JP2000173789A - Lighting device of discharge tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the preheating time of a discharge tube and prevent the heat generation and damage of a lighting device. SOLUTION: A first series circuit 10, comprising an FET Q1 and a source resistor R3, and a second series circuit 20 comprising a thyristor Q2 and a series resistor R1 are connected, through a reverse current preventing diode D1, in parallel with filament terminals f2, f2' of a fluorescent lamp FL connected to a stabilizer CH, the connection point of the thyristor Q2 to the series resistor R1 is connected to a gate terminal G of the FET Q1 to turn on the FET Q1 at the turning-on of power to carry a preheating current, a trigger signal having a predetermined voltage value is input to the thyristor Q2 from a trigger circuit 30 to turn off the FET Q1, and thereby, the preheating time is reduced with a steep kick voltage. Heat generation and damage to a lighting device 1 is prevented by forming an integrating circuit for absorbing noise, a first timer for limiting the preheating, and a second timer for performing the preheating for a predetermined time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge tube lighting device using an FET.

[0002]

2. Description of the Related Art As a lighting device for a discharge tube, for example, a fluorescent lamp, a device using a glow lamp has been well known.

As shown in FIG. 7, this lighting device has two filament terminals f1, f2, f1'f2 'at each end.
One of the filament terminals at one end of the fluorescent lamp FL provided with
1 is connected to one of the AC power terminals a via a ballast CH, one of the filament terminals f1 'at the other end is connected to the other a' of the AC power terminals, and the other filament terminals f2 and f2 'are glowed. By connecting the lamp GL, the connected glow lamp GL is turned on to preheat the filament of the fluorescent lamp FL for a certain period of time, and then turned off, so that the ballast CH generates a high pressure pulse for starting. is there.

[0004]

However, in the above-described lighting device, the remaining heat time is constant due to the structure of the glow lamp. Therefore, depending on the fluorescent lamp, there is a problem that the residual heat is too much or insufficient (especially a terminal tube).

That is, since a new fluorescent lamp has too much residual heat, blackening occurs quickly and shortens the life. on the other hand,
Since the end tube has insufficient heat, it fails to light and repeats the heat many times. As a result, an overcurrent or an overvoltage occurs, which causes a problem that the ballast generates heat and the lighting device is damaged.

[0006] Therefore, an object of the present invention is to firstly reduce the residual heat time, to ensure reliable lighting even if the residual heat is reduced, and to improve the lighting and starting time. An object of the present invention is to prevent overcurrent and overvoltage from occurring due to reliable transient operation, thereby preventing heat generation of the ballast and damage to the lighting device.

[0007]

In order to solve the above-mentioned problems, in claim 1, two filament terminals are provided at both ends, and one of the filament terminals at one end is connected to one of the AC power supply terminals via a ballast. A lighting device for a discharge tube connected to the other filament terminal of a discharge tube in which one of the filament terminals at the other end is connected to the other AC power supply terminal, wherein the lighting device comprises one of a source or drain terminal of an FET. Or a first series circuit having a resistor connected to both, a second series circuit including a three-terminal switch element such as a transistor or thyristor having a gate terminal and a series resistor connected in series to the switching element;
A trigger circuit, comprising a backflow prevention diode, connecting one end of the first series circuit and one end of the second series circuit to the other one of the filament terminals on one end connected to the ballast of the discharge tube; A common return of the first and second series circuits is connected to an anode terminal of a backflow prevention diode, and a cathode terminal of the connected diode is connected to the other of the filament terminals on the other end of the discharge tube. The gate terminal of the FET of the first series circuit was connected to the connection point of the switching element and the series resistor of the second series circuit, and the trigger circuit was connected to the other of the filament terminals on one end side of the discharge tube. After applying power in the configuration, when a predetermined voltage is reached, a trigger signal is input to the gate terminal of the second series circuit, and the gate voltage of the FET is reduced by the switching element. To adopt a configuration that blocks the drain current.

By employing such a configuration, when the voltage on the ballast side starts rising from 0 V in the positive direction, for example, the FET is turned on by the voltage applied to the gate terminal via the second series circuit. And the residual heat current flows through the filament. When the power supply voltage reaches a predetermined voltage, the trigger circuit is turned on and a trigger signal is input to the control terminal of the second series circuit. Then, the second series circuit is:
Since the gate voltage is applied so that the FET interrupts the current, the FET is turned off and interrupts the residual heat current. As a result, a kick voltage is generated from the ballast and applied between the filaments of the discharge tube. At this time, since the FET can perform high-speed switching without the effect of accumulating carriers, it is possible to generate a steep kick voltage having a high peak value.

On the other hand, when the AC power supplied from the ballast is at a negative potential, the backflow preventing diode is in the reverse direction, so that the preheating operation is not performed and the power supply voltage is applied between the filaments.

[0010] By repeating such an operation for each cycle of the AC power supply, the operation is shifted to normal lighting.

According to a second aspect of the present invention, the configuration in which the integrating circuit is connected to the gate terminal of the FET is employed to remove unnecessary noise components input to the gate terminal by the time constant of the integrating circuit so as to start up or turn on the light. Prevents occurrence of overcurrent and overvoltage due to uncertain transient operation at the time.

According to a third aspect of the present invention, the lighting device is provided with a first timer means, and the lighting device is turned off after a lapse of a predetermined time. Operates to turn off the lighting circuit, thereby preventing unnecessary heat generation of the ballast and damage to the lighting device.

According to a fourth aspect of the present invention, a second timer means is added to the three-terminal switching element of the lighting device, and the operation start time of the switching element is delayed within the time from the start of the preheating to the turning off of the lighting device. By providing a predetermined remaining heat time, stable initial lighting is realized, and for example, deterioration or blackening of the filament of the fluorescent lamp is prevented.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment.

The lighting device 1 for a discharge tube of this embodiment is a lighting device 1 for a fluorescent lamp FL. The fluorescent lamp FL has two filament terminals f1, f2, f1 ', f2' at each end, and one of the filament terminals f1, f2 at one end.
Is connected to one of the AC power supply terminals a via a ballast CH. One of the other filament terminals f1 'and f2' is connected to the other a 'of the AC power supply terminal, and the lighting device 1 is connected to the other filament terminals f2 and f2'. .

In this embodiment, the lighting device 1 includes an N-channel power MOSFET (field effect transistor, hereinafter referred to as FET) Q1, a source resistor R3, a series resistor R1, a thyristor Q2, a Zener diode ZD, a resistor R2 and a backflow prevention device. It is composed of a diode D1. FET Q1
Has a source terminal S connected to a source resistor R3 to form a first series circuit 10.

Further, the series resistor R1 is connected to the anode terminal A of the thyristor Q2 provided as a three-terminal switch element to form a second series circuit 20.

The drain terminal D of the FET Q1 of the first series circuit 10 and the other end of the series resistor R1 of the second series circuit 20 are connected to the other one of the filament terminals f2 at one end of the fluorescent lamp FL.

On the other hand, the source resistance R of the first series circuit 10
3 and the cathode terminal K of the thyristor Q2 of the second series circuit 20, that is, the common return path of the first series circuit 10 and the second series circuit is connected to the anode terminal of the backflow prevention diode D1. The cathode terminal of the connected diode D1 is connected to the other filament terminal f2 'at the other end of the fluorescent lamp FL.

The FET Q1 of the first series circuit 10
Is connected to the series resistor R1 of the second series circuit 20.
And the connection point of the thyristor Q2.

Further, a trigger circuit 30 is formed by connecting the anode terminal of the Zener diode ZD and the current limiting resistor R2 in series, and the cathode terminal of the Zener diode ZD of the trigger circuit 30 is connected to the filament terminal of the fluorescent lamp FL. The other end is connected to the other end of the resistor end R2.
Is connected to the gate terminal G1 of the thyristor Q2.

Reference numeral C1 in the drawing denotes a capacitor for shaping the gate input waveform of the FET Q1 and preventing malfunction.

This embodiment is configured as described above, and FIG.
As shown in FIG.
Enter Now, when the a side of the AC power supply terminal becomes positive and the power supply voltage Vac rises from 0 V, the voltage rises from 0 V to the ballast CH → the filaments f1 and f2 of the fluorescent lamp FL → the series resistance R1 → the gate terminal G of the FET Q1. The voltage is applied to turn on the FET Q1. At this time, the FET Q1
Is turned on above a relatively low threshold voltage (up to about 4 V) because of the self-biasing operation by the source resistance R3, and has an effect of preventing overheating of the FET Q1 from damage due to overcurrent.

Therefore, when the FET Q1 is turned on, the power supply AC is switched to the power supply terminal a → the filament terminals f1, f2 at one end of the fluorescent lamp FL → the FET Q1 → the source resistance R3 → the backflow prevention diode D1 → the filament at the other end of the fluorescent lamp FL. Terminals f1 ', f2' → power supply terminal a 'and residual heat current Id
Starts flowing residual heat (see Id in FIG. 2).

After the start of preheating, when the increased tube voltage vt reaches a predetermined voltage, for example, when the phase angle of the voltage reaches around 150 ° (see the tube voltage Vac in FIG. 2), the trigger circuit 30 is activated. Is turned on, and the gate G1 of the thyristor Q2 is connected via the resistor R2.
Drive. Therefore, the voltage between the gate and the source of the FET Q1 becomes lower than the threshold voltage, and the FET Q1 is turned off. At this time, FET with excellent switching characteristics
Since the residual heat current Id is rapidly cut off by Q1, the ballast CH generates a steep, high-peak kick voltage vp. The generated kick voltage vp is applied between the filament terminals f1, f2 and f1 ′, f2 ′ of the fluorescent lamp FL.

On the other hand, when the terminal a is negative, the backflow prevention diode D1 is in the reverse direction, so that no preheating of the filament terminals f1, f2, f1 ', f2' is performed, and the power supply voltage Vac is reduced by the filament of the fluorescent lamp FL. Terminals f1, f2,
It is applied between f1 'and f2'.

Such a cycle is repeated (for example,
60HZ) and discharge (= lighting). Therefore, in the fully lit state, the filament terminals f1, f1 of the fluorescent lamp FL
A tube voltage vt is generated between f2, f1 ', and f2', and in the fully lit state, the tube voltage vt is applied to both the positive and negative cycles.

As described above, F is excellent in switching characteristics.
Since the kick voltage vp that is steep and has a high peak can be generated from the first cycle by the ETQ1, the fluorescent lamp F
Lighting of L (self-discharge) can be easily excited, and the remaining heat time can be reduced. Further, it is possible to prevent a lighting failure due to a shortage of residual heat even in the terminal tube.

FIG. 3 shows a second embodiment.

This embodiment is similar to the lighting device 1 of the first embodiment.
2 shows an integrated circuit 40 provided with an integrating circuit 40 so as to prevent the occurrence of overcurrent and overvoltage due to uncertain transient operation at the time of lighting or starting.

The integration circuit 40 of this embodiment includes a transistor Q3, a capacitor C2, a discharge resistor R5 and a resistor R6.

The transistor Q3 is a PNP transistor whose emitter terminal is connected to the gate terminal of the FET Q1,
The collector is connected to the anode of the backflow prevention diode D1 to form an emitter follower circuit, a feedback circuit is provided by a capacitor C2 from the emitter terminal of the emitter follower circuit to the base terminal, and a resistor R6 is inserted in series to the base terminal. It forms a Miller integrating circuit,
The input resistor R6 is connected to the source terminal S of the FET Q1.

As shown in FIG. 3, the integrating circuit 40 thus provided superimposes the integrated voltage vg based on the residual heat current Id detected by the source resistor R3 on the gate terminal G of the FET Q1. The integrated voltage vg has a slope based on a time constant (input resistance and feedback capacitor). By appropriately setting the slope, the excessive initial drive current and peak value of the gate voltage are absorbed and corrected. Of the gate voltage due to instantaneous interruption, instantaneous interruption, etc.

Therefore, it is possible to prevent the occurrence of overcurrent and overvoltage due to uncertain transient operation at the time of lighting or starting.
In particular, unnecessary heat generation of the ballast and breakage of the lighting device can be prevented in the terminal tube.

In addition, the lighting device 1 includes a noise preventing capacitor C4 and a fuse resistor R as safety measures.
4. A speed-up capacitor C3 and the like are provided.

The noise prevention capacitor C4 is for preventing malfunction due to noise. The fuse resistor R4 is used to prevent an accident due to fusing when an excessive current flows due to breakage of the lighting device 1 or the like. As what can be used in the same way as this fuse resistor R4,
A PTC (positive characteristic temperature sensitive element) may be used. PTC is
The circuit current can be limited by generating heat due to the overcurrent and rapidly increasing the resistance value.

The speed-up capacitor C3 is for speeding up the gate signal of the thyristor Q2, and is for surely triggering.

The other parts and operations are the same as those described in the first embodiment.

FIG. 4 shows a third embodiment.

In this embodiment, a transistor Q2 'is used in place of the thyristor Q2 of the lighting device shown in FIG.

In this case, the transistor Q2 '
An NPN transistor having a collector terminal connected to one end of the series resistor R1 and an emitter terminal connected to a backflow prevention diode D1.
Connected to the anode terminal. Further, the base terminal is connected to the resistor R2 of the trigger circuit 30.

The transistor Q2 'thus provided
Means that the saturation voltage between the collector and emitter terminals is 0.1 V
The saturation voltage between the anode and cathode terminals of the thyristor Q2 is lower than 0.7V. Therefore, FETQ
1 can be turned off sufficiently.

Therefore, the cost can be reduced by using the transistor Q2 'which is lower in price than the thyristor Q2.

The resistor R7 in FIG. 4 has one end connected to the cathode of the backflow prevention diode D1 and applies a reverse bias to the base circuit of the transistor Q2 'by the amount of the forward voltage of the backflow prevention diode D1. Thus, the switching characteristics are improved.

The other parts and operations are the same as those described in the first and second embodiments, and thus the same reference numerals are given and the description thereof will be omitted.

FIG. 5 shows a fourth embodiment.

This embodiment includes an integrating circuit 40 'using an integrating capacitor C5 instead of the Miller integrating circuit 40 of the third embodiment shown in FIG.
0 is provided.

As shown in FIG. 5, the integrating circuit 40 'comprises an integrating capacitor C5 and a resistor R8. The other end of the resistor R8 of this series circuit is connected to the other of the filament terminals f2.
And the other end of the integrating capacitor C5 is connected to the anode terminal of the backflow prevention diode D1. By connecting the connection point connecting the integrating capacitor C5 and the resistor R8 to the base of the transistor Q3, for example, when the voltage at the terminal a increases from 0 V in the positive direction, the transistor Q2 'is off and the power supply voltage AC Is input to the gate terminal G of the FET Q1 via the series resistor R1. At this time, since the integrating capacitor C5 is 0V, the transistor Q3
Is turned on, and the gate signal does not flow to the gate terminal of the FET Q1.

Thereafter, when the voltage of the capacitor C5 charged via the resistor R8 increases and the transistor Q3 turns off, the gate voltage input to the FET Q1 increases,
FET Q1 is turned on.

As described above, by providing the integrating circuit 40 ', as in the second embodiment, the excessive initial drive current and peak value of the gate voltage are absorbed and corrected. It is possible to absorb a change in gate voltage due to an instantaneous stop or the like.

On the other hand, the first timer circuit 50 comprises a timer capacitor C6, a timer resistor R9, and a transistor Q4. The other end of the timer resistor R9 is connected to the integration circuit 40 '.
To the connection point between the integrating capacitor C5 and the resistor R8,
Connect the other end of the timer capacitor C6 to the backflow prevention diode D1.
Connected to the anode end of The connection point between the timer capacitor C6 and the timer resistor R9 is connected to the base terminal of the transistor Q3, and the collector terminal of the transistor Q3 connected to the timer capacitor C6 and the timer resistor R9 is connected to the base terminal of the transistor Q4. .

Therefore, when the voltage of the timer capacitor C6 exceeds the saturation voltage (Vce) of the transistor Q4, the transistor Q4 turns on and the transistor Q3 turns on.

In this manner, the lighting device 1 can be turned off after a lapse of a predetermined time from energization. For example, by appropriately setting the time constants of the timer capacitor C6 and the timer resistor R9, the end of life can be achieved. When the lighting operation is repeated, the lighting device 1 is turned off to prevent unnecessary heat generation of the ballast CH and damage to the lighting device.

The other parts and operations are the same as those described in the first to third embodiments, and therefore the same reference numerals are given and the description thereof will be omitted.

FIG. 6 shows a fifth embodiment.

This embodiment is different from the switching device of the second series circuit of the fourth embodiment shown in FIG.
2 'is provided with a second timer circuit 60.

As shown in FIG. 6, the second timer circuit 60 comprises a transistor Q5, an integrating capacitor C7, and a charging resistor R10. The transistor Q5 is inserted in series with the emitter return path of the transistor Q2 '. A capacitor C7 and a resistor R are connected to the anode end of the diode D1.
10 is connected.

In this embodiment, when the power is turned on, for example, immediately after the start of the preheating of the fluorescent lamp FL, the charge of the integrating capacitor C7 is 0 V, so that the switching element Q2 'is off and inoperative. Thereafter, when the charge of C7 exceeds the threshold level value of Q5 by the charge resistor R10, Q5 is turned on. Thereafter, the transistor Q2 'is kept in the operating state, and the same lighting operation as in the fourth embodiment is performed. .

In this embodiment, the second timer circuit 60, that is, the FET Q1 sets the charging time constant of C7 and R10 to the first time.
The switching element can be operated after the elapse of the sufficient heat-up time necessary for the fluorescent lamp FL by appropriately setting the time before the timer circuit 50 shuts off, so that the blackening of the fluorescent lamp FL is reduced, and stable and reliable reproduction is achieved. A lighting device with excellent performance can be provided.

The other parts and functions of the present embodiment are described below.
Since they are the same as the first to fourth embodiments, they are denoted by the same reference numerals,
The description is omitted.

In this embodiment, the transistor using the transistor Q2 'as the three-terminal switching element has been described, but the present invention is not limited to this. For example, it is obvious that another switching element such as the thyristor Q2 described above may be used.

In each of the above embodiments, an N-channel FET is used. However, the present invention is not limited to this, and a P-channel FET may be used. At this time,
The connection type between the element type of the second series circuit (for example, NPN and PNP in the case of a transistor) and the resistor is appropriately set so that when a trigger signal is input, a gate voltage that allows the FET to cut off the current can be applied. It is set.

[0064]

According to the present invention, since the present invention is configured as described above, the remaining heat time can be shortened, and the occurrence of overcurrent and overvoltage due to uncertain transient operation at the time of lighting or starting can be prevented. Heat of the ballast and damage to the lighting device can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment.

FIG. 2 is a diagram showing voltage and current characteristics of the first embodiment.

FIG. 3 is a block diagram of a second embodiment.

FIG. 4 is a block diagram of a third embodiment.

FIG. 5 is a block diagram of a fourth embodiment;

FIG. 6 is a block diagram of a fifth embodiment.

FIG. 7 is a block diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 lighting device 10 first series circuit 20 second series circuit 30 trigger circuit 40 integration circuit 40 'integration circuit 50 timer circuit 60 second timer circuit a AC power supply terminal a' AC power supply terminal C1 Malfunction prevention capacitor C2 Capacitor C3 Speed-up capacitor C4 Noise prevention capacitor C5 Integrating capacitor C6 Timer capacitor C7 Charging capacitor f1 Filament terminal f1 'Filament terminal f2 Filament terminal f2' Filament terminal D1 Backflow prevention diode FL Fluorescent lamp CH Ballast Q1 Power MOSFET Q2 Thyristor Q2 ' Transistor Q5 Transistor R1 Series resistance R2 Resistance R3 Source resistance R10 Resistance ZD Zener diode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shozo Hirao 3-7-1001, Daito-cho, Miyakojima-ku, Osaka-shi, Osaka F-term (reference) 3K083 AA09 AA18 AA20 AA22 AA24 AA45 BA12 BB05 BB08 BB10 BB14 BC13 BC34 BE12 CA38

Claims (4)

[Claims] 1. Two filament terminals are provided at both ends, one of the filament terminals at one end is connected to one of the AC power terminals via a ballast, and one of the filament terminals at the other end is connected to the other AC power terminal. A lighting device for a discharge tube connected to the other filament terminal of the connected discharge tube, wherein the lighting device includes a first series connection in which a resistor is connected to one or both of a drain and a source terminal of an FET (field effect transistor). A second series circuit including a circuit, a three-terminal switch element such as a transistor or a thyristor having a gate terminal, and a series resistor connected in series to the switching element; a trigger circuit; and a backflow prevention diode. A filament terminal at one end where one end of the first series circuit and one end of the second series circuit are connected to a ballast of the discharge tube; Connected to the other end, the common return of the first and second series circuits is connected to the anode terminal of the backflow prevention diode, and the connected cathode terminal is connected to the other of the filament terminals on the other end side of the discharge tube. Connect with
Connecting the gate terminal of the FET of the first series circuit, the switching element of the second series circuit, and the connection point of the series resistor,
And when the trigger circuit is connected to the other of the filament terminals on one end side of the discharge tube and reaches a predetermined discharge voltage,
A lighting device for a discharge tube, wherein a trigger signal is input to a gate terminal of a second series circuit to cut off a main current of an FET energized by the switching element. 2. The discharge tube lighting device according to claim 1, wherein an integration circuit is connected to the gate circuit of the FET. 3. The lighting device for a discharge tube according to claim 1, wherein a first timer means is provided in said lighting device, and the lighting device is turned off after a predetermined time has elapsed. 4. The switching device of the lighting device according to claim 2,
The lighting device for a discharge tube according to any one of claims 1 to 3, wherein the timer means is provided to start lighting after a predetermined remaining heat time has elapsed.