JP3413099B2 - Lighting device for LCD projector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device for a liquid crystal projector which is effective for a liquid crystal projector, a liquid crystal projection television, etc. using a light source lamp and a liquid crystal panel.

[0002]

2. Description of the Related Art A relatively large illumination divergence angle is allowed 3.
Regarding a lighting device for a liquid crystal panel of a plate type or a single plate type using a color filter, Japanese Patent Application Laid-Open No. 5-346557 and paper "Illumination optical system for projector using irregular aperture lens array" (MICRO OPTICS NEWS Vol.14 / No3 1996- 9-26
) Etc. In this device, it is possible to efficiently collect the light emitted from the finite length light source on the liquid crystal.

However, if further miniaturization is attempted while maintaining the current light source shape due to the heat-resistant condition, the liquid crystal panel will be further miniaturized, and the light emitted from a constant light source is condensed and illuminated according to the light source principle. The smaller the area covered, the wider the divergence angle of illumination.

On the other hand, under the projection conditions, in order to achieve resolution and various performances as the liquid crystal becomes finer (smaller size and higher definition), the liquid crystal transmission divergence angle must be made rather small to maintain the current cost.

Therefore, it should be naturally understood that it is necessary to reduce the liquid crystal transmission divergence angle by reducing the illumination divergence angle to reduce the load on the projection lens. In the conventional illumination means, a means for reducing the illumination divergence angle while maintaining the light collection efficiency has not been shown as a concrete solution other than the extension of the optical path length, which is contrary to the main purpose of downsizing. Become.

In the microlens color separation type illumination optical system, etc., which will be described below with reference to FIG. 1 and FIG. 2, a microlens arranged for each liquid crystal pixel and a dichroic mirror for spectrally irradiating with an angle deviation are used.
In principle, the divergence angle of the illumination is extremely severe, so even if a large optical path length can be secured with the increase in the number of pixels, the effective divergence angle range on the light source side of the fly-eye lens will be reduced, resulting in high light collection efficiency. The current situation is that no effective means for constructing an optical system that can be secured has been shown.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention provides a liquid crystal projector capable of improving the light utilization efficiency of the fly-eye lens and improving the display performance of the liquid crystal projector while realizing the miniaturization of the entire device. An object is to provide a lighting device.

[0008]

A liquid crystal projector according to the present invention
The illuminator of the Jector is a liquid crystal that is illuminated by light from a light source.
It has a panel and projects the light emitted from the liquid crystal panel.
Intended for those who are sour. And put it in the first focus
An ellipse that collects and reflects the light emitted from the light source on the second focal point.
An elliptical reflector that is placed facing the circular reflector at a predetermined interval.
The first and second outer dimensions are smaller than the opening diameter of the deflector.
It consists of a fly-eye lens, an elliptical reflector and a liquid crystal panel.
The light emitted from the elliptical reflector is placed between the
Divide into a number and divide the light input into each division into a liquid crystal screen.
A flyer for emitting so that the entire flannel is illuminated.
Between the lens section and the fly-eye lens section and the liquid crystal panel
Virtual multiple in the split part of the fly-eye lens part
The light emitted from the light source is controlled to be a substantially parallel light and is emitted to emit a liquid crystal panel.
From the fly-eye lens section
So that the effective diameter of the elliptical reflector is optically small.
An elliptical reflector and a fly eye are used for optical correction.
Optical correction means provided between the lens and the lens
It was done.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a microlens color separation type liquid crystal projector to which the present invention is applied to an optical system.

Reference numeral 11 denotes a light source using a metal halide lamp or a high-pressure mercury lamp, which inevitably has a small fly-eye structure according to the principle of the present system. Originally, an elliptical reflector 12 is used to form the first element of the fly-eye lens unit 14. Control reflection is performed so that the light is focused on. The light condensed and reflected by the elliptical reflector 12 is incident on the fly-eye lens unit 14 through the optical correction means 13 which is a feature of the present invention. The fly-eye lens unit 14 is composed of first and second fly-eye lenses, divides the light emitted from the elliptical reflector 12 into an arbitrary plurality, and irradiates the entire liquid crystal panel 18 with the light input to the respective dividing units. Emit as if to. The fly-eye lens of the fly-eye lens unit 14 is configured, for example, in such a manner that four lens arrays face each other in the horizontal and vertical directions.

The light emitted from the fly-eye lens unit 14 is condensed by the condenser lens 15 and is inclined by the optical axis to the dichroic mirrors 16B, 16R and 16G arranged so that the three lenses substantially overlap. It is incident.

Here, the dichroic mirror 16R reflects light in the red wavelength band in the direction of 90 degrees, and the dichroic mirror 16B reflects light in the blue wavelength band in the direction of an obtuse angle than 90 degrees, and the dichroic mirror 16G. Reflects light in the green wavelength band in a direction more acute than 90 degrees. Through the dichroic mirrors 16R, 16B, none of the light reflected from 16G polarizer 17, the liquid crystal panel 18
Is irradiated. The liquid crystal panel 18 responds to each of R, G, and G according to a video signal supplied from a liquid crystal drive circuit (not shown).
The light transmission amount of the B cell is controlled.

The light spatially modulated image emitted from the liquid crystal panel 18, that is, the color optical image is incident on the projection lens 20 via the analyzer 19. The projection lens 20 magnifies the incident color optical image and projects it on the screen. Either rear projection or front projection may be used.

FIG. 2 is an enlarged view of a part surrounded by a dotted circle in FIG. As shown in FIG. 2, the projector device is a micro-lens color separator configuration method, the liquid crystal panel 18, the micro lens 18b is disposed on the front surface of the liquid crystal display device 18a. Each lens portion of the microlens 18b corresponds to each signal electrode of the liquid crystal display element 18a, and one lens portion of the microlens 18b corresponds to three (G, R, B) openings (one color) of the display element. It is arranged so as to correspond to an opening for a pixel).

In FIG. 2, lights 18R, 18G and 18B incident on the openings R, G and B are emitted from dichroic mirrors 16R, 16G and 16B, respectively. Since the light 18R travels straight, it enters the opening (for red) directly below the microlens portion. However, since the other lights 18G and 18B are incident on the microlens portion at an angle, respectively, they are incident on the apertures whose light collecting positions deviate from the apertures for red, that is, the apertures for G and B, respectively. To do.

As a result, the optical image emitted from the liquid crystal panel 18 is output as a color optical image. Here, the items required for the above lighting device and each part will be described as follows.

As shown in FIG. 3, the angle θ formed by the light beams 18R and 18R 'is an effective illumination angle which is effective for the present light valve, and requires a high precision and a small angle. As the definition of liquid crystal becomes higher, the effective illumination angle becomes smaller and higher precision is required. If the illumination conditions cannot secure this effective illumination angle or if the effective illumination angle exceeds the effective illumination angle due to optical component placement errors, etc., it will not be effective as illumination light and will also irradiate the liquid crystal ineffective part and become a heat source / stray light source. Adversely affects
If the angle is further increased, the illumination light leaks into the adjacent opening, causing so-called color mixing, which causes a problem that the color purity cannot be maintained.

On the other hand, the fly-eye lens unit 14 functions as a relay lens for focusing the light emitted from the elliptical reflector 12 onto each lens eye of the element A of the fly-eye lens by the condenser lens 15 and collecting the light. Light lens 1
5, the size of the effective illumination angle θ is superposed and averaged on the liquid crystal panel 18 while maintaining the state of the frame image. Here, the size of the effective illumination angle θ is affected by the size of the fly-eye lens 14 viewed from the liquid crystal position.

This is because the fly-eye lens 14 has a plurality of virtual light sources corresponding to the shape of the fly-eye in order to divide and superpose the light condensed by the reflector, and in order to reduce the effective illumination angle, The distribution range of the light source is narrowed, that is, a micro fly-eye lens is required. For this reason, the effective incident divergence angle (NA) to the fly eye must be reduced together with the number of fly eye divisions. Therefore, in order to secure the light utilization efficiency, the elliptical reflector 1 required by the fly eye.
For No. 2, it becomes necessary to reduce the distance or increase the distance from the fly-eye lens 14 to the reflector until it falls within the effective angle range.

On the other hand, on the other hand, there is a limit to miniaturization of the reflector due to thermal problems, and if the distance from the fly-eye lens 14 to the reflector is set to be large with a real light source having a finite length, the efficiency of reflection directivity due to the finite arc is increased. This is because it is difficult to focus light on the small fly-eye lens 14.

Therefore, according to the present invention, the fly-eye lens unit 1 is provided.
While satisfying the design conditions of 4 and satisfying the design conditions of the elliptical reflector 12, the above-mentioned problems are solved, and the light utilization efficiency of the fly-eye lens is improved while realizing the miniaturization of the entire device, and the liquid crystal projector. It is also intended to improve the display performance of.

As an example of the concrete means, as shown in FIG. 1, there is provided an optical correcting means 13 in which the effective diameter of the elliptical reflector 12 as viewed from the fly-eye lens portion 14 becomes smaller.

FIG. 4 shows an example of another specific shape of the above optical correction means 13. In the example of FIG. 4, a conical lens 21 whose optical axis is coaxial is provided between the fly-eye lens unit 14 and the opening of the elliptical reflector 12. As shown in the figure, when a light source 11 such as a metal halide lamp or a high-pressure mercury lamp is used, the light source 11 moves to the second focal point f.
Up to 2, the structure is such that light does not reach the optical axis and around the optical axis. This is said to be a void. This device
It also prevents the light from becoming non-uniform due to the effect of this hollow.

That is, this is an embodiment in which the conical lens 21 is applied as an optical means in which the reflector system viewed from the fly-eye lens unit 14 becomes small, that is, the fly-eye incident angle becomes small. As you can see from the figure, the fly-eye lens part 1
Considering the NA of 4 and the arc characteristics of the elliptical reflector 12, it is possible to reduce the fly-eye incident angle by half by applying the most appropriate conical lens apex angle. At the same time, since the light emitted from the conical lens 12 is mixed on the optical axis corresponding to the hollow portion, a high-quality illumination system can be constructed even with a small number of fly-eye divisions. Particularly, the high-pressure mercury lamp, which has recently become the mainstream, has a poor arc stability and is a very effective means.

FIG. 5A shows an example of a concrete shape of another optical correction means 13 of the present invention. Figure 5
(B) is a partially enlarged view. In this example, the conical lens 21 is arranged so as to straddle the second focal point f2 of the elliptical reflector 12 to further improve the light mixing frequency and improve the illumination quality. That is, the elliptical reflector 12 is arranged on the second focal point f2.

According to this example, although the luminous flux mixing frequency is improved, the telecentricity of the fly-eye incident light is slightly deteriorated. Therefore, the condenser lens 22 may be provided. By performing lens processing on the light source side of the first fly-eye lens 14a, the telecentricity is restored to the level of the example in FIG.

In this example, not only the conical lens 21 but also a condensing lens 22 is added, but the condensing lens function is the light source side of the fly-eye lens 14a and the conical lens 21.
Since it is possible to include the function of the condenser lens 22 by devising the shape of, the element is not added in most cases.

In the example shown in FIG. 6, a convex mirror 24 is added to obtain the same effect as the concave lens 13 when the optical axis needs to be bent between the elliptical reflector 12 and the fly-eye lens portion 14. This is an example. If the optical size of the projector is limited and it is necessary to add a mirror, and it becomes impossible to arrange a concave lens with the highest efficiency, the convex mirror 24 can be used to obtain the same effect. In addition, since it is a modification of the mirror originally required as a structural prerequisite, the effect of improving efficiency can be obtained without adding the number of parts, and the present invention can be applied at a lower cost.

Next, the course of thought that was the background to the present invention will be shown. The fly-eye lens unit 14 for seeing the reflector 12 can be realized with a small size and high efficiency if there is some illumination angle margin, but in the microlens color separation method, it is required to have a large number of pixels because of a tendency toward high definition. Then, the panel becomes large and the NA of the projection lens cannot be secured, or the aperture ratio of the liquid crystal becomes very small, and in any case, the effective illumination angle θ becomes small.

As an example focusing only on the horizontal direction, if the horizontal pixel pitch Wp is 90 μm in order to secure an aperture ratio of 40% or more in the liquid crystal display element, each dot pitch Wd is 30 μm and the opening width is 2 Wo. Is about 20 μ.

If the liquid crystal size at this time is set to a wide aspect ratio of VGA class resolution in consideration of a normal television, the panel size is about 3.5 inches. It is common sense that Fno should be limited to about 2 if the resolution, size, and cost are taken into consideration in an optical system intended for consumer life. Therefore, the collection angle range Θ within the glass of the projection lens is about 9.47 degrees. In this, the distance L from the microlens, in which all the liquid crystal transmitted light shown in FIG. 5 becomes effective light, is about 510 μm. On the other hand, the effective illumination angle range θ viewed from the illumination side is about 1.71 degrees.

If the distance Lcd from the liquid crystal to the fly-eye lens section is 300 mm, the maximum horizontal size Wf of the fly-eye lens section allowed is about 17.9 mm. If the fly-eye lens part is divided into four parts in the horizontal direction,
The horizontal width Wfp per surface is about 4.5 mm.

Next, the NA of the fly-eye lens portion obtained from the above conditions is calculated. The liquid crystal size is 76.8 from the above formula.
Since the distance is mm, the distance d between the first and second fly-eye lenses is about 4.5 mm. Therefore, the fly-eye effective collection angle θfe
Is about 7.3 degrees, that is, the NAfe of the fly eye is 0.1
Only about 3.

If the distance Lr from the reflector opening to the first fly-eye lens is 150 mm, the allowable effective aperture diameter φ of the reflector is about 38.4 mm. Of course, the elliptical reflector 12 also has some restrictions. First, due to the heat problem, the distance to the shortest reflection portion of the ellipsoidal reflector 12 depending on the lamp power, that is, the first focal length f
1 must be greater than or equal to a number. If the glass is sealed with protective glass or the like to prevent the risk of lamp rupture, this value naturally needs to be increased. In the specific example, if a 250 W lamp or the like is used for high brightness, the thermal expansion coefficient α is 3
Due to the heat resistance of conventional glass materials and vapor deposition coats of about 4 to 38, the above f1 must be at least 12 mm.

Here, it becomes necessary to consider the light distribution characteristics of the lamp. In general, the emission range of a lamp is about 130 degrees, so unless a considerable solid angle range is covered, the light distribution characteristic loss becomes large, and the meaning of using a high-efficiency fly eye is lost.

When covering 70% or more, the opening diameter reaches about 90 mmφ. Therefore, an elliptical reflector having an opening of 32 mmφ requires extremely small light distribution coverage, a very low power lamp, or a reflector using an expensive crystallized glass material and many cooling measures.

In order to avoid this inconvenience, the second focal point of the elliptical reflector is set to be large and the converging angle range is set to the fly-eye part 1.
A means of matching the NA of 4 can be considered. 90 mm
Distance Lf between the fly-eye part 14 that covers the entire surface of φ and the reflector is about 350 mm.

The elliptic mirror parameters that satisfy the above conditions are roughly as follows. f1 = 12mm, f2 = 400mm,
f = 194 mm, major axis a = 206 mm, minor axis b 69.3 m
m, effective aperture diameter 90 mm, aperture Xo = 49.5 mm, elliptical reflector aperture-fly eye distance Lf 350
At this time, assuming that the light emission range Larc (arc length) of the light source lamp is 1.5 mm and the neck side opening position Xk for fixing the lamp is 2 mm, the neck opening dφ is 19.
About 3 mm. The distance Lv from f1 to the shortest reflection surface V position is about 13.9 mm.

If the angle range on the optical axis of the arc viewed from the shortest reflecting surface RN is represented by θ arc, it becomes 4.4 degrees. Therefore, the radius Rsl of the width range in which the light emitted from the light source is reflected by the reflector reflecting surface V and reaches the opening fly-eye position is 15.1.
It is about mm.

On the other hand, since the fly-eye existing range obtained previously is 9 mm, it can be seen that the light reflected by the reflector neck near reflecting surface Rn is hardly condensed within the fly-eye effective range.

As described above, in the illumination optical system using the microlens and the angle deviation with a severe effective illumination angle as shown in FIG. 1, in the fly-eye illumination optical system defined by the liquid crystal and the projection lens, all the light reaching from the entire surface of the reflector is The efficiency is deteriorated because light cannot be condensed on the liquid crystal surface, or the fly eye can cover the entire surface of the reflector, but all the light emitted from the arc cannot be condensed on the effective surface of the fly eye and efficiency is deteriorated.

Therefore, in the present invention, an optical correction means for reducing the effective diameter of the elliptical reflector as viewed from the fly-eye lens is arranged in the optical path between the elliptical reflector and the fly-eye lens to improve the quality.

[0043]

As described above, according to the present invention, when a high degree of telecentricity (a state in which light rays are parallel to the optical axis) is required for the illumination angle, the minimum of the fly-eye lens and the optical correction means is required. By adding parts, it is possible to construct a high-efficiency, high-quality fly-eye illumination optical system.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is an enlarged view showing a part of FIG.

FIG. 3 is a diagram further showing a part of FIG. 2;

FIG. 4 is a diagram showing still another embodiment of the present invention.

FIG. 5 is a diagram showing still another embodiment of the present invention.

FIG. 6 is a diagram showing still another embodiment of the present invention.

[Explanation of symbols]

11 ... Light source, 12 ... Elliptical reflector, 13 ... Optical correction means, 14 ... Fly eye lens part, 15 ... Condensing lens,
16R, 16B, 16G ... Dichroic mirror, 17
... polarizing plate, 18 ... liquid crystal panel, 19 ... analyzer, 20 ... projection lens.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02F 1/13 505 G02B 27/18 G02F 1/13357 H04N 5/74

Claims (5)

(57) [Claims] 1. A liquid crystal panel irradiated with light from a light source.
And has a structure in which light emitted from the liquid crystal panel is projected.
In a liquid crystal projector, an elliptical reflector that condenses and reflects light emitted from a light source placed at a first focal point to a second focal point, and an elliptical reflector that is arranged to face the elliptical reflector at a predetermined interval.
First and second fly eyelets whose outer dimensions are smaller than the diameter
Is arranged between the elliptical reflector and the liquid crystal panel, divides the light emitted from the elliptical reflector into a plurality of light beams, and irradiates the entire liquid crystal panel with the light input to the respective divided portions. and hula <br/> Iairenzu portion for emitting as, said fly-eye lens unit disposed between the liquid crystal panel, substantially parallel light light emitted from the virtual multiple light sources in the divided portion of the fly-eye lens unit The optical correction is performed so that the effective diameter of the condensing lens that is controlled and emitted to enter the liquid crystal panel and the elliptical reflector as viewed from the fly-eye lens unit are optically small .
Therefore, between the elliptical reflector and the fly-eye lens part
An illuminating device for a liquid crystal projector, comprising: an optical correcting means provided between the illuminating device and the liquid crystal projector. 2. The optical compensator is the second focal position.
The illumination device for a liquid crystal projector according to claim 1, wherein the illumination device is a conical lens that is provided in the vicinity of the base and has a bottom surface on the side of the elliptical reflector . 3. The fly-eye is the optical correction means.
The illumination device for a liquid crystal projector according to claim 1, wherein the illumination device is a concave lens having a concave surface on the lens portion side . 4. The elliptical refraction means is provided for the optical correction means.
Reflects the light from the Kuta and enters the fly-eye lens section.
The lighting device for a liquid crystal projector according to claim 1, wherein the lighting device is a convex mirror. 5. A light source and an elliptical reflector for condensing and reflecting light emitted from the light source.
And the elliptical reflectors that are placed facing each other at a predetermined interval.
First and second fly eyelets whose outer dimensions are smaller than the diameter
Of the ellipsoidal reflector and the liquid crystal panel.
The light emitted from the elliptical reflector is placed between
Divide into a number and divide the light input into each division into the liquid
Fragment for emitting so that the entire crystal panel is illuminated.
An eye lens portion and a plurality of virtual portions in the divided portion of the fly eye lens portion.
The liquid crystal emitted by controlling the light emitted from the light source into substantially parallel light.
The condensing lens incident on the panel and the elliptical reflector seen from the fly-eye lens section.
Optical correction is performed so that the effective diameter becomes smaller optically.
Therefore, between the elliptical reflector and the fly-eye lens part
The light emitted from the condenser lens and the optical correction means provided therebetween are incident,
A liquid crystal panel that emits an optical image that is modulated by, and the optical image that is emitted from the liquid crystal panel is spread on a screen.
Liquid having a projection lens for large projection
Crystal projector.