US2348660A - Phonograph - Google Patents

Description

I. L. STEPHAN May 9, 1944.

PHONOGRAPH 2 Sheets-Sheet 1 Filed Dec. 19, 1940 i:-: ii

y 1944. L. STEPHAN 2,348,660

PHONOGRAPH Filed Dec. 19, 1940 2 Sheets-Sheet2 "Patented May 9, 1944 2,348,660 rnoNoGnaArH Ingo L. Stephan, Delanco, N. J assignor to Philco Radio and Television Corporation, Philadelphia, Pa., a corporation of Delaware Application December 19, 1940, Serial No. 370,865

8 Claims. (Cl. 179-100.41)

This invention relates to phonograph pickup devices generally and in particular to those employing an electro-optical system for translating the undulations of a sound record into electrical currents.

The principal-object of the. invention is to provide a novel device of simple construction and embodying certain desirable features hereinafter described.

Another object of the invention is to provide a novel phonograph pickup construction in which the stylus is retractably mounted in cooperative relation with guard means to protect the stylus against abusive or damaging forces.

A further object of the invention is to provide a novel and distinctive mounting for the stylus of a phonograph pickup device.

Still another object of the invention is to provide a novel mounting for both the stylus and the light-sensitive cell unit of an electro-optical phonograph pickup device.

Other objects and features of the inventionwill appear hereinafter.

In the accompanying drawings,

Fig. 1 is a fragmentary plan view of a tone arm embodying the novel pickup device, shown in cooperative relation with a sound record;

Fig. 2 is a plan view of the pickup head, with cover removed, upon which the electro-optical translating system is mounted;

Fig. 3 is an elevational view of the same with a portion of the supporting base broken away for clarity of illustration;

Fig. 4 is a sectional view taken along the line t-4 of Fig. 2;

Fig. 5 is a sectional view taken along line 5-5 of Fig. 2; and

Fig. 6 is a perspective view of the supporting base and cantilever mounting structure.

Referring to Fig. 1, there is shown a. tone arm i which is adapted to be pivotally mounted at one end (not shown) in the usual manner in order that the tone arm may move horizontally and vertically with respect to a sound record 2, as will be well understood. At its free end, the tone arm carries a pickup head 3 comprising a sheet metal supporting base 4 carrying the parts described hereinafter, and a removable cover 5. The tone arm I is preferably of inverted channel formation and has formed integrally therewith an interior rib 6 to which the base 4 may be removably secured by means of a nut I and screw 6, the base i being integrally joined with the nut l by welding or in any other suitable manner, as shown in Figs. 2 and 6. The details of the mounting of the pickup head on the tone arm are relatively unimportant, however, it being understood that any suitable mounting or attachment of the head to the tone arm may be utilized.

Referring now to Figs. 2 to 4, an L-shaped bracket 9is adjustably mounted on the supporting base 4 by means of the slot iii in the said bracket and the screw l l which engages. a threaded opening I2 in the supporting base. The bracket 9 serves to support a lamp socket i3 which is resiliently mounted on the upstanding portion 01' bracket 9 by means of rubber washers i4 and 15. The lamp i6 carried by socket I3 constitutes the light source for the electro-optical translating system. The end of the lamp socket or housing adjacent the lamp is preferably flared as at i! to serve as a reflector for the lamp. In order to obtain the maximum output from the pickup the lamp I5 and the reflector ll should be of such type that light from the lamp is focused into a beam directed onto the light-sensitive cell unit in the pickup. The lamp may be energized with either a, direct current or a high frequency alternating current such that hum resulting from lamp flicker would be inaudible.

The other elements of the electro-optical translating system, comprising the light-sensitive cell unit l8 and the light-controlling stylus member iii, are mounted upon a common supporting structure now to be described. An elongated wire-like element 20, which is substantially rigid but capable of slight deflection, is secured at one end to the supporting base i, as shown at 2i. (See Figs. 4 and 6.) Adjacent its said end, the element 2!! is surrounded and gripped by a resilient sleeve or covering 22, which may be formed of rubber, which, in turn, is seated upon several fiat metallic strips 23 which serve to support the element 20 above the base 4. Interdentate clamping elements 24 and 25 are turned upward from the sheet metal base 4 and encircle the resilient sleeve 22 so as to firmly clamp the same. In this manner, the end portion of element 20 is securely but resiliently anchored.

The element 20 is secured only at one end, as above described, and is free to flex in a vertical plane, and, therefore, this element constitutes a cantilever. At its free end portion which extends through a slot 26 in the end flange 21 of the supporting base, the element 20 is surrounded by a second resilient cushioning sleeve 28. This sleeve fits snugly within the slot 26 so that the element 20 is effectively prevented from swinging horizontally but movement thereof vertically upward is not restricted at all.

'I'he light-sensitive cell assembly (see Figs. 2 and 4) comprises a sheet metal angle bracket or support 29 having a horizontal portion 30 secured to element by means of spaced resilient mountings. To this end, element 20 carries spaced resilient sleeves 3i and 32 which encircle but do not grip element 20. These sleeves may be formed of rubber, and clamp elements 33 and 34 are turned from portion of the metallic bracket to encircle the resilient sleeves. In this manner, the bracket 29 is mounted upon element 20.

The vertical portion 35 of bracket 29 constitutes a backing plate for the light-sensitive cell assembly. A channel-shaped member 36 (see Fig. 2) having outwardly-extending side flanges 31 is secured to the backing plate 35 by the turned vertical edge portions 38 of the said plate which engage the flanges 31. Within the channel-shaped member 36, there is disposed a selenium element 39 constituting the light-sensitive element of the device. An insulating strip 40 is interposed between the front Wall of the enclosure 36 and the selenium element 39. A contact strip 4! is secured to the insulating strip at 42 and extends between the insulating strip and the selenium element making firm contact with the front face of the latter. A second contact strip 43 engages the rear face of the lightsensitive element and is held in firm contact therewith by a resilient insulating strip 44 of rubber or the like. Tabs 45 turned inwardly from the enclosure 36 engage the rear face of the resilient strip 44 and serve to maintain the enclosed elements firmly in place. Conductor 46 and 41 are connected to the electrode elements 4| and 43, respectively, and, in the use of the device, these external conductors will be conwith a vertical elongated slot 48 (see Fig. 5)

forming a light-admission window in proximity to the lamp I6. In order that the light admitted by the said slot may impinge on the lightsensitive element 39, the insulating strip 40 is provided with a similar slot and the contact strip 4| is arranged so that it does not interfere with the light transmission.

The light-controlling member l9, above referred to, comprises a. flat metallic strip 49 (see Fig. 5) disposed adjacent the window 48 and constituting a light-controlling means, and a stylus 50 attached to strip 49. The integral member It thus formed is secured to the wirelike member 20 at a point between the mountings 33 and 34 for the light-sensitive cell assembly, as shown in Fig. 4. Preferably, the member 20 extends through an aperture in the member I9 and the latter is rigidly secured to the wire-like member. An opening 5| ,in the light-sensitive cell support 29 permits the light-controlling member 19 to extend upward therethrough, as may be seen in Figs. 4 and 5.

Normally, the light-controlling element I 9 is disposed as illustrated in Fig. 5 and covers a portion of the window 48 so as to intercept a portion of the light beam impinging on the said window from the light source it. The stylus 50 is adapted to engage the grooves of a record to be reproduced and the undulations in the record grooves cause the member 19 to oscillate about the axis of the wire-like element 20 By virtue of the resilience of sleeve 22 and since the said element 20 is capable of slight torsional denected to a suitable vacuum tube amplifier for.

amplifying the sound currents before supplying flection, the small oscillatory movement of the member 19 is freely permitted but at the same time, the elements 22 and 20 tend to restore the member l9 to its normal position.

In order to resist rotational movement of the light-sensitive cell assembly about the axis of element 20, there is Provided a flat metallic spring element 52 (see Figs. 2 and 3) secured at one end to a mounting block 53 on the supporting base 4 and attached at its other end to the cell support 29 by means of screw 54. This spring element 52 is disposed at one side of the head, as shown in Fig. 2, and it efiectively maintains the light-sensitive cell assembly stationary while the light-controlling member is oscillating as above described, yet member 52 may also be deflected vertically upward as will be noted again hereinafter. The oscillatory movement of the light-controlling member l9 relative to the slot 48 varies the exposed area of window 48 and thus varies the light admitted to the light-sensitive element in accordance with the recorded sound. Consequently, the light-sensitive eiement generates electrical currents in conductors 46 and 41, which currents vary in accordance with the recorded sound, as will be well understood.

As mentioned above, the stylus element is retractably mounted by means of the resilient wire like member 20 in order to protect the stylus against damaging forces. To this end, the support plate 4 is bulged downward in the vicinity of the stylus to provide a guard portion 55 having an aperture 56 therein to accommodate the stylus 50. If the pickup is subjected to abuse. for example if it is dropped, the stylus is enabled to recede Within the guard 55 by virtue of the resilient cantilever member 20. When this occurs, member 20 flexes about its stationary mounting 2|, the free end of the said member moving vertically in slot 26. Since the lightsensitive cell assembly is mounted on the cantilever member 20, it too moves whenever the cantilever support member flexes in response to pressure on the stylus, and the member 52 will also be deflected sufliciently to permit movement of the cell assembly by an amount sufl'icient to protect the stylus.

From the foregoing description, it will be seen that the invention provides novel structural features in a phonograph pickup device. In particular, it will be seen that the invention provides a novel mounting for the stylus and the light cell unit having the advantages above set forth.

While a specific form of the device has been illustrated and described for the purpose of disclosure, it will be understood that the invention is not limited to the specific details thereof but is capable of various modifications and changes I claim:

1. In a phonograph pickup device, a tone arm, a light source mounted thereon, a light-sensitive cell unit, a light-controlling member including a vibratory stylus, mounting means for said cell unit and said member comprising a single semiresilient cantilever mounting permitting transverse vibratory movement of said member with respect to said cell unit in response to lateral undulations of a record groove, and guide means for the free portion of said cantilever mounting adapted to prevent lateral deflection thereof while permitting vertical deflection, whereby said pickup is responsive to a lateral recording and said stylus is enabled to recede whenever subjectedjto any abusive forces.

2. Ina phonograph pickup device, a tone arm,

a light source mounted thereon, a support member capable of slight bending and torsional deflection, means for securing said member at one portion thereof to said tone arm to provide a cantilever mounting, means for retaining the free part of said member against horizontal movement but permitting torsional deflection and vertical movement of said part, a light-sensitive cell unit, means for so mounting said cell unit on said member that the cell unit moves vertically with said member but is substantially unaffected by torsional deflection of said member, and a vibratory stylus mounted on the free part of said member for oscillatory transverse movement within the torsional deflection range of said member, said stylus being adapted to respond to lateral undulations in a record and being e'nabled by its mounting to recede vertically whenever subjected to any abusive force.

3. In a phonograph pickup device, a tone arm a light source mounted thereon, a light-sensitive cell unit, a light-controlling member including a vibratory stylus, mounting means for said cell unit and said member comprising a semi-resilient cantilever mounting permitting transverse vibratory movement of said member with respect to said cell unit in response to lateral undulations of a record groove, and means for retaining the free portion of said cantilever mounting against horizontal movement but permitting torsional deflection and vertical movement thereof, whereby said pickup is responsive to a lateral recording and said stylus is enabled to recede whenever subjected to any abusive forces.

4. In a phonograph pickup device, a tone arm, a light source mounted thereon, cantilever support means on said tone arm capable of bending and torsional deflection, a light-sensitive cell unit mounted on said support means so as to be movable therewith during bending of said means but substantially unaffected by torsional deflection of said means, a light-controlling member mounted on said support means so as to be movable therewith during both bending and torsional deflection 01 the support means, and a stylus arranged to torsionally deflect said support means in response to lateral undulations o! a record groove, whereby said light-controlling member is moved relative to said cell unit only in response to torsional deflection of said support means.

5. In a phonograph pickup device, a tone arm, a light source mounted thereon, a cantilever support member on said tone arm capable of bending and torsional deflection, a light-sensitive cell unit carried by said member, means for substantially preventing rotary movement of said cell unit when said member is torsionally deflected but permitting movement of the cell unit when said member bends, a light-controlling member mounted on said support member so as to be movable therewith during both bending and torsional deflection of the support member, and a stylus arranged to torsionally deflect said support member in response to lateral undulations of a record groove, whereby said light-controlling member is moved relative to said cell unit only in response to torsional deflection of said support member.

6. In a phonograph pickup device, a light source, a light-sensitive cell unit arranged cooperatively with said light source, a light-controlling member arranged to control the light im pinging on said cell unit, a stylus capable of lateral and other movement, and means operable by said stylus to effect relative movement between said light-controlling member and said cell unit in response to lateral movement of the stylus in a record groove, and to substantially prevent such relative movement in response to other movement of the stylus, whereby said cell unit is activated only in accordance with lateral undulations of the record groove.

7. In a phonograph pickup device, a tone arm, cantilever support means on said tone arm capable of bending and torsional deflection, means for producing electrical current undulations in' response to lateral undulations of a record groove, said last-named means including an element mounted on said support means so as to be movable therewith during bending of said support means but substantially unaffected by torsional deflection of said support means, a second element mounted on said support means so as to be movable therewith during both bending and torsional deflection of the support means, and a stylus arranged to torsionally deflect said support means in response to lateral undulations of a record groove, whereby said second element is moved relative to said first element only in respouse to torsional deflection of said support means.

8. In a phonograph pickup device, a tone am a plurality of relatively movable elements whicl by their relative movement produce electrical cur: rent undulations, a stylus capable of movement in a plurality of senses or directions, a common movable support means for said elements carried by said tone arm and arranged for actuation by said stylus, whereby said elements tend to move in unison during movement of. the stylus, and means for substantially preventing movement of one of said elements in response to movement of the stylus in one sense, whereby relative movement between said elements is effected only during movement of the stylus in said one sense.

INGO L. STEPHAN.

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