Device for detecting a key switch operation
First Claim
1. A device for detecting a key switch operation comprising:
- a key switch matrix circuit including a plurality of key switches arranged in rows and columns, said rows representing respective blocks of the key switches;
first means for detecting simultaneously all blocks in which key switches in operation exist;
second means for simultaneously detecting all columns in a single one of said detected blocks on which the key switches in operation are disposed, said column detecting being carried out for one block after another, for each of the separate blocks detected by said first means; and
control means for causing said second means to implement the column detection for one block at a time with respect to each of the blocks detected by said first means;
each of said key switches in operation being identified by a combination key code designating the single detected block and the column on which said key switch in operation is disposed.
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Accused Products
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.
11 Citations
12 Claims
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1. A device for detecting a key switch operation comprising:
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a key switch matrix circuit including a plurality of key switches arranged in rows and columns, said rows representing respective blocks of the key switches; first means for detecting simultaneously all blocks in which key switches in operation exist; second means for simultaneously detecting all columns in a single one of said detected blocks on which the key switches in operation are disposed, said column detecting being carried out for one block after another, for each of the separate blocks detected by said first means; and control means for causing said second means to implement the column detection for one block at a time with respect to each of the blocks detected by said first means; each of said key switches in operation being identified by a combination key code designating the single detected block and the column on which said key switch in operation is disposed. - View Dependent Claims (2, 3, 4, 5)
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6. A device for detecting a key switch operation in which key switches in a matrix are connected at row conductor and column conductor terminals thereof to a circuit for detecting the operation of the key switches, comprising:
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capacitance elements provided between each matrix row and column conductor and ground; first charging-discharging means for charging or discharging the capacitance elements provided on the row conductor terminals so that the charge-discharge condition of each such capacitance element indicates whether at least one switch in the corresponding matrix row is in operation; second charging-discharging means for charging or discharging the capacitance elements provided on the column conductor terminals only through the key switches in operation in one of the matrix rows in which there is at least one switch in operation, as indicated by the charge-discharge condition of said capacitance element on the corresponding row conductor terminal; and detection means responsive to the charge-discharge condition of each capacitance element on the column conductor terminals, as caused by said second charging-discharging means, for detecting which columns in said one matrix row contain key switches in operation. - View Dependent Claims (7)
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8. A system for detecting actuated key switches in a matrix, comprising:
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source means for providing signals in parallel to all columns of said matrix, a block memory having a storage cell associated with each row of said matrix, said block memory storing the signals received from said source means via said matrix so as to indicate which rows contain at least one actuated switch, single block extraction means for reading our row-indicating signals stored in said block memory one at a time, in sequence, and for providing a signal to said matrix along the single row corresponding to the currently read-out row-indicating signal, a note memory having a storage cell associated with each column of said matrix, said note memory storing signals received from said block extraction means through said matrix so as to indicate which columns in said single row contain actuated switches, note extraction means for reading pout column-indicating signals from said note memory one at a time, in sequence, each such read out column-indicating signal and the concurrently read out row-indicating signal together uniquely identifying a corresponding actuated switch in said matrix, and timing control means connected to said block extraction means and to said note extraction means, for causing said single block extraction means to read out the next sequential row-indicating signal only after all of the column-indicating signals for said single row have been read out by said note extraction means.
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9. A system for detecting the operation of individual switches in a matrix, comprising:
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a matrix of row conductors and column conductors, each switch being connected at an intersection of said matrix, there being a capacitance between each conductor and ground, first means for precharging all of the capacitances of each column conductor, whereby the capacitance of each row conductor which is connected to any column conductor by at least one closed switch will be initially charged second means for subsequently charging all of said row conductor capacitances except one that was previously charged by said first means, said one row capacitances being discharged, whereby all of said column capacitances for column conductors that are connected to said one row conductor by a closed switch will be discharged, all other column capacitances remaining charged, and means, responsive to the resultant charge condition of said row and column capacitances, for uniquely indicating the matrix position of closed switches in said matrix. - View Dependent Claims (10)
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11. A device for detecting a key switch operation comprising:
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a key switch matrix circuit including a plurality of key switches arranged electrically in rows and columns each connected via a unidirectional element between row conductors and column conductors, said rows representing respective blocks of the key switches; first means for detecting simultaneously all blocks in which key switches in operation exist; second means for simultaneously detecting all columns in a single one of said detected blocks on which the key switches in operation are disposed, said column detecting being carried out for one block after another, for each of the separate blocks detected by said first means; control means for causing said second means to implement the column detection for one block at a time with respect to each of the blocks detected by said first means; first capacitance means provided between each row conductor and ground; first voltage applying means connected to said first capacitance means to apply thereto a first level voltage which would forward bias said unidirectional elements for a first predetermined period as preparation for the block detection; second capacitance means provided between each column conductor and ground; second voltage applying means connected to said column conductors to apply thereto a second level voltage which would forward bias said unidirectional elements for a second predetermined period so that the voltage of such row conductor that is connected to key switches in operation is changed from said first level voltage to said second level voltage, and this change being detected by said first means; said second level voltage being applied also to said second capacitance means for this second predetermined period as preparation for the note detection, said first means being arranged to apply said first level voltage to the row conductors of the detected blocks one at a time for a third predetermined period so that the voltage of such column conductor that is connected to a key switch in operation is changed from said second level voltage to said first level voltage, and this change being detected by said seond means; each of said key switches in operation being identified by a combination key code designating the single detected block and the column on which said key switch in operation is disposed. .Iaddend. .Iadd.
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12. An electronic musical instrument comprising a key code generator which is composed of means for sequentially scanning with a first clock a plurality of blocks into which a plurality of key switches having contacts to be closed are divided, a priority selector for selectively outputting with a second clock closure information of each block sequentially in accordance with predetermined priority, means for inhibiting the first clock with an operation signal of the priority selector during its operation to temporarily stop the block scanning and means for converting the output from the priority selector and information of the block scanning to key data of a binary code and means for detecting completion of one scanning to output a variable frame signal of one frame time determined by the number of blocks and the number of closed key switches the converting means operating during each time frame.
Specification