JPS6351014A - Membrane keyboard switch - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a membrane keyboard (hereinafter referred to as membrane switch) composed of a plurality of key switches.
It's about switches.

2. Prior Art Conventional high frequency heating device (not shown) shown in FIG. 5, for example.
The control circuit includes a control block composed of a membrane switch 2 that selects various cooking menus, and a microcomputer 1 that determines which key is selected and executes appropriate system control. To briefly explain the membrane switch, FIG. 6 shows a part of the external appearance of the membrane switch, and FIG. 7 shows a cross-sectional view thereof.

A base film 7 is adhered to a fixing plate 14, a lower electrode (for example, silver paste) is printed on it, and a spacer 12 is formed by cutting out only a portion corresponding to the key bat 6.
is pasted, and further the upper electrode sheet 11 is pasted thereon. An upper electrode (for example, silver paste) 13 is printed on the sheet 11, and when the key butt part 6 is pressed with a finger 15, it contacts the lower electrode 8 and the signal is transmitted to the microcomputer via the connector 3 shown in FIG. It is input to the input terminal section.

Incidentally, since the lower electrical part of the base film lead part 7' is exposed and easily damaged, it is coated with an insulating paint for protection.

Problems to be Solved by the Invention However, in such a control circuit, the pull-down resistor (or pull-up resistor)
In microcomputer 1 that does not have a built-in
When the membrane switch 2 is not pressed, the input/output terminals of the microcomputer 1 are floating and the operation becomes unstable, so it is necessary to add an external pull-down (or pull-up) resistor 4. However,
Space is required on the printed circuit board to mount the resistor 4. In particular, as the number of keys in a membrane switch increases, more resistors are required, which increases costs, and also increases the space on the printed circuit board, making it difficult to miniaturize.

The present invention solves these conventional problems, and aims to reduce the size of a printed circuit board and reduce the total cost.

Means for Solving the Problems In order to achieve the above object, the membrane switch of the present invention includes a pull-down (or pull-up) resistor for the input/output terminal section of the membrane switch of a microcomputer using a printed resistor inside the membrane switch. The configuration is such that the common part of the pull-down (pull-up) resistor is connected to the printed circuit board with one conductive pattern in the same way as other signal lines.

Function The membrane switch of the present invention has the effect of reducing the size of the printed circuit board and reducing the total cost.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings.

As shown in FIGS. 1 and 4, a printed resistor connection pattern (silver base, etc.) 16 is connected in the middle of the lower electrode 8 for connection to the printed circuit board of each key 18, and the tip thereof A printed resistor (for example, metal glaze) is connected to the resistor. The electrical common part of these pull-down resistors 17 is made into a common pattern 2Q, and is led to the base film lead part 7/ in the same way as the other lower electrode 8 patterns, connected to the connector 3 on the printed circuit board, and connected to OVs of the printed circuit board circuit. Ru.

Here, since the pattern 16 for connecting the pull-down resistor and the pattern of the lower electrode 8 partially intersect with each other, electrical contact may cause malfunction, so the following countermeasures are taken. To explain based on FIG. 3, the base film 7 is first patterned with the lower electrode 8, and then the base film lead portion is patterned, except for the part where the lower electrode 8 and the pull-down resistor connection pattern 16 are connected. A protective coat 9 similar to that applied in the above is coated on the lower electrode 8. A pull-down resistor 17 is printed thereon, and a pull-down resistor connection pattern 16 and a pull-down resistor common pattern 20 are printed on the lower electrode 8 and the pull-down resistor 1.
7 and all connections. With this configuration, the two different conductive patterns are insulated by the protective coat 9 and do not come into contact with each other.

Effects of the Invention As described above, the membrane switch of the present invention provides the following effects.

(1) Pull-down (or pull-up) resistors can be eliminated from the printed circuit board, making it possible to downsize the printed circuit board.

In addition, the membrane switch side also has a built-in pull-down resistor using multi-layer wiring and has an external size that is almost the same as the conventional one.

(2) Many printed resistors can be manufactured at the same time, so
It is cheaper than the conventional method consisting of single items.

In particular, the greater the number of keys, the greater the effect.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a plan view and a side view of a membrane switch with a built-in resistor, which is an embodiment of the present invention, and Fig. 2 is a plan view and a side view of the upper electrode portion of Fig. Figure 3 is a front view and side view of the main parts of the resistor and lower electrode section, Figure 4 is a circuit diagram of an embodiment of the present invention, Figure 5 is a circuit diagram of a conventional example, and Figure 6 is an external view of a conventional membrane keyboard switch. Partial plan view of figure 7
The figure is a sectional view of FIG. 6. 1...Microcomputer, 2...
Membrane keyboard switch, 3... Connector, 4... Pull-down resistor, 8... Lower electrode, 9... Protective coat, 11...
Upper electrode, 17...Pull-down resistor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 2/'1, Figure 4, Figure 5, Figure 6, Figure 7, Figure 1, etc.

Claims (2)

[Claims] (1) In a key matrix with multiple combinations of upper electrodes and lower electrodes facing each other, the resistors connected to the input/output parts of the key matrix can be connected to the upper or lower electrodes using printed resistors. Membrane keyboard switch configured on the same surface. (2) The membrane keyboard according to claim 1, wherein an insulating protective coating, which is used for external connection leads, is applied to the portion where the different polarity patterns intersect to prevent cross contact. switch.