Abstract: The present invention is an electronic musical instrument the type in which information of the actuation of keys is detected by scanning the keys of a keyboard. The electronic musical instrument includes keys selectively actuable for producing sounds which correspond to respective musical scale notes, circuitry for sequentially scanning these keys for detection of the information of the actuation of these keys, and a memory circuit corresponding to each of the keys so that the information of the actuation of the keys is stored in the memory circuits.

Abstract: A tone generator system for an electronic organ which is capable of being fabricated into an LSI structure and receives a saw-tooth wave or staircase wave as an input thereto comprises a frequency divider for the saw-tooth wave or staircase wave including a ladder resistor network and a complementary MOS FET devices, an analog switch having a wide dynamic range and a high linearity in input-output transfer characteristic constructed by MOS FET devices to serve as an indirect keying means, a sustain means including a novel structure of a variable impedance element which is constructed to control a channel current in a MOS FET device by varying a potential distribution in a source region, and an impedance converter constructed by complementary MOS FET devices and free from a D.C. level shift. With the above arrangement a tone generator system of high quality for an electronic organ is provided.

Abstract: The present invention is an integrated circuit for an electronic musical instrument comprising: a plurality of frequency divider chains receiving a plurality of input signals for dividing the frequencies of the input signals one after another and corresponding to a plurality of series of adjacent notes which are chromatically arranged in turn in a twelve-tone of a musical scale, respectively; keyer-gates for switching on and off the input signals and output signals of the frequency dividers of the frequency divider chains respectively; and adding means for adding at least two output signals of the keyer-gates which correspond to the adjacent notes chromatically arranged to each other, so as to produce output tone signals therefrom, respectively.

Abstract: A tone generator system for an electronic organ which is capable of being fabricated into an LSI structure and receives a saw-tooth wave or staircase wave as an input thereto comprises a frequency divider for the saw-tooth wave or staircase wave including a ladder resistor network and a complementary MOS FET devices, an analog switch having a wide dynamic range and a high linearity in input-output transfer characteristic constructed by MOS FET devices to serve as an indirect keying means, a sustain means including a novel structure of a variable impedance element which is constructed to control a channel current in a MOS FET device by varying the potential distribution in the source region, and an impedance coverter constructed by complementary MOS FET devices and free from a D.C. level shift. With the above arrangement a tone generator system of high quality for an electronic organ is provided.

Abstract: The channel current of an MOS transistor is controlled by varying the potential distribution in the source area. The source area is formed of a resistive material and provided with at least two electrodes on at least one of which a controlling voltage is applied. The current between the source and the drain terminals increases more rapidly than the linear change with respect to the increase in the voltage between the terminals, i.e. current-voltage characteristics are convex toward the lower direction. This device has excellent characteristics for use as a discharge impedance element in a sustain function circuit of an indirect keying or other circuit of an electronic musical instrument.

Abstract: An electronic organ comprises memory means for memorizing in an analog manner the synthesizing ratio of repetitively occuring waves such as square waves for synthesizing qualities of sound in response to the signals from means for selecting qualities of sound (to be referred to as tablets hereinafter); a mixing circuit for adding the synthesizing ratio for each repetitively occuring wave when the means for selecting qualities of sound are selected; frequency dividers for dividing the oscillation frequencies of top octave generators, an indirect keying circuit for interrupting the current corresponding to the ratio of repetitively occuring waves in response to the repetitively occuring signal waveforms from the frequency dividers and intermittingly interrupting said current in response to on-off signals from a keyboard; a synthesizing circuit for combining the outputs from the indirect keying circuit into a group for each octave; a variable filter for changing the frequency characteristics electronically in re