US3814012A

US3814012A - Train printers

Info

Publication number: US3814012A
Application number: US00273594A
Authority: US
Inventors: R Derc
Original assignee: Fujitsu Services Ltd
Current assignee: Fujitsu Services Ltd
Priority date: 1971-07-23
Filing date: 1972-07-20
Publication date: 1974-06-04
Anticipated expiration: 1991-06-04
Also published as: DE2235394A1; GB1350442A; AU4452572A; CH551665A; JPS5528866B1; DE2235394C2; AU463240B2

Abstract

A train printer cartridge and print slug arrangement having a closed loop guide track for non inter connected print slugs freely slidable in the guide track and each having a single drive tooth on each side of the slug, the teeth meshing with notched drive wheels. The track arrangement permits the slugs to move from abutting contact whilst meshing with the wheels and also enables transformation of angular motion around the wheels to the straight line motion for advancing to the printing section to be completed before the slug leaves the drive wheels.

Description

United States Patent 11 1 Dere 11] 3,814,012 June 4, 1974 TRAIN PRINTERS [75] Inventor: Roman Derc, Letchworth, England [73] Assignee: International Computers Limited,

London, England [22] Filed: July 20, 1972 [21] Appl. No.: 273,594

[30] Foreign Application Priority Data 12/1963 Simpson 101/111 3,379,126 7/1966 Stalleretall 101/382 3633501 9/1969 Edwards 101/111 Primary Examiner-J. Reed Fisher Assistant Examiner-Paul J. Hirsch Attorney, Agent, or Firm-Hane, Baxley & Spiecens 1 7 ABSTRACT A train printer cartridge and print slug arrangement hay nga closed loop guide tracli for non 1115656611 ne cted print slugs freely slidable in the guide track and .each having a single drive tooth on each side of the slug, the teeth meshing with notched drive wheels. The track arrangement permits the slugs to move from abutting contact whilst meshing with the wheels and also enables transformation of angular motion around the wheels to the straight line motion for advancing to the printing section to be completed before the slug leaves the drive wheels.

'5 Claims, 6 Drawing Figures PATENTEDJuu 4 I974 SHEET 2 [IF 2 I TRAIN. PRINTERS BACKGROUND OF THE INVENTION The invention relates to train printers.

In a train printer print slugs, each bearing a few characters push each other in guides round a closed-loop, generally oval, track having at least one straight portion at which printing takes place. The slugs are not connected to each other and have integral teeth by which they are driven at part of the track, for example by a toothed drive wheel at either, or both, ends of an oval track. Some clearance is necessary in the guides and,

According to the invention there is provided a train printer print slug having a body portion with teeth for engaging with a toothed driving wheel of a train printer, characterised in that the slug has a single centrally disposed tooth at each side of the body portion.

Preferably in accordance with an aspect of the invention a train printer cartridge comprises guide means defining a closed-loop track for print slugsaccor ding to the invention, the track having a straight portion extending from a curved portion about a toothed drive wheel for meshing with teeth of the slugs to drive them into the straight portion, one part of the guide means permitting slugs being driven to move radially outwardly of the drive wheel without losing driving engagement, and another part co-operating with surfaces of a slug to bring that slug into alignment with the straight track portion before the centre. of that slug reaches the perpendicular from the driving wheel axis tothe straight portion.

The slugs will thus have their rotational movement round the driving wheel transformed to rectilinear movement prior to leaving the driving wheel. The avoidance of coincidence of these two actions reduces BRIEF DESCRIPTION OF THE DRAWING One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings,'in which:

FIG. I shows, diagrammatically, parts of a train printer cartridge;

FIG. 2 is a side view of a print slug;

FIG. 3 is an end view of a print slug;

FIG. 4 is a section through the teeth of a slug drive wheel; 1

FIG. 5 is an enlarged view of a detail of the cartridge of FIG. 1; I

FIG. 6 is a part section on the line 22 of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT In the illustrated train printer cartridge, a series of print slugs 11 are passed along a generally oval track between inner and

outer guide surfaces

12 and 13, respectively. The slugs 11 are separate an d are driven only at the ends of the track by toothed drive wheels 114; In between these drive wheels, the slugs abut at their ends to push each other along 'a straight part of the track. Alongside one such straight part is a printing hammer block 15. In operation, paper and an inked web are present between the hammer block 15 and the print slugs II and, as the latter pass by,ballistic ham mers within the block l5 are fired at appropriate times to press the paper and ink web against the characters borne by the slugs 11. The print bearing portions of the slugs protrude through spaced parts of the outer guide surfaces 13.

chatter of the slugs and enables printing to take place nearer the driving wheel.

Since'the slug has a single tooth disposed substantially centrally on each side thereof, driving forces from the driving wheel teeth will be generally symmetrical relative to the centre of gravity of a slug. This avoids the kinds of movement on the slug that result for slugs operating with outer guides of the guide means. These shoulders may flank an upstanding character bearing surface and are sloped at each end. These slopes, to gether with slopes on the tooth edges and the ends of the slug co-operate in achieving the above mentioned prior alignment with the straight track portion. v

It is convenient for the inner guide surface 12 to comprise the edge surface of an ovalplate 49, and each of the outer guide surfaces 13 to comprise the inner side surface of an edge flange on a generally oval cover 13A for each face of the oval plate.

The outer guide surfaces 13 are curved about the drive wheel 14 and spaced therefrom by a, distance greater than the distance between the

surfaces

12 and 13 along the straight portion of the track to allow the slugs to'move radially outwardly of the drive wheel without losing driving engagement, and be brought into alignment with their directionof travel along the straight parts ofthe track prior to each slug leaving the teeth of the drive wheels, in factpriorto its centre reaching top dead centre. This results from the transition from curved to straight in the outer guide surfaces 113 and improves the way in which the slugs 11 travel past thehammer block 15, and alsov enables the latter to be nearer to top dead centre of the left hand drive,

FIG. I, would in practice, correspond with front" and back respectively.

Instead of being in abutting, or near-abutting relation, the slugs 11 in the curved part l3, are slightly spaced as indicated by the gap 19 in FIG. 1. The transi- 3 tion of the guide surface 13 from curved to straight at position 21 prior to top dead centre 22 marks the beginning of tipping of a slug forwards to achieve alignment with the track past the hammer block at a position 23 prior to the centre of the slug-coinciding with top dead centre 22. Transformation of angular motion into rectilinear motion is thus achieved prior to a slug leaving the teeth of the drive wheel, which occurs at top dead centre 22. This action reduces irregularities of subsequent slug motion.

Each slug 11 has a single centrally disposed tooth 26 on each side. These teeth 26 taper so that their upper surfaces 27 extend further along the slug. The slide surfaces 27 are extensions of stepped central parts 28 of the slug along body portion 30A to either side of an upstanding character 29 bearing portion 30. At each end, the central stepped parts 28 have extensions 31 inclined downwardly. Along straight portions of the slug track, the outer guide 13 will contact the central stepped parts 28. The-stepped parts 31 are inclined more than would be required for them to make chords on the curved part of the upper guide. This allows a slug to be tipped forwards immediately after the upper guide transition 21.

Each slug has a central channel 32 for engaging the lower guide 13. Sides 33 which are downwardly extending from the body portion 30A flank this channel 32 and have lower front and rear faces 34 that slope inwardly of the slug from middle surface portions 35. The

rest of the slug body'portion 30A above the surface portions 35 is stepped back therefrom at 36. It is by abutment of the middle surfaces 35 that the slugs push each other between the drive wheels 14. The bottom 37 of the channel 32 has both its end portions 38 sloped upwardly to allow the desired tipping. This is also of assistance in tipping of the slugs prior to leaving a drive wheel as does the taper on the teeth 26. In fact, the three factors mentioned are aspects of the same design feature of prior alignment of the slugs.

The front of a slug ,ll vis brought down into the matching drive wheel notch until the slug is aligned with its straight path of travel by the time the centre of the slug reaches the position 23 prior to top dead centre 22 of the drive wheel.

As shown in FIGS. 4, 5 and 6, each drive wheel 14 comprises an assembly of two similarly notched

wheels

45 and 46 carried on the same shaft 50 through a suitable bearing 51 to define spaced

toothed portions

47 and 48 in register with each other on either side of the plate 49 whose edges comprise the guide surface 12.

The factthat the slug has a single centrally disposed tooth on each side leads to a very well balanced and simple structure that is readily achieved by coining rather than sintering techniques and using, it is envisaged, nitrided steel with all the attendant advantages. Such teeth are relatively large and so contribute to enabling the movement of the slugs radially of a drive wheel without significant loss of driving efficiency.

I claim:

I. A train printer slug for use with a closed loop guide track having two parallel spaced outer guide tracks for slugs and an inner guide track for slugs spaced from and aligned with the gap between the outer tracks, the slug comprising a body element having a print character bearing portion, two parallel side walls flanking said body element to extend from the body element in a direction away from the character bearing portion to form with the body element a central guide channel for slidable co-operation with the inner guide track with each said wall providing on the surface thereof adjacent to the character bearing portion a laterally extending slide surface for sliding abutment with said'outer guide tracks; and a drive tooth flanking the central outer portion of each side wall each said tooth being profiled for driving co-operation with means for driving the slug along the track.

2. A train printer slug as claimed in claim 1, in which each side tooth has a surface which is flush with the slide surface of the adjacent side wall and which acts as an extension of the slide surface.

3. A train printer cartridge for driving a plurality of non interconnected toothed print slugs around a closed loop path; including an-outer guide track unit having two spaced parallel outer guide tracks and an inner guide track spaced from and aligned with the gap between the outer tracks, said guide tracks defining a closed loop with a part circular section leading into a straight section which is co-operable with arectilinear printing station, a drive wheel assembly at said part circular section including on each side of the inner guide track a toothed wheel for meshing with the teeth on the slugs, the axes of rotation of the wheels lying-upon a perpendicular to the adjacent end of the inner track straight section; said outer track unit being so curved about and spaced from the inner track unit that the slugs during their transit around the part circular section can be displaced radially outwardly into a nonabutting position whilst maintaining driving engagement with the teeth and that the end of the straight section of the outer track is extended relative to that of the inner track to overlie a portion of the part circular section of the inner track the portion of the outer track'circular section merging with the extended straight portion being shaped to enable alignment of the slugs with the straight line section to commence in advance of said perpendicular whereby transformation of angular motion is achieved prior to aslug leaving the drive wheel assembly.

4. A train printer cartridge for driving a plurality of toothed print slugs around a guide track unit having two spaced parallel outer guide tracks defining a continuous slot an inner guide track spaced from and aligned with the slot between the outer tracks said guide tracks defining a closed loop with a part circular section leading into a straight section which is cooperable with a'rectilinear printing station and a slug drive assembly, including on each side of the inner guide track a toothed wheelfor meshing with the teeth 7 on the slugs, the axes of rotation of the wheels lying on a perpendicular to the adjacent end of the inner track straight section, said slugs each comprising a body element having a print character bearing portion which is able to project through the slot; two parallel sidewalls flanking said body element to extend from the body element in a direction away from the character bearing portion to form with the body element a control guide channel for slidable co-operation with the inner guide track and to provide on the surfaces thereof adjacent to the character bearing portion a laterally extending slide surface for sliding abutment with the outer guide tracks; and a drive tooth on each side wallfor driving co-operation with'the toothed wheels said outer track unit being so curved about and spaced from the inner track unit that the slugs during their transit around the in advance of said perpendicular whereby transformation of angular motion is achieved prior to a slug leaving the drive wheel assembly.

5. A train printer cartridge as claimed in claim 4, in which each side tooth of each slug has a slide surface which is flush with the slide surface of the adjacent side wall thereby to act as a lateral extension of the slide surface.

Claims

1. A train printer slug for use with a closed loop guide track having two parallel spaced outer guide tracks for slugs and an inner guide track for slugs spaced from and aligned with the gap between the outer tracks, the slug comprising a body element having a print character bearing portion, two parallel side walls flanking said body element to extend from the body element in a direction away from the character bearing portion to form with the body element a central guide channel for slidable cooperation with the inner guide track with each said wall providing on the surface thereof adjacent to the character bearing portion a laterally extending slide surface for sliding abutment with said outer guide tracks; and a drive tooth flanking the central outer portion of each side wall each said tooth being profiled for driving co-operation with means for driving the slug along the track.

3. A train printer cartridge for driving a plurality of non interconnected toothed print slugs around a closed loop path; including an outer guide track unit having two spaced parallEl outer guide tracks and an inner guide track spaced from and aligned with the gap between the outer tracks, said guide tracks defining a closed loop with a part circular section leading into a straight section which is co-operable with a rectilinear printing station, a drive wheel assembly at said part circular section including on each side of the inner guide track a toothed wheel for meshing with the teeth on the slugs, the axes of rotation of the wheels lying upon a perpendicular to the adjacent end of the inner track straight section; said outer track unit being so curved about and spaced from the inner track unit that the slugs during their transit around the part circular section can be displaced radially outwardly into a non-abutting position whilst maintaining driving engagement with the teeth and that the end of the straight section of the outer track is extended relative to that of the inner track to overlie a portion of the part circular section of the inner track the portion of the outer track circular section merging with the extended straight portion being shaped to enable alignment of the slugs with the straight line section to commence in advance of said perpendicular whereby transformation of angular motion is achieved prior to a slug leaving the drive wheel assembly.

4. A train printer cartridge for driving a plurality of toothed print slugs around a guide track unit having two spaced parallel outer guide tracks defining a continuous slot an inner guide track spaced from and aligned with the slot between the outer tracks said guide tracks defining a closed loop with a part circular section leading into a straight section which is co-operable with a rectilinear printing station and a slug drive assembly, including on each side of the inner guide track a toothed wheel for meshing with the teeth on the slugs, the axes of rotation of the wheels lying on a perpendicular to the adjacent end of the inner track straight section, said slugs each comprising a body element having a print character bearing portion which is able to project through the slot; two parallel side walls flanking said body element to extend from the body element in a direction away from the character bearing portion to form with the body element a control guide channel for slidable co-operation with the inner guide track and to provide on the surfaces thereof adjacent to the character bearing portion a laterally extending slide surface for sliding abutment with the outer guide tracks; and a drive tooth on each side wall for driving co-operation with the toothed wheels said outer track unit being so curved about and spaced from the inner track unit that the slugs during their transit around the part circular section can be displaced radially outwardly into a non-abutting position whilst maintaining driving contact with the teeth and that the end of the straight section of the outer track is extended relative to that of the inner track to overlie a portion of the part circular section of the inner track, the portion of the outer track circular section merging with the extended straight portion being shaped to enable the alignment of the slugs with the straight line section to commence in advance of said perpendicular whereby transformation of angular motion is achieved prior to a slug leaving the drive wheel assembly.