JPH0625054Y2 - Audio equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In an audio device using an electronic volume, when the mute circuit is operated, the electronic volume is simultaneously set to the maximum attenuation amount to realize a sound leakage prevention function equivalent to that of a two-stage mute circuit. .

[Industrial application field]

The present invention relates to an audio device using an electronic volume.

[Conventional technology]

As shown in FIG. 3, the multi-source audio device can be configured by sharing the audio control circuit 4, the electronic volume 5, the mute circuit 6, the amplifier circuit 7, the mute control circuit 8 and the speaker 9. In this example, the sources are a radio receiver and a cassette deck, and 1 and 2 are linear circuits for each.

The output of the linear circuit 1 is directly input to the audio control circuit 4, while the output of the linear circuit 2 is input to the audio control circuit 4 via the mute circuit 3. This difference is due to the addition of a mode in which the head is brought into sliding contact with the tape in the fast-forwarding state, such as cueing or blank skipping, as a function of the cassette deck in recent years, and high frequency noise is generated in this operation.

The mute control circuit 8 operates the two mute circuits 3 and 6 at the same time so as to effectively reduce the sound leakage generated from the linear circuit 2 of the cassette.

[Problems to be solved by the device]

However, the use of two stages of mute circuits as shown in FIG. 3 complicates the device structure and increases the cost.

The present invention utilizes the electronic volume as a substitute for the mute circuit so that one mute circuit produces the same sound leakage prevention effect as the two-stage mute circuit.

[Means for Solving the Problems]

The present invention has an electronic volume (5) and a mute circuit (6)
In the audio device using the serially connected circuit, when the mute circuit (6) is operated, it is controlled to maximize the attenuation amount of the electronic volume (5) at the same time.

[Action]

If the attenuation of the electronic volume is maximized, the same effect as the mute circuit can be expected. Therefore, using only one mute circuit in the audio device using the electronic volume provides the same sound leakage prevention effect as the two-stage mute circuit. Can play.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention, in which the mute circuit 3 of FIG. 3 is omitted and a mute control circuit 8 is used instead.
It controls the mute circuit 6 and the electronic volume 5.

As shown in FIG. 2, the mute circuit 6 is composed of resistors R _{1 to} R ₄ and a transistor Q ₁ connected between the coupling capacitors C ₁ and C ₂ , and has H (high) and L (low) 2
When the value mute control signal becomes H level, the transistor Q ₁ is turned on and the signal line is grounded by the on resistance of the transistor.

The electronic volume 5 is a circuit that receives a volume control signal that linearly changes between H and L at the volume control terminal 51 to linearly change the attenuation amount. In this example, the resistors R ₅ and R ₆ and the transistor Q _{2 are used.} Is added, and when the above-mentioned mute control signal from the mute control circuit 8 becomes H, the transistor Q ₂ is turned on and the volume control terminal 51 is forcibly grounded.

This electronic volume 5 uses an electronic volume having a characteristic of maximizing the amount of attenuation when the control terminal 51 goes to L level, and when the mute circuit 6 operates, the amount of attenuation is maximized at the same time and the noise on the signal line is increased. To the maximum. Therefore, by cooperating with the mute circuit 6, a sound leakage prevention effect equivalent to that of the two-stage mute circuit can be expected. In this example, an electronic volume with a larger amount of attenuation is used as the control voltage to the control terminal is smaller, but other types of electronic volume can be handled with a simple circuit change. It is also possible to control both the control signal of the electronic volume and the control signal of the electronic volume.

[Effect of device]

As described above, according to the present invention, since the electronic volume for volume control is also used in place of the mute circuit, the sound leakage prevention effect equivalent to that of the two-stage mute circuit can be expected by providing only one mute circuit. .

[Brief description of drawings]

 FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram of a main part of FIG. 1, and FIG. 3 is a block diagram of a conventional audio device.

Claims (1)

[Scope of utility model registration request] 1. In an audio device using an electronic volume (5) and a mute circuit (6) in series, when the mute circuit (6) is operated, the attenuation amount of the electronic volume (5) is maximized at the same time. An audio device characterized by being controlled as follows.