JP2002075269A - Discharge lamp and image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp with heightened illumination intensity maintenance rate. SOLUTION: From among a plurality of peaks of OH between wavelengths of 305 nm to 310 nm including the wavelength of 306.4 nm at time of glow discharge by supplying an electrode 23 of a high-pressure discharge lamp 5 with 2.5 mA current at glow voltage of 20 V, a spectrum of the highest wavelength of 305 nm is to be A, and a spectrum of the wavelength 404.7 nm of Hg is to be B. By sealing in OH so that A/B is larger than 0.35, tungsten spattered from the electrode 23 makes a compound with oxygen and halogen inside the luminous tube 21, with which, an oxy-halogen cycle returning to the electrode 23 is activated, to bring forth a high maintenance rate of illumination intensity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp and an image projection apparatus which improve an illuminance maintenance factor.

[0002]

2. Description of the Related Art In recent years, floodlights and image display devices have become widespread, and high-pressure discharge lamps are often used as light sources.

Further, a short arc type discharge lamp which is close to a point light source and easy to control the alignment is used in the liquid crystal projector.

[0004] Since liquid crystal projectors are often carried around, reduction in size and weight is desired. In addition, as the size of the liquid crystal panel is reduced along with the reduction in size and the size thereof, the diagonal is about 3.3 cm. In order to obtain a luminous efficiency, miniaturization of the discharge lamp is required.

To reduce the size of the discharge lamp, it is conceivable to shorten the arc length of the discharge lamp. However, if the arc length of the discharge lamp is simply shortened, the lamp voltage decreases.
In order to obtain the same brightness, the lamp current increases. When the lamp current increases, the size of the lighting device increases, and the size cannot be reduced as a whole.

Therefore, as a discharge lamp for shortening the arc length without lowering the lamp voltage, for example, Japanese Unexamined Patent Publication No.
A configuration described in Japanese Patent No. 52830 is known. The discharge lamp described in JP-A-6-52830 raises the arc impedance by increasing the pressure during operation, increases the lamp voltage, and suppresses the increase in the lamp current.

[0007]

However, there is a problem that it is not possible to increase the illuminance maintenance rate for a long period of time by simply increasing the pressure during lighting as in the discharge lamp described in Japanese Patent Application Laid-Open No. 6-52830. ing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a discharge lamp and an image projection apparatus having a high illuminance maintenance ratio.

[0009]

According to a first aspect of the present invention, there is provided a discharge lamp including: a light emitting tube having a light-transmitting container; a pair of electrodes provided to form a discharge path in the light emitting tube; 10 ^-3 μm inside the arc tube so that the pressure is 10 MPa or more
a discharge medium containing mercury, a rare gas, and a halogen contained at a rate of at least ol / mm ³ , and a spectrum of OH when glow discharge is performed by supplying a current of 2.5 mA between the electrodes. Is A, and when Hg spectrum is B, 0.35 ≦ A / B ≦ 1.50.
The metal substance scattered from the electrode forms a compound of oxygen and halogen in the arc tube and uses the oxyhalogen cycle that returns to the electrode to extend the life, and the OH spectrum uses oxygen as oxygen. However, since none of O ² appears in the spectrum, OH is used.
When the spectrum of H is A and the spectrum of Hg is B, 0.35 ≦ A / B ≦ 1.50 is satisfied by 0.3
In the case of 5> A / B, the oxyhalogen cycle was not sufficiently activated to improve the illuminance maintenance ratio, and A / B> 1.5.
This is because if the value is 0, the illuminance maintenance rate is improved, and a problem may occur. The lighting pressure is 10MPa
As described above, by improving the lighting pressure, the impedance of the arc is increased, the lamp voltage is increased, and an increase in the lamp current is suppressed.

According to a second aspect of the present invention, in the discharge lamp of the first aspect, the spectrum of OH has a wavelength of 3
Of a plurality of peaks including a wavelength of 306.4 nm between 05 nm and 310 nm, the highest spectrum is used.
The spectrum of g uses a spectrum at a wavelength of 404.7 nm, and by using these spectra, an optimum state can be obtained.

According to a third aspect of the present invention, there is provided an image projection apparatus according to the first aspect.
Or the discharge lamp according to 2 above; and an image projection apparatus main body accommodating the discharge lamp.

The image projection apparatus is, for example, a projector having display means or projection means of a transmission type or a reflection type such as a liquid crystal panel, or a projection television having a screen in addition to the display means and projection means. is there.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image projection apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a high-pressure discharge lamp, and FIG.
Is an explanatory view showing a liquid crystal projector, FIG. 3 is a sectional view showing electrodes, and FIG. 4 is a block diagram showing a measuring device.

As shown in FIG. 2, reference numeral 1 denotes a liquid crystal projector as an image projection device. The liquid crystal projector 1 has a main body 2 as a main body of the image projection device. Is formed.

A light source 4 is provided in the main body 2, and the light source 4 is formed by a high-pressure discharge lamp 5 and a reflector 6 as a reflection means optically opposed to the high-pressure discharge lamp 5. And, ahead of the irradiation direction of the light source 4,
A liquid crystal panel 7 as display means is provided, and a projection lens 8 as projection means is provided corresponding to the projection opening 3 in front of the liquid crystal panel 7.

Further, a lighting circuit 11 is provided in the high-pressure discharge lamp 5.
The liquid crystal panel 7 is connected to a liquid crystal drive circuit 12, and the lighting circuit 11 and the liquid crystal drive circuit 12 are connected to a commercial AC power supply e.
It is connected to the. The lighting circuit 11 may be either a circuit for lighting the high-pressure discharge lamp 5 with DC or a circuit for lighting with AC.

A screen is provided in front of the projection opening 3.
15 are arranged.

As shown in FIG. 1, the high-pressure discharge lamp 5 has an arc tube 21 made of quartz, and a spherical portion 22 forming a discharge space is formed at an intermediate portion of the arc tube 21 in the longitudinal direction. Have been. The spherical portion 22 contains mercury (Hg), bromine (Br), an alkali metal containing at least lithium (Li), and argon (Ar) gas at 10 ⁻³ μmol / m 2.
encapsulated in m ³ or more sealing pressure, mercury lights pressure 10MP
It is sealed so that the lamp voltage becomes 80 V or more at a or more. In addition, bromine and lithium are enclosed in a pellet of HgBr ² -Li along with the sphere 22. Further, in order to increase the oxygen content in the sphere portion 22 more than usual, exhaust is performed at about 10 ⁻² Pa lower than the normal exhaust level, and oxygen is left in the sphere portion 22.

Further, electrodes 23, 23 are disposed on the spherical portion 22 so as to face each other with a gap of 1.3 mm. As shown in FIG. 3, the electrode 23 is made of triated tungsten or high-purity tungsten and has a shaft diameter of 0.45 m.
The shaft 24 has a length of 9.0 mm and a length of 9.0 mm. A first coil 25 is formed at the tip of the shaft 24. The first coil portion 25 is made of high-purity tungsten having a diameter of 0.2 mm at a position 0.2 mm from the tip as a first pitch of 10 mm.
The first pitch is wound 7 turns as a second pitch on the first pitch, and the overall length is 2.0 m.
m. The second coil 26 has a diameter of 0.07.
5 mm of high-purity tungsten is 5.0
It is wound 20 turns over the length of mm.

Further, the electrode 23 has a thickness of 0.020 mm,
Molybdenum (Mo) foil 31 with a width of 1.5 mm and a length of 17 mm
The arc tube 21 is hermetically sealed at the molybdenum foil 31 portion. A base 32 is attached to one molybdenum foil 31, a wire 33 is attached to the other molybdenum foil 31, and a lead wire 34 is attached to the wire 33.

Next, the operation of the liquid crystal projector 1 will be described.

First, the high-pressure discharge lamp 5 of the light source 4 is turned on by the lighting circuit 11, so that the light from the high-pressure discharge lamp 5 is irradiated directly or reflected by the reflector 6 toward the liquid crystal panel 7. The liquid crystal panel 7 is a liquid crystal drive circuit
The display changes at 12, the light from the light source 4 is transmitted and projected by the projection lens 8 to display an image on the screen 15.

Here, experimental results on the relationship between the spectrum and the illuminance maintenance ratio will be described.

First, the measuring device is configured as shown in FIG. 4 and has a lighting box 41 in which the high-pressure discharge lamp 5 is housed.
have. The lighting box 41 is connected via a slit plate 42 to a spectroscope (product: Nikon G-250) 43 for separating the glow discharge of the high-pressure discharge lamp 5. The spectroscope 43 has a monochromator auto scanner (product: Nikon AS-C101) 44.
Is connected. Further, the spectroscope 43 has a photomultiplier (photomultiplier tube product: HA) that receives light of an arbitrary wavelength extracted from the spectroscope 43 via the slit plate 42.
MAMATSUR1509) 45, a photometer (product: Nikon SP-105) 46 which converts light received by the photomultiplier 45 into an electric quantity and detects a spectrum quantity of each wavelength.
A recorder 48 for recording the amount of spectrum detected by the photometer 46 is connected.

Then, as shown in FIG.
A plurality of peaks including a wavelength of 306.4 nm between a wavelength of 305 nm and a wavelength of 310 nm of OH when a current of 2.5 mA is supplied to the electrode 23 at a glow voltage of 20 V and glow discharge is performed by scanning a spectrum amount in seconds. Of these, the spectrum with the highest wavelength of 305 nm is A, and the Hg wavelength 4
A / B when the spectrum at 44.7 nm is B,
The relationship with the illuminance maintenance rate after 100 hours, 300 hours, and 500 hours is considered.

The reason for using the spectrum of OH is to use OH because oxygen does not appear in the spectrum of either O or O ² .

In the experiment, six samples were used. Sample 1 shown in Table 1 had an A / B of 1.50, sample 2 had an A / B of 1.20, and sample 3 had an A / B of 0.68. Sample 4 had an A / B of 0.39, sample 5 had an A / B of 0.35, and sample 6 had an A / B without oxygen.
/ B is 0.04 and a lamp power of 100 W is input.

[0029]

[Table 1] As shown in Table 1, according to the experiment, the illuminance maintenance ratio of Sample 2, Sample 3 and Sample 4 was 90% or more even after 500 hours had elapsed. White turbidity was generated on the wall surface, and the illuminance maintenance ratio was reduced due to the light shielding effect of the white turbidity.

From this fact, by encapsulating OH so that A / B is greater than 0.35, tungsten scattered from the electrode 23 forms a compound of oxygen and halogen in the arc tube 21 and It is considered that the oxyhalogen cycle which returns to the above is activated, and a high illuminance maintenance ratio is obtained.

On the other hand, in the sample 1, a phenomenon occurs in which the illuminance maintenance ratio increases even after a lapse of time, and there is a possibility of causing a problem. Therefore, it is considered that the upper limit should be set to 1.50 or less.

[0032]

According to the discharge lamp of the first aspect, when the current of 2.5 mA is supplied to the electrode to perform glow discharge and the spectrum of OH is A and the spectrum of Hg is B, .35 ≦ A / B ≦ 1.50, the metal substance scattered from the electrode forms a compound of oxygen and halogen in the arc tube, and the oxyhalogen cycle which returns to the electrode again is used to improve the illuminance maintenance rate and increase Life can be extended. Further, since the lighting pressure is 10 MPa or more, by improving the lighting pressure, the arc impedance can be increased, the lamp voltage can be increased, and an increase in the lamp current can be suppressed.

According to the discharge lamp of the second aspect, in addition to the effect of the first aspect, the spectrum of OH has a wavelength of 30.
Of a plurality of peaks including a wavelength of 306.4 nm between 5 nm and 310 nm, the highest spectrum is used and Hg is used.
Since the spectrum of the wavelength of 404.7 nm is used, the optimum state can be obtained.

According to the image projection apparatus of the third aspect, since the discharge lamp of the first or second aspect is used, each effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view showing one embodiment of a high-pressure discharge lamp of the present invention.

FIG. 2 is an explanatory view showing the same liquid crystal projector.

FIG. 3 is a cross-sectional view showing the same electrode.

FIG. 4 is a block diagram showing a measuring device according to the first embodiment;

FIG. 5 is a graph showing a spectrum according to the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal projector as an image projection apparatus 2 Main body as an image projection apparatus main body 5 High-pressure discharge lamp 21 Arc tube 23 Electrode

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ichiro Tanaka 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo F-term in Toshiba Lighting & Technology Corporation (reference) 5C015 JJ01 QQ34 RR01 RR05 5C039 HH02 HH05

Claims (3)

[Claims] An arc tube provided with a light-transmitting container; a pair of electrodes provided to face each other to form a discharge path in the arc tube; and a lamp inside the arc tube so as to have a lighting pressure of 10 MPa or more.
A discharge medium containing mercury, a rare gas, and a halogen contained at a concentration of 0 ^-3 μmol / mm ³ or more, wherein a 2.5 mA current is supplied between the electrodes to perform glow discharge. Let the spectrum of OH be A and the spectrum of Hg be B
Where 0.35 ≦ A / B ≦ 1.50. 2. The spectrum of OH has a wavelength of 305 nm or more.
2. The discharge lamp according to claim 1, wherein the highest spectrum among a plurality of peaks including a wavelength of 306.4 nm between 310 nm is used, and the Hg spectrum uses a spectrum with a wavelength of 404.7 nm. 3. 3. A discharge lamp according to claim 1, wherein:
An image projection device main body containing the discharge lamp.