JPH10133198A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a lens array small-sized and sufficiently improve the light utilization efficiency even when a liquid crystal panel with microlenses is adopted by using an elliptic surface mirror as a reflector which reflects the illumination light from a light source and providing a concave lens surface between the reflector and a lens array behind it. SOLUTION: The illumination light from a metal halide lamp 1 as the light source is made incident on a 1st lens array 4 through a lamp reflector 3. Here, a lamp reflector 5 is the elliptic surface mirror, and the 1st lens array has the concave lens as its incidence surface 7 and converts the converged light 8 from the lamp reflector 3 into nearly parallel light. The projection light 9 from the 1st lens array 4 passes through an increased reflection silver mirror 10 and a 2nd lens array 11 and made incident on a dichroic mirror 12, which reflects its B color light 13 and transmits G and R color light 14. Then the light is made incident on a liquid crystal panel 18 for B color light and a liquid crystal panel 24 for G color light through a condenser lens, a polarizing plate, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for irradiating illumination light from a light source to a liquid crystal panel via a reflector, a first lens array, and a second lens array, and emitting light from the liquid crystal panel through a projection lens. The present invention relates to a liquid crystal projector that projects on a screen.

[0002]

2. Description of the Related Art A liquid crystal projector using a transmission type liquid crystal panel of this type is disclosed in, for example, JP-A-63-2160.
As disclosed in the drawing of JP-A No. 26, the light source (21
, A first reflecting mirror (corresponding to 23), a first dichroic mirror (corresponding to 26), a second reflecting mirror (corresponding to 30), a second dichroic mirror (corresponding to 27), a third Reflection mirror (equivalent to 28), fourth reflection mirror (equivalent to 29), and a first transmission type liquid crystal panel (3).
3), a second transmissive liquid crystal panel (corresponding to 39), a third transmissive liquid crystal panel (corresponding to 45), a dichroic prism (corresponding to 49), a projection lens (50).
The illumination light from the light source is incident on the first dichroic mirror via the first reflection mirror, and the first outgoing light color-separated by the first dichroic mirror is subjected to the second reflection. The first liquid crystal panel is radiated through the mirror, the second outgoing light color-separated by the first dichroic mirror is made incident on the second dichroic mirror, and the first light that is color-separated by the second dichroic mirror. Outgoing light is made incident on the second liquid crystal panel, and the second outgoing light color-separated by the second dichroic mirror is irradiated on the third liquid crystal panel via the third reflecting mirror and the fourth reflecting mirror. And the transmitted light from the first liquid crystal panel,
The light transmitted from the liquid crystal panel and the light transmitted from the third liquid crystal panel are color-combined by a dichroic prism, and the color-combined outgoing light is projected on a screen by a projection lens.

Further, as disclosed in, for example, JP-A-3-10218, an exhaust fan (1) for cooling a light source is disclosed.
5 and 27) are known.

[0004] For example, 22Fa0 of JAPAN OPTICS '94, Hamamatsu '94 (p135-p136), organized by Japan Optical Society (Reaction Society).
6. As disclosed in "High Efficiency Illumination Optical System for Liquid Crystal Projector Using Deformed Aperture Lens Array", a metal halide lamp and a parabolic mirror are used as a light source, a UV-IR cut filter, a first lens array, One provided with a two-lens array is known.

A liquid crystal projector having a configuration combining the above three known examples has been put to practical use. Hereinafter, a liquid crystal projector that combines this conventional technique will be described in detail with reference to the drawings.

FIG. 6 is a top view of a liquid crystal projector optical system obtained by combining the conventional techniques.

Illumination light 51 from a metal halide lamp 50, which is a light source, is applied to lamp reflectors 52, U of a parabolic mirror.
V-IR cut filter 53, first lens array 54,
A cold mirror 55 serving as a first reflecting mirror, a second lens array 56, and a dichroic mirror 5 serving as a first dichroic mirror for transmitting R color light and reflecting G and B light.
7, the R color light 58 is transmitted, and the G and B color lights 59
Is reflected.

The R-color light 58 is reflected by a reflective aluminum mirror 60 which is a second reflecting mirror, and is reflected by the condenser lens 6.
1, through a polarizing plate 62, is incident on a liquid crystal panel 63 for R color light, which is a first transmission type liquid crystal panel.

The G and B color lights 59 are incident on a G dichroic mirror 64 which is a second dichroic mirror that reflects and transmits G color light, where the G color light 65 is reflected and the B color light 66 is transmitted. The G color light 65 passes through the condenser lens 6
7. The light enters a G-color light liquid crystal panel 69, which is a second transmission type liquid crystal panel, via a polarizing plate 68.

The B-color light 66 is supplied to a relay lens 70, a third reflection mirror, an increased reflection aluminum mirror 71, a relay lens 72, and a fourth reflection mirror, an increased reflection aluminum mirror 7
3, via the condenser lens 74 and the polarizing plate 75,
To the liquid crystal panel 76 for B color light, which is a transmission type liquid crystal panel.

The R transmitted light 77 from the liquid crystal panel 63, the G transmitted light 78 from the liquid crystal panel 69, and the B transmitted light 79 from the liquid crystal panel 76 are color-combined by a dichroic prism 80, and the emitted light is color-combined. 81 to projection lens 8
2 project onto a screen (not shown).

An exhaust fan 83 for cooling the light source is arranged in the vicinity of the metal halide lamp 50 and the lamp reflector 52 so as to prevent heat generated from the light source having a high temperature from affecting components other than the light source. The hot air 8 is placed outside the housing (not shown) of the liquid crystal projector.
Exhaust 4

According to the liquid crystal projector having this configuration, the liquid crystal panels 63 and 6 are formed by the optical integrator configuration of the first lens array 54 and the second lens array 56.
The uniform illumination light is radiated to 9, 76, and a bright large-screen image with uniform peripheral illuminance on the screen is obtained.

[0014]

However, in a conventional liquid crystal projector of this configuration, the reflector 5
2 is a parabolic mirror, so that parallel light is incident on the first lens array 54 and the first lens array 54 and the cold mirror 5
5, second lens array 56, dichroic mirror 57
There was a problem that it became large.

Also, no consideration has been given to the problem that the light utilization efficiency does not improve when a liquid crystal panel with microlenses is employed because the second lens array 56 is large.

FIG. 7 shows a liquid crystal panel 8 with microlenses.
5 is a sectional view of FIG. Even if the parallel light 86 is completely incident on the liquid crystal panel 85, the light is emitted from the liquid crystal panel as divergent light 88 having an angle a due to the action of the microlens 87. However, since the divergent light 88 passes through the pixel opening 90 without being blocked by the black matrix 89,
The effective aperture ratio of the liquid crystal panel is improved, and the light use efficiency is improved.

FIG. 8 shows a second lens array 56 optimally designed for a liquid crystal panel 91 without a micro lens.
FIG. 6 is a ray diagram from to the projection lens aperture 92. It can be seen that the incident angle b and the outgoing angle c of the liquid crystal panel 91 are designed to be equal.

FIG. 9 shows a liquid crystal panel 8 with microlenses.
5 is a ray diagram from the second lens array 56 to the projection lens aperture 92 when No. 5 is adopted. Since the emission angle c of the liquid crystal panel 85 is increased by the divergence angle a described with reference to FIG. Usage efficiency does not improve much.

It is an object of the present invention to propose a configuration of an optical system capable of sufficiently improving the light use efficiency even when a lens array is downsized and a liquid crystal panel with micro lenses is employed.

[0020]

In order to achieve the above object, according to the present invention, the reflector is an ellipsoidal mirror, and a concave lens surface is provided between the reflector and the second lens array.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a top view of a liquid crystal projector optical system according to a first embodiment of the present invention.

Illumination light 2 from a metal halide lamp 1 as a light source passes through a lamp reflector 3 of an ellipsoidal mirror.
The light enters the first lens array 4. Here, the lamp reflector 5 of the spherical mirror is provided for the purpose of returning the previously unused illumination light 6 from the metal halide lamp 1 to the metal halide lamp 1 to reuse the light.

The first lens array 4 has a function of converting the convergent light 8 from the lamp reflector 3 of the ellipsoidal mirror into a substantially parallel light by making the entrance surface 7 a concave lens surface. Was made smaller.

The outgoing light 9 from the first lens array 4 is reflected by a silver mirror 10 as a first reflecting mirror, a second lens array 11, a B-color light reflection as a first dichroic mirror, and G and B-color light transmission. Dichroic mirror 12
, The B color light 13 is reflected, and the G and R color lights 14 are transmitted. The B-color light 13 is reflected by a reflection-enhancing aluminum mirror 15 as a second reflection mirror, and is reflected by the condenser lens 1.
6. The light is incident on a B-color light liquid crystal panel 18, which is a first transmission type liquid crystal panel, via a polarizing plate 17. The G and R color lights 14 are incident on a dichroic mirror 19 which is a second dichroic mirror, which reflects G light and transmits R light.
The G light 20 is reflected and the R light 21 is transmitted. G color light 2
Reference numeral 0 denotes a liquid crystal panel 24 for G color light, which is a second transmission type liquid crystal panel, via a condenser lens 22 and a polarizing plate 23.
Incident on.

The R-color light 21 is transmitted through a relay lens 25 and a cold mirror 2 that transmits infrared light, which is a third reflection mirror.
6, through a relay lens 27, an enhanced reflection silver mirror 28 as a fourth reflection mirror, a condenser lens 29, and a polarizing plate 30, the light is incident on an R color light liquid crystal panel 31 as a third transmission type liquid crystal panel.

The B transmitted light 32 from the liquid crystal panel 18, the G transmitted light 33 from the liquid crystal panel 24, and the R transmitted light 34 from the liquid crystal panel 31 are color-combined by a dichroic prism 35, and the emitted light is color-combined. 36 is the projection lens 3
7, the image is projected on a screen (not shown).

In order to prevent heat generated from the light source having a high temperature from affecting components other than the light source, exhaust for cooling the light source is provided in the vicinity of the metal halide lamp 1, the lamp reflector 3 and the lamp reflector 5, which are light sources. Fan 38
Are disposed, and the hot air 39 is exhausted outside a housing (not shown) of the liquid crystal projector.

In this embodiment, the first outgoing light 13 separated by the first dichroic mirror 12 is the reflected light of the first dichroic mirror 12, and the second outgoing light separated by the first dichroic mirror 12. The first dichroic mirror 12 is transmitted through the first dichroic mirror 12 so that the first
Reflection mirror 10, first dichroic mirror 12,
Second dichroic mirror 19, third reflecting mirror 2
6 are arranged in this order, and a first reflecting mirror 10, a metal halide lamp 1 as a light source, and an exhaust fan 38 are arranged in this order. A first reflecting mirror 10, a metal halide lamp 1 as a light source, and an exhaust fan 38 are arranged in this order. The arrangement is substantially parallel to and adjacent to the arrangement of the projection lens 37, the dichroic prism 35, and the second dichroic mirror 19.

According to the liquid crystal projector of this embodiment, the hot air 39 exhausted by the exhaust fan 38 flows in the same direction as the light 36 emitted from the projection lens 37. It is impossible for the viewer to be positioned in the vicinity of the direction of the light 36 emitted from the projection lens 37 because the viewer himself blocks the emitted light 36 and generates a shadow on the image on the screen. Therefore, it does not flow in the direction of the viewer located near the liquid crystal projector, and does not give any discomfort to the viewer.

For the same reason, even when an image device such as a personal computer is used in the vicinity of a liquid crystal projector, hot air does not hit these heat-sensitive devices, and there is no need to consider the position of the device. In addition, in order to efficiently exhaust the heat generated from the light source, there is no need to take care not to place an object that blocks the exhaust at the position where the hot air is exhausted, thus improving usability.

In the present embodiment, the first dichroic mirror 12 has a spectral characteristic of reflecting B-color light and transmitting G-color light and R-color light.
By using the spectral characteristic of reflecting the G color light and transmitting the R color light, it was possible to relatively increase the B color light component as compared with the R color light component. This means that only the B color light
This is because S-polarized light components having higher reflectance than the P-polarized light component can be used at 0, 12, and 15 and can be used only for reflection. This has the effect of increasing the white color projected on the screen to a desirable color temperature. In particular, some glass and plastic materials for optical components used in liquid crystal projectors reduce the light utilization efficiency of B color light (for example, polarizing plates and liquid crystal panels). The decline was not avoided. Therefore, with this configuration, the B-color light component could be used to the maximum, and the decrease in the color temperature could be minimized.

In the present embodiment, the R color light is compared with the B color light and the G color light by the relay lenses 25 and 27 and the reflection mirror 2.
Since the extra color filters 6, 28 must be used, the reduction of the R color light is a problem due to the loss of transmittance and reflectance.

Therefore, in the present embodiment, the first reflecting mirror is the enhanced silver mirror 10, the third reflecting mirror is the cold mirror 26 transmitting infrared rays, and the fourth reflecting mirror is the enhanced silver mirror 28. did.

In addition, with the use of the enhanced reflection silver mirrors 10 and 28, it becomes necessary to block unnecessary infrared rays and ultraviolet rays.

Therefore, in the present embodiment, the third reflecting mirror is a cold mirror 26 that transmits infrared rays. This prevents harmful infrared rays from being emitted to the polarizing plate 30 and the liquid crystal panel 31.

In this embodiment, the first liquid crystal panel 1
In the optical path between the polarizing plate 17 and the first dichroic mirror 12 disposed on the light incident side of No. 8, a UV cut filter for blocking ultraviolet rays is disposed. In this embodiment, the UV cut filter 17a is formed on the incident surface of the polarizing plate 17.

In the first embodiment of the present invention, the light source side of the first lens array is formed as a concave lens surface. However, the present invention is not limited to this.
Any configuration may be used as long as a concave lens surface is provided between the reflector 3 and the second lens array 11.

FIG. 2 is a ray diagram from the second lens array 4 to the projection lens aperture 92 when the liquid crystal panel with micro lenses 85 is employed in the present invention. Even if the emission angle c of the liquid crystal panel 18 is increased by the divergence angle a described with reference to FIG. 7, the incident angle b can be reduced by the miniaturization of the second lens array 4, so that the projection lens opening 92 cuts off. No light generation occurred, and the light use efficiency was sufficiently improved.

FIG. 3 is a top view of a liquid crystal projector optical system according to a second embodiment of the present invention.

The difference from the first embodiment is that the reflector 3
A flat concave / convex lens 42 having a flat surface 41 on the reflector 3 side is provided between the first lens array 40 and the first lens array 40.
0 is a point that a plano-convex lens configuration is adopted.

According to this embodiment, although the number of components increases and the price increases, the aberration performance of the lens is improved, so that the lens array 11 is minimized and the light use efficiency is further improved.

FIG. 4 is a top view of a liquid crystal projector optical system according to a third embodiment of the present invention.

The difference from the first embodiment is that the second lens array 11 side of the first lens array 43 is
The point is 4.

According to this embodiment, the first lens array 4
Although it is necessary to design the opening shape of the convex lens array of No. 3 to be slightly modified from a rectangle, the aberration performance of the lens is improved as compared with the first embodiment, so that the lens array 11 is less likely to be shaken, and the light utilization is improved. Efficiency is further improved.

[0046]

As described above, according to the present invention,
Since the reflector is an ellipsoidal mirror and a concave lens surface is provided between the reflector and the second lens array, it is possible to have the function of converting the convergent light from the reflector into substantially parallel light, so that the first lens array and The second lens array can be reduced in size. Thereby, even when a liquid crystal panel with microlenses is employed, there is an effect that the light use efficiency can be sufficiently improved.

[Brief description of the drawings]

FIG. 1 is a top view of a liquid crystal projector optical system according to a first embodiment of the present invention.

FIG. 2 is a ray diagram from a second lens array 4 of the present invention to a projection lens aperture 92.

FIG. 3 is a top view of a liquid crystal projector optical system according to a second embodiment of the present invention.

FIG. 4 is a top view of a liquid crystal projector optical system according to a third embodiment of the present invention.

FIG. 5 is a top view of a conventional liquid crystal projector optical system.

FIG. 6 is a sectional view of a liquid crystal panel with microlenses.

FIG. 7 shows a projection lens opening 92 from the second lens array 4 in the case of a conventional liquid crystal panel without microlenses.
FIG.

FIG. 8 is a ray diagram from the second lens array 4 to the projection lens aperture 92 in the case of a conventional liquid crystal panel with microlenses.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal halide lamp, 2 ... Illumination light, 3 ... Lamp reflector, 4 ... 1st lens array, 5 ... Lamp reflector, 6 ... Illumination light, 7 ... Incident surface, 8 ... Convergent light, 9 ... Outgoing light, 10 ... Increase Reflective silver mirror, 11 second lens array,
12: dichroic mirror, 13: B color light, 14: G
And R color light, 15: enhanced reflection aluminum mirror, 16: condenser lens, 17: polarizing plate, 17a: UV cut filter, 18: liquid crystal panel for B color light, 19: dichroic mirror, 20: G color light, 21: R color light, Reference numeral 22: condenser lens, 23: polarizing plate, 24: liquid crystal panel for G color light, 25: relay lens, 26: cold mirror, 27
... Relay lens, 28 ... High reflection silver mirror, 29 ... Condenser lens, 30 ... Polarizer, 31 ... R color liquid crystal panel, 32 ... B transmitted light, 33 ... G transmitted light, 34 ... R transmitted light, 35 ... Dichroic Prism, 36 ... outgoing light, 3
7 Projection lens, 38 Exhaust fan, 39 Hot air, 40
... first lens array, 41 ... plane, 42 ... plano-concave lens,
43: first lens array, 44: concave lens surface, 50: metal halide lamp, 51: illumination light, 52: lamp reflector, 53: UV-IR cut filter, 54: first
Lens array, 55: Cold mirror, 56: Second lens array, 57: Dichroic mirror, 58: R color light, 59: G and B color light, 60: Increasing reflection aluminum mirror, 61: Condenser lens, 62: Polarizing plate, 63 ... R
Liquid crystal panel for colored light, 64 ... dichroic mirror, 65
... G color light, 66 ... B color light, 67 ... Condenser lens, 6
Reference numeral 8: polarizing plate, 69: liquid crystal panel for G color light, 70: relay lens, 71: reflective aluminum mirror, 72: relay lens, 73: reflective aluminum mirror, 74: condenser lens, 75: polarizing plate, 76: B LCD panel for colored light, 77 ...
R transmitted light, 78 G transmitted light, 79 B transmitted light, 80 dichroic prism, 81 outgoing light, 82 projection lens, 83 exhaust fan, 84 hot air, 85 liquid crystal panel with micro lens, 86 Parallel light, 87: micro lens, 88: divergent light, 89: black matrix, 90
... Pixel aperture, 91 ... Liquid crystal panel without micro lens, 9
2: Projection lens aperture, a: divergence angle, b: incidence angle, c: emission angle.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G03B 33/12 G03B 33/12 H04N 5/74 H04N 5/74 A (72) Inventor Hisao Inage Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa (292) Inventor Takashi Kakuda Takashi Kakuda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi Multimedia Systems Development Headquarters

Claims (5)

[Claims] A light source, a reflector, a first lens array,
A second lens array, a liquid crystal panel, and a projection lens; and irradiating the liquid crystal panel with illumination light from a light source via the reflector, the first lens array, and the second lens array.
1. A liquid crystal projector for projecting light emitted from a liquid crystal panel onto a screen by a projection lens, wherein the reflector is an elliptical mirror and a concave lens surface is provided between the reflector and the second lens array. 2. The liquid crystal projector according to claim 1, wherein the liquid crystal panel has a micro lens. 3. The liquid crystal projector according to claim 1, wherein the light source side of the first lens array has a concave lens surface. 4. A method according to claim 1, further comprising the step of:
2. The liquid crystal projector according to claim 1, wherein a plano-concave lens having a flat surface on the reflector side is provided, and the first lens array is a plano-convex lens. 5. The liquid crystal projector according to claim 1, wherein the second lens array side of the first lens array has a concave lens surface.