JP2001155888A - Lighting apparatus for high pressure discharge lamp and light apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting apparatus for high pressure discharge lamp and light apparatus that can be controlled responding to lighting sensing and trouble. SOLUTION: The high pressure discharge lamp HPL is turned on with direct output voltage of a DC-DC converter DCV having flat condenser C between direct output terminals. A negative property of non-straight resistor NTC is connected in series to the flat condenser C between direct output terminals of the DC-DC converter DCV. When the high pressure discharge lamp HPL is turned on, the negative characteristic non-1inear resistor NTC exhibits limiting flowing and projected current is suppressed, converting efficiency can increase. By controlling of the DC-DC converter DCV responding to the terminals voltage of the non-1inear resistor NTC, turning on and trouble of the high pressure discharge lamp HPL are detected to carry out a predetermined control. When current flows to the negative characteristic non-1inear resistor NTC, the terminals voltage is lower responding to flowing of current. Further, it can be protected with a controlling like non turning on and when a disorder is detected, it can be displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high pressure discharge lamp lighting device for lighting a high pressure discharge lamp using a DC-DC converter, and a lighting device using the same.

[0002]

2. Description of the Related Art In a high-pressure discharge lamp lighting device for lighting a small high-pressure discharge lamp for projection or optical fiber, such as a liquid crystal projector or an overhead projector, a high-pressure discharge lamp using a DC-DC converter such as a step-down chopper. There are many things that light up. That is, a high-pressure discharge lamp is connected between the DC output terminals of the DC-DC converter via a starter to perform DC lighting, or is connected via a DC-AC inverter and a starter to perform AC lighting.

[0003] In the case of DC lighting, there is an advantage that the life of the high-pressure discharge lamp can be prolonged and the light utilization rate increases. On the other hand, in the case of AC lighting, there is an advantage that the lamp efficiency is increased.

[0004] In any of the DC lighting and the AC lighting, at the start of lighting, the charge of the smoothing capacitor temporarily becomes an inrush current and flows to the high-pressure discharge lamp of the load. A current limiting resistor is inserted in the smoothing capacitor.

However, in this type of conventional high-pressure discharge lamp lighting device, there is a problem that a power loss occurs when a lamp current flows through a current limiting resistor connected in series to a smoothing capacitor, and conversion efficiency is reduced. .

Therefore, Japanese Patent Application Laid-Open No. Hei 10-241875 uses a negative-characteristic thermistor, which is a kind of negative-characteristic non-linear resistor, for the current-limiting resistance. Since the negative characteristic thermistor is cold at the start of lighting of the high pressure discharge lamp, it exhibits a high resistance value, and therefore exhibits a sufficient current limiting effect to suppress the inrush current. Also, after lighting the high pressure discharge lamp,
Self-heating is caused by the lamp current flowing therethrough, and the resistance value is reduced, so that the power loss is reduced.

On the other hand, in the applications described above, the high pressure discharge lamp does not light even when the starter is operated,
If the lamp voltage is dark without rising even if it is turned on, a retry is performed.

When the high-pressure discharge lamp becomes abnormal, it is promptly detected and replaced with a normal high-pressure discharge lamp or retried several times. If the abnormality continues, the power is turned on again. However, it may be configured to control to stop the lighting operation.

Further, during lighting, the high pressure discharge lamp is controlled as required, such as constant power control.

[0010] Further, when an overcurrent such as a short-circuit current flows during the operation of the high-pressure discharge lamp, it is possible to detect the occurrence of an overcurrent and shut off the lighting power supply.

As described above, in this type of high-pressure discharge lamp lighting device, since the lighting of the high-pressure discharge lamp is detected and necessary control is performed based on the detection, this lighting detection is an important function.

Conventionally, the lamp voltage of a high-pressure discharge lamp is detected by detecting the DC output voltage of a DC-DC converter through a voltage divider composed of a resistor, and lighting is detected based on the detected value. That is, if the lamp voltage changes before and after lighting, and if the high-pressure discharge lamp is lit, the lamp voltage will decrease. If the voltage is lower than a certain reference voltage, it is determined that the lamp is lit. It is determined to be turned on, and the control is shifted to a mode such as power-on.

[0013]

In addition, since the high-pressure discharge lamp causes a malfunction of the high-pressure discharge lamp such as a slow leak, even if the lamp current becomes excessive, the lamp voltage is lower than a normal value. There is a problem that this cannot be detected. Similarly, when a short circuit occurs on the secondary side of the DC-DC converter, this cannot be detected.

[0014] As a result, parts of a circuit such as a DC-DC converter, which is used for lighting a high-pressure discharge lamp, are short-circuited due to excessive current, abnormal temperature rise of winding parts, and switching means is broken. There is fear.

The present invention reduces DC-DC power loss caused by a current limiting resistor connected in series to a smoothing capacitor.
Provided is a high-pressure discharge lamp lighting device capable of improving the conversion efficiency of a converter, accurately lighting a high-pressure discharge lamp and detecting an abnormality, and performing required control or display, and a lighting device using the same. The purpose is to:

[0016]

According to a first aspect of the present invention, there is provided a lighting apparatus for a high pressure discharge lamp, comprising: a DC power supply; and a smoothing capacitor connected between the DC output terminals. A DC-DC converter that obtains a DC output voltage having a value different from the DC power supply voltage; and a high-pressure discharge lamp that is turned on based on the DC output voltage of the DC-DC converter;
A negative characteristic non-linear resistor connected in series with the smoothing capacitor at a DC output terminal of the DC-DC converter; control means for controlling the DC-DC converter according to a terminal voltage of the negative characteristic non-linear resistor; Starting means for starting the lamp.

The definitions and technical meanings of the terms used in the present invention and each of the following inventions are as follows.

<About DC Power Supply> The DC power supply may be any means that can supply a DC voltage, such as a rectified DC power supply or a battery power supply, and is not limited to a specific configuration.

The DC voltage to be supplied is not limited. However, it is preferable that the DC voltage has a value necessary for starting the lighting of the high-pressure discharge lamp, because the structure of the lighting circuit can be simplified.

Further, in general, since a commercial AC power supply is widely used, a rectified DC power supply obtained by rectifying an AC voltage is the most easily obtained DC power supply. In this case, since the DC-DC converter includes a smoothing capacitor and has a function of smoothing the DC output voltage, the DC power supply may output a non-smooth DC.

<About DC-DC Converter> DC-
The DC converter means a DC-DC conversion circuit having switching means, an inductance and a diode as main components, and a DC chopper such as a step-down chopper, a step-up chopper, and a polarity inversion chopper can be used.

However, among the DC-DC converters, the step-down chopper generates a DC output voltage stepped down in proportion to the ratio of the ON time to one cycle, that is, the ON duty, so that the DC output voltage is applied to the high-pressure discharge lamp before and after lighting. Since the control of the voltage to be performed is easy, it is suitable for the present invention.

Further, the DC-DC converter has a current limiting function due to the use of inductance, so that it is not necessary to newly connect a current limiting impedance as a ballast in series with the high pressure discharge lamp. However, the present invention does not exclude the use of a separately provided current limiting impedance.

Further, using a DC-DC converter,
Lighting of the high-pressure discharge lamp can be controlled as desired.
For example, it can be configured to supply a predetermined lamp power to a high-pressure discharge lamp according to a lamp current and / or a lamp voltage. Note that the predetermined lamp power includes constant power and is set so as to provide desired lighting characteristics such as constant current and constant voltage.

In order to light the high-pressure discharge lamp with desired lighting characteristics, the on-duty of the switching means of the DC-DC converter is controlled by a predetermined control according to, for example, the lamp current and / or the lamp voltage. This can be realized by changing the pattern.

<High Pressure Discharge Lamp> A high pressure discharge lamp means a discharge lamp in which an ionized medium enclosed therein exhibits a pressure of about 1 atm or more during operation.
High-pressure mercury lamp, metal halide lamp, etc.

The high-pressure discharge lamp has a light-emitting tube in which a pair of electrodes are sealed at both ends of a translucent discharge vessel and an ionization medium is sealed inside. Note that an outer tube that houses the arc tube as necessary can be used.

Further, "the high-pressure discharge lamp is lit based on the DC output voltage of the DC-DC converter" means that
Either a mode in which the DC output voltage of the C-DC converter is directly applied and DC lighting is performed, or a mode in which the DC output voltage of the DC-DC converter is indirectly applied through a DC-AC inverter or the like to perform lighting. Means that you may.

By the way, in the case of a high-pressure discharge lamp, the following structure is required for a metal halide lamp for a liquid crystal projector, ie, the required luminous characteristics, that is, luminous efficiency,
Preferred results are obtained in terms of correlated color temperature, chromaticity and color rendering. That is, dysprosium Dy, cesium C
s and neodymium Nd as main components, and thallium Tl and / or tin Sn are added as sub-components as necessary,
An appropriate amount of iodine and / or bromine is encapsulated with mercury and a rare gas for these components.

On the other hand, a metal halide discharge lamp for a headlight of a moving body such as an automobile is a lamp mainly containing a halide of sodium Na and scandium Sc and enclosing 1 to 15 atm of xenon as a rare gas. Is preferred.

Further, when the high pressure discharge lamp has a short arc, the distance between the electrodes is generally preferably 6 mm or less, and particularly preferably 4 mm or less.

<Regarding Negative Characteristic Non-Linear Resistor> A negative characteristic non-linear resistor has a non-linear resistance characteristic with respect to temperature.
In addition, it means a resistor having a negative temperature characteristic. That is, the negative characteristic non-linear resistor shows a relatively high resistance value at room temperature, and the resistance value decreases when the temperature rises, and further decreases rapidly when the temperature rises to a predetermined value by energization or the like. Has characteristics.

The negative characteristic non-linear resistor has a current capacity to withstand the lamp current of the high pressure discharge lamp supplied from the smoothing capacitor, that is, a part of the lamp current. Shall be Such a negative characteristic nonlinear resistor can be obtained as a so-called power thermistor.

Furthermore, it is desirable that the resistance of the negative characteristic nonlinear resistor suitable for the present invention be as small as possible when the temperature is raised to a predetermined value. Ideally, it is 0Ω, but in practice, it is about 1Ω. If it is below, there is no problem in practical use.

<Regarding the Control Means> Since a current proportional to the lamp current flows through the negative characteristic non-linear resistor, the lamp current of the high pressure discharge lamp can be detected from the voltage drop. Then, an abnormality such as lighting or non-lighting of the high-pressure discharge lamp can be determined based on the detected value.

Therefore, the terminal voltage of the negative characteristic non-linear resistor is detected to determine whether the high-pressure discharge lamp is turned on or off, and the DC-DC converter can be controlled as required based on the result.

The control means can perform necessary control, for example, constant power control when the high-pressure discharge lamp is turned on, and can perform control such as retry when an abnormality occurs.

More specifically, control after lighting of the high-pressure discharge lamp can be performed by arranging detection means such as a power control detection unit for controlling the DC-DC converter. The control to be performed when the high-pressure discharge lamp is not turned on is so-called retry for restarting the high-pressure discharge lamp. For this purpose, it is necessary to control the DC-DC converter and starting means to be described later as necessary. Can be.

Next, "abnormal" means that the lamp is not lit, an overcurrent flows due to leakage of the high-pressure discharge lamp, a DC-DC
For example, when the DC output of the converter is short-circuited for some reason. In the case of non-lighting or overcurrent, control for turning on the high-pressure discharge lamp again, that is, retry can be performed. In this case, for example, if the non-lighting state continues after retrying for 5 to 10 seconds, control is performed so that the DC output of the DC-DC converter is not applied to the high-pressure discharge lamp even if the power is turned on again. can do.

<Starting Means> The starting means may have any configuration as long as it can start the high-pressure discharge lamp, and various known starting circuits can be employed.

<Operation of the Present Invention> In the present invention, a current proportional to the lamp current of the high-pressure discharge lamp is detected based on the terminal voltage of the non-linear resistor having a negative characteristic, whereby the lighting and non-lighting of the high-pressure discharge lamp are detected. It is possible to make a determination and perform necessary control according to the result of the determination.

In addition to the above, since the negative characteristic non-linear resistor is connected in series with the smoothing capacitor connected to the DC output terminal of the DC-DC converter, the negative characteristic non-linear resistance is started when the high pressure discharge lamp starts lighting. The current limiting device suppresses a large inrush current.

Further, when the high-pressure discharge lamp is turned on, the non-linear resistor generates self-heating due to the lamp current flowing therethrough and rises in temperature, and its resistance value is reduced, so that the power loss is reduced accordingly. As a result, the conversion loss of the DC-DC converter is improved.

According to a second aspect of the present invention, there is provided the high pressure discharge lamp lighting device according to the first aspect.
The negative characteristic nonlinear resistor is characterized in that its terminal voltage is reduced when an overcurrent flows.

According to the present invention, for example, when a high-pressure discharge lamp is short-circuited, when an overcurrent flows through the negative characteristic nonlinear resistor, the terminal voltage is reduced accordingly. Thus, when such an overcurrent flows, the “overcurrent” is turned on by comparing the terminal voltage of the negative characteristic non-linear resistor with a preset threshold.
Can be determined separately.

When an overcurrent is detected, the same control as when the high-pressure discharge lamp is not lit can be performed.

Therefore, the protection operation can be appropriately performed by stopping the DC-DC converter, that is, by stopping the energization of the high-pressure discharge lamp and taking the same measures as in the case of non-lighting.

According to a third aspect of the present invention, there is provided a lighting device, comprising: a lighting device main body; a high-pressure discharge lamp provided in the lighting device main body; ; Characterized by having;

The lighting device according to the present invention is a broad concept including any device that uses a high-pressure discharge lamp for some lighting purpose. For example, a lighting device, a light projection device, a headlight for a moving object, a display device, a photochemical reaction device, and the like are included as the lighting device.

As the lighting equipment, it can be applied to various outdoor and indoor lighting equipment. The light projection device can be applied to a liquid crystal projector, an overhead projector, and the like.

According to a fourth aspect of the present invention, in the lighting device according to the third aspect, when an abnormality is detected in accordance with a terminal voltage of the negative characteristic non-linear resistor of the high pressure discharge lamp lighting device, the abnormality is detected. The lighting device is transmitted to the main body, and is configured to perform required control.

In the present invention, when an abnormality is detected,
The lighting device body is configured to be controlled as required.

"Control as required" includes control such as retrying the lighting device in response to the detected abnormality or displaying the content of the abnormality on the display means. As the abnormality display, for example, when an abnormality is detected, "abnormal", "lamp replacement", or the like is displayed, and the indicator lamp can be turned on continuously or blinking.

Therefore, according to the present invention, handling of the lighting device is facilitated.

[0055]

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

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

In the figure, DC is a DC power supply, DCV is D
C-DC converter, CM is control means, NTS is a negative characteristic non-linear resistor, LCD is a lamp current detection circuit, ST is starting means, and HPL is a high pressure discharge lamp.

<About DC power supply DC> DC power supply DC
Outputs a DC voltage of 300V.

<About DC-DC Converter DCV>
The DC-DC converter DCV includes a converter main body a and a power control detection unit, and obtains a DC voltage necessary for lighting the high-pressure discharge lamp HPL, and performs desired lighting such as constant-power lighting of the high-pressure discharge lamp HPL. Function to control.

The converter body a constitutes a step-down chopper circuit, and has switching means Q, a diode D, an inductor L and a smoothing capacitor C as main components.

That is, the switching means Q is formed of a bipolar transistor, the collector of which is a DC power supply D.
Drive signal generation circuit D
A drive signal is supplied from the SG to perform on / off switching at a high frequency.

The diode D has an anode connected to the negative electrode of the DC power supply DC and a cathode connected to the emitter of the switching means Q.

Further, one end of the inductor L is connected to the emitter of the switching means Q and the cathode of the diode D.

Further, the smoothing capacitor C is connected between the other end of the inductor L and the negative electrode of the DC power supply DC via a power control detection unit b described later.

Next, the power control detecting section b comprises a voltage detecting circuit or the like, the input terminal of which is connected between the other end of the inductor L and the negative electrode of the DC power supply DC, and the smoothing capacitor C connected to the output terminal. Have been.

<Regarding the Control Means CM> The Control Means CM
Is a drive signal generation circuit DS according to a judgment output of a power control detection unit b and a lamp current detection circuit LCD described later.
G is controlled to control the repetition frequency and / or on-duty of the drive signal.

<Regarding Negative Characteristic Non-Linear Resistor NTC> The negative characteristic non-linear resistor NTC is composed of a power thermistor, and is connected in series with the smoothing capacitor C between the DC output terminals of the DC-DC converter DCV.

<Regarding Lamp Current Detection Circuit LCD> The lamp current detection circuit LCD has a negative characteristic non-linear resistor NTC.
Control input of the terminal voltage of the high-pressure discharge lamp HP
The lamp current of L is detected, and lighting and abnormality (non-lighting, overcurrent) of the high-pressure discharge lamp NPL are determined based on the lamp current. Then, based on the determination result, the control means C
Control M.

<Regarding the Starting Means ST> The starting means ST
Consists of a pulse generation circuit, and a DC-DC converter D
A pulse voltage is generated by being energized by the DC output voltage of the CV, and the generated pulse voltage is converted to a DC-DC converter DCV
Is connected in parallel to the DC output terminal of the DC-DC converter DCV so as to be superimposed on the output voltage of the DC-DC converter DCV.

<High Pressure Discharge Lamp HPL> The high pressure discharge lamp HPL is a short arc type metal halide lamp having a rated lamp power of 440 W and a rated lamp voltage of 60 V, as will be described later with reference to FIG. S
It is connected between the DC output terminals of the DC-DC converter DCV via T.

<Circuit operation> High pressure discharge lamp HP
To light L, turn on DC power supply DC
-The switching means Q of the DC converter DCV is in an ON state with an ON duty of 100%. At this time, 300 V of the DC power supply voltage is directly applied to the high-pressure discharge lamp HPL.

When the starting means ST operates, the pulse voltage is superimposed on the DC output voltage of the DC-DC converter and applied to the high-pressure discharge lamp GHL.

For this reason, the high pressure discharge lamp HPL is started by the breakdown of the enclosed ionizing medium by the high voltage, and is turned on.

When the high-pressure discharge lamp HPL is turned on, the lamp voltage decreases, and the charge of the smoothing capacitor C tries to rapidly enter the high-pressure discharge lamp HPL as a lamp current. Since the resistance exhibits a current limiting effect, the inrush of the lamp current is suppressed. In this state, the resistance of the negative characteristic nonlinear resistor NTC is large.

When the high-pressure discharge lamp HPL is turned on, the charge of the smoothing capacitor C flows into the high-pressure discharge lamp HPL through the negative-characteristic non-linear resistor NTC as a part of the lamp current. A terminal voltage proportional to the lamp current appears at both ends of the device NTC. Then, the terminal voltage is control-input to the lamp current detection circuit LCD, and lighting is determined. When the lighting is determined, the control signal is inputted to the control means CM, so that the control means c controls the drive signal generation circuit DSG to generate a drive signal having a required on-duty, and the switching means Q
To perform a switching operation.

As a result, the DC-DC converter DCV
Performs a step-down chopper operation to generate a DC output voltage stepped down from a DC power supply voltage.

The step-down chopper operation of the DC-DC converter DCV is as follows.

That is, when the switching means Q is on, the positive terminal of the DC power supply DC, the switching means Q, the inductor L, the smoothing capacitor C, the negative characteristic non-linear resistor NT
An increasing current flows through the path of C and the negative electrode of the DC power supply DC, and electromagnetic energy is accumulated in the inductor L.

Next, when the switching means Q is turned off,
The electromagnetic energy stored in the inductor L is released and flows through the path of the inductor L, the smoothing capacitor C, the negative characteristic nonlinear resistor NTC, the diode D, and the inductor L.

Thereafter, the above operation is repeated at a high frequency. As a result, the DC power supply voltage is Vin, the DC output voltage is Vout,
The on time of the switching means Q is Ton and the off time is Tof
Assuming that f, the stepped-down DC output voltage Vo substantially expressed by the following equation
ut is obtained at both ends of the smoothing capacitor C.

Vout = Vin {Ton / (Ton + Toff)} In the above equation, Ton / (Ton + Toff) indicates a so-called on-duty. Therefore, by controlling the on-duty of the switching means Q, the high-pressure discharge lamp H is controlled.
It can be understood that, by controlling the DC output voltage applied to the PL, the lamp power flowing into the high-pressure discharge lamp HPL can be controlled, for example, at a constant power.

On the other hand, after the high-pressure discharge lamp HPL is turned on, the power control detector b detects the lamp power supplied to the high-pressure discharge lamp HPL, and accordingly, the control means C
M, and the control means CM further controls and inputs to the drive signal generation circuit DSG. By setting a required control pattern in the control means CM (or the power control detection unit b), a required control pattern is set. , For example, constant power control.

Next, when the high-pressure discharge lamp HPL causes a problem such as a slow leak to generate an overcurrent, an overcurrent flows through the negative characteristic nonlinear resistor NTC. At this time, the negative characteristic non-T
As a result of generating much self-heating, the resistance value of the Y struggling resistor NTC is significantly reduced. Therefore, the lamp current detection circuit LCD determines that the high-pressure discharge lamp HPL is not lit.

Therefore, the control means c controls the drive signal generation circuit DSG to stop the generation of the drive signal, so that the DC-DC converter DCV stops the operation and performs the protection operation. For this reason, an abnormal temperature rise of the high pressure discharge lamp lighting device can be prevented, and it is possible to prevent a serious problem such as smoking and ignition from developing.

FIG. 2 is a sectional view showing a first example of a high-pressure discharge lamp device suitable for use in the first embodiment of the high-pressure discharge lamp lighting device of the present invention, together with a lighting circuit.

In the figure, the high-pressure discharge lamp device comprises a high-pressure discharge lamp HPL and a reflector M. BC is a base cement, CC is a connection conductor, and OC is a high pressure discharge lamp lighting device.

The high-pressure discharge lamp HPL comprises a translucent discharge vessel 1, an anode 2, a cathode 3, a sealing metal foil 4, an insulator 5, external introduction wires 6, 7 and a discharge medium.

The translucent discharge vessel 1 is made of quartz glass and comprises an elliptical spherical enclosing portion 1a and a pair of sealing portions 1b, 1b extending outward from both ends of the enclosing portion 1a.

The anode 2 and the cathode 3 are sealed in the enclosing portion 1a of the translucent discharge vessel 1 with the tips thereof being close to each other, and their base ends are hermetically embedded in a pair of sealing portions 1b. Is welded to the sealed metal foil 4.

The insulator 5 is fixed to the outer surface of the sealing portion 1b on the anode side.

One external introduction wire 6 is welded to the sealing metal foil 4 on the anode 2 side, though not shown.

The other external introduction wire 7 is welded to the sealing metal foil 4 on the cathode side.

The discharge medium is made of a halide of a luminescent metal, mercury, and a rare gas.
a.

The reflecting mirror M comprises a base 8a and a reflecting surface 8b.

The base 8a is formed into a paraboloid of revolution by glass molding, and has a neck 8a1 at the top and a through hole 8a2 at the paraboloid of revolution.

The reflection surface 8b is composed of a multilayer light interference film 2c formed on the inner surface of the base 8a, and reflects visible light and transmits infrared light.

The high-pressure discharge lamp HPL is obtained by inserting the insulator 5 into the neck portion 8a1 and fixing the insulator 5 and the neck portion 8a1 with the ferrule BC.
A high-pressure discharge lamp device is formed integrally with the reflecting mirror M.

One end of the connection conductor CC is connected to the external introduction line 7 of the high-pressure discharge lamp HPL, the middle part passes through the light transmission 8a2 of the reflector M, and the other end is led out to the back side of the reflector M. ing.

The high pressure discharge lamp lighting device OC is the first embodiment of the present invention shown in FIG. 1, and its output terminal is connected to external introduction lines 6 and 7 via a connection conductor CC or the like.

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

In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The present embodiment is different from the first embodiment in that a display means DP is provided in addition to the configuration of the first embodiment so that an abnormality can be displayed.

That is, when the lamp current detection circuit LCD detects an abnormality, the display means DP displays the fact.

FIG. 4 is a circuit diagram showing a third embodiment of the high pressure discharge lamp lighting device according to the present invention.

In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

This embodiment is different in that the high-pressure discharge lamp is operated by AC.

That is, the DC-AC inverter INV is interposed between the DC-DC converter DCV and the starting means ST.

As the DC-AC inverter INV, a full-bridge inverter, a half-bridge inverter, or the like can be used.

FIG. 5 is a sectional view showing a second example of a high-pressure discharge lamp device suitable for use in the third embodiment of the high-pressure discharge lamp lighting device of the present invention, together with a lighting circuit.

In the figure, the same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

The present embodiment is different in that the high-pressure discharge lamp HPL includes a pair of electrodes 3 having the same structure and is configured for AC lighting.

FIG. 6 is a circuit diagram showing a high-pressure discharge lamp lighting device according to a fourth embodiment of the present invention.

In the figure, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description is omitted.

This embodiment relates to a DC-AC inverter IN
While using a full-bridge type inverter as V,
The starting means ST is configured using a discharge gap. In the figure, reference numeral 11 denotes a DC power supply unit. The DC power supply unit 11 includes the DC-DC converter DVC, the negative characteristic nonlinear resistor NTC, and the lamp current detection circuit LC in FIG.
D.

<About the DC-AC inverter INV>
The DC-AC inverter INV has a bridge connection of four switching means Q1 to Q4, and has an input terminal connected to DC-AC.
Connected to DC output terminal of DC converter DCV. The output terminal is connected to the secondary winding 13s of the step-up transformer 13 for starting.
Is connected to the high-pressure discharge lamp HPL.

Then, the four switching means Q1 to Q1
Q1 and Q3 with Q4 connected to the opposing arm
And Q2 and Q4 are turned on and off alternately, thereby outputting a high-frequency rectangular AC wave between its output terminals, and the AC voltage is applied to the high-pressure discharge lamp HPL.

<Regarding the Starting Means ST> The starting means ST
Comprises a starting voltage generating means 12, a starting step-up transformer 13, and a high frequency bypass capacitor C2.

(Regarding the Starting Voltage Generating Means 12) The starting voltage generating means 12 includes a first relaxation oscillation circuit 12a and a second relaxation oscillation circuit 12b.

The first relaxation oscillation circuit 12a includes a series circuit of a resistor 12a1 and a capacitor 12a2 connected between the DC output terminals of the DC power supply unit 11, and one end of the capacitor 1a.
Trigger diode 12a connected between both ends of 2a2
3 and a primary winding p of an insulating transformer 12b11 described later.

The second relaxation oscillation circuit 12b includes a capacitor charging circuit 12b1 and a capacitor discharging circuit 12b2.

The capacitor charging circuit 12b1 includes an insulating transformer 12b11, a diode 12b12, and a plurality of capacitors 12b13 connected in parallel.

The insulating transformer 12b11 has one end of the primary winding p connected to one end of the capacitor 12a2 via the trigger diode 12a3 of the first relaxation oscillation circuit 12a, and the other end connected to the other end of the capacitor 12a2. ing. One end of the secondary winding s of the insulating transformer 12b11 is connected to the cathode of the diode 12b12, and the other end is connected to one end of the capacitor 12b12.

The anode of the diode 12b12 is connected to the other end of the capacitor 12b13.

The capacitor discharging circuit 12b2 includes a pair of gaps 12b21 and a primary winding 13p of the starting step-up transformer 13.

The pair of gaps 12b21 are connected in series, one end of the series circuit is connected to the connection point of the capacitor 12b13 and the diode 12b12, and the other end is connected to one end of the primary winding 13p of the starting step-up transformer 13. I have. The other end of the primary winding 13p is connected to the capacitor 12b13
Is connected to the other end.

(Regarding the Starting Step-Up Transformer 13) The starting step-up transformer 13 has its secondary winding 13s connected in series to the high-pressure discharge lamp HPL as described above.

(Regarding the High Frequency Bypass Capacitor 14) The high frequency bypass capacitor 14 is a secondary winding 13s of the high pressure discharge lamp HPL and the starting step-up transformer 13.
Is connected in parallel to the series part.

<Circuit Operation> When the DC output voltage of the DC power supply unit 11 is applied to the first relaxation oscillation circuit 12a, the terminal voltage of the capacitor 12a2 increases according to the time constant time. The terminal voltage is the trigger diode 1
When the trigger voltage of 2a3 is exceeded, the trigger diode 12a3 is turned on, and the charge of the capacitor 12a3 is transferred via the trigger diode 12a3 to the insulating transformer 12b.
11 to the primary winding p. And the capacitor 12
When the terminal voltage of a3 decreases, the capacitor 12a3 is charged again from the DC power supply unit 11 via the resistor 12a1, and the same circuit operation is repeated as described above. Generate input voltage.

On the other hand, when an input voltage is applied to the primary winding p of the insulating transformer 12b11, a boosted voltage corresponding to the turns ratio is induced in the secondary winding s. The induced voltage of the secondary winding s is half-wave rectified by the diode 12b12 to charge the capacitor 12b13.

When the charging voltage of the capacitor 12b13 increases, the gap 12b21 discharges, and a primary voltage appears between the terminals of the primary winding 13p of the starting step-up transformer 13.
Therefore, the secondary winding 13s of the starting step-up transformer 13
, A secondary voltage stepped up by the turn ratio appears. Then, the secondary voltage of the starting step-up transformer 13 is applied to the high-pressure discharge lamp HPL as a required starting voltage.

Since the starting voltage applied to the high-pressure discharge lamp HPL bypasses the high-frequency bypass capacitor 14, it does not flow out to the DC power supply unit 11 side.

FIG. 7 is a conceptual diagram showing a liquid crystal display device as one embodiment of the lighting device of the present invention.

In the figure, 21 is a high-pressure discharge lamp device,
22 is a liquid crystal display means, 23 is an image control means, 24 is an optical system, 25 is a high pressure discharge lamp lighting device, 26 is a main body case, and 27 is a screen.

The high-pressure discharge lamp device 21 is the same as that shown in FIG.

The liquid crystal display means 22 displays an image to be projected by liquid crystal, and is illuminated from the back by a high-pressure discharge lamp device 21.

The image control means 23 drives and controls the liquid crystal display means 22, and can have a television receiving function if necessary.

The optical system 24 projects the light passing through the liquid crystal display means 22 onto the screen 27.

The high pressure discharge lamp lighting device 25 has the same configuration as the reference character OC in FIG.

The main body case 26 is provided with each of the above elements 21 to 2
6 is stored.

[0140]

According to the first and second aspects of the present invention, in addition to the configuration for lighting a high-pressure discharge lamp based on the DC output voltage of a DC-DC converter having a smoothing capacitor between the DC output terminals, a DC-DC converter is provided. Control means for connecting a negative characteristic non-linear resistor in series with the smoothing capacitor between the DC output terminals of the converter and controlling the DC-DC converter according to the terminal voltage of the negative characteristic non-linear resistor Thereby, the lighting and abnormality of the high-pressure discharge lamp can be reliably determined according to the terminal voltage of the non-linear resistor, and necessary control can be performed according to the result.
At the start of lighting, the negative characteristic non-linear resistor exhibits a current-limiting effect to suppress the inrush current from flowing from the smoothing capacitor, and after lighting, self-heating occurs due to the lamp current flowing there, reducing the resistance value. A high pressure discharge lamp lighting device with reduced power loss and improved conversion efficiency can be provided.

According to the second aspect of the present invention, in addition, the terminal voltage is reduced when an overcurrent flows through the negative characteristic non-linear resistor. Thus, a high pressure discharge lamp lighting device capable of appropriately performing a protective operation by performing the same treatment as in the above case can be provided.

According to the invention of claim 3, it is possible to provide a lighting device having the effects of claims 1 and 2.

According to the fourth aspect of the present invention, when an abnormality is detected in accordance with the terminal voltage of the negative characteristic nonlinear resistor, the abnormality is transmitted to the lighting device main body, and the lighting device main body performs required control. With such a configuration, a lighting device that can be easily handled can be provided.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing a first example of a high-pressure discharge lamp device suitable for use in the first embodiment of the high-pressure discharge lamp lighting device of the present invention, together with a lighting circuit.

FIG. 3 is a circuit diagram showing a second embodiment of the high pressure discharge lamp lighting device of the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of the high pressure discharge lamp lighting device of the present invention.

FIG. 5 is a sectional view showing a second example of a high-pressure discharge lamp device suitable for use in the third embodiment of the high-pressure discharge lamp lighting device of the present invention together with a lighting circuit.

FIG. 6 is a circuit diagram showing a fourth embodiment of the high pressure discharge lamp lighting device of the present invention.

FIG. 7 is a conceptual diagram showing a liquid crystal display device as one embodiment of the lighting device of the present invention.

[Explanation of symbols]

 DC: DC power supply DCV: DC-DC converter a: Converter body Q: Switching means D: Diode L: Inductor C: Smoothing capacitor b: Power control detection section CM: Control means DSG: Drive signal generation circuit NTC: Negative characteristic non-linear Resistor LCD ... Lamp current detection circuit ST ... Starting means HPL ... High pressure discharge lamp

Claims (4)

[Claims] 1. A DC power supply, comprising: a smoothing capacitor connected between DC output terminals, for converting a DC power supply voltage to obtain a DC output voltage having a value different from the smoothed DC power supply voltage.
A C-DC converter; a high-pressure discharge lamp that is turned on based on the DC output voltage of the DC-DC converter;
A negative characteristic non-linear resistor connected in series with the smoothing capacitor at the DC output end of the C converter; control means for controlling the DC-DC converter according to the terminal voltage of the negative characteristic non-linear resistor; A high-pressure discharge lamp lighting device, comprising: starting means for starting. 2. The high pressure discharge lamp lighting device according to claim 1, wherein the negative characteristic non-linear resistor is configured so that its terminal voltage decreases when an overcurrent flows. 3. A lighting device main body; a high-pressure discharge lamp provided in the lighting device main body; and a high-pressure discharge lamp lighting device according to claim 1 or 2 for lighting the high-pressure discharge lamp. Lighting device characterized by the following. 4. When an abnormality is detected in accordance with a terminal voltage of a negative characteristic non-linear resistor of a high pressure discharge lamp lighting device, the abnormality is transmitted to a lighting device main body, and the lighting device main body performs a required control. The lighting device according to claim 3, wherein the lighting device is used.