JP3494092B2 - Optical device and liquid crystal projector including the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device and a liquid crystal projector including the optical device.

[0002]

2. Description of the Related Art Generally, in an optical device used in a device such as a liquid crystal projector, light emitted from a light source lamp is efficiently converted into light parallel to an optical axis (hereinafter also referred to as "parallel light"). Then, it is necessary to have the ability to irradiate the irradiated area (hereinafter, simply referred to as “irradiated area”) of the irradiated object such as a liquid crystal display panel. Usually, one example of such an optical device is composed of a short arc type discharge lamp and a concave reflecting mirror for converting light emitted from the discharge lamp into parallel light. In recent years, there has been a demand for miniaturization of liquid crystal projectors, so it is necessary to miniaturize the optical device used in the liquid crystal projector. Further, the liquid crystal display panel itself, which is an irradiation target, is also downsized, which is one of the reasons why the downsizing of the optical device is required.

FIG. 3 is an explanatory view showing an example of the configuration of a conventional optical device. The optical device 60 of this example is configured by incorporating a short arc type discharge lamp 61 into a parabolic reflector 66. The discharge vessel of the short arc type discharge lamp 61 is composed of a roughly spherical arc tube portion 62 and rod-shaped sealing portions 63 that extend from both ends of the arc tube portion 62. The cathode 64 and the anode 65 are arranged to face each other. In FIG. 3, 67 is a front opening of the parabolic reflector 66, and 68 is a central through hole.

In the short arc type discharge lamp 61, the arc direction thereof coincides with the optical axis L of the parabolic reflector 66, and the arc bright spot A formed between the cathode 64 and the anode 65 is parabolic reflected. It is arranged so as to match the focal point of the mirror 66.
On the other hand, a dielectric multilayer reflective film (not shown) is formed on the inner surface of the parabolic reflector 66.

In this optical device 60, a rear area located behind (left in the figure) a virtual straight line N connecting an arbitrary point M on the front outer edge of the parabolic reflector 66 and the arc bright point A, That is, of the light emitted toward the area of the solid reception angle θ of the parabolic reflection mirror 66 centered on the arc bright point A, except the light transmitted through the central through hole 68, the parabolic reflection mirror 66 is used. The reflected light becomes parallel light that is parallel to the optical axis L and is projected onto the irradiation area.

In order to reduce the size of the optical device 60 as described above, the length of the parabolic reflector 66 in the direction of the optical axis L may be reduced. In that case, the light receiving solid angle θ is small. And the amount of reflected light decreases. However, if an attempt is made to reduce the diameter of the front opening portion 67 (hereinafter, referred to as “aperture diameter”) while securing the same stereoscopic light receiving angle θ, the parabolic reflector 66 has a length in the optical axis L direction. The ratio of the opening diameters becomes small, and it becomes a so-called deep type.

However, when the parabolic reflector 66 is of a deep type, the curvature variation of the parabolic reflector 66 is large, so that a dielectric multilayer reflective film is deposited on its inner surface by vapor deposition. It is difficult to form, and the parabolic reflector 66
When it is made of crystallized glass or the like, it becomes difficult to polish the inner surface of the parabolic reflecting mirror 66, and as a result, good reflection characteristics cannot be obtained. Further, since the focal length of the parabolic reflector 66 becomes small, the shortest distance between the arc bright spot A and the arc tube portion 62 and the parabolic reflector 66 becomes small. Therefore, the parabolic reflector 66 concerned. Has a problem that it may be damaged as a result of being heated by the arc bright spot A and the heat from the arc tube portion 62.

In general, the wavelength characteristic of the light reflected by the parabolic reflector 66 (hereinafter also referred to as "reflected light") is the light emitted from the arc tube portion 62 (hereinafter also referred to as "radiated light"). .) Of the parabolic reflector 66 with respect to the inner surface of the parabolic reflector 66. Therefore, when the parabolic reflector 66 is of a deep type, the emitted light in the vicinity of the front opening 67 of the inner surface of the parabolic reflector 66 and the central portion of the parabolic reflector 66. Since the difference in the incident angle between the radiated light and the radiated light is large, the wavelength characteristics of the reflected light due to them are significantly different, and as a result, it is not possible to irradiate the illuminated area with light having uniform wavelength characteristics. , There is a problem.

As a result of downsizing the optical device 60,
The arc tube 6 with respect to the size of the opening diameter of the parabolic reflector 66
When the ratio of the two is large, the proportion of the light reflected by the parabolic reflector 66 is blocked by the arc tube portion 62 is high, so that the amount of light to be lost is increased, and as a result, the utilization of the emitted light is increased. There is a problem of reduced efficiency.

Further, in the above optical device 60, since the short arc type discharge lamp 61 is arranged so that the optical axis L of the parabolic reflecting mirror 66 and the arc direction coincide with each other, the light from the light source device 60 concerned is emitted. However, due to the presence of the short arc type discharge lamp 61, the short-arc type discharge lamp 61 forms a cylindrical state and irradiates the irradiated area, and as a result, a ring-shaped light mark is generated in the irradiated area (hereinafter, this is referred to as “a hollow defect”). That is the problem).

As described above, with the miniaturization of the optical device 60, the above various problems occur.

On the other hand, the short arc type discharge lamp 61
It is originally preferable that the light be turned on in a vertical state in which the arc direction is the vertical direction. From this, for example, an optical device 70 having a structure as shown in FIG. 4 is also proposed. This optical device 70 includes a short arc type discharge lamp 61,
A parabolic reflector 66 arranged so that the optical axis L coincides with the arc direction of the short arc type discharge lamp 61;
The parabolic reflector 66 is configured by a plane reflector 71 that reflects light reflected in a vertical direction (left and right direction in the drawing).

However, in such an optical device 70, since the plane reflection plate 71 is indispensable, there is a problem that the height of the entire device becomes large and it is difficult to achieve miniaturization.

[0014]

SUMMARY OF THE INVENTION The present invention has been made under the circumstances described above, and an object thereof is to achieve a small size and to improve the utilization efficiency of light emitted from a short arc type discharge lamp. It is to provide an optical device which is expensive and has a long service life. Another object of the present invention is to provide a liquid crystal projector including the above optical device.

[0015]

The optical device of the present invention comprises a reflector, a short arc type discharge lamp arranged so that the optical axis of the reflector is orthogonal to the arc direction, and the short arc type discharge lamp. An optical device comprising a condenser lens arranged in front of a spherical arc tube portion, wherein the reflector is a spherical reflection portion arranged behind an arc bright point of a short arc discharge lamp, and the spherical reflection portion. It consists of an annular parabolic reflector that reflects the light emitted to the outside of the condenser and projects the reflected light parallel to the optical axis.
The reflective film that reflects the light emitted toward the
Formed on the front outer surface of the arc tube of the arc discharge lamp.
It is characterized by

[0016]

Further, in the optical device of the present invention, it is preferable that the spherical reflecting portion is a spherical reflecting mirror disposed behind the arc bright spot of the short arc type discharge lamp.

A liquid crystal projector according to the present invention is characterized by including the above optical device.

[0019]

According to the above construction, the short arc type discharge lamp is arranged so that the optical axis of the reflector is orthogonal to the arc direction, and the reflector is composed of the spherical reflecting portion and the parabolic reflecting portion. Since the reflector has a form along the rear side wall of the arc tube part,
The shape of each of the spherical reflecting portion and the parabolic reflecting portion is close to a flat shape, which makes it possible to reduce the length of the entire device in the optical axis direction, and ultimately to reduce the size of the entire optical device. can do.

Further, since the spherical reflecting portion reflects the light emitted from the arc bright spot and returns the reflected light to the arc region,
The brightness of the arc can be increased, and the parabolic reflector reflects the light emitted to the outside of the spherical reflector and can project the reflected light in a direction parallel to the optical axis. It is possible to prevent the loss of the amount of emitted light, and as a result, it is possible to increase the utilization efficiency of the light emitted from the short arc type discharge lamp.

Further, since it is not necessary to bring the reflector and the arc luminescent spot close to each other, a sufficient separation distance between the arc luminescent spot and the reflector is ensured, so that the reflector is damaged by heat from the arc luminescent spot. It can be effectively prevented, resulting in a long service life.

Since the specific reflection film is formed on the arc tube portion of the short arc type discharge lamp ,
The light that should pass through the tube wall of the arc tube is also reflected back to the arc bright spot, and as a result, of the light emitted in the front area,
Since the light other than the light projected by the condenser lens can be converted into parallel light by the reflector, the light utilization efficiency can be further increased.

In the liquid crystal projector of the present invention,
Since the above optical device is provided, the entire liquid crystal projector can be made small.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The optical device of the present invention will be described in detail below. FIG. 1 is an explanatory sectional view showing an example of the configuration of the optical device of the present invention. The optical device 1 of this example is
The reflector 10, the short arc type discharge lamp 20 arranged so that the arc direction is orthogonal to the optical axis L extending in the horizontal direction of the reflector 10, and in front of the short arc type discharge lamp 20, arranged on the optical axis L. And the condenser lens 30 that is formed.

Reflector 10 which constitutes the optical device 1.
Is a spherical reflecting mirror 11 made of glass, for example, which is arranged on the optical axis L on the rear side of the arc bright spot A of the short arc type discharge lamp 20, and the light emitted to the outside of the spherical reflecting mirror 11. It is composed of an annular parabolic reflector 12 that reflects and projects the reflected light in a direction parallel to the optical axis L. The parabolic reflector 12 has a front opening portion 13 for disposing the short arc type discharge lamp 20, and a rear opening portion 14 thereof is provided so as to be in contact with an outer peripheral edge portion of the spherical reflecting mirror 11. There is.

On the inner surface of the reflector 10, for example, a dielectric multilayer reflection film (not shown) formed by laminating titanium oxide (TiO ₂ ) and silica (SiO ₂ ) is formed.

The short arc type discharge lamp 20 is composed of a discharge vessel made of, for example, quartz glass, and a cathode 23 and an anode 24 arranged therein. The discharge vessel is an arc tube portion 21 and the arc tube portion 21. And a rod-shaped sealing portion 22 that is continuously provided so as to extend from both ends to the outside. In the arc tube portion 21, a cathode 23 and an anode 24
Are arranged so as to face each other in the vertical direction, and an electrode rod 25 having a cathode 23 or an anode 24 at its tip extends inside the sealing portion 22 and is provided with its rear end protruding from the sealing portion 22. The sealing portion 22 and the electrode rod 25 are welded together to form an airtight seal portion.

Further, a specific outer front surface of the arc tube portion 21 is specified.
The area is directed outward in the radial direction of the condenser lens 30.
Reflects light that was once emitted, eg titanium oxide (T
iO ₂) And silica (SiO₂) And dielectric
Body multilayer reflective film, or gold made of platinum or rhodium
An annular reflective film 26 such as a metal reflective film is formed.

In the short arc type discharge lamp 20, the arc direction thereof is orthogonal to the optical axis L of the reflector 10, and the arc luminescent spot A coincides with the center of the spherical reflecting mirror 11 and the parabolic reflecting mirror. It is incorporated in the reflector 10 so as to match the focal point of 12.

The arc tube portion 21 constituting the short arc type discharge lamp 20 has a spherical shape, and its center coincides with the arc bright point A.

In the reflector 10, the diameter of the front opening 13 of the parabolic reflector 12 is, for example, 30 to 60 m.
m, the diameter of the rear opening portion 14 of the parabolic reflector 12 is, for example, 8 to 20 mm, and the outer diameter of the spherical reflector 11 is, for example, 8 to 2.
It is 0 mm. In the short arc type discharge lamp 20, the total length is, for example, 40 to 75 mm, the outer diameter of the arc tube portion 21 is, for example, 7 to 14 mm, the distance between the cathode 23 and the anode 24 is, for example, 1 to 3 mm, and the length of the sealing portion 22. Is, for example, 10
It is 20 mm. The outer diameter of the condenser lens 30 is, for example, 8 to 20 mm, and preferably coincides with the outer diameter of the spherical reflecting mirror 11 (the diameter of the rear opening portion 14).

In the optical device 1, of the light emitted to the area behind the arc bright spot A of the short arc type discharge lamp 20, the light in the central area is reflected by the spherical reflecting mirror 11 to reach the arc bright spot A. It is returned to increase the brightness of the arc, or is transmitted through the arc region and projected by the condenser lens 30 in a direction parallel to the optical axis L. Also, of the light emitted in the area behind the arc bright spot A, the spherical reflecting mirror 11
The light radiated toward the outside of is reflected by the parabolic reflector 12 and projected in a direction parallel to the optical axis L.

Of the light emitted to the area in front of the arc bright spot A of the short arc type discharge lamp 20, the light in the central area is projected by the condenser lens 30 in the direction parallel to the optical axis L. Of the light emitted in the area in front of the arc bright spot A, the light emitted toward the outside of the condenser lens 30 is reflected by the reflection film 26 formed on the outer surface of the arc tube portion 21. The light is returned to the arc bright spot A to enhance the brightness of the arc or to pass through the arc region and projected by the parabolic reflector 12 in a direction parallel to the optical axis L.

According to the above optical device 1, the short arc type discharge lamp 20 is arranged so that the optical axis L of the reflector 10 and the arc direction are orthogonal to each other, and the reflector 1 is also provided.
Since 0 is composed of the spherical reflecting mirror 11 and the parabolic reflecting mirror 12, the reflector 10 has the arc tube portion 2
Since each of the spherical reflecting mirror 11 and the parabolic reflecting mirror 12 has a shape close to a flat shape, the length of the entire apparatus in the optical axis L direction can be reduced. Can be reduced, and in the end, the entire optical device 1 can be reduced in size.

Further, since the spherical reflecting mirror 11 reflects the emitted light from the arc bright spot A and returns the reflected light to the arc region, the brightness of the arc can be increased and the parabolic reflecting mirror 12 Since the light emitted to the outside of the spherical reflecting mirror 11 can be reflected and the reflected light can be projected in the direction parallel to the optical axis L, it is possible to prevent the loss of the amount of emitted light. As a result, the utilization efficiency of the light emitted from the short arc type discharge lamp 20 can be increased.

Further, according to the above-mentioned optical device 1, the following effects can be obtained depending on the positional relationship between the reflector 10 and the short arc type discharge lamp 20 and the configuration of the reflector 10. Since it is not necessary to bring the reflector 10 and the arc bright spot A close to each other, a sufficient separation distance between the arc bright spot A and the reflector 10 is ensured, and therefore the reflector 10 is damaged by heat from the arc bright spot A. Can be effectively prevented, resulting in a long service life.

Since the fluctuation range of the curvature of the reflector 10 is small, it becomes easy to form a dielectric multilayer reflection film having good reflection characteristics on its inner surface by vapor deposition, and
When the reflector 10 is made of crystallized glass, the inner surface of the reflector 10 can be easily polished.

Since the incident angle of the radiated light on the inner surface of the reflector 10 is almost the same at any point on the inner surface, the wavelength characteristic of the reflected light is highly uniform,
As a result, it is possible to irradiate the irradiated area with light having a uniform wavelength characteristic.

Since the short arc type discharge lamp 20 is arranged so that the optical axis L of the reflector 10 and the arc direction are orthogonal to each other, when the light from the optical device 1 is applied to the irradiation area, the irradiation area is irradiated onto the irradiation area. It is possible to prevent the occurrence of the hollow defect.

In the above example, the arc tube portion 2
In addition to making the shape of 1 a spherical shape, the electrode is arranged at an appropriate position with high accuracy with respect to the arc tube portion 21 so that the arc bright point A is aligned with the center of the arc tube portion 21 and Since the specific reflection film 26 is formed on the front outer surface, the light that should pass through the tube wall of the arc tube portion 21 in this region is also reflected and returned to the arc bright spot A.
Since most of the light emitted to the front area can be made into parallel light by the reflector 10, the light utilization efficiency can be further increased.

On the other hand, if the entire reflector is composed of only the spherical reflecting mirror, the light emitted from the short arc type discharge lamp is reflected by the spherical reflecting mirror and returned to the arc bright spot. When the light returned to the arc bright spot is transmitted through the front tube wall of the arc tube section, it is necessary to enlarge the condenser lens in order to make this light parallel to the optical axis. Can't be small.

In the above-described optical device 1, the case where the reflector 10 in which the spherical reflecting portion is the spherical reflecting mirror 11 and the parabolic reflecting portion is the parabolic reflecting mirror 12 is used has been described. It is not limited to this,
For example, the spherical reflector is the outer surface on the rear side of the arc tube, and is reflected at the position where the reflected light can be incident on the condenser lens 30 by reflecting the emitted light from the arc bright spot. It is also possible to employ a structure composed of a film.

FIG. 2 is an explanatory view showing an example of a liquid crystal projector provided with the above optical device 1. In this figure, 1 is an optical device, 31 is a support plate for supporting the condenser lens 30, 40 is a front glass, 41a is a first optical integrator lens, 41b is a second optical integrator lens, 42 is a polarization beam splitter, 43 Is the second condenser lens, 44 is 1
/ 2 phase difference plate, 45a is a first aluminum mirror, 45b is a second aluminum mirror, 45c is a third aluminum mirror, 4
6a is a first dichroic mirror, 46b is a second dichroic mirror, 47 is a relay lens, 48 is a field lens, 49 is a liquid crystal display panel, 50 is a color combining cross prism, 51 is a projection lens, and 52 is a screen.

Since the liquid crystal projector described above is provided with the optical device 1, the entire liquid crystal projector can be made compact, and the following effects can be obtained. As a result of the collimated light having better optical characteristics than the optical device 1 being projected, the illuminance of the image projected on the screen 52 can be increased, and the occurrence of the hollow defect in the illuminated area of the liquid crystal display panel 49 is prevented. Can be prevented.

[0045]

EXAMPLES Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto. Example 1 An optical device (1) of the present invention was manufactured according to the configuration shown in FIG. The short arc type discharge lamp (20) of this optical device (1) has a rated power consumption of 180
W is a super high pressure mercury lamp with a rated voltage of 110 V, a distance between electrodes of 2.0 mm, and an operating pressure of 13 MPa. The arc tube part (21) has an outer diameter of 11.5 mm and an inner diameter of 7 mm.
It has a spherical shape of mm. In the reflector (10), the diameter of the front opening portion (13) of the parabolic reflecting mirror (12) is 50 mm, the diameter of the rear opening portion (14) is 12 mm, and the outer diameter of the spherical reflecting mirror (11) is. It is 12 mm. The condenser lens (30) has an outer diameter of 12.0 mm.

Comparative Example 1 A comparative optical device (60) was manufactured according to the structure shown in FIG. This optical device (6
The short arc type discharge lamp (61) of 0) is the same as the short arc type discharge lamp (20) used in Example 1. The parabolic reflector (66) has an opening diameter (diameter of the front opening portion (67)) of 60 mm and a central through hole (68).
Has a diameter of 12 mm.

When each of the optical device of the present invention and the optical device for comparison was operated, the optical device of the present invention could be used for 1000 hours without damaging the reflector made of borosilicate glass. . On the other hand, in the comparative optical device, the borosilicate glass reflector was damaged after only 100 hours of use. Further, while the wavelength of the light from the optical device of the present invention is uniform, the wavelength of the light from the optical device for comparison is not constant, and there is considerable variation.

[0048]

As described above, according to the optical device of the present invention, the short arc type discharge lamp is arranged so that the optical axis of the reflector and the arc direction are orthogonal to each other, and the reflector has a spherical reflecting portion and a parabolic surface. Since the reflector has a shape along the rear side tube wall of the arc tube section because it is configured by the reflecting section, the shape of each of the spherical reflecting section and the parabolic reflecting section becomes close to a flat surface. As a result, the length of the entire device in the optical axis direction can be reduced, and as a result, the entire optical device can be made compact.

Further, since the spherical reflecting portion reflects the radiation light from the arc bright spot and returns the reflected light to the arc region,
The brightness of the arc can be increased, and the parabolic reflector reflects the light emitted to the outside of the spherical reflector and can project the reflected light in a direction parallel to the optical axis. It is possible to prevent the loss of the amount of emitted light, and as a result, it is possible to increase the utilization efficiency of the light emitted from the short arc type discharge lamp.

Furthermore, since it is not necessary to bring the reflector and the arc bright spots close to each other, a sufficient separation distance between the arc bright spot and the reflector is ensured, so that the reflector may be damaged by heat from the arc bright spot. It can be effectively prevented, resulting in a long service life.

Since the arc tube portion of the short arc type discharge lamp is provided with a specific reflection film ,
The light that should pass through the tube wall of the arc tube is also reflected back to the arc bright spot, and as a result, of the light emitted in the front area,
Since the light other than the light projected by the condenser lens can be converted into parallel light by the reflector, the light utilization efficiency can be further increased.

According to the liquid crystal projector of the present invention, since the above optical device is provided, the liquid crystal projector as a whole can be made small.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view showing an example of the configuration of an optical device of the present invention.

FIG. 2 is an explanatory diagram showing an example of a liquid crystal projector including an optical device.

FIG. 3 is an explanatory diagram showing an example of the configuration of a conventional optical device.

FIG. 4 is an explanatory diagram showing another example of the configuration of a conventional optical device.

[Explanation of symbols]

1 Optical device 10 reflector 11 Spherical reflector 12 Parabolic reflector 13 Front opening 14 Rear opening 20 Short arc type discharge lamp 21 arc tube 22 Sealing part 23 cathode 24 Anode 25 electrode rod 26 Reflective film 30 condenser lens 31 Support plate 40 Front glass 41a 1st optical integrator lens 41b Second Optical Integrator Lens 42 Polarizing beam splitter 43 Second condenser lens 44 1/2 phase plate 45a First aluminum mirror 45b second aluminum mirror 45c Third aluminum mirror 46a First dichroic mirror 46b Second dichroic mirror 47 relay lens 48 field lens 49 LCD display panel 50 colors synthetic cross prism 51 Projection lens 52 screen 60 Optical device 61 Short arc type discharge lamp 62 arc tube 63 Sealing part 64 cathode 65 Anode 66 Parabolic reflector 67 Front opening 68 Central through hole 70 Optical device 71 Flat reflector

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 2000-122178 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03B 21/00-21/30

Claims (3)

(57) [Claims] 1. A reflector, a short arc type discharge lamp arranged such that an optical axis of the reflector is orthogonal to an arc direction, and a short arc type discharge lamp arranged in front of a spherical arc tube portion constituting the short arc type discharge lamp. In an optical device comprising a condenser lens, the reflector is a spherical reflecting portion arranged behind the arc bright spot of the short arc type discharge lamp, and reflects the light emitted to the outside of the spherical reflecting portion. be more parabolic reflecting portion of the annular parallel projected to the optical axis of the reflected light is radiated outward in the radial direction of the condenser lens
A short arc type discharge lamp with a reflective film that reflects light
An optical device, which is formed on the outer surface on the front side of the arc tube portion of . 2. The spherical reflecting portion is a short arc type discharge laser.
Of a spherical reflector placed behind the arc bright spot of the pump.
The optical device according to claim 1, wherein: 3. The optical device according to claim 1 or 2.
A liquid crystal projector, which is characterized in that it is provided with a device.