US2224332A - Pickup arm construction for phonographs - Google Patents

Description

Dec. '10, 1940." B. N. ALSBROOK, JR 2,224,332

' PICKUP ARM CONSTRUCTION FOR PHONOGRAPI 'I S Filed-April 22, 1940 mam Mi B/sHoP/zm same/gm:

Patented Dec. 10, 1940 UNITED v STATES mm ARM CONSTBUCTiON ron PHONOGRAPHS Bishop N. Alsbrook, In, El Campo, Tex. Application April 22, 1940, Serial No'. 331,031

'ZClaims.

This invention relates to pickup arm constructions for phonographs, and more particularly to such constructions which are particularly adapted for use in connection with portable phonographs or phonographs installed or carried in automobiles or other places where they may be subjected tojolts or suddenmovements during their operation, although my invention may also be advantageously applied to other phonographs or sound recording or reproducing machines.

Theprimary objects of the invention are: to provide an arm or mounting means for the sound pick-up unit of a phonograph which serves to at all times during operation maintain the needle of said unit in operative engagement in the'groove of the record regardless of jolts or sudden movements of the phonograph which might tend to jar the needle out of the record groove; to provide in connection with such an arm novel simple means for adjusting the same to maintain the needle or stylus of the pickup device in engagement with the record at any desired degree of pressure; and to provide such a pickup arm construction which is of simple economical construction and operation, and which may be of very light weight if desired to reduce the moment of inertia at the free end of the-pickup arm.

In this application I show and describe only the preferred embodiment of my invention simply vention, as by aw required. However, I recognize that my invention is capable of other and different embodiments, and that the various details thereof may be modified in various ways, all without departing from my said invention; therefore the drawing and description herein are to be considered as merely illustrative and not as exclusive.

In the accompanying drawing:

Figure 1 represents a perspective view of a pickup arm construction embodying my invention;

Figure 2; a side elevation partly in section, of the device illustrated in Figure 1 with the pickup 5 unit in engagement with a record;

Figure 3, a section on the line 3-3 of Figure 2, looking in the direction of the arrows; and,

Figure 4, a fragmentary top plan view of the preferred embodiment of. my invention.

lustrated in the accompanying drawing broadly comprises a resilient pickup arm or member, a sound pickup unit carried at the free end of said arm in any suitable fashion, preferably being dis- 55 posed in a suitable housing or casing,and suit:

by way of illustration of thepractice of my in-e The preferred embodiment of my invention ilable means for mounting said arm for swinging movement in a plane parallel to the surface of a record, with the needle of the pickup unit maintained in resilient engagement with the record by the resilient downward pressure of said arm. ,5 Also the preferred embodiment of my invention comprises means for adjusting the arm of the pickup arm construction to obtain the desired pressure of the needle on the record, though this feature is not essential to my invention considered from its broader aspects.

The preferred form of pickup arm I illustrated in the accompanying drawing consists of a preferably flat downwardly curved leaf spring or spring steel or other suitable resilient material member. In the form illustrated the arm I is formed with a narrow tip or free end portion 2' to extend into the casing of housing 3 for the pickup unit D, said casing 3 being rigidly attached to arm I by suitable means such as a bolt 4 passing through the overlapping portions of the casing toprpanel 5 and the tip 2 of arm i.

However, said casing 3 merely constitutes one convenient and attractive means which may be employed for mounting or carrying the sound pickup device or unit D at the free end of arm I and may be modified or dispensed with if desired.

The particular form of casing 3 illustrated con- 1 sists simply of a channeled or inverted U-shaped cross-section member, preferably formed from a single integral piece of aluminum or other preferably extremely light material having a fiat top panel 5 and downwardly depending spaced sides or side panels 5 covering the respective top and side portions of the sound pickup unit D disposed therein. If desired the top panel 5 of the casing may bev formed with an aperture I to permit inspection of the electrical connections or terminals of the wires G at the rear end of thepickup unit D.

The pickup device or unit D, preferably dis- 40 posed in the casing 3 at the free-end of pickup arm I, may be of any usual type of preferably light weight preferably electrical pickup device or unit having the usual. downwardly directed needle or stylus E adapted to engage in the sound groove of a record 13 disposed on the usual phonograph'turn table C, said needle E being retained in position by the usual fastening screw F.

For the purpose of fastening the pickup unit 60' D in casing 3, I prefer to employ screws 9 and Ill threaded through the sides or side panels 6 of said casing into suitable receiving sockets (not shown) formed in the pickup unit D.

Whenthe pickup device D is of the electrical type illustrated, the usual wires Gconducting electric current to and from the unit D may, if

desired, be disposed and concealed beneath the arm I by running them through a clip or eyelet 8 secured to the lower face of arm I.

Although the mounting means for the pickup arm I may be of any type permitting free swinging movement of said arm in a lateral plane, or a plane parallel to the surface of record B, while in normal operation preventing vertical swinging movement (as distinguished from resilient I bending in a vertical direction) of the arm I,

the preferred mounting means illustrated embodies in its construction a new and useful feature of my invention consisting of means for adjusting the arm I so as to obtain any desired resilient pressure of theneedle E on record B.

Accordingly, the preferred form of mounting means for arm I, as illustrated in the accompanying drawing, comprises a rotary plate or bracket II mounted for rotation in a lateral plane preferably by means of an integral perpendicular downwardly depending pivot or pin I2 freely rotatably journalled in the vertical bore I8 of a suitable stationary base I! fixedly secured by screws ll or other suitable means to the motor boardor top panel A of the phonograph adjacent the turn table B. Vertical motion of the bracket II may be prevented by disposing the same in free rotating engagement with the upper portion of base I3 and by means of an enlargement or head ii at the lower end of pivot pin l2 disposed in freely rotating engagement with the base I 3 at the lower end of bore I8.

- end portions or abutments or shoulders I! and raised relatively spaced lugs or dogs ll projecting upwardly from the opposed sides of each said shoulder I I, the end portion or pivoted end of 40 pickup arm I resting on and extending between said raised shoulders I I, and being disposed and positioned between the .lugs I8 of each shoulder,

whereby said lugs I8 serve to prevent relative rotation between the arm I and-plate or bracket 45 I I. The lugs- I 8 however are not essential and may be omitted if desired.

Cooperating with the bracket II,'as thus far described, are suitable means for maintaining the arm I and bracket II in properly assembled relation and for exerting an adjustable downward pressure on the arm I at some point between the two spacedribs or shoulders II on which the pivoted end of arm I rests, for the purpose of raising or lowering the free end of arm I-and thereby 55 regulating the resilient pressure of needle E on record B. v

The means illustrated consists of an upwardly projecting screw-threaded pin or member I! disposedon the upper face of bracket II medially 00 between the shoulders I! thereof, and passing through an aperture in the adjacent pivoted end of arm I, to receive at itsupper end a wing nut 2|! which may. be screwed or turned down to exert any desired degree of pressure on the arm 65 I. If desired, and as shown, a washer or sleeve 2I and a pressure distributing member22 may be interposed about pin I9 between the nut 20 and arm I, the member 22 serving to distributev the pressure evenly across the entire width of 7 arm I and being prevented from rotation relative Thebracket II is provided with spaced raised the nut 20 on arm I increases, the free -end of the arm I tends to rise, thereby decreasing the pressure of the needle E on the record B, and as the pressure exerted by nut 20 decreases, the free end of arm I tends to descend or press against the record with an increasing pressure.

It is to, be noted of course,-that'in order to function as above described, the arm I is so positioned and adjusted that, in the absence of the record B the point of needle E would normally be resilientlypositioned or supported by ml at a plane or level somewhat. below the surface of the record thus when the needlepoint is placed in operative engagement with the record the resilient arm I by- -its tendency to move towards or regain such normal position resiliently presses and maintains the needle E in eng'agement with record B and may be adjusted to prevent said needle from jumping or being'jarred out of the record groove when the phonograph is subjected to such shocks or-jolts as would ordinarily be encountered during transportation of the phonograph in an automobile or other vehicle. In fact it has been found'that in oper ation the preferred embodiment of my invention herein described will maintain the needle E in operative engagement with the, record B even @though the phonograph is played in an'upside down position.

Obviously when it is desired to remove or change the record, the resiliency of arm I per? mits the needle E to be lifted outof engagement with the record whereupon the arm may be swung laterally off of the record without changing the setting of the pressureadjusting nut 20. 35

'The hereinbefore mentioned-light weight of the pickup unit D and easing 3, in accordance with the preferred construction of the invention, serves to increase the efiiciency thereof in that it reduces the moment of inertia at the free end of said pickup arm I, thereby reducing the tendency of the needle E to bounce out of the record groove when jolted, and accordingly requiring less pressure of the needle E on the record than would otherwise be the case.

It is to be noted that, in addition to its other advantageamy invention is particularly adapted for use with records which have become warped due to heat or other causes, as it will permit the needle to move up or down in engagement with the high or low portions of the record, while at the same time maintaining a substantially constant pressure between'the record and needle and preventing the needle from bouncing out of its groove.

I claim:

1. A pickup arm construction for phonographs comprising a stationary base, a pickup arm mounting and adjusting bracket mounted on said base for swinging movement in a lateral plane, a pair of raised opposed spaced shoulders formed atthe respective opposed end portions of said bracket, and a resilient pickup arm mounted on said bracket for swinging movement in a lateral plane and having one end portion of said am resting on and extending between said shoulders said end portion being formed with an aperture extending therethrough and the free end of said arm being adapted to carry a sound pickup unit, in combination with means for exerting a variable degree of downward pressure on the portion of said arm extending between said bracket shoulders to vary the pressure of the pickup unit needle on a record, said means comprising an 7 upwardly projecting screw-threaded member secured to the medial portion of said bracket and passing upwardly through said aperture formed in the pick-up arm, and a nut threaded on the upper end or said member to be screwed down to exert any desired degree of pressure on said pickup arm.

2. A pickup arm construction for phonographs a comprising a mounting and adjusting bracket mounted for swinging movement in a lateral plane, a pair of raised opposed laterally spaced shoulders formed on said bracket, and a resiliently vertically bendable pickup arm mounted on and having its end portion extending between said shoulders, said end portion havingan aperture disposed therethrough the free end of said arm being adapted to carry a sound pickup unit, in combination with means for exerting a variable degree of downward pressure on the portion of said arm extending between said bracket shoulders to vary the pressure of the pickup unit on a record, said means comprising an upwardly projecting screw-threaded member secured to the medial portion of said bracket and passing upwardly through said aperture in the pickup arm, and a nut threaded on the upper end or said member. I

3. A pickup arm construction for phonographs comprising a mounting and adjusting bracket disposed for swinging movement in a lateral plane, a pair or raised opposed laterally spaced shoulders formed on said bracket, a resiliently vertically bendable pickup arm having one end portion disposed across said shoulders and formed with an aperture therethrough, the other end being adapted to carry a sound pickup unit. in operative engagement with a record, in combination with means for varying the pressure or said pickup unit on the record comprising a screw- 40 threaded member secured to said bracket and passing upwardly through the aperture formed in said arm, and a nut threaded on said member above said arm. a I

4. A pickup arm construction for phonographs 5 comprising a mounting and adjusting bracket disposed for swinging movement in a lateral plane, a pair or raised opposed laterally spaced shoulders formed on said bracket, and a resiliently vertically bendable pickup arm having its end portion disposed across said shoulders, its

. other end being adapted to carry a sound pickup unit in operative engagement with a record, in combination with means for exerting a variable degree of downward pressure on said arm between said bracket shoulders to vary the pressure of the pickup unit on a record.

5. Mounting and adjusting means for a resilient pickup arm comprising a stationary base, a mounting and adjusting bracket mounted on said base for swinging movement in a lateral plane, and laterally spaced shoulders formed on said bracket and adapted to'have the pickup arm extending thereacross, in combination with means carried by said bracket for exerting a variable amount or downward pressure on the portion of the pickup arm extending across said shoulders, comprising an upwardly disposed screw-threaded member secured to said bracket to extend above said pickup arm, and a nut threaded on said member to be turned into engagement with said pickup arm.

6. Mounting and adjusting means for a resilient pickup arm comprising a stationary'base, a mounting andadjusting bracket mounted on said base for swinging movement in a lateral plane,

andlaterally spaced shoulders formed on said bracket and adapted to have the pickup arm ex tending thereacross, in combination with means carried by said bracket for exerting a variable amount of downward pressure on the portion of portion or said pickup arm extending betweensaid shoulders.

BIBH OP Jil-

Images