JPH11260582A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set the voltage to be applied to a discharge lamp not more than the re-igniting voltage and thereby improve stability and responsiveness at the time of turning off the discharge lamp by oscillating an inverter circuit at high frequency when the discharge lamp is turned off and is brought into a preheat waiting state. SOLUTION: In bringing about a change from an oscillation stop state to a preheat waiting state to apply a preheat current, a V/f conversion circuit 5, when switching over to the frequency f2 for applying a preheat current after stopping oscillation at an oscillation frequency f1 , oscillates at a frequency f3 higher than a frequency f2 at the time of waiting for preheat in response to the voltage level of Vs +Vc1 obtained by adding a charge voltage Vc1 of a capacitor C1 charged by 3 control voltage Vcc to a dimming signal Vs after the expiration of an oscillation stop timer 7. Thereafter, Vc1 is gradually lowered with the discharge of the capacitor C1 and the oscillation frequency is transferred to f2 . The oscillation frequency of an inverter circuit is also gradually changed in conjunction with it. Thereby, the voltage applied to the discharge lamp begins at a low voltage level and does not exceed the re-igniting voltage, so that re-lighting is prevented and the responsiveness to the dimming signal is improved.

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, and more particularly, to a discharge lamp lighting device having functions of turning off, dimming, and lighting a discharge lamp.

[0002]

2. Description of the Related Art A circuit diagram of a first conventional example according to the present invention is shown in FIG.
Shown in This circuit uses the external control signal to turn off / off the discharge lamp.
A discharge lamp lighting device having a lighting control function, comprising: a DC power supply circuit 1 for converting a power supply voltage Vac of an AC power supply AC into a first DC voltage (hereinafter referred to as a DC voltage);
Capacitor C1 for smoothing and charging the DC voltage output of
And an inverter circuit connected to both ends of the smoothing capacitor C1 and converting the voltage Vdc across the smoothing capacitor C1 into a high-frequency AC voltage and supplying it to the load circuit side. The inverter circuit includes a series circuit of switching elements S1 and S2 connected to both ends of a smoothing capacitor C1, and the load circuit includes an inductor L0 connected to both ends of the switching element S2 and a coupling capacitor C2.
2. It is composed of a series circuit of the discharge lamp LMP and a capacitor C0 connected to both ends of the discharge lamp LMP. Further, a resonance circuit is formed by the inductor L0 and the capacitor C0, the capacitor C0 also serves as a capacitor for preheating the discharge lamp LMP, and the switching elements S1 and S2 receive a control signal (dimming signal) Vs from the outside. In this circuit, which is alternately turned on and off by the control circuit 4, for example, by using a DC voltage signal as the control signal Vs and changing the voltage to 0 to 10 V,
Dimming and extinguishing control of the discharge lamp LMP are performed. FIG. 8 shows the relationship between the voltage level of the control signal Vs and the light output ratio of the discharge lamp LMP. According to FIG. 8, when the control signal Vs ≧ D, the discharge lamp LMP is turned off. When the control signal Vs <D, for example, the output of the discharge lamp LMP can be controlled by the control circuit 4 changing the oscillation frequency of the inverter circuit in response to a voltage change of the control signal Vs. In this circuit, in order to instantly shift the discharge lamp from the extinguished state to the lit state, for example, as shown in Japanese Patent Application Laid-Open No. 6-223991, a preheating state that allows immediate lighting when the extinguished lamp is used, There is means for shifting the oscillation frequency of the inverter circuit to a standby frequency at which the applied voltage does not reach the firing voltage.

In the circuit shown in FIG. 7, when the discharge lamp LMP fades from a lighting state to a light-out state by controlling the operating frequency of the inverter circuit, the discharge lamp LMP is turned on by shifting the oscillation frequency of the inverter circuit to a higher frequency side. The electric power that can be maintained is no longer supplied from the inverter circuit side, and the discharge lamp LMP is turned off. However, the time until the discharge lamp LMP turns off varies depending on the variation of the discharge lamp LMP and the ambient temperature. Therefore, when one control signal is used to turn off a plurality of discharge lamps at the same time, a first problem occurs in that each discharge lamp is turned off separately.

[0004] As means for solving the first problem,
As shown in Japanese Patent Application Laid-Open No. 5-326174 (second conventional example according to the present invention), at the time of fading out, the supply of the preheating current to the discharge lamp cannot be substantially maintained for a certain period of time. In some cases, by limiting the discharge lamp to a level, the discharge lamp is forcibly turned off halfway before the discharge lamp is turned off naturally. In the circuit shown in FIG.
As shown in (b), by stopping the oscillation of the inverter circuit for a certain period T (= time t2 to t3), the supply of the preheating current to the discharge lamp LMP can be limited only for the certain period T.

[0005]

However, in the second prior art, when the inverter circuit starts oscillating again at time t3, as shown in FIG. Since a high voltage exceeding the re-ignition voltage of the discharge lamp is generated, the end of the tube becomes bright for a moment to turn on the discharge lamp, or in extreme cases, the voltage across the discharge lamp becomes the re-ignition voltage of the discharge lamp. As a result, a second problem occurs that the discharge lamp is turned on (slightly discharged) in spite of the light-off mode.

In order to solve the second problem, it is necessary to lengthen the time F from when the control signal is input to the light-out mode to when the inverter circuit temporarily stops oscillating and when the inverter circuit starts oscillating again. there were. The reason can be explained as follows. Activating ions in the discharge lamp gradually disappear with the lapse of time at the time of fade-out, so that the re-ignition voltage of the discharge lamp increases with the lapse of time. Therefore, by increasing the time F, the voltage generated when the inverter circuit restarts oscillation can be reduced to the re-ignition voltage or less, and the second problem can be solved.

However, this requires a time F of 1 second or more. If the time F becomes longer, a third problem arises in that the response of the discharge lamp to the control signal at the time of extinguishing the light is slow and the user feels uncomfortable. Would. The present invention has been made in view of all the above problems, and an object of the present invention is to prevent the discharge lamp from becoming bright for a moment when transitioning from the lighting state of the discharge lamp to the preheating standby state. Another object of the present invention is to provide a discharge lamp lighting device capable of improving responsiveness when the discharge lamp is turned off.

[0008]

To achieve the above object, according to the present invention, there is provided a load circuit including a discharge lamp and an inverter circuit for converting a DC voltage into a high-frequency AC voltage and supplying the high-frequency AC voltage to the load circuit. And control means for controlling the oscillation frequency of the inverter circuit to turn on / off the light, dimming and preheating the discharge lamp, and the control means supplies a preheating current to the filament of the discharge lamp after stopping the oscillation of the inverter circuit. It is characterized in that the inverter circuit starts to oscillate at a frequency higher than the oscillation frequency at which the preheating current is applied when entering the preheating standby state in which the current is applied to the discharge lamp when the oscillation of the inverter circuit is restarted. And the voltage applied to the discharge lamp is suppressed to be less than or equal to the re-ignition voltage, and the lighting of the discharge lamp in the preheating standby state can be prevented.
Responsiveness when the discharge lamp is turned off can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the control means, when entering the preheating standby state, controls the inverter circuit from an oscillation frequency higher than the oscillation frequency for applying the preheating current to an oscillation frequency in the preheating standby state. It is characterized in that the oscillation frequency is continuously changed, and the voltage applied to the discharge lamp is continuously increased to more reliably prevent the voltage from reaching the re-ignition voltage.

According to a third aspect of the present invention, in the first aspect of the invention, the control means continuously changes the oscillating frequency of the inverter circuit from the oscillating frequency at the time of lighting when shifting the discharge lamp from the lit state to the unlit state. It is characterized in that the oscillation of the inverter circuit is stopped after changing to a high frequency, the oscillation frequency is continuously changed from the oscillation frequency at the time of lighting to the high frequency when the oscillation of the inverter circuit is stopped, and the discharge lamp at the time of extinguishing Since the residual charge of the discharge lamp can be reduced, it is possible to reliably turn off the light and to prevent the discharge lamp from being turned on again in the standby preheating state.

According to a fourth aspect of the present invention, the control means performs lighting, extinguishing, dimming, and preheating of the discharge lamp by changing the oscillation frequency of the inverter circuit in accordance with an externally applied control signal. As a characteristic, the discharge lamp can be controlled from the outside. According to a fifth aspect of the present invention, in the fourth aspect, the control means changes the oscillation frequency of the inverter circuit in accordance with the level of the external control signal provided by the DC voltage, thereby controlling the change in the level of the DC voltage. Thus, the discharge lamp can be turned on and off, and light can be adjusted.

According to a sixth aspect of the present invention, the configuration of the inverter circuit can be simplified by using the half-bridge type inverter circuit in the first aspect of the invention.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) Hereinafter, FIGS.
The first embodiment will be described in detail with reference to FIG. The basic configuration of this embodiment is common to the conventional example shown in FIG. 7, and controls the load circuit including the discharge lamp LMP, the inverter circuit, and the oscillation frequency of the inverter circuit to turn on, off, and adjust the discharge lamp LMP. It comprises a control circuit 4 as control means for performing light and preheating. Illustration and description of parts common to the conventional example are omitted, and only the control circuit 4 which is a feature of the present embodiment will be described.

As shown in FIG. 1, a voltage level at which the discharge lamp LMP is turned off is set as a reference voltage Vb by dividing the control voltage Vcc by R1 and R2, and a dimming signal Vs externally supplied as a DC voltage and a reference voltage Vb. A comparator IC2 for comparing the voltage Vb with a reference voltage Vb of the comparator IC2;
The reference voltage Va is set to a higher voltage, and Vs> Va
And an oscillation stop timer circuit 7 which starts counting at a predetermined time while the output is changed from a high level to a low level and changes the output from a low level to a high level after the time is up.
The output terminal of the oscillation stop timer circuit 7 is connected to the input terminal of the V / f conversion circuit 5 via the input terminal of the AND circuit IC3 via C1 and IC4.

On the other hand, the base of a transistor Tr2 is connected to the output terminal of the AND circuit IC3 via a base resistor R4, and the base of the transistor Tr1 is connected to the collector of the transistor Tr2. The transistor Tr2 is turned on and off by the output of the AND circuit IC3, and the transistor Tr1 is turned on when the transistor Tr2 is turned on.
Turns on.

A capacitor C2 and a series circuit of resistors R7 and R8 are connected in parallel between the collector of the transistor Tr1 and the emitter resistor R6 of the transistor Tr2.
8, a capacitor C1 is connected to both ends. Therefore,
When the transistor Tr1 is turned on, the capacitors C1 and C2 are charged by the control voltage Vcc. The V / f conversion circuit 5 operates (oscillates) only when the output of the oscillation stop timer circuit 7 is at a high level, and outputs a signal having a frequency corresponding to the voltage level of the dimming signal Vs input via the diode D1. The driver 6 receiving this signal turns on and off the switching elements S1 and S2 of the inverter circuit, and the oscillation frequency of the inverter circuit is varied according to the voltage level of the dimming signal Vs.

If the dimming signal Vs having a voltage level lower than the reference voltage Vb is input to the comparator IC2 when the discharge lamp LMP is turned on, Vb> Vs, so that the output of the comparator IC2 becomes high level. Become. Then, since the output of the comparator IC2 is inverted by the inverter IC1 and input to the AND circuit IC3, the output of the AND circuit IC3 becomes low level. Therefore, the transistor Tr2 is turned off. At this time, the oscillation stop timer circuit 7 sets the reference voltage Va to a voltage higher than that of the comparator IC2.
Is set, is not triggered, the output remains at a high level, and the V / f conversion circuit 5 is turned on. Therefore, the V / f conversion circuit 5 turns on the discharge lamp LMP and turns on the discharge lamp LMP. During this period, oscillation continues. That is, the dimming signal Vs input from the outside is V / f through the diode D1.
The frequency is converted by the conversion circuit 5, and the switching frequency of the switching elements S1 and S2 of the inverter circuit is changed via the driver 6, the power supplied from the inverter circuit side is adjusted, and the discharge lamp LMP is turned on and dimmed. I have.

In this circuit, a DC voltage is used as the dimming signal Vs, and the dimming and extinguishing control of the discharge lamp LMP is performed by varying the voltage from 0 to 10V. As shown in FIG. 8, the relationship between the DC voltage of the dimming signal Vs and the light output ratio of the discharge lamp LMP is such that when Vs> D, the discharge lamp LMP is turned off, and when Vs <D, the change in the dimming signal Vs is not changed. The output of the discharge lamp LMP can be controlled by varying the oscillation frequency of the inverter circuit upon receipt.

Next, the discharge lamp LMP which is the gist of the present invention is described.
The operation of the control circuit 4 when turning off the light will be described. FIG.
As shown in (a), when the voltage level of the dimming signal Vs is increased, the light output ratio gradually decreases in accordance with the voltage level of the dimming signal Vs, and the dimming signal Vs> D (FIG. D =
9V), the discharge lamp LMP is turned off. At this time, FIG.
When the voltage level of the dimming signal Vs exceeds the reference voltage Vb of the comparator IC2 as shown in FIG. 2A, the output of the comparator IC2 changes from a high level to a low level as shown in FIG. However, the reference voltage Va of the oscillation stop timer circuit 7 is equal to the reference voltage Vb of the comparator IC2.
Is set to a higher voltage than the comparator I
After C2, as shown in FIG. 2C, Va <Vs
At this point, the output of the oscillation stop timer circuit 7 is changed to low level by being triggered. Then, the oscillation stop timer circuit 7 starts counting a predetermined time, and returns the output to the high level again after the time-up. The outputs of the comparator IC2 and the oscillation stop timer circuit 7 are inverters IC1 and IC
4 and is input to the AND circuit IC3, and the output of the AND circuit IC3 becomes high level (FIG. 2 (d)).
reference).

As a result, the transistor Tr2 is turned on by the high level output of the AND circuit IC3, and the control voltage Vcc causes the capacitors C1 and C2 via the transistor Tr1 to turn on.
Is charged. Here, since the non-ground side of the capacitor C1 is connected to the connection point between the input terminal of the V / f conversion circuit 5 and the cathode of the diode D1 via the diode D2, the capacitor C1 as shown in FIG. The voltage (Vs + Vc ₁ ) obtained by adding the voltage Vc ₁ to the dimming signal Vs via the diode D 2 is input to the V / f conversion circuit 5.

When the oscillation stop timer circuit 7 times out and the output changes from low level to high level, the output of the AND circuit IC3 changes to low level and the transistor Tr2 turns off. Further, the transistor Tr1 is also turned off, and as a result, the charged charges of the capacitors C1 and C2 are discharged via the resistors R7 and R8. At the same time, the V / f conversion circuit 5 restarts the oscillation after the oscillation stop timer circuit 7 times up. At this time, the oscillation frequency f corresponding to the voltage level (Vs + Vc ₁ ) input to the V / f conversion circuit 5
_3. Restart the oscillation. However, since the oscillation resumes at the same time the capacitors C1, C2 starts to discharge, the voltage across Vc ₁ of the capacitor C1 is continuously lowered as shown in FIG. 2 (e), V / f conversion circuit 5 dimming The voltage level of the signal Vs gradually decreases from (Vs + Vc ₁ ), and finally becomes only the dimming signal Vs. Oscillation frequency in response to changes in the voltage level of the dimming signal Vs also shifts from f ₃ to the oscillation frequency f ₂ during preheating standby (see FIG. 2 (f)).

FIGS. 3B and 3C show changes in the oscillation frequency of the V / f conversion circuit 5 when entering the preheating standby state in which the preheating current is applied after the oscillation stops. After oscillation stop at an oscillation frequency f _1, at the transition to the f ₂ to give preheating current, V / f conversion circuit 5 resumes oscillation at an oscillation frequency f ₃ corresponding to the voltage level of the above-described (Vs + Vc ₁₎ Therefore, re-oscillates at a frequency higher than the oscillation frequency f _2, then the capacitor C1 due to the discharge of the capacitor C1, C2
It has shifted to the oscillation frequency f ₂ during preheating standby due to a decrease in the voltage across Vc ₁ of. At this time, in response to the change in the oscillation frequency of the V / f conversion circuit 5, the oscillation frequency of the inverter circuit changes in the same manner as the oscillation frequency of the V / f conversion circuit 5, as shown in FIG. Thus, when shifting from the oscillation stop during off into the preheating wait state for providing the preheating current, the oscillation oscillation frequency at the time of re-start of oscillation of the inverter circuit at a high frequency f ₃ than the oscillation frequency f ₂ during preheating stand To restart the discharge lamp LMP as shown in FIG.
Will start at a lower voltage level,
It is possible to prevent the discharge lamp LMP from turning on again without exceeding the restrike voltage, and to improve the response to the dimming signal Vs.

(Embodiment 2) FIG. 4 shows Embodiment 2 of the present invention.
2 shows the configuration of the control circuit 4 in FIG. However, the control circuit 4 according to the present embodiment also has the same basic configuration as the control circuit 4 according to the first embodiment. Therefore, the common parts are denoted by the same reference numerals, and description thereof will be omitted. Only the portions will be described.

In the present embodiment, when the voltage level of the dimming signal Vs falls below a level at which electric power capable of lighting the discharge lamp LMP can be supplied, the oscillation frequency of the inverter circuit is continuously changed to the high frequency side to change the inverter frequency. This ensures that the oscillation of the circuit is stopped. Therefore, in the control circuit 4 of the present embodiment, the timer 8 which is triggered when the output of the inverter IC1 becomes high level and starts counting for a predetermined time, and the output of the AND circuit IC3 and the output of the timer 8 are connected to the input terminals. An OR circuit I that receives an input and has an output terminal connected to the base of the transistor Tr2 via the resistor R4.
C9, a reference voltage obtained by dividing the control voltage Vcc by voltage dividing resistors R9 and R10, and a voltage Vc across the capacitor C1.
And a comparator IC10 for comparing ₁ and an oscillation stop timer circuit 7 is adapted to be triggered by the output of comparator IC10.

When the discharge lamp LMP is turned on, a dimming signal Vs having a voltage level lower than the reference voltage Vb is input to the comparator IC2, the output of the comparator IC2 becomes high, and the timer 8 is also triggered without being triggered. Since the output remains at the low level, the AND circuit IC3
Becomes low level, the transistor Tr2 is turned off, and the output of the comparator IC10 is high level because the capacitor C1 is not charged. Therefore, the output of the oscillation stop timer circuit 7 also becomes high level. , The V / f conversion circuit 5 continues to oscillate at an oscillation frequency corresponding to the voltage level of the dimming signal Vs.

Next, when the voltage level of the dimming signal Vs is increased in order to turn off the discharge lamp LMP, as shown in FIG. 5A, when the dimming signal Vs exceeds the reference voltage Vb, the comparator IC2 is turned on. The output goes low. Since the output of the comparator IC2 is inverted by the inverter IC1 and input to the timer 8, the timer 8 is triggered to start counting for a predetermined time and the output goes high (see FIG. 5C).

When the output of the timer 8 goes high, the output of the OR circuit IC9 goes high, and the transistor T
When the transistor r2 is turned on, the transistor Tr1 is also turned on. As a result, while the timer 8 is counting the predetermined time, the capacitors C1 and C2 are charged by the control voltage Vcc via the transistor Tr1. As a result, FIG.
As shown in (f), the voltage Vc ₁ across the capacitor C1 gradually increases, and the voltage Vc ₁ is added to the dimming signal Vs and input to the V / f conversion circuit 5, so that the V / f conversion circuit 5 The oscillation frequency of No. 5 also continuously increases toward the high frequency side, and the oscillation frequency f of the inverter circuit also gradually increases as shown in FIG. 5G (see FIG. 6C). Therefore, as shown in FIG. 6D, the voltage applied to the discharge lamp LMP also gradually decreases in accordance with the oscillation frequency of the inverter circuit, and the voltage Vc ₁ across the capacitor C1 eventually exceeds the reference voltage of the comparator IC10. Comparator I
As shown in FIG. 5D, the output of C10 becomes low level, the oscillation stop timer circuit 7 is triggered, the output becomes low level, the operation of the V / f conversion circuit 5 is stopped, and the discharge lamp LMP is turned off. It will be forcibly turned off.

On the other hand, the predetermined time of the timer 8
5 is set to such an extent that the charging of FIG.
When the timer 8 times out, the output of the timer 8 changes to low level as shown in FIG. However, at this time, since both the output of the oscillation stop timer circuit 7 and the output of the comparator IC2 are at the high level, the output of the AND circuit IC3 becomes the high level, whereby the output of the OR circuit IC9 is maintained at the high level ( 5 (e), the capacitors C1 and C2 are not discharged (see FIG. 5 (f)).

Then, as shown in FIG. 5D, when the oscillation stop timer circuit 7 times out and its output changes to a high level, the V / f conversion circuit 5 resumes operation (oscillation), and Since the output of the circuit IC3 is at a low level and the output of the OR circuit IC9 is also at a low level (see FIG. 5E), the transistors Tr1 and Tr2 are turned off, and the charges stored in the capacitors C1 and C2 are discharged. As described in 1, the voltage level of the dimming signal Vs of the V / f conversion circuit 5 gradually decreases from (Vs + Vc ₁ ), and finally becomes only the dimming signal Vs (see FIG. 5F). . In response to the change in the voltage level of the dimming signal Vs, the oscillation frequency also shifts from f ₃ to the oscillation frequency f ₂ during standby for preheating (see FIG. 5G). Therefore, similarly to Embodiment 1, the higher the oscillation frequency f ₃ from the oscillation frequency f ₂ of the preheating standby state will be starts oscillating (see FIG. 6), applied to the discharge lamp LMP upon entering standby preheat state Thus, it is possible to prevent a voltage higher than the restriking voltage of the discharge lamp LMP from being applied.

Further, in the present embodiment, the power supplied to the discharge lamp LMP is gradually reduced by gradually increasing the oscillation frequency of the inverter circuit when the lamp is turned off as described above, thereby turning off the lamp (FIG. 5). (Refer to (g)), since the residual charge of the discharge lamp LMP is reduced, the light can be reliably turned off.

[0031]

According to the first aspect of the present invention, there is provided a load circuit including a discharge lamp, an inverter circuit for converting a DC voltage into a high-frequency AC voltage and supplying the AC voltage to the load circuit, and controlling and oscillating the oscillation frequency of the inverter circuit. Control means for lighting, extinguishing, dimming, and preheating of the electric lamp, and the control means enters a preheating standby state in which a preheating current is supplied to a filament of the discharge lamp after the oscillation of the inverter circuit is stopped and a standby is performed. Since the inverter circuit starts oscillating at a frequency higher than the oscillation frequency that gives the preheating current, the voltage applied to the discharge lamp is gradually increased when restarting the oscillation of the inverter circuit, and the voltage applied to the discharge lamp is reset. It is possible to prevent the discharge lamp from being turned on in the preheating standby state by suppressing the discharge voltage to not more than the arc voltage, and to improve the responsiveness when the discharge lamp is turned off.

According to a second aspect of the present invention, when entering the preheating standby state, the control means continuously changes the oscillation frequency of the inverter circuit from an oscillation frequency higher than the oscillation frequency for applying the preheating current to an oscillation frequency in the preheating standby state. Therefore, there is an effect that the voltage applied to the discharge lamp can be continuously increased to more reliably prevent the voltage from reaching the restrike voltage.

According to a third aspect of the present invention, when the control means shifts the discharge lamp from the on state to the off state, it changes the oscillation frequency of the inverter circuit from the oscillation frequency at the time of lighting to a continuously high frequency. Since the oscillation of the inverter circuit is stopped, the oscillation frequency can be continuously changed from the oscillation frequency at the time of lighting to a higher frequency when the oscillation of the inverter circuit is stopped, and the residual charge of the discharge lamp at the time of turning off the light can be reduced. This has the effect of reliably turning off the light and preventing re-lighting of the discharge lamp in the standby preheating state.

According to a fourth aspect of the present invention, the control means performs lighting, extinguishing, dimming, and preheating of the discharge lamp by changing the oscillation frequency of the inverter circuit according to a control signal given from the outside. There is an effect that the discharge lamp can be controlled from the outside. According to a fifth aspect of the present invention, the control means changes the oscillation frequency of the inverter circuit in accordance with the level of the external control signal given by the DC voltage. There is an effect that light control can be performed.

According to the sixth aspect of the present invention, since the inverter circuit is a half-bridge type, there is an effect that the configuration of the inverter circuit can be simplified.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a control circuit according to a first embodiment.

FIGS. 2 (a) to 2 (f) are waveform diagrams for explaining the operation of the above.

FIGS. 3A to 3D are explanatory diagrams for explaining the operation of the above.

FIG. 4 is a circuit diagram of a control circuit according to a second embodiment.

5 (a) to 5 (g) are waveform diagrams for explaining the operation of the above.

FIGS. 6A to 6D are explanatory diagrams for explaining the operation of the above.

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

FIG. 8 is an explanatory diagram for explaining the operation of the above.

FIGS. 9A to 9C are explanatory diagrams for explaining the operation of the above.

[Explanation of symbols]

 5 V / f conversion circuit 7 Oscillation stop timer circuit Vs dimming signal

Claims (6)

[Claims] 1. A load circuit including a discharge lamp, an inverter circuit for converting a DC voltage into a high-frequency AC voltage and supplying the AC voltage to the load circuit, and turning on / off / adjusting the discharge lamp by controlling an oscillation frequency of the inverter circuit. Control means for performing light and preheating, the control means is configured to stop the inverter circuit from oscillating and then supply a preheating current to the filament of the discharge lamp to enter a preheating standby state. A discharge lamp lighting device characterized by starting oscillation of an inverter circuit at a high frequency. 2. The control means, when entering a preheating standby state,
2. The inverter circuit according to claim 1, wherein the oscillation frequency of the inverter circuit is continuously changed from an oscillation frequency higher than an oscillation frequency for applying a preheating current to an oscillation frequency in a preheating standby state.
The discharge lamp lighting device as described in the above. 3. The control means, when shifting the discharge lamp from the on state to the off state, changes the oscillation frequency of the inverter circuit from the oscillation frequency at the time of lighting to a continuously high frequency, and then starts the oscillation of the inverter circuit. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is stopped. 4. The control device according to claim 1, wherein the control means changes the oscillation frequency of the inverter circuit in accordance with an externally applied control signal to turn on, turn off, dimming, and preheat the discharge lamp. Discharge lamp lighting device. 5. The discharge lamp lighting device according to claim 4, wherein the control means changes an oscillation frequency of the inverter circuit in accordance with a level of a control signal provided by a DC voltage. 6. The discharge lamp lighting device according to claim 1, wherein the inverter circuit is a half-bridge type.