JPH065259A - Metallic vapor discharge tube - Google Patents

Abstract

PURPOSE:To improve the heat accumulating property of a metallic vapor discharge tube without reducing the luminance of a radiating surface by applying a heat insulating film to an ineffective utilization area prescribed in a specific condition, in a metallic vapor discharge tube main body. CONSTITUTION:A metallic vapor discharge tube 10 is composed of a metallic vapor discharge tube main body 1 which is formed of a glass or the like, and a pair of opposite electrodes 2 provided oppositely in the main body 1, a starter gas, Hg, and a metallic haloid compound are sealed in the main body 1, and the axes of the opposite electrodes 2 are arranged parallel to the radiation surface S by combining with a reflector R. A heat insulating film (ZrO2, etc.) is applied to the ineffective utilization area (cross hatching part) of the main body 1 prescribed in the formula 0<theta1<=tan<-1> (2.-L/Sy) (where X-axis is made in the extending direction of the opposite electrodes, Y-axis is made in the direction extending orthogonal to the X-axis passing the middle point of the opposite electrodes, and parallel to the radiation surface S, theta1 is the angle made by the Y-axis and the line combining the middle point of the opposite electrodes and the end in the Y-axis direction of the radiation surface S, and Sy is the length of the radiation surface S along the Y-axis direction).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vapor discharge tube, and more particularly to a metal vapor discharge tube having a heat insulating film formed on its outer peripheral surface.

[0002]

2. Description of the Related Art A general metal vapor discharge tube (metal halide lamp) is a main body of a metal vapor discharge tube in which a starting gas such as a rare gas (mainly Ar) and Hg and a halide of various metals (mainly iodide) are enclosed. And a counter electrode and the like which are arranged to face each other in the metal vapor discharge tube body.
Such a metal vapor discharge tube has the following excellent characteristics as compared with a halogen lamp which has been conventionally used as a light source lamp. That is, the halogen lamp is 200
The coil breaks and turns off after about 300 hours of use, whereas the metal vapor discharge tube has a light quantity of 5 which is the life of the product.
It can be used for about 600 to 700 hours until it drops to 0%. In terms of luminous efficiency, a halogen lamp has a luminous efficiency of about 20 lumens / watt, whereas a metal vapor discharge tube has a luminous efficiency of about 80 lumens / watt, and the metallic vapor discharge tube has a luminous efficiency about four times that of a halogen lamp.

Since the metal vapor discharge tube has such excellent characteristics, it is used as a light source for a projection type liquid crystal display such as an overhead projector (OHP) or a liquid crystal projector (LCP) instead of a halogen lamp. Has increased.

However, the inner peripheral surface of the metal vapor discharge tube body made of glass is contaminated in the metal vapor discharge tube by the sputtering of electrodes or the reaction between the enclosed metal halogen compound and the glass (devitrification of quartz glass). However, there is a problem that the light transmittance of the glass constituting the metal vapor discharge tube main body gradually deteriorates, and eventually the product life is extended. By increasing the inner peripheral surface area of the metal vapor discharge tube main body, the density of contamination on the inner peripheral surface of the metal vapor discharge tube main body due to sputtering or the like can be diluted, so that the inner peripheral area of the metal vapor discharge tube main body is increased. As a result, the life of the metal vapor discharge tube can be extended.

In the case of a metal vapor discharge tube, there is a close relationship between vaporization of metal (luminous efficiency) and temperature (heat quantity) in the metal vapor discharge tube. That is, if the temperature inside the metal vapor discharge tube body is high, the vaporization of the metal is promoted and the luminous efficiency of the metal vapor discharge tube is increased, while if the temperature is low, the vaporization of the metal is suppressed and the luminous efficiency is increased. Will fall. Therefore, if an attempt is made to increase the life of the metal vapor discharge tube by increasing the inner peripheral area of the metal vapor discharge tube body (that is, increasing the size of the metal vapor discharge tube body) as described above, There is a problem that the heat radiation from the metal vapor discharge tube increases, the temperature inside the metal vapor discharge tube body decreases, and the luminous efficiency decreases.

As a countermeasure against this, the main body of the metal vapor discharge tube has a double tube structure consisting of an inner tube and an outer tube, and a metal halogen compound or the like is enclosed inside the inner tube to provide a space between the inner tube and the outer tube. Has proposed a metal vapor discharge tube having a structure in which a rare gas of vacuum or low pressure is sealed. Since the metal vapor discharge tube of this double tube structure suppresses heat dissipation from the inner tube, even if the volume (surface area) of the inner tube is increased, the same luminous efficiency as that of the single tube can be obtained, and the surface area The increase in the life of the metal vapor discharge tube has been achieved.

[0007]

However, the metal vapor discharge tube of this double tube structure has a problem that the production process is complicated and the production cost rises, and the metal vapor discharge tube as a whole has an outer tube. However, there has been a problem in that the volume is increased and the compactness is impaired.

Therefore, there has been a demand for a metal vapor discharge tube capable of achieving a longer life and a longer life while maintaining a high luminous efficiency by another method.

Further, when the irradiation surface such as a liquid crystal surface is illuminated by the metal vapor discharge tube, the light emitted from the metal vapor discharge tube is 100%.
Percentage does not illuminate the illuminated surface. That is, the light emitted from the predetermined portion of the metal vapor discharge tube does not reach the irradiation surface. The surface portion of the metal vapor discharge tube where the light that does not reach the irradiation surface is generated is defined as an ineffective utilization area. There has been a demand for effective utilization of the light from this non-effective utilization region by some method.

Further, since the metal vapor discharge tube 30 requires a high-voltage starting voltage (10 KV or more) at the initial stage of lighting, the metal vapor discharge tube main body 31 having a pair of opposing electrodes 32 inside is provided on the outer periphery of the metal vapor discharge tube body 31. It has been conventionally performed to wind the trigger wire 33 and use the creeping discharge to lower the starting voltage (FIG. 7). In this type of metal vapor discharge tube 30, although the starting voltage can be lowered, the work is troublesome because the trigger wire 33 is wound during manufacturing, and it is difficult to improve the manufacturing efficiency.

The present invention has been made in view of the above problems, and the luminous efficiency does not decrease even when the life of the metal vapor discharge tube is increased by increasing the volume of the metal vapor discharge tube main body. Moreover, it is an object of the present invention to provide a metal vapor discharge tube capable of effectively utilizing the light emitted from the non-effective utilization region of the surface of the metal vapor discharge tube body.

Another object of the present invention is to provide a metal vapor discharge tube whose starting voltage can be lowered without winding a trigger wire.

[0013]

In order to achieve the above object, a metal vapor discharge tube of the present invention is disposed so as to face a metal vapor discharge tube body and inside the metal vapor discharge tube body, and each is connected to a power source. And a pair of counter electrodes.
A starting gas, Hg, and a metal halide are enclosed in the metal vapor discharge tube body. The metal vapor discharge tube is arranged such that the axis of the counter electrode is parallel to the irradiation surface. The metal vapor discharge tube body is coated with a heat insulating film in the first non-effective utilization region defined by the formula 0 <θ ₁ ≦ tan ⁻¹ (2 · L / Sy). Here, the X-axis is the direction in which the axis of the counter electrode extends, and the Y-axis is the direction that extends through the midpoint of the counter electrode and is orthogonal to the X-axis and parallel to the irradiation surface. , Θ ₁
Is an angle formed by the Y axis and a line connecting the intermediate point of the counter electrode and the end of the irradiation surface in the Y axis direction, and L is
Let Sy be the distance between the X-axis and the irradiation surface, and let Sy be the length of the irradiation surface along the Y-axis direction.

Here, the first non-effective utilization region is preferably -La / 2≤X≤ of the metal vapor discharge tube body.
It is provided in the area defined by La / 2. Here, X is the position of the metal vapor discharge tube on the X axis,
Let La be the distance between the opposing electrodes.

The heat insulating film further comprises: 0 <θ ₂ (δ _x ) ≦ tan ⁻¹ [2 · (L · cos δ of the metal vapor discharge tube body.
_x / (Sx−La))] is preferably provided in the second non-effective region. Where 0 ≦ δ _x
≦ ± tan ⁻¹ [Sy / (Sx−La)]. Also,
_Let θ ₂ (δ _x ) be the angle formed by the line connecting the X-axis and the tip of one of the electrodes and the end of the irradiation surface in the X-axis direction, and let δ _x be
Let Sx be the length of the irradiation surface in the X-axis direction, where Sx is the angle made from the X-axis toward the Y-axis with the electrode tip as the fulcrum. In this case, it is preferable that the heat insulating film contains metal or carbon and has conductivity.

[0016]

According to the metal vapor discharge tube of the present invention having the above-mentioned structure, since the heat insulating film for reflecting infrared rays is applied to the non-effective utilization region of the metal vapor discharge tube body, the metal vapor discharge tube main body is not covered with the heat insulating film. Infrared rays emitted from the effective use area are reflected in the metal vapor discharge tube body, improving the heat storage property of the metal vapor discharge tube body, compared to a metal vapor discharge tube of the same size without a heat insulating film applied. High luminous efficiency can be obtained. When a conductive material is mixed in the coating film,
By generating a creeping discharge along the coating film, the starting voltage can be lowered.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail below with reference to the drawings. 1 to 3 show a state in which a metal vapor discharge tube 10 according to the first embodiment of the present invention is combined with a reflecting mirror (spherical mirror) R and is arranged to face an irradiation surface S such as a liquid crystal surface. The metal vapor discharge tube 10 has basically the same structure as a conventional metal vapor discharge tube, and is opposed to the metal vapor discharge tube body 1 formed of a material such as glass and the inside of the metal vapor discharge tube body 1. It is composed of a pair of opposed electrodes 2 and 2 arranged. The pair of counter electrodes 2 and 2 are connected to external electrodes by electric wires (not shown). In addition, a starting gas such as a rare gas (mainly Ar) and H
g, halides of various metals (mainly iodides), etc. are enclosed.

FIG. 1 is a plan view of a state in which the metal vapor discharge tube 10 is combined with a concave mirror (spherical mirror) R and is opposed to an irradiation surface S such as a liquid crystal surface as viewed from above (the side of the reflecting mirror R). Figure 2
FIG. 2 is a sectional view taken along line II-II of FIG. 1 taken along the line II-II, and FIG. 3 is a sectional view taken along line III-III of FIG. 1.
It is a III cross-section arrow line view. The portion indicated by cross-hatching in the metal vapor discharge tube body 1 is the above-mentioned ineffective utilization area, and a heat insulating film is applied to this portion. This heat insulating film is composed of a metal oxide such as ZrO ₂ , TiO ₂ , and Al ₂ O ₃ and has a property of reflecting infrared rays.
For this reason, infrared rays generated by the metal vapor discharge tube are reflected at the heat insulating film portion, which contributes to the improvement of heat storage in the metal vapor discharge tube body.

Such a heat insulating film is applied to the sealing root of the electrode, and various metal components sealed in the metal vapor discharge tube main body near the electrode sealing root which is the low temperature portion in the metal vapor discharge tube main body. A metal vapor discharge tube 40 has been proposed in the past, which is intended to prevent the precipitation of metal (FIGS. 8 to 1).
0). Since the electrode sealing root part corresponds to the non-effective use area defined by the following mathematical formulas 1 and 2, even if a heat insulating film is applied to this part, the illuminance of the irradiation surface does not decrease. Is applied.
In this specification, the midpoint between the two opposing electrodes of the metal vapor discharge tube is the origin, and the X axis is the direction in which the axis of the opposing electrode extends. In addition, the Y axis extends in a direction that passes through the midpoint of the counter electrode and is orthogonal to the X axis, and is parallel to the irradiation surface. In addition, the Z axis passes through the midpoint of the counter electrode,
The X-axis and the Y-axis are axes that are orthogonal to the XY plane.

[0020]

## EQU1 ## 0 <θ ₂ (δ _x ) ≦ tan ⁻¹ [2 · (L · co
sδ _x / (Sx-La))] Here, δ _x takes the following range.

## EQU2 ## 0 ≦ δ _x ≦ ± tan ⁻¹ [Sy / (Sx−L
a)]

Θ ₂ (δ _x ) is an angle formed by a line connecting an axis (X axis) connecting both counter electrodes 2 and 2 and a tip end of one electrode and an end of the irradiation surface in the X axis direction. Then, its value changes according to the value of δ _x (FIG. 9). L is a metal vapor discharge tube 10
Between the central axis (X axis) of the and the irradiation surface S (FIGS. 8 and 9)
Δ _x is the angle (FIG. 8) formed from the X axis to the Y axis with the electrode tip as a fulcrum, Sx is the length of the irradiation surface in the X axis direction (FIG. 9), and La is the distance between the electrodes. The distance (Fig. 9) is Sy
Represents the length of the irradiation surface in the Y-axis direction (FIG. 10).

A metal vapor discharge tube 1 shown in FIGS. 1 to 3.
In 0, the heat insulating film having the property of reflecting infrared rays is applied to the non-effective utilization region represented by the formulas 3 and 4, which will be described later, in addition to the non-effective utilization region represented by the formulas 1 and 2. Therefore, the heat storage property of the metal vapor discharge tube body is improved as compared with the conventional metal vapor discharge tube (FIGS. 8 to 10) in which the heat insulating film is applied only to the electrode sealing root. Therefore, high luminous efficiency can be obtained as compared with a metal vapor discharge tube having the same size and the same electrical characteristics and having no heat insulating film applied.

[0023]

Equation 3] ^{_{0 <θ 1 ≦ tan -1 (}} 2 · L / Sy) where regions of Equation 3 is defined within a range shown in Equation 4 below.

## EQU00004 ## −La / 2 ≦ X ≦ + La / 2

Here, θ ₁ is an angle (FIG. 3) formed by the Y axis and a line connecting the center of the metal vapor discharge tube and the end of the irradiation surface in the Y direction, and L is the metal vapor discharge tube 10. Central axis (X axis)
Between the irradiation surface S and the irradiation surface S (FIGS. 2 and 3), Sy is the length of the irradiation surface in the Y-axis direction (FIG. 3), and X is the origin (counter electrodes 2, 2) of the metal vapor discharge tube body. And the La is the distance between both electrodes (FIG. 2).

In the metal vapor discharge tube 10 of the first embodiment, a heat insulating film is provided in both the non-effective use regions defined by the formulas 1 and 2 and the non-effective use regions defined by the formulas 3 and 4. It has been applied. However, the heat insulating film may be applied only to the non-effective use region defined by the formula 3 or the formulas 3 and 4. Particularly, in the metal vapor discharge tube of the type in which the distance between the electrode sealing root portion and the electrode tip portion is shortened and the temperature gradient in the metal vapor discharge tube is reduced, the non-effective utilization region defined by the above mathematical formula 3 is set. The heat storage property of the metal vapor discharge tube body can be enhanced by applying only the heat insulating film. This makes it possible to suppress a decrease in luminous efficiency when the inside of the metal vapor discharge tube is enlarged.

Next, the results of a comparative experiment between the metal vapor discharge tube of the first embodiment (the present invention) and the conventional metal vapor discharge tube (comparative example) will be shown.

The metal vapor discharge tube of the present application and the metal vapor discharge tube of the comparative example have the same electrical characteristics and optical characteristics shown below. Electrical characteristics Discharge tube voltage 95 ± 10V Discharge tube current 6.05 ± 0.5A A constant power source is used so that the discharge tube power becomes 575W. Optical characteristics Luminous efficiency 80 ± 5lm / W

In the present application, the pipe diameter was 25 mm and the pipe length was 28 mm, and in the comparative example, the pipe diameter was 22 mm and the pipe length was 25 mm. The thickness of the metal vapor discharge tube body was set to 2.3 ± 0.2 mm in both the present application and the comparative example. Further, although the heat insulating film is not applied to the comparative example, the metal vapor discharge tube of the present embodiment (the present application) is covered with the heat insulating film at the portions represented by the above formulas 1 to 3.

A metal vapor discharge tube of the present embodiment and a metal vapor discharge tube of a comparative example having the above-mentioned constitutions were prepared, and each was used as a light source of an OHP (overhead projector) having a constitution as shown in FIG. The change over time in the central illuminance of the screen, which is the illuminated surface, was measured. The measurement result is shown in FIG.

It can be seen that the life of the comparative example (conventional example) reaches about 800 hours, while the life of the comparative example (conventional example) reaches about 50 hours of illuminance, whereas the working example of the present invention reaches the life of about 1200 hours. This is a result of increasing the size of the metal vapor discharge tube body of the present application (increasing the inner peripheral area of the metal vapor discharge tube body) as described above, but in the case of the present application example, the heat insulating film was not applied. Therefore, the same luminous efficiency as that of a small-sized (comparative example) metal vapor discharge tube is obtained.

No unevenness of illuminance on the screen due to the application of the heat insulating film to the non-effective utilization area defined by the formulas 1 to 3 was found.

In an optical system such as OHP, a condenser lens may be inserted between the metal vapor discharge tube which is the light source and the irradiation surface. Although the present invention is applicable to such an optical system, it is necessary to consider various conditions such as the curvature of the lens when calculating the non-effective use area.

Next, the metal vapor discharge tube 20 of the second embodiment of the present invention will be described. The basic structure of the metal vapor discharge tube 20 of the second embodiment is the metal vapor discharge tube 1 of the first embodiment.
It is the same as 0 (FIGS. 6, 7, and 8). That is, a pair of counter electrodes 22, 22 are arranged in a metal vapor discharge tube body 21 formed of glass or the like, and a starting gas such as a rare gas (mainly Ar) and Hg, halides of various metals (mainly iodides), etc. are enclosed. Further, a heat insulating film is applied to the non-effective use region defined by the above-mentioned formulas 1 to 4 represented by the cross-hatched portion in FIG. Since the heat insulating film of this embodiment is mixed with a conductive material, the heat insulating film has a function as a conductor. Specific examples of the conductive material mixed in the heat insulating film include carbon, iron, nickel, tin, lead, gold, silver, titanium, vanadium, chromium, manganese, cobalt, copper, and
Zinc, gallium, germanium, molybdenum, niobium,
Zirconium, palladium, cadmium, indium,
Examples thereof include metals such as tantalum, tungsten, rhenium, osmium, iridium, platinum, and alloys thereof.

In the metal vapor discharge tube of this embodiment, one end of the lead wire 23 is connected to a heat insulating film mixed with a conductive material. The other end of the lead wire 23 is connected to a power source (FIG. 6). In the conventional metal vapor discharge tubes shown in FIGS. 8 to 10, the heat insulating film is provided only in the two regions of the electrode sealing root of the counter electrode, and the two regions are in contact with each other.
Not linked. However, in the present invention, the heat insulating film is formed not only in the two regions (regions defined by the formulas 1 and 2) but also in the regions defined by the formulas 3 and 4. Here, as shown in FIGS. 1 to 3 and 6, the regions represented by the formulas 1 and 2 are in contact with and connected to the regions represented by the formulas 3 and 4. Therefore, in the case of the present invention, the heat insulating film is provided in a wide single region extending to the electrode sealing roots of both counter electrodes. Therefore, when a conductive material is mixed in the coating film of the present invention, creeping discharge can be generated along the coating film, and the starting voltage can be lowered. That is, the conductive heat insulating film produces the same effect as the trigger wire 33 (FIG. 7) wound around the metal vapor discharge tube body, and can reduce the starting voltage of the metal vapor discharge tube. The starting voltage required at least 16 KV when the conductive heat insulating film was not applied, but when the conductive heat insulating film was applied to the same lamp as shown in FIG. 6, it was possible to reduce it to 11 KV. .

The present invention is not limited to the above embodiments, and various modifications and changes can be made according to the technical matters described in the claims.

[0036]

According to the present invention described in detail above, since the heat insulating film is applied to the non-effective utilization region of the surface of the metal vapor discharge tube main body, the metal vapor discharge tube of the metal vapor discharge tube is not deteriorated without reducing the illuminance. The heat storage property can be improved. As a result,
Even when the metal vapor discharge tube main body is enlarged to have a long life due to an increase in the inner peripheral area, the luminous efficiency does not decrease.

Further, when the heat insulating film is made to have conductivity, the starting voltage can be lowered without the complicated process of winding the trigger wire.

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which a metal vapor discharge tube according to a first embodiment of the present invention is combined with a reflecting mirror and is arranged to face an irradiation surface.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

FIG. 3 is a line III-I along the line III-III in FIG.
II cross-section arrow view.

FIG. 4 OH tested metal vapor discharge tube of the present invention
The schematic block diagram of P apparatus.

FIG. 5 is a graph showing changes in illuminance over time of the metal vapor discharge tube of the first embodiment of the present invention and the metal vapor discharge tube of the comparative example.

FIG. 6 is a schematic view of a metal vapor discharge tube according to a second embodiment of the present invention.

FIG. 7 is a schematic view of a conventional metal vapor discharge tube wound with a trigger wire.

FIG. 8 is a plan view showing a state in which a metal vapor discharge tube of a conventional example is combined with a reflecting mirror and is arranged to face an irradiation surface.

9 is a cross-sectional view taken along the line IX-IX of FIG. 8 taken along the line IX-IX.

10 is a cross-sectional view taken along the line X-X of FIG.

[Explanation of symbols]

 1 Metal Vapor Discharge Tube Body 2 Counter Electrode 10 Metal Vapor Discharge Tube S Irradiation Surface R Reflector

Claims (4)

[Claims] 1. A metal vapor discharge tube main body and a pair of counter electrodes which are arranged to face each other in the metal vapor discharge tube main body and are connected to a power source, respectively, and a starting gas, Hg, and metal are provided in the metal vapor discharge tube main body. Of the metal vapor discharge tube, wherein the halide of the metal vapor discharge tube is enclosed and the axis of the counter electrode is arranged in parallel to the irradiation surface, wherein 0 <θ ₁ ≦ tan ⁻¹ (2 · L / Sy) (where the X axis is the direction in which the axis of the counter electrode extends,
The Y-axis is defined as a direction that extends perpendicularly to the X-axis through the midpoint of the counter electrode and parallel to the irradiation surface.
₁ is the Y axis, the midpoint of the counter electrode and the Y of the irradiation surface.
The angle formed by the line connecting the ends in the axial direction is defined as L
Is a distance between the X-axis and the irradiation surface, and Sy is a length of the irradiation surface along the Y-axis direction). A metal vapor discharge tube characterized by having. 2. The first non-effective utilization region is −La / 2 ≦ X ≦ La / 2 of the metal vapor discharge tube body (where X is the metal vapor discharge tube on the X axis). 2. The metal vapor discharge tube according to claim 1, wherein the metal vapor discharge tube is provided in a region defined by a position and La is a distance between the opposing electrodes. 3. The heat insulation film further comprises: 0 <θ ₂ (δ _x ) ≦ tan ⁻¹ [2 · (L · cos δ _x / of the metal vapor discharge tube body.
(Sx−La))] (where 0 ≦ δ _x ≦ ± tan ⁻¹ [Sy / (Sx−L
a)] and θ ₂ (δ _x ) is an angle formed by the line connecting the X-axis and the tip of one of the electrodes and the end of the irradiation surface in the X-axis direction, and δ _x is a fulcrum at the tip of the electrode. And an angle formed from the X axis toward the Y axis, and Sx is a length of the irradiation surface in the X axis direction). The metal vapor discharge tube according to claim 2. 4. The metal vapor discharge tube according to claim 3, wherein the heat insulating film applied to the first and second ineffective regions contains metal or carbon and has conductivity.