JP4016451B2 - Cooling device for audio playback device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cooling device in an audio playback device.
[0002]
[Prior art]
In audio playback devices, the greater the output of an amplifier that plays music, etc., the better the playback capability, and the greater the margin that the speaker can be driven. Etc. become large, and there is a problem that the audio reproducing apparatus becomes large.
[0003]
In order to solve this problem, recently, there is a fan equipped with a fan for cooling the heat sink of the amplifier. In this case, even if the output of the amplifier is increased, there is an advantage that the heat sink can be reduced in size and the audio reproduction apparatus can be reduced in size. However, the noise of the fan becomes a problem, and particularly in the case of delicate music reproduction.
[0004]
To solve this problem, the temperature (heat) of the heat sink is detected and the fan is stopped when the temperature is low, or the output signal level of the amplifier is detected and the signal level is below the set level. Sometimes, a method of stopping the fan has been proposed.
[0005]
However, with the former method, there is a problem that the time delay of temperature detection is very large and the fan is driven for a considerable period of time even if the volume is low after playback at a high volume. It was.
On the other hand, in the latter method, when only headphones are used instead of speakers, the headphone speakers are used even when the output signal level of the amplifier increases and exceeds the set level of the signal level detection circuit. Since the resistor is connected in series to the (load) and the impedance is large, the output current of the amplifier is small and the amplifier does not generate much heat, but the fan is driven and the silence is broken in the above case There was a problem with.
[0006]
[Problems to be solved by the invention]
It is an object of the present invention to provide a cooling device in an audio playback device that can solve the above-described problems.
[0007]
[Means for Solving the Problems]
To achieve the above object, it is an aspect of the present invention, the amplifier, through the speaker driving switch, a speaker is connected to the connection point of the amplifier and the loudspeaker drive switch, the output terminal is connected for headphones The input terminal of the headphone can be intermittently connected to the output terminal, and the fan that cools the heat sink of the amplifier and the fan drive circuit are provided. The fan drive circuit is provided with a fan drive switch. The speaker drive switch and the fan drive switch are turned off in conjunction with the connection operation of the headphone input terminal to the output terminal, and both the switches are turned on in conjunction with the input terminal cutoff operation to the output terminal. In some cases, interlocking means is provided.
Furthermore, the interlocking means is a . Interlocking means for a speaker drive switch for operating the speaker drive switch ; There may be a fan drive switch interlocking means for operating the fan drive switch.
In addition, the fan drive circuit may be provided with a signal level detection circuit that allows power to be supplied to the fan only when the level of the output signal of the amplifier exceeds a set level.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a comparative example of the present invention will be described with reference to the drawing of FIG. 1. Left and right input terminals 1L and 1R have left and right power amplifiers (low frequency amplifiers) 2L and 2R, speaker drive switches 3L and open / close switches, 3R, (loud) speakers 4L and 4R are connected in the above order. The amplifiers 2L and 2R are composed of power transistors and the like. Headphone output terminals 5L and 5R are connected to connection points between the amplifiers 2L and 2R and the speaker drive switches 3L and 3R via resistors 22L and 22R, respectively. The output terminals 5L and 5R, the ground terminal 6 and the like constitute a headphone jack ((connected) connection portion) 7.
[0009]
A headphone 9 includes a pair of left and right speakers 10L and 10R, input terminals 11L and 11R, a ground terminal 12, and the like. A plug (connection portion) 13 is configured by the terminals 11L, 11R, and 12; Since the plug 13 can be connected to and disconnected from the headphone jack 7, the input terminals 11 </ b> L and 11 </ b> R and the ground terminal 12 of the headphone 9 can be intermittently connected to the headphone output terminals 5 </ b> L and 5 </ b> R and the ground terminal 6. Has been.
[0010]
A fan 16 is connected to a connection point between each amplifier 2L, 2R and each speaker drive switch 3L, 3R via a fan drive circuit 15, and the fan 16 cools the heat sink 8 of the amplifier 2L, 2R. The fan drive circuit 15 includes a signal level detection circuit 17, a fan drive switch 18, and a power source.
[0011]
The signal level detection circuit 17 allows the power supply to the fan 16 only when the level of the output signal of the amplifiers 2L and 2R exceeds the set level, and is configured as follows. That is, one end of resistors 19L and 19R is connected to the connection point between each amplifier 2L and 2R and each speaker drive switch 3L and 3R, and the other end of these resistors 19L and 19R is connected to each other. The diode D1 is connected to the base of the (switching) transistor T1. The connection point between the resistors 19L and 19R and the diode D1 is grounded via the resistor 20, and the connection point between the diode D1 and the transistor T1 is grounded via the diode D2 and the electrolytic capacitor C connected in parallel. . The emitter of the transistor T1 is grounded, and a positive voltage (power supply) + B is applied to its collector via a resistor 21. The base of the transistor T2 is connected to the connection point between the collector of the transistor T1 and the resistor 21, the positive voltage + B is applied to the emitter, and the fan drive switch 18 is connected to the collector. .
[0012]
The fan drive switch 18 is an open / close switch and mechanically interlocks with the speaker drive switches 3L and 3R. When the speaker drive switches 3L and 3R are turned on, the fan drive switch 18 is turned on and the speaker drive switches 3L and 3R are turned on. During the turning-off operation, the fan drive switch 18 is turned off. Thus, the fan drive switch 18 can be automatically turned on / off simply by turning on / off the speaker drive switches 3L, 3R, and the operation is simple.
[0013]
According to the comparative example, during audio reproduction by using the speakers 4L and 4R, the speaker drive switches 3L and 3R are turned on, and the fan drive switch 18 is turned on in conjunction with this. Further, the plug 13 of the headphone 9 is separated from the headphone jack 7, and the input terminals 11L and 11R and the ground terminal 12 of the headphone 9 are disconnected (separated) from the headphone output terminals 5L and 5R and the ground terminal 6. It is said that.
[0014]
When an acoustic signal is input to the input terminals 1L and 1R in the above state, the acoustic signal is amplified by the amplifiers 2L and 2R and supplied to the speakers 4L and 4R via the speaker drive switches 3L and 3R. The speakers 4L and 4R are driven to perform audio reproduction.
[0015]
Incidentally, the level of the output signal of each amplifier 2L, 2R is detected by the signal level detection circuit 17 as follows. That is, the output signals of the amplifiers 2L and 2R are attenuated to the set level by the resistors 19L and 19R, then rectified and smoothed to direct current by the diodes D1 and D2 and the capacitor C, and input to the base of the transistor T1. The When the level of the output signal of each amplifier 2L, 2R is equal to or lower than the set level, the voltage applied to the base of the transistor T1 is equal to or lower than the set voltage (for example, 0.6 V or lower), and the transistor T1 is turned off. Accordingly, the transistor T2 in the next stage is also turned off, and power supply to the fan 16 is blocked.
[0016]
When the level of the output signal of each amplifier 2L, 2R exceeds the set level, the voltage applied to the base of the transistor T1 exceeds the set voltage, the transistor T1 is turned on, and the transistor T2 in the next stage is also turned on. The power supply to the fan 16 is allowed. Since the fan drive switch 18 is on, power is supplied to the fan 16, the fan 16 is rotationally driven, and the heat sink 8 of the amplifiers 2L and 2R is cooled. Thus, since the heat sink 8 can be cooled by the fan 16, even if the outputs of the amplifiers 2L and 2R are increased, the heat sink 8 can be reduced in size, and the audio reproducing apparatus can be reduced in size.
[0017]
On the other hand, when audio is played back by using the headphone 9, the plug 13 of the headphone 9 is connected to the headphone jack 7, and the terminals 11L, 11R, 12 of the headphone 9 are connected to the headphone output terminals 5L, 5R and the ground terminal 6. Is done. In addition, the speaker drive switches 3L and 3R are turned off, and in conjunction with this, the fan drive switch 18 is turned off.
[0018]
When an acoustic signal is input to each of the input terminals 1L and 1R in the above state, the acoustic signal is amplified by the amplifiers 2L and 2R, and each speaker 10L of the headphone 9 is passed through the headphone jack 7 and the headphone plug 13. , 10R, the speakers 10L, 10R are driven, and audio reproduction is performed.
[0019]
By the way, when the headphone 9 is used, the output signal is reproduced through (via) the large series resistors 22L and 22R even when the level of the output signal of the amplifiers 2L and 2R is the same as that of the audio reproduction by using the speakers 4L and 4R. Therefore, the output currents of the amplifiers 2L and 2R are smaller than those at the time of reproduction, and the amplifiers 2L and 2R generate little heat. However, sometimes the level of the output signal becomes higher than the set level of the signal level detection circuit 17. In this case, the transistors T1 and T2 of the signal level detection circuit 17 are turned on, and power supply to the fan 16 is allowed. However, as described above, since the fan drive switch 18 is in the off state, the fan 16 is not driven and the silence is not broken.
[0020]
FIG. 2 shows an example of an embodiment of the present invention, in which speaker driving is performed in conjunction with the intermittent operation of the input terminals 11L and 11R and the ground terminal 12 of the headphone 9 with respect to the headphone output terminals 5L and 5R and the ground terminal 6. Interlocking means 25 for turning on / off the switches 3L and 3R and the fan drive switch 18 is provided. As described above, in the second example, the speaker drive switches 3L and 3R and the fan drive switch 18 can be automatically turned on / off by the intermittent operation of the input terminals 11L and 11R of the headphones 9 and the operation is simple. . In the second example, the interlocking means 25 includes a speaker drive switch interlocking means 26 and a fan drive switch interlocking means 27.
[0021]
The speaker drive switch interlocking means 26 turns off the speaker drive switches 3L and 3R in conjunction with the connection operation of the input terminals 11L and 11R of the headphone 9 to the headphone output terminals 5L and 5R, and outputs the output. The speaker drive switches 3L and 3R are turned on by operating the terminals 5L and 5R etc. to shut off the input terminals 11L and 11R (connection cutoff and disconnection). Specifically, the speaker drive switches 3L and 3R A positive contact + B is applied to one end of the relay coil 30 of the output relay 29 as a relay contact of the output relay 29. The headphone jack 7 is provided with an interlocking switch 31, which has a contact 32 and an interlocking part 33, and the other end of the relay coil 30 is connected via the contact 32. Is grounded. The interlocking unit 33 opens and closes the contact 32 in conjunction with the insertion / removal operation of the plug 13 of the headphone 9 with respect to the headphone jack 7, and when the plug 13 is inserted into the jack 7, the contact 32 is turned off. When the plug 13 is separated from the jack 7, the contact 32 is turned on.
[0022]
The fan drive switch interlocking means 27 turns off the fan drive switch 18 in conjunction with the operation of connecting the input terminals 11L, 11R, etc. of the headphones 9 to the headphone output terminals 5L, 5R, etc. , 5R, etc., to turn on the fan drive switch 18 by shutting off the input terminals 11L, 11R, etc. Specifically, the fan drive switch 18 is provided in the headphone jack 7, and the contact 34, The fan drive circuit 15 is provided with an interlocking portion 35 and a contact 34. Similarly to the above, the interlocking unit 35 opens and closes the contact 34 in conjunction with the insertion / removal operation of the plug 13 of the headphone 9 with respect to the headphone jack 7, and turns off the contact 34 when the plug 13 is inserted into the jack 7. In operation, when the plug 13 is separated from the jack 7, the contact 34 is turned on.
[0023]
According to the above configuration example, when audio is reproduced by using the speakers 4L and 4R, the plug 13 of the headphone 9 is separated from the headphone jack 7, the contact 32 of the interlocking switch 31 is turned on, and the relay coil 30 is connected. Power is supplied, the speaker drive switches 3L and 3R are turned on, and the contact 34 of the fan drive switch 18 is also turned on.
[0024]
In this state, when an acoustic signal is input to the input terminals 1L and 1R, the speakers 4L and 4R are driven to perform audio reproduction, and the levels of the output signals of the amplifiers 2L and 2R are detected by the signal level detection circuit 17. When the level exceeds the set level, the fan 16 is rotationally driven and the heat sink 8 is cooled in the same manner as in the first example.
[0025]
When audio is played back by using the headphones 9, the plug 13 of the headphones 9 is connected to the headphone jack 7. As a result, the interlocking portion 33 of the interlocking switch 31 is activated, the contact 32 is turned off, the power supply to the relay coil 30 is stopped, the speaker drive switches 3L and 3R are turned off, and the fan drive switch 18 is operated. The interlocking portion 35 is also operated, and the contact 34 is turned off.
[0026]
In this state, when an acoustic signal is input to the input terminals 1L and 1R, the speakers 10L and 10R of the headphone 9 are driven and audio reproduction is performed. Further, when the level of the output signal of the amplifiers 2L and 2R becomes equal to or higher than the set level of the signal level detection circuit 17, power supply to the fan 16 is permitted, but the contact 34 of the fan drive switch 18 is in an off state. The fan 16 is not rotationally driven and the silence is not broken.
[0027]
【The invention's effect】
As described above in detail, according to the present invention, in use of headphones, the fan is not driven, the co if never silence is broken only intermittently operating the input terminal of the F Ddofon output terminal headphone Thus, the speaker drive switch and the fan drive switch can be automatically turned on / off, and the operation is simple.
[0028]
Furthermore, according to the third aspect of the present invention, the fan drive can be controlled according to the level of the output signal of the amplifier when the speaker is driven, and there is no possibility that the noise of the fan becomes an obstacle when reproducing a small volume.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a comparative example of the present invention.
FIG. 2 is a circuit diagram showing an example of an embodiment of the present invention.
[Explanation of symbols]
2L, 2R Power amplifier 3L, 3R Speaker drive switch 4L, 4R Speaker 5L, 5R Headphone output terminal 7 Headphone jack 8 Heat sink 9 Headphone 11L, 11R Input terminal 13 Plug 15 Fan drive circuit 16 Fan 17 Signal level detection circuit 18 Fan Driving switch 25 Interlocking means 26 Speaker driving switch interlocking means 27 Fan driving switch interlocking means

Claims (2)

A speaker is connected to the amplifier via a speaker drive switch,
The headphone output terminal is connected to the connection point between the amplifier and the speaker drive switch,
The input terminal of the headphones can be intermittently connected to the output terminal,
With a fan that cools the heat sink of the amplifier and a fan drive circuit,
The fan drive circuit is
A power supply path for supplying power from the power source to the fan via the headphone output terminal;
Switch means for allowing or preventing power supply from the power source to the fan in the power supply path;
A signal level detection circuit that turns on the switch means to allow power supply to the fan only when the level of the output signal of the amplifier is equal to or higher than a set level;
A fan drive switch that is included in the headphone output terminal and that allows or blocks power supply to the fan ;
Included in the output terminal for the headphone, to the output terminal for the headphone, in conjunction with the connection operation of the input terminals of the headphones, while turned off the speaker drive switch and the fan drive switch, to the output terminal for the headphone And an interlocking means for turning on the speaker drive switch and the fan drive switch in conjunction with the shut-off operation of the input terminal of the headphones ,
When the headphone input terminal is connected to the headphone output terminal, the fan driving switch is turned off by the interlocking means, so that the fan is connected to the fan regardless of the level of the output signal of the amplifier. Power supply is blocked,
When the headphone input terminal is cut off from the headphone output terminal, the fan drive switch is turned on by the interlocking means to allow power supply to the fan, and the output signal of the amplifier When the level exceeds a set level, the signal level detection circuit turns on the switch means to allow power supply to the fan, and the signal level detection circuit detects that the level of the output signal of the amplifier is higher than the set level. If not, the cooling device in the audio reproducing apparatus is configured to turn off the switch means to prevent power supply to the fan . The interlocking means,
And interlocking means for driving the speaker switch to operate the speaker drive switch,
Cooling device in the audio reproducing apparatus according to claim 1 having an interlocking means for a fan drive switch for operating the fan drive switch.

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