JPH0810879Y2 - Signal switching circuit for audio equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a signal switching circuit for an audio device including a preamplifier and a main amplifier.

(B) Conventional technology Conventionally, as a signal switching circuit for an audio device, for example, as shown in FIG.
A selector switch 33a, 33b, 33c, 33d for switching the input of the preamplifier 31 is provided while connecting the 32, and is provided in the preamplifier 31 based on ON / OFF of these selector switches 33a, 33b, 33c, 33d. Microcomputer
There has been provided a switching circuit for an audio device in which 33 controls a switching circuit 34 composed of an analog switch to switch to any one of the input circuits 35a, 35b, 35c, 35d.

(C) Problems to be solved by the device However, in the above-mentioned conventional device, the digital signal is input to the input circuit 35a of the preamplifier, and the D / A converter 36
Is converted into an analog signal by the switching circuit 34 and is then supplied to the front amplifier 37 provided in the main amplifier 32. In the preamplifier, the signal is passed through the source signal switching and the analog signal correction circuit such as surround. Since the path is complicated and the gain is higher than that of the main amplifier, noise radiated from the digital signal from the D / A converter 36 peripheral in the digital circuit or noise sneak from the power supply line is generated in the switching circuit 34. , The surround circuit 10 and other analog circuits can be adversely affected and adversely affect the analog signal, resulting in poor sound quality. Consider the layout of the D / A converter 36, provide a shield, or provide a dedicated power supply. Was needed.

This invention was made in view of the above points, and its purpose is to eliminate the adverse effect on the analog circuit from around the D / A converter, so that the signal path is simple and the gain is small. When the amplifier is equipped with a D / A converter and the analog signal is corrected directly or
A preamplifier is provided with a switching circuit for sending an analog signal of an output signal of a D / A converter, and it is to provide a signal switching circuit of an audio device in which a switching circuit of one amplifier can be controlled by a switch of one amplifier. .

(D) Means for Solving the Problem A signal switching circuit of an audio device according to the present invention is a signal switching circuit of an audio device including a preamplifier and a main amplifier, and the preamplifier is an analog input terminal and a digital input. A first switch for selecting an analog signal applied to the terminal and an analog input terminal or an analog input terminal, and a first switch that operates based on whether the first switch is on or off. A switching circuit, a first microcomputer that controls the first switching circuit, and an output terminal that outputs a signal from the first switching circuit are provided, and the main amplifier is a D / A converter and a D / A converter. A digital input terminal for adding a digital signal, an analog input terminal connected to an output terminal for outputting a signal from the first switching circuit, and an output of the D / A converter. Based on a digital output terminal connected to the digital input terminal by force, a second switch for selecting either the output of the D / A converter or the analog input terminal, and on / off of the second switch And a second microcomputer for controlling the second switching circuit are provided, and the first microcomputer and the second microcomputer are provided with the second switch by the first switch. A bus line for transmitting a control signal for controlling the switching circuit or controlling the first switching circuit with the second switch is provided.

(E) Function According to this invention, the digital input terminal and the D / A converter are provided in the main amplifier in order to reproduce the high-quality music signal that has passed through the D / A converter.
The preamplifier and the main amplifier are provided with switches for switching respective input signals, and the switch of one amplifier can be controlled by the switch of the other amplifier, so that a high quality music signal can be reproduced.

Furthermore, since the switch of one amplifier controls the switching circuit of the other amplifier, operability can be improved.

(F) Embodiment An embodiment of a switching circuit of an audio device according to the present invention is a block diagram of FIG. 1 and main parts of programs of the first and second microcomputers shown in FIGS. 2 (A) and 2 (B). It will be described based on the flowchart of FIG.

In FIG. 1, 1 is a preamplifier and 2 is a main amplifier.
3, 4 and 5 are input terminals for adding an analog input signal (not shown) to the preamplifier 1, 6 is an input terminal for adding a digital analog input signal to the preamplifier 7,
Is a first switching circuit composed of analog switches for switching the input signals applied to the input terminals 3, 4, 5, 6, 8 is a first microcomputer for controlling the first switching circuit 7, and 8a is A central processing unit (hereinafter referred to as CPU) of the microcomputer 8, 8b is a ROM, 8c is a RAM for storing calculation results of the CPU 8a, 8d is an input / output port, 9a, 9b, 9c, 9d.
Is a first switch for selecting and instructing an input signal applied to the input terminals 3, 4, 5 and 6, and 10 is a rear signal (not shown) obtained from the input signal passed through the first switching circuit 7. Surround circuit, 11 is an output terminal for guiding the output of the surround circuit 10 to the main amplifier 2, and 12 is a preamplifier 1.
Output terminal, 13 is a terminal for connecting the bidirectional data bus DBUS, 14 is a terminal for connecting the bidirectional control bus CBUS, 15 is an input terminal for adding a digital input signal to the main amplifier 2, and 16 is D / A converter in main amplifier 2, 1
7 is an input terminal for adding an analog signal output from the preamplifier 1 to the main amplifier 2, 18 is a front amplifier provided in the main amplifier 2, 19 is an input terminal 15 or an input terminal
A second switching circuit composed of a switch or the like for selecting any one of the input signals applied to 17, 20 is a second microcomputer for controlling the second switching circuit 19, 20
a is the central processing unit of this microcomputer 20 (hereinafter C
PU), 20b is a ROM, 20c is a RAM for storing the calculation results of the CPU 20a, 20d is an input / output port, and 21 is a second input instruction for selecting a digital input signal applied to the input terminal 15.
Switch, 22 is a second switch for selecting and instructing an analog input signal applied to the input terminal 17, 23 is a rear amplifier, 24 is an input terminal of the rear amplifier 23, 25 is an output terminal of the D / A converter 16, and 27 Is the output terminal of the front amplifier 18,
28 is an output terminal of the rear amplifier 23, 29 is a bidirectional data bus
DBUS connection terminal, 30 is a bidirectional control bus CBUS connection terminal.

Next, the configuration of the signal switching circuit of this audio device will be described in detail.

The input terminals 3, 4, 5 and 6 of the preamplifier 1 are the first switching circuit 7
The output of the first switching circuit 7 is connected to the output terminal 12 and the input of the surround circuit 10, and the output of the surround circuit 10 is connected to the output terminal 11.

The first switch 9a, 9b, 9c, 9d is connected to the input / output port 8d of the first microcomputer 8, and the input / output port 8d and the first switching circuit 7 are connected. The port 8d is connected to the terminals 13 and 14.

The input terminal 15 of the main amplifier 2 is connected to the input of the D / A converter 16, and the output of the D / A converter 16 is connected to one terminal 19d of the switch, which is the second switching circuit 19, and also the output terminal. 25, the input terminal 17 is connected to the other terminal 19a of the switch which is the second switching circuit 19, the common terminal 19c of this switch is connected to the input of the front amplifier 18, and The output of the amplifier 18 is connected to the output terminal 27 so as to be connected to a front speaker (not shown).

The second switching circuit 19 is connected to the input / output port 20d of the second microcomputer 20, and the input / output port 20d is connected to the second switches 21 and 22 and the terminal 29 for connecting the bidirectional data bus DBUS. And terminal 30 for bidirectional control bus CBUS connection
Is connected.

The input terminal 24 is connected to the input of the rear amplifier 23, and the output of the rear amplifier 23 is connected to the output terminal 28 so as to drive a rear speaker (not shown).

Further, the output terminals 11, 12, 25 and the input terminals 24, 17, 5 are connected respectively, and the terminals 13, 14 and the terminals 29, 30 are respectively connected so that the main amplifier 1 and the preamplifier 2 are connected to each other. Wired to operate as one audio device.

The analog signals applied to the input terminals 3, 4, 5 of the preamplifier 1 are fed to the first switching circuit 7, the output terminal 12 and the input terminal 17, the second switching circuit 19, and the front amplifier 18 of the main amplifier 2. After that, the signal for the rear is led to the output terminal 28 via the surround circuit 10, the output terminal 11, the input terminal 24, and the rear amplifier 23.

The digital input signal applied to the input terminal 15 of the main amplifier 2 is amplified by the front amplifier 18 via the D / A converter 16 and the second switching circuit 19, and is led to the output terminal 27.

Next, the operation of the signal switching circuit of this audio equipment will be described based on the flowchart shown in FIG.

This flow chart shows the flow chart of the program of the first and second microcomputers 8 and 20, and in the figure, "switch" means the first switch when viewed as the flow chart of the first microcomputer 8, When viewed as a flow chart of the second microcomputer 20, it refers to the second switch, and the "switching circuit" means the first switching circuit 7 when viewed as a flow chart of the first microcomputer 8.
When viewed as a flow chart of the second microcomputer 20, the second switching circuit 19 is referred to.

The input / output mode of each input / output port 8d, 20d of the microcomputer of the preamplifier 1 and the main amplifier 2 is instructed to be the normal output mode, and the data output request flag SERF is also cleared. Since neither the 1st or 2nd switch is pushed, the route of the figure
A closed loop of R1, R2, and R6 is formed, and the first microcomputer 8 and the second microcomputer 20 have the first or second switch pressed or receive data from the other microcomputer. Waiting for

In this state, if the first switch 9a for selecting the input signal connected to the input terminal 3 of the preamplifier 1 is pressed, it is determined that the first switch 9a is pressed (step S1), Then, whether the first switch 9a that has been pressed is a switch that selects an analog input circuit,
It is determined whether the switch is a switch for selecting an input circuit for digital (step S2).

Since the first switch 9a is a switch for selecting an analog input circuit, necessary switch data is set in the memory MSEL of the RAM 8c (step S3).

Data for controlling the first switching circuit 7 is created based on the switch data of the memory MSEL (step S
5) The first switching circuit 7 is operated (step S6).

Subsequently, the data in the memory MSEL is converted into serial data for transfer, and this serial data is stored in the output buffer SSEL for transfer (step S7). Next, the output request flag SERF is set to 1 according to the transfer procedure of this microcomputer (step S8). If the output request flag SERF is not set to 1, transfer is not possible, so step
The processing is transferred to S13 (route R2), but the output request flag SER
Since F is set to 1, it is determined whether or not the data bus DBUS for serial data transfer is free (step S10). If the data bus DBUS is not available, data cannot be transferred, so the process moves to step S13 (route R3).
If the data bus DBUS is empty, the output request flag SERF is returned to O (step S11), and the data of the output buffer SSEL is output from the input / output port 8a. At this time, the start bit added to the beginning of the data bit is set to “H” level for 10 ms, and then the serial data is transferred (step S1
2). When the transfer is completed, the input / output port 8d returns to the output mode.

Then, it is checked whether the input / output port 8d is in the input mode or the output mode (step S13). Since the input / output port 8d is in the output mode, the route R6 is passed and the step is performed again.
It returns to S1 and waits for the first switches 9a, 9b, 9c, 9d to be pressed.

Now, the second microcomputer 20 of the main amplifier 2 on the data receiving side waits while checking whether the second switch 21, 22 or serial data is received in the closed loop of the routes R1, R2, R6. But the first
When a signal indicating that the second microcomputer 20 can receive the serial data transfer request of the second microcomputer 20 is sent, the input / output mode of the input / output port 20d of the second microcomputer 20 becomes the input mode. Therefore, in step S13, the route R5 is selected and the start bit for signaling the data transfer is input to the input / output port 20d (step S14).

Next, it is checked whether the start bit is at the “H” level for 10 ms (step S15). If this is not the case, it is not a correct signal and the route R8 returns to step S1 again. If the start bit is at "H" level for 10 ms, the serial data is input to the reception buffer of the second microcomputer 20 (step S16). The received serial data is analyzed (step S17), and what kind of switch data this serial data is is determined. If the switch data transferred from the first microcomputer 8 of the preamplifier 1 is the data for selecting the digital input terminal 15, then the second
The digital switch data is stored in the memory MSEL of the RAM 20c of the microcomputer 20 (step S2
0), since the switch data transferred from the first microcomputer 8 is data for selecting an analog circuit, the memory of the RAM 20c of the second microcomputer 20.
Store analog switch data in MSEL (step S1
9), and then the data in the memory MSEL is transferred to the second switching circuit 19
Is converted into data for controlling (step S21), and the second switching circuit 19 is operated.

In this state, the second switch of the main amplifier 2
When 21 is pressed and the digital input signal connected to the input terminal 15 is selected, as described above, the switch of the second switching circuit 19 is switched to the terminal 19d side and the D / A converter 16
The digital input signal converted into analog is reproduced.

The first microcomputer 8 of the preamplifier 1 receives necessary serial data from the second microcomputer 20 of the main amplifier 2, and the first switching circuit 7 is switched so as to select the input terminal 5.

Next, when the second switch 22 of the main amplifier 2 is pressed again, the switch of the second switching circuit 19 is switched to the terminal 19a side, and the analog input signal applied to the input terminal 17 is transferred to the front amplifier 18. Switch to play.

The first microcomputer 8 of the preamplifier 1 is the second
The switch data for selecting an analog input signal is received from the microcomputer 20 of, and the input serial data is analyzed (step 17), and it is the data for selecting the analog circuit based on the analysis result.
The first switching circuit 7 selects the input terminal 3 again. The second switch 22 of the main amplifier 2 is thus the preamplifier 2
The input terminal 3 is selected by the first switching circuit 7 of
The input terminals 3, 4, and 5 of the switching circuit 7 are the first terminals of the preamplifier 2.
Are arbitrarily selected by the switches 9a, 9b, 9c.

In this way, the first switch 9a, 9b, 9c, 9d and the second switch 21, 22 can freely input signals connected to the preamplifier 1 and the main amplifier 2 as if they were one component. You can choose.

Also, since the digital input signal connected to the input terminal 15 of the main amplifier 2 is converted into a high quality analog signal by the D / A converter 16 provided in the main amplifier 2 and immediately guided to the front amplifier 18, High fidelity reproduction without deterioration of sound quality is possible.

(G) Effect of the device According to the switching circuit of the audio device according to the present invention, in order to be able to reproduce a high-quality music signal that has passed through the D / A converter, a digital input terminal and a D / A converter are provided in the main amplifier. And a switch for switching the input signals to the preamplifier and the main amplifier, and the switch circuit of the other amplifier can be controlled by the switch of one amplifier, so that a high-quality music signal can be reproduced. You can

Further, since the switch of one amplifier controls the switching circuit of the other amplifier, there is an effect of improving operability.

In addition, it has excellent features such as simple structure and easy implementation because it can be configured at low cost.

[Brief description of drawings]

FIGS. 1 to 2 (A) and (B) show an embodiment of the present invention, and FIG. 1 is a block diagram of essential parts, and FIGS.
(B) is a flow chart of a main part of programs of the first and second microcomputers, and FIG. 3 is a circuit diagram showing a conventional embodiment. Description of main figure numbers 1: Preamplifier 2: Main amplifier 3,4,5,6,15,17,24: Input terminal 7: First switching circuit 8: First microcomputer 9a, 9b, 9c, 9d : First switch 11,12,25,27,28: Output terminal 13,14,29,30: Terminal 16: D / A converter 18: Front amplifier 19: Second switching circuit 20: Second microcomputer 21,22: Second switch 23: Rear amplifier

Claims (1)

[Scope of utility model registration request] 1. A signal switching circuit for an audio device comprising a preamplifier and a main amplifier, wherein the preamplifier is added to an analog input terminal and a digital input terminal and an analog input terminal or a digital input terminal. A first switch for selecting one of the analog signals, a first switching circuit that operates based on ON / OFF of the first switch, and a first microcomputer that controls the first switching circuit And an output terminal for outputting a signal from the first switching circuit, the main amplifier includes a D / A converter, a digital input terminal for adding a digital signal to the D / A converter, and the first switching circuit. An analog input terminal connected to the output terminal that outputs the signal from the circuit, and a digital output terminal that is connected to the digital input terminal at the output of the D / A converter. And the terminal, D / A converter output or a second switching circuit that operates based on the second switch and the second switch on and off to select one of the analog input terminals,
A second microcomputer for controlling the second switching circuit is provided, and the first microcomputer and the second microcomputer control the second switching circuit with the first switch, or the second microcomputer. And a bus line for transmitting a control signal for controlling the first switching circuit with the switch described above.