US2833976A - Positioning mechanism - Google Patents

Description

May 6, 1958 G. J. KENNEDY ErAx. bPosITIoNING 'MECHANISM' 2 Sheets-Sheet l ,ud Hnudnnvn Filed July 15, 1955 IHHHMUHH Illll'nllll' nl May 6, 1958 G. J. KENNEDY l-:TAL 2,833,976

PosITIoNING MECHANISM Filed July 15, 1955 2 Sheets-Sheet 2 ill V IN VEN TORS WMM/2.0 nf. 00x; BY

i AGE/Vf POSITIONING MECHANISM Gilbert J. Kennedy, Philadelphia, and Winfield W. Loose,

Reading, Pa., assignors to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application July 15, 1955, Serial No. 522,293

4 Claims. (Cl. S18-467) This invention relates to motorized positioning mechanisms, and more particularly to ratchet stepping mechanisms for positioning a rotary device by moving it in a .step-by-step fashion.

The invention has as its broad and primary object to provide a novel and simple electromechanical mechanism for operating a rotary device step-by-step through predetermined sequential angular increments. Y

Another object of the invention is the provision of such a positioning mechanism which is automatically responsive to momentary closing of a control switch to operate a rotary device, moving it from one position to another, and then to shut itself ofi.

A further object of the invention is to provide a ratchet lstepping mechanism which will self-cycle or step through a number of positions automatically.

It is also an object of the invention to provide such apparatus in which the rotary device is capable of being selectively operated either electrically or manually.

A specific object of the invention is the provision of a self-cycling ratchet stepping device adapted for remote control, and in which a single control impulse from a remote switch will cause the mechanism to step, or cycle, until a desired predetermined position is reached.

More specifically, it is an object of the invention to provide apparatus embodying the broad concepts of the invention and particularly suited for remote actuation of channel selector switches in television receivers.

Another specific object of the invention is to provide such apparatus whereby channel selection is predetermined, yet easily changeable, as desired.

A further and still more specific object of the invention is to provide mechanism of the above-stated type which is simple in construction and operation, easy to adjust, yet is characterized by rugged construction.

In accordance with the present invention, and rst briefly described, the mechanism includes a motorized self-cycling stepping ratchet wheel which, in response to momentary closing of a starting switch in a power supply circuit, is moved sequentially and step-by-step through predetermined angular increments by a motor actuated pawl, each angular increment in the illustrated embodiment corresponding to a different television channel. Indexing stops or pins, at preselected positions on the ratchet wheel, operate mechanism controlling a holding switch in the motor circuit to retain the circuit closed during self-cycling of the ratchet wheel, and to shut off the motor when the ratchet wheel is stepped to the next preselected position or channel. Means is provided for stopping operation of the actuating mechanism at a predetermined initial oi rest position whereby sequential cycles thereof all start at the same position.

The invention may be clearly understood from the following detailed description with reference to the accompanying drawings, wherein:

Figure 1 is an elevational view of apparatus embodying the concepts of the invention (the motor not being shown) and showing the device in its rest or starting position;

" nited States Patent O 2,833,976` latented May 6, 1958 ICC Figures 2, 3, 4, 5 and 6 are views similar to Figure l, but showing sequential operational conditions of the apparatus;

Figure 7 is a top plan view of the apparatus; and

Figure 8 is a circuit diagram.

While in its broader aspects, `as mentioned above, the invention is applicable to any appropriate device, the following description is in connection with its use as an operating agency for rotary switches of the type used for channel selection in television receivers.

As viewed in Figure 1, the apparatus comprises a base plate 9 having journalled therein a shaft 10 carrying a stepping ratchet wheel 11 provided with a number of te/eth 12, corresponding to the number of available V. H. F. television channels. Ratchet wheel 11 is pro vided adjacent each tooth 12 with an aperture 13 adapted to receive indexing stops or pins 14, one being shown in each of the apertures designating channels 3, 6 and 10.

Also journalled in base plate 9, upon a shaft 15, is a drive gear 16 arranged to be rotated by motor .17, Figure 7, through pinion 18. The drive engagement between the motor and the pinion may be of any wellknown type but, as shown, comprises driving element 19 and driven element 20, element 19 being secured to the motor shaft 21 while element 20 is formed integrally with pinion 18, the latter being mounted for free rotation upon extension 22 of the motor shaft 21. The motor shown is of the type having an offset motor which, when the motor is energized, centers itself relative to the stator, moving element 19 forwardly in a position to engage element 20 and thereby rotate pinion 18 to drive gear 16.

Journalled on a shaft 24, carried by gear 16 eccentrically of gear shaft 15, is a pawl 25 held against the gear under spring tension, as by spring washer 26, and normally tending to rotate counter-clockwise, with gear 16. However, the pawl is provided with an outturned end portion 27, indicated in dotted line, which engages a cam surface 28 formed on one side of a slot or aperture 29 in base plate 9, and4 thus is guided into engagement with the teeth on the ratchet wheel, the extent of the swinging movement of the pawl being determined by the width of slot 29. l

Also journalled on base plate 9, as by shaft 30, is suitable lever means which, in the present embodiment comprises rocker-arm or bell crank 31 including arm elements 32 and 33. Element 33 is independently journalled on shaft 30 over element 32 but is releasably held against the lower portion 34 of element 32 by spring 35. One end of spring 35 is connected to a lateral extension 36 at the lower end of the link 33, and its other end connected to a portion 33a of arm 34 bent around the lower left-hand edge of link 33. The bell crank has been constructed in this manner to provide independent movement of link 33, if for some Lreason bell crank 31 fails to function properly while the ratchet wheel is being rotated.

It will be noted that link 33 of the bell crank is provided on its left-hand edge with a cam portion 37, the purpose of which will be explained later. The upper end of the bell crank is bifurcated, providing a recess 38 and two linger elements 39 and 40. A circuit holding switch 41 including a resilient contact element 42 and a fixed contact member 43 is mounted on panel 9 with the end of contact element 42 extending into recess 38.

AFinger 40 is provided with an outwardly turned cam follower or lug 44 which, as shown in Figure l, is normally engaged by a cam surface or track 45 formed 4by a depending portion of gear 16. Lug 44 is shown, in Figure l, in a generally central position relative to the cam surface, the latter being formed with an arcuate central portion and outwardly ared end portions.

Also journalled on shaft 30 is a link 46 extending to the left beneath gear 16. The link is provided in an edge portion thereof with a detent 47 releasably engaging a pin 48 depending from the inner side of gear 16. The .link is biased clockwise against pin 48 as by spring 49. In Figure 1, the pin is shown at the bottom of detent 47 thus positioning the mechanism in its rest or starting position.

Shaft is provided with extensions 50 and 51, shown in broken lines in Figure 1. Aknob 52 is shown attached to the end of shaft extension 50 for manually rotating the channel selector switch (not shown) in the tuner housing indicated by the numeral 53 at the end of shaft extension 51.

Motor 17, as shown in Figure 8, may be connected in circuit with a suitable source of energy, identified by the letter 1., through holding switch 41 Aand/or manually operable control switches 54 and 55. Switch 54 may be mounted on the cabinet of the television receiver, while switch 55 may be situated at a position removed from the receiver thereby enabling the motor to be energized from a remote position. While only two operating switches have been shown, it is understood that any convenient number may be provided.

In the operation of the apparatus described above,

either one of switches 54 or 55 (Figure 8) may be closed f momentarily to energize motor 17, at which time armature 23 centers itself relative to the stator, moving shaft 21 forwardly to engage driving element 20, as is clearly shown in Figure 4, and rotate gear 16 in a counterclockwise direction. It will be seen from Figure 1, showing the mechanism in the rest or starting position, that carn follower 44 of bell crank 31 is engaging cam surface 45, and nger 39 is holding switch 41 open, while cam portion 37 of link 33 is held slightly spaced to the right of the indexing pin 14, at channel 3. Also, pawl is in its retracted position at the upper end of the cam slot 29 in base 9. When the mechanisms are in this condition it will be seen that ratchet Wheel 11 is free to be rotated in either direction, thus permitting manual tuning, as by knob 52, if desired.

Upon momentary closing of either of switches 54 or 55, as mentioned above, gear 16 is rotated in a counterclockwise direction. When it has rotated through approximately 90, as shown in Figure 2, cam follower 44 has been released from cam track 45, permitting arm 32 of bell crank 31 to be moved in a clockwise direction by spring 56, permitting holding switch 41 to close, and moving cam portion 37 on link 33 against pin 14 at channel 3. Pawl 25 is now engaging the tooth 12 opposite the aperture 13 at channel 9. It will be understood that the condition shown in Figure 2 is arrived at almost instantaneously with the momentary closing of either of switches 54 or 55. Note thatthe holding switch 41 now is closed and therefore the starting switch may be released without stopping the operation of motor 17.

Continued rotation of gear 16, as shown in Figure 3, urges pawl 25 to its completely advanced position to rotate the ratchet wheel 11 through one angular increment, indicated at A. This moves the indexing pin 14 at channel 3 away from cam portion 37 of arm 33, bringing the empty aperture 13, at channel 4, opposite the cam portion, and permitting the latter to move into Vthe path of rotative movement of the next indexing pin,

at channel 6.

A single complete rotation, or cycle, of gear 16 is illustrated in Figure 4. Pawl 25 is again in its retracted position with its end 27 moved, as guided by cam surface 28, out of the path of rotation of ratchet wheel 11. Bell crank 31 has moved in a clockwise direction, and therefore cam lug 44 on the end of finger 4G is out of the path of movement of cam surface 45, and holding switch 41 stays closed, leaving motor 17 energized. vAs a result, gear 16 is again conditioned to start through another cycle of rotation and will move ratchet wheel 11 through another angular increment, as described above, wherein the aperture at channel 5 will be moved opposite to cam portion 37, and, as there has been no movement of the cam follower 44 in a counter-clockwise direction, completion of the second cycle will see hold* ing switch 41 still closed and gear 16 will start another cycle.

With reference to Figure 5, illustrating the condition of the mechanism just after the beginning of the third cycle, it will be noted that pawl 25 is against the tooth 12 opposite channel 11, and cam 37 on link 33 is in contact with the indexing pin 14 at channel 6. Further rotation of gear 16 moves pawl 25 downwardly to rotate ratchet wheel 11 through another increment to the position shown in Figure 6. In reaching this position, indexing pin 14 at channel 6 has moved against the cam portion 37 rotating the bell crank in a counter-clockwise direction, a distance suicient to place cam lug 44 in the path of rotation of the ared end of cam track 45, the latter two elements being shown in Figure 6 at the actual point of contact just prior to completion of the third cycle. In this position, finger 39 of link 32 is moving against the flexible contact element 42 of switch 41, and pin 48 is approaching detent 47 of link 46. Continued rotation of the gear causes the cam track to move the bell crank farther in the counter-clockwise direction,- opening switch 41 and deenergizing motor 17, however inertia carries the mechanism to the fully at rest position, illustrated in Figure 1, wherein cam lug 44 is in the arcuate portion of cam track 45, and pin 48 is at the bottom of detent 47. The cam surface 45 is so formed as to move the bell crank still farther in a counterclockwise direction, a distance sufficient to disengage cam 37 from the indexing pin at channel 6 at the completion of the cycle, whereby the equipment is conditioned to respond to channel 6 and shaft 10 is again free to be rotated manually by knob 52.

Having described the operation of the apparatus as between two spaced channel positions, its operation between any two predetermined positions, as established by pins 14, may be easily understood. t should also be understood that the apparatus may be made to cycle past the indexing pins merely by holding one of switches 54 or 55 closed. Release of the switch will cause the mechanism to stop at the next predetermined position established by one of pins 14. It will, of course, be clear from the foregoing description that selection of the desired channels requires nothing more than insertion of the pins 14 in the proper corresponding apertures.

It is evident that various modifications may be made in the structure without departing from the invention. For example, the number of teeth 13 may be changed, the throw of pawl 25 may be modified, etc., to meet various operating conditions, as desired.

We claim:

1. A self-cycling ratchet stepping mechanism, cornprising: a ratchet wheel to be rotated step-by-step through predetermined angular increments; means for rotating said wheel including, a pawl, a motor, and means interconnecting said pawl and said motor whereby, when energized, said motor will drive said pawl through reciprocatory movements; means for guiding said pawl against said wheel during such movement to move said wheel, one increment for each complete reciprocation of said pawl; a source of power; a control switch to energize said motor from said source; a circuit holding switch; a bell crank; means at predetermined positions on said wheel to condition said bell crank to open said holding switch; and means operable by said means interconnecting said pawl and said motor to effect movement of said bell crank to open said holding switch and stop operation of said motor.

2. A self-cycling ratchet stepping mechanism, comprising: a wheel having a plurality of ratchet teeth arranged to be rotated step-hy-step through predetermined angular increments, each increment being equal to the distance ybetween said teeth; means for rotating said wheel, including a gear, a pawl carried eccentrically upon said gear, and a motor for rotating said gear to drive said pawl through reciprocatory movement; means for guiding said pawl against said teeth during such movement in a manner to move said wheel one increment for each complete reciprocation of said pawl; a source of power; a circuit connecting said motor to said power source; a manually operable switch to close said circuit and energize said motor; a circuit holding switch; a bell crank; means at predetermined positions on said wheel to condition said hell crank to open said holding switch; and means asso* elated with said gear to effect movement of said bell crank to open said holding switch and stop operation of said motor.

3. A self-cycling stepping mechanism, comprising: a shaft; a wheel mounted upon said shaft and having a plurality of ratchet teeth dening increments of rotation; a gear; a motor for driving said gear; a power circuit for energizing said motor including, a source of electrical energy, at least one manually operable normally open control switch for closing said circuit, and an automatically operable holding switch for retaining said circuit closed after said control switch is opened; a pawl having one end pivotally mounted upon said gear eccentrically of the axis of said gear and its other end arranged to engage said teeth whereby rotation of said gear moves said pawl through reciprocatory movements between a retracted position away from said Wheel and an advanced position engaging one of said teeth and moving the wheel through one rotative increment; a bell crank; indexing stop means on said wheel; a cam track on said gear; cam follower means on one arm of said bell crank releasably engaging said cam track; means on said bell crank for retaining said holding switch open when said cam follower is so engaged and to close said holding switch when disengaged therefrom; and cam means at the other arm of said bell crank cooperable with said indexing means to condition said cam follower to re-engage said cam track and open said holding switch to stop operation of said motor.

4. Apparatus for angularly positioning a rotatable shaft, comprising; drive means releasably coupled to said shaft and adapted to rotate the same through angular step-bystep increments; motor driven means for imparting the incremental motion to said drive means; switch means actuatable either to energize or deenergize said motor driven means; indexing means movable in step-by-step iashinn with said shaft; and lever means pivotally mounted intermediate end portions thereof and including cam means adiacent one of the end portions operable to actuate said switch means to energize the motor driven means, and cam means adjacent the other of the end portions of said lever means operable by said indexing means, when the latter reaches a predetermined position, to provide for actuation of said switch means to deenergize the motor driven means.

References Cited in the iile of this patent UNlTED STATES PATENTS 2,646,910 Barnett July 7, 1936 2,409,895 Phelps Oct. 22, 1946 2,433,805 Wolit Dec. 30, 1947 2,637,835 Davidson May 5, 1953 2,651,397 Miller Sept. 8, 1953 2,689,281 Hooker Sept. 14, 1954 2,798,259 Feldhausen et al May 1G, 1955

Images