JP2539210Y2 - Sound field playback device - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention relates to improvement of a sound field reproducing apparatus using a digital signal processor or the like, and particularly to improvement of input signal adjustment.

[Prior art] Conventionally, an analog signal is converted into a digital signal, and the digital signal is subjected to desired signal processing by digital signal processing means (digital signal processor: hereinafter referred to as DSP). Driving sound field reproducing means is employed.

Referring to FIG. 3, this type of reproducing apparatus will be described. In the figure, 01 is an analog signal input terminal, 02 is input level adjusting means, 03 is analog-digital converting means (hereinafter referred to as ADC), 04 is DSP, and 05 is DSP Digital-analog conversion means (hereinafter referred to as DAC) 06 is an analog output terminal. 07 is A
This is a level meter that displays the input level to DC03.

The analog signal input to input terminal 01 is used for level adjustment
After the level is adjusted to a level determined for normal operation of the ADC03 by 02, the analog signal input to the ADC03 is converted to a digital signal. The digital signal is input to DSP04 and subjected to necessary signal processing. The signal-processed digital signal is converted from a digital signal to an analog signal by the DAC 05 and output to the output terminal 06. The output analog signal is amplified to a required signal level via an amplifier circuit (not shown), and then drives the speaker device.

The level adjusting means 02 generates an overflow when an excessive input is supplied to the ADC 03, and increases the quantization noise when an excessive input is supplied to the ADC 03. Provided for adjustment within the level range.

[Problems to be Solved by the Invention] As described above, it is necessary to adjust the input level to the ADC, and the level of the input signal is controlled by a source device connected to the input terminal, for example, a tape recorder, a tuner, a compact disk player. Program source (music genre) even if the signal is from the same device.
Therefore, it is troublesome to monitor the level meter and adjust the level adjusting means each time.

As a means for solving such inconvenience, a sound field reproducing apparatus shown in FIG. 4 has been proposed.

In the figure, 01 is the analog signal input terminal, 03 is the ADC, 04 is D
SP and 05 are DACs and 06 is an analog output terminal, which performs the same operation as in FIG.

Reference numeral 08 denotes a central processing unit (hereinafter referred to as a CPU), 02 'denotes an input level adjusting unit, and 09 denotes a motor for driving the level adjusting unit 02' under the control signal of the CPU 08. In this device, the signal level is detected by the DSP 04, and the CPU 08 outputs a motor control signal based on the signal level information output in response to the signal level. The input level is adjusted by changing the amount of attenuation by sliding the sliding piece of the resistor. And in this device, DS
If the input level detected at P04 is high, the variable resistor 0
Adjust the input level to ADC03 by increasing the amount of attenuation of 2 '.
Adjust the input level to C03. Therefore, the level is automatically adjusted in accordance with the level of the input signal, so that the trouble of the apparatus shown in FIG. 3 can be eliminated. However, the adjusting means operates in the direction of decreasing the level if there is a high-level part in the music program, and operates in the direction of increasing the level if there is a low-level part even in the same source. Therefore, there is a problem that the level linearity in the same program is lost.

[Means for Solving the Problem] The present invention provides an analog signal input terminal, an input level adjusting means connected to the input terminal, an analog-digital converting means connected to the input level adjusting means, Digital signal processing means connected to the digital conversion means, digital-analog conversion means connected to the digital signal processing means, and input / output characteristics of the input level adjustment means connected to the digital-analog conversion means; Output level adjusting means having reverse input / output characteristics, an analog signal output terminal connected to the output level adjusting means, and the input level adjusting means based on signal level information detected and obtained as an output by the digital signal processing means. And a central processing unit for controlling the output level adjusting unit.

[Operation] The analog signal supplied to the analog signal input terminal is adjusted to an appropriate level as an ADC input by the input adjusting means, converted into a digital signal by the analog-digital converting means, and a desired signal processing is performed by the digital signal processing means. Then, the signal is converted into an analog signal by a digital-analog converter, adjusted by the output level adjuster in a manner opposite to the adjustment by the input level adjuster, and output to an analog signal output terminal as an analog signal.

Further, the CPU controls the input level adjusting means and the output level adjusting means based on DSP level signal information, and operates so that the level change amount by the input level adjusting means is complemented by the output level adjusting means.

[Embodiment] The present invention will be described below with reference to an embodiment shown in FIG.

In FIG. 1, 1 is an analog signal input terminal, 2 is an input level adjusting means, 3 is an ADC, 4 is a DSP, 05 is a DAC, 6 is an analog output terminal, 7 is an output level adjusting means, and 8 is a CPU. The input level adjusting means 2 and the output level adjusting means 7
Have input / output characteristics (gain characteristics) complementary to each other. That is, the gain of the input adjustment means is β
When (β ≦ 1: attenuation characteristic), the gain of the output adjusting means is set to 1 / β (amplification characteristic). Alternatively, when the gain of the input level adjusting means is set to β (β ≧ 1: amplification characteristic), the gain is set to 1 / β (attenuation characteristic) in the output level adjusting means.
And Hereinafter, the case where β ≦ 1 will be described. The gain of each of the input level adjusting means 2 and the output level adjusting means 7 is adjusted by a control signal of the CPU 8.

In the above configuration, the analog signal input to the input terminal 1 is input to the ADC 3 via the input level adjusting means 2, and the analog signal is converted into a digital signal. The digital signal is input to the DSP 4 and performs necessary signal processing. The processed digital signal is converted from a digital signal to an analog signal by the DAC 5 and output to the output terminal 6 via the output level adjusting means 7. The output analog signal is amplified to a required signal level via an amplifier circuit (not shown), and then drives the speaker device.

The DSP 4 outputs signal level information output corresponding to the signal level, and the information is processed in the CPU 8 to output a control signal for adjusting the gain of the input level adjusting means 2 and the output level adjusting means 7. The input level adjusting means 2 adjusts the gain based on the control signal so that the excessive signal and the excessive signal are not input to the ADC 3. On the other hand, the output level adjusting means 7 adjusts the gain based on the control signal. The gain characteristic has a characteristic to complement the gain by the input level adjusting means 2. That is, the input level adjusting means 2
When the gain is set to β (attenuation) by the control of the CPU 8, the gain is set to 1 / β to supplement the attenuation β, and the amplification amount 1 / β is obtained. Therefore, the input terminal 1 level and the output terminal 6 level maintain a proportional relationship regardless of the adjustment amount by the input level adjusting means 2.

FIG. 2 shows a specific configuration of the input level adjusting means 2 and the output level adjusting means 7. The input level adjusting means 2 is composed of a variable resistor 21 and a resistor 22 connected between the variable resistor 21 and the ground. The output level adjusting means 7 comprises an amplifier circuit.
73, a variable resistor 71 connected to the feedback loop of the amplifier circuit, and a resistor connected between the variable resistor 71 and the ground.
It consists of 72. Each of the variable resistors 21 and 71 is driven by a motor 9 whose rotation axis is controlled by a CPU 8. The variable resistor 21 the resistance value R ₁ and R ₄ and the resistance value R ₃ the resistance value of the resistor 72 of resistance R ₂ and the variable resistor 71 of the variable resistor 21 R _1: R ₂ = R ₃ : if selected input-output characteristic of the resistance value and the variable resistor so that the R _4, can be set input and output characteristics of the output level adjusting means and the input level adjusting means (gain) in reciprocal relationship.

[Effects of the Invention] According to the invention described above, the amount of input level adjustment by the input level adjustment means is supplemented by the output level adjustment means. The linearity of input and output can be maintained because the proportional relationship is maintained irrespective of the operation of the device, and it has the advantage that the optimal input to the ADC can be set automatically when the source device is switched or the program source changes. .

When the input level adjusting means is configured to have an amplification characteristic as described above, the output level adjusting means may be configured to have an attenuation characteristic. Further, each adjusting means may use an electronic volume instead of the variable resistor shown in the figure.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the invention, FIG. 2 is a block diagram showing a specific example of the invention, and FIGS. 3 and 4 are block diagrams of a conventional example. 1: Analog signal input terminal 2: Input level adjustment means 3: Analog-digital conversion means 4: Digital signal processing means 5: Digital-analog conversion means 6: Analog signal output terminal 7: Output level adjustment means 8: Central processing means

Claims (1)

(57) [Scope of request for utility model registration] 1. An analog signal input terminal (1), input level adjusting means (2) connected to the input terminal (1), and analog-digital converting means connected to the input level adjusting means (2). (3) and digital signal processing means (4) connected to the analog-digital conversion means (3);
A digital-analog converting means (5) connected to the digital signal processing means (4), and an input / output characteristic opposite to the input / output characteristic of the input level adjusting means (2) connected to the digital-analog converting means (5); Output level adjusting means (7) having input / output characteristics, an analog signal output terminal (6) connected to the output level adjusting means (7), and signal level information output from the digital signal processing means (4) And a central processing means (8) for controlling the input level adjusting means (2) and the output level adjusting means (7).