Push Switch

The present invention relates to a push-pull switch adapted for use mainly in combination with a rotatable variable resistance.

The field of push-pull electrical switches may be considered to be a crowded and well-developed technical field in which improvements are in the exact manner and elements of construction. There have been hundreds of push-pull switches of various constructions which have been suggested and many examples of such constructions are presently being commercially marketed.

The object of the invention is to provide a push-pull switch which comprises a lesser number of parts, which is easy to assemble and which will not be likely to malfunction with prolonged usage.

The above and the other objects, as well as advantageous features of the invention, will become clear from the following description of a preferred embodiment taken in conjunction with the attached drawings in which:

FIG. 1 is a side elevational view of a switch according to the present invention which is also a rotary variable resistor,

FIG. 2 is an exploded perspective view of a switch section, showing the push-pull switch elements,

FIG. 3 is a side elevational sectional view of a casing for the switch section,

FIG. 4A is a side elevational sectional view of an essential part of the switch section,

FIG. 4B is a front elevation of the essential part of the switch section,

FIG. 4C is a top plan view of the essential part of the switch section,

FIGS. 5A to 5F are illustrations explanatory of the manner of operation of cam teeth section and a driving piece, and

FIGS. 5A' to 5F' are illustrations explaining the operation of a driving section and a contact piece.

Referring to the drawings showing an embodiment of the present invention, and first referring to FIG. 1, a switch-equipped variable resistance consists of a switching section A and a variable resistance section B. The changing-over or the switching of the switching section A is performed by pushing and pulling an operation shaft 1, while the resistance value of the variable resistance section B is varied by rotating the same operation shaft 1.

The switch section A will be explained in detail with specific reference to FIG. 2 which shows an exploded perspective view. Switch section A includes a casing 2 made of a plastic resin and has a central hollow section 2a. The peripheral edge 2b of the case 2 is provided with four slits 2c, 2c and 2d, 2d. A semi-cylindrical recess 2e and a groove 2f are formed in the inner wall surface of the case 2, at the upper and lower portion of the latter as viewed in the drawings, respectively. These recess and groove have sufficient lengths to reach the bottom 2g (FIG. 3) of the case 2. A projection 2h is formed unitarily with the case 2 to stand up from the bottom 2g.

A slider 3 of a formed plastic resin is provided at its upper surface with a semi-cylindrical recess 3a for receiving a coil metal spring 4, and at its lower surface, with a driving pin 3b formed thereon.

On the side surface of the slider 3, a container section 3c having a notch 3d for receiving a head 1a of the operation shaft 1 is provided. The shaft 1 may freely rotate within the notch 3d and will push or pull the slider 3 when the shaft 1 is moved along its axis. In the lower surface of the container section 3c, there is formed a projection 3e adapted for sliding in the groove 2f of the casing 2.

A driving body 5 is made of a plastic resin insulating material and has a cam-teeth section 5a and a rectangular driving section 5b. The driving body 5 is freely rotatably supported on the slider 3 by a pin 3b of the slider which passes through a central bore 5c of the driving body 5. The aforesaid plastic resin members may be injection molded of a suitable plastic resin, such as a suitable nylon, polycarbonate, ABS or other resin.

The generally E-shaped resilient metallic plates 6,6 have supporting sections 6a,6a on which retaining pieces 6b,6b and 6b,6b are arranged in pairs in the vertical direction. The metallic plates 6,6 are further provided with, at their central portion, contact pieces 6c,6c associated with the driving section 5b of the driving body 5, as well as driving pieces 6e,6e adapted to resiliently engage the cam-teeth section 5a. The plates are formed, for example, stamped from sheet metal, and are resilient flexible electrically conductive members. Alternatively, and not shown, the contact pieces 6c,6c may be separate members.

The ends of the contact pieces 6c,6c are bent to form contacts 6d,6d while portions 6f,6f and 6g,6g constitute terminals.

Claws 6h,6h are provided corresponding to the supporting section 6a,6a, while a projection 6i is formed on the driving piece 6e of both of the metal pieces 6,6.

One way to assemble the switch section A is as follows: At first the coiled spring 4 is inserted into the hollow section 2a of the casing 2, and is attached onto the projection 2h.

Subsequently, the slider 3 with its driving pin 3b rotatably carrying the driving body 5 is brought into the hollow section 2a of the casing 2.

At this time, the end of the pin 3b and a projection 3e of the slider 3 are received by the groove 2f of the casing 2. At the same time, the coiled spring 4 is received by the semi-cylindrical recess of 3a of the slider 3.

Subsequently, as detailed in FIGS. 4A to 4C showing the essential parts, the contact pieces 6c,6c and the driving pieces 6e,6e of the two metal pieces 6,6 are disposed in the hollow section 2a of the casing 2, as the upper and the lower retaining pieces 6b,6b of one of the metal pieces 6 is fitted into the slits 2c,2c in the peripheral edge 2b of the casing 2, while the retaining pieces 6b,6b of the other metal piece 6 are fitted into the slits 2d,2d.

In this state, the ends of the retaining pieces 6b,6b are retained by a part of the peripheral edge 2b of the casing 2, so as to prevent the metal piece 6 from being dropped out.

At the same time, the claws 6h,6h on the supporting sections 6a,6a of the metal pieces 6,6 abut the side surface of the slider 3, to maintain the latter 3 in an energized state by the coiled spring 4 within the hollow section 2a of the casing 2.

At the same time, the contacts 6d,6d of the contact pieces 6c,6c of the metal pieces 6,6 are adapted to contact with each other by their own resiliency. (See FIG. 4A).

In addition, the driving pieces 6e,6e of the metal pieces 6,6 are adapted to be resiliently pressed onto and clamp the cam-teeth section of the driving body which has been previously housed by the hollow section 2a, while the projection 6i of the one of the driving piece 6e comes to engage with the cam-teeth section 5a.

Finally, the reduced-diameter section 1b of the operation shaft 1 is fitted into the notch 3d provided at the container section 3c of the slider 3, so as to bring the head 1a of the operation shaft 1 into the container section 3c to complete the switch section A.

The switch section A may, alternatively, be assembled in another way than described above. This alternative assembly method is as follows:

Namely, at first two metal pieces 6,6 are fitted into the slits 2c,2c and 2d,2d of the casing 2. Subsequently, the coiled spring 4 is secured to the projection 2h on the bottom 2g of the casing 2. Then, the slider 3 having the driving body 5 is put in the hollow section 2a of the casing 2a. At this time, the slider 3 comes to abut the claws 6h,6h of the metal pieces 6,6. However, the resiliency of the metal pieces 6,6 allows snapping of the slider 3 into the hollow section 2a. Thus, the claws 6h,6h come to be retained at side surfaces of the slider 3, thereby to maintain the slider 3 in the hollow section 2a of the casing 2. Finally, the head of the operation shaft 1 is put into the container section 3c of the slider 3, to complete the switch section A.

Referring now to FIG. 5 showing the manner of operation of the switch section, at first the switch is kept at its ON state, with the contacts 6d,6d of the contact pieces 6c,6c on the metal pieces 6,6 abut with each other, as shown in FIG. 5A.

When the operation shaft 1 is depressed (pushed inwardly) the head 1a of the shaft moves the slider 3 along the groove 2f in the inner wall of the casing 2, against the biasing force of the coil spring 4.

Concurrently, the driving body 5 rotatably secured to the slider 3 through a driving pin 3b is moved in the direction of arrows in FIGS. 5A and 5A'. Then, the cam-teethed section 5a of the driving body 5 having been clamped by the driving pieces 6e,6e of the metal pieces 6,6 comes in engagement with the projection 6i on one of the driving piece 6e to be rotated, as will be seen from FIGS. 5B,5B', so that the rectangular driving section 5b unitary with the cam-teethed 5a is brought perpendicular to the contact pieces 6c,6c as shown in FIG. 5C', to move the later 6c,6c apart from each other to release the contacts from each other.

As the depressing force is released, the coiled spring 4 received by the semi-cylindrical recess 2e of the slider 3 urges the slider 3 to its original position. The driving body 5 on the driving pin 3b of the slider 3 moves in the direction of arrow of FIGS. 5C,5C', so that the cam-teeth section 5a slides along the inclined surface of the projection 6i of the one 6e of the driving pieces without rotating, so that the driving piece 5b is kept perpendicular to the contact pieces 6c,6c as shown in FIGS. 5D,5D', to keep the contact pieces 6c,6c away from each other, i.e. at the OFF status of the switch.

A subsequent depression of the operation shaft 1 repeats the described operation and the cam-teeth section 5a of the driving body 5 is rotated by the projection 6i, as shown in FIGS. 6E,6E, so as to bring the driving section 5b in parallel with the contact pieces 6c,6c, to allow the contacts 6d,6d of the contact pieces 6c,6c to engage with each other to turn the switch to ON.

As the depressing force is released, the driving body 5 is returned to its original position, without being rotated, i.e. with its driving section 5b kept in parallel with the contact pieces 6c,6c, preserving the ON status of the switch.

The rectangular driving body 5 is so dimensioned that its one side is longer than the distance between the contact pieces 6c,6c, while the other side is shorter.

As has been described, the switching of the switch section A can be completed by pushing and pulling the operation shaft 1.

To sum up, according to the invention, a push switch is provided with an insulating driving body 5 having a cam-teeth section 5a and a driving section 5b and rotatably secured to a slider 3. The casing has a hollow section 2a for movably accomodating the driving body and the slider 3, and at least two resilient metal pieces 6,6 having contact pieces 6c and driving pieces 6e. The metal pieces 6,6 are attached to the casing 2, and the contact pieces 6c and the driving pieces 6e disposed in the hollow section with the driving pieces 6e,6e clamping the cam-teeth section 5a therebetween. The driving pieces 6e,6e and the contact pieces 6c,6c may each be separate members. In other words, the driving pieces 6e,6e may each be completely separate members. A projection 6i is provided on one of the driving pieces 6e for engagement with the cam-teethed section 5a, whereby the driving body is rotated by the movement of the slider 3, through the projection 6i, to allow both contact pieces 6c,6c to contact with each other.

The switching operation of the switch can be performed without fail by the movement of the slider 3, through the depression of the operation shaft 1.

The switch can be easily assembled by simple insertion and snapping of parts into the casing 2, thus providing a compact push switch having a lessened number of parts and which is easy to assemble.