US2093494A - Selective tuning mechanism for radio receivers - Google Patents

Description

J. M W. STONE SELECTIVE TUNING MECHANISM FOR RADIO RECEIVERS Sept. 21, 1937.

Filed Aug. 30, 1934 6 Sheets-Sheet W/M'ua ITIHP-HHH ATTORN E Y5 Sept. 21, 1937. J STONE 4 2,093,494

SELECTIVE TUNING MECHANISM FOR RADIO RECEIVERS Filed Aug. 30, 1934 6 SheetsSheet 2 to u N 3 u Fly 3 INVENTOR. fafin/Vz/W/mms 5 #0 0e ATTORNEYS Sept. 21, 1937. J. Mew, STQNE 2,093,494

SELECTIVE TUNING MECHANISM FOR RADIO RECEIVERS Filed Aug. 50, 1934 6 Sheets$heet 3 INVENTOR.

ATTORNEYS s'e i. 21, 1937. STONE 2,093,494

SELECTIVE TUNING MECHANISM FOR RADIO RECEIVERS Filed Aug. 30, 1934 6 Sheets-Sheet 4 INVENTOR.

A TTORN E Y5 Sept. 21, 1937. E J, Mew, STONE 2,093,494

SELECTIVE TUNING MECHANISM FOR RADIO RECEIVERS Filed Aug. 30, 1934 s Sheets-Sheet 5 3 Q T k a \P Q o Q 8 W ATTORNEYS Sept. 21, 1937. J, MOW- STONE 2,093,494

SELECTIVE TUNING MECHANISM FOR RADIO RECEIVERS Filed Aug. 50, 1934 6 Sheets-Sheet 6 INVENTOR.

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ATTORNEYS Patented Sept. 21, 1937 PATENT OFFICE SELECTIVE TUNING MECHANISM FOR RADIO RECEIVERS John McWilliams Stone, Geneva, Ill., assignor to Operadio Manufacturing 00., St. Charles, 111., a corporation of Illinois Application August 30, 1934, Serial No. 742,097

4 Claims.

My invention relates to selective tuning mechanism for radio receivers.

It is the principal purpose of my invention to provide a system for pre-selecting a number of programs occurring at different hours or periods of time during the day so that the user of the radio set may pick out the broadcast he desires to receive, make his selections on the pre-selector and thereafter have his receiving set automatgeally tuned in on the various programs as they My invention contemplates also certain improvements on the drive unit by means of which the tuning shaft of the receiving set is operated which improvements insure accurate tuning while at the same time they permit resetting or manual tuning without the necessity of making any complicated changes.

It is also an important object of this invention to provide a reversible driving motor in combination with a tuning or setting device requiring accurate stopping without overrunnlng with means to set up electrically a powerful braking effect in the motor when it is desired to stop the tuning device.

My invention contemplates also the provision of a novel pre-selecting attachment for a clock or timing device.

My invention further contemplates certain improvements in the starting mechanism for the clock or timing device which improvements enable one to accurately set the clock in response to a time signal.

Other and more specific changes and advantages of the invention will appear as the description proceeds in connection with the accompanying drawings wherein the preferred form of the invention is shown.

In the drawings:-

Fig. 1 is a diagrammatic view showing the wiring diagram for connecting up the pre-selecting device;

Fig. 2 is a vertical section through the drive unit;

Fig. 3 is a view taken on the line 3-3 of Fig. 2;

Fig. 4 is a rear view of the device shown of the drive unit with the cover removed;

Fig. 5 is a front view of the drive unit;

Fig. 6 is an expanded showing of the several elements which are combined with the drive unit for selecting the desired stations to be tuned in by the pre-selector;

Fig. 7 is a vertical section through the clock, with the impulse and timing mechanisms shown 'in full;

Fig. 8 is a rear view with the cover broken away from the mechanism shown in Fig. 7;

Fig. 9 is a front view of the mechanism shown in F18. 7

Fig. 10 is a fragmentary section taken substantially on the line ill-l0 of Fig. '7; and

Fig. 11 is a diagrammatic view of the motor parts.

Referring now in detail to the drawings, the pre-selecting system consists of a motor A of a special type which will be more thoroughly ex plained hereinafter, a drive unit B actuated from said motor. a switching unit C actuated from said motor, a clock D, and the pre-s'electing mechanism E.

The drive unit will be first described as it is essential to understand the type of driving motion that is imparted to the set.

Referring now to Fig. 2, I have shown a coupling at H which is adapted to be attached directly to the tuning condenser shaft and is driven by the drive unit B. the drive shaft i2 of which projects through the cover it. The motor A and the switching unit C are also mounted beneath the cover It and supported from a base I and standard I! by means of suitable brackets and screws, the switching mechanism being supported on the bracket i6 and the motor being supported upon the bracket or plate ii.

The standard I! also has connected thereon the bracket i8 which is insulated from i5 by means of the insulation i8 and which carries the contact pin 20 adjustably up and down by means of the adjusting screw 2i and pressed down by I means of the spring 22. The depending arm 23 is apertured as indicated at 24 to receive an aligning pin for a purpose which will presently appear.

The motor A by means of its shaft 25 drives a train of gears consisting of the pinion 28 on the shaft 25, gear 21, pinion 28 on the gear 21, gear 29 meshing .with the pinion 28. pinion 30 which is rigid with the gear 29, meshes with gear 3i, and gear 32 meshing with gear 2|.

Gear 32 is mounted on the hollow shaft I3 which is journalled in bearing 34 in the standard IS. The hollow shaft 33 carries disk 35 which carries the several adjusting plates and insulating plates shown as separated out in Fig. 6. The r gear 32 is also directly connected to the shaft I2. The switching mechanism C as shown clearly in Fig. 3 is offset laterally with respect to gear 32, and shaft i2 carries the switch operating bar 36 (see particularly Figs. 3 and 4) which bar is adapted to engage a pin 31 on shaft 38 which is 'laflng r ng 56 encircling the portion 55.

pivoted in the switch frame. Rocking of the bar 31 actuates the control fingers 39, 49 and 4i which operate switches 42, 43 and 44 respectively.

Switch 43 is called the off switch. Switch 42 is the impulse switch and switch 44 is the reversing and drive switch. These switches are operated in definite time relation by means of the fingers 39, 40 and 4! so that when the shaft i2 is rotating to move toward off position, the off switch 43 is opened slightly before the impulse switch 42 and the reversing switch 44 is opened last. This result is accomplished by the positioning of the fingers 39, 49 and 4i with respect to the corresponding cams on the switches which are indicated at 46 and 41 on switch 42 in Fig. 3. By referring to Fig. 1, it will be noted that the opening of the off switch 43 first disconnects the power from the line 4 which leads to the radio set.

The motor A is a reversible motor and is reversed by the opening and closing of the reversing switch 44. This reversing switch is also operated on the return stroke when the shaft i2 has rotated 180 in the opposite direction when the other end of the arm 36 will strike the pin 31 and swing the operating shaft 38 in the opposite direction. Thus the normal operation, if no control were exerted to stop the motor A, would be to rock the shaft I2 through a full arc of 180, the switching mechanism C serving to reverse the motor.

The impulse switch 42 is connected by means of the conductor 48 to the contact pin 20 which causes the contact pin circuit to be opened when this switch is opened. The driving unit is also provided with a manually operable circuit making andbreaklng device 49, the purpose of which will appear presently in the description of the operation in the circuit.

Another manually operable push button type circuit closer is indicated at 59. These two manually operable controls 49 and 59 operate to control contacts ill, 52 and 53 which as shown are secured to the plate H as shown most clearly in Figs. 2 and 4.

Referring now to Figs. 1. and 6, it will be noted in Fig. 5 that there are six projections numbered from 9 to 5 and these six projections are each adapted to contact the pin 29 when moved under it by the rotation of the shaft [2. These several projections are mounted upon corr s onding plates 69. 6|, 62, 63. 64 and 65 which plates are aoertured to fit over the projecting sleeve 55 of the disk 35 having a suitable insu- The plates 69 to 65 are in contact on one side with the contact plates 10. ll, 12, i3. 14 and 15 and on the other side of the plates 69 to 65. are the insulat ng plates 89, 6|, 82, 83. 94 and 65.

It will be noted that the plates such as 60 to 65 directly opposite the projections are cut away or reduced in width as indicated. for examp e, in 66, 67 and 69 in Fig. 6 so that they terminate short of the openings such as 16 and 96 in the plates "and 99 respectively. These openings are to receive the insulating sleeve 51 and the mounting screw 59 which fixes plates 19 to 76 and 99 to 85 on the sleeve 55 so that they cannot rotate.

An extra insulating plate 81 is interposed between disk 35 and plate 70 and a heavy clamping plate 11 constitutes the outer plate member against which the securing collar 59 presses. A cap 99 of insulating material closes the end of the sleeve 55. The plates 19 to 15 are each provided with tongues such as indicated at .8 hich project through the slot provided at 69 in the member 55 and in the ring 56, these tongues being used for wiring terminals as shown most clearly in Fig. 1.

From the above described construction of the disk 35 and the plates mounted thereon. it wlll be evident that plates 69 to 65 are frictionally held against rotation on the sleeve 55 by the plates on opposite sides thereof but that these plates 60 to 65 may be turned on the sleeve 55 by. hand to change their relative position.

In adjusting the driving unit for tuning the receiver to the wave length of a desired station, I first loosen the collar 59. Then, by placing the opening in the projection on one of the plates 66 to 65 in direct alignment with the opening 24 by inserting a suitable pin, I can then turn the disk 35 until the desired station for that particular projection is tuned in. The pin then can be withdrawn and another projection on a different one of the plates 69 to 65 lined up with the opening 24 and secured by the pin so that upon repeating the tuning performance to a different station this second projection will be properly positioned for tuning that station. In this fashion each of the projections, I to 5, can be properly set so that when they strike the pin 20, the station for which they are set will be tuned in by the receiving set.

The oif projection marked 9 needs no adjustment and is always left in fixed position. The frictional engagement between the plates is sufficient to prevent any shifting during the adjustment or setting and after that of course, the tightening up of the collar 59 and the removal of the pin from the opening 24 leaves the plates finally set in proper position for the desired tuning effects.

Referring now to Figs. 7 to 10, I show a clock mechanism and the pre-selecting mechanism by which the clock causes the driving unit to move the proper projection on the plates 69 to 65 into contact with the pin 29 at the proper time.

Referring first to Fig. 9, it will be noted that the face of the clock outside of the dial has fortyeight openings or slots such as 99 which slots correspond to the quarter hour indications on the dial. Projecting through the slots 99 or accessible thereto are the polygonal ends of the setting shafts. These ends I have referred to by the numeral 9! and the shafts shown more clearly in Fig. '7 are referred to by the numeral 92. It is understood of course, that there are fortyeight of the shafts 92. These shafts are journalled at their opposite ends in the face plate 93 and back flange 95 of the rim 94 of the clock casing. Each shaft 92 has located thereon a number of projections such as 96 which projec tions equal in number the projections on the plates 60 to 65, that is, in the present instance there are six of the projections 96 on each shaft. They are spaced longitudinally of the shaft and they are angularly disposed about the shaft so that they are separated by substantially equal angles.

A commutator arm 91 is fixed upon the disk 98 which rotates with the hour hand of the clock and this commutator arm carries six contact elements which I have generally indicated by the numeral I99 there being one contact element aligned with each projection on the shaft 92. These contact elements I00 are connected by the conductors i0| to the corresponding commutator rings I02 which are secured in the insulating disk 99. A stationary contact plate I03 of insulating material is mounted in front of the rotating disk 98 and carries a series of six independent brushes such as I04 and I05 for engaging with the commutator rings I02 and each of these brushes has a terminal such as I08 connected to a suitable conductor I01 which is carried out to the back of the clock case.

It is evident from the above description that if a contact be made between one of the projections 96 on a shaft and a corresponding contact element I00 then a circuit will be completed from the shaft 92 through the projection and contact element to the commutator ring on disk 90 corresponding to that element and the associated brush I04 to one of the conductors I01 so long as the contact element and projection remain in engagement. The contact elements are preferably made long enough so that there is an appreciable time of contact before the projection and contact element are moved out of engagement.

The conductors I01 are brought out to the back of the clock mechanism and connected to the terminal plate I03 where the leads to the control and drive unit B are connected therewith. By reference to Fig. 1, it will be noted that there are six of these leads which I have numbered I I0, III, H2, H3, H4 and H5. The terminal plate I08 may also have other leads connected therewith such, for example, as the leads to the clock mechanism.

The cover I08 fits against the flange 85 and is held in position by suitable screws such as lit to cover the mechanism on the back of the clock case. On the back of the clock case, there is a disk II1 which moves with the minute hand of the clock so as to make one revolution per hour and this disk is notched in four places by suitable notches II8 and spring pawl IIS mounted on the supporting arm I20 and cooperates with the notches II8 to periodically close contact between the springs I2I and I22 and break contact between the springs I23 and I24. The springs I2I and I22 are in series with the contacts 5I so that if either of these groups of contacts are opened, their circuit is broken.

The supporting arm I20 may be adjusted about the axis of the disk vII1 by means of the screw plate I25 when the clamping screw I28 is loosened to permit sliding of the screw in this slot I21. A suitable spring such as I28 is interposed between the arm I20 and the shoulder I28 on the mounting plate.

The center shaft for setting the hands of the clock has the projecting knob I32, and, at I33, I show the starting knob which is utilized to spin the clock mechanism to bring it up to synchronous speed for starting, this of course being a standard piece of equipment for clocks of this type.

I also provide a switch I 34 which is secured to bracket I35 and also to the cover I08. This switch has an operating lever I88 on the outside of the cover for manual operation. Switch I34 is normally closed to close the circuit over conductors I31 and I38 through the energizing coil 139 of the clock, conductors I31 and I38 being permanently connected across a source of alternating current. The switch is utilized in starting the clock and accurately setting it in the following fashion: The hands are set by means of the setting knob I32 to a few minutes ahead of the correct time with the switch I34 in off position and the contact springs I23 and I24 will, when the pawl I I 9 is riding on the surface of the disk II1, maintain the circuit of the clock closed until II8 drops into a notch marking an exact fifteen minute point on the clock dial. Now, when the clock stops at this point, the attendant closes the switch I 34 and waits if he is obtaining the time signal from the radio set until he hears the signal indicating the end of the quarter hour period. Then the attendant turns the starting mechanism by turning the knob I33, thus starting the clock quite accurately in step with the time as given by the radio signal. Of course, the clock may be set from a master clock in the same fashion by starting it when the master clock reaches a quarter hour point.

The motor unit A is a special type of drive motor having a main energizing coil I40 which is connected across the 110 volt A C. line by means of conductors I H and I42 through the radio set control switch I43. In the wiring diagram shown in Fig. 1, the coils I45 and I48 in series, constitute .one pair of shading coils, and the coils I41 and I48 form the other pair of shading coils.

The operation of the motor may be briemr explained as follows: As the magnetic flux builds up in value, due to current in the main winding of the motor, there will be a current produced in any closed electrical circuit which encircles any part of this flux, and the direction of this current will be such that it tends to produce a magnetic field in the opposite direction through the closed electrical circuit. Furthermore, when the magnetic flux through the closed electrical circult decreases in value, there will be a current produced in the electrical circuit, and the direction of this current will be such that it tends to produce a magnetic flux through the closed electrical circuit in the same direction as that produced by the current in the main winding.

The application of the above statements to the operation of the small shaded pole motor may be explained by reference to Fig. 11. When all or the windings I45, I46, I41, and I48 are open, there will be no current produced in them and the main field flux will not be influenced by their presence. If, however, windings I45 and I48 are shorted independently or in series, the following action will take place. As the main magnetic flux increases in value from zero to a maximum with the upper main pole of north magnetic polarity, ward the right side of the pole face due to the action of the winding I45, and hence the point of maximum north pole strength will not be in the center of the pole face, but to the right. As the main magnetic flux decreases in value from maximum to zero with the upper main pole of north polarity, the magnetic flux will be crowded toward the left side of the pole face due to the action of the winding I45 and hence the point of maximum north pole strength will not be in the center of the pole face but to the left. The

the magnetic flux will be crowded tonorth pole, as a result of the above action, travels from right to left across the upper pole face or in a counter-clockwise direction. An identical action is taking place over the face of the lower pole face, and a south pole is travelling in a counterclockwise direction. At the end of the first half cycle of main flux change, the polarity of the main pole face is reversed, and a south pole travels counter-clockwise across the upper pole face, and a north pole counterclockwise across the lower pole face. The magnetic field in effect is rotating counter-clockwise around the rotor, and there will be an electromotive force induced in the rotor bars,

and a current willcirculate in these bars as they are part of a closed circuit. This current reacts upon the magnetic field, and a torque is produced in a counterclockwise direction causing the rotor to rotate. The speed of the rotor will never be equal to that of the rotation of the magnetic field. Now, it the rotor is rotating counter-clockwise due to the action of the shorted windings I45 and I45, and windings I41 and I48 be shorted, the following action will take place. Two magnetic poles of like sign will move from the center of a pole face toward the two sides. The two poles moving in opposite directions will produce opposite eiiects upon the rotor and of unequal magnitude. The poles moving in the direction of the rotor will produce a torque in the direction in which the rotor is rotating. The poles rotating torques will be equal.

I will now trace a complete operation of the device on the diagram shown in Fig. 1 to show how the automatic tuning is accomplished. We will assume that the switch I43 is closed, thus connecting up the motor A for operation. Assume that the clock is also operating and switch I34 therefore is in normal closed position, and we will take the instant when the pawl IIS drops into a notch in the disk II1 as shown in Fig. 1. We will assume also that the third projection 96 on one of the setting shafts 92 has just engaged its corresponding contact element I which it should do when the pawl II9 drops into a notch in the disk III. In this position, the lead II2,

which is connected in the drive unit 13 to the projection numbered 2 on disk 62 by means of disk 12 and its corresponding tongue, is connected through its brush I to the corresponding ring I02 on the rotating disk 98 and by means of the conductor IOI, contact element I00, projction 06, through 92 and the frame oi the clock to the ground lead I50. Ground lead I50 is connected to one terminal or the reversing switch 44 as indicated at I5I. It is also connected to one terminal of coil I41 by means of conductor I52.

When pawl II 9 drops into the notch in disk I I1, it closes contact between the springs I2I and I22 to thus close the circuit over conductors I53 and I54 from the center tap of the reversing switch 44 to the common terminal of coils I45 and I48 through the closed contacts 5I which are not opened unless the member 49 is manually be in position to connect contacts 44 and I5I so tacts I2I and I22, over conductor I53, through reversing switch contacts 44 and I55, to the outside terminal of coil I48.

This reverses the motor to cause it to operate the drive unit B in a clockwise direction and as the projections pass the contact pin 20, nothing will happen until the projection 2 strikes the contact pin. When this occurs, a circuit is completed from one terminal of impulse switch 42, through pin 20, and projection 2 over conductor II2, through brush I05, ring I 02, conductor IOI, contact element I00, and pin 96 to the casing of the clock and then to ground line I50, to terminal I52 and coil I41, through coils I41 and I48, to

the common terminal of coils I45 and I48, thence through contacts 5| and over conductors I54 and I53, and through reversing switch 44, conductor I56, back to switch 42 which is now closed. Thus, both sets of coils have their circuits closed so that they work against each other which forms a braking effect to stop the motor at this point.

The next step in the operation of the device is the opening of contacts I2I and I22 by the rotation or the disk I I1 which causes pawl II9 to ride up out of the notch II8. This breaks, at contacts I2I and I22, the circuits for both sets of coils which circuits are held over the line running from the common terminal of coils I45 and I48, through contacts 5|, the conductor I54, contacts I2I and I22, and conductor I53, to the center terminal of switch 44. The motor will, therefore, remain stopped with the tuning apparatus set for the station corresponding to the projection 2 until such time as circuit again is completed at the contacts I2I and I22 which will be at a time when the new one of the pre-selection shafts 92 is in position to engage by means of its projections 96 with one of the contact elements I00. 7

If the same contact element I00 is engaged by the same relative projection on the new shaft, the'same connections will be established so that projection 2 will remain on contact pin 20 to hold the same station tuned in. If, however, the new shaft has a projection engaging a diflerent one of the contact elements I00, then the motor will stop the driving unit in position so that the corresponding projection engages the contact pin 20.

It is evident that, ii the operator wishes to continue to listen to the station beyond the time when the apparatus would tune a new station in, he may do so by operating the control member 49 to manually break the circuit by separating contacts 5I. This would prevent circuit being completed to either of the coils I45 or I48 by the closing of contacts I2I and I33 so that the motor could not be energized.

The push button 50 may also be operated to complete the energizing circuit for the motor when it is stopped and contacts I2I and I22 are opened since, by pushing it in and closing its contacts 52 and 53, a shunt is established around conductors I53 and I54, and, since the contact element I00 moves off the pin 96 very shortly after the tuning is accomplished, circuit cannot be completed through the impulse switch 42 and the particular conductor which is at the moment connecting the contact element I00 with the contact pin 20, circuit will be completed for coils I45 and I46 only, and this will result in moving the driving unit B toward off position where the oil switch will be opened and, if the push button 50 is not held. on, the motor will come to rest in the ofi position because the reversing circuit connecting in coils H1 and I will be broken at contacts 52 and 53.

While the invention has been described in connection with a timing mechanism for pre-selection, certain features of the invention are not limited to a pre-selectlon by means of a timing device. The selections may be made by manually operated circuit control devices instead of by the clock.

From the above description, it is believed that the construction and operation of this device will be clear to those skilled in this art and the advantages readily apparent.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A pre-selecting system for radio receiving apparatus comprising a drive unit for tuning the radio receiving apparatus, a motor for driving said unit, a clock having means to energize the motor periodically at definite periods, and means on the clock cooperating with said drive unit and motor determining the position to which the drive unit moves the tuning device for each energization oi the motor, said last named means comprising manually adjustable selectors arranged around the clock dial to correspond to the quarter hour positions thereon, said selectors comprising individually rotatable shafts having contact making pins thereon, a rotatable member driven by said clock and having a contact member for each pin on the shaft, electrical con nections from said contact members to said drive unit, said drive unit having adjustable contact members thereon to which said electrical connections lead, and a stationary contact member controlling said motor and adapted to engage the contact members on the drive unit.

2. A pre-selecting system for radio receiving apparatus comprising a drive unit for tuning the radio receiving apparatus, a motor for driving said unit, a clock having means to energize the motor periodically at definite periods, and means on the clock cooperating with said drive unit 5 and motor for determining the position to which the drive unit moves the tuning device for each energization of the motor, said motor having windings electrically connected with said last named means for braking the motor to stop the drive unit, the electrical connection to said motor windings including a series of contacts adapted to be rocked by said drive unit, a stationary contact for engaging said last named contacts, and a switching device operated by said drive unit for completing circuit from said stationary contact to the windings oi the motor.

3. A pre-selecting system for radio receiving apparatus comprising a drive unit for tuning the radio receiving apparatus, a motor for driving said unit, a clock having means to energize the motor periodically at definite periods, and means on the clock cooperating with said drive unit and motor for determining the position to which the drive unit moves the tuning device for each energization of the motor, said last named means including manually operable selectors spaced around the clock dial, said selectors comprising shafts rotatably mounted in the clock frame and grounded thereon, each shaft having a series of contact members spaced circumferentially and longitudinally with respect to each other on the sh 4. A selective tuning system for radio receiving apparatus comprising a drive unit for tuning the radio receiving apparatus, a motor for driving said unit, a selecting device to energize the motor, said selecting device having means cooperating with said drive unit and motor for determining the position to which the drive unit moves the tuning device for each energization of the motor, said motor having windings electrically connected with said last named means for braking the motor to stop the drive unit, the electrical connection to said motor windings including a series 0! contacts, a control contact for engaging said last named contacts, said drive unit including means for causing relative movement between said control contact and said series of contacts, and a switching device operated by said drive unit for completing circuit from said control contact to the windings oi the motor.

JOHN McWILLIAMs STONE.

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