JPH0355795A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To obtain stable lighting even in connection to a phase control light adjustor by setting a running angle of the phase control light adjustor for starting initial operation larger than that for lighting off a discharge lamp after lighted on. CONSTITUTION:AC voltage which has a running angle controlled from an AC power supply 1 via a phase control light adjustor 2 is input to a full-wave rectifier 3. If a running angle of the light adjustor 2, obtained in a running angle detecting circuit 7, is larger than 90 deg., a switch element 11 is open-close- controlled through a control circuit 8 to perform pre-heating of filaments 16, 17 for a discharge lamp 15 and also to light the discharge lamp 15. When the discharge lamp 15 is lighted, a load condition in view of the light adjustor 2 is changed to affect the running angle as well, which is narrower than that before lighted. As a result, the drive of the element 11 is stopped and the running angle for lighting off the discharge lamp 15 is set smaller than that for starting the discharge lamp 15, thereby to allow it to be lighted off again even if the running angle is narrow when lighted on and to be stably lighted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a discharge lamp lighting device that is connected to a phase control dimmer to perform dimming control of a discharge lamp.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 63-81795, the conventional discharge lamp lighting device changes the output voltage waveform of the dimmer to
By slicing at a certain predetermined voltage level, the flow angle of the dimmer is detected, and the detected flow angle controls the opening/closing operation of the switching element in the discharge lamp lighting circuit that operates with high-frequency voltage, thereby adjusting the dimming level. It is structured to change the.

[Problem to be solved by the invention]

However, in order to light a discharge lamp, a sufficient starting voltage is required, and by starting the discharge lamp when the flow angle of the phase control dimmer has expanded beyond a certain level, the discharge lamp can be started reliably. can be started. However, when the discharge lamp goes from not being lit to being started, a load fluctuation occurs, and the phase control dimmer is affected by this, resulting in a narrow flow angle and the lamp being turned off again. There was a problem where the Furthermore, when the discharge lamp is not yet lit, the output waveform of the phase control dimmer is unstable, so the lighting operation may start with an incorrect waveform and start may fail. The above-mentioned conventional technology did not take these points into consideration.

An object of the present invention is to eliminate the above two disadvantages and provide a discharge lamp lighting device that can be reliably lit even when connected to a phase control dimmer.

[Means to solve the problem]

The above objective is achieved by setting the flow angle of the phase control dimmer that starts the starting operation as A, and the flow angle of the phase control dimmer that turns off the discharge lamp after lighting it as B, and making the relationship A>B. be done.

In addition, to detect the flow angle when the discharge lamp is not yet lit, connect a series circuit of a resistor and a switch element to the secondary side of the rectifier circuit, and periodically open and close the switch element. The structure is such that it is determined whether or not to start the discharge lamp based on the flow angle during the period when the element is closed.

Furthermore, the period during which the switch element is open is set to 20ms.
By doing the above, a stable output waveform of the phase control dimmer is obtained.

[Effect]

When the discharge lamp is not lit, the power supply smoothing capacitor of the lighting circuit is simply connected to the dimmer and becomes a capacitive load, making the output voltage waveform of the phase control dimmer unstable. Therefore, if an attempt is made to light the discharge lamp when the detected flow angle exceeds a certain value, an erroneous waveform will be detected, making it impossible to reliably light the discharge lamp. Therefore, a resistive load is connected to the power supply, and the power is periodically switched on and off to suppress the power loss of the resistive load. Reliable startability can be obtained by detecting the flow angle during a period when current is flowing through the resistive load, that is, during a period when the output waveform of the phase control dimmer is stable. Furthermore, a more stable waveform can be obtained by setting the period during which current is passed through the resistive load to be at least 20 ms or more continuously, that is, two cycles of the waveform after full-wave rectification of the commercial power supply.

Furthermore, when a discharge lamp is turned on, the load seen from the dimmer changes and the flow angle becomes narrower. Therefore, it is necessary to set the flow angle at which the discharge lamp is turned off to a value narrower than the current flow angle. [Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a discharge lamp lighting device according to the present invention, FIG. 2 is a diagram showing voltage waveforms in the above embodiment, and FIG. 3 is a diagram showing the relationship between opening/closing of a switch element and flow angle. 4 are circuit diagrams showing other embodiments of the present invention.
In Fig. 1, 1 is an AC power supply, 2 is a phase control dimmer,
3 is a full-wave rectifier, 4 is a partial smoothing circuit, 5 and 6 are flow angle detection resistors, 7 is a flow angle detection circuit, 8 is a control circuit, 9 is a load resistor, 10 and 11 are switch elements, 12 is a diode, 13 14 is a resonant capacitor, 14 is a current-limiting choke coil, 15 is a discharge lamp equipped with filaments 16 and 17, 18 is a preheating capacitor, and l9 is a preheating choke coil. An AC voltage whose flow angle is controlled is input from an AC power supply 1 to a full-wave rectifier 3 via a phase control dimmer 2 . The voltage waveform obtained by resistance-dividing the output voltage of the full-wave rectifier 3 by the flow angle detection resistors 5 and 6 is the waveform 20 shown in FIG.
It is. A waveform 22 is obtained by slicing the above waveform 20 at a certain voltage level as shown by a dashed line 2l.

The above function is performed by the flow angle detection circuit 7 shown in FIG. When the flow angle of the phase control dimmer 2 obtained by the flow angle detection circuit 7 is larger than about 90°, the control circuit 8 controls the opening and closing of the switch element 1 and the resonant capacitor 13.
．． Resonance is generated between the current limiting choke coil 4, the preheating capacitor 18, and the preheating choke coil ↓9, and the filaments 6 and 17 of the discharge lamp 5 are preheated.

Furthermore, a high voltage is generated across the parallel circuit of the preheating capacitor 18 and the preheating choke coil 19, and the discharge lamp 1
5 lights up. In addition, a switch element 10 is connected to the load resistor 9.
The waveform of the phase control dimmer 2 is stabilized by passing current while periodically controlling the opening and closing of the dimmer.

In FIG. 3, a waveform 23 shows the output waveform of the flow angle detection circuit 7, and a waveform 24 shows the drive waveform of the switch element 10, and the switch element 10 is closed during a period when the voltage is high. As shown in FIG. 3, when the switch element 10 is closed, the second waveform 25 shows a stable flow angle, but the switch element 1
The waveform during the period when 0 is open is irregular, and in particular, if the flow angle is large and erroneously detected as in waveform 26, sufficient voltage to start the discharge lamp 15 will not be obtained and startup will fail. Therefore, so that at least two waveforms fall within the period when the switch element 10 is closed, a time period of 20 ms or more is taken, and the waveforms are synchronized with the period during which the switch element 10 is closed.
By importing the flow angle data, the discharge lamp 15 can be stably started.

However, when the discharge lamp 15 is turned on, the load condition seen from the phase control dimmer 2 changes, which also affects the flow angle, resulting in a flow angle that is narrower than before the light is turned on. Therefore, by stopping the movement of the switch element 11 and setting the flow angle at which the discharge lamp 15 is turned off to be smaller than the flow angle at which the discharge lamp 15 is started, even if the flow angle becomes narrower when the discharge lamp 15 is turned on. , it is possible to stably turn on the light without turning it off again.

In the lighting circuit of the embodiment shown in FIG. 1, a resonant circuit is used, but in the other embodiment shown in FIG. 4, a self-excited two-stone push-pull circuit is used. It can also be used in various circuits such as half-bridge circuits and full-bridge circuits. In FIG. 4, 31 is a switch element, 30 is a resistor,
32 is a current limiting choke coil, 33 is a transformer, 34 is a resonant capacitor, 35 and 36 are transistors,
Otherwise, the same reference numerals as those shown in FIG. 1 indicate the same or equivalent parts. In another embodiment shown in FIG. 4, when the flow angle becomes approximately 90" or more, the switch element 3
By closing the transistors 35 and 36, base current is supplied to the transistors 35 and 36, which start oscillation and light up the discharge lamp 5. As mentioned above, it can be applied not only to separately excited circuits but also to self-excited circuits.

〔Effect of the invention〕

As described above, the discharge lamp lighting device according to the present invention has an input terminal connected to an AC power source via a phase control dimmer, and a discharge lamp operating device that operates at a high frequency. and a discharge lamp connected to the output of the discharge lamp lighting circuit, a circuit for detecting the flow angle of the phase control dimmer is connected between the secondary terminals of the rectifier circuit, and the discharge lamp When the discharge lamp is not lit, the discharge lamp is turned on when the flow angle is equal to or greater than a predetermined value A, and when the discharge lamp is turned on, when the flow angle becomes equal to or less than the predetermined value B, the discharge lamp is turned off. , by setting the relationship between A and B as A>B,
A discharge lamp lighting device that can provide stable lighting even when connected to a phase control dimmer can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a discharge lamp lighting device according to the present invention, FIG. 2 is a diagram showing voltage waveforms in the above embodiment, and FIG. 3 is a diagram showing the relationship between opening/closing of a switch element and flow angle. 4 are circuit diagrams showing other embodiments of the present invention.

Claims (1)

[Claims] 1. An input terminal is connected to an AC power supply via a phase control dimmer, and the input terminal, a rectifier circuit, a smoothing circuit, a discharge lamp lighting circuit that operates at a high frequency, and the discharge lamp lighting circuit operate at a high frequency. a discharge lamp connected to the output of the electric lamp lighting circuit, and a circuit for detecting the flow angle of the phase control dimmer is connected between the secondary terminals of the rectifier circuit, and when the discharge lamp is not lit, the When the flow angle becomes equal to or greater than a predetermined value A, the discharge lamp is turned on, and when the discharge lamp is turned on, when the flow angle becomes equal to or less than a predetermined value B, the discharge lamp is turned off, and the discharge lamp is turned off. A discharge lamp lighting device in which the relationship A>B. 2. The flow angle detection circuit has a series circuit of a resistor and a switch element connected in parallel, and the switch element periodically opens and closes, and when the discharge lamp is not lit, the switch element is closed. 2. The discharge lamp lighting device according to claim 1, wherein it is determined whether or not to light the discharge lamp based on a detected value of the flow angle detected at the time of discharge. 3. The discharge lamp lighting device according to claim 2, wherein the switch element is closed for at least 20 ms in one cycle during opening/closing operation during non-lighting.