US2472536A - Tuning indicator system - Google Patents

Description

June 7, 1949. Q c, ElL, JR" ETAL 2,472,536

TUNING INDICATOR SYSTEM Fild Nov. 25, 1947 .smnon .seLecroR \45 clRcu/rs Patented June 7, 1949 TUNING INDICATOR SYSTEM Otto C. Keil, Jr., Quakertown, and Jesse Hewitt Lofto'n, Havertown, Pa., assig'nors to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application November 25, 1947, Serial No. 788,052

The invention herein described and claimed relates to an improved .annunciator system adapted for use in selective multi-circuit communication and signaling apparatus. More particularly, the invention relates to an improved visual-indicator system employing individual indicating means, preferably lamps, for identifying the circuit or station selected.

The present invention may be eniployed .to excellent advantage in pushbutton-operated radio receivers, particularly radio receivers which use a non-latching type of pushbutton mechanism, either for station or wave-band selection. Non-latching pushbutton mechanisms have been found to be particularly useful in automobile radio receivers where it is desired to provide tuning means controlled both by hand-operated pushbutton station-selector mechanism and by a foot-operated station-selector switch.

It will be understood that in a non-latching type of selector mechanism, a pushbutton, when depressed, returns to released position as soon as the pressure of the operators finger is removed; and thereafter, all pushbuttons occupy similar released positions. It is hence impossible to ascertain, from merely looking at the pushbuttons, the station to which the receiver is tuned, and it is necessary to provide some means of identifying the station. That is the function of the annunciation or visual-indicator system whose improved circuit arrangement is the subject matter of the present invention.

The invention may be used to excellent advantage in radio receivers employing the non-latching type of pushbutton mechanism described and claimed in the copending application of Gilbert J, Kennedy, Serial No. 754,013, filed June 11, 1947, and assigned to the assignee of the present invention.

It is an object then of this'invention to provide an improved annunciator or visual-indicator system for selective multi-circuit communication and signaling apparatus.

It is another object of this invention to provide an improved indicating lamp system for use in pushbutton-operated radio receivers.

It is a more specific object of this invention to provide, in a radio receiver having a non-latching type of pushbutton selector mechanism, improved means for identifying, by the lighting of an individual indicator lamp, the station and/or wave band to which the receiver is tuned.

In a preferred embodiment of the presentinvention employed in a radio receiver having nonlatching pushbutton station selectors, when a 4 Claims. (Cl. 177-353) selected pushbutton is depressed by the operator, all indicator lamps are immediately extinguished and all remain in extinguished condition until a rotary switch, through whose agency the station selection is accomplished, has completed its'stepby-step rotation, at which time the individual indicator lamp, associated with the selected station, is automatically illuminated. The undesirable flashing of lamps, which would otherwise occur as the rotary switch passed through various station positions during the course of its rotation, is eliminated by the means of the present invention.

These and other objects, features and advantages of the present invention, and the manner in which the objects are attained, will become clear from a consideration of the following description and of the accompanying drawing, wherein:

Figure 1.is a schematic representation of visual indicator means embodying a preferred form of the present invention; and f Figures 2, 3, and 4 are schematic representations which will be helpful in describing and understanding the operation of the circuit of Figure 1.

Referring now 'to Figure .1, there is shown a portion of a radio receiver including six stationselector'pushbuttons l li6, individual indicator lamps "-22 associated with the six pushbuttons, a rotary switch 23, a source of direct-current voltage 29, and conductors 31-42 and 3'la- 42a for effecting various circuit connections to be described.

In Figure 1, rotary switch 23 is comprised of a solenoid 24, a combination switch and pawl 25, a ratchet 26, a wafer-section 21, and a wafersection 28. The switch contacts of switch-pawl 25 are normally closed, as shown in the drawing, but when solenoid 24 is actuated, as will be described, the movable switch-arm 25a is ,pulled' .Wafer-section 21 oi rotary switch 23 includes a plurality of wiper contacts H and a disc-like rotor 3| having recessed portions or notches 32 and 33, spaced 180 apart. Wafer-section 28 includes a plurality of wiper-contacts h-n and a disc-like rotor 34 having extending portions or contacts 35 and 36 which are in radial alignment with notches 32 and 33 of rotor 3|.

Ratchet 26, rotor 3|, and rotor 34 are splined or keyed to a common shaft 30, as is indicated in Figure 1 by the dotted-line representation 49, and when ratchet 28 is rotatably moved, rotors 3| and 34 rotate in corresponding manner.

In Figure l, wiper-contacts a-f terminate conductors 3142 from lamps "-22 at rotor 3|; and wiper-contact a terminates conductor 44 from switch 25. Wiper-contacts h-m terminate conductors 310-4211 from lamps |1-22 at rotor 34; and wiper-contact n terminates ground connection 46.

In the particular arrangement illustrated in Figure 1, there are three equally-spaced wipercontacts per switch quadrant. Therefore, ,the switch mechanism, comprising solenoid 24, pawlarm a and ratchet 26, is so constructed as to move rotors 3| and 34 through sectors for each actuation of the rotary switch.

A plurality of pre-tuned station-selector circuits, indicated generally in Figure 1 by block 48, are operatively associated with rotary switch 23. being mechanically connected to shaft 30 by known means, indicated by the dotted-line representation 43. Upon each actuation of the solenoid, the station selector device 48 is switched from one position, in which a predetermined station is received, to another position, in which a diflerent station is received. Such pre-tuned station-selecting circuits are well known in the art and it is unnecessary to describe device 48 in greater detail.

4 divides substantially equally among the other indicator lamps |822, these five lamps being in parallel with each other, as just described. Each of these five lamps therefore receives but onefifth of the total current.

In accordance with the present invention, the circuit constants are so chosen that, while the total current in the above or similar circuit, when passed through a series-connected indicator lamp, is adequate to effect illumination, i. e., incandescence, thereof, one-fifth of the total current is not sufficient to eflect illumination. In addition, the circuit constants are so chosen that the total current through the above-described or similar circuit, while sufiicient to illuminate an indicator lamp, is insufilcient to actuate solenoid 24. Hence, in the example being described, with all pushbuttons in released positions, indicator lamp |1 remains illuminated as a result of a prior actuation of pushbutton all other lamps remain extinguished, and the receiver remains tuned to the station associated with pushbutton H and identified by lamp l1.

Assume now that the operator presses, say pushbutton l4, with the intention of tuning in the station associated therewith. As soon as pushbutton I4 is depressed, lamp I1 is extin- The operation of the circuit of Figure 1 will now be described. It is believed that an understanding of the invention will be facilitated by describing, in sequence, a series of assumed operating conditions.

Assume first that, as the description starts, the receiver is in operation and that, as a result of pushbutton having been previously depressed by the operator, the receiver is tuned to the station associated therewith. All pushbuttons are now in released position, since, as described above, the pushbutton mechanism is of the non-latching type and a button remains depressed only so long as the finger of the operator is in engagement therewith.

Indicator lamp l1, associated with pushbutton II, is illuminated, but all other indicator lamps are extinguished. The circuit components and connections which effect this condition may be reduced to the circuit shown schematically in Figure 2. By referring to Figures 1 and 2 it will be observed that a circuit is completed from the grounded terminal of voltage source 29 through lamp H to ground by way of the following' circuit components: voltage source 23, solenoid 24, the normally closed switch-contacts of switch 25, conductor 44, wiper-contact a, rotor 3|, wipercontacts b-f, conductors 38-42 in parallel, lamps |822 in parallel, conductor 43, lamp l1, conductor 31, conductor 31a, wiper-contact h, contact 35, rotor 34, wiper-contact n, and ground connection 46. Observe that the current, which passes, by way of the above-described circuit,

through lamp to effect illumination thereof,

guished, tor the current, which previously passed through the series-connected lamp l1 and through the bank of parallel-connected lamps |822, is now passed directly to ground 41, by way of the closed contacts of depressed pushbutton |4. The circuit which exists at the instant pushbutton I4 is depressed is shown in reduced form in Figure 3 and comprises the following: voltage source 29, solenoid 24, the closed contacts of switch 25, conductor 44, wiper-contact g, rotor 3|, and, forming a low resistance bypass across the entire indicating-lamp circuit, wiper-contact d, conductor 40, the closed contacts of pushbutton I4, and the ground connection 41. When the indicator lamps are thus bypassed, the resistance of the battery-throughsolenoid-to-ground circuit is decreased, the magnitude of the current through solenoid 24 is increased, and the increased current is adequate to actuate the solenoid;

When solenoid 24 is thus actuated, the movable pawl-arm 25a is drawn upwardly, i. e., toward the solenoid, and ratchet 26 is moved rotatably in a clockwise direction. When pawlarm 25a moves upwardly, the contacts of switch 25 open, but it will be understood that the established magnetic field of solenoid 24 is effective to complete the upward stroke of the pawl-ann, thus moving ratchet 26 through 30 of rotation.

When solenoid 24 is actuated and ratchet 26 is rotated, by pawl-arm 25a, as just described, rotors 3| and 34, being splined to common shaft 30, move rotatably clockwise, as is indicated by the arrows in Figure 1. Connection is made substantially immediately between rotor 3| and wiper-contact a, and, concurrently connection is broken at contact 35 between rotor 34 and wipercontact h. Pawl-arm 25a completes its stroke, as above described, and rotors 3| and 34 move through 30 of rotation, thus bringing notch 22 and contact 35 to the positions occupied by wiper-contactsb' and 2', respectively. At or about this time, pawl-arm 25a is released by solenoid 24 and returns to the de-energized position, thereby again closing the switch contacts of switch 25. Lamp I8 is now connected in a manner similar to that of lamp II in Figure 3, i. e., lamp I8 now occupies the position between the bank of cuit now obtaining may be traced in Figure 1 as follows: voltage source 23, solenoid 24, the againclosed contacts of switch 25, conductor 44, wipercontact 9, rotor 3|, wiper-contacts a, c-f, conductors 31, 39-42 in parallel, lamps I1, "-22 in parallel, conductor 43, lamp I8, conductors 33,

38a, wiper-contact 1, contact 35, rotor 34 and ground connection 46. When so connected. lamp l8 does not become illuminated, for, as previously described with respect to lamp ll, the lamp circuit bypassed by the low-resistance path which extends from rotor 3| to ground 41 by way of the closed contacts of the depressed pushbutton, i. e., pushbutton M. The current through solenoid 24 therefore remains substantially the same as that which obtained when pushbutton l4 was first depressed. Solenoid 24 therefore remains energized, pawl-arm 25a is again drawn upwardly, ratchet 26 is again moved through 30 of rotation, and rotors 3| and 34 are moved in like manner.

The action described above continues, in well known step-by-step fashion, until the low-resistance path, through solenoid 24 to ground 41, by way of the still-closed contacts of pushbutton I4, is broken at rotor 3| by the arrival of notch 32 at the position occupied by wiper-contact d associated with conductor 40 and depressed pushbutton l4.

After the connection between rotor 3| and conductor 40 is broken at wiper-contact d, as above described, a path obtains-from voltage source 25 through solenoid 24 to ground which may be traced as follows: battery 29, solenoid 24, the again-closed contacts of switch 25, conductor 44, wiper-contact g, rotor 3|, wiper-contacts aF-c, e, f, conductors 31-39, 4|, 42 in parallel, lamps 9, 2|, 22 in parallel, conductor 43, lamp 20, and then, assuming pushbutton H to be still depressed, to ground by way of parallel paths, one comprising the closed contacts of pushbutton I4 and ground connection 41, and the otherpath comprising conductor 40a, wiper-contact k, contact 35, rotor 34 and ground connection 45. The

reduced circuit is shown schematically in Figure 4.

It will be observed that in the circuit of Figure 4, just described, lamp 20 is in series with a parallel network comprised of the remaining five lamps and associated conductors. It is apparent that the resistance of the circuit of Figure 4 is increased over that of the'circuit of Figure 3, for in Figure 4 the bank of parallel-connected lamps and the single series-connected lamp 20 are in series with solenoid 24 whereas in Figure 3 the lamps are shunted by a path of negligible resistance. The current through solenoid 24 is hence decreased with respect to that which obtained in the circuit of Figure 3; and this decreasedpurrent is insuflicient to actuate solenoid 24.

It will be seen from the above that the step-bystep action of rotary switch 23 ceases when the low-resistance shunt path through the closed contacts of the depressed push-button is broken by the arrival of notch 32 at. the wiper-contact associated with the depressed pushbutton. The current in the circuit then obtaining, i. e. the current in the circuit shown in Figure 4, while insuflicient to actuate solenoid 24, is, as previously described, adequate to illuminate the seriesconnected lamp 20 associated with the depressed pushbutton l4. However, each of the other lamps,

- being in shunt with each other, draws but one fifth o! the total current, which is to eii'ect incandescence. I

The receiver has now been tuned, through the agency of the pre-tuned station-selector circuits. to the station identified with pushbutton l4: and the operator is informed that this has been accomplished by the lighting of lamp 20. In practice, the action is fast, and the selected station is obtained without appreciable delay. The operator thereupon releases the depressed pushbutton, 1. e., pushbutton 20 in the present example, and the circuit of Figure 4 becomes similar to that shown in Figure 2, with the exception of course that lamp 2o occupies the position occupied in Figure 2 by lamp II.

In prior art circuits of which we have'know ledge, indicator lamps associated with non-depressed pushbuttons are illuminated as the varinsumcient ions wipe-contacts are passed during the homing action of the rotary switch. And, since the pushbuttons and indicator lamps are ordinarily in ,sequential arrangement, the illumination will appear to run along the dial. This is an undesirable condition which is completely eliminated by the improved circuit of the present invention. For, as described above, all indicator lamps are extinguished as soon as a pushbutton is depressed, that is, as soon as a pushbutton is depressed to tune in a station other than the station to which the receiver is already tuned. Thereafter, no indicator lamps become illuminated until the homing action of the rotary switch is completed, at which time the individual indicator lamp identified with the selected station is lighted.

Attention is invited to the fact that the visualindicator system of the present invention will correctly identify the station received, even though the station received is not identified with the particular pushbutton depressed. For, in a radio receiver equipped with station-selector mechanism actuated by a rotary switch, it is quite possible, ordinarily, for the operator to tune in a station other than the station identified with a the particular depressed pushbutton. For example, assume again that in Figure 1 the receiver is tuned to the station associated with pushbutton H and that the operator presses pushbutton Assume further, however, that the operator releases pushbutton l4 after the rotary switch has moved through but two steps, i. e., through 60 instead of 90". In such case, the station associated with pushbutton l3 will be received instead of the station associatedv with pushbutton |4. Observe, however, that the visual indicating system of the present invention will correctly identify the station received. For, under the circumstances just assumed, lamp I! will become illuminated rather than lamp 2|. This will be readily. apparent from Figure 1 and from the circuit descriptions previously given. The indicating system of the present invention is readily adapted to use in automobile radio receivers which employ a foot-operated switch as an auxiliary to the hand-operated pushbutton mechanism. In Figure l, the connection 5| and the normally-open switch 52 is intended to indicate such an auxiliary foot-control circuit. When switch 52 is closed, as by the foot of the 7 operator, solenoid 24 is actuated and ratchet 26 is advanced 30, thus to tune in the station associated with the particular position to which the rotary switch is now advanced. Upon release of foot pressure, switch 52 opens, and the indicating la'mp associated with the station then tuned-in.

*asvasso 7 is illuminated, as will be readily understood from the description previously given hereinabove. Repeated operation of foot-switch 52 will bring in sequentially the stations associated with the various positions of the rotary switch, and will illuminate sequently the individual lamps associated with the said stations. We have described a preferred embodiment of our invention. Various modifications will occur tothose skilled in the art.

Having described our invention. we claim: 1. In a radio apparatus, an annunciator system comprising: a source of supply voltage; a sequence switch actuated by a solenoid in response to a. current of at least predetermined magnitude; a plurality of selector circuits operatively assoelated with said rotary switch; a plurality of manually-operated switches operatively asso- 'ciated with said selector circuits through the switch, for opening said low resistance path,

when said sequence switch has effected selection of the selector circuit associated with said closed switch, to efiect cessation of actuation of said sequence switch; and means, including said sequence switch, for closing, substantially concurrently with said opening of said low resist ance path, a high resistance path which includes, in series, said source of supply voltage,

said solenoid, the individual indicator means identified with said selected selector circuit, and the other of said indicating means, said other indicating means being connected in shunt with each other, the resistance of said high resistance path being such that the current through said solenoid is smaller than said predetermined magnitude, the current through the series-con- 1 nected indicating means identified with said selected circuit is sufiicient to effect activation thereof, and the current through said other shunt-connected indicating meansis insufilcient to efl'ect activation thereof.

2. In a radio receiver, an annunciator system comprising: a source of supply voltage; a rotary switch actuated by a solenoid in response to-a current or at least predetermined magnitude; a plurality of pre-tuned station-selector circuits operatively associated with said rotary switch; a plurality of pushbutton switches operatively associated with said pre-tuned circuits through the agency of said rotary switch; a plurality of individual indicator lamps operatively associated with said rotary switch, each of said lamps being identified with a different circuit of said .pre-tuned station-selectorcircuits; means, o'perative upon closing of a pushbutton switch, for completing a low resistance path, which includes said source of supply voltage and said solenoid but excludes said indicator lamps, to effect current flow of at least said predetermined magnitude and to effect actuation of said rotary switch; means, including said rotary switch, for opening said low resistance path, when said rotary switch has effected selection oi. the pretuned circuit associated with said closed pushbutton switch, to

\ ei'fect cessation of actuation of said rotary switch; and means, including said rotary switch, for closing, substantially concurrently with said opening of said low resistance path, a high resistance path which includes, in series, said source of supply voltage, said solenoid, the individual lamp identified with said selected pretuned circuit, and the other of said lamps, said 10 other lamps being connected in shunt with each identified with said selected pro-tuned circuit is sufiicient to effect incandescence thereof, and the current through said othershunt-connected lamps' is insufiicient to eil'ect incandescence thereof.

3. In a radio apparatus; a plurality of keys,

each of said keys being identified with a difi'erent circuit; a plurality of individual indicator means associated with said keys; selector mechanism, operative in response to the actuation of a key,

for effecting automatically selection 01' a circuit;

means, operative upon said actuation of said key, for: connecting a low resistance path in shunt with said plurality oi indicator means to maintain said indicator means in inactive condition during operation of said selector mechanism:

and means, automatically operative when the selection of the circuit has been eflected, for opening said shunt path and for connecting the individual indicator means identified with the cir- 5 cult selected in series with the other of said in dicator means, said other indicator means being connected in shunt with each other, thus to activate the' indicator means identified with the station selected while maintaining said other in- 0 dicator means in inactive condition.

4. In a radio receiver; a plurality of pushbuttons, each of said pushbuttons being identified with a difierent station; individual indicator lamps associated with said pushbuttons; station selector mechanism operative in response to the actuation 01' a pushbutton for tuning automatically said receiver to a selected station; means operative upon said actuation of said pushbutton for connecting a low resistance path in shunt with'said indicator lamps to maintain said indicator lamps extinguished during operation of said selector mechanism; and means automatically operative when the selection of the station has been eflected, for opening said shunt path and for connecting the individual indicator lamp identified with the station selected in series with the other of said lamps, said other lamps being connected in shunt with each other, thus to illuminate the indicator lamp identified with the station selected while maintaining said other lamps in extinguished condition.

' OTTO C. KEIL, Ja.

JESSE HEWITT LOF'ION.

5 REFERENCES CITED The following referenices are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,777,796 Hubbell Oct. '7, 1930 2,241,156 Powell May 6, 1941 2,387,444 Hayslett Oct. 23, 1945 2,424,243 Lowell July 2'7, 194'? Certificate of Correction Patent No. 2,472,536. June 7, 1949.

OTTO C. KEIL, JR., ET AL. It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 30, for annunciation read anmmciator; column 2, line 31, for conductors 37-42 read conductors 37-44; column 5, line 13, before the word bypassed insert is; line 41, after one insert path; column 6, line 19, for Wipecontacts read wiper contacts; column 7, line 6, for sequently read sequentially; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 8th day of November, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents.

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