Title:
FORCE ADJUSTMENT IN IMPACT PRINTERS
United States Patent 3823667


Abstract:
A plurality of self-restoring equally spaced apart print hammers selectively are driven lineally toward a printing position by continuously rotating impellers having equiangularly spaced radial impelling elements. Each impeller is effective through the agency of a rockable interponent, which is selectively elevated into the path of associated impelling elements upon latching of the armature of an electromagnet, for transmitting impeller force to a corresponding print hammer. An elastomeric bumper, disposed in the path of the print hammers, dampens printing force on dies, which are conveyed past said hammers for printing, in equally spaced relationship different from the spacing of said hammers. Each die, when at a printing station, is aligned with a print hammer but spaced therefrom a distance inversely proportional to its printing area for producing copy of uniform intensity.



Inventors:
BABLER E
Application Number:
05/268237
Publication Date:
07/16/1974
Filing Date:
07/03/1972
Assignee:
TELETYPE CORP,US
Primary Class:
Other Classes:
101/93.31, 101/111
International Classes:
B41J1/20; B41J7/94; B41J9/10; B41J9/26; B41J9/32; B41J9/42; (IPC1-7): B41J9/12
Field of Search:
101/93C,111,368 197
View Patent Images:
US Patent References:



Other References:

bear et al., "Print Hammer Impact Control Mechanism," IBM Technical Disclosure Bulletin, Vol. 5, No. 11, Apr., 1963, pp. 27-29..
Primary Examiner:
Pulfrey, Robert E.
Assistant Examiner:
Coven, Edward M.
Attorney, Agent or Firm:
Appel, Sherman Landis John P. L.
Claims:
I claim

1. In a printer having means for selectively driving a print hammer for movement in a lineal path between a non-printing position and a printing position, and a carrier arranged with said hammer for relative movement to successively align carrier supported dies with said hammer for printing by impact with force generated against an aligned die by said hammer, means for decreasing the printing impact of said hammer as the distance of hammer movement along the lineal path increases comprising:

2. A combination according to claim 1 characterized by means for adjusting the spacing of said hammer and an aligned die.

3. A combination according to claim 2 characterized by means for moving said carrier in a circuitous path, and means for adjusting said dies transversely of said carrier toward and away from said hammer.

4. A combination according to claim 3 wherein said carrier has a hammer proximate side and a hammer distal side, and said adjusting means comprises an adjustable stop fixed adjacent said carrier at said distal side for limiting the adjustment of said dies on said carrier.

5. A combination accoding to claim 1 characterized by:

6. A combination according to claim 1, including means for spacing said dies, when aligned for printing, varying distances from said hammer.

7. A combination according to claim 6 wherein said dies comprise a plurality of groups of different lengths, and the spacing means includes means for spacing each group from said carrier a distance different from the spacing of any other group.

8. A combination according to claim 6 wherein each die, when aligned for printing, is spaced from said hammer a distance inversely proportional to the printing surface area of the character on each die to be printed.

9. In a printer of the type wherein printing is effected by driving an impacting means toward a selected one of a plurality of dies, each die having a printing surface area, a mechanism for increasing the impact force of the impacting means on the selected die as the printing surface area of the selected die increases comprising:

10. In a printer of the type including means means for propelling a print hammer toward a selected one of a number of type dies to effect a printing operation, and means, engageable with a portion of the hammer as the hammer is propelled toward a type die, for damping the velocity of the print hammer prior to impact with the type die to absorb some of the hammer energy prior to printing, the improvement wherein:

11. A printer as recited in claim 10, wherein: the means for propelling includes means for initially positioning the hammer in the same position prior to propelling, regardless of the type character to be printed; and

12. A printer as recited in claim 11, wherein th damping means includes means for setting the distance between the type dies and the bumper in accordance with type face area so that the dies with the smallest printing area are positioned furthest from the bumper in the printing position.

13. A printer as recited in claim 12, wherein the type dies are formed at the inner ends of type support members, and further comprising:

14. A printer as recited in calim 13:

15. A printer as recited in claim 10, wherein the propelling means comprises:

16. A printer as recited in claim 15, further comprising:

17. In combination with a teleprinter of the type having a chassis, a resilient bumper mounted in the chassis along an axis Y, and a print hammer reciprocable along a printing axis X to engage a type member to print a character and arranged so that a portion of the print hammer strikes the bumper to dampen the hammer energy prior to impact with the type member, an improved hammer assembly characterized by:

18. A teleprinter assembly as recited in claim 17, further comprising:

19. A teleprinter as recited in claim 17, wherein the hammer rebounds after printing and wherein the front wall of the slot strikes the front wall of the bumper on rebound to dampen the hammer rebound energy, the bumper having resiliant front and rear walls engageable alternately with the front and rear walls of the slot.

20. A teleprinter as recited in claim 17, further comprising:

21. A teleprinter assembly as recited in claim 20, wherein the hammer is symmetrical about the axis X in a plane through the X axis perpendicular to the Y axis.

22. A teleprinter assembly as recited in claim 21, further comprising:

23. In a teleprinter assembly as recited in claim 17, of the type wherein the print hammer is propelled toward a slected one of a number of type dies to effect a printing operation, the improvement further characterized by:

24. A teleprinter assembly as recited in claim 17, further comprising:

25. A teleprinter assembly as recited in claim 24, wherein the means for striking comprises:

26. A teleprinter assembly as recited in claim 17, wherein the hammer comprises:

27. In combination with a teleprinter of the type having a print hammer linearly reciprocable along a printing axis X to engage a type member to print a character and arranged so that a portion of the print hammer strikes a resilient bumper to dampen hammer energy prior to impact with the type member, an improved hammer assembly comprising:

Description:
BACKGROUND OF THE INVENTION

The present invention relates to impact printers. More particularly, the invention relates to means for adjusting printing force in impact printers.

In printers of one class with which the present invention is concerned, printing may be effected in response to signals, a "line-at-a-time," on the fly, and at high speeds. In such printers, character dies or type are conveyed on a continuously moving endless carrier past print hammers which are actuated by a logic system responsive to data to be reproduced.

Ideally suited for developing impact forces in said class of printers, because of the high level of timing accuracy for print hammer control, are impelling means of the type disclosed in U.S. Pat. No. 2,927,960, issued to W. P. Byrnes, Mar. 8, 1960. In my copending application Ser. No. 286,238, filed contemporaneously herewith, there is shown and described an improvement for adapting the disclosure of said patent for high speed printing.

Heretofore unknown for printers with such impelling means are mechanisms for varying the printing forces such that image density is substantially uniform from one print-out period to another, regardless of the: (1) number of copies (within limits) simultaneously printed during each print-out period and (2) variation in the masses of printing dies within a font.

It is an object of the present invention to provide an improved impact printer.

It is another object of the invention in an impact printer to adjust the printing forces in accordance with the number of plies simultaneously being printed.

It is a further object of the invention in an impact printer to adjust printing forces according to the masses of the printing dies.

SUMMARY OF THE INVENTION

To attain the foregoing, and other objects of the invention which will become apparent from the ensuing detailed description, in a printer which has means for selectively driving a print hammer in a lineal path between a non-printing position and a printing position. A carrier and the hammer are relatively movable for successively aligning carrier supported dies with the hammer for printing. The impact of the hammer is adjusted according to the depth of material against which the impact is applied, the adjustment resulting from means for damping the driving force and disposed in the path of the hammer.

From another aspect, the objects of the invention are attained in an impact printer in which printing is effected by aligning a succession of dies with impact means. In such printer, means are provided for varying the printing force applied to the dies at the time of printing according to their printing areas.

BRIEF DESCRIPTION OF THE DRAWINGS

In the ensuing detailed description of the drawings, reference is had to the accompanying drawings on which:

FIG. 1 is a perspective view of an impact printer embodying one form of the invention, parts being broken away and parts omitted for the purpose of illustration;

FIG. 2 is a vertical sectional view of said printer according to the line 2--2 of FIG. 1;

FIG. 3 is an enlarged elevational view of a print hammer for said printer; and

FIG. 4 is a detailed view taken in a horizontal plane according to the line 4--4 of FIG. 2, parts having been omitted for the purpose of illustration.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1 of the drawings, the impact printer shown is generally designated 10. It has a pair of spaced apart pulleys 12 and 14 about which an endless carrier 16 is trained for translocating a plurality of pallets 18 by movement in a circuitous path. A plurality of dies 17 (FIG. 2) are carried on the front faces of the pallets, the latter being uniformly dimensioned and uniformly and equally spaced apart axially of the carrier. When the dies comprise alphanumeric characters, two or more successive fonts axially of carrier 16 may enable longer line output.

Carrier 16 and pallets 18, together with their mountings may be substantially as shown and described in the copending application of Francis E. Huntoon and James F. Kearney, Ser. No. 208,198, filed Dec. 15, 1971, and assigned to the assignee of the present application, now Pat. No. 3,742,848, granted July 3, 1973. In accordance with said last copending application, the plane in which parallel axes of pulleys 12 and 14 are disposed and the vertical section 20 of web 22 on which printing is about to occur are orthogonally disposed. Such arrangement generates a loop in the carrier with an upper or printing course 21 and a lower or return course 23 which are disposed in a plane which is substantially parallel to web section 20.

In the exemplary printer 10, pulley 12 is an idler sheave while pulley 14 is a drive sheave secured to a shaft 24. Driving torque continuously is transmitted to said shaft from an operating prime mover means, herein shown as a motor 26, through a drive train generally designated 28. The latter herein includes an impeller shaft 30. This shaft is continuously driven in the direction indicated by arrow 31 during printer operation.

A segment 32 of ribbon 34 is disposed in a plane substantially parallel to carrier course 21 between and spaced slightly from face 36 of web section 20 and the pallets 18 supported from said last course. The ribbon is trained about a plurality of ribbon guides 38 which are spaced apart such that the ribbon assumes a generally rectangular configuration in a horizontal plane. Opposed end portions of the ribbon are secured to a pair of adjoining ribbon spools 40 and 42 which alternately function for ribbon supply and accumulation. They alternately are driven in opposite angular directions, by a spool control mechanism 44, the details of construction of which form no part of the present invention. Mechanism 44 is connected to motor 26 through a pulley wheel 46, disposed in a common plane with spools 40 and 42. It is secured on an end portion 47 of shaft 24 for driving the spool control mechanism through a pulley belt 48.

A clutch 50, which may be conventional, is mounted for releaseably securing the split shaft section 52 to the shaft 24 from which said section extends axially. Selective actuation of the clutch may be effected through logic (not shown) which may be conventional and the details of construction of which form no part of the invention. Thereupon, operating means, being a drive train generally designated 54, advances web 22, in the direction shown by arrow 56, a line at a time. Such advancement results from incremental rotation of a worm gear 58 for driving a pulley belt 60 intermittently angularly to move a cylindrical roller 62. Roller 62 is disposed transversely of and adjacent to the path of web movement for frictionally engaging web 22 and in cooperation with other components (not shown), intermittedly drawing said web from its supply source (not shown) about a guiding cylinder 64, as said web is advanced.

Impelling means comprises an array of radially symmetrical impellers 66 (only representative ones of which are shown in FIG. 1). The impelling means herein are substantially as shown and described in my aforesaid copending applications Ser. No. 268,238 and in another application Ser. No. 268,236, also filed contemporaneously herewith. Accordingly, each impeller is comprised of a plurality of raidal, equiangularly spaced arms or impelling elements 68, the impellers being concentrically secured to shaft 30 for rotation therewith in the direction shown by arrow 70 (FIG. 2), in the exemplary embodiment. The impellers are axially or horizontally spaced such that each is disposed in substantially horizontal alignment with a printing station on an imaginary line extending horizontally across web section 20. Opposed end portions of the shaft 30 are journalled in spaced apart vertical side members 72 (only one is shown in FIG. 2) of the frame or chassis 74 of printer 10.

Impacter means for printing comprise a plurality of hammers 76 (only some of which are shown in FIG. 1) having enlarged printing heads 77 at their inner ends, the heads 77 being disposed behind back face 78 (FIG. 2) of web section 20. As shown in FIG. 4, each hammer is aligned with the others in a horizontal array parallel to the alignment of impellers 66 for linear reciprocating movement along a horizontal printing axis X, toward and away from an associated type die 17. As illustrated in FIGS. 3 and 4, the printing axes X refer to horizontal axes running longitudinally through the centers of the hammers 76, from left to right in those FIGS., and through the center of the type dies 17 when aligned with a hammer for printing, as shown in FIG. 3 and as shown for the first, third and fifth dies 17 from the top in FIG. 4. Each hammer also is aligned with, though spaced from, and disposed out of the path of movement of an associated impeller by which it can be selectively driven in a lineal path along printing axis X, perpendicularly to web section 20, between a normal or non-printing position (FIG. 1) and a printing position (dashed line of FIG. 4) in which the hammer head 77 engages against said back face 78 (FIG. 2).

The dies 17 on pallets 18 in course 21 and hammers 76 are disposed at a common horizontal level; and said pallets and their dies when translocated move in a path parallel to the hammer array for printing. Thereby, each pallet 18 and groups thereof can be moved successively into printing positions in horizontal alignment with successive hammers 76 and groups thereof, along printing axes X. The force generated by each impeller 66 for urging web section 20, ribbon segment 32 and any aligned dies 17 into contact is of sufficient magnitude for printing by forming an image of each such die on web face 78. In the exemplary embodiment of the invention, the hammers are associated with and reciprocatively arranged in chassis 74 by means and in the manner disclosed in said copending application Ser. No. 268,238. As described in that application, and as shown in this application each hammer 76 is elongated in the direction of its line of flight (axis X), and includes a rectangular body section 176, having the head section 77 formed at the inner or right end, as viewed in FIGs. 3 and 4, and having a relatively long, relatively thin, rectangular tail section 177 formed at the outer or left-end of the body section 176, and extending toward the associated impeller 66, as illustrated in FIG. 2. The outer or left end 178 of the tail section 177 is flattened as shown in FIGS. 1 and 4 for driving by one of the impeller arms 68 to propel the hammer 76, as will be explained hereafter. As illustrated in FIGS. 3 and 4, the hammer sections 77, 176 and 177 will extend in a straight horizontal line centered on the printing axis X.

Each hammer 76 is mounted in the printer chassis 74 for free linear reciprocating movement, along its printing axis X. For this purpose, the printer chassis 74 includes an upper horizontal wall 180 (FIG. 2) defining the base of a row of chambers 182 behind the web section 20 on which printing is to occur. The hammers 76 are slideably mounted in the chambers 182 against a transverse bearing bar 183 mounted on the wall 180. A chassis plate 184 has portions disposed in bearing engagement with hammers 76 and extends in a horizontal plane as a roof or cover for chamber 182. A slotted flange (not shown) depends from the plate 184 to provide horizontally aligned vertical guide slots between which the hammers are reciprocative, as shown and described in the copending application Ser. No. 268,238. These guide members in the frame serve to mount and guide the hammers 76 for precise linear reciprocation along the printing axes X, to print characters as will be described hereafter.

A horizontal bumper in the form of an elongated rod 80 is disposed parallel to shaft 30 along a horizontal axis Y (FIGS. 1 and 4) perpendicular to hammer axes X, and has opposed ends secured in the chassis sides 72. Said rod extends through horizontally aligned holes or slots 82 in the hammers 76 for limiting horizontal hammer movement along axis X, as illustrated in FIGS. 2 and 3, the slots are generally rectangular as viewed in the plane of FIGS. 2 and 3, and extend through the body section section 176 of each hammer in the direction of bumper axis Y. (The bumper axis Y refers to the perpendicular horizontal aixs running through the center of the bumper 80, from top to bottom in the layout of FIG. 4, or from left to right in FIG. 1.)

As shown in FIGS. 3 and 4, the bumper 80 has a portion received within the slot 82 of each hammer 76 in the row, and the height of the bumper 80 (from top to bottom in FIG. 3) is less than that of the slots 82 so that the hammers 76 may reciprocate with respect to the bumper along the printing axis X. However, the portion of the bumper 80 within each slot 82 is enclosed on all sides by walls of the slot 82, as shown in FIGS. 1 and 3, the slot 82 and body section 176 of the hammer being symmetrical above and below axis X, as viewed in the vertical plane of FIG. 3, so that the bumper is centered on axis X as is the slot 82.

A leaf spring 84 (FIG. 2) of general vertical orientation and associated with each hammer 76, is included in hammer driving means. It has a lower end portion which is rigidly secured to a front chassis plate 86 and an upper end portion engaged in a downwardly opening slot 88 in the printing head 77 of each hammer 76. Each hammer head 77 is also formed with an upwardly opening slot 89 (FIGS. 3 and 4) aligned with the slot 88 and of the same shape so that the hammer 76 is symmetrical above and below axis X, as viewed in FIG. 3. Each spring 84 has a slightly tensioned condition (FIG. 2) during which its hammer is in its rearward or most remote non-printing position, and a most tensioned condition (not shown) during printing for urging or restoring its hammer to non-printing position.

Each impeller 66 is adapted to move a printingly associated and aligned hammer 76 through the agency of an interponent 90. In the preferred embodiment of the invention, printing is effected and the assemblies of the interponents as well as the other parts of printer 10, including means for controlling and liberating the interponents are, as shown and described in said last named copending application. In accordance therewith, the interponents are disposed in general horizontal alignment and each has: (1) a first or upper position in which it is in a projected condition, with its upper free end portion disposed in the path of movement of associated impelling elements 68 for transmitting force from its impeller 66 to an aligned hammer 76 in consequence of which printing occurs, and (2) a lower, non-printing, or second position in which said interponent has fallen and is removed from the impeller path.

As shown and described in said application Ser. No. 268,238, each interponent 90 intermittently is controlled by an electromagnet assembly comprised of a magnetically latchable armature 92 and an electromagnet 94 (FIG. 2). Any suitable logic (not shown and forming no part of the present invention) which may be conventional may be employed for energizing each of said electromagnets 94 selectively. In consequence of energization of any electromagnet its armature will be rocked, magnetomotively, against the restoring bias of its spring 96 clockwise from its position shown (FIG. 2) to a latched position (not shown).

Correspondingly, an affected interponent will be thrust upwardly (from its FIG. 2 position) into its first position or projected condition (not shown) between a pair of adjoining impelling elements 68 against the lowering bias of an associated spring 98 which becomes tensioned upon upward movement of its interponent. Ensuingly, the upwardly thrust interponent will be engaged by a circuitously traveling impelling element 68 and rocked into engagement with an associated hammer 76 to effect momentum transfer and translation of impeller torque into a lineal force for printing. In the exemplary printer 10, both momentum transfer and restoration of an interponent to its second position (FIG. 2) following momentum transfer, as well as the conditioning of interponents 90 for repeat cycles are as shown and described in said last named copending application.

In the printer 10, as illustrated (FIG. 4), the hammers 76 are equally spaced apart and the pallets 18 in a font in course 21 are also equally spaced apart. However, the spacing between the centers of the hammers is not the same as the spacing between the centers of the pallets. Their spacing, as well as their dimensions, mode and sequence of operations, and printing with printer 10 are as shown and described in said copending application Ser. Nos. 268,238 and 268,236.

As shown in said Huntoon-Kearney patent pallets 18 are mounted on the inner ends of shanks 100; and the shanks are disposed in a horizontal plane and are removably mounted in carrier 16, extending transverely through its hammer proximate side 102 and hammer distal side 104. In accordance with the present invention, for adjusting the impact of each hammer 76 upon printing according to the depth of material against which the impact is applied, damping means is disposed in the path of hammer movement. Herein, said last means comprises a resilient or a viscous damper which may be an elastomer from which bumper 80 is fabricated. Thereby, the hammers and said damping means are arranged for relative movement. The disposition of the bumper in the hammer slot 82 is such that the bumper limits movement of each hammer in each of opposite directions along printing axis X by engagement with front and rear sides 106 and 108 (FIG. 3) of slots 82. In the initial or nonprinting position of the hammer 76, the leaf spring 84 biases the hammer to the left in FIGS. 3 and 4 to a rest position where the inner or front side wall 106 of the slot 82 engages an inner or front wall 109 of the bumper, as shown in FIGs. 2 and 3.

As best illustrated in FIGS. 2 and 3, the slot 82 is elongated along the X axis, compared with the width of the bumper 80 (from left to right in FIG. 3), so that a preset clearance or distance 110 is provided between the slot and bumper along the axis X of hammer flight. More specifically, the distance 110 between the rear wall 112 of bumper 80 and each rear side 108 of a slot 82, when its hammer 76 is in its normal position (FIG. 3) is such that, for the thickest number of plies of sheets of paper intended to be accommodated in the horizontal span 113, between the end face 114 of hammer head 77 and a die 17 aligned therewith for printing, side 108 will just come into engagement with wall 113, when said hammer face reaches printing position. Accordingly, to the extent that the thickness of the paper mass in span 112 is reduced from such maximum, each hammer 76 will move further to the right (relative to FIGS. 2 and 3), compressing the bumper 80 correspondingly, to reach printing position shown in phantom lines for the second hammer 76 from the top in FIG. 4. By fabricating bumper 80 of polyurethane material having a durometer Shore hardness of 90A, printing of good quality can be produced on as few as one sheet or on as many as six carbon copies, simultaneously without adjusting the distance across span 113.

Additionally, the bumper 80 is proportioned such that it serves to absorb rebound energy of the hammers 76 following printing as they are restored to normal positions (FIG. 1). As each hammer 76 rebounds to the left in FIGs. 3 and 4 from a printing operation, the inner or right side wall 106 of the slot 82 engages the inner or right side wall of the bumper 80 to absorb and dampen rebound energy, and thus facilitate return of the hammer 76 to the initial position resting against the bumper 80, by the biasing spring 84.

For adjusting the spacing of hammers 76 and pallets 18, that is, for setting the distance across span 113, the pallets are adjustable toward and away from the hammers. To that end a back-up bar or stop member 116 is supported from a frame or chassis member 18 along side 104 of carrier course 21. The back-up bar is engaged by the outer ends of shanks 100 in said upper course and is adjustable in a horizontal plane toward and away from carrier 16 within the limits of a slot 120 in said back-up bar. Means for releaseably securing the back-up bar in adjusted positions may comprise a threaded pin 122 passed through slot 120 from member 118 for holding a clamping nut 124 against the back-up bar.

From another aspect of the invention, the impact upon printing is adjusted according to the force transfer areas or sizes of the printing surfaces of the printing dies. This adjustment is for minimizing variation in copy intensity due to variation in the size of characters of the dies. For that purpose, the lengths of shanks 100 are varied according to the sizes of the printing surfaces of dies 17. If it is impractical to vary the lengths according to the size of the printing surface of each die, the variation may be according to sizes within selected ranges. Herein, three pallet groups 18A, 18B, and 18C are shown (FIG. 4). EAch group has a range of die sizes different from the size ranges of the others. Pallets 18 having dies whose sizes or printing areas are within the smallest range have the shortest shanks 100A. In an alphanumeric font, punctuation marks such as a period, and a colon belong in this last-named range. Dies whose printing areas are within the greatest size range have the longest shanks 100C. Examples of alphanumeric characters in this last named range are capitals M and W. Dies within the intermediate size range, such as many lower case letters, have shanks 100B of intermediate length.

Accordingly, a hammer 76 which is impelled toward a pallet carried on a shank 100A will travel the greatest distance for printing. Such hammer will compact the greatest damping mass in bumper 80. Consequently, when it strikes for printing, its impact force will be less than the impact force when printing with a die on a pallet carried on either a shank 100B or 100C; and such force will be dissipated over an area in the smallest range. On the other hand, a hammer printing with a die on a shank 100C will travel the least distance to printing position. Such hammer encounters less damping mass in bumper 80 before reaching printing position that a hammer printing with a die carried on either a shank 100A or 100B. Such hammer will have the greatest energy on impact; however, such force will be dissipated over a printing surface in the greatest range.

As many modifications in the described construction could be conceived, and as many widely different embodiments could be made without departing from the spirit and scope of the claims, it is intended that all matter contained in the accompanying specification shall be considered as illustrative only and not in a limiting sense.