US3185078A - Paper drive mechanism in a high speed printer - Google Patents

Description

y 1965 F. G. PENSAVECCHIA 3,185,078

PAPER DRIVE MECHANISM IN A HIGH SPEED PRINTER Filed Sept. 21, 1961 2 Sheets-Sheet l Farmdt Control INVENTOR Frank 6. Pensavecchl'a BY Wfir P ATTORNEY PAPER DRIVE MECHANISM IN A HIGH SPEED PRINTER Filed Sept. 21, 1961 May 25, 1965 F. G. PENSAVECCHIA 2 Sheets-Sheet 2 mkm INVENTOR Frank 6. Pensavecch/a United States Patent C) 3,185,078 PAPER DRIVE MECHANESM N A HIGH SEEED PEWTER Frank G. Pensavecchia, Urchard Lake, Mich, assigncr, lay mesne assignments, to Control Data Corporation,

Minneapolis, Minn, a corporation of Minnesota Filed Sept. 21, i961, Ser. No. 139,679 11 Claims. (Cl. 10193) This invention relates to printers for use with electronic computers, and particularly to a novel electro-mechanical, so-called, on-the-fiy type printer. More specifically, this invention relates to the means employed in the printer for advancing the paper or other record strip on which the characters are printed.

A complete description of a printer with which my invention can be used, is found in application Serial No. 138,157 entitled High Speed Printer. The pinter includes a continuously rotated print drum having characters spaced radially around the drum in horizontal rows of identical characters to be printed. Printing takes place by causing hammers to drive the paper into the characters on the drum.

The printer disclosed therein may be used in conjunction with a computer-buffer combination as a medium and/ or high speed data processing system. For example, the particular embodiment of the printer disclosed therein is capable of printing 120 character lines at a rate of 150 lines per minute, and under special circumstances at a rate of 600 lines per minute for all numeric characters. The computer derives the necessary information and places it on its output terminals in such a way that it is fed into the printer one line at a time. After the computer has completed the derivation of one line of information, it then derives the vertical format or number of lines which the computer desires to skip on a printed sheet before it prints the next line. This information is also fed out onto the computer output lines and used by the printer.

My invention is primarily concerned with the paper advance mechanism, various details thereof, and with the relationship of the paper advance mechanism and a for mat controlled device which is not only slaved to the paper advance mechanism but also imposes control commands to the advance mechanism. In this regard, one of the objects of my invention is to provide a single means for driving both the format control and the paper moving or advance mechanism of a printer.

Another object of the invention is to provide a means for the above purpose which is fast acting so as to accomplish paper advance between printing cycles in a minimum of time, thus, increasing the overall speed of the printer.

Another object of the invention is to provide a high energy, fast acting mechanical amplifier type mechanism for driving both the format control and paper moving mechanisms so as to maintain the total electrical power required at a low level.

A still further object of the invention is to provide a system of this kind wherein extremely low power electrical signals are employed to release and utilize an abundance of mechanical energy.

A further object of the invention is to provide an improved spring clutch mechanism for the above purpose, one of the improvements being in the means for precisely aligning the input and output portions of the spring clutch.

Another object of the invention is to provide a paper advance mechanism which prevents cumulative error in the vertical spacing of the lines of print.

Another object of the invention is to provide a detented paper advance mechanism providing a zero reference feature such that any error in the vertical spacing in a single line of print is limited to that particular line of print. In

3,185,6'38 Patented May 25, 1%55 other words, the mechanism prevents the addition of any error in a preceding line of print to succeeding lines of print.

Another object of the invention is to provide paper advance mechanism that will automatically advance the paper one line unless it is desired to skip one or more lines.

Another object of the invention is to provide a spring clutch mechanism having means for substantially eliminating backlash of the paper.

Another object of the invention is to provide a spring clutch mechanism to index the paper the same amount from line to line of print.

Another object of the invention is to provide a spring clutch mechanism adapted to drive all standard grades of paper and number of forms in the same length of time.

Still another object of the invention is to prevent the paper from backlashing more than a predetermined minimum amount so as to substantially maintain the paper in a single plane between the paper drive mechanism and the print drum so as to eliminate problems in character registration.

Another object of the invention is to provide a system in which the format control mechanism is driven by the spring clutch and controls disengagement of the clutch.

Another object of the invention is to provide a spring clutch mechanism having means to allow the output shaft of the spring clutch to coast only during the last few degrees of its total motion, thus holding the total cycle time at a minimum.

A further object of the invention is to provide a spring clutch mechanism controlling the backlash of the output shaft of the clutch by means of a lug formed on the output shaft engaging a shoulder of a clutch actuating shell which is connected to the clutch input shaft by means of the drive spring.

Another object of the invention is to provide a spring clutch mechanism having an auti-backlash pin located such that the total backlash of the clutch output shaft will be maintained at a minimum, resulting in an even lesser backlash on the paper tractor drive shaft.

Another object of the invention is to provide precise spring clutch mechanism in which the drive spring will disengage itself from the clutch input shaft only during the final few degrees of output shaft motion.

Another object of the invention is to provide a spring clutch mechanism that will insure precise operation over a long period of time and will operate without servicing for seventy million or more cycles.

Another object of the invention is to provide a spring clutch construction of proper materials so as to insure negligible wear, thus preventing the increase of backlash with use.

A still further object of the invention is to provide a spring clutch mechanism having a solenoid plunger and an anti-backlash pin, with the plunger and pin guide holes in the main support casting being positioned accurately so as not to defeat the object of maintaining the backlash to a minimum.

These and other objects and advantages of the invention will become apparent by reference to the following specification and the accompanying drawings, wherein:

FIGURE 1 is a schematic perspective view illustrating a portion of the drive system of the printer disclosed in the referenced application, and particularly illustrating the relationship of my paper advance mechanism and the format control device with the drive system of the printer.

FIGURE 2 is an exploded perspective view of the spring clutch which is schematically disclosed in FIGURE 1 and which drives both the paper advancing assemblies of the printer and the format control device.

FIGURE 3 is a fragmentary vertical sectional view showing the details of the clutch mechanism of FIGURE 2 as they appear with the clutch assembled, and also showing both drive and driven belts connected therewith.

My invention is primarily concerned with the paper advance mechanism, certain details thereof, and with the relationship of the paper advance mechanism with a format control. The format control is not only synchronized with the paper advance mechanism, but also imposes control commands to the paper advance mechanism.

As mentioned before, a printer with which my invention can be used is fully described in application Serial No. 138,157. To the extent pertinent here, the printer uses a main drive motor 107 (FIGURE 1) for driving substantially all of the movable parts of the printer, including the input shaft 117 of my spring clutch assembly 128. The drive connection to shaft 117 is schematically shown as motor shaft 107a, pulley 127, belt 129, and pulley 130. Pulley 121 attached to shaft 107a, and belt 124 represent the main drive motor connection with other parts of the printer.

Spring clutch assembly 128 (described in detail later) has an output shaft 118 to which pulleys 134 and 135 are secured. These have belts 140 and 138 engaged therewith. Belt 138 mechanically drives a format control or control device 375 through pulley 137, and belt 140 drives a paper tractor drive mechanism 139. Thus the tractor drive mechanism 139 and the format control 375 are synchronized.

For the purpose of my invention the format control 375 can be considered conventional (the details are found in the referenced application), consisting of a photoelectric reader for coded tape 429 providing commands or control signals over line 37 5b to clutch assembly 128 by way of OR gate 375d and line 3775a. The nature of the signals will depend upon the codes in the tape, while their timing and frequency are slaved to the paper advance mechanism via clutch assembly 128.

Tractor drive mechanism 139 together with the paper tractors 384 (only one shown) are also conventional, e.g., the latter being a Kidder Press Company, Model C-95 tractor. The illustrated tractor 384 includes a sprocket driver actuated by shaft 382 (connected with drive 139) and supported by a stationary guide shaft 383 and bracket. The paper 157 has sprocket holes engaged with the pins of the tractor.

The overall operation of the printer is such that it prints data one line at a time on paper 157. However, the format control 375 issues format commands (electrical signals over line 3751: and/or line 375a) for the tractors 384 to move paper 157 through distances equal to the spaces required for one line, two lines, or more lines at a time between line print cycles. Paper drive spring clutch assembly 128 is largely responsible for the satisfactory operation of this portion of the printer.

Assembly 128 includes a clutch, a solenoid actuating assembly 390 (FIGURE 2) and an anti-backlash assembly 391. The spring clutch 128a (FIGURE 2) has the aforementioned input shaft 117 which is. driven continuously (by motor 107). Shaft 117 is mounted in a hearing 423 (FIGURE 3) in one end of clutch housing 392 (FIGURE 3) which may be either separately formed integral with support member 102 constituting a part of the frame of the printer. Housing 392 is provided with a cavity 393 to receive the assembled spring clutch.

As seen in FIGURES 2 and 3 the inner end of input shaft 117 has a larger diameter part 394 having a radial flange 395 extending from the outer surface thereof. Axial bore 396 (FIGURE 3) is formed in the part 394 and in the input shaft 117. An annular oilite or other suitable bearing 394a is fitted over part 394 and against flange 395 to provide bearing surfaces for the shell or actuating sleeve 404 and the input end a helical coil spring 403 of rectangular cross section. Spring 403 is a preloaded main drive spring as more fully described later.

Output shaft 118 of the spring clutch is also mounted in member 102 and it is in axial alignment with the input shaft 117. Shaft 118 (FIGURE 3) is mounted in a suitable bearing 397 disposed in a separate mounting member 398 to provide access into the cavity 393. The previously mentioned pulleys and 134 are secured to the end of the output shaft by suitable conventional means.

The inner end of shaft 118 has an intermediate enlarged part 399, the left end (as shown) of which is formed with ratchet teeth or lobes 400. The circumferential lengths of the lobes are substantially equivalent to the space required for one line of print; while the other end of part 399 is formed. to provide oppositely disposed, axially extending lugs 401 extending over an intermediate reduced portion 402 of part 399 (FIGURE 2). The extreme end of shaft 118 has a pilot 118a and a bearing 405 to pilot in the axial bore 396. Portions 394 and 402 of the input and output shafts have precise, identical diameters, and spring 403 is disposed over these portions. The inner diameter of spring 403, when free, has an interference fit on portions 394 and 402 of the two shafts such that rotation of the input shaft 117 (when the spring 403 is free) causes the spring to wind tight on the two shafts in the manner of a self-energizing brake or clutch.

The clutch actuating shell or sleeve 404 is positioned over spring 403 in a manner such that the radially-extending toe 403a of the spring is engaged in slot 406 in the end of sleeve 404. The axially-extending toe 4014b at the opposite end of the spring engages the slot 408 formed in the ring 409 which is secured to the portion 402 of shaft 118 by set screws 410 (or the equivalent). Ring 409 serve as a bearing and a guide for the lugs 411 extending from the actuating sleeve 404, which mesh like gear teeth with the corresponding lugs 401 extending from the output shaft 118. When the output shaft 118 and sleeve 404 are made of metal, ring 409 may be of a suitable bearing material; on the other hand, ring 409 may be made of metal, such as steel, where the actuating sleeve 404 is made of plastic such as nylon or Delrin. The actuating sleeve 404 has ratchet teeth or lobes 412 formed on the outer surface thereof, the lobes being in the same number as lobes 400 on shaft 118 but extending in the opposite direction. The inner diameter of sleeve 404 is larger than the outer diameter of spring 403 in its free position so that the spring can be unwound to a larger diameter and thereby prevent its making mechanical connection between the input shaft and the output shaft and permit the input shaft to rotate free of the output shaft.

Solenoid assembly 390 (FIGURE 2) consists of a conventional solenoid 414 having an armature 414a which terminates in latch 413. The armature and latch are spring-loaded by spring 4141) in a direction to engage the latch with lobes 412 on the actuating sleeve. Thus, when the solenoid is not energized, latch 413 is normally engaged with the ratchet teeth or lobes 412.

The anti-backlash device 391 is made of a latch 415 loaded by a properly matched spring 416 in a direction so that the latch is always engaged against the lobes or ratchet teeth 400 on the output shaft 118.

Since the paper tractor drive 139 and the format control 375 are driven by the same shaft (118) they are always synchronized and are subject to motions of shaft 118 equally. This, of course, means that the benefits of, for example, the anti-backlash feature, are distributed equally to the paper tractor and to the format control.

From the foregoing it is understandable that the primary function of the paper drive and format control is to start, continue and stop the movement of paper 157. The start signal can originate from any source, for example, from a computer, buffer, etc. over line 375c. The stop signal can also be obtained from external sources and/or from the format control 375, the latter alternative being schematically shown in FIGURE 1. It is preferred, although not essential, that the start signal be a high power signal and of short duration, for example that required to overdrive (electrically) solenoid 414 for a duration exactly corresponding to that required for the spring clutch to drive the paper tractor through a distance of one print line. Thus, when the high power signal is received, it is impressed on solenoid 414 over line 375a through OR gate 375d and over line 3752. No further signal is necessary owing to the original hypothesis that the high power signal will be of a duration which is correct for the paper tractor to drive paper 157 only one line. In those cases where the format control 375 commands that the spring clutch 128 remain energized to drive the paper .157 two, three or more lines, the electrical signal necessary for carrying out this command is conducted on line 3751), through OR gate 375d and over line 3752. However, the so called stop signal need not be a high power signal for optimum response time characteristics (high acceleration), because the stop signal reaches solenoid 414 when it is already energized by the high power signal. In reality, the stop signal functions as a low power holding signal which holds the solenoid energized (latch 413 of FIGURE 2 retracted) for a time sufflcient to carry out the format control command, i.e., whether one, two, three or more spaces corresponding to lines of print on the paper 157, are to be moved before the next print cycle.

Returning now to the operation of the mechanical phase of my spring clutch 128, when solenoid latch 413 is separated from engagement with the lobes 412 of sleeve M4, the clutch is prepared to drive as follows: sleeve 494 will begin to rotate due to toe 433a of the preloaded main drive spring 4% pushing against it. In moving forward, spring 4% will grip the continuously rotating input shaft 117. The input shaft will now drive the output shaft 118 through the main drive spring 403. After an advance of paper corresponding to one line of print (owing to the duration of the high power signal on line 3750), solenoid 414 will have been de-energized and the latch 413 will be driven by spring 41415 into engagement with the next lobe on sleeve 4%. However, the output shaft 118 will continue to rotate in a forward direction due to inertia, thereby again unwinding or preloading the main drive spring 433, and the lugs 491 on output shaft 118 will immediately impact lugs 411 on the actuating sleeve, which is now being held at rest by latch 413. Latch pin 4-15 of the anti-backlash device is continuously urged into the anti-backlash lobes 490 of the output shaft by spring 416. Accordingly, when the output shaft 118 rebounds from the actuating sleeve 4%, it will impact the pin 415 and be positioned by it.

Summarizing, paper 157 must move a distance corresponding to either one line or a plurality of lines of print upon command. It has been found that the paper moves a single line at a time very accurately so that the distance between any two printed lines is always within a close tolerance. This is accomplished by spacing the lobes of the spring clutch at even intervals around the circum ference of the clutch. Further, the paper moves in a manner so as to prevent cumulative error in vertical registration on printed line locations. This is due to the fact that the spring clutch will always bring itself back to its original starting point after one full cycle. No more than a very small amount of paper backlash is allowed; thus, the paper will not buckle. This is assured by allowing only a negligible amount of spring clutch output shaft backlash, by the correct positioning of the anti-backlash pin.

It is understood that the illustrated embodiment of my invention is given by way of example only, and that all modifications, changes and the like falling within the scope of the following claims may be resorted to.

What I claim as my invention is:

1. In a line printer having means for advancing paper through distances equal to one or more print-line spaces depending upon the desired format; first means for advancing said paper; a driven means to provide a signal for controlling the number of said spaces which said paper is to be advanced; and actuating means to simultaneously actuate said first and said driven means, said actuating means operatively connected with and controlled by said driven means and including'a ratchet having one tooth for each space that the paper is advanced, and an electrically operated latch engageable with a tooth of said ratchet and actuated upon the siganl from said driven means to automatically release one tooth of said ratchet, and said latch being re-engageable with another tooth of said ratchet to thereby enable said first means to advance the paper through a distance equal to one print-line space.

2. A spring clutch assembly comprising an input shaft having a flange intermediate the ends thereof, an output shaft having a plurality of different diameter portions, an intermediate diameter portion being identical to the diameter of the adjacent end of said input shaft, a plurality of lobes formed on one end of the largest diameter portion of said plurality of diameter portions, a first extension formed on the other end of said largest diameter portion of said plurality, a spring surrounding said identical diameter end and portions of said input and said output shafts respectively and abutting at its one end against said flange of said input shaft, an actuating shell surrounding said spring, said shell having a central lobe section and a second extension on one end thereof engaged with said first extension, and latch means operatively connected with said central lobe section.

3. In a line printer having means for advancing paper through distances equal to one or more print-line spaces at a time depending upon the format desired, first means for driving said paper; second means to control the number of spaces that said paper should be driven, and third means driving said first and second means simultaneously, said third means being controlled by said second means and including an input shaft having large and small diameter ends and a flange intermediate said ends, an output shaft having a plurality of different diameter portions, an intermediate diameter of said plurality of different diameter portions being identical to said large diameter end of said input shaft, a first lug formed on one end of said lar est diameter portion of said plurality, a ring surrounding said intermediate diameter portion, a spring surrounding said identical end and portion of said input and said output shafts respectively and abutting at its one end against said flange of said input shaft and at its other end against said ring, a sleeve'surrounding said spring, and said sleeve having a second lug on one end thereof engaging said first lug.

4. In a line printer having means for advancing paper through distances equal to one or more print-line spaces at a time depending upon the format desired, first means for driving said paper; second means to control the number of spaces that said paper should be driven, and third means driving said first and second means simultaneously, said third means being controlled by said second means and including an input shaft having large and small diameter ends and a flange intermediate said ends, an output shaft having a plurality of different diameter portions, an intermediate diameter portion of said plurality of dilferent diameter portions being identical to said large diameter end of said input shaft, a plurality of lobes formed on one end of the largest diameter portion of said plurality of portions, a first lug formed on the other end of said largest diameter portion, a ring surrounding said intermediate diameter portion, a spring surrounding said identical end and portion of said input and said output shafts respectively and abutting at its one end against said flange of said input shaft and at its other end against said ring, a sleeve surrounding said spring, said sleeve having a central lobe section and a second lug on one end of said sleeve engaging said first lug, and latch means operatively engaging said central lobe section.

5. In a line printer having means for advancing paper through distances equal to one or more print-line spaces at a time depending upon the format desired, first means for driving said paper; second means to control the numher of spaces that said paper should be driven, and third means driving said first and second means simultaneously, said third means controlled by said second means and including an input shaft having large and small diameter ends and a flange intermediate said ends, an output shaft having a plurality of different diameter portions, an intermediate diameter portion of said plurality of different diameter portions being identical to said large diameter end of said input shaft, a plurality of ratchet teeth formed on one end of the largest diameter portion of said plurality of portions, a first lug formed on the other end of said largest diameter portion of said plurality of portions, a ring surrounding said intermediate diameter portion, a spring surrounding said identical diameter end and portion of said input and said output shafts respectively and abutting at its one end against said flange of said input shaft and at its other end against said ring, a sleeve surrounding said spring, said sleeve having a central ratchet toothed section and a second lug on one end of said sleeve and engaging said first lug, a first spring-loaded latch, normally engaging said ratchet toothed section, a solenoid to disengage said latch from said toothed section, and a second spring-loaded latch for engagement with said plurality of ratchet teeth.

6. A clutch mechanism comprising an input shaft adapted to be driven continuously, said shaft having large and small diameter ends and a flange intermediate said ends, an output shaft having a plurality of different diameter portions, an intermediate diameter portion of said plurality of different diameter portions being identical to said large diameter end of said input shaft, a plurality of lobes formed on one end of the largest diameter portion of said plurality of diameter portions, a first lug formed on the other end of said largest diameter portion, a ring surrounding said intermediate diameter portion, said ring having a notch on one end thereof, a spring surrounding said identical diameter end and portion of said input and said output shafts respectively and abutting at its one end against said flange of said input shaft and at its other end against said ring, said spring having bent ends thereon, one of said bent ends being in engagement with said notch. a sleeve surrounding said spring, said sleeve having a slot on one end thereof for engagement with the other of said bent ends of said spring, said sleeve having a central lobe section and a second lug on the other end thereof which meshes with said first lug, a solenoid having a first springloaded latch which engages said central lobe section when said solenoid is not energized, and an anti-backlash device including a second latch and a spring biasing said latch into engagement with said plurality of lobes.

7. A spring clutch mechanism comprising an input shaft adapted to be driven continuously, an output shaft, said input and output shafts being aligned and having adjacent cylindrical outer surfaces of identical diameter, said output shaft having a larger cylindrical portion the outer end of which is formed with a first set of ratchet teeth and the inner end of which is formed with axially extending lugs, a close wound coil drive spring mounted over said adjacent cylindrical portions of said input and said output shafts, and a sleeve mounted over said drive spring, the internal diameter of said sleeve providing sufiicient clearance to allow limited unwinding of said spring so as to prevent said spring from gripping said shafts and providing a mechanical connection therebetween, said spring having a first toe formed at the input shaft end iereof, said sleeve having a slot receiving said toe, a second toe formed at the output shaft end of said spring, means coupling said second toe to said output shaft, the outer surface of said sleeve having a second set of ratchet teeth, said second set of ratchet teeth extending in the opposite direction from said first set of ratchet teeth formed on said output shaft, and the output shaft end of said sleeve being formed with axially extending lugs meshing with limited clearance with said lugs formed on said output shaft.

8. An indexing, anti-backlash clutch mechanism, comprising a power input shaft, the inner end of said input shaft having an outer cylindrical surface and an axial bore, an output shaft having an outer cylindrical surface and a pilot stem and sleeve bearing disposed in said axial bore of said input shaft, the diameters of said outer cylindrical surfaces of said input and output shafts being identical, a close-wound helical coil drive spring positioned over said cylindrical surfaces of said input and said output shafts, said output shaft having an enlarged portion with the outer end thereof formed with ratchet teeth and the adjacent inner end thereof formed with a pair of oppositely disposed lugs, a clutch shell comprising a cylindrical member positioned over said drive spring, said shell being formed with a pair of oppositely disposed lugs adapted to mesh with the lugs on said output shaft, a slot on the end of said shell opposite said lugs, a radially extending toe formed on the input shaft end of said drive spring and engaging said slot, said drive spring being formed at the output end thereof with a second toe, means coupling said second toe with said output shaft, the outer circumference of said shell being formed intermediate the ends thereof with second ratchet teeth extending in a direction opposite to that of said ratchet teeth formed on said output shaft, and anti-backlash means engaging said second ratchet teeth.

9. A spring clutch mechanism comprising an input shaft adapted to be driven continuously, an output shaft, said input and output shafts being aligned and having adjacent cylindrical outer surfaces of identical diameter, said output shaft having a larger cylindrical portion the outer end of which is formed with a first set of ratchet teeth and the inner end of which is formed with axially extending lugs, a close wound coil drive spring mounted over said adjacent cylindrical portions of said input and said output shafts, a sleeve mounted over said drive spring, the internal diameter of said sleeve provides clearance sufficient to allow limited unwinding of said spring so as to prevent said spring from gripping said shafts and providing a mechanical connection therebetween, said spring having a first toe formed at the input shaft end thereof, and said sleeve having a slot engaged with said first toe, said output shaft having a slot, and said spring having a second toe formed at the output end thereof and received in the slot in said output shaft, the outer surface of said sleeve being formed with a second set of ratchet teeth, said second set of ratchet teeth extending in the opposite direction from said first set of ratchet teeth formed on said output shaft, the output shaft end of said sleeve being formed with axially extending lugs meshing with limited clearance with said lugs formed on said ouput shaft, a spring biased latch continuously urged into engagement with said ratchet teeth formed in said output shaft, a solenoid having a core member spring-biased to engage said ratchet teeth formed on said sleeve when said solenoid is not energized and adapted to be withdrawn from said ratchet teeth when said solenoid is energized, said spring clutch mechanism being constructed and arranged such that energizing said solenoid results in said main drive spring gripping both said input and said output shafts so that said continuously rotating input shaft drives said output shaft and such that non-energizing said solenoid causes said core member to engage said second set of ratchet teeth on said sleeve and unwind said main drive spring to break the mechanical connection between said input and output shafts, said meshing lugs being dimensioned so as to permit limited continued rotation of said output shaft upon non-energization of said solenoid and the resulting stopping of said sleeve so as to preload said spring a determined amount, and said spring biased latch engaging said ratchet teeth onsaid output shaft to maintain some preload of said spring.

10. In a printer for forming successive lines of print on a record strip, said printer having a support, first means for advancing said record strip one or more lines at a mechanism for driving said first and second means simultaneously, said spring clutch mechanism being housed in said main support and comprising a continuously driven input shaft, an output shaft for driving said first and second means, said input and output shafts being piloted for purposes of alignment and having abutting cyiindrical outer surfaces of identical diameter, said output shaft having a larger cylindrical portion the outer end of which is formed with a first set of ratchet teeth and the inner end of which is formed with a pair of oppositely disposed lugs, a close Wound coil drive spring mounted over said abutting cylindrical portions of said input and said output shafts, a sleeve mounted over said springs, the internal diameter of said sleeve being sufficient to allow limited unwinding of said spring so as to prevent said spring from gripping said shafts and providing a mechanical connection therebetween, said spring having a first toe formed at the input shaft end thereof received in a slot formed in said sleeve and a second toe formed at the output end of said spring, said output shaft having a slot rceiving said second toe, the outer surface of said sleeve being formed with a second set of ratchet teeth, said second set of ratchet teeth being the same in number as the number of teeth formed on said output shaft but extending in the opposite direction, the output shaft end of said sleeve being formed with a pair of oppositely disposed lugs meshing with limited clearance with said iugs formed on said output shaft, a floating spring-biased latch mounted in said main support and being continuously urged into said ratchet teeth formed in said output shaft, a solenoid having a core member spring-biased to engage said ratchet teeth formed on said sleeve when said solenoid is not energized and withdrawn from said ratchet teeth when said solenoid is energized, said spring clutch mechanism being constructed and arranged such that energizing said solenoid results in said drive spring gripping both said input and said output shafts so that said continuously rotating input shaft drives said output shaft and such that de-energizing said solenoid causes said core member to engage said second set of ratchet teeth on said sleeve and unwind said main drive spring to break the mechanical connection between said input and output shafts, said meshing lugs being dimensioned so as to permit limited continued rotation of said output shaft upon non-energization of said solenoid and the resultant stopping of said sleeve so as to preload said spring a predetermined amount, and said floating springbiased latch engaging said ratchet teeth on said output shaft to maintain said spring preload.

11. An indexing, anti-backlash clutch mechanism, comprising an input shaft adapted to be driven, the inner end of said input shaft having an outer cylindrical surface and an axial bore, an output shaft having an outer cylindrical surface and a pilot stem and sleeve bearing disposed in said axial bore of said input shaft, the diameters of said outer cylindrical surfaces of said input and output shafts being identical, a close-wound helical coil drive spring positioned over said cylindrical surfaces of said input and said output shafts, said output shaft having an enlarged portion with the outer end thereof having ratchet teeth and the adjacent inner end thereof having a pair of oppositely disposed lugs, a clutch shell comprising a cylindrical member positioned over said drive spring, said shell being formed with a pair of oppositely disposed lugs adapted to mesh with the lugs on said output shaft, a slot on the end of said shell opposite said lugs, a radially extending toe formed on the input shaft end of said drive spring and engaging said slot, said drive spring being formed at the output end thereof with a second toe, said output shaft having a slot with which said second toe is engaged, the outer circumference of said shell being formed intermediate the ends thereof with ratchet teeth, said ratchet teeth being the same in number as said ratchet teeth formed on said output shaft but extending in the opposite direction, a solenoid having a spring-biased plunger positioned so as to engage said ratchet teeth on said shell except when said solenoid is energized, and a separate spring-loaded plunger adapted to engage said ratchet teeth on said output shaft so as to prevent backlash on said output shaft.

References Cited by the Examiner UNITED STATES PATENTS 2,475,432 7/49 Marihart 192-40 X 2,884,852 5/59 Saltz 197133 X 2,996,166 8/61 Bradshaw et al. 197-130 3,018,721 1/62 Monticello et a1 10193 WILLIAM B. PENN, Primary Examiner. R. A. LEIGHEY, Examiner.

Claims (1)

1. IN A LINE PRINTER HAVING MEANS FOR ADVANCING PAPER THROUGH DISTANCES EQUAL TO ONE OR MORE PRINT-LINE SPACES DEPENDING UPON THE DESIRED FORMAT; FIRST MEANS FOR ADVANCING SAID PAPER; A DRIVEN MEANS TO PROVIDE A SIGNAL FOR CONTROLLING THE NUMBER OF SAID SPACES WHICH SAID PAPER IS TO BE ADVANCED; AND ACTUATING MEANS TO SIMULTANEOUSLY ACTUATE SAID FIRST AND SAID DRIVEN MEANS, SAID ACTUATING MEANS OPERATIVELY CONNECTED WITH AND CONTROLLED BY SAID DRIVEN MEANS AND INCLUDING A RATCHET HAVING ONE TOOTH FOR EACH SPACE THAT THE PAPER IS ADVANCED, AND AN ELEC-

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