JPS5933919B2 - Key switch scanning and encoding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a key switch detection processing device useful in electronic musical instruments.

In keyboard electronic musical instruments such as electronic organs and pianos, an important issue concerns the interconnection between the keyboard switch and the sound source circuit.

A typical electronic organ has several manual keyboards, a pedal keyboard, and a bank of stop selection switches. If each keyboard and stop switch were connected to the circuit using separate connection wires, the wiring would be extremely complicated, resulting in high assembly costs and difficulty in repair and inspection. For this reason, it has been desired to simplify the wiring connections. One approach is to use time division multiplexing, where each keyboard switch is associated with a unique time slot.

The presence or absence of a pulse in a given time slot indicates whether the corresponding key is pressed. The advantage of this is that only a single multiplex line is required for interconnection between the keyboard and the instrument circuitry. However, it has two drawbacks. The first is that a unique time slot is used for each switch that is open or closed, so the time to scan all keyswitches is fixed. This results in an undesirable time lag between pressing or releasing the key and detecting this new condition. For example, if a switch is closed immediately after it is scanned, it will take one scan cycle to detect the closed state of that switch, even if no other switches are closed. The fixed time period has elapsed. Second, the use of multiple signals requires a separate decoder circuit to match the encoder, thereby complicating the required circuitry. A time division multiplex selection system is disclosed by Watson in US Pat. No. 3,610,799.

There, the keyboard switches are configured such that 12 note name switches for each octave of each manual keyboard and pedal keyboard are arranged in separate rows corresponding to the octave and keyboard, forming a matrix arrangement. ing. All column outputs of this array are connected to a single multiplex signal line. This array is scanned at a predetermined clock rate. In this way, during the first 12 clock cycles, 12 switches corresponding to the highest octave of one manual are scanned. Next, the 12 switches corresponding to the next octave of the same manual are scanned, and so on. The multiple waveforms presented on the common output line by this sequential scanning have pulses in time slots corresponding to the notes selected on the keyboard. The total time required to scan the keyboard array corresponding to the length of the multiplexed waveform is Kt. where K is the total number of switches in the matrix arrangement and t is the predetermined clock period. To utilize this multiplexed signal, a decoder circuit synchronized with the scanning clock is required.

In the device described by Watson, musical tones are generated by repeatedly reading musical waveforms stored in memory. The phase angle between sequential sample points in memory determines the fundamental frequency of the sound. Watson uses the decoded multiplexed signal to control this phase angle to determine the sound produced by the instrument. The decoder circuit reads the contents of the keyboard counter, which is clocked;
A signal for phase angle control is extracted by comparing the generation time of each pulse of multiple lines. Another time division multiplexing technique relates to mutual manual coupling in U.S. Pat.
It is disclosed by Mr. Cran in No. 87 specification.

By means of the manual coupling and the pulse-controlled sequential connection of the tone selection switches, wiring savings are made when operating several keys of one keyboard to produce complex tones in the same or different manuals. Rectifying the output of individual source waveform generators onto a common line for processing by a single waveformer or sounding device is disclosed in U.S. Pat.
No. 9885.

There, rectification of a delay line at a high rate compared to the frequency of the sound being generated is used to mix the outputs of the source waveform generators selected by a key switch onto a common line. Although this technique allows the use of a common timbre-determining circuit, it requires individual connection lines from each source waveform generator to the corresponding keyboard switch. It is an object of this invention to provide an apparatus for keyboard encoding which is useful for electronic musical instruments and which does not require a fixed scan rate independent of the number of switches selected.

To achieve this objective, it is proposed in the invention to operate the key switch device alternately in two modes. One is the “search mode” and the other is the “use mode”. In the search mode, scanning of the keyswitch device is advanced. When key switch operation is detected, the mode switches to usage mode. In the use mode, the scanning of the key switch device is interrupted and the identification data of the key switch whose operation is detected is made available for use. Thereafter, the use mode is terminated, and the search mode is returned again. Switches that are open or off are scanned at a faster rate than switches that are on. Savings in scanning speed are achieved because each newly closed or released switch is detected without significant delay. An encoded signal representing each selected key is retrieved. The encoded signal is provided over a small number of lines for direct use by electronic sound generators or other circuitry. Wiring savings are achieved without the limitation of fixed scanning times and without the need for decoding time during use. In accordance with the present invention, an apparatus is provided for asynchronously scanning and encoding a plurality of key switches.

Each key switch is arranged in a matrix of M groups, and each group is connected to N columns of common output lines, respectively. The group selection counter selects each group in turn in the search mode so that the closing switch in the selected group produces an output on the output line associated with that switch of the N output lines. These N output lines are scanned at a rapid rate until the line associated with the closed switch is detected. Encoded signals corresponding to the detected lines are generated by a code matrix. At the same time, scanning is interrupted and the mode of use is interrupted. This encoded signal, along with the output from the groove selection counter, identifies the selected switch.
After a delay time sufficient to permit use of the encoded keyswitch signal, operation of the use mode is terminated;
Returns to search mode and continues line scanning. The group select counter is incremented each time all N output lines are scanned, thereby allowing the next switch groove to be scanned. In this way the switch matrix is completely and constantly monitored. Scanning of the matrix output lines is accomplished, for example, by a line scan logic circuit having an N-ary circular shift register and N line selection gates.

Each gate, when opened by each stage of the shift register, connects a corresponding output line to the code matrix. If the line connected to the code matrix is for an open (off) switch, the code matrix will not produce a coded output. Based on this detection of no code output, the shift register is advanced at a high speed. In this way, only a minimum amount of time is spent in scanning the switches that are not selected. When the line associated with the closed (on) switch is made conductive to the code matrix, the utilization mode is entered and an encoded output is generated.

The shift register remains in the same state for a short enough hold time to utilize the switch identification code. Thereafter, the response provided by the utilization device or delay circuit, i.e. 10
The KW signal terminates the use mode and advances the shift register to the next state, whereby the next line is connected to the code matrix and the scan operation continues and returns to the search mode. The scanning speed is not fixed.

A short time T to effectively jump over unselected keys
s is spent and a longer time Td is required to encode and utilize the selected key. Therefore, if K switches are closed (turned on), the time Ts for scanning the selected switch is Tsktd;
The time Tc to jump over unselected switches is T
c=(K-k)Ts. However, K is the total number of switches in the matrix arrangement. Compared to the time required to scan the entire array of keyboard switches at a constant speed t=Td, which is required in the time division multiplexing method, the time saved Δt is: This time saving is especially useful for many manual keyboards, pedal keyboards,
This is important in electronic musical instruments that have stops and controls. The invention will now be described in detail with reference to the embodiments of the accompanying drawings.

In the key encoding device 10 of FIG. 1, the key switches to be encoded are arranged in a switch matrix circuit 11 consisting of M groups each containing N switches.

These switches are associated with N rows of output lines 12 and are selected by group selection counter 13 to select one of M groups.
The output line 12 from the one switch matrix circuit 11 provides an output (i.e. a switch on signal) only to the line corresponding to the closed (ON) switch in the energized group when one is energized. It is sequentially scanned by line scan logic 14 in cooperation with gate circuit 15.

Each line 12 is then connected to a code matrix circuit 17 via a bus 16. If the line 12 conducted to the code matrix circuit 17 is associated with the closing switch of the energizing group in the switch matrix circuit 11, a switch-on signal is being applied, and in response to this switch-on signal, the line 12 is switched on. A column identification code signal (hereinafter simply referred to as a code) that designates a line appears on the bus bar 18. This code, together with the bus 19 output from the groove selection counter 13 representing the activation group (ie, the selection signal), significantly identifies the closed switch in the matrix circuit 11. This encoded key data is supplied to appropriate utilization means 20-22. If the line conducted to code matrix circuit 17 is associated with an open (off) switch, code matrix circuit 17 will not provide a code output to bus 18.

This state of no code output means that the line scan logic 14
Then, the gate circuit 15 immediately connects the next line among the N output lines 12 to the code matrix circuit 17. Until the state in which no code is output ends, the no-code detection circuit 23 determines that no code signal is present on the bus 18, and based on this, it outputs a signal via the OR circuit 24 in order to satisfy the condition of the AND circuit 25. supply The output state of the OR circuit 24 instructs the search mode or usage mode. When the output of the OR circuit 24 is "1", the system operates in the search mode, and when it is "0", it operates in the use mode.In the search mode, the clock generator 26 is One clock pulse supplied from N-ary circular shift register 27
Take one step forward. As a result, the line selection gate circuit 15
The next subsequent matrix output line 12 is made conductive to the code matrix circuit 17. Scanning of keyswitches that are not selected proceeds at high speed. N-ary shift register 27 contains a single binary bit 1.

When each subsequent stage receives this binary signal 1, the corresponding line selection gate circuit 15 is operated in sequence. When the shift register 27 recirculates, a pulse is applied via line 28 to the counting input of the group selection counter 13.
This increments the contents of counter 13, thus allowing the next switch groove in matrix circuit 11 to be selected. Scanning continues such that the N output lines 12 corresponding to each switch of the newly selected groove are made conductive to the code matrix circuit 17 one by one.
The group selection counter 13 is M-ary, so all switch groups of the matrix circuit 11 are repeatedly selected in sequence. A coded output is produced on bus 18 each time line 12 associated with a close (on) switch is conducted to code matrix circuit 17. As a result, no output is generated from the no-code detection circuit 23, the output of the OR circuit 24 becomes "01", the usage mode is turned off, and the shift register 2
7 is kept as is.

This interrupts the scanning and makes the coded signals available to said means 20-22. When a response or 10 KW signal is provided to OR circuit 24 via line 30, the utilization mode is terminated and the search mode is returned to continue scanning. Receipt of this 70K'' signal provides a clock pulse to shift register 27, which causes the next matrix output line 12 to be scanned. It may be supplied from the delay circuit 31. In another embodiment, after the encoded key information is used, the use means 21, 22
The response signal may also be generated by. Here, the group selection counter 13 corresponds to a first scanning device, and the line selection gate circuit 15 and shift register 27
The clock generator 26 corresponds to a second scanning device, and the code matrix circuit 17, codeless detection circuit 23, OR circuit 24, and AND circuit 25 correspond to a control device. A specific example of the key encoding device 10 is shown in FIGS. 2A and 2B.

In the figure, the switch matrix circuit 11 has N (columns)
×M (rows) connected multiple switches 35-1, 35-
2, . . . 35-1 and a switch 35-j having a plurality of switching positions. Each switching position of switch 35-j is considered a separate switch in matrix circuit 11. A diode 36 is associated with each switch 35. For example, the switch 35 used for tone selection is operated by a keyboard or a pedal key. Other switches 35 are used for stop selection for attack and decay control, or for other functions in the electronic musical instrument. In the specific example of FIG. 2A, M
The stage cyclic shift register 13 is a counter 13 that sequentially selects M switch grooves in the matrix circuit 11.
used instead of. Each output stage 13-1, 13-2, . . . 13-M of the register 13' is connected to each of the group selection lines 19-1, 19-2, . . . 19-M, respectively. be done. Register 13! Only one of them is 2
The switch group 35 has a forward signal of 1 and corresponds to this.
is selected. All remaining stages of register 13' are binary signal 0's. Each time a pulse is received on line 28, the register 13 is shifted, causing only one signal 1 bit to pass to the next stage. This selects the next switch group in the matrix circuit 11. For example, if register stage 13-M has a single signal 1 bit, line 19-M selecting the associated groove will be at a positive voltage, which causes switch 3 connected to line 19-M to
Groups 5-1 to 35-N are selected.

All other group selection lines 1 except line 19-M
9 is the ground voltage. The next shift pulse on line 28 recirculates register 13, transfers the bit of signal 1 to stage 13-1, and selects the switch group associated with line 19-1. The output line 12 of the matrix circuit 11 is normally biased to ground voltage via resistors 37-1 to 37-N.

However, if there is a closed switch in the selected group, the corresponding output line 12 will be high. In other words, it becomes a positive voltage level supplied from the selection stage of register 1, and this becomes a switch-on signal.
Thus, as shown in FIG. 2A, when switch 35-2 is closed and line 19-M is selected, output line 12-2 goes high and all other output lines 1
2 is a low level. Of course, 1 in each selected groove.
The above switches may be closed, or none of the switches may be closed. The line selection gate circuit 15 includes NAND gates 15 to which each matrix output line 12-1 to 12-N is connected to one input side.
-1 to 15-N.

The other input side of the NAND gate 15 is connected to each stage 27-1 to 27-N of the N-ary cyclic shift register 27, respectively.
This register 27 also contains a single binary signal 1 which is shifted by the generation of a pulse from the AND circuit 25. The stage of the register 27 containing this signal 1 satisfies the condition of the corresponding NAND gate 15, and the conditions of the other NAND gates 15 do not hold. According to this arrangement, each matrix output line 12 is connected sequentially to the code matrix circuit 17 as the bits of a single binary signal 1 are circulated through the shift register 27.

For example, at the beginning of a line scan cycle, register stage 27-1 opens line select gate circuit 15-1 to connect output line 12-1 to input line 16-1 of the coat matrix circuit. By successive shifts of the register 27, the gates 15-2 to 15-N are sequentially opened and the corresponding output lines 12-2 to 12-N are sequentially connected to the code matrix circuit 17. When a bit of signal 1 is fed back to stage 27-1, the same pulse supplied via line 28 is applied to group selection register 13.
' is shifted, thereby selecting the next switch group of the matrix circuit 11. Code matrix circuit 17 consists of diodes 38-1 to 38-1 interconnecting input line 16 and output line 18.

Output line 18 is biased to a positive voltage + through resistor 39. If the output line 12 conducted to the code matrix circuit 17 is associated with a selected and closed switch in the matrix circuit 11, the matrix circuit 17 outputs a code on the output lines 18-1 to 18-Q. supply If the selected line 12 is associated with an open switch in the matrix circuit 11, all lines 18-1 through 18-Q remain high, indicating that no code output is present. represent. If group line 19-M is selected,
When line 12-1 is conducted to code matrix circuit 17, input line 16-1 is connected to corresponding switch 35.
Since -1 is open, it remains at a high level.

In this case, all of the output lines 18 remain high and no code output is generated. When gate 15-2 opens, line 16-2 connects to corresponding switch 35-2.
Since 2 is closed, the level is low. Therefore, output line 18-2, which is connected to line 16-2 through diode 38-5, goes low and line 18-2
-1 and 18-Q remain high, and this combination forms the code designating the selected line 16-2. Along with the group identification signal on line 19-M, the code on line 18 significantly identifies that switch 35-2 is closed. In the specific example of FIG. 2A,
The no-code detection circuit 23 consists of an AND circuit 23' to which line 18 is connected.

All of the lines 18-1 to 18-Q are at high level, indicating a no-code state, and the AND circuit 23
′ output is also at a high level. This output is OR circuit 2
4, the conditions of the AND circuit 25 are established, and the shift register 27 is supplied with a clock pulse. This causes the shift register 27 to shift and code matrix circuit 1
The next line 12 is made conductive to 7. Assuming no code is again generated on line 18, the next clock pulse is applied to register 27. In this manner, scanning continues at the clock speed of clock pulse generator 26 until a closed switch 35 is detected and the system is operated in search mode. When detected,
A code output appears on line 18, and at least line 18
One of -1 to 18-Q becomes a low level. the result,
The output of the AND circuit 23' is at a low level and the system is operated in the utilization mode. Reply i.e. “0”
Scanning is stopped until the K'' signal is sent from the utilization devices 21, 22 or from the delay circuit 31 via line 30. In the example shown, lines 19-1 and 19-2
The switch group of matrix circuits 11 selected by
-3 to 19-5 are used for the second device 21, and switches selected by lines 19-6 to 19-M are used to control the third device 22. used.

FIG. 2B shows an example of the arrangement of gate circuits for supplying encoded signals from the key encoding device 10 to each of the utilization devices 20-22. Group selection lines 19-1 and 19-2 are connected to OR circuit 40, respectively;
A gating signal is generated on line 41 when either of the first two groups is being scanned in matrix circuit 11.

This gate signal opens the AND circuit group 42 and connects the code feed lines 18-1 to 18-Q and the groove designation lines 19-1 and 19-2 to the first utilization device 20. Similarly, group selection lines 19-3 to 19
-5 is selected, the line 4 is connected to the OR circuit 45 connected to the lines 19-3 to 19-5.
The output AND circuit group 43 is opened by the signal supplied on the output AND circuit 43. This AND circuit group 43 supplies the code signal on line 18 and the group designation signal on lines 19-3 to 19-5 to the second utilization device 21. AND circuit group 46, which is opened by the signal on line 47 supplied via OR circuit 48, connects groove selection lines 19-6 to 19.
1M is selected, an encoded output is supplied to the third utilization device 22. When the encoded output is provided to the first utilization device 20, a reply or 10K8 signal is sent out by the delay circuit 31.

During this time, ie, when either groove select line 19-1 or 19-2 is selected, the resulting signal on line 41 also causes AND circuit 50 to open. When a code output is generated on line 18, an output is generated from NAND circuit 51. This output is the AND circuit 5
0 to the delay circuit 31. At the end of the delay time, the circuit 31 sends a 10K1 signal on line 30. As is clear from the above explanation, when switching from the search mode to the usage mode, the signal applied from the no-code detection circuit 23 (AND circuit 23'') to the OR circuit 24 contributes, and when switching from the usage mode to the search mode, the signal applied to the OR circuit 24 contributes to the switching from the usage mode to the search mode. The signal applied to the OR circuit 24 via 30 contributes (・
Ru.

Here, in the embodiment described above, switching to the use mode is performed in response to generation of an encode signal from the code matrix circuit 17. However, the present invention is not limited to this, and the point is that it is sufficient to switch to the usage mode in response to the detection of the switch in the operating state, and each output of the line selection gate circuit (NAND gate) 15 is used instead of the output of the code matrix circuit 17. Alternatively, the signal may be supplied to the AND circuit 23', thereby controlling the switching to the usage mode. In this way, when the operation switch detection output is generated from the line selection gate circuit 15, the use mode is immediately set in response to the detection, the scanning of the key switch is interrupted, and the operation switch is supplied via the gate circuit 15. The state of the detection output is fixed. In response to fixing the detection output in this usage mode,
The code matrix circuit 17 continuously outputs a code signal that identifies the operating switch, and
, 22. The key encoding device 10 of the present invention may be used with any type of utilization device, but particularly the type of keyboard type described by Deutsch in JP-A-48-90217 ``Electronic Musical Instruments''. Useful for electronic musical instruments.

In this electronic musical instrument, the fundamental frequency of each musical tone generated is determined by a frequency number selected from a frequency number storage device. The timbre of a musical tone is determined by a combination of pre-stored harmonic coefficients, each coefficient determining the amplitude associated with the Fourier components making up the generated musical waveform. Several combinations of such harmonic components may be individually stored and made available for selection by a stop selection switch.
Attack and decay are performed digitally by systematically varying the amplitude values of the Fourier components that are constructed in successive sound generation cycles. Key coding device 1
0 is used in such a computer towel gun, the first utilization device 20 comprises attack and decay control elements, the second utilization device 21 comprises a stop selection circuit, and the third utilization device 22 comprises a sound control element. It may consist of a generating circuit.

In such a configuration, lines 19-6 to 19-M
The switch groups selected by are two groups of manual keyboard and pedal keyboard switches for tone selection. The encoded signal supplied to the sound generation circuit 22 via the gate circuit 46 is used to recall the corresponding frequency number from memory. During this time, the coded signal supplied via the gate circuit 46 remains at the frequency number 3 memory address of the selected tone. Similarly, attack and decay control switches and stop selection switches are included in matrix circuit 11 and lines 19-1 and 19-1.
2 and 19-3 to 19-5 individually. As explained above, according to the present invention, it is possible to newly
A turned-off switch is quickly detected, and the wiring between the keyboard and other electronic musical instrument circuits is simplified.

The embodiments of this invention can be summarized as follows.

(1) In a device that scans and encodes a large number of switches arranged in a matrix as a whole, the switches in each group are connected to N columns of common output lines, and the switches in each group are individually selectable. circuit, and a scanning device that causes the encoding circuit to sequentially conduct the N columns of output lines, the encoding circuit being conductive when a switch in a selected matrix group corresponding to the rendered output line is closed. generates a column identification code signal identifying the encoded line, does not generate a column identification code signal when the switch is open, and causes the scanning device to perform the encoding when no column identification code signal is provided. an interleaving device for rapidly energizing the next output line to the circuit and stopping the scanning device for a sufficient time to make use of a column identification code signal if it is provided by the encoding circuit; A switch scanning and encoding device comprising:

(2) A groove selection device that sequentially selects each of the M grooves of the switches in the matrix so as to select the next switch group when the scanning device completes scanning of all N columns of output lines. The switch scanning and encoding device according to item (1) above, further comprising:

3) a utilization device for receiving two signals identifying closed switches in the matrix, namely the column identification code signal provided by the encoding circuit and a selection signal indicating the selected switch group; The switch scanning and encoding device according to item (2) above, further comprising:

4) The scanning device includes N gate circuits that connect each one of the N column output lines to the encode circuit when in operation, and a gate operation signal to only one stage and a non-operation signal to the other stages. and each register stage is connected to a corresponding one of said gate circuits for opening the gate circuit corresponding to the stage containing said gate operation signal, and in response to said interleaving device, said register stage is connected to a corresponding one of said gate circuits to open said gate circuit corresponding to said gate operation signal. The switch scanning and encoding device according to item (1) above, comprising an N-ary circular shift register whose position is shifted.

]) Only one stage contains a group selection signal and the other stages contain a non-selection signal, and each register stage is connected to a corresponding group of switches in the matrix in order to select a group corresponding to the stage containing the group selection signal. (4) further comprising: an M-ary cyclic shift register connected to each of the scanning device; and means for shifting the M-ary cyclic shift register each time the N-ary register in the scanning device is recirculated.
Term switch scanning and encoding device. (6) The skipping device includes a no-code detection circuit that supplies a no-code detection signal only when no code signal is supplied from the encoding circuit in accordance with the output of the encoding circuit; a response device that generates a response signal for a predetermined period of time after the code has been detected, and the scanning device conducts the next line to the encoding circuit in response to the no-code detection signal or the response signal.
1) Switch scanning and encoding device. (7) In the switch scanning and encoding device according to item (6), the encoding circuit has a diode code matrix, and the no-code detection circuit has a gate circuit that receives a code-containing parallel line from the code matrix. A switch scanning and encoding device comprising:

(8) In the switch scanning and encoding device according to item (7), the reply device is driven when a code signal from the code matrix is generated, and is delayed by supplying the reply signal after a predetermined time delay from this generation. A switch scanning and encoding device comprising a circuit. (
9) Item (1) above, further comprising a utilization device that utilizes the code signal and supplies a response signal after the use, and the response signal causes the scanning device to restart scanning of the output line. switch scanning and encoding device.

(3) The switch scanning and encoding device according to item (1), which is attached to an electronic musical instrument having a key operation switch arranged in a matrix and a tone generating circuit responsive to the code signal.

(self) A switch matrix circuit having switches arranged in M groups, in which the switches of each group are connected to N columns of common output lines, and each of the M groups being connected to one group at a time. a groove selection device that selects and supplies an output signal only to the output line corresponding to the actuated switch in the selected groove;
a code matrix circuit having inputs of columns, and one of the output lines is connected to a corresponding one input side of the code matrix circuit, respectively, and corresponds to the output line connected to the code matrix circuit in the selected group. an N-line selection gate circuit that causes the code matrix circuit to provide a code output only when a switch is activated; an N-ary circular register device that sequentially activates the line selection gate circuit; and an output of the code matrix circuit. When a state in which there is no code output from the code matrix circuit is detected in response to the above, the register means rapidly operates the next line selection gate circuit, and when the code output is supplied from the code matrix circuit. a shift device for activating the next line select gate circuit after a sufficient time has elapsed for the register device to utilize the code output.

In the z-th switch scanning and encoding device, the group selection device comprises an M-ary circular register having a line selection signal in only one stage, and when each of all M stages receives this line selection signal, the Each stage of registers is connected to the switch matrix circuit to select a corresponding one of M switch groups, and each stage of registers is connected to the line selection signal each time all of the line selection gate circuits are activated by the register device. A switch scanning and encoding device characterized in that the number of stages is shifted from one stage to the next. Moat Switch scanning of the σ-th term and . In the encoding device, the shift device includes a logic gate that is connected to the code matrix circuit and supplies a predetermined signal only when a code output is not supplied from the code matrix circuit, and a logic gate that is responsive to generation of a code output from the code matrix circuit. a response device for supplying a delayed response signal; and means for supplying shift pulses to the N-ary register device in response to the logic gate signal or the response signal. Device.

I4) further comprising means for providing for external use said code output and optionally a signal representative of said selected group of switches, said code output and said display signal together identifying said actuated switches; The switch scanning and encoding device according to the above item (self).

(to) Incorporating the switch scanning and encoding device of the above item (self), and comprising a keyboard-operated tone selection switch and other switches for controlling the characteristics of the generated musical tones, and these switches are the switches of the matrix circuit. an electronic musical instrument further comprising a musical tone generating circuit and a small number of lines supplying said code output to said musical tone generating circuit. (to) The musical tone generation circuit includes a memory that stores in advance a frequency number that determines the fundamental frequency of the generated musical tone, and the code signal generated by the operation of the tone selection switch corresponds to the address of the frequency number memory. Section electronic musical instrument.

[Brief explanation of the drawing]

FIG. 1 is an electrical block diagram showing one embodiment of the key switch detection processing device according to the present invention, and FIGS. 2A and 2B are schematic electrical circuit diagrams showing specific examples of the circuits of each part in FIG. 1. 10... Key coding device, 11...
Switch matrix circuit, 13...Group selection counter, 14...Line scanning logic, 1
5...Line selection gate circuit, 17...
-Code matrix circuit, 20-22...Using device, 27...N-ary shift register.

Claims (1)

[Claims] 1 Divide multiple key switches into M groups and N columns,
A switch matrix circuit in which one end of each key switch is commonly connected to a group line corresponding to each group, and the other end of each key switch is commonly connected to a corresponding column line for each column, and the switch matrix circuit a first scanning device that sends a selection signal for sequentially selecting the group lines to the group line, and in response to the selection signal that sends a switch-on signal to the column line corresponding to the column to which the operating key switch belongs; a second scanning device that sequentially specifies the column lines of the matrix circuit and extracts the signals of each column line; and when the switch-on signal is extracted by the second scanning device, a column identification code corresponding thereto; a control device for transmitting a signal and causing scanning by the first and second scanning devices to be paused for a predetermined period of time, and for causing the scanning to occur rapidly when the switch-on signal is not taken; and a key switch detection processing device for an electronic musical instrument, which obtains a code signal for identifying an operating key switch constituted by the column identification code signal.