JPS63311807A - Voice reproducing signal correcting device - Google Patents

Abstract

PURPOSE:To adjust the control level with respect to the sound volume without being affected by the signal level by combining the gain of a power amplifier and the input versus sound pressure level of a speaker so as to recognize the reproduced sound pressure level from the output signal level of a preamplifier in a reproducing signal selection circuit. CONSTITUTION:A reproducing signal selection circuit 2 is provided, which is connected to plural sound signal output devices 1 of different signal form, has a selection circuit and a preamplifier and amplifies and outputs a signal from one of sound signal output devices 11, 12 to be selected. A signal S5 corresponding to reproducing signals SL1, SR1 and the noise level of the noise source is inputted to the post-stage of the circuit 2, a reproducing signal correction value regulated based on the input signal is calculated and the output level of the reproducing signal is corrected based on the reproducing signal correction value by means of a level correction means 6. Thus, the level correction quantity is calculated based on the sound reproducing signal and the signal S5 from a noise level signal generating section 5 and the reproducing signal is corrected by the level correction quantity.

Description

[Detailed Description of the Invention] [Summary] When the sound reproduced by an in-vehicle stereo reproduction device etc. is masked and erased by engine noise etc., a reproduction signal correction that applies a volume equivalent to the volume erased by masking. The present invention is an audio playback signal correction device that performs accurate correction without depending on the signal characteristics of the audio playback devices even when a plurality of audio playback devices are provided.

[Industrial application field]

The present invention relates to an audio playback signal correction device that corrects playback sound by the amount that is erased by noise.

The audio reproduction signal correction device of the present invention is used in a vehicle-mounted stereo reproduction device and the like.

[Conventional technology]

For example, the sound from a car stereo playback device can be heard from the engine,
The so-called "masking phenomenon" is known, in which sounds from air conditioners etc. are drowned out. This masking occurs primarily in the low frequency range. Therefore, the sound level in the frequency range that is canceled by masking is increased by a level corresponding to the level that is canceled by noise.

As a conventional level correction method, a microphone is installed in a car to detect raw noise, and the level is increased according to the noise level. Other known level correction methods include matching the state of the engine, which is the noise source, with the readings of the vehicle speed sensor, or reading the state of the air conditioner, and making level corrections according to these readings. There is.

[Problem that the invention seeks to solve]

When the level of reproduced sound is corrected using the above-mentioned microphone, there is a problem in that it is expensive.

Furthermore, in any of the above cases, check the volume angle of the preamplifier's volume resistor for level correction.

This is done by adjusting the volume angle. If there is only one playback device, this type of method is fine, but
When multiple playback devices such as CD players, cassette decks, and tuners are installed, each with different characteristics, the method of uniformly adjusting the volume as described above results in different signal levels being input to the volume resistor. The correction effect varies due to the level difference between the sets connected before and after the device, and a problem has been encountered in that sufficient level correction cannot be performed.

Therefore, there is a need for a relatively low-cost level correction device that can perform accurate level correction even when a plurality of playback devices are provided.

[Means and actions to solve the problem]

FIG. 1 shows a block diagram of the principle of the reproduced signal correction device of the present invention.

In Figure 1, the gain of power amplifier 3 and speaker 4
The reproduction sound pressure level can be determined from the output signal level of the preamplifier housed in the reproduction signal selection circuit 2 in combination with the input versus sound pressure level. Therefore, even if a plurality of audio signal generators 11 and 12 are provided, the control level for the volume can be adjusted from the output signal level of the preamplifier without being affected by these signal levels. The present invention utilizes such a principle.

Therefore, the audio reproduction signal correction device of the present invention inputs the audio reproduction signals SLI and SRI after the preamplifier, in other words, before the power amplifier 3, and outputs the audio reproduction signals and the signal S5 from the noise level signal generator 5. A level correction amount is calculated based on the level correction amount, and the reproduced signal is corrected using this level correction amount.

Therefore, according to the present invention, the playback device is connected to a plurality of audio signal output devices 1 having different signal formats, has a selection circuit and a preamplifier, and amplifies and outputs the signal from one selected audio signal output device. A signal selection circuit 2 is provided at a stage subsequent to the reproduction signal selection circuit, and includes a reproduction signal SLI from the reproduction signal selection circuit.

A signal S5 corresponding to the noise level of the SRI and the noise source is input, a reproduced signal correction value defined based on these input signals is calculated, and the output level of the reproduced signal is corrected based on the reproduced signal correction value. An audio reproduction signal correction device is provided which includes level correction means 6.

The above level correction is performed for a specific frequency range that is canceled out by noise.

〔Example〕

An audio reproduction signal correction device according to a first embodiment of the present invention will be described with reference to FIG.

The audio playback signal correction device includes a plurality of playback signal generation devices such as a CD player 11, a cassette deck 12, and a tuner 13, and a playback signal selection device that includes a built-in preamplifier that selects one of the playback signal generation devices and amplifies it with a predetermined gain. circuit 2, a power amplifier 3 that amplifies the reproduction signals SL1 and SRI selected from the reproduction signal selection circuit and amplified by the preamplifier to an output level sufficient to drive the speakers 41 and 42;
has. Furthermore, an audio reproduction signal correction device is provided between the reproduction signal selection circuit 2 and the power amplifier 3, and is configured to compensate for noise in the reproduction signal SL1. It has level correction means 6 for correcting SR1.

The level correction means 6 includes a level correction circuit 6 in a low frequency region.
1, 62, Level correction circuit for all frequency ranges 64゜65
and a level control circuit 63a, which in this embodiment is a microcomputer. Level control circuit 63
a is the volume level detection circuit 7 which detects the playback signals SLI and SRI;
1, the vehicle speed signal S91 from the vehicle speed sensor 91 is transmitted through the frequency/voltage (F/V) converter 71, and the power on/off and output cylinder/
A signal 392 indicating low is input manually, and a correction value is determined using these inputs as parameters, and level correction circuits 64 and 65 for all frequency regions and level correction circuit 61 for a low frequency region are used.
, 62, respectively control signals SL, SRC+,
5LC2 and 5RC2 are applied to reproduce the reproduced signal SL1. S.R.
The power amplifier 3 outputs the signals SL2 and SR2 that have been corrected by 1.

This embodiment is aimed at stereo, and SL1 indicates the left channel reproduction signal, and SRI indicates the right channel reproduction signal.

Further, in this embodiment, the level correction means 6 uses the reproduced signal SL.
After correcting all frequencies of I and SRI, correction is performed for the low frequency region that is particularly affected by noise.

The detailed circuit of the volume level detection circuit 71 in FIG. 2 is as shown in FIG. 3 (both channel reproduction signal SLI).

It is composed of an addition circuit 711 that adds SRI, and a detector 712 that detects the added signal as shown. The detection signal S71 is applied to the correction control circuit 63a.

The signal from the vehicle speed sensor 91 is shown at a frequency corresponding to the vehicle speed, and is expressed using a well-known frequency/voltage converter (F/V
It is applied to the correction control circuit 63a as a voltage signal S72 via a converter) 72.

As shown in FIG. 4, the level correction circuit 61 is an amplifier 61 to which the L channel reproduction signal SLI is applied to the inverting input terminal.
1, and a weighting circuit 612 connected between the output terminal and the non-inverting input terminal of the amplifier 611. A control signal 5LC2 from a correction control circuit 63a, which will be described later, is connected to the weighting circuit 612, and outputs a level correction signal 5LLC in response to the control signal 5LC2. The weighting circuit 612 is weighted to output a correction signal for low frequency regions affected by noise. The level correction circuit 62 on the R channel side and the level correction circuits 63 and 64 for all frequency regions are also similar to the circuit shown in FIG.

The operation of the correction control circuit 63a, in this embodiment the microcomputer, will be described with reference to the flowcharts of FIGS. 5 to 8 and the correction data configuration diagram of FIG. 9.

When the correction control circuit 63a, ie, the micro combiator, is activated, it is checked whether or not the level correction control is requested (FIG. 5, step 5o1). Exit if control is not requested.

If control is requested, a detection signal S7 from the volume level detection circuit 71 is sent via an A/D converter (not shown).
1 (Step S○2). Next, as shown in the flowchart shown in FIG. 6, the parameter l is determined according to the volume level (step 303 in FIG. 5, steps 331 to S36 in FIG. 6).

Similarly, read the vehicle speed signal S72 (step 5O4), and
As shown in the flowchart in the figure, a parameter m is determined according to the vehicle speed (step 5O5).

Furthermore, the digital air conditioner signal S92 is read (step 5O6), and the parameter n is determined according to the contents of the flowchart in FIG. 8 (step 5O7).

Thereafter, a correction value C0 is determined using these l, m, and n as parameters (508). This correction value is
As shown in FIG. 9, the parameters (1, m, n) are stored in a memory (not shown) to be uniquely determined as addresses. Measurements are taken for various cases such as noise, noise from an air conditioner, etc., the results are analyzed, and optimal values are determined according to various conditions and stored in memory.

For example, if the reproduced sound level is high, for example J=2, and the influence of noise is not seen, the correction value is small. The higher the vehicle speed, the higher the noise level, so the correction value is larger. The larger the parameter n of the air conditioner, the larger the correction value.

The correction values obtained as above are used as voltage level level control signals 5LLC+, 5RLC1, 5LLC2, 5RLC.
2 as level correction circuits 61 , 62 , 63 , 64
The weighting is output to the circuit 612 (step 509), and the target correction amount is selected.

Thereafter, repeat the above process.

According to the above correction, as shown in FIG. 10, even if the original reproduced signal level is erased by noise as shown in the broken line CV2 with respect to the curve CVI, the level is corrected as shown in the curve CV3. , a corrected reproduction signal SL2 equivalent to the original reproduction signal level.

SR2 is obtained.

Since the above correction is performed on the reproduced signal using the reproduced signal as a reference, efficient and accurate correction is possible without depending on the type of reproduced signal generating device.

A second embodiment of the audio repeating signal correcting device of the present invention will be described with reference to FIG.

The audio reproduction signal correction device shown in FIG. 11 has signal conversion circuits 81 to 83 added to the audio reproduction signal correction device shown in FIG. Attached is the changeover switch circuit 632
This was realized in

The signal conversion circuit 82 for the vehicle speed signal consists of a plurality of Schmitt trigger circuits 821 to 823 as shown in FIG. .1.2.3
Outputs the corresponding on signal. Volume level detection signal S
The signal conversion circuit 81 for 71 is also constituted by a Schmitt trigger circuit as shown in FIG. 13, and outputs an ON signal corresponding to J=0.1.2 based on the reference as shown in the flowchart of FIG. The signal conversion circuit 83 for the air conditioner signal S92 outputs an on signal corresponding to n=o, 1.2 shown in FIG. 8 based on the power on/off signal and high/low signal.

The matrix circuit 631 of the correction control circuit 63b receives signals 1.1 from the signal conversion circuits 81 to 83. A matrix circuit 631 that inputs m and n signals and is determined by these three-dimensional parameters.
One of the correction data similar to that shown in FIG. 9 stored in advance in the computer is extracted. The output of the matrix circuit 631 is output as a binary code. The weighting switch circuit 632 sets a correction amount corresponding to the correction binary code in each level correction circuit.

〔Effect of the invention〕

As described above, the present invention performs level correction using the reproduced signal as a reference, and enables accurate level correction for various audio signal generating devices without depending on these characteristics.

Further, in the present invention, existing signals such as a vehicle speed sensor and an air conditioner operation signal are used as signals for level correction, and level correction can be performed at a relatively low cost.

[Brief explanation of drawings]

FIG. 1 is a principle proref diagram of the audio reproduction signal correction device of the present invention, FIG. 2 is a configuration diagram of the audio reproduction signal correction device of the embodiment of the invention, and FIG. 3 is a volume level detection circuit diagram of FIG. 2. Figure 4 is the second
Figure 5 is an operation flowchart of the correction control circuit in Figure 2. Figures 6 to 8 are partial detailed flowcharts of Figure 5. Figure 9 is a correction in the correction control circuit in Figure 2. Data configuration diagram, FIG. 10 is a correction characteristic curve according to an embodiment of the present invention, and FIG.
FIG. 12 is a block diagram of an audio reproduction signal correction device according to another embodiment of the present invention, FIG. 12 is a correction control circuit diagram of FIG. 11, and FIG.
2 is a signal conversion circuit diagram for vehicle speed signals shown in FIG. 1; FIG. (Explanation of symbols) 1...Audio signal generator, 2...Reproduction signal selection circuit, 2a...Preamplifier, 3...Power amplifier, 4...Speaker, 5...Noise level signal generation 6...Level correction means, 61, 62...Low frequency region level correction circuit, 63
. . . Correction control means, 64 , 65 . . . Full frequency domain level correction circuit, 71
...Volume level detection circuit. Figure 2 Volume level detection circuit diagram Figure 3m Figure 2 level correction circuit diagram Figure 4 $5 Figure 7 @ Figure 8

Claims (1)

[Claims] 1. Connected to a plurality of audio signal output devices (1) with different signal formats, having a selection circuit and a preamplifier, and amplifying and outputting the signal from one selected audio signal output device. A reproduced signal selection circuit (2) is provided at a subsequent stage of the reproduced signal selection circuit to output the reproduced signal (SL1) from the reproduced signal selection circuit.
, SR1) and a signal corresponding to the noise level of the noise source (
S5), calculates a reproduction signal correction value defined based on these input signals, and corrects the output level of the reproduction signal based on the reproduction signal correction value (6).
An audio reproduction signal correction device comprising: 2. The audio reproduction signal correction device according to claim 1, wherein the level correction means corrects the output level of the reproduction signal only in a specific frequency range. 3. The audio signal output device is a sound device mounted on a vehicle, and the signal corresponding to the noise level is a signal indicating the operating state of the internal combustion engine and/or the operating state of the air conditioner of the vehicle. An audio playback signal correction device as set forth in claim 1 or 2, characterized in that: 4. The audio reproduction signal correction device according to any one of claims 1 to 3, wherein the specific frequency range is a low frequency range.