JP2000083319A - Power source unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized power source unit at low cost which has a protective means for preventing heating which is superior in temperature detecting sensitivity. SOLUTION: A power source circuit 10 is formed on the surface of an alumina ceramic board whose thermal conductivity is high, and a temperature sensor S1 is arranged on the back of the board. A choke coil L, a diode D and a transistor Tr1 whose heating values are large are arranged adjacently to each other, and the temperature sensor S1 is set at a position facing these heat generating components. When the detected temperature of the temperature sensor S1 exceeds a specified value, the output of the transistor Tr1 is cut off with a control circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a power supply device,
In particular, the present invention relates to a power supply device having a heating prevention unit.

[0002]

2. Description of the Related Art FIG. 1 shows a power supply device provided with a DC-DC converter according to the present invention.

In FIG. 1, reference numeral S1 denotes a temperature sensor, which comprises, for example, a thermistor. Reference numeral 10 denotes a power supply circuit including a DC-DC converter, which includes a choke coil L, a diode D,
It comprises a capacitor C, an NPN transistor Tr1, and a control circuit 11 for controlling the switching operation of the transistor Tr1.

One end of the choke coil L is an input terminal.
The other end is connected to the anode of the diode D and the collector of the transistor Tr1. Diode D
Is connected to the output terminal OUT and grounded via the capacitor C. Also, the transistor Tr
One emitter is grounded, and a control signal output from the control circuit 11 is input to the base.

Further, a temperature sensor S1 is connected to the control circuit 11.

The control circuit 11 is operated by a DC power supply from an input terminal IN, and switches on and off the transistor Tr1 at a predetermined cycle.

As a result, the current output from the choke coil L is charged to the capacitor C via the diode D, the level of the input voltage Vin applied to the input terminal IN is converted, and the output voltage Vout is output from the output terminal OUT. Is done.

[0008] Further, based on the temperature detected by the temperature sensor S1, the control circuit 11 controls the transistor Tr when the detected temperature exceeds a predetermined temperature and becomes overheated.
1 is turned off to shut off the voltage output to the output terminal OUT.

As shown in FIG. 7, these components are mounted on one surface of a circuit board 2 made of paper epoxy or glass epoxy, and a temperature sensor S1 is mounted on the circuit board.
Are arranged near the transistor Tr1 (heat generating part) or near the transistor Tr1 and the diode D (heat generating part), which generate a large amount of heat.

Thus, it is possible to prevent the destruction of parts and the occurrence of fire due to the heating.

[0011]

However, in the above-described conventional power supply device, heat generated from the heat generating portions such as the transistor Tr1, the diode D, and the choke coil L is not transmitted to the circuit board 2 or the space having a low thermal conductivity. To the temperature sensor S1, the sensitivity of the temperature detection decreases,
Temperature detection accuracy was poor.

As a result, the output is shut down before the heating occurs to affect the parts and the like, and the output power is unnecessarily limited, or the parts are broken before the detected temperature reaches the set value and the output is shut down. There was a problem that

It is also conceivable to improve the temperature detection accuracy by transmitting heat from the heating section to the temperature sensor S1 using a wiring pattern provided on the circuit board 2. In this case, there has been a problem that the cost is increased by the trouble of providing a pattern for heat conduction having high heat conductivity on the circuit board 2 and the material cost of the pattern.

When a heat radiator is used for the heat generating portion, for example, when the heat radiator 3 is mounted on the switching transistor Tr1 as shown in FIG.
, The temperature is detected, but there is a problem that the cost of the heat radiating plate 3 increases and the size of the device increases.

An object of the present invention is to provide a small-sized and inexpensive power supply device provided with a protection means for preventing heat having excellent temperature detection sensitivity in view of the above problems.

[0016]

According to the present invention, in order to achieve the above object, according to the present invention, an insulating substrate and a heat-generating component formed on the substrate and applied to an input terminal are provided. A power supply circuit for converting an input voltage into a voltage different from the input voltage and outputting the voltage, and a detection signal corresponding to a detection temperature, provided at a position on the substrate substantially opposite to the heat-generating component, with the detection signal corresponding to a detected temperature output The present invention proposes a power supply device comprising: a temperature sensor that performs the operation; and an operation stop unit that stops the operation of the power supply circuit when a temperature detected by the temperature sensor becomes equal to or higher than a predetermined temperature based on the detection signal.

According to the power supply device, the heat generated from the heat-generating components of the power supply circuit is transmitted through the substrate to the temperature sensor, and the temperature sensor detects the heat generation temperature, and the temperature sensor responds to the detected temperature. The detected signal is output.

Since the substrate is insulative but has a high thermal conductivity, and since the temperature sensor is provided across the substrate so as to face the heat-generating component, the heat generated from the heat-generating component is small. It is transmitted to the temperature sensor efficiently.

When the temperature detected by the temperature sensor becomes equal to or higher than a predetermined temperature based on the detection signal output from the temperature sensor, the operation of the power supply circuit is stopped by the operation stopping means. Thereby, destruction or fire of the heat generating component or the power supply circuit caused by heating can be prevented.

According to a second aspect of the present invention, in the power supply device according to the first aspect, a blank area in which a wiring pattern and a through hole are not formed is provided on a portion of the substrate located between the heat generating component and the temperature sensor. Suggest a power supply.

According to the power supply device, since a blank area where a wiring pattern and a through hole are not formed is provided in a portion of the substrate located between the heat-generating component and the temperature sensor, the substrate is generated from the heat-generating component. The generated heat is conducted to the temperature sensor through the substrate without being widely dispersed by the wiring patterns and the through holes.

According to a third aspect of the present invention, there is provided the power supply device according to the first or second aspect, wherein the substrate is made of alumina ceramic.

According to the power supply device, since the alumina ceramic substrate has an insulating property and contains a metal and has a relatively high thermal conductivity, the heat generated from the heat-generating component is hardly lost and the temperature sensor is hardly lost. Can be conducted.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a power supply device according to a first embodiment of the present invention.

In FIG. 1, reference numeral S1 denotes a temperature sensor, for example, a thermistor. Reference numeral 10 denotes a power supply circuit including a DC-DC converter, which includes a choke coil L, a diode D,
It comprises a capacitor C, an NPN transistor Tr1, and a control circuit 11 for controlling the switching operation of the transistor Tr1.

One end of the choke coil L is an input terminal.
The other end is connected to the anode of the diode D and the collector of the transistor Tr1. Diode D
Is connected to the output terminal OUT and grounded via the capacitor C. Also, the transistor Tr
One emitter is grounded, and a control signal output from the control circuit 11 is input to the base.

Further, a temperature sensor S1 is connected to the control circuit 11.

The control circuit 11 operates by supplying DC power from the input terminal IN, and switches on and off the transistor Tr1 at a predetermined cycle.

Thus, the current output from the choke coil L is charged to the capacitor C via the diode D, the level of the input voltage Vin applied to the input terminal IN is converted, and the output voltage Vout is output from the output terminal OUT. Is done.

Further, based on the temperature detected by the temperature sensor S1, the control circuit 11 detects whether the transistor Tr
1 is turned off to shut off the voltage output to the output terminal OUT.

In the first embodiment, the control circuit 1
1 and the transistor Tr1 constitute an operation stopping means.

The circuit shown in FIG. 1 is similar to the circuit shown in FIGS.
Are formed on the front and back surfaces of the substrate 20 as shown in FIG. That is, the power supply circuit 10 excluding the control circuit 11 is formed on one surface (front surface) 20a of the substrate 20, and the control circuit 11 is formed on the other surface (rear surface) 20b of the substrate 20, and the temperature sensor S1 is mounted thereon. Has been implemented.

Here, the choke coil L, the diode D, and the transistor Tr1, which is an electronic switch, are arranged adjacent to each other to form the heating section 21.

The mounting position of the temperature sensor S1 is set on the opposite side of the heating unit 21 with the substrate 20 interposed therebetween, for example, a position overlapping the mounting position of the transistor Tr1 on one surface. A blank area where the wiring pattern 22 and the through-hole 23 are not formed (an area substantially coinciding with the area of the heat generating part 21) is provided between the sensor and the sensor S1.

According to the above-described configuration, the alumina ceramic substrate 20 is connected to the heating portion 21 of the power supply circuit 10 including the choke coil L, the diode D, and the transistor Tr1.
, The distance between the heat generating portion 21 and the temperature sensor S1 can be minimized and a high thermal conductivity can be obtained, and the choke coil L, the diode D, and the transistor can be obtained. The heat generated from Tr1 can be detected with high sensitivity and high accuracy by the temperature sensor S1. Thereby, when the temperature detected by the temperature sensor S1 becomes equal to or higher than the predetermined temperature, the operation of the power supply circuit 10 is stopped without fail, and it is possible to prevent the destruction or fire of the components or the power supply circuit caused by heating beforehand. .

Further, by changing the material of the substrate and the arrangement of the temperature sensors in the conventional power supply device, the power supply device can be easily implemented without providing a heat conduction wiring pattern or a heat radiating plate. There is no.

Further, the heat generated from the heat generating portion 21 is transmitted through the substrate 20 to the vicinity of the edge thereof, and is radiated to the space therefrom, so that the generation of heating can be reduced as compared with the conventional case.

The alumina ceramic substrate 20 is made of Al
_The main component is alumina having a composition of ₂ O ₃ . In the first embodiment, the alumina ceramic substrate 20 has a thermal conductivity of 0.02 to 0.04 cal / cm ° C. and a thermal expansion coefficient of 6.0 to 6.5 × 10 ⁻⁶ / ° C. (0 to 300
C), the dielectric constant is 8.5 to 9.5 (1 MHz), and the thermal conductivity of the glass epoxy substrate in the conventional example is 0.00.
07-0.0015 cal / cm ° C, thermal expansion coefficient is 10
-30 × 10 ^-6 / ° C (0-300 ° C), dielectric constant 4.9
To 5.1 (1 MHz), and the alumina ceramic substrate 20 has a much higher thermal conductivity than the glass epoxy substrate.

Next, a second embodiment of the present invention will be described.

FIG. 4 is a circuit diagram showing a power supply device according to the second embodiment. In the figure, the same components as those in the first embodiment are denoted by the same reference numerals. The power supply device of the second embodiment is a case where the power supply circuit using a choke coil in the power supply device of the first embodiment is replaced with a power supply circuit using a transformer.

That is, S1 is a temperature sensor, 30 is DC-D
The power supply circuit includes a transformer T, a diode D, a capacitor C, a field effect transistor Tr2, and a control circuit 31 that controls a switching operation of the field effect transistor Tr2.

One end of the primary winding of the transformer T is connected to the positive input terminal + IN, and the other end is a field effect transistor Tr.
2 is connected to the negative input terminal -IN via the drain / source of the second.

One end of the secondary winding of the transformer T is connected to the anode of the diode D, and the other end is connected to the negative output terminal -O.
Connected to UT. The cathode of the diode D is connected to the positive output terminal + OUT and to the negative output terminal -OUT via the capacitor C.

The control signal output from the control circuit 31 is input to the gate of the field effect transistor Tr2.

Further, a temperature sensor S1 is connected to the control circuit 31.

The control circuit 31 operates by supplying DC power from the input terminal IN, and switches on and off the field effect transistor Tr2 at a predetermined cycle.

As a result, the voltage applied to the input terminal is boosted or stepped down by the transformer T, then charged in the capacitor C via the diode D, and the level of the input voltage Vin applied to the input terminal IN is converted. Output terminal OUT
Outputs an output voltage Vout.

Further, based on the temperature detected by the temperature sensor S1, the control circuit 31 detects whether the transistor Tr
2 is turned off to shut off the voltage output to the output terminal OUT.

In the second embodiment, the control circuit 3
1 and the field effect transistor Tr2 constitute an operation stopping means.

The components described above are mounted on a substrate to form a circuit. That is, as shown in FIGS. 5 and 6, the power supply circuit 30 excluding the control circuit 31 is formed on one surface (front surface) 20 a of the substrate 20.
On the other surface (back surface) 20b, a control circuit 31 is formed and a temperature sensor S1 is mounted.

Here, the transformer T, the diode D, and the field-effect transistor Tr2, which is an electronic switch, are arranged adjacent to each other to form a heating section 21 '.

The mounting position of the temperature sensor S1 is set on the opposite side of the heat generating portion 21 'with respect to the substrate 20, for example, at a position overlapping the mounting position of the field effect transistor Tr2 on one surface. A wiring pattern 22 and a through hole 23 are provided between the heat generating portion 21 'and the temperature sensor S1.
Is provided with a blank area where no is formed. The blank area in the second embodiment is set to be substantially the same as the area of the heat generating portion 21 ', similarly to the first embodiment.

According to the above configuration, the transformer T, the diode D and the field effect transistor Tr2 of the power supply circuit 30
Since the temperature sensor S1 is disposed with the alumina ceramic substrate 20 interposed between the heat-generating portion 21 'and the heat-generating portion 21', the distance between the heat-generating portion 21 'and the temperature sensor S1 is minimized and the thermal conductivity is high. Can be obtained, and the heat generated from the transformer T, the diode D, and the field effect transistor Tr2 can be detected with high sensitivity and high accuracy by the temperature sensor S1.

Thus, when the temperature detected by the temperature sensor S1 exceeds a predetermined temperature, the power supply circuit 30
Operation is stopped, and destruction of components or a power supply circuit or a fire caused by heating can be prevented.

Further, by changing the material of the substrate and the arrangement of the temperature sensors in the conventional power supply device, the power supply device can be easily implemented without providing a wiring pattern for heat conduction or a heat radiating plate. There is no.

Here, the thermal expansion coefficient of the ferrite of the transformer T in the second embodiment is about 6.8 × 10 ⁻⁶ / ° C.
(0-300 ° C.).

In the second embodiment, the same effects as in the first embodiment can be obtained.

The configurations of the first and second embodiments are merely examples, and the present invention is not limited to these.

[0060]

As described above, according to the first aspect of the present invention, since the temperature sensor is arranged with the substrate interposed between the heat-generating components of the power supply circuit, the space between the heat-generating component and the temperature sensor can be reduced. The distance is required minimum, and the substrate is insulative, but high thermal conductivity can be obtained, and the heat generated from the heat generating component is detected with high sensitivity and high accuracy by the temperature sensor. Can be. Thereby, when the temperature detected by the temperature sensor becomes equal to or higher than a predetermined temperature, the operation of the power supply circuit is reliably stopped by the operation stop means, and the destruction or fire of the heat generating component or the power supply circuit caused by heating is prevented. It can be prevented beforehand. Further, by changing the material of the substrate and the arrangement of the temperature sensors in the conventional power supply device, the power supply device can be easily implemented without providing a heat conduction wiring pattern or a heat radiating plate.

According to the second aspect of the present invention, in addition to the above effects, a blank area in which a wiring pattern and a through hole are not formed is provided on a portion of the substrate located between the heat generating component and the temperature sensor. Since the heat generated from the heat-generating component is conducted to the temperature sensor via the substrate without being widely dispersed by the wiring pattern and the through-hole, the temperature detection sensitivity can be further improved, and the output can be reduced. The error of the temperature value to be shut off can be reduced.

According to the third aspect of the present invention, in addition to the above effects, the alumina ceramic substrate has an insulating property and a relatively high thermal conductivity. Therefore, the temperature can be transmitted to the temperature sensor, so that the temperature detection sensitivity can be further improved, and the error of the temperature value at which the output is cut off can be further reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a power supply device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a component arrangement on a substrate surface according to the first embodiment of the present invention;

FIG. 3 is a diagram showing a component arrangement on the back surface of the board according to the first embodiment of the present invention;

FIG. 4 is a circuit diagram showing a power supply device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a component arrangement on a substrate surface according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a component arrangement on the back surface of a substrate according to a second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing a component arrangement on a board in a conventional example.

FIG. 8 is a schematic configuration diagram showing a component arrangement on a substrate in a conventional example using a heat sink.

[Explanation of symbols]

10, 30 power supply circuit, 11, 31 control circuit, 20 board, 20a front surface, 20b back surface, 21
Reference numeral 21 ': heat generating portion, 22: wiring pattern, 23: through hole, L: choke coil, D: diode, C: capacitor, T: transformer, S1: temperature sensor, Tr1: transistor, Tr2: field effect transistor.

Continued on the front page (72) Inventor Yasuo Hosaka 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd. F-term (reference) 5G065 AA00 AA08 BA00 DA07 EA01 LA07 MA09 MA10 PA04

Claims (3)

[Claims] An insulating substrate, a power supply circuit formed on the substrate, having a heating component, and converting an input voltage applied to an input terminal to a voltage different from the input voltage and outputting the converted voltage; A temperature sensor that is provided on the substrate at a position substantially opposite to the heat-generating component, and that outputs a detection signal corresponding to a detection temperature; and a temperature detected by the temperature sensor is determined based on the detection signal. A power supply device comprising: operation stop means for stopping the operation of the power supply circuit when the temperature becomes equal to or higher than a temperature. 2. The power supply device according to claim 1, wherein a blank region in which a wiring pattern and a through hole are not formed is provided in a portion of the substrate located between the heat generating component and the temperature sensor. 3. The power supply device according to claim 1, wherein the substrate is made of alumina ceramic.