JP2005123747A - Audio reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio reproducing apparatus with simple circuit constitution adaptive to the case that a maximum output of each channel differs from each other and exhibiting an acoustic effect equal to that of prior arts. <P>SOLUTION: A power supply voltage Vcc is supplied to each of audio amplifiers 14a to 14f through a rectifier circuit 21 from a power transformer 20. Then the impedance of each of loudspeakers 15a to 15f is set in accordance with the maximum output of each output channel. Thus, in the case of increasing the maximum output of a woofer more than that of other loudspeakers, the impedance of the woofer is selected smaller to permit the setting of a higher maximum output. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an audio reproducing apparatus having a plurality of output channels such as 5.1CH.

  In recent years, with the progress of digital audio technology and acoustic technology such as speakers, multi-channel audio playback devices have been developed and have become widely used because they have an acoustic effect that is faithful to the original sound and excellent in realism.

  In such an audio reproducing apparatus, an audio signal is output for each channel from the digital signal processing circuit, transmitted to a D / A converter and an audio amplifier corresponding to each channel, and audio is reproduced and output from each speaker. The role of each output channel has been diversified along with the multi-channel. For example, in the case of a 5.1CH multi-channel audio playback device, a center and left and right front speakers, left and right rear speakers, and a low-frequency woofer are provided, and an audio signal corresponding to the role of each output channel is provided. Processing, setting of speaker characteristics, and the like have been performed.

For example, in Patent Document 1, by changing the power supply voltage supplied to the audio amplifiers connected to the two speakers, the driving power of each audio amplifier can be changed, and the power distribution of the two speakers can be easily changed. The points that can be done are described. In Patent Document 2, the input impedance of the speaker is calculated, and the tap of the power transformer supplied to the amplifier circuit connected to the speaker is switched based on the calculation result, and the maximum volume according to the impedance of the speaker is automatically set. The point which can be obtained automatically is described. Further, in Patent Document 3, a power amplifier is configured such that a contact of a relay circuit is switched to connect a two-channel speaker and a power amplifier of any channel other than the two-channel system among multi-channels. It also describes that a relay circuit is provided between the speaker and the speaker, and the volume is reproduced and output even when a two-channel audio signal is reproduced.
JP 2001-177360 A JP 2003-52095 A JP 2002-27600 A

In the conventional audio reproduction apparatus, when the maximum output of each channel is different, for example, in 5.1CH, the output of the bass woofer is increased more than twice the output of other speakers to increase the volume. However, in this case, as shown in FIG. 4, the power supply voltage is supplied corresponding to each output. The power transformer 100 rectifies and supplies two power supply voltages V ₁ and V _{2. The} power supply voltage V ₁ is supplied to the amplifier 200 connected to the woofer 201, and the power supply voltage V ₂ is supplied to the woofer 201. Are supplied to amplifiers 300 to 304 connected to the other speakers 305 to 309, respectively. Since the power supply voltages V ₁ and V ₂ are set to different voltage values, two power supply circuits are required. Further, it is necessary to design the circuit arrangement and the like in an insulated state, which causes an increase in cost burden such as separately providing a circuit board or making an insulating state with an insulating sheet.

  In the above-mentioned prior art documents, the power supply voltage supplied to the audio amplifier of the output channel is changed to change the power distribution or to correspond to the impedance of the speaker, but all have complicated circuit configurations. However, an increase in cost is inevitable.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an audio reproducing apparatus that can cope with a case where the maximum output of each channel is different with a simple circuit configuration and can exhibit a conventional acoustic effect. It is.

  The audio reproduction device according to the present invention is an audio reproduction device that includes an audio amplifier and a speaker for each of a plurality of output channels, and is set so that the maximum output of at least one output channel is different. A single power supply circuit for supplying a power supply voltage is provided, and the impedance of the speaker is set corresponding to the maximum output of each output channel.

  Another audio reproduction apparatus according to the present invention is an audio reproduction apparatus that includes an audio amplifier and a speaker for each of a plurality of output channels and is set so that a maximum output of at least one output channel is different. A single power supply circuit for supplying the same power supply voltage to the amplifier is provided, and a plurality of audio amplifiers are connected to one speaker corresponding to the maximum output of the output channel.

  Furthermore, in the above audio reproducing apparatus, all of the audio amplifiers are attached to a common heat sink.

  By having the configuration as described above, the power supply circuit can be unified by supplying the same voltage to the audio amplifier of each output channel, and the entire circuit system related to the power supply is simplified. In other words, by reducing the number of parts by using a single power supply circuit that has conventionally been required to be provided, and by reducing the size of the power transformer, the use of thick windings improves regulation and improves sound quality. And transient response is improved.

  Since the same voltage is supplied to each audio amplifier, all the audio amplifiers can be mounted on one board, the board itself can be made compact, and only one heat dissipation structure can be attached to the board. Therefore, since the structure of the entire circuit system can be simplified, the cost can be reduced and the production efficiency can be improved.

  In addition, since the impedance of the speaker is set corresponding to the maximum output, for example, when it is desired to set the maximum output of the woofer speaker to a large value such as 5.1CH, the speaker having a smaller impedance than the other speakers. Is used, the maximum output is increased accordingly, and the sound quality of the speaker is maintained as before.

  When it is desired to set a large maximum output channel, a plurality of audio amplifiers can be connected to one speaker. That is, if a plurality of audio amplifiers to which the same voltage is supplied are provided, and two audio amplifiers are connected to a speaker of a certain output channel, for example, the maximum output is set to twice that of other output channels. Can do.

  Examples of the power supply circuit include a transformer power supply circuit and a switching power supply circuit, but the present invention is not limited to a specific power supply circuit.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  FIG. 1 shows an overall block diagram relating to an embodiment of the present invention. Audio signals include two-channel signals transmitted from TV, radio, VTR, etc., and multi-channel signals transmitted from DVD, CD, and the like. The two-channel signal is input to the surround processing circuit 12 by selecting one type of signal by the switching control of the control circuit 11 in the signal switching circuit 10. The surround processing circuit 12 performs signal processing corresponding to the multi-channel and inputs the signal to the switch circuit 13. The switch circuit 13 selects an audio signal from the surround processing circuit 12 or an audio signal input from a DVD or the like according to a switching control signal from the control circuit 11 and outputs the selected audio signal to the audio amplifier 14. A drive signal is output from the audio amplifier 14 to each of the speakers 15a to 15f, and audio is output.

  FIG. 2 is a circuit configuration diagram relating to a circuit for supplying power to the audio amplifier 14. The audio amplifier 14 is provided with six amplifiers 14a to 14f corresponding to each output channel, and is connected to the speakers 15a to 15f, respectively. The speaker 15a is a woofer speaker that outputs low sounds, the speakers 15b, 15c, and 15d are front center and left and right speakers, and the speakers 15e and 15f are rear left and right speakers.

  The power supply voltage Vcc obtained by transforming the output from the AC power source by one power transformer 20 and rectified by the rectifier circuit 21 is supplied to each of the audio amplifiers 14a to 14f. Therefore, the same voltage is supplied to each of the audio amplifiers 14a to 14f. The woofer speaker 15a is set to have a low impedance because the maximum output of the output channel needs to be larger than that of the other output channels. The woofer speaker outputs sound in the low sound region, but human hearing is insensitive to low sound output, so that the balance becomes poor unless the maximum output is increased compared to other speakers.

For example, the relationship among the maximum output Pmax of the audio output, the impedance R of the speaker, and the power supply voltage Vcc supplied to the audio amplifier is expressed by the following equation.
Pmax = Vcc ² / 8R
As a conventional example, in the example shown in FIG. 3, assuming that V ₁ = ± 37 V, V ₂ = ± 26 V, the impedance of the woofer 201 is 8Ω, and all the impedances of the speakers 305 to 309 are 8Ω, 2) ² / (8 × 8Ω) = 86W
The maximum output of the speakers 305 to 309 is
(26V × 2) ² / (8 × 8Ω) = 43W
Therefore, the total maximum output is
86W + 43W × 5 = 301W
It becomes. In order to maintain this conventional maximum output in the embodiment of FIG. 2, assuming that Vcc = ± 26 V, the impedance of the speaker 15a is 4Ω, and the impedances of the speakers 15b to 15f are all 8Ω,
The maximum output of the speaker 15a is (26V × 2) ² / (8 × 4Ω) = 85W
The maximum output of the speakers 305 to 309 is
(26V × 2) ² / (8 × 8Ω) = 43W
Therefore, the total maximum output is
85W + 43W × 5 = 300W
It becomes. Therefore, the conventional output channels can be set to be maintained as they are.

  FIG. 3 shows a modification of the embodiment described above. In this case, seven audio amplifiers 14a to 14g are provided as audio amplifiers. The sound amplifiers 14a and 14b are connected to the woofer speaker 15a, and the sound amplifiers 14c to 14g are connected to the speakers 15b to 15f, respectively. The audio amplifiers 14a to 14g are supplied with the voltage Vcc from a single power supply circuit. Since the woofer speaker 15a is input from the two audio amplifiers 14a and 14b, the maximum output can be set larger than that of the other speakers. Therefore, there are effects such as simplification of the power supply circuit as in the above-described embodiment.

  As described above, since the same power supply voltage is supplied to each audio amplifier, they are installed on the same substrate. A common heat radiating plate for radiating heat from all the audio amplifiers may be attached to the substrate. Therefore, an insulating structure such as an insulating sheet that must be provided when different voltages are supplied is not necessary. Since only one power supply circuit is required and a heat sink can be used in common, it is possible to reduce the number of components and the board area.

  In the above embodiment, the transformer power supply is described as an example of the power supply circuit, but the switching power supply can be used in the same manner.

It is a block block diagram regarding embodiment which concerns on this invention. It is a circuit diagram regarding the power supply circuit of embodiment which concerns on this invention. It is a circuit diagram which shows the modification of embodiment which concerns on this invention. It is a circuit diagram regarding the power supply circuit regarding a prior art example.

Explanation of symbols

10 Signal switching circuit
11 Control circuit
12 Surround processing circuit
13 Switch circuit
14 Audio amplifier
15 Speaker

Claims (3)

  In an audio reproducing apparatus including an audio amplifier and a speaker for each of a plurality of output channels and having a maximum output of at least one output channel set differently, a single power source that supplies the same power supply voltage to each of the audio amplifiers An audio reproducing apparatus comprising a circuit, wherein an impedance of a speaker is set corresponding to a maximum output of each output channel.   In an audio reproducing apparatus including an audio amplifier and a speaker for each of a plurality of output channels and having a maximum output of at least one output channel set differently, a single power source that supplies the same power supply voltage to each of the audio amplifiers An audio reproducing apparatus comprising a circuit, wherein a plurality of audio amplifiers are connected to one speaker in correspondence with a maximum output of an output channel.   The audio reproducing apparatus according to claim 1, wherein all of the audio amplifiers are attached to a common heat sink.

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