JPH1125917A - Discharge lamp, lamp device and liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of discharge at the root. SOLUTION: A discharge lamp comprises: an air-tight container 2 made of quartz glass; a discharge medium enclosed inside the air-tight container 2 and including at least metal halide; an anode 5 and a cathode 6 disposed opposite to each other inside the air-tight container 2 with a predetermined interval therebetween; and a projection 8 projecting toward the anode 5 around a portion where the cathode 6 penetrates at the inner circumferential surface of the air-tight container 2. Although the metal halide inside the air-tight container 2 is vaporized during lighting while solidified when extinguished, the formation of the projection 8 formed at the root of the cathode 6 can prevent the solidified metal halide from staying at the root of the cathode 6, thereby preventing generation of discharge at the root during the lighting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a discharge lamp, a lamp device, and a liquid crystal projector.

[0002]

2. Description of the Related Art In recent years, as a light source of a liquid crystal projector, a short arc type metal halide lamp which is lit by a DC power supply has been widely used. The short arc type metal halide lamp is easy to control in the optical system because it is close to a point light source, it can obtain a large amount of light for low power, and it radiates red, blue, and green components efficiently. It is excellent in that the calorific value is small.

In a metal halide lamp, a metal halide (a compound of a metal and a halogen), mercury, and a rare gas are sealed in an airtight container made of quartz glass, and an anode and a cathode face each other at a predetermined interval. Are located.

When the metal halide lamp is turned on, a DC voltage is applied to the anode to discharge the anode to the cathode. At the time of this lighting, the temperature on the anode side becomes high, but the cathode side does not generate much heat. In addition, the metal halide evaporates during lighting, and solidifies when turned off. In this case, since the temperature on the cathode side is lower than that on the anode side, solidification of the metal halide proceeds faster on the cathode side, and the solidified metal halide tends to accumulate at the root of the cathode.

[0005]

When a large amount of solidified metal halide accumulates at the base portion of the cathode, immediately after lighting, the solidified metal halide accumulated at the base portion of the cathode and the anode are exposed. Discharge (hereinafter referred to as root discharge) occurs. As a result, the temperature of the inner wall of the airtight container on the cathode side becomes locally high, and the airtight container may be cracked.

Accordingly, the present invention prevents a large amount of solidified metal halide from accumulating at the base of the cathode, and prevents the occurrence of base discharge between the metal halide accumulated at the base of the cathode and the anode. An object of the present invention is to provide a discharge lamp that can be used, a lamp device using the discharge lamp, and a liquid crystal projector.

[0007]

According to a first aspect of the present invention, there is provided a discharge lamp comprising: an airtight container formed of quartz glass;
A discharge medium containing at least a metal halide sealed in the hermetic container; an anode and a cathode disposed opposite to each other in the hermetic container at a predetermined interval; and the cathode in an inner peripheral surface of the hermetic container penetrates. A protruding portion formed on the periphery of the portion to be protruded toward the anode. The projection may be formed such that the thickness of the quartz glass is thicker at the base of the cathode and the discharge space side is gradually thinner, or that the base of the cathode is coated with a refractory insulator. Therefore, the metal halide evaporates when the discharge lamp is turned on and solidifies when the discharge lamp is turned off, and the solidified metal halide easily accumulates on the cathode side where the temperature at the time of lighting is low, but the cathode on the inner peripheral surface of the hermetic container penetrates. Since the protruding portion protruding toward the anode side is formed around the portion where the metal halide is present, the solidified metal halide does not accumulate at the root portion of the cathode, and no root discharge occurs at the time of lighting again. The root discharge is a discharge generated between the anode and the solidified metal halide accumulated at the root of the cathode immediately after lighting. When root discharge occurs, the temperature of the inner wall of the airtight container on the cathode side becomes locally high, and the airtight container may be cracked.

According to a second aspect of the present invention, there is provided a lamp device comprising: the discharge lamp according to the first aspect; and a reflecting mirror that reflects light from the discharge lamp in a predetermined direction. Therefore, according to the lamp device of the present invention, the occurrence of the root discharge at the time of lighting is prevented, and the decrease in the durability due to the root discharge does not occur.

According to a third aspect of the invention, there is provided a liquid crystal projector according to the second aspect, a liquid crystal display panel irradiated with light from the lamp device, and a liquid crystal driving device for driving the liquid crystal display panel. An optical system for projecting the light passing through the liquid crystal display panel onto a projection target surface; and a housing accommodating at least the lamp device, the liquid crystal display panel, and the optical system. Therefore, according to the liquid crystal projector of the present invention, the occurrence of the root discharge at the time of lighting is prevented, and the decrease in durability due to the root discharge does not occur.

[0010]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a vertical side view showing a lamp device using a discharge lamp, FIG. 2 is a vertical side view showing an enlarged discharge lamp, and FIG. 3 is a vertical side view showing a schematic structure of a liquid crystal projector using this lamp device. It is.

First, the discharge lamp 1 will be described. The discharge lamp 1 includes an airtight container 2 made of quartz glass. The airtight container 2 has a thickness of about 1.2.
mm, a major axis is about 14 mm, and a minor axis is about 11 mm. The elliptical rotor has a discharge space having a volume of about 1 cc. Sealing portions 3 and 4 are formed at both ends in the major diameter direction on the outer peripheral portion of the airtight container 2. An anode 5 and a cathode 6 are disposed inside the hermetic container 2 at opposite ends in the major diameter direction. The cathode 6 has a wire diameter of 0.7 m.
m, and the anode 5 has a wire diameter of 0.7 m.
A large diameter portion 7 is formed at the tip of tungsten of m. The electrode interval between the anode 5 and the cathode 6 is set to about 3 mm.

A projection 8 protruding toward the anode 5 is formed around an inner peripheral surface of the hermetic container 2 around a portion through which the cathode 6 penetrates. This projection 8
Is set to about 5 mm.

The portions of the anode 5 and the cathode 6 that have come out of the hermetic container 2 are sealed in the sealing portions 3 and 4 and are sealed in the sealing portions 3 and 4. Metal foil conductor 9,
10 is connected. The metal foil conductors 9 and 10 are formed using molybdenum to have a thickness of about 30 μm and a width of about 3 mm. One metal foil conductor 9 is connected to the base 11,
The other metal foil conductor 10 is connected to an external lead wire 12.

In the hermetic container 2, a discharge medium such as a metal halide as a light emitting metal, mercury as a buffer metal for suppressing light emission of the metal halide, and a rare gas is sealed. Metal halides are dysprosium (Dy),
Neodymium (Nd), Holmium (Ho), Thulium (T
m) a halide of at least one rare earth metal selected from the group consisting of: a halide of cesium (Cs);
Indium (In), and thallium (T
l), at least one metal halide selected from gallium (Ga), zinc (Zn), and cadmium (Cd). The amount of these metal halides to be enclosed is 1.0 × 10 to ⁷ per unit arc length.
Mol / mm to 1.0 × 10 to ⁶ mol / mm.

A reflective film (not shown) is applied on the outer peripheral surface of the hermetic container 2 in a range from the end on the side where the cathode 6 is sealed to the vicinity of the front end of the cathode 6. For this reflection film, Al ₂ O ₃ —SiO ₂ , platinum or the like can be used.

Next, a lamp device 13 using the discharge lamp 1 will be described. The lamp device 13 is configured such that the base 11 of the discharge lamp 1 is
And is bonded by an adhesive 16 such as insulating cement. The reflecting mirror 14 reflects light from the discharge lamp 1 in a predetermined direction.
On the inner peripheral surface of No. ₄ , a reflection surface 14a made of a deposited film of TiO ₂ —SiO ₂ or the like having excellent reflection characteristics is formed. The external lead wire 12 is connected to the reflecting mirror 14 by the reflecting mirror 14.
Is formed at the back side of the substrate.

Next, a liquid crystal projector 18 using the lamp device 13 will be described. The liquid crystal projector 18 includes the lamp device 13 and the discharge lamp 1.
Lighting circuit 1 for controlling lighting by applying a DC voltage to the anode 5
9, a liquid crystal display panel 20 for color, a liquid crystal driving device 21 for driving the liquid crystal display panel 20, and an optical system for projecting an image displayed on the liquid crystal display panel 20 onto a screen 22, which is a projection surface. And a light projecting lens 23. These lamp device 13, lighting circuit 19, liquid crystal display panel 20, liquid crystal drive device 21, and light projecting lens 23
It is stored in the housing 24.

Here, the lighting circuit 19 converts an alternating current into a direct current, and the ripple frequency "f" at this time is set so that f <610 / d. Here, d is the maximum diameter of the airtight container 2.

In such a configuration, when lighting the discharge lamp 1, a DC voltage is applied to the anode 5 to cause a discharge between the anode 6 and the cathode 6. As a result, the metal halide evaporates, and discharge occurs while the metal halide evaporates, so that the discharge lamp 1 emits light. At the time of lighting, the temperature of the anode 5 is high and the temperature of the cathode 6 is low.

When the light is turned off, the metal halide is solidified. Solidification of the metal halide proceeds rapidly on the side of the cathode 6 where the temperature is low. However, the cathode 6 on the inner peripheral surface of the hermetic container 2
Since the projection 8 is formed at the base side of the cathode 6, the solidified metal halide does not accumulate at the base of the cathode 6. Therefore, when turned on again, the anode 5 and the cathode 6
Is discharged between the anode 5 and the solidified metal halide accumulated at the base of the cathode 6 and the anode 5 are prevented from being generated. Therefore, the discharge state is stable even immediately after lighting, and the inner wall of the airtight container 2 on the cathode 6 side is prevented from being locally heated due to the occurrence of the root discharge. As a result, a crack is prevented from being formed on the cathode 6 side of the airtight container 2.

As a result, the durability of the lamp device 13 is improved.
Will be replaced less frequently.

In the airtight container 2, per arc length,
1.0 × 10 to ⁷ mol / mm to 1.0 × 10 to ⁶ mol / mm
Metal halide is enclosed. As a result, the amount of light emitted from the discharge lamp 1 increases, and the lamp device 13
, The brightness increases, and the image projected on the screen 22 becomes clearer in the liquid crystal projector 18.

When the lighting circuit 19 converts an AC current into a DC current, the ripple frequency “f” is set so that f <610 / d. Therefore, flickering of the discharge lamp 1 during lighting is eliminated, the brightness is stabilized in the lamp device 13, and the flickering of the projected image can be prevented in the liquid crystal projector 18.

[0024]

According to the discharge lamp of the first aspect of the present invention, the metal halide in the airtight container which has evaporated at the time of lighting is solidified at the time of turning off, and the temperature of the solidification of the metal halide is low at the time of lighting. Although progressing quickly on the cathode side, a metal halide solidified at the base of the cathode is formed because a projection protruding toward the anode side is formed around the part where the cathode penetrates on the inner peripheral surface of the airtight container, Can be prevented from accumulating in the airtight container.Therefore, it is possible to prevent the occurrence of a base discharge at the time of relighting, and the base wall of the airtight container is locally heated to a high temperature due to the base discharge, and the airtight container is cracked. Can be prevented.

According to the lamp device of the second aspect of the present invention, since the discharge lamp of the first aspect of the present invention is used, it is possible to prevent the occurrence of a base discharge at the time of lighting, and the inner wall on the cathode side of the hermetic container by the base discharge. However, it is possible to prevent the airtight container from cracking due to high temperature locally, and to improve the durability.

According to the liquid crystal projector of the third aspect of the present invention, since the lamp device of the second aspect of the present invention is used, a root discharge can be prevented from occurring at the time of lighting, and the inner wall on the cathode side of the hermetic container is caused by the root discharge. However, it is possible to prevent the airtight container from cracking due to high temperature locally, and it is possible to reduce the frequency of replacement of the lamp device.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing a lamp device according to an embodiment of the present invention.

FIG. 2 is an enlarged longitudinal side view showing the discharge lamp device.

FIG. 3 is a vertical sectional side view showing a schematic structure of a liquid crystal projector.

[Explanation of symbols]

 1: Discharge lamp 2: Airtight container 5: Anode 6: Cathode 8: Projection 13: Lamp device 14: Reflector 20: Liquid crystal display panel 21: Liquid crystal drive device 22: Projected surface 23: Optical system 24: Housing

Continuation of the front page (72) Inventor Tsuyoshi Kinoshita 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo Inside Toshiba Lighting & Technology Corporation (72) Inventor Mamoru Furuya 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo Toshiba Lighting & Technology Corporation In company

Claims (3)

[Claims] An airtight container formed of quartz glass; a discharge medium containing at least a metal halide sealed in the airtight container; an anode opposed to the airtight container at a predetermined interval; A discharge lamp, comprising: a cathode; and a projection formed on an inner peripheral surface of the hermetic container and protruding toward the anode around a portion through which the cathode penetrates. 2. A lamp device, comprising: the discharge lamp according to claim 1; and a reflecting mirror that reflects light from the discharge lamp in a predetermined direction. 3. The lamp device according to claim 2, a liquid crystal display panel irradiated with light from the lamp device, a liquid crystal driving device for driving the liquid crystal display panel, and a light passing through the liquid crystal display panel. An optical system for projecting onto the surface to be projected;
A liquid crystal projector, comprising: a housing accommodating at least the lamp device, the liquid crystal display panel, and the optical system.