Abstract: 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.

Abstract: 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.

Abstract: A digital electronic musical instrument which produces musical notes by approximately reproducing a waveshape based on information of points of extremal values on a musical waveshape, storing the approximate waveshape after sampling it with the number of the frequency at which the notes are to be produced and reading out the stored waveshape with a predetermined clock.

Abstract: 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.

Abstract: Keyboard apparatus for an electronic musical instrument in which a particular code is assigned to each of keys of the keyboard and which is provided with a multiplexer circuit for detecting the depression of the key corresponding to an input code, means for sequentially generating the codes of the keys, memory means for storing the codes, a comparator circuit for comparing the outputs from the memory means and the code generating means to provide a coincidence signal when the both outputs are coincident with each other, a cycle control circuit for controlling a key ON cycle and a key OFF cycle in distinction from each other, and gate means for selecting the output code from the code generating means and the code of the memory means with the key ON cycle and the key OFF cycle to output to the multiplexer circuit. In the key ON cycle, the multiplexer circuit detects that the key having not been depressed yet is newly depressed, and stores it in the memory means.

Abstract: 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.

Abstract: A musical-tone signal forming apparatus for an electronic musical instrument is characterized by the use of a musical-tone waveform setting circuit by which repeatedly at least one cycle of a musical-tone waveform is sampled at n points so the amplitude thereof at each sampling point can be compared with the amplitude thereof at the preceding sampling point and an increase signal, an equal signal, or a decrease signal is generated as a digital signal. Also employed is an envelope setting circuit in which an envelope of a musical tone is sampled at m points and the analog amount thereof at each sampling point is generated as a corresponding digital signal. An integrating circuit is used in which the digital signals of the envelope setting circuit are accumulatively added or subtracted according to the digital signals of the musical-tone waveform setting circuit. The output signal of the integrating circuit is taken out through a D-A converter as a musical-tone signal.

Abstract: 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.

Abstract: A musical-tone signal forming apparatus is provided for an electronic musical instrument. The apparatus comprises a musical-tone wave form setting circuit in which at least one cycle of a musical-tone wave form is repeatedly subjected to sampling at n points and the amplitude at each sampling point is compared with the amplitude at the preceeding sampling point. An increase, equal or decrease signal is generated in the form of a digital signal to indicate the relationship determined. An envelope setting circuit is provided in which an envelope of a desired musical-tone is subjected to sampling at m point and the analog amount at each sampling point is generated sequentially as a digital signal corresponding thereto. A pulse generating circuit whereby a pulse signal having a number corresponding to the digital signal value produced by the envelope setting circuit is repeatedly generated is employed.

Abstract: 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.