Push Button Switch Having Two Resilient Contacts Operated at Different Times

(1) Field of the Invention

The present invention relates to a push-button switch. More specifically, the present invention relates to a push-button switch of the momentary motion type in which the thickness of the switch is reduced, a light switching touch is obtained and two-motion changeover operation is possible.

(2) Description of the Prior Art

A two-motion push-button switch is used for various purposes. For example, it is used in a tape recorder or the like to perform the switching operation of the running speed of the tape to move the tape at an ordinary speed or a higher speed, and in adjusting the indicating hands of an electric clock, the two-motion push-button switch is used for performing the switching operation of the rotation speed and turning the hands at a higher speed. Furthermore, the two-motion push-button switch is combined with an electric circuit and is used as a pulse-generating swtich.

Various push-button switches of this type differing in structure have heretofore been proposed. However, these switches typically have a complicated structure and are often large in their dimensions. In the field of electronic appliances such as radio sets and television sets, diversification of the functions, reduction of the size and enhancement of the quality and capacity have been desired, and development of a push-button switch of this type which is reduced in size and can be operated by a small driving force with a good operation touch is desired.

The present invention is to provide a two-motion push-button switch meeting the above requirements. More specifically, in accordance with the present invention, there is provided a two-motion push-button switch of a simple structure with small size and reduced thickness, in which a light switching operation touch can be obtained by reversing operations of a reversing spring formed by a thin, electrically conductive metal plate high in resiliency and having contact pieces. Auxiliary springs are disposed to enable two-motion switching operations and the reversing spring contact pieces are pressed in the direction along planes thereof.

The present invention will now be described in detail with reference to the accompanying drawings illustrating one embodiment of the present invention.

FIG. 1 is a fragmentary perspective view illustrating the structure of one embodiment of the two-motion push-button switch according to the present invention.

FIG. 2 is a sectional side view of the push-button switch shown in FIG. 1.

FIGS. 3(a) to 3(c) are sectional side views illustrating the operations of the push-button switch shown in FIG. 1.

Referring to the drawings in which FIG. 1 is a fragmentary perspective view showing the structure of the push-button switch of the present invention, FIG. 2 is a sectional view of the push-button switch of the present invention and FIGS. 3(a), 3(b) and 3(c) are diagrams illustrating the operations of the push-button switch of the present invention, a first case 1 is molded from a synthetic resin and comprises an open concave portion 1a, an opening 1b formed in the upper side wall shown in FIG. 1 and a side wall 1c confronting said opening 1b and projecting outward at a right angle from a bottom 1e. Grooves 1d having a V-shaped section and a concave portion 1f for receiving auxiliary springs described hereinafter are formed in the side wall 1c, posts 1g are formed at the four corners of the side walls for attachment of a case portion described hereinafter and projections 1h are formed at the two upper corners as shown in FIG. 1. In the bottom of the concave portion 1b are fixed contact pieces 2 and 3 providing fixed contacts 2a and 3a, and external connection terminals 2b and 3b connected to the fixed contacts extend from the surface of the bottom 1e of the case 1. Incidentally, the fixed contact pieces 2 and 3 are fixed to the case simultaneously with the molding of the case by arranging the contact pieces in a mold and insert-molding a synthetic resin in the mold. A movable contact piece 4 forming a movable contact of first and second switch portions is integrally formed from a thin, electrically conductive metal plate high in resiliency, and the movable contact piece 4 comprises a pair of arms 4a and 4a' formed on respective ends of the contact piece, and a reversing portion 4b held between the arms 4a and 4a'. A part of the reversing portion 4b is punched to provide a movable contact portion 4d divided into a plurality of segments and having tongue pieces 4c and connecting portions 4e. The tongue pieces 4c are bend outwardly for engagement with the fixed contacts 2a and 3a, as will be set forth more fully below. When a force is applied to the arms 4a and 4a' in the direction indicated by the arrows in FIG. 1, the reversing portion 4b is urged outwardly toward the fixed contacts 2a and 3a. In order to promote this reversing action, the arms 4a and 4a' are slightly folded with a certain angle on the bases thereof. A slider 5 comprises a push-button portion 5a, notches 5b to be engaged with the projections 1h formed on the case 1, a jaw portion 5c formed on one face 5d and a concave portion 5f formed on the other face 5e at a position confronting the jaw portion 5c to receive an auxiliary spring. The length lc of the notches 5b is larger than the length lp of the projections 1h, so that the slider 5 moves in and out along a length (lc-lp) within the concave portion 1a of the case 1. One arm 4a' of the movable contact piece 4 is engaged within the jaw portion 5c. Reference numeral 5g represents an end portion. A second case 6 constituting a switch case in combination with the above-mentioned first case 1, which has a substantially channel shape, comprises a concave portion 6a, projections 6b and holes 6c corresponding to the concave portion 1a, projections 1h and post 1g of the first case 1. Fixed contact portions 7a and 8a are exposed on a bottom 6d of the concave portion 6a and fixed contact pieces 7 and 8 having external connection terminals 7b and 8b are integrally formed by insert-molding.

Auxiliary springs 9 and 9' are formed of a thin metal plate high in resiliency and are bent to have a substantially U-figured shape. V-figured anchoring grooves 9a and 9a' are formed on free ends to support one arm of a movable contact piece 4. Resilient forces of the auxiliary springs are determined relative to the pressing force necessary for reversing of the movable contact piece 4. In the present embodiment, the resilient force of the auxiliary spring 9 is made larger than that of the auxiliary spring 9' and also larger the force required for reversing of the movable contact piece 4, while the resilient force of the auxiliary spring 9' is smaller than the force required for reversion of the movable contact piece 4.

Assembling of the push-button switch of the present invention will now be described. First, the auxiliary spring 9 is inserted in the concave portion 1a of the case 1 so that the free end is directed towards the bottom 1e and the anchoring groove 9a is located above. Then, one arm 4a of a movable contact piece 4 is engaged with and fitted in the groove 9a formed on the auxiliary spring 9. Then, the slider 5 is arranged in the opening 1b of the concave portion 1a of the case 1, and the other arm 4a' is engaged with the jaw portion 5c of the slider 5. In this state, the slider 5 is slightly pushed in the direction pressing the movable contact piece 4 to engage the notches 5b with the projections 1h of the case 1, whereby the movable contact piece 4 is held on the case through the slider 5 on one side and through the auxiliary spring 9. Furthermore, the central part of the bent movable contact portion 4d of the movable contact piece 4 is brought into close contact with the surface 5d of the slider 5. The slider 5 is always urged outwardly by the spring force of the movable contact piece 4, and the push button portion 5a is projected from the case 1.

Then, the auxiliary spring 9' is inserted in the concave portion 5f formed on the other face 5e of the slider 5 so that the anchoring groove 9a' confronts the V-shaped groove 1d formed on the side wall 1c of the case 1. Then, the arm 4a' of another movable contact piece 4 is engaged with the anchoring groove 9a' of the auxiliary spring 9' and the other arm 4a is engaged with the groove 1d of the side wall 1c, so that the auxiliary spring 9' is slightly bent upward, whereby the movable contact piece 4 forming the second switch portion is held on the case 1 on one side and on the slider 5 through the auxiliary spring 9' on the other side. Thus, the central part of the bent movable contact portion 4d is brought in close contact with the other face 5e of the slider 5. Then, the second case 6 is fixed by inserting the poles 1g of the first case 1 into the holes 6c so that the movable contact portion 4d of the movable contact piece 4 confronts the fixed contact portions 7a and 8a, whereby assembling is completed, as shown in FIG. 2.

The operations of the push-button switch of the present invention will now be described with reference to FIGS. 2 and 3.

In the state where the push-button portion 5a is not depressed, as shown in FIGS. 2 and 3(a), the slider 5 is urged upward by the movable contact pieces 4 and auxiliary springs 9 and 9' and the contact portions 4d of the movable contact pieces 4 of the first and second switch portions are kept in the non-contact state with the confronting fixed contact portions 2a and 3a of the fixed contact pieces 2 and 3 and the switch is off. The movable contact portion 4d of the second switch portion is also kept in the non-contact state with the fixed contact portions 7a and 8a of the fixed contact pieces 7 and 8.

When the push-button portion 5a is depressed in the direction of arrow B in this state, since the auxiliary spring 9 has a larger elastic force than the movable contact piece 4 of the first switch portion, the initial shape is substantially retained in the auxiliary spring 9, and the arms 4a and 4a' of the movable contact piece 4 are bent in the direction of arrow C of FIG. 3(b). When the push-button portion 5a is further depressed in the direction of arrow B, the connecting portions 4e of the movable contact piece 4 and the movable contact portion 4d are reversed suddenly in the direction of arrow C. The tongue pieces 4c of the movable contact portion 4d are pressed to the fixed contact portions 2a and 3a by the repulsive force of the movable contact piece 4 to produce the switch-on state.

Since the resilient force of the auxiliary spring 9' of the second switch portion is smaller than that of the movable contact piece 4, the auxiliary spring 9' is bent and the original state of the movable contact piece 4 is substantially retained, and the switch-on state is maintained. When the push-button portion 5a is further depressed in the state shown in FIG. 3(b), the end 5g of the slider 5 is brought into contact with the back face of the auxiliary spring 9 to further bend the auxiliary spring 9, and the reversed movable contact piece 4 slides downward with sliding of the slider 5 while keeping the switch-on state.

In the second switch portion, the auxiliary spring 9' is bent and the free end thereof is kept in the contacted state, and further pressing force acts directly on the movable contact piece 4, whereby the connecting portions 4e and movable contact portion 4d of the movable contact piece 4 are reversed suddenly in the direction of arrow D. The tongue pieces 4c of the movable contact portion 4d are pressed to the fixed contact portions 7a and 8a by the repulsive force of the movable contact piece 4 to produce the switch-on state, as shown in FIG. 3(c). The movement range of the slider 5 is limited by the length lc of the notches 5b and the length lp of the projections 1h so that an unnecessarily large pressing force is not applied. When the pressing force is released in the state where the push-button portion 5a is pressed to the last extremity, the state shown in FIG. 3(a) is restored to produce the switch-off state.

According to the present invention, the first switch portion and second switch portion are fabricated so that the reversing portion having a bent shape is formed by molding a thin, electrically conductive metal plate high in resiliency, the movable contact portion having tongue pieces is formed in the vicinity of the reversing portion and arms are formed on both the ends of the reversing portion to form a reversing spring movable contact piece, the movable contact portion is arranged in the case so that the movable contact portion confronts the fixed contact portion, and by pressing the tongue pieces in the direction of the length of the movable contact piece, the reversing portion is reversed in a direction rectangular to the pressing direction to cause disconnection. Furthermore, a reversing spring is disposed on one end of the movable contact piece, and the resilient force of one auxiliary spring is made larger than the resilient force required for reversion of the reversing spring movable contact piece while the resilient force of the other auxiliary spring is made smaller than the resilient force required for reversion of the reversing spring contact piece. Accordingly, the size of the push-button switch in the thickness direction can remarkably be reduced, and since the reversing action is transmitted to the finger, a very excellent changeover touch can be produced. Thus, a very excellent two-motion push-button switch can be provided according to the present invention.

In the foregoing embodiment, the resilient force of one auxiliary spring is made larger than the resilient force of the movable contact piece while the resilient force of the other auxiliary spring is made smaller than that of the movable contact piece. In the present invention, there may be adopted a modification in which the resilient force of one movable contact piece is made larger than that of the auxiliary spring while the resilient force of the other movable contact piece is made smaller than that of the auxiliary spring. The same excellent effects as described above can similarly be attained even if this modification is adopted.