US3647356A

US3647356A - Printer drive with page record feed

Info

Publication number: US3647356A
Application number: US11258A
Authority: US
Inventors: Alvin Feder
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 1970-02-13
Filing date: 1970-02-13
Publication date: 1972-03-07
Anticipated expiration: 1989-03-07
Also published as: IL35946A; ZA708726B; DE2106960B2; IL35946A0; DE2106960A1

Abstract

A printer drive mechanism for a printer including a cylindrical platen and page record mechanism coaxially mounted on the platen shaft. A gear train connects the platen to the page record feed mechanism allowing synchronous but independent rotation of the platen and the page record feed mechanism, with the page record feed mechanism rotating at a slower rate than the platen. A stepping motor is used to rotate the platen, and printing occurs after each step of the motor thereby preventing the printed dot from blurring due to platen rotation or page record advancement.

Description

United States Patent Feder Mar. 7, 1972 [54] PRINTER DRIVE WITH PAGE RECORD FEED [72] Inventor: Alvin Feder, Skokie, ll].

[73] Assignee: Motorola, Inc, Franklin Park, 111.

[22] Filed: Feb. 13, 1970 211 Appl. 140.: 11,258

[52] U.S.Cl. ..346/l0l, 101/93 C, 178/25 [51] Int. Cl. ..B4lj 11/24, 8413' 11/38 [58] Field ofSearch ..101/93 C, 93 R, 93 MN;

346/101; 178/25, 32 561 References Cited UNITED STATES PATENTS 1,848,862 3/1932 Young ..346/ l 01 X 3 ,409,904 1 1/1968 Maiershofer... ..346/ 101 2,934,974 5/1960 Schoepe ....l92/47 X 2,909,996 10/1959 Fitch ..l01/93 C 1,958,885 5/1934 Carlisle .L ..346/l01 Chilberg et a1. .346] 101 Amada Hell Alden Young ..346/ l 01 Primary Examiner-J. Reed Fisher Attorney-Mueller & Aichele ABSTRACT A printer drive mechanism for a printer including a cylindrical platen and page record mechanism coaxially mounted on the platen shaft. A gear train connects the platen to the page record feed mechanism allowing synchronous but independent rotation of the platen and the page record feed mechanism, with the page record feed mechanism rotating at a slower rate than the platen. A stepping motor is used to rotate the platen, and printing occurs after each step of the motor thereby preventing the printed dot from blurring due to platen rotation or page record advancement.

9 Claims, 5 Drawing Figures PATENTEDIMR "/1912 3,647. 356

SHEET 1 UF 2 FIG. 1'

FIG. 3

Inventor ALVIN FEDER ATTYS.

PATENTEDMAR 7 I972 SHEET 2 BF 2 Ga a Inventor ALVIN FEDER W E Rau w ATTYSh PRINTER DRIVE WITH PAGE RECORD FEED BACKGROUND OF THE INVENTION Mechanical drive mechanisms in printers require a platen for printing and a page record drive mechanism to drive the paper through the printer. Print hammers strike the paper against the platen to print a symbol. Prior printers have mounted the paper feed wheels coaxially with the platen, however, the feed wheels were rotatably secured to the printer chassis. A ratchet mechanism, actuated by an appropriate signal, turned the page record drive mechanism thereby advancing the paper. Both the mechanical mounting of the drive mechanism and the ratchet mechanism were complex, expensive, and unsuitable for use in a mobile environment. Lack of synchronization between the platen, printer hammers, and page record drive mechanisms caused overtyping and inconsistent spacing between printed lines.

SUMMARY OF THE INVENTION It is therefore an object of this invention to provide a simplified printer drive mechanism for use in a mobile printer.

Another object of this invention is to provide a printer drive mechanism wherein no ratchet mechanism is required to advance the page record.

Yet another object of this invention is to provide a printer drive mechanism wherein the page record feed means is precisely synchronized with the platen rotation and printer hammer operation.

In practicing this invention a printer drive mechanism is provided wherein a platen shaft having a helical platen vane thereon is rotatably secured to the printer chassis. Page record feed wheels are rotatably mounted on a journaled portion of the platen shaft, adjacent each end of the helical platen vane. A stepping motor is secured to the printer chassis adjacent the platen shaft and coupled to the platen shaft through a pair of gear wheels. The other end of the platen shaft is coupled through a series of reducing gears to a gear shaft which has two gears thereon. The two gears on the gear shaft are coupled to gear teeth on the page record feed mechanism. Rotation of the platen shaft by the stepping motor causes the page record feed mechanism to rotate in the same direction as the platen shaft but at a slower rate of rotation. Tension wheels mounted to springs secured to the printer chassis, bear against the page record feed mechanism causing the page record to be aligned parallel to the platen shaft. Pizoelectric printer hammers are selectively energized to strike against the page record and platen vane causing a dot to appear on the page record. The piezoelectric printer hammers are actuated after the motor has stepped and while the platen vane and page record feed mechanism are stopped so that the printed dot will not be blurred.

In a second embodiment the reducing gears couple the platen shaft to the page record feed mechanism such that the page record feed mechanism is incremently rotated once for each full revolution of the platen shaft. Allowing rotation of the page record feed wheels once after each platen rotation simplifies the gearing mechanism and positioning of the piezoelectric printer hammers. The simplified gearing allows the use of the lower torque stepping motor.

A spring biased knurled thumbwheel located on the printer front panel, allows manual advancement of the page record. Pushing the thumbwheel upward will also depress the thumbwheel and cause it to bear against a second wheel located at the end of a gear shaft which is coupled to the page record feed mechanism. The gear shaft is normally rotated by a gear train coupled to the platen shaft. Rotation of the thumbwheel disengages a one-way slip clutch coupling the gear shaft and the drive train, thereby allowing the gear shaft and page record feed mechanism to be rotated independent of the platen shaft and gear train.

The invention is illustrated in the drawings of which:

FIG. 1 is a perspective drawing of the printer drive mechanism;

FIG. 2 is a plan view of the printer drive mechanism of the invention;

FIG. 3 is a cutaway drawing showing a page record drive mechanism;

FIG. 4 is a perspective drawing of another embodiment of the invention;

FIG. 5 is a perspective drawing ofa portion of the gear train shown in FIG. 4.

DETAILED DESCRIPTION Referring to FIGS. 1 and 2 there is shown a printer drive mechanism incorporating the features of this invention. The printer drive mechanism has a rotary platen having a platen shaft 21 and a raised helical portion or vane 22. Adjacent to the raised helical portion 22 there is a

paper drive mechanism

27 and 28 rotatably mounted on a journaled portion of the platen shaft 21. Bearings 29 and 30 rotatably mount platen shaft 21 on chassis mounting bracket 31. Stepping motor 33, coupled to the platen shaft 21 through

gears

34 and 35, drives the platen 20 in the direction of arrow 36. In this embodiment the platen is rotated at I66 revolutions per minute, with 48 steps per revolution. Platen gear 38 mounted at the end of the platen shaft 21 drives a gear train consisting of

gears

39, 40 and 41 which are rotatably mounted to chassis mounting bracket 31. Gear 41 is connected through a one-way clutch 42 to gear shaft 43. Gear shaft 43 is rotatably mounted in chassis mounting bracket 31 by bearings 45 and 46.

Gears

49 and 50 mounted on gear shaft 43 engage

gears

51 and 52 of page

record feed mechanisms

27 and 28 causing the page record feed mechanisms to rotate. The purpose of the gear train is to allow the page

record feed mechanisms

27 and 28 to rotate at a speed slower than the speed of platen 20 yet retain a synchronization between the rotation of the platen 20 and the rotation of page

record feed mechanisms

27 and 28. In this embodiment the page

record feed mechanisms

27 and 28 rotate at a speed of 1.57 revolutions per minute, with 48 stops per revolution. The gear train produces a speed reduction of 105 to l.

Referring to FIG. 3 the page record feed mechanism 27 includes a cylindrical metal portion 53 having a hollow center 48. The cylindrical metal portion 53 is inserted into the center opening of a cylinder 54, preferably made of a plastic material such as polyurethane. Cylinder 54 bears against the paper, feeding it through the printer mechanism. The other end of metal cylinder 53 is inserted into a center opening in page record drive gear 52. Page record drive gear 52 and cylinder 54 are separated by ridge 55 on metal cylinder 53. Ballbearings 56 and 57 are inserted in metal cylinder 53 to allow the page record feed mechanism 27 to rotate on platen shaft 21.

Pressure rollers 58 and 59 (FIG. 1) rotatably mounted on

spring brackets

60 and 61, bear against

paper drive mechanisms

27 and 28 causing the ink-impregnated paper 62 to move upward in front of platen 20. Piezoelectric printer hammers 63, when actuated by a proper electric signal will strike against the ink-impregnated paper 62 and the platen helix 22 causing a dot to appear on the paper.

In operation stepping motor 33 rotates, turning platen 20 at 166 revolutions per minute, wheel 64 secured to gear 35 has a magnet 65 thereon. Magnetic relay 66 located adjacent platen shaft 21 will be energized once every revolution of platen shaft 21 when magnet 65 passes magnetic relay 66. The signal produced when magnetic relay 66 is energized is used to synchronize the rotation of the platen 20 and operation of the piezoelectric printer hammers 63. Stepping motor 33 stops 48 times in each revolution, causing platen 20 and the page

record feed mechanisms

27 and 28 to also stop. While stopped electronic signals actuate piezoelectric hammers 63 causing them to strike the ink-impregnated paper 62 against platen helix 22, producing a dot. By stopping rotation of the platen 20 and page

record feed mechanisms

27 and 28 each time a dot is printed, no blurring of the dot will occur. A line of dots can be printed for each rotation of platen 20. As the page

record feed mechanisms

27 and 28 advance the paper slightly for each revolution of platen 20, a line of dots printed in a single revolution of platen 20 would be slightly skewed on the page record. To eliminate this problem piezoelectric hammers 63 are skewed slightly with those at the left being lower than those at the right. To provide a space between printed lines plate 20 is allowed to rotate an approptiate number of times without actuating any of the piezoelectric printer hammers 63, thereby allowing page

record feed mechanisms

27 and 28 to advance the page record.

Referring to FIGS. 4 and 5 there is shown a second embodiment of a printer drive mechanism incorporating the features of this invention. Gear wheel 74 mounted at the end of platen shaft 21 has a single gear tooth recess 75 in the peripheral edge. An axially protruding tab 80, secured to face 81 of gear wheel 74 will bear against secondary gear tooth 82 causing gear wheel 76 to rotate and position primary gear tooth 83 on gear wheel 76 to allow engagement with gear tooth recess 75 on gear wheel 74. The proximity of

gear wheels

74 and 76 prevents gear wheel 76 from turning freely until tab 80 bears against secondary gear tooth 82 and a primary gear tooth 72 on gear wheel 76 is in alignment with gear tooth recess 75 in gear wheel 74. Gear wheel 74 drives the gear train consisting of

gears

76, 77 and 78, which are rotatably mounted to chassis mounting bracket 31. As in the previous embodiment (FIG. 2) gear 78 (gear 41 in FIG; 2) is connected through a one-way clutch 42 to gear shaft 43.

When platen has completed one full revolution, gear tooth recess 75 in gear wheel 74 will engage and rotate gear 76. This rotation will be transferred from gear 76 through

gears

77 and 78, gear shaft 43, and shaft gears 49 and 50 to

paper drive mechanisms

27 and 28. As a line of dots may be printed in each rotation of platen 20, without the page record advancing as the line is printed, the piezoelectric printer hammers 63 can be assembled parallel to platen 20 and not skewed as shown in the previous embodiment. Since skewing of the piezoelectric printer hammers 63 requires adjustment to precise tolerances, the use of a drive mechanism which advances the page record, after each line of dots, simplifies installation and maintenance of the printer drive mechanism.

With the gears coupled to the platen shaft 21 only once in each revolution there is less drag on platen 20 and therefore a lighter load on stepping motor 33. With the lighter load on stepping motor 33, a lower torque and less expensive stepping motor may be used in the printer drive mechanism.

In order to manually advance the page record, a spring biased thumbwheel 68 (FIG. 1) is provided which is mounted on the printer front panel 69. To advance the paper the thumbwheel 68 is pushed upward and rotated in the direction of arrow 70. This upward pushing movement also depresses the thumbwheel 68 and engages, in frictional drive, wheel 71 fastened on an extension of gear shaft 43. Rotation of thumbwheel 68 causes rotation of wheel 71 and gear shaft 43. One-way clutch 42 mounted on gear shaft 43 allows gear shaft 43 to rotate independent of gear 41 (or gear 78 in FIG. 4). The rotation of gear shaft 43 rotates shaft gears 49 and 50 causing page

record feed mechanisms

27 and 28 to rotate, thereby advancing the page record.

As can be seen, a simplified printer drive mechanism has been provided which is capable of operation in shock and vibrational environment. Use of a coaxially mounted platen and page record feed mechanism synchronously driven by a motor and gear train eliminates the need for complex ratchet or escapement mechanisms and provides a simplified drive mechanism less susceptible to improper operation, shock and vibration.

lclaim:

l. A mechanical drive mechanism for a symbol printing page record printer including in combination, an elongated rotatable platen, page record feed means rotatably mounted coaxially on said platen adjacent each end thereof, mounting means for rotatably mounting said platen to the symbol printing page record printer, a stepping motor coupled to said platen for incrementally rotating said platen at a first rate of rotation, first gear means coupling said page record feed means to said platen, said first gear means including a gear shaft rotatably mounted to said mounting means, first and second gear wheels secured to said shaft and in operative association with said page record feed means, clutch means secured to said shaft, and transfer gear means rotatably mounted to said mounting means and in operative association with said platen and said clutch means for transferring said platen rotation to said page record feed means by way of said clutch means and synchronously, incrementally rotating said record feed means at a second rate of rotation slower than said first rate of rotation, and manual page record feed means including a first wheel secured to an end of said gear shaft, a thumbwheel and biasing mounting means therefor for holding said thumbwheel a first position spaced from said first wheel, said thumbwheel being movable to a second position in operative association with said first wheel so that rotation of said thumbwheel causes said first wheel, said gear shaft, and said first and second gear wheels to rotate by way of said clutch means independently of said transfer gear means, whereby said page record feed means is rotated independently of the rotation of said platen.

2. The mechanical drive mechanism of claim 1 wherein said page record feed means includes, a cylindrical shaped portion, a gear wheel having gear teeth in the peripheral edge secured to one end of said cylindrical shaped portion, a hole cut through said gear wheel and cylindrical portion along the axis of said cylindrical portion, and bearing means secured to the walls of said hole for rotatably mounting said page record feed means on said platen shaft.

3. The mechanical drive mechanism ofclaim 1 wherein said platen includes, a cylindrical platen shaft and a raised helical platen vane, said platen shaft extending through and rotatably supporting said page record feed means on each side of said helical platen vane, said platen shaft being rotatably mounted on said mounting means, second gear means at an end of said platen shaft in operative association with said first gear means, and third gear means at the other end of said platen shaft in operative association with said stepping motor.

4. The mechanical drive mechanism of claim 3 wherein said second gear means is a gear wheel having a single gear tooth in the peripheral edge.

5. The mechanical drive mechanism of claim 3 wherein said second gear means is a gear wheel having a plurality of gear teeth in the peripheral edge.

6. The mechanical drive mechanism of claim 3 wherein said transfer gear means includes a plurality of gear wheels coupling said second gear means on said platen shaft to said gear shaft to incrementally rotate said page record feed means when said platen is rotated.

7. The mechanical drive mechanism ofclaim 6 wherein said transfer gear means includes, a third gear wheel having gear teeth on the peripheral edge thereof coupled to said clutch means, a fourth gear wheel rotatably secured to said mounting means having first and second gears thereon, a fifth gear wheel rotatably secured to said mounting means having third and fourth gears thereon, said third gear in operative association with with said second gear on the fourth gear wheel, said fourth gear in operative association with said second gear means on said platen shaft, said gear wheels and gear shaft cooperating to incrementally rotate said page record feed means when said platen is rotated.

8. The mechanical drive mechanism ofclaim 6 wherein said transfer gear means includes, a third gear wheel having gear teeth in the peripheral edge thereof coupled to said clutch means, fourth and fifth gear wheels having gear teeth in the peripheral edge thereof rotatably secured to said mounting means, said fourth gear in operative association with said second gear means on said platen shaft, said gear wheels and gear shaft cooperating to incrementally rotate said page record means when said platen is rotated.

9. The mechanical drive mechanism of claim 6 wherein said clutch means is a one-way clutch allowing rotation of said gear shaft in only one direction of rotation.

Claims

1. A mechanical drive mechanism for a symbol printing page record printer including in combination, an elongated rotatable platen, page record feed means rotatably mounted coaxially on said platen adjacent each end thereof, mounting means for rotatably mounting said platen to the symbol printing page record printer, a stepping motor coupled to said platen for incrementally rotating said platen at a first rate of rotation, first gear means coupling said page record feed means to said platen, said first gear means including a gear shaft rotatably mounted to said mounting means, first and second gear wheels secured to said shaft and in operative association with said page record feed means, clutch means secured to said shaft, and transfer gear means rotatably mounted to said mounting means and in operative association with said platen and said clutch means for transferring said platen rotation to said page record feed means by way of said clutch means and synchronously, incrementally rotating said record feed means at a second rate of rotation slower than said first rate of rotation, and manual page record feed means including a first wheel secured to an end of said gear shaft, a thumbwheel and biasing mounting means therefor for holding said thumbwheel a first position spaced from said first wheel, said thumbwheel being movable to a second position in operative association with said first wheel so that rotation of said thumbwheel causes said first wheel, said gear shaft, and said first and second gear wheels to rotate by way of said clutch means independently of said transfer gear means, whereby said page record feed means is rotated independently of the rotation of said platen.

3. The mechanical drive mechanism of claim 1 wherein said platen includes, a cylindrical platen shaft and a raised helical platen vane, said platen shaft extending through and rotatably supporting said page record feed means on each side of said helical platen vane, said platen shaft being rotatably mounted on said mounting means, second gear means at an end of said platen shaft in operative association with said first gear means, and third gear means at the other end of said platen shaft in operative association with said stepping motor.

7. The mechanical drive mechanism of claim 6 wherein said transfer gear means includes, a third gear wheel having gear teeth on the peripheral edge thereof coupled to said clutch means, a fourth gear wheel rotatably secured to said mounting means having first and second gears thereon, a fifth gear wheel rotatably secured to said mounting means having third and fourth gears thereon, said third gear in operative association with with said second gear on the fourth gear wheel, said fourth gear in operative association with said second gear means on said platen shaft, said gear wheels and gear shaft cooperating to incrementally rotate said page record feed means when said platen is rotated.

8. The mechanical drive mechanism of claim 6 wherein said transfer gear means includes, a third gear wheel having gear teeth in the peripheral edge thereof coupled to said clutch means, fourth and fifth gear wheels having gear teeth in the peripheral edge thereof rotatably secured to said mounting means, said fourth gear in operative association with said second gear means on said platen shaft, said gear wheels and gear shaft cooperating to incrementally rotate said page record means when said platen is rotated.