US3532003A - Actuator for a switch - Google Patents

Description

United States Patent 3,532,003 ACTUATOR FOR A SWITCH Junji Ohno, Hamamatsu-shi, Japan, assignor to Nippon Gakki Seizo Kabushiki Kaisha, Hamamatsu-shi, Shizuoka-ken, Japan Filed Oct. 14, 1968, Ser. No. 767,251 Int. Cl. F16h 21/00 U.S. Cl. 74108 2 Claims ABSTRACT OF THE DISCLOSURE An actuator for a switch, such as a keyboard switch in an electronic musical instrument, having a resilently mounted actuating member which performs a translational movement. The switch actuator has a base portion secured on a frame, a first resilient member projecting forward from the base and a second integral resilient member extending rearwardly from the free end of the first member. The first and second members are proportioned in length, second moment of area and Youngs modulus so that the actuating member mounted on the free end of the second member performs the desired translational movement.

The present invention relates to an actuator for a switch and, more particularly, it relates to an actuator for a keyboard switch of an electronic musical instrument.

It is an object of the present invention to provide an actuator which can be advantageously used in a switch having a plurality of movable contacts arranged in a juxtaposed relationship with respect to each other in a relatively narrow space in a switch box, such as a keyboard switch of an electronic musical instrument.

In accordance with the present invention there is provided an actuator for a switch in which an actuating member is resiliently supported so as to perform a translational movement, with a simple construction.

The invention will be explained with reference to the accompanying drawings in which:

FIG. 1 is a side view of actuators embodying the present invention;

FIG. 2 is a bottom plan of the actuators shown in FIG.

FIGS. 3a, b, c and d are diagrammatic views illustrating the principle of the present invention;

FIG. 4a is a vertical sectional view of the actuator shown in FIG. 1, and FIG. 4b is a sectional view similar to FIG. 4a shown in the depressed state; and

FIG. 5 is a side view of a keyboard switch of an electronic musical instrument including the actuators shown in FIG. 1.

Referring to the drawings, an actuator for a switch according to the present invention comprises a base portion 2 adapted to be fixed to a suitable frame by means of a screw or the like, a first resilient member 3 extending forward from said base portion, a second resilient member 4 folded back from the forward end of said first resilient member and an actuating member 5 fixed at the free end of said second resilient member, said first and second resilient members being so proportioned in length, second moment of area and Youngs modulus that said member performs a translational movement. The second moment of area is determined by the cross sectional configuration such as width and thickness of each of the resilient members and the Youngs modulus is determined by the material thereof.

Now the principle of the present invention will be explained with reference to FIG. 3. FIGS. 3a, b and 0 diagrammatically show an actuator having a first resilient member 3 and a second resilient member 4 which are formed as an integral piece of uniform material having uniform thickness and width. The first resilient member 3 is fixed at its base end, while the second resilient member 4 is provided at its free end with an actuating member 5, to which a switch actuating force is applied. In FIG. 3a, is a distance between the point of force A and the point of the forward end of the first resilient member B, is a distance between the point of force A and the point of the fixed end of the first resilient member C and W is a force applied to the point of force A. FIG. 3b shows a stress distribution in the resilient mernbers caused by the force W, and FIG. 3c shows a deflection of the resilient members. In FIG. 30, 0 is an angle of deflection of each of the resilient members between the points A and B 6 is an angle of deflection of the first resilient member between the points A and C. The angles 0 and 0 can be expressed by the following equations:

where E is a Youngs modulus of the resilient member, and I is a second moment of area of the resilient member.

Thus the second resilient member at the point A is always maintained in a horizontal plane of the relation 20 =0 exists. This is,

2 WI1 W12 2E1 2EI where I is a second moment of area at the part of 1 of the resilient members (at the part of 1 the total width of the first resilient member is equal to the width of the second resilient member, that is and I is a second moment of area at the part of (it is assumed that part of 1 has a uniform width b) If 202562,

Accordingly, when the condition l /5l is satisfied, the second resilient member is always maintained in a horizontal plane at the point to which the switch actuating force is applied and thus the actuating member performs a translational movement.

The same result will be obtained by properly selecting the distribution of the second moment of area or the Youngs modulus, such as by varying the width, thickness or material of the respective resilient members.

FIG. 1 shows an actuator embodying the above principle of the present invention. In the form shown in FIG. 1 the first resilient member 3 is relatively thick at its intermediate portion so that the resilient deformation occurs principally at its end portions. The second resilient member 4 is integrally connected with the first resilient member 3. FIGS. 4a and b illustrate in cross section the operation of said actuator, FIG. 4a showing the state where the actuating member has not been depressed and FIG. 4b showing the state where the actuating member is depressed.

FIG. 5 is a side view of a keyboard switch including the actuator constructed in accordance with the present invention, in which is a key pivotally mounted at the backward end thereof, 11 is an actuator according to the present invention, 12 is a movable wire contact adapted to be actuated by said actuator and 13 is a fixed bus-bar contact. When the key 10 is depressed the actuator is urged downward to move the movable wire contact 12 into contact with the fixed bus-bar contact 13.

It will be apparent from the above description that in accordance with the present invention the translational movement of the actuator can be easily obtained by properly selecting the length, the width, the thickness and the material of the first and second resilient members which resiliently support the actuating member. The actuator is very simple and compact in construction and can be manufactured at low cost, and consequently it can be conveniently adapted in a switch including a plurality of switch contacts arranged in a juxtaposed relationship with respect to each other in a narrow space.

What is claimed is:

1. An actuator for a switch comprising a base portion adapted to be secured on a supporting frame, a first resilient member projecting forward from said base portion, a second resilient member extending rearwardly from the forward free end of said first resilient member, and an actuating member secured at the free end of said second resilient member, said first and second resilient members being so proportioned in length, second moment of area and Youngs modulus that the actuating member performs a translational movement.

2. An actuator for a switch according to claim 1, in which the first and second resilient members are integral portions of a single stamped sheet of metal.

References Cited UNITED STATES PATENTS 2,627,002 1/1953 Alvarez 74-l00 2,755,346 7/1956 Fisher 200166 2,794,888 6/1957 Morse 200166 WESLEY S. RATLIFF, JR., Primary Examiner

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