JP2005065141A - Audio amplifier for multichannel audio apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio amplifier for the multi-channel audio apparatus having a plurality of amplification parts corresponding to a plurality of channels including a sub-woofer gain variable amplification part, wherein the risk of destruction caused by heating due to an excessive output is surely prevented and the audio amplifier is composed of an IC. <P>SOLUTION: The audio amplifier for the multi-channel audio apparatus includes at least a detection part 6 for detecting a temperature T of a sub-woofer gain variable amplification part 4<SB>SW</SB>and a comparison part 8 for comparing the detected temperature T with a first reference temperature T1 and a second reference temperature T2 (T1<T2) within one IC chip. When the detected temperature T is higher than the second reference temperature T2, a gain G of the sub-woofer gain variable amplification part 4<SB>SW</SB>is reduced from an initial value G1 for a predetermined amount ▵G (gain G=G1-▵G). When the detected temperature T becomes lower than the first reference temperature T1, the gain G of the sub-woofer gain variable amplification part 4<SB>SW</SB>is returned to the original gain G1 (increased: gain G=G1). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an audio amplifier for a multi-channel audio device, and more particularly to an audio amplifier for a multi-channel audio device having a plurality of amplifying units corresponding to each of a plurality of channels including a subwoofer variable gain amplifying unit.

  In-vehicle audio equipment is required to have higher performance, and there is a tendency that the higher performance is required to be realized without increasing the price. As one of the high performance of such in-vehicle audio equipment, there is multi-channelization, and for example, a multi-channel in-vehicle audio apparatus such as 4 channels has been developed. The 4-channel in-vehicle audio system has speakers on the front left, rear left, front right, and rear left in the vehicle, left audio signals on the front left and rear left speakers, and right audio on the front right and rear right speakers. A sound is reproduced by applying a signal.

  Furthermore, mounting a subwoofer speaker in an in-vehicle audio device has also been studied so that a low-frequency sound can be emphasized to obtain a powerful and deep sound. In this audio device with a subwoofer, the low frequency components of the left and right audio signals are applied to the subwoofer to reproduce the low frequency components, and the volume can be controlled independently from other speakers. It is a thing.

As an integrated circuit for an on-vehicle multichannel audio device having a subwoofer speaker, Japanese Patent Laid-Open No. 2000-152369 processes an input audio signal and outputs it to the front, rear and subwoofer speakers. A signal, a post-output signal and a subwoofer output signal have been introduced.
JP 2001-152369 A

By the way, in a multi-channel audio device with a subwoofer for vehicle use, it is important and difficult to eliminate the possibility that the power amplifier is destroyed by heat.
This is because in-car multi-channel audio devices are originally used in environments that tend to be hotter than ordinary homes in cars, especially with or without subwoofers. Above all, there are many drivers who try to appreciate music by increasing the volume of the bass to obtain powerful and deep sound, and the subwoofer can adjust its volume independently, so the driver This is because, in order to enhance the acoustic effect, the volume of the subwoofer is increased and an excessive output is likely to occur.

Further, when the audio signal is viewed in frequency, there is a tendency that the low frequency side has a larger amplitude than the high frequency, so that when the subwoofer is attached, there is a strong possibility that the heat generation of the amplification unit for the subwoofer becomes intense. .
Therefore, conventionally, it has been difficult to make an IC effective for reducing the price of a power amplifier of an audio device with a subwoofer for vehicle use.

That is, the power amplifier needs to be improved as the multi-channel audio device becomes higher in performance, and therefore it is easy to increase the price, but it is necessary to avoid the increase in price as much as possible. It is effective to integrate power amplifiers corresponding to all speakers into an IC (Integrated Circuit).
However, in the case of an on-vehicle audio device with a subwoofer, as described above, there are many factors that are likely to cause excessive output. Therefore, considering the destruction due to heat generation, the power amplifier is integrated with the IC. It was difficult in the past.

  The present invention has been made to solve such a problem, and in an audio amplifier for a multi-channel audio device having a plurality of amplifying units corresponding to a plurality of channels including a subwoofer variable gain amplifying unit, It is an object of the present invention to make it possible to configure an IC chip while reliably preventing the possibility of destruction due to heat generated by output.

  The audio amplifier for a multi-channel audio device according to claim 1 is constituted by a single IC chip, and a temperature detection unit for detecting the temperature of the subwoofer variable gain amplification unit, and the temperature detection unit inside the IC chip. A comparator that compares the detected temperature with a preset reference temperature, and when the determination result that the detected temperature is higher than the reference temperature is generated from the comparator; It is characterized in that gain control is performed to lower the gain.

Therefore, according to the audio amplifier for a multi-channel audio device of claim 1, when the temperature detection result of the subwoofer variable gain amplifier becomes higher than the reference temperature, the gain of the subwoofer variable gain amplifier is lowered. It can be avoided that the variable gain amplifier for use becomes a temperature substantially higher than the reference temperature.
Therefore, the audio amplifier for a multi-channel audio device can be integrated with the IC chip while reliably preventing the possibility of destruction due to heat generated by excessive output.

  The audio amplifier for a multi-channel audio device according to claim 2 is composed of one IC chip, and is detected by the temperature detection unit for detecting the temperature of the subwoofer gain variable amplification unit and the temperature detection unit inside the IC chip. A comparison unit that compares the detected temperature with the first reference temperature and a second reference temperature that is higher than the first reference temperature, and the detected temperature is higher than the second reference temperature from the comparison unit. When a signal indicating high is generated, the gain of the subwoofer variable gain amplifying unit is lowered, and when a signal lower than the first reference temperature is generated, the gain before decreasing the gain of the subwoofer variable gain amplifying unit It is characterized by being raised (returned).

Therefore, according to the audio amplifier for a multi-channel audio apparatus of claim 2, the temperature of the subwoofer variable gain amplifier is detected, and the detection result is compared with the first and second reference temperatures set in advance. When the detection result is higher than the range between the two reference temperatures, the gain of the variable variable amplifier for the subwoofer is decreased, and when the detection result is lower, the gain of the variable variable amplifier for the subwoofer is increased. Can be controlled.
Therefore, the audio amplifier for a multi-channel audio device can be integrated with the IC without reliably preventing the possibility of destruction due to heat generated by excessive output.
When the temperature falls between the first and second reference temperatures, the original gain is restored, so that it is possible to avoid the situation where the subwoofer volume desired by the driver cannot be achieved. it can.

According to the audio amplifier for a multi-channel audio device of claim 1, no matter how the audio device user (for example, driver) controls the volume of the subwoofer to increase the volume, the temperature of the subwoofer variable gain amplification unit is set in advance. Since the gain is automatically reduced when the set reference temperature is exceeded, it is possible to prevent the audio amplifier for a multi-channel audio device from being destroyed due to heat generated by an excessive output.
Since the audio amplifier for the multichannel audio device is constituted by the IC chip, the price of the audio amplifier for the multichannel audio device can be reduced.

According to the audio amplifier for a multi-channel audio device of claim 2, if the temperature of the subwoofer variable gain amplifier is higher than the second reference temperature, the gain can be lowered to avoid an excessive output state.
Moreover, if the temperature of the subwoofer variable gain amplification unit becomes lower than the first reference temperature as a result of the gain reduction, the gain can be restored to the original level of the subwoofer desired by the user (for example, driver), It is possible to avoid the situation where the subwoofer volume desired by the user cannot be achieved.

According to a first aspect of the present invention, an audio amplifier for a multi-channel audio device is configured in one IC chip, and a temperature detection unit that detects the temperature of a subwoofer variable gain amplification unit, and the temperature detection unit A comparison unit that compares the detected temperature detected by the step and a preset reference temperature, and controls the gain of the subwoofer gain variable amplification unit to be lowered when the detected temperature is higher than the reference temperature. It is a thing.
As the reference temperature, an appropriate temperature should be selected as an allowable limit temperature at which destruction can be avoided. In the case of a normal IC, that is, an IC formed on a silicon semiconductor substrate, 150 to 170 in consideration of its heat resistance and the like. It can be said that it is preferable to set the temperature within a range of ° C, for example, 150 ° C.

In the second embodiment of the present invention, the first and second reference temperatures higher than the first reference temperature are set as the reference temperatures, and when the temperature of the subwoofer variable gain amplifier is lower than the first reference temperature, The gain of the variable gain amplifying unit is returned to the original magnitude, and when the temperature is higher than the second reference temperature, the gain of the subwoofer variable gain amplifying unit is forcibly reduced.
As with the reference temperature in the second embodiment, the second reference temperature should be selected as an allowable limit temperature that can avoid destruction, and is formed on a normal IC, that is, a silicon semiconductor substrate. In the case of IC, it can be said that it is preferable to set the temperature within a range of 150 to 170 ° C., for example, 150 ° C. in consideration of the heat resistance and the like.

Further, the first reference temperature is lower than the second reference temperature, and there is no possibility of destruction of the IC chip due to heat generation of the subwoofer variable gain amplifier before the gain of the amplifier is forcibly reduced. It can be said that it is preferable to select a temperature at which the gain can be returned. Specifically, it may be set to a temperature lower by, for example, 10 to 30 ° C. than the second reference temperature.
By the way, if the first reference temperature is set too low than the second reference temperature, there is a possibility that the state in which the volume from the subwoofer preferred by the user (such as a driver) is forcibly lowered will continue for a long time. In addition, if the temperature is set too close to the second reference temperature, there is a problem that the sound volume frequently changes due to the gain change and the stability of the sound is impaired. Therefore, it can be said that it is preferable to set the first reference temperature in consideration of both problems.

The present invention arranges speakers on the front left, rear left, front right, and rear left in the vehicle, the left audio signal on the front left and rear left speakers, the right audio signal on the front right and rear right speakers, Apply low-frequency components (audio signals filtered with a low-pass filter) of the left audio signal and right audio signal to the subwoofer speaker at an appropriate location (any location within the car because of sound effects) to reproduce sound. It can be said that it is a preferable embodiment to be applied to a 4.1 channel in-vehicle audio apparatus.
However, the present invention is not necessarily limited thereto, and the present invention can be generally applied to an amplifier for a multi-channel audio apparatus having a subwoofer, and is not limited to a vehicle-mounted one.

Hereinafter, the present invention will be described in detail according to illustrated embodiments.
1 and 2 show a first embodiment of an audio amplifier for a multi-channel audio apparatus according to the present invention. FIG. 1 is a circuit diagram, and FIG. 2 is a flowchart showing a gain control operation of a subwoofer variable gain amplifier. .
In the figure, the multi-channel audio device for audio amplifier of the present embodiment _2, in _{4 FL, 4 RL, 4 SW} , 4 RR, 4 FR amplification unit constituting the multichannel audio device for audio amplifier _{2, 4 FL} the amplifier for amplifying the audio signal S _FL to the left front speaker, 4 _RL is an amplification unit that amplifies the audio signal S _RL of the rear left speaker.

4 _SW is amplifying unit that amplifies the subwoofer signal S _SW that has passed through the low-pass filter LPF to subwoofer speaker, for example, a gain control signal such as a voltage, which is to control the gain (gain), of the claims This corresponds to the variable gain amplifier for subwoofer in the range. Gain of the amplification unit _{4 SW} is controllable in the range of, for example, 0～40DB.
4 _RR is an amplifying unit that amplifies the audio signal S _RR to the rear right speaker, and 4 _FR is an amplifying unit that amplifies the audio signal S _FR to the front right speaker. The amplifying units 4 _FL , 4 _RL , 4 _RR , 4 _FR other than the amplifying unit 4 _SW are set to have a constant gain, for example, 26 dB by BTL connection (Bridged Transless).

  Reference numeral 6 denotes a temperature detection unit (temperature sensor) for detecting the temperature of the subwoofer amplification unit 4SW, and 8 denotes a temperature detected by the temperature detection unit 6, that is, a detection temperature T and a preset first reference temperature. It is a comparison circuit that compares T1 and a second reference temperature T2. In the comparison circuit 8, the first reference temperature T1 to be compared with the detected temperature T is set as a temperature at which there is no risk of destruction due to heat generation and the gain of the amplifier 4SW can be returned to the gain before the forced reduction. It is. In this embodiment, it is set to 140 ° C.

The second reference temperature T2 is a temperature set as a temperature at which it can be said that it is necessary to reduce the gain and suppress the heat generation because there is a risk of destruction of the IC chip due to the heat generation of the subwoofer variable gain amplification unit. Is set to 150 ° C.
A gain control circuit 10 controls the gain of the amplifying unit _4SW based on the comparison result of the comparison circuit 8.
The audio amplifier 2 for a multi-channel audio device is formed in an IC chip made of one silicon Si.

It will now be described by referring to the gain control operation for the subwoofer for the variable-gain amplifying unit 4 _SW of the multichannel audio device for audio amplifier to FIG.
(1) “gainG = G1”
Gain gain subwoofer for the variable-gain amplifying unit 4 _SW is in a predetermined initial gain G1.
(2) “T> T2?”
Detecting the temperature T of the subwoofer for the variable-gain amplifying unit 4 _SW, it determines the detected temperature T is higher than or the second reference temperature T2.
If the determination result is No, this determination is repeated until a determination result of Yes is obtained.

(3) “gainG = G−ΔG”
The case where the judgment result is Yes (2), i.e., when the temperature T of the subwoofer for the variable-gain amplifying unit 4 _SW is higher than the second reference temperature T2, the gain G of the subwoofer for the variable-gain amplifying unit 4 _SW G1 To a predetermined amount ΔG is forcibly reduced [gainG (G1) −ΔG].
This step gain G is (becomes G1-.DELTA.G) forcibly .DELTA.G reduced is from the initial value G1 by (3), the output of the subwoofer for the variable-gain amplifying unit 4 _SW decreases, the heating value of course is less The temperature will begin to drop.

(4) “T <T1?”
Step (3) is completed, it detects the temperature T of the subwoofer for the variable-gain amplifying unit 4 _SW, determines whether the detected temperature T is lower than the first reference temperature T1.
If the determination result is No, the process returns to step (2).
(5) “gainG = G1”
The case (4) of the judgment result is Yes, GainG i.e., when the temperature T of the subwoofer for the variable-gain amplifying unit _{4 SW} is lower than the first standard temperature T1, the gain G of the subwoofer for the variable-gain amplifying unit _{4 SW} -ΔG is restored to the original G1 (initial value). Then, it returns to step (2).

Thus, when the temperature T of the subwoofer for the variable-gain amplifying unit 4 _SW is lower than the first reference temperature T1, the forced ΔG the lowered value of the gain G of the subwoofer for the variable-gain amplifying unit 4 _SW since return to the original initial value G1, we can state that the temperature T of the subwoofer for the variable-gain amplifying unit 4 _SW is against the will of the driver or the like T1 or less, such to no fear of breaking is prevented from continuing.
That is, it is unavoidable to forcibly reduce the gain G of the subwoofer variable gain amplifying unit 4 _SW in order to avoid the destruction of the IC chip, but the volume of the subwoofer is reduced against the intention of the driver or the like. become. Therefore, it is not preferable to continue the state contrary to the intention of the driver or the like even though the heat generation is reduced and the IC chip is no longer damaged by the heat generation. Therefore, when the detected temperature T becomes lower than the first reference temperature T1, the gain G is returned to the original G1 to return to a state in line with the intention of the driver or the like.

Figure 3 is a flow chart for explaining the gain control operation of the second embodiment of the subwoofer for the variable-gain amplifying unit 4 _SW of the present invention. In this embodiment, only one temperature Tsta is set as a reference temperature, and this reference temperature Tsta is selected as an allowable limit temperature at which destruction can be avoided, and the second temperature of the first embodiment. This corresponds to the reference temperature T2. What corresponds to the first reference temperature T1 in the first embodiment does not exist in the present embodiment (second embodiment).

With reference to FIG. 3 illustrating the gain control operation of the subwoofer for the variable-gain amplifying unit 4 _SW.
(1) “gainG = G1”
Gain gain subwoofer for the variable-gain amplifying unit 4 _SW is in a predetermined initial gain GI.
(2) “T> Tsta (T2)?”
The temperature T of the subwoofer variable gain amplifier 4SW is detected, and it is determined whether or not the detected temperature T is higher than the reference temperature Tsta (T2).

(3) “gainG = G−ΔG”
When the determination result of (2) is Yes, that is, when the temperature T of the subwoofer variable gain amplifier 4SW is higher than the reference temperature Tsta (T2), the gain G of the subwoofer variable gain amplifier 4SW is set to a predetermined value from G1. The amount ΔG is forcibly lowered [gain (G−ΔG)].
Since the gain G by the step (3) is reduced ΔG from forcibly G1, the output of the subwoofer for the variable-gain amplifying unit 4 _SW decreases, the heating value decreases course, that the temperature starts to decrease Become.

(4) “t measurement”
When step (3) ends, a certain time t (for example, several tens of seconds to several minutes) is measured, and then the process returns to step (2). This prevents hunting in the gain control of the subwoofer for the variable-gain amplifying unit 4 _SW, in order gain is prevented from varying frequently, once to continue its state After lowering the gain G1 by at least the time t To do.
(5) “gainG = G1”
The case where the judgment result is No in (2), i.e., when the temperature T of the subwoofer for the variable-gain amplifying unit _{4 SW} reference temperature Tsta (T2) lower than the gain G of the subwoofer for the variable-gain amplifying unit 4SW gain ( The original G1 (initial value) is restored from (G−ΔG). Then, it returns to step (2).

  By this step (5), although the temperature T of the subwoofer variable gain amplifying unit 4SW is below the reference temperature Tsta (T2) at which there is no possibility of destruction, the gain G is forcibly lowered to reduce the volume of the subwoofer against the intention of the driver or the like. It is possible to avoid the state where the sound level is lowered for a long time, and to recover the sound volume state according to the intention of the driver or the like.

  INDUSTRIAL APPLICABILITY The present invention has general applicability to audio amplifiers for multichannel audio devices having a plurality of amplifiers corresponding to each of a plurality of channels including a subwoofer variable gain amplifier, and is not necessarily limited to in-vehicle use, for example There is also the possibility to use it.

1 is a circuit diagram of a first embodiment of an audio amplifier for a multichannel audio apparatus according to the present invention; FIG. It is a flowchart which shows the gain control operation | movement of the said 1st Example. It is a flowchart which shows the gain control operation | movement of the 2nd Example of the audio amplifier for multichannel audio apparatuses of this invention.

Explanation of symbols

2... Audio amplifier for multi-channel audio device, 4 _FR , 4 _RR , 4 _FL , 4 _RL , 4 _SW ... Amplifying section of each channel, 6... Temperature detecting section, 8. 10: Gain control circuit.

Claims (2)

In an audio amplifier for a multi-channel audio device having a plurality of amplification units corresponding to each of a plurality of channels including a subwoofer variable gain amplification unit,
It is configured in one IC chip,
Inside the IC chip, a temperature detection unit for detecting the temperature of the variable gain unit for subwoofer,
Comparison means for comparing the detected temperature detected by the temperature detection unit with a reference temperature set in advance as an allowable limit temperature capable of avoiding destruction,
Having at least
An audio for a multi-channel audio device, characterized in that when the signal indicating that the detected temperature is higher than the reference temperature is generated from the comparing means, the gain of the subwoofer variable gain amplifier is lowered by a predetermined amount. Amplifier. In an audio amplifier for a multi-channel audio device having a plurality of amplification units corresponding to each of a plurality of channels including a subwoofer variable gain amplification unit,
It is configured in one IC chip,
Inside the IC chip, a temperature detection unit for detecting the temperature of the variable gain unit for subwoofer,
The detection temperature detected by the temperature detection unit and a first reference temperature lower than an allowable limit temperature at which destruction can be avoided and an allowable limit temperature at which destruction higher than the first reference temperature can be avoided are set in advance. Comparing means for comparing the measured second reference temperature;
Having at least
When the comparison result that the detected temperature is higher than the second reference temperature is obtained from the comparison means, the gain of the subwoofer variable gain amplifying unit is lowered and the comparison result that the detected temperature is lower than the first reference temperature is obtained. An audio amplifier for a multi-channel audio apparatus, wherein the gain of the subwoofer gain variable amplification section is increased to a gain before being lowered.

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