JP2000030886A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device smoothly changing the light output of a discharge lamp and reducing the stress applied to the constituting elements of an inverter circuit. SOLUTION: An inverter circuit 2 converts the output of a DC power source 4 into an AC voltage with a switching element and feeds it to a discharge lamp La. A control circuit 3 sets the operating frequency of the inverter circuit 2 to the prescribed preheating frequency to preheat the discharge lamp La, then changes the operating frequency of the inverter circuit 2, to the prescribed starting frequency lower than the preheating frequency, and applies the starting voltage capable of lighting the discharge lamp La to the discharge lamp La. When a lighting detecting circuit 5 detects that the discharge lamp La is lighted, the control circuit 3 instantaneously changes the operating frequency of the inverter circuit 2 from the starting frequency to a first frequency which is higher than the starting frequency and lighting frequency and lower than the maximum value of the frequency capable of maintaining the lighting state of the discharge lamp La then gradually changes the operating frequency from the first frequency to the prescribed lighting frequency.

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.

[0002]

2. Description of the Related Art A discharge lamp lighting device of this type has a circuit configuration as shown in FIG. This discharge lamp lighting device includes a rectifier circuit 1 for rectifying an AC voltage of an AC power supply AC, a smoothing capacitor C1 for smoothing the rectified voltage of the rectifier circuit 1, and a switching element Q1 connected between both ends of the capacitor C1. The power supply side terminals of both filament electrodes are connected via an inverter circuit 2 composed of a series circuit of Q2 and a series circuit composed of a DC cut capacitor C2 and a resonance inductor L1 between both ends of a low-side switching element Q2. Discharge lamp La and discharge lamp La
And a control circuit 3 for controlling the output of the inverter circuit 2 and a capacitor C3 for preheating connected between the non-power-supply-side terminals of both filament electrodes. Note that the inductor L
1 and the capacitor C3 form a resonance circuit.

In this discharge lamp lighting device, an AC voltage of an AC power supply AC is rectified by a rectifier circuit 1, and a voltage obtained by smoothing an output of the rectifier circuit 1 by a capacitor C 1 is output to an inverter circuit 2. The control circuit 3 includes switching elements Q1,
Q2 is alternately turned on and off, a predetermined AC voltage is applied to the discharge lamp La by using a resonance phenomenon of a resonance circuit including the inductor L1 and the capacitor C3, and the discharge lamp La is started.
Turn on. That is, the control circuit 3 changes the operating frequency of the inverter circuit 2 by changing the switching frequency of the switching elements Q1 and Q2, thereby preheating, starting, and lighting the discharge lamp La.

FIG. 4 shows a frequency characteristic of a lamp voltage V1 generated between both ends of the discharge lamp La. When the discharge lamp La is not turned on, the equivalent resistance RL of the discharge lamp La becomes substantially infinite, so that the frequency characteristic of the lamp voltage V1 has a characteristic curve as shown in FIG.

Here, the operation of the circuit from the preheating of the filament electrode of the discharge lamp La to the lighting of the discharge lamp La will be described. First, the control circuit 3 preheats the filament electrode of the discharge lamp La for a predetermined time with the operating frequency of the inverter circuit 2 as a predetermined preheating frequency fy. Next, the control circuit 3 shifts the operating frequency of the inverter circuit 2 from the preheating frequency fy to a predetermined starting frequency fs lower than the preheating frequency fy, and supplies a starting voltage at which the discharge lamp La can be turned on to the discharge lamp La for a predetermined time. By applying the voltage, the discharge lamp La is turned on. After that, the control circuit 3 changes the operating frequency of the inverter circuit 2 according to the dimming signal input from the outside, and dims and lights the discharge lamp La.

When the discharge lamp La is turned on, the equivalent resistance RL of the discharge lamp La decreases, and the frequency characteristic of the lamp voltage V1 changes. The control circuit 3 controls the operating frequency of the inverter circuit 2 according to the dimming signal S1 input from the outside. If the equivalent resistance of the discharge lamp La when the discharge lamp La is fully lit is RL1, the lamp voltage is The frequency characteristic of V1 has a characteristic curve as shown in FIG. 4B, and the control circuit 3 controls the inverter circuit 2 so that a rated output can be obtained.
Are operated at the frequency f1. On the other hand, assuming that the equivalent resistance of the discharge lamp La when the dimming is deepest is RL2, the equivalent resistance RL2 of the discharge lamp La at the time of dimming lighting is the discharge lamp La at the time of full lighting.
, The frequency characteristic of the lamp voltage V1 becomes a characteristic curve shown in FIG. 4C, and the control circuit 3 operates the inverter circuit 2 at the frequency f2.

Thus, the control circuit 3 changes the operating frequency of the inverter circuit 2 between the operating frequency f1 for full lighting and the operating frequency f2 for the deepest dimming in accordance with the dimming signal S1. Thus, the discharge lamp La can be dimmed and lit. At this time, since the equivalent resistance RL of the discharge lamp La changes according to the operating frequency of the inverter circuit 2, the frequency characteristic of the lamp voltage V1 is also a characteristic curve at full lighting (b in FIG. 4) and a characteristic at dimming lighting. The curve continuously changes between the curve (C in FIG. 4).

[0008]

In the discharge lamp lighting device having the above structure, the control circuit 3 changes the operating frequency of the inverter circuit 2 to preheat and start the discharge lamp La.
It is lit.

FIG. 5A shows a change in the reciprocal (ie, a cycle) of the operating frequency f of the inverter circuit 2 from the time when the discharge lamp La is preheated to the time when it is turned on. As shown in FIG.

First, from time t0 to time t1, the control circuit 3 operates the inverter circuit 2 at a predetermined preheating frequency fy to preheat both filament electrodes of the discharge lamp La for a predetermined preheating time Ty (preheating mode). ). Next, at time t1
From t2 to t2, the control circuit 3 operates the inverter circuit 2 at a predetermined starting frequency fs lower than the preheating frequency,
A voltage at which the discharge lamp La can be turned on is applied to the discharge lamp La for a predetermined start time Ts, and the discharge lamp La is turned on (start mode). After time t2, the control circuit 3 changes the operating frequency f of the inverter circuit 2 between f1 and f2 in accordance with the dimming signal S1 input from the outside, and dims and lights the discharge lamp La (dimming lighting). mode). Here, when the discharge lamp La is turned on at the time t3 between the times t1 and t2 operating in the start mode, the discharge lamp L is turned on from the time the discharge lamp La is turned on at the time t3 to the end of the start mode at the time t2.
a is lit at the light output L1 determined by the starting frequency fs, and after time t2, the light output L3 determined according to the dimming signal S1.
, The discharge lamp La is turned on. Therefore, when shifting from the starting mode to the dimming lighting mode at time t2, the light output of the discharge lamp La changes stepwise from L1 to L3.
There is a problem that a user feels strange.

Therefore, in order to reduce such a sense of discomfort, as shown in FIG. 6, for example, a lighting detection circuit 5 for detecting the lighting state of the discharge lamp La from a lamp voltage V1 generated between both ends of the discharge lamp La is provided. When the lighting detection circuit 5 detects that the discharge lamp La has been turned on, the control circuit 3 changes the operating frequency of the inverter circuit 2 from the starting frequency fs to the dimming signal S.
One that changes up to a lighting frequency determined according to 1 has been proposed. In this circuit, the inverter circuit 2 converts the DC voltage of the DC power supply 4 into a high-frequency voltage and applies it to the discharge lamp La.

In this discharge lamp lighting device, FIGS.
As shown in (c), at time t0 to t1, the control circuit 3 changes the operating frequency of the inverter circuit 2 to the preheating frequency fy.
After preheating both filament electrodes of the discharge lamp La, the control circuit 3 shifts the operating frequency of the inverter circuit 2 to the start frequency fs, and applies a start voltage to the discharge lamp La. At time t3 during operation in the start mode, the discharge lamp L
When a is turned on, the discharge lamp La is turned on with the light output L1 determined by the starting frequency fs. When the discharge lamp La is turned on, the equivalent resistance RL of the discharge lamp La is reduced, and the lamp voltage V1 is reduced. Therefore, the lighting detection circuit 5 compares the magnitude relationship between the lamp voltage V1 and a predetermined threshold value Va, and determines the time t4. Since the lamp voltage V1 becomes smaller than the threshold value Va, it is detected that the discharge lamp La is turned on. When the lighting detection circuit 5 detects that the discharge lamp La has been turned on, the control circuit 3 switches the operating frequency of the inverter circuit 2 from the starting frequency fs to a predetermined lighting frequency. The lighting period can be shortened, and the light output of the discharge lamp La changes stepwise when switching from the start-up mode to the dimming lighting mode, thereby providing an effect of reducing a sense of discomfort given to the user. .

However, immediately after the discharge lamp La is turned on, the equivalent resistance RL of the discharge lamp La changes transiently.
For example, immediately after the discharge lamp La is turned on, the control circuit 3 changes the operating frequency of the inverter circuit 2 to the operating frequency f1 at the time of full lighting.
, The equivalent resistance RL of the discharge lamp La changes transiently, and the frequency characteristic of the lamp voltage V1 is a characteristic curve at full lighting (b in FIG. 4) and a characteristic curve at the deepest dimming. (C in FIG. 4). When the control circuit 3 operates the inverter circuit 2 at the frequency f1 at the time of full lighting, the equivalent resistance RL of the discharge lamp La fluctuates, and the frequency characteristic of the lamp voltage V1 becomes a characteristic curve in the case of the deepest dimming. Since the operating frequency f1 of the inverter circuit 2 is lower than the resonance frequency f3 in this case,
Becomes an advanced mode, and there is a problem that excessive stress is generated in the switching elements Q1 and Q2 of the inverter circuit 2.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce a sense of discomfort due to a stepwise change in the light output of a discharge lamp.
An object of the present invention is to provide a discharge lamp lighting device in which stress applied to components of an inverter circuit is reduced.

[0015]

According to one aspect of the present invention, there is provided a DC power supply, an inverter circuit for converting an output of the DC power supply into an AC voltage and supplying the AC voltage to a discharge lamp, and an inverter circuit. A control circuit for controlling the output of the inverter circuit, the control circuit preheats the filament electrode of the discharge lamp for a predetermined time using the operating frequency of the inverter circuit as a predetermined preheating frequency, and sets the operating frequency of the inverter circuit from the preheating frequency to the preheating frequency. Also, the discharge lamp is switched to a predetermined starting frequency, a voltage at which the discharge lamp can be turned on is applied to the discharge lamp for a predetermined period of time, and the operating frequency of the inverter circuit is shifted from the starting frequency to a predetermined lighting frequency to output a predetermined light output to the discharge lamp. In the discharge lamp lighting device that is lit by the control circuit, when the control circuit shifts the operating frequency of the inverter circuit from the starting frequency to the lighting frequency, After the instantaneous transition to a first frequency that is higher than the lamp frequency and less than or equal to the maximum value of the frequency at which the discharge lamp can maintain lighting, gradually transitioning from the first frequency to the lighting frequency, Since the first frequency is higher than the resonance frequency of the lamp voltage when the discharge lamp is turned off, when shifting the operating frequency of the inverter circuit from the starting frequency to the first frequency, the inverter circuit must be in the slow phase mode. The inverter circuit operates at a maximum frequency that is higher than the starting frequency and lighting frequency, and that the discharge lamp can maintain lighting. Since the frequency gradually shifts from the first frequency below to the lighting frequency, the light output of the discharge lamp rises smoothly from a low luminous flux, reducing the sense of discomfort felt by the user. Rukoto can.

According to a second aspect of the present invention, there is provided a DC power supply, an inverter circuit for converting the output of the DC power supply into an AC voltage and supplying the AC voltage to the discharge lamp, and a control circuit for controlling the output of the inverter circuit. The operating frequency of the inverter circuit is set to a predetermined preheating frequency, the filament electrode of the discharge lamp is preheated for a predetermined time, the operating frequency of the inverter circuit is shifted from the preheating frequency to a predetermined starting frequency lower than the preheating frequency, and the discharge lamp is turned on. A possible voltage is applied to the discharge lamp for a predetermined time, and the operating frequency of the inverter circuit is shifted from the starting frequency to a lighting frequency determined according to a dimming signal input from the outside, so that the discharge lamp has a desired light output. In the discharge lamp lighting device that performs dimming lighting, the control circuit determines the starting frequency when shifting the operating frequency of the inverter circuit from the starting frequency to the lighting frequency. After an instantaneous transition to a first frequency that is higher than the lighting frequency, and is equal to or less than the maximum value of the frequency at which the discharge lamp can maintain lighting, gradually transitioning from the first frequency to the lighting frequency, Since the first frequency is higher than the resonance frequency of the lamp voltage when the discharge lamp is turned off, when the operation frequency of the inverter circuit is shifted from the starting frequency to the first frequency as in the first aspect of the invention. In addition, the inverter circuit always operates in the slow phase mode, which can prevent stress on the components of the inverter circuit, and the operating frequency of the inverter circuit is higher than the starting frequency and the lighting frequency, and the discharge lamp Gradually shifts from the first frequency that is equal to or less than the maximum value of the frequency at which lighting can be maintained to the lighting frequency, so that the light output of the discharge lamp rises smoothly from a low luminous flux, It is possible to reduce the discomfort felt by the use person.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a lighting detection circuit for detecting a lighting state of the discharge lamp is provided, and when the lighting detection circuit detects that the discharge lamp is lit, the control circuit After the operating frequency of the inverter circuit is instantaneously shifted from the starting frequency to the first frequency, the operating frequency is gradually shifted from the first frequency to the lighting frequency. The time until the frequency is switched to the first frequency can be shortened.

[0018]

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

FIG. 1 shows a circuit configuration of the discharge lamp lighting apparatus according to the present embodiment. The DC power supply 4 is switched by switching the DC voltage of the DC power supply 4 using a switching element (not shown). Inverter circuit 2 that converts a DC voltage to an AC voltage and supplies the AC voltage to a discharge lamp La described later.
A discharge lamp La in which the power supply side terminals of both filament electrodes are connected between output terminals of the inverter circuit 2, and a discharge lamp La
A capacitor C3 for resonance connected between the non-power-supply-side terminals of the two filament electrodes, a control circuit 3 for controlling the output of the inverter circuit 2 by controlling the operating frequency of the inverter circuit 2, and a lamp for the discharge lamp La. A lighting detection circuit 5 for detecting the lighting state of the discharge lamp La from the voltage V1. Note that the inverter circuit 2 has the same configuration as the circuit shown in FIG. 3 described above, and a description thereof will be omitted. Although not shown, a DC cut capacitor and a resonance inductor are connected between the inverter circuit 2 and the discharge lamp La, similarly to the circuit shown in FIG.

Hereinafter, the operation from the time when the discharge lamp La is preheated to the time when it is turned on will be described with reference to FIGS. 2 (a) to 2 (c).

First, at times t0 to t1, the control circuit 3 changes the operating frequency of the inverter circuit 2 to a predetermined preheating frequency fy.
And the filament electrode of the discharge lamp La is preheated for a predetermined preheating time Ty (preheating mode). When the preheating of the filament electrode ends at time t1, the control circuit 3
Shifts the operating frequency of the inverter circuit 2 from the preheating frequency fy to a predetermined starting frequency fs lower than the preheating frequency fy, and changes the starting voltage at which the discharge lamp La can be turned on to the discharge lamp La.
(Start mode). When the discharge lamp La is turned on at time t3 during operation in the start-up mode, the lamp voltage V1 becomes smaller than the threshold value Va at time t4, so that the lighting detection circuit 5 detects that the discharge lamp La is turned on. When a detection signal indicating that the discharge lamp La is turned on is input from the lighting detection circuit 5 to the control circuit 3,
The control circuit 3 raises the operating frequency of the inverter circuit 2 from the starting frequency fs to a frequency higher than the starting frequency fs or the lighting frequency ft and a first frequency fe lower than the maximum value fd of the frequency at which the discharge lamp La can maintain lighting. After instantaneously shifting to (fs, ft <fe ≦ fd), the shift is gradually made from the first frequency fe to the lighting frequency ft determined according to the dimming signal S1. Note that the lighting frequency ft may be set to an arbitrary frequency between the frequency f1 at the time of full lighting and the frequency f2 at the time of the deepest dimming, and FIG.
The case where t is set to the frequency f1 at the time of full lighting is shown.

FIG. 2C shows a change in the light output of the discharge lamp La from the time when the discharge lamp La is preheated to the time when it is turned on. At time t3 during operation in the start mode, the discharge lamp La
Is turned on, at time t4, the lighting detection circuit 5 detects the lighting of the discharge lamp La, and the control circuit 3 changes the operating frequency of the inverter circuit 2 from the starting frequency fs to the first frequency fe.
(The period dt), the light output of the discharge lamp La becomes the light output L1 when the inverter circuit 2 operates at the starting frequency fs.

Next, at time t4, when the control circuit 3 shifts the operating frequency of the inverter circuit 2 from the starting frequency fs to the first frequency fe, the light output of the discharge lamp La is changed by the inverter circuit 2 to the first frequency fe. The light output of the discharge lamp La becomes L2 as the control circuit 3 gradually shifts the operating frequency of the inverter circuit 2 from the first frequency fe to the lighting frequency ft.
To a desired dimming output determined by the lighting frequency ft.

As described above, in the period dt, the discharge lamp La is turned on with the light output L1 determined by the starting frequency fs, so that the light output of the discharge lamp La becomes bright for a moment. If this period dt is shortened as much as possible, Due to the persistence characteristics of human eyes,
The brightness perceived by human eyes changes smoothly as shown by a broken line A in FIG. 2C, and the sense of discomfort given to the user can be reduced. Further, the first frequency fe is equal to the starting frequency fs.
And the operating frequency of the inverter circuit 2 is set to the first frequency fd, which is higher than the lighting frequency ft and the maximum frequency fd at which the discharge lamp La can maintain lighting.
Is gradually changed from the frequency fe to the lighting frequency ft, the equivalent resistance RL of the discharge lamp La does not change abruptly, and the light output of the discharge lamp La rises smoothly from a low luminous flux and is given to the user. Discomfort can be further reduced. In addition, since the first frequency fe is higher than the resonance frequency f0 of the lamp voltage V1 when the discharge lamp La is turned off, the equivalent resistance RL of the discharge lamp La changes transiently while the operating frequency of the inverter circuit 2 is switched. , The inverter circuit 2 always operates in the slow mode,
Since the phase-advancing operation does not occur, no stress is applied to the constituent elements of the inverter circuit 2.

In the discharge lamp lighting device according to the present embodiment, the control circuit 3 changes the operating frequency of the inverter circuit 2 in accordance with the dimming signal S1 input from the outside to dimming the discharge lamp La. However, when the control circuit 3 controls the operating frequency of the inverter circuit 2 to a predetermined lighting frequency to light the discharge lamp La with a predetermined light output, when switching from the starting mode to the lighting mode, After the control circuit 3 instantaneously shifts the operating frequency of the inverter circuit 2 from the starting frequency fs to the first frequency fe, the operating frequency of the inverter circuit 2 gradually shifts from the first operating frequency fe to a predetermined lighting frequency. You can make it happen.

In the discharge lamp lighting device of the present embodiment,
When the lighting detection circuit 5 detects that the discharge lamp La is turned on, the control circuit 3 instantaneously shifts the operating frequency of the inverter circuit 2 from the starting frequency fs to the first frequency fe. After the operating frequency of the circuit 2 is shifted from the preheating frequency fy to the starting frequency fs, and the inverter circuit 2 is operated at the starting frequency fs for a predetermined starting period fs, the control circuit 3 changes the operating frequency of the inverter circuit 2 to the starting frequency. The frequency may be instantaneously shifted from fs to the first frequency fe, and the operating frequency of the inverter circuit 2 may be gradually shifted from the first frequency fe to the lighting frequency ft.

[0027]

As described above, according to the first aspect of the present invention, there is provided a DC power supply, an inverter circuit for converting the output of the DC power supply into an AC voltage and supplying the AC voltage to the discharge lamp, and a control circuit for controlling the output of the inverter circuit. The control circuit preheats the filament electrode of the discharge lamp for a predetermined time using the operating frequency of the inverter circuit as a predetermined preheating frequency, and changes the operating frequency of the inverter circuit from the preheating frequency to a predetermined starting frequency lower than the preheating frequency. A discharge lamp lighting device that applies a voltage that allows the discharge lamp to be turned on to the discharge lamp for a predetermined time, shifts the operating frequency of the inverter circuit from the starting frequency to a predetermined lighting frequency, and lights the discharge lamp with a predetermined light output. In, the control circuit, when shifting the operating frequency of the inverter circuit from the starting frequency to the lighting frequency, higher than the starting frequency and the lighting frequency, and, After the lamp has instantly is shifted to the maximum value below the frequency of the first frequency to maintain the lighting, the first
The first frequency is higher than the resonance frequency of the lamp voltage when the discharge lamp is off, so that the operating frequency of the inverter circuit is changed from the starting frequency to the first frequency. The inverter circuit always operates in the slow mode when shifting to the frequency of the inverter circuit, which can prevent stress on the components of the inverter circuit, and the operating frequency of the inverter circuit is higher than the starting frequency or the lighting frequency. Since the frequency gradually increases from the first frequency, which is higher than the maximum value of the frequency at which the discharge lamp can maintain lighting, to the lighting frequency, the light output of the discharge lamp rises smoothly from a low luminous flux, and the user feels discomfort. There is an effect that it can be reduced.

According to a second aspect of the present invention, there is provided a DC power supply, an inverter circuit for converting the output of the DC power supply into an AC voltage and supplying the AC voltage to the discharge lamp, and a control circuit for controlling the output of the inverter circuit. The operating frequency of the inverter circuit is set to a predetermined preheating frequency, the filament electrode of the discharge lamp is preheated for a predetermined time, the operating frequency of the inverter circuit is shifted from the preheating frequency to a predetermined starting frequency lower than the preheating frequency, and the discharge lamp is turned on. A possible voltage is applied to the discharge lamp for a predetermined time, and the operating frequency of the inverter circuit is shifted from the starting frequency to a lighting frequency determined according to a dimming signal input from the outside, so that the discharge lamp has a desired light output. In a discharge lamp lighting device that performs dimming lighting, the control circuit determines the starting frequency or the starting frequency when shifting the operating frequency of the inverter circuit from the starting frequency to the lighting frequency. After the instantaneous transition to a first frequency that is higher than the lamp frequency and less than or equal to the maximum value of the frequency at which the discharge lamp can maintain lighting, gradually transitioning from the first frequency to the lighting frequency, Since the first frequency is higher than the resonance frequency of the lamp voltage when the discharge lamp is turned off, when the operation frequency of the inverter circuit is shifted from the starting frequency to the first frequency as in the first aspect of the invention. In addition, the inverter circuit always operates in the slow phase mode, which can prevent stress on the components of the inverter circuit, and the operating frequency of the inverter circuit is higher than the starting frequency and the lighting frequency, and the discharge lamp Gradually changes from the first frequency below the maximum value of the frequency at which the lamp can be maintained to the lighting frequency, so that the light output of the discharge lamp rises smoothly from a low luminous flux and is used. There is an effect that can reduce the discomfort felt by the person.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a lighting detection circuit for detecting a lighting state of the discharge lamp is provided. The operation frequency of the inverter circuit is instantaneously shifted from the starting frequency to the first frequency, and then gradually shifted from the first frequency to the lighting frequency. Since the time from when the discharge lamp is turned on to when the operating frequency of the inverter circuit is switched to the first frequency can be shortened, the period during which the discharge lamp is turned on with the light output determined by the starting frequency can be shortened. As a result, the light output of the discharge lamp can be changed more smoothly, and there is an effect that the sense of discomfort felt by the user can be further reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a discharge lamp lighting device according to an embodiment.

FIGS. 2A to 2C are waveform diagrams illustrating the operation of the above discharge lamp lighting device.

FIG. 3 is a circuit diagram showing a conventional discharge lamp lighting device.

FIG. 4 is an explanatory diagram illustrating frequency characteristics of a lamp voltage according to the first embodiment;

FIGS. 5A and 5B are explanatory diagrams illustrating the operation of the above.

FIG. 6 is a circuit diagram showing another discharge lamp lighting device of the above.

FIGS. 7A to 7C are explanatory diagrams illustrating the operation of the above.

[Explanation of symbols]

 2 Inverter circuit 3 Control circuit 4 DC power supply 5 Lighting detection circuit La Discharge lamp

Claims (3)

[Claims] A DC power supply; an inverter circuit for converting an output of the DC power supply into an AC voltage and supplying the AC voltage to a discharge lamp; and a control circuit for controlling an output of the inverter circuit, wherein the control circuit operates the inverter circuit. The filament electrode of the discharge lamp is preheated for a predetermined time using the frequency as a predetermined preheating frequency, and the operating frequency of the inverter circuit is shifted from the preheating frequency to a predetermined starting frequency lower than the preheating frequency to release a voltage at which the discharge lamp can be turned on. In a discharge lamp lighting device that applies a predetermined time to an electric lamp, shifts the operating frequency of the inverter circuit from the starting frequency to a predetermined lighting frequency, and lights the discharge lamp with a predetermined light output, the control circuit controls the operating frequency of the inverter circuit. When shifting from the starting frequency to the lighting frequency, the highest frequency that is higher than the starting frequency or the lighting frequency and that allows the discharge lamp to maintain lighting. After instant is shifted to the following first frequency value, the discharge lamp lighting apparatus, characterized in that to gradually transition to the lighting frequency from the first frequency. And a control circuit for controlling an output of the inverter circuit. The control circuit controls an output of the inverter circuit. The control circuit controls an output of the inverter circuit. The filament electrode of the discharge lamp is preheated for a predetermined time using the frequency as a predetermined preheating frequency, and the operating frequency of the inverter circuit is shifted from the preheating frequency to a predetermined starting frequency lower than the preheating frequency to release a voltage at which the discharge lamp can be turned on. A discharge lamp is applied to the electric lamp for a predetermined period of time to shift the operating frequency of the inverter circuit from the starting frequency to a lighting frequency determined according to a dimming signal input from the outside, so that the discharge lamp is dimmed and lit with a desired light output. In the lamp lighting device, when the control circuit shifts the operating frequency of the inverter circuit from the starting frequency to the lighting frequency, the control circuit sets the operating frequency higher than the starting frequency or the lighting frequency. And, after the discharge lamp is instantly is shifted to the maximum value below the frequency of the first frequency to maintain the lighting, the discharge lamp lighting apparatus, characterized in that to gradually transition to the lighting frequency from the first frequency. 3. A lighting detection circuit for detecting a lighting state of a discharge lamp is provided. When the lighting detection circuit detects that the discharge lamp is lit, a control circuit changes an operating frequency of the inverter circuit from a starting frequency to a first frequency. 3. The discharge lamp lighting device according to claim 1, wherein after the instantaneous shift, the shift is gradually made from the first frequency to the lighting frequency.