JPS63205017A - Keyboard switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an operating keyboard switch used in a control device for a high-frequency heating device.

Conventional technology In recent years, high-frequency heating devices have been manufactured that utilize microcomputers (hereinafter referred to as microcomputers) to perform complex cooking sequences and utilize various sensors. In devices having the above, an operation means using a keyboard 1 as shown in FIG. 3 is used to convey the operator's intention. In the conventional manual key system, a keyboard is generally used, as shown in Figure 4, where each key 2 uses a switch consisting of two contacts, forming a matrix that combines the output signal system of the microcomputer and the input signal system. However, a manual key system has also been proposed, as shown in FIG. 5, which uses an analog input terminal and a digital input terminal and is equipped with a key switch in which one key 3 has three contacts. In the latter key manual method, as shown in Figure 6, a spacer 6 is sandwiched between the lower electrode 4 and the upper electrode 6, an aluminum foil 7 is further layered to shield static electricity, and letters are written on the polyester film on top of the spacer 6. It is common to have a structure in which printed character sheets are stacked one on top of the other.

Problems to be Solved by the Invention However, in the case of such a key switch, the contact electrode is separated into two surfaces, the upper and lower surfaces, so the lead wire from the electrode also needs to be drawn out from the two surfaces. Ta. In FIG. 6, 9 is a lead line of the lower electrode, and 10 is a lead line of the upper electrode. These electrodes shown in Figure 6 are made by printing a conductive paint containing carbon or silver paste as a main component on a plastic film such as polyester, then cutting the plastic film, stacking them on top of each other, and applying adhesive or the like. It is pasted together. Therefore, if there is a protrusion for the leader line, the area used for the film increases, the cost increases, and the precision of bonding the leader line is required, making it difficult to manufacture. The present invention solves these conventional problems, and the upper electrode 5 shown in FIG. 6 has a simple structure.
By eliminating the need for a keyboard switch, the present invention provides an excellent keyboard switch that is inexpensive and easy to manufacture.

Means for Solving the Problem The keyboard switch of the present invention has three
A keyboard switch consisting of a contact structure with two electrodes, two of the three electrodes of one switch are arranged on one plane, and the remaining one electrode uses metal foil, which was conventionally used as a static electricity shield, as an electrode. By doing so, a structure was created in which no upper electrode film was required. In addition, by printing a conductive carbon paint on the metal foil contacts, the structure prevents the metal from rusting and unstable contact.

Furthermore, the metal foil that is the upper electrode is connected to the chassis to protect the control device from static electricity, and the chassis is used as a conductor.

Function The keyboard switch of the present invention can eliminate the need for the conventional upper electrode film by using the metal foil conventionally used for the purpose of shielding static electricity also as the upper electrode. Furthermore, by printing the contact portion of the metal foil with a carbon-based conductive paint, it is possible to prevent poor contact due to oxidation of the metal. Furthermore, conventionally, metal foil has been connected to the chassis as an electrostatic shield, but in the present invention, by connecting the chassis to the potential of the upper electrode of the control circuit, the chassis can be used as a conductor. .

Embodiment Hereinafter, a keyboard switch according to an embodiment of the present invention will be explained with reference to the drawings. As shown in FIG. 1, the lower film 11 with two electrodes of the keyboard switch, which has a contact structure with three electrodes in one key switch, has lead wires 12 and 13 connected to the two electrodes. .

Furthermore, there is a lead wire 16 passing through the resistor 14 corresponding to Ro in FIG. An upper electrode 17 made of aluminum foil is placed between the lower film 11 and a spacer film 16 having a hole at the contact point. Lower electrode 1 of aluminum foil 17
On the side facing 1, printing 18 is applied only to the contact portion using carbon-based conductive paint. Furthermore, aluminum foil 17
There is a character sheet 19 made of polyester film on which characters are printed. Aluminum foil 17 and character sheet 1
9 has screw holes 20 and 21 for screw tightening. Second
The figure shows the keyboard switch 22 shown in FIG. 1 connected to a metal plate 23, which is a part of the chassis, using screws 24. The aluminum foil 17 of the keyboard switch 22 is electrically connected to the chassis by tightening the screws. A printed circuit board 25 including a control circuit is further connected to the metal plate 23 using screws 26, 27, and 28. An electrode 29 is formed of copper foil around the screw hole on the side of the printed circuit board 26 facing the metal plate 23. This electrode 29 is the chassis ground portion 3° of the +5V line shown in FIG. By tightening the screws 24 and 26, the upper electrode of the keyboard switch 22 (FIG. 1 17) and the control section (chassis ground 30 shown in FIG. 5) are connected. In addition, in FIG. 2, 30 is an operation panel.

Effects of the Invention As described above, the keyboard switch of the present invention has a simple structure, and by using the metal foil conventionally used as an electrostatic shield as the upper electrode, it is possible to eliminate the upper electrode film required in the past. This allows for significant cost savings in materials and assembly. In addition, the electrical connection of the upper electrode is made by fixing the keyboard, tightening screws to the chassis to shield static electricity, and fixing the control circuit board to the chassis, so it is possible to connect electrically without using lead wires. A connection is made, eliminating the need for additional parts or connection work for electrical connections. This makes it possible to realize a device that is easy to assemble and is inexpensive, which is very practical in practice.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of a keyboard switch according to an embodiment of the present invention, Fig. 2 is an exploded perspective view of the keyboard switch attached to the operating section, Fig. 3 is a perspective view of a general electronic switch, and Fig. 4 is an exploded perspective view of a keyboard switch according to an embodiment of the present invention. FIG. 5 is a circuit diagram of a conventional keyboard, FIG. 5 is a wiring diagram of another keyboard, and FIG. 6 is an exploded perspective view of the conventional keyboard. 11...Lower film, 12...Leader wire, 14...Resistor, 16...Spacer film, 17...Aluminum foil, 18...
...Carbon printing, 19...Character sheet, 2o
...screw hole, 22 ...keyboard, 2
3...Metal plate (shear 7), 25...
Printed circuit board, 29... Chassis ground electrode,
30...Operation panel. Name of agent: Patent attorney Toshio Nakao and 1 other person16
- Suko - Riki Rum Figure 3 r = ----------Co

Claims (3)

[Claims] (1) A keyboard switch consisting of a contact structure with three electrodes in one switch, in which the first and second electrodes of the three electrodes of one switch are arranged on one plane, and the remaining one electrode is A keyboard switch having a structure in which a certain third electrode is made of a metal foil having a static electricity shielding effect and is arranged with a small space maintained on a plane facing the first and second electrodes. (2) A film of conductive paint consisting mainly of carbon is formed on the third metal foil electrode at the contact point between the third electrode and the first and second electrodes. keyboard switch. (3) The keyboard switch according to claim 1, wherein the metal foil serving as the third electrode is electrically connected to the chassis of the main body.