JPS6210438B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic musical instrument that detects key depression information by scanning a keyboard.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic musical instrument in which keyboard switches are arranged and connected in a matrix, and the envelope of musical tones can be freely controlled.

Another object of the present invention is to provide an electronic musical instrument in which keyboard switches are arranged and connected in a matrix, and the volume of musical tones can be changed depending on the speed at which the keys are depressed.

Another object of the present invention is to enable the sound source circuit of an electronic musical instrument to be easily integrated into a single chip.

That is, the present invention dynamically stores and retains key press information, press speed information, envelope information, etc. of each keyboard arranged in a matrix in a relatively small capacitor, making it extremely simple and easy to integrate. The aim is to obtain an electronic musical instrument suitable for circuitization.

The details of the present invention will be explained below with reference to embodiments and drawings.

FIG. 1 shows the sound source and keying section of an electronic organ which is one embodiment of the present invention, and FIG.
This is an example of the configuration of blocks 101 to 188 in the figure.

An original oscillation clock signal with a frequency of about 2 MHz is input from input terminal 1, and a reset signal to the frequency divider is input from input terminal 2. 1/4 frequency divider 3
For example, it is constructed by connecting two 1/2 frequency dividers in series. Frequency dividers 4, 5, 6, and 7 are all 1/
It is a 2 frequency divider and continuously divides the output of the 1/4 frequency divider 3. The 3-pit decoder 8 is a 1/2 frequency divider 5~
It decodes the output of 7 and outputs 8 sequential pulses. Further, a 2-bit decoder 10 decodes the outputs of the 1/4 frequency divider 3 and the 1/2 frequency divider 4, and outputs four pulses sequentially.

On the other hand, from the source signal input to input terminal 1, top octave divider 12 converts keyboard C ₇
……Fundamental frequency of 12 tones of C ₆ #, i.e. approximately 8372
Signals with 12 different frequencies are created by dividing the range from Hz to approximately 4186Hz so that the ratio is approximately 12√2 times, and each is supplied to the terminal 1004 of the circuit blocks 101, 102...112 (see Figure 2). be done. The signal applied to the end terminal 1004 is a 1/2 frequency divider 100.
The frequency is divided by 1/2 by 1, outputted from a terminal 1005, and supplied to an input terminal 1004 of the next stage block. With such a connection, blocks 101 and 10
2, . . . 112 correspond to the sounds of C ₈ , B ₇ , . . . C ₇ #, and similarly blocks 113, 114, .
24 corresponds to the tones of C ₇ , B ₆ , . . . C ₆ #, and similarly blocks 125 to 188 correspond to the tones of each octave.

In _each block _{101 to 188 ,} as shown in FIG _. It is connected to the gates of input transistors Q ₅ and Q ₈ of each of the two analog gates.

This concludes the explanation of the sound source signal frequency dividing section.
Next, the keyboard scanning section will be explained.

The source signal input to input terminal 1 is sent to 1/4 frequency divider 3.
The signal is down-converted to a frequency that is easier to handle, and is supplied to the cascade-connected 1/2 frequency dividers 4 to 7. Frequency divider 5~
The output of 7 is converted by a decoder 8 into sequential pulses P ₀ to _{P 7} without overlap. Sequential pulses P ₀ ~ _{P 7}
are shown in Figure 4 along with their levels. That is, the sequential pulses P ₀ -P ₇ are typically -V ₁ volts, the pulse peak voltage is OV, and there are eight repeating sequential pulses that do not overlap with each other.

The output sequential pulses P ₀ to _{P 7} of the decoder 8 are supplied to the vertical axis of the keyboard matrix 9 and simultaneously supplied to one input terminal of the AND gates 13 to 20.

In the keyboard matrix 9, the vertical axis is the output of the decoder 8.
_P0 to _P7 , and the waveform thereof is as shown in FIG. The horizontal axes are each grounded via a variable impedance element within the block 11. Keyboard contacts and their associated circuits are placed at the intersections of both axes in the matrix 9 marked with a circle.
The details are shown in FIG. 901 in Figure 3
are the vertical and horizontal axes connected to the output _P7 of decoder 8.
This is the intersection with R ₀ , but the other intersections marked with ○ are constructed in exactly the same way.

The operation at the intersection 901 in FIG. 3 will be explained below.

SW ₁ and SW ₂ are keyboard switches, and when no keys are pressed, they are both connected to the normally on (NC) terminal, and capacitor C ₁ is
Charged to V ₁ . Now, when the performer presses the key for scale note C ₁ , the NC terminal of keyboard switch SW ₁ opens, the charge in capacitor C ₁ begins to discharge through resistor R ₁ , and the potential difference across capacitor C ₁ gradually decreases. . Eventually, the changes in the keyboard become large, and the contact of keyboard switch SW ₁ becomes normally off (NO).
When connected to the side, the current due to the charge of capacitor C ₁ also flows to the base of transistor Q ₁ , and the current is amplified by transistor Q ₁ and charges capacitor C _2. Note that the capacitance ratio of capacitors C ₁ and C ₂ is If it is sufficiently large, there is no need for current amplification, and a diode may be used.

Now, for ease of explanation, transistor Q ₁
If we ignore the forward voltage between the base and emitter of , and the forward voltage of diodes D ₁ and D ₂ , the potential difference across capacitor C ₂ will be the same as when the middle point of keyboard switch SW ₁ is connected to the NO side. It is approximately equal to the potential difference across capacitor _C1 . Therefore, when the output _P7 of the decoder 8 is _-V1 , the potential at the point X becomes a value between _-V1 and _O. The shorter the time from when it leaves the NC terminal until it is connected to the NO terminal, the closer the value will be to O.

Now, when pulses appear sequentially at the output _P7 of the decoder 8, that is, when the vertical axis becomes O, the potential at point X is raised to the positive side by _V1 , and becomes a value between O and _V1 . Become. The same horizontal axes of the matrix, in this case the vertical axes corresponding to other intersections leading to the horizontal axis Ro, are all -V ₁ at this moment, so the X points of those intersections are all between -V ₁ and O. become. Therefore, the potential at point X of the intersection point 901, which corresponds to scale note C ₁ , where the vertical axis is O, is the diode.
It passes through D ₁ and appears on the horizontal axis R ₀ .

The horizontal axis R ₀ represents blocks 101, 113, 125,
It is connected to the terminal 1002 of 137, 149, 161, 173, and 185. On the other hand, matrix 9
The vertical axis of is input to AND gates 13 to 20, where it is ANDed with the strobe signal sent from decoder 10 via the AND gates, and as a result, the output is delayed from the output of decoder 8, as shown in FIG. Rise, fall quickly, and low level is O
Then, pulses whose high level is _V1 are sequentially supplied to blocks 101 to 188. The vertical axis that we are currently focusing on, that is, the output P ₇ of the decoder 8, becomes the pulse SP ₇ as shown in FIG.
This is block 185, 186, 187, 188
terminal 1003 of these blocks 1
Transistors _Q2 from 85 to 188 are turned on.
Therefore, the potential across the capacitor C ₂ of the block 901 is transmitted to the capacitors Cs ₁ and Cs ₂ of the gates of the transistors Q ₄ and Q ₇ of the block 185. Transistors Q ₄ and Q ₇ are turned on by the potential transmitted to the gates, and the input rectangular waves of input transistors Q ₅ and Q ₈ are transmitted to the gates of transistors Q ₉ and Q ₁₀ . At this time, even after the sequential pulses of the decoder 8 are transferred to others and the transistor _Q2 is turned off,
Since the potential is dynamically held in the capacitors Cs ₁ and Cs ₂ , the on state of the transistors Q ₄ and Q ₇ is maintained. Transistors Q ₉ and Q ₁₀ are source followers, and serve to prevent impedance conversion and cross-modulation with other sounds. Due to the above operation, the sources of transistors Q ₁₀ and Q ₉ have
A rectangular wave repeating at the fundamental frequency and a rectangular wave one octave higher than the fundamental frequency are obtained, and these are mixed by the resistors R ₁₃ and R ₁₄ at a required mixing ratio and output from the output terminal 1006.

On the other hand, when the potential of the output _P7 of the decoder 8 is 0,
The charge of capacitor _C2 is connected to the variable impedance element commonly connected to the horizontal axis of matrix 9.
It is discharged through _R2 , and the potential at point X gradually decreases. This discharge occurs every time the vertical axis of the matrix 9 becomes 0, and the potentials of the capacitors Cs ₁ and Cs ₂ of the block 185 decrease little by little each time. Correspondingly, the on-resistance of transistors Q ₄ and Q ₇ increases, and the amplitude of the musical tone signal supplied to the gates of transistors Q ₉ and Q ₁₀ decreases.
This is a so-called attenuated sound.

Next, when the keyboard is released, the keyboard switch SW ₁ returns to the NC side, the capacitor C ₁ is charged again, and is ready for the next key press, and the keyboard switch SW ₂ is grounded via the NC terminal, and the output terminal of the decoder 8 _P7 is 0
When , both ends of capacitor C ₂ have the same potential, discharging capacitor C ₂ and terminal 1 of block 185.
002, therefore, the potential of capacitances Cs ₁ and Cs ₂ is set to 0,
Turn off transistors Q ₄ and Q ₇ to eliminate the musical tone.
Except for the grounding at the center point of keyboard switch SW ₂ , the sound will remain even after the key is released.

The circuit corresponding to keyboard C ₁ has been explained above, but the same applies to the other tones. In short, as the output of decoder 8 moves from P ₀ to P ₇ in sequence, it is sequentially scanned octave by octave. ,
During that time, the capacity of blocks 101 to 188 is Cs ₁ ,
Cs ₂ stores and retains analog amplitude information, while
The envelope-controlled discharge elements are attached one by one to each horizontal axis of the matrix 9, and are used in a time-division manner.

The outputs of blocks 101 to 106 are combined into one, led to a tone filter through a terminal 21, and given a predetermined tone. Thereafter, the six tones are similarly grouped and supplied to tone filters from terminals 22 to 35, respectively, and the tone filters suitable for each range are used to add timbre. (However, terminal 3
Only 5 has 4 notes. ) In the above embodiment, in order to simplify the explanation, the third
Although the block 901 in the figure has a power supply E for level shifting, it is not actually necessary to do so, and it is easy to understand that it is sufficient to have one power supply for each vertical axis of the matrix 9. It will be.

Furthermore, various types of variable impedance elements can be used as the variable impedance element grouped together as block 11. No. 1972-46886) “Variable impedance element” (filed on October 18, 1971), patent application No. 1972-100846
No. (Japanese Unexamined Patent Publication No. 1983-244477) “Variable impedance circuit” (filed on August 19, 1975), patented in 1972-
It is possible to use the variable impedance element or the variable impedance circuit disclosed in No. 18095 (Japanese Unexamined Patent Publication No. 100952/1983) "Variable Impedance Circuit" (filed on February 20, 1975), and in this case, the It is possible to achieve damping characteristics close to those of a piano. This block 11 can be integrated into the same chip as the other circuit parts except for the matrix 9 in FIG. You can assemble it with

Furthermore, in the above-mentioned embodiment, one variable impedance element in the block 11 is arranged on each horizontal axis of the matrix 7. 1977-
No. 143010) “Electronic musical instrument” (filed on May 24, 1975)
According to the method of scanning the sound source block both vertically and horizontally, similar to the example disclosed in FIG.
As shown in FIG. 3 of No. 51-59137, only one variable impedance element can be prepared and used by sequentially switching the variable impedance element using a changeover switch element or the like. However, in this case, the discharge time of the capacitor _C2 is limited to the period when this discharge element is connected to the corresponding line. Input terminal 2 is a reset input terminal for resetting the frequency divider in the system, and is used to align the phases of two or more circuits as shown in Figure 1 when they are simultaneously driven by the same clock. Therefore, it can be removed if it is not needed.

In the embodiment shown in FIG. 1, the parts other than the keyboard block matrix 9 can be constructed from a 40 to 42 pin LSI, which is extremely effective in reducing the size and cost of the entire system. Furthermore, as mentioned above, the variable impedance device of block 11 can be formed as a separate chip and have various variations, such as having different characteristics depending on the system configuration. The number of LSI terminals in the main part remains unchanged.

Further, although the matrix 9 has a structure of 8×12 in length and width in the above-described embodiment, this can be changed freely, and may be set to 16×6, for example. In this case, decoder 8 becomes a 4-bit decoder, and this 4-bit decoder and top
Even if you use an external octave divider 12,
After all, it can be configured with a 40-42 pin LSI. In this case, a decoder is also required inside the LSI to sequentially supply pulses to the AND gates 13 to 20, and the system configuration requires a separate 4-bit decoder or equivalent circuit such as a shift register. It becomes necessary.

Furthermore, in the above embodiment, the gate capacitances Cs ₁ and Cs ₂ of the MOS transistors are used as capacitances for storing and retaining analog values, but the analog values can be converted into capacitances without using any special capacitance elements. It is also possible to utilize circuit elements constituting a circuit for storing and retaining information, such as gate capacitance of transistors, wiring capacitance, parasitic capacitance, etc.

As explained above using the examples, the present invention
Since information such as analog amplitude is dynamically stored in a small capacitance such as the gate capacitance of a MOS transistor, in an electronic musical instrument using a group of keyboard contacts electrically arranged in a matrix, the following Function can be realized.

(1) The envelope of musical sounds can be controlled freely.

(2) It is possible to obtain the loudness of the musical sound according to the speed at which the keyboard is pressed down.

(3) Since the envelope-controlled charge discharge variable impedance element is shared by multiple keys,
It requires fewer keys than the number of keyboards.

(4) Since envelope-controlled charge discharge is performed intermittently, the capacitance of the charge storage capacitor can be small.

(5) The function of muting the musical tone can be easily realized using the information on the release of the pressed key.

Further, since the present invention can realize most of the musical tone signal generating section with an extremely small number of LSIs, it is extremely advantageous in terms of miniaturization and cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
3 are circuit diagrams showing the main parts of the embodiment of FIG. 1, and FIGS. 4 and 5 are waveform diagrams of the main parts of the embodiment of FIG. 1. 1, 2...Input terminal, 3-7...Frequency divider, 8,
10...Decoder, 9...Matrix, 12...
Top octave divider, 13-20...AND gate, 21-35...Output terminal connected to tone filter, 101-188...Block with memory function, Cs ₁ , Cs ₂ ... Electric capacity.

Claims (1)

[Scope of Claims] 1. A keyboard consisting of a large number of keys, with the intersection of a matrix consisting of a vertical axis to which a scanning pulse for scanning the keyboard is applied and a horizontal axis to which an analog value is output corresponds to the keyboard. key press detection means for detecting key press information as an analog value corresponding to the amplitude of a musical tone, etc.;
A holding means consisting of an electric capacitance for storing and holding this analog value is provided for each key, and when a scanning pulse appears on the vertical axis, the analog value from the holding means is outputted on the horizontal axis, and the analog value is outputted from the holding means on the horizontal axis. An electronic musical instrument configured to time-division multiplex values. 2. The key press detection means includes a transfer switch corresponding to each key, and a first transfer switch whose one end is connected to the midpoint of the switch and which is connected in parallel with an impedance element so that the discharge time is determined according to the key press speed. An electronic musical instrument according to claim 1, comprising a capacitive element. 3. The holding means includes a second capacitive element that stores and holds the potential of the first capacitive element via the normally off terminal of the transfer switch, and stores and holds the potential of the first capacitive element through the normally off terminal of the transfer switch. By applying a scanning pulse to the reference potential side of the second capacitive element, the potential of the capacitive element to which the scanning pulse has been applied is selectively read out via a directional element such as a diode. Electronic musical instruments according to scope 2. 4. The electronic musical instrument according to claim 1, wherein the electric capacitance is constituted by the gate capacitance of a MOS transistor.