Communications: electrical – Audible indication – Percussion-type sound producer
Patent
1976-08-09
1979-04-03
Caldwell, Sr., John W.
Communications: electrical
Audible indication
Percussion-type sound producer
84 101, 340365C, 340166R, G06F 302, G10B 312
Patent
active
041480171
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 column 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.
REFERENCES:
patent: 3626406 (1971-12-01), Iritani
patent: 3660838 (1972-05-01), Gove et al.
patent: 3949365 (1976-04-01), Kashio
patent: 3955460 (1976-05-01), Southard
patent: 3974478 (1976-08-01), Griffith et al.
patent: 3981217 (1976-09-01), Oya
patent: 4041826 (1977-08-01), Oya
patent: 4051471 (1977-09-01), Hatano et al.
Caldwell Sr. John W.
Groody James J.
Nippon Gakki Seizo Kabushiki Kaisha
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