Device For Simultaneously Controlling A Plurality Of Variable Resistors

Abstract

A device for simultaneously controlling a plurality of variable resistors, in which a pair of bearing members each having a bearing surface consisting of a part of a spherical surface are fixed to the top of an opened bottom casing made of an electrically conductive material and having four side walls, in coaxial relation with a center hole formed through the top. A ball member having an operating shaft extending through the center thereof is rotatably supported by the pair of bearing members so that when the operating shaft is rotated, a plurality of variable resistors mounted on the side walls respectively may be simultaneously controlled. The pair of bearing members as well as the ball member are made of an electrically conductive material, and an elastic member is interposed between the pair of bearing members or in one of them so as to bias the ball member toward one of the pair of bearing members.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a device for simultaneously controlling a plurality of variable resistors. The control device in accordance with the present invention may be used, for example, in a stereophonic sound reproduction system in which more than two volume controls must be adjusted simultaneously.

There has been proposed a device for controlling simultaneously a pluality of variable resistors of the type in which a pair of bearing members which defines a bearing surface consisting of a part of a spherical surface are fixed to the top of an electrically conductive casing having four side walls, in coaxial relation with a center hole formed through the top, and a ball member having an operating shaft extending through the center thereof is rotatably supported by the pair of bearing members so that four variable resistors mounted on the side walls may be simultaneously controlled by rotating the operating shaft. However the undesirable clearance between the ball member and the bearing members is objectionable in that the control of variable resistors cannot be effected with a higher degree of accuracy. Furthermore, when the bearing members and the ball member are made of a non-conductive material, the noise or hum is induced in the sound reproduction systems or the like.

SUMMARY OF THE INVENTION

One of the objects of the present invention is therefore to eliminate the clearance between the ball member and the bearing members in the device for simultaneously controlling a plurality of variable resistors of the type described above.

Another object of the present invention is to prevent the introduction of noise or hum when the variable resistors are controlled.

In order to attain the above objects of the present invention, resilient means is disposed within the bearing members so as to bias the ball member toward one of the bearing members, and the bearing members as well as the ball member are made of an electrically conductive material.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a front view of a first embodiment of the present invention;

FIG. 2 is a bottom view thereof;

FIG. 3 is a partially cross sectional view, on enlarged scale, of a portion thereof;

FIG. 4 is a perspective exploded view thereof;

FIG. 5 is a partially cross sectional view of a second embodiment of the present invention; and

FIG. 6 is a perspective view illustrating one of the bearing members thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment, FIGS. 1-4

A square casing 1 which is made of an electrically conductive material has an open bottom. Molded bearings 3 and 4 each having a bearing surface which is a part of a spherical surface are securely fixed with rivets 5 to the top of the casing 1 coaxially of a hole 2 formed through the top as best shown in FIG. 4. A ball member 8 which is made of an electrically conductive material and has an operating shaft 7 fitted into a through hole 6 formed through the center of the ball member 8 which is rotatably supported by the pair of bearings 3 and 4. A ring-shaped leaf spring 9 which is made of a conductive material and has a plurality of projections 10 radially inwardly extending from the inner periphery thereof is interposed between the pair of bearings 3 and 4 in such a manner that the projections 10 contact the ball member 8 so as to bias it in one direction. In the instant embodiment, the ball member 8 is biased toward the bearing 3 under the force of the leaf spring 9. The wall 11 of the lower bearing 4 serves to limit the angle of rotation of the operating shaft 7.

Variable resistors 12-15 are securely fixed to the four side walls of the casing 1, respectively in such a manner that their shafts 24-27 extend through the side walls into the casing 1. In this embodiment, in order to mount the variable resistors 12-15 on the casing 1, projections or ears 20-23 struck out of the ends of shielding bottoms 16-19 of the variable resistors 12-15 are inserted through engaging holes (not shown) formed in the side walls of the casing 1 and then bent as best shown in FIG. 2. The variable resistors 12-15 may be of the conventional type. Each of a pair of bow-shaped connecting members 28 and 29 which may be made of an elastic material, has projections 28a and 29a (the projection 29a being not shown) which are struck out from the ends of the bow-shaped connecting member and engage with notches 24a-27a formed at the ends of the shafts 24-27 of the variable resistors 12-15. (The notches 25a and 27a are not shown in the figures.) Thus the opposing shafts 24 and 26; and 25 and 27 are interconnected through the bow-shaped connecting members 28 and 29, respectively which cross each other as best shown in FIG. 2. The leading end 32 of the operating shaft 7 is fitted into longitudinal elongated slots 30 and 31 formed in the connecting members 28 and 29.

Next, the mode of operation will be described. Since the ball-member 8 is rotatably supported by the upper and lower bearings 3 and 4, the operating shaft 7 extending from the ball member 8 may be rotated or shifted in any direction. The end 32 of the operating shaft 7 is slidably fitted into the elongated slots 30 and 31 of the connecting members 28 and 29 so that when the operating shaft 7 is rotated, its lower end 32 causes the bow-shaped connecting members 28 and 29 to rotate about the axes of the shafts 24 and 26; and 25 and 27. As a result, the rotation of the bow-shaped connecting members 28 and 29 are transmitted to the shafts 24-27 of the variable resistors 12-15. Therefore, when the operating shaft 7 is rotated, the resistances of the variable resistors 12-15 may be simultaneously varied.

When it is desired to adjust only a pair of opposed variable resistors 12 and 14 or 13 and 15, one may shift the operating shaft 7 in the direction in which the other pair of variable resistors 13 and 15 or 12 and 14 which are not to be adjusted are disposed, that is, in a plane which contains the axis of the shafts 17 and 19 or 16 and 18 and is perpendicular to the axis of the shafts 16 and 18 or 17 and 19. In this case, the end of the operating shaft 7 slides in the elongated slot 31 or 30 without causing the connecting member 29 or 28 to rotate, but causes the connecting member 28 or 29 to rotate. Thus only one pair of opposed variable resistors 12 and 14 or 13 and 15 may be adjusted.

Since the leaf spring 9 interposed between the upper and lower bearings 3 and 4 serves to bias the ball member 8 in one direction as explained above, undesired play of the ball member 8 may be taken up. Furthermore the ball member 8 which is made of an electrically conductive material is electrically connected to the casing 1 through the condustive leaf spring 9, and the rivets 5 that the noise may be prevented from being induced when the operating shaft 7 is actuated.

Second Embodiment, FIG. 5 and FIG. 6

The second embodiment shown in FIGS. 5 and 6 is substantially similar to the first embodiment described above except that a plurality of resilient projections 9a are formed integral with the wall 10 of the lower bearing 4, thus the leaf spring 9 used in the first embodiment is eliminated.

In the second embodiment, the plurality of resilient projections 9a may be formed simultaneously when the bearing 4 is molded. Therefore the number of parts may be reduced and the assembly may be much facilitated, so that the second embodiment is more economical than the first embodiment.

Claims

What is claimed is:

1. In a device for simultaneously controlling a plurality of variable resistors of the type in which a pair of molded bearing members each having a bearing surface which is a part of a spherical surface are securely fixed to the top of an electrically conductive casing having four side walls in coaxial relation with a center hole formed in the top of said casing;

a ball member having an operating shaft extending through the center thereof is rotatably supported by said pair of bearing members; variable resistors are fixed on the side walls of said casing in such a manner that their shafts extend through each side wall into said casing; and the end of said operating shaft is slidably fitted into elongated slots formed in bow-shaped elastic connecting members each connecting the opposed shafts of said variable resistors,

a member having a plurality of elastic projections interposed between said ball member and said pair of bearing members so as to contact said ball member and to bias it toward one of said pair of bearing members, and

said pair of bearing members and said ball member being of an electrically conductive material electrically connected to the casing.

2. A device as defined in claim 1 wherein said member is made of an electrically conductive material and is interposed between said pair of bearing members so as to bias said ball member toward one of said pair of bearing members.