JPH10340791A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device wherein filament preheating is made appropriate. SOLUTION: Transistors Q1, Q2 are on-off controlled at a frequency different from a frequency established in a series resonance circuit 6, until a trigger is outputted to a control circuit 4 by a trigger circuit 7. Filaments FLa, FLb of a fluorescent lamp FL are preheated by filament-preheating windings Tr2b, Tr2c at a fixed preheating voltage lower than that in a lighting state. A current flowing in the filament FLb is converted into a voltage value by a shunt resistance R1 and, when this voltage becomes equal to or falls below a preset value, the trigger circuit 7 triggers the control circuit 4. The transistor Q1 and the transistor Q2 are on-off controlled to the resonance frequency of the series resonance circuit 6 by the control circuit 4, a starting secondary voltage is generated in the fluorescent lamp FL, and a lighting state of a voltage higher than a preheating state is brought about, causing the fluorescent lamp FL to be started/lighted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a discharge lamp lighting device for lighting a discharge lamp by preheating a filament.

[0002]

2. Description of the Related Art Conventionally, as a discharge lamp lighting device of this type, for example, a configuration shown in FIG. 4 is known. This figure 4
In the discharge lamp lighting device shown in FIG. 1, a noise filter circuit 1 is connected to a commercial AC power supply e, and the noise filter circuit 1 has a capacitor C1, a common mode choke Tr1, and a capacitor C2. The input terminal of the full-wave rectifier circuit 2 such as a diode bridge is connected, and the output terminal of the full-wave rectifier circuit 2 is connected to a smoothing capacitor C3.

The capacitor C3 includes a series-resonant half-bridge type inverter for high frequency which can be changed between a preheating state for outputting a preheating voltage and a lighting state for outputting a lighting voltage higher than the preheating voltage. Circuit 3 is connected. In the inverter circuit 3, a transistor Q1 and a transistor Q2 are connected in series.
The control circuit 4 is connected to the base of the transistor Q2, and the control circuit 4 is connected to a timer circuit 5 which passes a predetermined time from the start.

One end of each of filaments FLa and FLb of a fluorescent lamp FL as a discharge lamp is connected between the collector and the emitter of the transistor Q2, and a series resonance circuit 6 is connected via a ballast choke L1. The series resonance circuit 6 includes a resonance capacitor C4
And a series circuit of a primary winding Tr2a of the filament preheating transformer Tr2 and a DC cut capacitor C5 are connected in parallel.

Further, the filaments FLa and FLb are provided with a filament preheating winding Tr of a filament preheating transformer Tr2.
2b and Tr2c are connected.

Then, the AC voltage of the commercial AC power supply e is full-wave rectified by the full-wave rectifier circuit 2 via the noise filter circuit 1, and is smoothed by the capacitor C3. Further, the output of the inverter circuit 3 is varied by turning on and off the transistor Q1 and the transistor Q2 alternately by the control circuit 4 and changing the on / off frequency.

That is, for a predetermined time measured by the timer circuit 5 after the power is turned on, the transistors Q1 and Q2 are controlled to be turned on and off at a frequency different from the frequency set by the series resonance circuit 6, and the filament preheating winding Tr2b ,
The filaments FLa and FLb of the fluorescent lamp FL are preheated at a voltage lower than the lighting state by the Tr2c.

After the timer circuit 5 has counted a predetermined time, the control circuit 4 controls the transistors Q1 and Q2 to be turned on and off at the resonance frequency of the series resonance circuit 6 so that the lighting state is higher than the preheating state. Start and turn on the fluorescent lamp FL.

[0009]

However, in the above-described conventional discharge lamp lighting device, the filaments FLa and FLb are always preheated by the timer circuit 5 only for a certain period of time.
For example, at low temperatures, preheating is insufficient and filament FLa
, FLb, and the life of the discharge lamp FL is shortened due to blackening of the discharge lamp FL, and flickering and faults occur.

On the other hand, if the filaments FLa and FLb are preheated for an unnecessarily long preheating time by, for example, re-lighting of the fluorescent lamp FL, the fluorescent lamp FL is activated and the fluorescent lamp FL is activated.
For example, there is a problem that a secondary voltage is generated when the FL is turned on again.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a discharge lamp lighting device in which filament preheating is appropriately performed.

[0012]

According to a first aspect of the present invention, there is provided a discharge lamp lighting device including a lighting state in which a discharge lamp having a filament is preheated and a voltage higher than the preheating state is output to light the discharge lamp. A lighting circuit having a filament temperature detecting means for detecting the temperature of the filament of the discharge lamp; and, when the temperature of the filament detected by the filament temperature detecting means is equal to or higher than a predetermined value, the lighting circuit is changed from a preheated state to a lighting state. And a control circuit for starting and lighting the discharge lamp.The filament temperature detecting means detects the temperature of the filament, and when the temperature of the filament exceeds a predetermined value, the control circuit changes the lighting circuit from the preheating state to the lighting state. Since the discharge lamp is started and turned on, it always lights up when the filament temperature is appropriate. To prevent insufficient preheating or preheating excess of the filament.

A lighting circuit having a lighting state for lighting a discharge lamp by outputting a voltage higher than the preheating state together with a preheating state for preheating the discharge lamp having a filament and the discharge lamp having the filament, A filament resistance detecting means for detecting a resistance value of a filament of the discharge lamp; and, if the resistance value of the filament detected by the filament resistance detecting means is a predetermined value or more, the lighting circuit is changed from a preheated state to a lighting state to start the discharge lamp. Since the resistance value of the filament rises when the filament is preheated, the resistance value of the filament is detected by the filament resistance detection means, and when the resistance value of the filament exceeds a predetermined value. The control circuit sets the lighting circuit from the preheating state to the lighting state, and starts the discharge lamp and lights it Since the always temperature of the filament is turned in the proper state, to prevent insufficient preheating or preheating excessive filament.

[0014] According to a third aspect of the present invention, there is provided a discharge lamp lighting device having a lighting state in which a discharge lamp having a filament is preheated at a constant voltage value and a voltage higher than the preheating state is output to light the discharge lamp. A circuit, a filament current detecting means for detecting a current value flowing through the filament of the discharge lamp, and, when the current value of the filament detected by the filament current detecting means is a predetermined value or less, the lighting circuit is changed from a preheated state to a lighting state. And a control circuit for starting and lighting the discharge lamp. When the filament is preheated, the resistance value of the filament increases, and when the voltage is constant, the current decreases. The control circuit detects the value of the current flowing through the lighting circuit, and when the current value exceeds a predetermined value, the control circuit prepares the lighting circuit. Since from the state to the lighting state starting to light the discharge lamp, always the temperature of the filament is turned in the proper state, to prevent insufficient preheating or preheating excessive filament.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the discharge lamp lighting device according to the present invention will be described with reference to the drawings. Parts corresponding to those of the conventional example shown in FIG.

In the discharge lamp lighting device shown in FIG. 1, a noise filter circuit 1 is connected to a commercial AC power supply e, and the noise filter circuit 1 has a capacitor C1, a common mode choke Tr1, and a capacitor C2. The input terminal of a full-wave rectifier circuit 2 such as a diode bridge is connected to the noise filter circuit 1, and the output terminal of the full-wave rectifier circuit 2 is connected to a smoothing capacitor C3.

The capacitor C3 has a high frequency series resonance type half-wave as a lighting circuit that can be changed between a preheating state in which a voltage for preheating is output and a lighting state in which a voltage for lighting higher than the preheating is output. A bridge type inverter circuit 3 is connected. In the inverter circuit 3, a transistor Q1 and a transistor Q2 are connected in series, and the bases of the transistor Q1 and the transistor Q2 are
The control circuit 4 is connected.

One end of each of the filaments FLa and FLb of the fluorescent lamp FL as a discharge lamp is connected between the collector and the emitter of the transistor Q2, and the series resonance circuit 6 is connected via a ballast choke L1. The series resonance circuit 6 includes a resonance capacitor C4
And a series circuit of a primary winding Tr2a of the filament preheating transformer Tr2 and a DC cut capacitor C5 are connected in parallel.

Further, the filament preheating winding Tr of the filament preheating transformer Tr2 is connected to the filaments FLa and FLb.
2b and Tr2c are connected, and a shunt resistor R1 for converting a current into a voltage is connected between the filament FLb and the filament preheating winding Tr2c.

The shunt resistor R1 has a filament temperature detecting means for detecting the voltage of the shunt resistor R1,
A trigger circuit 7 as a filament resistance detecting means and a filament current detecting means is connected, and the trigger circuit 7 is connected to the control circuit 4.

Next, the operation of the above embodiment will be described.

First, the AC voltage of the commercial AC power supply e is full-wave rectified by the full-wave rectifier circuit 2 via the noise filter circuit 1,
Smooth with capacitor C3. Until the trigger circuit 7 outputs a trigger to the control circuit 4, the series resonance circuit 6
The transistor Q1 and the transistor Q2 are alternately turned on and off by the control circuit 4 at a frequency different from the resonance frequency of the inverter circuit 3 to lower the output of the inverter circuit 3.

That is, until the trigger circuit 7 triggers, the transistors Q1 and Q2 are controlled to be turned on and off at a frequency different from the frequency set by the series resonance circuit 6, and the lighting state is controlled by the filament preheating windings Tr2b and Tr2c. The filaments FLa and FLb of the fluorescent lamp FL are preheated at a lower constant preheating voltage.

Then, the filament FL is set by the shunt resistor R1.
The current flowing through b is converted into a voltage value, and when this voltage falls below a predetermined value and the trigger circuit 7 triggers the control circuit 4,
The control circuit 4 controls the transistors Q1 and Q2 to be turned on and off at the resonance frequency of the series resonance circuit 6, and a starting secondary voltage is generated in the fluorescent lamp FL. Starts and lights up.

Here, the relationship among the resistance value, voltage value and current value of the filaments FLa and FLb will be described with reference to FIG. From the inverter circuit 3, as shown in FIG.
When the voltage value is kept constant, the filaments FLa, FLb
When the temperature of the filaments FLa and FLb rises, the resistance value rises as shown in FIG. 2 (a) and the voltage is constant, so that the filaments FLa and FLb become constant as shown in FIG. 2 (c). The current flowing through FLa and FLb decreases.

Therefore, when the voltage of the shunt resistor R1 falls below a predetermined value, the filament FLb is properly preheated. Therefore, the preheating temperature of the filament FLb can be determined by detecting the voltage of the shunt resistor R1. Can start the fluorescent lamp FL at an appropriate temperature.

Next, another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 1 in that a current transformer CT1 is used instead of the shunt resistor R1, and the current transformer CT1 is connected between the filament FLb and the filament preheating winding Tr2c. Primary winding CT1a
And the secondary winding CT1b of the current transformer CT1 is connected to the trigger circuit 7.

When the current flowing through the secondary winding CT1b of the current transformer CT1 becomes equal to or less than a predetermined value, the trigger circuit 7 triggers and the control circuit operates basically in the same manner as the embodiment shown in FIG. 4, the output of the inverter circuit 3 is increased.

Therefore, in any case, the filaments FLa and FLb are appropriately preheated, so that the preheating is insufficient at a low temperature, and the filaments FLa and FLb are burdened.
It is possible to prevent the life of the fluorescent lamp FL from shortening due to blackening, the occurrence of flickering, and the occurrence of defects.

Further, it is possible to prevent the filaments FLa and FLb from being preheated for an unnecessarily long preheating time due to the re-lighting of the fluorescent lamp FL and the like. Generation of a secondary voltage can also be prevented.

[0032]

According to the discharge lamp lighting device of the first aspect, the filament temperature is detected by the filament temperature detecting means, and when the filament temperature exceeds a predetermined value, the control circuit changes the lighting circuit from the preheating state to the lighting state. Then, the discharge lamp is started and turned on, so that the filament is always turned on at an appropriate temperature, and insufficient preheating or excessive preheating of the filament can be prevented.

According to the discharge lamp lighting device of the second aspect,
When the filament is preheated, the resistance value of the filament rises. Therefore, the resistance value of the filament is detected by the filament resistance detection means, and when the resistance value of the filament exceeds a predetermined value, the control circuit changes the lighting circuit from the preheated state to the lighting state. Since the discharge lamp is started and turned on, the filament is always turned on with an appropriate temperature of the filament, so that insufficient preheating or excessive preheating of the filament can be prevented.

According to the discharge lamp lighting device of the third aspect,
When the filament is preheated, the resistance value of the filament increases, and when the voltage is constant, the current decreases.Therefore, the current value flowing through the filament is detected by the filament current detection means, and control is performed when the current value exceeds a predetermined value. Since the circuit starts the lighting of the discharge lamp by changing the lighting circuit from the preheating state to the lighting state, the lighting is always performed in a state in which the temperature of the filament is appropriate, and insufficient preheating or excessive preheating of the filament can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a graph showing a relationship among a resistance value, a voltage value, and a current value of the filament.

FIG. 3 is a circuit diagram showing a discharge lamp lighting device according to another embodiment of the present invention.

FIG. 4 is a circuit diagram showing a conventional discharge lamp lighting device.

[Explanation of symbols]

3 Inverter circuit as lighting circuit 4 Control circuit 7 Trigger circuit as filament temperature detecting means, filament resistance detecting means and filament current detecting means FL Fluorescent lamps FLa and FLb filaments as discharge lamps

Claims (3)

[Claims] 1. A lighting circuit having a lighting state for lighting a discharge lamp by outputting a voltage higher than the preheating state together with a preheating state for preheating a filament in a discharge lamp having a filament, and detecting a temperature of a filament of the discharge lamp. A filament temperature detecting means, and a control circuit for starting and lighting a discharge lamp by changing the lighting circuit from a preheated state to a lighting state when the temperature of the filament detected by the filament temperature detecting means is a predetermined value or more. Discharge lamp lighting device. 2. A lighting circuit having a lighting state for lighting a discharge lamp by outputting a voltage higher than the preheating state together with a preheating state for preheating the discharge lamp having the filament and detecting a resistance value of the filament of the discharge lamp. And a control circuit for starting and lighting the discharge lamp by changing the lighting circuit from the preheating state to the lighting state when the resistance value of the filament detected by the filament resistance detecting means is equal to or more than a predetermined value. Discharge lamp lighting device characterized by the above-mentioned. 3. A lighting circuit having a lighting state in which a discharge lamp having a filament is preheated at a constant voltage value and a voltage higher than the preheating state is output to light the discharge lamp, and a filament of the discharge lamp is provided. A filament current detecting means for detecting a flowing current value, and a control for starting and lighting a discharge lamp by changing the lighting circuit from a preheated state to a lighting state when the filament current value detected by the filament current detecting means is a predetermined value or less. A lighting device for a discharge lamp, comprising: a circuit;