JPS59102289A - Envelope controlling circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an envelope control circuit, and more particularly to a circuit for controlling the envelope of an output musical tone signal in an electronic musical instrument.

Generally, envelope control in electronic musical instruments is performed by using a multiplier to multiply the count output from an envelope counter by data read from a waveform ROM in which waveform data is stored. In this case, in order to minimize the waveform distortion of the output tone waveform deviation that is subjected to comparator control, the h1 value of the envelope counter is changed in synchronization with the data read from the waveform ROM.

That is, when the output data from the waveform ROM is at its center zero level, the envelope counter is advanced, thereby changing the envelope without distorting the output waveform.

However, when the desired waveform period is long, that is, when outputting waveform data with a low pitch, and the envelope rise time is set to be extremely short, conventional synchronization methods cannot satisfy this requirement. On the other hand, if the envelope counter is advanced to set the rising 9 time to the desired value, the waveform data will be distorted.
This has the disadvantage that a beat sound is generated, which significantly impairs the quality of the multiplication signal.

Therefore, an object of the present invention is to provide an improved envelope control circuit that does not reduce the quality of the obtained musical tone signal even if the envelope is controlled so that a musical sound waveform with a relatively long period rises in a short time. It is about providing.

Hereinafter, the present invention will be explained in detail with reference to the illustrated embodiments.

FIG. 1 shows a block diagram of an embodiment of a tone waveform generation circuit including an envelope control circuit according to the present invention. The musical sound waveform generating circuit 1 generates the basic l of a desired musical sound waveform.
The waveform ROM 2 has a waveform ROM 2 in which sampling data for cycles is stored, and the waveform ROM 2 is stored in accordance with the address data D of the address counter 4 that counts the pitch clock cK1 output from the pitch pulse generation circuit 3.
The sampling data of the basic waveform stored in the memory is read out every j pulses.

The pitch pulse generation circuit 3 generates pitch name data D2 and octave cheetah D out of press information from a keyboard (not shown).
This is a circuit for outputting a pitch clock CKl at a pitch corresponding to the frequency ft)fz+ of each of the 12 tones of the highest octave. , , has 12 oscillators 51.52.6.512 each outputting a pulse signal "1 y "2 r-, PI3 of a frequency related to f12,
These pulse coefficients P1 t "2 'r --"1
2, a pulse signal having a frequency corresponding to the note name indicated by the note name data D2 is selected by the multiplexer 6 and inputted to the frequency divider 7.

Frequency divider 7ba, μ frequency divider "'" t82r,
--8n are connected in cascade, and the output pulse signals Q1, Q2, . . . , Qn from each residual frequency divider and the output pulse signal QO from the multiplexer 6 are input to another multiplexer 9. The octave data D3 is applied to the multiplexer 9 and the ! The output pulse signal is selectively output according to the octave designated by the octave data D3.

As a result, pitch name data D is used as pitch clock CK1.
2 and octave data D3.The waveform ROM 2 outputs the note name and octave data D2.

Tone waveform data D4 having a frequency according to D3 is output.

The musical sound waveform data D4 is the envelope ft1lJ control f
-Envelope control data D5 from evening generation circuit 10
The output waveform data D6 having envelope characteristics according to the envelope control data D5 is input to the D/A converter 12.

The output waveform data D6 is converted into an analog signal by the ≠converter 12 and output as a desired musical waveform signal S.

Envelope control data generation circuit RI Id, multiplexer 13 that selects and outputs any one of the output pulse signals Qo to Qn, variable frequency divider that divides the output pulse signal O from the multiplexer 13 by 1β Vessel 14. The envelope counter 15 outputs envelope control data D5 based on the envelope clock pulse ECL from the variable frequency divider 14.

Multiplexer l: (, ROM 16, 1 corresponding to the variable frequency divider 14 and envelope counter 15, respectively)
7 and 18 are provided, and these ROMs 1.6
, 17 and 18 are input with control data D7 consisting of pitch name data, rise data indicating the rise time of the envelope, and fall data indicating the fall time of the envelope, respectively. The ROM 15 outputs selection control data D8 for controlling the selection operation of the multiplexer 13 in response to the control data D7, and outputs a predetermined output pulse signal to the multiplexer according to the content of the control data D7. output from J3, ROM17 is variable frequency divider 1
The frequency division control data D9 for determining the frequency division ratio of 4 to 1 is output, and the output pulse signal 0' (i7 is divided by the frequency division ratio according to the frequency division control data D9. Output pulse number 3 Q1o to Q
Each frequency of n is determined by the value of the pitch name data at that time. Therefore, once the pitch name is specified, it is difficult to determine which output pulse signal to use and how to set the frequency division ratio. It can be preprogrammed to obtain envelope clock pulses EcL- of different frequencies.

The envelope counter 15 uses the 3-bit control data Dlo output from the ROM 113 to determine the increment of the count contents of the envelope counter 15 when one envelope clock pulse ECL is input, and uses the addition/subtraction control data Dll to determine the increment of the count contents of the envelope counter 15 when one envelope clock pulse ECL is input. , the addition/subtraction mode of the envelope counter J5 is turned off. A data map of the ROM 18 is created so that the contents of the control data D10 and the adjustment control data Dll are determined according to the contents of the control data D7 (V).In the end, the output data map of the envelope counter 15, the frequency of the envelope clock pulse ECL, It is determined by control data DIG and adjustment control data Dll.

In this way, the multiplexer 13 and the frequency divider 14 obtain an envelope clock pulse ECL of a predetermined frequency according to the data map of the ROM 16.17 based on one of the output pulse signals Qo to Qn. , so that a predetermined synchronous relationship is established between the data read from the waveform ROM 2 and the data read from the envelope counter 15. In other words, the frequency of the clock pulse that advances the contents of the envelope counter [5] is the frequency of the musical sound waveform data D4 outputted from the waveform ROM2, or an integer multiple. No beat sound is generated.

(
That is, when the contents of the control data D7 are determined), the envelope data DII (data DII) required for outputting the envelope 1 data D9 is determined based on this condition.
Although a plurality of combinations of p Dlo HDll can be considered, the contents stored in each ROM 16 , 17 , and 18 are determined so that one of the combinations is output.

FIG. 2 shows a concrete block diagram showing the configuration of the envelope counter 5. As shown in FIG. In Figure 2, 2
1 is a decoder that explains the contents of the data D10, and the number of outputs corresponding to the contents of the data Dlo becomes "H" level.

Each output number of the decoder 21 is inputted to the input terminal group A1 to A8 of the adder/subtractor B via the gate circuit 22, and the 8-bit input terminal group B1 to B8 is inputted to the other input terminal group B1 to B8. The outputs of the latch circuits are connected to each input of the latch circuit, and each input of the latch circuit is connected to the output terminal of the adder/subtractor.
! to OB are connected to each other.

According to such a configuration, when the level of the envelope clock pulse FCL is set to a high level every K, the input terminal AI
(The level of the input terminal corresponding to the contents of the data D10 among A8 to A8 is VH' level), and the data Y indicated by the level state input to the input terminals Al to A8 is added to the output data X of the latch circuit group. , added or X
Y is subtracted. Whether an addition operation or a subtraction operation is executed is determined according to the level of the addition/subtraction control data D11. The calculation result of addition or subtraction is output from output terminals 01 to o8, and sent to the latch circuit group.
It is latched at a predetermined timing. Therefore, a counting operation is performed in which the number Y determined by the data Dlo is added to or subtracted from the value of the data X every time the envelope clock pulse FiCL reaches the rJ level.

According to the present invention, as described above, envelope control data is created based on a frequency-divided signal for creating a read clock for the waveform ROM, and the frequency of the clock pulse that advances the contents of the counter for creating the envelope control data is adjusted. Since the frequency of the musical waveform data output from the waveform ROM is configured to be a number of times or a fraction of an integer, there is a problem that the beat sound is superimposed on the output signal obtained as a result of envelope control. is eliminated, and no matter what envelope control is performed, a high quality musical waveform signal can always be obtained.

[Brief explanation of drawings]

FIG. 1 is an embodiment of a tone waveform generation circuit including an envelope control circuit according to the present invention, and FIG. 2 is a detailed block diagram of the envelope counter shown in FIG. 1. 1... Musical waveform generation circuit 2... Waveform ROM 3... Pitch pulse generation circuit II)... Envelope control data generation circuit 13...
-Multiplexer 14...Variable frequency divider 15-@Φ envelope counter 16, 17, 18...ROM D2...Pitch name data D3...Octave data l)4...Music waveform data D5 -Φ envelope control data D6 ... Output waveform data D7 ... Control data D8 ... Selection control data D, ... Frequency division control data Dlo ... Control data Dll ... Adjustment control data Applicant: Co., Ltd.

Claims (1)

[Claims] In the envelope control W+ circuit, the envelope control W+ circuit is configured such that a desired envelope characteristic is given to the musical sound waveform data by multiplying the output data from the envelope counter and the musical sound waveform data read from the waveform ROM in a multiplier. An envelope control circuit characterized in that the frequency of the clock pulse that increases or decreases the output data of the counter is an integral multiple or an integral fraction of the frequency indicating the pitch of the musical waveform data.