JP2011222217A - Optical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical apparatus in which a short-arc mercury lamp can be actuated with no problem even when the optical apparatus is constituted so that the radiation light of the short-arc mercury lamp can be utilized with high efficiency.SOLUTION: At least one of a main reflector (20), a sub-reflector (30) or a translucent cover (40) has a UV light reflection function. The main reflector (20) consists of an ellipsoidal surface while the sub-reflector (30) consists of a spherical surface and they are arranged to face each other at the identical first focus position and surround a short arc mercury lamp (10) at the identical first focus position. An ultraviolet supplementary light source (70) is provided on a non-reflective surface in the light source device.

Description

  The present invention relates to an optical device. In particular, the present invention relates to an optical device used in a projector device.

Generally, there are a projector apparatus using a liquid crystal (LCD) panel and a DLP system.
There are 1 and 3 types of LCD panel systems. However, in either system, the radiated light from the light source is separated into three colors (RGB), and the LCD panel supports image information. In this method, the transmitted light is adjusted for transmission, and then the three colors transmitted through the panel are combined and projected onto the screen.
On the other hand, the method using DLP (registered trademark) is a spatial modulation element (also called a light modulation device, specifically a DMD element, etc.) through a rotary filter in which the RGB region is divided and formed from the light emitted from the light source. Etc.) in a time-sharing manner, and the DMD element reflects specific light to irradiate the screen. The DMD element has about 1 million small mirrors corresponding to each pixel, and the projection of light is controlled by controlling the direction of each small mirror.
Compared with the LCD system, the DLP system has a merit that the entire apparatus is small and simple because the optical system is simple and there is no need to use three LCD panels.

On the other hand, a short arc mercury lamp having a high vapor pressure is used as the light source of the projector apparatus. This is because by increasing the mercury vapor pressure, light in the visible wavelength range can be obtained with high output.
In addition, this short arc mercury lamp (hereinafter also simply referred to as “lamp”) is incorporated in a concave ellipsoidal reflecting mirror (substantially bowl-shaped) in order to brighten the image projected on the screen. This is because by using the concave reflecting mirror, the light emitted from the lamp in all directions can be focused and efficiently radiated on the screen of a limited area.

In recent years, projector devices and the like used for presentations are often used on the go, and there is a strong demand for smaller and lighter devices in the sense that they can be easily carried.
When the projector device is required to be miniaturized, naturally, the optical device (discharge lamp and concave reflecting mirror) incorporated in the projector device is also required to be miniaturized.
On the other hand, as a matter of course, the utilization efficiency of the radiated light of the short arc mercury lamp cannot be lowered even if the size and shape are restricted.

FIG. 11 shows a schematic structure of a conventionally proposed optical device. This is disclosed in Japanese Patent Application Laid-Open No. 11-64795. In addition to the main concave reflecting mirror 20, a sub-reflecting mirror 30 (auxiliary reflecting mirror) is provided, and light is directly incident on the concave reflecting mirror from the short arc mercury lamp. 55 and the light 56 radiated forward are combined with the light passing through the space between the electrodes of the light emitting unit 11 and returned to the concave reflecting mirror, and used as the outgoing light 57.
Furthermore, there is shown a technique constituted by a translucent cover 40 having a function of correcting an optical path of light emitted from a reflecting mirror.

As the projector housing is miniaturized, the integration density in the projector device increases and the cooling efficiency deteriorates. For this reason, the short arc mercury lamp provided to the projector is mainly provided near the casing wall of the projector for the purpose of improving the cooling efficiency. Further, stray light leaking from the optical device also becomes a problem, so that the optical device is surrounded by the light shielding mechanism, and it becomes difficult for light from the outside of the projector device to reach the short arc mercury lamp 10, resulting in a short circuit. Arc mercury lamp startability is a problem.

As a technique for improving startability, Japanese Patent Application Laid-Open No. 2002-100433 discloses an ultraviolet light start auxiliary light source. However, in the disclosed technique, since ultraviolet light is guided from the end face, only a very small part of the light emitted from the auxiliary light source reaches the light emitting part, and a sufficient effect cannot be confirmed. In particular, when the projector apparatus is not used for a long time, there is a problem that startability is difficult. Further, when the space is surrounded by the main reflecting mirror 20, the sub-reflecting mirror 30, and the translucent cover 40 and is provided at a position where the ultraviolet light directly reaches the light emitting unit 11, the main reflecting mirror 20 and the sub-reflecting mirror are provided. There was also a problem of obstructing the optical path of the light beam reflected by 30.

In particular, in the configuration of Japanese Patent Laid-Open No. 11-64795, the entire circumference is covered with a reflecting mirror and a translucent cover, which are optical components, and the arrival of light from outside the projector device, particularly ultraviolet light, is significantly reduced. Tend to.
JP-A-11-64795 JP 2002-100433

  The problem to be solved by the present invention is to provide an optical device that can start the short arc mercury lamp without any problem even when it is configured as an optical device that can use the radiation light of the short arc mercury lamp with high efficiency. .

In order to solve the above problems, the present invention provides a short arc mercury lamp (10) comprising a light emitting portion having a pair of electrodes and sealing portions provided at both ends of the light emitting portion, and the short arc mercury lamp (10 ) Arc direction and optical axis coincide with each other, and a main reflector (20) composed of a spheroidal surface arranged so as to surround the short arc mercury lamp (10) in a state where the first focal point is formed between the electrodes. ) And surrounding the opening of the main reflector (20), and the light directly radiated from the short arc mercury lamp (10) to the opening side of the main reflector (10) 20) a sub-reflecting mirror (30) composed of a spherical mirror for reflection again toward the head 20), and an opening provided in the sub-reflecting mirror (30) for passing light reflected from the main reflecting mirror (20); The translucent cover provided in the opening And (40), an optical system comprising an ultraviolet light reflecting function provided in at least one of the main reflecting mirror (20), the sub-reflecting mirror (30), and the translucent cover (40). In the apparatus, an ultraviolet light auxiliary light source (70, 71) is placed in a space surrounded by the main reflecting mirror (20), the sub-reflecting mirror (30), the translucent cover (40), and the non-reflecting surface. Is arranged.
In the present invention, the non-reflecting surface is a portion that connects the reflecting surface and the reflecting surface of the light source device, and does not contribute to the reflection of light, specifically, the sub-reflecting mirror (30) and the translucent surface. A portion connecting the surface of the protective cover (40) where the interference film is provided, a neck portion for holding the short arc mercury lamp (10) in the main reflector (20), and the main reflector This is a part connecting (20) and the sub-reflecting mirror (30), where the interference film is interrupted.

  Furthermore, the ultraviolet light auxiliary light source is arranged on the surface of the non-reflecting surface.

  Further, the opening diameter of the sub-reflecting mirror (30) on the side of the main reflecting mirror (20) is larger than or substantially equal to the opening diameter of the main reflecting mirror (20). It is characterized in that the maximum outer diameter of the sub-reflecting mirror (30) is smaller than the maximum outer diameter.

  Furthermore, a projector device including the optical device according to any one of claims 1 to 3 is provided.

According to the present invention, even if the present invention is an optical device that can use the light emitted from the short arc mercury lamp for light efficiency, the main reflecting mirror, the sub-reflecting mirror, and the translucent cover have an ultraviolet light reflecting function. By operating the ultraviolet light auxiliary light source in a space surrounded by the surface and the non-reflecting surface where the reflecting surface is not formed, the startability can be improved reliably even if the optical device is downsized.
Further, by providing the ultraviolet light auxiliary light source on the surface of the non-reflecting surface, the startability can be improved without obstructing the optical path.
Furthermore, by making the diameter of the sub-reflecting mirror smaller than the opening diameter of the main reflecting mirror, it is possible to secure a place for attaching the ultraviolet light auxiliary light source, and to improve startability without increasing the size of the optical device.

1 is a schematic cross-sectional view showing the overall structure of an optical device according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view for explaining the progress of light in an optical device according to the present invention. Schematic which shows the advancing condition of the ultraviolet light from the ultraviolet auxiliary light source of the optical apparatus which concerns on this invention. Schematic which shows the attachment structure of the ultraviolet light auxiliary light source in the optical apparatus which concerns on this invention. The schematic sectional drawing which shows other embodiment of the translucent cover of the optical apparatus which concerns on this invention. Other embodiment which has arrange | positioned the light emitting cover of the optical apparatus which concerns on this invention. 1 is a schematic sectional view showing an embodiment of an optical device according to the present invention. 1 is a schematic cross-sectional view showing an embodiment of a translucent cover of an optical device according to the present invention. The conceptual structure figure of the short arc mercury lamp light emission part of the optical apparatus which concerns on this invention. The schematic diagram of the electrode of the short arc mercury lamp of the optical apparatus which concerns on this invention. FIG. 6 is a schematic cross-sectional view showing a conventional optical device.

The optical device of the present invention includes a main reflecting mirror 20, a sub reflecting mirror 30 disposed on the opening side of the main reflecting mirror 20, and a translucent cover 40 disposed on the optical axis on the sub reflecting mirror 30 side. The auxiliary light source 50 is provided in a space surrounded by the sub-reflecting mirror and the translucent cover, and either one of the sub-reflecting mirror or the translucent cover is provided with an ultraviolet light reflecting function. Even when the ultraviolet light auxiliary light source 50 is installed at a position where the ultraviolet light from the ultraviolet light auxiliary light source 50 does not directly reach the light emitting part 11 of the short arc mercury lamp 10, the ultraviolet light is reflected by the reflection by the reflecting mirror or the translucent cover. The light emitting unit 11 can be reached.
That is, even if the ultraviolet light from the ultraviolet light auxiliary light source 50 cannot reach the short arc mercury lamp light emitting unit 11 directly, it can be used once or a plurality of times by the ultraviolet light reflecting function provided in the reflecting mirror or the translucent cover. The optical device is reflected and reaches the light emitting unit 11 of the short arc mercury lamp. A specific configuration will be described below with reference to the drawings.

FIG. 1 shows an overall external view of an optical apparatus according to the present invention.
The optical device includes a short arc mercury lamp 10, a main reflecting mirror 20, and a sub-reflecting mirror 30. The main reflector 20 is arranged so as to surround the short arc mercury lamp 10, and the arc direction of the short arc mercury lamp 10, that is, the direction connecting the tips of the electrodes coincides with the optical axis of the main reflector 20. ing. The main reflecting mirror 20 has a spheroid structure having a first focal position in the approximate center between the electrodes, and the sub-reflecting mirror 30 is configured by a spherical mirror having the same first focal position as the main reflecting mirror 20. .

The short arc mercury lamp 10 has a substantially spherical light emitting portion 11 and sealing portions 12 (12a, 12b) at both ends thereof, and one sealing portion 12a is attached to the neck (top) 24 of the main reflecting mirror 20. . The short arc mercury lamp 10 and the main reflecting mirror 20 are fixed using a heat-resistant adhesive 25 or the like, and both may be directly attached as shown, or a base (ref base: not shown) or the like is used as a separate member for short-circuiting. The arc mercury lamp 10 may be attached to the reflex base, and the reflex base may be fixed to the main reflecting mirror 20.
It is also possible to provide a hole through which cooling air passes in the reflex base.

The reflecting portion 22 of the main reflecting mirror 20 is a spheroidal surface, and has a concave shape (substantially bowl-shaped) as a whole. The main reflector 20 is made of borosilicate glass, which is a heat-resistant glass, and an interference film that reflects visible light (VIS) and ultraviolet light (UV) and transmits infrared light (IR) is formed on its inner surface. The Specifically, the interference film is formed by forming a film in which titania (TiO ₂ ) and silica (SiO ₂ ) are alternately laminated as a first layer with respect to a base material, and a hafnium oxide as a second layer thereon. A film in which (HfO ₂ ) and magnesium fluoride (MgF ₂ ) are alternately stacked is formed. Thereby, in the first layer, for example, ultraviolet light having a wavelength of 400 to 700 nm can be reflected, and in the second layer, for example, visible light having a wavelength of 200 to 400 nm can be reflected.

The sub-reflecting mirror 30 is attached so as to cover the opening of the main reflecting mirror 20. The main reflector 20 is joined by a dedicated fixture such as a heat-resistant silicone adhesive, stainless steel, or heat-resistant resin. The sub-reflecting mirror 30 has a substantially spherical body following the light emitting part 11 of the short arc mercury lamp as the same first focal position as the main reflecting mirror 20, and therefore reflects the light incident on the reflecting mirror in the same direction. Let Since the sub-reflecting mirror 30 is mounted at a position away from the light emitting part of the short arc mercury lamp, it is easy to avoid heat from the short arc mercury lamp, so that glass, resin, metal, etc. can be used as a base material. On the inner surface, an interference film that reflects visible light (VIS) and ultraviolet light (UV) and transmits infrared light (IR) is formed. Specifically, the interference film is a film in which tantala (Ta ₂ O ₅ ) and silica (SiO ₂ ) are alternately laminated as a first layer on a base material, and a second layer is formed thereon. A film in which hafnium oxide (HfO ₂ ) and magnesium fluoride (MgF ₂ ) are alternately stacked is formed. Thereby, in the first layer, for example, ultraviolet light having a wavelength of 300 to 400 nm can be reflected, and in the second layer, for example, visible light having a wavelength of 400 to 700 nm can be reflected. Of course, the interference film is not limited to this, and other combinations can be selected.
Further, when metallic aluminum is used for the sub-reflecting mirror 30, it also has a reflecting function and can be used without forming an interference film. Of course, since aluminum can reflect the entire wavelength range, it also reflects infrared light. However, when the light incident on the sub-reflecting mirror 30 is reflected again by the main reflecting mirror 20, the infrared light is reflected. As a result, light that does not contain infrared light is emitted.

  Here, it is desirable that the opening edge of the main reflecting mirror 20 and the opening edge of the sub-reflecting mirror 30 substantially coincide. This is because the state in which the opening edges of the main reflecting mirror 20 and the sub-reflecting mirror 30 substantially coincide with each other is the case where the diameter of the optical device is minimum. Further, since the light reflected by the sub-reflecting mirror 30 is returned again to the short arc mercury lamp 10 and emitted through the main reflecting mirror 20, the apparent distance between the electrodes of the short arc mercury lamp 10 is reduced to almost half. As a result, there is an advantage that a brighter light source can be provided.

A translucent cover 40 is disposed in front of the main reflecting mirror 20. The translucent cover 40 is provided to prevent the broken pieces from scattering when the short arc mercury lamp 10 is broken.
The translucent cover is often formed of a so-called flat plate whose both surfaces are flat, but a lens shown as an example in FIGS. 5B and 5C described later can also be used. By using such a lens, it is possible to correct the lens effect due to the difference in the thickness of the light emitting container used in the light emitting unit 11. Furthermore, the light converged by the elliptical mirror can be converted into parallel light mainly used in the LCD projector apparatus.
That is, the shape of the lens is appropriately selected according to the purpose of the projector apparatus.

Although not shown, the translucent cover 40 is attached to a translucent cover holding member, and this translucent cover holding member is also attached to an optical unit (not shown). The translucent cover 40 has a size (outer diameter) capable of receiving all the light from the main reflecting mirror 20 and is disposed at a position where all the light from the main reflecting mirror 20 can be received. The base 41 of the translucent cover is made of borosilicate glass (TEMPAX), which is a hard glass, and transmits visible light (VIS) and reflects ultraviolet light (UV) to the surface on the main reflecting mirror 20 side. Interference film 43 is formed. Specifically, the interference film is formed by alternately laminating hafnium oxide (HfO ₂ ) and magnesium fluoride (MgF ₂ ) on the base material. Thereby, for example, ultraviolet light having a wavelength of 200 to 400 nm can be reflected and visible light having a wavelength of 400 to 700 nm can be transmitted. An antireflection film (AR coating) (not shown) is applied to the surface of the translucent cover 40 opposite to the main reflecting mirror 20. This is to prevent the visible light transmitted through the translucent cover 40 from being reflected again.
Of course, the combination of the interference films is not limited to this, and may be omitted if the main reflecting mirror 20 and the sub-reflecting mirror 30 have an ultraviolet light reflecting function. That is, the arrangement of the interference film means that an optimum combination can be selected depending on the mounting position of the ultraviolet light auxiliary light source 50.
For the same reason, the ultraviolet light reflecting function of the main reflecting mirror 20 and the sub-reflecting mirror 30 can be omitted depending on the mounting position of the ultraviolet light starting auxiliary light source 50.
When the light source device is incorporated in an actual projector or the like, a liquid crystal panel or a DLP rotating color filter is disposed in front of the light-transmitting cover 40.

FIG. 2 is a diagram for explaining the state of travel of short arc mercury lamp radiation.
For the sake of explanation, the main reflecting mirror 20, the sub-reflecting mirror 30, and the transmitted light cover 40 are provided with an ultraviolet light reflecting function, and the main reflecting mirror 20 and the sub-reflecting mirror 30 have infrared light (IR) transmittance. This interference film is also formed.
The emitted light of the short arc mercury lamp 10 includes visible light (VIS), infrared light (IR), and ultraviolet light (UV). The wavelength range of visible light (VIS) is approximately 400 to 700 nm, the wavelength range of infrared light (IR) is approximately 700 nm or more, and the wavelength range of ultraviolet light (UV) is approximately 400 nm or less. In the figure, the light incident on the reflecting mirror or translucent cover is indicated by a solid line, visible light (VIS) is indicated by a one-dot chain line, infrared light (IR) is indicated by a large dotted line, and ultraviolet light (UV) is indicated by a small dotted line. Is shown.
Of the radiated light from the short arc mercury lamp, the light 53 that has reached the sub-reflecting mirror 30 reflects visible light (VIS) and ultraviolet light (UV) at the sub-reflecting mirror 30 to produce infrared light (IR). Permeate.
Next, the light 55 that has reached the main reflecting mirror 20 reflects visible light (VIS) and ultraviolet light (UV) and transmits infrared light (IR) in the main reflecting mirror 20. The light 55 includes direct light from the short arc mercury lamp 10, but also includes light reflected by the sub-reflecting mirror 30.
Further, the light reaching the translucent cover 40 transmits only the visible light (VIS) 51 and reflects the ultraviolet light (UV) 52 in the translucent cover 40.

In the above description, the means of the optical device that effectively uses the emitted light from the short arc mercury lamp 10 of the present invention has been described, but a method for improving startability in the ultraviolet light auxiliary light source will be described.
FIG. 3 is a diagram for explaining the operation of the ultraviolet light auxiliary light source.
Since the configuration of the reflecting mirrors 20 and 30 and the transmissive cover 40 is the same except for the difference in the reflecting function of each member, description thereof will be omitted.
The reflecting function of each reflecting mirror and translucent cover to be set is shown. The main reflecting mirror 20 is configured to transmit infrared light (IR) and reflect ultraviolet light (UV) and visible light (VIS), and the sub-reflecting mirror 30 includes ultraviolet light (UV) and infrared light (IR). ) And reflects visible light, and the translucent cover 40 is configured to reflect ultraviolet light (UV) and infrared light (IR) and transmit visible light (VIS).
When the lighting device (not shown) of the short arc mercury lamp 10 is turned on, first, the ultraviolet light auxiliary light source 70 emits light, and the ultraviolet light from the ultraviolet light auxiliary light source 70 is emitted in all directions. Direct light 61, which is one of them, reaches the lamp light emitting unit 11. The ultraviolet light 63 reflected by the interference film 42 coated on the base material 41 of the translucent cover 40 also reaches the lamp light emitting part 11 and is further reflected by the interference film 22 coated on the substrate 21 of the main reflecting mirror 20. 62 also reaches the lamp light emitting unit 11.
Compared with the case where only the direct light 61 arrives, reflected light from multiple directions is added, and more intense ultraviolet light arrives, which improves the lighting performance.
Further, since the ultraviolet light auxiliary light source 70 is provided on a non-reflecting surface on which no reflecting mirror that reflects visible light such as the main reflecting mirror 20 and the sub-reflecting mirror 30 is disposed, it is emitted from a short arc mercury lamp. Visible light can be used efficiently.
The non-reflective surface in the present invention is a portion that connects the reflective surface and the reflective surface of the light source device, and does not contribute to the reflection of light. In this embodiment, the sub-reflecting mirror (30) and the translucent surface. It is the part which connects the surface of the side where the interference film is provided of the conductive cover (40), and is the part where the interference film is interrupted. In addition to the above, the non-reflecting surface includes a neck portion for holding the short arc mercury lamp (10) in the main reflecting mirror (20), the main reflecting mirror (20), and the sub-reflecting mirror ( 30), which is a portion where the interference film is interrupted.

The structure of the ultraviolet light auxiliary light source 70 will be described using the ultraviolet light auxiliary light source 71 having the shape shown in FIG.
A quartz glass tube that transmits ultraviolet light is used as a light emitting container 700, and a pair of external electrodes 701 are disposed on both ends of the surface. Argon (Ar), xenon (Xe), and neon (Ne) are disposed in the light emitting container. In addition to a rare gas such as nitrogen, nitrogen (N 2) or helium (He) is sealed. If mercury (Hg) is also enclosed, the lighting voltage can be lowered by utilizing the penning effect.
Further, it is possible to use atmospheric discharge generated by applying a high voltage with electrodes provided at appropriate positions, or other ultraviolet light emitting light sources such as light emitting diodes and lasers that emit ultraviolet light.

  FIG. 5 shows embodiments (a) to (c) of the translucent cover 40 according to the present invention. In either case, the left side of the translucent cover indicates the light incident surface, and the right side indicates the light output surface, and the interference film 42 that reflects the ultraviolet light from the ultraviolet light auxiliary light source is formed. (A) shows the case of flat glass, which has the effect of preventing scattering at the time of breakage, and (b) shows the case of an aspherical surface, which corrects the lens effect caused by the light emitting container of the short arc mercury lamp and reduces the light distribution. The case of making it uniform is shown. (C) shows a case where the incident surface has a shape obtained by combining two curved surfaces, in which the lens effect by the light emitting container of the short arc mercury lamp is corrected to make the light distribution uniform.

The description of the light rays emitted from FIGS. 5A and 5C will be made with reference to FIG. The lower half of FIG. 6 shows the state of the translucent cover of FIG. 5A, and the upper half of FIG. 6 shows the state of the translucent cover of FIG. 5C. Further, the ray trajectory in FIG. 5A is indicated by a wavy line, and the ray trajectory in FIG. 5C is indicated by a solid line.
When the light-transmitting covers 41a and 41c are incident from the same angle, the light-transmitting cover 41a has no change in incident and outgoing angles, while the light-transmitting cover 41c is refracted according to the thickness of the light-transmitting cover. Then, the angles of incidence and emission are changed, and the light is condensed on P1 and P2, respectively. The density of the light at this time is shown by the boxes 67 and 68. Although the density of the emitted light from the translucent cover 41a is biased, the density 68 is shown to be uniform in the translucent cover 41c. That is, the non-uniform distribution at the condensing point P1 indicates that the light is uniform at the condensing point P2. That is, the translucent cover 41c means that light having a uniform distribution can be output from the optical device. By using such a translucent cover, there is an advantage that more uniform light can be taken into the projector apparatus side without enlarging the optical apparatus itself.

FIG. 7 shows an embodiment in which the material and shape of the sub-reflecting mirror 30 used in the optical apparatus of the present invention are changed. In the embodiment shown in FIG. 1, an example in which the sub-reflecting mirror 30 uses a borosilicate glass as a base material is shown, but FIG. 7 shows an embodiment in which an aluminum base material is used.
Since the configuration of the reflecting mirrors 20 and 30 and the transmissive cover 40 is the same as that of FIG. 1 except that the sub-reflecting mirror 30 is changed, the description thereof is omitted.
The sub-reflecting mirror 30 is manufactured by aluminum spatula drawing, pressing, cutting, or the like, and constitutes a rotary reflecting surface having the same shape as that in FIG. When borosilicate glass is used as the base material, it is necessary to process the interference film, which is a reflection member, but in this embodiment, which is made of aluminum, the aluminum surface is used as it is without providing an interference film. In addition to reflecting light of all wavelengths emitted from the short arc mercury lamp 10, ultraviolet light emitted from the ultraviolet auxiliary light source 71 can also be reflected.
Moreover, although it is possible to use it without processing anything on the reflecting surface, it can also be used after alumite treatment or processing of a silica (SiO ₂ ) film for protecting the reflecting surface. The processed portion described here is the portion indicated by 32 in FIG. Even in this case, light of all wavelengths emitted from the short arc mercury lamp 10 can be reflected.
Furthermore, as in the case where borosilicate glass is used as a base material, it is possible to form a reflection film using an interference film without any problem.

Further, the auxiliary reflecting mirror 30 can be made thin by making it aluminum. The thickness of the borosilicate glass substrate needs to be about 4 mm, whereas that of aluminum can be made very thin, about 1 mm, so that it is possible to reduce the weight, and the mechanical strength is a problem even if the wall thickness is reduced. It is available without. Even if the outer diameter is the same by reducing the wall thickness, the size of the opening side of the sub-reflecting mirror that does not hinder the emitted light can be increased, and the amount of light flux that can be captured can be increased.
Furthermore, the inner diameter of the sub-reflecting mirror 30 is larger than the opening diameter of the main reflecting mirror 20, and a hollow circular portion 26 without overlapping of both is formed on the mating surface of both. A recess is provided in a part of the hollow circular portion 26, and the ultraviolet light auxiliary light source 71 can be installed in the recess 27. The hollow circular portion 26 and its recess 27 are non-reflective surfaces in the present invention. FIG. 4 is a diagram showing an installation state in the section AA. The shape of the ultraviolet light auxiliary light source 71 can be made into a crescent shape as shown in FIG.
By setting the installation state shown in the present embodiment, the ultraviolet light from the ultraviolet light auxiliary light source 71 is transmitted to the short arc mercury lamp 10 without interfering with the optical paths of both the short arc mercury lamp 10 and the reflecting mirror. It is possible to reach the inside of the light emitting unit 11 and to improve the lamp startability.
Thus, the embodiment shown in FIG. 7 shows an example in which the difference between the members of the main reflecting mirror 20 and the sub-reflecting mirror 30 is used without changing the outer diameter of the optical device. If not only the inner diameter of the sub-reflecting mirror 30 but also the outer diameter thereof is larger than that of the main reflecting mirror 20, a recess 27 is formed on the opening side end face of the main reflecting mirror 20 as in FIG. It goes without saying that the light source 71 can be installed.

FIG. 8 is a diagram showing the progress of ultraviolet light in an embodiment in which an aluminum material is used for the sub-reflecting mirror 30 and the inner diameter of the sub-reflecting mirror 30 is larger than the opening diameter of the main reflecting mirror 20. .
Since the configuration of the main reflecting mirror 20, the sub reflecting mirror 30, and the transmissive cover 40 is the same as that of FIG. 1 except that the sub reflecting mirror 30 is changed, the description thereof is omitted.
Each reflecting mirror to be set and the reflecting function of the translucent cover are shown. The main reflecting mirror 10 is configured to transmit ultraviolet light (UV) and infrared light (IR) and reflect visible light (VIS), and the sub-reflecting mirror 30 uses an aluminum material and performs anodizing 32. The visible light (VIS), ultraviolet light (UV), and infrared light (IR) are reflected, and the translucent cover 40 reflects ultraviolet light (UV) and infrared light (IR). It is configured to transmit visible light (VIS).
When the lighting device (not shown) of the short arc mercury lamp 10 is turned on, first, the ultraviolet light auxiliary light source 71 emits light, and the ultraviolet light from the ultraviolet light auxiliary light source 71 is emitted in all directions. Since the ultraviolet light auxiliary light source 71 is installed in the recess 27, direct light emitted from the ultraviolet light auxiliary light source 71 cannot reach the lamp light emitting unit 11. However, the ultraviolet light 65 reflected by the interference film 42 coated on the base material 41 of the translucent cover 40 reaches the lamp light emitting unit 11, and further, the ultraviolet light 66 reflected by the substrate 31 of the sub-reflecting mirror 30. Also reaches the lamp light emitting unit 11.
Even if the direct light does not reach the lamp light-emitting unit 11, it is configured as an optical device that can use the emitted light of the short arc mercury lamp 10 with high efficiency by the ultraviolet light reflected from the reflecting mirror or the translucent cover. Even in the case (the state where there is no external light excitation), the short arc mercury lamp 10 can be started without any problem.

FIG. 9 shows the overall structure of the short arc mercury lamp 10. The short arc mercury lamp 10 is a so-called short arc type discharge lamp, and has a substantially spherical light emitting portion 11 formed by a discharge vessel made of quartz glass. A light emitting space is formed in the light emitting portion 11, and electrodes 13b having the same shape are arranged to face each other at an interval of 0.5 mm to 2 mm in the space. Sealing portions 12 (12a, 12b) are formed at both ends of the light emitting portion 11, and conductive metal foils 15 (15a, 15b) made of molybdenum are hermetically sealed by, for example, a shrink seal. Buried. The shaft of the electrode 13 (13a, 13b) is joined to one end of the metal foil 15 (15a, 15b), and the external lead 14 (14a, 14b) is joined to the other end of the metal foil 15. Power can be supplied from an external power supply device. The light emitting unit 11 is filled with mercury, rare gas, and halogen gas. Mercury is used to obtain a necessary ultraviolet light wavelength, for example, radiation having a wavelength of 300 to 360 nm, and is 0.15 mg / mm ³ or more, specifically 0.15 to 0.25 mg / mm ³ enclosed. Yes. Although the amount of sealing varies depending on the temperature condition, it becomes a high vapor pressure of 8 MPa or more during lighting.

As the rare gas, for example, argon gas is sealed at about 13 kPa. Its function is to improve the lighting startability. As for halogen, iodine, bromine, chlorine and the like are enclosed in the form of mercury or other metals and compounds. The encapsulated amount of halogen is selected from the range of 5 × 10 ^{−5 to} 7 × 10 ⁻³ μmol / mm ³ . The function of the halogen is to extend the life using a so-called halogen cycle. However, an extremely small and extremely high operating vapor pressure such as the discharge short arc mercury lamp of the present invention also has an effect of preventing devitrification of the discharge vessel. is there. An example of a numerical value of a short arc mercury lamp is, for example, the maximum outer diameter of the light emitting portion 11 is 9.5 mm, the distance between the electrodes is 1.5 mm, the inner volume of the arc tube is 75 mm ³ , the rated voltage is 70 V, the rated power is 200 W, and the AC lighting is performed at 350 Hz. Is done.

In addition, this type of short arc mercury lamp is built in a projector apparatus that is miniaturized, and as a whole size is required to be extremely small, a high amount of emitted light is also required. For this reason, the thermal influence in the light emitting part is extremely severe. The lamp wall load value of the lamp is 0.8 to 2.0 W / mm ² , specifically 1.5 W / mm ² . By having such a high mercury vapor pressure and tube wall load value, it is possible to provide light with good color rendering when mounted on a presentation device such as a projector device or an overhead projector. The driving method of the short arc mercury lamp is not limited to AC lighting, and may be DC lighting.

FIG. 10 is a schematic diagram showing an electrode tip and a protrusion. A projection 2b is formed at the tip of the electrode 13 (the end facing the other electrode) as the short arc mercury lamp is turned on. The phenomenon in which the protrusion 2b is formed is not necessarily clear, but is estimated as follows. That is, tungsten (electrode constituent material) evaporated from a high temperature portion near the electrode tip during the operation of the short arc mercury lamp is combined with halogen and residual oxygen present in the arc tube. For example, if the halogen is Br, WBr, WBr ₂ , WO, WO ₂ , WO ₂ Br, WO ₂ Br ₂ and other tungsten compounds. These compounds are decomposed into tungsten atoms or cations at a high temperature portion in the gas phase near the electrode tip. These tungsten atoms are diffused from the arc, which is the high temperature part in the gas phase, to the vicinity of the tip of the electrode, which is the low temperature part, so-called temperature diffusion, and the tungsten atoms are ionized in the arc. Due to the phenomenon of becoming positive ions and attracted toward the cathode by the electric field when the cathode is operating, so-called drift phenomenon, the density of tungsten vapor in the gas phase near the electrode tip increases, and deposits on the electrode tip to form protrusions It is thought that.

According to FIG. 10, the electrode 13 is composed of a sphere portion 2a and a shaft portion 2c, and a protrusion 2b is formed at the tip of the sphere portion 2a. Even if the projection 2b does not exist at the start of lighting of the short arc mercury lamp, it is naturally formed by the subsequent lighting. Here, the protrusion 2b does not occur in any discharge lamp. The distance between the electrodes is 1 mm to 2 mm, and 0.08 mg / mm ³ or more of mercury, rare gas, and halogen are enclosed in the range of 5 × 10 ^{−5 to} 7 × 10 ⁻³ μmol / mm ^{3 in} the light emitting part. This is a phenomenon that occurs in the short arc type discharge lamp, and as the lamp is lit, the protrusion 2b is formed, and an arc is formed between the protrusions 2b.
As described above, the short arc mercury lamp of the present invention has protrusions formed on the electrodes, so that it is not abnormally heated by the return light from the outside, so that infrared light (IR) does not return to the light emitting part. Yes.

  The main reflecting mirror 20, the sub-reflecting mirror 30, and the transmitted light cover 40 forming the optical device of the present invention are particularly limited to the above-described embodiment as long as the light emitted from the short arc mercury lamp can be reflected or transmitted by the wavelength. It is not something. However, in terms of being used in a projector apparatus, it is preferable to use a member having excellent heat resistance and strength resistance. Specifically, the main reflecting mirror 20 is based on borosilicate glass, quartz glass, or the like, and the sub-reflecting mirror 30 is a metal material such as aluminum, polyimide resin in addition to the members of the main reflecting mirror 20. A heat-resistant resin material such as can also be used. In particular, the reason why the heat resistance of the main reflecting mirror 20 is required is that the main reflecting mirror 20 is overheated by heat from the lamp because it is close to the lamp light emitting unit 11, and the main reflecting mirror 20 is about 400 ° C. when the lamp is turned on. It is because it becomes high temperature. The reason why strength resistance is required is that even if the short arc mercury lamp breaks during lighting, the reflector itself is not damaged, and it is possible to reliably prevent the short arc mercury lamp from being scattered. It is to do.

  In addition to the above-described configuration, the translucent cover 40 may be disposed away from the front opening of the sub-reflecting mirror 30. In this case, there is an advantage that cooling air can be blown toward the sealing portion 12b of the short arc mercury lamp 10. Furthermore, instead of the light-transmitting cover, a lens used in a projector device than an optical device can be attached. With such a configuration, further downsizing is possible.

10 Short Arc Mercury Lamp 20 Main Reflector 30 Sub Reflector 40 Translucent Cover 70 Ultraviolet Light Auxiliary Light Source

Claims (4)

A short arc mercury lamp (10) comprising a light emitting part having a pair of electrodes and sealing parts provided at both ends of the light emitting part;
A spheroidal surface arranged so as to surround the short arc mercury lamp (10) in a state where the arc direction of the short arc mercury lamp (10) coincides with the optical axis and the first focal point is formed between the electrodes. A main reflector (20) comprising:
The main reflector (20) is disposed so as to surround the opening, and light emitted directly from the short arc mercury lamp (10) toward the opening of the main reflector (20) is transmitted to the main reflector ( 20) a sub-reflecting mirror (30) comprising a spherical mirror for reflection again toward
An opening provided in the sub-reflecting mirror (30) for passing light reflected from the main reflecting mirror (20);
A translucent cover (40) provided in the opening;
An ultraviolet light reflecting function provided on at least one of the main reflecting mirror (20), the sub-reflecting mirror (30), and the translucent cover (40);
An optical device comprising:
An ultraviolet auxiliary light source (70, 71) is disposed in a space surrounded by the main reflecting mirror (20), the sub-reflecting mirror (30), the translucent cover (40), and the non-reflecting surface. An optical device.   The optical apparatus according to claim 1, wherein the ultraviolet light auxiliary light source is disposed on a surface of the non-reflecting surface.   The opening diameter of the sub-reflecting mirror (30) on the side of the main reflecting mirror (20) is larger than or substantially equal to the opening diameter of the main reflecting mirror (20), and is the maximum outside of the main reflecting mirror (20). The optical device according to claim 1, wherein the maximum outer diameter of the sub-reflecting mirror (30) is smaller than the diameter.   A projector apparatus comprising the optical apparatus according to claim 1.

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