| 摘要 |
PURPOSE:To decrease the number of lines of a keyboard switch by providing the 3rd terminal to an elastic conduction part which conducts with a pushing operation and converting the analog voltage delivered from the 3rd terminal into the digital signals through an A/D converter. CONSTITUTION:A keyboard switch contains resistors 14a-14c which are printed in parallel on a substrate 11 with fixed intervals. These resistors are connected to output terminals 18a-18c via lead wirings 20a-20d respectively. While the lower electrodes 12a-12i are provided to switch operating parts 17a-17i and connected to the resistors 14a-14c, respectively. A spacer 13 having an opening (a) is set on the substrate 11 together with a surface sheet 17 containing an upper electrode 15. Thus the keyboard switch is completed Furthermore, the output terminal 18b is connected to an A/D converter and delivers the ana log voltage in response to the parts 17a-17i. As a result, the number of input and output terminals led from the keyboard switch part is reduced down to three in all. Then the states of many switches can be discriminated with said three terminals.
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