JP2010092883A - Discharge lamp lighting device and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of restraining rapid increase of lamp power and lessening melting of an electrode tip and deterioration of illumination, and a projector having the discharge lamp lighting device. <P>SOLUTION: A control circuit 15 calculates electric power supplied to a high-pressure discharge lamp from voltage equivalent to lamp voltage detected by a voltage detection circuit and drive current detected by a current detection circuit after starting the high-pressure discharge lamp by an ignitor 13, and makes a down-chopper 11 control the drive current so as to set up an increased value per unit time of electric power at a designated value or below when the electric power is less than the designated power value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device and a projector incorporating the discharge lamp lighting device, and more particularly to control of drive current at the time of starting a lamp.

  A conventional discharge lamp lighting device is, for example, “constant current control for controlling the supply current to the discharge lamp by switching at the beginning of lighting when the lamp voltage is low, and switching lamp for the stable period when the lamp voltage is stable. In a discharge lamp lighting device that performs constant power control for controlling power supplied to the switching element, the ratio between the conduction period and the non-conduction period of the switching element is controlled by converting the switching frequency of the switching element, and further, an abnormality In the state, the switching frequency becomes a preset lower limit value and the conduction period of the switching element is shortened ”is proposed (see, for example, Patent Document 1).

Japanese Patent No. 2942113 (Claim 1)

  A conventional discharge lamp lighting device starts up a high-pressure discharge lamp (hereinafter also referred to as a lamp), then increases the lamp voltage, supplies a constant driving current until the lamp power reaches the rated power, and after reaching the rated power, Constant power control is performed so that the lamp power is constant. The lamp voltage depends on the pressure in the arc tube, and the pressure in the arc tube increases due to a temperature increase due to lamp emission and an increase in the number of molecules due to mercury evaporation accompanying the temperature increase. Further, in the case of a lamp with a secondary mirror, the temperature further rises due to the return light emitted by the secondary mirror itself, and the pressure in the arc tube rapidly increases. However, since a constant driving current is supplied, the lamp power also increases rapidly as the lamp voltage increases rapidly. The rapid increase in lamp power has a problem that the impact load of electrons applied to the electrode tip in the arc tube is rapidly increased, and as a result, the electrode tip melts. In addition, the melting of the electrode tip causes a problem that the discharge arc becomes large and illuminance deterioration occurs.

  The present invention has been made to solve such problems. By controlling the drive current at the time of starting the lamp, the rapid increase of the lamp power is suppressed, and the melting of the electrode tip and the deterioration of illuminance are prevented. It is an object of the present invention to provide a discharge lamp lighting device that can be reduced and a projector incorporating the same.

  A discharge lamp lighting device according to the present invention inputs a DC voltage and performs a current control for supplying a predetermined power to a high-pressure discharge lamp, and an output current of the DC voltage power circuit with a predetermined frequency. An inverter that converts the alternating current into a high-pressure discharge lamp and supplies a drive current to the high-pressure discharge lamp; an igniter that is connected to the output side of the inverter and generates a high voltage at start-up to start the high-pressure discharge lamp; A voltage detection circuit for detecting a voltage corresponding to a lamp voltage; a current detection circuit for detecting a current corresponding to a driving current of the high-pressure discharge lamp; and a control means for controlling the DC voltage power supply circuit, the inverter and the igniter. The control means includes a voltage corresponding to a lamp voltage detected by the voltage detection circuit after the high pressure discharge lamp is started by the igniter, and the current. The power supplied to the high-pressure discharge lamp is obtained from the drive current detected by the output circuit, and when the power is less than a predetermined power value, the direct current is increased so that the increase rate of the power is not more than a predetermined value. The power supply circuit controls the drive current. In the present invention, the drive current is controlled so that the rate of increase in the power supplied to the high-pressure discharge lamp is below a predetermined value. For this reason, the lamp accompanying a rapid rise in the lamp voltage at the start of the lamp A rapid increase in power can be suppressed, and melting of the tip of the lamp electrode and deterioration of illuminance can be reduced.

  In the discharge lamp lighting device according to the present invention, when the power supplied to the high-pressure discharge lamp is less than a predetermined power value, the control means increases a rate of increase in the power supplied to the high-pressure discharge lamp to a predetermined constant value. The drive current is controlled by the DC power supply circuit so that In the present invention, the drive current is controlled so that the rate of increase in the power supplied to the high-pressure discharge lamp becomes a predetermined constant value. For this reason, the lamp accompanying a rapid rise in the lamp voltage at the start of the lamp A rapid increase in power can be suppressed, and melting of the tip of the lamp electrode and deterioration of illuminance can be reduced.

  In the discharge lamp lighting device according to the present invention, when the power supplied to the high-pressure discharge lamp is less than a predetermined power value, the control means drops the drive current supplied by the DC power supply circuit over time. In the present invention, the drive current supplied by the DC power supply circuit is controlled to decrease with the passage of time, so that a rapid increase in lamp power accompanying a rapid increase in lamp voltage at the start of the lamp is suppressed. It is possible to reduce melting of the tip of the lamp electrode and deterioration of illuminance.

  In the discharge lamp lighting device according to the present invention, when the power supplied to the high-pressure discharge lamp reaches a predetermined power value, the control means maintains the direct current so as to maintain the power at the predetermined power value. The power supply circuit controls the drive current. In the present invention, when the power supplied to the high-pressure discharge lamp reaches a predetermined power value, the drive current is controlled in the DC power supply circuit so as to maintain the power at the predetermined power value. After the power supplied to the high pressure discharge lamp rises to a predetermined power value, the power supplied to the high pressure discharge lamp can be maintained at the predetermined power value.

  In the discharge lamp lighting device according to the present invention, the DC power supply circuit supplies a drive current to the high-pressure discharge lamp with a secondary mirror. In the present invention, the DC power supply circuit controls the drive current supplied to the high-pressure discharge lamp with the secondary mirror. For this reason, the lamp voltage suddenly increased with the temperature rise due to the return light reflected by the secondary mirror. Even in this case, a rapid increase in lamp power can be suppressed, and melting of the lamp electrode tip and illuminance deterioration can be reduced.

  The projector according to the present invention includes a high pressure discharge lamp or a high pressure discharge lamp with a sub mirror, the discharge lamp lighting device, a spatial light modulator, and an optical means for guiding light from the high pressure discharge lamp to the spatial light modulator. And projection means for projecting an image drawn on the spatial light modulator onto a screen. In the present invention, the discharge lamp lighting device controls the drive current so that the rate of increase in the power supplied to the high pressure discharge lamp is not more than a predetermined value, so that the electrode tip of the high pressure discharge lamp melts. As a result, the discharge arc becomes large, and the occurrence of illuminance deterioration can be reduced.

It is a block diagram of the discharge lamp lighting device which concerns on Embodiment 1 of this invention. It is a figure which shows the return light by the submirror of a lamp with a submirror. It is a figure which shows the lamp voltage and lamp current of a lamp with a submirror. It is a figure which shows the lamp electric power of a lamp with a submirror. It is a figure which shows the lamp voltage and lamp current which concern on Embodiment 1 of this invention. It is a figure which shows the lamp | ramp electric power which concerns on Embodiment 1 of this invention. It is an optical system block diagram of the projector which concerns on Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a discharge lamp lighting device according to Embodiment 1 of the present invention. The discharge lamp lighting device of FIG. 1 includes a down chopper 11, an inverter 12, an igniter 13, a DC / DC converter 14, and a control circuit 15 that is a control means, and a lamp 20 is connected to the output terminal of the igniter 13. ing. The down chopper 11 corresponds to the DC power supply circuit of the present invention, and adjusts the DC voltage input to supply power to the lamp 20 which is a high pressure discharge lamp. In this example, the input voltage is reduced by the chopper process. In order to supply power to the lamp 20, current control is performed by an operation described later. The output current of the down chopper 11 is output to the inverter 12. Resistors R1 and R2 are connected in parallel to the output terminal of the down chopper 11, and the potential at the connection point between the resistors R1 and R2 is supplied to the control circuit 15 as the output voltage of the down chopper 11. Further, a resistor R3, which is a current detection circuit, is connected in series to the negative potential side of the down chopper 11, and a current flowing through the resistor R3 is detected as a drive current (hereinafter also referred to as a lamp current), and the control circuit 15 To be supplied.

  The inverter 12 is composed of, for example, four switching elements connected in a full bridge, and by switching alternately, the input DC voltage is converted into an AC voltage and output to the igniter 13. The igniter 13 is composed of, for example, an igniter transformer and its drive circuit, and generates a high voltage and applies it to the lamp 20 when the lamp is started. Further, resistors R4 and R5 are connected in parallel to the output terminal of the igniter 13, and a voltage detection circuit that detects the potential at the connection point between the resistors R4 and R5 as the lamp voltage of the lamp 20 is detected and detected. The lamp voltage is supplied to the control circuit 15. The DC / DC converter 14 generates a drive voltage for the control circuit 15, drops the input voltage, and supplies it to the control circuit 15. The control circuit 15 is composed of, for example, a microprocessor and controls the down chopper 11, the inverter 12, and the igniter 13, respectively. The control circuit 15 obtains lamp power supplied to the lamp 20 from the detected lamp voltage and lamp current, and controls the output current of the down chopper 11 by the operation described later. The control circuit 15 appropriately controls the output frequency of the inverter 12 and controls the igniter 13 at the time of starting to generate a high voltage. The control circuit 15 is connected to an external control IF 15a for taking in a control signal from the outside and a variable resistor VR for adjusting the frequency. The lamp 20 is, for example, a reflection-type light source device, and an arc tube 21 is fixed to the central portion of the reflection mirror 22 with heat-resistant cement.

  Next, the operation of the discharge lamp lighting device of FIG. 1 will be described. The down chopper 11 drops the input DC voltage by the chopper process, and the output current is output to the inverter 12. The inverter 12 converts the input direct current into an alternating current having a predetermined frequency and outputs the alternating current to the igniter 13. When the lamp is started, the igniter 13 generates a high voltage and applies it to the lamp 20. When the lamp 20 is turned on, the output voltage of the inverter 12 is applied to the lamp 20 as it is and the lighting state is continued. At this time, the control circuit 15 takes in the lamp voltage and lamp current of the lamp 20 and controls the down chopper 11 so that the power of the lamp 20 does not rapidly increase by an operation described later. Next, the relationship between the rapid increase in lamp power at the time of starting the lamp and the lamp voltage will be described.

  First, the relationship between the lamp voltage at the time of starting the lamp and the lamp pressure will be described. The lamp pressure P is proportional to the temperature T and the number of molecules n inside the arc tube as expressed by the equation of state PV = nRT. V is the volume inside the arc tube, and R is a gas constant. The temperature T inside the arc tube rises due to light emission. Further, the mercury in the arc tube evaporates due to the temperature rise and the number of molecules n increases. In the case of a lamp with a secondary mirror, the temperature rises due to the return light reflected by its own light emission, and the temperature T further rises. As a result, the lamp pressure P increases rapidly. The lamp voltage depends on the lamp pressure, and the lamp voltage increases rapidly as the lamp pressure increases. Next, a rapid rise in lamp voltage and lamp power of such a lamp with a secondary mirror will be described.

  FIG. 2 is a diagram showing the return light from the secondary mirror of the secondary mirror lamp. In FIG. 2, a lamp 20 is, for example, a high-pressure mercury lamp. Inside the arc tube 21, mercury, a rare gas, a small amount of halogen, and the like are sealed, and an electrode 24 is sealed. The secondary mirror 23 functions to reflect the light emitted from the electrode 24, pass through the inside of the arc tube 21, and return the light to the reflective mirror 22 (not shown in FIG. 2). The arc tube 21 is not limited to a high-pressure mercury lamp, but may be another lamp such as a metal halide lamp or a xenon lamp. As shown in FIG. 2, in the lamp 20, the light emitted by the discharge between the electrodes 24 is reflected by the secondary mirror, and the reflected return light passes through the arc tube 21. At this time, since heat is generated in the arc tube 21 by the return light, the temperature in the arc tube 21 further rises.

  FIG. 3 is a diagram showing the lamp voltage and lamp current of the lamp with the secondary mirror, and FIG. 4 is a diagram showing the lamp power of the lamp with the secondary mirror. In FIG. 3, after starting the lamp, the lamp voltage rises as the lamp pressure increases and stabilizes at the rated voltage. The lamp voltage of the lamp with the secondary mirror is rapidly increased with respect to the lamp without the secondary mirror. Here, in the conventional discharge lamp lighting device, the lamp current after starting the lamp is supplied with a constant driving current until the lamp power reaches a rated power (for example, 135 W). Constant power control is performed on the current so as to be constant. Therefore, the lamp power determined by the lamp voltage and the lamp current rapidly increases with the rapid increase of the lamp voltage until the lamp power reaches the rated power as shown in FIG. Such a rapid rise in lamp power causes a sudden increase in the collision load of electrons applied to the electrode tip in the arc tube. As a result, the electrode tip melts and the electrode tip melts, resulting in a large discharge arc and deterioration in illuminance. Cause.

  In order to reduce the melting of the electrode tip and the deterioration of illuminance due to the rapid increase in lamp power as described above, it is necessary to control the lamp current so as to suppress the rapid increase in lamp power. Details of the lamp current control operation will be described with reference to FIGS.

  FIG. 5 is a diagram showing a lamp voltage and a lamp current according to the first embodiment of the present invention, and FIG. 6 is a diagram showing a lamp power according to the first embodiment of the present invention. After starting the lamp 20 by the igniter 13, the control circuit 15 calculates the lamp power by multiplying the lamp voltage and the lamp current detected by the voltage detection circuit and the current detection circuit, and the lamp power is a predetermined power. When the value is less than the value (rated power value, for example, 135 W), the increase value of the voltage per unit time, which is the rate of increase of the lamp voltage, is obtained, The lamp current value that is less than or equal to the value is obtained. The control circuit 15 causes the down chopper 11 to control the current so as to supply the lamp 20 with the lamp current having the obtained current value. When the lamp power becomes a predetermined power value due to the increase of the lamp voltage, the control circuit 15 causes the down chopper 11 to control the lamp current so that the power supplied to the lamp 20 becomes constant. As shown in FIG. 6, by causing the down chopper 11 to control the lamp current in this way, as shown in FIG. 6, with respect to the increase in lamp power in the conventional discharge lamp lighting device that performs constant current control for supplying a constant current after starting the lamp Since the lamp power of the discharge lamp lighting device according to the present invention is controlled by the current control so that the rate of increase of the lamp power is a predetermined value or less, the rapid increase of the lamp power is suppressed.

  As described above, in the first embodiment, after the lamp 20 is started, the lamp pressure rapidly increases as the temperature rises due to lamp emission and the temperature rises due to the return light from the secondary mirror. When the voltage suddenly increases, the control circuit 15 obtains the electric power supplied to the lamp 20, and controls the lamp current so that the lamp power does not increase suddenly, thereby suppressing the rapid increase in lamp electric power. It is possible to reduce the load caused by the collision of electrons applied to the tip of the electrode of the lamp 20 due to a rapid rise in lamp power, and to reduce the dissolution of the lamp electrode. Moreover, by melting the electrode tip, the discharge arc becomes large, and the occurrence of illuminance deterioration can be reduced.

  In the above description, the case where the increase rate of the lamp power is set to a predetermined value or less has been described. However, the present invention is not limited to this, and any control that suppresses a rapid increase in lamp power as the lamp voltage increases can be used. For example, lamp current control may be used in which the increase rate of the lamp power is set to a predetermined constant value.

  Further, for example, after starting the lamp 20 by the igniter 13, the control circuit 15 controls the lamp current supplied by the down chopper 11 to decrease with time when the lamp power is less than a predetermined power value. May be.

  Further, for example, a lamp current table corresponding to the voltage value and the increase rate of the lamp voltage may be created in advance, and the lamp current may be controlled by referring to the table, or the lamp current may be changed discretely. May be.

  In this embodiment, the case where the drive current is supplied to the lamp with the secondary mirror has been described. However, the present invention is not limited to this, and a lamp without the secondary mirror may be used.

Embodiment 2. FIG.
FIG. 7 is an optical system configuration diagram of the projector according to Embodiment 2 of the present invention. The projector according to the present embodiment is obtained by incorporating the discharge lamp lighting device according to the first embodiment into an illumination optical system. The discharge lamp lighting device 10 in FIG. 7 corresponds to the discharge lamp lighting device 10 in FIG.

  This projector includes an illumination optical system 100, dichroic mirrors 210 and 212, reflection mirrors 220, 222, and 224, an incident side lens 230, a relay lens 232, three field lenses 240, 242, and 244, and a space. Three liquid crystal panels 250, 252, and 254 as light modulators, polarizing plates 251, 253, 255, 256, 257, and 258 disposed on the emission side and the incident side of each liquid crystal panel, and a cross dichroic prism 260, respectively. And a projection lens 270.

  The illumination optical system 100 includes a lamp 20 that emits a substantially parallel light bundle, an illumination device 120, a reflection mirror 150, and a condenser lens 160. The lamp 20 includes an arc tube 21 with a secondary mirror and a reflecting mirror 22 as a radiation source that emits a radial light beam. The light emitted from the lamp 20 is made uniform by the illuminating device 120 and then enters the condenser lens 160 via the reflection mirror 150. The condenser lens 160 causes the uniform light emitted from the illumination device 120 to enter the panel surfaces of the liquid crystal panels 250, 252, and 254.

Further, the two dichroic mirrors 210 and 212 include a color light separation optical system 214 that separates light emitted from the illumination optical system 100 into three color lights of red (R), green (G), and blue (B). It is composed. The first dichroic mirror 210 transmits the red light component of the light emitted from the illumination optical system 100 and reflects the blue light component and the green light component.
The red light transmitted through the first dichroic mirror 210 is reflected by the reflection mirror 220 and passes through the field lens 240 and reaches the liquid crystal panel 250 for red light. This field lens 240 has a function of condensing each passing partial beam so that it becomes a light beam parallel to the principal ray (central axis) of each partial beam. The field lenses 242 and 244 provided in front of other liquid crystal panels operate in the same manner.

  Of the blue light and green light reflected by the first dichroic mirror 210, the green light is reflected by the second dichroic mirror 212 and passes through the field lens 242 to reach the green light liquid crystal panel 252. On the other hand, the blue light passes through the second dichroic mirror 212 and passes through the incident side lens 230, the relay lens system including the relay lens 232 and the reflection mirrors 222 and 224. The blue light that has passed through the relay lens system further passes through the field lens 244 and reaches the liquid crystal panel 254 for blue light.

  The three liquid crystal panels 250, 252, and 254 have a function as a light modulation device that converts each color light incident thereon into light for forming an image according to a given image signal and emits the light. The liquid crystal panels 250, 252, and 254 have polarizing plates 256, 257, and 258 on the light incident side, and the liquid crystal panels 250, 252, and 254 have polarizing plates 251, 253, and 255 on the light emission side, respectively. The polarization direction of each color light is adjusted by them. The light that has passed through these liquid crystal panels 250, 252, and 254 then enters the cross dichroic prism 260.

  The cross dichroic prism 260 has a function as a color light combining optical system that combines the three color lights emitted from the three liquid crystal panels 250, 252, and 254. In the cross dichroic prism 260, a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an approximately X shape at the interface of four right-angle prisms. These dielectric multilayer films combine the three color lights to form a combined light for projecting a color image. The combined light generated by the cross dichroic prism 260 enters the projection lens 270 and is projected onto the projection screen 300 from there. As a result, the images displayed on the liquid crystal panels 250, 252 and 254 are projected on the projection screen 300.

  As described above, the second embodiment includes the discharge lamp lighting device of the first embodiment and applies the lamp 20 lit by the discharge lamp lighting device to the illumination optical system. A rapid increase in lamp power can be suppressed, melting of the tip of the lamp electrode can be reduced, deterioration of lamp illuminance can be reduced, and the brightness of the image projected on the projection screen 300 can be maintained.

  10 discharge lamp lighting device, 11 down chopper, 12 inverter, 13 igniter, 14 converter, 15 control circuit, 15a IF, 20 lamp, 21 arc tube, 22 reflecting mirror, 23 secondary mirror, 24 electrode, R1 resistance, R2 resistance, R3 resistance, R4 resistance, R5 resistance, 100 illumination optical system, 120 illumination device, 150 reflection mirror, 160 condenser lens, 210 dichroic mirror, 212 dichroic mirror, 214 color light separation optical system, 220 reflection mirror, 222 reflection mirror, 224 reflection Mirror, 230 incident side lens, 232 relay lens, 240 field lens, 242 field lens, 244 field lens, 250 liquid crystal panel, 251 polarizing plate, 253 polarizing plate, 255 polarizing plate, 256 polarizing plate, 57 polarizing plate, 258 polarizing plate, 252 a liquid crystal panel, 254 a liquid crystal panel, 260 cross dichroic prism, 270 a projection lens, 300 a projection screen.

Claims (6)

A DC power supply circuit that inputs a DC voltage and performs current control for supplying predetermined power to the high-pressure discharge lamp;
An inverter that converts an output current of the DC voltage power supply circuit into an AC current of a predetermined frequency and supplies a driving current to the high-pressure discharge lamp;
An igniter that is connected to the output side of the inverter and generates a high voltage at the start to start the high-pressure discharge lamp;
A voltage detection circuit for detecting a voltage corresponding to the lamp voltage of the high-pressure discharge lamp;
A current detection circuit for detecting a current corresponding to a driving current of the high-pressure discharge lamp;
Control means for controlling the DC voltage power supply circuit, the inverter and the igniter,
The control means starts the high-pressure discharge lamp by the igniter and then uses the voltage corresponding to the lamp voltage detected by the voltage detection circuit and the drive current detected by the current detection circuit to generate the high-pressure discharge lamp. When the power supplied to is determined to be less than a predetermined power value,
A discharge lamp lighting device that causes the DC power supply circuit to control the drive current so that an increase rate of the electric power is a predetermined value or less. When the power supplied to the high pressure discharge lamp is less than a predetermined power value, the control means,
2. The discharge lamp lighting device according to claim 1, wherein the driving current is controlled by the DC power supply circuit so that an increase rate of electric power supplied to the high pressure discharge lamp becomes a predetermined constant value. When the power supplied to the high pressure discharge lamp is less than a predetermined power value, the control means,
The discharge lamp lighting device according to claim 1, wherein the driving current supplied by the DC power supply circuit is decreased with the passage of time. When the power supplied to the high-pressure discharge lamp reaches a predetermined power value, the control means,
The discharge lamp lighting device according to any one of claims 1 to 3, wherein the driving current is controlled by the DC power supply circuit so as to maintain the electric power at the predetermined electric power value.   The discharge lamp lighting device according to any one of claims 1 to 4, wherein the DC power supply circuit supplies a drive current to the high-pressure discharge lamp with a sub mirror. A high pressure discharge lamp or a high pressure discharge lamp with a secondary mirror;
The discharge lamp lighting device according to any one of claims 1 to 5,
A spatial light modulator;
Optical means for guiding light from the high pressure discharge lamp to the spatial light modulator;
A projector comprising: projection means for projecting an image drawn on the spatial light modulator onto a screen.

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