US3438476A - Fixed time delay for carriage return mechanism - Google Patents

Description

April 15, 1969 L. E. HARE ETAL FIXED TIME DELAY FOR CARRIAGE RETURN MECHANISM Sheet ors Filed May 26, 1966 INVENTORS LLOYD E. HARE DANIEL J. R BORG BY%(M ATTORNEYS April 15, 1969 L. E. HARE ETAL FIXED TIME DELAY FOR CARRIAGE RETURN MECHANISM Sheet 2 Filed May 26, 1966 INVENTORS LLOYD E. HARE DANIEL J. ROSBORG bQw ATTORNEYS April 15, 1969 L. E. HARE ETAL FIXED TIME DELAY FOR CARRIAGE RETURN MECHANISM I} Filed May 26. 1966 Sheet United States Patent U.S. Cl. 197-65 2 Claims ABSTRACT OF THE DISCLOSURE Depression of a carriage return key is adapted to effect movement of a cam to a position adapted to render a power return clutch engaged. Responsive to termination of carriage return, the power return clutch is caused to disengage automatically and the cam is caused to automatically move to a position where it will again react to depression of the carriage return key in the manner previously described. The cam provides a fixed time delay before engagement of the power clutch, and an equally precise fixed time period, which must elapse before a repeat carriage return may be initiated.

This invention relates to power operated carriage return mechanism for typewriter machines, and more particularly to improved means for controlling or conditioning such mechanism for operation and more specifically to a timed clutch mechanism for carriage return operation.

The conventional electric typewriter carriage return and line spacing mechanism employs a flexible drawband connected between the typewriter carriage and a drawband spool to advance the platen and then move the carriage from the end of its travel to a carriage return position as the drawband is wound. Normally, the drawband spool is connected to a motor driven shaft by a power clutch, which may be engaged by depressing a carriage return key mounted on the typewriter keyboard. Heretofore, these carriage return clutches performed erratically, ofttimes engaging and disengaging before platen indexing was completed, when the carriage return was initiated in the carriage return position, and on other occasions having delayed engagements accompanied with much noise and vibration, due to the difference in timing between the clutch and the unclutched components.

In accordance with the present invention, the carriage return mechanism is comprised of a timing wheel, coupled to a rotary cam, and adapted to rotate and st p at particular angular positions. When the timing wheel is activated, in response to a depression of a carriage return key, it rotates and carries the cam to a discrete angular position, where the cam acts on an actuator, to engage a power clutch, which couples a carriage return drawband spool to a constantly rotating motor driven shaft, whereby the platen is indexed and the carriage is moved toward the carriage return position. When the carriage reaches the carriage return position, the timing wheel is once again activated to rotate and carry the cam to a second discrete angular position, whereby the actuator disengages the power clutch and the carriage is halted. Since a repeat carriage return action may not be initiated until the timing wheel has reached the second angular position of the cycle, and since the time for moving the timing wheel from one angular position to another is only dependent on the rotational speed of the motor driven shaft, timing of the engagement and repeat engagements of the carriage return mechanism is therefore always consistent, uniform and very precise.

Accordingly, an object of the invention is in the provision of a clutch mechanism, which responds quickly and reliably to a clutch engagement signal.

Another object of the invention is in the provision of a clutch mechanism, which provides a constant uniform time to engage a driving member to a driven member.

A further object of the invention is to provide a carriage return mechanism for a typewriter, which so controls carriage return clutch engagement, as to prevent a repeat engagement before a previous carriage return movement has been completed.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing in which like reference numerals designate like parts throughout the figures thereof and wherein:

FIGURE 1 is an exploded view showing carriage return clutch elements of the invention in inactive position;

FIGURE 2 is a side elevational view showing the elements in an active position;

FIGURE 2a is an enlarged fragmentary view of the strap lever and fastener;

FIGURE 3 is a sectional view taken along the lines 33 of FIGURE 2;

FIGURE 4 is a rear view showing carriage return and associated carriage return knock-off elements;

FIGURE 5 is a partial perspective view showing the connection of the d-rawband to the line feed indexing mechanism carried by the carriage;

FIGURE 6 is a side elevational view of an alternate preferred embodiment of the mechanism in an active position;

FIGURE 7 is a partial rear view showing the interposer lever in an active position engaged to the cam follower; and

FIGURE 8 is a view similar to FIGURE 7 showing the interposer lever in the inactive position.

Referring now to the drawing, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIGURE 1 a link 10, which is adapted to be driven forwardly in response to depression of a carriage return key (not shown). The rearwardmost end of the link 10 is articulately connected to the upward extending arm 11 of a lever 12, which is pivotally mounted on a fulcrum 13. The fulcrum 13, as viewed in FIGURE 2, is journaled in a bracket 14, which in turn is secured to a machine frame 15. The lever 12 is formed with a rearward extending arm 16, the extremity of which is bent off to form a stop 17 adapted to engage one of the primary lugs 18a or 18b, when the carriage return key is at rest, and to engage one of the interposer lugs 19a or 1912, when the carriage return key is maintained in a depressed position, as will hereinafter be more fully described. The primary lugs 18a and 18b are arranged apart (near a sleeve hub 26b) on a rotatable timing wheel 21, whereas the interposer lugs 19a and 191) which angularly lead the primary lugs 18a and 18b (counterclockwise as viewed in FIGURE 1), are located near the periphery of the timing wheel 21.

The timing wheel 21, as shown in FIGURE 3, is loosely mounted on a cam sleeve 25, which is integral with a cam 24. Cam 24 has two lobes 24a located 180 apart (FIGURE 1), and is loosely mounted on a sleeve 26 secured by a retaining screw 27 to a constantly rotating motor driven shaft 23 (FIGURE 3). A conventional C ring 22, axially restrains one side of cam 24, and sleeve end wall 26a restrains the other side. Cam 24 and timing wheel 21 are coupled together to rotate with shaft 23, by a wrap spring clutch, generally designated by reference numeral 28. A bent 01f end 77 of spring clutch 28, which surrounds sleeve 26, is secured in cam 24 and the other end 29 is secured in timing wheel 21. As best viewed in FIGURE 1, the cam hub is provided with a slot 25a for accommodating the spring clutch end 29 and permitting sufiicient angular movement of the spring clutch 28, such that it may wrap around the sleeve 26 and rotate therewith, when the timing wheel lugs 18 and 19 are not engaged by either the lever 12 or an interposer lever 31, which is pivotally mounted on a bracket supported pin 30. The interposer lever 31 is biased counterclockwise around pin by a spring 50, to engage one of the interposer lugs 19a or b as will be described below.

Referring now to FIGURE 1, when the lever 12 is rocked counterclockwise incident to depression of the carriage return key, the bent off stop 17 will be elevated, and thereby disengaged from the primary lug 18a, to permit the wrap spring clutch 28 to couple the cam 24 and timing Wheel 21 to the rotating sleeve 26. Thus, the spring clutch 28, cam 24, and timing wheel 21 rotate with sleeve 26 until lug 19b engages a bent over stop 31a, on the depending end of the interposer lever 31. With the timing wheel 21 prevented from rotating, by stop 31a engaging lug 19b, the spring clutch 28 will unwrap and disengage from rotating sleeve 26, and thus the cam 24 and timing Wheel 21 will have rotated a quarter of a revolution, as shown in FIGURE 2. This rotation of cam 24 positions one of the cam lobes 24a such that a power clutch actuator 32 activates a power clutch to couple the continuously driven shaft 23 to a carriage return drawband spool 34, as will hereinafter be more fully described.

Referring again to FIGURE 3, sleeve 26 extends axially towards a spool sleeve 34a of a drawband spool 34 associated with the carriage return conventional drag means 33 for preventing too rapid turning of the spool 34. Both sleeves 26 and 34a are surrounded by the wrap spring power clutch 35, which has one end 36 secured as by friction to the driven sleeve 26, and the other end 37 being free; the normal diameter being such that the coils at the free end 37 are spaced from the spool sleeve 34a. The power clutch actuator 32, as best viewed in FIGURES 1 and 2, is comprised of a strap 38, which surrounds the coils of the free end 37 of wrap spring 35, and is secured to a strap lever 39 by a fastener 41. The actuator 32 is further comprised of a cam follower 42 threaded into a cam lever 43, secured thereto by a nut 44; the cam lever 43, which is pivotally mounted on a bracket journalled pin 40, in turn, is secured to the strap lever 39 by a fastener 46, whose shank diameter 46a is smaller than a corresponding aperture 72 in strap lever 39 (FIGURE 2A), whereby strap lever 39 may pivot clockwise around a tail 43a which passes through a slot 61 in strap lever 39, as will be described below. The end 41a of strap lever fastener 41 is used to secure one end of a spring 45, the other end of which is fastened to cam lever 43 such that spring 45 acts to cause the gradual engagement of strap 38 to the free end coils when the cam follower 42 is engaged by cam 24 and also acts to compensate for wear of the strap 38.

Accordingly, when the cam lever 43 is pivoted clockwise around pin by one of the cam lobes 24a acting on cam follower 42, spring 45 exerts a force to pivot strap lever 39 clockwise, around the tail 43a, until strap 38 has engaged the free end coils, and the consequent friction slows down the free end coils relative to the fixed end coils causing the spring power clutch 35 to wrap and couple spool 34 to the motor driven shaft 23.

As viewed in FIGURES 4 and 5, the carriage return drawband 47 is trained about guide pulleys 48, 49 and 74 and connected to the carriage frame 51; the pulley 49 being rotatably carried by a line space pawl lever arm 52 rotatably mounted on a platen shaft 53 and biased as by spring 54 to the position shown in FIGURE 5. As the drawband 47 is wound on spool 34, the lever arm 52 is rotated counterclockwise, and this motion is coupled to a pawl indexing lever 55, also mounted on the platen shaft 53, by a motion transmitting spring 56, whereby an index pawl 57 carried by lever 55 will engage the line space ratchet (not shown) and rotate the platen. After a platen 53a is indexed, a stud 58 on the lever 55 encounters an abutment 59 on the carriage frame 51, so that continued pull on the carriage return drawband 47 will pull the carriage toward the carriage return position.

With reference to FIGURE 4, when a margin stop 61 on the margin bar carried by the carriage encounters a margin locator or knock-off paddle 62, pivotally secured to the center post 63 of the machine, the locator 62 is rocked counterclockwise around pivot 60, as viewed in FIGURE 4, and its lower end 64 pulls a link 65 toward the right, thereby rocking the interposer lever 31 clockwise about pivot 30 against the bias of spring 50. This movement releases lug 1%, thereby permitting wrap spring clutch 28 to couple cam 24 and timing wheel 21 to the rotating sleeve 26. After a quarter revolution, the lug 18b will encounter stop 17 or if the carriage return key has not been released, lug 1912 will encounter stop 17. In either case, spring clutch 28 will be disengaged. In the latter case, when the carriage return key is released, stop 17 will be lowered in the conventional manner by a spring (not shown), and almost immediately thereafter engage lug 18b before the spring clutch 28 can wrap. The movement of the cam 24 over this quarter revolution moves the cam lobe 24a from under cam follower 42, which rides on cam surface 241), and simultaneously the rotating spring clutch 35 frictionally pivots the strap lever 39 counterclockwise such that strap 38 releases the free end coils 37 of wrap spring 35, thereby to effect disengagement of the spring clutch 35.

The aforedescribed carriage return mechanism provides a precise fixed time period for engaging the power clutch 35, and an equally precise fixed time period, which rnust elapse, before a repeat carriage return may be initiated (for platen indexing) after the carriage has been returned to the carriage return position. However, disengagement of the carriage return drawband pulley 34 from the continuously driven shaft 23 does not occur immediately after the margin stop 61 encounters the margin locator 62, but some time later, when cam lobe 24:: has been rotated out of the pivotal path of the power clutch actuator 32, and this condition, for some applications, is not very desirable. Therefore, in an alternate preferred embodiment shown in FIGURES 6, 7 and 8, cam lobes 66a are formed to have a somewhat narrower shape than cam lobes 24a, and link 65 is coupled to interposer lever 31 via a slot 31b, whereby lever 31 may be pivoted counterclockwise around stud 30, by spring 50, without moving link 65, when the cam lever 43 is pivoted clockwise by one of the cam lobes 66a, and simultaneously an interposer lever surface 31c engages and retains the power clutch actuator 32 in a position to maintain the power clutch 35 engaged, as will be described below.

Thus, upon depression of the carriage return key and the subsequent release of lug 18a, the timing wheel 21 and cam 66 rotate, such that one of the cam lobes 66a acts on cam follower 71, to pivot the cam lever 43 clockwise around shaft 40, as before, to engage the power clutch 35. The interposer lever 31 is pivoted counterclockwise around stud 30, by spring 50, from the inactive position depicted in FIGURE 8 to the active position shown in FIGURE 7, when the cam follower head 71a no longer obstructs the pivotal path of the interposer level 31. At this time, the interposer lever surface 31c slides under the cam follower head 7111, until it contacts the cam follower body 71b, thus to restrain the cam lever 43 in a position whereby the power clutch 35 is maintained engaged. The interposer lever 31 also halts the timing wheel 21 and cam 66, as before, by stop 31a engaging lug 19b on the timing wheel 21. However, in this embodiment when the timing wheel 21 and cam 66 are halted, the cam lobe 66a, due to its shape, is no longer under cam follower 71. Therefore, when the carriage is returned and the margin stop 61 encounters the margin locator 62, the interposer lever 31 is rocked clockwise, as before, and the power clutch actuator 32 is almost simultaneously released (5 milliseconds), thereby producing an extremely rapid power clutch disengagement.

It will now appear that I have provided a carriage return mechanism that attains the several objects set forth above in a thoroughly practical and efficient manner.

The invention claimed is:

1. In a carriage return mechanism having driving and driven members:

a rotary cam;

a clutch operable when enabled to couple said rotary cam to said driving member;

an actuator operable in response to a predetermined movement of said rotary cam to effect the coupling together of said driving and driven members;

means operable in response to depression of a carriage return key for enabling said clutch;

interposer means operative, upon said rotary cam moving through a first predetermined angle during which said actuator is moved to a position effecting the coupling of said driving and driven members together, to disengage said clutch and to hold said actuator in said coupling position;

and control means driven upon termination of a carriage return to disable said interposer means, thereby immediately releasing said actuator effecting uncoupling of said driven and driving members, and causing said clutch to be re-engaged and to rotate said rotary cam through a second predetermined angle, whereby said means for enabling said clutch in response to the depression of a carriage return key is restored to an operable mode after a predetermined delay subsequent to termination of carriage return and uncoupling of said driving and driven members.

2. In a typewriter having a carriage and a platen rotatably mounted thereon:

a platen indexing mechanism operable through a working interval incident to powered carriage movement and through a recovery interval after termination of powered carriage movement;

a rotatable drum;

a carriage return drawband connected to said drum and to said platen indexing mechanism;

a power shaft;

a power clutch;

a rotary cam freely mounted on said power shaft;

rotatable connecting means secured to said rotary cam and associated with said power shaft to couple said rotary cam to said power shaft and thereby drive said rotary cam;

an actuator movable in response to a predetermined movement of said rotary cam, to a position to effect engagement of said power clutch for coupling said power shaft to said drum thereby in turn operating said platen indexing mechanism through its working interval and returning said carriage;

stop means normally locking and preventing said rotatable connecting means from rotating with said power shaft, operable in response to depression of the carriage return key to release said rotable connecting means whereby said rotary cam is coupled to said power shaft;

interposer means operable after said cam has rotated through an angle necessary to move said actuator to said position effecting engagement of said power clutch, to engage said connecting means and said actuator so as to uncouple said cam from said power shaft, and hold said actuator in said position effecting engagement of said power clutch;

and control means driven upon termination of a carriage return to disengage said interposer means from said actuator and said connecting means, whereby said actuator disengages said power clutch and said rotary can moves with said power shaft until said connecting means encounters and is halted by said stop means, thus restoring the stop means to a normay operable mode after a predetermined delay subsequent to the termination of carriage return and disengagement of the power clutch.

References Cited UNITED STATES PATENTS ERNEST T. WRIGHT, ]R., Primary Examiner.

US. Cl. X.R.

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