JPS5923411B2 - keyboard switch - Google Patents

Description

[Detailed Description of the Invention] The present invention utilizes the dielectric constant of a laminate to form a capacitor, and applies pulses to the electrodes of this capacitor to detect changes in the signal by touching the common electrode with a finger. The present invention relates to an improvement of a keyboard switch that can be used to obtain a switch function, and is intended to enable a matrix-like arrangement.

Conventionally, as shown in FIG. 1, a ground electrode 2 is provided on one side of a laminated board 1, and an input electrode 3 and an output electrode 4 are provided at positions corresponding to the ground electrode 2 on the other side. A keyboard switch that equalizes the capacitance with the ground electrode 2, continuously applies constant pulses to the input and output electrodes 3 and 4, and uses the change in signal when a finger touches the ground electrode 2 as a switching signal. It was being developed. This first
The equivalent circuit in the figure is as shown in FIG. 2, where C1 is the capacitance between the input electrode 3 and the ground electrode 2, and C2 is the capacitance between the output electrode 4 and the ground electrode 2, which is C1-C2. however,
The third pattern is a set of two such capacitors.
When a plurality of them are arranged in parallel as shown in the figure, it is impossible to arrange them in a matrix because the signal input/output wiring 5 and 6 must be done in the layered board 1 on which the input electrodes 3 and output electrodes 4 are formed. Tonarro.

To solve this problem, a three-layer structure is required.

In this case, a process is required to make a multilayer wiring board, and heat pressing is usually not possible with ordinary phenol or paper epoxy base materials, and it is limited to glass cloth or glass epoxy base materials due to cost considerations. There were also major obstacles in selecting materials. The present invention eliminates the drawbacks of the prior art as described above.

Embodiments of the present invention will be described below with reference to FIGS. 4 to 8.

First, in FIG. 4, reference numeral 1 denotes a laminate made of phenol or paper epoxy, and an input electrode 8 is provided on the bottom surface of this laminate 1, and an output electrode 9 is provided on the top surface.

Note that an output electrode may be provided on the bottom surface and an input electrode may be provided on the top surface. The input/output electrodes 8 and 9 are formed so as not to face each other, and an adhesive layer or a flexible substrate is provided on the upper surface of the laminate T. is the human output electrode 8 above.
, 9 are formed.

Then, the ground electrode 11, the input electrode 8, and the ground electrode 11
The capacitances of the output electrode 9 and the output electrode 9 are configured to have the same value.

That is, the electrode 8 formed on the bottom surface of the laminate 7 has a large area, and the electrode 9 formed on the top surface has a small area, and the capacitance C of each is made equal. is as shown in FIG. In FIG. 4, 12 is an input wiring, and 13 is an output wiring. In this configuration, if a constant pulse signal is applied to the input wiring 12, a constant signal is obtained from the output wiring 13, but when a human finger or the like touches the ground electrode 11, a signal obtained from the output wiring 13 is obtained. changes, and the change in this signal is used as a switching signal to function as a keyboard switch.

With this configuration, a matrix arrangement as shown in FIG. 6 is possible.

Next, the specific manufacturing process will be explained.

First, in FIG. 7, copper foil 14 is placed on both sides as shown in A.
As shown in B, on the top surface of the laminated board 15, there is a wiring for inputting a signal and an input electrode 16 that will be the electrode of the capacitor connected to this wiring, and on the bottom surface there is a wiring for drawing out the output and an output electrode that will be the electrode of the capacitor. 17 is formed by etching.

These electrodes 16 and 17 form a pair with each other, and are formed at positions that do not face each other with the laminated plate 15 in between. In addition, the input/output wiring must be in the form of orthogonal lines via the laminated board 15.

A non-conductive adhesive 18 is applied to the upper surface of such a laminate 15 as shown in C, a protective coating agent or adhesive 19 is applied to the lower surface, and then the above adhesive is applied as shown in D. A ground electrode 20 having an area corresponding to the electrodes 16 and 17 is formed on the electrode 18 by plating, vapor deposition, or printing.

As another example, as shown in FIGS. 8A to 8F, first, as shown in A, a laminate 15 with copper foil 14 pasted on both sides is used.
As shown in B, a manual electrode 16 is formed on the upper surface and an output electrode 17 is formed on the lower surface by etching.
As shown in D, a double-sided adhesive 18 is provided on the upper surface, a protective coating layer or adhesive layer 19 is provided on the lower surface, and a flexible substrate 22 with a metal 21 pasted on the upper surface is pasted on the double-sided adhesive 18 on the upper surface as shown in D. Then, as shown in E, an etching resist layer 23 is provided on the metal 21 and etched, and as shown in F, a ground electrode 20 corresponding to the input/output electrodes 16 and 17 is provided on the flexible substrate 22. Ru.

As described above, the keyboard switch of the present invention allows freedom in selecting the base material, has a three-layer structure using adhesive, eliminates the need to use the heat press process in the multilayer board manufacturing process, and does not cause deterioration in characteristics and costs. This is advantageous in terms of aspects, and also enables matrix arrangement, allowing a large number of switches to be arranged in a small space, which is of great industrial value.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a conventional capacitor type keyboard switch, Fig. 2 is an equivalent circuit diagram, Fig. 3 is a top view showing the same arrangement, and Fig. 4 is an embodiment of the keyboard switch of the present invention. 5 is an equivalent circuit diagram, FIG. 6 is a top view showing the matrix arrangement, and FIGS. 7A-D and 8A-F are process steps showing the method of manufacturing the keyboard switch. FIG. 7...-...Laminated board, 8...Input electrode, 9...
... Output electrode, 10 ... Adhesive or flexible substrate, 11 ... Earth electrode, 12 ...
...Input wiring, 13...Output wiring.

Claims (1)

[Claims] 1. Input wiring and input electrodes are provided on one surface of the laminate; output wiring and output electrodes are provided on the other surface of the laminate; A keyboard switch characterized in that a ground electrode is provided so that the capacitance obtained between the input and output electrodes is equal. 2. The keyboard switch according to claim 1, wherein a metal layer provided on a flexible substrate is used as the ground electrode.