JPS6338718B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a musical waveform generator for an electronic musical instrument, and is particularly suitable for application to a waveform memory storage type device. Conventionally, as a musical waveform generator using a waveform memory storage method, for example, a patent application filed in 1972 by the applicant of the present patent,
- There is a disclosure in No. 133913. In this conventional example, waveform information consisting of a triangular wave, sine wave, etc. is stored in a waveform memory in advance, and a musical waveform signal can be output by reading out the address using an addressing signal consisting of a Gray code signal. Such a configuration is shown, and utilizes the following properties of the Gray code signal. For example, a 5-bit binary code signal _BC5 to _BC1
When converted into a Gray code, 4-bit Gray code signals GC ₄ to _{GC 1} as shown in Table 1 are obtained.

【table】

[Table] The Gray code signals GC ₄ to _{GC 1} change symmetrically around the point where the binary code signals BC ₅ to _{BC 1} change from 15 to 16 in decimal. Therefore, if these Gray code signals GC ₄ to _{GC 1} are used as address signals of the waveform memory, the first half of the change in Gray code signals GC ₄ to _{GC 1} (binary code signal
BC ₅ ~ BC ₁ decimal representation corresponds to 0 to 15) and the latter half (binary code signal BC ₅ ~ _{BC 1} decimal representation 15)
to 31), the readout direction is reversed, and by using this, it is possible to read out one period of a triangular wave by simply storing the waveform for half a period of the triangular wave in the waveform memory. By the way, the top 3 of Gray code signals GC ₄ to GC ₁
Bit signal GC ₄ ~ GC ₂ and binary code signal BC ₅ ~
When the signal BC ₅ of the most significant bit of BC ₁ is added to form 4-bit signals BC ₅ , GC ₄ , GC ₃ , and GC ₂ , these signals BC ₅ to GC ₂ are converted into Gray code signals GC as shown in Table 2. The signal changes in the same way as the first half of the change of ₄ to GC ₁ (corresponding to 0 to 8 in decimal notation of the Gray code signals GC ₄ to _{GC 1} ), and repeats the same value twice. In other words, the signals BC ₅ to _{GC 2} change in the same way as the first half of the Gray code signals GC ₄ to GC ₁ , and their repetition period is equal to that of the Gray code signals GC _{4 to} GC 1.
It is the same as the repetition period of GC ₁ .

【table】

[Table] The present invention utilizes the above-mentioned properties of the Gray code to devise a reading method for a waveform memory, thereby reading out the waveform of a musical waveform signal output from the waveform memory in one direction as needed, and repeating the waveform. Another object of the present invention is to propose a musical sound waveform generator capable of switching to a reciprocating readout repetitive waveform. That is, in this invention, a multi-bit binary code signal that repeatedly changes in accordance with the pitch of a musical tone to be generated is first converted into a Gray code signal, and the first address signal consisting of this Gray code signal or this A selection circuit is provided for selecting one of a second address signal consisting of a signal of other bits other than the least significant bit of the Gray code signal and a signal of the most significant bit of the binary code signal. By using the thus selected first or second address signal as an addressing signal for the waveform memory, it is possible to output a musical waveform signal having a unidirectional readout repetitive waveform or a reciprocating direction readout repetitive waveform from the waveform memory. Make it. Further, in the present invention, there is provided a logic level specifying means for selectively specifying the logic level of the most significant bit of the binary code signal to the logic "0" level, thereby allowing musical waveform signals of different feet to be specified as necessary. It is possible to output from the waveform memory. Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the accompanying drawings. FIG. 1 shows an embodiment of a musical sound waveform generator for an electronic musical instrument according to the present invention. In Figure 1, 2 is input as a manual address signal.
The hexadecimal code signals O ₁ to O ₆ are converted in an address signal conversion means composed of a Gray code conversion circuit 1 and a selection circuit 2 according to conversion conditions determined based on the read direction selection signal SE and the foot switching signal OU. , decoder 3 as the addressing signal
The signal is applied to the waveform memory 4 via the waveform memory 4. The input signals O ₁ to _{O 6} are binary code signals and sequentially change according to frequencies corresponding to pitches. These 6-bit binary code signals O ₁ to O ₆ are first applied to the Gray code conversion circuit 1 . Here, the most significant bit signal O ₆ of the binary code signals O ₁ to O ₆
is applied to the address signal converting means as a signal O ₆ ' through an AND circuit A1 which is operable by a signal whose logic level has been inverted by an inverting circuit IN1, but this AND circuit A1 is later As will be described in detail, when the signal OU is at logic "1", it is inactive, thereby forming a sawtooth waveform signal of a different foot (one octave higher). In this example, the signal OU
When the signal _O6 is the logic "0", the signal _O6 is input to the Gray code conversion circuit 1 and the selection circuit 2 via the AND circuit A1 as the most significant bit signal O6' of the binary code signal. When is logic "1", the logic level of the output terminal of AND circuit A1 is held at logic "0", and thus the logic level of the most significant bit of the binary code signal input to Gray code conversion circuit 1 and selection circuit 2 is selectively designated to the logic "0" level. The Gray code conversion circuit 1 includes five exclusive OR circuits EX1 to EX5, and converts 6-bit binary code signals _O1 to _O6 into 5-bit Gray code signals _GC1 to _GC5 . Table 3 shows how the Gray code conversion circuit 1 converts the binary code signals O ₁ to O ₆ to the Gray code signals GC ₁ to _{GC 5} .

[Table] As is clear from Table 3, Gray code signal
GC ₅ to GC ₁ change symmetrically around the point where the binary code signals O ₁ to O ₆ change from 31 to 32 in decimal notation. The Gray code signals GC ₁ to _{GC 5} outputted from the Gray code conversion circuit 1 and the signal O ₆ of the most significant bit of the binary code signal via the AND circuit A 1 are applied to the selection circuit 2 . The selection circuit 2 consists of 10 AND circuits A2 to A11 and 5 OR circuits OR1 to OR5, and the signal SE
Gray code signals GC 1 to GC 5 outputted from the Gray code conversion circuit 1 in accordance with the gray code conversion circuit ₁ or other signals GC ₂ to GC ₅ except for the signal GC ₁ of the least significant bit of this Gray code signal and via the _AND circuit A1. I did 2
One of the signals consisting of the most significant bit signal _O6 of the hexadecimal code signal is switched and selected. That is, when the signal SE is "1", the AND circuit A2~
A6 becomes operational, selects the output of AND circuit A1 and signals GC ₅ to _{GC 2} of the upper 4 bits of Gray code signals GC 1 to GC ₅ , and sends them to decoder 3 via OR circuits OR5 to OR1, respectively. Add as the second address signal. Also, signal SE is “0”
, the logic level of this signal SE is inverted by an inverting circuit.
The signal inverted by IN2 enables AND circuits A7 to A11 to operate, selects Gray code signals _GC5 to _GC1 , and outputs them to the OR circuits.
It is applied as a first address signal to the decoder 3 via OR5 to OR1. The decoder 3 receives a total of 5-bit signals O ₆ , consisting of the output of the AND circuit A ₁ and upper 4-bit signals GC ₅ to GC ₂ of the Gray code signals GC ₁ to GC 5.
GC ₅ , GC ₄ , GC ₃ , GC ₂ or 5-bit Gray code signals GC ₅ to _{GC 1} are sent to 32 output lines l ₀ to l ₃₁
The signal is decoded and output to form an addressing signal for reading out the waveform memory 4. Here, the signals O ₆ , GC ₅ ,
GC ₄ , GC ₃ , GC ₂ as Gray code signal GC ₅ ~ _{GC 1}
Table 4 shows this based on the relationship with .

【table】

Claims (1)

[Scope of Claims] 1. A multi-bit binary code signal that repeatedly changes in accordance with the pitch of a musical waveform signal to be generated is converted into a multi-bit Gray code signal in a Gray code conversion circuit, and is converted almost linearly. By specifying each address of the waveform memory in which waveform information representing sample values of a monotonically increasing or monotonically decreasing waveform is stored using an addressing signal formed based on the Gray code signal, reading is performed from the waveform memory. In a musical sound waveform generator for an electronic musical instrument, the musical sound waveform signal is generated based on the output waveform information, a first address signal consisting of the Gray code signal output from the Gray code conversion circuit;
selecting means for selecting one of the bits other than the least significant bit of the Gray code signal and a second address signal consisting of the most significant bit of the binary code signal and outputting the selected one as the addressing signal; When the first address signal is selected and outputted by the selection means, a musical sound waveform signal corresponding to the reciprocating readout repetition waveform of the waveform that monotonically increases or decreases almost linearly is generated, and the music waveform signal is outputted to the selection means. Therefore, when the second address signal is selectively outputted, a tone waveform signal corresponding to the unidirectional readout repeating waveform of the waveform that monotonically increases or decreases in a substantially linear manner is generated. Musical sound waveform generator for electronic musical instruments. 2. Converting a multi-bit binary code signal that repeatedly changes in response to a desired pitch into a multi-bit Gray code signal in a Gray code conversion circuit;
By specifying each address of the waveform memory in which waveform information representing sample values of a waveform that increases or decreases monotonically in a substantially linear manner is stored using an addressing signal formed based on the Gray code signal, In a musical sound waveform generator for an electronic musical instrument configured to generate a musical sound waveform signal based on waveform information read from a waveform memory, a first address signal consisting of the Gray code signal output from the Gray code conversion circuit; and,
a selection means for selecting one of the bits other than the least significant bit of the Gray code signal and a second address signal consisting of the most significant bit of the binary code signal and outputting it as the addressing signal; logic level designation means for selectively designating the logic level of the most significant bit of the hexadecimal code signal to the logic "0" level, and when the selection means selects and outputs the first address signal, the above-mentioned approximately When a musical waveform signal corresponding to a repeating reciprocating waveform of a linearly monotonically increasing or monotonically decreasing waveform is generated, and the selection means selects and outputs the second address signal, the almost linearly monotonous signal is generated. A musical waveform signal corresponding to a unidirectional readout repeating waveform of an increasing or monotonically decreasing waveform is generated, and the logic level of the most significant bit of the binary code signal is set to a logic level by the logic level specifying means. 1. A musical sound waveform generator for an electronic musical instrument, characterized in that when a 0'' level is specified, a musical sound waveform signal having a pitch one octave higher than the desired pitch is generated.