JP2003168587A - Discharge lamp lighting device and lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of reducing the output when a load circuit generates abnormal heat and capable of starting at normal temperature, and to provide a lighting device using the same. <P>SOLUTION: The feedback drive signal generation circuit 5 has a drive resonance circuit 11 composed of a feedback winding L2b feeding back the current flowing into a load circuit 4, a drive resonance inductor L3 resonating with a feedback voltage generated at the feedback winding L2b, and a drive resonance capacitor C7 changing its static capacity according to the change of temperature. The drive resonance capacitor C7 has such a temperature characteristics that makes the capacitance of the drive resonance capacitor possible to charge a voltage necessary for the starting. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device provided with a capacitor having a capacitance change characteristic with respect to ambient temperature, and a lighting device using the same.

[0002]

2. Description of the Related Art In a discharge lamp lighting device having a half-bridge type inverter, it has already been performed to feed back a current flowing in a load circuit to form a drive signal for a switching element by self-excited oscillation. This discharge lamp lighting device has an advantage that it has a relatively simple circuit configuration and can be easily miniaturized, and is often used especially for compact fluorescent lamps that require miniaturization.

The prior art (Japanese Unexamined Patent Publication No. 2001-338790) filed by the applicant of the present patent application will be described below with reference to the drawings. FIG. 6 is a circuit diagram of a discharge lamp lighting device 50 showing the prior art. In the figure, Vs is a commercial 100V low-frequency AC power source, F1 is an overcurrent fuse integrally formed on a wiring board, 7 is a noise filter, 8 is a rectifier, 9 is a smoothing circuit, 3 is a switching circuit, and Q1 is
Is a first switching means, Q2 is a second switching means, 4 is a load circuit, 51 is a feedback drive signal generating circuit, and 52 is a starting circuit.

The feedback type drive signal generation circuit D51 includes a feedback winding L2b, a drive resonance circuit 53, and a temperature sensitive resistor R.
_{It comprises a PTC} (Positive Characteristic Thermistor), a capacitor C8 and a drive protection circuit 12. The feedback winding L2b is an auxiliary winding that is magnetically coupled to the resonance inductance L2 of the load circuit 4.

The drive resonance circuit 53 has an inductor L3.
And two capacitors C9 and C10. That is, the inductor L3 has one end connected to one end of the feedback winding L2b. One ends of the capacitors C9 and C10 are
It is connected to the other end of the feedback winding L2b. Capacitor C9
The other end of is connected to the other end of the inductor L3. The other end of the capacitor C10 is connected to the other end of the inductor L3 via a thermosensitive resistor R _PTC in series. After all, the capacitors C9 and C10 form a series resonance circuit with the inductor L3.

Next, the operation of the temperature sensitive resistor R _{PTC and} the operation of the discharge lamp 10 will be described. That is, since the resistance value of the temperature sensitive resistor R _PTC is small when the power is turned on,
The capacitance of the capacitor C10 almost directly affects the resonance action, so that the resonance frequency is relatively low and the operating frequency of the inverter is relatively low. By setting this operating frequency lower than the resonance frequency of the load circuit 4, the inverter operates in the phase advance mode and at an operating frequency relatively far from the resonance frequency. Therefore, the filament electrodes 10a, 10b of the discharge lamp 10
Since the output voltage of the inverter applied during this period is low, the discharge lamp 10 cannot be started, so only the filament electrodes 10a, 10b are preheated. That is, in the load circuit 4, when a current flows through the resonance capacitor C4 during the above operation, the current flows through the pair of filament electrodes 10a and 10b of the discharge lamp 10 and is electrically heated.

On the other hand, during the above operation, a resonance current flows in the drive resonance circuit 53 due to the resonance operation, so that the temperature-sensitive resistor R _PTC is electrically heated and its resistance value rises. Along with this, the current flowing through the capacitor C10 decreases, so that the effective drive resonance capacitance of the drive resonance circuit 53 decreases. Therefore, the resonance frequency rises as the resistance value of the temperature sensitive resistor R _PTC rises, the operating frequency of the inverter rises, and the resonance frequency of the load circuit 4 approaches relatively, so that the resonance capacitor is The voltage across C4 increases. This voltage is applied to the pair of filament electrodes 10a of the discharge lamp 10,
Since it is applied to 10b, the discharge lamp 10 will start and light up soon.

[0008]

In the prior art, the feedback drive signal generating circuit 51 including the temperature sensitive resistor R _PTC which continuously changes the resonance frequency of the drive resonance circuit 53 when the power is turned on is provided. Since the discharge lamp 10 is started after the filament electrodes 10a and 10b are preheated, the blinking characteristic can be improved.

However, this prior art is mainly intended to continuously change the resonance frequency of the drive resonance circuit 53 in order to improve the blinking characteristic of the discharge lamp 10 when the power is turned on as described above. For example, the discharge lamp 1 when the discharge lamp 10 is abnormally heated
Lighting control of 0 is not performed.

It is an object of the present invention to provide a discharge lamp lighting device capable of reducing the output when abnormal heat is generated in a load circuit and starting at a normal temperature, and a lighting device using the discharge lamp lighting device.

[0011]

The invention of a discharge lamp lighting device according to claim 1 is a direct current power supply; first switching means and second switching means connected in series with each other between the outputs of the direct current power supply. A switching circuit having means; a discharge lamp, a resonance inductance and a resonance capacitance, and a load circuit operated by high-frequency alternating current generated by alternate switching operations of the first and second switching means; a load circuit Has a drive resonance circuit configured to include a feedback winding that returns the current flowing through the drive winding, a drive resonance inductor that resonates with the feedback voltage generated in the feedback winding, and a drive resonance capacitor whose capacitance changes with temperature changes. , The capacitance of the drive resonance capacitor changes due to an abnormal rise in ambient temperature, causing the resonance frequency of the drive resonance circuit to change. A feedback drive signal generation circuit configured to alternately control the first and second switching means based on the resonance voltage of the drive resonance circuit so that the output of the load circuit is reduced by changing the number of the load resonance circuit. A drive circuit for operating at least one of the first and second switching means when a voltage of a DC power supply is applied, and the drive resonance capacitor has a capacitance capable of charging a voltage required for start-up at a normal temperature. It is characterized by having the following temperature characteristics.

In the present invention and each of the following inventions, each constitution is as follows unless otherwise specified.

"The first and second switching means are connected in series between the outputs of the DC power supply" means that the first and second switching means are in a series connection relationship when viewed from the DC power supply. That is, another circuit component such as a resistor may be interposed between the first and second switching means and the DC power supply. Also, a circuit component may be interposed between the first and second switching means.

The "normal temperature" refers to a temperature other than an abnormal rise in the ambient temperature such as abnormal discharge lamp lighting, and the drive immediately after the discharge lamp is turned off normally. It includes the ambient temperature of the resonant capacitor. Therefore, the drive resonance capacitor has an electrostatic capacity that can generate the resonance frequency and the resonance voltage of the drive resonance circuit that can start the load circuit even at a high temperature immediately after the discharge lamp is turned off.

According to the present invention, for example, when the load circuit heats up abnormally, the ambient temperature of the drive resonance capacitor rises, the capacitance changes, and the resonance frequency of the drive resonance circuit changes. Since it acts to reduce the output of the load circuit, abnormal heat generation of the load circuit is reduced, and thermal damage to constituent circuit parts is prevented. Also,
Since the drive resonance capacitor has a temperature characteristic such that the voltage required for start-up has a chargeable electrostatic capacity at normal temperature, the discharge lamp is reliably started after the discharge lamp is turned off.

The invention of a discharge lamp lighting device according to a second aspect is the discharge lamp lighting device according to the first aspect, wherein the drive resonance capacitor is at least 140 to 150 ° C.
The electrostatic capacity is set so that the discharge lamp can be started at the ambient temperature of.

The ambient temperature of 140 to 150 ° C. is formed in the cover of a light bulb type fluorescent lamp, for example.

According to the present invention, since the capacitance of the drive resonance capacitor is set so that the discharge lamp can be started at an ambient temperature of at least 140 to 150 ° C., it is 140 to 150 ° C. immediately after the discharge lamp is turned off. The discharge lamp is reliably relit even at the ambient temperature of.

According to a third aspect of the invention, there is provided the discharge lamp lighting device according to the first or second aspect, wherein the drive resonance capacitor is a ceramic chip capacitor.

According to the present invention, since the drive resonance capacitor is a ceramic chip capacitor, it is small in size, and the capacitance can be easily changed with respect to the ambient temperature, and a desired capacitance can be easily set.

The invention of a lighting device according to a fourth aspect comprises a lighting device main body; and the discharge lamp lighting device according to any one of the first to third aspects, which is disposed in the lighting device main body. It is characterized by

The illuminating device is a broad concept including all devices that utilize the light emission of a discharge lamp. For example, a lighting device, a backlight device such as a liquid crystal, and a personal computer incorporating the same, a television receiver, and a GP.
Office equipment such as various information equipment such as S equipment, image reading device and copiers, facsimiles, scanners, etc. incorporating the same.
Equipment, as well as compact fluorescent lamps.

According to the present invention, there is provided an illumination device in which the output of the discharge lamp is reduced when the discharge lamp abnormally generates heat and the discharge lamp can be restarted at a normal temperature.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. First, a first embodiment of the present invention will be described.

FIG. 1 is a circuit diagram of a discharge lamp lighting device showing a first embodiment of the present invention. The same parts as those in FIG. 6 are designated by the same reference numerals.

The discharge lamp lighting device 1 shown in FIG. 1 comprises a DC power supply 2, a switching circuit 3, a load circuit 4, a feedback type drive signal generating circuit 5 and a starting circuit 6.

The DC power supply 2 includes a noise filter circuit 7, a rectifying device 8 and a smoothing circuit 9 which are connected to a commercial 100V low frequency AC power supply Vs via an overcurrent fuse F1 formed integrally with the wiring board. It is configured to have.

The noise filter circuit 7 is interposed in series between the low-frequency AC power supply Vs and the rectifying device 8, and the first and second switching means Q1 and Q of the switching circuit 8 are provided.
The high frequency noise generated by the alternating switching operation of 2 is blocked so as not to flow out to the low frequency AC power supply Vs side, and is parallel to the low frequency AC power supply Vs on the inductor L1 and the low frequency AC power supply Vs side of the inductor L1. And an inductor L1 and a capacitor C1 that forms an inverted L-shaped circuit.

The rectifier 8 is formed by a bridge type full-wave rectifier circuit, the AC input end of which is connected to the low frequency AC power supply Vs via the noise filter circuit 7 and the DC output end of which is connected to the smoothing circuit 9. There is.

The smoothing circuit 9 comprises a series circuit of a resistor R1 and a smoothing capacitor C2, and both ends of the smoothing circuit 9 are a rectifying device 8.
It is connected between the DC output terminals of. Then, a smoothed DC voltage is generated across the smoothing capacitor C2.

The switching circuit 3 has a first switching means Q1 and a second switching means Q2 connected in series between the outputs of the DC power supply 2. The first switching means Q1 is composed of an enhancement N-channel MOSFET, and its drain is connected to the positive electrode of the smoothing circuit 9.
The second switching means Q2 is composed of an enhancement P-channel MOSFET, the source thereof is connected to the source of the first switching means Q1, and the drain thereof is connected to the negative electrode of the smoothing circuit 9. That is, the first and second switching means Q1 and Q2 are constructed in a complementary manner. Further, the first and second switching means Q1 and Q2 are connected in series between the output terminals of the smoothing circuit 9.

As the first and second switching means, switching means having the same polarity are used, but voltage control type switching means such as MOSFET or current control type switching means such as bipolar transistor can be used. The switching circuit 3 has a snubber capacitor C3 connected between the source and drain of the second switching means Q2. Thus, the switching circuit 3 forms a half-bridge type inverter.

The load circuit 4 is composed of a series circuit of a resonance inductance L2, a discharge lamp 10, a resonance capacitor C4 and a DC cut capacitor C5, and is connected in parallel to the second switching means Q2.
The resonance capacitor C4 and the DC cut capacitor C5 form resonance capacitance. However, since the capacitance of the DC cut capacitor C5 is relatively large, the resonance capacitor C4 predominantly acts as the resonance capacitance.

The discharge lamp 10 is a fluorescent lamp having a pair of filament electrodes 10a and 10b,
A pair of filament electrodes 10a and 10b are connected to both ends of the resonance capacitor C4 and are serially inserted in the load circuit 4. The resonance inductance L2 provides a current limiting impedance to the discharge lamp 10 that constitutes the load.
The load circuit 4 is operated by the high frequency alternating current (high frequency current) generated by the alternating switching operation of the first and second switching means of the switching circuit 3.

Then, the feedback type drive signal generation circuit 5
Is composed of a drive resonance circuit 11, a capacitor C6 and a drive protection circuit 12.

The drive resonance circuit 11 has a feedback winding L2.
b, a drive resonance inductor L3, and a drive resonance capacitor C7 having a temperature characteristic in which the electrostatic capacity changes due to a temperature change. Feedback winding L2b
Is an auxiliary winding that is magnetically coupled to the resonance inductance L2 of the load circuit 4. One end of the drive resonance inductor L3 is connected to one end of the feedback winding L2b, one end of the drive resonance capacitor C7 is connected to the other end of the feedback winding L2b, and the other end is the other end of the drive resonance inductor L3. It is connected to the. After all, the drive resonance capacitor C7 forms a series resonance circuit with the drive resonance inductor L3.

The feedback winding L2b feeds back the current flowing in the load circuit 4, and the drive resonance inductor L3 and the drive resonance capacitor C7 resonate with the feedback voltage generated in the feedback winding L2b. That is, the drive resonance circuit 11 generates a resonance voltage of positive and negative polarities by the resonance caused by the drive resonance inductance of the drive resonance inductor L3 and the drive resonance capacitance of the drive resonance capacitor C7. Then, this resonance voltage is
And to the second switching means Q1, Q2.

When the secondary winding of the unsaturated transformer is used as the feedback winding L2b, the inductance seen from the secondary winding side can be used as the drive resonance inductance. Resonance inductance L of load circuit 4
When a feedback transformer is configured by magnetically coupling the feedback winding L2b to 2, the inductance seen from the secondary winding side can be used in the same manner as above, but a separately provided inductance is used as the drive resonance inductance. You may use. The resonance circuit may be connected in either a parallel resonance circuit or a series resonance circuit. Further, as the drive resonance electrostatic capacity, in addition to using the capacitor C7, the electrostatic capacity of the first and second switching means Q1 and Q2, for example, the gate-source electrostatic capacity of the MOSFET can be used.

The drive resonance capacitor C7 is
For example, a ceramic chip capacitor has a temperature characteristic that the capacitance change rate increases and the capacitance decreases when the ambient temperature or the self temperature rises above a predetermined temperature. Since the capacitance of the ceramic chip capacitor changes with the ambient temperature, the resonance frequency of the drive resonance circuit 11 changes, and the output of the load circuit 4 can be reduced in response to the increase in ambient temperature. Also,
Since it is small, it can be installed in a narrow space on the circuit board.

FIG. 2 shows the capacitance change rate (∇C / C) of the drive resonance capacitor C7 with respect to the ambient temperature, which is based on the capacitance at the ambient temperature of 20 ° C. The ambient temperature of the drive resonance capacitor C7 is 1
At 40 ℃ or higher, the capacitance suddenly decreases and 160
At C, the capacitance decreases by about 11%. That is, the predetermined temperature of the drive resonance capacitor C7 is 140 ° C., for example. The ambient temperature near the filament electrodes 10a and 10b of the discharge lamp 10 is 170 ° C.
In the above case, the ambient temperature of the drive resonance capacitor C7 becomes higher than or equal to a predetermined temperature, the capacitance thereof decreases, the resonance frequency of the drive resonance circuit 11 increases, and the discharge lamp 10 is turned off. And the drive resonance capacitor C
7 is the filament electrodes 10a, 10 of the discharge lamp 10.
If it is arranged close to the heat generating portion such as b, it can be operated effectively.

The capacitance of the drive resonance capacitor C7 may have a temperature characteristic such that it is gradually reduced at normal temperature with an increase in ambient temperature.

In FIG. 1, the capacitor C6 has a relatively large electrostatic capacity, and the connection point A between the drive resonance inductor L3 and the drive resonance capacitor C7 of the drive resonance circuit 11 and the first and second switching means Q1. , Q2 and the gate of Q2 are inserted in series.

The drive protection circuit 12 comprises a pair of zener diodes ZD1 and ZD2 connected in anti-series,
It is connected between the gate and source of the first and second switching means Q1 and Q2.

The drive protection circuit 12 includes first and second drive protection circuits.
Is to prevent an excessive voltage from being applied to the drive terminals of the switching means Q1 and Q2, and its concrete circuit configuration may be any, as shown in FIG.
For example, at least two Zener diodes ZD
1 and ZD2 can be connected in series with opposite polarities. The drive protection circuit 12 can protect the resonance voltage of both positive and negative polarities. Further, when the complementary switching means Q1 and Q2 are used, one drive protection circuit 12 also exerts a gate protection action on both the first and second switching means Q1 and Q2. Further, the drive protection circuit 12 can be configured by various similar circuit configurations as long as it is a constant voltage element without using a Zener diode. Furthermore, the number of constant voltage elements used may be determined by the relationship between the constant voltage and the gate voltage.

Thus, the amount of voltage that causes an overvoltage to the gates of the first and second switching means Q1 and Q2 is
Since it is short-circuited and absorbed by the drive protection circuit 12, only a proper voltage is applied to each gate of the first and second switching means Q1 and Q2. When the overvoltage is applied to the first and second switching means Q1 and Q2, it causes the destruction of the first and second switching means Q1 and Q2. Therefore, it is preferable to add the drive protection circuit 12.

As described above, the feedback type drive signal generating circuit 5 is configured to alternately control the switching of the first and second switching means Q1 and Q2 based on the resonance voltage of the drive resonance circuit 11. .

The starting circuit 6 includes resistors R2 and R
3, a series circuit of the drive resonance capacitor C7 and the resistor R4, and a capacitor C6 connected in parallel to the resistor R3.
Consists of. The resistor R2 has one end connected to the positive electrode of the smoothing circuit 9, and the other end connected to the gate of the first switching means Q1 and the connection point B of the capacitor C6 of the drive signal generation circuit 5. The resistor R3 is connected to the connection point A of the capacitor C6 of the drive signal generation circuit 5. The resistor R4 is connected in parallel between the drain and source of the second switching means Q2.

The starting circuit 6 is turned on by turning on the DC power supply 2.
The capacitor C6 is charged with the time constant of the resistor R3. Then, the first switching means Q1 is turned on by the charging voltage of the capacitor C6.

Next, the circuit operation of the first embodiment of the present invention will be described.

When the low frequency AC power supply Vs is turned on, a DC voltage smoothed by the rectifier 8 and the smoothing circuit 9 of the DC power supply 2 is generated across the smoothing capacitor C2. Then, a DC voltage is applied between the drain and source of the first and second switching means Q1 and Q2 connected in series. However, the first and second switching means Q
Since the drive voltage is not applied to 1 and Q2, they remain in the off state.

Then, the DC voltage of the DC power supply 2 is simultaneously applied to the series circuit of the resistors R2 and R3, the drive resonance capacitor C7 and the resistor R4. And the capacitor C
6 is charged by the voltage drop of the resistor R3. Therefore, the voltage generated across the capacitor C6 is applied between the gate and source of the first switching means Q1 and exceeds the threshold voltage (Vth), so that a channel is formed and turned on. At this time, the second switching means Q2 remains in the off state because no voltage is applied to its gate.

Then, when the first switching means Q1 is turned on, the load circuit 4, that is, the resonance inductance L2, the filament electrode 10a, from the positive electrode of the smoothing circuit 9 via the drain / source of the first switching means Q1,
A current flows through the resonance capacitor C4, the filament electrode 10b, the DC cut capacitor C5, and the negative electrode path of the smoothing circuit 9. At this time, the resonance inductance L2 of the load circuit 4, the DC cut capacitor C5, and the series resonance circuit of the resonance capacitor C4 resonate to cause resonance capacitor C2.
The terminal voltage of 4 becomes high and is charged.

Furthermore, since a current flows through the resonance inductance L2, a voltage is induced in the feedback winding L2b of the feedback drive signal generating circuit 5 magnetically coupled to the resonance inductance L2. Then, since the feedback voltage induced in the feedback winding L2b is applied to the drive resonance circuit 11, the drive resonance circuit 11 resonates in series. Due to this series resonance, the terminal voltage of the drive resonance capacitor C7 rises, and the capacitor C6
Since the first drive signal voltage is applied to the gate of the first switching means Q1 via the, the first switching means Q1 is still in the ON state. At this time, since a voltage lower than that of the source is applied to the gate of the second switching means Q2, it remains in the off state.

However, the resonance voltage of the drive resonance circuit 11 has its polarity reversed next due to the vibration due to resonance, and at that time, the gate of the first switching means Q1 becomes a reverse voltage and turns off, and conversely the second voltage. Switching means Q
A second drive voltage in the forward direction is applied to the gate of No. 2 to turn it on.

Therefore, the first switching means Q1
ON time is determined by the capacitance of the drive resonance capacitor C7 of the drive resonance circuit 11 of the feedback drive signal generation circuit 5 and the inductance of the drive resonance inductor L3. The capacitance of the capacitor C6 is
It is selected so large that it does not affect the value or phase of the positive and negative gate voltages, and the first switching means Q1 is activated at startup.
Ensures that the gate of is maintained at the forward voltage.

When the first switching means Q1 is turned off, the electromagnetic energy stored in the resonance inductance L2 is released, and the filament electrode 10a, the resonance capacitor C4, the filament electrode 10b, and the DC cut capacitor C5 are emitted from the resonance inductance L2. , A parasitic diode (not shown) of the second switching means Q2.
And the current continues to flow through the path of the resonance inductance L2, but when the current becomes zero, the charged electric charge of the resonance capacitor C4 is the filament electrode 10a, the resonance inductance L2, the second switching means Q2,
The direct current cut capacitor C5, the filament electrode 10b and the resonance capacitor C4 are discharged along the path, and a current flows in the opposite direction to the above. At this time, the resonance inductance L
The voltage induced in the feedback winding L2b magnetically coupled to 2 is
Since it is the opposite of the above, the first switching means Q1 to which the resonance voltage is applied through the feedback type drive resonance circuit 5 is applied.
Keeps the off state, and the second switching means Q2 keeps the on state.

However, the feedback type drive signal generation circuit 5
When the resonance voltage of the drive resonance circuit 11 of oscillates and the polarity is inverted, the first switching means Q1 is turned on again,
The second switching means Q2 is turned off.

As a result, after the electromagnetic energy stored in the resonance inductance L2 is released, the current again flows from the positive electrode of the smoothing circuit 9 to the load circuit 4 as described above. Hereinafter, the operation described above is repeated to operate as a half-bridge type inverter.

Then, in the above repetition, the resonance voltage due to the resonance inductance and the resonance capacitance of the load circuit 4 causes the filament electrodes 10a, 1 of the discharge lamp 10 to have a resonance voltage.
The discharge lamp 10 is lit by being applied between 0b, and the lighting is maintained. Then, the heat of the discharge lamp 10 causes the ambient temperature of the drive resonance capacitor C7 to rise.

Then, as shown in FIG. 2, when the ambient temperature of the drive resonance capacitor C7 becomes 140 ° C. or higher,
The capacitance changes so as to decrease. This allows
The resonance frequency due to the resonance with the drive resonance inductor L3 increases. As a result, the resonance voltage due to the resonance inductance and the resonance capacitance of the load circuit 4 is reduced, and the output of the discharge lamp 10 is reduced, but the lighting thereof is maintained.

The drive resonance capacitor C7 is
The temperature characteristic is such that the discharge lamp 10 has a predetermined electrostatic capacity capable of being restarted at an ambient temperature of at least 140 to 150 ° C. That is, the discharge lamp 10 can be relighted immediately after the discharge lamp 10 is turned off. As described above, the drive resonance capacitor C7 is preset to have a capacitance capable of starting the discharge lamp 10 at the normal temperature.

FIG. 3 shows the first and second switching means Q for the resonance voltage of the feedback drive signal generating circuit 5.
It is an operation | movement figure which shows starting of 1 and Q2. The resonance voltage is
Resistance R to the resonance voltage (AC voltage) of the drive resonance circuit 11
The voltage across both ends of 3 (DC voltage) is superimposed. Therefore, the resonance voltage has a high amplitude on the positive side and a low amplitude on the negative side. Therefore, the first switching means Q1
Is easy to turn on, and the second switching means Q2 is hard to turn on. However, the drive resonance capacitor C
No. 7 is set so as to have a predetermined capacitance even when the ambient temperature is at least 140 to 150 ° C., so that the negative amplitude of the resonance voltage of the feedback drive signal generating circuit 5 is large and the resonance voltage of the positive voltage is high. The resonance voltage turns on the first switching means Q1, and the resonance voltage on the negative side turns on the second switching means Q2. In this way, the feedback drive signal generating circuit 5 is based on the resonance voltage of the drive resonance circuit 11 and the first and second switching means Q1, Q.
2 is alternately switched. This allows
The discharge lamp 10 has a normal temperature, that is, an ambient temperature of the drive resonance capacitor C7 of at least 140.
It is surely started (restarted) at ~ 150 ° C.

Next, the operation of the discharge lamp 10 at the end of the life of the discharge lamp 10 and during abnormal discharge such as abnormal overheating of the filament electrodes 10a and 10b will be described.

At the time of abnormal discharge of the discharge lamp 10, the temperature in the vicinity of the filament electrodes 10a and 10b becomes relatively higher than that at the time of normal discharge, so that the electrostatic capacitance of the drive resonance capacitor C7 becomes relatively small. Resonance capacitance is reduced. That is, as shown in FIG. 2, the ambient temperature of the drive resonance capacitor C7 becomes 160 ° C. or higher, and the capacitance of the drive resonance capacitor C7 decreases by 10% or more. Therefore, the resonance frequency of the drive resonance circuit 11 becomes relatively high, and the operating frequency of the inverter becomes relatively high. Since this operating frequency is higher than the resonant frequency of the load circuit 4, the inverter operates in the lag mode and at an operating frequency relatively far from the resonant frequency. Therefore, the filament electrode 10 of the discharge lamp 10
The output of the inverter applied between a and 10b becomes low, and the discharge lamp 10 is turned off and the output is decreased. Therefore, the discharge lamp 1 is prevented from the abnormal discharge as described above.
0 and other circuit components are protected.

FIG. 4 shows the first and second switching means Q for the resonance voltage of the feedback drive signal generating circuit 5.
It is an operation | movement figure which shows the inactivation of 1 and Q2. The resonance voltage is the drive resonance circuit 1 as described in FIG.
Since the DC voltage generated by the resistor R3 is superimposed on the resonance voltage of No. 1, the amplitude on the negative side is low. Therefore, if the drive resonance capacitor C7 is set to be lower than the predetermined electrostatic capacity at the normal temperature, the amplitude of the resonance voltage on the negative side becomes small, and the second switching means Q2.
Cannot be turned on and the discharge lamp 10 will not be activated.

Even if the drive resonance capacitor C7 is set to a predetermined capacitance at the normal temperature, when the ambient temperature rises to an abnormal temperature, for example, 160 ° C. or higher, the capacitance is greatly reduced, so that the drive resonance is generated. Circuit 1
The resonance voltage of 1 decreases. The resonance voltage of the feedback drive signal generation circuit 5 is particularly low because the DC voltage of the resistor R3 is superimposed on the resonance voltage of the drive resonance circuit 11. As a result, initially, the first switching means Q1 is turned on, but the second switching means Q2 is not turned on. Since the second switching means Q2 is not turned on, the first and second switching means Q1 and Q2 are deactivated and the discharge lamp 10 is deactivated.

The output voltage of the half-bridge type inverter applied to the discharge lamp 10 changes according to the degree of resonance due to the resonance inductance and resonance capacitance of the load circuit 4, and the degree of resonance is the half-bridge type. It changes according to the operating frequency of the inverter. When the half-bridge inverter is in the phase advance mode in which the half bridge inverter operates in the phase advance region of the resonance characteristic curve of the load resonance circuit formed by the resonance inductance and the resonance capacitance of the load circuit 4, when the operating frequency becomes high, the discharge lamp The output voltage applied to 10 rises. On the contrary, in the case of the lag phase mode in which the half-bridge inverter operates in the lag phase region of the resonance characteristic curve of the load resonance circuit, the output voltage applied to the discharge lamp 10 decreases as the operating frequency increases.

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

FIG. 5 is a partially cutaway front view of a light bulb shaped fluorescent lamp showing a second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof is omitted.

The light bulb type fluorescent lamp 13 as an illuminating device shown in FIG. 5 includes a fluorescent lamp 14 as a discharge lamp, a lighting circuit means 15, a cover 16 as an illuminating device main body, a base 17, a globe 18, a partition plate 19 and the like. It is configured.

The fluorescent lamp 14 includes a translucent discharge vessel 20 and a filament electrode (not shown). The translucent discharge vessel 20 has four U-shaped glass tubes 20a having an outer diameter of 10 mm at three locations. Connected and each U-shaped glass tube 20
It is formed so that a is evenly distributed on the circumference. Each U-shaped glass tube 20a is formed with a seal portion 20b at both ends thereof, and each thin tube (not shown) projects from one seal portion 20b to the outside. The thin tube communicates with the inside of the translucent discharge vessel 20, and is used for exhausting the inside of the translucent discharge vessel 20, storing a main amalgam (not shown), and enclosing a rare gas. The connecting pipe 20c is formed by a blowout method. The phosphor layer (not shown) is mainly composed of a three-wavelength light emitting phosphor, and a protective film (not shown) mainly containing alumina fine particles is provided on the inner surface side of the translucent discharge vessel 20. Has been formed. Filament electrode (not shown)
Is a double coil made of a tungsten wire coated with an oxide of an electron emitting substance made of an alkaline earth metal. The main amalgam (not shown) is housed in the thin tube of the translucent discharge vessel 20. The main amalgam is made of, for example, Bi-In-Hg containing 6% by weight of Hg, and encloses three particles having a particle diameter of about 2.5 mm. The auxiliary amalgam (not shown) is made by plating a thin plate of stainless steel with indium In, and is welded to the lead-in wire so as to be located in the vicinity of the main amalgam.

The lighting circuit means 15 is an electric circuit of the discharge lamp lighting device 1 shown in FIG. 1, which energizes the fluorescent lamp 14 to light it, and is housed in the cover 16. The high frequency output end is connected to the fluorescent lamp 14 as required. The lighting circuit means 15 includes a wiring board 21 and circuit components 22 mounted on the wiring board 21, and is mounted on the lower surface of the wiring board 21 in the drawing. on the other hand,
In the circuit component 22, since the cavity inside the cover 16 has an inverted frusto-conical shape, the wiring is made so that the contour becomes a substantially inverted conical shape having the apex of the circuit component such as the tall capacitor C2 in accordance with it. It is mounted on the substrate 21. Further, the pair of switching means Q1 and Q2 are drain exposed mold package type MOSFETs having a DIP terminal.

The cover 16 is formed by molding a white light-shielding heat-resistant synthetic resin into a cup-shaped cylindrical body. Then, the base end 16a is narrowed down, the front end 16b is opened, and the inside forms a cavity for housing the circuit component.

The base 17 is an E26 type base and is attached to the base end 16a of the cover 16 by caulking with a punch. The input end of the lighting circuit means 15 is a base 1
7 center contacts 17a and the base shell 17b.

The globe 18 has a milky white light diffusing property by coating light diffusing fine particles on the inner surface of the transparent glass bulb.
It is A-shaped and surrounds the fluorescent lamp 14. Then, the base end of the globe 18 is connected to the opening at the tip of the cover 16, and the globe 18 and the cover 16 are separated from each other by the envelope 2
3 is formed.

The partition plate 19 supports the fluorescent lamp 14 and the wiring board 21, and divides the inside of the envelope 23 into a light emitting chamber C and a lighting circuit housing chamber D. Further, the partition plate 19 includes the fluorescent lamp 14 and the lighting circuit means 15.
And supports the glove 18 together with the cover 16
The following structure is provided for fixing to. That is, the partition plate 19 is provided with a tubular portion 19a having a closed top portion that is open downward in the figure, and a flange portion 19b that projects to the outside of the tubular portion 19a. Then, the top surface 1 of the tubular portion 19a
The U-shaped glass tube 20 has an insertion hole (not shown) for inserting the vicinity of the seal portion at both ends of the U-shaped glass tube 20a of the translucent discharge vessel 20 of the fluorescent lamp 14 in 9a1.
Insert the vicinity of the seal portion of a and adhere with a silicone adhesive (not shown) to attach the fluorescent lamp 14 to the partition plate 1.
It is supported by 9 and fixed. Further, the wiring board 21 is inserted and supported inside the lower end of the cylindrical portion 19a of the partition plate 19. Further, the partition plate 19 is inserted into the cover 16 so that the collar portion 19b of the partition plate 19 abuts the inner surface of the cover 16 near the opening, and the open end of the globe 18 is inserted into the open end of the cover 16 from above. In this state, they are fixed by a silicone adhesive (not shown).

The compact fluorescent lamp 13 is the fluorescent lamp 14
The temperature inside the cover 16 rises due to the heat generation. The ambient temperature of the drive resonance capacitor C7 is usually 140 when installed in a lighting fixture such as a downlight.
Raise to ~ 150 ° C. Drive resonance capacitor C7
As shown in FIG. 2, the electrostatic capacitance sharply decreases at 140 ° C. or higher. However, it is set so that the voltage required for starting the load circuit 4 can be charged even with an electrostatic capacity at least 150 ° C. That is, 140-1
50 ° C. is a normal temperature, and a drive resonance capacitor C7 having a temperature characteristic capable of restarting the fluorescent lamp 14 even if the temperature rises to the normal temperature is preset.

Further, in the light bulb type fluorescent lamp 13, when the temperature inside the cover 16, that is, the ambient temperature of the drive resonance capacitor C7 further rises due to abnormal heat generation of the fluorescent lamp 14, for example, rises to 160 ° C. or more, the drive resonance capacitor C7 becomes unstable. The capacitance is greatly reduced, and the resonance frequency of the drive resonance circuit 11 is greatly increased. As a result, the resonance voltage due to the resonance inductance and the resonance capacitance of the load circuit 4 is reduced, the output of the fluorescent lamp 14 is reduced, or the fluorescent lamp 14 is turned off.

[0079]

According to the first aspect of the present invention, for example, when the load circuit heats up abnormally, the ambient temperature of the drive resonance capacitor rises, the capacitance changes, and the resonance frequency of the drive resonance circuit changes. Since this resonance frequency acts to reduce the output of the load circuit, abnormal heat generation of the load circuit is reduced, heat damage to the constituent circuit parts can be prevented, and the drive resonance capacitor is Since the temperature characteristic is such that the voltage required for starting becomes the chargeable electrostatic capacity, the discharge lamp can be started reliably.

According to the second aspect of the present invention, the capacitance of the drive resonance capacitor is set so that the discharge lamp can be started at an ambient temperature of at least 140 to 150 ° C. Therefore, the drive resonance capacitor is set to 140% immediately after the discharge lamp is turned off. ~ 150 ° C
The discharge lamp can be reliably turned on even at the ambient temperature of.

According to the invention of claim 3, since the drive resonance capacitor is a ceramic chip capacitor,
It is small and can be set to a desired capacitance with respect to the operating temperature.

According to the invention of claim 4, it is possible to provide an illuminating device in which the output of the discharge lamp is reduced when the discharge lamp abnormally generates heat and the discharge lamp is activated even in a normal high temperature atmosphere.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a discharge lamp lighting device showing a first embodiment of the present invention.

FIG. 2 is a temperature characteristic diagram showing a capacitance change rate with respect to an ambient temperature of a drive resonance capacitor.

FIG. 3 is an operation diagram showing the activation of the first and second switching means with respect to the resonance voltage of the feedback drive signal generation circuit.

FIG. 4 is an operation diagram showing the inactivation of the first and second switching means with respect to the resonance voltage of the feedback drive signal generating circuit.

FIG. 5 is a partially cutaway front view of a light bulb shaped fluorescent lamp showing a second embodiment of the present invention.

FIG. 6 is a circuit diagram of a discharge lamp lighting device showing a prior art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Discharge lamp lighting device, 2 ... DC power supply, 3 ... Switching circuit, 4 ... Load circuit, 5 ... Feedback type drive signal generating circuit, 6 ... Start-up circuit, 13 ... Light bulb type fluorescent lamp as a lighting device, 16 ... Lighting Cover as device body

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiyuki Hiraoka             4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo Toshiba             Inside Litec Co., Ltd. (72) Inventor Tsutomu Araki             4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo Toshiba             Inside Litec Co., Ltd. F term (reference) 3K072 AA02 AC02 AC11 BA03 BC01                       CB06 DC07 DC08 EA03 EB04                       EB06 GA03 GB12 GC02 HA03

Claims (4)

[Claims] 1. A direct current power supply; and a first switching means and a second switching means connected in series with each other between the outputs of the direct current power supply.
A switching circuit having switching means of
A load circuit having a discharge lamp, a resonance inductance, and a resonance electrostatic capacitance and operated by a high-frequency alternating current generated by the alternating switching operation of the first and second switching means; and a feedback winding for feeding back a current flowing through the load circuit. It has a drive resonance circuit configured to include a drive resonance inductor that resonates with the feedback voltage generated in the feedback winding and a drive resonance capacitor whose capacitance changes with temperature changes. Of the first and second switching means are alternately controlled based on the resonance voltage of the drive resonance circuit so that the capacitance of the drive resonance circuit changes and the resonance frequency of the drive resonance circuit changes to decrease the output of the load circuit. A feedback drive signal generating circuit configured to:
A drive circuit that operates at least one of the first and second switching means by applying a voltage to the DC power supply; and the drive resonance capacitor has an electrostatic capacity capable of charging a voltage required for start-up at a normal temperature. A discharge lamp lighting device characterized by having such temperature characteristics. 2. The discharge lamp lighting device according to claim 1, wherein the drive resonance capacitor has an electrostatic capacity set so as to start the discharge lamp at an ambient temperature of at least 140 to 150 ° C. 3. The discharge lamp lighting device according to claim 1, wherein the drive resonance capacitor is a ceramic chip capacitor. 4. A lighting device comprising: a lighting device main body; and the discharge lamp lighting device according to claim 1, which is provided in the lighting device main body.