JP3665160B2 - Discharge lamp, lamp device, lighting device, and liquid crystal projector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp, a lamp device, a lighting device, and a liquid crystal projector.
[0002]
[Prior art]
Recently, as described in, for example, Japanese Patent Laid-Open No. 8-87066, short arc type discharge lamps that take advantage of characteristics such as point light sources, high brightness, high efficiency, and high color rendering properties, particularly metal halide lamps are liquid crystal projectors, etc. Widely used as a light source.
[0003]
As a light source used in this way, a metal halide (compound of metal and halogen), mercury, and a rare gas are sealed in a quartz glass bulb, and an anode and a cathode facing each other in the discharge space are placed in the bulb. There is a discharge lamp that is provided, and this discharge lamp is mounted at the center of a hemispherical reflecting mirror, and a DC voltage is applied to the anode and the cathode to cause discharge between both electrodes.
[0004]
In the case of this DC drive type, the anode side becomes high temperature, but the cathode side does not generate much heat. The reason why the heat on the cathode side is low is that it is located on the open side of the reflecting mirror. On the other hand, metal halides evaporate when turned on, but solidify when turned off. In this case, since the temperature on the cathode side is lower, the metal halide tends to accumulate at the base of the cathode. As a result, since halogen does not evaporate at the beginning of the next lighting, discharge is generated at a certain ratio between the metal halide solidified and accumulated at the base of the cathode and the anode. This is called root discharge. Due to this root discharge, a part of the inner surface of the bulb wall near the root of the cathode may partially rise in temperature, and the bulb may crack due to internal strain.
[0005]
For this reason, metal halide is accumulated on the cathode side when the lamp is turned off. As a result, in order to prevent root discharge from occurring at the beginning of lighting, the entire outer periphery of the bulb side is covered with a heat insulating film. The temperature on the cathode side is not lowered so much.
[0006]
[Problems to be solved by the invention]
However, when the entire outer periphery on the cathode side is covered with a heat insulating film as described above, when the light is lit with the optical axis substantially horizontal (hereinafter referred to as horizontal lighting), the temperature becomes higher due to convection. In particular, in order to increase luminous efficiency, the distance between the anode and the cathode is increased and the cathode projection length is shortened due to the matching with the discharge lamp with increased tube wall load (wattage per surface area inside the bulb) and the optical system. In the case of a discharge lamp, the upper part on the cathode side of the bulb becomes hot. The inside of the heat insulating film is particularly hot. In such a case, devitrification grows. This devitrification is a phenomenon in which the structure of the quartz glass, which is the material of the bulb, and the metal atom of the metal halide are interchanged to change the structure. The appearance becomes whitish and the properties become brittle. As a result, there is a problem that the luminous flux maintenance factor is lowered and the life is shortened.
[0007]
Accordingly, the present invention provides a discharge lamp that satisfies the conditions for preventing the occurrence of bulb cracks due to root discharge and can prevent devitrification due to temperature rise, and a lamp device, a lighting device, and a liquid crystal projector using the discharge lamp. The purpose is to do.
[0008]
[Means for Solving the Problems]
A discharge lamp according to claim 1 is a bulb formed of quartz glass; a discharge medium containing at least a metal halide enclosed in the bulb; a pair of electric introduction bodies provided at both ends of the bulb; An anode and a cathode that are electrically connected to the electrical introduction body and are horizontally opposed to each other in a discharge space in the bulb; a base between the tip of the anode and the vicinity of the base of the cathode at the beginning of lighting In order to prevent discharge, a heat insulating film is provided in a range of a substantially half lower periphery on the cathode side of the bulb to keep a part of the entire outer circumference on the cathode side of the bulb.
[0009]
Therefore, the cathode side of the bulb has a lower temperature than the anode side, but is kept warm by the heat retaining film, and thus is kept above a predetermined temperature. Therefore, the action of collecting metal halides biased toward the base of the cathode when extinguished is suppressed. Thereby, generation | occurrence | production of a root discharge is prevented at the time of lighting initial stage. In addition, when the lamp is lit, the upper part of the bulb is higher than the lower part due to convection, but the insulation layer on the cathode side of the bulb is limited by the insulation film, so that the horizontal illumination with the insulation film facing downwards is limited. In the case of the usage form, the heat radiation action at the upper part of the valve is promoted. Furthermore, in the case of horizontal lighting with the heat insulation film facing downward, it is possible to effectively prevent the temperature of the lower half of the bulb on the cathode side from dropping too much and promote the heat dissipation action on the upper half. The
[0010]
In this case, mercury, rare gas or the like can be enclosed in the bulb together with the discharge medium. The heat insulating film may be a film that does not release heat. For example, a film made of alumina oxide or a reflective film having a high reflectance on the inner surface of the bulb side is applied.
[0012]
Lamp device according to claim 2 includes a discharge lamp of claim 1 Symbol placement; comprising a; a reflecting mirror for reflecting light in a predetermined direction from the discharge lamp.
[0013]
Lighting apparatus according to the third aspect, a discharge lamp of claim 1 Symbol placement; comprising a; a lighting circuit for providing current to the lamp power is turned stably to the pair of electrodes of the discharge lamp.
[0014]
The liquid crystal projector according to claim 4, wherein the lighting device according to claim 3 is supported so that the optical axis is substantially horizontal with the heat insulating film facing downward; a liquid crystal display panel driven by the liquid crystal driving device; An optical system that projects light radiated from a discharge lamp included in the lighting device through the liquid crystal display panel onto the screen; and accommodates the lighting device, the liquid crystal drive device, the liquid crystal display panel, and the optical system, and transmits through the liquid crystal display panel A housing in which an opening for projecting the light to the screen is formed.
[0015]
Therefore, the lamp device according to claim 2, the liquid crystal projector of the lighting device and claim 4, wherein the third aspect, since comprises a discharge lamp of claim 1 Symbol placement, the occurrence of root discharge lighting initial time Is prevented. Further, in the case of the horizontal lighting usage mode, the heat radiation action at the upper part of the bulb is promoted.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal side view of a discharge lamp and a lamp apparatus in a horizontal lighting usage mode, and FIG. 2 is a horizontal sectional view as seen from the bottom side in FIG.
[0017]
In the figure, 1 is a discharge lamp. The bulb 2 of the discharge lamp 1 is made of quartz glass, and sealing portions 3 and 4 are formed at both ends. The bulb 2 is filled with a discharge medium such as a metal halide, mercury, or a rare gas, and the metal foils 5 and 6 are sealed in the sealing portions 3 and 4. One end of one of the metal foils 5 is connected to a lead terminal 8 that is supported by a base 7 and connected to a lighting circuit (not shown), and an anode 9 is connected to the other end. One end of the other metal foil 6 is connected to a lead terminal 11 which is an electricity introducing portion connected to the lighting circuit through a lead wire 10 and the other end is connected to a cathode 12. A heat insulating film 13 is attached to a part of the entire outer periphery of the bulb 2 on the cathode 12 side. The range where the heat insulating film 13 is affixed is a minimum necessary range to prevent a root discharge between the tip of the anode 9 and the vicinity of the root of the cathode 12 at the beginning of lighting, and in this example, is approximately a half circumference. .
[0018]
In such a discharge lamp 1, the lamp device 16 is formed by inserting the base 7 into the center of the hemispherical reflecting mirror 14 and filling cement 15 or the like between the outer periphery of the base 7 and the inner surface of the reflecting mirror 14. Is done.
[0019]
In such a configuration, when a DC voltage is applied to the lead terminal 8, a discharge occurs between the anode 9 and the cathode 12, and the halogen of the metal halide evaporates. At this time, the bulb 2 emits light by the discharge during the evaporation of the halogen. In this case, the temperature of the bulb 2 on the cathode 12 side is lower than that on the anode 9 side, but the cathode 12 side is kept at a predetermined temperature or more because it is kept warm by the heat insulating film 13. Therefore, the action of collecting metal halides biased toward the base of the cathode 12 when the lamp is turned off is suppressed.
[0020]
At the beginning of the next lighting, the metal halide is in a solid state, but since the action of the metal halide being biased and accumulated at the base of the cathode 12 at the previous extinction is suppressed, generation of root discharge is prevented. . As a result, a state in which the inner wall of the bulb 2 on the cathode 12 side is locally hot is avoided, so that the bulb 2 can be prevented from cracking.
[0021]
Further, the temperature of the bulb 2 becomes higher than the lower portion due to convection at the time of lighting, but in the usage mode of horizontal lighting, the cathode 12 of the bulb 2 is supported by supporting the lamp device 16 so that the heat insulating film 13 is on the lower side. The heat of the upper part on the side can be radiated from the upper tube wall where the heat insulating film 13 does not exist. Therefore, devitrification due to high temperature can be prevented. In this case, approximately half of the entire circumference of the bulb 2 on the cathode 12 side is kept warm by the heat retaining film 13, so that in the case of horizontal lighting, the temperature of the lower half circumference of the bulb 2 on the cathode 12 side is excessively lowered. It can prevent effectively and can accelerate | stimulate the thermal radiation effect | action in an upper half periphery.
[0022]
The effect of the heat insulating film 13 and the effect of limiting the heat insulating region of the heat insulating film 13 have been described above. To prove this, a conventional discharge lamp in which a heat insulating film is formed on the entire circumference of the cathode side of the bulb A comparative experiment was conducted with the discharge lamp 1 of the present invention in which the heat insulating film 13 was formed on substantially the outer circumference of the bulb 2 on the cathode 12 side. The result will be described.
[0023]
First, with respect to the luminous efficiency, the conventional configuration and the present configuration have substantially the same results. It was confirmed that root discharge does not occur in the proposed configuration. In the case of the conventional configuration, since the heat retaining property is higher than that of the present configuration, the root discharge does not occur. The difference between the conventional configuration and the present configuration is about illuminance and devitrification. That is, in the conventional configuration, the heat retaining property by the heat retaining film is high, and the temperature increases accordingly, so that 4 out of 6 devitrified as a result after lighting for 100 hours. On the other hand, the results of the present configuration were not devitrified in total (six). It was also confirmed that the illuminance was increased by 5% from that of the conventional configuration. This is because the range through which light passes is wider than when the heat insulating film 13 is formed on the entire circumference of the discharge lamp 1 on the cathode 12 side.
[0024]
Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those described in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is also omitted. FIG. 3 is a longitudinal side view showing a reduced outline of the internal structure of the liquid crystal projector including the lighting device.
[0025]
In the figure, 17 is a lighting device. The lighting device 17 is formed by the above-described discharge lamp 1 and a lighting circuit 18 that supplies stabilized electric power to the discharge lamp 1. The lighting circuit 18 is connected to the lead terminal 8 and the lead wire 10 (both see FIG. 1) of the discharge lamp 1.
[0026]
The liquid crystal projector 19 is provided with, for example, a color liquid crystal display panel 20 and a light projection lens 21 as an optical system in front of the projection of the discharge lamp 1, and an image displayed on the liquid crystal display panel 20 is displayed on the screen 22. To project. The lighting device 17 including the lighting circuit 18, the liquid crystal display panel 20, and the liquid crystal driving device 23 that drives the liquid crystal display panel 20 are housed in a housing 24. The housing 24 includes an opening 25 for allowing an image projected through the light projecting lens 21 to pass therethrough.
[0027]
As described above, since the lamp device 16 and the lighting device 17 constituting the liquid crystal projector 19 use the discharge lamp 1 that keeps a part of the entire outer periphery on the cathode 12 side of the bulb 2 with the heat insulating film 13. As described above, root discharge and devitrification can be prevented.
[0028]
【The invention's effect】
According to the first aspect of the present invention, a part of the entire outer periphery on the cathode side of the bulb is kept warm within a minimum necessary range to prevent the root discharge between the tip of the anode and the vicinity of the cathode root at the beginning of lighting. Since the temperature of the cathode side of the bulb is lower than that of the anode side, a predetermined temperature can be maintained by the heat insulation film. Accordingly, it is possible to suppress the action of the metal halide being concentrated on the base of the cathode when the light is extinguished, thereby preventing the occurrence of root discharge and the occurrence of cracks in the bulb due to the root discharge at the beginning of lighting. In addition, when the lamp is lit, the upper part of the bulb is higher than the lower part due to convection. However, the insulation layer on the cathode side of the bulb is limited by the insulation film, so the insulation film is turned on horizontally. In the case of the use form, it is possible to promote the heat radiation action at the upper part of the valve and prevent devitrification due to the temperature rise. In addition, since approximately half of the entire outer circumference on the cathode side of the bulb is kept warm by the heat insulation film, in the case of horizontal lighting with the heat insulation film facing downward, the lower part of the bulb on the cathode side It is possible to effectively prevent the temperature of the half circumference from dropping excessively and to promote the heat radiation action in the upper half circumference.
[0030]
The liquid crystal projector according to the lamp apparatus of claim 2, the lighting device according to claim 3 and claim 4, wherein, since it comprises a discharge lamp of claim 1 Symbol mounting, toward the heat insulating film on the lower side In the case of the horizontal lighting in the state, the occurrence of cracks and devitrification of the bulb due to the root discharge of the discharge lamp can be prevented.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of the present invention, and is a longitudinal side view of a discharge lamp and a lamp device in a usage state of horizontal lighting. FIG. 2 is a horizontal sectional view seen from the bottom side in FIG. 3 shows a second embodiment of the present invention, and is a vertical side view showing a reduced outline of the internal structure of a liquid crystal projector including a lighting device.
1: Discharge lamp 2: Bulb 8: Electric introduction body 9: Anode 11: Electric introduction body 12: Cathode 13: Thermal insulation film 14: Reflecting mirror 16: Lamp device 17: Lighting device 18: Lighting circuit 20: Liquid crystal display panel 21: Optical system 22: Screen 23: Liquid crystal driving device 24: Housing 25: Opening

Claims (4)

A bulb formed of quartz glass;
A discharge medium comprising at least a metal halide enclosed in a bulb;
A pair of electrical introduction bodies provided at both ends of the valve;
An anode and a cathode which are electrically connected to these electrical introduction bodies and which are horizontally opposed to each other in the discharge space in the bulb;
In order to prevent a root discharge between the tip of the anode and the vicinity of the base of the cathode at the beginning of lighting, it is provided in a range of a substantially half circumference on the cathode side of the bulb and in the entire outer circumference on the cathode side of the bulb A heat insulating film for keeping a part of the heat
A discharge lamp comprising: A discharge lamp of claim 1 Symbol placement;
A reflector that reflects light from the discharge lamp in a predetermined direction;
A lamp device comprising: A discharge lamp of claim 1 Symbol placement;
A lighting circuit comprising: a lighting circuit that stably supplies power by supplying power to an anode and a cathode of a discharge lamp. The lighting device according to claim 3 , wherein the lighting device is supported so that the optical axis is substantially horizontal with the heat insulating film directed downward.
A liquid crystal display panel driven by a liquid crystal driving device;
An optical system that projects light emitted from a discharge lamp included in the lighting device and passed through the liquid crystal display panel onto the screen;
A liquid crystal projector comprising: a lighting device, a liquid crystal driving device, a liquid crystal display panel, and an optical system; and a housing having an opening for projecting light transmitted through the liquid crystal display panel onto the screen. .

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