Abstract: A method for producing a tone waveform having a desired spectral construction by modulating an input address signal of a selected frequency for a waveform memory. For the modulation of the input address signal, the output of the waveform memory is multiplied by a parameter .beta. of a suitable value and the multiplication product is added to the input address signal. If the input address varies in the manner of, for example, a saw-tooth wave, a desired tone waveform can be produced within a range between a saw-tooth wave and a sinusoidal wave by selecting a suitable value of the parameter .beta.. More specifically, a saw-tooth wave is produced as a tone wave form if a sufficiently large value of .beta. is selected. As .beta. is gradually decreased, the amplitude is decreased from a higher order and the amplitude also disappears from a higher order until the tone waveform becomes a sinusoidal wave when .beta. is zero.

Abstract: A device for detecting a key switch operation capable of detecting an operating state of a plurality of key switches which are commonly connected with respect to each row line (block line) at one terminal thereof and commonly connected with respect to each column line at the other terminal thereof, thereby constituting a switch matrix. If a signal is provided on all column lines, the signal is transmitted to a block line through a key switch which is in operation and thereby a block including the key switch in operation is detected. A signal is then supplied from the detected block line to a column line only through the key switch in operation in the detected block. The position of the key switch in operation is known by detecting the column line on which the signal arrives. According to an embodiment of the invention, capacitance elements are provided both on the block lines and on the column lines for effecting delivery of the signal by charging and discharging of these capacitance elements.

Abstract: Upon key depression, there is produced a phase progress signal in digital representation which varies by an increment predetermined in accordance with the frequency of the note designated by the depressed key. The phase progress signal is subjected to a coordinate conversion and squaring operation to provide downward opening parabolic curves and upwardly opening parabolic curves, which are alternately connected at their open ends to produce an approximate sinusoidal waveform as a digital tone signal. The digital tone signal is multiplied by a digital envelope signal to produce a keyed musical tone signal.

Abstract: In a digital type electronic musical instrument, a glide effect is produced by digitally frequency-modulating the frequency of a musical tone in such a manner that the frequency changes quickly and smoothly. Glide information used for effecting this frequency-modulation is produced on the basis of a glide code obtained by counting a clock pulse. The glide information which changes its contents uniformly is multiplied with the basic frequency information to effect the frequency-modulation. The glide effect can be controlled for each individual keyboard. According to an embodiment of the invention, the frequency-modulation is applied to an attack portion of a musical tone only and sustain and decay portions of the musical tone are reproduced with a normal frequency so that the musical tone will be provided with a crisp, vivid musical effect.

Abstract: A channel processor capable of assigning a key code provided by a key coder and representing making (or breaking) of a key switch to one of a plurality of channels for storage therein and subsequently detecting breaking (or making) of the same key switch on the side of the channel processor. The assignment of the key code is implemented by holding the key code provided by the key coder during a predetermined period of time, detecting whether conditions for the key code assignment have been satisfied or not in a former half of the holding period and, if such conditions have been satisfied, causing the key code to be stored in an empty channel of a main memory device in a latter half of the holding period. Detection of breaking of the made key switch (or vice versa) is made by once clearing a memory storing the assigned channels by means of a start code generated by the key coder and subsequently finding that a channel among the cleared channels is not stored in the memory again, i.e.

Abstract: In a waveform producing system for use in, for example, an electronic musical instrument, a tone generator circuit and/or a tone control circuit including tone keyer circuits, each or either one of said tone generator circuit and said tone control circuit comprises: pulse generators associated with key-actuated switches, respectively; waveform memorizing means having at least one row of voltage dividers of which the division ratios are preset in characteristics corresponding to either the tone waveforms, the tone envelopes or the depression speeds of the key operated by the player of the instrument; sequential memory read-out means connected to the respective voltage dividers; and pulse generators thereby providing an enabling signal sequentially to the individual dividers every time a pulse is inputted from the pulse generators to read-out the memorized waveform in the form of a modified audio signal at the output side of the circuit.

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.