JPH0531329U - Power amplifier - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a highly reliable device for suppressing the temperature rise of the power amplifying device used for an audio amplifier or the like. [Structure] A power amplifier device in which the temperature detector 5 is attached to a power transformer 8 and the power of the output stage 3 is controlled by the output of the temperature detector 5, thereby suppressing the temperature rise of the device. [Effect] By attaching the temperature detector to the power transformer with large heat capacity and slow temperature rise, the temperature protection function does not operate during normal use, but operates only during marginal use to protect the device.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a power amplification device used for an amplifier of an audio device.

[0002]

[Prior Art]

 2. Description of the Related Art In recent years, power amplifiers used for amplifiers and the like of audio devices have been increased in output.

An example of the above-described conventional power amplification device will be described below with reference to the drawings. FIG. 3 shows a block diagram of a conventional power amplifier. In FIG. 3, 1 is an input terminal, 2 is a voltage amplification stage, 3 is an output stage, 4 is an output terminal, 5 is a temperature detector attached to the heat sink of the output stage 3, 6 is an attenuator, and 7 is the above temperature. Control means 8 controls the attenuator 6 according to the temperature of the detector 5, and 8 is a power transformer.

As the output increases, the power loss of the output stage 3 increases and the temperature of the radiator rises. This is detected by the temperature detector 5 and the attenuator 6 is operated through the control means 7. As a result, the input signal is attenuated, the output is reduced, and the temperature rise of the device is suppressed.

[0005]

[Problems to be solved by the device]

 However, in the conventional power amplification device as described above, temperature detection is performed by the radiator of the output stage 3, and therefore the loss of the output stage of the commonly used class B power amplification device is shown in FIG. As shown in Fig. 6, there is little difference between the medium output and the maximum output, and it is not possible to distinguish between normal use and abnormal use such as continuous maximum output for a long time, and the output stage can be protected due to an increase in ambient temperature. However, the power transformer cannot be protected against abnormal use as described above, and if the detection temperature is lowered for this reason, the temperature protection will operate easily even in normal use and the output will drop, resulting in the inability to achieve the original performance of the device. Had problems.

In view of the above-mentioned conventional problems, the present invention has been made for the purpose of providing a highly reliable power amplification device in which the temperature protection function does not operate in normal use but operates only in abnormal use. Is.

[0007]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the power amplification device of the present invention comprises a power transformer equipped with a temperature detector, control means for switching the power supply voltage according to the signal of the temperature detector, and voltage switching means. To do.

[0008]

[Action]

 Due to the above-mentioned configuration, the temperature of the power transformer rises at the time of continuous maximum output for a long time, and the power supply voltage is switched by the signal of the temperature detector attached to this to lower the power voltage than usual, thereby significantly reducing the loss in the output stage. It is possible to prevent damage to the equipment by lowering the temperature of the power transformer and suppressing the temperature rise. Furthermore, in normal use, the temperature of the power transformer rises and the protective device does not operate. In addition, since the power transformer has a large heat capacity, the protective device does not operate even with a large output for a short time, and there is no problem in actual use, and the protective device operates properly in the event of an abnormality and enhances the reliability of the device.

[0009]

【Example】

 Hereinafter, an embodiment of the power amplifier device of the present invention will be described in detail with reference to FIGS.

FIG. 1 is a block diagram of a power amplification device according to an embodiment of the present invention. In FIG. 1, 1 is an input terminal, 2 is a voltage amplification stage, 3 is an output stage, 4 is an output terminal, 5 is a temperature detector attached to a power transformer, and 7 is a temperature of the temperature detector 5 described later. Is a power supply transformer, and 9 is a voltage switching means that can be controlled by the control means 7.

The operation of the power amplifier configured as above will be described below.

First, during normal use, the temperature of the power supply transformer 8 does not rise so much, the power supply voltage is normal, and the rated output is obtained. Next, at the time of continuous high output for a long time, the temperature of the power supply transformer 8 rises, the control means 7 detects the signal of the temperature detector 5, and controls the voltage switching means 9 to lower the power supply voltage. As a result, the power loss of the power amplifier is reduced, the temperature rise of the power transformer 8 is suppressed, and the device can be prevented from being destroyed. In addition, as shown in Fig. 2, the temperature rise of the power transformer is relatively gentle compared to the radiator in the output stage, so the protective device will not operate when used at high output for a short time, and in actual use You can maximize the performance of the power amplifier.

As described above, according to the present embodiment, the temperature of the power transformer is detected and the power voltage is controlled, so that the performance of the device can be maximized in the normal use, and it is possible to obtain a high output for a long time. The protective device can be operated properly during abnormal use.

[0014]

[Effect of the device]

 As described above, according to the present invention, the temperature protection device does not operate in the actual use where a high output is required for a short time by mounting the temperature detector on the power transformer whose temperature rises slowly and controlling the power supply voltage. Can maximize the performance of. In addition, even during abnormal use where high output continues for a long time, the maximum output can be reduced slightly, and the temperature rise of the device can be suppressed and destruction can be prevented. Furthermore, even in the case of a speaker connected to the output of this power amplifier, it is possible to prevent the speaker from being destroyed due to a decrease in the maximum output during a long period of high output. As described above, according to the present invention, an excellent and highly reliable power amplification device capable of maximizing the performance of the device even in actual use, accurately protecting the temperature including the speaker connected in the event of abnormalities, and preventing damage can be obtained. Can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a power amplification device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a temperature rise curve of a power transformer and a temperature rise curve of a radiator at an output stage in a general power amplification device.

FIG. 3 is a block diagram of a conventional power amplification device.

FIG. 4 is a diagram showing a relationship between output and power loss in a class B output stage of the power amplifier.

[Explanation of symbols]

 1 Input Terminal 2 Voltage Amplifying Stage 3 Output Stage 4 Output Terminal 5 Temperature Detector 6 Attenuator 7 Control Means 8 Power Transformer 9 Voltage Switching Means

Claims (1)

[Scope of utility model registration request] 1. A power amplification device comprising: a power supply transformer equipped with a temperature detector; control means for switching a power supply voltage according to a signal from the temperature detector; and voltage switching means.