JP2009104864A - Discharge lamp, light source device, projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp having a longer lifetime as compared with a conventional one by further suppressing devitrification and blackening of an arc tube which is caused by using it for a long time, a light source device, and a projection type display device. <P>SOLUTION: This discharge lamp has the arc tube 111 made of silica glass, a pair of tungsten electrodes 112 disposed face to face in the arc tube 111, an a metal oxide film 116 coating at least a part of the inner surface 111a of the arc tube 111 and having a melting point lower than the melting point of the arc tube 111 and higher than the temperature of the inner surface 111a of the arc tube 111 during normal usage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge lamp, a light source device, and a projection display device.

  When the discharge lamp is lit for a long time, the arc wall causes the tube wall of the arc tube to become hot, and microcracks are generated. Such micro cracks cause devitrification, which not only causes a decrease in illuminance of the arc tube, but can also cause damage to the arc tube.

Also, if the arc length is shortened by shortening the distance between the electrodes in order to obtain high-intensity light emission close to a point light source, the lamp voltage (arc voltage) at the time of starting decreases and the lamp current increases, thereby increasing the temperature between the electrodes. Will rise excessively. Then, the evaporating action of tungsten (W) constituting the electrode and impurities contained in the tungsten is promoted, so that the electrode is consumed or deformed in a short period of time and the light emitting part is prematurely blackened. Also, the heat applied during the manufacture of the discharge lamp causes the metal foil connected to the electrode and the molybdenum (Mo) constituting the lead wire to evaporate and combine with bromine (Br), oxygen (O ₂ ), etc. in the arc tube. The Mo compound adhered to the inner surface of the arc tube, causing devitrification and blackening.

Therefore, in order to suppress blackening and devitrification of the arc tube, a porous material of metal oxide is arranged in the gap formed at the base of the electrode, and always near the discharge part of the sealed body (including when it is extinguished) A method of incorporating a substance that induces blackening or devitrification into a porous material by keeping the temperature lower (Patent Document 1), or a method of defining the amount of Mo compound that is incorporated as an impurity in the arc tube during production ( Patent Document 2) and the like have been proposed.
JP 2003-151502 A JP 2003-173759 A

  However, in Patent Document 1, since the metal oxide is relatively stable, it is difficult to incorporate all the substances that induce blackening or devitrification into the porous material. In Patent Document 2, it is possible to suppress the generation of the Mo compound during the manufacturing process, but it is difficult to suppress the devitrification and blackening of the arc tube due to the tungsten compound generated during lighting. The devitrification of the arc tube is caused by a microcrack generated with a tungsten compound adhering to the tube wall as a nucleus. Therefore, it is desired to suppress the generation of microcracks as long as possible. Furthermore, at present, there is no effective countermeasure against microcracks that have occurred.

  The present invention has been made in view of the above-described problems of the prior art, further suppresses devitrification and blackening of the arc tube due to long-time use, and has a longer life than conventional discharge lamps and light sources. It aims at providing a device and a projection type display device.

  In order to solve the above problems, the discharge lamp of the present invention covers an arc tube made of quartz glass, a pair of electrodes disposed opposite to each other in the arc tube, and at least a part of the inner surface of the arc tube. And a metal oxide film having a melting point lower than the melting point and higher than the inner surface temperature of the arc tube during normal use.

According to the present invention, a metal oxide film having a predetermined melting point is formed on the inner surface of the arc tube, and by raising the output (arc voltage) of the discharge lamp to raise the temperature inside the tube than during normal use, the metal The oxide film can be in a molten state. Then, the melted metal oxide film is permeated into the microcracks formed on the tube wall to repair the cracks, and the devitrification of the arc tube is recovered.
Thereby, since the progress and increase of microcracks can be suppressed, it is possible to prevent the arc tube from becoming clouded and to prevent the luminance of the discharge lamp from being lowered. Thereby, it is possible to further suppress devitrification (decrease in devitrification area) as compared with the conventional case, and it is also possible to prevent damage to the discharge lamp due to microcracks and the like. Therefore, a discharge lamp having a longer life can be obtained.
Furthermore, since the tungsten compound generated at the time of lighting is prevented from adhering to the inner surface of the arc tube by the metal oxide film, blackening of the arc tube and generation of microcracks can be suppressed.

Moreover, it is preferable that melting | fusing point of a metal oxide film is 1500 degrees C or less.
According to the present invention, the metal oxide film has a melting point lower than the melting point (1500 ° C.) of the quartz glass constituting the arc tube. In this case, only the metal oxide film can be melted without altering the quartz glass. As a result, the arc tube can be stably repaired.

Moreover, it is preferable that melting | fusing point of a metal oxide film is 1200 degreeC or more.
According to the present invention, since the metal oxide film has a melting point higher than the inner surface temperature (1200 ° C.) of the arc tube during normal lighting, the arc tube can be repaired by melting the metal oxide film during lighting. The metal oxide film that can be stably formed does not melt on the inner surface of the arc tube during normal use, but melts when the arc voltage is intentionally increased, and maintains the film shape during melting.

The metal oxide film is preferably a single layer film or a multilayer film containing at least one element selected from the group consisting of gallium (Ga), germanium (Ge), niobium (Nb), and cerium (Ce). .
According to the present invention, by providing a metal oxide film made of a metal having a melting point lower than that of quartz glass, the metal oxide film can be surely melted without altering the quartz glass due to temperature rise in the arc tube due to lighting (arc heat). And can penetrate quickly into the microcracks to fill the gaps. In this way, the life of the discharge lamp can be extended by providing the arc tube repair function.

Moreover, it is preferable that the metal oxide film is provided so as to cover a part vertically above the arc generating portion.
According to the present invention, devitrification of the arc tube can be prevented regardless of the mounting state of the discharge lamp.

The metal oxide film preferably has a thickness of 10 μm or less.
According to the present invention, devitrification caused by microcracks can be suppressed without impairing the transparency of the arc tube by the metal oxide film.

In order to solve the above problems, a light source device of the present invention includes the above-described discharge lamp, a monitor device that measures the illuminance maintenance rate of the discharge lamp, and a control device that adjusts the arc voltage based on the measurement result of the monitor device; , Provided.
According to the present invention, the illuminance maintenance factor is measured by monitoring the illuminance of the discharge lamp over time by the monitor device, and the control device increases the arc voltage to the discharge lamp based on the measurement result. Then, the metal oxide film in the discharge lamp is melted, and the melted metal oxide penetrates into the microcracks and the devitrification area is reduced. Thereby, devitrification of the discharge lamp is suppressed, and desired luminance can be ensured for a long period of time.

The controller preferably increases the arc voltage when the illuminance maintenance rate of the arc tube is below a specified value.
According to the present invention, the change in the illuminance maintenance factor of the arc tube is constantly monitored, and when the illuminance maintenance factor falls below a specified value due to the occurrence of microcracks, the discharge voltage is increased to melt the metal oxide film in the arc tube, Reduces devitrification. As a result, a light source device capable of ensuring desired luminance for a long period can be obtained.

A projection display device according to the present invention includes the above-described light source device.
ADVANTAGE OF THE INVENTION According to this invention, the reliable projection type display apparatus using the long life which a light source device has can be obtained. In addition, since the occurrence of devitrification and blackening of the discharge lamp and the accompanying luminance decrease can be suppressed, a projection display device with high display quality can be obtained.

The projection type display device of the present invention is modulated by the above-described discharge lamp, polarization separation means for polarization-separating light emitted from the discharge lamp, a light modulation device for modulating the polarization-separated light, and the light modulation device. Projection means for projecting light, a monitor device for measuring the illuminance maintenance rate of the discharge lamp, and a control device for adjusting the arc voltage of the discharge lamp based on the measurement result of the monitor device and controlling the light modulation device It is characterized by that.
According to the present invention, the arc tube can be automatically repaired at a suitable time, and devitrification and blackening can be stably suppressed. Thereby, since it becomes possible to always maintain desired illuminance, a high-intensity discharge lamp can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

[Light Source Device of First Embodiment]
FIG. 1 is a cross-sectional view showing a schematic configuration of a light source device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a schematic configuration of the discharge lamp.
1 and 2, the light source device 100 includes a discharge lamp 101, a reflector 102 (main reflecting mirror), and a sub-reflecting mirror 103, and is housed in a lamp housing (not shown). Then, the light beam emitted from the discharge lamp 101 is emitted as convergent light by the reflector 102 with its emission direction aligned in front of the apparatus (x direction).

The discharge lamp 101 includes an arc tube 111 made of quartz glass (main composition is SiO ₂ ), and a pair of tungsten electrodes 112 and 112 disposed in the arc tube 111. The arc tube 111 is made of quartz glass (main composition is SiO ₂ ), and includes a light emitting portion 111A having a central portion swelled in a spherical shape, and a sealing portion 111B extending on both sides of the light emitting portion 111A. A substantially spherical discharge space K is formed inside the light emitting portion 111A.

  In the present embodiment, a metal oxide film 116 is formed on the inner surface 111a of the light emitting unit 111A. The metal oxide film 116 is made of a material having a melting point lower than the melting point of the arc tube 111 (softening temperature of quartz glass) and higher than the temperature of the inner surface 111a of the light emitting part 111A during normal use (lighting). For example, it is composed of a single layer film or a multilayer film containing at least one element selected from the group consisting of gallium (Ga), germanium (Ge), niobium (Nb), and cerium (Ce). The metal oxide film 116 has a predetermined thickness and is formed so as to cover substantially the entire inner surface 111a of the light emitting portion 111A. In the present embodiment, the transparency of the arc tube 111 is ensured by setting the thickness to 10 μm or less.

  In the discharge space K, a pair of tungsten electrodes 112 and 112 and an enclosure are enclosed. Examples of the inclusion include mercury, rare gas, and halogen compounds. The rare gas is used to promote light emission, and is not particularly limited, but commonly used argon, xenon, and the like can be used. Furthermore, the halogen compound can use any halogen of chlorine, bromine and iodine, and it is particularly preferable to use bromine.

  The tungsten electrode 112 includes an electrode shaft 112a, a heat radiation coil 112b, and a discharge end C1 (C2). The heat radiating coil 112b is manufactured by winding a core wire, which is a conducting wire, around the electrode shaft 112a, and the discharge end portions C1 and C2 are spherical shapes having a large heat capacity by thermally melting one end portion of the electrode shaft 112a with a laser. Or it is a dome shape. The electrode shaft 112a and the heat radiation coil 112b wound around the electrode shaft 112a may be fused and integrated, or may be fixed by the occupying force of the heat radiation coil 112b. Such tungsten electrodes 112 and 112 are disposed in the discharge space K with the discharge end portions C1 and C2 facing each other and at a predetermined interval.

  Note that high purity tungsten is used for the tungsten electrode 112. Thereby, the amount of potassium and impurities contained in the tungsten electrode 112 released into the discharge space K during lighting can be suppressed.

  A metal foil 113 made of molybdenum that is electrically connected to the tungsten electrode 112 is inserted into each sealing portion 111B of the arc tube 111 and sealed with a glass material or the like. The metal foil 113 is further connected with a lead wire 114 made of nickel as an electrode lead wire, and the lead wire 114 extends to the outside of the arc tube 111. In addition, a base 118 for electrically conducting is fixed to the end of each sealing portion 111B at the end opposite to the discharge ends C1 and C2 of the tungsten electrodes 112 and 112. The lead wire 114 is attached to the base 118.

  In the discharge lamp 101 described above, when a voltage is applied to the lead wire 114 extending outward from the sealing portion 111B, a discharge occurs between the tungsten electrodes 112 as shown in FIG. 2, and the light emitting portion 111A emits light.

The reflector 102 is an integrally molded product made of glass that includes an insertion portion 121 through which the sealing portion 111B of the discharge lamp 101 is inserted and an elliptical curved reflection portion 122 that extends from the insertion portion 121. An insertion hole 123 is formed at the center of the insertion part 121, and the arc tube sealing part 111 </ b> B is disposed at the center of the insertion hole 123. The reflecting portion 122 is configured by depositing a metal thin film on the elliptically curved reflecting surface 122A, and is a cold mirror that reflects visible light and transmits infrared rays. The focal position of the reflecting surface 122A and the center position of the pair of tungsten electrodes 112 (arc-shaped light emitting portions) are preferably configured to substantially coincide with each other.
The shape of the reflector 102 is not limited to this, and can be changed.

  The sub-reflecting mirror 103 is disposed to face the reflector 102 with the reflecting surface 133A facing the light emitting unit 111A. The sub-reflecting mirror 103 is an integrally formed glass product including an insertion portion 131 into which the sealing portion 111B of the discharge lamp 101 is inserted and an elliptical curved reflection portion 132 that extends from the insertion portion 131. The reflecting member is smaller than the reflector 102. An insertion hole 133 is formed at the center of the insertion portion 131, and the arc tube sealing portion 111 </ b> B is disposed at the center of the insertion hole 133. The reflecting portion 132 is configured by depositing a metal thin film on a concave curved reflecting surface 132A that follows the spherical surface of the discharge space K, and is a cold mirror like the reflector 102. It is preferable that the two focal positions of the reflecting surface 133A and the positions of the discharge ends C1 and C2 of the pair of tungsten electrodes 112 are substantially coincident with each other.

  Note that the reflecting surface 122A of the reflector 102 and the reflecting surface 133A of the sub-reflecting mirror 103 can be formed of not only an elliptical curved surface but also a spherical surface.

  When the discharge lamp 101 is fixed to the reflector 102 and the sub-reflecting mirror 103, the insertion hole 123 and the insertion hole 133 are filled with an inorganic adhesive, and the pair of the discharge lamp 101 is placed in the reflector 102 and the sub-reflecting mirror 103. The sealing portion 111B is fixed so as to be horizontal.

  When the light source device 100 is driven, light generated by the discharge between the tungsten electrodes 112 of the discharge lamp 101 is emitted in various directions within the discharge space K. A part of the light beam emitted from the light emitting unit 111A passes through the light emitting tube 111 and enters the sub-reflecting mirror 103, is reflected by the reflecting surface 133A, and is returned to the light emitting unit 111A again. Part of this return light travels toward the reflector 102, and the light incident on the reflector 102 is reflected by the reflecting surface 122A of the reflecting portion 122 and emitted in a predetermined direction. When the discharge lamp 101 is turned on, the light beam emitted from the light emitting unit 111A is emitted in a predetermined direction as substantially collimated light by the reflector 102 and the sub-reflecting mirror 103.

When the discharge lamp 101 as described above is turned on, the heat of the arc generated between the tungsten electrodes 112 (about 3500 ° C.) evaporates tungsten (W) constituting the tungsten electrode 112 and impurities contained in the tungsten. Tungsten oxide (WO) is generated by combining with the air (O ₂ ) remaining in the discharge space K. If this tungsten oxide adheres to the inner surface 111a of the arc tube 111, there is a possibility that it becomes a nucleus of microcrack generation. In this embodiment, the metal oxide film 116 is formed on the entire inner surface 111a of the light emitting portion 111A of the arc tube 111. Thus, the tungsten oxide is prevented from adhering to the inner surface 111a of the arc tube 111. Therefore, the occurrence of microcracks can be effectively suppressed, and devitrification of the discharge lamp 101 due to white turbidity of the arc tube 111 can be prevented. Further, since the tungsten oxide is prevented from adhering to the inner surface 111a of the arc tube 111, blackening of the arc tube 111 can be prevented.

The metal oxide film 116 can prevent the arc tube 111 (quartz glass) from evaporating due to arc heat. As a result, it is possible to suppress the separation and generation of oxygen (O ₂ ) from the arc tube 111 in the discharge space K. Thereby, since the production | generation of tungsten oxide is suppressed, it can prevent that the tungsten electrode 112 is consumed in a short time, and can prolong the lifetime of the tungsten electrode 112.

  At the time of lighting, the temperature of the inner surface 111a (tube wall) of the arc tube 111 rises due to arc heat, and the temperature reaches about 1200 ° C. In particular, a portion of the inner surface 111a located vertically above the arc generating portion 115 is hotter than the other portions, so that microcracks are likely to occur. Since the progress and increase of microcracks cause devitrification of the discharge lamp 101, it is necessary to prevent the generation area of microcracks from increasing even during long-time lighting.

Specifically, in the present embodiment, when the generation area of the microcracks exceeds a certain value, the arc voltage to the discharge lamp 101 is increased to temporarily increase the arc heat. Then, the temperature of the inner surface 111a of the light emitting unit 111A temporarily rises and the metal oxide film 116 is melted.
At this time, since the melting point of the metal oxide film 116 is lower than the softening temperature (1500 ° C.) of quartz glass, the arc tube 111 itself is not altered. Further, since the metal oxide film 116 is melted while maintaining the film shape on the inner surface 111a of the light emitting portion 111A, the inner surface 111a of the arc tube 111 is not exposed.

  The molten metal oxide film 116 permeates into the microcracks formed in the arc tube 111 by a capillary phenomenon, and is cured by a subsequent temperature drop. The temperature can be lowered by restoring the arc voltage of the discharge lamp 101. Moreover, since the cured metal oxide film 116 also has translucency, the transparency of the arc tube 111 is ensured. The temporary increase in voltage during lighting is repeated under the above-described conditions, and each time the arc tube 111 is repaired by melting the metal oxide film 116, the intended purpose is achieved.

  As described above, the progress and increase (devitrification area) of the microcracks are suppressed, and the luminance reduction of the discharge lamp 101 due to the white turbidity of the arc tube 111 can be prevented for a long time. In addition, since it is possible to prevent the arc tube 111 from being damaged and the tungsten electrode 112 from being consumed due to microcracks, the life of the discharge lamp 101 can be extended.

  Note that the metal oxide film 116 may be formed in a band shape on the inner surface 111a of the light emitting portion 111A so as to cover at least a part vertically above the arc generating portion 115. By adopting such a configuration, it is possible to prevent devitrification (microcracks) and blackening of the arc tube 111 regardless of the use state of the discharge lamp 101.

[Light Source Device of Second Embodiment]
FIG. 3 is a block diagram for explaining the internal configuration of the light source device according to the second embodiment, and FIG. 4 is a flowchart for explaining the operation of the light source device.
In FIG. 3, a light source device 150 is connected to the discharge lamp 101, a monitor device 152 that measures the illuminance maintenance ratio thereof, and a light output that adjusts the arc voltage based on the measurement result of the monitor device 152. A control device 154 and a power source 156 of the discharge lamp 101 connected to the light output control device 154 are provided.

  The monitor device 152 includes an illuminance processing circuit 160 including an illuminance meter 157, a comparator 158, and a memory 159. The illuminance meter 157 measures the illuminance of the discharge lamp 101. A prescribed value (initial illuminance of the discharge lamp 101 or desired illuminance) is stored in the memory, and a comparator 158 connected thereto stores the measured value obtained from the illuminometer 157 during lighting and the memory 159 in advance. Comparison with the specified value is performed over time, and the illuminance maintenance rate of the discharge lamp 101 is measured. The light output control device 154 is connected to the power source 156 of the discharge lamp 101 and adjusts the arc voltage of the discharge lamp 101 based on the measurement result by the illuminance processing circuit 160.

  Specifically, as shown in FIGS. 3 and 4, the illuminance of the discharge lamp 101 being lit is measured with an illuminometer 157 (step S1), and a prescribed value (for example, stored in the memory 159 in the comparator 158) The initial illuminance of the discharge lamp 101 is set to 100%) to calculate the illuminance maintenance ratio (step S2). When it is determined by the monitor device 152 that the illuminance maintenance rate of the discharge lamp 101 has become 70% or less of the specified value (step S3), the arc voltage of the discharge lamp 101 is increased temporarily or for a certain period by the light output control device 154. (Step S4). Along with this, the temperature of the inner surface 111a of the arc tube 111 rapidly rises, the metal oxide film 116 is melted, and the melted metal oxide penetrates into the microcracks. In this way, the microcracks are filled, and white turbidity of the arc tube 111 is suppressed.

FIG. 5 is a graph showing the results of life tests on the products A and B of the present invention and the comparative product, wherein the vertical axis represents the devitrification area (mm ² ) and the horizontal axis represents the lighting time (H). As the products A and B of the present invention, a discharge lamp (light source device) having a metal oxide film made of niobium oxide (Nb ₂ O ₅ ) is used on the inner surface of the arc tube, and the inner surface of the light emitting part is a metal oxide film as a comparative product. A discharge lamp (light source device) provided with an arc tube not covered with a light source was used. Inventive products A and B and comparative products were each subjected to a life test at an arc voltage of 200 W, and the average values were graphed. In this test, the product A of the present invention continued normal lighting for a long time, and the product B of the present invention temporarily increased the arc voltage when the illuminance maintenance rate fell below a specified value.

As shown in FIG. 5, it can be seen that the comparative product starts devitrification before the lighting time reaches 1000 hours, and the devitrification area rapidly increases with time. On the other hand, in the products A and B of the present invention, devitrification did not occur for a while even after the lighting time exceeded 2000 hours, and devitrification finally occurred just before the lighting time reached 3000 hours. It can be seen that the rate of increase in the devitrification area is extremely small compared to the comparative product. When the initial illuminance of the discharge lamp was set to 100% and the maintenance ratio of the illuminance fell below 70%, the arc voltage for the product B of the present invention was increased to 230 W and lit for several hours. Then, the devitrification area rapidly decreased. Moreover, it turns out that the increase rate of a devitrification area is also suppressed very small for about 1000 hours after that. As a result, the product B of the present invention could confirm long-term durability of 5000 hours.
Further, when the discharge lamp 101 was disassembled and SEM observation inside the arc tube was carried out, it was confirmed that niobium oxide constituting the metal oxide film 116 penetrated into the microcracks.

  As a result, it has been found that the effect of suppressing the devitrification of the arc tube 111 in the long term can be sufficiently obtained by covering the inner surface of the arc tube 111 with the metal oxide film 116. Furthermore, it has become clear that the devitrification area can be rapidly reduced by temporarily increasing the arc voltage to melt the metal oxide film 116. In this way, the defect repair function of the arc tube 111 could be confirmed.

[projector]
FIG. 6 shows a schematic configuration of a projector 500 which is an example of a projection display device according to the present invention, and FIG. 7 is a block diagram showing a schematic configuration of the projector 500.
The projector 500 according to the present embodiment includes an illumination device 300 including a discharge lamp, a monitor device 172, and a light output control device 174. Since these are the same as those described in the above embodiment, a duplicate description is omitted. .

The illuminating device 300 includes the discharge lamp of the above-described embodiment, and includes red light (hereinafter referred to as “R light”), green light (hereinafter referred to as “G light”), and blue light (hereinafter referred to as “R light”). Light including "B light").
The integrator 504 makes the illuminance distribution of the light from the illumination device 300 uniform. The light whose illuminance distribution is made uniform is converted into polarized light having a specific vibration direction, for example, S-polarized light by the polarization conversion element 505. The light converted into S-polarized light is incident on an R-light transmitting dichroic mirror 506R constituting a color separation optical system (polarization separation means).

  The R light transmitting dichroic mirror 506R transmits R light and reflects G light and B light. The R light transmitted through the R light transmitting dichroic mirror 506R is incident on the reflection mirror 507. The reflection mirror 507 bends the optical path of the R light by 90 degrees. The R light whose optical path is bent is incident on a light modulation device 510R that modulates the R light according to an image signal. The light modulation device 510R is a transmissive liquid crystal light valve that modulates R light according to an image signal. Note that even if the light passes through the dichroic mirror, the polarization direction of the light does not change, so the R light incident on the light modulation device 510R remains as S-polarized light.

The light modulation device 510R includes a λ / 2 phase difference plate 523R, a glass plate 524R, a first polarizing plate 521R, a liquid crystal panel 520R, and a second polarizing plate 522R. The λ / 2 phase difference plate 523R and the first polarizing plate 521R are disposed in contact with a light-transmitting glass plate 524R that does not change the polarization direction. By contacting the glass plate 524R, the problem that the first polarizing plate 521R and the λ / 2 phase difference plate 523R are distorted by heat generation can be avoided.
In FIG. 6, the second polarizing plate 522 </ b> R is provided independently, but may be disposed in contact with the exit surface of the liquid crystal panel 520 </ b> R or the entrance surface of the cross dichroic prism 512.

  The S-polarized light incident on the light modulation device 510R is converted into P-polarized light by the λ / 2 phase difference plate 523R. The R light converted into the P-polarized light passes through the glass plate 524R and the first polarizing plate 521R as it is, and enters the liquid crystal panel 520R. The P-polarized light incident on the liquid crystal panel 520R is converted into S-polarized light by modulation according to the image signal. The R light converted into S-polarized light by the modulation of the liquid crystal panel 520R is emitted from the second polarizing plate 522R. In this way, the R light modulated by the light modulation device 510R enters the cross dichroic prism 512, which is a color synthesis optical system.

  The G light and B light reflected by the R light transmitting dichroic mirror 506R have their optical paths bent 90 degrees. The G light and the B light whose optical paths are bent enter the B light transmitting dichroic mirror 506G. The B light transmitting dichroic mirror 506G reflects G light and transmits B light. The G light reflected by the B light transmitting dichroic mirror 506G is incident on a light modulation device 510G that modulates the G light according to an image signal. The light modulation device 510G is a transmissive liquid crystal light valve that modulates G light according to an image signal. The light modulation device 510G includes a liquid crystal panel 520G, a first polarizing plate 521G, and a second polarizing plate 522G.

  The G light incident on the light modulation device 510G is converted into S-polarized light. The S-polarized light incident on the light modulation device 510G passes through the first polarizing plate 521G as it is and enters the liquid crystal panel 520G. The S-polarized light incident on the liquid crystal panel 520G is converted into P-polarized light by modulation according to the image signal. The G light converted into P-polarized light by the modulation of the liquid crystal panel 520G is emitted from the second polarizing plate 522G. In this way, the G light modulated by the light modulation device 510G enters the cross dichroic prism 512 which is a color synthesis optical system.

  The B light transmitted through the B light transmitting dichroic mirror 506G is incident on the light modulation device 510B that modulates the B light according to the image signal via the two relay lenses 508 and the two reflection mirrors 507. . The light modulation device 510B is a transmissive liquid crystal light valve that modulates B light according to an image signal.

  The reason why the B light passes through the relay lens 508 is that the optical path length of the B light is longer than the optical path lengths of the R light and the G light. By using the relay lens 508, the B light transmitted through the B light transmitting dichroic mirror 506G can be directly guided to the light modulation device 510B. The light modulation device 510B includes a λ / 2 phase difference plate 523B, a glass plate 524B, a first polarizing plate 521B, a liquid crystal panel 520B, and a second polarizing plate 522B. Note that the configuration of the light modulation device 510B is the same as that of the light modulation device 510R described above, and a detailed description thereof will be omitted.

  The B light incident on the light modulation device 510B is converted into S-polarized light. The S-polarized light incident on the light modulation device 510B is converted into P-polarized light by the λ / 2 phase difference plate 523B. The B light converted into P-polarized light passes through the glass plate 524B and the first polarizing plate 521B as it is, and enters the liquid crystal panel 520B. The P-polarized light incident on the liquid crystal panel 520B is converted into S-polarized light by modulation according to the image signal. The B light converted into S-polarized light by the modulation of the liquid crystal panel 520B is emitted from the second polarizing plate 522B. The B light modulated by the light modulation device 510B enters the cross dichroic prism 512, which is a color synthesis optical system. As described above, the R light transmitting dichroic mirror 506R and the B light transmitting dichroic mirror 506G constituting the color separation optical system separate light supplied from the illumination device 300 into R light, G light, and B light.

  The cross dichroic prism 512, which is a color synthesis optical system, is configured by arranging two dichroic films 512a and 512b orthogonally in an X shape. The dichroic film 512a reflects B light and transmits R light and G light. The dichroic film 512b reflects R light and transmits B light and G light. As described above, the cross dichroic prism 512 combines the R light, G light, and B light modulated by the light modulation device 510R, the light modulation device 510G, and the light modulation device 510B, respectively. The projection lens 514 projects the light combined by the cross dichroic prism 512 onto the screen 516. Thereby, a full color image can be obtained on the screen 516.

  As described above, the light incident on the cross dichroic prism 512 from the light modulation device 510R and the light modulation device 510B is set to be S-polarized light. Further, the light incident on the cross dichroic prism 512 from the light modulation device 510G is set to be P-polarized light. In this way, by changing the polarization direction of the light incident on the cross dichroic prism 512, the light emitted from the light modulators for the respective color lights in the cross dichroic prism 512 can be effectively combined. The dichroic films 512a and 512b are usually excellent in the reflection characteristics of S-polarized light. For this reason, R light and B light reflected by the dichroic films 512a and 512b are S-polarized light, and G light transmitted through the dichroic films 512a and 512b is P-polarized light.

  The light modulation devices 510R, 510G, and 510B are connected to a light modulation device control unit 181 that controls them, and the light modulation device control unit 181 controls the drive control of each of the light modulation devices 510R, 510G, and 510B. is doing.

In the present embodiment, a monitor device 172 that monitors the illuminance maintenance rate of the illumination device 300 is provided in the vicinity of the reflection mirror 507 and the light modulation device 510R. The R light whose optical path is bent by 90 degrees by the reflection mirror 507 is incident on the light modulation device 510R, but a part of the R light is reflected by the surface of the glass plate 524R and enters the monitor device 172 as leakage light R1.
Note that the light output control device 174 of this embodiment is a control unit provided separately from the projector control device 182 having the light modulation device control unit 181 that controls the light modulation devices 510R, 510G, and 510B.

FIG. 7 is a block diagram for explaining the internal configuration of the projector.
In FIG. 7, the monitor device 172 measures the illuminance of the leaked light R1 with the illuminance meter 175 and compares it with the initial illuminance stored in the memory 178 in the comparator 177 of the illuminance processing circuit 176 over time. Calculate the maintenance rate.
The light output control device 174 adjusts the arc voltage of the lighting device 300 according to the illuminance maintenance ratio calculated by the illuminance processing circuit 176. In other words, the light output control device 174 causes the arc during normal lighting when the monitor device 172 produces a measurement result in which the initial illuminance of the illumination device 300 is 100% and the illuminance maintenance rate of the illumination device 300 is less than 70%. It is set to increase by a predetermined value from the voltage. The power source 179 supplies power to the lighting device 300 based on the control signal sent from the light output control device 174.
Then, in lighting device 300, the metal oxide film in the discharge lamp melts due to the increase in arc voltage, and the occurrence of microcracks is repaired. In this way, the illuminance maintenance rate of the lighting device 300 is properly restored.

  The projector 500 includes the illumination device 300, the monitor device 172, and the light output control device 174 of the above-described embodiment. The illumination device 300 is provided with a defect repair function by the monitor device 172 and the light output control device 174, and can irradiate high-intensity illumination light for a long period of time. For this reason, a high-quality bright projection image of the projector 500 can be stably obtained. The arrangement position of the monitor device 172 can be changed as appropriate without being limited to the above-described place. Further, as the light modulation device, a reflective liquid crystal panel or DMD (manufactured by Texas Instruments) can also be used. Further, the configuration of the projector is not limited to the three-plate configuration, and can be appropriately changed as long as it is a single-plate configuration or a configuration that does not depart from the gist of the present invention.

  The light output control device 174 may be provided in the projector control device 182 together with the light modulation device control unit 181. As a result, a repairing operation linked with the operation of the projector is possible. For example, a repair confirmation screen for the discharge lamp can be presented to the user, or a repair operation can be performed when the projector is started up, down, or driven.

  The preferred embodiments according to the present invention have been described above with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to such examples, and the above embodiments may be combined. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  For example, in the above-described embodiment, the discharge lamp and the monitor device for measuring the illuminance of the discharge lamp and the control device are provided, respectively. However, the projector illumination device is provided with a monitor function and a light output control function. A discharge lamp, that is, the light source device 150 of the second embodiment may be provided. In this case, it is preferable to provide means for splitting the light to the illuminometer without hindering the light from entering the integrator 504. Since such a light source device has a configuration in which a discharge lamp, a monitor device, and a control device are integrated, it can be easily incorporated into a projector.

1 is an overall configuration diagram of a light source device according to a first embodiment. The schematic block diagram of the discharge lamp of 1st Embodiment. The block diagram for demonstrating the internal structure of the light source device of 2nd Embodiment. The flowchart figure for demonstrating the effect | action of the light source device of 2nd Embodiment. The graph which shows the result of the life test in this invention product and a comparison product. The schematic block diagram of the projector which is an example of a projection type display apparatus. The block diagram for demonstrating the internal structure of a projector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Light source device, 101 ... Discharge lamp, K ... Discharge space, 102 ... Reflector, 103 ... Sub-reflector, 111 ... Arc tube, 112 ... Tungsten electrode, 112a ... Electrode axis, 112b ... Heat dissipation coil, 113 ... Metal foil , 114 ... lead wire, 115 ... arc generating part, 111A ... light emitting part, 111B ... sealing part, 116 ... metal oxide film, 121 ... insertion part, 122 ... reflection part, 122A ... reflection surface, 123 ... insertion hole, 131 DESCRIPTION OF SYMBOLS ... Insertion part, 132 ... Reflection part, 132A ... Reflection surface, 133 ... Insertion hole, 133A ... Reflection surface, 150 ... Light source device, 152 ... Monitor device, 154 ... Light output control device, 156 ... Power source, 157 ... Illuminance meter, 158: Comparator, 159 ... Memory, 160 ... Illuminance processing circuit, 172 ... Monitor device, 174 ... Light output control device, 175 ... Illuminance meter, 176 ... Illuminance processing circuit 177 ... comparator, 178 ... memory, 179 ... power supply 181 ... optical modulator controller, 182 ... projector control unit, 300 ... illumination device 500 ... projector (projection display device), R1 ... leakage light

Claims (10)

An arc tube made of quartz glass;
A pair of electrodes disposed opposite to each other in the arc tube;
A metal oxide film covering at least a part of the inner surface of the arc tube and having a melting point lower than the melting point of the arc tube and higher than the temperature of the inner surface of the arc tube during normal use. To discharge lamp.   The discharge lamp according to claim 1, wherein the melting point of the metal oxide film is 1500 ° C. or less.   The discharge lamp according to claim 1 or 2, wherein the melting point of the metal oxide film is 1200 ° C or higher.   The metal oxide film is a single layer film or a multilayer film containing at least one element selected from the group consisting of gallium (Ga), germanium (Ge), niobium (Nb), and cerium (Ce). The discharge lamp according to any one of claims 1 to 3.   The discharge lamp according to any one of claims 1 to 4, wherein the metal oxide film is provided so as to cover a part vertically above the arc generating portion.   6. The discharge lamp according to claim 1, wherein the metal oxide film has a thickness of 10 μm or less. The discharge lamp according to any one of claims 1 to 6,
A monitoring device for monitoring the illuminance maintenance rate of the discharge lamp;
And a control device that adjusts an arc voltage based on a measurement result of the monitoring device.   The light source device according to claim 7, wherein the control device increases the arc voltage when an illuminance maintenance factor of the arc tube falls below a specified value.   A projection display device comprising the light source device according to claim 7. The discharge lamp according to any one of claims 1 to 6,
Polarized light separating means for polarizing and separating the light emitted from the discharge lamp;
A light modulation device for modulating the polarization separated light;
Projection means for projecting light modulated by the light modulation device;
A monitoring device for monitoring the illuminance maintenance rate of the discharge lamp;
A projection display device comprising: a control device that adjusts an arc voltage of the discharge lamp based on a measurement result of the monitor device and controls the light modulation device.

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