JPS6039951Y2 - capacitive keyboard switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to small push button switches used in electronic desk calculators, electronic calculators, typewriters, etc., and particularly to capacitive keyboard switches.

Conventionally, as this type of capacitive keyboard switch, there is a type that can be combined with a printed circuit board having fixed electrodes, and in order to make the entire device thin, it has been necessary to reduce the height of the switch as much as possible.

However, with conventional capacitive switches, if the switch height is lowered, the switching stroke becomes too short, and there is a limit to how low the switch height can be made.

For example, if the conventional structure required a switching stroke of 4 MIL, the switch height with the key top attached was at least 20 rrrm.

If this height is forcibly lowered, the guide portion between the actuator and the case becomes shorter, resulting in drawbacks such as increased wobbling of the key top when the key top is pressed.

In other words, in the conventional structure, if the switch height is set to 19771771 without wobbling the key top, the switching stroke will not be the necessary 4N, but will be 3rIrIIK.

The purpose of the present invention is to provide a capacitive keyboard switch that has a low switch height, has the necessary switching stroke, and does not cause wobbling of the key tops, in view of the prior art as described above. be.

According to the present invention, in a capacitive keyboard switch that can be combined with a printed circuit board having a fixed electrode, there is provided a switch case that is installed on the printed circuit board so as to surround the fixed electrode, and a switch case that is installed on the printed circuit board so as to surround the fixed electrode; an actuator having a key top mounting part protruding upward from the upper part for mounting the key top; and a movable electrode mounting part housed in the switch case and having a movable electrode facing the fixed electrode; The top mounting includes a key top attached to the section and a return spring provided between the key top and the upper part of the switch case, and the movable electrode mounting is provided around the section protruding downward and above the switch case. A guide pin is provided in sliding contact with the inner wall of the switch case to guide the movement of the actuator, and a guide pin escape hole is formed in the printed circuit board to receive the guide pin, so that the key top is pressed. When the actuator is
The movable electrode is moved toward the fixed electrode against the deflection force of the return spring and according to the guiding action of the inner wall of the switch case and the guide pin. It is distantly related to capacitive keyboard switches.

Next, the present invention will be described in more detail with regard to embodiments of the present invention based on the accompanying drawings.

FIG. 1 is a perspective view of an exploded component arrangement of a capacitive keyboard switch as an embodiment of the present invention.

The capacitive keyboard switch of this embodiment is one in which a plurality of switch elements are integrally formed, and a plurality of fixed electrodes 11 are formed in a matrix on a printed circuit board 10.

A plurality of switch cases 21 are integrally formed on the keyboard housing 20 stacked on the printed circuit board 10 at positions corresponding to the respective fixed electrodes 11 on the printed circuit board 10.

Each switch case 21 includes a key top mounting portion 31 that protrudes upward from the opening 22 at the top of the switch case 21 to attach the key top 40, and a movable electrode that is housed within the switch case 21 and faces the fixed electrode 11. 3
An actuator 30 having a section 32 is attached to the movable electrode mounting section 3.

At four corners around the movable electrode mounting section, guide pins 34 are provided that protrude downward and slide against the inner wall of the switch case to guide the movement of the actuator 30.

Guide pin escape holes 12 are formed around the fixed electrodes 11 of the printed circuit board 10 to receive guide pins 34 of the corresponding actuators 3o.

A key top 40 is attached to the key top attachment portion 31 of the actuator 30 that protrudes upward from the opening 22 of each switch case 21.
A conical coil spring 50 for return is provided between the upper part of the key top 1 and the key top 40.

In FIG. 1, only one set of the actuator 30, movable electrode 33, key top 40, and return conical coil spring 50 is shown, but these are the same number of sets as the switch cases 21 provided in the keyboard housing 20. Only one person can be provided.

After arranging the actuator 30, movable electrode 33, conical coil spring 50 for return, and key top 40 in each switch case 21, the printed circuit board 10 and the keyboard housing 20 are fixed to each other using the upper frame 60 and the screws 70. At that time, each movable electrode 33 correctly faces each fixed electrode 11, and the guide pin 34 of each actuator 30 is inserted into the guide pin escape hole 1 of the printed circuit board 10.
It is designed to face each of the two.

FIG. 2 shows an enlarged cross-section of one switch case in such an assembled state, and as is clearly shown in this enlarged cross-sectional view, there are , guide pin 2 of actuator 30
Guide pin grooves 23 are formed for receiving and guiding the pins 4, respectively.

A movable electrode 33 is fixed to the movable electrode mounting portion 32 of the actuator 30 with an adhesive or the like via a sponge disk member 33A.

Since the capacitive keyboard switch of the present invention has such a configuration, when the key top 40 is pressed, the actuator 30 descends against the deflection force of the return conical coil spring 50, and at this time, the actuator 30 The movement of the guide pin 34 is reliably guided by the sliding engagement between the guide pin 34 and the guide pin groove 23, and the tip of the guide pin 34 is received by each guide pin escape hole 12 of the printed circuit board 10. , a large switching stroke is obtained, and when the key top 40 is lowered, the key top 40
There is no wobbling, and the movable electrode 33 can be brought close enough to the fixed electrode 11 correctly.

In the above embodiment, the reason why the return spring is a conical coil spring is that when the spring is compressed when the key top 40 is pressed,
The compressed length can be minimized, since this is preferable in order to suppress the switch height and obtain the maximum switching stroke.

In the embodiment described above, the bottom of the switch case 21 is flat so that it is simply placed on the top surface of the printed circuit board 10, but the switch case 21 has a flat bottom so that it is simply placed on the top surface of the printed circuit board 10. Guide bosses that protrude into the guide pin relief holes 12 are formed at the bottom of the case 21, and the switch case 2 is attached to these guide bosses.
A guide groove may be formed as an extension of the first guide pin groove 23, and by doing so, the actuator can be guided more stably than the switch height.

Furthermore, in the above-mentioned embodiment, the keyboard housing is made by integrating multiple switch cases, but this is so that the printed circuit board and each case can be fixed at once. This is because it is preferable to minimize the space required for screwing.

In a keyboard housing that integrates multiple switch cases in this way, as shown in Figure 1, water distribution grooves 24 are installed to make it easier to remove water spilled onto the board.
It is a good idea to form a

Furthermore, according to the present invention, guide pin relief holes 12 are formed in the printed circuit board 10, so that in order to prevent dust from entering the switch case through these holes,
It is preferable to cover the lower surface of the printed circuit board 10 with a dust cover made of cloth, resin sheet, or the like.

As is clear from the above, by providing the guide pin escape hole in the printed circuit board according to the present invention, the guide pin can be guided for a long time without interfering with the switching stroke of the actuator, and the height of the switch can be reduced. You can still get a sufficient switching stroke even when the key tops are wobbling.

[Brief explanation of drawings]

FIG. 1 of the accompanying drawings is a perspective view of an exploded component arrangement of a capacitive keyboard switch as an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view taken along line A--A in FIG. 1. 10... Printed circuit board, 11... Fixed electrode, 12... Guide pin escape hole, 20...
... Keyboard housing, 21 ... Switch case, 23 ... Guide pin groove, 30 ...
... Actuator, 31...Key top installation is part, 32...Movable electrode installation is part, 33...
...Movable electrode, 34...Guide pin, 40
...Key top, 50 ... Conical coil spring for return, 80 ... Dust cover for dustproofing.

Claims (6)

[Scope of utility model registration request] (1) In a capacitive keyboard switch that can be combined with a printed circuit board having a fixed electrode, a switch case is installed on the printed circuit board so as to surround the fixed electrode, and a an actuator having a key top mounting section protruding from the switch case to attach a key top; and a movable electrode mounting section housed in the switch case and mounting a movable electrode facing the fixed electrode; The movable electrode mounting includes a key top attached to the section, and a return spring provided between the key top and the upper part of the switch case, and the movable electrode attachment protrudes downward around the section and is attached to the upper part of the switch case. A guide pin is provided in sliding contact with the inner wall to guide the movement of the actuator, and the printed circuit board is formed with a guide pin relief hole into which the idle pin is received, and when the key top is pressed. , the actuator is configured to move the movable electrode toward the fixed electrode against the deflection force of the return spring and according to the guiding action of the inner wall of the switch case and the guide pin. A capacitive keyboard switch characterized by: (2) The capacitive keyboard switch according to claim (1), wherein the switch case is integrally formed with at least two keyboard housings. (3) The capacitive keyboard switch according to claim 1 or 2, wherein the return spring is a conical coil spring. (4) The switch case according to claim 1, 2, or 3, wherein a guide pin groove for receiving the guide pin is formed in the inner wall of the switch case. Capacitive keyboard switch. (5) The lower surface of the printed circuit board is covered with a dust cover. Capacitive keyboard switch. (6) A guide boss protruding into the guide pin relief hole of the printed circuit board is formed on the bottom of the switch case. The capacitive keyboard switch described in item (3), item (4), or item (5).