Abstract: Apparatus is disclosed for viewing a target volume by two spaced apart viewing devices which create respective two dimensional video picture frame signals. The picture frame signals are divided into discrete areas. If there is an image change in one of the discrete areas then analyzing means provides control signals which feed a reaction providing means, which in turn is then responsive to a change of an object within the volume.

Abstract: An array of universal processing elements (UPEs) may be interconnected through a switching matrix in response to control words which are in turn produced by a programmed digital computer in response to commands from a keyboard or a data file, thereby routing the outputs of selected UPEs to other UPEs for further processing and/or combining a sound stream in digital form. The matrix is comprised of both local and global conductors, the local ones being available to selected groups of UPEs. Each UPE is implemented as a digital multiplier, preferably with pipelining, and each UPE is comprised of a plurality of stages, preferably implemented with an adder for computing the sum of a plus the Boolean logic function [b.multidot.m+d.multidot.m] and a multiplexer for forming the function [b.multidot.+d.multidot.m], where a, b, d and m are bits of the respective two's complement number A, B, D and M, whereby the entire array of stages in a UPE computes A+[B.times.M+D.times.(1-M)].

Abstract: An electronic musical instrument comprises: a keyboard circuit for generating a pitch data signal which designates the note name of a musical tone to be produced; a speech signal generator for generating a speech signal which tells in human voice the name of the designated musical tone; multiplexed processing circuit for time-divisionally processing the pitch data signal and the speech signal; and sound signal producing circuit for producing the musical tone and the human voice in accordance with the processed output from the multipled processing circuit. Thus the instrument speaks the names of the tones as it produces the musical tones.

Abstract: An electronic apparatus in which the operator inputs both the textual material and a sequence of pitches which upon synthesization simulates singing qualities. The operator inputs a textual material, typically through a keyboard arrangement, and also a sequence of pitches as the tune of the desired song. The text is broken into syllable components which are matched to each note of the tune. The syllables are used to generate control parameters for the synthesizer from their allophonic components. The invention allows the entry of text and a pitch sequence so as to simulate electronically the singing of a tune.

Abstract: A keyboard musical instrument with a transpositional function includes a keyboard, a mode selection switch, a microcomputer, a musical tone signal generator and a sound system. The keyboard has a plurality of keys respectively representing different notes in a musical scale. The mode selection switch selects one of a transposition mode and a play mode. The microcomputer includes a CPU, a ROM, and a RAM to detect first and second depressed keys when the transposition mode is selected by the mode selection switch. The microcomputer generates transposition data having a value corresponding to an interval between the notes represented by the first and second keys. The microcomputer generates a note signal representing a note higher or lower by the interval represented by the transposition data than a note of a given depressed key when the play mode is selected by the mode selection switch.

Abstract: A keyboard operated musical instrument is disclosed in which the number of tone generators can be less than the number of keyswitches in a keyboard array of keyswitches. A binary-tree search is programmed to search subsets of the keyswitches to find keyswitches that have been actuated. The subsets are selected in an adaptive fashion which minimizes the search time required to detect and identify all the actuated keyswitches. A modular assignment subsystem is described whereby tone generators are assigned to actuated keyswitches according to a predetermined priority logic.

Abstract: A note clock generation circuit generates note clock pulses in correspondence to a note name of a tone to be generated. An octave rate data generation circuit generates rate data in correspondence to the octave range to which the tone to be generated belongs. By performing addition or subtraction of the rate data at the timing of generation of the note clock pulses, an address signal is generated. A tone generator generates a tone waveshape in the form of amplitude sampled values in response to an integer section of this address signal. An interpolation circuit performs interpolation between adjacent amplitude sampled values thus generated in response to a decimal section of the address signal. The rate of change of the decimal section of the address signal is changed in accordance with the tone range so that a finer interpolation is made as the tone range becomes lower. By this arrangement, decrease in an effective sampling frequency in the lower tone range can be prevented.

Abstract: An interactive music performance system employs a synthesizer, a programmable computer, and at least one performance device for permitting a user input. The computer is programmed with algorithms which automatically generate controls and interpret a performer's actions in the context of music and sound generating variables, and apply those controls to a synthesizer to determine its production of music. The system is interactive in that a user can direct the system's production of music, as he or she hears it being produced, by use of the performance device. If the user does not provide an input, the system proceeds automatically under control of the performance algorithm.

Abstract: An improved waveform generator used in an electronic musical equipment for reproducing musical sounds stored therein, in which the waveform of each musical sound is stored in a memory as a sequence of amplitudes sampled at specific sampling points on the waveform and reproduced therefrom by interpolating arithmetically any point between these sampling points.

Abstract: A fiber-optic signal transmission link is used in place of electric audio cable to inter-connect performing musicians and all the necessary pieces of music processing equipment being used in a performance in order to isolate all the people involved in the performance from potential electrical and physical hazards created by the electric audio cables being used.

Abstract: A set value of a frequency setting register is accumulated upon each occurrence of a clock signal, and a waveform memory is read out by using the accumulated value as an address. In the waveform memory, amplitude data of one cycle of the waveform of a burst signal to be generated are stored at fixed phase intervals. The output read out of the waveform memory is converted into an analog signal. A wave-number counter counts the number of times the amplitude data of one cycle is read out of the waveform memory and, when having counted by a preset number of waves, yields a wave-number counting end signal. After the occurrence of the wave-number counting end signal, a phase counter counts clock signals, and, when the count value of the phase counter reaches a value corresponding to a preset end phase, the generation of the burst signal is stopped.

Abstract: A musical tone generating apparatus of an adapter type to be connected to a host electronic keyboard musical instrument via an information cable for generating musical tone signals in accordance with key information supplied from the host musical instrument. The musical tone generating apparatus comprises switches for designating a fractional key range in the keyboard and generates a musical tone signal only when a key within the designated key range is depressed. A plurality of musical tone generating apparatuses of the same construction as the aforesaid musical tone generating apparatus can be connected in a cascade fashion to a single host electronic keyboard musical instrument.

Abstract: A membrane keyboard for e.g. a low cost electronic tone generator of the type affixed to the binding of a songbook is disclosed. The keyboard includes a base carrying a set of interdigital upwardly facing printed circuit contacts for each key. A membrane overlay is vacuum formed of a thin plastic sheet to define a horizontal row of playing keys, each key being formed as a plateau area, with a vertical depression spring rib separating each key. Each key includes an elastomeric foam pad affixed to its underside area which carries a conductive lower surface aligned with with the interdigital traces of the key. The conductive surface bridges the traces to complete an electrical circuit when the membrane is depressed downwardly from its top surface.

Abstract: A keyboard musical instrument includes: a keyboard; an acoustic musical tone production mechanism for generating an acoustic musical tone; a tone generator for generating an electronic musical tone; a solenoid driver for inhibiting generation of the acoustic musical tone from the acoustic musical tone production mechanism; and an operation panel for designating a musical tone to be inhibited. When a player designates a musical tone to be inhibited via the operation panel in advance and then depresses a key on the keyboard, the generation of the acoustic musical tone is inhibited by means of the solenoid driver.

Abstract: An electronic musical instrument comprises a keyboard for generating tone data or key codes each representative of a tone to be generated and a tone generating circuit having a plurality of tone generating channels. The electronic musical instrument also comprises a RAM having a plurality of storing positions for storing the key codes each of which is assigned under the control of a central processing unit (CPU) to a respective one of the tone generating channels to thereby generate a tone determined by the assigned key code. When a key is newly depressed on the keyboard, each of the key codes stored in the RAM is read therefrom and supplied to an envelope generator which in turn generates data representative of an amplitude of each of the envelopes given to the tones. The key codes read from the RAM are also supplied to a ROM to read therefrom weighting data.

Abstract: A keyboard operated musical instrument is disclosed in which musical tones are created by reading out data values stored in a waveshape memory. The number of stored data points is reduced by storing the data values in segments corresponding to one-half of the number of data points for a period of a waveshape. By using synthesized data having a symmetry about the midpoint, the second half of the waveshape is recovered by a forward and backward memory address read of each waveshape segment. After reading each segment a predetermined number of cycles, an abrupt jump is made to the next segment of waveshape data points. The fundamental frequency of the tone is varied in a temporal manner by changing the memory advance rate of reading waveshape data out of memory in response to a frequency offset data corresponding to each segment of the waveshape data. An alternative embodiment is disclosed for a tone generator in which the musical waveshape is computed in real time from stored sets of harmonic coefficients.

Abstract: These small, inexpensive ornaments and novelties emit music and other sounds (such as simulated voice) when exposed to light, and can be placed out-of-doors in a garden. Being light-powered, they can operate for an essentially indefinite time, even though unattended.Each such ornament or novelty consists of a thematically configured body and a three-element working module sealed in a watertight can. It has no input keyboard or other terminal, and no display panel or other electronic or visual data output, except the audio output.Elements are (1) a circuit, preprogrammed to produce electronic oscillations corresponding to a tune or other sounds preestablished at manufacture, (2) a speaker receiving the oscillations and emitting the sounds, and (3) a solar panel powering the circuit. The speaker shuts off if light is inadequate for completely correct operation, and otherwise is amplitude modulated by the light level.

Abstract: In an apparatus for generating an aperiodic waveform having a gradually decaying envelope, a sequence of digital samples representing the magnitude of the waveform at sample points is stored in a memory. The stored digital samples are grouped into at least first and second continuous portions, the second portion including that portion of the sequence in which none of the digital samples has a magnitude exceeding 1/n the magnitude of the largest of the digital samples, where n is an integer greater than unity, each of the digital samples of the second portion being scaled by a factor of n. The memory further stores a code indicating the beginning of the second portion. An address counter develops an address signal for sequentially addressing the stored digital samples and code from the memory in response to clock pulses. When the stored code is addressed, an additional clock pulse is supplied from a code detector to the address counter.

Abstract: To enhance low and high frequency components in a sound signal, low frequency components are used to generate new yet lower frequencies (subharmonics), and high frequency components are used to generate new yet higher frequencies (harmonics), the new frequencies added to the original signal thereby increasing the original signal bandwidth.

Abstract: A musical scale generating circuit comprises an oscillator, a programmable frequency divider for frequency-dividing an output signal from the oscillator, a tone generating circuit for generating a tone, and a frequency dividing ratio data output circuit for successively outputting frequency dividing ratio data determinative of a plurality of frequency dividing ratios of the programmable frequency divider. A frequency dividing ratio discriminating circuit detects whether a frequency dividing ratio necessary for outputting a desired scale frequency is an odd or even number. A frequency dividing ratio correcting circuit is operative to add one to or substract one from frequency dividing ratio data, when a frequency dividing ratio is detected to be an odd numbered frequency dividing ratio and applies corrected frequency dividing ratio to the programmable frequency divider. A one-half frequency divider further divides a signal from the programmable frequency divider by two.

Abstract: A keyboard operated musical instrument is disclosed in which musical tones are created by computing waveshapes from a set of harmonic coefficients. Tones with time variant spectra are obtained by scaling each harmonic coefficient in response to a stored set of scaling numbers. An efficient scaling implementation is described which changes the harmonic coefficients by increments of a predetermined ratio. The tone generation system provides a significant reduction in the number of stored numbers in comparison with a simple stored waveform tone generator.

Abstract: An electronic musical instrument of the sampling type is provided. The electronic musical instrument comprises a memory having a plurality of storage areas, and operates in one of full sampling, part sampling, full play and part play modes. Sampling data of waveform of a tone are stored into addresses of all the storage areas in the full sampling mode, and are stored into addresses of one of the storage areas in the part sampling mode. Thus, only one waveform is sampled and stored in the full sampling mode, whereas a plurality of waveforms can be sampled and stored in the part sampling mode. In the full play mode, the whole sampling data are read from the storage areas to form a tone, so that the tone can have a complicated waveform if the sampling data have been stored in the memory in the part sampling mode.

Abstract: A CPU reads out sampled waveform data stored in a waveform memory and detects a peak value of the read-out data for each predetermined block using working registers, thereby obtaining an interpolated envelope curve. The CPU then divides the sampled waveform data by the interpolated envelope curve to obtain a normalized sound waveform without any envelope in an original sound signal.

Abstract: A digital pattern generator generates various kinds of digital pattern signals. A first memory stores an execution signal, an area control signal and a digital pattern. A program counter generates a first address signal in accordance with the execution signal read from the first memory and a first clock signal, and the first memory is addressed by the first address signal. Thus, the pattern generator operates as a microprogram type generator. A second memory includes a plurality of memory areas each storing a digital pattern, and a capacity of each the memory area corresponds to that of the first memory. When the second memory is addressed by a second address signal from an address counter, the pattern generator operates as a sequential type generator. When the memory area of the second memory is selected by the area control signal read from the first memory and the selected memory area is addressed by the first address signal, the second memory acts as an auxiliary memory of the first memory.

Abstract: A digital keyboard interface for a keyboard operated musical instrument, such as a piano, includes at least one switch associated with each key on the keyboard and positioned therebeneath. Key actuation produces a corresponding associated switch actuation. The keyboard interface is readily installed within an acoustic or electronic piano and includes adjustments for height and side-to-side alignment to provide precise registration of keys and switches and to provide simplified installation of the interface within the piano. A switch matrix includes a plurality of rows that assign switch closure information to corresponding data byte bit positions in a digital data stream. A shift register sequentially, and on a one-at-a-time basis, actuates a series of matrix columns to read a set of swtiches associated with the column. Thus, each switch operated in an actuated column corresponds to a data byte bit position in the data stream which is further processed to generate a serial data stream for external devices.

Abstract: Apparatus for viewing a target area and for providing a reaction consequent on a changing image in the target area (1), said apparatus having video cameras (3) for viewing the target area (1) and for creating video picture frame signal of the target area, analog to digital converters (7, 9, 11, 13, 14, 15, 17, 21, 31) for analyzing the signals relating to one or more discrete areas within each picture frame, the converters feeding control signals to a synthesizer to provide a change in the reaction consequent on there being an image change in the one or more discrete areas from an earlier frame.

Abstract: A keyboard operated musical instrument is disclosed in which the musical tones are generated by reading out data values stored in a waveshape memory. The number of stored data points is reduced by storing the data values in segments corresponding to one-half of the number of data points for a period of a waveshape. By using synthesized data having a symmetry about the midpoint the second half of the waveshape is recovered by a forward and backward memory address read of each waveshape segment. After reading each segment a predetermined number of cycles, an abrupt jump is made to the next segment of waveshape data points.

Abstract: In a method for providing musical accompaniment in response to the playing of an accompaniment-type musical instrument, accompaniment chord voicing is randomly selected from a pluraltiy of stored possibilities and the chord is sounded according to the selected voicing. In a preferred embodiment, the voicings may be stored separately from rhythm information according to which the chord is to be sounded, and the selection of chord voicings is constrained by a pre-selected range of chord tones. In another method for providing musical accompaniment having at least one stored melodic figure, melodic information is represented as a plurality of tokens independent of chord type and the tokens are subsequently converted to note parameters appropriate for a preselected chord type. The tokens are preferably related to the scale functions of the melodic information and may also contain information for each of a plurality of chord sub-types.

Abstract: External sound signal coupled through a MIC IN terminal is fed through an operating switch panel section to an A/D converter for conversion to a digital signal. The digital signal is stored in a record memory through a waveform R/W controller under the control of a CPU. The digital signal stored in the record memory is read out from the CPU according to control data stored in a work memory to be fed to an external sound system for sounding.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators that are assigned to actuated keyswitches. Musical tones are produced by computing a master data set from an interpolated sequence of harmonic coefficient values. The master data set points are read out sequentially and repetitively from a memory and converted into an audible tone. A plurality of harmonic coefficient memories are used to store preselected sets of harmonic coefficients. In response to a timing clock, the harmonic coefficients from a cyclically chosen pair of harmonic coefficient memories are selected. A tone having a time variant spectra is produced by using a time variant interpolation between the selected pair of harmonic coefficients.

Abstract: A keyboard is capable of being used by splitting it in plural key areas at a predetermined split position or positions. A tone forming circuit generates a tone signal corresponding to a depressed key in each key area in a tone generation manner corresponding to one of the split key areas. A plurality of key touch sensors are provided in correspondence to splittable key areas. In case that a certain key split mode is being selected, each touch sensor outputs a touch signal representing a degree of depression of the depressed key in a corresponding key area and supplies it to the tone forming circuit. The tone forming circuit imparts the tone signal for each key area with a touch responsive characteristic in accordance with the corresponding touch signal, thereby performing a properer touch response control in an electronic musical instrument.

Abstract: Data for each sample point amplitude values of a desired waveshape is expressed in mantissa and exponent in accordance with a floating-point representation. The desired waveshape is divided into a plurality of frames along a time axis and the exponent data is common in each individual one of said frames which includes a plurality of sample points. The number of the frames is much smaller than the number of all sample points. In this waveshape memory, the mantissa data corresponding to the respective sample points are stored in a first memory, and exponent data corresponding to the respective frames are stored in a second memory.

Abstract: A CPU supplies data write and read commands to only an address control section, and the address control section then designates, for the purpose of writing and reading data, addresses of a waveform memory in which external sound waveform data is stored.

Abstract: A method of and a device for transforming the musical notes of a piece of music into different notes to obtain a new piece of music. The notes constituting the original piece of music are stored in an original music memory. These notes are then transformed into other notes in accordance with predetermined rules stored in a transforming means and the transformed notes are thereafter stored in a transformed music memory.

Abstract: When key-off information is given after the start of an operation of generating a predetermined tone according to key-on information, a predetermined period of time is counted from the instant the key-off information is provided and, after the lapse of the predetermined period of time, a process of stopping the tone is executed, whereby a minimum necessary interval of a tone can, according to a key signal, be ensured.

Abstract: A sound producing device producing different notes when rotated. Three orthagonally mounted gravity switches produce signals corresponding to their orientation to a reference. A multiplexer or programmable counter coupled to the switches selects one output line for each combination of states of the switches. Each output is passed through different values of resistance so that unique frequencies result. The output of the multiplexer is coupled through an oscillator to a speaker and a tone corresponding to the frequency of the output selected is produced. Multivibrators are coupled to the switches and to the oscillator to shut off the production of sound when the device has been left at rest for a certain time period.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators that are assigned to actuated keyswitches. Musical tones are produced by computing a master data set which defines the data points corresponding to a period of a musical waveshape. The master data set points are read out sequentially and repetitively from a memory and converted into an audible musical tone. Circuitry is provided whereby the master data set is computed from a time sequence of harmonic coefficients which is modulated to produce a musical tone having a time variant spectra.

Abstract: An electronic instrument comprises a main electronic keyboard instrument body and a remote playing unit. The main electronic keyboard instrument body includes a keyboard, a sound generating circuit, and a processing circuit for discriminating a chord responsive to a manipulation of the keyboard and for determining a scale in accordance with the chord. The processing circuit causes the sound generating circuit to generate sound in accordance with the determined scale with a designated timing. The remote playing unit is electrically coupled to the main electronic keyboard instrument body, and comprises a plurality of elongated bar switches arranged side by side with an interval between two mutually adjacent bar switches. The timing with which the sound is generated by the main electronic keyboard instrument body is designated by manipulating and closing the bar switches.

Abstract: A digital pitch bend signal is supplied from an A/D converter to a first coefficient multiplier for every predetermined sampling period. An output of the first coefficient multiplier is added with an output of a second coefficient multiplier at an adder an output of which is delivered, as a digital pitch bend signal in the present cycle, from a buffer for the tone generation. The output of the adder is also fed back to an input of the second coefficient multiplier. Thus, from the buffer, a converted pitch bend signal having a value corrected during the respective sampling periods is produced.

Abstract: A musical instrument employing probabilistic wavetable-modification method of producing musical sound. A randomly initialized wavetable which is periodically accessed to provide an output signal which determines the musical sound. The output signal from the wavetable is probabilistically modified and stored back into the wavetable as modified data. The modified data, after a delay, is accessed from the wavetable and thereby becomes a new output signal. This process is periodically repeated whereby each new output signal is stored (after possibly being modified) back into the wavetable to produce rich and natural musical sound.

Abstract: A data input apparatus comprises an operation panel; a plurality of input keys arranged on the operation panel; and a fine adjusting bar arranged on the operation panel; and a data generator coupled to the input keys and to the fine adjusting bar. Each of the input keys designates a coarse selection of an input instruction, respectively, from among a plurality of input instructions such as musical note pitches and durations. The fine adjusting bar designates a fine adjustment for and in common to the respective selected input instructions designated by the input keys. The data generator generates data bearing information formed by the selected input instruction and the fine adjustment. Thus the data input apparatus composes musical performance data for automatic performance by musical tones with adjusted note pitches, note durations, and other note characters.

Abstract: In a musical tone signal generating apparatus of a harmonic combination system, the coefficient values of a continuous harmonic to be formed are discretely sampled. Among the sampled values, the values between each two adjacent sampling points (i.e., each two adjacent frames) which vary are selected, and only difference coefficient data therebetween are stored in a memory. When the harmonic coefficient data is to be formed, the difference coefficient data is used for the coefficient varying values between each two adjacent sampling points, and a new coefficient value is calculated. However, as for the nonvarying values between each two adjacent sampling points, no calculation is performed and an already calculated coefficient value is used, thereby updating harmonic coefficients as a function of time, and hence generating a musical tone signal whose tone color is changed as a function of time.

Abstract: In a musical instrument in which a plurality of data words corresponding to the amplitudes of a corresponding number of evenly spaced points defining a cycle of an audible musical waveform are transformed at an average rate corresponding to the fundamental frequency of the tone being generated, a frequency generator is provided using a single clock source for selectively producing the entire frequency range of selected musical notes. A non-integer frequency generator is implemented which periodically adds a frequency number, corresponding to an actuated keyswitch, to itself in an accumulator. The integer portion of the accumulator content is used to address out waveshape values stored in a memory. The decimal portion of the accumulator content is used to select the time at which either the current read out waveshape data value or a previously read out waveshape data value is converted into an analog signal by means of a digital-to-analog converter.

Abstract: The generating function cos[Z(t).multidot.sin(.omega.'t)] of Bessel functions is utilized as a modulating function for a fundamental function sin(.omega.t) in synthesis of a musical tone including many harmonic (over tone) components, wherein Z(t) is used as a modulating index. The modulating frequency .omega.' in sin(.omega.'t) of the modulating function cos[Z(t).multidot.sin(.omega.'t)] is selected relative to the fundamental frequency so that w'=n.omega. wherein n is a half integer or an irrational number.

Abstract: An electronic musical instrument which has a keyboard and creates a musical tone by striking keys of the keyboard, is provided with an operation control circuit and an adder both for effecting keyboard switch chattering prevent operation processing and touch response select operation processing, a timing control circuit for controlling the switching between the chattering preventing operation and the touch response detecting operation and the scanning of the keyboard switches to detect their status, a musical tone generator for performing a musical tone generating operation asynchronously with the keyboard switch scanning operation, the keyboard switch chattering preventing operation and the touch response detecting operation, and a transfer circuit for transferring touch response information to the musical tone generator.

Abstract: An electronic keyboard musical instrument is operated by a main system computer in a manner dependent on the settings of input elements. A plurality of tone modules are used, each of which comprises a subsystem computer including a subsystem bus, a memory and a microprocessor. Data is exchanged between the main system computer and a subsystem computer through a bus switch which alternately connects the subsystem memory with the main system bus and the subsystem bus. This allows for an effectively "real time" exchange of data between the main system and the subsystem.

Abstract: An electronic musical instrument capable of producing, by frequency modulation, a musical tone containing harmonic components of integer and non-integer orders at complicated ratios which change with time. In frequency modulation, amplitudes of carrier and side frequencies are preceded by a positive or negative sign depending upon a value of modulation index. By suitably setting the value of modulation index, phase inversion occurs in the side frequencies so that cancellation or augmentation of amplitude will occur between side frequencies of the same frequency. By utilizing this phenomenon and also the fact that the harmonic spectrum can be varied by varying the carrier and the modulating waves, the electronic musical instrument according to the invention produces a musical tone containing extremely complex harmonic components.

Abstract: A keyboard operated electronic musical instrument is disclosed which has a number of tone generators each of which is assigned to an actuated keyswitch. The generated musical waveshapes are transformed to produce tones having a time variant spectra by processing the waveshapes with a time variant masking function.

Abstract: An electronic musical instrument is provided with a first programmable counter for generating a reference clock signal corresponding to a musical frequency and a plurality of cascade-connected programmable counters which are each triggered by the preceding programmable counter. A multi-level signal which assumes one of a plurality of levels for each period specified by one of the cascade-connected programmable counters is output as a primary waveform. The electronic musical instrument is capable of setting various variations of the primary waveform abundantly containing harmonics and is satisfactory in the tone quality and in the degree of freedom in setting tones, and hence is of high musicality.

Abstract: In a electronic musical instrument wherein a portamento is played by supplying the pitch voltage corresponding to a subsequently depressed key to a capacitor holding the pitch voltage corresponding to a previously depressed key, the charge and discharge currents of the capacitor corresponding to the difference between the two pitch voltages are controlled to vary exponentially thus changing exponentially the capacitor terminal voltage. The terminal voltage of the capacitor is applied to drive a voltage controlled oscillator to vary its oscillation frequency. To vary exponentially the terminal voltage of the capacitor, a mutual conductance converter is connected between the capacitor and a keyboard section and the output current from the mutual conductance converter is controlled by a control signal corresponding to the terminal voltage of the capacitor.