JPS643721A - Key input device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of malfunctions of a key input device without using a diode nor an exclusive reading line, by distributing no key to one or both of the crossing positions between a specific 1st or 2nd key scan line and a 2nd or 1st key reading line. CONSTITUTION:A code key 48 is set at the crossing position between a scan line D5 and a read line K7 together with a shift key 55 set at the intersecting point between a scan line D6 and a red line K6, and an X key 47 set at the intersecting position between the line D5 and the line K6 respectively. When these keys are pushed, the input terminals K6 and K7 of a reading board K are set at '0' in case an arithmetic control par 61 scans the line D5. Thus it is decided that both keys 47 and 48 are pushed. While the push of the key 55 is decided since the terminal K6 is set at '0' when the line D6 is scanned. In this case the current flows on a read, line K7 to a terminal d6 via each key together with '0' inputted to a terminal d7. However no key is distributed at the crossing position between both lines D6 and K7 and therefore the signals are neglected to cause no malfunction. Furthermore no data is confirmed when three keys including the key 55 and other two keys except the key 48; while data are confirmed when the key 48 and >=3 keys except the key 55 are pushed.