JP2000236676A - Power supply device, discharge lamp-lighting system, and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce generation of unbalance and connection failures by inputting the DC voltage of a DC power supply device for alternately turning on and off for switching, and by setting voltage applied between the gate and the source of a P-type FET to be larger than that for an N-type FET for alternately turning on and off a switching device. SOLUTION: A drive means 9 applies a voltage between the gate and the source of FETs 7 and 8 and alternately turns on and off the FETs 7 and 8. A load circuit 10 is provided in parallel with the P-type FET 8. The switching devices 7 and 8 input a DC voltage from a DC power supply device 1 for switching by the output signal of the drive means 9. The output of the drive means 9 sets voltage applied between the gate and the source of the P-type FET 8 is set larger than that applied between the gate and the source of the N-type FET 7, thus allowing the calorific values of the FETs to be close, and hence providing heat radiation countermeasures and balancing the service life.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to complementary N-channel field-effect transistors (hereinafter referred to as "N-FETs") and P-channel field-effect transistors (hereinafter referred to as "P-FETs"). The present invention relates to a power supply device, a discharge lamp lighting device, and a lighting device mainly including a switching device.

2. Description of the Related Art Conventionally, this kind of apparatus has been disclosed in Japanese Patent Application Laid-Open
The one described in FIG. 5 of JP-A-2986 is known.
In this device, an N-type FET and a P-type FET connected in series with each other are alternately turned on and off, and a switching lamp obtained by these FETs is used to light a discharge lamp at a high frequency.

In this prior art, a feedback winding is provided on a ballast choke provided in series with a discharge lamp, and a pair of switching devices (P type,
N-type FETs are alternately turned on and off. A constant voltage element is provided for each FET in order to stabilize it so that an excessive drive voltage is not applied between the gate and the source of each FET.

In the structure of a complementary P-type FET and an N-type FET, when driven at the same gate voltage, the P-type FET has an N-type FE.
It is known that the on-resistance is larger than T, and is also shown in a characteristic diagram issued by a switching element maker. Therefore, in the above-mentioned prior art, the P-type FET generates a larger amount of heat during operation and the temperature rises transiently. For this reason, the P-type FET has an unbalance such that it has a shorter life and requires relatively large heat radiating means. Further, when soldering each FET and other components, the thermal stress of the solder of the P-type FET and the solder located near the P-type FET becomes relatively large, which may cause a connection failure. The present invention relates to a P-type FET and an N-type FE
It is an object of the present invention to provide a power supply device, a discharge lamp lighting device, and a lighting device capable of eliminating or reducing the life of these switching devices, the imbalance of heat radiating means, and the occurrence of connection failure by equalizing the ON resistance of T. Aim.

According to a first aspect of the present invention, there is provided a power supply apparatus comprising: a DC power supply; and an N-type FET and a P-type FET which are complementary types. A switching device that is turned on and off to switch a DC voltage; and a driving unit that turns on and off the switching device alternately by making the voltage applied between the gate and source of the P-type FET larger than the voltage applied to the gate and source of the N-type FET. ;

In the present invention and the following inventions, unless otherwise specified, each configuration, term, and the like are defined as follows. The switching devices may be of the type connected in parallel to the input DC power supply device or of the type connected in series to each other, or may be provided in two or more pairs. The driving means is at least an N-type FET
And the P-type FET must be turned on alternately, and the gate-source voltage of the P-type FET must be relatively increased. However, it does not matter whether the driving means is a so-called separately-excited type or a self-excited type. In the case of the separately-excited type, for example, the output of the oscillator that outputs the drive signal may be different between the P-type FET and the N-type FET. Further, means for reducing the output for the N-type FET among the outputs of the oscillator may be provided. In the case of the self-excited type, the feedback means may be common to each switching device or may be specially provided. As such a feedback means, a transformer, a current transformer, a device using a photocoupler or the like can be used. In the case where the feedback means is common, the gate-source voltage of the P-type FET is reduced by providing the asymmetry means in the feedback means.
It can be larger than that of T. Return means is each F
In the case where the ET is specially provided, the asymmetry means may be provided, or the output of the feedback means may be made different. As an asymmetrical means, a simple method is to provide a constant voltage element between the gate and the source of each FET, and to make the constant voltage value of the constant voltage element different between the N-type FET and the P-type FET. The constant voltage element is typically a Zener diode, but other elements such as a varistor can also be used. The constant voltage value of the constant voltage element is selected so that each FET can be turned on. The degree to which the voltage value of the constant voltage element corresponding to each FET is different is such that the on-resistance of each FET is close and preferably equal. Note that an impedance element may be added to the constant voltage element. In addition, each F
Providing the ET with a constant voltage element means that the respective drive voltages can be made constant, and it does not matter whether or not the ET is provided corresponding to each FET in circuit connection.

[0004] The switching frequency of the pair of switching devices is not particularly limited, but is preferably 20 kHz or more in that it is higher than the audible frequency.

[0005] In the first aspect of the present invention, the driving means is provided for each FE.
A drive voltage is applied between the gate and source of T, and the FET is turned on and off alternately. This drive voltage is N
It is set larger than the type FET. Therefore, P
The on-resistance of an N-type FET decreases with an increase between the gate and the source and approaches, and preferably equals, the on-resistance of an N-type FET. As a result, the calorific values of both FETs also come close to each other, so that a balance between heat dissipation measures and life is achieved. Also,
P-type FET and P-type FE even when solder is used for connection
The thermal stress of the solder in the vicinity of T is not increased, and connection failure is unlikely to occur.

A power supply device according to a second aspect of the present invention includes a DC power supply device and N-type FETs and P-type FETs that are complementary types. A switching device for switching; a load circuit for outputting an AC voltage based on a switching output; feedback means provided in the load circuit for generating an AC voltage and applying it to each FET as an ON / OFF drive voltage; provided in the feedback means Means for making the gate-source voltage of the P-type FET larger than the gate-source voltage of the N-type FET. The load circuit is, for example, for supplying electric power to the discharge lamp and lighting the discharge lamp, and includes a current limiting impedance element for stably lighting the discharge lamp as needed, a filament preheating circuit, and the like. Since various types of such load circuits themselves are well known and can be appropriately configured by those skilled in the art, these can be appropriately adopted in the present invention.

According to a third aspect of the present invention, in the power supply device according to the first or second aspect, the degree to which the gate-source voltage of the P-type FET is made higher than the gate-source voltage of the N-type FET is such that And on-resistance of the N-type FET is substantially equal.

According to the third aspect of the present invention, since the on-resistance of each FET is substantially equal, the conditions relating to each FET are substantially equal. According to a fourth aspect of the present invention, there is provided a power supply device according to any one of the first to third aspects, and a discharge lamp activated by an output of the power supply device.

The discharge lamp may be of any type such as a low-pressure mercury vapor discharge lamp represented by a hot-cathode fluorescent lamp, a cold-cathode fluorescent lamp, a rare gas discharge lamp, and a high-intensity discharge lamp. Is also good.

According to a fifth aspect of the present invention, there is provided a lighting fixture body;
And a discharge lamp lighting device according to claim 4.

The functions of the inventions of claims 4 and 5 are basically the same as those of any one of claims 1 to 3.

In the invention of claim 5, the lighting fixture body may be for indoor or outdoor use, and may be for general lighting, display, OA equipment, or the like. It may or may not have a light control body such as a reflector or a light shield. Further, the discharge lamp lighting device may or may not be housed in the lighting fixture body.

[0013]

Next, one embodiment of the present invention will be described.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.
FIG. 2 is a voltage waveform diagram showing the operation of the embodiment of FIG.
Reference numeral 1 denotes a DC power supply. The DC power supply 1 has a high-frequency cut filter 3 connected to an AC power supply 2.
The rectifier 4 further includes a rectifier 4 to which an AC voltage is input via the high-frequency cut filter 3, a smoothing capacitor 5 provided between output terminals of the rectifier 4, and a current limiting resistor 6. 7,
Reference numeral 8 denotes a pair of switching devices connected in series to each other, and is provided between output terminals of the DC power supply 1.
7 is an N-type FET and 8 is a P-type FET, and their sources are connected to each other. The gates of the FETs 7 and 8 are also connected to each other. 9 is a driving means, each F
A voltage as shown in FIG. 2 is applied between the gate and the source of the ETs 7 and 8, and the FETs 7 and 8 are turned on and off alternately. Reference numeral 10 denotes a load circuit. This load circuit 10 is provided in parallel with the P-type FET 8. The operation of the present embodiment will be described. The pair of switching devices 7 and 8 receive a DC voltage from the DC power supply device 1 and switch at, for example, several tens KHz according to an output signal of the driving unit 9. As shown in FIG. 2, the output of the driving means 9 is a voltage applied between the gate and the source of the P-type FET 8 in the form of an N-type FE.
The voltage is higher than the voltage applied between the gate and source of T8. As a result, the on-resistance of the P-type FET 8 decreases as the voltage applied between the gate and the source increases. Note that the output voltage waveform of the driving means 9 is not a rectangular wave,
It may be a sine wave, a trapezoidal wave, or the like. In order to surely avoid the simultaneous ON state of the FETs 7 and 8, it is effective to provide an idle period for positive / negative voltage switching, and to provide a certain slope at the rise and fall of the voltage such as a sine wave. is there. A second embodiment of the present invention will be described. FIG. 3 is a circuit diagram showing the second embodiment. Parts that are the same as or correspond to those in FIG. In the present embodiment, the load circuit 11 includes a discharge lamp 12, and the driving means 13 is a so-called self-excited type, which will be described in detail later. First, the load circuit 11 includes a series circuit of the discharge lamp 12, the DC cut capacitor 14, and the current limiting inductor 15, and a filament preheating and starting capacitor 16 provided between the non-power supply side filaments of the discharge lamp 12. Contains. Load circuit 1 of the present embodiment
1 is set so that the current limiting inductor 15 and the filament heating capacitor 16 resonate in series, and therefore applies a resonance voltage to the discharge lamp 12. Before and after the discharge lamp 12 is turned on, the resonance characteristics change depending on the presence or absence of the resistance component of the discharge lamp 12. Discharge lamp 1
2 is designed so that the sharpness of the resonance becomes larger before lighting. The driving means 13 uses an output of an output winding as feedback means 17 magnetically coupled to the current limiting inductor 15 as a power supply. A series resonance circuit of an inductor 18 and a capacitor 19 is provided between both ends of the feedback means 17, and a voltage between both ends of the capacitor 19 is applied between the gate and source of each of the switching devices 7 and 8 via the capacitor 20. I have. Further, a pair of constant voltage elements 21 and 22 are provided between the commonly connected gate and source, the anodes of which are commonly connected. In this embodiment, the constant voltage elements 21 and 22 have different constant voltage values. That is, the constant voltage value of the constant voltage element 22 is larger than that of the constant voltage element 21. Therefore,
The drive voltage of the P-type FET 8 is higher than the drive voltage of the N-type FET 7. Here, 23, 24 and 25 are resistors forming a starting circuit. Reference numeral 26 denotes a capacitor for snubber, switching improvement, and both functions.

Next, the operation of the present embodiment will be described. When the AC power supply 2 is turned on by a switch (not shown), the DC power supply 1 generates a predetermined DC voltage across the smoothing capacitor 5. During or after the voltage across the smoothing capacitor 5 has sufficiently risen, the resistance 2
3, 24, 25, and the output voltage of the DC power supply 1 is applied to the closed circuit of the feedback means 17. Thereby, the real resistance 24
Is applied between the gate and source of each of the FETs 7 and 8 and reaches the threshold voltage of the N-type FET 7 in the forward direction, the N-type FET 7 is turned on.

When the N-type FET 7 is turned on, a current flows from the DC power supply 1 to the load circuit 11 via the drain / source of the N-type FET 7. The current flowing through the load circuit 11 becomes a resonance current by the current limiting inductor 15 and the filament heating capacitor 16. Also,
The feedback means 17 outputs a voltage in accordance with the voltage of the current limiting inductor 15 to forward bias the N-type FET 7 and the P-type FET 8
Reverse bias. In this period, the voltage value of the substantially constant voltage element 21 + the forward voltage drop of the constant voltage element 22 is applied between the gate and the source of the N-type FET 7.

Next, when the resonance voltage by the current-limiting inductor 15 and the filament heating capacitor 16 is inverted, the polarity of the output voltage of the feedback means 17 is also inverted, and N
The reverse bias is applied to the FET 7 and the forward bias is applied to the P-type FET 8. Therefore, the N-type FET 7 turns off and the P-type FET 8 turns on. When the P-type FET 8 is turned on, a resonance current flows in the load circuit 11 through the P-type FET 8 in a direction opposite to the previous direction. During this period, the P-type FE
The voltage of the constant voltage element 22 plus the forward voltage drop of the constant voltage element 21 is applied between the gate and the source of T8. Since the voltage value of the constant voltage element 22 is larger than the voltage value of the constant voltage element 21, the gate-source voltage of the P-type FET 8 is N-type F
It becomes larger than the gate-source voltage of ET7. Therefore, the on-resistance of the P-type FET 8 becomes smaller than that when a gate-source voltage of the same magnitude as that of the N-type FET 7 is applied, and approaches the on-resistance of the N-type FET 7.

Thereafter, the FETs 7 and 8 are alternately turned on and off, and the load circuit 11 supplies a high-frequency voltage to the discharge lamp 12 in response thereto. After the filament is preheated, the discharge lamp 12 starts and lights up.

In this embodiment, N-type and P-type FETs are used.
The driving means 13 can be used in common for the pair of switching devices 7 and 8 and the current limiting inductor 15 is used as the feedback means, so that the overall size of the device can be further reduced. Can be achieved.

Next, an embodiment of the lighting device of the present invention will be described. FIG. 4 is a simplified front view showing an embodiment of the lighting device of the present invention. This embodiment is applied to a so-called bulb-type fluorescent lamp. Reference numeral 40 denotes a lighting fixture body, which includes a base 41, a cover 42, and a glove
3 The base 41 is of a well-known Edison type, and the cover 42 is molded of resin or the like and is generally non-translucent. The glove 43 is formed of a diffusible material such as transparency and milky white. Reference numeral 44 denotes a discharge lamp, which is formed in a U-shape by connecting three glass bulbs to form one discharge space. Reference numeral 45 denotes a discharge lamp lighting device,
The electronic component 47 is mounted on the cover 6 and housed in the cover 42. Although not shown, the discharge lamp lighting device 45, the discharge lamp 44, and the base 41 are electrically connected by a known means such as an electric wire. As in the present embodiment, in the case of a so-called bulb-type fluorescent lamp, particularly when downsizing is required, the discharge lamp lighting device 45 is reduced in size by reducing the number of parts as shown in FIG. The preferred embodiment is preferred.

According to the present invention, the gate-source voltage of the P-type FET of the switching device having the complementary N-type FET and the P-type FET is relatively large. As a result, the on-resistance of the P-type FET can be reduced to approach the on-resistance of the N-type FET. As a result, the calorific values of both FETs can be approached,
Balance of heat dissipation measures and life. Further, even when solder is used for the connection, the thermal stress of the P-type FET and the solder near the P-type FET does not increase.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a voltage waveform diagram showing the operation of one embodiment of the present invention.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a simplified front view showing an embodiment of the lighting device of the present invention.

[Explanation of symbols]

1: DC power supply device, 7, 8: Switching device, 9, 1
3: driving means, 10, 11: load circuit, 12: discharge lamp,
17 Return means.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K072 AA02 AA06 BA03 BB01 BC01 BC03 DB03 DD04 GA02 GB12 GC02 GC04 HB03 5H007 AA03 AA06 AA17 BB03 CA02 CB03 CB04 CB17 CB22 CC07 DB03

Claims (5)

[Claims] 1. A DC power supply, comprising: a complementary type N-channel field-effect transistor and a P-channel field-effect transistor, receiving a DC voltage of the DC power supply, and alternately turning on and off to switch the DC voltage. Driving means for alternately turning on and off the switching device by setting a voltage applied between the gate and source of the P-channel field effect transistor higher than a voltage applied to the gate and source of the N-channel field effect transistor; A power supply device comprising: 2. A DC power supply, comprising: an N-channel type field effect transistor and a P-channel type field effect transistor of a complementary type, receiving a DC voltage of the DC power supply, and alternately turning on and off to switch the DC voltage. A load circuit that outputs an AC voltage based on a switching output; a feedback unit that is provided in the load circuit and that generates an AC voltage and applies it to each field-effect transistor as an on / off drive voltage; Means for making the gate-source voltage of the P-channel field-effect transistor greater than the gate-source voltage of the N-channel field-effect transistor. 3. The degree to which the gate-source voltage of a P-channel field-effect transistor is made higher than the gate-source voltage of an N-channel field-effect transistor is determined by P
3. The power supply device according to claim 1, wherein the on-resistances of the channel type field effect transistor and the N channel type field effect transistor are substantially equal. 4. A discharge lamp lighting device comprising: the power supply device according to claim 1; and a discharge lamp energized by an output of the power supply device. 5. A lighting device comprising: a lighting fixture body; and the discharge lamp lighting device according to claim 4.