Kabushiki Kaisha Kawai Gakki Seisakusho

Noriji Sakashita

Toshio Kugisawa

Hironori Watanabe

Seiji Kameyama

Yutaka Washiyama

Sadaaki Ezawa

Tatsunori Kondo

Hikaru Hashizume

Nobuharu Obayashi

Hiroshi Kitagawa

An electronic musical instrument of digital processing in which required musical waveshape data are calculated by a tone control device to obtain a complex musical waveshape and the complex musical waveshape is read out at a read frequency produced by a key closure to generate the selected musical note. The electronic musical instrument has a calculator for calculating a musical waveshape in association with the operation of the tone control device in a period of time independent of the period of the generated musical note, a read-out signal generator for producing a memory read-out signal based on the closure of the key switch, a period detector for detecting by one period of each channel resulting from the closure of the key switch, first and second memories for storing the musical waveshape from the calculator, the stored musical waveshape being read out by the read-out signal, and means for achieving such a control that while the first memory is read out, the musical waveshape is stored in the second memory, that the read output signal from the first memory is sequentially written in the second memory by the output signal from the period detector in synchronism with the period of the generated musical note and that after completion of reading out of a new first memory, the musical waveshape from the calculator is stored in the first memory.

Electronic musical instrument

A musical waveshape processing system for an electronic musical instrument in which time-division time slots are set corresponding to a plurality of channels for producing notes selected on keyboards of the electronic musical instrument and the notes are each produced by repeatedly calculating the musical waveshape amplitude value of each channel in each time-division time slot. A musical waveshape calculator is provided which calculates the musical waveshape amplitude value as f(t)=at.sup.2 +bt+c based on waveshape data a, b and c and address information t. A multiplier is provided by which the value of an envelope synchronized with the time-division time slot is multiplied by the waveshape data a, b and c. A tone control circuit is provided which counts time-division multiplex signals of the ON-OFF state of a tone selection switch with a counter every frame of the time-division multiplexing and compares the count values of two successive frames to detect a change in the state of the tone selection switch from non-coincidence between the both count value, thereby controlling the musical waveshape.

Musical waveshape processing system

An electronic musical instrument which has a key assignor or assignors of one or more channels for generating and temporarily storing key code corresponding to key depression and release, respectively, a memory for storing waveshape information such as inclination and amplitude variations of a required musical waveshape divided into a plurality of periods so as to read out the waveshape information corresponding to the key code, a plurality of tone source devices, each including waveshape generators of different sound ranges respectively corresponding to keyboard switches in the same channel of each key assignor, the tone source device reading out the waveshape information from the memory on a time divided basis to generate from the waveshape generators waveshapes of different frequencies based on the read out waveshape information, and means for simultaneously actuating the corresponding waveshape generators by the key code from the key assignor and coupler information.

A key code generator for electronic musical instruments which has a switch matrix circuit having a plurality of switches disposed at the intersections of two sets of buses, means for simultaneously applying signals to the switch matrix circuit from one of the two sets of buses to derive outputs from a plurality of blocks into which the buses of the other set are divided line by line, a memory for detecting the blocks that even one switch is in the on state from the bus outputs of the switch matrix circuit and temporarily storing signals of the detected blocks, a first priority selector for selecting block signals in a predetermined order of priority from the bus outputs and sequentially outputting the block signals with a predetermined clock pulse, means for inhibiting the block detecting operation during outputting from the first priority selector and applying the selected block signals to the buses of the detected blocks to sequentially scan only the detected blocks, a second priority selector for selecting switch signals in a predetermined order of priority from respective switch signals of the scanned blocks and sequentially outputting the switch signals with a predetermined clock pulse, and means for preventing clock pulses from inputting to the first priority selector until the switch signals of each designated block are all outputted.

Key code generator

A tone source apparatus for an electronic musical instrument is characterized in that at least one cycle of a musical-tone waveform, which it is desired be produced, is depicted as a sequence of section lines and a series of pulses having regular intervals is varied, by a pulse-density varying circuit, in pulse density in accordance with the degrees of inclination of the respective section lines. The resultant series of pulses having varied pulse density is formed, by a waveform forming circuit, into the desired musical tone waveform. The pulse-density varying circuit comprises a first counter to which is applied as an input, the aforementioned series of pulses having regular intervals. A second counter is connected, in series or in parallel, to the first counter and a decoder is connected to an output terminal of the second counter. A memory circuit is connected to the output terminals of the decoder. The memory circuit comprises a plurality of pulse-density setting portions which set frequency-dividing ratios for the first counter for selecting output pulse-densities. The memory circuit also comprises a plurality of section range setting portions which set frequency-dividing ratios for the second counter for selecting output time intervals of signals obtained at respective output terminals of the decoder.

Tone-source apparatus for electronic musical instrument

A tone source apparatus is provided for an electronic musical instrument. It comprises a memory circuit which has a plurality of addresses and is so arranged that where at least one cycle of a musical tone waveform is divided into p units and a waveform in each section range is represented by a formula containing the abscissa as its variable, a coefficient and a section range quantum number of each formula is memorized in the form of digital signals in the corresponding address. Also included are a clock pulse oscillator, a counter means for counting output clock pulses of the clock pulse oscillator, and a coincidence circuit serving to generate the coincidence signal when the output digital signal of the counter means and a digital signal of the section range quantum number memorized in the memory circuit coincide with one another. A decoder designates the next stage address in order by output signals of the coincidence circuit. A calculation circuit is used for calculating a digital signal from the counter means and a coefficient digital signal from the designated address. A D-A convertor converts the output digital signal of the calculation circuit into a corresponding analog signal. The addresses in the memory circuit have memory portions which memorize as digital signals respective coefficients of n degree multiple term formulae for respective section ranges, and respective section range quantum numbers.

Tone source apparatus for an electronic musical instrument

An apparatus for forming a musical-tone waveform for an electronic musical instrument characterized in that at least one cycle of a musical-tone waveform, which it is desired be produced, is divided in amplitude by dividing lines at equal intervals and sampling points on a time axis are determined from respective crossing points between the waveform and the dividing lines and the distance between the initial and the final sampling points is represented by an appropriate number of pulses so that each sampling point may be represented by a pulse number. There is further provided a memory circuit wherein each sampling point, that is, the pulse number thereof is set up in the form of a digital signal. Additionally, there is a set up in the form of a digital signal a tendency such as increase, decrease or equal at each sampling point with reference to the preceding sampling point. An envelope setting device is used wherein the envelope of a muscial-tone waveform, which it is desired be produced, is subjected to sampling and the analog amount of each sampling point is set up in the form of digital signal. An accumulatively adding device is employed whereby the output digital signal of the envelope setting device is accumulatively added to or subtracted from the output digital signal of the memory circuit. The accumulatively adding device is connected at its output terminal to a D-A converter for converting its output signal into an analog signal.

Musical-tone-waveform forming apparatus for an electronic musical

An electronic musical instrument in which a plurality of order pulse generators and a plurality of musical-tone-waveform forming circuits are connected in order to a tone-source-signal pulse generator. Interposed in each of a plurality of circuits diverging from the output terminal of the tone-source-signal pulse generator to the order pulse generators is a pulse-counter circuit which has a variable frequency-dividing ratio. On the output side of the pulse-counter circuit, a frequency-dividing ratio-setting signal-generating counter circuit is provided which generates a signal for setting the frequency-dividing ratio thereof.

An electronic musical instrument in which a plurality of order pulse generators and musical-tone waveform forming circuits are connected in order to a tone-source-signal pulse generator. A first pulse-counter circuit and a second pulse-counter circuit are provided in each of the circuits diverging from the output terminal of the tone-source-signal pulse generator to the respective order pulse generators, so that the output signal of the tone-source-signal pulse generator is frequency-divided by the first pulse-counter circuit into 1/x and is then applied as an input signal to the order pulse generator, while the output signal of the tone-source-signal generator is frequency-divided by the second pulse-counter circuit into 1/n and is then applied as a reset pulse to both the first pulse-counter circuit and the order pulse generator. The numbers x and n are integral numbers with the relation 0&lt;x&lt;n. Each musical-tone waveform forming circuit has a sampling number of from 10 to 40.

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Hamamatsu, Japan

Noriji Sakashita