US3774531A - Print chain assembly for high speed printer - Google Patents

Abstract

A print chain structure for a high speed printer, wherein an endless dual timing belt has a series of teeth on an inner surface thereof for engagement with a belt driving mechanism. The belt also has a series of teeth on its outer surface. A series of printing elements include interruptions which mechanically and removably cooperate with interstices of the teeth on the outer surface of the belt so that the belt-driving mechanism may efficiently drive the printing elements and the elements may be readily removed for servicing when the need arises. An improved guiding means is also provided for controlling the high speed movement of the printing elements with the belt.

Description

United States Patent 1 Hansen et ,al.

[ Nov. 27, 1973 PRINT CHAIN ASSEMBLY FOR HIGH SPEED PRINTER [75] Inventors: Robert L. Hansen; Clyde C. Roshon,

both of San Jose, Calif.

[73] Assignee: International Business Machines Corporation, Armonk, NY.

[22] Filed: June 21, 1971 [21] Appl. No.: 155,003

52 us. or. 101/93 (3, 101/111 51 Int. Cl B41j 5/08 [58] Field of Search 10l/93 C, 111, 109,

[56] References Cited UNITED STATES PATENTS 2,222,333 11/1940 Wenz/eletal 101/381 2,643,609 6/1953 Gottscho.... l0l/377 2,936,704 5/1960 Hense 101/93 C 3,209,682 10/1965 Cooper et al.. 101/109 3,379,125 4/1968 Antonucci 101/93 C 3,402,657 9/1968 Potter et al.... 101/111 X 3,416,442 12/1968 Brown et al.... 101/93 C 3,577,919 5/1971 Hinze 101/93 C 3,621,778 11 1971 Rippleet a]. ..,101/93 c l/l972 Edwards lOl/lll 2/1972 Dr eja et al. lOl/93 C OTHER PUBLICATIONS IBM Technical Disclosure Bulletin-VoL 13 No. 11 April 1971 Pages 3366-3367.

[57] ABSTRACT A print chain structure for a high speed printer, wherein an endless dual timing belt has a series of teeth on an inner surface thereof for engagement with a belt driving mechanism. The belt also has a series of teeth on its outer surface. A series of printing elements include interruptions which mechanically and removably cooperate with interstices of the teeth on the outer surface of the belt so that the belt-driving mechanism may efficiently drive the printing elements and the elements may be readily removed for servicing when the need arises. An improved guiding means is also provided for controlling the high speed movement of the printing elements with the belt.

5 Claims, 6 Drawing Figures PAIENTEBnnv 2 7 I975 SHEET 1 BF II I] II [I II II II II II 1}" II III! ll II III FIG.1

INVENTORS ROBERT L.HAN$EN CLYDE C ROSHQN ATTORNEY PRINT CHAIN ASSEMBLY FOR HIGH SPEED PRINTER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a chain printer, and 'more particularly to a structure for movably supporting a series of printing elements in high speed chain printers.

2. Description of the Prior Art In chain printers of a type commonly usedtoday, a chain of uniformly spaced apart print elements or type slugs is moved at constant speed in a continuous path. A portion of the path is located on a print line extending transversely of a record receiving web, such as a paper. The paper is fed intermittently, line by line, into registry with the print line, by a feed mechanism that is controlled either manually or electronically. A plurality of hammers located respectively adjacent toprint columns in the print line, are operated selectively by computer controlled electronic firing circuits to impress a selected type character of a print element against a ribbon and paper backed by a platen, as that type character moves into registry with a print column near which the selected hammer is located.

The aforementioned chain of print elements has most commonly involved the provision of an endless carrier loop, which comprises either a series of interconnected links or a unitary flexible belt. The flexible belt is considerably less expensive than the interconnected links,

and provides superior service-free performance and long life for many high speed printer applications. For attaching the print elements to the flexible belt, various techniques have been utilized in the prior art. One such technique has been to rivet to the belt a supporting shoe, which serves as a carrier for each'of the type ele ments. Another approach has been to couple each printing element to the flexible belt by means of me-.

ements and an endless flexible belt, which enhances the servicability of the printing elements while at the same time affording substantial economy in manufacturing and material costs.

SUMMARY OF THE INVENTION An important object of this invention is to provide an extremely reliable print chain assembly for high speed chain printers, which includes an endless belt that supports a plurality of readily disassemblable type elements.

Another object of this invention is to provide an improved print chain assembly which includes an endless dual timing belt and a plurality of printing mechanisms removably and mechanically coupled to the belt.

A further object of the present invention is to provide an improved print chain assembly which incorporates a dual timing belt having teeth disposed on its inner and outer surfaces, and a plurality of printing elements drivably and removably cooperable with the teeth on the outer surface of the belt.

In carrying out my invention in one form thereof, it is applied to a high speed chain printer which includes a continuous or endless dual timing belt characterized by a series of accurately spaced teeth disposed on each of its inner and outer surfaces'The teeth on the inner surface of the dual timing belt are engaged by a belt driving means for driving the belt in a continuous predetermined fashion. A plurality of printing elements are disposed on the outer surface of the belt. These printing elements each include a supporting shoe having one or more outwardly facing interruptions formed on it. These interruptions cooperate with the teeth on the outer surface of the belt, to provide mechanical coupling between the elements and the belt. With such an arrangement, the belt driving means acts upon the inner teeth of the belt to concurrently drive both the belt and the printing elements, and the printing elements may be readily removed from mechanical cooperation with the belt for purposes of servicing. For guiding and controlling the movement of the elements with the belt, each shoe also includes a pair of resiliently operable guiding arms. These arms coact with a guiding shoulder of a printer cartridge to help accurately control the high speed movement of the printing elements.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing objects, features and advantages of this invention will beapparent from the following de- FIG. 3 is an enlarged view of a portion of the print chain assembly, to show in greater detail the interrelationships. of the print elements, belt and sprocket wheel;

FIG. 4 is a back view of the printer cartridge of FIG.

I Land FIG. 5 is an alternative embodiment of the printing element. r

FIG. 6 is a partially broken away, three-dimensional view of the printer cartridge.

DETAILED DESCRIPTION Referring now to the drawings, there is shown in FIGS. 1, 2 and 3 a front printing chain printer having a type carrier 10 which travels in a substantially vertical plane in front of a series of print hammers 12. A series of printing elements M are mounted on the type carrier 10. Each of the printing elements 14 resembles a hand having four flexibly movable fingers 16 (FIG. 3). The finger 16 has a type slug 17 secured to one of its faces near the free end thereof, to produce the selected character when each finger 16 is struck by the print hammer 112. The type slug orcharacter is pressed into engagement with a ribbon m and a record member 20 (FIG. I) that is backed by a suitable platen member 22.

The hammers l2;have faces which each traverse the I span of a plurality of adjacent print positions. Control of printing is accomplished by a suitable hold coil 23 which holds all hammers 12 in the retracted inoperative position and individual bucking coils 25 which are selectively actuated to release and cause the associated hammer to complete a cycle of operation. The character or printing slug 17 of the printing finger 16 selected is aligned before an appropriate protrusion on the face of the print hammer 12 so that the appropriate selected type slug 17 may be printed while the other type slugs 17 are not contacted by the hammer face and are consequently not printed. When the hammer 12 strikes the type slug 17 onto the platen member 22, the hammer rebounds and the hold coil flux reattracts the hammer to the inoperative position so that the hammer is then in a position to be selected for another printing position. The signal to energize the bucking coil is generated by a suitable control means. This control means provides stored coded data of the text to be printed for a complete line and this data is compared with the coded data representing the print element in position for printing at each print position. This print element position is established by the combination of a home pulse generated by the appropriate hand, and a column by column emitter at the input drive shaft. An equal compare produces a signal which is coupled to actuate the proper print hammer for printing the designated character at the designated print position. A similar operation is conducted at each time designated characters on the chain reach a print position, until the complete line is printed.

As further shown in FIGS. 1-4 of the drawings, the printer comprises a cartridge 24 wherein there is located the type carrier mounted to be driven by a pair of sprocket wheels 26. The wheels 26 are driven from a suitable drive motor. The cartridge 24 includes a front housing portion 28, and a rear housing portion 30, which are suitably fastened together to provide a compact type of removable support for the type carrier 10 and its printing elements 14. Rear housing portion 30 provides a base for supporting the type carrier and printing elements 14, and front housing portion 28 provides a cover for enclosing the carrier mechanism in the housing. When the front and rear housing portions 28, 30 of cartridge 24 are fastened together, they provide suitable guide surfaces, which will be described further hereinafter, that act to control the path of movement of the printing element 14.

To provide an efficient and economical means for driving the printing elements 14 while also enabling them to be readily removable from the cartridge 24, in accordance with the present invention, the type carrier assembly is specially constructed as shown in FIG. 3. Carrier 10 is an endless and flexible belt having on its inner surface a plurality of uniformly spaced internal teeth 32 between which there are locted a series of interruptions 34. Teeth 32 mesh with the external teeth of sprocket wheels 26. In similar manner to the inner surface of carrier 10, on its external surface, there is located a series of uniformly spaced external teeth 36 separated by a series of outwardly facing interruptions As further shown in FIG. 3, the four flexible fingers 16 of each printing element 14 extend upwardly from an integral interconnecting base portion 40. Also attached to base portion 40 of element 14, there is a shoe 42. The shoe 42 is constructed to provide a lower section 44, the bottom 44a of which includes a series of relatively fiat protrusions 48 uniformly spaced apart and separated from each other by interruptions 50. The size and spacing of the protrusions 48 and interruptions 50 of lower section 44 of shoe 42, is such that the profile thereof meshes with the size and'spacing of the external teeth 36 and outside interruptions 38 of the type carrier 10. As a result, the shoe 42, which supports each printing element 14, is removably interengageable with the external periphery of the type carrier 10, and may readily drive the printing elements 14 around the wheels 26.

As shown by FIG. 3, the shoe 42 of the printing element 14 has a breadth of generally the same size as the distance between the outer edges of the four fingers of element 14. In addition, from viewing FIG. 2, it will be noted that shoe 42 is considerably thicker than hands 16 and bight section 40. On the rear side of the shoe 42 (i.e. the left side of FIG. 2) there is a horizontal ledge 51 for supporting the bottom of bight section 40, and on the front side of shoe 42 (i.e., the right side of FIG. 4) there is an upwardly facing guiding section 52. The guiding section 52 includes a pair of outwardly extensive cantilevered arms 54 and 56 (FIG. 3). From viewing FIG. 3, it will be noted that one side of shoe 42 is positioned vertically relative to the type carrier or belt 10 by means of the engagement of protrusions 48 and interruptions 50 of the shoe with external teeth 36 and interruptions 38 of the carrier 10. The other side of the shoe 42 is generally positioned vertically for movement with the belt by means of the resilient engagement of guiding sections 52, and arms 54, 56 with a loopshaped downwardly facing shoulder 60 formed as part of a guiding groove on the rear housing portion 28. (See FIG. 2)

More specifically shown in three-dimensional in FIG. 6, the cartridge 24 comprises front and rear housing portions 28, 30, respectively, which are formed with guide surfaces 62, 64. These surfaces 62, 64 form a continuous slot slightly wider than the thickness of the printing finger l6 and guide the fingers as the type element 14 is driven in an endless path by the carrier or belt 10. The rear housing portion 28 is formed with a loop-shaped channel or groove sized to receive the carrier or belt 10 and the shoe 42 of the printing element 14 engaged therewith. The loop-shaped channel is partially formed by a shoulder 60, whose surface is in sliding contact with the guiding section 52 of the shoe 42 as the print element 14 moves along the channel. At the loop portions of the channel, the cantilevered arms 54 and 56 also come into sliding contact with the shoulder 60.

With carrier 10 being driven around sprocket wheels 26 at a relatively high rate of speed, the resilient cantileveredarms 54 and 56 engage in'cam-like fashion with the facing surface of shoulder 60 so that the flexible fingers 16 are maintained in a direction generally perpendicular or normal to the direction of movement of the carrier 10. In view of the resilient capability of the arms 54, 56, the printing elements 14 are continuously maintained in a desired position of vertical alignment relative to the flexible belt while the printer is in operation.

To provide continuous front to rear (or horizontal) alignment of the printing elements 14 (viewing FIG. 2) during their movement within the cartridge 24, a guiding surface 62 of cover housing portion 30 and guiding surfaces 64 of the base housing portion 28, are positioned in contiguity with adjacent front and rear faces of base portion 40 of the type element 14.

To enable any of the printing elements 14 to be readily removed from and replaced in the cartridge housing without disassembling the cartridge housing halves 28,

30, an access doorway 70 (FIG. 4) is provided in the rear housing portion 30. Doorway 70 is constructed so that it is disposed opposite the lower horizontal path of the print elements 14 so that any print element may be readily removed from the access doorway 70. When the printer is in normal operation, the doorway 70 is suitably closed by a door (not shown).

With such an arrangement as that described and shown, an economical dual timing belt may be conveniently used for the type carrier 10. Such a belt, which is of well known standard construction, is also readily available on the market and is low in cost. In view of the fact that the printing elements 14 are each driven by means of a profile or matching tooth type cooperation with external teeth and associated interruptions in the external periphery of the dual timing belt, the type elements may be readily removed for convenient servicing through an individual access doorway without removing the printer chain from its housing.

The actual print hammer actuator arrangement used may be of any particular type. The type hammer actuator shown in FIG. 2 is that disclosed in U.S. Pat. No. 3,460,469, entitledPrint Hammer Actuator, and assigned to the same assignee as the present invention. Such a hammer actuator assembly involves a plurality of print actuators 72 mounted in a side-by-side array. Each of the actuators 72 comprises a magnetic core structure 74 forming a substantially closed path shaped to form two laterally offset pole pieces 76, 78. The resilient hammer 12 is mounted with one point 80 fixed relative to the magnetic core structure 74 and another point 81 coupled to a movable magnetic member 82. The point 81 secured to the movable magnetic member is positioned so that the generation of a magnetic flux within the magnetic core structure 74 attracts the movable member 82 to complete a magnetic circuit and position the hammer 14 in a ready position. The bucking coils 25 are provided for selective energization to release the movable magnetic member 82 so that the hammer 12 produces one cycle of movement.

FIG. 5 shows a modification of the present invention wherein theprinting element and its supporting shoe are integrally constructed, such as for example, from a plastic material such as Delrin. Here, type element 114 includes a plurality of flexible fingers 116 and an integral shoe 142 that has a series of protrusions 148 and interruptions 150. The type slugs 117 may be integral, inserted mechanically, or molded in place. The type element 114 operates in substantially the same fashion as the type element 14, in cooperation with the dual belt carrier as previously described.

it will now therefore be seen that we have provided a new and improved technique for expeditiously driving printing elements from a type carrier or flexible belt. This structure readily lends itself to printer servicing, while also facilitating high speed operation in conjunction with a chain printer.

While in accordance with the Patent Statutes, we have described what at present are considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes or modifications may be made therein without departin from the present invention.

What we claim is:

l. A print chain assembly for high speed chain printers comprising:

a housing,

a pair of sprocket wheels having teeth thereon mounted within said housing;

means for rotatably supporting said wheels on spaced parallel axes;

a print chain trained about said wheels;

said print chain including an endless belt having uniformly spaced internal teeth on the inner surface thereof to mesh with the teeth of said wheels;

said belt also having a series of external teeth on the outer surface thereof;

and a plurality of printing elements spaced along the outer surface of said belt, each printing element including a base portion which meshes with at least one of said external teeth of the belt, so that the printing element engages said belt, thereby enabling said element to be driven by the belt along the belt path and yet is removable normal to the belt path;

guiding means disposed within said housing adjacent said belt and essentially parallel to said belt path for maintaining the base portion of each of said printing element in engagement with said belt, and

means included with said housing for permitting access to and removal of said printing elements from the housing.

2. The print chain essentially described in claim 1 wherein each printing element of the print chain includes at least one resilient finger having a type slug affixed to the free end thereof,

and said base portion connected to the other end of said finger,

said portion including a shoe portionhaving a series of teeth structured to mesh with the teeth of the outer surface of said belt.

3. The printer described in claim 2 wherein the teeth on the shoe portion of the printing element face in a first direction and said type slug faces in a second direction, said first and second directions being disposed in perpendicular relationship.

4. In a high speed printer, a print chain assembly comprising:

a housing;

a belt contained within said housing;

driving means disposed in said housing and engageable with one sideof said belt for driving said belt at high speed, the other side of the belt having a plurality of teeth;

a plurality of printing elements in contact with said belt, each having a shoe portion with teeth engaging and meshing with the teeth of the belt such that the printing elements are driven in a direction along the path of the belt, but are removable normal to the belt path;

loop-shaped guiding means located in said housing and adjacent said belt and essentially parallel to said belt path for maintaining said printing elements in engagement with said belt when said belt is driven by said driving means;

a pair of resilient arms associated with each of said printing elements and coactable with the loop portions of said guiding means for maintaining the printing elements generally normal to the belt during movement of the belt through the loop portions; and

means included with said housing for permitting access to and removal of said printing elements from the housing.

5. The printer described in claim 4 wherein said access and removal means housing includes a doorway located on one side of the housing in facial alignment with one of said printing elements coupled to said belt; said doorway being larger than and facing one of said ment with said doorway.

Claims (5)

1. A print chain assembly for high speed chain printers comprising: a housing, a pair of sprocket wheels having teeth thereon mounted within said housing; means for rotatably supporting said wheels on spaced parallel axes; a print chain trained about said wheels; said print chain including an endless belt having uniformly spaced internal teeth on the inner surface thereof to mesh with the teeth of said wheels; said belt also having a series of external teeth on the outer surface thereof; and a plurality of printing elements spaced along the outer surface of said belt, each printing element including a base portion which meshes with at least one of said external teeth of the belt, so that the printing element engages said belt, thereby enabling said element to be driven by the belt along the belt path and yet is removable normal to the belt path; guiding means disposed within said housing adjacent said belt and essentially parallel to said belt path for maintaining the base portion of each of said printing element in engagement with said belt, and means included with said housing for permitting access to and removal of said printing elements from the housing.

2. The print chain essentially described in claim 1 wherein each printing element of the print chain includes at least one resilient finger having a type slug affixed to the free end thereof, and said base portion connected to the other end of said finger, said portion including a shoe portion having a seriEs of teeth structured to mesh with the teeth of the outer surface of said belt.

3. The printer described in claim 2 wherein the teeth on the shoe portion of the printing element face in a first direction and said type slug faces in a second direction, said first and second directions being disposed in perpendicular relationship.

4. In a high speed printer, a print chain assembly comprising: a housing; a belt contained within said housing; driving means disposed in said housing and engageable with one side of said belt for driving said belt at high speed, the other side of the belt having a plurality of teeth; a plurality of printing elements in contact with said belt, each having a shoe portion with teeth engaging and meshing with the teeth of the belt such that the printing elements are driven in a direction along the path of the belt, but are removable normal to the belt path; loop-shaped guiding means located in said housing and adjacent said belt and essentially parallel to said belt path for maintaining said printing elements in engagement with said belt when said belt is driven by said driving means; a pair of resilient arms associated with each of said printing elements and coactable with the loop portions of said guiding means for maintaining the printing elements generally normal to the belt during movement of the belt through the loop portions; and means included with said housing for permitting access to and removal of said printing elements from the housing.

5. The printer described in claim 4 wherein said access and removal means housing includes a doorway located on one side of the housing in facial alignment with one of said printing elements coupled to said belt; said doorway being larger than and facing one of said printing elements when the latter is in alignment with said doorway, to facilitate the ready removal and replacement of the printing element in alignment with said doorway.

Images