JPH06303718A - Heat radiator - Google Patents

Abstract

PURPOSE:To sense a malfunction of an air cooling fan with a simple circuit construction. CONSTITUTION:A terminal A of an air cooling fan is connected to an inverting input terminal (-) of a comparator 7 and a non-inverting input terminal (+) of a comparator 8. A first reference voltage VB is applied to the non-inverted input terminal (+) of the comparator 7, and a second reference voltage VC is applied to the inverted input terminal (-) of the comparator 8. When a fan 1 is mechanically locked to be stopped, the VA becomes '0'. When both the terminals of the fan are short-circuited, the VA becomes equal to Vcc. Accordingly, when a malfunction occurs in the fan 1, a logic level of a point E becomes '0', thereby stopping an operation of an inverter circuit 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipation device for radiating heat of an electronic device in a body of an electronic device by means of an air-cooling fan. The present invention relates to a heat dissipation device for prevention.

[0002]

2. Description of the Related Art Conventionally, an air-cooling fan is used to exhaust air in order to reduce the temperature rise of a heat-generating part inside an electronic device body, but the fan is mechanically stopped for some reason. As a protective measure against failure or disconnection of wiring, the presence or absence of current flowing in the fan is detected, and when the current stops flowing, the operation of the heat generating part inside the electronic device is stopped, and the abnormal temperature rise causes electronic device To protect the electronic components, or to detect the presence or absence of ripple components in the current that flows with the rotation of the fan, and if no ripple components are detected, stop the operation of the heat generating part inside the electronic device to prevent the abnormal temperature rise. We have adopted a method of protection.

[0003]

However, in the above-mentioned conventional method, the former method detects only the presence or absence of the current flowing through the fan, so that when the wiring of the fan is short-circuited or a circuit other than the fan is erroneously connected. In this case, the current continues to flow even though the fan stops and exhaust cannot be performed.Therefore, there is a problem that the protection circuit cannot detect an abnormality and the device cannot be prevented from being destroyed due to an abnormal temperature rise. It was

Further, in the latter case, since it is possible to detect the fan rotation abnormality by detecting the presence or absence of the ripple component of the current flowing with the rotation of the fan, when the wiring of the fan is short-circuited or by mistake, Even if the circuit is connected, the protection circuit has the advantage that the device can be prevented from being damaged due to an abnormal temperature rise.However, in general electronic devices, the customer does not need to connect the fan wiring, so There is no fear that other circuits will be connected, the performance is excessive, and a means to detect the presence or absence of ripple components of the current that flows with the rotation of the fan is required, and the configuration is more complicated than the former. There was a problem that became.

The present invention has been made in view of the above problems, and detects an abnormality such as a disconnection or a short circuit of an air-cooling fan with a simple structure to stop the operation of a heat-generating portion inside an electronic equipment main body. An object of the present invention is to provide a heat dissipation device that can protect electronic equipment from an abnormal temperature rise.

[0006]

In order to achieve the above object, the present invention provides an air-cooling fan for radiating heat of an electronic circuit in an electronic equipment main body and a current supplied to the fan from a power supply means. A second reference current that is less than or equal to a first reference current that is less than the minimum current supplied by the power supply means and that is greater than the maximum current supplied by the power supply means.
It has a current detecting means for outputting a signal when the current is equal to or more than the reference current, and a means for stopping the operation of the heat generating portion by the signal from the current detecting means.

[0007]

According to the present invention, when the value of the current flowing through the cooling fan is out of the predetermined range, the heat generation is stopped and protection is performed. Therefore, the electronic device is protected even when the wiring of the fan is broken or short-circuited. be able to.

[0008]

1 is an electric circuit diagram of a heat dissipation device in one embodiment of the present invention. In FIG. 1, reference numeral 1 is a fan for air cooling, 2 to 6 and 10 to 12 are resistors, 7 and 8 are comparator ICs as current detecting means, and an output circuit is an open collector circuit and a wired OR. It is connected. 9 is a photothyristor coupler, 9a is a light emitting diode, 9b is a light receiving diode, 13 is a capacitor, and 14 is AC.
The rectifying diode 15 for the power supply is an inverter circuit in the switching power supply device and has a control input terminal that stops its operation when the potential becomes high level.

Further, FIG. 2 shows operating voltage waveforms VA to VC, VE and VF at points A to C, E and F shown in FIG.

The operation of the heat dissipating device of this embodiment having the above structure will be described. First, the operation of the comparators 7 and 8 will be described. Non-inverting input terminal of comparator 7 +
And the inverting input terminal-of the comparator 8 has resistors 3 to
A voltage obtained by dividing the power supply voltage Vcc (+12 V) by 5 is applied. Therefore, the voltage at point B is VB (first
, And the voltage at point C is VC (second reference voltage), VB> VC. Further, the inverting input terminal − of the comparator 7 and the non-inverting input terminal + of the comparator 8 are connected to each other. The current flowing through the air-cooling fan 1 is converted into a voltage by the resistor 2 and applied here. This voltage is VA.

Here, how the state of the output terminals E of the comparators 7 and 8 changes depending on the magnitude relation between VA, VB and VC will be described.

First, the case of VB>VC> VA will be described. Focusing on the comparator 8, since the voltage VA of the non-inverting input terminal + is smaller than the voltage VC of the inverting input terminal −, the output of the comparator 8 becomes a logic level Low. Focusing on the comparator 7, the non-inverting input terminal +
Is higher than the voltage VA at the inverting input terminal-, the output of the comparator 8 becomes a logic level High. Here, since the output circuits of the comparators 7 and 8 are open collector circuits and are connected by wired OR, the point E becomes a logic level Low.

Next, the case of VB>VA> VC will be described. Focusing on the comparator 8, since the voltage VA of the non-inverting input terminal + is higher than the voltage VC of the inverting input terminal −, the output of the comparator 8 is a logic level High.
Becomes Focusing on the comparator 7, since the voltage VB of the non-inverting input terminal + is higher than the voltage VA of the inverting input terminal −, the output of the comparator 7 is a logic level High.
Becomes Here, since the output circuits of the comparators 7 and 8 are open collector circuits and are connected by wired OR, the point E becomes a logic level High.

The case of VA>VB> VC will be described. Focusing on the comparator 8, the non-inverting input terminal +
Is higher than the voltage VC at the inverting input terminal-, the output of the comparator 8 becomes a logic level High. Focusing on the comparator 7, the non-inverting input terminal +
Is smaller than the voltage VA at the inverting input terminal-, the output of the comparator 7 becomes a logic level Low. Here, since the output circuits of the comparators 7 and 8 are open collector circuits and are connected by wired OR, the point E becomes a logic level Low.

Here, since the current flowing in the normal state of the fan 1 for air cooling is a pulsating current, the voltage VA generated at the point A has a waveform as shown in FIG. Therefore, the voltage VC at the inverting input terminal − of the comparator 8 is 0V.
It is larger than the minimum value of the voltage at the point A in the normal state of the air cooling fan 1, and the voltage VB of the non-inverting input terminal + of the comparator 7 is the point A in the normal state of the air cooling fan 1. If the values of the resistors 3 to 5 are set so as to be larger than the maximum value of the voltage VA of VB>VA> VC described above.
Is the same as the case of, and the E point becomes the logic level High.

Next, the case where the air cooling fan 1 is mechanically locked will be described. In this case, the current flowing through the air-cooling fan 1 temporarily increases, but becomes approximately 0 after about 2 seconds. Therefore, the voltage generated at the point A temporarily increases for about 2 seconds as shown in FIG. 2 (2). It will be almost 0 later. When the air-cooling fan 1 is not connected (including disconnection), no current flows, so the voltage generated at the point A becomes zero. These states correspond to the case of VB>VC> VA described above,
The point E becomes the logic level Low.

Next, when the terminals D and A of the air-cooling fan 1 are short-circuited, it becomes as shown in FIG. 2 (3). In this case, the voltage VA at the point A rises to almost the power supply voltage Vcc. This state corresponds to the case of VA>VB> VC described above, and the point E becomes the logic level Low.

As described above, at the point E, when the air-cooling fan 1 is normal as shown in FIG. 2 (1), the logic level becomes High, and no current flows through the light emitting diode 9a of the photothyristor coupler 9, but FIG. In the abnormal states (mechanical lock, disconnection, short circuit) shown in (2) and (3), the point E becomes a logic level Low, and a current flows through the light emitting diode 9a of the photothyristor coupler 9 through the resistor 6.

In the photothyristor coupler 9, when a current flows through the light emitting diode 9a, the light receiving diode 9b senses light, and the thyristor is turned on via the control input terminal (point F) of the inverter circuit 15 coupled by the light. Arc (voltage VF)
It is made conductive. Therefore, when the fan 1 for air cooling is in an abnormal state, the thyristor is ignited and brought into conduction. AC (100V AC) is a diode 14 in the capacitor 13.
Although the DC voltage rectified by the thyristor is applied, the voltage divided by the thyristor and the resistors 10 and 12 in the conductive state is applied to the control input terminal (point F) of the inverter circuit 15 as shown in FIG. Is applied. Therefore, the inverter circuit 15 stops the switching operation and stops the supply of electric power (DC output: 12 etc) to the electronic device body. Also, heat generation due to the switching operation is stopped.

In this embodiment, the method of protecting the apparatus from abnormal temperature rise by stopping only the power supply operation of the electronic device when the air cooling fan has an abnormality has been described. For example, the output signal from the protection circuit of the present invention is used to stop the power supply to the heat generating section inside the electronic device other than the power source section, or switch to the low power consumption state to suppress the heat generation of the device and prevent the destruction. The application of doing is also possible.

[0021]

As described above, the heat dissipation device of the present invention detects an abnormality such as a disconnection or a short circuit of an air-cooling fan with a simple structure and stops the operation of the heat generating portion inside the electronic device to cause an abnormal condition. The electronic device can be protected from the temperature rise.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a heat dissipation device according to an embodiment of the present invention.

FIG. 2 is an operating voltage waveform diagram of each part in FIG.

[Explanation of symbols]

1 ... Fan for air cooling, 7, 8 ... Comparator IC,
9 ... Photothyristor coupler, 9a ... Light emitting diode,
9b ... Light receiving diode, 13 ... Capacitor, 14 ... Rectifying diode, 15 ... Inverter circuit.

Claims (1)

[Claims] 1. An air-cooling fan for radiating heat of an electronic circuit in an electronic equipment body, and a current supplied from a power supply means to the fan is smaller than a minimum current supplied from the power supply means. A current detecting unit that outputs a signal when the current is less than or equal to a first reference current and a second reference current that is greater than a maximum current supplied from the power supply unit, and a heating unit by a signal from the current detecting unit A heat dissipation device having means for stopping the operation of.