Abstract: The invention is directed to a waveshape generator capable of producing a desired waveshape by previously storing basic amplitudes obtained by sampling one period of the waveshape at a coarse interval and calculating amplitudes with a fine interval between the basic amplitudes. While basic amplitudes A and B are sequentially produced at a coarse interval in response to an integer portion of the input data, a function X (c) is produced in response to a fraction portion of the input data. Waveshape amplitudes are interpolated between the basic amplitudes by carrying out calculation of A + (B - A) .times. X(c) in response to these values A, B and X(c). A special form of function X(c) is also used for applying interpolation by a partial waveshape of a trigonometric function wave. An example of a musical tone waveshape generator is also described in which different waveshapes are produced depending upon different tone ranges by moving the position of a radix point for each of the different tone ranges.

Abstract: This key switch system (1) scans closed (or open) key switches in a matrix to produce corresponding key data, (2) encodes these key data into corresponding key codes, and (3) effectively registers the encoded key codes into time-shared channels of a key code memory.The key switch system may be incorporated in an electronic musical instrument. The system includes a key data generator which produces block data consisting of one pulse per scanning cycle in a time slot representing a block to which a key switch which is ON belongs, and note data consisting of a pulse in a time slot representing the particular key switch which is ON in the block indicated by the block data. A key coder encodes the block data and note data supplied from the data generator into key codes each representing the key name of the depressed key. A channel processor allots the key codes to storage channels of a key code memory having a number of such channels equal to the maximum number of tones to be reproduced simultaneously.

Abstract: In a digital type electronic musical instrument in which basic frequency information corresponding to a depressed key is cumulatively counted and a musical tone waveshape is read from a memory by the resultant output of the cumulative counting, a musical tone including a coarse noise is produced by randomly frequency-modulating the basic frequency of the musical tone, thereby providing the tone with a random vibrato effect. The frequency-modulation is effected by randomly adding or subtracting information expressed in the form of a certain frequency difference relative to the basic frequency information to or from the basic frequency information. According to an embodiment of the invention, a noise effect is produced only during a rise portion of the musical tone by reducing noise component in steps from the start of depression of a key and reproducing a musical tone of a normal pitch after a lapse of a predetermined period of time.

Abstract: In a digital type electronic musical instrument in which basic frequency is cumulatively counted and a musical tone waveshape is read from a memory by the resultant output of the cumulative counting, a desired vibrato effect is produced by digitally frequency-modulating the basic frequency. Vibrato information for effecting the frequency-modulation is produced from a vibrato code obtained by counting a clock pulse and a vibrato depth signal and has contents which change as time elapses. The frequency-modulation is made by multiplying the basic frequency with the vibrato information. The vibrato depth may be controlled for each individual keyboard. Vibrato frequency may be changed by changing the frequency of the clock pulse for each keyboard. According to an embodiment of the invention, the vibrato depth progressively increases from the start of reproduction of the musical tone. The speed of change of the vibrato depth may also be controlled for each individual keyboard.

Abstract: In a digital type electronic musical instrument in which frequency information corresponding to a depressed key is cumulatively counted and a musical tone waveshape is read from a memory by the resultant output of the cumulative counting, modified frequency information is produced by adding to or subtracting from said frequency information second frequency information represented by a predetermined frequency difference. A tone of a pitch which is slightly different from a normal pitch is generated from this modified frequency information for producing a beat effect between notes in an octave relation. The pitch can be controlled by suitably adjusting the second frequency information. Different beat effects can be produced for respective keyboards by varying the second frequency information by each keyboard.