JP2000048976A - High pressure discharge lamp lighting circuit, high pressure discharge lamp lighting device, and image display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of a lamp life and lamp startability caused by input voltage fluctuation, and extinction at the time of start, to improve a lamp start characteristic at the time of arc transition, and to allow a small- sized starter circuit to be used. SOLUTION: A timer circuit 16 for inputting an input voltage or an output voltage of a chopper circuit 13 and making variable a high voltage pulse generating time for lamp starting in response to the level of the voltage is provided in a high pressure discharge lamp lighting device provided with the chopper circuit 13 as a stabilized power source circuit, a starter circuit 14 for inputting a chopper output voltage at the time of starting to generate a high voltage pulse, and a high pressure discharge lamp 15 started based on the high voltage pulse and driven by the chopper output voltage at the time of stable lighting. A high voltage pulse generating number for lamp starting is made constant irrespective of the level of the input voltage or the output voltage at the time of no load before starting the high pressure discharge lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high pressure discharge lamp lighting circuit, a high pressure discharge lamp lighting device, and an image display device.

[0002]

2. Description of the Related Art Conventionally, in a high-pressure discharge lamp such as a metal halide lamp, if the distance between the electrodes is large, the high-pressure discharge lamp lighting device is configured as an AC lighting system in order to prevent color unevenness. For this reason, in order to prevent extinguishing at the time of discharge reversal, the discharge lamp lighting circuit requires a secondary open-circuit voltage that is greater than 2.5 times the maximum output voltage during lamp lighting (when the lamp is stable). . This point is that even in the later-described DC lighting method, which is shifting in recent years, the discharge lamp lighting circuit is designed to stabilize the transition characteristic from glow discharge to arc discharge at the restart with respect to the maximum output voltage during lamp lighting. It is general to set the secondary side open voltage larger than 2.5 times.

By the way, when attention is paid to a high-pressure discharge lamp, in recent years, a short arc in which a point light source is formed by bringing the electrodes as close as possible has been advanced, and the distance between the electrodes in the lamp has been reduced to about 3 mm, for example. The color unevenness, which has been a problem in the past, has been reduced to a level that does not cause a problem with the short arc, and thus the DC lighting method is becoming mainstream. For the short arc type,
In the case of the DC lighting method, it has been reported that there is little turbidity on the tube wall during the service life, and there is a good point that the luminous flux maintenance rate is good, and furthermore, the discharge lamp lighting circuit has an output polarity inversion circuit. Since it is not necessary to provide such a method, it is a convenient method for achieving small size and high efficiency.

However, in the case of the DC lighting system, the resistance component in the polarity inversion circuit portion in the AC lighting system is completely lost, so that a high-level smoothing circuit for DC provided in the output stage in the discharge lamp lighting circuit is required. Since a starting circuit such as a pulse transformer that generates a voltage pulse is directly connected, the rush current flowing through the high-pressure discharge lamp at the moment when an arc transition occurs at the time of starting the lamp, as compared with an AC lighting type lighting circuit. It tends to be larger. If the starting circuit part is further reduced in pursuit of miniaturization, the inductance of the pulse transformer will also be reduced, so the inrush current flowing through the high-pressure discharge lamp at startup will be even greater, and the sealed part with less current capacity Cracks occur from the foil bonding portion of the, and it is easy to cause a slow leak or a lamp rupture. Also, with the increase of the rush current when starting the lamp,
Since the vibration also increases, a zero cross of the current occurs, and the discharge may be extinguished, and the lamp may not start. In order to prevent this, the miniaturization of the pulse transformer is kept to a minimum, a certain inductance value is secured, and the rush current is flattened to prevent the lamp from being damaged.

Conventionally, in a high pressure discharge lamp lighting device, when a restart or a lamp cannot be started, generation of a high voltage pulse is automatically stopped after a lapse of a predetermined time by a timer circuit or the like. . This has been carried out for the purpose of preventing the danger caused by the high voltage and the purpose of ensuring the life of the discharge lamp lighting circuit.

FIG. 13 is a block diagram showing an outline of a conventional high pressure discharge lamp lighting apparatus of a DC lighting system for a short arc type high pressure discharge lamp. In the figure, an AC voltage from a commercial AC power supply 1 is rectified and smoothed by a full-wave rectifier circuit 2 to obtain an input DC voltage, and the DC voltage is supplied to a chopper type switching power supply circuit (hereinafter referred to as a chopper circuit) 3 as a stabilized power supply circuit. To obtain a stabilized DC voltage. As the chopper circuit, for example, a step-down chopper circuit is used. The step-down chopper circuit includes a switching element to which a rectified DC voltage is input, a smoothing circuit including a flywheel diode and an LC filter connected to a subsequent stage, and an on / off period (or switching frequency) of the switching element and the like. And a control circuit for controlling according to a change in voltage or output power so as to obtain a constant voltage or constant power output. The stabilized DC voltage from the chopper circuit 3 is supplied through the starting circuit 4 between the anode and the cathode of the high-pressure discharge lamp 5. In the preceding stage of the starting circuit 4, an integrating circuit comprising a resistor R0 and a capacitor C0 is connected between the plus and minus terminals of the chopper circuit 3, and a bidirectional switching having a predetermined breakover voltage at a connection point between the resistor R0 and the capacitor C0. When the lamp is started by turning on the AC power supply 1, a no-load voltage is output from the chopper circuit 3, and the capacitor C0 is charged by the no-load output voltage. When the voltage exceeds the breakover voltage, the SIDAC D0 conducts and the high pressure discharge lamp 5 is turned on. After the high-pressure discharge lamp 5 is turned on, the lamp voltage (that is, the output voltage of the chopper circuit) across the high-pressure discharge lamp 5, which is a load, is considerably lower than the voltage at the time of no load. The starting circuit 4 is stopped without exceeding the breakover voltage, and is turned on.

However, in the conventional discharge lamp lighting device, when the input DC voltage of the chopper circuit 3 fluctuates due to the fluctuation of the AC power supply 1, or when the voltage of the commercial AC power supply is different, such as when used overseas. As a result, the no-load output voltage of the chopper circuit 3 also fluctuates, and the time required for the charging voltage of the capacitor C0 to reach the breakover voltage of the Sidac D0 also fluctuates. Changes. Normally, when the input voltage of the chopper circuit 3 increases, the no-load output voltage also increases, so that the time required for the charging voltage of the capacitor C0 to reach the breakover voltage of the Sidac D0 is shortened, and the generation period of the high voltage pulse is shortened. The number of high-voltage pulses generated within a certain time increases. Therefore, when the input voltage is high,
The number of times of use, such as the gas-filled switching gap in the starting circuit 4, makes it more susceptible to components whose characteristics deteriorate. There is a possibility that the characteristics become unstable early and the startability deteriorates, or in some cases, the operation is completely stopped.

[0008] In the case of a model that can be used both in Japan and abroad, there is a possibility that malfunctions may occur early in overseas, even if there is no problem in Japan. For this reason, changing the component constant for each destination value,
Special work was required.

In order to prevent this problem, the gas-filled switching gap is provided with a trigger function to make the pulse generation cycle constant, or to make the input circuit constant to suppress the fluctuation of the no-load voltage. I have.

[0010] However, these components have a remarkable increase in the number of parts, and increase in weight and cost is inevitable.

As another countermeasure, there is a method in which a design is made on the basis of a pulse generation cycle at the maximum input voltage to provide a large margin at the normal input voltage. In some cases, the number of high-voltage pulses generated becomes very small, and the starting characteristics are deteriorated. In the case of a model for both domestic and international use, the starting performance may be deteriorated during domestic use.

Further, in the conventional high pressure discharge lamp lighting device, immediately after the high pressure discharge lamp is started, both the lamp voltage and the lamp current are very unstable. In particular, in the case of a type in which a plurality of encapsulated metals solidify in the lamp or the electrode when the lamp is not lit, such as a metal halide lamp, the discharge starting point (bright point) on the electrode easily moves immediately after the lamp is started, and the lamp voltage becomes extremely high. fluctuate. As a result, in the case of a conventional lighting circuit designed mainly for stable control, if the lamp state detection value at the time of starting the lamp significantly fluctuates, the lamp goes out. This extinction is due to the fact that the lamp current is reduced by the constant power control when the lamp voltage temporarily sharply increases. Immediately after the lamp is started, the tip of the electrode is not sufficiently heated. If the current is reduced in this state, the discharge cannot be maintained.

Further, with the advancement of potting technology (such as resin encapsulation) in a starting circuit portion for generating a high-voltage pulse for starting a high-pressure discharge lamp, a higher voltage than before can be output safely, and instantaneous restart and the like can be performed. It is now possible. Also,
It has also become possible to achieve a very small size while maintaining a sufficient pulse voltage.

However, the recent miniaturized starting circuit has a very small inductance value of the pulse generating transformer, and thus has excellent dielectric breakdown resistance, but has an arc transfer like a conventional large starting circuit. There was no stabilizing effect at the time, and a separate coil had to be installed on the lighting circuit side. For this reason, even if the starting circuit itself can be very small, a large coil must be installed separately to obtain stable starting characteristics. there were.

[0015]

As described above, in the conventional high pressure discharge lamp lighting apparatus, when the input DC voltage fluctuates or when an AC power supply having a voltage different from that in Japan such as in a foreign country is used, a high voltage When the pulse generation cycle changes, especially when the input voltage increases, the number of pulse outputs increases, causing the characteristics to become unstable early, deteriorating the startability, and in some cases failing to operate completely. there were.

Immediately after the start of the high-pressure discharge lamp, the lamp voltage and the lamp current are both extremely unstable. Since the control is performed, when the lamp voltage temporarily increases steeply, there is a problem that the lamp current is reduced and the lamp goes out.

Furthermore, in the conventional high pressure discharge lamp lighting device, when the size of the coil in the pulse transformer in the starting circuit is reduced, an additional coil is required to prevent an inrush current and obtain stable starting characteristics. Therefore, there has been a problem that the overall size is insufficiently reduced.

Therefore, the present invention provides a method of controlling the high-pressure discharge lamp at one start even if the no-load voltage supplied from the stabilized power supply circuit to the high-pressure discharge lamp changes with the change of the input DC voltage. A high-pressure discharge lamp lighting circuit, a high-pressure discharge lamp lighting device, and an image display device in which the number of high-voltage pulses supplied thereto is fixed so that the life characteristics and lamp startability of the lamp and the circuit are not affected by changes in input voltage. The purpose is to provide.

The present invention also provides a high-pressure discharge lamp lighting circuit, a high-pressure discharge lamp lighting device, and an image display device which can ensure the stability of the high-pressure discharge lamp at the time of starting and in particular prevent the lamp from extinction at the time of starting. The purpose is to provide.

Further, the present invention provides a high pressure discharge lamp lighting circuit and a high pressure discharge lamp lighting method capable of improving the lamp starting characteristics at the time of arc transition even if the inductance value of a coil including a pulse transformer used in the lighting circuit is reduced. It is an object to provide a device and an image display device.

[0021]

According to a first aspect of the present invention, there is provided a high pressure discharge lamp lighting circuit including a switching element for output control and a smoothing circuit, for switching a DC power supply voltage supplied as an input, and a smoothing circuit. A stabilized power supply circuit for controlling the output DC power by smoothing the power supply; generating a high-voltage pulse for starting at a frequency corresponding to the level of the no-load output voltage from the stabilized power supply circuit to generate a high-voltage discharge. A starting circuit to be applied to the lamp; and a control for varying the generation time of the starting high-voltage pulse according to the level of the input voltage or the output voltage of the stabilized power supply circuit when there is no load before starting the high-pressure discharge lamp. A timer circuit for performing the operation.

According to a second aspect of the present invention, in the high pressure discharge lamp lighting circuit according to the first aspect, the timer circuit includes a pulse generation time when the input voltage or the output voltage of the stabilized power supply circuit is low when no load is applied. Is controlled to be long, and when high, the pulse generation time is controlled to be short;

According to the first and second aspects of the present invention, the stabilized power supply circuit includes a switching element for controlling output power, for example, a switching transistor, and controls the output power to the high-pressure discharge lamp to be stable. A step-down chopper circuit or the like for lamp power control may be used. As the starting circuit, one having a pulse transformer is used. For the pulse transformer, the primary winding and the secondary winding may be separate, but a single winding sharing the primary winding is used. It may have a line structure. When the lamp is started, the DC power supply voltage supplied as an input to the stabilized power supply circuit fluctuates, and even if the no-load output voltage of the stabilized power supply circuit changes, the number of pulses output continuously during one start It can be controlled to keep the maximum value constant. For this reason,
The deterioration characteristic of the life and the deterioration of the starting characteristic due to the number of times of lamp lighting do not depend on the fluctuation of the input power supply voltage.

A high pressure discharge lamp lighting circuit according to a third aspect of the present invention has a switching element for output control and a smoothing circuit, and switches a DC power supply voltage supplied as an input, and smoothes the output by a smoothing circuit. A stabilized power supply circuit for controlling power; a starting circuit for receiving an output DC voltage from the stabilized power supply circuit, generating a high-voltage pulse for starting and applying the pulse to a high-pressure discharge lamp; A detection circuit for detecting a voltage and a current on the output side; and controlling on / off of a switching element of the stabilized power supply circuit in accordance with a detection value of the detection circuit so as to make power supplied to the high-pressure discharge lamp constant. A control circuit for controlling;
Means for detecting whether a stable region has been reached after starting the high-pressure discharge lamp, and disabling constant power control of the control circuit before reaching the stable region.

According to a fourth aspect of the present invention, in the high pressure discharge lamp lighting circuit according to the third aspect, the means for invalidating the constant power control is provided by a separately provided lamp voltage comparison and detection means after the high pressure discharge lamp is started. When a region where the lamp voltage is lower than a predetermined value is detected, a switch means is provided for preventing the detection value of the detection circuit from being supplied to the control circuit.

According to a fifth aspect of the present invention, in the high pressure discharge lamp lighting circuit according to the third aspect, an input current detection circuit for detecting an input current input to the stabilized power supply circuit is further provided; Means for detecting that an input current detection value from the input current detection circuit exceeds a predetermined value after starting the high-pressure discharge lamp, and the control circuit limits the output current of the stabilized power supply circuit to a predetermined value. To be performed;

According to the third to fifth aspects of the present invention, the constant power control designed mainly when the lamp is stable is not performed in the unstable range from immediately after the lamp is started until the lamp is stably operated. As a result, unnecessary control for fluctuations on the lamp side from immediately after the start of the lamp to stable lighting can be suppressed, and a stable rise without extinguishing can be realized.

A high pressure discharge lamp lighting circuit according to a sixth aspect of the present invention has a switching element for output control and a smoothing circuit, and switches a DC power supply voltage supplied as an input, and smoothes the output DC voltage by a smoothing circuit. A stabilizing power supply circuit for controlling electric power; a starting circuit having a pulse transformer for generating a high-voltage pulse for starting and applying the pulse to a high-pressure discharge lamp; and supplying power from the stabilized power supply circuit to the high-pressure discharge lamp. A coil connected in series with an output line to be connected; between an output line of the stabilized power supply circuit where the coil is not installed, and an end of the coil on the side of the stabilized power supply circuit,
A rectifying element connected in a direction such that a lamp current at the time of stabilization does not flow from the stabilized power supply circuit side of the coil to the output line side.

In the invention according to claim 6, for example, a diode is used as the rectifying element. When an inrush current zero-cross occurs at the time of starting the high-pressure discharge lamp, a current flows through the rectifying element so as to suppress the inrush-current zero-cross, so that the startability can be improved without extinguishing. Therefore, even if a small coil having a small inductance value is used as the coil connected in series with the output line for supplying power from the stabilized power supply circuit to the high-pressure discharge lamp, the startability can be ensured.

According to a seventh aspect of the present invention, there is provided a high pressure discharge lamp lighting device comprising: a high pressure discharge lamp lighting circuit according to any one of the first to sixth aspects; and a pair of electrodes opposed to each other in a bulb. And a high-pressure discharge lamp which is started and maintained by the lighting circuit.

In the invention according to claim 7, the high-pressure discharge lamp is a so-called short-circuit in which an anode and a cathode are arranged to be extremely close to each other, such as about 3 mm, in a bulb in which a halogen compound is sealed as a light emission contributing medium. Lamps such as arc-type metal halide lamps are used. In this case, a near conductor such as a wire having the same potential as that of the cathode may be provided on the outer periphery of the lamp near the cathode. When used as a light source for an image display device, for example, a highly efficient 250 W
Lamps are used.

[0032] The image display device according to the eighth aspect is the seventh aspect.
An image data output device for outputting image data of an image to be displayed; receiving the irradiation light of the high pressure discharge lamp and the image data output from the image data output device, and responding to the image data. And an image forming unit for forming an image.

In the invention according to the eighth aspect, the image display device includes a liquid crystal video projector, a projection device, an overhead projector and the like. As for the liquid crystal video projector, a screen projection method or a method of directly viewing an image displayed on the liquid crystal itself may be used. As the image data output device and the image forming unit, those corresponding to the image display device are used. For example, in the case of a liquid crystal video projector, a device that outputs a video signal according to the NTSC system, a liquid crystal device, or the like is used.

[0034]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a high pressure discharge lamp lighting device according to a first embodiment of the present invention. Here, an outline of a DC lighting type high pressure discharge lamp lighting device for a short arc type high pressure discharge lamp is shown.

In FIG. 1, an AC voltage from a commercial AC power supply 11 is rectified and smoothed by a full-wave rectifier circuit 12 to obtain an input DC power supply voltage, and the DC voltage is supplied to a chopper circuit 13 as a stabilized power supply circuit to be stabilized. Obtain a direct current. As the chopper circuit 13, for example, a step-down chopper circuit is used. The step-down chopper circuit includes a switching element to which a rectified DC voltage is input, a smoothing circuit including a flywheel diode and an LC filter connected to a subsequent stage, and an on / off period (or switching frequency) of the switching element and the like. And a control circuit for controlling according to a change in voltage or output power so as to obtain an output of constant power. The stabilized DC voltage from the chopper circuit 13 is supplied through the starting circuit 14 between the anode and the cathode of the high-pressure discharge lamp 15. A time constant circuit comprising a resistor R0 and a capacitor C0 is connected between the plus and minus terminals of the chopper circuit 13 at a stage preceding the starting circuit 14, and a bidirectional circuit having a predetermined breakover voltage at a connection point between the resistor R0 and the capacitor C0. A circuit formed by connecting a Sidac D0 as a switching element is provided. When the lamp is started by turning on the AC power supply 11, a no-load voltage (voltage before starting the lamp) is output from the chopper circuit 13. The capacitor C0 is charged by the output voltage, and when the charged voltage exceeds the breakover voltage, the Sidac D0 conducts and the starting circuit 14 operates to supply a high voltage pulse between the electrodes of the high pressure discharge lamp 15. Discharge the lamp and turn it on. The starting circuit 14 has, for example, a pulse transformer. Further, the starting circuit 14 may use a gas-filled switching gap inside. After the high pressure discharge lamp 15 is turned on, the high pressure discharge lamp
5 Since the lamp voltage at both ends (that is, the output voltage of the chopper circuit) is considerably lower than the voltage at no load, the capacitor C
The charging voltage of 0 does not exceed the breakover voltage of Sidac D0 (that is, the starting circuit 14 does not generate a high voltage pulse), and the lighting state is maintained.

Further, in the present embodiment, when there is no load before starting the high-pressure discharge lamp 15, the generation time of the starting high-voltage pulse by the starting circuit 14 is varied according to the level of the input voltage of the chopper circuit 13. A timer circuit 16 for performing control is provided. The timer circuit 16 has a time constant circuit formed by connecting a resistor R1 and a capacitor C1 in series between a plus terminal of the full-wave rectifier circuit 12 and a reference potential point for providing ground, and a connection point between the R1 and C1. A control signal terminal of a switch means for turning on / off a pulse generating circuit (not shown, but not shown) of a pulse generating circuit (not shown) in the starting circuit 14 through, for example, a zener diode D1. ). Therefore, when the lamp is started, the positive input voltage of the chopper circuit 13 is supplied to the capacitor C1 of the time constant circuit, and when this is charged, when the charged voltage to the capacitor C1 reaches the breakover voltage of the Zener diode D1. , The Zener diode D1 becomes conductive, and a pulse generation stop signal is supplied to the starting circuit 14, so that the starting circuit 14 stops generating a high voltage pulse. In addition, when the input voltage fluctuates due to a voltage fluctuation of the AC power supply 11 or a difference in the standard of the AC power supply 11 (for example, overseas specification), the capacitor C1 is changed according to the magnitude of the input voltage to the chopper circuit 13. Because the charging speed of the input voltage is different, the time until the breakover voltage is reached differs depending on the level of the input voltage. That is, if the input voltage is high, the pulse generation stop signal from the timer circuit 16 to the starting circuit 14 is supplied earlier in time, and if the input voltage is low, the pulse generation stop signal is supplied later in time. Become.

Next, the operation of generating a high-voltage pulse in the apparatus shown in FIG. 1 will be described.

The output voltage of the full-wave circuit 12, that is, the input voltage V0 of the chopper circuit 13 is different from the normal state or the used standard due to the voltage fluctuation of the AC power supply 11 or the difference in the standard of the AC power supply 11. In this case, the output voltage of the chopper circuit 13 also differs depending on the level of the input voltage V0. When the input voltage V0 is high and the output voltage of the chopper circuit 13 is high, the time required for the charging voltage of the charging capacitor C0 of the time constant circuit to reach the breakover voltage of the Sidac D0 becomes shorter, and the charging and discharging of the capacitor C0 is shortened. The frequency of the high voltage pulse generated by the starting circuit 14 generated by the above becomes higher. Conversely, when the input voltage V0 is low and the output voltage of the chopper circuit 13 is low, the time until the charging voltage of the charging capacitor C0 reaches the breakover voltage of the Sidac D0 becomes longer, and the capacitor C0
The frequency of the high voltage pulse generated by the charging and discharging of the battery becomes low. Therefore, as shown in FIGS. 2 (a) and 2 (b), when the input voltage V0 is high, the frequency of the high voltage pulse is high, that is, the period of generation of the high voltage pulse is short, and when the input voltage V0 is low, The frequency of the high voltage pulse is low, that is, the period of generation of the high voltage pulse is long. This is the same in the case of the conventional example described with reference to FIG. In the present embodiment, a timer circuit 16 for varying the high voltage pulse generation time of the starting circuit 14 to regulate the number of pulse generations in accordance with the input voltage V0.
When the input voltage V0 is high, the pulse generation stop signal from the timer circuit 16 to the starting circuit 14 is supplied earlier in time, and as shown in FIG. (This is determined by the input voltage V0)
Only a high voltage pulse will be generated. Input voltage V
When 0 is low, the pulse generation stop signal from the timer circuit 16 to the starting circuit 14 is supplied later in time, and
As shown in (b), a high-voltage pulse is generated for a fixed time t2 (which is longer than the time t1 determined by the input voltage V0) after the power is turned on.

From the above, when the lamp is started, even if the input DC voltage supplied to the chopper circuit 13 which is a stabilized power supply circuit fluctuates and the no-load output voltage of the chopper circuit 13 changes, one start operation is performed. It is possible to control so that the maximum value of the number of pulses output continuously at times is constant. Therefore, there is an advantage that the deterioration characteristic of the life and the deterioration of the starting characteristic due to the number of times of lamp lighting do not depend on the input voltage fluctuation.

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

In the second embodiment, the input voltage of the chopper circuit 13 is supplied as an input to the timer circuit 16 as in the first embodiment, but different from the first embodiment, The output of the circuit 16 is connected to a control terminal of the chopper circuit 13 (that is, a control signal terminal of a switch (not shown) for turning on and off the operation of the chopper circuit 13). In other words, in the present second embodiment, the output of the timer circuit 16 causes the chopper circuit 13
Is configured to perform control for varying the operation time of the control. Also in the case of the present embodiment, the timer circuit 16 is, as a result, equivalent to performing control to vary the generation time of the starting high-voltage pulse by the starting circuit 14. The same operation and effect as in the first embodiment can be obtained.

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

In the third embodiment, the chopper circuit 1
3 is supplied to the timer circuit 16 as an input, and the output of the timer circuit 16 is supplied to the ON / OFF control terminal (ie, not shown) of the pulse generating circuit (not shown) in the starting circuit 14 in the same manner as in the first embodiment. , A control signal terminal of a switch means for turning on and off a pulse generating circuit in the starting circuit 14). Since the output voltage of the chopper circuit 13 changes according to the level of the input voltage, the same effects as those of the first and second embodiments can be obtained in this embodiment.

FIG. 5 is a block diagram showing a high pressure discharge lamp lighting device according to a fourth embodiment of the present invention.

In the fourth embodiment, the output voltage of the chopper circuit 13 is supplied as an input to the timer circuit 16 as in the third embodiment, but different from the third embodiment, The output of the circuit 16 is connected to a control terminal of the chopper circuit 13 (that is, a control signal terminal of a switch (not shown) for turning on and off the operation of the chopper circuit 13). In other words, in the fourth embodiment, the output of the timer circuit 16 causes the chopper circuit 13 in the preceding stage of the starting circuit to operate.
Is configured to perform control for varying the operation time of the control unit. Also in the case of the present embodiment, the timer circuit 16
This is equivalent to performing control to vary the generation time of the starting high voltage pulse by the starting circuit 14, and the same operation and effect as those of the first to third embodiments can be obtained.

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

In FIG. 6, an AC voltage from a commercial AC power supply 11 is rectified and smoothed by a full-wave rectifier circuit 12 to obtain an input DC power supply voltage, and the DC voltage is supplied to a chopper circuit 13 as a stabilized power supply circuit to be stabilized. Obtain a DC voltage. As the chopper circuit 13, for example, a step-down chopper circuit is used. The step-down chopper circuit includes a switching element to which a rectified DC voltage is input, and a smoothing circuit connected to a subsequent stage by a flywheel diode and an LC filter. The on-off period of the switching element is provided outside the chopper circuit 13. (Or switching frequency)
And the like in accordance with a change in the output voltage or output power of the smoothing circuit so that a constant power output can be obtained. Output voltage and current)
And a detection circuit 17 for supplying the same. Detection circuit 1
Reference numeral 7 denotes a lamp voltage detecting circuit in which voltage dividing resistors of resistors R2 and R3 are connected in series between a plus output terminal of the chopper circuit 13 and a ground point (reference potential point), and a detected voltage is obtained from the connection point; And a lamp current detection circuit comprising a current detection resistor R4 inserted in series with the output line of the circuit 13. The voltage value detected by the detection circuit 17 is
It is supplied to the control terminal of the control circuit 18 via one switch of the switch means 20 composed of two switches,
Further, the detected current value is supplied to another control terminal of the control circuit 18 through the other switch of the switch means 20 composed of two switches. The two switches constituting the switch means 20 are turned on and off at the same time according to the comparison detection result of the comparison detection circuit 19. The comparison detection circuit 19
When the detected value of the lamp voltage detecting circuit by the resistors R2 and R3 is inputted to one input terminal and the voltage of the reference voltage source E is supplied to the other input terminal, and the lamp voltage detected value is larger than the reference value, A comparison detection signal is output when the lamp voltage is higher than a predetermined value. The two switches of the switch means 20 are turned on when the comparison detection signal is output from the comparison detection circuit 19, and when the comparison detection signal is not output from the comparison detection circuit 19, that is, when the lamp is started. When the lamp voltage is smaller than a predetermined value, the lamp is turned off. Therefore, when the lamp voltage is equal to or higher than the predetermined value (for example, when the lamp is stable after lighting), the control circuit 18 is supplied with the detected values of the voltage and the current from the detection circuit 17, and the control circuit 18 detects the detected value. By controlling the lamp voltage and lamp current to generate a switching control signal and controlling the switching elements in the chopper circuit 13, constant power control is performed. When the lamp voltage is smaller than the predetermined value (for example, when the lamp is unstable immediately after starting the lamp), the control circuit 18 is not supplied with the detected values of the voltage and current from the detection circuit 17, and the control circuit 18 detects the detected voltage and current. The field-back control based on the lamp voltage and the lamp current is not performed, and only the switching elements in the chopper circuit 13 are turned on and off at a predetermined on-duty by dead time control. Thus, when the lamp voltage is smaller than a predetermined value (for example, when the lamp is unstable immediately after starting the lamp), the feedback control is not performed in a state where the lamp voltage and the lamp current are unstable.

The DC output from the chopper circuit 13 is supplied through the starting circuit 14 between the anode and the cathode of the high-pressure discharge lamp 15. Inside the starting circuit 14,
It is assumed that a trigger circuit is built-in. Here, the starting circuit 14 generates a high-voltage pulse in a cycle based on an internal trigger and supplies the high-voltage pulse between the electrodes of the high-pressure discharge lamp 15 to discharge the lamp and turn it on. High pressure discharge lamp 15
After the lamp is turned on, the lamp voltage across the high-pressure discharge lamp 15 as a load (that is, the output voltage of the chopper circuit 13) drops below the voltage when no load is applied. Will be maintained.

According to the configuration of the fifth embodiment, in the region where the lamp voltage is low immediately after the lamp is started, the detection results of the voltage and current on the lamp side can be invalidated, and stable lighting can be achieved immediately after the lamp is started. It is possible to improve the stability in the period up to and prevent the disappearance due to the feedback control at the time of instability. Further, it is possible to improve the luminous flux rising quality at the time of starting.

FIG. 7 is a block diagram showing a high pressure discharge lamp lighting device according to a sixth embodiment of the present invention.

In the sixth embodiment, the comparison detection circuit 19 and the switch means 20 of the fifth embodiment are deleted, and the detection values of the lamp voltage and the lamp current from the detection circuit 17 are constantly transmitted to the control circuit 18. Input is enabled, and in addition to the configuration of the fifth embodiment, an input current input to the chopper circuit 13 is detected by inserting, for example, a resistor R5 in series with the input line of the chopper circuit 13. The control circuit 18 detects that an input current detection value from the input current detection circuit 21 exceeds a predetermined value after starting the high-pressure discharge lamp, and The duty control is performed so as to limit the input current to a predetermined value.

Next, the operation of the sixth embodiment shown in FIG. 7 will be described with reference to FIG.

In FIG. 8, the horizontal axis represents the chopper circuit 1
The output voltage Vout of the chopper circuit 13 is shown on the vertical axis, and the output current Vout of the chopper circuit 13 is shown on the vertical axis. A1 indicates a constant power control curve based on the detection value of the detection circuit 17;
In the case where the detected value to the reference numeral 8 is only from the detection circuit 17, control is performed so that constant power can be obtained along the characteristic curve A1 (including the solid line and the broken line) regardless of when the lamp is started and when the lamp is stabilized. Will be A2 indicates an input current limit line based on an input current detection value of the detection circuit 21;
When the lamp current exceeds a predetermined value IL, the current is limited to a constant value IL.
In the region where the lamp voltage is low immediately after the lamp is started, as shown by the broken line portion of A1, control is performed to prevent the lamp current from sharply increasing, that is, to limit the lamp current to a constant value IL to prevent an overcurrent. In the region where the lamp voltage is low, the constant power control based on the detection value of the detection circuit 17 can be made ineffective. Note that the limit value IL is
For example, it may be set near the upper limit of the rated current value of the high-pressure discharge lamp 15. By performing such a control, the normal lamp voltage and the normal
It is possible to suppress flicker and overshoot in a region where the control is switched to lamp current detection, and it is possible to start the luminous flux without a sense of incongruity.

FIG. 9A is a block diagram showing a high pressure discharge lamp lighting device according to a seventh embodiment of the present invention. FIG. 9 (b) is a conventional example corresponding to FIG. 9 (a) of the present invention, and is shown to explain the difference from FIG. 9 (a).

FIG. 9A is different from the conventional circuit of FIG. 9B in that a diode D3 as a rectifying element is added.

In FIG. 9A, an AC voltage from a commercial AC power supply 11 is rectified and smoothed by a full-wave rectifier circuit 12 to obtain an input DC power supply voltage, and the DC voltage is supplied to a chopper circuit 13 as a stabilized power supply circuit. To obtain a stabilized DC voltage. As the chopper circuit 13, for example, a step-down chopper circuit is used. The step-down chopper circuit includes a switching element Q such as a switching transistor to which a rectified DC voltage is input.
And the flywheel diode D2 connected to the subsequent stage
And a control circuit for controlling an on / off period (or switching frequency) of the switching element Q in accordance with a change in the output power of the smoothing circuit to obtain a constant power output. And a circuit (not shown). The output from the chopper circuit 13 is supplied to the anode of the high-pressure discharge lamp
It is supplied between the cathodes.

The starting circuit 14 generates a high-voltage pulse for a certain time at the same time as the power is turned on, and outputs a high-voltage pulse from the primary winding L0 to the secondary winding L1 of the pulse transformer 23. The secondary winding L1 of the pulse transformer 23 is connected to the high-pressure discharge lamp 15 in series. Also, chopper circuit 1
A coil L3 is connected in series with an output line for supplying power from the power supply 3 to the high-pressure discharge lamp 15. This coil L3
Is the secondary winding L with the downsizing of the pulse transformer 23.
This coil L3 is also small in size and has an inductance value smaller than that used in the conventional circuit, although it is inserted to compensate for the small inductance of FIG. Further, the chopper circuit 13
An output line b where the coil L3 is not installed,
Between the coil L3 and the output line side b from the chopper circuit side a of the coil L3
A diode D3 as a rectifying element is connected in such a direction that a lamp current does not flow in a stable state.

The high-voltage pulse from the starting circuit 14 is applied to the high-pressure discharge lamp 15 through the pulse transformer 23 for a certain period of time to discharge the high-pressure discharge lamp 15 and light it.

Next, the operation at the time of starting the lamp shown in FIG.
This will be described with reference to FIGS. FIG. 10 shows FIG.
FIG. 11A shows a lamp voltage and a lamp current at the time of starting in the present embodiment, and FIG. 11 shows a lamp voltage and a lamp current at the time of starting in the conventional example of FIG. 9B.

First, the operation of the conventional example shown in FIG. 9B will be described with reference to FIG. 11. When the power supply 11 is turned on and output from the chopper circuit 13, the starting circuit 14 operates and the high-voltage pulse Is applied to the high-pressure discharge lamp 15 via the pulse transformer 23. The output voltage V1, from the time when the high pressure discharge lamp 15 is started by this high voltage pulse,
The lamp current I1 is shown in FIGS. 11 (a) and 11 (b), respectively. At the start of the lamp, glow discharge starts first, as shown in FIG. 11 (a), and then transitions to arc discharge. At the transition to the arc, an inrush current flows as shown in FIG. 11 (b). Then, when the output voltage V1 enters a state where the polarity crosses with zero crossing as shown in FIG. 11A, the lamp current I1 becomes close to zero as shown in FIG. In some cases, the tip is not sufficiently heated, so that the discharge cannot be maintained and the state transitions to the extinguishing state. After the extinction, the lamp current I1 becomes zero, and the output voltage V1 becomes the output voltage of the chopper circuit 13 when there is no load.

Next, the operation of the embodiment of the present invention shown in FIG. 9A will be described with reference to FIG. 10. When the power supply 11 is turned on and output from the chopper circuit 13, the starting circuit 14 operates at the same time. Thus, a high voltage pulse is applied to the high pressure discharge lamp 15 via the pulse transformer 23. The output voltage V1 and the lamp current I1 from the start of the high-pressure discharge lamp 15 with this high-voltage pulse are shown in FIGS. 10 (a) and 10 (b), respectively. When the lamp is started, the glow discharge first enters the glow discharge and then the arc discharge as shown in FIG. 10 (a). At the transition to the arc, an inrush current flows as shown in FIG. 10 (b). Then, at the moment when the output voltage V1 tries to cross zero as described in FIG. 11A, a current flows from the minus side b to the plus side a of the chopper circuit 13 through the diode D3, and the lamp current I1 flowing through the coil L3.
Has a current value sufficient to maintain the discharge as shown in FIG. 10 (b), and it is possible to prevent the occurrence of extinction. At this time, the output voltage V1 follows the change in the lamp current I1, but the voltage V1 shifts to a stable lamp voltage without reversing the polarity.

According to the seventh embodiment described above, when a rush current zero-cross occurs at the time of starting the high-pressure discharge lamp 15, a current flows through the rectifier diode D3 so as to suppress the rush-current zero-cross, and the extinction occurs. The startability can be improved without any problem. Therefore, even if a small coil having a relatively small inductance value is used as the coil L3 connected in series with the output line for supplying power from the chopper circuit 13 to the high-pressure discharge lamp 15,
Startability can be ensured.

Next, an image display device using the high pressure discharge lamp lighting device of the present invention will be described with reference to FIG.

FIG. 12 is a block diagram showing a schematic configuration of an image display device according to the eighth embodiment of the present invention. The image display device 31 is, for example, an application example to a liquid crystal video projector, and is a method of projecting an image on a screen 32. The image display device 21 includes a high-pressure discharge lamp lighting device 33 having a configuration as shown in each of the embodiments of FIGS. 1, 3 to 5, 6 and 7, and FIG. An output device 34 and an image forming unit 35 are provided.
As the image forming unit 35, for example, an image forming liquid crystal system is used. Here, as the high-pressure discharge lamp 15,
A high-efficiency 250 W metal halide lamp that can be used even in a bright room is used.

In such a configuration, the irradiation light in the form of a point light source from the high-pressure discharge lamp 15 is given to the image forming section 35. On the other hand, the image data output device 34 is, for example, NTSC
The image data according to the method is provided to the image forming unit 35 and driven according to the image data. Therefore, the image forming unit 35 is configured to control the irradiation light of the high-pressure discharge lamp 15 and the image data output device 3.
4 to form an image according to the image data given. This image is projected on the screen 32.

According to such an image display device 31, the high-pressure discharge lamp 15, which functions as a point light source of the short arc type, is lit by a miniaturized lighting circuit without fear of inrush current, lamp breakage or extinguishing. , Image data can be displayed. That is, it is possible to provide an image display device having excellent startability.

In the above-described embodiment, the high-pressure discharge lamp is configured to be lit by direct current, but may be configured to be lit by alternating current using a known polarity inversion circuit or the like.

[0068]

According to the first and second aspects of the present invention, when the lamp is started, the DC voltage supplied to the power supply circuit as an input fluctuates, and even if the no-load output voltage of the power supply circuit changes, one time. The maximum value of the number of pulses that are continuously output at the time of starting can be kept constant, so that the deterioration characteristics of the life of the lamp and circuit due to the number of times of lamp lighting and the starting characteristics can be suppressed from being dependent on input fluctuations. A lighting device can be realized.

According to the third to fifth aspects of the present invention, in the unstable discharge region from immediately after the start of the lamp to the stable lighting,
This is to prevent output control based on the detected voltage and current values on the lamp side. As a result, unnecessary control for fluctuations on the lamp side from immediately after the start of the lamp to stable lighting can be suppressed, and a stable rise without extinguishing can be realized. It is possible to improve the stability of the starting characteristics and the quality of rising of the luminous flux.

According to the present invention, when a rush current zero-cross occurs at the time of starting the high-pressure discharge lamp, a current flows through the rectifying element so as to suppress the rush-current zero-cross, thereby preventing extinction and improving the starting characteristics. Can be achieved. Therefore, even if a small coil having a relatively small inductance value is used as a coil inserted in series with a high-pressure discharge lamp together with a small pulse transformer, the startability can be improved by the inrush current zero-cross suppression effect. .

According to the seventh aspect of the present invention, since the high pressure discharge lamp lighting circuit according to any one of the first to sixth aspects is used, the short arc type high pressure discharge lamp can be replaced with a compact lighting circuit. As a result, the lamp can be stably lit without fear of inrush current, lamp damage, extinguishing, etc.

According to the invention of claim 8, since the high pressure discharge lamp lighting device of claim 7 is used for a light source device,
The short arc type high pressure discharge lamp can be lit by a miniaturized lighting circuit without fear of rush current, lamp damage, extinguishing, etc., so that image data can be displayed favorably.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a high-pressure discharge lamp lighting device according to a first embodiment of the present invention.

FIG. 2 is a view for explaining the operation of FIG. 1;

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

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

FIG. 5 is a block diagram showing a high pressure discharge lamp lighting device according to a fourth embodiment of the present invention.

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

FIG. 7 is a block diagram showing a high pressure discharge lamp lighting device according to a sixth embodiment of the present invention.

FIG. 8 is a view for explaining the control operation of FIG. 7;

FIG. 9 is a block diagram showing a high-pressure discharge lamp lighting device according to a seventh embodiment of the present invention.

FIG. 10 is a view for explaining the operation of FIG. 9 (a).

FIG. 11 is a view for explaining the operation of FIG. 9 (b).

FIG. 12 is a block diagram illustrating a schematic configuration of an image display device according to an eighth embodiment of the present invention.

FIG. 13 is a block diagram showing an example of a conventional high pressure discharge lamp lighting device of a DC lighting type for a short arc type high pressure discharge lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Commercial AC power supply 12 ... Full-wave rectifier circuit 13 ... Chopper circuit (stabilized power supply circuit) 14 ... Starting circuit 15 ... High-pressure discharge lamp 16 ... Timer circuit 17 ... Lamp voltage and lamp current detection circuit 18 ... Control circuit 19 ... Comparison Detection circuit 20 switch means 21 input current detection circuit 31 image display device 33 high pressure discharge lamp lighting device 34 image data output device 35 image forming unit

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) CC01 DD02 FD01 FD11 FD31 FD41 FG05 XC12

Claims (8)

[Claims] 1. A stabilized power supply circuit having a switching element for output control and a smoothing circuit, switching a DC power supply voltage supplied as an input, and controlling an output DC power by smoothing with a smoothing circuit; A starting circuit for generating a high-voltage pulse for starting at a frequency corresponding to the level of the no-load output voltage from the stabilized power supply circuit and applying the pulse to the high-pressure discharge lamp; A high-pressure discharge lamp lighting circuit, comprising: a timer circuit for performing control to vary the generation time of the starting high-voltage pulse according to the level of an input voltage or an output voltage of the stabilized power supply circuit. 2. The method according to claim 1, wherein the timer circuit controls the pulse generation time to be long when the input voltage or the output voltage of the stabilized power supply circuit under no load is low, and to shorten the pulse generation time when the input voltage or the output voltage is high. The high pressure discharge lamp lighting circuit according to claim 1. 3. A stabilized power supply circuit having a switching element for output control and a smoothing circuit, switching a DC power supply voltage supplied as an input, and controlling the output DC power by smoothing with a smoothing circuit; A starting circuit that receives an output DC voltage from the stabilized power supply circuit, generates a high-voltage pulse for starting and applies the pulse to a high-pressure discharge lamp; and a detection circuit that detects a voltage and a current at the output side of the stabilized power supply circuit. A control circuit that controls on / off of a switching element of the stabilized power supply circuit in accordance with a detection value of the detection circuit so as to control power supplied to the high-pressure discharge lamp to be constant; Means for detecting whether or not the vehicle has reached the stable region, and disabling constant power control of the control circuit before the vehicle reaches the stable region. Discharge lamp lighting circuit. 4. The means for disabling the constant power control is provided when a lamp voltage comparison and detection means provided separately detects an area where the lamp voltage after starting the high pressure discharge lamp is lower than a predetermined value. 4. The high pressure discharge lamp lighting circuit according to claim 3, further comprising switch means for preventing a detected value of the circuit from being supplied to the control circuit. 5. The system according to claim 1, further comprising: an input current detection circuit for detecting an input current input to the stabilized power supply circuit; 4. The high-pressure discharge lamp according to claim 3, wherein the control circuit limits the output current of the stabilized power supply circuit to a predetermined value upon detecting that the input current detection value exceeds a predetermined value. Lighting circuit. 6. A stabilized power supply circuit which has a switching element for output control and a smoothing circuit, switches a DC power supply voltage supplied as an input, and controls the output DC voltage by smoothing with a smoothing circuit; A starting circuit having a pulse transformer for generating a high-voltage pulse for starting to apply to the high-pressure discharge lamp; a coil connected in series with an output line for supplying power from the stabilized power supply circuit to the high-pressure discharge lamp And between an output line of the stabilized power supply circuit where the coil is not installed and an end of the coil on the side of the stabilized power supply circuit, when the coil is stabilized from the stabilized power supply circuit side to the output line side. And a rectifier connected in a direction in which the lamp current does not flow. 7. A high-pressure discharge lamp lighting circuit according to claim 1, comprising a pair of electrodes opposed to each other in a bulb, and being started and maintained by the high-pressure discharge lamp lighting circuit. And a high-pressure discharge lamp. 8. The high pressure discharge lamp lighting device according to claim 7,
An image data output device that outputs image data of an image to be displayed; an image forming unit that receives the irradiation light of the high-pressure discharge lamp and the image data output from the image data output device, and forms an image corresponding to the image data; An image display device comprising: