US2413206A

US2413206A - Pickup arm

Info

Publication number: US2413206A
Application number: US510809A
Authority: US
Inventors: Arthur F Worsham
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-11-18
Filing date: 1943-11-18
Publication date: 1946-12-24
Anticipated expiration: 1963-12-24

Description

Dec. 24, 1946. l` A. F.1wosHAM 2,4115205 PICK-UP ARM Filed Nov. 18, 1943 2 Sheets-Sheet 1 as 25 J I\\\\\ ec. 24, 1946. A. F. WORSHAM PICK-UP ARM Filed Nov. 18, 1945 2 Sheets-Sheet 2 Ummm lla.

Patented Dec. 24, 1946 UNITED STATES PATENT (`)}'-`FICIE`.

PICKUP ARM Arthur F. Worsham, Phoenix, Ariz.

Application November 18, 1943, Serial No. 510,809

2 Claims. (Cl. 179-100.41)

This invention relates to a pickup arm for phonographs and similar devices, and has for the primary object the provision of a device of this character which will provide zero tracking of the sound grooves of a record, that is the needle or stylus of the pickup arm wil1 be maintained tangent to .the sound grooves for the entire movement of the pickup head across the record and thereby eliminate tracking errors which occur by the use of the conventional swingable type of tone or pickup arm.

With these and other objects in view as will become more apparent as the description proceeds, the invention consists in certain novel features of construction, combination and arrangement of parts as Will be hereinafter more fully described and claimed.

For a complete understanding of my invention, reference is to be had to the following description and accompanying drawings, in which lFigure 1 is a top plan view illustrating a pickup arm and pickup head constructed in accordance with my invention and showing the pickup arm and head associated with av record on a turntable of a phonograph or similar device.

Figure 2 is a side elevation illustrating the same.

Figure 3 is a vertical sectional view illustrating the pickup arm and pickup head carried thereby and the mounting for the pickup arm.

Figure 4 is a fragmentry vertical sectional View illustrating the pickup arm in an inoperative position.

Figure 5 is a transverse sectional view taken on the line 5-5 of Figure 3.

Figure 6 is a fragmentary sectional view taken on the lin 6-6 of Figure 3.

Figure 7 is a view similar to Figure 6 with the pickup arm removed.

Referring in detail to the drawings, the numeral 5 indicates a fragmentary portion of a case or cabinet of a phonograph Aor similar device and 5 the turntable on which the record 'I is arranged for rotation. The record is in disc form with the sound grooves disposed uppermost. It `Vis customary in phonograph construction to provide a, pickup arm mounted on the case or cabinet for swinging movement relative to the turntable so that a record may be placed on and removed from the turntable and also whereby the stylus of the pickup arm may track in the sound grooves. vA pickup arm of this character produces tracking errors, and in order to have zero tracking of the sound grooves by the stylus the stylus at all times at its point of contact with the sound grooves must be tangent to the oncoming groove and which cannot be accomplished by a swingable pickup arm of the character mentioned, consequently resulting in tracking errors.

It is the purpose of the present invention to eliminate the tracking errors and to produce zero tracking by maintaining the point of contact of the stylus or needle tangent to the sound grooves entirely across the record.

In the present invention the pickup arm is designated by the character 8 and is mounted horizontally so as to traverse the record as shown in Figures 1 to 3, inclusive, of the drawings. The pickup arm 8 is of inverted channel formation and has mounted therein a track assembly 9 including upper and lower spaced insulating plates I0 detachably connected together by bolts II which also pass through the pickup arm or the top wall thereof. Angle iron rails I2 of conductive material are secured to the opposing faces 0f the plates I0 to be engaged by rollers I3 and I4 of a pickup head I5. The pickup head I5 is of the electrical type and the rollers thereof are arranged in upper and lower pairs to engage the upper and lower rails. The upper and lower rollers are insulated from each other. The needle or stylus of the pickup head is indicated by the character IB and operates through a slot I I provided in the lower plate l0 to engage in the sound grooves of the record 1.

Conductors I8 electrically connect the rollers to the stylus and the rails have electrical conductors I9 connected thereto which are in turn connected to the usual electrical amplifier of the phonograph or similar device (not shown).

The pickup head I5 is free to move endwise of the pickup arm and its movement is checked by a cushion block 20 carried by combined fulcrum and stop arm 2| when the pickup arm is moved into inoperative position, as shown in Figure 4. The combined fulcrum and stop arm is arranged horizontally within one end portion of the pickup arm and is pinned to a supporting shaft 23 journaled in a sleeve 24 and is also capable of having sliding movement in said sleeve.

The sleeve 24 has a screw threaded portion 25 to extend through an opening provided in the case or cabinet 5 and has threaded thereon a retaining nut 26. The screw threaded portion 25 is slightly reduced in diameter over the remaining portion of the sleeve so as to form a shoulder to cooperate with the nut 2S in securing the sleeve in place. A coil spring 21 surrounds the lower end portion of the shaft 23 and bears against the lower end of the screw threaded portion 25 of nel formation and is arranged horizontally and is provided with a slot 33 opening through one end thereof. The slot permits the supporting plate to straddle the sleeve with portions thereof tting in a groove provided in the sleeve. If desired, the supporting plate after being assembled on the sleeve as speciiied may be welded or otherwise secured thereto. The hinge member 30 connecting the pickup arm to the supporting. y

plate 32 as specified, will permit said pickup arm to be swung upwardly fulcruming on the combined fulcrum and stop arm 2|, as shown in Figure 4, so that the pickup arm will be clear of the turntable whereby a record may be removed and another placed thereon without interference from the pickup arm. When the pickup arm assumes an inoperative position, the pickup head slides in engagement with the cushion 20, repositioning the pickup head for the playing of the next record. The pickup head is caused to travel to the right of the pickup arm during the engagement of the stylus with the sound grooves, vthe point of contact between the stylus, and the sound grooves being tangent to the sound grooves thereby providingzero tracking.

While I have shown and described the preferred embodiment of my invention, it will be understood that minor changes in construction, combination and arrangement of parts may be made without departing from the spirit and scope of the invention claimed. v

Having thus described the invention, what I claim is:

1. In a pickup device, a pickup arm arranged horizontally and traversing a horizontally arranged record, a track assembly carried by said pickup arm and providing electrical conductors, means electrically connecting the track assembly to a sound amplifier, an electrical type pickup head slidably supported by the track assembly and including a stylus to engage the sound grooves and having its point of contact with the the sound grooves maintained tangentially thereto by the pickuparm', a combined fulcrum and stop, a cushion carried by the combined fulcrum and stop to be engaged by an endwise movement of the pickup head, a shaft secured to the combined fulcrum and stop, a sleeve receiving said shaft and secured to a support adjacent the record with the shaft slidable therein, tension means between the sleeve and the shaft, and a hinge connection between the pickup arm and the sleeve.

2. In a pickup device, a pickup arm arranged horizontally and 'traversing a horizontally arranged record, a track assembly carried by said pickup arm and providing electrical conductors, means electrically connecting the track assembly to a sound ampliiier, an electrical type pickup head slidably supported by the trackassembly and including a stylus to engage the sound grooves and having its point of contact with the sound grooves maintained vtangentially thereto by the pickup arm, a combined fulcrum and stop, a cushion carried by the combined fulcrumand stop to be engaged lby an endwise movement-'of the pickup head, a shaft' secured to th'e combined fulcrum andv stop, a"sleeve receiving "said shaft and secured to a support adjacent 'the record with the shaft slidable therein, tension means between the sleeve and shaft, a supporting plate secured to the'sleeve and arranged horizontally and having notches, a hinge "element pivoted to the pickup arm and received by the notches and straddllng the shaft.

' ARTHUR F. WORSHAM.