US2821631A - Signal-seeking device - Google Patents

Description

2 Sheets-Sheet 1 Filed May 25, 1955 Jan. 28, 1958 J. H. LOFTON 2,821,631

SIGNAL-SEEKING DEVICE Filed May 2:5, 1955 2 sheets-sheet 2 Fvg. 2.

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csp/4"" 46 INVENTOR. 75555 f7. LFTN limited States Patent O 8 Claims. (Cl. Z50- 40) Pa., assignor to Philco Pa., a corporation of Penn- The invention hereinafter described and claimed relates to signal receivers of the signal-seeking type which function, 1n response to successive initiations on the part of the user, to tune themselves automatically and successively to receivable signals within the reception range. More partlcularly, the invention has to do with signal receivers of. the type described and claimed in the copending application of l. E. Laschenski, Serial No. 468,008, filed November 10, 1954, and assigned to the assignee of the present invention.

The apparatus of the aforesaid application provides for overall signal-seeking operation i. e., signal-seeking operation which progresses through the entire reception range or band from one end of the band to the other. However, it also provides for limited signal-seeking operation over selected portions of the reception band. Thus, With respect to broadcasting stations to which the user of a radio receiver customarily listens, it provides selection of signals in the respective portions of the reception band in which the transmitting frequencies of such stations are located. By providing selective limited signal-seeking in response to selective operation of push-buttons, the tunlng operation is greatly simplified and elTort on the part of the operator is minimized.

It is an object of the present invention to provide an improved signal-seeking receiver of the aforesaid type.

Another object of the invention is to provide improved apparatus for selectively limiting the predetermined portions of the reception range over which the signal-seeking operation is carried out.

A further object of the invention is to provide such an arrangement for limited signal-seeking which is simple in construction, easy to adjust, and which is substantially immune to accidental change of setting of the elements which determine the selective limited signal-seeking portions of the reception range.

In accordance with the present invention, there is provided in apparatus of the above-identified type, improved means whereby the limited signal-seeking portions of the broadcast range may be quickly and easily selected or adjusted from one portion of the broadcast band to another.

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

Figure 1 is a diagrammatic illustration of a signalseeking receiver in which the apparatus of the present invention is particularly adapted for use;

Figure 2 is a sectional elevational view of apparatus embodying the present invention;

Figure 3 is a perspective View of one of the elements which determine the selectable portions of the reception band for limited signal seeking;

Figure 4 is a sectional view taken on line 4--4 of Figure 2;

Figure 5 is a sectional view taken on line 5 5 of Figure 2; and

Figure 6 is a view similar to Figure 5 but showing a different operational condition.

It is believed that the present invention may best be understood by considering iirst the electrical system and the general operation of the receiver, and then a mechanical structure incorporating the improvement afforded by the present invention.

The system which embodies the invention is preferably of the type described and claimed in the above-mentioned Laschenski disclosure and, as shown in Figure l, includes a conventional signal receiver which, in the embodiment depicted in the figure, is a superheterodyne radio receiver. Such a receiver may comprise an antenna 11, one or more R. F. amplifier stages 12, a converter and oscillator stage 13, one or more I. F. amplifier stages 14, a detector 15, one or more audio amplifier stages 16, and a sound reproducer or loud-speaker 17. Tuning of the receiver preferably is effected by movement of adjustable cores according to the well-known permeability tuning method, two such cores being represented at 18 and 19. The cores are moved by means of a carriage 20 to which they are connected as indicated by the dashed lines 21 and 22. The carriage 20 preferably is actuated by means of an electric motor 23 through suitable actuating means represented by the block 24, and while other actuating means might be used for this purpose, the apparatus shown and described in above-identitied copending application is preferred.

While the invention is broadly applicable to signal receivers, it may be assumed that the radio receiver shown in Figure 1 is to be used on a vehicle, such as an automobile, and therefore the usual vehicle battery is represented at 25, and the usual vibrator and rectifier unit is represented in block form at 26. It will be understood that the battery 25 and the unit 26 supply the operating voltages to the receiver components shown in block form. For simplicity, the connections for supplying such voltages have been omitted.

The driving motor 23 is controlled by a relay 27 whose winding 28 is energized from unit 26 by momentary closure of switch 29. The relay winding 28 has one terminal connected to the anode of a control tube 30 and the outer terminal connected to the positive high voltage supply of the rectifier unit 26. In addition, the terminal of winding 28 which is connected to the anode of tube 30 is also connected through a current-limiting resistor to one terminal of single-pole single-throw switch 29, the other terminal of which is connected to a point at ground potential. When switch 29 is momentarily closed, relay 27 is energized, thereby connecting the cathode of control tube 30 to a point at ground potential through relay contact 31. As a result, a heavy cathodeanode current flows through control tube 30 and maintains energization of relay 27 independently of switch 29. Through its contact 32, the relay effects energization of the motor 23 which is in circuit with the battery 2S. Through contact 36, the relay mutes the radio receiver by short-circuiting the input to the audio stages.

The motor 23 drives carriage 20 in a direction to tune the receiver to the next receivable signal. When such a signal is tuned in, the tube 30 is rendered non-conductive to deenergize the relay winding 28 thereby to deenergize the motor and to restore the operative condition of the audio input, thereby producing audible signals which in the normal operation of the receiver serve to reproduce music or speech or the like and which in accordance with this invention also indicate the moment for one of the manipulations in the station selecting operation. The opening of relay contact 31 opens the cathode circuit of tube 30 and thus renders the tube inoperative until such time as the relay is again energized by closure of switch 29.

It iswell-known vinthe art to effect cut-od of a control tube in response to a tuned-in signal, and any of the known arrangements may be employed to cut-off the control tube 30. Preferably, however, the control arrangement is of the character disclosed and claimed in the copending application of Ralph Bray, Serial No. 459,043, led September 29, 1954, and is represented by the rectangle 33. In such a system, two signals are derived from the I. F. portion of the receiver via conductors 34 and 35 and are applied to a phase detector, the output of which is coupled to the control grid of the control tube through a dierentiating circuit.

As thus far described, the receiver comprises means for tuning in signals having frequencies within a predetermined frequency range, e. g. the broadcast band, and means for stopping the tuning operation when a signal is tuned in. In accordance with the present invention, and 1n common with the Laschenski contribution, provision is made for limited signal-seeking operation under control of at least two pairs of switches, one switch of each pair being actuated by the tuning means, and the other switch of each pair serving to render the rst switch effective or ineffective. The stopping of the tuning operation is made to depend, not only upon the reception of a signal, but also upon the conditioning of circuit means under control of the pairs of switches.

In the illustrated embodiment, there are tive switches numbered 39 to 43, but it should be understood that this number of switch pairs is arbitrarily chosen. Each of the switches 39 to 43 forms a part of one of said pairs of switches and comprises a movable contact 44 which is actuated by the carriage 20, as by apparatus indicated by the Vdashed lines 45 (see also Figure 2), and a stationary but adjustable contact 46; the various adjustable contacts 46 being mounted for presetting so as to effect closure of the various switches 39 to 43 in different portions of the operating range of the carriage corresponding to different portions of the reception band. In the illustrated system, the contact 44 of each of the switches 39 to 43 is grounded, but this is only because of the way in which the switches are made to serve the desired vpurpose as hereinafter described. Associated with the switches 39 to 43 are push-button switches 47 to 51 which are normally in the front position, as shown, but are selectively movable to a back position. Each of the push-button switches comprises a front Contact 52, a back contact 53, an intermediate contact 54, and a movable bridging contact 55 which engages the intermediate contact 54 in both positions of the switch. The back contacts 53 of the push-button switches are connected respectively to the stationary contacts 46 of the switches 39 to 43. Actuation of any one of the push-buttton switches causes the movable contact element 55 to leave the front contact 52 and to engage the back contact 53.

The above-described switches serve to effect selective limited signal-seeking through control of circuit means adapted to control operation of the means for stopping the tuning operation. Preferably such circuit means 4is the cathode-to-ground connection for one or more of the high frequency stages of the receiver. Thus, in the illustrated embodiment, the circuit conductor 56 is connected to the cathodes of the tubes in the R. F. and I. F. stages, and this conductor extends to the contact 54 of the extreme left-hand push-button switch 47, which contact is a terminal to which ground potential must be applied as a condition precedent to the stoppage of the tuning operation. It will also be noted that the front and intermediate contacts of adjacent push-button switches are interconnected. It will be seen, therefore,

thatemovement of any one of the push-button switches tov its back position will edect connection of the conductor 56 lto the corresponding one of switches 39 to 43.v As in' the case of the conventional push-button mechanism,

a latch bar 57 (see also Figure 2) serves to hold any one'- 4 of the push-button switches in its back position, releasing any previously actuated switch.

Therefore, the conductor 56 can be connected to only one of the switches 39 to 43 at one time, so that only one of said switches can be effective to apply ground potential to said conductor.

With the arrangement shown, if the push-button switches are all left in their front positions, as shown, and switch 29 is actuated, the tuning system will operate to effect overall signal-seeking action from one end to the other of the reception band. This is due to the fact that the conductor 56 is connected to ground (through device 59) independently of switches 39 to 43 which are ineffective. However, actuation of any one of the pushbutton switches 47 to 51 will cause the tuning system to effect selective limited signal-seeking action over the selected portion of the reception band, because the conductor 56 will then be connected to ground only as controlled by one of the switches 39 to 43.

To initiate overall signal-seeking operation of the system, the switch Z9 need only be closed momentarily. In the preferred embodiment illustrated, this switch is momentarily actuated by the latch bar 57 which shifts momentarily toward the right, as in conventional pushbutton arrangements, each time one of the push-buttons is depressed. A push-button 5S, spring loaded at 95, is provided which serves simply to shift the latch bar momentarily to etect momentary closure of switch 29.

In signal-seeking receivers, it is generally desirable to provide for decreased sensitivity of the receiver during overall signal-seeking operation. The purpose of this is to insure that the tuning will be stopped only in response to a signal of adequate strength for satisfactory operation of the receiver. Therefore, in the illustrated system, there is preferably provided `a sensitivity control device 59 which may comprise a tapped resistor 60 and a multiposition switch having a grounded movable contact 61 and stationary contacts 62. This device is connected, as shown, to the front contact of push-button switch 51 and to the normally-closed stationary contact 37 of relay 27. When the relay is deenergized, the device 59 is rendered ineffective as the conductor 56 is connected to ground independently of the device 59 through relay contact 37. However, when the relay 27 is energized, the ground connection for conductor 56 through contact 37 is opened, and the conductor 56 is connected to ground through the switch arm 61. With this switch arm in its eXtreme lefthand position, the receiver sensitivity is not reduced, but with the switch arm in other positions, the receiver sensitivity is reduced according to the amount of included resistance.

The present invention is particularly concerned with the switching mechanism providing improved selection of portions of the reception band for limited signal-seeking operation. In this regard, reference is now made to Figures 2 through 6.

In Figure 2 it is seen that the apparatus 45, which is indicated by dashed lines in Figure l, comprises an inverted channel member 62 to which eXible contact lingers 44 are secured by clamping plate 63 and rivets 64. The push-button mechanism includes a front panel 65 secured to a base member 66. Above the base member isa horizontal shelf 67 formed of insulating material and supported at its front on flange 68a of a shell 63 secured to front panel 65 by screws 69. At its rear, shelf 67 is supported by a bracket 70 mounted on base plate 66. The member 62 is moved by the carriage 20 (Fig. l) in a horizontal plane in the space between base plate 66 and shelf 67 I(Fig. 2).

Secured to the underside of the insulating shelf 67 is a supporting bracket 71. While only one of these brackets is shown, it will ybe understood that each of the ve push-buttons 47 through 51, see Figure l, is so i provided. As shown in Figure 2,- each of these brackets supports, as shown at 71a and 7llb, track means which in .5 this embodiment of the invention comprises a rotatable shaft 72 which has a forwardly projecting stem 73 that projects through an aperture in the front panel 65.

In particular accordance with the present invention, each of the shafts preferably is I-shaped in cross-section, as shown in Figures 4 through 6, with opposite at sides 74 and 75. It should be understood, however, that it is sufficient that only one flat side or reduced diameter portion be provided, as will appear more clearly as the description proceeds.

Each of the shafts 72 passes through apertures 77 in end walls 78` of one of the adjustable, stationary switch elements 46, which element may be U-shaped, thus slidably to support the element upon the shaft, it being noted that this is the similarly designated switch element mentioned in the preceding description in connection with Figure l. Each of the end Walls 78 include an upper, reduced portion 78a (Fig. 5), which extends into an area between side llanges 76 of the associated bracket 71, thus to prevent the element 46 from turning with the supporting shaft 72. The central area 79 of the bottom surface of each element 46 is framed by an insulating member 80 (see Figure 3) which is held against the bottom surface of element 46 by turned-down lugs 81 thereon. The framed portion of the bottom surface of the contact element 46 is adapted to be engaged by one of the resilient contact fingers 44 whose free end portion wipes over said area between the retaining lugs 81 during signal-seeking action.

As shown in Figures 2 and 5, each of elements 46 may be locked against slidable movement on shaft 72 by resilient means comprising leaf spring 82 bearing upwardly against the bottom of the shaft when the latter is in a vertically disposed position with the reduced diameter portion turned away from the spring. Reduced end portions 83 of the spring extend through slots 84 formed in member 46 at the juncture of the end walls 73 with the bottom surface 8S. By rotating shaft 72 through 90 so that the reduced diameter portion faces spring 82, as shown in Figure 6, the spring tension is released and element 46 is free to slide on the shaft.

As may be seen in Figure 2, each of the shaft-supporting brackets 71 has an upwardly-extending contact linger 53, which corresponds to the similarly designated contact in Figure l and is an element of the corresponding pushbutton switch. Thus this finger is electrically connected to contact element 46 through the shaft and associated bracket. This linger 53 projects upwardly through an aperture (not shown) in the insulating shelf 67 so that it is within the enclosure defined by the shelf 67 and the previously mentioned shell 68. This enclosure also contains the other elements of the push-button switches 47 to 51. As shown in Figure 2, each of these switches comprises a slide bar 86 which is urged forwardly to the right, by a spring 87. Each slide bar carries an insulating plate 88 on which contact element 55 is mounted, the latter being the similarly designated contact of Figure l. This contact is a bridging contact which normally engages the front and intermediate contacts 52 and 54 which are mounted on the insulating shelf 67. The electrical connections to the latter contacts are as shown in Figure l. Normally, the bridging contact 55 engages contacts 52 and 54, but when the slide bar 86 is actuated, the bridging contact 55 leaves contact 52 and engages the back contact 53 so that it then bridges the contacts 53 and 54. Upon such actuation of any push button, this push button is latched behind bar 57 by cam and shoulder 91, 92, whereas during such actuation all other push buttons are unlatched, as is well known to the art.

As previously described in connection with Figure l, the contact elements 46, in cooperation with contact lingers 44, serve to dene portions of the signal reception range or band for limited signal-seeking tuning. The contact elements 46 may be preset for selection of a 6 particular broadcasting station in the novel manner now to be described.

With all of the push-buttons in their outer position (Figure l) and shafts 72 all turned to the position shown in Figure 6, the Search unit is operated through one cycle, preferably with the sensitivity adjusted too low to pick up a signal suiciently strong to stop the operation. During the complete cycle, spring contacts 44 pick up elements 46 by movement of the ends 44a of the contacts into the framed central areas 79. Elements 46 then move freely on shafts 72, and as a unit with member 45 and contacts 44, during cycling of the core bar.

The sensitivity control 59 is then adjusted to stop tuning in response to a signal of desired strength, and when the search unit has been started again and the first such response received any one of the shafts 72, depending upon the push-button with which it is desired to associate this signal, is turned as shown in Figure 5, thus locking the selected element 46 on the shaft in the position automatically established by the stopping of the tuning operation. The same procedure is followed in setting up the other push-buttons to receive other signals. As pointed out below, this is a simple and very accurate pre-sele-ction procedure.

With this arrangement, it is unnecessary to make highly accurate adjustments for preselecting stations to be tuned in by the push-buttons. The signal-seeking action within the available range in itself effects accurate automatic positioning of a switch element 46, as described above; and the manual fixing of this element, in the position automatically established by the apparatus described, avoids any danger of disturbing said position, thereby insuring highly accurate subsequent tuning of the receiver to the desired station. This eliminates the need for extremely accurate mechanical tolerances and adjustments. Furthermore, the presetting adjustment is simple and can easily be performed by the user.

What is claimed is:

1. In switching apparatus wherein a first contact element can be moved in predetermined directions by a power means, relative to a second, normally stationary Contact element which is adjustable in said directions, an adjustment selector for the second element, comprising: track means for the adjustable contact element, extending parallel to said directions; means for inter-engaging and disengaging the first and second contact elements so that the power means may effect movement of the inter-engaged elements, along the track means; means for stopping such movement; and engagement control means, operable after such stopping to move the track means and a part of the adjustable contact element relative to one another, transversely of the track means, and for thereby fixing the adjustable contact element in the position established by said stopping.

2. In apparatus as claimed in claim 1, engagement control means as described including means for manually moving only the track means transversely of its length.

3. In apparatus as claimed in claim 2, track means comprising a flattened shaft rockably engageable with the adjustable contact element.

4. In a signal receiver, a set of tuning elements; motoractuated means for moving such elements relative to one another into a position where they are tuned to a preselected signal; switch means adapted to stop said motor actuated means exactly in the tuned position, said switch means comprising a contact normally movable by said motor-actuated means and an adjustable, normally xed Contact; and adjustment means for the latter contact, comprising means for mechanically inter-engaging said normally fixed and movable contacts for joint movement, in order to adjust the adjustable contact, and engagement control means fixing the adjustable contact pursuant to and exactly at a point of said stopping, to correspondingly preselect a different signal.

5. In a receiver as claimed in claim 4, engagement` control means as described including track meansV for the adjustable contact; means on the adjustable contact for gripping the track means in a rst position of the track means and for substantially releasing it in a second position thereof; and means for placing the track means in either of said positions.

6. In a receiver as claimed in claim 5, engagement control means as described including resilient means on the adjustable contact for engaging and disengaging the track means.

7. In a receiver as claimed in claim 5, the feature that the track means, in moving from one of said positions to the other, moves transversely of the movement of said elements.

8. In a receiver as claimed in claim 5, means for'interengaging as described, including a resilient contactor linger on one of the contacts.

References Cited in the le of this patent UNITED STATES PATENTS 1,906,106 Schaefer Apr. 25, 1933 2,034,254 Stenerson Mar. 17, 1936 2,177,850 Vogt et al Oct. 31, 1939 2,186,828 Forstrorn Ian. 9, 1940 2,501,003 Pifer Mar. 21, 1950

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