A push-button switch having an interlocking device

Abstract: An interlocking device for a push-button switch comprises a locking lever 13 which is pivotally disposed in a slot 10 extending between two push-buttons. The two end portions of the lever are engaged in recesses in the respective push-buttons and a projection 13a which acts as a fulcrum is formed at the centre of the underside of the lever 13. A pin 12 which engages the projection or fulcrum of the lever is rotatably fitted in journal grooves and extends transversely of the slot. When either of the two push-buttons is depressed, the lever pivots into an inclined position and locks the other push-button against being pressed downward.

Description: This invention relates to a push-button switch having an interlocking device. In some push-button switches, an interlocking device which prevents two push-buttons from being pushed down simultaneously is required in order to avoid breaking of the switch caused by simultaneous operation of two push-buttons. Widely used interlocking devices for pushbutton switches are disclosed in Japanese Utility Model Publications Nos. 551/57 and 28139/64 for example. These devices have a construction such that a rod for interlocking purpose is disposed movably in lateral direction in the switch body between two parallel push-buttons so that when either one of the two pushbuttons is pushed down, an interlocking piece is moved toward the other push-button to lock it. This earlier interlocking system is complicated in construction, has many component parts and is troublesome to assemble, especially where springs and balls are employed in the switches. In US-A-1351161 a switch is described in which a lever is provided to open or close electrical connection between two contacts provided. The lever is actuated by two push buttons and has an arm which is in contact with a resilient roller to prevent operation of the two push-buttons together. The lever is pivotally mounted on a pin which is journaled into lugs fixedly connected to the switch housing so that operation of either one of the push-buttons causes the lever to pivot about the pin thereby opening or closing the electrical connection. A push-button switch device is claimed comprising a switch body in which two push-buttons are mounted side by side for guided sliding movement parallel to each other, an interlocking lever extending between the push-buttons and having its opposite ends in engagement with the two push-buttons respectively and a pin mounted in the switch body and extending transversely of the interlocking lever, the interlocking lever having at its side further from the tops of the pushbuttons and mid-way between its ends a projection which is held by and co-operates with the pin so as to enable pivotal movement of the interlocking lever whereby when either one of the two push-buttons is depressed initially the interlocking lever is caused to swivel about its end engaged with the other of the two pushbuttons so that the projection moves round the side of the pin remote from the push-button being depressed characterised in that the interlocking lever is located in and guided by a channel extending between the two push-buttons which are mounted in the switch body for two-stage operation and the interlocking lever is held by and co-operates with the pin so as also to be capable of lateral movement parallel to and within the channel whereby when the push-button is further depressed in a second stage the entire lever is caused to move laterally within the channel with the opposite ends of the lever respectively moving towards and away from end regions of the channel thereby enabling the projection to move further round the side of the pin remote from the push-button being depressed the engagement between the pin and the lever thereby preventing the other of the two push-buttons from being depressed in both the first and second stages. Thus, when either of the two push-buttons is depressed, the lever swings in a see-saw manner, so that the opposite end of the lever is inclined upward as shown in Figure 5(B) and the other push-button is locked, i.e. it cannot be depressed. When the pushbutton is depressed further, the projection on the lever slides about the outer periphery of the pin. At this time the lever moves laterally toward the other push-button, and the pin may also be arranged to rotate a little, whereby wear on the projection is reduced and the locking action on the other push-button reinforced. Thus locking can be carried out accurately when the pushing down action is made in two steps. The nature and advantage of the present invention will be understood more clearly from the following description of a preferred embodiment of the invention making reference to the accompanying drawings, in which: Figure 1 is a longitudinal section of a push-button switch device according to the present invention, Figure 2 is a side view of the push-button switch of Figure 1, Figure 3 is a plan view of the push-button switch shown in Figure 1, Figure 4 is a bottom view of the push-button switch shown in Figure 1, and Figure 5 is an explanatory drawing of the operation, showing the relation between the push-button and the interlocking lever. Referring to the drawings, two holes 1a in which push-buttons 2 are slidably mounted side by side are provided in the switch body 1. A vertical guide groove 1b for guiding a guide ball 3 for two-step operation is provided in the upper part of the wall of each hole 1a. The guide ball 3 is led into the hole 1a from the guide groove 1b. Each push-button 2 is of such shape as to be slidable vertically in the corresponding hole 1a in the switch body. Each guide ball 3 is disposed in a lateral hole 2a in the push-button and is urged outward against the surface of the guide groove 1b by the biasing force of a spring 4 disposed in the hole 2a and seated against the blanked-off bottom of the hole 2a. A central hole 2b extends upward from the bottom of the push-button 2 and a spring 5 is interposed between the upper end of the hole 2b and the bottom of the hole 1a in the switch body 1 so that the push-button 2 is urged resiliently upward by the spring 5. In order to prevent the push-button 2 from being pushed out of the switch body 1 by the biasing force of the spring 5, the push button 2 is restrained by movable contact pieces S₁, S₂ which extend through the push-button 2 laterally and move toward and away from fixed contact pieces T₁, T₂ fixed to the side of the switch body. A slot 10 is formed in the top surface of the switch body 1 in such a fashion that it interconnects the two parallel holes 1a, and journal grooves 11 in which a cylindrical pin 12 is rotatably mounted to extend transversely of the slot 10 are formed substantially centrally of opposite surfaces of the slot 10. A locking lever 13 is disposed in the groove 10. The lever 13, as shown in Figures 1 and 5, has a projecting fulcrum 13a of triangular shape at the centre of its lower surface. This fulcrum 13a makes contact with the top of the periphery of the pin 12. The ends of the lever 13 are engaged in recesses 2c in the sides of the two push-buttons 2 respectively. The operation of the push-button switch will now be described with reference to Figure 5. Figure 5 (A) shows the OFF state where neither of both push-buttons 2 is depressed. When the right-hand push-button 2 is pushed down a short distance (i.e. a first step) as shown in Figure 5 (B), the lever 13 tilts to the right about its fulcrum 13a. In this state, depression of the left-hand push-button is impossible because the fulcrum 13a is in abutment with the pin 12. Thus, the left-hand push-button 2 is in a locked state. When the right-hand push-button 2 is pushed down further (a second step), it reaches the position shown by Figure 5 (C). The fulcrum 13a of the lever 13 is pressed more strongly against the pin 12, and the pin 12 rotates causing the fulcrum 13a to swing to the left and to make contact with the pin 12 at a position lower than the top surface of the pin 12. Thus the fulcrum 13a is kept in contact with and is held by the pin 12, so that the lever 13 is checked from pivotal movement and is in a locked state. When the push-button is released, it reverts to its original position automatically due to the biasing force of the spring 5 acting on the push-button. At this time, the lever 13 also reverts to its original position shown in Figure 5 (A). In the case of the left-hand push-button the operational action is opposite to that mentioned above, and the right-hand push-button is locked in first and second-step actuating movements. Thus, the preferred embodiment is simple in construction and makes it possible to carry out interlocking of the push-buttons in each of two stages of operation.

Claims: A push-button switch device comprising a switch body (1) in which two push-buttons (2) are mounted side by side for guided sliding movement parallel to each other, an interlocking lever (13) extending between the push-buttons (2) and having its opposite ends in engagement with the two push-buttons (2) respectively and a pin (12) mounted in the switch body (1) and extending transversely of the interlocking lever (13), the interlocking lever (13) having at its side further from the tops of the push-buttons (2) and mid-way between its ends a projection (13a) which is held by and co-operates with the pin (12) so as to enable pivotal movement of the interlocking lever (13) whereby when either one of the two push-buttons (2) is depressed initially the interlocking lever (13) is caused to swivel about its end engaged with the other of the two push-buttons (2) so that the projection (13a) moves round the side of the pin (12) remote from the push-button (2) being depressed characterised in that the interlocking lever (13) is located in and guided by a channel (10, 2c) extending between the two push-buttons (2) which are mounted in the switch body (1) for two-stage operation and the interlocking lever (13) is held by and co-operates with the pin (12) so as also to be capable of lateral movement parallel to and within the channel (10, 2c) whereby when the pushbutton (2) is further depressed in a second stage the entire lever (13) is caused to move laterally within the channel (10, 2c) with the opposite ends of the lever (13) respectively moving towards and away from end regions (2c) of the channel (10) thereby enabling the projection (13a) to move further round the side of the pin (12) remote from the push-button (2) being depressed the engagement between the pin (12) and the lever (13) thereby preventing the other of the two push-buttons (2) from being depressed in both the first and second stages. A switch device as claimed in claim 1, characterised in that said pin (12) is capable of rotational movement about its lengthwise axis in its mounting in the switch body (1).

Inventors: KATO SHIGERU, KATO, SHIGERU
Applicants: SHINKO ELECTRIC CO LTD, SHINKOH ELECTRIC CO., LTD.
Application year: 1990
Main classification: H01H13
IPC codes: H01H13, H01H9