US2791422A

US2791422A - Controlled feed device

Info

Publication number: US2791422A
Application number: US390974A
Authority: US
Inventors: John S Baer
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1953-11-09
Filing date: 1953-11-09
Publication date: 1957-05-07
Anticipated expiration: 1974-05-07

Description

y 1957 J. s. BAER 2,791,422

CONTROLLED FEED DEVICE Filed Nov. e, 1953 2 Sheets-Sheet 1 SHAFT EOTAT/OI-V S/G/VALS comm emu/r C OIW'ML CIRCUIT SHAFT e 0771 7/0 801570/0 SIGNALS i INVENTOR.

JOHN 3. BABE )ITTORNE 1 May 7, 1957 55, BAER 2,791,422

' CONTROLLED FEED DEVICE Filed Nov. 9, 1953 2 Sheets-Sheet 2 IXIENTOR. S BAER ATTORNEY CONTROLLED FEED DEVICE John S. Baer, Woodbury, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application November 9, 1953, Serial No. 390,974

13 Claims. (Cl. 271-2.4)

This invention relates to a controlled feed device, and particularly to a device for selectively moving a length of strip material in varying amounts and with varying velocities.

One example of the use of the structure of the present invention is a strip material feed employed in the output section of a modern high-speed data processing machine. The output devices in this section first encode information as a pattern of light variations on photographic film. This encoded pattern is then transferred to another light sensitive medium which provides a final, useable copy. The information on one frame of film may be reproduced as many times as needed for the number of final copies desired.

This reproduction process requires a slow speed controlled scanning movement of the film in one direction as the light sensitive medium is exposed, then a high-speed return movement to the starting point for a repetition of the scan. The amount of time involved in this return or pull-back is important. If the pull-back speed is fast enough, the light sensitive medium can be kept moving during the pull-back, thus effecting a considerable saving in synchronizing and control equipment. Also, because modern data processing machines can often present output data faster than it can be utilized, a faster pull back reduces the time wasted and permits better utilization of the services of the machine.

Proper registration of the film at the desired frame after pull-back is also an important requirement of this strip material feed device. The device should advance and pull-back only complete frames, and without accumulating errors in registration. The desired operations should be performed economically, and the equipment should be durable and reliable, in contrast to expensive and cumbersome film pull-back equipment heretofore used.

Therefore, an object of this invention is to provide a device for imparting a controlled motion to a strip material, which device is simpler and more efficient than devices previously known in the art.

It is another object of this invention to provide a mechanism for supplying mechanical movements of variable amplitudes and two velocities which is smoother and more precise in operation than devices heretofore available.

Another object of this invention is to provide a rugged and compact mechanism for controllably advancing and pulling back a length of strip material.

Yet another object of this invention is to provide .an improved two-speed reciprocating film drive.

It is a further object of this invention to provide a controlled motion mechanism for a film feed which imparts a selectable amount of continuous slow speed movement in one direction, and a selectable amount of highspeed movement in a direction the reverse of the first, which mechanism is superior in performance and econ- States PatentO latented May 7, 1957 omy to the mechanisms previously known for performing this function.

According to the invention, there are provided means for continuously supplying the desired rates and directions of motion, and means for selectively employing incremental amounts of these motions. In a preferred embodiment of this invention, a slow speed forward and a high-speed return motion are derived by means of a pair of continuously rotating shafts. Each continuously rotating shaft is coupled to a different input of a differential through a different intermediate one-revolution spring clutch. The differential output is driven by either of the continuously rotating shafts, dependent upon which clutch is engaged. The output rotation continues for a predetermined number of shaft revolutions, dependent on the period of time the clutch is engaged. Accordingly, a film drive coupled to the differential output is given a positive, continuous motion at desired rates of speed in forward and return directions.

The foregoing and other novel features of this invention, as well as the invention itself, both as to its organization and method of operation, will best be understood from the following description, when read in connection with the accompanying drawing, in which like reference numerals refer to like parts, and in which:

Fig. 1 is a schematic plan view, partly in section, of a preferred embodiment of the invention;

Fig. 2 is a side sectional view of the preferred embodiment of the invention, taken along the line 22 of: Fig. l; and

Fig. 3 is a schematic front view of the preferred embodiment of the invention, showing the arrangement of the associated film handling apparatus.

Referring to Fig. 1, a differential 10 having two wormwheel inputs 12, 14 and a cage output 16 is used to provide two output rotations having opposite senses. One worm-wheel 12 input is here termed the advance wormwheel input, the other 14 is termed the pull-back wormwheel input. The differential it) is of a type well known in the art, which provides an output rotation equal to one-half the algebraic sum of the rotations of its inputs. The cage output 16 of the differential turns an output shaft 18 which is rotatably mounted in the system housing 20. Each of the two input worm-Wheels i2, 14 freely rotates on the output shaft 18.

The worm-wheels 12, 14 on the differential are driven by matching advance and pull-

back worms

22 and 24 fixedly mounted respectively .to advance and pull-back

differential drive shafts

26 and 28. T he worms 22 and 24 may both have right-hand threads, as shown in Fig. 1. Separate motors 30, 32, rotating at desired speeds and in desired senses, provide individual drives for each of the worms 2.2, 24. Individual advance and pull-back one-revolution spring clutches 38 and 40 couple each differential drive shaft 26, 2S and its associated worm 22-, 24 to a

shaft

34, 36 on each motor 30, 32. The spring clutches 38, 40 may, for example, be of the type shown and described in vol. I of the book Ingenious Mechanisms for Designers and Inventors, at page 140. The function of these clutches 38, 46 is to utilize the rotations available at the

motor shafts

34, 36 for driving the

worms

22, 24 for selectable periods. By one-revolution spring clutches, I include devices for engaging input and output shafts for one or more integral incremental revolutions.

A clutch 38 or 40 is engaged, and drives a

differential drive shaft

26 or 28 from the associated motor shaft 34 or 35, when the clutch 38 or 40 is permitted to rotate freely. A clutch 38 or 40 is disengaged, and its associated

differential drive shaft

26 or 28 is not driven, when the clutch 38 or 40 is held against rotation.

The spring clutches 38, 40 are engaged for

full revolustop members

42, 44 are fixed individually to the outer frame of each of the clutches 38, 40. Each

stud

42, 44 is aligned with one of two separate engaging pins 46, 48 extending'through the system housing 20. Each en'gaging pin here termed separately an advance or pull-back pin 46 or 48 is movable in the system housing 20. When inserted fully in the direction of the associated spring clutches 38, 40, the engaging pins 46, 48 protrude into the path of the studs or stop

members

42, 44, holding the

studs

42, 44, and the clutches 38, 40, against rotation.

The movement of the individual engaging pins 46, 48 within the system housing 20 is effected by separate solenoids, termed advance and pull-back solenoids 50 and 52 in correspondence to the elements to which they are coupled. Each of the solenoids 50, 52 is actuated by a

control circuit

54, 56 coupled to a selection and timing circuit 58, and is additionally responsive to the number of rotations made by their associated

motor shafts

34, 36. Shaft rotations may be counted, for example, by the use of a commutator surface on the shaft. The selection and timing circuit 58, and the

control circuits

54, 56, may employ any of several well known techniques for performing the desired control functions. First one solenoid, then the other, is impulsed for a preselected number of motor shaft rotations. This impulsing is re peated for a predetermined number of cycles, at the conclusion of which a new control pattern may be established. One technique which may be employed is to utilize a data processing machine itself for storing and presenting signal instruction to the circuits.

A film 60 which is to be given a controlled reciprocating motion is threaded across two

drive sprockets

64, 66, the teeth of which engage the sprocket holes 62 on the film 60. The

sprockets

64, 66 are each mountedon individual film drive shafts 68, 70 freely rotatable in the system housing 20. Driven gears 72, 74 fixedly mounted on each of the film drive shafts 68, 70 are rotated by a common drive gear 76 mounted on the output shaft 18 of the differential 10. a

The cage output 16 of the differential carries bevel gears 80 (shown more clearly in Fig. 2) which mesh with two

opposed bevel gears

82, 84. It is to be noted that the cage 16 of the differential 10 has, for clarity in illustration, been rotated to a vertical position in Fig. 2, in contrast to the horizontal position of Fig. 1. Each

bevel gear

82, 84 is fixed respectively to each of the wormwheel 12, 14 inputs. When the engaging pins 46, 48 are inserted each contact one of the

opposed studs

42, 44 on the one-revolution spring clutches 38, 40. The pins 46, 48 and the

studs

42, 44 have complementary mating surfaces at the point of contact. When an engaging pin 46 :or 48 is withdrawn the

stud

42 or 44 is no longer prevented from moving, and thus the associated clutch 38 or 40 is engaged.

Fig. 3 shows the arrangement by which the film 60 is advanced and pulled back smoothly and without undue stresses. This arrangement is fully shown and described in a co-pending application, Serial No. 389,707, for a Strip Material Feed Control filed on November 2, 1953, by John S. Baer and Charles E. Yearsley, and assigned to the present assignee. A film supply reel 90 feeds the film to the

drive sprockets

64, 66. The

sprockets

64, 66 drive the film 60 past a stripper roll 92, and through a pair of guide rolls 94 to a loop forming and controlling device 100. The loop control 100 includes three fixed studs; an uppermost smooth stud 102, an intermediate smooth stud 104 and a bottom rubber control stud 106. The film 60 is threaded between these three studs 102, 104, 106 so that the uppermost and

bottom studs

100, 104 are on the same fiat side of the film 60. The studs 102, 104, 106 are so positioned that a free loop L forms in the film 60 between the

sprockets

64, 66 and the

studs

42, 44. A constant torque capstan 108 is used to reel in the film 60, and also to cooperate 4 with the three studs 102, 104, 106, in the control of loop size L.

In operation, the device of the preferred embodiment (Fig. 1) may move film intermittently and in either direction along the length of the film strip. The principal direction of motion is that of film advance, in which the film 60 moves from the supply reel toward the capstan 108. For purposes of illustration here the principal direction of film motion has been selected as indicated by arrows A in Fig. 1. Accordingly, in this illustration the principal direction of rotation of the film drive shafts is also as indicated by arrows on the shafts in Fig. 1. The selection and timing circuit 58 is preset with the number of frames to be scanned in the advance movement, and the number of times the scan is to be repcatcd. At the commencement of a cycle of operation, and continually thereafter, both motors 30, 32 are rotating at normal speeds. The motor 30 coupled to the advance differential drive shaft 26 turns counter-clockwise (as viewed in Fig. 2) at a relatively low speed for scanning, while the motor 32 coupled to the pull-back differential drive shaft 28 turns clockwise (also as viewed in Fig. 2) at a relatively high-speed for the return or pull-back motion. In the standby condition both engaging pins 46, 48 are in, holding the spring clutches 38, 40 stationary and disengaging the

differential drive shafts

26, 28 from the

motor shafts

34, 36.

The unit begins operation on receiving the proper instruction impulses from the selection and timing circuit 58 and the

control circuits

54, 56. The instructions may be, for example, (1) to advance the film six frames, (2) then pull back the film six frames, and (3) to repeat this cycle four more times, or five times in all. We assume here that one-revolution of either

differential drive shaft

26 or 28 causes a movement of one frame in the film 60.

An impulse is first received at the advance solenoid 50, causing the advance engaging pin 46 to be disengaged from the stud 42 on the advance spring clutch 38. On release of the spring clutch 38 the clutch action causes the advance differential drive shaft 26 to rotate counter-clockwise (as viewed in Fig. 2), together with the coupled motor shaft 34. The worm 22 on the differential drive shaft 26 turns the advance worm-wheel 12 input on the differential 10 counterclockwise (as viewed from the bottom of Fig. 1). Accordingly, the differential output shaft 18 also rotates counter-clockwise (as viewed from the bottom of Fig. 1), at a slow rate of speed. The common drive gear 76 on the differential output shaft 18 thus rotates both fixed driven gears 72, 74, and both

sprockets

64, 66 clockwise (as viewed from the bottom of Fig. 1) in the advance or principal direction of motion. The

sprockets

64, 66 advance the fihm 60.

The

control circuits

54, 56 are responsive to the number of

motor shaft

34, 36 rotations during the time a clutch 38, 40 is engaged. Consequently, when the desired number of advance rotations (six) have been made, the

control circuits

54, 56 deactivate the advance solenoid 50 and impulse the pull-back solenoid 52. This action engages the advance engaging pin 46 to the advance spring clutch 38 at the completion of the sixth full revolution. The action also disengages the pull-back engaging pin 48 from the pull-back spring clutch 40, engaging the pull-back differential drive shaft 28 to the associated motor shaft 36. The worm 24 on the pull-back drive shaft 28 turns clockwise, rotating the pull-back wormwheel 14 input clockwise. This rotation, through the common drive gear 76 and the fixed driven gears 72, 74, rotates the

sprockets

64, 66 counter-clockwise, and reverses the direction of film 60 feed to the pull-back direction.

The film pull-back is rapid because of the relatively high-speed of motor 32, and continues for the desired number of shaft 36 rotations. During the period of rotation the control circuit 56 is again responsive to the number of shaft 36 rotations. When the required number (six) are completed, the positions of the engaging pins 46, 48 are again reversed, and film advance again commences. The cycle is repeated a total of five times before the device returns to the standby condition.

Thus each differential input is driven by means of a different motor. The control circuits and spring clutches provide a means, responsive to the motor rotations, or to portions of rotations, to control the driving of each input by its motor. By portions of rotations, I include one or more complete rotations, or fractions of. rotation greater or less than unity.

When the pull-back differential drive shaft 28 rotates clockwise (see Fig. 2), the pullback worm-wheel 14 input on the differential is driven clockwise (as viewed from the left in Fig. 2 on the bottom in Fig. l). The bevel gear 84 attached to the pullback worm-wheel 14 input turns the diflierential cage 16 in the same clockwise direction through the bevel gears 80 on the cage 16. The advance worm-wheel 12 input is at this time stationary. Accordingly, the differential output shaft 18 also rotates clockwise at one-half the speed of the pullback worm gear 14.

The mechanism described performs its functions in the same way regardless of the number of frames and the number of repetitions in a cycle of operation. Additional mechanical arrangements are not needed to permit changes in the operating speeds. The scanning and pull-back speeds are substantially linear and the scanning and pull-back movements are substantially mul tiples of a given amount. The employment of gear drives minimizes the compensations necessary due to wear and other operating factors.

The film handling mechanisms associated with the film drive are shown in Fig. 3. The operation of this film handling mechanism is described fully in the co-pending application of Baer and Yearsley previously referred to. The operation will, therefore, be described here only briefly. Referring to Fig. 3, film fed in the principal direction of motion from the sprocket-

s

64, 66 forms a free loop L between the guide rolls 94 and the three fixed studs 102, 104, 106. The constant torque capstan 103 exerts a continual pull on the film 60, tending to diminish the size of the loop L. When the loop L is small, however, the film 60 becomes taut between the uppermost and the intermediate smooth studs 102 and 104. These studs 102, 104 are so disposed that when the loop L is small they hold the film 60 frictionally on its flat sides. When loop size L becomes larger, however, the film 60 loosens between these studs 102, 104. The frictional forces on the fiat sides of the film 60 decrease until at a predetermined loop size the pull from the capstan 108 is sufficient to overcome the friction at the studs 102, 104. The capstan 108 then reels in film 60 until the loop L is once again small enough for the frictional forces to hold the film 60. The loop size, even when smallest, is sufficient to permit film pull-back at the

sprockets

64, 66.

The rubber control stud 106 is so positioned that it makes the egress path of the film 60 from the two smooth studs 102, 104.- substantially independent of the amount of film 60 wound upon the capstan 108. The control stud 106 also stabilizes the pull on the film 60 from the constant torque capstan 108, by providing a decreasing frictional force as the force at the end of the torque arm (the radius of the wound film) decreases.

Thus there has been described a simple, efficient means for providing variable amounts of movement at different velocities. Although a specific embodiment for providing a reversible motion has been shown, the device may be used to provide two speed or intermittent motions in the same direction.

What is claimed is:

1. In a system providing controlling signals corresponding to incremental movements of a controlled member, a mechanism for supplying incremental motions of selectable amplitude and different velocity comprising a pair of rotatable driving means, a differential means at least two inputs and an output, each of said differential inputs being driven by a different one of said driving means, and means responsive to said controlling signals for controlling said driving means for predetermined portions of rotation of said driving means, whereby corresponding incremental motions are imparted to said differential output.

2. A feed control device for supplying two motions of selectable amplitude and different velocity comprising first and second rotatable driving means, differential means having at least two inputs and an output, means for selectively coupling one of said inputs to each of said driving means, and means responsive to driving means rotations for controllably actuating said selective coupling means for predetermined portions of the rotations of the respective said driving means.

3. A film advance and pull-back mechanism for intermittently moving film with different speeds and directions, and in controlled amounts, comprising differential means having two inputs and an output, first and second rotatable driving means for supplying two rotations, clutch means for selectively driving each of said inputs in opposite senses with a different one of said rotations, means responsive to driving means rotations for actuating said clutch means for predetermined portions of the rotations of the respective said driving means, and film sprocket drive means coupled to said differential output.

4. The invention as set forth in claim 3, wherein said clutch means is a pair of one-revolution spring clutches, and wherein said clutch actuating means includes a pair of clutch engaging members.

5. A device for driving a length of strip material with intermittent forward and reverse movements of different speeds and varying incremental amplitudes, comprising a first low-speed rotatable drive means, a second hi gh-speed rotatable drive means, a differential having first and second inputs and an output, first and second drive gears coupled to said first and second inputs respectively, a first clutch coupling said first rotatable drive means and said first drive gear, a second clutch coupling said second rotatable drive means and said second drive gear, first and second means responsive to respective drive means rotations for selectively actuating said first and said second clutches respectively for integral portions of the rotations of said drive means, and a strip material sprocket drive coupled to said differential output.

6. The invention as set forth in claim 5, wherein said first and second clutches are each one-revolution spring clutches, and wherein said means for selectively actuating said clutches includes a stop member mounted on each of said clutches and a pair of stop engaging members.

7. In a system responsive to control signals in a predetermined sequence corresponding to incremental movements of an output member, a device for driving a length of film material with intermittent forward and reverse movements of different speeds and varying incremental amplitudes, comprising a first low-speed rotatable drive means, a second high-speed rotatable drive means, a differential having first and second inputs and an output, first and second drive gears coupled to said first and second inputs respectively, a first one-revolution clutch coupling said first rotatable drive means and said first drive gear whereby said first input is driven in a given sense, a second one-revolution clutch coupling said second rotatable drive means and said second drive gear whereby said second input is driven in an opposite sense to said first input, first and second engaging means for selectively actuating said first and said second clutches respectively, control means responsive to said control signals for operating said first and second engaging means in a predetermined sequence, and a film sprocket drive coupled to said differential output.

8. In a system responsive to signals reversibly to control reversibly the movement of film, a device for driving a length of film with intermittent forward and reverse movements of different speeds and varying incremental amplitudes, comprising a first low-speed rotatable drive means, a second high-speed rotatable drive means, a differential having first and second inputs and an output, first and second drive gears coupled to said first and second inputs respectively, a first one-revolution clutch selectively coupling said first rotatable drive means and said first drive gear whereby said first input is selectively driven in a given sense, a second one-revolution clutch selectively coupling said second rotatable drive means and said second drive gear whereby said second input is selectively driven in an opposite sense to said first input, first and second stop members fixedly mounted on said first and second clutches respectively, first and second stop engaging members selectively movable to register with said first and second stop members respectively, control means responsive to said control signals for operating said first and second engaging means, and a film sprocket drive coupled to said differential output.

9. The combination of first and second rotational driving means operating at different rates, a differential having two inputs and a rotational output, first and second clutch means coupling respectively said differential inputs to said driving means, settable control means connected to said clutch means for alternately engaging the one and then the other of said clutch means, said' control means being responsive to rotations of the driving means according to a program whereby saiddifferential output rotates for specified increments of rotation corresponding to a desired number of rotations of an engaged driving means.

10. In a system responsive to control signals corresponding to incremental movements to be transmitted to a driven member, a first and second rotational driving means, a differential having two inputs and an output, first and second clutch means coupling respectively said first and second driving means to separate differential inputs for imparting motions of different rates and different senses to said differential output, and clutch control means responsive to said control signals for engaging and disengaging alternate ones of said clutch means for a desired number of rotations of an engaged driving means.

11. A feed control device for supplying motions of selectable amplitudes and different velocities comprising a plurality of rotational driving means, a differential means having an output and a plurality of inputs each corresponding to a different driving means, clutch means for selectively coupling'each differential input with the respective corresponding driving means, and means responsive to said driving means for controllably actuating said clutch means for predetermined portions of the rotations of the coupled driving means.

'12. In a system responsive to control signals for advancing a strip material in incremental amounts, the combination comprising a first and a second rotational drive means, a differential having two input shafts and a revolving output shaft, a first and second clutch means for coupling respectively said first and second drive means each to a differential input shaft, clutch control means responsive to said control signals and to signals from said drive means for selectively engaging one of said clutch means through a number of revolutions corresponding to a desired number of differential output shaft revolutions, and strip material transporting means including sprocket means coupled to said differential output shaft for imparting desired increments of motion to said strip material.

13. A device for providing incremental movements to a strip material comprising in combination, sprocket means for engaging a strip to be moved, a differential having two inputs and an output, said differential output being connected for driving said sprocket means, a first and second rotational driving means each operating at a different rate, a first and second clutch means, each coupling one of said driving means to a separate differential input, clutch control means for selectively engaging one of said clutch means for driving one of said differential inputs, said clutch control means being responsive to signals from said driving means representing predetermined increments of rotation of the engaged one of said driving means, whereby incremental movements in desired amounts are imparted to the said differential output and coupled sprocket means.

References Cited in the file of this patent UNITED STATES PATENTS Davis July 28,