JPH0124824Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the shape of a rubber cover in a push button switch using conductive rubber contacts.

2. Description of the Related Art Conventionally, push button switches used as keyboard switches for electronic organs and the like have a movable contact portion consisting of a conductive rubber contact and a rubber cover integrally formed with the rubber contact. This type of push-button switch is widely used because it does not make a clicking sound when reversed and has a soft feel, but its stroke generally requires only a small amount of movement of the key after the switch is turned on, and is called an end-on switch. It's starting to become. However, from an ergonomic point of view, it is said that the ideal operating force curve as shown in FIG. 1a is the relationship between the operating force and the amount of movement, or stroke, of a musical instrument keyboard switch. As can be seen from the figure, a certain amount of movement is required even after the switch is turned on. However, in the conventional push button switch mentioned above, the relationship between the operating force and the amount of movement is as shown by the broken line in Figure 1b, the operating force increases rapidly after the switch is turned on, and the amount of movement is almost negligible, making it difficult to ergonomically. If you look at it, it is extremely defective.

Therefore, the present invention has a movable contact part made of a rubber cover integrally formed with a conductive rubber contact that has a movement amount even after the switch is turned on and has characteristics closer to the ideal actuation force curve shown in Figure 1a. The purpose is to provide a push button switch.

Next, the present invention will be explained in detail with reference to the drawings while comparing it with a conventional example. Fig. 2 shows a movable contact part of a conventional push button switch; Fig. 2a is a sectional view thereof, and Fig. 2b is a sectional view showing a state in which the contact is in contact with a fixed contact.
Figure c is a sectional view showing a state in which the movable contact portion is further pressed after contacting the contact. In Figure 2, 2
1 is a conductive rubber contact which is a movable contact portion; 1 is a bowl-shaped rubber cover formed integrally with the contact 2; and 5 is a pressing portion formed on the top of the rubber cover 1. When a load is applied from above the top pressing part 5 of the rubber cover 1 of such a movable contact part, the rubber cover 1 hardly deforms at first, and can withstand the load up to a certain value in that state. When the load exceeds a certain value, rubber cover 1
As shown in Figure b, buckling occurs at point 3,
The amount of movement changes instantly with a click action,
The conductive rubber contact 2 contacts a fixed contact (not shown) and the switch is turned on. If more load is applied, the overstroke bending portion 4 will stretch and deform, allowing a slight overstroke after turning on. However, when the amount of movement exceeds a certain amount, the lower part 6 of the pressing part 5 becomes strained.
A crack occurs in the lower part 6, making it unusable. In general, the life span is reached after 300,000 to 500,000 on-off cycles with an overstroke of 0.5 mm. FIG. 3 shows a movable contact portion of a push button switch according to the present invention, which was devised in order to eliminate such strain caused in the lower part 6 of the pressing portion 5 and to obtain a push button switch with a long life and a long overstroke.

Figure 3a is a sectional view of the movable contact, Figure 3b is a sectional view showing the contact in contact with the fixed contact, Figure 3c
FIG. 2 is a cross-sectional view showing a state in which the movable contact portion is further pressed after the contact is brought into contact. In FIG. 3, 2 is a conductive rubber contact, 1 is a bowl-shaped rubber cover integrally formed with the rubber contact 2, and 5 is an annular pressing portion formed on the top of the rubber cover 1. Reference numeral 7 denotes a notch portion formed approximately at the center of the lower surface of the press, and this notch portion 7 is different from the conventional movable contact portion shown in FIG. For details of this notch, see Section 4.
The cross-sectional view is shown in the figure. The top pressing portion 5 of the bowl-shaped rubber cover 1 of the movable contact portion configured as described above
When a load is applied from above, the bowl-shaped rubber cover 1 forms a buckling portion 3 as shown in FIG. . When a further load is applied, the notch 7 opens as shown in FIG.
This will eliminate the unreasonable stress that is applied to the By providing this notch 7 in the lower part 6 of the pressing part,
The stroke after switching on can be up to 2mm, and a 2mm overstroke provides a movable contact that can withstand 5 million on/off cycles. The relationship between the operating force and the amount of movement of this movable contact part is as shown in the solid line in Fig. 1b, which is better compared to the characteristic shown in the broken line of the conventional movable contact part in Fig. 1a.
This approaches the ideal characteristics shown in .
Further, as shown in FIGS. 2a and 3a, the length of the conventional bowl-shaped rubber cover 1 is l, the length of the overstroke bending part 4 is m, and the upper part of the notch part 7 and the lower part of the pressing part 6 is α, the length of the bowl-shaped rubber cover 1 of the present invention is l+α, and the length of the overstroke bending portion 4 is m+α, which is the distance between the upper part of the notch part 7 and the lower part of the pressing part 6. The lengths of the bowl-shaped rubber cover 1 and the overstroke bending portion 4 can be increased.

As explained in detail above, the push button switch according to the present invention is provided with a notch to eliminate unreasonable stress applied to the bottom surface of the top pressing part of the bowl-shaped rubber cover that is integrally formed with the conductive rubber contact. The length of the bowl-shaped rubber cover and overstroke bending part is longer, the lower surface of the pressing part is less likely to crack, the life is more than 10 times longer than the conventional movable contact part, and the overstroke is 4 times longer than the conventional one. Since the length can be twice as long, the relationship between the actuation force and the amount of movement of the keyboard switch is closer to the ideal condition from an ergonomic point of view, which is an excellent effect.

[Brief explanation of the drawing]

Figures 1a and b are characteristic curve diagrams showing the relationship between the operating force and the amount of movement of the movable contact part, Figures 2a, b, and c are cross-sectional views showing the movable contact part of a conventional push button switch, and Figure 3. a, b, and c are sectional views showing the movable contact portion of the push button switch according to the present invention, and FIG. 4 is an enlarged sectional view showing the notch provided on the lower surface of the press. DESCRIPTION OF SYMBOLS 1... Bowl-shaped rubber cover, 2... Conductive rubber contact, 3... Buckling part, 4... Overstroke bending part, 5... Pressing part, 7... Notch part.

Claims (1)

[Scope of utility model registration request] In the movable contact part of the push button switch, a substantially annular pressing part is provided at the top of the bowl-shaped rubber cover, and a conductive rubber contact is formed from this pressing part via an overstroke bending part. A push button switch characterized by having a notch section.