the carriage in parallel relationship with the platen 16 and the rest of the data terminal and transverse movement on the parallel bars is accomplished by a suitable drive mechanism 30 including a belt 32, attached to carriage 12, and pulley means 34 motivated by a reversible motor (not shown).

In the embodiment shown, a receipt 36, if required, is printed in the receipt station 18 and an audit trail 38 is printed in the audit station 20 when the carriage 12 is in the position shown as the two record media (paper) are moved forward, i.e., in thhe direction of the keyboard 24, and forms a suitable supply, such as a roll of paper, by a suitable roller feed mechanism 40 driven by a motor and clutch means 42 coupled to shaft 44. When the carriage 12 is positioned to the left from that shown, a form 46, such as a customer order form or bill of sale, is printed in station 22 at the same time the audit trail 38 is being printed.

The audit trail 38 is rolled onto a spool 48 partially shown in FIG. 1, while the receipt 36 is severed, when a complete transaction is recorded, by a suitable cutting mechanism, indicated in its entirety as 49. Also, the forms station is provided with a pair of electronic sensing means 50 and 52 which determine when a form 46 is properly located in the forms station, otherwise the terminal is inhibited from operating; suitable electronics being provided for this purpose. Rollers 54 feed the form in a direction opposite from the direction of travel of the audit trail by suitable gearing to couple the rollers to shaft 42 which moves the form and audit trail or audit trail and receipt, or an audit trail alone, as the case may be, incrementally, in response to and in combination with printing mechanisms to form rows and columns of data as determined by the input to the keyboard 24.

The carriage 12 is also provided with a pair of matrix printers 56 and 58 capable of printing on two of the three stations at the same time, viz., the receipt station and the audit station, or (when the carriage is positioned to the left from that shown) on the form station and audit station.

Suitable ink supply means for the dual matrix printer are located in the carriage and are shown in FIG. 1 only schematically, since the ribbon, its novel inking supply arrangement and other details to improve the operation of the matrix printers and data terminals generally are described and claimed in a copending application. It should be remembered that the matrix printers 56 and 58 are capable of printing an audit trail and 'a receipt, an audit trail alone or on a form, an audit trail depending upon the mode determined in the keyboard 24. The proper positioning and printing of the characters in rows and columns is dependent upon the combination of a mechanical strobe means 60 and electronic circuitry which cooperates therewith and it is this combination that will be described in detail hereinafter.

It should be noted at this time, however, that one of the many advantages of matrix printers in the data terminal is the ability to print legibly through several copies of forms in the form station and, also, by suitable electronics described and claimed in the this application, supra, the printing on the receipt is upside down relative to the printing on the audit trail and form. This upside down printing on the receipt enables the complete transaction, such as a sale, to be recorded and totaled in the manner in which any transaction is normally read, i.e., top to bottom, for the benefit of the customer. This is also true of the form printed at the form station since the form moves in a direction opposite to the direction of travel of the receipt. This is not true, however, for the printing on the audit trail, which is stored in the machine to be used by the vendor.

As will be seen in FIG. 1, the mechanical positioning means in the embodiment shown is the linear strobe mask or bar 60 which is affixed to the frame 14 of the data terminal and is further illustrated in FIG. 3A in a much enlarged form over that shown in FIG. 1 for purposes of clarity. The linear strobe 60 comprises a relatively thin, long, flat plate containing a plurality of apertures for slots through which sensing device such as phototransistors, LED's (light emitting diodes) or the like are provided to detect the absence or presence of a slot or aperture as the carriage 12 moves back and forth across the carriage bars carrying the sensing device along with it.

Referring to FIG. 3A, it will be seen that the linear strobe bar 60 is made of three horizontal areas or channels of slots or apertures. The topmost channel, channel C, has a long slot 61, at the center and a long slot 62, at the right. The middle channel, channel B, has long slots 63,, at the left and 64,, at the center. The lowermost channel, channel A, has a slot 65,, at the left, a slot 67,, in the center, and a slot 69,, at the right. Between 65,, and 67,, there is a series of small slots 66,, which comprise 32 equally spaced slots. A similar series of 32 slots which are designated 68,, also appear between the larger slots 67,, and 69,, of channel A.

Referring to FIG. 2, it will be seen that the carriage 12 carries with it a group of sensing

devices

102, 104, 106, and 102', 104', and 106 which comprise a group of light emitters and light sensors which are aligned with the channels A, B, and C of the linear strobe bar 60. As the carriage moves to the left and right along the linear strobe bar 60, the attached

light sensing devices

102, 104, 106 and 102, 104', and 106' will convey a group of signals depending upon the location of the carriage along the linear strobe bar 60. Thus, a means has been provided by which the carriage position in relationship to the linear strobe bar may be determined at any given time.

Certain indexing or HOME positions have been provided and these have been designated as the left- HOME position 70, the mid-HOME position 72, and the right-HOME position 74 which are used to provide certain indexing and other information when the dual matrix head carriage is located in one of these three positions.

Between the left and mid HOME positions and 7 2, there is a left print field 71 which allows space for the printing of 30 characters or spaces. Likewise, between the mid-HOME position 72 and the right-HOME position 74, there is provided a print field-right 73 which provides for spaces permitting the printing of 30 characters or spaces.

Referring to FIG. 3B, which illustrates the resultant effect of the motion of the sensing devices of the carriage as they move across the linear strobe bar 60, it will be seen that as the light sensors 102 and 102' traverse the linear strobe 60 from left to right, then channel C will show that there is no positive or photosensitive output on channel C except for the area of the mid position and the area of the

right HOME position

72 and 74.

Likewise, referring to the situation in regard to channel B where the sensing emitters and sensors 104 and 104' traverse this channel, it will be seen from FIG. 3B that channel B is in the On or photosensitive position at the left-HOME position 70, after which it turns off until it reaches the mid-HOME position 72 and again turns off and remains in a normal Off" position.

In regard to channel A of the linear strobe bar 60 which is scanned by sensing emitters and receivers 106 and 106', it will be seen that the light sensing devices are On for a portion of the left-HOME position after which they are turned off until they are again turned On at a portion of the mid-HOME position 72 and then remain off until they are again turned On" at the portion of the strobe bar at the right-HOME position 74.

As a resultof the combination of these events of carriage motion in relationship to the linear probe bar 60, it will be seen that certain definitions can be made from the condition of the light sensing devices, namely, that of the left HOME being defined as channel A on, channel B on, and channel, C off; the mid-HOME can be defined as all channels A and B and C, being on;" and the right-HOME can be defined as channel A on, channel C on, and channel B off; further, the print field can be designated as the situation where both channel B is off and channel C is off, while the strobe slots 66,, or 68,, provide strobe on pulses as the carriage and sensors move transversely.

As will be seen in FIG. 3B in regard to channel A, the 32 small slots 66,, (print field 71) or the 32 slots of 68,, (print field 73) will cause a series of sharp on/off pulses to occur along specified portions of channel A. These pulses are called character strobe pulses and provide as follows: when channel B is off and channel C is off, but channel A comes On, then there occurs the initiation of a space and time period which will permit the printing of an individual character, as will later be seen in connection with FIG. 4.

Thus, there has been provided a dual matrix head assembly mounted on a carriage positioned to move left and right across the face of a linear strobe bar. Light sensing means attached to the carriage and working in conjunction with the slots and apertures provided in the linear strobe bar provide sensing signals which tell the electronic circuitry the position of the carriage the areas in which the carriage may stop, and the time and space positions in which it is permissible to print data on the printout paper media.

In order to better understand the requirements of the electronic circuitry in relationship to the printing mechanism, it should be understood that each of the dual matrix heads are composed of seven wire rods or styli which can be actuated electromagnetically by means of output signals from a latch circuit 93 (FIG. 5).

The arrangement of the printable character head is such as that may be described as a nine by seven (9 X 7) matrix. As will be seen in FIG. 4, there is shown a matrix arrangement whereby there is pictured seven rows, each of which are spaced or separated by a distance L. Further, the matrix then further consists of nine columns which are separated by spaces equal to L/2; thus, there is provided a matrix of seven rows each separated by a space L and a series of nine columns, each separated by a space L/2 so as to provide the capability of the matrix dot printer which is programmed to print numerals and/or letters and having the capability of simulating curved areas.

Referring to FIG. 4, the space allowable for a single individual character comprises 14 columns of which the first 9 columns are used for printing the wire matrix heads while the remaining 5 columns constitute a noprint area to provide spacing between individual characters.

The strobe pulses derived from the slots 66,, or 68,, (of FIG. 3A) are used to electronically define the start and finish of each individual character space. The trailing edge of the strobe pulse (FIG. 4) is used to signal the end of one character space and the beginning of the next character space.

As will be discussed later, two alternate timing signals (15,, and qb (FIG. 4) are used to alternately enable" the activation of the first matrix head printer group and the second matrix head printer group during each individual column count of the first nine (print) columns.

Thus, there is the requirement for information to be delivered to the seven wires of each of the two matrix heads as to whether or not they should activate to imprint a dot pattern or not at any given position of the nine columns involved. Further, since there are nine sequentially printed columns involved in the format of which column of a given character matrix is available for printing and which of the seven-wire matrix heads are to be activated for that particular one column of the nine columns that constitute the character matrix.

As was previously discussed in FIG. 3A, the left print field 71 and the right field 73 of sections of the linear strobe bar are provided with thirty-two slots or apertures, each for purposes of locating the spaces and columns under which the printing of each individual character will take place on one or more of the record media. As was heretofore indicated, attempts to print columns of characters utilizing electronic circuitry alone for locating and columnizing the print characters has often resulted in skewed columns, especially on long tape runs. The present solution to the problem of skewed columns is considered to be a major improvement as provided for by this particular invention. Further, the problem of useless or wasted carriage return time has now been eliminated so that carriage motion in either direction is always utilized for printing.

In regard to the combination of the mechanical locating mask (linear strobe bar 60) and the inter-relating electronic circuitry to operate the matrix print heads, the 32 slots of the slot sets 66,, and 68,, precisely locate the columns into which any given character is to be printed, since the print heads will not be free to print unless the conditions of FIG. 3B are fulfilled such that the sensing devices of channel C are off, those of channel B are off, but those of channel A are being strobed by the 32 slots of print field 71 and/or print field 73. Thus, the 32 slots or apertures of the two print fields provide a set of precisely located positions which can be sensed by the electronic circuitry, in regard to when and where it is permissible to print a given character on the printout tape, should such a character be waiting in memory for printout.

A reversible motor moves the carriage and the matrix printer heads back and forth transverse the record or printout media, such as the audit trail and the receipt form as shown in FIG. 1. As the carriage so moves, the sensing devices, of course, move from their HOME slots.

As shown in FIG. 2, the sensing devices and the carriage 12 are aligned on the mid-HOME area. Depending upon the direction of travel, the carriage and sensing devices will move either from the center mid- I-IOME toward the right or toward the left, and the carriage will move until it comes to either the right HOME area or the left HOME area at which time the carriage will stop. Should there be more characters of data to be printed, of course the reversible motor and carriage will again move to traverse the printing media in order to printout the necessary information until such time as there is no more character information to be processed for printing.

As was previously described in connection with FIGS. 3A and 38, as the carriage leaves the HOME slot areas, the absence of a signal in the sensing devices of channel C and channel B and channel A indicates the beginning of the print field, such as 71 or 73. As the carriage with its light sensing means continues to move past the linear strobe bar 60, the uncovering of the first slot of 66,, then causes the light sensing signal (known as the character strobe examples of which are shown in FIG. 38 as occurring in channel A) to initiate a series of short pulses, at and 80.

When the light sensors 106 and 106 (FIG. 2) are sensitized by the first slot (print field) of the set 66,,

this initiates a character strobe as shown as element 80 in FIG. 5 (and also FIG. 3B). Referring to FIG. 5A, the character strobe 80 is amplified and used to activate a column skew one-shot multivibrator 81 which multivibrator has a pulse width of a selectable nature that is normally made to be about one-half the width of the character strobe pulse width. The column skew one-shot 81 performs the function of positioning the character to be printed in coordination with the timing of the remainder of the circuitry regardless of which direction the print carriage is moving, that is to say, regardless of which edge of the particular slot is being uncovered; for example, the right edge of the slot 66,,, 68,, or the left edge.

In FIG. 5A, a basic oscillator 82 (D) is frequencydivided in half by Oscillator 82' (D and again frequency divided to one-fourth the frequency by Column Oscillator 83 (D Thus, Column Oscillator 83 may be used to pulse Up Counter 84 and Down Counter 85 at a counting rate of 770 columns per second. The Up Counter 84 counts the character space columns l-14 of FIG. 4 using the digital numbers to 13. The Down Counter counts in reverse from columns 14 to 1 (again using digital numbers 13-0).

The pulse of the one-shot multivibrator 81 resets the oscillator (D designated element 82', and also resets the column oscillator (D 83, the column oscillator 83 having a pulse width equal (FIG. 6A) to twice the pulse width of the oscillator 82 (or one-half the frequency).

The output of the column oscillator 83 is connected to an up-counter 84 and down-counter 85.

Elements

84 and 85 are counters having two four-bit column counters. The up-counter 84 and the down-counter 85 provide the function of counting the columns within a given character to be printed, but from different directions in order to permit printing to occur during carriage motion in either direction, that is, right to left, or left to right.

The outputs of the up and down counters are fed to a multiplexer 86 which outputs a signal indicative of the nine columns of print which go to make up any individual character. As seen in FIG. A, the multiplexer 86 receives input pulses from oscillator 82 (D This may be called the A time and may be set at 1,540 pulses per second. Thus, multiplexer 86 is made to provide an output of the up-count" alternated with an output of the down count.

The column skew one-shot multivibrator 81 also has an output which is conveyed to a print-head position up counter 87 which carries five-bits of information. The five-bit output of this counter 87 corresponds to the position information of the 32 character slots of the left and right print field 71 and 73: The up counter, 87 corresponds to the print head and carriage motion moving from left to right. A complementing circuit 87,, alternately provides reverse character position counts which correspond to the motion of the carriage and print head from right to left. The output of the counter 87 which provides information as to print-head position for each of the 32 character spaces is conveyed to a comparator 88. The comparator 88 is keyed to the A time (D 82' so that it can alternately compare print head position counts in the up (left-right) direction and in the down (right-left) direction.

Simultaneous with these other units of information being provided to the comparator 88 and the multiplexer 86, a fast clock oscillator 89 (having approximately 32 times the speed of the oscillator 82') provides an output conveyed to a buffer counter 90. The buffer counter is a five-bit (up) counter, and its output tells the sequence position of the particular character residing at the output end of the circulating shift register 91.

It will be seen that the comparator 88 receives printhead position count information, and at the same time the comparator 88 receives from the buffer counter 90, the count position location of characters in memory to be printed. The comparator 88 thus compares the transverse position of the print head with the buffer counter 90 information count which is representative of a particular character and its character space position count.

Concurrently, the oscillatory output of the fast clock oscillator 89 is used to operate a character buffer circulating shift register 91 which consists of a dynamic shift register having an output to a character generator readonly memory 92. The character generator read-only memory 92 has another input taken from the multiplexer 86 which is indicative of the column position information of a given character to be printed. Thus, when there is a correlation and a compare between a character count in the circulating shift register 91 and the correct column count of a character (as indicated by the output of the multiplexer 86) then the output of the character generator 92 is dumped into the latch circuit 93.

Referring to FIG. 5B, the remainder of the electronic control circuitry is shown in more detailed form. The latch circuit 93 of FIG. 5A is in reality composed of two latch circuits: an A latch 93,, and B latch 93,, as shown in FIG. 5B.

Referring again to FIG. 5B, it will be seen that the comparator 88 has an output line to the A latch 93,, and to the B latch 93,,. Further, the character generator ROM 92 has an output set of seven lines to the A latch 93,, and to the B latch 93,,.

The output of the A latch 93,, is used to empower the seven hammers of the left matrix head while the output lines of the B latch 93,, comprise a series of lines which go to drive the seven hammers of the right matrix head.

Circuit 94,, (NAND gate and solenoid driver circuit) is shown connected to one output line of B Latch 93,, and also connected to one line of Hammer Timing One- Shot Circuit 94,. This is exemplary in the drawing to indicate that each of the output lines of A Latch 93,, and B Latch 93,, are similarly provided with such gate circuits as exemplified by 94,.

Since the right matrix printhead (58 of FIG. 1) is required to print on two separate stations (

stations

18 and 20 of FIG. 1) in an inverted printout, the output lines of B Latch 93,, are passed through an inverting circuit 99 (FIG. 5B) which inverts the order of the printhead driving signals from their normal order so that the right printhead 58, when positioned over station 18 (receipt station) will print its character data in an upside down orientation as seen in FIG. 1 on record medium 36. The inverter 99 is only active when a control signal line 99, (activated by the right print field apertures 68,, of strobe bar 60 and carriage locais printing on record medium 36.

As seen in FIG. A, there was provided enabling circuitry 94 in order to control the operation of the matrix print heads. This system is shown in more detail in FIG. 5B wherein there is provided a group of hammer timing one-shots 94,, which are used to phase the firing of the hammers of the left matrix head; and there is also provided another group of hammer timing one-shots 94,, which are used to phase the timing of the hammer driving for the right matrix head.

As will be subsequently shown in the timing diagrams, the firing of the left print head and the right print head is done on alternate cycles even though they appear to be printing simultaneously due to the high rate of printing.

FIGS. 6A, 6B, and 6C are timing drawings illustrative of various timing cycles used by the electronic control circuitry of the printing system. These timing diagrams may be understood more completely by concurrent reference to the drawings and description of FIGS. 5A and 58 to which they also refer.

Referring to FIG. 6A, at line 6-1, there will be seen the basic oscillator (D) pulses which correspond to element 82 of FIG. 5A.

Line 6-2 shows the timing cycles involved in oscillator 82' (D wherein the pulse frequency is divided in half in that oscillator D provides only one output pulse during the time that the basic oscillator (D) is providing two output pulses.

Line 63 shows the timing cycle provided by oscillator 83 (D which further subdivide its on/off pulses into longer time periods. These time periods constitute A Time where the logic output is zero or false, and a B Time where the logic output is one or true.

Line 6-4 shows the On" time in this cycle that it is possible to trigger the hammer-one-shot for the hammers of the left print head. Similarly line 6-7 shows the phase B trigger hammer one-shot On time which can be used to trigger the print heads of the right print head.

Line 6-5 shows the time available for firing the hammers of the left print head through the enabling circuitry 94.

Line 6-6 shows basic reference timing markings in microseconds to give some idea of the relative times involved.

Line 6-8 shows how a match can occur during the A Time in order to cause a printout of the left print head; and likewise, line 6-9 shows how a match from the comparator may occur in order to print out information through the right-hand print head during B time.

Just below line 6-4 there is shown a time designation indicating that one column of the character printing space has a time equivalent of 1,280 microseconds and this is plotted on the'timing diagram in order to show relative occurrence times.

The basic oscillator (D) shown at line 6-1 is shown to have a single cycle time of 320 microseconds while the oscillator D has a cycle time of 640 microseconds. The oscillator (D (at line 6-3) has a cycle time of 1,280 microseconds and is the equivalent time for one column time. Thus, the time period for one column has been split into A Time and a B Time as shown at line 6-3 which also correlates with the drawing of FIG. 4 where there is shown a phase A time and a phase B time. Since the fast clock 89 runs at least 32 times greater than the basic oscillator D, or 64 times greater than the A Time rate, then during the course of any one particular column print time, all 32 character spaces in memory (circulating shift register 91) are scanned for their position and compared in the comparator 88 so that there will be at least two matches occurring every 320 microseconds which is one-half of the A time available for printing on the left matrix print head. Likewise, there are at least 32 character spaces in circulating register 91 which are scanned with the possibility of at least two matches occurring during the B Time or printout time for the right matrix print head.

Referring to FIG. 6B, there is shown a series of timing diagrams indicating relative relationships between the character strobe pulses and other timing functions. In FIG. 6B, line 6-10, there is seen a character strobe pulse occurring (which is normally set at 55 pulses per second). Line 6-11 shows the column skew one-shot 81 (as referred to in FIG. 5A), and as seen, the column skew one-shot pulse is approximately half the pulse width of the character strobe pulse but is initiated by the leading edge of the character strobe pulse. Referring to FIG. 63, it will be seen in line 6-(10) that the character strobe pulse, which is derived from a slit (66 68,, of FIG. 3A) in the strobe bar, has a leading edge which triggers the column skew one-shot as seen in line 6-(11). The trailing edge of the column skew one-shot pulse, line 6-(11), starts the column counter line 6-(12) so that th matrix printhead may initiate its printout for each column of the character space.

While the carriage is moving in the left to right direction, the character strobe is triggered by the left edge of the slit in the strobe bar. However, if the carriage and printhead are moving in the opposite direction, from right to left, then it is the right-hand edge of the slit of the strobe bar which triggers the character strobe and the column skew one-shot pulse. Now since the slit in the strobe bar is of a finite width, and the left-hand edge of the slit is separated from the right-hand edge of the slit, then therefore it can be seen that the triggering start pulse on the left to right motion is going to be different position-wise from the triggering or start pulse when the carriage is moving from right to left, since the left edge of the slit and the right edge of the slit in the strobe bar are separated by a gap. The effect of this would normally be to cause characters which were printed in left to right motion to be out of columnar alignment with characters which were printed while the carriage was moving in the other direction, from right to left.

Thus, by providing an adjustment for the column skew one-shot of FIG. 6B and line 6-(11) thereof (the adjustment is in the width of the column skew oneshot), this adjustment has the effect of compensating for the print solenoid lag time, the flight time of the wire styli, and the width of the strobe bar slit, so that when the character printout is made in the left to right direction and then made in the right to left direction, a visual comparison can be made to see how well the characters in each line fall one under the other. Thus, the adjustment of the width of the column skew oneshot pulse width can be done by visually watching the printout columnar alignment as the printing occurs in both directions.

As was seen in FIG. 5A, the output of the column skew one shot is used to reset the basic oscillator D, the oscillator D the oscillator D and also the up and down counters 84 and 85. Further, as was indicated in FIG. 4, the trailing edge of the output pulse of the Column skew one-shot 81 triggers the start of a character space. Also, the trailing edge of the pulse of the column skew one-shot resets and restarts the basic oscillator D which is used to pulse the column counters 84 and 85. Referring to line 6-12, the start of the basic oscillator (D) triggers the column counters 84 and 85 into pulses which are shown having numbered spaces between them. These numbered spaces between the 14 pulses are the timing features which define the total character space for the printout and spacing of each individual character, and also define each of the nine print and five no print columns of the character space shown in FIG. 4.

Line 6-13 of FIG. 6B shows the A Time timing pulses which have half the pulse-width but double the frequency of the pulses from the column counter shown in line 6-12. The on portions of the A Time" pulses are one-half the pulse width of the column counter pulse width. The trailing edges of the A Time pulses trigger the phase A pulses of line 6-14 for enabling the firing of the left print head; the leading edges of the A Time pulses trigger the phase B pulses of line 6-15 to enable the firing of hammers in the right print head.

Lines 6-14 and 6-15 show the print hammer pulses in timing sequence for the A print hammer and the B print hammer (left and right print head hammers) which are shown to operate alternately in slightly different phases. The printer of this embodiment uses a carriage having dual printheads, a left printhead and a right printhead (as one faces the front of the keyboard of the terminal). A unique problem arises here in that, as seen in FIG. 1, the left printhead will always be arranged to write or print its characters in the printout orientation as shown on the paper record 38 of the audit trail station 20. This means that a person facing the front keyboard can directly read the characters since they are in the proper orientation for one facing the front of the machine. The last 20 lines of the transaction are visible to the operator on the audit trail.

However, on the receipt station 18, and the record paper 36, it will be seen that the orientation of the character printout is reversed and inverted. The result is to produce a receipt oriented in standard accounting form (top to bottom) for the customers receipt.

The dual type printhead carriage 12 operates to cover and to print out on any two of the three printout stations. When the carriage 12 is in the position shown in FIG. 1, then the left-hand printhead 56 will be printing with its orientation for a person standing in front of the machine, and the right-hand printhead 58 will be printing in the reverse inverted orientation.

Now, when the dual printhead carriage is moved to the left side of the machine, it will be seen that while the left-hand printhead 56 will still be printing in the front orientation for an operator facing the keyboard, however, the right-hand printhead 56 must be in a reversed condition from what it had previously been in that it must now also print in the front printout orientation for a person facing the keyboard.

Thus, while the left-hand printhead 56 will always print in the same orientation (the front orientation), the right-hand printhead 58 must reverse itself when it is printing on the audit station 20. That is to say, it must reverse and invert its printout from its printout as shown on the receipt station 18 on the paper record 36.

Thus, the situation involved here is not simply a case where one printhead is simply duplicating the other printhead, but rather is a situation in which the two printheads are separated in space and operate under different conditions and have different output results at certain times.

Station 46, the forms station, prints in the front orientation and the form moves inwardly toward the machine to provide the proper orientation of the printout.

Referring to FIG. 6C, there is shown another group of timing diagrams relative to the electronic control circuitry of the data terminal printer.

Line C-l shows the output pulses of the fast clock 89 which are made to run at least 32 times greater than the basic oscillator frequency D. Line C-2 shows the output of the circulating shift register or buffer 91 maintaining constant character information reading until the end of each fast clock cycle after which there is an information change, but the character information remains constant during the entirety of the fast clock cycle. This indicates that there is a period of approximately 10 microseconds wherein the character information at the output of circulating shift register 91 is stable and useable.

Line C-3 of FIG. 6C shows how the the trailing edge of the fast clock pulses are used to trigger the buffer counter 90 in order to count the character spaces in coordination with the character spaces in the circulating shift register. The buffer counter 90 counts spaces from 0 up to 31, then resets to 0 again.

Line C-4 shows the entry of the first character into the circulating shift register 91 as being located in the number one position since the position zero is not used but is a (spacing) position.

Line C-5 of FIG. 6C indicates that during the time of the first character position, there will be a match" as a result of the comparator 88 which will set the latch unit 93 for a printout through one of the print heads.

The fast clock 89 pulses the circulating shift register 91 so that, when the printhead is at any given position across the printing line, the circulating shift register pulses more than 32 times during the column dwell time, so that at any given character space-column position, all characters in the circulating shift register are scanned.

Thus, when the comparator 88 detects that a match has occurred as between the buffer counter 90, the 5-bit up counter 87 (which counter 87 provides information as to the printhead position for each of the 32 character spaces), then the comparator 88 will trigger the A latch 93 so that the character generator signals from character generator ROM 92 can operate to cause the printhead to print the appropriate dot pattern for the character column.

However, the character generator ROM 92 must be gated by the output of the multiplexer 86 which provides the appropriate character-column-code to the character generator ROM 92 as to which particular orientation of the character to be printed.

Since we have an up-counter 84 and a down-counter 85, it does not make any difference whether the printhead is moving from left to right or right to left. Since printing can take place in either direction, the up" counter 84 is used for printhead motion from left to right and the down counter 85 is used for printhead motion from right to left.

The multiplexer 86 alternately switches between the up-count and down-count column code in feeding character generator ROM 92 when printing is occurring on both the receipt station and audit station simultaneously. The use of either the up-count or the downcount is determined by the direction of printing motion. The control signal D to multiplexer 86 selects the appropriate up or down counter code.

The complementing circuit 87,, takes the information of the 5-bit up counter 87 and complements it so as to provide reverse character position counts which correspond to the motion of the carriage and printhead from right to left.

The up-counter 87 corresponds to the printhead position where the carriage is moving from left to right while the complementing circuit 87, provides reverse character position counts of the printhead position corresponding to the motion of the carriage and print head from the right to the left side.

In essence, the subject printer eliminates the need for carriage return such that the printer is always printing while moving in the right to left direction or in the left to right direction. There is no loss or wasted time for the action of returning the carriage printhead to an initial or beginning position, as is characteristic of the prior art.

Thus, the conditions for a printout are:

a. that the output character of the circulating shift register have a count--address (provided by buffer counter 90) which when supplied to the Comparator 88, matches up with the count of the 5-bit up counter 87. The count of Counter 87 gives the position information of the 32 character spaces of the left and right print fields 71 and 73;

b. that the given output character of circulating shift register 91 is fed into character generator ROM 92 and generator ROM 92 is supplied (by multiplexer 86) the appropriate column code of the 14 columns of the character space which is determined by the up-counter 84 or the down-counter 85.

Thus, herein has been described a data terminal printing unit with electronic control circuitry capable of accurate and positive printing on any one of three separate print stations or alternately on any two of said print stations simultaneously.

The present set of printout stations have been described as a receipt station, an audit-trail station, and a forms station. Any two of these stations may be activated for simultaneous printing during any particular cycle of transaction activity; or if not necessary, the only printout that is needed to take place will take place on the audit trail printout station. Another feature of the present embodiment involves the feature in which the printout on-the receipt station is printed out in upside down orientation to the printout at the audit trail and forms station. This is easily accomplished by the use of inversion or complementing circuitry. Concurrently, with this feature of one print station printing upside down to another print station, it should also be noted that the problem of column skewing has been resolved thereby and also no longer occurs.

What is claimed is:

1. In a data terminal printer system providing for printout of characters on a recording medium programmed for a series of character-spaces each of said character-spaces being programmed to consist of m vertical columns of which n columns are used for character printout and (m-n) columns are provided for nonprint spacing, the combination comprising:

a. a plurality of printout stations having separate recording media each of which are separately movable;

b. carriage means movable transversely back and forth across said printout stations;

c. first and second dot matrix printheads mounted on said carriage means; said printheads including a plurality of wires for impacting on said recording media;

d. sensing means for determining the location of each of said printheads relative to each of said plurality of printout stations and relative to each column of each unit character-space;

e. means for generating character strobe pulses indicative of character-spaces available for printing on each of said plurality of printout stations;

f. a circulating shift register for storage of character data to be printed, said circulation rate being at least 32 times the rate of said character strobe pulses;

g. means for input of data characters into said circulating shift register;

h. means for providing a real-time count of each character-space located opposite the real-time location of said printhead during printhead motion in either of two directions;

i. first counting means for providing information as to what particular column of a character-space is available for printing by each of said first and second matrix printheads;

j. multiplexing means to alternately provide a count of each character-space column during carriage motion for the left-right direction of motion and for the right-left direction of carriage motion;

k. second counting means for providing character position information from said circulating shift register to said first and second matrix printheads, said position information including data for left-right carriage motion and for right-left carriage motion;

1. comparison means for comparison of the printhead position count of each of said first and second matrix printheads with the count of each character position in said circulating shift register, said comparison being responsive to the appropriate direction of carriage motion;

m. memory translation means for programming a selected character symbol into signals representative of dots in a series of columns; and

n. circuit means, activated by said memory translation means, for empowering selected wires of said printhead as said printhead is positioned at each column of a character-space, said circuit means empowering said first and second printheads in alternate phases.

2. In a data terminal printer system providing for programmed printout of data characters in a group of unit character spaces, each unit character space having 14 vertical columns per character space of which nine columns are used for character printout and five columns are used for non-print spacing, the combination comprising:

a. a plurality of printout stations having movable recording media;

0. first and second wire matrix printheads mounted on said carriage means;

d. indicia means for programming the location of character-spaces available for printing on each recording media for each printout station;

e. sensing means for determining the carriage and printhead position relative to each of said character spaces available for printing;

f. means for input of data characters in a memory device;

g. means for addressing each of the data characters in said memory device; and

h. means for matching the programmed character space positions with the appropriate data character address positions in said memory device during transverse motion of the printheads in either direction in order to trigger the first and second printheads into a printout of the proper character in the proper character space on the preselected printout stations desired.

3. The printer system of claim 2 including means for the alternate triggering of the first and second printheads for printout during the period of any given column count which was started by the character position strobe derived from said indicia means.

4. The printer system of claim 2 including means for vertical columnar alignment of characters printed on one line of recording media with characters printed out on other lines of recording media.

5. The printer system of claim 2 including means for adjusting the time between the initiation of a character strobe pulse, which locates an available character space on the recording media, and the initiation of a series of column count pulses, which pulses permit character imprintation dots to be printed by said printheads.

6. In a printing device in which the printed characters are formed of differential combinations of the dots of a matrix of dots arranged in sequential columns, the combination comprising:

a. a plurality of printout stations each having separately movable recording media;

b. carriage means movable transversely back and forth across each of said print-.out stations;

c. first and second wire matrix printheads mounted on said carriage means and juxtaposed movably across said plurality of printout stations, said printheads being capable of printout while moving from left .to right or right to left;

d. means for programming character spaces on said printout stations;

e. sensing means for establishing the printhead positions relative to each programmed character space;

f. means for intake and storage of character input data;

g. means for matching printhead position information with stored character data location information in order to trigger the printout of a stored character at a programmed location on one or more of the recording media of the plurality of printout stations;

h. initiating means for activating said first and second printheads into printout of a sequential series of columns of dots whether said printheads are moving from right to left or left to right.

7. The printing device of claim 6 including timing means for alternately triggering the printout times of the said first and second printheads during each period of column strobing of each character to be printed.

8. The printing device of claim 6 including adjustment means for said initiating means, said adjustment means providing for the vertical columnar alignment of printout characters on one line of the recording media with the printed out characters on succeeding lines of the recording media.

9. The printing device of claim 6 including means for simultaneous printing on two of said plurality of printout stations whereby the printout from said second printhead is selectively controlled to print characters in a front orientation or a reverse orientation.

10. The printing device of claim 6 wherein said sensing means comprises an indicia bar having indicia to indicate end-stop positions for said printhead and to indicate programmed character space positions as being available for printout separately for each of two different positions of said carriage means and including readout means to read said indicia from said indicia bar for conversion to electronic timing signals.

11. In a printing device in which the printed characters are formed of differential combinations of the dots of a matrix of dots arranged in sequential columns the combination comprising:

a. a printout station having movable recording media;

b. carriage means movable transversely back and forth across said printout station;

c. printhead means mounted on said carriage means, and capable of printout during carriage motion back and forth across said print-out station;

d. sensing means for establishing the printhead position relative to each character space programmed as available for printing on said recording media;

e. means for intake and storage of character input data;

f. means for matching printhead position information with stored character data location information for printout of a stored character at a designated location on the recording media, said means-for matching being operative for causing character printout during forward or reverse motion of said carriage means.

12. The printing device of claim 11 including means for vertical columnar alignment of the printout of characters on one line of the recording media with the printout of characters on other lines of the same recording media.

13. The printing device of claim 11 wherein said sensing means comprises an indicia bar having selected indicia to indicate end stop positions for said printhead and to indicate character print positions programmed as available for printout on said recording media and including means for initiating the printout of a combination of dots in a column during the time that the printhead means is moving from left to right or is moving from right to left; and including means for adjustment of said initiating means so that the printout of characters on one line of print of said recording media is properly aligned columnarly with the printout of a column skew one-shot circuit triggered by the leading edge of said character strobe pulse and for providing a column-skew pulse;

column-counting circuitry for strobing the various columns of a character-space, said columncounting circuitry being triggered by the trailing edge of said column-skew pulse.

15. The printing device of claim 14 wherein the column skew one-shot circuit is adjustable in order to regulate the width of the column skew pulse.

Claims

1. In a data terminal printer system providing for printout of characters on a recording medium programmed for a series of character-spaces each of said character-spaces being programmed to consist of m vertical columns of which n columns are used for character printout and (m-n) columns are provided for non-print spacing, the combination comprising: a. a plurality of printout stations having separate recording media each of which are separately movable; b. carriage means movable transversely back and forth across said printout stations; c. first and second dot matrix printheads mounted on said carriage means; said printheads including a plurality of wires for impacting on said recording media; d. sensing means for determining the location of each of said printheads relative to each of said plurality of printout stations and relative to each column of each unit characterspace; e. means for generating character strobe pulses indicative of character-spaces available for printing on each of said plurality of printout stations; f. a circulating shift register for storage of character data to be printed, said circulation rate being at least 32 times the rate of said character strobe pulses; g. means for input of data characters into said circulating shift register; h. means for providing a real-time count of each character-space located opposite the real-time locatiOn of said printhead during printhead motion in either of two directions; i. first counting means for providing information as to what particular column of a character-space is available for printing by each of said first and second matrix printheads; j. multiplexing means to alternately provide a count of each character-space column during carriage motion for the leftright direction of motion and for the right-left direction of carriage motion; k. second counting means for providing character position information from said circulating shift register to said first and second matrix printheads, said position information including data for left-right carriage motion and for rightleft carriage motion; 1. comparison means for comparison of the printhead position count of each of said first and second matrix printheads with the count of each character position in said circulating shift register, said comparison being responsive to the appropriate direction of carriage motion; m. memory translation means for programming a selected character symbol into signals representative of dots in a series of columns; and n. circuit means, activated by said memory translation means, for empowering selected wires of said printhead as said printhead is positioned at each column of a character-space, said circuit means empowering said first and second printheads in alternate phases.

2. In a data terminal printer system providing for programmed printout of data characters in a group of unit character spaces, each unit character space having 14 vertical columns per character space of which nine columns are used for character printout and five columns are used for non-print spacing, the combination comprising: a. a plurality of printout stations having movable recording media; b. carriage means movable transversely back and forth across said printout stations; c. first and second wire matrix printheads mounted on said carriage means; d. indicia means for programming the location of character-spaces available for printing on each recording media for each printout station; e. sensing means for determining the carriage and printhead position relative to each of said character spaces available for printing; f. means for input of data characters in a memory device; g. means for addressing each of the data characters in said memory device; and h. means for matching the programmed character space positions with the appropriate data character address positions in said memory device during transverse motion of the printheads in either direction in order to trigger the first and second printheads into a printout of the proper character in the proper character space on the preselected printout stations desired.

6. In a printing device in which the printed characters are formed of differential combinations of the dots of a matrix of dots arranged in sequential columns, the combination comprising: a. a plurality of printout stations each having separately movable recording media; b. carriage means movable transversely back and forth across each of said print-out stations; c. first and second wire matrix printheads mounted on saId carriage means and juxtaposed movably across said plurality of printout stations, said printheads being capable of printout while moving from left to right or right to left; d. means for programming character spaces on said printout stations; e. sensing means for establishing the printhead positions relative to each programmed character space; f. means for intake and storage of character input data; g. means for matching printhead position information with stored character data location information in order to trigger the printout of a stored character at a programmed location on one or more of the recording media of the plurality of printout stations; h. initiating means for activating said first and second printheads into printout of a sequential series of columns of dots whether said printheads are moving from right to left or left to right.

11. In a printing device in which the printed characters are formed of differential combinations of the dots of a matrix of dots arranged in sequential columns the combination comprising: a. a printout station having movable recording media; b. carriage means movable transversely back and forth across said printout station; c. printhead means mounted on said carriage means, and capable of printout during carriage motion back and forth across said print-out station; d. sensing means for establishing the printhead position relative to each character space programmed as available for printing on said recording media; e. means for intake and storage of character input data; f. means for matching printhead position information with stored character data location information for printout of a stored character at a designated location on the recording media, said means for matching being operative for causing character printout during forward or reverse motion of said carriage means.

13. The printing device of claim 11 wherein said sensing means comprises an indicia bar having selected indicia to indicate end stop positions for said printhead and to indicate character print positions programmed as available for printout on said recording media and including means for initiating the printout of a combination of dots in a column during the time that the printhead means is moving from left to right or is moving from right to left; and including means for adjustment of said initiating means so that the printout of characters on one line of print of said recording media is properly aligned columnarly with the printout of characters on succeeding lines of print of saId recording media.

14. The printing device of claim 13 wherein said initiating means includes: an indicia bar having slitted apertures for programming positions of available character-space positions available for printout along said recording media; movable light and photodetector sensing means referenced to said printhead position for scanning said slitted apertures and for providing a character strobe pulse; a column skew one-shot circuit triggered by the leading edge of said character strobe pulse and for providing a column-skew pulse; column-counting circuitry for strobing the various columns of a character-space, said column-counting circuitry being triggered by the trailing edge of said column-skew pulse.