JP2000134048A - Input circuit of electronic volume ic for car audio - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the whole device small-sized and inexpensive by switching a digital signal input of two or more systems to that of one system with a control signal from the outside in a digital switching circuit and inputting it to one D/A converter to be subjected to analog conversion. SOLUTION: Signals from an MD player 11, a CD player 12 and an external digital device 13 are respectively inputted to a digital switching circuit 15 provided in an inputting part of an electronic volume IC 14. The digital switching circuit 15 selects one of the externally inputted signals from the MD player 11, the CD player 12 or the external digital device 13 and inputs it to a D/A converter 17. After the signal converted into an analog signal by the D/A converter 17 is amplified by an amplifier 18, it is inputted to a volume circuit 19 to be subjected to volume adjustment and is outputted to an external speaker.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an input circuit for an electronic volume IC for car audio.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional car audio electronic volume IC and its input side configuration. FIG.
, 1 is an MD player, and 2 is a CD player. The signal from the MD player 1 is transmitted to the D / A converter 3
, And is input to the electronic volume IC5. The signal from the CD player 2 is also converted into an analog signal by another D / A converter 4 and the electronic volume IC
5 is input. In the electronic volume IC 5, analog signals from the D / A converters 3 and 4 are added and amplified by the amplifier 6, and then input to the volume circuit 7, where the volume is adjusted. Output to the speaker.

[0003]

However, in the above-mentioned conventional electronic volume IC 5 for car audio, the MD
Since the digital signals from the player 1 and the CD player 2 were converted into analog signals by the external D / A converters 3 and 4 and then input to the electronic volume IC 5, respectively, the D / A converter was connected to the electronic volume IC. However, there is a problem that the number of external digital devices required is increased.

The present invention solves such a conventional problem, and reduces the number of external D / A converters.
It is an object of the present invention to provide an input circuit of a car audio electronic volume IC for realizing miniaturization and low cost of the whole apparatus.

[0005]

According to the present invention, in order to achieve the above object, two or more systems of digital signal inputs are switched to one system by a digital switching circuit by an external control signal, and are switched to one system. The signal is input to a D / A converter and is converted into an analog signal, so that the entire apparatus can be reduced in size and cost can be reduced.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a digital switching circuit having two or more digital input terminals for inputting signals from an external digital device including a plurality of digital sound reproducing devices. An input circuit for an electronic volume IC for car audio, wherein the digital switching circuit is switched to one system by an external control signal, without using an external D / A converter. Signals from players and other external digital devices are directly sent to electronic volume ICs
It has the effect of being able to input to

According to a second aspect of the present invention, the switched digital signal is converted into an analog signal by a built-in D / A converter and then output to a volume circuit. It is an input circuit of the electronic volume IC for car audio described above, and switches signals from two or more external digital devices to one system, and
Since the signal is input to the A / A converter, only one D / A converter is required, which has an effect that the entire device can be reduced in size and cost can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment) FIG. 1 shows a configuration of an electronic volume IC for car audio and an input side thereof according to an embodiment of the present invention. In FIG. 1, reference numeral 11 denotes an MD player,
Reference numeral 12 denotes a CD player, and reference numeral 13 denotes other external digital devices. Signals from the MD player 11, the CD player 12, and the external digital device 13 are supplied to a digital switching circuit 1 provided at the input section of the electronic volume IC 14, respectively.
5 is input. In the digital switching circuit 15, one of the externally input signals from the MD player 11, the CD player 12 or the external digital device 13 is selected by a control signal from the external microcomputer 16 and D / D
The signal is input to the A converter 17. D / A converter 17
The signal converted into an analog signal by the amplifier is amplified by an amplifier 18, input to a volume circuit 19, adjusted in volume, and output to an external speaker.

As described above, in the present embodiment, the MD player 11, the CD player 12, or the external digital device 1
3 is switched by the digital switching circuit 15 by a control signal from the external microcomputer 16 and is input to the D / A converter 17, so that the D / A
Only one converter is required, and the size and cost of the entire device can be reduced.

[0010]

According to the present invention, as is apparent from the above embodiment, a plurality of digital signals from an MD player, a CD player, and other external digital devices are directly transmitted without using an external D / A converter. While input to the electronic volume IC, one of them is switched by an external control signal and converted into an analog signal by one D / A converter and output to the volume circuit. Cost can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electronic volume IC for car audio and an input side thereof according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an electronic volume IC for car audio and an input side thereof in a conventional example.

[Description of Signs] 11 MD player 12 CD player 13 External digital device 14 Electronic volume IC 15 Digital switching circuit 16 Microcomputer 17 D / A converter 18 Amplifier 19 Volume circuit

Claims (2)

[Claims] A digital switching circuit having two or more digital input terminals for inputting signals from an external digital device including a plurality of digital sound reproducing devices, wherein the digital switching circuit is controlled by an external control signal. An input circuit for an electronic volume IC for car audio, wherein the input circuit is switched to one system. 2. After the switched digital signal is converted into an analog signal by a built-in D / A converter,
3. The input circuit of an electronic volume IC for car audio according to claim 2, wherein the input is output to a volume circuit.