US2060546A - Automatic program selector for radio receivers - Google Patents

Description

NOV. 10, 1936. w; ALLEN, JR 2,060,546

AUTOMATIC PROGRAM SELECTOR FOR RADIO RECEIVERS Filed 'April 29, 1955 I 2 Sheets-Sheet 1 c FIGIZT /b v 56 /'3'I I INVEN TOR M .1.@11-.. yr.

Nov. 10,1936. w A L JR 2,060,546

AUTOMATIC PROGRAM SELECTOR FOR RADIO RECEIVERS Filed April 29, 1935 2 Sheets-Sheet 2 FIRE I6 I 31 l:

l6 b ns-i ise IN VEN TOR am; w. w i

Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE Edward W. Allen, Jr., Washington, D. C.

Application April 29,

18 Claims.

This invention relates to automatic tuning devices for radio receivers.

Heretofore in the art, automatic control devices which are adapted to reset the tuners of radio receivers at given intervals have employed a clock or timing mechanism to determine the time at which the tuner is to be reset and which controls a motor or source of power which performs the work of resetting the tuner. In the ma- 10 jority of these devices, the clock closes electrical contacts which control an electric motor and causes it to set the tuner to the desired position. It has been found that such contacts, exposed to grease and dirt over a long period of time, are

conducive to false operation of the device.

In order to assure positive operation of such devices it has been found desirable to employ mechanical means for performing the desired functions wherever possible.

It has been known heretofore to control the automatic selection of radio programs by automatic mechanical means, but in all such devices of which I am aware, it has been necessary in setting up each sequence of programs to make individual adjustments of the stops which determine the tuning of the set. When such adjustments are necessary, a great deal of care must be exercised in order to assure the proper tuning, and where a long series of programs is desired such a procedure may be exceedingly tedious. In some devices of this nature it is even necessary to tune the set to each station to make the adjustment. In the invention herein described, such a procedure is not necessary.

In the majority of localities, owing to our present system of broadcasting networks, any desired sequence of programs may usually be obtained by the proper sequential selection of programs from a few, say three or four, broadcasting stations. In the herein described invention, a plurality of stops, equal in number to the broadcasting stations usually selected, are provided. By tuning the radio set to these stations in turn, the stops may be adjusted to control thereafter the tuning of the set. So long as these same stations are selected in future programs, regardless of the sequence in which selected, these stops will not be again adjusted. In many cases, they may be adjusted by the dealer or servicing agency in accordance with the wishes of the owner upon the purchase of the set and never be changed thereafter.

For the purpose of setting up any given sequence from the programs broadcast by the selected stations, a series of selector elements is.

1935, Serial No. 18,956

provided each of which is manually adjustable to positions one greater in number than the stops. The adjustment of an element to one of the positions prevents any of the stops from acting and corresponds to a no program or off position. The adjustment of the element to any other position causes the corresponding stop to control the tuning of the set. It is thus apparent that by making the selection of a station dependent upon the adjustment of the element to one of, say, four positions, each of which may be quickly and easily selected, instead of to any one of a hundred or more positions which must be adjusted with care, much of the tedium of setting up the program series is relieved. Further means are provided for rotating the tuning device at intervals corresponding to conventional broadcast periods and for controlling the stops to restrain the tuning device at desired stations in accordance with the adjustment of each of the series of selector elements. For the purpose of disclosing this invention, a period of 15 minutes has been chosen as the broadcast period.

In order to prevent discomfort upon the part of the audience, it is desirable that the set be prevented from responding to signals during the tuning period, and also that all stations be received at the same volume level. Some radio sets are equipped with automatic volume control to perform this function but this has not proven to be entirely satisfactory, particularly where broadcasting stations of widely varying power are concerned. For this reason it has been found desirable to provide herein a mechanically operated volume control which may be separately adjusted for each station, and which has the additional function of silencing the set during the tuning operation.

Accordingly, it is an object of this invention to produce a device which will automatically reset the tuner of a radio receiver to positions corre sponding to desired stations at given intervals and in accordance with a predetermined sequence.

Another object is to produce a device which will silence the radio set during the tuning operation.

Another object is the production of a device which will automatically adjust the volume of signal reception to a uniform level regardless of the power of the transmitting station simultaneously with the tuning action, and which is also manually adjustable to vary this level of reception.

Another object is to produce a device which will turn on the radio set at a desired future time, tune it to various stations in any desired sequence, and turn off the set at the end of the sequence.

Another object is to perform the above functions by mechanical means wherever feasible.

Another object is to supply the mechanical energy necessary to perform the above functions from a single continuously rotating motor of small size.

My invention will be more clearly understood when explained with reference to the drawings, of which:

Figure I is a side view of one form of the device.

Figure II is a broken front view of the same form of the device.

Figure III is a top view of the timing and driving mechanism.

Figure IV is a detailed view of the adjustable stops and separating washers of the stop assembly of Figure I.

Figure V is a detailed view of one of the rotatable selector buttons of Figure I.

Figure VI is a schematic diagram of the electrical connections of the signal silencer and level control of the first modification.

Figure VII is a side view of another form of the device.

Figure VIII is a front view of a manually adjustable selector bar of Figure VII.

Figure IX is a broken front view of the second form of the device.

Figure X is a detailed view of the tip of the selector arm of the second form of device.

Figure XI is an expanded view of a part of the timing and driving mechanism.

Figure XII is a rear view of the assembly for supporting and rotating the selector arm of the second form of device.

Figure XIII is an enlarged side view of the selector element of Figure VIII.

Figure XIV is an enlarged front view of the same element.

Figure XV is a circuit diagram showing the cooperation of the automatic and manual volume control means.

First modificationP-Structure.Referring to Figures I to VI and XI of the drawings in detail, a variable condenser or condenser gang I, whose function is to tune the radio receiver, has a rotary shaft 2 carrying rotor plates in the conventional manner. This condenser is of the 180 type and may conveniently have several degrees of movement beyond its positions of maximum and of minimum capacity. A flat spiral spring 3 is attached at its inner end to the shaft 2 and its outer end attached to the condenser stator at 4, and tends to rotate the rotor to its extreme clockwise position. A setscrew 5, in the hub of gear 6, secures the latter against rotation on shaft 2. Gear 6 carries a pawl I, pivoted at 8, and urged against the rear surface of flat spring member I9 by the spring 9. Gear 6 also carries a pin I which opens the power supply switch 60 when the rotor assumes its most clockwise position. Switch 6|! is shown as a simple set of spring supported contacts but may be of any conventional type which is suitable for controlling the power supply of the radio set. A pinion II, carried by a rotatable shaft l2, meshes with gear I5. Shaft I2 carries a pair of governor springs I3 having flyweights I4. When in rotation, springs I3 bear inside of a metallic cup I5 connected to the set antenna as shown in Figure VI. When at rest, one of the springs, which is longer than the other, makes contact with the annular resistor III. This resistor, which may be of the order of 50,000 ohms, is connected at one end to the cup and at the other end to ground, and the position of spring I3 thereon determines the signal input to the radio set.

A bushing 20, rotatably mounted on shaft 2, is prevented from turning therewith by a flat spring member I9 which is secured at its center to the rear or disc portion of bushing and is supported at its ends by standoff bushings from panel 30. The bushing carries a bossed washer 26 which serves as a spacer and bearing for the eye portion of the selector arm 2| which is freely rotatable thereupon. Washer 26 is prevented from rotating upon bushing 20 by tits, similar to those shown at 28 in Figure IV, which engage two grooves in the side of bushing 20. Bushing 20 also carries a plurality of rotatable washers 22, separated by washers 23 having tits 28 to prevent rotation. The rotatable washers 22 have forwardly projecting stops which extend, in a clockwise direction, gradually increasing distances into the path of pointer 29 attached to the end of shaft 2. The pointer 29 has the double function of indicating the condenser setting and acting as a stop to determine this setting under automatic operation. Threaded upon the forward end of bushing 20 is a clamping nut 24 which may be tightened sufficiently to hold washers 22 in any position to which they may have been set. The whole assembly carried by bushing 20 is urged rearwardly under the influence of flat spring I9.

In order to position the assembly in various axial positions and thus determine which of the stops 25 intercepts the pointer 29, panel 30 has a circular array of 48 rotatable buttons 3|. These buttons are divided into sectors w, b, c, (1, having graduated heights and separated by walls e. The buttons may be turned so that any sector will be presented to the tip of the selector arm H and when it rests thereon will determine the axial position of the stop assembly. The walls e which separate the sectors a, b, c, d, serve to lock the selector arm against rotation until it is moved forwardly in an axial direction. Spring washers 32 normally hold the buttons against the panel but allow sufficient forward motion so that the ridge on the rear of the button 3| will ride from one groove in the panel 30 to the other as the button is rotated. The ridge and its cooperating grooves insure correct orientation of the button as Well as a permanent setting until manually rotated.

To provide for rotation of the selector arm 2| to successive ones of the buttons, a slot 21 in spring I9 and the disc portion of bushing 20 allows the pawl I to engage an annular set of ratchet teeth in the eye portion of selector arm 2|. The inclination of pawl I causes the assembly to move forward as the gear 6 approaches its extreme counterclockwise position, until the tip of the arm 2I overrides the wall e of the button upon which it has been resting. The selector arm is then rotated counterclockwise by the pawl until the pawl strikes the end of the slot 21. At this time the arm has rotated until its tip is over the next button. As the gear 5 begins its clockwise motion as hereinafter ex plained, the tip of arm 2| is dropped into the presented sector of this button.

A synchronous motor 33 drives the gear 34 at one revolution each fifteen minutes. Gear 34 drives shaft 35 to which is attached the inner is on the surface of greater radius.

end of flat spiral spring 36. The outer end of spring 36 is attached to the cross member of the U-shaped rider 31. Rider 3! turns freely and has a limited axial movement on shaft 35. A detent 38,'when down, restrains the rider against rotation.' If the detent is lifted, the cam surface I31 of the rider (Figure XI) engages the rear surface of the cam 54 and the rider rotates uniformly with the gear 34. Detent 38 is fixed to the forward end of a rotatable shaft 39 to the rear end of which is fixed an L shaped mem ber comprising the arm 40, terminating in a cam surface which cooperates with pinion 55, and the arm 5|, terminating in a cam follower, which cooperates with the cam 50. Loosely pivoted upon shaft 39- is an inverted U-shaped member 4! having a downwardly extending arm 42 which terminatesin a cam surface extending into the path of rotation of rider 3?, and a second downwardly extending portion which is counterweighted to urge the member in a clockwise direction of rotation and upon which is pivoted the pawl 43. Pawl 44 is loosely pivoted upon shaft 39, and a stop 53 punched from member 4| bears upon its upper side to prevent arm 42 from moving too far into the path of rider 31. Hub 45 is freely rotatable on shaft 35 and carries a gear 46 which meshes with gear 3. Gear 46 has a forwardly extending stop 41 which will clear the crossmember of rider 31 when the latter is restrained by the detent 38 or by the underside of the cam 54. Figure XI is an expanded view of these elements, the operation of which will be explained in detail hereinafter.

A shaft 48 carries a ratchet wheel 49 to the rear side of which is fixed a cam 55 having two circularsurfaces each subtending approximately 180 upon which rides the follower 5|. The approach to the surface of greater radius is in the form of a steep ramp so that the follower 5| will ride thereover during the rotation of ratchet wheel 49 through an angle subtended by one or two teeth. If two teeth are required, the detent should not clear rider 31 until the follower 5| The approach to the surface of lesser radius is radial and allows the follower 5! to drop to this surface immediately. Shaft 48 also carries a pointer 52 which pass-es over an index on the panel. If the panel carries 48 of the buttons 3|, or sufficient to set up programs for twelve hours, the ratchet wheel 49 should have 96 teeth and the index should be divided into two twelve hour periods, one marked Off. when the cam follower 5| is upon the surface of greater radius, and the other marked Oh, when the follower is upon the surface of lesser radius.

To provide for 'manual selection of radio programs, a shaft 55, rotatable and axially movable in split bushing 5l, carries a pinion 56 which is adapted to mesh with gear 46. Moving the pinion rearwardly to mesh it with gear 46 causes it to engage the cam surface of lever 40 and raise the detent 38.

The device as shown is capable of selecting programs from three different stations in any desired sequence at 15 minute intervals over a period of twelve hours. If desired, for convenience in setting up the sequence, the panel 30, carrying the buttons 3|, may be indexed as a clock face, the buttons being located at 15 minute intervals. It will be apparent from the foregoing description that the selector arm is rotated in a counterclockwise direction and the index would have to be arranged counterclockwise. It

would be commercially desirable to have the index in the conventional form, and this may be done by constructing the device as a mirror image of this disclosed in detail herein.

Operati0n.--To adjust the device, the pinion 56 is forced rearwardly into engagement with the gear 46. Split bushing 51 has sufficient friction to hold the condenser in any desired position against the tension of spring 3. The condenser is manually rotated to its extreme counterclockwise position. This allows switch 50 to close and turn on the radio set. Clamping nut 24 is loosened until washers 22, carrying stops 25, are manually rotatable but still have sufiicient friction to remain in any selected position. The stops 25 are manually rotated counterclockwise until the three are bunched against the pointer 29, which will then lie in a horizontal position. The button 3| lying beneath the selector arm 2|, which is then thrust forward with the stop assembly by pawl I, should be rotated so that sector a is presented to the tip of the selector arm. The condenser is then rotated clockwise until the most counterclockwise of the desired stations is reached and the volume set at the desired level. It will be noted that as the condenser is rotated, the spring contact l3 will rotate around the resistor i8, causing the input from the antenna to be varied in recurrent waves. It is imperative therefore that the gear ratio between the gear 6 and the pinion ll be sufficiently high to cause an input peak to occur at each kilocycles around the dial, so that each station will receive a peak. Since a slight movement of the condenser is necessary to effect the desired volume adjustment, the set should have fairly broad tuning characteristics or be designed with a signal seeking circuit such as that disclosed in Radio Retailing for March 1935 at pages 39 and 40, in order that the quality of reproduction be not impaired. Rotation of the condenser to the station causes the bunched stops 25 to be rotated by pointer 29, the first stop resting against the side of the pointer. Next, the button 3| lying next in a counterclockwise direction is rotated manually until sector b is presented to the selector arm tip. The condenser is again rotated to its extreme counterclockwise position, which causes selector arm 2| to be rotated to the second button. lowing the arm to rest on sector I) of this button. Sector I) being lower than sector a, the stop assembly, under the influence of spring |9, assumes a more rearwardly position than before. The pointer 29 passes over the first or shortest of the bunched stops. 25 and engages the second, carrying it and the third stop to a position corresponding to the frequency and volume of the second of the desired stations. The next counterclockwise button is then rotated to present sector 0 and the steps repeated to position the third stop at the desired position. The condenser is then rotated to the extreme counterclockwise position to force the assembly outward and the clamping nut 24 tightened to clamp the stops in a fixed position. Flat spring I 9 is designed to hold bushing 20 stationary while nut 24 is being tightened.

If the button beneath the selector arm is turned to present sector d, the stop assembly assumes its most rearward position and when the condenser is rotated in a clockwise direction the pointer 29 will pass freely over all the stops 25, and the condenser may be turned manually in the conventional manner. Since rotating the The condenser is rotated clockwise, al-

condenser to one extreme position will step the selector arm off the properly adjusted button, and rotating it to the other will turn off the radio set, each of these positions should be beyond the normal tuning range of the condenser or the circuit design be such that the whole broadcast band will lie within these positions.

To condition the receiver for selecting a sequence of programs, the buttons 3| are manually rotated to present sectors o b, or c in the desired order in a counterclockwise direction around the face of the dial. The button immediately preceding the sequence is rotated to present sector (1 and. the selector arm placed thereon. Pinion 56 is pulled forward and disengaged from gear 46, allowing the condenser to rotate to the extreme clockwise position, cutting off the set. Lever 40 drops and allows detent 38 to fall into the path of rider 31 if the pointer 52 indicates On. If Off is indicated, cam follower prevents detent 38 and lever 40 from dropping.

A small synchronous motor 33 drives gear 34 continuously and, if detent 30 is lifted, the rider 31 moves therewith. Each time that the rider engages the cam surface of the arm 42, it rocks the member 4| about the shaft 39 and causes pawl 43 to step ratchet wheel 49 one tooth. This operation continues, one tooth each 15 minutes, until cam follower 5| drops down to the smaller radius cam. This allows detent 30 to drop into the path of rider 31. On its next revolution, gear 34 will tension spring 36 since rider 31 is restrained. When gear 34 has made nearly a complete revolution, the outer surface of cam 54 carried thereby engages the near leg of rider 31 and forces it to the rear until the rider escapes the detent 38. When the condenser is in the extreme clockwise position, the stop 41 on gear 46 is directly opposite the rider and will be engaged thereby when the rider is forced to the rear. As soon as the rider is released from the detent, urged by the spring 36 it will overcome spring 3 and rotate the condenser to the extreme counterclockwise position, stepping ratchet wheel 49 as it passes the arm 42, and stepping the selector arm to the first button of the series as it reaches this position. At this position, the cam surface I31 of the rider engages the inner surface of the cam 54, moving the rider forward and freeing it from stop 41. Selector arm 2| drops to the presented sector of the first button as the condenser slowly rotates clockwise under the control of the governor, due to the action of spring 3, and the corresponding stop intercepts the pointer 29. During rotation of the condenser, the governor springs I3 contact the cup I5 and short-circuit the antenna circuit, silencing the set. When pointer 29 engages the selected stop 25, the longer spring contacts the annular resistor l8 at the point selected for this station, and causes the signals to assume the proper level.

At the end of the next 15 minute period the operation is repeated, the stop 41 on gear 46 not being opposite the detained rider 31 but at a point in its path of travel corresponding to the position of the first station. To assure that the rider, when released under these conditions, will travel close to the gear 46 and contact stop 41, the spring 36 is secured to the shaft 35 and the rider 31 so as to tend to move the rider toward gear 46. To prevent impact of the rider with the stop 41. the spring is made self governing by winding it in a tight spiral, as shown in Figure II, and filling it with a light grease. The dial index for pointer 52 indicates the length of time before the set will begin or cease operation. So long as the pointer is upon the on" side and the manual tuning knob is pulled outward, the set will hunt for a new station each 15 minutes. If the button selected by the arm 2| presents sector 01, the condenser will resume its extreme clockwise position after the hunting action and the set be turned off by the opening of switch 60. Pointer 52 is manually rotatable in a clockwise direction so that operation can be initiated or terminated at any time up to twelve hours later.

Second modification--Structure.-Referring to Figures VII to X, XII, XIII, and XIV of the drawings in detail, the condenser shaft 2, which is spring biased in a clockwise direction by a spring 3 as shown in Figure I, has fixed thereto a bushing I20. The bushing has fixed thereto a gear I06 and is grooved upon its upper and lower sides to accommodate the tits 20 of washers 23. Interposed between washers 23 are adjustable stop m mbers I22 having forwardly projecting stops I25. A clamp nut I24 is threaded on bushing I20 so as to clamp the stop assembly against the shoulder of the bushing. The central openings of members I22 are oval so that they may be adjusted radially as well as circumferentially and the lower ends thereof are in the form of curved legs terminating in cam surfaces I65. A light spring I63, fastened at one end to the shoulder of bushing I20, has a forwardly disposed portion which engages the legs of the members I22 and, when they are released by loosening the clamping nut I24, collects them against the pin I64 which projects from gear I06. Owing to the curved form of the legs, the members are collected in such a manner that the tops of the oval openings lie against the bushing I20. Gear I06 meshes with a pinion I69 which in turn meshes with a gear I10 driving the governor |1I for controlling the speed of rotation of the condenser. Pinion I69 rotates upon a stub shaft carried by lever I14 which is pivoted upon a shaft I12, upon which the gear I10 is freely rotatable. Lever I14 also carries a shielding cylinder I13 formed of material of good electrical conductivity and which is insertable between the primary I60 and the secondary I59 of the antenna coupler. Upon the other end of the lever I14 are cam followers I66 and I61. A manually rotatable male and female spiral cam I60 cooperates with the follower I61. The spiral is open so that the follower may cooperate with either the male or the female surface of the cam. Follower I66 cooperates with cam surfaces I65 and will oscillate the lever in accordance with the radial adjustment of the members I22.

Meshing with gear I06 is a gear train I6| with which the manual control pinion 56 is caused to mesh for manual operation as in the first modification.

Rotatably mounted upon the clamping nut I24 is the selector arm |2| having a hub which terminates at the rear in a disc portion having 96 annular ratchet teeth, equal in number to the adjustable station selector bars I3I, which are, in this modification, sufficient for twenty-four hours of continuous operation. The tip of the selector arm has a pair of cam surfaces upon its under side which straddle the selector bars when the tip of the arm is allowed to rest upon the bars. See Figure X. The selector bars, shown enlarged in Figures XIII and XIV, slide radially in slots I32 in the panel I30. The panel I30 has a series of annular grooves I33 in the rear thereof with which the spring detents 43I on bars I3I cooperate to maintain the bars in any of the four positions selected. Ears 23I and 33I serve to maintain the bars normal to the panel so that they will slide without binding. By sliding the bars inwardly or outwardly, any one of the steps a, b, c, (1 may be made to cooperate with the tip of the arm I2I.

Spring member I I9 has an eye which fits over the hub of selector arm I2 I, and bears against the disc portion thereof, tending to move the selector arm toward the panel. The ends of the spring II9 are supported from stand-off bushings carried by the panel I30. Spring member II9 also has a stop I62 adapted to coact with the stops I25, and a guide slot I21 for pawl I43. Notch 243 of pawl I43 rides on guide I21 which has a rearwardly bent portion which prevents the pawl from engaging more than one tooth of the ratchet I26 for each reciprocation, regardless of the length of the stroke. Pawl I43 is inclined, similar to pawl 1, and the length of the stroke will vary, depending upon the position of the assembly comprising the spring and its associated elements. Pawl I43 is actuated by lever I42 whose lower end lies in the path of the rider 31. A bellcrank I5i, pivoted upon the panel I36, bears against the front of spring H9 and beneath lever 40, which controls detent 38, and lifts the detent when the selector arm I2I rests upon the top step (d') of the selector bars I3I. Counterweight I4I for lever 40 is provided so that a slight pressure of bellcrank I5I is sufficient to raise lever 40.

The spring tensioning and releasing elements 33 to 31, 45, 46, and 41 are not shown in detail in these figures since they are the same as in the first modification. The gear 46, in this instance, drives the condenser gear I06 through the medium of pinion I69 and gear I10. Condenser gear I06 has a pin I0, not shown, to control a switch 60 for the power supply as in the first modification. Pin I64 may be made to perform this function by locating the switch lever close to the gear I06, so as not to interfere with the operation of stop members I22.

Operation.-The cam I68 is rotated to its extreme counterclockwise position, causing the female surface to engage the follower I61 and to rock the lever I14 about the pivot I12. This removes the follower from the paths of the cam surfaces I65 of members I 22 and causes the shielding cylinder I13 to be moved upwardly between the primary and secondary of the antenna coupler. The selector arm I2I is manually pulled forward and set upon step .d' of a selector bar I3I Clamping nut I24, which has a left handed thread, is loosened until a click is heard, denoting that the spring I63 has collected the members I22 against the pin I64. With the manual control pinion 56 disengaged, clamping nut I24 is then tightened until the condenser tends to turn therewith against the tension of the spring 3. This insures proper tension to enable setting the members I22 without being moved thereafter by the spring I63. Manual control pinion 56 is next engaged with the train I6I and the condenser rotated to the extreme counterclockwise position. Three selector bars I 3I are then positioned so that the tip of the selector arm I 2I will rest upon steps 0, b, and a, respectively. Arm I2I is manually placed upon step c of the first bar and the condenser rotated to the most clockwise of the three stations desired to be selected. The longest of the stops I25 will engage the stop I62 and be positioned circumferentially. By rotating the cam I68 clockwise, follower I61 will be moved upward and will cause follower I66 to move member I22 upward, and at the same time will cause the shielding cylinder I13 to be withdrawn from between the primary and secondary of the antenna coupler, increasing the volume of reception. In addition to its shielding efiect, the cylinder I13 has a varying energy absorbing effect, due to its variable coupling with the primary I60 and the secondary I59, which enhances its volume controlling characteristics. When the volume has been adjusted to the desired level, the cam I68 is turned to the extreme counterclockwise position, and the condenser also turned to this position. The selector arm is then placed upon step b of the second bar, the condenser rotated to the next most clockwise station and the volume adjusted as before. These steps are repeated for the adjustment of the third station. After the third station has been adjusted, the clamping nut I24 is tightened sufiiciently to hold all of the members I22 in their adjusted positions when operating to restrain the condenser against rotation by spring 3. Cam I68 is turned to the position shown in Figure IX so as not to interfere with the motion of the lever I14. Se lector arm I2I is placed upon step d of a selector bar and the manual control pinion 56 disengaged from the train I6I. This allows the condenser to rotate freely to the right and turn off the set.

The inverse order of procedure in setting the stops as disclosed above is necessary with this modification since, if all the stops were rotated as a group, adjustment of the volume for the first station would position all of the stop members in a radial direction and the cam surfaces I 65 would not be low enough to cut down the volume of a subsequent station of higher power than the station being positioned.

To set up a preselected sequence of stations to begin at a future time, one selector bar I3I for each 15 minute period of elapsed time, save one, is set up in a clockwise direction with step d in position to cooperate with the tip of the selector arm I 2|. The bar representing the last period of elapsed time is set with any other step in position. The desired sequence of stations then set up consecutively in a clockwise direction, bars I 3| presenting steps a, b, or c in accordance with the station desired. To terminate the sequence, all subsequent bars are adjusted to present step d.

Rider 31, making one revolution each 15 minutes, engages the lever I42 once each revolution and causes the pawl I43 to force the selector arm I2I forward and step it one step (to the next bar I3I). If the arm I2I rests upon step d of this bar, bellcrank I5I holds detent 38 out of the path of rider 31 and the rider 31 follows the gear 34 at a uniform rotational speed. If the arm rests on step a, b, or c, detent 38 is dropped into the path of the rider 31 and restrains it, causing the rotation of gear 34 to store energy in the spring 36. As in the former modification, when gear 36 has rotated almost a complete revolution, rider 31 is released from the detent 38, engages the stop 41 of the gear 46 and, acting through gear I10 and pinion I69, rotates the condenser to its extreme counterclockwise position. Just prior to the point at which rider 31 releases the condenser, it actuates the lever I42, stepping the selector arm to the next selector bar. After release from rider 31, the condenser rotates slowly in a clockwise direction under the control of the governor I1I until the stop I25 corresponding to the selected step of bar I3I is intercepted by the stop I62. This causes the condenser to tune in the desired station, and the positioning of the shield I13 by the cooperation of cam surface I65 and the follower I66 causes the station to be received with the desired volume.

The selector arm I2I now being upon say step a, the detent 38 will be lowered into the path of the rider 31 and when the rider reaches this point it will be restrained and the spring again tensioned as before. The above operations continue until the selector arm reaches the array of bars I3I which are set at step d, at which time the condenser when released from the rider 31 will rotate to the extreme clockwise position and cut off the set. The detent will be lifted from the path of the rider 31 and the latter will rotate with the gear 34. It will be noted that during the idle period, i. e., when the set is adjusted for manual operation or when the selector arm is upon step d, the motor 33 is not tensioning the spring 36 and is merely idling at synchronous speed, thereby having a minimum of current consumption during this period.

Whenever the gear I06 is rotated through the medium of pinion I69, or whenever it drives the governor I1I therethrough, the reaction upon the stub shaft of the pinion I69 will force the lever I16 in a counterclockwise direction. This will force the shield I13 upward, silencing the set, and will force the cam follower I66 downward, keeping it clear of the cams I65. When manually rotated through the train I6I, this does not necessarily occur, as the speed of manual rotation may not be sufficient to actuate the governor I1I. The cam surfaces I65 have sufficient pitch to cause the follower I66 to ride thereover even when they are in the lowest position, so that when the condenser is manually rotated the lever will oscillate without hanging and moving the stops out of adjustment.

The purpose of the volume control features above disclosed in conjunction with the automatic tuning arrangement is not to supplant but to supplement the conventional manual volume control by causing the input to the set to assume a substantially constant level. The desired level of reception can be adjusted to suit the occasion manually and will be substantially the same for all stations upon the selected list. The cooperation between the automatic and the manual volume control means is best shown by means of a simple circuit diagram such as that shown in Figure XV. The shielding cylinder I13 is interposed between the primary I60 and the secondary I59 of the antenna coupler, as above disclosed in connection with Figure IX, to control the input to the set. The output from the conventional radio frequency amplifier is rectified by a conventional diode rectifier and the rectified currents pass through the manual volume control potentiometer I15, which controls the input signal voltage of the first stage of audio frequency amplification. The circuit also shows the connection of the power supply switch 60 and the manner in which it cuts off the set when engaged by pin I0 which is attached to the gear 6 or I06.

Also it may be desirable to include conventional automatic volume control to compensate for va riations in the signal intensity of the same station at various times and also to compensate for slight discrepancies in the operating action of the automatic input signal adjusting means herein disclosed. Especially would this be desirable in conjunction with the first modification, since with the high gear ratio necessary to effect adjustment for each station, a slight inaccuracy or play in the gears might change the signal level to some extent.

Various modifications of each of the devices may obviously be made by those skilled in the art. For example, the specific number of stops 25 or I25, the number of selector buttons 3| or selector bars I3I, or the number of teeth in the ratchet wheel 49 may be modified to suit desired conditions of operation. When a different number of stops is used, it is obvious that the number of sectors a, b, c, d on the buttons 3i or steps a, b, c, d on bars I3I must be equal to the number of stops plus one. Either modification may be designed to employ either buttons ill or bars I3I as their functions are identical, the tip of the selector arm being designed to cooperate therewith.

()ther governing means may be provided for the rider in lieu of the self-governing spring 36. For example a gear of greater radius than the rider which meshes with a pinion connected to a conventional governing mechanism such as I1I may be substituted for the leg 231 of the rider 31. A stop would be provided upon its rear side to cooperate with the stop 41 when the rider is shifted axially as above described. The pinion should be long enough so that the gear will mesh therewith regardless of the axial position of the rider.

The foregoing are a few modifications which will occur to those skilled in the art and other similar modifications may obviously be made without departing from the scope of my invention which I do not intend to be limited by the specific structures disclosed but only by the scope of the appended claims.

I claim:

1. In a radio receiving set, the combination of a tuning device, a spring for rotating the tuning device, means. for restraining the tuning device at any one of a plurality of positions corresponding to the frequencies of desired stations, a plurality of adjustable selector elements and means cooperating therewith in sequence for controlling the restraining means and determining the sequence in which the stations are selected, a synchronous motor for tensioning the spring, means responsive to the rotation of the motor for de-- laying the initiation of the sequence a predetermined time interval, means responsive to the initiation of the sequence for energizing the radio set, means also responsive to the rotation of the motor for determining the time interval between the selections of succeeding stations of the sequence, and means responsive to the termination of the sequence for deenergizing the radio set.

2. The combination of a variable condenser having a rotary shaft, a stop carried by the shaft, a stationary panel through which the shaft projects, a substantially circular array of adjustable selector elements carried by the panel, a selector arm rotatable about the shaft and adapted to engage the selector elements, means for rotating the condenser shaft at predetermined intervals and for concurrently rotating the selector arm to the succeeding selector element, and a second stop mechanically controlled by the selector arm and positionable thereby in response to a particular adjustment of the selector element for engaging the first stop and restraining the condenser shaft.

3. The combination of a variable condenser having a rotary shaft, arresting means carried by the shaft, a stationary panel through which the shaft projects, a substantially circular array of adjustable selector elements carried by the panel, a selector arm rotatable about the shaft and adapted to engage the selector elements, means for rotating the condenser shaft at predetermined intervals and for concurrently rotating the selector arm to the succeeding selector element, and a second arresting means mechanically connected to the selector arm and movable thereby to various positions in a direction parallel to the condenser shaft in accordance with the adjustment of the selector element for engaging the first arresting means and restraining the condenser shaft.

4. The combination as in claim 3, in which the first arresting means comprises a plurality of individually adjustable stops having various paths of travel, whereby they may selectively cooperate with the second arresting means and restrain the condenser in any one of a plurality of positions in accordance with the adjustment of the engaged selector element.

5. The combination as in claim 3, in which the second arresting means comprises a plurality of individually adjustable stops which intercept various parts of the path of travel of the first arresting means, whereby they may cooperate therewith selectively an-d restrain the condenser at any one of a plurality of positions in accordance with the adjustment of the engaged selector element.

6. An automatic tuning device for radio receivers comprising a tuning condenser having a shaft, a panel through which the shaft projects, a circular array of adjustable selector elements upon the panel substantially concentric with the shaft, a selector arm rotatable about the shaft for selectively engaging the elements, means responsive to oppositely directed axial movements of the arm for locking the arm against rotation during engagement with an element and for unlocking the arm to permit rotation, and means for periodically disengaging the arm from the engaged element and causing it to engage a succeeding element.

'7. The combination as in claim 6, in which the selector arm has a pointed tip and in which each of the selector elements consists of a button having a plurality of discrete sectors of varying thickness and is manually rotatable to present any one of the sectors to the tip of the selector arm.

8. The combination as in claim 6, in which each of the selector elements consists of a radially adjustable bar having a plurality of steps of varying thicknesses, and in which the locking means consists of a pair of cam surfaces upon the tip of the selector arm and in cooperative relation to the bars.

9. A stop assembly for an automatic station selector comprising a bushing having a longitudinally grooved body portion, a raised shoulder at one end of the body, a plurality of rotatably adjustable stop members and interposed washers disposed upon the body, the washers having tits to engage the grooves in the body and prevent rotation of the washers, means disposed upon the other end of the body to clamp the members and washers against the shoulder, a shaft passing through the bushing and rotatable therein coaxiall'y with the stop' members, and a stop fixed to the shaft and adapted to cooperate with the first stop members.

10. A stop assembly for an automatic station selector comprising a bushing having a longitudinally grooved body portion, a raised shoulder at one end of the body, a plurality of stop members and interposed washers disposed upon the body, the stop members having oval eyes therein to permit of radial and rotary adjustment of the members about the body and the washers having tits to engage the grooves in the body and prevent rotation of the washers, and means disposed upon the other end of the body to clamp the members and washers against the shoulder.

11. In a radio receiving set, the combination of a tuning device, a stop assembly for the device comprising a plurality of mechanically adjustable steps, a series of mechanically adjustable selector elements, means for engaging the elements in sequence and for selecting one of the stops mechanically in accordance with the adjustment of the engaged element, means for rotating the tuning device at predetermined intervals, and means responsive to the adjustment of the selected stop for controlling the tuning of the device and the level of reception of the tuned signals.

12. In a radio receiving set, the combination of a tuning device, a stop assembly for the tuning device comprising a plurality of radially and rotatably adjustable stops, a series of adjustable selector elements, means for engaging the elements in sequence and for selecting one of the stops in accordance with the adjustment of the engaged element, means for rotating the tuning device at predetermined intervals, means responsive to the rotary adjustment of the selected stop for controlling the tuning of the device, and means responsive to the radial adjustment of the selected stop for controlling the level of reception of the tuned signals.

13. In a radio receiving set, the combination of a tuning device, a stop assembly for the device comprising a plurality of mechanically adjustable stops, a series of mechanically adjustable selector elements, means for engaging the elements in sequence and for selecting one of the stops mechanically in accordance with the adjustment of the engaged element, means for rotating the device at predetermined intervals, means for preventing the production of signals during rotation of the device, and means responsive to the adjustment of the selected stop for controlling the tuning of the device and the level of the received signals.

14. In a radio receiving set having a rotatable tuning device, means for silencing the set during the rotation of the device comprising a gear carried by the device, a pinion meshing with the gear, a pivoted lever upon which the pinion is mounted for rotation, and a silencing device actuated by oscillation of the lever in response to the reaction of the pinion upon the lever.

15. In a radio receiving set, the combination of a high frequency transformer having a primary and a secondary winding, a rotatable tuning device, a plurality of cams carried by the tuning device, a cam follower adapted to cooperate with the cams, an electrically conducting shield movable to various positions between the windings and means controlled by the cam follower for varying the position of the shield between the windings in accordance with the ad- Justments of the cams.

16. In a radio receiving set having signal responsive circuits and a rotatable tuning device, means for silencing the set during rotation of the device and for controlling the level of the tuned signals comprising a rotatable shaft, a radially displaceable member attached at one end to the shaft, a metallic cylinder and an annular resistor concentric with the shaft and having the other end of the contact member therebetween whereby the member contacts the cylinder when in rotation and the resistor when at rest, electrical connections from the cylinder, resistor, and contact member to the signal responsive circuits, and means for rotating the shaft from the tuning device.

17. Means for effecting intermittent rotary oscillation of a radio tuning device comprising a rotatable driven member connected to the device, a rotatable intermediate member, and a continuously rotatable driving member, a spring connected between the intermediate member and the driving member, means for restraining the intermediate member and causing the spring to be tensioned by the rotation of the driving member, means responsive to the rotation of the driving member for moving the intermediate member in an axial direction, releasing it from the restraining means and causing it to engage the driven member, whereby both may be rotated by the spring, means responsive to the rotation of the intermediate member for causing it to release the driven member, and means for rotating the driven member in the reverse direction upon release by the intermediate member.

18. Means for producing intermittent rotation of a radio tuner comprising a synchronous mo tor, a gear driven by the motor, a rider and a driven member in substantially coaxial alignment with the gear, a detent for the rider, 2. spring connected between the gear and rider and adapted to be tensioned by the gear when the rider is restrained by the detent, means responsive to the rotation of the gear for causing the rider to escape the detent and to engage the driven member, thereby rotating the latter under the influence of the spring, means responsive to the rotation of the rider for causing it to disengage the driven member, a cam follower for controlling the detent, a cam cooperating with the follower, a pawl and ratchet wheel for rotating the cam, means for causing the rider to actuate the pawl, and means for causing the follower to follow the gear when the detent is disabled by the cooperation of the cam and follower.

EDWARD W. ALLEN, J R.

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