JPS5830597B2 - Tone control device for electronic musical instruments - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses an electric signal control filter whose filter characteristics can be changed using an electric signal to change the timbre of a musical tone, and an arithmetic level control filter that controls the cutoff frequency of the electric signal control filter. Regarding a sound source device for an electronic musical instrument that uses an antilogarithmic amplifier using a semiconductor PN junction as an antilogarithmic conversion element to convert voltage into a cutoff frequency that changes geometrically correspondingly, This eliminates the need for temperature-sensitive resistors for temperature compensation, which are essential to amplifiers.

A VCO (voltage controlled oscillator) is used in the sound source of conventional electronic musical instruments, particularly music synthesizers, to obtain a scale frequency corresponding to a pressed key.

That is, a method is often used in which a VCO is controlled using a geometric voltage obtained by converting an arithmetic voltage corresponding to each weight using an inverse logarithmic amplifier to obtain a scale frequency corresponding to the pitch of each weight.

Similarly, a VCF (voltage control filter) is used in the tone forming section of a music synthesizer, which changes the tone of the musical tone over time to create a powerful sound, and at the same time adjusts the scale frequency of the key pressed. By correspondingly moving the cutoff frequency of the VCF, a substantially constant timbre is maintained even when the musical range changes (the spectrum of musical tones is kept substantially constant).

That is, a method is often used in which a cutoff frequency corresponding to the pitch of each weight is obtained by controlling the VCF using a geometric voltage obtained by converting an arithmetic voltage corresponding to each weight using an inverse logarithmic amplifier.

Moreover, most antilogarithmic amplifiers use PN junctions such as transistors and diodes as antilogarithmic conversion elements.

The electric EV-current IM characteristic of a semiconductor PN junction is I −l5
It is expressed as exp (dT).

Here, Is is the reverse saturation current, k is the Boltzmann constant, T is the Kelvin temperature, and q is the amount of electron charge.

That is, the PN junction has an inverse logarithm conversion element, but also has a change element due to temperature T.

In particular, although the reverse saturation current Is is small in absolute value,
It changes almost exponentially with temperature changes, so when configuring an antilogarithm amplifier, one of a pair of PN junctions with well-matched voltage-current characteristics, such as a pair of transistors, is used for voltage-current antilogarithm conversion. , the other is used for canceling the inverse saturation current Is to eliminate fluctuations in the inverse logarithm conversion characteristic due to temperature changes in the inverse saturation current Is.

However, since the temperature T in the above characteristic equation is in the exponential term, pairability cannot be compensated for.

For this reason, in conventional anti-logarithmic amplifiers, temperature-sensitive resistors whose resistance changes in direct or inverse proportion to temperature are used to cancel out the temperature T in the characteristic equation. The resistance coefficient is nonlinear, and even if various combinations are tried, it is impossible to completely match the desired temperature compensation characteristics over a wide temperature range.

Moreover, the resistance value and temperature coefficient of the temperature-sensitive resistor vary widely, and even if it happens to be possible to compensate for the temperature with a certain 11 resistors, when mass-produced, it is not possible to completely compensate for the temperature of all the resistors.

Furthermore, in order to achieve complete temperature compensation, selecting a temperature-sensitive element can be expensive.

Therefore, although the inverse logarithmic amplifier plays an important role in music synthesizers, it is not possible to completely compensate for the temperature including variations, so even if a VCF with high temperature stability is used, the inverse logarithmic amplifier cannot be used. The temperature stability of the tone had to be poor.

The present invention was made to eliminate the above-mentioned drawbacks, and by using an arithmetic difference voltage that changes in proportion to temperature and corresponds to the cutoff frequency of the electrical signal control filter as an input to an antilogarithmic amplifier, A geometric electrical signal (current or electric current l'E) that is proportional to the cutoff frequency and stable with respect to temperature changes.
The present invention provides a timbre control device for an electronic musical instrument that can provide the following.

Examples thereof will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a temperature-sensitive senior official generation circuit that generates a voltage vT that changes in proportion to the temperature T (OK).

2 is a cutoff frequency control generation circuit that generates a cutoff frequency control voltage VPO that changes in proportion to the temperature T (OK) and corresponds to the cutoff frequency fc;
The scale voltage that changes in proportion to the scale frequency ■K
A scale voltage generation circuit 21 that generates a scale voltage, and a cutoff frequency shift voltage E that changes in proportion to the temperature T and has a variable level setting.
It is composed of a cutoff frequency shift voltage generation circuit 22 that generates Vps, and an addition circuit 23 that adds the scale voltage vK and the cutoff frequency shift chief VPS at an appropriate level to generate a cutoff frequency control voltage vpc. There is.

3 is an antilogarithmic amplifier using a semiconductor PN junction as an antilogarithmic conversion element, and temperature compensation for antilogarithmic conversion percentage is not performed.

The anti-logarithmic amplifier 3 performs anti-logarithmic conversion on the cut-off frequency control voltage ■Pc to obtain a current I (3=Aexp(BYpc
/T) is output.

However, A and B are constants not related to temperature T, and T indicates Kelvin temperature (0K).

4 is a current control filter whose cutoff frequency fc changes in direct proportion to the input current IC.

40 and 41 are a sound source signal input terminal and an output terminal, respectively.

Next, the operation of the embodiment shown in FIG. 1 will be briefly explained.

The anti-logarithmic conversion characteristic of the anti-logarithmic amplifier 3 which is not temperature compensated explicitly includes the temperature T as described above, and has a large temperature dependence.

If an input voltage that cancels out this large temperature dependence is applied to the input of the antilogarithmic amplifier 3, the output current IC will be stable against temperature changes, and the cutoff frequency fc, which changes in proportion to the current IC, will also change with temperature. It is stable against.

This is proved as follows.

This is the output of the cutoff frequency controlled electrostrictive generation circuit 2.

Cutoff frequency stability EVPO is proportional to temperature T.

That is, it is expressed as controlled EVPO=KT.

However, K is a constant that can be set in accordance with the cutoff frequency fc.

The output current IC of the anti-logarithmic amplifier 3 is expressed as < , I (
3=A exp(BVpc/T).

By substituting VPO=KT into this equation, I C= Aex
p (B K ), and the temperature T disappears.

Therefore, the current IC becomes stable against temperature changes.

Next, an example in which each block of the example shown in FIG. 1 is realized by a specific electric circuit will be shown below.

FIG. 2 shows a specific embodiment of the temperature-sensitive voltage generating circuit 1.

11 and 12 are high input impedance differential amplifiers;
Reference numerals 3 and 14 designate a pair of transistors having the same electromotive current characteristics, and 15 to 18 designate resistors that are stable against temperature changes.

The resistors that ground the non-inverting inputs of the differential amplifiers 11 and 12 are connected to the input bias current I of the differential amplifiers 11 and 12, respectively.
This is to remove the offset caused by B.

In addition, a capacitor between each output of the differential amplifiers 11 and 12 and the inverting input, and a capacitor between the output of the differential amplifier 12 and the transistor 13
, 14 and the resistor 19 is provided to maintain good frequency stability of the circuit 1.

Next, the operation of the temperature sensitive voltage generating circuit 1 will be explained.

Base-emitter type EVB of transistors 13 and 14
Et+VBE2, and the collector current is IOt, respectively.
When t IO2, the following relational expression holds true if the base minister and collector voltages are at approximately the same potential.

However, ■s1. ■s2 are transistors 13 and 13, respectively.
14, k is the Boltzmann constant, q is the electron charge, and T is the Kelvin temperature.

Negative feedback is applied to the differential amplifier 11 through a resistor 18 and transistors 14 and 13, and the differential amplifier 12 is connected to a resistor 19.
Since negative feedback is applied through the transistor 14, the inverting inputs of the differential amplifiers 11 and 12 are both at ground potential.

Also, this is because the input impedance of the differential amplifiers 11 and 12 is sufficiently high.

The output voltage of the differential amplifier 11 is VT, and the transistor 1
If the base power of 4 is vB, then the following holds true.

The base of transistor 13 is grounded, and transistor 1
Since both emitters 3 and 14 are connected, the following equation holds true.

becomes.

Here, since the characteristics of transistors 13 and 14 are the same, it can be set as ■5L=IS2, and the above equation can be approximated. If we rewrite equation (10) as 1T for VT=, K1 is independent of temperature T. becomes a constant, and VT is proportional to temperature T.

Therefore, the electric current EVT is generated at the terminal 10 as a temperature-sensitive voltage that changes in proportion to the temperature.

From equation (1o), the temperature-sensitive voltage vT is the two resistance ratio R4/R
3. Determined only by R1/R2, power type EVcc
It turns out that it is unrelated.

This shows that the temperature-sensitive voltage generation circuit 1 has an excellent feature of not being affected by fluctuations in the power source, and the temperature-sensitive EVT is used as the cut-off frequency control voltage generation circuit 2 that follows. Considering that he is a senior minister of standards, this is a big advantage.

FIG. 3 shows a specific embodiment of the cutoff frequency control voltage generation circuit 2. In FIG.

The cutoff frequency control voltage generation circuit 2 includes a scale voltage generation circuit 21, a cutoff frequency control voltage generation circuit 22,
It is removed from the adder circuit 23.

The scale voltage generation circuit 21 includes a voltage-current conversion circuit 211 that converts the temperature-sensitive EVT into a current T proportional to vT, and a voltage-current conversion circuit 211 that converts the temperature-sensitive EVT into a current T proportional to vT. Forging pressure generation circuit 2 converting to voltage vK
12, and a sample/hold circuit 213 that temporarily stores the electric current EVK.

Of these, the sample-and-hold circuit 213 is a well-known circuit as shown in FIG. 3, and is not directly related to the purpose of the present invention. This will be explained as a circuit that transmits information.

In the voltage-current conversion circuit 211t of FIG.
Reference numeral 1 denotes a differential amplifier, which together with surrounding resistors constitutes a known inverting amplifier.

2110 is an output terminal of the inverting amplifier.

2114 to 2116 are stable resistance against temperature changes,
2112 is a high input impedance differential amplifier, 21
13 is a FET (field effect transistor).

FET 2113, differential amplifier 2112, and resistor 2114 constitute a known current source, and differential amplifier 2
Since the inverting input and non-inverting input of FET 2112 are kept at the same potential, the output current IT appearing at the drain of FET 2113
is the voltage across the resistor 2115 and the resistance value R of the resistor 2114
It will be divided by 5.

The voltage across the resistor 2115 is as follows, because if the gain of the inverting amplifier constituted by the differential amplifier 2111 is 10 (G is a positive constant), a voltage -GVT is generated at the terminal 2110.

Therefore, the output current (1) of the voltage-current conversion circuit 211 is expressed by the following equation.

becomes.

K1. Since both of and 2 are constants independent of temperature T, current IT is proportional to temperature T.

In the forging pressure generation circuit 212 shown in FIG. 3, 2121 is a high input impedance differential amplifier,
It constitutes a voltage follower that outputs the voltage with low impedance.

2123 to 2126 have mutually equal resistance values R,
It is a resistor that is stable against temperature changes and is connected in series.

One end of the resistor 2123 is grounded, and one end of the resistor 2126 is connected to the output of the voltage drop-current conversion circuit 211.

The key switches are written to correspond to higher scale frequencies.

Therefore, the Oth key switch (the key switch whose terminal is grounded) corresponds to the lowest scale frequency.

Now, when all the key switches are in the OFF state, an equal voltage RIT is generated between the terminals of two adjacent key switches.

When a key switch of any lock is turned on, the terminal of the turned-on key switch is applied to the busper 2122, converted to low impedance by a voltage follower, and output.

When multiple key switches are turned on at the same time, all the turned-on key switches are short-circuited by the busper 2122 and have the same potential, so the key switch corresponding to the lowest scale frequency among the turned-on key switches voltage is output.

That is, the forging pressure generation circuit 212 has a function of generating an arithmetic positive voltage with priority given to bass sounds.

Now, as shown in FIG. 3, if the n-th key switch is turned on, the output voltage vK of the forging pressure generation circuit 212 is as follows, and n + R2Kl I K2 is independent of the temperature T. Since it becomes a constant, the voltage vK is proportional to the temperature T).

The sample/hold circuit 213 is the forging mold generator circuit 212
This circuit is used to temporarily store the output voltage vK when the key is turned on and off, but as mentioned above, this circuit is not directly related to the purpose of the present invention, so it is not used as a circuit that directly transmits the voltage vK. can be handled.

Therefore, the scale voltage generation circuit 21 outputs the arithmetic difference voltage ■K that changes in proportion to the temperature T and corresponds to the scale frequency, as shown in equation (14).

Next, the cutoff frequency shift voltage generation circuit 2 shown in FIG.
2 will be explained.

220 is a three-terminal variable resistor, the output chamber EVT of the temperature-sensitive voltage generation circuit 1 is connected to the third terminal 223, and the output chamber EVT of the temperature-sensitive voltage generation circuit 1 is connected to the first terminal 221.
The output voltage vT of the temperature-sensitive voltage generation circuit 1 is input to the differential amplifier 21.
Electric E-GVT which is inverted and amplified by the inverting amplifier configured by 11.
are applied to each.

The output voltage VPS of the cutoff frequency shift voltage generation circuit 22 is taken out from the second terminal 222 of the three-terminal variable resistor 220.

The cutoff frequency shift voltage generation circuit 22 is a circuit for entirely shifting the cutoff frequency corresponding to a plurality of scale pitches selected by the scale voltage generation circuit 21, and is for example a circuit that shifts the cutoff frequency corresponding to a plurality of scale pitches selected by the scale voltage generation circuit 21. , When the cutoff frequency shift voltage EVPs is zero and a cutoff frequency corresponding to the scale pitch of C3 to C6 is obtained, ■ By generating a shift voltage VPS corresponding to an octave increase, C4 to C4 can be played on the same keyboard. A cutoff frequency corresponding to the C7 scale pitch can be obtained.

In other words, the cutoff frequency can be moved to a desired range without having to manually move the knob of the three-terminal variable resistor 220 up and down, and it is also possible to tune to the desired cutoff frequency.

Now, returning to FIG. 3, it is shown that the cutoff frequency shift voltage VPS is proportional to temperature.

If the No. 2 terminal 222 is located at a location a times (O≦a≦■) the total resistance value of the three-terminal variable resistor 220, the voltage appearing at the No. 2 terminal 222, that is, the cutoff frequency shift voltage EVp 8 is expressed by the following formula.

Therefore, the cutoff frequency shift voltage EVPS is proportional to the temperature.

g(a) is a linear function of a, and the increase in g(a) with respect to the increase in aa, Jg(a), is (l+G)・A
It becomes a.

Therefore, the increase in P8 with respect to the increase in a 5'jAa is 1
1VPs becomes 1T(1+G)la, and an arithmetic change in a appears as an arithmetic change in vps.

Now, in the cutoff frequency shift voltage generation circuit 22, as the voltage to be applied to the No. 1 terminal 221, the voltage -GVT which is inverted and amplified by the inverting amplifier constituted by the differential amplifier 2111 is used. Any voltage of opposite polarity is sufficient, and an inverting amplifier may be provided in the cut-off frequency shift voltage generating circuit 22 to invert and amplify the temperature sensitive voltage ■T and apply it to the No. 1 terminal 221.

However, since this is completely wasteful, in FIG. 3, the voltage to be applied to the No. 1 terminal 221 is obtained from the output terminal 2110 of the inverting amplifier in the scale voltage generating circuit 21.

Next, in the adder circuit 23 of FIG.
are resistors that are stable against temperature changes, and form a resistance adding circuit.

The output voltage VPO of the cut-off frequency control voltage generation circuit 2 is generated at the connection terminal 20 of the resistors 231 to 233.

From FIG. 3, the voltage vPc is expressed by the following equation.

Since the coefficients before the temperature T are all constants unrelated to temperature, the cutoff frequency control voltage Pc is proportional to the temperature T.

Since the output terminal 20 of the adder circuit 23 is connected to the base of a transistor constituting the subsequent antilogarithmic amplifier 3, it is desirable that the impedance of the terminal 20 is sufficiently smaller than the base input impedance of the transistor.

Furthermore, in the embodiment shown in FIG. 3, the output impedance of the cutoff frequency shift senior generation circuit 22 is not zero and may be changed manually, so it is convenient for RIO to be sufficiently larger than R8.

Therefore, regarding the resistance of the adder circuit 23, R8 is relatively small (approximately IK, Q or less in practice), and Ro and RIO
is set relatively large.

FIG. 4 shows a specific example of the anti-logarithmic amplifier 3. Reference numeral 31 is a differential amplifier with high input impedance, 32 and 33 are paired transistors with the same voltage-current characteristics, and 34
is a stable resistance against temperature changes.

This is for removing the offset caused by the input bias current ②B of the differential amplifier 31.

In addition, the capacitor between the output of the differential amplifier 31 and the inverting input, and the resistance interposed between the output of the differential amplifier 31 and both emitters of the transistors 32 and 33 improve the frequency stability of the antilogarithmic amplifier 3. It is meant to be maintained.

Next, the operation of the antilogarithmic amplifier 3 will be explained.

The output chamber EVPO of the cut-off frequency control voltage generation circuit 2 is applied to the base of the transistor 33 as an input, and the current IC driving the subsequent current control filter 4 flows through the collector terminal 30 of the transistor 33.

The base-emitter voltage of transistors 32 and 33 is V
BE3sVBE4 and the collector current is lR, respectively.
2l0, and if the base voltage and collector voltage are at approximately the same potential, the following relational expression holds true, similar to equations (1) and (2).

However, ■s3. ■s4 is each transistor 32
．． 33, k is the Boltzmann constant, q is the amount of electron charge, and T is the Kelvin temperature.

Since the differential amplifier 31 is subjected to negative feedback via the resistor and the transistor 32, the inverting input of the differential amplifier 31 is at ground potential.

Also, since the input impedance of the differential amplifier 31 is sufficiently high, the IR is as follows.

The base of transistor 32 is grounded, and transistor 3
Since the cutoff frequency control voltage VPO is applied to the base of transistor 3 and both emitters of transistors 32 and 33 are connected, the following equation holds true.

becomes.

Here, since the characteristics of the transistors 32 and 33 are the same, it may be set as 83-s4, and the above equation can be approximated as follows.

By substituting equations (21) and (22) into equation (23), the following equation is obtained.

The fact that the temperature T is included in the exponential term of equation (24) representing the output current ■c of the antilogarithmic amplifier 3 means that the output current ■c of the antilogarithmic amplifier 3
This shows that it has not only antilogarithmic transformation characteristics but also extremely large temperature dependence.

Now, in equation (24), the equation (
Substituting 18) gives the following equation, and by eliminating the temperature T in the numerator and denominator, the output current IC of the antilogarithmic amplifier 3 is expressed by the following equation.

However, n=0, 1, 2, 3=”・, O≦a≦1
1g(a)=a(1+G)-G.

As shown in equation (25), the output current I of the antilogarithmic amplifier 3
Since C does not include temperature T, it can be seen that it is stable against temperature changes.

Return to Figure 1 again.

As described above, the current control filter 4 has a cutoff frequency fc that is directly proportional to the input current IC.

That is, when the proportionality constant is set to 5, the cutoff frequency f
c is expressed by the following formula.

When formula (25) is substituted into formula (26) and rearranged, the off frequency fc is expressed by the following formula.

cut The off frequency fc is stable against temperature changes.

In particular, as in equation (24), the temperature T that was in the exponential term has been eliminated, and the temperature stability for the geometrical change in the cutoff frequency fc is perfect.

Equation (27) shows that the cutoff frequency fc is determined by the keyboard information n (indicating which key is being pressed) and the cutoff frequency shift information a (indicating how much the cutoff frequency has been shifted). It shows that

Both n and a are in the exponential term, and an equileft-curved change in n or a appears as a geometric change in the cutoff frequency fc.

(27), 6 to 8. By setting each constant of G so as to have desired characteristics as a timbre control device, a timbre control device whose cutoff frequency fc is completely unaffected by temperature changes can be obtained.

In actual circuit fabrication, the transistors 13 and 14 of the temperature-sensitive voltage generating circuit 1 in FIG. 2 and the transistors 32 and 33 of the antilogarithmic amplifier 3 in FIG. It is necessary to take into account the design, such as arranging them as two, mold-packing them together, or using four transistors on the same IC chip.

Note that 213 in Figure 3 is a sample-and-hold circuit for convenience, but any circuit with proportional input-output characteristics and stable against temperature changes may be used.For example, an integrating circuit may be placed before the sample-and-hold circuit. It may also be a built-in circuit (tone portamento effect circuit).

In the embodiment shown in FIG. 1, a current control filter is used as the filter 4 for controlling the timbre of musical sounds, but the present invention is not limited to this, and the cutoff frequency is set to the level of the input electrical signal. Any electrical signal control filter that changes in direct proportion may be used; for example, a voltage control filter may be used as 4.

However, in this case, a voltage output type antilogarithmic amplifier is used as the antilogarithmic amplifier 3, or a circuit in which a current-voltage converter is provided after the current output type antilogarithmic amplifier of the embodiment shown in FIG. 4 is used. There is a need.

Further, although both the scale senior generation circuit 21 and the cutoff frequency shift voltage generation circuit 22 are used simultaneously in the cutoff frequency control voltage generation circuit 2 shown in FIG. There are no restrictions.

For example, when used as a tone control device for an electronic instrument without a keyboard, the cutoff frequency shift voltage generation circuit 22
You can also use only

In other words, the cutoff frequency control voltage generation circuit 2 is a variable gain amplifier (or multiplier) that receives the temperature sensitive voltage VT as an input.
It can be said that it has the following functions.

Although one three-terminal variable resistor 220 is used in the cut-off frequency shift voltage generation circuit 22 of FIG. 3, there is no limit to the number of these as well. A variable resistor is provided in parallel with the variable resistor 220, and the variable resistor 220 is used for rough adjustment of the cutoff frequency, and the other 3-terminal variable resistor is used for fine adjustment of the cutoff frequency. You can also do it.

Needless to say, at this time, it is necessary to add one input to the adder circuit 23.

In addition, various contents of the cutoff frequency shift voltage generation circuit 22 shown in FIG. 3 can be considered.

For example, the commonly used devices for changing the cutoff frequency using an electrical signal rather than manually are an LFO (low frequency oscillator) to add a grumble, or a wah effect that temporarily shifts the cutoff frequency and then gradually returns to it. Examples include a wah envelope generator to produce a wah sound, and various envelope generators to make the cutoff frequency jump as desired.

Since it is inconvenient that these effects also change with temperature changes, it is necessary to configure the LFO so that the output amplitudes of the various envelope generators change in proportion to the temperature T.

An example for this purpose is shown below.

FIG. 5 shows an embodiment in which a wah envelope generator is used in the cutoff frequency shift voltage generating circuit 22.

Transistor Tri is for capacitor charging, and transistor Tr2 is for emitter follower.

Since the temperature-sensitive voltage vT is applied to the emitter of the transistor Tr1, as shown in FIG. 5, when a pulse voltage more negative than the temperature-sensitive voltage vT is applied to the terminal 50, the output type E
VpS rises from the ground potential to (7) and gradually returns to the ground potential with the time constant CRG.

Therefore, the amplitude of the output type EVPS is T (VBFli of Tr2 is small and can be ignored), and is proportional to the temperature T.

FIG. 6 shows that the cut-off frequency shift voltage generation circuit 22 is
An example using analog waveform generators including FO and various envelope generators will be shown.

51 is an analog waveform generator.

A multiplier 52 outputs a voltage proportional to the product of the output voltage of the analog waveform generator 51 and the temperature-sensitive voltage vT.

Now, when the output amplitude of the analog waveform generator 51 is Va, the amplitude of the output type EVPs of the multiplier 52 is MYTV
It becomes a.

However, M is a multiplication constant that is not related to temperature.

Therefore, the output voltage ■Ps changes in proportion to the temperature.

FIG. 7 shows that the cut-off frequency shift voltage generation circuit 22 is
An embodiment using a digital signal output waveform generator including an FO and various envelope generators will be described.

53 is a waveform generator that outputs a 4-bit digital signal, and generates a binary signal corresponding to the amplitude of the output type EVPS from Q1 to
Output to Q4.

54 is a 4-bit D/A converter using a well-known R-2R ladder resistor network.

541 is a differential amplifier for current-sensor conversion.

81 to S4 are current switches whose switching is controlled by the outputs Q1 to Q4 of the waveform generator 53, respectively.

Temperature-sensitive type E as a reference for the D/A converter 54
Since VT is given, the current flowing through the current switches 81 to S4 is the current flowing through the current switches 5n (n=1 to 4) to the differential amplifier 541 when the output Qn (n=1 to 4) of the waveform generator 53 is rtJ. When Qn is "O", it is connected to the ground side.

Therefore, if Qn represents the number 1.0 corresponding to logic "l" and "O", the output voltage Vps is as follows.

Since the coefficient of vT is a constant that is not related to temperature, the voltage V
PS will change in proportion to temperature T.

In the embodiment of FIG. 7, a 4-bit digital signal is used for convenience of explanation, but it is clear that the embodiment can be realized without any restriction on the number of bits.

The embodiments shown in FIGS. 3, 5, 6, and 7 have been described above as embodiments of the cutoff frequency shift voltage generation circuit 22, but it is not necessary to use each of them independently. However, they can be combined and configured in parallel.

As described above, the present invention solves all at once the difficulty of temperature compensation inherent in the antilogarithmic amplifier for converting the arithmetic level cutoff frequency control room modulus into the corresponding geometric cutoff frequency. Moreover, it is extremely valuable because it can completely compensate for the temperature without any variation without any adjustment, and can significantly improve the temperature stability of the tone (filter cutoff frequency) of electronic musical instruments, especially music synthesizers. It is something.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
A specific circuit configuration diagram of an embodiment of the temperature-sensitive voltage generation circuit 1 shown in the figure,
Figure 3 shows the cut-off frequency control voltage generation circuit 2 in Figure 1.
4 is a specific circuit diagram of the embodiment of the antilogarithmic amplifier 3 of FIG. 1, and FIG. 5 is a diagram of the cut-off frequency shift voltage generation circuit of FIG. Specific circuit configuration diagram of an embodiment using an envelope generator, No. 6
The figure is a circuit configuration diagram of an embodiment in which an analog waveform generator is used in the cutoff frequency shift voltage generation circuit shown in Fig. 3, and Fig. 7 is a circuit configuration diagram of an example in which an analog waveform generator is used in the cutoff frequency shift voltage generation circuit shown in Fig. 3. FIG. 3 is a circuit configuration diagram of an embodiment using a device. DESCRIPTION OF SYMBOLS 1... Temperature-sensitive voltage generation circuit, 2... Cut-off frequency control voltage generation circuit, 3... Anti-logarithm amplifier, 4... Current control filter, 21... Scale voltage generation circuit, 22.
...Cutoff frequency shift voltage generation circuit, 23...
Addition circuit, 211... Voltage-current conversion circuit, 212-
0° forging pressure generation circuit, 51... analog waveform generator,
52... Multiplier, 53... Waveform generator for digital signal output.

Claims (1)

[Scope of Claims] 1. A temperature-sensitive voltage generation circuit that generates a voltage that changes in proportion to temperature, an electric signal control filter whose cutoff frequency changes in direct proportion to the level of a control signal, and the temperature-sensitive voltage generation circuit that generates a voltage that changes in proportion to the temperature. at least one cutoff frequency control voltage generation circuit that receives the output voltage of the circuit as an input and generates a voltage that changes in proportion to temperature and corresponds to the cutoff frequency of the electrical signal control filter; and a semiconductor as an antilog conversion element. an anti-logarithmic amplifier using a PN junction, and the electrical signal control filter is controlled by an electrical signal obtained by anti-logarithmically converting the output voltage of the cut-off frequency control voltage generation circuit with the anti-logarithmic amplifier. A timbre control device for an electronic musical instrument, characterized in that a signal obtained by passing a sound source signal through the electric signal control filter is used as a musical tone signal. 2 As a cut-off frequency control voltage generation circuit, a scale voltage generation circuit that receives the output voltage of the temperature-sensitive voltage generation circuit as an input, changes in proportion to temperature, and generates a scale voltage corresponding to the scale frequency, and the temperature-sensitive voltage A cutoff frequency shift voltage generation circuit that receives the output voltage of the generation circuit as an input and generates a voltage that changes in proportion to temperature and whose level is variable; the output voltage of the scale voltage generation circuit; and the cutoff frequency shift voltage generation circuit. The electronic musical instrument according to claim 1, further comprising: an adder circuit for appropriately adding levels of the output voltage of the adder circuit, and a cut-off frequency control voltage generating circuit whose output is the output voltage of the adder circuit. Control device. 3 As a scale voltage generation circuit, a voltage-current conversion circuit that converts the output voltage of the temperature-sensitive voltage generation circuit into a current proportional to the output voltage, and a voltage-current conversion circuit that receives the output current of the voltage-current conversion circuit as input and corresponds to the scale frequency. and a forging pressure generation circuit that generates an arithmetic voltage, the tone of the electronic musical instrument according to claim 2, which uses a scale voltage generation circuit whose output voltage is the output voltage of the forging pressure generation circuit. Control device. 4 As a voltage-current conversion circuit, an inverting amplifier that inverts and amplifies a DC voltage, a differential amplifier, and a first .
a second resistor, a third resistor, and a field effect transistor; a connection point between the first and second resistors is connected to a non-inverting input of the differential amplifier; one end and the source of the field effect transistor are connected to the inverting input of the differential amplifier, the output of the differential amplifier is connected to the gate of the field effect transistor, and the output of the inverting amplifier is connected to the second resistor. the other end of the first resistor and the other end of the third resistor are connected to the input of the inverting amplifier, and the output voltage of the temperature-sensitive voltage generating circuit is connected to the input of the inverting amplifier. 4. The timbre control device for an electronic musical instrument according to claim 3, which uses an electromotive current conversion circuit configured to input a current and obtain an output current to the drain of the field effect transistor. 5 As a forging pressure generation circuit, both terminals of adjacent key switches of a plurality of key switches having a common bus bar are connected with equal resistance values, and the lowest tone (or highest tone) is connected. It has a keyboard in which the terminals of the corresponding key switches are connected to a fixed potential point, and a voltage follower, and the output current of the voltage-current conversion circuit is connected to the highest (or lowest) tone of the keyboard. Claim No. 1, which uses a forged motor generating circuit configured to lead to a terminal of a key switch corresponding to the key switch, and at the same time convert the impedance of the voltage of the bus bar when the key is turned on by the voltage follower and output it. The timbre control device for an electronic musical instrument according to item 3 or 4. 6. As a cut-off frequency shift voltage generation circuit, a three-terminal variable resistor is provided, and the output voltage of the temperature-sensitive voltage generation circuit and the output voltage of the temperature-sensitive voltage generation circuit are connected to both terminals of the three-terminal variable resistor. Claim 2, which uses a cut-off frequency shift voltage generation circuit configured to apply a voltage inverted by an inverting amplifier and output the voltage appearing at the sliding terminal of the three-terminal variable resistor. - The timbre control device for an electronic musical instrument according to any one of Items 5 to 5. 7. Claims 2 to 7 which use a cutoff frequency shift voltage generation circuit that outputs an electrical signal having an output amplitude proportional to the output voltage of the temperature sensitive voltage generation circuit as the cutoff frequency shift voltage generation circuit. The timbre control device for an electronic musical instrument according to any one of Item 5. 8. A waveform generator that outputs amplitude information of a desired waveform as an electrical signal as a cutoff frequency shift voltage generation circuit;
a multiplication circuit that receives the output signal of the waveform generator and the output voltage of the temperature-sensitive voltage generation circuit as input and outputs a voltage proportional to the product of the levels of these two outputs; The timbre control device for an electronic musical instrument according to claim 7, which uses a cutoff frequency shift voltage generation circuit configured to output. 9 As a temperature-sensitive voltage generation circuit, first and second differential amplifiers, first and second differential amplifiers, and first and second differential amplifiers; a second transistor, a seventh transistor, an eighth transistor; ninth and tenth resistors, the inverting inputs of the first and second differential amplifiers are connected to a constant voltage source via the seventh and eighth resistors, respectively; The non-inverting input of the second differential amplifier, one end of the ninth resistor, and the base of the first transistor are grounded, and the collectors of the first and second transistors are connected to the difference between the first and second transistors. the output of the second differential amplifier is connected to the emitter of the second transistor through a resistor, and the emitter of the second transistor is connected to the emitter of the first transistor. and connecting the base of the second transistor to the other end of the ninth resistor, and connecting the output of the first differential amplifier to the base of the second transistor via the tenth resistor. An electronic musical instrument according to any one of claims 1 to 8, which uses a temperature-sensitive voltage generation circuit configured to output the output voltage of the first differential amplifier. Tone control device. 10 anti-logarithmic amplifier, a third differential amplifier;
a fourth transistor and an eleventh resistor, the non-inverting input of the third differential amplifier and the base of the third transistor are grounded, and the inverting input of the third differential amplifier is grounded; The eleventh resistor is connected to a constant voltage source, the collector of the third transistor is connected to the inverting input of the third differential amplifier, and the output of the third differential amplifier is connected to the resistor. connected to the emitter of the third transistor through
A patent using an anti-logarithmic amplifier configured such that the emitter of the fourth transistor is connected to the emitter of the third transistor, and the base of the fourth transistor is used as a voltage input terminal and the collector as a current output terminal. A tone color control device for an electronic musical instrument according to any one of claims 1 to 9. 11. The timbre of the electronic musical instrument according to any one of claims 1 to 10, which uses a current control filter whose cutoff frequency changes in direct proportion to the input current level as the electric signal control filter. Control device. As a 12m1 transistor and a second transistor,
10. The timbre control device for an electronic musical instrument according to claim 9, which uses a pair of transistors having the same voltage-current characteristics. 13 As the third transistor and the fourth transistor,
11. The timbre control device for an electronic musical instrument according to claim 10, which uses a pair of transistors having the same voltage-current characteristics. 14. The timbre control device for an electronic musical instrument according to claim 1, wherein the temperature-sensitive electromotive generator circuit and the antilogarithmic amplifier are kept in substantially the same temperature equilibrium state.