JP2023184124A - Lighting devices for discharge lamps and irradiation devices for vehicles - Google Patents

Abstract

An object of the present invention is to provide a lighting device for a discharge lamp and an irradiation device for a vehicle that can suppress a rise in temperature of circuit components. A lighting device for a discharge lamp according to an embodiment is a lighting device that applies a driving voltage of a predetermined frequency to a discharge lamp. The discharge lamp lighting device includes: a first transformer electrically connected to one electrode of the discharge lamp; a second transformer electrically connected to the other electrode of the discharge lamp; and a resonance one. It is electrically connected to the primary winding of the first transformer and the primary winding of the second transformer via a capacitor, and converts the DC voltage into an AC voltage of a predetermined frequency by PWM control. a switching output circuit that converts; an LLC control circuit that inputs a PWM signal used for the PWM control to the switching output circuit; and when the ambient temperature exceeds a predetermined value, the duty of the PWM signal is changed according to the temperature. and a temperature compensation circuit for changing the ratio. [Selection diagram] Figure 3

Description

Embodiments of the present invention relate to a discharge lamp lighting device and a vehicle irradiation device.

There is a lighting device that lights a discharge lamp. For example, a lighting device having a pulse lighting circuit has been proposed as a lighting device for lighting a dielectric barrier discharge lamp such as an excimer lamp. If a pulse lighting circuit is used, a pause period can be provided in the current waveform of the discharge lamp during lighting, so that the luminous efficiency of the discharge lamp can be improved. Further, in order to further improve the luminous efficiency of discharge lamps, a pulse lighting circuit using a flyback circuit has also been proposed.

However, the general pulse lighting circuit has a large power loss in the transformer and the switching element, so the circuit efficiency is poor. If the circuit efficiency is poor, the amount of heat generated by the circuit components provided in the pulse lighting circuit increases, and the temperature of the circuit components increases.

Furthermore, in the case of a discharge lamp lighting device used in a vehicle irradiation device, it is necessary to consider that the discharge lamp lighting device is provided in an atmosphere of about 85°C. Therefore, there is a possibility that the temperature of the circuit components will further increase. Further, it is desired that the lighting device for a discharge lamp used in a vehicle irradiation device be made smaller, and there is also a risk that the temperature of the circuit components may further increase due to thermal interference between the circuit components. If the temperature of the circuit components becomes too high, the functions of the circuit components may deteriorate or the circuit components may malfunction.
Therefore, it has been desired to develop a technology that can suppress the temperature rise of circuit components.

Japanese Patent Application Publication No. 2000-200690

The problem to be solved by the present invention is to provide a discharge lamp lighting device and a vehicle irradiation device that can suppress the temperature rise of circuit components.

A lighting device for a discharge lamp according to an embodiment is a lighting device that applies a driving voltage of a predetermined frequency to a discharge lamp. The discharge lamp lighting device includes: a first transformer electrically connected to one electrode of the discharge lamp; a second transformer electrically connected to the other electrode of the discharge lamp; and a resonance one. It is electrically connected to the primary winding of the first transformer and the primary winding of the second transformer through a capacitor, and converts the DC voltage into an AC voltage of a predetermined frequency by PWM control. a switching output circuit that converts; an LLC control circuit that inputs a PWM signal used for the PWM control to the switching output circuit; and when the ambient temperature exceeds a predetermined value, the duty of the PWM signal is changed according to the temperature. and a temperature compensation circuit for changing the ratio.

According to the embodiments of the present invention, it is possible to provide a discharge lamp lighting device and a vehicle irradiation device that can suppress a rise in temperature of circuit components.

FIG. 1 is a schematic perspective view illustrating a vehicle irradiation device according to the present embodiment. 2 is a schematic cross-sectional view of the vehicle irradiation device in the direction of line AA in FIG. 1. FIG. FIG. 2 is a circuit diagram for illustrating a lighting device. FIG. 2 is a circuit diagram for illustrating a temperature compensation circuit. 5 is a timing chart for illustrating the operation of the temperature compensation circuit in FIG. 4. FIG. FIG. 7 is a circuit diagram for illustrating a lighting device according to another embodiment.

Hereinafter, embodiments will be illustrated with reference to the drawings. Note that in each drawing, similar components are denoted by the same reference numerals, and detailed explanations are omitted as appropriate.
Although there is no particular limitation on the application of the lighting device for a discharge lamp according to this embodiment, it can be used, for example, in a vehicle irradiation device provided in a vehicle such as an automobile or a railway. Therefore, in the following, a case will be described as an example in which a discharge lamp lighting device is provided in a vehicle irradiation device.

The vehicular irradiation device can be provided, for example, in the passenger compartment or trunk room of an automobile, or in the passenger compartment of a railway vehicle. However, the installation location of the vehicle irradiation device is not limited to the illustrated example.

FIG. 1 is a schematic perspective view illustrating a vehicle irradiation device 100 according to the present embodiment.
FIG. 2 is a schematic cross-sectional view of the vehicle irradiation device 100 in the direction of line AA in FIG.
As shown in FIGS. 1 and 2, the vehicle irradiation device 100 includes, for example, a discharge lamp lighting device 1 (hereinafter simply referred to as the lighting device 1), a housing 2, a substrate 3, a discharge lamp 4, a lamp A cover 5, wiring 6, window 7, and shield 8 are provided.

First, a lighting device 1 according to the present embodiment will be illustrated.
As shown in FIG. 2, the lighting device 1 is provided inside a housing 2. The lighting device 1 is provided, for example, on the surface of the substrate 3 on the side where the discharge lamp 4 is provided. If the discharge lamp 4 and the lighting device 1 are provided on the same side of the substrate 3, it becomes easy to reduce the thickness dimension T of the housing 2. The lighting device 1 is electrically connected to a pair of terminal holders 41 to which the discharge lamp 4 is mounted, for example, using a wiring member such as a wiring cord or a metal plate. Therefore, by attaching the discharge lamp 4 to the pair of terminal holders 41, the lighting device 1 and the discharge lamp 4 can be electrically connected.

The lighting device 1 applies a driving voltage of a predetermined frequency to the discharge lamp 4. When a driving voltage is applied to the discharge lamp 4, for example, discharge occurs between a pair of electrodes provided on the discharge lamp 4, and light such as ultraviolet rays is emitted from the discharge lamp 4.

FIG. 3 is a circuit diagram illustrating the lighting device 1. As shown in FIG.
As shown in FIG. 3, the lighting device 1 includes, for example, a switching output circuit 11, a transformer 12 (corresponding to an example of a first transformer and a second transformer), a resonance capacitor 13, a detection unit 14, and a control circuit 15. , and a temperature detection element 16.

The switching output circuit 11 is electrically connected to the primary windings of the two transformers 12 via a resonance capacitor 13. The switching output circuit 11 converts a DC voltage into an AC voltage of a predetermined frequency by PWM (Pulse Width Modulation) control. For example, the switching output circuit 11 converts the DC voltage from the DC power supply 200 into an AC voltage of a predetermined frequency, for example, a pseudo sine wave voltage. Furthermore, the switching output circuit 11 changes the voltage applied to the primary winding of the transformer 12. The DC power source 200 is, for example, a battery or a battery mounted on a vehicle such as an automobile.

The switching output circuit 11 illustrated in FIG. 3 is a half-bridge circuit. The switching output circuit 11, which is a half-bridge circuit, includes, for example, a switching element 11a, a switching element 11b, and a drive circuit 11c.

The switching element 11a and the switching element 11b are, for example, MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistor Field effect transistors). If the switching element 11a and the switching element 11b are MOSFETs that are voltage-driven elements, power loss in the circuit can be reduced. Further, if the switching element 11a and the switching element 11b are MOSFETs, it is possible to increase the switching speed and reduce switching loss.

For example, the drive circuit 11c alternately applies voltage to the gate electrode of the switching element 11a and voltage to the gate electrode of the switching element 11b based on a control signal (PWM signal) from the control circuit 15. to convert the DC voltage from the DC power supply 200 into an AC voltage of a predetermined frequency. For example, the frequency is about 100kHz to 300kHz.

Further, the drive circuit 11c changes the output voltage (the voltage applied to the primary winding of the transformer 12) by changing the duty ratio based on the PWM signal from the control circuit 15.
Although the switching output circuit 11 is a half-bridge circuit, the switching output circuit 11 may be, for example, a full-bridge circuit.

Two transformers 12 are provided. As described above, the primary windings of the two transformers 12 are electrically connected to the switching output circuit 11. A secondary winding of one transformer 12 is electrically connected to one electrode of the discharge lamp 4. The secondary winding of the other transformer 12 is electrically connected to the other electrode of the discharge lamp 4. That is, this is a form of double high-pressure discharge with the midpoint of the transformer 12 as the ground (reference).

Here, the DC voltage from the DC power supply 200 may vary greatly. For example, a DC power source 200 (for example, a battery) provided in a vehicle such as an automobile is electrically connected to the lighting device 1 provided in the vehicle irradiation device 100. Generally, the rated voltage of the DC power supply 200 provided in a vehicle such as an automobile is about 13.5V.

However, in reality, the voltage of the DC power supply 200 may fluctuate within a range of, for example, 9V to 16V due to battery voltage drop, alternator operation, circuit effects, and the like. When the fluctuation in the voltage input to the lighting device 1 increases, the fluctuation in the drive voltage output from the lighting device 1 and applied to the discharge lamp 4 increases. If the fluctuation of the driving voltage becomes large, there is a possibility that the amount of light emitted from the discharge lamp 4, ultraviolet rays, etc., becomes unstable.

Therefore, the lighting device 1 is provided with a detection section 14 and a control circuit 15.
The detection unit 14 detects the output state of the transformer 12. The detection unit 14 can be provided in each of the two transformers 12, for example. The detection unit 14 can be, for example, an auxiliary winding provided in the transformer 12. If the detection unit 14 is an auxiliary winding, the current flowing in the secondary winding of the transformer 12 (the output state of the transformer 12) can be detected by detecting the current flowing in the auxiliary winding.

The control circuit 15 inputs an appropriate PWM signal to the switching output circuit 11 (drive circuit 11c) based on the output state of the transformer 12 detected by the detection unit 14.

The control circuit 15 includes, for example, a PWM control circuit 15a, a comparator 15b, a reference voltage section 15c, and an LLC control circuit 15d.

PWM control circuit 15a generates a PWM signal.
The comparator 15b compares the output state of the transformer 12 detected by the detection unit 14 with the reference value from the reference voltage unit 15c, and detects the amount of variation in the drive voltage due to variation in the DC voltage. For example, the comparator 15b compares the voltage based on the current detected by the detection section 14 and the reference voltage from the reference voltage section 15c. In this way, it is possible to detect the amount of variation in the drive voltage applied to the discharge lamp 4 due to the voltage variation of the DC power supply 200.

The LLC control circuit 15d intermittently controls the switching output circuit 11. The LLC control circuit 15d inputs a PWM signal used for PWM control to the switching output circuit 11 (drive circuit 11c). The LLC control circuit 15d changes the duty ratio of the PWM signal generated by the PWM control circuit 15a based on the amount of variation in the drive voltage applied to the discharge lamp 4, which is detected by the comparator 15b. For example, when the drive voltage applied to the discharge lamp 4 becomes lower than the reference value (when the voltage of the DC power supply 200 decreases), the LLC control circuit 15d changes the duty ratio of the PWM signal to the discharge lamp 4. It is increased according to the amount of decrease in the applied drive voltage. For example, when the drive voltage applied to the discharge lamp 4 becomes higher than the reference value (when the voltage of the DC power supply 200 increases), the LLC control circuit 15d changes the duty ratio of the PWM signal to the discharge lamp 4. It is lowered according to the amount of increase in the applied drive voltage. That is, the control circuit 15 performs feedback control of the switching output circuit 11 (drive circuit 11c) based on the output state of the transformer 12 detected by the detection unit 14.

Since the lighting device 1 according to the present embodiment is provided with the detection unit 14 and the control circuit 15, even if the voltage of the DC power supply 200 fluctuates, fluctuations in the drive voltage applied to the discharge lamp 4 are suppressed. can do. Therefore, even if the voltage of the DC power supply 200 fluctuates, the amount of light emitted from the discharge lamp 4, ultraviolet rays, etc. can be stabilized.

Further, since the LLC resonant circuit including the switching output circuit 11, the transformer 12, and the resonant capacitor 13 is operated intermittently by PWM control, even if the voltage of the DC power supply 200 fluctuates, the voltage applied to the discharge lamp 4 remains constant. The peak value of the drive voltage can be maintained. Therefore, the amount of light emitted from the discharge lamp 4, ultraviolet rays, etc. can be stabilized.

Further, since the lighting device 1 is provided with an LLC resonant circuit having a switching output circuit 11, a transformer 12, and a resonant capacitor 13, switching loss of the circuit can be reduced. Therefore, the circuit efficiency can be improved compared to the case where the discharge lamp 4 is simply lit with a sine wave alternating current. If the circuit efficiency can be improved, the amount of heat generated by the circuit components provided in the lighting device 1 will be reduced, so it is possible to suppress the temperature rise of the circuit components. Examples of the circuit components include the switching element 11a, the switching element 11b, an element provided in the drive circuit 11c, a transformer 12, a resonance capacitor 13, an element provided in the detection unit 14, and an element provided in the control circuit 15. It is.

However, in the case of the lighting device 1 used in the vehicle irradiation device 100, it is necessary to consider that the lighting device 1 is provided in an atmosphere of about 85°C. Further, since the vehicle irradiation device 100 is often installed in a narrow space such as a vehicle interior, it is desired that the lighting device 1 be made smaller. When the lighting device 1 is miniaturized, the distance between the circuit components becomes shorter, and the temperature of the circuit components tends to increase due to thermal interference or the like. If the temperature of the circuit components becomes too high, the functions of the circuit components may deteriorate or the circuit components may malfunction.

Therefore, the lighting device 1 is further provided with a temperature detection element 16 and a temperature compensation circuit 15e.
The temperature detection element 16 is electrically connected to the temperature compensation circuit 15e. The temperature detection element 16 detects the temperature of the atmosphere in which the lighting device 1 is provided. The temperature detection element 16 can be provided inside the housing 2, for example. The temperature detection element 16 can be, for example, a thermistor, a thermocouple, a resistance temperature detector, or the like. However, the temperature detection element 16 is not limited to the one illustrated, and may be any element that can convert temperature information into an electrical signal.

The temperature compensation circuit 15e is electrically connected to the PWM control circuit 15a. The temperature compensation circuit 15e can be provided in the control circuit 15, for example. The temperature compensation circuit 15e changes the duty ratio of the PWM signal in accordance with the temperature when the ambient temperature exceeds a predetermined value. For example, the temperature compensation circuit 15e decreases the pulse width (duty width) in the pulse period as the temperature increases. That is, the temperature compensation circuit 15e lengthens the OFF time (rest period) as the temperature increases. As the OFF time becomes longer, the amount of heat generated by the circuit components decreases, so even if the ambient temperature increases, the temperature rise of the circuit components can be suppressed. Therefore, even if the ambient temperature becomes high, it is possible to prevent the functions of the circuit components from deteriorating or from breaking down.

FIG. 4 is a circuit diagram illustrating the temperature compensation circuit 15e.
Note that FIG. 4 shows a case where the temperature detection element 16 is a thermistor.
As shown in FIG. 4, the temperature compensation circuit 15e includes, for example, a voltage generation circuit 15e1, a switching element 15e2, a triangular wave generation circuit 15e3, and a comparator 15e4.

The voltage generating circuit 15e1 applies a predetermined voltage to the base B of the switching element 15e2 when the ambient temperature is equal to or higher than a predetermined value (for example, 60° C.).
When a predetermined voltage is applied to the base B of the switching element 15e2, the switching element 15e2 is turned on, and a current flows through the temperature detection element 16 (thermistor).
Since the resistance of the temperature detection element 16 (thermistor) changes depending on the temperature, the voltage input to the inverting input (V-) of the comparator 15e4 changes.
The triangular wave generation circuit 15e3 applies a triangular wave voltage to the non-inverting input (V+) of the comparator 15e4.

The comparator 15e4 outputs a predetermined voltage if the voltage at the non-inverting input (V+) (triangular wave voltage) is higher than the voltage at the inverting input (V-) (voltage at point A).
The comparator 15e4 does not output a voltage if the voltage at the non-inverting input (V+) (triangular wave voltage) is lower than the voltage at the inverting input (V-) (voltage at point A).

The output of the temperature compensation circuit 15e (comparator 15e4) is input to the PWM control circuit 15a. The PWM control circuit 15a changes the duty ratio of the PWM signal according to the input from the temperature compensation circuit 15e (comparator 15e4).

FIG. 5 is a timing chart for illustrating the operation of the temperature compensation circuit 15e in FIG.
FIG. 5 shows that when the ambient temperature is 60°C or higher, the temperature compensation circuit 15e performs temperature compensation for the PWM signal, and when the ambient temperature is less than 60°C, the temperature compensation circuit 15e performs temperature compensation for the PWM signal. This is a case where it is not carried out. Note that the switching temperature is not limited to 60° C., and can be changed depending on the temperature margin of the circuit components.

As shown in FIG. 5, when the ambient temperature is 60° C. or higher, a predetermined voltage is output from the comparator 15e4 during a period when the voltage of the triangular wave is higher than the voltage at point A. The PWM control circuit 15a changes the duty ratio of the PWM signal input to the LLC control circuit 15d according to the input from the comparator 15e4.

In this case, if the ambient temperature changes, the voltage at point A changes, so the period during which the predetermined voltage is output from the comparator 15e4 changes.
For example, as shown in FIG. 5, if the ambient temperature decreases in the range of 60° C. or higher, the voltage at point A decreases, so the period during which a predetermined voltage is output from the comparator 15e4 becomes longer. The longer the period during which the predetermined voltage is output from the comparator 15e4, the higher the duty ratio of the PWM signal becomes.

On the other hand, if the temperature of the atmosphere rises, the voltage at point A rises, so the period during which the predetermined voltage is output from the comparator 15e4 becomes shorter. If the period during which the predetermined voltage is output from the comparator 15e4 becomes shorter, the duty ratio of the PWM signal becomes lower. Therefore, temperature rise in circuit components can be suppressed.

That is, with the temperature compensation circuit 15e according to this embodiment, when the temperature of the atmosphere exceeds a predetermined value, the duty ratio of the PWM signal can be changed in accordance with the change in temperature. Therefore, the temperature of the circuit components can be kept within an appropriate range.

When the ambient temperature is less than a predetermined value, temperature compensation of the PWM signal by the temperature compensation circuit 15e can be prevented. For example, if the period (OFF period) in which the predetermined voltage is not output from the comparator 15e4 is longer than a predetermined value, the PWM control circuit 15a can generate, for example, a predetermined PWM signal.

FIG. 6 is a circuit diagram illustrating a lighting device 1a according to another embodiment.
As shown in FIG. 6, the lighting device 1a includes, for example, a switching output circuit 11, a transformer 12, a resonance capacitor 13, a detection section 14, a control circuit 15, and a temperature detection element 16. The control circuit 15 includes, for example, a PWM control circuit 15a, a comparator 15b, a reference voltage section 15c, an LLC control circuit 15d, and a temperature compensation circuit 15e.
The configuration of the lighting device 1a can be the same as the configuration of the lighting device 1 described above. However, in the case of the lighting device 1 described above, the detection section 14 is provided in each of the two transformers 12. On the other hand, in the case of the lighting device 1a, the detection unit 14 is provided in either one of the two transformers 12. That is, the detection unit 14 may be any device that detects the output state of at least one of the two transformers 12.

For example, when the characteristics of the transformer 12 are stable, the feedback control described above may be performed based on the output state of one transformer 12.
In this way, it is possible to reduce the size and cost of the lighting device 1a.

Next, returning to FIGS. 1 and 2, the housing 2, substrate 3, discharge lamp 4, lamp cover 5, wiring 6, window 7, and shield 8 provided in the vehicle irradiation device 100 will be illustrated.
As shown in FIGS. 1 and 2, the casing 2 has a box shape and has a space therein for accommodating the substrate 3, the discharge lamp 4, the lamp cover 5, and the lighting device 1. The thickness T of the casing 2 can be smaller than the planar dimension of the casing 2. The vehicular irradiation device 100 may be installed in a narrow space such as a vehicle interior together with electronic equipment used for operating the vehicle. Therefore, if the thickness dimension T of the housing 2 is small, installation of the vehicle irradiation device 100 becomes easy.

Further, the housing 2 is divided into a first portion 21 and a second portion 22 in the thickness direction of the housing 2. The first part 21 can be, for example, a base on which the substrate 3, the discharge lamp 4, the lamp cover 5 and the lighting device 1 are attached. The second portion 22 can be, for example, a cover that covers the opening side of the first portion 21 . The second portion 22 can be provided with a hole 22a for emitting ultraviolet light or light. The hole 22a can be provided at a position facing the discharge lamp 4.

The second portion 22 can be detachably attached to the first portion 21 . For example, the first portion 21 and the second portion 22 are removably connected by elastic force generated by fitting the opening portions together.

The first portion 21 and the second portion 22 are made of, for example, an insulating resin. In this case, the material of the second portion 22 may be the same as or different from the material of the first portion 21. If the first part 21 and the second part 22 have insulating properties, the distance between the inner walls of the first part 21 and the second part 22 and the discharge lamp 4, lighting device 1, etc. can be shortened. be able to. Therefore, the casing 2 can be easily made smaller and thinner.

The substrate 3 has a plate shape. The substrate 3 is provided on the first portion 21 via, for example, a spacer 31. Note that instead of the spacer 31, the substrate 3 may be provided on a convex portion provided on the first portion 21.

The discharge lamp 4 is located between the substrate 3 and the second part 22. The discharge lamp 4 can be provided at a position facing the hole 22a of the second portion 22. The discharge lamp 4 is removably attached to a pair of terminal holders 41. The pair of terminal holders 41 are provided on the substrate 3, for example. In addition, in FIG. 2, FIG. 3, and FIG. 6, the case where one discharge lamp 4 is provided is illustrated, but a plurality of discharge lamps 4 may be provided. At least one discharge lamp 4 may be provided.

The discharge lamp 4 can be, for example, a mercury lamp, a metal halide lamp, a dielectric barrier discharge lamp, or the like. However, the discharge lamp 4 is not limited to the one illustrated, and may be any type as long as it can irradiate ultraviolet rays or light (for example, visible light).

The lamp cover 5 is located between the substrate 3 and the second part 22. The lamp cover 5 can be provided on the substrate 3, for example. The lamp cover 5 has a box shape and is open at the end opposite to the substrate 3 side. The opening 5a of the lamp cover 5 faces the hole 22a of the second portion 22. Inside the lamp cover 5, a discharge lamp 4 and a pair of terminal holders 41 can be provided. For example, the lamp cover 5 is made of an insulating resin. The material of the lamp cover 5 can be, for example, the same as the material of the housing 2. However, since the lamp cover 5 may be exposed to ultraviolet rays emitted from the discharge lamp 4, it is preferable to use a material that has higher resistance to ultraviolet rays than the material of the housing 2.

If the lamp cover 5 is provided, it is possible to prevent ultraviolet rays and light emitted from the discharge lamp 4 from entering the inner wall of the housing 2, the substrate 3, and the lighting device 1. Therefore, it is possible to suppress deterioration of these components due to ultraviolet rays and the like.

Further, the lamp cover 5 can also have a reflector function. For example, the lamp cover 5 may be made of a white resin, a reflective film may be formed on the inner wall of the lamp cover 5, or the inner wall of the lamp cover 5 may be curved. If the lamp cover 5 has a reflector function, the efficiency of using the ultraviolet rays and light emitted from the discharge lamp 4 can be improved.

One end of the wiring is electrically connected to the lighting device 1 inside the housing 2 . The other end of the wiring is drawn out to the outside of the casing 2 and electrically connected to, for example, a DC power supply 200.

The window 7 is provided in a portion of the housing 2 (second portion 22) where the hole 22a is provided. For example, the window 7 is provided on the inner wall of the second portion 22 and covers the hole 22a. The window 7 transmits ultraviolet rays and light emitted from the discharge lamp 4. The window 7 has, for example, a plurality of openings. The window 7 can be formed, for example, by weaving a plurality of wire rods, or by forming a plurality of openings by etching, pressing, or the like.

Here, if discharge occurs between the electrodes of the discharge lamp 4 when the discharge lamp 4 is turned on, electromagnetic waves may be emitted along with ultraviolet rays and light. Further, when the discharge lamp 4 is turned on, electromagnetic waves may be emitted from the switching elements 11a and 11b provided in the lighting device 1 and the wiring electrically connected to the switching elements 11a and 11b.

The shield 8 suppresses electromagnetic waves generated inside the housing 2 from being radiated to the outside of the housing 2. The shield 8 has conductivity and can be provided on the outer wall of the housing 2, for example. If the shield 8 is conductive, the reflection loss in the shield 8 can be increased, so that electromagnetic waves generated inside the housing 2 can be suppressed from being radiated to the outside of the housing 2. .

Further, as described above, the window 7 is provided with a plurality of openings through which the ultraviolet rays and light emitted from the discharge lamp 4 are transmitted. Therefore, there is a possibility that electromagnetic waves may be radiated to the outside of the housing 2 through the plurality of openings provided in the window 7. Therefore, the window 7 is formed from a conductive material.

The conductive window 7 and shield 8 can be made of metal such as aluminum, for example. Further, the window 7 and the shield 8 are electrically connected to the ground of the vehicle (for example, the frame of the vehicle).

If the conductive window 7 and shield 8 are provided, even if the distance between the vehicle irradiation device 100 and the electronic equipment used for vehicle operation is shortened, electromagnetic waves will not enter the electronic equipment. can be suppressed.

Although several embodiments of the present invention have been illustrated above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, changes, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents. Further, each of the embodiments described above can be implemented in combination with each other.

Furthermore, in one embodiment of the present invention, the vehicle irradiation device 100 including the lighting device 1 has been described, but a modification of the lighting device 1 (for example, the lighting device 1a) may also be applied to the vehicle irradiation device 100. Can be done.

Additional notes regarding the above-described embodiments will be shown below.

(Additional note 1)
A lighting device that applies a driving voltage of a predetermined frequency to a discharge lamp,
a first transformer electrically connected to one electrode of the discharge lamp;
a second transformer electrically connected to the other electrode of the discharge lamp;
It is electrically connected to the primary winding of the first transformer and the primary winding of the second transformer through a resonant capacitor, and is converted into a DC voltage at a predetermined frequency by PWM control. a switching output circuit that converts into voltage;
an LLC control circuit that inputs a PWM signal used for the PWM control to the switching output circuit;
a temperature compensation circuit that changes the duty ratio of the PWM signal in accordance with the temperature when the ambient temperature exceeds a predetermined value;
A discharge lamp lighting device comprising:

(Additional note 2)
The lighting device for a discharge lamp according to supplementary note 1, wherein the temperature compensation circuit lengthens the OFF time in the pulse period as the temperature increases.

(Additional note 3)
a detection unit that detects an output state of at least one of the first transformer and the second transformer;
a comparator that compares the output state detected by the detection unit with a reference value to detect an amount of variation in the drive voltage caused by variation in the DC voltage;
further comprising;
The lighting device for a discharge lamp according to appendix 1 or 2, wherein the LLC control circuit changes the duty ratio of the PWM signal based on the amount of variation in the drive voltage detected by the comparator.

(Additional note 4)
The lighting device for a discharge lamp according to any one of Supplementary Notes 1 to 3, wherein the LLC control circuit intermittently controls the switching output circuit.

(Appendix 5)
A vehicle irradiation device installed in a vehicle;
discharge lamp;
a discharge lamp lighting device according to any one of Supplementary Notes 1 to 4, which is electrically connected to the discharge lamp;
A vehicle irradiation device equipped with.

Reference Signs List 1 lighting device, 1a lighting device, 2 housing, 4 discharge lamp, 11 switching output circuit, 11a switching element, 11b switching element, 11c drive circuit, 12 transformer, 13 resonance capacitor, 14 detection unit, 15 control circuit, 15a PWM control circuit, 15b comparator, 15c reference voltage section, 15d LLC control circuit, 15e temperature compensation circuit, 15e1 voltage generation circuit, 15e2 switching element, 15e3 triangular wave generation circuit, 15e4 comparator, 16 temperature detection element, 100 vehicle irradiation device, 200 DC power supply

Claims (5)

A lighting device that applies a driving voltage of a predetermined frequency to a discharge lamp,
a first transformer electrically connected to one electrode of the discharge lamp;
a second transformer electrically connected to the other electrode of the discharge lamp;
It is electrically connected to the primary winding of the first transformer and the primary winding of the second transformer through a resonant capacitor, and is converted into a DC voltage at a predetermined frequency by PWM control. a switching output circuit that converts into voltage;
an LLC control circuit that inputs a PWM signal used for the PWM control to the switching output circuit;
a temperature compensation circuit that changes the duty ratio of the PWM signal in accordance with the temperature when the ambient temperature exceeds a predetermined value;
A discharge lamp lighting device comprising: 2. The discharge lamp lighting device according to claim 1, wherein the temperature compensation circuit lengthens the OFF time in the pulse period as the temperature increases. a detection unit that detects an output state of at least one of the first transformer and the second transformer;
a comparator that compares the output state detected by the detection unit with a reference value to detect an amount of variation in the drive voltage caused by variation in the DC voltage;
further comprising;
3. The discharge lamp lighting device according to claim 1, wherein the LLC control circuit changes the duty ratio of the PWM signal based on the amount of variation in the drive voltage detected by the comparator. 3. The discharge lamp lighting device according to claim 1, wherein the LLC control circuit intermittently controls the switching output circuit. A vehicle irradiation device installed in a vehicle;
discharge lamp;
A discharge lamp lighting device according to claim 1, which is electrically connected to the discharge lamp;
A vehicle irradiation device equipped with.

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