US3439292A - Multiple-selection pushbutton device for radio sets having voltage variable capacitance tuning means - Google Patents

Description

April 15, 1969 G. A. HENRY 3,439,292

MULTIPLE-SELECTION PUSHBUTTON DEVICE FOR RADIO SETS HAVING VOLTAGE VARIABLE CAPACITANCE TUNING MEANS Filed June 5, 1967 v Sheet of 4 FIG. '1

V/ 7 101 A v 101 I0 10; 104 10! is 101 INVENTOR Georges A. HENRY April 15, 1969 s. A. HENRY 3,439,292

MULTIPLE-SELECTION PUSHBUTTON DEVICE FOR RADIO SETS HAVING VOLTAGE VARIABLE CAPACITANCE TUNING MEANS Filed June 5, 1967 Sheet 2 of 4 all/ll ///7/ INVENTOK Georges A. HENRY 3,439,292 ETS Sheet on 5m 5m 8w 1 QOE mvm'roa Gotges A. BY Mufl" NRY ATTORNE G. A. HENRY PUSHBUTTON DEVICE FOR RADIO S VOLTAGE VARIABLE CAPACITANCE TUNING MEANS Apnl 15, 1969 MULTIPLE-SELECTION HAVING Filed June 5. 1967 WOE a a m a: a m a a mivvv h-= Q Ililil: --=l==- Q. w u x1 Nil: 2: m 9E 3,439,292 ETS Sheet 4 of 4 A. HENRY PUSHBUTTON DEVICE FOR RADIO 5 HAVING VOLTAGE VARIABLE Filed June 5. 1967 A April 15, 1969 G,

MULTIPLE-SELECTION CAPACITANCE TUNING MEANS United States Patent Int. or. has; /32

US. Cl. 334-7 5 Claims ABSTRACT OF THE DISCLOSURE Multiple selection pushbutton device for radio sets including variable capacitors and variable capacitance diodes, comprising (i) a plurality of rotatable push-buttons each having a helical potentiometer body rigidly connected thereto and a push-rod rotatively connected thereto, (ii) a plurality of mechanisms each including a slide cooperating with the potentiometer body, (iii) a capacitor actuating bar in the path of the push-rods and actuated thereby depending on their length, (iv) members provided on the pushbutton mechanism extending in different radial directions for selectively actuating a frequency range, (v) change-over switches, (vi) means for feeding the helical potentiometer through the changeover switches and (vii) means for varying the length of the push-rod and the position of the slide with respect to the potentiometer body, whereby the rotation of the pushbutton simultaneously determines the length of the push-rod and the biasing voltage of the variable capacitance diodes.

The present invention relates to improvements to the multiple-selection pushbutton device for radio and television sets described in my copending patent application Ser. No. 549,395 filed May 11, 1966, now US. Patent No. 3,390,581, issued July 2, 1968.

In this device, applicable in particular to television receivers, the depression of a pushbutton causes the reception of the corresponding transmitter through simultaneous action of various parts of a pushbutton mechanism on various switches and on the tuning control members of the receiver, each pushbutton permitting the scanning of the selected frequency range, the complete scanning of the VHF and UHF bands being effected by means of variable capacitors and of three circuit arrangements corresponding to three frequency ranges, two for the VHF bands I and III totalling a dozen channels and a single one for the UHF bands IV and V totalling more than forty channels.

The UHF range is not divided into several sub-ranges because any switching over in such a range is a delicate operation; it follows that variable capacitors are used as tuning control members, since the range of frequencies in question is very wide.

Likewise in the device forming the subject of the Patent No. 3,390,581 above referred to, a single group of variable capacitors is provided, rigidly connected to one and the same shaft to control either the UHF tuning circuits or the VHF tuning circuits which are then connected in series with the aforesaid circuits as is well known in the art at present. In mass-production, this leads to incorrect alignment of the high-frequency circuits, not originally in accordance with the same laws of variation.

On the other hand, it is known that the variable-capacity diodes, known as Varicaps, now offer valuable characteristics for the tuning of the VHF bands. These semiconductor diodes have an internal capacity inherent in the junction which they comprise and this capacity depends 3,439,292 Patented Apr. 15, 1969 on the reverse bias. This interesting property has found various applications including the most recent which is the automatic frequency control known as AFC, in which the limited range of variation in frequency does not raise any problems.

It is likewise known that the Varicap tuning-circuit control consists of a variable-voltage generator composed of a simple potentiometer or rudimentary potentiometer device the potentiometer control versus voltage characteristic curve of which is adapted to the capacitance versus voltage curve of the diodes in such a manner that the variation in frequency is linear or substantially linear as a function of the control of the potentiometer.

The present invention relates to the association with the various mechanisms of the pushbutton device, forming the subject of the above mentioned Patent No. 3,390,581, of control means for generating a biasing voltage for variable-capacity diodes.

Another object relates to the switching, by each of the pushbuttons, of the device of the invention, of a possible automatic frequency control circuit AFC.

Other features and advantages of the present invention will be apparent from reading the following description of a typical example of an embodiment applied to television, said description being given with reference to the accompanying drawings in which:

FIG. 1 illustrates, in perspective, the selector of the invention which is identical in appearance with the selector of the aforesaid patent application;

FIG. 2 illustrates, partially and diagrammatically, the various elements of the electrical circuits which the selector contains;

FIGS. 3a and 3b are respectively an axial section and cross-section through a pushbutton and its mechanism in the position of rest;

FIGS. 4a and 4b are respectively an axial section and a view partially in elevation, partially in section, of a pushbutton and its mechanism, respectively in the engaged position and in the tuning position;

FIG. 5 illustrates the spring grid co-operating with the barrels;

FIGS. 6a, 6b and 6c illustrate a new barrel provided with contact spring-blades;

FIG. 7 illustrates a threaded core acting as a potentiometer body or a support for a variable resistor;

FIGS. 8a, 8b, 8c, 8d, 8e, 8 and 8h show the parts of the new mechanism in a metal which is an electrical conductor, except the part 8g which is of insulating material;

FIGS. 9 and 10 are two electrical diagrams using a potentiometer;

FIGS. 11, l2, 13, 14 are electrical diagrams using only a variable resistor; and

FIGS. 15 and 16 illustrate a modification of the pushbutton mechanism according to the invention.

Referring first to FIG. 1, the new selection device is seen as a whole. It comprises seven pushbuttons 10 to 10 as in the example described in the aforesaid patent application, all the selection means of which are retained apart from the switching elements associated with the UHF circuits which are no longer required as will be seen in the course of this description and as can be seen in FIG. 2 which comprises diagrammatically and partially the various means used in the present device.

It should be understood that, as it is illustrated diagrammatically in FIG. 2, the present device applies to other applications than television, particularly to AM-FM receivers.

The selection mechanism consists of a turret 19/1 (FIGS. 3a and 3b) externally identical to the turret 319 in the aforesaid Patent No. 3,390,581 (FIG. 15c) which can be pushed by a pushbutton 1011 (FIG. 311) externally identical to the pushbutton 311 of the said patent (FIG. 15a). The pushbutton 1011 is drilled axially and can slide freely on the front portion of shaft 1211 (FIG. 3a and FIG. 8a). This front portion has a square section as does the axial bore in the pushbutton 10m The pushbutton comprises a collar 13 and terminal teeth 312 (FIG. 3a) which, with the teeth 320 of the turret 1911, form a dog clutch which enables the pushbutton to drive in rotation the turret 19n, a barrel 4911, and a setting cone 40 fulfilling identical functions to the cone 40 in the aforesaid patent.

The pushbutton 10n is of insulating material and it comprises a terminal conductive member 100 in the form of a disc, the edge of which projects with respect to the internal cylindrical surface of the pushbutton. The part 100 comprises a spring tongue 10! which fits into an appropriate housing 10a inside the pushbutton and the arched end of this tongue rubs against the shaft 12n thus ensuring a permanent electrical contact between the disc and the shaft.

The shaft 12a is drilled with a flat bottom and internally threaded and the push-rod 25 screws into the axial bore in the shaft. This push-rod 25 comes into contact with the control bar 81 when the pushbutton is engaged.

The shaft 1212 is terminated by a stop collar 12b, bored at 12c to form a seating adapted to receive a core which will be discussed later.

The barrel 4% (FIGS. 6a, 6b and 6c) is provided with an internal envelope 49e of a conducting metal comprising recesses 54 and two diametrically opposite, longitudinal spring blades 491. The recesses 54 co-operate with the dihedrals 57 of the flat ladder-type spring 55 (FIG. held tangent to all the barrels by means of two slots hollowed out respectively from the bar50 and the frame 101 into which the edges of the spring are inserted. The bar 50 and the frame 101 are both made of insulating material; it follows that the spring 55 is electrically insulated with respect to ground as represented by the device but it is in permanent electrical contact with the cylinder jackets 49e of the barrels and, consequently, with the spring blades 491. It will easily be understood that by pushing in the pushbutton 1011, the disc c enters between the blades 491 to ensure an electrical contact.

At the point which the description has reached and anticipating the description of the general operation, it will be seen that an electrical circuit, one terminal of which was connected to the flat spring 55 and the other to the control bar 81 could be closed by two switches in series, the terminals of which would be 491 and 10a for the one and 25 and 81 for the other.

Force-fitted into the seating 12c in the collar 12b of the shaft 121: (or cast thereon) is a threaded core 200 (FIG. 7), force-fitted or cast on to the other end of which is a pierced metal cup 201 (FIG. 8e).

Welded on to the flanges of the collar 12b and of the cup 201 are the ends of a resistance wire 202 wound in the bottom of the threads 203 in the core. The threading, which is over-dimensioned with respect to the resistance wire, is adapted to a slide 204 (FIG. 8d). This slide is in the form of a spider, one arm 205 of which is rectilinear and overhung and ensures a double contact with a metal tongue 291 and the other arm 206 is curved and ensures a double contact with the resistance wire 202.

The tongue 29l is soldered on to a metal ring 2911 (FIG. 80) force-fitted (or cast) on to the turret 1911 and which constitutes the boss of the turret serving for the engagement of the latter with the interlock plate 35. The tongue 291 is housed and fixed at the bottom of a longitudinal groove 19;- formed inside the turret 19n (FIGS. 3a and 3b).

The core 200 and the shaft 12n which is rigidly connected thereto can rotate freely inside the turret but are held there by the guide member 3411 (FIG. 8g) fixed by adhesion or otherwise to the rear of the turret. It will be understood that the core 200, driven in rotation by the shaft 1211, because of its threading, urges the slide axially, from the front towards the rear or vice versa according to the direction of rotation, the guide groove 191', in which the arm 205 is inserted (with appropriate clearance), preventing the slide from being driven in rotation and, on the other hand, since the push-rod 25, guided by the member 34n, has a stop collar 25', it follows that the number of revolutions of the core is limited by the number of threads in the push-rod 25, the latter abutting, during the rotation of the shaft 12n, either against the bottom of the axial bore 23 in the shaft or against the member 34a with its collar 25' according to the direction of rotation. The purpose of this arrangement is to protect, in the event of forced manipulation, the slide, the portions 206 of which bear laterally against the inside of the threading in the core being relatively fragile; now the closer the threads, the more numerous they will be, and consequently the longer will be the path but also the more fragile will be the slide. It is therefore advisable to limit the scanning of the slide 204 by the travel of the push-rod 25.

The member 34n has a square aperture in which the push-rod 25 slides and it comprises two diametrically opposite holes 34: serving for the passage of two teeth 208 on a disc 207 (FIG. 8 against which there bears the return spring 59 of the pushbutton mechanism. The other end of this spring bears against the frame of the apparatus by means of a metal plate 209 (FIG. 8/1). This metal plate 209 is drilled with as many holes 210 as there are pushbuttons to allow free passage to the push-rods 25 and remain isolated from the push-rods. The plate 209 constitutes a connection which is common to all the pushbutton mechanisms and is cut out so as to fit into the dished holes 157 and into an appropriate groove 157r formed in the support of insulating material 156 for the fixed contacts 119 of the standards switch (FIGS. 1, 3a and 8h). The plate 209 is equipped with a soldering lug 211.

At the point which the description has now reached, it is easy to understand the potentiometric system adapted to control the Varieap diodes and forming the main object of the present invention. If a source of current is connected in between the control bar 81 and the lug 211 it will feed the resistance wire 202 wound on the core 200, in the engaged position of FIG. 4a, and a variable voltage depending on the position of the shaft 12n will appear between the interlock plate 35 and the control bar 81 or the lug 211. Actually, on the one hand the current reaches one of the ends of the resistance wire 202 wound on the core 200 by means of the push-rod 25 pressing against the control bar 81 and screwed into the shaft 1211, the collar 12b of which is soldered to the resistance wire. The current reaches the other end of the resistance wire by means of the cup 201 to which is soldered the other end of the resistance wire in sliding contact with the disc 207 through its teeth 208 which are sufliciently long to be always in contact as a result of a spring 59 electrically connecting the disc 207 to the lug 211. As for the variable voltage, this is transmitted to the interlocking bar 35 by means of the slide 204 in contact with the resistance wire 202 and with the tongue 291 soldered to the ring 29n which, with the bar 35, constitutes the interlock mechanism. It will likewise be understood that when the pushbutton mechanism is in the position of rest of FIG. 3a, the current no longer circulates in the wound resistor because of the interruption between 25 and 81 and the fact that the ring 2% and the plate 35 are no longer in contact. It may therefore be said that the ring 2911 and the plate 35 constitute the terminals of a first switch designated hereinafter by the symbol 29/35, just as the push-rod 25 and the stop 81 constitute the terminals of a second switch hereinafter designated by the symbol 25/81. Similarly, with regard to the switch constituted by the parts and 49l, this will be designated hereinafter by the symbol 10/ 49.

The inputs or the outputs of the various circuits described hereinafter may, if necessary, be constituted by flexible wires, as in current practice, 212 soldered to the control bar 81, 213 soldered to the ladder- type spring 55 and 214 soldered to the interlock plate 35. The return springs 36 of the plate 35 are no longer secured to the above mentioned spring 55 as in the aforesaid Patent No. 3,390,581 but to the frame 101 of insulating material, this feature only being necessary for the wiring diagrams in FIGS. 9, 10, 11 and 12.

FIG. 9 illustrates a practical wiring diagram for the tuning of a channel through control of Varicap diodes. In this figure, 301 designates a Varicap diode, 302 the inductance and 303 the decoupling capacitor of a VHF tuning circuit (FIG. 2). FIG. 9 again shows the switches 29/35, 25/81 and 10/49, the resistance wire 202, the slide 204 and the equipotential bar 291. When the switches /81 and 29/35 are closed, the source of current 304 feeds the potentiometer 202 and the output voltage of the potentiometer biases the Varicap diode 301. If the switch 10/49 is closed, the AFC circuit is closed through the resistor 305 connected in series with the tuning circuit. If the switch 10/49 is open, the AFC circuit is interrupted. The resistor 306 of the order of one Megohm is adapted to protect the Varicap diode from possible excess voltage and to block the high-frequency interactions between the various circuits.

In all the following diagrams, the switch 10/49 serves to interrupt the AFC circuit.

As has been seen, when the switches are open the source 304 does not supply current. The number of selection mechanisms can therefore be multiplied as shown in FIG. 10. The reference numerals in each potentiometric circuit and each switch are given an index, 1 with regard to the pushbutton 10 which is at rest and 4 with regard to the pushbutton 10 in FIG. 1 which is engaged.

In FIGS. 11, 12, 13, 14, the potentiometer is replaced by a variable resistor likewise designated by 202.

It is known that a linear variation in voltage applied to the Varicap diodes does not lead to a linear variation in frequency and that, in consequence, the control potentiometers have a variation curve adapted to the capacitance-voltage curve peculiar to the diodes in order to produce a linear variation in frequency or substantially so as a function of the control. From this it will be understood that in the present selection device, using a plurality of potentiometers, the setting of the channels, as a function of the number of revolutions, will necessitate similar voltage versus control curves for the potentiometers.

Although the possibility is not excluded of depositing a track of graphite or carbon instead of a resistance Wire at the bottom of the threads 203 in the core 200, it appears diflicult, if not expensive, to reproduce faithfully similar tracks with a non-linear variation of voltage'versus control and this is why, in order to obtain correct tuning and with a view to mass-production, a simple solution consisting in replacing the conventional potentiometers by resistors varying linearly as a function of the number of revolutions and connected to the terminals of the source of current by means of a resistor 307 to the terminals of which there is connected the Varicap-diode oscillating circuit, has been adopted in the four diagrams in FIGS. 11 to 14.

The law of variation in the voltage at the terminals of a fixed resistor 307 as a function of the variable voltage across a variable resistor 202 in series is well known and corresponds substantially to the curve of voltage variation which must be applied to Varicap diodes in current use, in order to obtain a linear variation in frequency. The resistor 308 in series with 202 and 307 is a supplementary correction resistor relating to the upper frequency limit of the selected frequency range; the resistors 307 and 308 may advantageously be adjustable. By way of example, the resistor 202 may be approximately equal to four times the resistor 307, the value of 307 being double that of the resistor 308.

As can be seen in the diagram in FIG. 11, the lug 211 does not appear and, in consequence, the three members 201, 207 and 209 previously needed by the selection mechanisms equipped with potentiometers, are not used and are therefore superfluous; the variable- voltage circuit 202, 307, 308 closed through an external source 304 is in series with respect to the resistor 305, shunting the AFC circuit normally connected to earth.

The diagram in FIG. 12, derived from the previous diagram, illustrates by way of example the use of a transformer 309 and of a rectifier 310 (which may be added to all the diagrams) with the object of using a resistance wire, wound on the core 200, which wire, as will be well understood, can only have a resistance of a few hundred ohms which does not permit a sufficient voltage at its terminals to control the present-day Varicap diodes; this is why the step-up transformer 309 is provided, the impedance of the winding 309 in series with the regulating circuit serving the purpose of the resistor 307, 310' is a smoothing capacitor and 304 a source of alternating current.

FIG. 13 illustrates another diagram using all the means described but only using one variable resistor 202; for this purpose, the end of the resistor 202, which has previously been soldered to the collar 12b of the shaft 12n, is electrically insulated; the AFC circuit can be closed through two switches in series enabling another modification of the pushbutton mechanism of the aforesaid patent application to be used as well be seen later.

The last diagram (FIG. 14) is clearly distinguished from the others by the fact that only two switches are used; for this purpose, the tongue 29! is electrically insulated from the ring 29n, its other end being soldered to the disc 207 which no longer has any teeth 208 which are now superfluous, like the cup 201 previously soldered to the variable resistor 202. In fact, the tongue 291 and this new disc without teeth may be made in one piece and bent at right angles as may easily be imagined.

FIGS. 15 and 16 illustrate another embodiment of pushbuttom mechanism, the dimensions of which are adapted to fit into the base parts of the device of the invention and which is therefore interchangeable with the mechanism previously described.

As will be seen, it is a question of the mechanism forming the subject of FIGS. 24, 25 and 26 of the aforesaid patent application, permitting more convenient adjustment as a result of the piston head 418 having a positon emerging from the alignment level of the other pushbuttons when it is pulled after having been engaged.

This mechanism is briefly recalled to mind. The pushbutton proper 1011 is provided with a terminal head 418 and a tubular coaxial cap 411. The pushbutton 10n is drilled axially and can slide freely on the front portion of a shaft 1211, this front portion having a square section as does the axial bore in the pushbutton 10n. Shaft 12n is quite similar to shaft 1211 of FIG. 3a and, like it, it has a stop collar 12b bored at to form a seating adapted to receive core 200. Shaft 1211 is adapted to turn freely inside turret 1911. Head 418 can slide inside cap member 411 without driving it into rotation. Cap member 411 can slide inside barrel 49m and can drive it into rotation. A tubular intermediate member 440 can slide inside barrel 4911. Member 440 has two terminal collars for respectively allowing cap 441 to be pulled in one direction and pushbutton 1011 in the reverse direction.

The pushbutton can take three positions:

( l) A rest position not shown (this position is represented in FIG. 24 of the aforesaid patent application);

(2) An engaged position (FIG. 15). In this position the turret is pushed backwards; intermediate member 440 is pushed to the bottom of the barrel by spring 441. When the pushbutton is released, it, together with head 418, is urged forwardly by spring 441 and head 418 drags along cap 411 by its collar 450. Tongue 49l rubs against intermediate member 440 closing the switch 440/49 which plays the same part as switch /49; and

(3) A control position. The pushbutton being engaged,

head 418 is pulled and responds to this action. The result is that the head 418 serving as tuning means emerges from the level of alignment of the other buttons, consequently permitting more convenient adjustment.

The switch 10/49 of the mechanism in FIGS. 3a and 4a is open in the rest position of FIG. 3a and closed in the engaged position of FIG. 4a and again open in the regulating position of FIG. 4b. It will be seen that the difference between the two mechanisms is that all the switches 440/49 are closed in the rest position whereas all the switches 10/ 49 are open in the same rest position. It will therefore be understood that only the diagrams in FIGS. 12, 13 and 14 can manage with the switch 440/49 in series with the switch 25/81 because of the switch 29/35 which electrically disconnects the tuning circuit from the AFC circuit. Since these same diagrams can likewise use switches 10/49 of the first mechanism described it is possible, in a selection device, to combine the two formulae, and to provide, for example, for one of the pushbuttons, associated with the rapid finding of stations to be in accordance with the modification permitting more convenient adjustment (FIGS. 15 and 16), the other more economical pushbuttons being of the type in FIGS. 3a and 4a.

The various mechanisms as well as the basic wiring diagrams having thus been completely described, the op- 'eration will now be rapidly explained, taking as an ex ample the diagram in FIG. 10 which uses all the means of the present patent application.

When the pushbutton 10 is in the non-engaged position of FIG. 3a, the band and the standard can be selected directly as explained in the aforesaid Patent No. 3,390,581; in this same position, all the switches 29/35, 25/81 and 10/49 are open, the biasing of the Varicap diode is in the normal state corresponding to the setting of the lowest frequency in the frequency range selected and the AFC is disconnected.

In the engaged position of FIG. 4a, as of the pushbutton 10 the tuning and AFC circuits are closed by the corresponding switches, the Varicap diode is then biased in accordance with the channel selected, this bias being the resultant of two voltage sources in series; that of the tuning, previously set up, and that resulting from the frequency discriminator of the AFC. If it is found that the reception of the selected channel is disturbed by a more powerful adjacent channel, the pushbutton 10n is pulled (FIG. 4b) to cut the AFC. Similarly, it should be underlined that there is no risk of deregulation with regard to the pre-regulated channels during the manipulation of the present selector, when the pushbuttons associated with said channels are in the first two positions, these pushbuttons then being coupled to the turret and consequently resiliently coupled to the barrels.

In the above, it has been assumed that the invention would be applied to the case where the tuning of the radio-frequency circuits was effected by Varicap diodes in certain ranges of frequency (VHF) and thetuning was effected through variable capacitors in other ranges of frequency (UHF). The invention would naturally be equally applicable to the case in which all the tuning circuits were controlled by Varicap diodes. The shaft 71 is then stripped of the rotors of variable capacitors, no longer needed, and then serves only for the setting.

What I claim is:

1. Multiple selection pushbutton device for radio equipment and television sets having at least one radiofrequency circuit including a variable capacitance diode,

comprising a frame, a plurality of engageable pushbuttons, each including an actual pushbutton, a control shaft driven in rotation thereby, a helical potentiometer body and a push-rod respectively rigidly and rotatively connected to said control shaft, a plurality of engageable pushbutton mechanisms respectively associated with said pushbuttons, each pushbutton mechanism including means for being engaged with the associated pushbutton and disengaged therefrom and a slider cooperating with said potentiometer body, an interlock bar for locking said pushbutton mechanisms, a plurality of barrels respectively associated with said pushbutton mechanisms and resiliently connected to said frame, a first control bar for tuning said radio-frequency circuits, situated in the path of said push-rods and actuated thereby depending on their length, at least one frequency range switch, a second control bar for selectively controlling said switch,- members of different extension provided on the pushbutton mechanism in different radial directions, the position assumed by said second bar depending on the extension of the member which actuates it and consequently on the angular position of the pushbutton mechanism about its axis, change-over switches controlled by the pushbutton, means for feeding said helical potentiometer through said change-over switches, and means for causing the length of the push-rod and the position of the slide with respect to the body of the potentiometer to vary through rotation of the pushbutton with respect to the pushbutton mechanism, whereby said rotation simultaneously determines the length of the push-rod and the voltage taken off at the slide.

2. Multiple selection pushbutton device for radio equipment and television sets having at least one radiofrequency circuit including a variable capacitance diode and an automatic frequency control circuit, comprising a frame, a plurality of engageable pushbuttons, each including an actual pushbutton, a control shaft driven in rotation by said pushbutton, a helical potentiometer body rigidly connected to said control shaft and a push-rod rotatively connected to said control shaft, a plurality of engageable pushbutton mechanisms respectively associated with said pushbuttons, each pushbutton mechanism including means for being engaged with the associated pushbutton and disengaged therefrom and a slider cooperating with said potentiometer body, an interlock bar for locking said pushbutton mechanisms, a plurality of barrels respectively associated with said pushbutton mechanisms and resiliently connected to said frame, a first control bar for tuning said radio-frequency circuits, situated in the path of said push-rods and actuated thereby depending on their length, at least one frequency range switch, a second control 'bar controlling said frequency range switch, members of different extension provided on the pushbutton mechanism in different radial directions, the position assumed by said second bar depending on the extension of the member which actuates it and consequently on the angular position of the pushbutton mechanism about its axis, a first change-over switch between said push-rod and said frame, a second changeover switch between said actual pushbutton and said barrel, a third change-over switch between said pushbutton mechanism and said interlock bar, a direct current source, means for feeding said helical potentiometer from said current source through said first change-over switch, means for feeding said helical potentiometer from said automatic frequency control circuit through said second change-over switch, means for feeding said variable capacitance diode from said slide through said third change-over switch and means for causing the length of the push-rod and the position of the slide with respect to the potentiometer body to vary through rotation of the pushbutton with respect to the pushbutton mechanism whereby said rotation simultaneously determines the length of the push-rod and the voltage taken off at the slide.

3. Multiple selection pushbutton device according to claim 1 in which the control shaft is drilled and internally threaded, the helical potentiometer body is tubular and coaxial with said control shaft, the push-rod selectively extends through said body and screws into said control shaft and the pushbutton mechanism comprises sliding means for slidably and longitudinally guiding the slider along the potentiometer body, means for preventing the push-rod from rotating and means for limiting the longitudinal course of the slider to an extent smaller than the push-rod extension.

4. Multiple selection pushbutton device according to claim 1 in which the barrels respectively associated with the pushbutton mechanisms comprise internal spring conductive blades and the engageable pushbuttons comprise external extension conductive members cooperating with said spring conductive blades to form a change-over switch.

5. Multiple selection pushbutton device for radio equipment and television sets having at least one radiofrequency circuit including a variable capacitance diode and an automatic frequency control circuit, comprising a frame, a plurality of engageable pushbuttons, each including an actual pushbutton, a control shaft driven in rotation by said pushbutton, a helical potentiometer body having an externally threaded cylindrical core and a resistance Wire located at the bottom of the threads, rigidly connected to said control shaft and a push-rod rotatively connected to said control shaft, a plurality of engageable pushbutton mechanisms respectively associated with said push-buttons, each pushbutton mechanism including means for being engaged with the associated pushbutton and disengaged therefrom, sliding means and a slider in the form of a spider having two perpendicular arms, the first located in potentiometer body threads, the second sliding in said sliding means, an interlock bar for locking said pushbutton mechanisms, a plurality of barrels respectively associated with said pushbutton mechanisms and resiliently connected to said frame, a first control bar for tuning said radio-frequency circuits, situated in the path of said push-rods and actuated thereby depending on their length, at least one frequency range switch, a second control bar controlling said frequency range switch, members of different extension provided on the pushbutton mechanism in different radial directions, the position assumed by said second bar depending on the extension of the member which actuates it and consequently on the angular position of the pushbutton mechanism about its axis, a first change-over switch between said push-rod and said frame, a second change-over switch between said actual pushbutton and said barrel, a third change-over switch between said pushbutton mechanism and said interlock bar, a direct current source, means for feeding said helical potentiometer from said current source through said first change-over switch, means for feeding said helical potentiometer from said automatic frequency control circuit through said second change-over switch, means for feeding said variable capacitance diode from said slide through said third change-over switch and means for causing the length of the push-rod and the position of the slide with respect to the potentiometer body to vary through rotation of the pushbutton With respect to the pushbutton mechanism whereby said rotation simultaneously determines the length of the push-rod and the voltage taken off at the slide.

References Cited UNITED STATES PATENTS 9/1953 Miller 334-7 X 5/1966 Kazyk et a1. 334-7 X US. Cl. X.R.

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