US3817538A - Brush for phonograph pick-up apparatus - Google Patents

Abstract

A brush assembly mounted on the pick-up apparatus or tone arm of a phonograph is provided for cleaning a phonograph disc. The brush bristles are connected to a brush-mounting bracket and in the preferred embodiment are grouped together in any suitable configuration, such as a substantially rectangular crosssectional shape. The bristles are substantially parallel with respect to one another. In operative position, the bristles are oriented toward and angled toward the center of the disc, to offset the skating force caused by the brush contacting the record grooves. The longitudinal axis of the cross section of the group of brush bristles is oriented at an acute angle away from the direction of movement of the disc grooves at the point of contact between the brush and the groove to continuously sweep dust particulate on the phonograph disc toward the center of the record without contacting the stylus.

Description

United States Patent [191 Jenrick BRUSH FOR PHONOGRAPH PICK-UP APPARATUS [75] Inventor: Paul W. Jenrick, Mount Prospect,

Ill.

[73] Assignee: Shure Brothers, Inc., Evanston, Ill.

[22] Filed: Mar. 9, 1973 [21] Appl. No.: 339,961

[52] US. Cl. 274/47 [51] Int. Cl. Gllb 3/58 [58] Field of Search 274/47; 15/160, 210 R [56] References Cited UNITED STATES PATENTS 1,459,549 6/1923 ODonnell, Jr. 274/47. 2,259,275 10/1941 Stone, Jr 274/47 3,421,171 1/1969 Tsuruzawa l5/l59A 3,572,725 3/1971 Murphy 274/47 FOREIGN PATENTS OR APPLICATIONS 5/1921 Great Britain 274/47 1 June 18, 1974 Primary Examiner-Harry N. l-laroian Assistant ExaminerJohn W. Shepperd Attorney, Agent, or Firm-Molinare, Allegretti, Newitt & Witcoff [57] ABSTRACT A brush assembly mounted on the pick-up apparatus or tone arm of a phonograph is provided for cleaning a phonograph disc. The brush bristles are connected to a brush-mounting bracket and in the preferred embodiment are grouped together in any suitable configuration, such as a substantially rectangular crosssectional shape. The bristles are substantially parallel with respect to one another. In operative position, the bristles are oriented toward and angled toward the center of the disc, to offset the skating force caused by the brush contacting the record grooves. The longitudinal axis of the cross section of the group of brush bristles is oriented at an acute angle away from the direction of movement of the disc grooves at the point of contact between the brush and the groove to continuously sweep dust particulate on the phonograph disc toward the center of the record without contacting the stylus.

mfinq m e in Fi ure 1, 1

1 BRUSH FOR PHONOGRAPH PICK-UP APPARATUS BACKGROUND OF THE INVENTION This invention generally relates to a phonograph disc cleaning brush for use with a phonograph.

Various types of phonograph disc cleaning brushes have been constructed and are disclosed in the prior art. Included in this prior art are the following patents: U.S. Pat. No. 3,572,725, issued Mar. 30, 1971, by Murphy; U.S. Pat. No. 1,435,645, issued Nov. 14, 1922, by Kidder, et al.; U.S. Pat. No. 3,185,485, issued May 25, 1965, by 'Brubaker; U.S. Pat. No. 3,410,464, issued Nov. 12, 1968, by Shatavsky; U.S. Pat. No. 2,259,275, issued Oct. 14, 1941, by Stone; U.S. Pat. No. 3,405,946, issued Oct. 15, 1968, by Bodoh; U.S. Pat. No. 2,773,692, issued Dec. 11, 1956, by Dunnavan; U.S. Pat. No. 3,189,353, issued June 15, 1965, by Grado; U.S. Pat. No. 3,618,958, issued Nov. 9, 1971,

by Schmidlin. The most pertinent of the foregoing references, in applicants opinion, are Murphy, Schmidlin and Kidder, et al.

The brush in the Schmidlin reference, termed a wiper, does not have bristles and does not set forth the novel orientation of the brush of the present invention. Rather, Schmidlin uses a fibrous mat made from felt or other, similar material (column 2, lines 4-9). The Murphy reference does teach the use of brush bristles. However, there is no teaching or suggestion of the orientation of these brush bristles in accordance with applicants invention. While the brush of the Murphy invention is generally useful for the purpose intended, there is no teaching or suggestion in Murphy of the orientation of brush bristles so as to accomplish a sweeping of the dust particulate on the phonograph disc toward the center of the disc or the orientation of brush bristles so as to prevent skating which might otherwise occur as a result of the force exerted by the brush on the phonograph disc.

The Kidder, et a1. device utilizes a pad 25 which is shaped in a manner similar to the bristles of Murphy. Accordingly, Kidder, et a1. does not teach a brush having bristles oriented to sweep dust toward the center of the disc or oriented to prevent skating of the stylus across thedisc.

In view of the foregoing, it is desirable to provide an improved phonograph cleaning brush economical to produce and easy to use. It is also desirable to produce such a brush which will sweep a number of grooves of the phonograph disc at one time, move the dust particulate on the disc toward the center of the record, and prevent skating of the stylus across the grooves of the phonograph disc.

SUMMARY OF THE INVENTION The present invention is generally related to a phonograph disc cleaning brush adapted for use with a phonograph of the type utilizing a phonograph disc resting horizontally on the phonograph apparatus. Such a disc has a plurality of sound encoded grooves defined on the disc and spiraling inwardly toward the center of the disc. The invention includes a brush-mounting bracket connectable to one end of a pick-up assembly or to a tone arm and a brushhaving a plurality of bristles connected to the mountingbracket. In one embodiment, the bristles are grouped together and connected to the 2. mounting bracket so as to have a substantially rectangular cross-sectional shape.

The bristles extend outwardly from the brushmounting bracket so that when the stylus tracks in the grooves of the phonograph disc, the longitudinal axis of the grouped bristles is oriented at an acute angle in relation to the direction of movement of the grooves in contact with the brush bristles so as to sweep the dust particulate toward the center of the record. The bristles are also oriented substantially parallel to one another and angled toward the center of the phonograph disc when in operative position so as to prevent skating of the stylus otherwise caused by a component of the frictional force between the brush and the record disc.

BRIEF DESCRIPTION OF THE DRAWINGS Following is a brief description of the drawings showing a presently preferred embodiment of this invention wherein like numerals refer to like elements and wherein:

FIG. 1 is a perspective view of the brush of this invention mounted on the pick-up apparatus of a phonograph;

FIG. 2 is a top view of the brush of FIG. 1 with the pick-up assembly not shown;

FIG. 3 is a cross-sectional view of the brush of FIG. 1 taken substantially along the lines 3-3 of FIG. 1;

FIG. 4 is a side view of the brush and brush mounting shown in FIG. 1; and

FIG. 5 is a top view of the brush and brush mounting connected to the pick-up apparatus in operative position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring generally to FIGS. 1 and 2, there is shown applicants phonograph cleaning device 10 in place on a phonograph disc 12. The disc is positioned on a tumtable (not shown) and includes a plurality of sound encoded grooves 14 which spiral inwardly toward the disc center which is positioned on the turntable spindle 16. A pick-up assembly shown generally at 18 includes a cartridge 24 and atone arm 22. A stylus grip assembly 26 is connected to the cartridge 24 by means of a connecting member 27 which may be inserted into a channel (not shown) defined in the cartridge 24. The phonograph disc cleaning device 10 of this invention is connected to the stylus grip assembly 26 which will be more fully described with reference to FIGS. 1, 2 and 4.

The phonograph disc cleaning device 10 includes a brush-mounting bracket 30 having a top plate portion 32 and bracket arms 34 and 36 connected on opposite sides of the plate portion 32 and extending outwardly therefrom. Arm 34 includes an offset portion 38 having an aperture 40 defined therein and adapted to receive a connecting pin 42. Likewise, arm 36 also includes an offset portion 44' having an aperture 46 defined therein and adapted to receive a connecting pin 48. The connecting pins 42 and 48 which serve as pivot members for the cleaning device 10 may be molded as part of the stylus grip assembly 26. Also, stop members 50 and 52 may be molded on the stylus grip assembly to form apositioning means for the arms 34 and 36 of the cleaning device 10. In this manner, the cleaning device 10 may be mounted on the connecting pivot pin members 42 and 48 so as to drop down into inactive position with the arms 34 and 36 resting against the stop members 50 and 52 when the stylus is lifted away from the phonograph disc.

Referring generally to FIGS. 3 and 5, a brush 54 is provided for the brush cleaning device 10 and includes substantially parallel bristles 56. The bristles 56 are grouped together to form a brush. In the preferred embodiment, the brush bristles are aligned in a plane and have a substantially rectangular cross-sectional shape as may be seen in FIG. 5. The bristles 56 are connected at one end to a bristle-holder member 58 which may be plastic or any other suitable material. The bristles may be secured to the bristle-holder member by the use of a suitable adhesive or other appropriate means.

The bristle-holder member 58 is secured to the underside of the plate 32. In the preferred embodiment, the member 58 includes flanges 59 and 61 which snap into slots 63 and 65 defined in the bracket 30 and adapted to receive flanges 59 and 61.

ORIENTATION OF THE BRUSH BRISTLES Control of the tracking force" of the stylus (i.e., the force which the stylus exerts on the phonograph disc) is of crucial importance to obtain an accurate reproduction of the signals encoded on the disc and to prevent undesirable wear of the grooves. This tracking force must be of sufficient magnitude so that the stylus rides in continuous contact in one of the grooves 14 of the disc 12 but of no greater a magnitude than necessary so as to prevent wear of the grooves 14 which might otherwise arise from excessive stylus pressure to tracking force and to avoid a distortion of the signal transmitted from the stylus 57.

It also is important to control the skating force of the stylus (i.e., the force which tends to cause the stylus to skip over the grooves of the phonograph disc). It is undesirable for a brush positioned on the pick-up apparatus 18 of a phonograph to cause the stylus to skip over the grooves 14 toward the center 16 of the disc 12 and/or imbalance the tracking forces on the two groove walls which causes distortion in the signals from one groove wall and excess wear of the other groove wall. This skating force is produced by a component of the frictional force between the disc 12 and the brush bristles 56 which creates a moment about the tone arm (not shown). This moment produces the undesirable skating force.

In accordance with applicants invention, the bristles 56 are oriented toward the disc and are angled toward the center 16 of the disc 12 at an acute angle when the bristles 56 are in operative position on the pick-up apparatus 18. This acute angle 0 is related to the friction which exists between the disc 12 and the bristles 56. As this friction increases, the angle 0 should be increased.

It has been found that an orientation of the bristles 56 at an acute angle 6 of approximately or greater, away from the normal (an imaginary line perpendicular to plane of the disc 12) for bristles made of pony hair provided an optimum counterbiasing force at the stylus 57 sufiicient to compensate for the skating which might otherwise be caused by the cleaning device 10. For bristles of a synthetic substance, this angle is increased. For example, for nylon bristles, the angle 0 should be about or greater.

By arranging the bristles 56 out in a substantially, rectangular cross-sectional shape as has been described, forward of and projecting on each side of the stylus 57, it has been found that it is possible to clean a large number of grooves simultaneously. In addition to the orientation of the bristles 56 downwardly and toward the center 16 of the disc 12, the longitudinal axis 60 of the grouped bristles 56 is oriented at an acute angle 4) in relation to the direction of movement of the grooves 14 in contact with the bristles 56. In the preferred embodiment, it was found that an angle (1) of approximately achieved the desired effect of moving the dust particulate on the disc 12 toward the center 16. Of course, other angles may be used to accomplish the beneficial results of this invention.

While in the foregoing there has been described a presently preferred embodiment illustrative of the principles of this invention, it is to be understood that modifications may be made to this embodiment without departing from the true spirit and scope of the invention.

What is claimed is:

l. A phonograph disc cleaning brush for a phonograph of the type adapted to receive a phonograph disc having a plurality of sound encoded grooves defined on said disc and spiraling inwardly toward the center of said disc, said phonograph including a stylus mounted in a stylus-retaining member comprising, in combination a brush-mounting bracket; and a brush having a plurality of substantially parallel bristles connected to said mounting bracket about a longitudinal axis and extending from said bracket, said bracket and said brush being arranged so that when said stylus tracks in the grooves of said disc and when said brush and brushmounting bracket are in operative position, the longitudinal axis of the brush is oriented at an acute angle in relation to the tangent of the grooves of the disc in contact with said brush, said bristles also being oriented toward the disc and toward the center of said disc at an acute angle 0 in relation to the normal of the disc, said angle 0 being directly related to the friction between the disc and the bristles of said brush such that said forces at the stylus may be counterbalanced to prevent skating and such that dust particulate on the phonograph disc may be moved toward the center of the record without contacting said stylus.

2. The combination as set forth in claim 1 wherein said brush has a substantially rectangular cross section.

3. The combination as set forth in claim 1 wherein said bristles are connected to a bristle-holder member, and said holder member is connected to said mounting bracket.

4. The combination as set forth in claim 1 including a stylus grip assembly and including means for pivotally mounting said bracket on said grip assembly.

5. The combination as set forth in claim 4 wherein said pivotal mounting means includes first and second pivot pins connected to said grip assembly and first and second mounting apertures on said bracket adapted to receive the first and second pivot pins, respectively.

6. The apparatus as set forth in claim 4 including first and second stop members connected to said grip assembly, adapted to contact said brush-mounting bracket so as to upwardly bias the mounting bracket and position the bracket when the stylus is lifted away from the phonograph disc.

Claims (6)

1. A phonograph disc cleaning brush for a phonograph of the type adapted to receive a phonograph disc having a plurality of sound encoded grooves defined on said disc and spiraling inwardly toward the center of said disc, said phonograph including a stylus mounted in a stylus-retaining member comprising, in combination a brush-mounting bracket; and a brush having a plurality of substantially parallel bristles connected to said mounting bracket about a longitudinal axis and extending from said bracket, said bracket and said brush being arranged so that when said stylus tracks in the grooves of said disc and when said brush and brush-mounting bracket are in operative position, the longitudinal axis of the brush is oriented at an acute angle phi in relation to the tangent of the grooves of the disc in contact with said brush, said bristles also being oriented toward the disc and toward the center of said disc at an acute angle theta in relation to the normal of the disc, said angle theta being directly related to the friction between the disc and the bristles of said brush such that said forces at the stylus may be counterbalanced to prevent skating and such that dust particulate on the phonograph disc may be moved toward the center of the record without contacting said stylus.

2. The combination as set forth in claim 1 wherein said brush has a substantially rectangular cross section.

3. The combination as set forth in claim 1 wherein said bristles are connected to a bristle-holder member, and said holder member is connected to said mounting bracket.

4. The combination as set forth in claim 1 including a stylus grip assembly and including means for pivotally mounting said bracket on said grip assembly.

5. The combination as set forth in claim 4 wherein said pivotal mounting means includes first and second pivot pins connected to said grip assembly and first and second mounting apertures on said bracket adapted to receive the first and second pivot pins, respectively.

6. The apparatus as set forth in claim 4 including first and second stop members connected to said grip assembly, adapted to contact said brush-mounting bracket so as to upwardly bias the mounting bracket and position the bracket when the stylus is lifted away from the phonograph disc.

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