JPS6223200Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a stereo playback device in which the so-called L
One set of desired modes such as reverse (R is output to L and L is output to R), mono (L + R), stereo, wide (reverse phase mixing) from two left and right signals called channel and R channel. The present invention relates to a continuously variable mode control circuit that allows continuous selection only by adjusting variable resistors linked together.

Conventional mode control circuits include, for example, a switch type shown in FIG. 1 and a continuous type shown in FIG. 2, but both have various drawbacks. In other words, in the case of the switch switching method shown in Figure 1, there is no problem in stereo or mono mode, but when the switch is switched to wide, reverse phase mixing (L _IN - mR _IN ) and (R _IN - mL _IN ) may cause problems. However, in the wide mode obtained, it is difficult to finely adjust the mixing ratio.

On the other hand, in the case of the continuous type shown in Figure 2, fine adjustment in wide mode is possible, but a capacitor C is connected between the emitter of the transistor Q _L , which uses the L output as a positive phase output, and the collector of the transistor Q _R , which uses the L output as a negative phase output. ₁ , variable resistor connected in series with resistor R ₁
From VR ₁ , and similarly, the R output is connected to the transistor Q _R
Since the variable resistors VR 2 are connected in series with the capacitor C ₂ and the resistor R ₂ between the emitter of the transistor Q _L and the collector of the transistor Q _L , the variable resistors VR ₁ and VR ₂ are interlocked in the a direction in Fig. Even in the fully turned state (stereo mode), the output impedance at the emitter of each transistor causes the signal of the other party (R when viewed from L, L when viewed from R) to appear in the output, resulting in incomplete stereo. Also, as is clear from the circuit configuration, variable resistors VR ₁ and VR ₂ are each L
Since the voltage between _IN to -R _IN and R _IN to -L _IN is divided and output, only stereo, wide, and reverse modes are available, and a mono output cannot be obtained from a stereo input. Furthermore, for mono inputs where the left and right signals are the same (L _IN = R _IN ), the signals will mix half and half with the same signal of opposite phase near the center of variable resistors VR ₁ and VR ₂ and become zero. The problem is that the output is inconsistent and there is no compatibility with mono inputs. In addition to the above drawbacks, reverse mode, in which variable resistors VR ₁ and VR ₂ are fully turned in direction b, has various other drawbacks, such as poor separation of left and right signals and the phase being reversed compared to stereo mode. Ta.

The present invention has been proposed in view of the above points, and aims to provide a simple and useful variable mode control circuit that is continuously type capable of fine adjustment and does not have the above-mentioned drawbacks. be.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to drawings showing examples.

First, FIG. 3 shows an embodiment of the continuously variable mode control circuit of the present invention. The input signal L _IN is connected to the intermediate terminal of the variable resistor 5 via the input terminal 1 and input to the first mixer 9, and is output via the output terminal 3.
Similarly, the input signal R _IN is connected via the input terminal 2 to the intermediate terminal of the variable resistor 6 that interlocks with the variable resistor 5, and is also input to the second mixer 10, and is input to the second mixer 10 via the output terminal 4. Output. Further, the terminals at both ends of the variable resistors 5 and 6 are connected in parallel to form a so-called double variable resistor, and if one is designated as point A and the other as point B, then point A is connected to the first terminal consisting of an operational amplifier or the like. The point B is connected to the inverting input terminal of the amplifier 7 and the non-inverting input terminal of the second amplifier 8. connected to the input terminal. Furthermore, the outputs of the first and second amplifiers 7 and 8 are input to the mixers 9 and 10, respectively, and are connected to be added to the input signals L _IN and R _IN, respectively.

Next, its operation will be explained. However, in this embodiment, the variable resistors 5 and 6 are interlocked,
When the intermediate terminal of variable resistor 5 moves toward A as shown by the arrow, the intermediate terminal of variable resistor 6 moves toward B.

Therefore, if the total resistance value of variable resistors 5 and 6 is K, and the resistance value from point B to the intermediate terminal of variable resistor 5 is x, then the resistance value of variable resistor 5 is (K-x)
and x (K), and the resistance value of the variable resistor 6 is also x and (K-x), and the double variable resistor has a bridge relationship between these resistance sides. Also, point A, B
The voltage at the point e _A , e _B , each signal name (L _IN , L _OUT ...
..., etc.) represents the voltage value of the signal, and assuming that the apparent amplification degree of the amplifiers 7 and 8 is 1 and the input impedance is sufficiently high, the following relationship holds true.

L _IN -e _A /K-x≒e _A -R _IN /x=i ₁ - L _IN -e _B /x≒e _B -R _IN /K-x=i ₂ - The formula is the intermediate terminal of variable resistor 5. →Represents the relationship between the current flowing from point A → to the intermediate terminal of variable resistor 6,
The equation similarly expresses the relationship between the current flowing through point B. Further, the following relationship exists between the input and output voltages of the mixers 9 and 10.

L _OUT = L _IN −e _A +e _B − R _OUT = R _IN +e _A −e _B − By eliminating e _A and e _B from the above equation, the following relationship is obtained.

L _OUT =2(1-x/K)・L _IN +(2x/K-1)・R _IN - R _OUT =2(1-x/K)・R _IN +(2x/K-1)・L _IN - By the way, the resistance value x can be continuously changed from O to the total resistance value K by operating the variable resistors 5 and 6, and the characteristic values and mono inputs operate as follows.

(1) When x=0, by substituting x=0 into the equation, L _OUT = 2L _IN −R _IN R _OUT = 2R _IN −L _IN , resulting in reverse phase mixing and wide mode. Note that from x=0 to x=K/2, which will be described next, the mixing ratio in wide can be continuously varied and fine adjustment can be made.

(2) When x=K/2, L _OUT = L _IN R _OUT = P _IN , resulting in complete stereo mode.

(3) When x=3K/4, L _OUT = 1/2L _IN + 1/2R _IN R _OUT = 1/2R _IN + 1/2L _IN , resulting in a mono mode in which left and right signals are mixed in half.

(4) When x=K, L _OUT = R _IN and R _OUT = L _IN , resulting in reverse mode where the left and right signals are swapped.

(5) In the case of mono input L _IN = R _IN , L _OUT = L _IN = R _IN R _OUT = R _IN = L _IN , which results in a complete mono output regardless of the value of x, that is, the adjustment position of variable resistors 5 and 6. Become.

Figure 4 explains the above operation, and shows the values of 2(1-x/K)・L _IN , (2x/K)・R _IN , and The value of L _OUT , which is the sum of these values, is shown. In the figure, for convenience of explanation, |L _IN |=|R _IN |=1
Although only the case of L _OUT is shown, the same applies to R _OUT . As is clear from this figure, when x = 0, wide output, when x = K/2, stereo output, and when x = 3K/4, x = K, mono, Reverse output is obtained and L _IN
=L in all modes in case of R _IN mono input.
As shown by _OUT = 1, the output is constant, and it is compatible with not only stereo input but also mono input for accurate reproduction.

Also, in the above explanation, the apparent amplification degree of the amplifiers 7 and 8 is assumed to be 1, but if the amplification degree is arbitrary m and n, the following expression may be applied instead of the above expression. .

L _OUT =L _IN -me _A +me _B - R _OUT =R _IN +ne _A -ne _B - Next, FIG. 5 shows an example of a circuit in which the embodiment of FIG. 3 is realized using specific circuit elements. In terms of the structure, the amplifier 7 and mixer 9, and the amplifier 8 and mixer 10 in the embodiment shown in FIG. The difference from Figure 3 is the insertion. In addition,
Since the operation is a mixer and amplifier integrated, the output L _OU
The only difference between _T and R _OUT is that the inputs L _IN and R _IN are inverted in phase and output, and there is no other difference, so a detailed explanation thereof will be omitted to avoid duplication.

As described above, according to the present invention, a double variable resistor consisting of a first variable resistor and a second variable resistor is used, and the voltage at both ends thereof is mixed with the input signal via an amplifier. There is an advantage that the wide, stereo, mono, and reverse modes can be switched and finely adjusted continuously and easily by only a single operation of the two variable resistors.

In addition, as described above, the two variable resistors constitute a bridge circuit in which the resistance values at opposing positions are equal, such as x, x, (K-x), and (K-x), respectively, and x = K /2 has the advantage that the bridge is balanced and independent of the input impedance of the subsequent amplifier, resulting in a perfect stereo mode.

In addition, as mentioned above, for mono input, 2
A constant output is always obtained regardless of the value of the variable resistor, and it also has excellent compatibility between stereo and mono inputs.

In addition, in the present invention, each output signal L _OUT and R _OUT is expressed by a linear expression of the resistance value x, so the output signal changes almost smoothly as the resistance value changes, and fine adjustment of each desired mode is possible. It has the advantage of being extremely easy to perform. Furthermore, it is also possible to use a plurality of the present invention to deal with multi-channels, and in this case also the same effects as described above can be obtained.

[Brief explanation of the drawing]

1 and 2 are conventional mode control circuits, FIG. 3 is an embodiment of the continuously variable mode control circuit according to the present invention, FIG. 4 is an explanatory diagram of the operation of the embodiment of FIG. 3, and FIG. The figure shows a specific circuit example. 1, 2, 3, 4... terminal, 5, 6... variable resistor, 7, 8... amplifier, 9, 10... mixer.

Claims (1)

[Scope of utility model registration request] A double variable resistor consisting of a first and a second variable resistor having both ends connected in parallel, and a first variable resistor having differential input terminals connected to both ends of the first and second variable resistors, respectively.
and a second amplifier, the first input signal being coupled to the intermediate terminal of the first variable resistor and the input terminal of the first mixer; The amplifier is connected to the intermediate terminal of the second variable resistor and the input terminal of the second mixer, and the output terminals of the first and second amplifiers are connected to the first and second mixer, respectively. . A continuously variable mode control circuit, characterized in that it is configured to obtain a desired mode output by operating the two variable resistors.