Importance

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Abstract

A device for detecting a key switch operation capable of detecting an operating state of a plurality of key switches which are commonly connected with respect to each row line (block line) at one terminal thereof and commonly connected with respect to each column line at the other terminal thereof, thereby constituting a switch matrix. If a signal is provided on all column lines, the signal is transmitted to a block line through a key switch which is in operation and thereby a block including the key switch in operation is detected. A signal is then supplied from the detected block line to a column line only through the key switch in operation in the detected block. The position of the key switch in operation is known by detecting the columnn line on which the signal arrives. According to an embodiment of the invention, capacitance elements are provided both on the block lines and on the column lines for effecting delivery of the signal by charging and discharging of these capacitance elements. There is also disclosed a construction in which detected blocks are once stored in a memory and positions of key switches in operation in the detected blocks are detected and stored block by block. The stored blocks and key switch positions are codified to produce key codes identifying the key switches in operation.

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First Claim