JP2010060855A - Optical apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical apparatus adapted for a request of miniaturization. <P>SOLUTION: Each of a main reflection mirror (MR) and a subsidiary reflection mirror (SR) reflects the ultraviolet light and visible light of the light emitted from a mercury lamp (10) and transmits the infrared light thereof. A lens, which transmits the visible light of the reflected light from the main reflection mirror (MR), reflects the ultraviolet light thereof and has a curved side face on the lamp side, is arranged at such a position that the reflected light from the main reflection mirror (MR) is received and the position between the lens and the main reflection mirror (MR) is shorter than that between the lens and a second focus of the main reflection mirror (MR). <P>COPYRIGHT: (C)2010,JPO&INPIT

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 is a device in which millions of small mirrors are laid out for each pixel, and light projection 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 type mercury lamp having a high vapor pressure is used as a 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 mercury lamp (hereinafter also simply referred to as “lamp”) is incorporated in a spheroid concave 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 lamp cannot be lowered even if the size and shape are restricted.

  FIG. 7 shows the schematic structure of a conventionally proposed optical device. Separately from the concave reflecting mirror, an auxiliary reflecting mirror (sub-reflecting mirror) is provided to return the light (La) radiated forward from the lamp to the concave reflecting mirror without directly irradiating the concave reflecting mirror. (Lb), to use.

  However, since the distance between the electrodes is shortened when the lamp is further downsized, the light reflected by the auxiliary reflecting mirror is shielded by the electrodes, and there is a problem that it cannot be guided to the concave reflecting mirror. This is because the arc luminescent spot is not actually a point light source but has a finite size, the shape of the light emitting part 11 is not a perfect sphere, light is refracted at the interface of the light emitting part, etc. by.

Further, when the light reflected by the auxiliary reflecting mirror irradiates the electrode, the temperature of the electrode is raised and the problem of electrode wear also occurs. On the other hand, when the distance between the electrodes is increased, there is a problem that the arc bright spot is increased and the brightness of the emitted light is lowered as a whole.
JP-A-2005-197208 JP 2006-030378 A JP 2006-106656 A

  The problem to be solved by the present invention is to provide an optical device that can efficiently use the radiated light of the lamp and is suitable for the demand for miniaturization.

In order to solve the above problems, an optical device of the present invention includes a short arc type 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, and the short arc. The main reflector made of a spheroid arranged so as to surround the mercury lamp (10) with the arc direction of the mercury lamp (10) coincident with the optical axis and with the first focal point formed between the electrodes. (MR) and light that is attached to the sealing portion of the sealing portion that is disposed on the opening side of the main reflecting mirror (MR) and is directly emitted from the mercury lamp (10) to the opening side of the main reflecting mirror. And an auxiliary reflecting mirror (SR) for reflecting again toward the main reflecting mirror (MR).
The main reflecting mirror (MR) and the auxiliary reflecting mirror (SR) both reflect ultraviolet light and visible light but transmit infrared light out of the radiated light of the mercury lamp (10). Further, among the light from the main reflecting mirror (MR), a lens that transmits visible light but reflects ultraviolet light and has a light incident surface having a curved shape is provided on the main reflecting mirror (MR). ) Is located closer to the main reflector (MR) than the second focal position.

  Furthermore, the lens is configured such that light from the main reflecting mirror enters vertically.

  Further, the lens is a meniscus lens.

  Further, the auxiliary reflecting mirror is composed of a spherical reflecting mirror.

  Furthermore, the virtual surface (MR-VS) formed by the opening edge of the main reflecting mirror (MR) and the virtual surface (SR-VS) formed by the opening edge of the auxiliary reflecting mirror (SR) are substantially the same. It is characterized by doing.

Further, the short arc type mercury lamp (10) is characterized in that 0.15 mg / mm ³ or more of mercury is sealed in the light emitting portion.

  Further, the short arc type mercury lamp (10) is characterized in that a gap between a pair of electrodes is 0.5 to 2.0 mm.

Furthermore, the short arc type mercury lamp (10) is characterized in that 5 × 10 ^{−5 to} 7 × 10 ⁻³ μmol / mm ³ of halogen is enclosed in the light emitting portion.

  Further, the short arc type mercury lamp (10) is characterized in that a projection is formed at the tip of the electrode.

The present invention has the following effects.
(1). By returning the ultraviolet light of the light emitted from the mercury lamp to the light emitting part of the lamp, the light emission of the lamp can be enhanced. This is because the ultraviolet light can be absorbed by mercury vapor so that the temperature of the light emitting part can be increased as a whole.
(2). Further, infrared light out of the light emitted from the mercury lamp is prevented from returning to the lamp, so that the problem that the electrode is locally heated and worn can be solved.

FIG. 1 shows an overall external view of an optical apparatus according to the present invention.
The optical device includes a mercury lamp (hereinafter also simply referred to as “lamp”) 10, a main reflecting mirror MR, and an auxiliary reflecting mirror SR. The main reflecting mirror MR is arranged so as to surround the lamp 10, and the arc direction of the lamp 10, that is, the direction connecting the tips of the electrodes coincides with the optical axis Z of the main reflecting mirror MR. The main reflecting mirror MR has a spheroidal surface structure having a first focal point at a substantially central position between the electrodes, and the auxiliary reflecting mirror SR is formed in a spherical structure corresponding to the spherical shape of the lamp light emitting unit. Yes.

  The 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) MRa of the main reflecting mirror MR. The lamp 10 and the main reflector MR are fixed using an adhesive or the like, but both may be directly attached as shown, or a base (ref base) is used as a separate member, and the lamp 10 is attached to the reflex base. The reflex base may be fixed to the main reflector MR.

  The reflecting part MRb of the main reflecting mirror MR is a spheroidal surface, and has a concave shape (substantially bowl-shaped) as a whole. The main reflector MR is made of borosilicate glass, which is a low expansion glass, and has an interference film that reflects visible light (VIS) and ultraviolet light (UV) and transmits infrared light (IR) on its inner surface. Is done. Specifically, the interference film is formed by alternately laminating titania (TiO 2) and silica (SiO 2) as a first layer with respect to a base material, and on that, hafnium oxide (HfO 2) is formed as a second layer. ) And magnesium fluoride (MgF) are alternately laminated. Thereby, for example, ultraviolet light having a wavelength of 300 to 380 nm can be reflected in the first layer, and visible light having a wavelength of 380 to 830 nm can be reflected in the second layer.

  The auxiliary reflecting mirror SR is attached to the sealing portion 12 b of the lamp 10. Attached with heat-resistant ceramic adhesive. Since the auxiliary reflecting mirror SR has a substantially spherical body following the light emitting part 11 of the lamp, the auxiliary reflecting mirror SR reflects the light incident on the reflecting mirror in the same direction. Since the auxiliary reflector SR is near the lamp bulb and becomes high temperature, quartz glass is used as a base material, and the inner surface reflects visible light (VIS) and ultraviolet light (UV) and transmits infrared light (IR). An interference film is formed. Specifically, the interference film is formed by alternately stacking tantala (Ta2O5) and silica (SiO2) as the first layer on the base material, and on that, hafnium oxide (HfO2) is formed as the second layer. ) And magnesium fluoride (MgF) are alternately laminated. Thereby, in the first layer, for example, ultraviolet light having a wavelength of 300 to 380 nm can be reflected, and in the second layer, for example, visible light having a wavelength of 380 to 830 nm can be reflected.

  Here, the virtual surface (MR-VS) formed by the opening edge of the main reflecting mirror (MR) and the virtual surface (SR-VS) formed by the opening edge of the auxiliary reflecting mirror (SR) substantially coincide. It is desirable. This is because the length of the main reflecting mirror (MR) in the optical axis direction can be reduced, so that the entire optical device can be miniaturized, and the emitted light from the lamp 10 is converted into the main reflecting mirror (MR) or the auxiliary reflecting mirror (SR). This is because it can be reflected by at least one of the above.

  A lens ML is disposed in front of the main reflector MR and closer to the main reflector MR than the second focal position of the main reflector MR. The lens ML has at least a convex portion (a shape protruding in the same direction as the main reflecting mirror MR) on the side surface on the lamp side, and has a curved surface shape so that the light emitted from the main reflecting mirror MR enters vertically. Specifically, it is desirable to use a so-called meniscus lens, which is a single lens or a cemented lens whose one surface is convex and whose opposite surface is concave as shown in the figure.

Although not shown, the lens ML is attached to a lens holding member, and this lens holding member is attached to an optical unit (not shown). The lens ML has a size (outer diameter) capable of receiving all the light from the main reflecting mirror MR, and is disposed at a position where all the light from the main reflecting mirror MR can be received. The lens ML is made of borosilicate glass (TEMAX), which is hard glass, and an interference film that transmits visible light (VIS) and reflects ultraviolet light (UV) to the surface on the main reflecting mirror MR side. It is formed. Specifically, the interference film is formed by alternately laminating hafnium oxide (HfO 2) and magnesium fluoride (MgF) on the base material. Thereby, for example, ultraviolet light having a wavelength of 300 to 380 nm can be reflected, and visible light having a wavelength of 380 to 830 nm can be transmitted. An antireflection film (AR coating) is applied to the surface of the lens ML opposite to the main reflecting mirror MR. This is to prevent the visible light that has passed through the lens ML from being reflected again.
A liquid crystal panel and a DLP rotating color filter are disposed in front of the lens ML.

FIG. 2 is a diagram for explaining the progress of the lamp radiation.
The emitted light of the lamp 10 includes visible light (VIS), infrared light (IR), and ultraviolet light (UV). The wavelength range of visible light (VIS) is approximately 380 to 830 nm, the wavelength range of infrared light (IR) is approximately 830 nm or more, and the wavelength range of ultraviolet light (UV) is approximately 380 nm or less. In the figure, the light incident on the reflecting mirror or lens 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. Yes.
Of the lamp radiation, the light EL1 that has reached the auxiliary reflector SR reflects visible light (VIS) and ultraviolet light (UV) and transmits infrared light (IR) in the auxiliary reflector SR.
Next, the light EL2 reaching the main reflecting mirror MR reflects visible light (VIS) and ultraviolet light (UV) and transmits infrared light (IR) in the main reflecting mirror MR. The light EL <b> 2 includes direct light from the lamp 10, but also includes light reflected by the auxiliary reflecting mirror SR.
Further, the light EL3 reaching the lens ML transmits visible light (VIS) and reflects ultraviolet light (UV) in the lens ML. The reflected ultraviolet light (UV) is returned to the lamp 10 again via the main reflecting mirror MR. Of the light EL3 that reaches the lens ML, infrared light (IR) is absorbed by the lens ML.

  With such a configuration, the optical device of the present invention emits only visible light (VIS) to the outside of the optical device. Then, the ultraviolet light (UV) is returned to the lamp light-emitting unit 11 again and absorbed by mercury vapor to raise the temperature of the light-emitting unit.

FIG. 3 is an enlarged conceptual diagram of the light emitting unit 10 of the lamp.
The inside of the light emitting unit 10 is filled with mercury vapor (mercury atoms). Here, ultraviolet light (UV) is absorbed by mercury vapor, thereby raising the temperature of the light emitting unit 10. On the other hand, infrared light (IR) is not absorbed by mercury vapor, but passes through the space between the electrodes and passes through the lamp or collides with the electrodes. In the latter case, the temperature of the electrode is locally increased, and the electrode is worn out. In particular, as will be described later, the lamp of the present invention often has a protrusion formed at the tip of the electrode, and when the protrusion is irradiated with infrared light (IR), the protrusion deforms, thereby causing an arc of the discharge lamp. The direction is deformed, and the illuminance is reduced or the so-called 'arc jump' is caused by electrode wear.

  FIG. 4 shows other embodiments (a) to (c) of the lens ML according to the present invention. In either case, the right side of the lens represents the light incident surface, and the left side represents the light exit surface. (A) shows the case where the curvature of the entrance surface is smaller than the curvature of the exit surface, and (b) shows the case where the curvature of the entrance surface is greater than the curvature of the exit surface. Each of these lenses is a so-called “convex meniscus lens” (a crescent-shaped lens). The incident surface is convex, but the exit surface is concave. By using this lens, when a convex meniscus lens having a uniform thickness is used in the present invention, there is an advantage that the optical path of light transmitted through the lens is not affected. There is a so-called 'plano-convex lens' whose exit surface is a flat plate. In any of the lenses (a) to (c), it is desirable that the incident surface has a curved surface shape so that the light beam from the main reflecting mirror MR enters perpendicularly. This is for returning ultraviolet light (UV) to the lamp light emitting unit 11 again.

FIG. 5 shows the overall structure of the lamp 10. The lamp 10 is a so-called mercury lamp, and has a substantially spherical light emitting unit 10 formed by a discharge vessel made of quartz glass. A light emitting space is formed in the light emitting portion 11, and the same electrode 2 is disposed oppositely in the space at an interval of 0.5 mm to 2 mm. Sealing portions 12 are formed at both ends of the light emitting portion 11, and the conductive metal foil 3 made of molybdenum is embedded in the sealing portions 12 in an airtight manner, for example, by a shrink seal. The shaft portion of the electrode 2 is bonded to one end of the metal foil 3, and an external lead is bonded to the other end of the metal foil 3 to supply power from an external power supply device. The light emitting unit 11 is filled with mercury, rare gas, and halogen gas. Mercury is necessary ultraviolet light wavelength, for example, for obtaining a radiation wavelength 300~360nm, 0.15mg / mm ³ or more, specifically are 0.15~0.25mg / mm ³ encapsulation. Although the amount of the sealing varies depending on the temperature condition, it becomes a high vapor pressure of 80 atm or more at the time of 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 lighting vapor pressure such as the discharge lamp of the present invention also has an effect of preventing devitrification of the discharge vessel. As an example of the numerical value of the lamp, 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 arc tube inner volume 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.

As an example of the numerical value of the lamp, for example, AC lighting is performed at a maximum outer diameter of the light emitting portion 11 of 1.0 mm, a distance between electrodes of 1.0 mm, an arc tube inner volume of 75 mm ³ , a rated voltage of 70 V, and a rated power of 200 W.
In addition, this type of discharge lamp is built in a projector apparatus that is miniaturized, and requires a large amount of light emission while requiring an extremely small overall size. 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 . When such a high mercury vapor pressure or tube wall load value is mounted on a presentation device such as a projector device or an overhead projector, light with good color rendering can be provided. The discharge lamp is not limited to AC lighting, and may be DC lighting.

A projection is formed at the tip of the electrode 2 (the end facing the other electrode) as the lamp is turned on. The phenomenon in which the protrusion is formed is not necessarily clear, but is estimated as follows. That is, tungsten (electrode constituent material) evaporated from the high temperature portion near the electrode tip during lamp operation is combined with halogen and residual oxygen present in the arc tube. For example, if the halogen is Br, WBr, WBr ₂ , WO, It exists as tungsten compounds such as WO ₂ , WO ₂ Br, and WO ₂ Br ₂ . These compounds are decomposed into tungsten atoms or cations at a high temperature portion in the gas phase near the electrode tip. Temperature diffusion (high-temperature part in the gas phase = from the arc to low-temperature part = diffusion of tungsten atoms toward the tip of the electrode) and when tungsten atoms ionize into cations in the arc and operate as a cathode It is considered that the tungsten vapor density in the gas phase in the vicinity of the electrode tip is increased by being attracted (drift) toward the cathode by the electric field, and is deposited on the electrode tip to form a protrusion.

FIG. 6 is a schematic diagram showing electrode tips and protrusions. The electrode 2 includes a sphere portion 2a and a shaft portion 2B, 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 lamp, it is formed spontaneously by so-called 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. In the short arc type discharge lamp, as the lamp is lit, the protrusion 2b is formed, and an arc is formed between the protrusions 2b.
Thus, since the lamp | ramp of this invention has the processus | protrusion formed in the electrode, it is given so that infrared light (IR) may not be irradiated.

  The main reflecting mirror MR, the auxiliary reflecting mirror SR, and the lens ML are not particularly limited to the above embodiments as long as they can reflect and transmit the radiated light from the lamp. 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 base material is borosilicate glass, quartz glass or the like. The reason why heat resistance is required is that when the lamp is lit, the main reflecting mirror MR is at a high temperature of about 400 ° C. and the auxiliary mirror SR is at 800 ° C. or higher. In addition, the reason why strength resistance is required is that the shape does not change when the projector device is placed in close proximity to other electrical and optical components, or if the lamp is damaged, it will be damaged as well. This is to prevent it from happening.

  The lens ML is preferably separated from the front opening of the main reflecting mirror MR. This is because cooling air can be blown toward the sealing portion 12 b of the lamp 10. Although it is conceivable to attach glass or the like to the front opening of the main reflecting mirror MR, it is not desirable because the entire optical device becomes large.

  When the main reflector MR, the auxiliary reflector SR, and the lens ML are configured to reflect ultraviolet light having a wavelength of 380 to 420 nm, the light output is improved by 7% as compared with a conventional device that transmits ultraviolet light. It was confirmed that Further, when the main reflector MR, the auxiliary reflector SR, and the lens ML are configured to reflect ultraviolet light having a wavelength of 300 to 420 nm, the light output is improved by 10% as compared with a conventional device that transmits ultraviolet light. It was confirmed that

As described above, the present invention has the following effects.
(1). By returning the ultraviolet light of the light emitted from the mercury lamp to the light emitting part of the lamp, the light emission of the lamp can be enhanced. This is because the ultraviolet light can be absorbed by mercury vapor so that the temperature of the light emitting part can be increased as a whole.
(2). Further, infrared light out of the light emitted from the mercury lamp is prevented from returning to the lamp, so that the problem that the electrode is locally heated and worn can be solved.

1 shows the overall structure of an optical device according to the present invention. The progress of light in the optical device according to the present invention is shown. The conceptual structure of the lamp light emission part of the optical apparatus which concerns on this invention is shown. 1 shows an embodiment of a lens of an optical device according to the present invention. 1 shows an enlarged structure of a lamp of an optical device according to the present invention. The schematic diagram of the electrode of the lamp | ramp of the optical apparatus which concerns on this invention is shown. 1 shows a conventional optical device.

Explanation of symbols

10 Lamp MR Main reflector SR Auxiliary reflector ML Lens

Claims (9)

A short arc type mercury lamp comprising a light emitting part having a pair of electrodes and sealing parts provided at both ends of the light emitting part;
A main reflector made of a spheroid arranged so as to surround the mercury lamp in a state where the arc direction of the short arc type mercury lamp coincides with the optical axis and the first focal point is formed between the electrodes,
Attached to the sealing part arranged on the opening side of the main reflecting mirror among the sealing parts, and for reflecting again the light emitted directly from the mercury lamp to the opening side of the main reflecting mirror toward the main reflecting mirror Auxiliary reflectors,
An optical device comprising:
Both the main reflecting mirror and the auxiliary reflecting mirror reflect ultraviolet light and visible light, but transmit infrared light, among the radiated light of the mercury lamp,
Further, among the light from the main reflector, visible light is transmitted but ultraviolet light is reflected, and a lens having a curved incident surface of the light is more main than the second focal position of the main reflector. An optical device arranged at a position close to a reflecting mirror.   The optical apparatus according to claim 1, wherein the lens is configured so that light from the main reflecting mirror enters vertically.   The optical apparatus according to claim 1, wherein the lens is a meniscus lens.   2. The optical apparatus according to claim 1, wherein the auxiliary reflecting mirror is constituted by a spherical reflecting mirror.   The virtual surface (MR-VS) formed by the opening edge of the main reflecting mirror and the virtual surface (SR-VS) formed by the opening edge of the auxiliary reflecting mirror substantially coincide with each other. 1. Optical device. 2. The optical apparatus according to claim 1, wherein the short arc type mercury lamp has 0.15 mg / mm ³ or more of mercury sealed in a light emitting portion.   2. The optical apparatus according to claim 1, wherein the short arc type mercury lamp has a gap between a pair of electrodes of 0.5 to 2.0 mm. 2. The optical apparatus according to claim 1, wherein the short arc type mercury lamp has 5 × 10 ^{−5 to} 7 × 10 ⁻³ μmol / mm ³ halogen sealed in a light emitting portion.   9. The optical apparatus according to claim 8, wherein the short arc type mercury lamp has a protrusion formed at a tip of an electrode.

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