Nippon Gakki Seizo Kabushiki Kaisha

Mitsumi Katoh

Masatada Wachi

Koji Niimi

Tokuji Hayakawa

A plurality of waveshapes of different characteristics are stored in a waveshape memory among which a waveshape to be read out is selected in accordance with a selected tone color or elapse of time and data of the selected waveshape is read out. At least one waveshape among the waveshapes stored in the waveshape memory is coded in a coding form different from one used for the other waveshapes. For matching characteristics of each individual waveshape, waveshapes are coded according to respectively suitable coding forms such, for example, that one waveshape is coded according to the pulse code modulation system, another waveshape according to the differential pulse code modulation system and still another waveshape according to the delta modulation system. The waveshape data read out from the waveshape memory is converted in its code to a predetermined common coding form (e.g. PCM). By differring the coding form of waveshapes stored in the waveshape memory, reduction in the memory capacity and improved resolution in reproduced waveshapes matching characteristics of individual waveshapes can be achieved.

Tone signal generator with code converter for converting stored

A waveshape memory stores waveshape data representing plural waveshapes each having plural periods. A reading sequence controller designates ones to be read out among said waveshape data from the waveshape memory and the readout order thereof. This order may either be a random order or a predetermined one. By performing the readout of the waveshape data, repetitive reading of the same waveshape data is basically avoided, and a periodical noise and monotonousness in the tone color which tend to arise from such repetitive reading are eliminated.

Tone signal generation device

The present invention provides a tone color control so that the tone color in an attack portion of a tone to be generated differs depending upon whether or not a slur effect is to be imparted. If, for example, the slur effect is not imparted, a tone color for an attack portion of a tone which is rich in variation is used, whereas if the slur effect is to be imparted, a stable tone color which is the same as the sustain portion of a tone is used. In another aspect of the invention, in the case of imparting the slur effect, a tone signal is distributed to two channels and envelopes of signals in the respective channels are separately and independently controlled by separate control signals. In one channel, a control signal of decay characteristics is used whereas in the other channel, a control signal of attack characteristics is used. The changing rate of the control signal of the attack characteristics is made greater than that of the control signal of the decay characteristics.

Slur effect pitch control in an electronic musical instrument

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. The interpolation circuit receives the amplitude sampled values and the interpolation parameter (i.e., the decimal section of the address signal) respectively in a pitch synchronized state and performs the interpolation operation in the pitch synchronized state. The timing of the interpolation operation thereby is synchronized with the pitch of the generated tone so that inharmonic noise components are substantially removed.

Tone signal generation device with interpolation of sample points

A digital filter is provided between a tone signal generation circuit which supplies a digital tone signal in accordance with a first sampling frequency and a sampling circuit which resamples this digital tone signal in accordance with a second sampling frequency which is lower than the first sampling frequency. This digital filter filters the input digital tone signal with such amplitude-frequency characteristics as to be able to substantially remove an aliasing noise produced due to the second sampling frequency (e.g., with low-pass filter characteristics having a cut-off frequency which is 1/2 the second sampling frequency). This removes high frequency components producing an aliasing noise from the digital tone signal before it is applied to the resampling circuit whereby generation of the aliasing noise in resampling is prevented. The resampling is performed for adapting the digital tone signal to an operation clock frequency of an effect imparting circuit provided in a posterior stage for imparting, in digital, a tone effect such as a modulation effect to the digital tone signal.

Tone signal processing device

Plural channels of tone generation capable of selectively generating plural kinds of waveshape signals are provided. A waveshape signal to be selected in each of the channels is designated in accordance with the tone pitch or tone range of a tone to be generated and waveshape signals which differ from each other between the channels are respectively generated. The different waveshape signals of the respective channels are weighted by scaling parameters according to the tone pitch. A circuit capable of providing the waveshape signal with amplitude envelopes which differ from each other between the channels is further provided and selection between imparting of such envelopes and weighting in accordance with the scaling parameter is made in response to a tone color. A plurality of tone synthesis systems having the tone synthesis function described may be provided and tone signals obtained in the respective systems may be added together.

Electronic musical instrument controlling a tone waveshape by key scaling

A digital filter imparting a desired tone color to the tone signal is realized by the combination of a digital pole filter and a digital zero filter capable of controlling a pole and a zero in an amplitude-frequency characteristic respectively. The amplitude-frequency characteristic of the digital filter is a composite of the respective characteristics of the pole filter and the zero filter. A 'peak' portion and a 'valley' portion in this composite characteristic can be set independently by the pole control of the pole filter and the zero control of the zero filter, whereby the desired tone color characteristic can be readily realized. Further, the digital filter may comprise a plurality of digital filters having respective different constructions and a connection switching circuit capable of setting arbitrarily connection between these filters. The filter characteristic as a whole can be diversely altered by changing the connection, whereby diverse tone color characteristics can be realized with ease.

Digital filter for an electronic musical instrument

An electronic musical instrument comprises a keyboard, a tone generator and a digital filter. The tone generator bit-serially generates a musical tone signal corresponding to a depressed key on the keyboard. The digital filter bit-serially performs a digital filtering operation of the musical tone signal in accordance with the predetermined amplitude-frequency characteristic. A musical tone is produced based on an output of the digital filter, whereby the characteristic is imparted to the musical tone. This bit-serial processing in the digital filter makes not only the circuit construction of the digital filter itself but also that of the electronic musical instrument incorporating this digital filter smaller and simpler.

A frequency number corresponding to the frequency of a tone intended to be sounded is accumulated in an accumulator at every calculation timing of a constant interval to produce values progressing at a rate corresponding to the tone frequency. At this rate, waveform amplitude value samples are sequentially produced one after another in a tone producing section using the output of the accumulator as phase angle data. A reset circuit is provided in connection with the accumulator and this circuit functions to compulsorily reset the progressing values in the accumulator to its initial value in response to a carry out signal generated at the calculation timing when the phase angle data has reached its predetermined modulo value. Thus the period of progress of the phase angle data is harmonized with the calculation timing, i.e., the sampling timing. As a result, the frequency of a tone waveform signal, whatever it may be, can be harmonized with the sampling frequency while the interval of the respective sampling timing is maintained constant.

Electronic musical instrument forming tone waveforms

A musical tone is synthesized by controlling harmonic components of a note selected in a keyboard in accordance with a desired fixed formant. A parameter computation circuit detects a harmonic frequency which is nearest to a center frequency of the fixed formant and produces FM computation parameters using the nearest harmonic frequency as a carrier frequency and a fundamental or harmonic frequency of the selected note as a modulating frequency. A frequency modulation circuit performs an FM computation on the basis of these parameters and, as a result, a tone whose harmonic components have been controlled in accordance with a formant having the nearest harmonic frequency as a central component is synthesized. The parameter computation circuit computes frequency difference between the nearest harmonic frequency and the center frequency of the fixed formant for controlling the level of a formant synthesized in a frequency modulation circuit in accordance with this frequency difference. This level control is achieved by controlling an amplitude coefficient of a tone or a modulation index in the FM computation. A subformant having as its central component another harmonic frequency in the vicinity of the nearest harmonic frequency may be formed in a relatively low level for reinforcing the formant with this subformant.

Electronic musical instrument of fixed formant synthesis type

In a wave shape generator of the memory reading type, a waveshape memory stores sample values of a wave each value being represented by an integral address. A coefficient memory stores coefficients for nth order interpolation. Unknown intermediate sample values not stored in the wave shape memory represented by non-integral addresses and are approximated by multiplication of stored sample values of the waveshape and corresponding coefficient values on the basis of nth order interpolation. Use of the interpolation method assures smoothness of the wave shape with respect to time and thereby minimizes quantization noise while permitting use of relatively small memories.

Waveshape generator for electronic musical instruments

An electronic musical instrument is provided with a plurality of wave shape memories storing different musical tone wave shapes of different memory sizes for different tone ranges. The memory for the treble tone is of a small size and that for the bass tone is of a large large size. When a key is operated in the keyboard, a memory corresponding to the tone range to which the operated key belongs is selected and read out. While successfully avoiding economically disadvantageous increase in the memory size of the wave shape memories, beautiful and clear musical tones can be obtained having different tone colors for different tonal pitches just like those generated by natural musical instruments.

Growing community of inventors

Hamamatsu, Japan

Mitsumi Katoh