JPH04208703A - Cooling device for amplifier - Google Patents

Abstract

PURPOSE:To reduce the rotation sounds and whistling of a cooling fan and to suppress the rise of temperature in an enclosure by driving a motor at a rotating speed lower than a prescribed value in the case of the output level lower than a prescribed level. CONSTITUTION:When the output level of an output amplifier 2 is lower than a set prescribed level, a transistor TR Q3 of an intermittent driving control circuit 13 is intermittently turned on/off at the time of output of intermittent pulses from a terminal 12a of a microcomputer 12. Only when the TR Q3 is turned on, the operation of a constant voltage circuit 11 is turned on to supply about 2V power to a motor 6, and the motor 6 is driven at a rotating speed lower than a prescribed value. Thus, the cooling fan is intermittently rotated at the rotating speed lower than the prescribed value to cool the output amplifier 2.

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amplifier cooling device for suppressing a temperature rise within a housing of an output amplifier of an audio device.

00O2]

[Prior Art] In recent years, although there has been a trend toward miniaturization of audio equipment, the output has been large, and the heat generated by the amplifiers has caused a problem of temperature rise inside the amplifier housing, so amplifier cooling devices such as cooling fans have been required. Generally used. [00031] An example of the above-mentioned conventional amplifier cooling device will be described below with reference to the drawings. [00041] FIG. 2 is a circuit diagram showing the configuration of a conventional amplifier cooling device. In FIG. 2, 1 is an audio signal source such as a tuner, cassette deck, CD, etc., and 2 is an output amplifier that amplifies the signal from the audio signal source 1 and drives a speaker 3. 4 is a rectifier diode D1 and a resistor R1
This is a level detector that detects the output level of the output amplifier 2 that is input via the resistor R2, the diode D2, the capacitor CI, and the transistor Q1. 5 is a motor drive circuit that receives the output of the level detector 4 and drives the motor 6 of the cooling fan that cools the output amplifier 2;
It consists of resistors R3 and R4, a transistor Q2, and a Zener diode D3. [0005] The operation of the above configuration will be explained below. When the level detector 4 detects the output level of the output amplifier 2 and the output level exceeds the set level, the transistor Q1 becomes conductive and the transistor Q2 of the motor drive circuit 5 becomes conductive.
The motor 6 is driven by supplying power to the motor 6 by making it conductive. As a result, the cooling fan rotates and the output amplifier 2 can be cooled. In this example, the output of the motor drive circuit 5 is supplied to the motor 6 with a voltage fixed at about 5 to 1000 volts by the Zener diode D3, and is driven at a predetermined rotational speed. [0006]

However, in the conventional amplifier cooling device as described above, when the output level of the output amplifier 2 is below the level set by the level detector 4, the cooling device does not operate, and the output amplifier Since the casing of the output amplifier 2 is small, there is a problem in that the output amplifier becomes abnormally hot even when the output amplifier 2 has a small output. Furthermore, in order to solve this problem, if the setting level of the detector 4 is lowered so that the cooling fan operates even when the output is small, there is a problem in that the rotation sound of the cooling fan and the wind noise become unpleasant to the ears. [0007] In view of the above-mentioned conventional problems, the present invention has been made with the object of providing an amplifier cooling device that can be effectively used even in the case of an output amplifier of a small audio device having a small housing. be. [0008]

[Means for Solving the Problems] In order to solve the above problems, the amplifier cooling device of the present invention is a cooling device that suppresses the temperature rise in the housing of an output amplifier of an audio device, and is a cooling device that suppresses the temperature rise inside the housing of an output amplifier of an audio device. an output amplifier that amplifies and drives a speaker, a motor equipped with a cooling fan that can cool the output amplifier, and a level detector that detects that the output level of the output amplifier is equal to or higher than a predetermined level. a first motor drive circuit that drives the motor at a predetermined rotational speed when the level detector detects that the output level of the output amplifier is equal to or higher than a predetermined level; and a second motor drive circuit that drives the motor at a rotation speed lower than the predetermined rotation speed when the rotation speed is lower than the predetermined rotation speed. [0009]

[Operation] According to the above-described structure, the present invention includes a second motor drive circuit that drives the motor at a rotation speed lower than the predetermined rotation speed when the output level of the output amplifier is lower than the predetermined level. As a result, the cooling fan can be driven even when the output is low, so even if the case is an output amplifier for a small audio device, the temperature rise in the case can be suppressed, and the rotation noise and wind noise of the cooling fan can be suppressed. It is something that will never happen. [00101

[Embodiment] Hereinafter, an embodiment of the amplifier cooling device of the present invention will be described in detail with reference to FIG. [00111 FIG. 1 is a circuit diagram showing the configuration of an amplifier cooling device in an embodiment of the present invention. [0012] Note that the same numbers are given to the configurations of the same parts as in the conventional example, and detailed explanations are omitted. In FIG. 1, 11 is a constant voltage circuit;
It is composed of resistors R8, R9, RIO, a diode D5, a Zener diode D4, a transistor Q4, and a capacitor C3°C4, and an output voltage of about 2V is supplied to the motor 6. Further, 12 is a microcomputer, which outputs intermittent pulses as shown in the figure to a terminal 12a. 13 is microcomputer 12
This is an intermittent drive control circuit that intermittently turns on and off the operation of the constant voltage circuit 11 in response to intermittent pulses that are the output of the circuit, and is composed of resistors R5, R6, R7, a transistor Q3, and a capacitor C2. Note that the constant voltage circuit 11 may be turned on intermittently,
The off timing can be arbitrarily set by the microcomputer 12 and the intermittent drive control circuit 13, and for example, the on time can be set to about 10 seconds and the off time can be set to about 30 seconds. [00141 The operation of the amplifier cooling device of the present invention configured as described above will be described below. [0015] First, when the output level of the output amplifier 2 is above a predetermined level, the level detector 4 detects the output level of the output amplifier 2, and when it becomes above the set level, as in the conventional example. Transistor Q1 conducts, transistor Q2 of motor drive circuit 5 conducts, and power of about 5V is supplied to motor 6, so that motor 6 is driven at a predetermined rotational speed. [0016] Thereby, the cooling fan rotates at a predetermined rotational speed, and the output amplifier 2 can be cooled. [0017] Next, when the output level of the output amplifier 2 is lower than the predetermined level, the terminal 1 of the microcomputer 12
When an intermittent pulse is output from 2a, the intermittent drive control circuit 1
Transistor Q3 of No. 3 is intermittently turned on and off. Then, the constant voltage circuit 11 is
is turned on, and approximately 2 cm of power is supplied to the motor 6, so that the motor 6 is driven at a rotation speed slower than the predetermined rotation speed.

As a result, the cooling fan rotates intermittently at a rotation speed slower than a predetermined rotation speed, and the output amplifier 2 can be cooled. [0019] As described above, according to this embodiment, even when the output level of the output amplifier 2 is lower than a predetermined level, a power lower than the predetermined voltage is supplied to the motor 6 so that the motor 6 maintains the predetermined level. By being driven at a rotational speed slower than the rotational speed of the cooling fan, the output amplifier 2 can be cooled by reducing the rotational noise and wind noise of the cooling fan, thereby suppressing the temperature rise inside the output amplifier housing. . Furthermore, intermittent driving of the cooling fan can extend the life of the motor compared to continuous driving. [00201] [Effects of the Invention] As described above, the present invention provides a cooling device for suppressing the temperature rise inside the housing of an output amplifier of an audio device, which is an output amplifier that amplifies a signal from an audio signal source to drive a speaker. a motor equipped with a cooling fan that can cool the output amplifier; a level detector that detects that the output level of the output amplifier is equal to or higher than a predetermined level; a first motor drive circuit that drives the motor at a predetermined rotational speed when an output level is detected to be equal to or higher than a predetermined level; By being equipped with a second motor drive circuit that drives at a rotation speed slower than the predetermined rotation speed, the cooling fan can be driven even when the output is low, so even if the case is a small output amplifier for a small audio device, the case can be easily used. It is possible to provide an amplifier cooling device capable of suppressing a rise in body temperature and in which the rotation sound of a cooling fan and wind noise do not become unpleasant to the ears.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an amplifier cooling device in an embodiment of the present invention.

[Fig. 2] A circuit diagram showing the configuration of a conventional amplifier cooling device.

[Figure 1]

Claims (2)

[Claims] 1. A cooling device for suppressing a temperature rise in a housing of an output amplifier of an audio device, comprising: an output amplifier that amplifies a signal from an audio signal source to drive a speaker; and a cooling device for cooling the output amplifier. a motor equipped with a cooling fan capable of controlling the output power, a level detector that detects that the output level of the output amplifier is at least a predetermined level, and a level detector that detects that the output level of the output amplifier is at least the predetermined level. a first motor drive circuit that drives the motor at a predetermined rotational speed when detecting the motor, and a first motor drive circuit that drives the motor at a rotational speed slower than the predetermined rotational speed when the output level of the output amplifier is lower than the predetermined level. 1. A cooling device for an amplifier, comprising: a second motor drive circuit. 2. The amplifier cooling device according to claim 1, further comprising an intermittent drive control circuit that intermittently outputs the output of the second motor drive circuit.