US3446083A - Two-speed tuner drive system - Google Patents

Description

May 27, 1969 J. G. BADGER TWO-SPEED TUNER DRIVE SYSTEM Sheet Filed Feb. 10, 1967 INVENTOI? J05 a. BADGER Afforneys y 7. 1969 J. G. BADGER 3,446,083

TWO-SPEED TUNER DRIVE SYSTEM Filed Feb. 10. 1967 FIG. 9

INVE/VTUR JOE 6. BADGER B Attorneys United States Patent 3,446,083 TWO-SPEED TUNER DRIVE SYSTEM Joe G. Badger, Bloomington, Ind., assignor to Sarkes Tarzian, Inc., Bloomington, Ind., a corporation of Indiana Filed Feb. 10, 1967, Ser. No. 615,247 Int. Cl. F16h 35/18 US. Cl. 74-10.5 6 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to television tuners, and, more particularly, to a swo-speed drive mechanism for such tuners. It is a primary object of the invention to provide a new and improved drive mechanism for television tuners which is simple and economical to manufacture while at the same time providing precision operation of the tuning mechanism.

In certain instances it is desirable to provide a tuner having a two-speed drive mechanism which requires very low torque on the tuning knob to effect both high speed and low speed operations. This low torque requirement cannot be met in most of the tuners presently available because the drive mechanism itself inherently requires a large amount of torque for adjustment and additional loading on the dial indicator sleeve increases the torque which must be exerted by the user to make the desired tuner adjustments.

It is, therefore, another object of the present invention to provide a new and improved two-speed drive mechanism which requires relatively little torque to effect the desired tuner adjustments.

It is a further object of the present invention to provide .a new and improved two-speed tuner drive mechanism in which facilities are provided for limiting movement of the tuner shaft without bending or twisting thereof upon the application of a large torque to the tuning knob.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings in which:

FIG. 1 is a perspective view of the two-speed drive mechanism of the present invention shown in conjunction with a UHF television tuner;

FIG. 2 is a right-hand view of the drive mechanism of FIG. 1 shown with a portion of the drive housing broken away;

FIG. 3 is a sectional view taken along the line 33 of FIG. 2;

FIG. 4 is a sectional view, on a somewhat enlarged scale, taken along the lines 44 of FIG. 3;

FIG. 5 is a fragmentary sectional view on an enlarged scale taken along the line 55 of FIG. 2;

FIG. 6 is a view similar to FIG. 5 but showing the lost motion connecting means in a different position;

FIG. 7 is an enlarged fragmentary sectional view taken along the line 7-7 of FIG. 2; and

3,446,083 Patented May 27, 1969 FIGS. 8 and 9 are fragmentary sectional views taken along the lines 33 of FIG. 2 and illustrating the action of the stop mechanism provided for the main tuning shaft of the UHF tuner.

Referring now to the drawings, the two-speed tuner drive arrangement of the present invention is therein illustrated as comprising a drive housing indicated generally at 10 which is provided with a rear wall 11 and end walls 12 and 13 and shallow side flanges 14. A cover 15 is provided with tongue portions 16 which are secured to ends 12 and 13 of the housing 10 by means of screws 17 to house the mechanical parts-of the two-speed drive mechanism. The rear wall 11 of the housing 10 is arranged to be secured to an end wall 20 of a UHF tuner indicated generally at 22 and having a cover 23, the housing 10 being secured to a plate 24 positioned on the end wall 20 of the tuner 22 by means of the screws 26. The main tuning shaft 28 of the UHF tuner 22 extends through a clearance opening 30 in the rear wall 11 of the housing 10 and a hub 32 is secured to the end of the tuning shaft 28 by means of the set screw 34. A main tuning gear 36 is secured to the hub 32 by any'suitable means such as staking.

In order to drive the main tuning shaft 28 of the UHF tuner at a relatively slow speed to provide fine tuning to a particular UHF station while at the same time permitting a high speed direct drive connection to the shaft 28 through the gear 36, there is provided a stop lever indicated generally at 40 which is provided with a clutch plate portion 42 positioned on the hub 32. The clutch plate portion 42 is urged into engagement with a friction plate 44 position between the clutch plate 42 and the main gear 36 by means of a spring washer 46 which is held in place by a C washer 48.

Rotation of the stop lever 40 produces a slow speed rotation of the gear 36, and hence the shaft 28, through the friction plate 44. On the other hand, when the stop lever 40 is retrained by means to be described in more detailed hereinafter, the main gear 36 may be drive directly at high speed while the clutch plate portion 42 slips with respect to the main gear 36.

A two-speed control shaft 50 which carries a two-speed tuning knob 52 on the outer end thereof is secured to an input hub member 54 provided with a rearwardly extending pin portion 56 of reduced cross section which is rotatably mounted in an aperture provide in an offset portion 58 which is struck inwardly from the rear wall 11 of the housing 10. The forward end of the two-speed tuning shaft 50 is supported by means of a flange '69 which is formed in the cover 15. The shaft 50 is rigidly connected to the hub 54 by means of knurling, transverse pinning, cement, or any other suitable means, so that the shaft 50 can transmit substantial torque to the member 54. The hub 54 is provided with a radially extending flange 60 which carries on the forward face thereof adjacent the periphery thereof an annular series of teeth 62 which mate with a corresponding annular series of teeth 64 provided on the rear face of a transfer disc 66. The transfer disc 66 is loosely supported on the input hub 54 and carries a forwardly extending lost motion drive lug 68 which is positioned on the forward face thereof. An indicator sleeve 70 surrounds the shaft 50 and is provided with a cup-shaped portion 72 shaped to fit around the input hub 54 and having a series of gear teeth 74 formed in the exterior thereof which mesh with the teeth of the main gear 36. The sleeve 70 is further provided with a second cup-shaped portion 7-6 of larger diameter than the cup-shaped portion 72, the lip of the cup-shaped portion 76 being adjacent the forward surface of the transger disc 66. A lost motion driven lug portion 78 is provided inside the cup-shaped portion 76 which is adapted to be engaged by the driving lug 68.

The rear face of the radial flange portion 60 of the input hub 54 is urged into engagement with a clutch member 80 of suitable material, such as cork, which is arranged to transmit rotation of the input hub 54 to a cam plate member 82 which is rotatably mounted on the pin portion 56 of the input hub 54. The periphery of the cam plate 82 is formed to provide an eccentric cam surface with respect to the axis of rotation of the shaft 50 and is provided with a projecting stop lug portion 84.

The stop lever 40 is provided with an offset, right angle follower arm portion 86 terminating in a right angle end portion which rides on the cam surface of the plate 82, this right angle end portion having a piece of tubing 88 of a material having a low coefiicient of friction secured thereon for sliding engagement with the cam surface of the plate 82.

In accordance with an important feature of the present invention, the teeth 62, 64 of the members 66 and 60 and the clutch comprising the members 60, 80 and 82 are held in engagement with the desired amount of force by means of an arrangement which does not place a load on the indicator sleeve 70. Furthermore, this arrangement is one wherein a single spring provides the desired clutch pressure and also acts to hold the follower arm 86 against the periphery of the cam plate 82. More particularly, a cradle member indicated generally at 90 is pivotally mounted on the main housing and is provided with a pair of ears 92, 93 which ride on the forward face of the transfer disc 66 outside the periphery of the cup portion 76 of the sleeve 7 0.

The cradle member 90 is provided with an upward extending notch portion 94 which provides clearance for the indicator sleeve 70 and a pair of rearwardly extending flanges 96 which terminate in outwardly extending pintles 98 which are received behind upwardly extending lugs 100 on the upturned side flange 14 of the main bracket 10 to provide a pivot for the cradle 90. A coil spring 104 is connected between one of the arms 96 and an offset arm portion 106 of the stop lever 40. The cradle member 90 is pivotally mounted by engagement of the pintles 98 with the shoulders 100 and the spring 104 causing the ears 92 to exert a rearwardly directed force against the transfer disc 66. Accordingly, the teeth 62, 64 are held in mesh and the input hub 54 is urged against the cam plate 82 so that rotation of the two-speed tuning knob 52 produces rotation of the cam plate 82. The spring 104 also exerts a clockwise directed force on the follower arm 86 of the stop lever 40, when viewed as in FIG. 5, for example, so that this arm is held in engagement with the periphery of the cam plate 82.

It should be noted that the forces exerted on the transfer disc 66 and the clutch plate 80 are not exerted through any portion of the indicator sleeve 70 so that the sleeve 70 is free to move and may be connected to any suitable dial indicator. If a very low torque indicator, such as a simple pointer, is connected to the sleeve 70, an extremely low torque drive mechanism is provided. This means that a very low torque is required to be exerted on the fine tuning knob 52 to move the cam plate 82 throughout its entire fine tuning range. Also, when a direct drive through the indicator sleeve 70 is achieved for high speed rotation of the shaft 28, only a low torque need be exerted on the knob 52 since the dial sleeve 70 adds only a low torque in the total assembly of driving parts. In this connection, it will be noted that the sleeve 70 is provided with a clearance opening through the center thereof to provide for sidewise play with respect to the shaft 50. Also, the sleeve 70 is only loosely retained between the forward surface of the transfer disc 66 and the rear surface of the cover 15.

From the foregoing, it will be seen that when the tuning knob 52 is initially rotated, the input hub functions to drive the cam plate 82 through the friction clutch 80 and as the cam plate 82 is rotated, the stop lever 40 transmits a slow speed rotational movement to the main tuning shaft 28 through the clutch member 44 as the follower arm 86 follows the peripheral cam surface of the plate 82. This slow speed rotation of the main tuning shaft 28 continues for somewhat less than 360 rotation of the shaft 50 until the stop lug 84 strikes the end of the follower arm 86. Thus, if the two-speed tuning shaft 50 is rotated in the counterclockwise direction, as viewed in FIG. 6, the edge of the stop lug 84 engages the member 88 on the end of the arm 86, the outer edge 108 of this lug being moved into engagement with the other side of the tubular member 88 when the shaft 28 is rotated in a clockwise direction. The follower arm 86 thus moves from the position shown in full lines in FIG. 7 to the position shown in dotted lines in this figure to provide a slow speed adjustment of the main tuning shaft 28.

When the cam plate 82 is thus restrained from further rotation, the input hub 54 continues to drive the transfer disc 66, and when the driving lug 68 on this disc picks up the driven lug 78 provided on the sleeve 70, the gear teeth 74 on this sleeve function to drive the main gear 36 and hence the main tuning shaft 28, at a relatively high speed to provide rapid selection of a different television channel in a different portion of the UHF band. When the gear 36 is rotated at high speed, the clutch member 44 slips since the stop member 40 is restrained from further rotational movement by the fact that the cam plate 82 can no longer rotate.

As soon as a new UHF tuning area is reached, rotation of the tuning knob 52 in the opposite direction is effective to move the cam plate 82 so that the stop 84 is moved away from the member 88 and a slow speed fine tuning operation is thus performed in the new UHF tuning area. As this occurs, the driving lug 68 moves away from the driven lug 78 so that the main gear 36 is no longer rotated at high speed. However, when the fine tuning knob 52 is rotated almost a full revolution in the opposite direction, the driving lug 68 picks up the driven lug 78 on the opposite face thereof and again provides a high speed direct driving connection to the main tuning shaft 28.

In accordance with a further feature of the invention, movement of the main tuning shaft 28 is limited without bending or twisting of this shaft when excessive torque is exerted on the knob 52. More particularly, the main gear 36 is provided with a pair of forwardly projecting lugs 112 and 114. These lugs are adapted to engage opposite edges of a stop lug 116 (FIG. 2) which is formed rearwardly from the front wall of the cover member 15. The lugs 112 and 114 are positioned so that the rotational movement of the main tuning shaft is sufficient to cover the entire UHF band. Thus, when the tuning shaft 28 is in one extreme position, the lug 114 is in engagement with one edge of the stop 116, as shown in FIG. 8. When the main tuning shaft 28 has been rotated through the entire tuning range, the lug 112 is moved into engagement with the other edge of the lug 116, as shown in FIG. 9.

The lugs 112 and 114 are positioned near the periphery of the gear 36 and the stop member 116 is positioned close to the plane of the gear 36. With this arrangement, the force which is transmitted to the periphery of the gear 36 through the driving gear 74 does not produce any bending or twisting movements which would tend to cause gears 74 and 36 to separate. Also, since the lugs 112, 114 are near the periphery of the gear 36 better control over the limits of travel of the shaft 28 can be obtained, insofar as tolerances, etc. are concerned. Also, by positioning the lugs 112 and 114 on the gear 36 rather than in association with the main tuning shaft 28, the large external forces which may be exerted on the periphery of the gear 36 are not transmitted to the tuning shaft 28 as is the case if internal stops within the UHF tuner are relied upon to limit travel of the shaft 28. This is particularly important because the shaft 28 is in many instances notched down to provide a suitable bearing area as it enters the UHF tuner 22 and hence is relatively weak and susceptible to twisting or bending forces at this point. Furthermore, as noted above, since the stop 116 engages the lugs 112 and 114 in substantially the same plane as the one in which force is exerted on the gear 36, no bending or twisting forces are experienced when the stop 116 is reached and a large force is exerted on the knob 52. Also, since the lugs 112 and 114 are provided on the gear 36, the hub 32 may be adjusted relative to the shaft 28 to provide a desired alignment by simply loosening the set screw 34 and moving the shaft 28. The set screw 34 may then be tightened and the new alignment position is maintained because no large forces are exerted on the shaft 28 through the hub 32.

Even though the stop 116 is capable of withstanding a substantial force without bending of the shaft 28 or producing gear separation, it is desirable to limit the maximum amount of torque which can be exerted on the twospeed tuning mechanism. To this end, the force exerted by the spring 104 on the cradle 90 which urges the teeth 64 on the transfer disc 66 into engagement with the teeth 62 on the input hub '54 may be overcome by exerting a large rotational force on the knob 52. When this occurs, the teeth 62 slip or ride over the teeth 64 on the transfer disc 66 so that a declutching action is provided between these members to limit the maximum torque which may be transmitted through the transfer disc 66 and the teeth 74 on the sleeve 7 0 to the main gear 36.

In accordance with another aspect of the present invention, the main housing 10 is arranged to be oriented in any one of a number of angular positions with respect to the UHF tuner to accommodate various orientations of the tuner within a television receiver cabinet. Furthermore, variations in orientation of this housing are accomplished, while providing for adjustment of gear engagement between the gears 74 and 36. More particularly, a number of mounting holes 120 are provided on the rear wall 11 of the housing 10 so that the mounting screws 26 may be inserted in any one of these holes to provide a desired orientation of the housing 10 with respect to the tuner 22. The holes 120 are elongated in the direction of a line connecting the axes of the shaft 50 and the main tuning shaft 28. Accordingly, the housing 10 may be positioned along this line at the desired location to provide the correct separation between the gears 74 and 36 after which the screws 26 are tightened to maintain the housing in fixed relation to the tuner 22. Furthermore, such an arrangement permits adjustment to different sized gears without requiring redesign of the drive assembly. In addition, inexpensive parts may be used while providing precision gear action by adjustment in the direction of the gear centers prior to locking of the mounting screws 26.

While a preferred embodiment of the invention has been described by way of illustration, many modifications will occur to those skilled in the art.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a tuner, a tuning shaft, a stop member mounted for rotation about the axis of said tuning shaft, clutch means interconnecting said stop member and said tuning shaft, a control shaft rotatably mounted at a point offset from said tuning shaft, an input disc connected to said control shaft and having a first series of teeth, a transfer disc rotatably mounted on said control shaft and having a second series of teeth in engagement with said first series of teeth, a cam plate rotatably mounted on the axis of said control shaft, a clutch plate between said cam plate and said input disc, a pivotally mounted bracket having a pair of ears engaging said transfer disc at points spaced from the axis of said control shaft, and spring means interconnecting said bracket and said stop member so that said ears urge said first and second discs, said clutch plate and said cam plate together so that said cam plate is driven from said control shaft, said spring means also acting to urge said stop member into engagement with the periphery of said cam plate, whereby said tuning shaft is driven at relatively slow speed in response to rotation of said cam plate.

2. In a tuner as set forth in claim 1, the arrangement which includes means defining a lug extending from one edge of said cam plate beyond the cam surface thereof and adapted to engage said stop member to limit rotation of said cam plate to less than 360.

3. In a tuner, a main tuning shaft, a control shaft, a cam plate mounted for rotation on the same axis as said control shaft, clutch means interconnecting said control shaft and said cam plate, a cam follower member mounted for rotation about the same axis as said main tuning shaft and including an arm urged into engagement with the edge of said cam plate, clutch means interconnecting said follower member and said main tuning shaft so that rotation of said control shaft is effective to drive said main tuning shaft through both said clutch means at a relatively slow speed, stop means on said follower member for limiting rotation of said cam plate to less than 360, first gear means rotatably mounted on said control shaft, second gear means connected to said main tuning shaft and in mesh with said first gear means, means operative when a rotational limit of said cam plate is reached to drive said main tuning shaft from said control shaft at a relatively high speed through said first and second gear means and independently of said clutch means, first stop means on said second gear means, and stationary stop means positioned between the axes of said main tuning shaft and said control shaft and cooperating with said first stop means for limiting rotation of said main tuning shaft.

4. In a tuner, a housing, a tuning shaft extending through said housing, a gear secured to said tuning shaft, a stop member rotatably mounted on said tuning shaft, friction clutch means for urging said stop member into engagement with said gear, a drive housing connected to said tuner housing, a control shaft rotatably mounted in said drive housing at a point offset from said tuning shaft, an input disc connected to said control shaft and defining a series of forwardly facing teeth, a transfer disc rotatably mounted on said control shaft and having a series of rearwardly facing teeth adapted to mesh with said forwardly facing teeth, a cam plate rotatably mounted on said control shaft, a clutch plate between said cam plate and said input disc, a pivotally mounted bracket having a pair of ears engaging said transfer disc at points spaced from the axis of said control shaft, an indicator sleeve rotatably mounted on said control shaft and having drive gear means which is in engagement with said first named gear, spring means interconnecting said bracket and said stop member so that said ears urge said first and second discs, said clutch plate and said cam plate together so that said cam plate is driven from a said control shaft, said spring means also acting to urge said stop member into engagement with the periphery of said cam plate, whereby said tuning shaft is driven at relatively slow speed in response to rotation of said cam plate, means defining a stop on said cam plate which engages said stop member and limits rotation of said cam plate to less than 360, and lost motion means interconnecting said transfer disc and said indicator shaft for driving said tuning shaft through said first and second series of teeth and said drive gear at a relatively high speed.

5. In a tuner, a tuning shaft, a gear secured to said tuning shaft, a stop member rotatably mounted on said tuning shaft, friction clutch means for urging said stop member into engagement with said gear, a control shaft rotatably mounted at a point offset from said tuning shaft, a cam plate rotatably mounted on said control shaft, clutch means interconnecting said cam plate and said control shaft, an indicator sleeve rotatably mounted on said control shaft and having a drive gear integral therewith which is in engagement with said first named gear, a. pivotally mounted bracket in engagement with said clutch means, spring means interconnecting said bracket and said stop member so that said cam plate is driven from said control shaft, said spring means also acting to urge said stop member into engagement with the periphery of said cam plate, whereby said tuning shaft is driven at relatively slow speed in response to rotation of said cam plate, means defining a stop on said cam plate which engages said stop member and limits rotation of said cam plate to less than 360, and lost motion means interconnecting said control shaft and said indicator shaft for driving said main tuning shaft through said drive gear at a relatively high speed.

6. In a tuner, a tuning shaft, a gear secured to said tuning shaft, a stop member rotatably mounted on said tuning shaft, friction clutch means for urging said stop member into engagement with said gear, a control shaft rotatably mounted at a point offset from said tuning shaft, a first release member secured to said control shaft, a second release member rotatably mounted on said control shaft and normally in mesh with said first release member, a cam plate rotatably mounted on said control shaft, a clutch disc between said cam plate and said first release member, a pivotally mounted bracket having a pair of ears engaging said second release member at points spaced from the axis of said control shaft, an indicator sleeve rotatably mounted on said control shaft and having a drive gear integral therewith which is in engagement with said first named gear, spring means interconnecting said bracket and said stop member so that said ears urge said first and second release members, said clutch disc and said cam plate together and said cam plate is driven from said control shaft, said spring means also acting to urge said stop member into engagement with the periphery of said cam plate, whereby said tuning shaft is driven at relatively slow speed in response to rotation of said cam plate, means defining a stop on said cam plate which engages said stop member and limits rotation of said cam plate to less than 360, and lost motion means interconnecting said second release member and said indicator shaft for driving said tuning shaft through said first and second release members and said drive gear at a relatively high speed.

References Cited UNITED STATES PATENTS 3,251,234 5/1966 Valdettaro 7410.8 X

FOREIGN PATENTS 609,651 10/1948 Great Britain.

MILTON KAUFMAN, Primary Examiner.

US. Cl. X.R. 74--10.6, 10.8

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