US3633500A

US3633500A - Means mounting type slugs on toothed belt in chain printers

Info

Publication number: US3633500A
Application number: US837085A
Authority: US
Inventors: James H Edwards; Alan M Swett
Original assignee: Mohawk Data Sciences Corp
Current assignee: DECISION DATA Inc A CORP OF; NationsBank of Texas NA; Mohawk Systems Corp
Priority date: 1969-06-27
Filing date: 1969-06-27
Publication date: 1972-01-11
Anticipated expiration: 1989-01-11
Also published as: FR2051192A5; DE2031173A1; DE2031173B2; GB1243617A; CA927673A; JPS4948005B1; DE2031173C3

Abstract

A chain printer containing a type chain which comprises a belt having a toothed side and which carries channel-shaped printing slugs along the print line. The web of each channel-shaped slug abuts the nontoothed side of the belt and has type characters thereon. The slugs'' flanges project across the edges of the belt and a pair of pins hold each slug at alternate teeth on the belt by extending between the flanges and projecting into holes therein. Each pair of pins abuts the opposite sides of a tooth and the adjacent side of the belt. A driving pulley moves the belt with a set of peripheral notches which mesh with those teeth not abutted by pins; a second set of peripheral notches is provided in the pulley for accommodating the abutting teeth and pins. When traveling around the pulley, the flanges pass over the pulley''s sides and thereby guide the belt and slugs.

Description

United States Patent [72] Inventors James H. Edwards Winchester; Alan M. Swett, Milton, both of Mass. [21] App1.No. 837,085 [22] Filed June 27, 1969 [45] Patented Jan. 11, 1972 [73] Assignee Mohawk Data Sciences Corporation Herkimer, N.Y.

[54] MEANS MOUNTING TYPE SLUGS 0N TOOTl-IED BELT IN CHAIN PRINTERS 10 Claims, 7 Drawing Figs.

[52] U.S.Cl 101/111 [51] Int. Cl B41jl/20, B4lj 1/30 [50] Field of Search 101/93 C, 93, 96,111,109, 383, 368

[56] References Cited UNITED STATES PATENTS 2,267,661 12/1941 Meyers 101/111 2,936,704 5/1960 Hense 101/93 3,041,964 7/1962 Simpson et al 101/111 3,041,965 7/1962 Sasaki 101/111 3,142,249 7/1964 Sasaki 101/111 Primary Examiner-William B. Penn Attorneys- Francis J. Thomas, Richard H. Smith, Thomas C. Siekman and Sughrue, Rothwell, Mion, Zinn and Macpeak ABSTRACT: A chain printer containing a type chain which comprises a belt having a toothed side and which carries channel-shaped printing slugs along the print line. The web of each channel-shaped slug abuts the nontoothed side of the belt and has type characters thereon. The slugs flanges project across the edges of the belt and a pair of pins hold each slug at alternate teeth on the belt by extending between the flanges and projecting into holes therein. Each pair of pins abuts the opposite sides ofa tooth and the adjacent side ofthe belt. A driving pulley moves the belt with a set of peripheral notches which mesh with those teeth not abutted by pins; a second set of peripheral notches is provided in the pulley for accommodating the abutting teeth and pins. When traveling around the pulley, the flanges pass over the pulleys sides and thereby guide the belt and slugs.

PATENTED JAN] 1 I972 3533500 saw 1 OF 4 INVENTORS JAMES H. EDWARDS ALAN M. SWETT ATTORNEY PATENTED JAN] 1 1972 31633500 SHEET 3 BF 4 PATENTEU JAN] 1 I972 SHEET 4 UF 4 MEANS MOUNTING TYPE SLUGS ON TOOTHED BELT IN CHAIN PRINTERS BACKGROUND OF THE INVENTION This invention relates to chain printers and, more particularly, to a type chain in such a printer and to the means used to move and guide the type chain.

Printers have been developed in which a type chain comprising type characters on a chain of printing slugs secured to a belt is moved along a print line across the document. In these printers, commonly called chain printers, one or more hammers adjacent the print line selectively strike a document against the moving type characters.

However, problems peculiar to chain printers have been encountered. The slugs must be positioned on the belt at precise locations and a suitable way of securely fastening the slugs onto the belt is required.

Another problem is found in guiding the moving chain with the necessary accuracy to enable the hammers to precisely strike the type character at the proper time. Without such precise hammer impact, poor registration of the type characters on the paper will occur. Mechanical and magnetic devices have been used. However, these devices, by contacting the slugs or belt, generate undesirable noise and friction. In some cases lubrication even is required.

In some chain printers, replacement of an individual printing slug requires the removal of a large number of slugs from the belt and is a time-consuming job. Difi'iculties have been encountered in developing printing slugs which may be easily removed from the belt for replacement, yet remain securely fastened during printing operations.

SUMMARY OF THE INVENTION It is, therefore, the primary object of this invention to provide a chain printer in which the above problems are overcome and yet is economical to manufacture and maintain.

In accordance with the invention, there is provided a chain printer having a type chain comprising a plurality of printing slugs, each of which has a printing portion and upper and lower portions cantilevered from the printing portion. These slugs are secured to a movable belt having a toothed side. The printing portion of each slug abuts a nontoothed side of the belt and its upper and lower portions project across the belt's edges. At least one pin, extending between the upper and lower portions of each slug, securely fasten each slug to the belt. Preferably, a pair of pins abuts the opposite sides of a tooth at which the slug is located and the adjacent side of the belt. By simply removing the necessary pins the slugs may be individually and easily replaced.

The belt is driven by a driving pulley having two sets of peripheral notches. One set meshes with at least some of the belts teeth and drives the belt. The other set accommodates the pins and, in the preferred embodiment, also those teeth abutting the pins as the belt travels around the pulley. When moving around the pulley the upper and lower portions of the slugs pass over the sides of the pulley and effectively guide the type chain.

Additionally, a member is placed adjacent the print line to resist the impact of the hammers as they force the slugs and document together. Another member stops the slugs upon their rebound from the impact resisting member. However, except when performing their respective functions, neither of these members contact the moving belt or slugs.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a schematic perspective view of a preferred embodiment of the printer.

FIGS. 2 and 3 are perspective views of a printing slug attached to the belt.

FIG. 4 is a perspective view of a pin used to secure the slugs onto the belt.

FIG. 5 is a plan view, partly in section, showing the driving pulley moving the print chain.

FIG. 6 and 7 are sections taken along lines 66 and 7--7 in FIG. 5 respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 schematically shows a chain printer printing on a document I which bends around guide bars 2 while being moved upwardly by a pair of tractors 3 engaging edge perforations la in the paper. The printer includes a plurality of hammer mechanisms disposed along the print line, i.e., that line along which characters are being printed. Each hammer mechanism contains a hammer 4a which, when activated by an electromagnet 4b, moves about its pivot 4c. One or more fonts of type characters are moved along the print line adjacent the hammers 4a by a type chain moving at a constant speed in a fixed revolving path. The type chain comprises a plurality of printing slugs '5 on which the type characters are located and an endless flexible belt 6, (FIG. 5) on which the slugs 5 are secured. During a printing operation, the proper hammer mechanisms are activated so that their hammers impact an inked ribbon 7 and the document 1 against selected type characters on the slugs 5. The inked ribbon is located between the document 1 and the type chain and is fed from a supply spool onto a takeup spool 8b.

The type chain is moved around a pair of pulleys: an idler pulley 9a, and a driving pulley 9 which is driven by means not shown located within a printer support 10. A conventional code disk 12 is mounted on the shaft 13 of the idler pulley 9a. It contains a plurality of radial slots which represent the rotating type characters and a further slot for indicating the end of each font. Light from a light source 15 is directed onto the code disk and passes through the slots therein and onto a photosensitive unit 14. By this well-known arrangement, the photosensing unit produces electrical outputs representing the positions of the type characters in the moving type chain. Such electrical signals are then used to properly time the activation of the hammer mechanisms.

As shown in FIGS. 2 and 3, the belt 6 of the type chain has a toothed side 6a on which a plurality of equally spaced teeth 16 are located. The belt is formed from fiberglass-reinforced neoprene and is of a type currently manufactured by the US. Rubber Company as a timing belt. The nontoothed smooth side 6b of the belt is abutted by the printing portions 17 of the slugs 5. Each slug 5 is channel shaped with the printing portion being the channels web and having one or more type characters 18 thereon. Four raised type characters are located on the slug illustrated. By using a plurality of type characters on each slug the printing speed may be increased with respect to the revolving speed of the type chain. The type characters are located equidistant from the top and bottom of the slugs, so

that the hammers do not tend to overturn the slugs when providing impact between the type characters and document. The flanges of the channel-shaped slugs,.their upper 19 and lower 20 portions, are cantilevered from the printing portions 17 of the slugs and project across the belts edges. If desired, the upper 19 and lower 20 portions can have slots therein to accommodate the belt where they project over the belts sides. The upper and lower portions each have a ledge, 21 and 22, at their cantilevered ends, i.e., their ends furthest away from the printing portion 17. Each ledge and the upper or lower portion on which it is located has a pair of holes 23. Extending between the upper and lower portions and projecting into the holes 23 therein are a pair of pins 24.

As shown in FIG. 4, the pins are elongated coil springs commonly called Spirol Pins. When installed, each pin is wound upon itself and its diameter thuscompressed, placed in the holes 23 and thereafter allowed to.expand. The pins abut both the opposite sides of a tooth I6 and the adjacent side of the belt 60 on which the teeth 16 are placed. So located, each pair of pins securely fasten a slug to the belt, yet by compressing and removing the pins, the slugs may be easily removed from the belt. In addition, each slug may be individually removed from the belt by merely taking out the pair of pins which secure it thereto.

F IG. 5 illustrates the method in which the belt is driven by the driving pulley 9. The pulley has two differently sized sets of peripheral notches 30 and 31. A pulley of this configuration may be easily constructed from a gear having equally spaced peripheral teeth by merely removing every third tooth. The printing slugs S are located at alternate teeth on the belt 6. Those teeth not abuted by a pair of pins 24 mesh with the notches 31 in the pulley formed by adjacent gear teeth. Those notches 30 of the pulley formed by removing one of the gears teeth accommodate the abutting pins and teeth. Thus, the belt is accurately driven by the pulley via one set of the pulley s notches and those teeth not abutted by pins. Of course, the idler pulley 90 around which the type chain also travels has two similar sets of notches to accommodate the teeth 16 and pins 24.

The cantilevered ends of the upper and lower portions, 19 and 20, of the printing slugs 5 have their corners removed so that the cantilevered ends of the upper and lower portions are smaller than their ends adjacent the printing portions 17 of the slugs. Since these ends are closest to the centers of the driving and idler pulleys when the type chain moves around them, movement of the slugs around the pulleys is facilitated. Removal of the slugs corners also has the desirable effect of concentrating the mass of each slug toward its center and thus enhances the stability of the slugs.

As shown in FIGS. 5 and 6, when the slugs 5 travel around the driving pulley 9 their upper and

lower portions

19 and 20 pass over the pulleys sides. Similarly, at the other end of the type chain they travel over the sides of the idler pulley 90. With sufficient tension maintained in the belt, the upper and lower portions sufficiently guide the entire type chain in this manner.

FIGS. 1, 5 and 7 show an impact resisting member disposed between the pulleys 9 and 9b and between the type chain. It is an essentially fiat member having concave ends which adjoin the driving and idler pulleys. The impact resisting member is located adjacent the print line and provides the backstop neces ary to resist the impact from the force of the hammers 4a as they force the document against the inked ribbon and type characters 18 on the slugs. By rebounding from the slugs and the impact resisting member, the hammers return to their initial positions. When a hammer is operated to strike a type character on a slug, that slugs upper and lower portions are forced against the impact resisting member. How ever, when they are not being forced together, a slight clearance is provided between the impact resisting member and me printing slugs. The slugs do not contact or ride along the impact resisting member and noise and friction is avoided.

FIGS. 5 and 7 also show a stop member 26 secured adjacent the print line to the impact resisting member 25 with screws 27. The stop member 26 has a lip 28 extending parallel to the print line and placed adjacent those ends of the ledges 21 disposed away from the cantilevered ends of the upper portions of the slugs. With this arrangement the stop member 26 prohibits the printing slugs from rebounding an unsatisfactory distance away from the impact resisting member 25 after the slugs are impacted by the hammers. As with the impacting resisting member, clearance is provided between the stop member 26 and the slugs 5, thus avoiding noise and friction. The ledges, 2 and 22 on the upper and lower portions of the slugs have an additional function; they provide an enlarged bearing surface between the slugs and the impact resisting member 25 when operation of the hammers force the two together.

Even though the slugs 5 do not ride on the impact resisting member 25, impact between these member during the printing operation causes wear. To minimize such wear, the slugs are preferably made of beryllium copper and the impact resisting member of hard-coated aluminum. Dispersion of a lubricative material, such as Teflon, in the hard coating is also preferred. Such materials provide the desired hardness and lubrication between the members. However, the slugs may also be made of hardened steel of metal-coated plastic and the impact resisting member of chrome-plated steel.

in summary, the print chain is effectively guided by the upper and lower portions, 1? and 20, of the slugs 5 as they pass over the sides of the driving and idler pulleys, 9 and 9a. Each slug 5 may be easily and individually removed from the belt 6 by removing a pair of pins 24, although each pair of pins abutting both the opposite sides of a tooth l6 and the belt itself securely fasten each slug to the belt. Noise and friction is avoided by clearances between the slugs 5 and the impacting resisting member 25 and the stop member 26.

We claim:

1, A type chain assembly comprising:

a. a movable flexible belt having first and second sides;

b. a plurality of spaced teeth located on the first side of the belt;

c. a plurality of printing slugs, each slug having a printing portion with at least one type character thereon abutting the second side of the belt, each slug also having at least one portion cantilevered from the printing portion and projecting across an edge of the belt;

d. at least one member securing each slug to the belt, the

securing members extending from the cantilevered portions of the slugs, positioned on the first side of the belt and located at some of the teeth; and

e. a driving pulley for moving the belt, the pulley having at least two sets of peripheral notches, one set adapted to mesh with some of the teeth, another set adapted to accommodate the securing members and the teeth at which they are located when the belt moves over the pulley.

2. The type chain assembly as recited in claim 1 wherein a pair of securing members extend from the cantilevered portion of each slug, each pair of members abutting opposite sides of a tooth on the first side of the belt.

3. The type chain assembly as recited in claim 2 wherein the notches in the pulley in the two sets are alternately arranged, alternate teeth on the belt are abutted by the securing members and the teeth on the belt are uniformly spaced.

4. The type chain assembly as recited in claim 2 wherein each pair of securing members also abuts the first side of the belt.

5. The type chain assembly as recited in claim 2 wherein each slug has two cantilevered portions which project across opposite edges of the belt and the securing members comprise pins projecting from the slugs cantilevered portions.

6. The type chain assembly as recited in claim 5 wherein each of the cantilevered portions of each slug contains a pair of holes and each securing member is a pin extending between the two cantilevered portions of a slug and projecting into a hole in each portion.

7. The type chain assembly as recited in claim 2 wherein at least part of the cantilevered portions of the slugs are adapted to pass over the sides of the driving pulley when the belt travels over the pulley.

8. A type chain assembly comprising:

a. a movable belt having first and second sides;

b. a plurality of spaced teeth located on the first side of the belt;

. a plurality of printing slugs, each slug having a printing portion with at least one type character therein abutting the second side of the belt, each slug also having at least one portion cantilevered from the printing portion and projecting across an edge of the belt;

d. at least two pins securing each slug to the belt, the pins extending from the slugs cantilevered portion, positioned on the first side of the belt, and abutting opposite sides of a tooth; and

e. a driving pulley for moving the belt, the pulley having at least two sets of peripheral notches, one set adapted to mesh with some of the teeth, another set adapted to accommodate the pins and the teeth they abut when the belt moves over the pulley.

9. The type chain assembly as recited in claim 8 wherein each pair of pins also abut the first side of the belt.

10. The type chain assembly as recited in claim 8 wherein each slug has two cantilevered portions which project across opposite edges of the belt, each of the two cantilevered portions contains a pair of holes, and each pin extends between the two cantilevered portions of a slug and projects into a hole 5 in each portion.

Claims

1. A type chain assembly comprising: a. a movable flexible belt having first and second sides; b. a plurality of spaced teeth located on the first side of the belt; c. a plurality of printing slugs, each slug having a printing portion with at least one type character thereon abutting the second side of the belt, each slug also having at least one portion cantilevered from the printing portion and projecting across an edge of the belt; d. at least one member securing each slug to the belt, the securing members extending from the cantilevered portions of the slugs, positioned on the first side of the belt and located at some of the teeth; and e. a driving pulley for moving the belt, the pulley having at least two sets of peripheral notches, one set adapted to mesh with some of the teeth, another set adapted to accommodate the securing members and the teeth at which they are located when the belt moves over the pulley.

5. The type chain assembly as recited in claim 2 wherein each slug has two cantilevered portions which project across opposite edges of the belt and the securing members comprise pins projecting from the slugs'' cantilevered portions.

8. A type chain assembly comprising: a. a movable belt having first and second sides; b. a plurality of spaced teeth located on the first side of the belt; c. a plurality of printing slugs, each slug having a printing portion with at least one type character therein abutting the second side of the belt, each slug also having at least one portion cantilevered from the printing portion and projecting across an edge of the belt; d. at least two pins securing each slug to the belt, the pins extending from the slug''s cantilevered portion, positioned on the first side of the belt, and abutting opposite sides of a tooth; and e. a driving pulley for moving the belt, the pulley having at least two sets of peripheral notches, one set adapted to mesh with some of the teeth, another set adapted to accommodate the pins and the teeth they abut when the belt moves over the pulley.

10. The type chain assembly as recited in claim 8 wherein each slug has two cantilevered portions which project across opposite edges of the belt, each of the two cantilevered portions contains a pair of holes, and each pin extends between the two cantilevered portions of a slug and projects into a hole in each portion.