JPS6348977Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a level adjustment circuit, and particularly to a level adjustment circuit suitable for use as a volume adjustment circuit in audio equipment.

[Prior Art] In audio equipment, for example, a receiver capable of receiving traffic information, when traffic information is being broadcast, it is necessary to switch this to inform the listener even if another program source is being output. An information signal is output. In such a case, the information signal must be output even when the volume in the volume adjustment circuit of the receiver is at zero.

FIG. 3 shows a circuit diagram of a conventional example of a level adjustment circuit as a volume adjustment circuit. In the figure, the signal supply points of the first signal (referred to as a normal signal) other than the information signal connected to the input terminals IN ₁ and IN ₂ , respectively, and the information signal as the second signal are connected to the input terminals IN 1 and IN 2, respectively, by switches S ₁ and S ₂ . Connected to one end of variable resistor VR. A resistor _R1 is connected between the other end of the variable resistor VR and the reference potential, and a switch _S3 which is inverted and interlocked with the switch _S2 is connected in parallel to the resistor _R1 .
A first or second signal output is derived from the sliding terminal of the variable resistor VR.

In this configuration, when the normal signal is input by closing the switch _S1 , the switch _S2 is opened and the switch _S3 is closed to short-circuit the resistor _R3 , and the output level of the normal signal is as shown in FIG. As shown in a, the rotation angle of the variable resistance VR, that is, the variable resistance
Proportional to VR resistance value.

On the other hand, when an information signal is input by closing switch _S2 (opening switch _S1 ), switch _S3 is opened, and the output level of the information signal varies from the predetermined level Vr at the minimum volume rotation angle to the volume level as shown in Figure 4b. It changes in proportion to the rotation angle. Here, the given level
Vr is set by resistor R ₁ to a value that allows the information signal to be heard sufficiently when the information signal is input at the minimum volume rotation angle, and is also set at the volume rotation angle commonly used when inputting normal signals. This approximately corresponds to the output level at the position (near the X position in FIG. 4).

[Problems to be solved by the invention] In such a conventional level adjustment circuit, for example, when the volume rotation angle is near the X position in FIG. 2, when an information signal is input, the output level changes by Vu. do. Therefore, even if the volume rotation angle is set to a position corresponding to a level that is easy to listen to, the output level suddenly increases due to the input of information signals, causing discomfort to the listener. .

[Means for Solving the Problems] The present invention has been made in order to solve the above-mentioned problems of the conventional art. a variable resistance element to which two signal supply points are selectively connected and derive the first or second signal output from the sliding end; a voltage dividing circuit having a point connected to the other end of the variable resistance element; and a third switching means connected between the voltage dividing point of the voltage dividing circuit and a reference potential point and interlocking with the second switching means. It is equipped with the following.

[Operation] In the above means, when the first switch means is closed and the second and third switch means are opened and closed, respectively, the first signal output is equal to the resistance value of the variable resistance element. It changes accordingly. Also,
When the first switch means is open and the second and third switch means are closed and opened, respectively, the second signal output is approximately the same from the minimum resistance value of the variable resistance element to the predetermined resistance value. The output level changes depending on the resistance value of the variable resistance element when the resistance value exceeds a predetermined resistance value.

[Embodiments of the invention] Examples of the invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of a level adjustment circuit according to the present invention, in which the same parts as in FIG. 3 are designated by the same symbols. In the figure, between the connection point of resistors R ₁ and R ₂ , which is the voltage dividing point of the voltage dividing circuit, and the reference potential, there is a switch S ₄ which is inverting and interlocking with switch S ₂ .
are connected, and the other configuration is the same as that in FIG. Further, the resistance value of the resistor _R1 is selected to be sufficiently smaller than the resistance value of the variable resistor VR.

In such a configuration, when the normal signal (first signal) is input by closing the switch S ₁ , the switch S ₂
is opened, and switch _S4 that is linked to this is closed. Therefore, the information signal (second signal) supplied to the input terminal _IN2 is grounded via the resistor _R2 and the switch _S4 . Furthermore, since the resistance value of the resistor _R1 is selected to be sufficiently small, the output level of the normal signal is proportional to the volume rotation angle of the variable resistor VR, that is, the resistance value of the variable resistor VR, as shown in FIG. 2a. On the other hand, when the information signal (second signal) is input by closing switch _S2 , _the switch
Since _S4 is open, the signal supply point of the information signal is connected to one end of the variable resistor VR, and is also connected to the connection point between the variable resistor VR and the resistor _R1 via the resistor _R2 . The output signal based on the input signal applied to one end of the variable resistor VR is proportional to the volume rotation angle of the variable resistor VR, as shown in FIG. 2a, as in the case described above. Furthermore, the output signal based on the input signal applied to the other end of the variable resistor VR via the resistor _R2 is the difference between _R1 and _R2 when the volume rotation angle of the variable resistor VR is at its minimum, as shown in Figure 2b. It decreases from a predetermined level Vr determined by the partial pressure ratio in inverse proportion to the volume rotation angle.
The input signals applied to both ends of this variable resistor VR are in phase, so the output signal is as shown in Fig. 2c.
As shown in the figure, it becomes the root mean square value of each of the above outputs, and when an information signal is input, the variable resistor VR's minimum resistance value to a predetermined resistance value, that is, the volume rotation angle is changed from the minimum to the commonly used position (the first position) when inputting a normal signal. The output level is approximately constant up to the vicinity of the X position in FIG. 2), and the output level is proportional to the volume rotation angle above a predetermined resistance value.

Therefore, even if an information signal is input in a volume rotation angle state near the X position, the information signal can be sufficiently heard because the output level is near the predetermined level Vr.

[Effects of the invention] As detailed above, according to the level adjustment circuit according to the invention, even if the resistance value of the variable resistor is the minimum, it is possible to output the second signal at the stop level, and the variable resistor is Even if the second signal is applied when the resistance value is at a commonly used resistance value, the output signal can be output at a level close to the predetermined level, so that it does not cause discomfort to the listener. Furthermore, the output characteristics can be set arbitrarily depending on the purpose of use.

Therefore, such a level adjustment circuit is suitable for use as a volume adjustment circuit in a weather information receiver, a traffic information receiver, etc. that needs to warn or alert listeners.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of FIG. 1, FIG. 3 is a circuit diagram of a conventional level adjustment circuit, and FIG. 4 is a circuit diagram of a conventional level adjustment circuit. FIG. VR……variable resistance, S ₁ to S ₄ ……switch.

Claims (1)

[Claims for Utility Model Registration] (1) First and second signal supply points are selectively connected to one end via first and second switch means, and the first or second signal supply points are selectively connected to one end via first and second switch means. a variable resistance element that derives a signal output; a voltage dividing circuit whose both ends are connected to a second signal supply point and a reference potential point and whose voltage dividing point is connected to the other end of the variable resistance element; and the voltage dividing circuit. third switch means connected between the voltage dividing point and the reference potential point and interlocked with the second switch means, closing the first switch means and closing the second and third switch means; The first signal output changes in accordance with the resistance value of the variable resistance element when the means are open and closed, respectively, and the first signal output is opened and the second and third switch means are respectively turned on. The second signal output changes at substantially the same output level from the minimum resistance value of the variable resistance element to a predetermined resistance value in the closed and open states,
A level adjustment circuit characterized in that the level adjustment circuit is configured to change in accordance with the resistance value of the variable resistance element above a predetermined resistance value. (2) The voltage dividing circuit includes a first resistor connected between the other end of the variable resistance element and the reference potential point, one end connected to the other end of the variable resistance element, and the other end connected to the first resistor. A second signal connected to the second signal supply point
The level adjustment circuit according to claim 1, characterized in that the level adjustment circuit comprises a resistor.