JP4474689B2 - Discharge lamp, discharge device, lighting device and liquid crystal projector using functionally gradient material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp using a functionally gradient material as a part of an electrode, and a discharge device, a lighting device, and a liquid crystal projector using the discharge lamp as a light source.
[0002]
[Prior art]
Conventionally, such a lamp is known from EP-A-0338637. Known lamps have the advantage that due to the high operating pressure of at least 200 bar, the radiation contains significantly more continuous radiation in the visible part of the space. This lamp has a long life, high luminous flux maintenance, and little change in its color point during the life.
[0003]
The lamp known from said EP patent application publication has an elongated, narrow cylindrical arc tube and consumes less power of 50 W or less. However, the luminous flux of this lamp is too small for the purpose of image projection such as a liquid crystal projector.
[0004]
Further, a discharge lamp as disclosed in JP-A-6-52830 is known. In this lamp, as shown in the example of Japanese Patent Laid-Open No. 6-52830, a pair of electrodes are arranged oppositely in an elliptical arc tube at the center of a discharge vessel made of quartz glass, a light emitting metal such as mercury, a discharge gas, etc. Is enclosed. A cylindrical closure tube is connected to both ends of the arc tube, and the ends of the electrode rod and the external lead rod are welded to both ends of a molybdenum foil having a thickness of several tens of μm. In this case, a closed tube made of quartz glass is welded to the central portion of the molybdenum foil. In this electrode structure, since the thermal expansion coefficient of the molybdenum foil or the electrode rod at the time of lighting is greatly different from that of quartz glass, the seal part may be peeled off due to expansion and may be damaged.
[0005]
In addition, when sealed with molybdenum foil, the end of the molybdenum foil to which the external lead rod is welded is in contact with air. There were also problems such as causing poor electrical continuity.
[0006]
In particular, in the case of a discharge lamp that consumes 100 W or more of electric power at a high operating pressure of 200 bar as shown in JP-A-6-52830, the tendency increases, and in JP-A-6-52830, In the case of a discharge lamp that consumes power of 150 W or more that was not used, the discharge lamp was broken when it was initially lit with a probability of nearly 100%, and was not established as a discharge lamp.
[0007]
Nevertheless, there is a strong demand for discharge lamps with very high brightness, stable high luminous efficiency, stable color point and long life, and, for example, a larger luminous flux than LCD projection TV lamps.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to obtain a lamp having very high brightness, stable luminous efficiency, stable color point and long life, and a large luminous flux.
[0009]
[Means for Solving the Problems]
The present invention achieves the above object by making the discharge lamp at the beginning as follows. As described in claim 1, an arc tube made of a non-conductive material having a region surrounding a discharge space, and a pair of electrodes are disposed oppositely in the arc tube to form a discharge path and discharge gas is formed. A cylindrical tube that is sealed and formed at the end of the arc tube mixes the non-conductive material and the conductive material, which are the same material as the arc tube, in the lengthwise direction or in a stepwise different ratio. In the closed discharge lamp, the gap between the closed body made of the functionally gradient material and the electrode rod is a closed body made of the functionally gradient material with the discharge space side made nonconductive and the other end side made conductive. There is a cermet made of a conductive material made of the same material as the electrode rod and a non-conductive material made of the same material as the arc tube. That is, when the arc tube is made of quartz glass, the closed tube at the end of the arc tube is made from a cermet containing a non-conductive substance of silica, a conductive substance such as molybdenum, and a non-conductive substance of silica of the same material as the arc tube. The discharge lamp is closed with a closing body made of a functionally gradient material. In the closed body formed of such a functionally gradient material, the non-conductive substance of silica is rich at the end on the discharge space side, and the proportion of the conductive substance such as molybdenum continuously increases toward the other end. Also, it will increase step by step. Therefore, the discharge space side of the closing body for sealing is non-conductive and has a characteristic that the coefficient of thermal expansion is substantially equal to the coefficient of thermal expansion of quartz glass that is the material of the arc tube.
[0010]
Such a functionally gradient material has a strong heat shock and mechanical strength because it does not have a boundary surface where the composition of its constituent components changes greatly. Also, when inserting the electrode rod of the closing body into the axial hole formed in the closing body of the functionally gradient material rich in the non-conductive substance up to the conductive portion to establish electrical continuity with the outside In addition, a cermet is formed in the gap between the electrode rod and the closed functional body made of the functionally graded material from a conductive material of the same material as the electrode rod and a non-conductive material made of the same material as the arc tube. It serves to alleviate the difference in the thermal expansion coefficient between the rod and the electrode rod, and eliminates the thermal shock between the electrode rod and the block made of functionally graded material, thereby improving reliability. It becomes a lamp.
[0011]
Therefore, it is possible to solve the problem that the seal part is peeled off or damaged due to the expansion of the seal part accompanying the temperature rise when the discharge lamp is turned on. In particular, even in the case of a discharge lamp that is not disclosed in Japanese Patent Laid-Open No. 6-52830 and consumes 150 W or more of electric power at a high operating pressure of 200 bar, it is possible to provide a lamp that does not break with a probability of almost 100%.
[0012]
A discharge device according to an eighth aspect includes a discharge lamp using the functionally gradient material according to the first aspect and a reflecting mirror that reflects light from the discharge lamp in a predetermined direction. Therefore, the light from the discharge lamp using the functionally gradient material is reflected by the reflecting mirror and guided in a predetermined direction. In this case, if the structure is such that one end of the discharge lamp using the functionally graded material is held in the reflecting mirror, the heat of the discharge lamp is efficiently radiated to the outside through the reflecting mirror.
[0013]
Lighting device according to claim 9 comprises a lighting circuit to the pair of electrodes of the discharge lamp and discharge collector according to claim 8 by feeding the lamp power is turned stably.
[0014]
A liquid crystal projector according to a tenth aspect of the present invention is a liquid crystal display panel that controls light from a discharge lamp using the lighting device according to the ninth aspect, a liquid crystal display panel driven by the liquid crystal driving device, and a functionally gradient material provided in the lighting device. And an optical system and a lighting device, a liquid crystal driving device, a liquid crystal display panel, and an optical system for projecting light onto the screen, and a housing having an opening for projecting light transmitted through the liquid crystal display panel to the screen.
[0015]
Therefore, since the lighting device according to claim 9 and the liquid crystal projector according to claim 10 include the discharge lamp using the functionally gradient material according to claim 1, the same functions and effects as those claims can be obtained. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment will be described with reference to FIG. The arc tube 11 of the discharge vessel made of quartz glass has a spherical shape or an elliptical spherical shape, and an electrode 20 made of tungsten is disposed opposite to the inside thereof. In addition, argon gas is sealed as a discharge gas at a predetermined pressure, and mercury and mercury bromide are sealed as light emitting metals. The blocking tube 12 is connected to both ends of the arc tube 11, and the end of the blocking tube 12 is closed by a closing body 50 made of a functionally gradient material. The functionally gradient material used here is made by sintering the same material of silica as the discharge vessel and the conductive material molybdenum, and the mixing ratio is varied continuously or stepwise in the length direction to emit light. The tube side is made non-conductive and one is made conductive. As an example, the end surface 51 on the non-conductive side of the closure 50 is made of almost 100% silica, and the conductive side end 52 on the other end side is made of a volume ratio composition of 25% molybdenum and 75% silica. Although it is a cermet, the composition ratio is not necessarily restricted to this.
[0017]
The closing body 50 is fitted into the closing tube 12 so that the end face 51 made of a non-conductive substance faces the arc tube 11, and the end face 51 is welded to the closing body 12 made of quartz glass. At this time, as shown in claim 3, the closed tube 12 and the closed body 50 are welded over the entire circumference of the closed tube 12 in the direction from the end surface 51 made of a nonconductive material to the end surface 52 made of a conductive material. Yes. When the welded length is 2 mm or less, the seal portion may be too short, causing problems such as leakage.
[0018]
The electrode rod 21 of the electrode 20 is made of a tungsten rod and is inserted into a hole 53 formed in the closing body 50. The hole 53 is a counterbore hole in the axial direction from the end surface 51 made of a non-conductive substance of the closing body 50 to the conductive portion toward the end face made of the conductive material of the closing body 50. In a state where the electrode rod 21 is inserted into the hole 53, a non-conductive substance made of the same material as the arc tube 11 between the closing body 50 and the electrode rod 21, in this case silica, and the same material as the electrode rod 21 In this case, a cermet 54 made of tungsten is present. The cermet 54 has a function of securely fixing the electrode rod 21 and the closing member 50 at the same time as reducing the heat shock between the electrode rod 21 and the closing member 50.
[0019]
However, when the volume ratio of the conductive material is 15% or less, the cermet has low conductivity, and there is a possibility that the electrical connection between the electrode rod 21 and the closing body 50 is lost. In addition, when the volume ratio of the conductive material is 50% or more, there is a possibility that the conductive material does not sinter well with the non-conductive material. It becomes a factor that adheres to the inner wall of the arc tube 11 and obstructs light. Therefore, the composition of the cermet is ideally such that the conductive material described in claim 2 is in the range of 15% to 50% by volume.
[0020]
A counterbore hole 55 is also formed in the end surface 52 on the conductive material side of the closing body 50 in the axial direction, and an external lead wire 56 for electrically connecting the outside and the electrode 20 is inserted into the hole 55. The external lead wire 56 is made of tungsten or molybdenum, and, as shown in claim 4, a cermet 57 is interposed, and the external lead wire 56 is securely fixed to the closing body 50 and is electrically connected.
[0021]
Further, since the closed body 50 on the side of the external lead wire 56 from the portion welded to the external lead wire 56 and the arc tube 11 is in contact with the air, it is heated to a high temperature of 350 ° C. or higher at the time of lighting similarly to the molybdenum foil seal. As a result, the conductive material existing on the surface of the closing body 50 and the external lead wire 56 may be oxidized, resulting in poor electrical continuity. Therefore, as shown in claim 5, a film 58 of the same material as the non-conductive substance of the closing body is formed on the surface portion of the closing body 50 made of functionally gradient material where the conductive substance is present and a part of the external lead wire 56. This can be solved.
[0022]
For example, in the case of a discharge lamp in which a closed body 50 made of functionally graded material made of molybdenum and silica is used, and a light emitting tube 11 made of quartz glass and an external lead wire 56 are made of tungsten, silica is used for the purpose of preventing oxidation. The film 58 is formed. Originally, silica of the same material as that of the arc tube is present on the conductive material side of the closing body 50, and silica is also present in the cermet 57 used for fixing the external lead wire 56 and the closing body 50. Therefore, when a silica film 58 of several tens of μm is formed in such a state, the wettability is surely covered and the electrical conduction failure due to oxidation can be completely prevented.
[0023]
As described above, the discharge lamp has a highly reliable seal portion with respect to heat and pressure as compared with the case of welding using molybdenum foil.
[0024]
【Example】
In the following, a discharge lamp was manufactured under the conditions shown in FIG. 1 and within the conditions of claims 6 and 7, and the lamp characteristics were evaluated. The production conditions are: discharge space volume 0.15 cc, distance between electrodes 1.4 mm, enclosed mercury amount 35 mg, enclosed mercury bromide amount 0.5 mg, gradient functional material occlusion body outer diameter 1.90 mm, gradient functional material occlusion body length 27 mm Arc tube occlusion tube outer diameter φ 6 mm, arc tube occlusion tube inner diameter 2 mm, occlusion body welded part length 7 mm, arc tube and occlusion tube material quartz glass, functionally graded material occlusion body non-conductive substance silica, functionally graded material occlusion body conductivity Material molybdenum, electrode and electrode rod material tungsten, external lead wire material tungsten, cermet material tungsten-silica (volume ratio 30% -70%).
[0025]
FIG. 2 shows changes in the composition of molybdenum and silica in the closed body made of functionally gradient material used in this example. The composition is 100% silica up to 7 mm from the end face on the arc tube side, and the composition continuously inclines from there to the external lead wire side, and electrical conduction can be obtained on the end face on the external lead side (volume ratio molybdenum). 25% -silica 75%). A portion where the silica was almost 100% was welded and sealed to the closed tube of the arc tube. The tungsten electrode rod is inserted up to a position of 18 mm from the end face on the arc tube side, and the external lead wire is inserted up to a position of 4 mm from the end face on the opposite side. It is in a state where the electrical continuity can be taken. Table 1 shows the characteristics of the discharge lamp alone. As is apparent from Table 1, it became possible to achieve an operating pressure of 200 atm or higher with a power of 150 W or higher.
[0026]
Table 1
[0027]
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a longitudinal side view showing a lamp device including the discharge lamp using the functionally gradient material shown in FIG. 1 together with its lighting device.
[0028]
The lamp device 70 of the present embodiment is a lamp device in which the discharge lamp 1 using a functionally gradient material is concentrically mounted on the inner diameter bottom portion of the bowl-shaped reflecting mirror 72.
The reflecting mirror 72 is a member formed in a bowl shape from glass or metal, and includes a dichroic mirror film 72a of a multilayer interference film on the inner surface of a rotating curved surface having the focal position. Thereby, infrared rays are transmitted to the back side of the reflecting mirror 72, while visible light is reflected to the light projection port 72b side.
[0029]
A mounting hole 72c is formed in a substantially central shaft portion of the bowl-shaped bottom portion of the reflecting mirror 72 so as to penetrate in the thickness direction. The outer end of one end of the discharge lamp 1 using the functionally gradient material and the base 73 fitted on the end are horizontally placed in a support cylinder 72d surrounding a mounting hole 72c provided in the bottom middle part of the reflecting mirror 72. Are concentrically inserted from each other and fixed by an electrically insulating cement 74.
[0030]
Further, the discharge lamp 1 is arranged so that the intermediate point between the electrodes in the discharge space substantially coincides with the focal point of the reflecting mirror 72. An introduction hole 75 is formed in the reflecting mirror 72, and a lead wire 76 a connected to the external lead wire 56 a of the discharge lamp 1 passes through the introduction hole 75 and is led to the back side. The leading end of the lead wire 76a is connected to one end of the lighting circuit 77, and the other end of the lighting circuit 77 is connected to the external terminal 78 of the base 73 of the discharge lamp 1 through another lead wire 76b.
[0031]
Such a lamp device was incorporated in the liquid crystal projector 80 shown in FIG. 4 and the light output was evaluated. A color liquid crystal panel 81 and a light projection lens 82 are installed in front of the light projection of the lamp device 70 shown in FIG. 3, and a shadow image displayed on the liquid crystal display panel 81 is projected onto the screen 83. A lamp device 70, a lighting circuit 77, a liquid crystal display panel 81, and a liquid crystal panel driving device 84 that drives the liquid crystal display panel 81 are housed in a housing 85.
[0032]
A performance comparison was made between a 250 W metal halide lamp that is currently used mainly and a 150 W discharge lamp using the functionally gradient material shown in the first embodiment of the present invention. When the brightness of the screen (ANSI lumen) was measured and compared as an evaluation index, an ANSI lumen value 1.8 times that of a 250 W metal halide lamp was obtained in spite of 150 W. As a result, it was possible to obtain a discharge lamp with very high brightness and stable and high luminous efficiency.
[0033]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
[0034]
The functionally gradient material constituted according to claims 1 and 2 has a strong heat shock and mechanical strength because it does not have a boundary surface where the composition of its constituent components changes greatly. Also, when inserting the electrode rod of the closing body into the axial hole formed in the closing body of the functionally gradient material rich in the non-conductive substance up to the conductive portion to establish electrical continuity with the outside In addition, a cermet is formed in the gap between the electrode rod and the closed functional body made of the functionally graded material from a conductive material of the same material as the electrode rod and a non-conductive material made of the same material as the arc tube. It serves to alleviate the difference in the thermal expansion coefficient between the rod and the electrode rod, and eliminates the thermal shock between the electrode rod and the block made of functionally graded material, thereby improving reliability. It became possible to use a lamp.
[0035]
According to the third aspect of the present invention, at least 2 mm or more is welded over the entire circumference of the occlusion pipe in the direction from the end face made of the non-conductive substance of the occlusion pipe and the occlusion body to the end face made of the conductive substance. By setting the welded length to 2 mm or more, problems such as leakage can be reliably prevented.
[0036]
According to the fourth aspect, it is possible to fix the conductive side portion of the closing body made of the functionally graded material and the conductive wire extending outside the arc tube without impairing electrical conduction.
[0037]
According to the fifth aspect, it is possible to prevent the conduction portion of the closing body from being oxidized.
[0038]
According to the sixth and seventh aspects, a lamp capable of obtaining the highest performance according to the present invention can be obtained.
[0039]
Since the lamp device according to the eighth aspect, the lighting device according to the ninth aspect, and the liquid crystal projector according to the tenth aspect include the discharge lamp according to the first aspect, the same effects as those of the respective claims can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of a discharge lamp using a functionally gradient material, showing a first embodiment of the present invention.
FIG. 2 is a graph showing the first embodiment of the present invention and showing the change in composition in the axial direction of a closed body made of a functionally gradient material.
3 is a longitudinal side view showing a lamp device including a discharge lamp using the functionally gradient material shown in FIG. 1 together with its lighting device as a second embodiment of the present invention.
4 is a longitudinal sectional side view of a liquid crystal projector including the lamp device shown in FIG. 3 as a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Discharge lamp, 11 ... Light-emitting tube, 12 ... Blocking tube, 20 ... Tungsten electrode 21 ... Electrode rod, 50 ... Blocking body, 51 ... Non-conductive substance side end face 52 ... Conductive substance side end face, 53 ... Hole, 54 ... Cermet, 55 ... Hole 56 ... External lead wire, 57 ... Cermet, 58 ... Film, 70 ... Lamp device 72 ... Reflector, 72a ... Dichroic mirror film, 72b ... Light projection port 72c ... Mounting hole, 72d ... Support cylinder 73 ... Base 74 ... Electrical insulating cement, 75 ... Introducing hole, 76 ... Lead wire 77 ... Lighting circuit, 78 ... External terminal, 80 ... Liquid crystal projector 81 ... Liquid crystal panel, 82 ... Projection lens, 83 ... Screen 84 ... Liquid crystal panel drive, 85 ... Housing [Table 1]

Claims (10)

When made of non-conductive material having a region surrounding the discharge space and both arc tube filled with a discharge gas,
An occlusion tube formed at an end of the arc tube;
An occlusion body that occludes a portion of the occlusion tube;
A pair of electrode rods arranged opposite to each other in the discharge space to form a discharge path;
A discharge lamp comprising:
The closing body is formed by mixing a non-conductive substance and a conductive substance of the same material as the arc tube continuously or stepwise in the length direction, the discharge space side being non-conductive and the other end. Made of functionally gradient material with conductive side,
A counterbore for inserting the electrode rod is formed in the non-conductive end face of the closing body, and the same material as the electrode rod is interposed between the electrode rod and the closing body in the counterbore hole. A discharge lamp comprising a conductive material and a cermet made of a non-conductive material of the same material as the arc tube.   2. The discharge lamp according to claim 1, wherein the ratio of the conductive material in the cermet is 15% or more and 50% or less by volume ratio.   2. The discharge lamp according to claim 1, wherein a non-conductive portion made of the same material as the closed tube is welded to the closed tube over the entire circumference of the closed body.   2. The discharge lamp according to claim 1, wherein the cermet exists between a conductive side portion of the closing body made of the functionally gradient material and an external lead wire extending to the outside of the arc tube. .   5. The film made of the same material as the non-conductive substance of the closing body is formed on a surface portion where the conductive material of the closing body made of the functionally gradient material is present and a part of the external lead wire. The described discharge lamp.   The discharge space is between 0.05 cc and 0.30 cc, the distance between the electrodes facing each other in the discharge space is between 0.8 mm and 2.0 mm, and is enclosed in the discharge space. 2. The discharge lamp according to claim 1, wherein the amount of mercury in the sealed gas is between 10 mg and 60 mg, and the amount of mercury bromide is between 0.1 mg and 1.0 mg.   The inner diameter of the cylindrical occlusion tube formed at the end of the arc tube is between 0.5 mm and 3.5 mm, and the outer diameter of the occlusion body made of the functionally graded material is 0.45 to 3.5 mm. The length of the closing body is between 5 mm and 50 mm, and the portion where the volume ratio of the non-conductive substance is 98% or more is 2 mm from the end face of the closing body located on the arc tube side. The discharge lamp according to claim 1, which is as described above.   A discharge device comprising: the discharge lamp according to claim 1; and a reflecting mirror that reflects light from the discharge lamp in a predetermined direction. A discharge device of claim 8, wherein the discharge lamp lighting device according to claim to power the lamp power to and a lighting circuit for lighting stably to the pair of electrodes. 10. The lighting device according to claim 9, a liquid crystal display panel driven by a liquid crystal driving device, an optical system that controls light from the discharge lamp and projects light onto a screen through the liquid crystal display panel, and the lighting device A liquid crystal projector comprising: a housing that houses the liquid crystal driving device, the liquid crystal display panel, and the optical system, and has an opening that projects light transmitted through the liquid crystal display panel onto a screen. .

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