JP2000123791A - Discharge lamp using gradient function material, discharge device, lighting device and liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lamp having very high brightness, stable luminous efficiency, a stable color spot, a long service life and a large luminous flux. SOLUTION: This discharge lamp is so structured that an arc tube 11 that has a region surrounding a discharge space and is formed of a nonconductive material, and cylindrical closing tubes 12 which are formed at the ends of the arc tube 11 and in which a pair of electrodes are arranged opposite to each other in the arc tube 11 to form a discharge path, and a discharging gas is sealed are closed by closing bodies each formed of a functionally gradient material which is formed by mixing a nonconductive substance of the same material as the arc tube 11 and a conductive substance at a continuously or stepwise different ratio in the lengthwise direction so as to make the discharge space side nonconductive and the other end side conductive. At that time, a conductive substance of the same material as an electrode rod and a cermet 54 formed of a nonconductive substance of the same material as the arc tube 11 are arranged in each gap between the closing body formed of the gradient function material and the electrode rod.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp using a functionally graded material as a part of an electrode, a discharge device using the discharge lamp as a light source, a lighting device, and a liquid crystal projector.

[0002]

Conventionally, such a lamp is known from EP-A-0 338 637. 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, has high luminous flux maintenance, and its color point changes little during its life.

A lamp known from the above-mentioned EP patent application has an elongated, narrow cylindrical arc tube and a 50 Watt power supply.
Consumes less power: But this lamp
The luminous flux is too small for the purpose of image projection such as a liquid crystal projector.

[0004] A discharge lamp as disclosed in JP-A-6-52830 is known. In this lamp, as shown in the embodiment of JP-A-6-52830, a pair of electrodes are opposed to each other in an elliptical arc tube at the center of a discharge vessel made of quartz glass, and a luminous metal such as mercury, a discharge gas, etc. Is enclosed. Then, cylindrical closed tubes are continuously provided at both ends of the arc tube, and the ends of the electrode rod and the external lead bar are welded to both ends of a molybdenum foil having a thickness of several tens of μm, and the molybdenum foil is sandwiched between quartz glass. And a fused tube made of quartz glass is welded to the central portion of the molybdenum foil. In this electrode structure, the coefficient of thermal expansion of the molybdenum foil or electrode rod during lighting is significantly different from the coefficient of thermal expansion of quartz glass.
In some cases, the seal portion peeled off due to the expansion and leaked or was damaged.

[0005] Further, in the case of sealing 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 peeling and poor electrical conduction.

[0006] In particular, in the case of a discharge lamp which consumes 100 W or more at a high operating pressure of 200 bar as shown in JP-A-6-52830, the tendency is increased. 15 not shown in 52830
In the case of a discharge lamp consuming 0 W or more of power,
It was broken at the time of initial lighting with the probability of being close to 100%, and was not established as a discharge lamp.

[0007] Nevertheless, very large brightness,
There is a strong demand for a discharge lamp that has a stable high luminous efficiency, a stable color point and a long life, and that has a larger luminous flux than, for example, a lamp of an LCD projection TV.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lamp having a very high brightness, a stable luminous efficiency, a stable color point, a long life and a large luminous flux.

[0009]

According to the present invention, the above-mentioned object has been attained by making the first discharge lamp 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 arranged in the arc tube to oppose each other to form a discharge path and discharge gas. A sealed cylindrical tube formed at the end of the arc tube is made by mixing a non-conductive substance and a conductive substance of the same material as the arc tube at different ratios continuously or stepwise in the length direction. In the discharge lamp closed by a closed body made of a functionally graded material in which the discharge space side is non-conductive and the other end side is conductive,
A conductive material of the same material as the electrode rod and a cermet of a non-conductive material of the same material as the arc tube are present in a gap between the closing member made of the functionally gradient material and the electrode rod. That is, when the arc tube is made of quartz glass, the closed tube at the end of the arc tube is made of a cermet containing a non-conductive material of silica, a conductive material such as molybdenum, and a non-conductive material of silica of the same material as the arc tube. The discharge lamp is closed by a closing body made of a functionally gradient material. In the closed body formed of such a functionally gradient material, the end on the discharge space side is rich in silica non-conductive substance, and the ratio of the conductive substance such as molybdenum continuously increases toward the other end. , And gradually increase. 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 as a material of the arc tube.

[0010] Such a functionally graded material does not have a boundary surface in which the composition of its constituents changes greatly, so that it has high heat shock and mechanical strength. Further, when the electrode rod of the closing body is inserted into the axial hole formed up to the conductive part in the closing part of the portion where the non-conductive substance of the functionally graded material is rich to establish conduction with the outside. Then, a cermet is formed in the gap between the electrode rod and the closing body made of a functionally graded material from a conductive material of the same material as the electrode rod and a non-conductive substance of the same material as the arc tube, so that the cermet is It serves to alleviate the difference in the coefficient of thermal expansion between the closed body and the electrode rod between the rod and the rod, and eliminates the thermal shock between the electrode rod and the closed body made of functionally graded material, thereby further improving reliability. Lamp.

Therefore, it is possible to solve the problem that the seal portion is peeled off or damaged due to the expansion of the seal portion caused by the temperature rise when the discharge lamp is turned on. In particular, JP
Even with a discharge lamp not shown in 52830, which consumes more than 150 W at a high operating pressure of 200 bar, it is possible to provide a lamp which is not broken with a probability of almost 100%.

An eighth aspect of the present invention provides a lamp device including a discharge lamp using the functionally graded material according to the first aspect and a reflector for reflecting light from the discharge lamp in a predetermined direction. Accordingly, light from the discharge lamp using the functionally graded material is reflected by the reflecting mirror and guided in a predetermined direction. In this case, if the reflector has a structure in which one end of a discharge lamp using a functionally graded material is held, the heat of the discharge lamp is efficiently radiated to the outside through the reflector.

According to a ninth aspect of the present invention, there is provided a lighting device including a discharge lamp using the functionally graded material according to the first aspect and a lighting circuit for supplying a lamp power to a pair of electrodes of the discharge lamp to stably light the lamp. .

According to a tenth aspect of the present invention, there is provided a liquid crystal projector which controls light from a discharge lamp using a functionally graded material provided in the lighting device, the liquid crystal display panel driven by the liquid crystal driving device, and the lighting device. A housing that houses an optical system and a lighting device that emits light to a screen through a liquid crystal display panel, a liquid crystal driving device, a liquid crystal display panel, and an optical system, and that has an opening formed to project light transmitted through the liquid crystal display panel onto the screen. Have.

Therefore, the lighting device according to the ninth aspect and the liquid crystal projector according to the tenth aspect include the discharge lamp using the functionally gradient material according to the first aspect. It works.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 inside the arc tube. In addition, argon gas is sealed at a predetermined pressure as a discharge gas, and mercury and mercury bromide are sealed as light emitting metals in predetermined amounts. The closed tubes 12 are provided at both ends of the arc tube 11.
Are continuously provided, but the end of the closing tube 12 is closed by a closing body 50 made of a functionally graded material. The functionally graded material used here is a material obtained by sintering the same material as the discharge vessel, silica and the conductive material molybdenum, and varying the mixing ratio 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 5 on the non-conductive side of the closing body 50
Numeral 1 is a cermet composed of almost 100% silica, and a conductive side end 52 at the other end is composed of 25% molybdenum and 75% silica by volume, but the composition ratio is not necessarily limited to this. Not something.

The closing body 50 is fitted into the closing tube 12 such that the end face 51 made of a non-conductive substance is directed toward the arc tube 11, and the end face 51 is welded to the quartz glass closing body 12. Is done. At this time, as shown in claim 3,
End surface 5 of non-conductive substance of occlusion tube 12 and occlusion body 50
1 is welded over the entire circumference of the closed tube 12 by at least 2 mm in the direction of the end face 52 made of a conductive material. If the welded length is 2 mm or less, the sealing portion may be too short, which may cause problems such as leaks.

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 formed in the end face 5 made of a non-conductive material of the closing body 50.
A counterbore in the axial direction from No. 1 to an electrically conductive portion toward the end face made of a conductive material of the closing body 50. With the electrode rod 21 inserted into the hole 53, the closing member 50 is closed.
A cermet 5 made of a non-conductive substance made of the same material as the arc tube 11 in this case, silica, and a conductive substance made of the same material as the electrode rod 21 in this case, tungsten
There are four. The cermet 54 is used for the electrode rod 21.
It has a function to alleviate the thermal shock between the electrode rod 21 and the closing body 50 and to securely fix the electrode rod 21 and the closing body 50.

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. If the volume ratio of the conductive material is 50% or more, the conductive material may not be sintered well with the non-conductive material. This is a factor that adheres to the inner wall of the arc tube 11 and hinders light. Therefore, the composition of the cermet is ideally such that the volume of the conductive substance described in claim 2 is in the range of 15% or more and 50% or less.

A counterbore hole 55 is also formed in the end face 52 of the closing body 50 on the conductive material side in the axial direction, so that the outside and the electrode 20 can be connected.
An external lead wire 56 for establishing electrical continuity is inserted into the hole 55. The external lead wire 56 is made of tungsten or molybdenum. As shown in claim 4, the cermet 57 is interposed between the external lead wire 56 and the external lead wire 56, which is securely fixed to the closing body 50 to achieve electrical conduction.

The external lead wire 56 and the arc tube 11
Since the closing body 50 on the side of the external lead wire 56 from the portion welded to the outside is in contact with the air, the closing body 5 becomes 350 ° C. or higher at the time of lighting as in the case of the molybdenum foil seal.
In some cases, the conductive material and the external lead wires 56 present on the surface 0 are oxidized, causing electrical conduction failure. Therefore,
As shown in claim 5, a closure 5 made of a functionally graded material
A coating 5 made of the same material as the non-conductive substance of the closing body on the surface portion where the conductive substance
8 can be solved.

For example, in the case of a discharge lamp using an occlusion body 50 made of a functionally graded material made of molybdenum and silica and using a luminous tube 11 made of quartz glass and an external lead wire 56 made of tungsten, the purpose is to prevent oxidation. Then, a silica film 58 is formed. Originally, silica of the same material as that of the arc tube exists on the conductive material side of the closing body 50, and silica also exists in the cermet 57 used for fixing the external lead wire 56 and the closing body 50. Therefore, when the silica film 58 of several tens of μm is formed on the portion in such a state, the wettability is good and the coating is ensured, and the electrical conduction failure due to oxidation can be completely prevented.

As described above, a discharge lamp having a seal portion which is highly reliable against heat and pressure as compared with a case where welding is performed using molybdenum foil is obtained.

[0024]

EXAMPLE A discharge lamp constructed as shown in FIG. 1 and within the conditions defined in claims 6 and 7 was manufactured and its lamp characteristics were evaluated. The manufacturing conditions were as follows: discharge space volume: 0.15 cc, distance between electrodes: 1.4 mm, amount of enclosed mercury: 35 mg, amount of enclosed mercury bromide: 0.5 mg, outer diameter of functionally graded material closure: 1.90 mm, length of functionally graded material closure: 27 m
m, arc tube occlusion tube outer diameter φ6 mm, arc tube occlusion tube inner diameter 2 m
m, length of a welded portion of an obstruction body 7 mm, quartz glass material of an arc tube and an obstruction tube, functionally graded material obstruction body non-conductive substance silica,
Functionally graded material Closed body Conductive substance molybdenum, electrode and electrode rod material tungsten, external lead wire material tungsten, cermet material tungsten-silica (volume ratio 30
% -70%).

FIG. 2 shows a change in the composition of molybdenum and silica in the plug made of the functionally graded material used in the present embodiment.
Up to 7 mm from the end face on the side of the arc tube, the composition is 100% silica, and the composition continuously slopes toward the external lead wire side, and electrical conductivity is obtained at the end face on the external lead side (molybdenum by volume ratio). 25% -75% silica). A portion almost 100% of silica was welded and sealed to the arc tube closing tube. The tungsten electrode rod was inserted up to a position 18 mm from the arc tube side end face.
Further, the external lead wire is inserted up to a position of 4 mm from the end face on the opposite side, so that electrical conduction can be sufficiently established between the electrode and the external lead. Table 1 shows the characteristics of the discharge lamp alone. As is clear from Table 1, 150
It has become possible to achieve an operating pressure of 200 atm or more with an electric power of W or more.

Table 1

Next, a second embodiment of the present invention will be described with reference to FIG.
A description will be given based on FIG. FIG. 3 is a vertical sectional side view showing a lamp device provided with a discharge lamp using the functionally graded material shown in FIG. 1 together with its lighting device.

The lamp device 70 of the present embodiment is a lamp device in which the discharge lamp 1 using a functionally graded material is mounted concentrically on the inner bottom of the reduced diameter of the bowl-shaped reflecting mirror 72. The reflecting mirror 72 is a bowl-shaped member made of glass or metal, and includes a dichroic mirror film 72a of a multilayer interference film on the inner surface of the rotating curved surface having the focal position. Thus, the infrared light is transmitted to the rear side of the reflecting mirror 72, while the visible light is reflected to the light emitting port 72b.

A mounting hole 72c is formed substantially in the center axis of the bowl-shaped bottom 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 graded material and the base 73 externally fitted to the one end are horizontally placed in a support cylinder 72d surrounding a mounting hole 72c provided at the bottom middle part of the reflector 72. And are fixed concentrically with an electrical insulating cement 74.

The discharge lamp 1 is arranged such that the midpoint 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 penetrates through the introduction hole 75 and is guided to the rear side. One end of the lead wire 76a is connected to one end of a lighting circuit 77, and the other end of the lighting circuit 77 is connected to an external terminal 78 of a base 73 of the discharge lamp 1 via another lead wire 76b.

Such a lamp device was incorporated in a liquid crystal projector 80 shown in FIG. 4, and the light output was evaluated. A liquid crystal panel 81 of color or the like and a light projecting 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 on a screen 83. Further, a lamp device 70, a lighting circuit 77, a liquid crystal display panel 81, and a liquid crystal panel driving device 84 for driving the liquid crystal display panel 81 are housed in a housing 85.

The performance of a 250 W metal halide lamp currently used mainly and a 150 W discharge lamp using the functionally graded material shown in the first embodiment of the present invention were compared. Screen brightness (A
NSI lumens) were measured and compared.
Despite the W, the ANSI lumen value was 1.8 times higher than that of the 250 W metal halide lamp. According to the present invention, a discharge lamp with extremely high brightness and stable high luminous efficiency was obtained.

[0033]

According to the present invention, the following effects are exhibited by the above configuration.

According to the first and second aspects of the present invention, the functionally graded material does not have a boundary surface in which the composition of the constituents changes greatly, so that it has high heat shock and mechanical strength. Further, when the electrode rod of the closing body is inserted into the axial hole formed up to the conductive part in the closing part of the portion where the non-conductive substance of the functionally graded material is rich to establish conduction with the outside. Then, a cermet is formed in the gap between the electrode rod and the closing body made of a functionally graded material from a conductive material of the same material as the electrode rod and a non-conductive substance of the same material as the arc tube, so that the cermet is It serves to alleviate the difference in the coefficient of thermal expansion between the closed body and the electrode rod between the rod and the rod, and eliminates the thermal shock between the electrode rod and the closed body made of functionally graded material, thereby further improving reliability. Lamps.

According to the third aspect, the closed pipe and the closed body are welded over at least 2 mm from the end face made of a non-conductive substance to the end face made of a conductive substance over the entire circumference of the closed pipe. By setting the welded length to 2 mm or more, defects such as leaks can be reliably prevented.

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 conducting wire extending outside the arc tube without impairing electrical conduction.

According to the fifth aspect, it is possible to prevent the conductive portion of the closing body from being oxidized.

According to the sixth and seventh aspects, it is possible to obtain a lamp capable of obtaining the highest performance according to the present invention.

The lamp device according to claim 8, the lighting device according to claim 9, and the liquid crystal projector according to claim 10,
Since the discharge lamp of claim 1 is provided, the same effects as those of each claim can be obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention and is a longitudinal sectional side view of a discharge lamp using a functionally graded material.

FIG. 2 is a graph showing a first embodiment of the present invention and showing a change in composition in an axial direction of an obstruction body made of a functionally graded material.

FIG. 3 is a longitudinal sectional side view showing a lamp device provided with a discharge lamp using the functionally graded material shown in FIG. 1 together with a lighting device as a second embodiment of the present invention.

FIG. 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 ... Arc tube, 12 ... Closed tube, 20 ...
Tungsten electrode 21 ... electrode rod, 50 ... closer, 51 ... non-conductive material side end face 52 ... conductive material side end face, 53 ... hole, 54 ... cermet, 55 ... hole 56 ... external lead wire, 57 ... cermet, 58 ... film,
70 lamp device 72 reflector mirror 72a dichroic mirror film 72b
... light emitting port 72c mounting hole 72d support cylinder 73 base 74 electrically insulating cement 75 introduction 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)

[Claims] 1. An arc tube made of a non-conductive material having a region surrounding a discharge space, and a pair of electrodes arranged in the arc tube to face each other, forming a discharge path and enclosing a discharge gas to emit light. A cylindrical closed tube formed at the end of the tube 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 longitudinal direction at different ratios. The discharge space side is made non-conductive, and the other end side is made of a functionally graded material that is conductive.In the closed discharge lamp, the electrode rod is provided in the gap between the functionally graded material and the electrode rod. A discharge lamp comprising a cermet made of a conductive material of the same material and a non-conductive material of the same material as the arc tube. 2. A cermet conductive material comprising a conductive material of the same material as the electrode and a non-conductive material of the same material as the arc tube has a volume ratio of 15% or more and 50% or less. Item 1. A discharge lamp according to Item 1. 3. The discharge lamp according to claim 1, wherein the closed tube and a non-conductive portion of the closed body made of the same material as the closed tube are welded over at least 2 mm over the entire circumference of the closed tube. 4. The method according to claim 1, wherein the conductive side portion of the closing body made of a functionally gradient material is connected to a conductor extending outside the arc tube.
2. A discharge lamp according to claim 1, wherein the same cermet is present. 5. A film made of the same material as the non-conductive substance of the closing body is formed on a surface portion of the closing body made of a functionally gradient material where the conductive substance is present and on a part of the conductive wire according to claim 4. The discharge lamp according to claim 1. 6. The discharge space is between 0.05 cc and 0.30 cc, the distance between opposed electrodes is between 0.8 mm and 2.0 mm, and the amount of mercury is 1
Between 0mg and 60mg, mercury bromide amount 0.1m
2. The composition of claim 1, wherein the amount is between g and 1.0 mg.
Discharge lamp. 7. The cylindrical closed tube formed at the end of the arc tube has an inner diameter of 0.5 mm to 3.5 mm, and an outer diameter of the closed body made of a functionally graded material is 0.45 to 3 mm. 0.5mm
The length of the closed body is between 5 mm and 50 mm, and the portion having a composition in which the volume ratio of the non-conductive substance is 98% or more is at least 2 mm or more from the end face of the closed body located on the arc tube side. The discharge lamp according to claim 1, wherein: 8. A discharge apparatus comprising: the discharge lamp according to claim 1; and a reflecting mirror that reflects light from the discharge lamp in a predetermined direction. 9. A lighting device, comprising: the discharge lamp according to claim 1; and a lighting circuit that supplies lamp power to a pair of electrodes of the discharge lamp to stably light the lamp. 10. A lighting device according to claim 8, a liquid crystal display panel driven by the liquid crystal driving device, and a lighting device, wherein the light from the discharge lamp is controlled to project light to a screen through the liquid crystal display panel. And a lighting device, a liquid crystal driving device, a liquid crystal display panel, and a liquid crystal display, comprising a housing having an opening formed therein for projecting light transmitted through the liquid crystal display panel to a screen. projector.