JPH09269485A - Illuminator for projection type liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high-quality illumination at low cost even when a fly-eye lens is used and to miniaturize the fly-eye lens by dividing light obtained by a parabolic mirror into plural and controlling plural main light beams generated by the fly-eye lens to almost parallel beams. SOLUTION: The light emitted from a light source lamp 11 is condensed by the parabolic mirror 15 and divided into plural by the fly-eye lens 21 so as to respectively irradiate an entire liquid crystal light valve 125, whereby luminance unbalance is averaged. The plural main light beams generated by the lens 21 are controlled to be the almost parallel beams by a condensing lens 23 and made incident on the light valve 125. Therefore, the fly-eye lens 21 can be made only one and miniaturized. The light emitted from the light valve 125 is made incident on a projection lens and enlarged by the projection lens to be displayed as a video on a screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting system for a projection type liquid crystal projector using a light source lamp and a liquid crystal light valve.

[0002]

2. Description of the Related Art In recent years, wide-screen broadcasting of terrestrial television broadcasting has begun following high-definition broadcasting. Also, with the spread of cable television, the upcoming digital television broadcasting, and the introduction of high-resolution software such as digital video discs, a high-quality large-screen image reproducing apparatus is desired. However, the CRT used in the conventional direct-view display device has a limit of about 40-inch due to manufacturing technology, manufacturing cost, product size and weight, and the like. Therefore, there is a front projection type or rear projection type projector system for realizing a larger screen.

Further, these projector systems have a CRT system and a liquid crystal system, respectively, depending on the device forming the original screen to be enlarged and projected, and the liquid crystal system is inferior in terms of maximum brightness to the CRT system. , Is considered superior in terms of focus performance, device weight and volume.

FIG. 6 is a block diagram showing an outline of a conventional projection type liquid crystal projector. In FIG. 6, a conventional projection type liquid crystal projector 101 includes a light source lamp 11 as a light source.
1 and a power supply circuit 11 for supplying power to the light source lamp 111
3, a parabolic mirror 115 arranged so that the light source lamp 111 is located at the focal point, a first polarizing plate 117, a color filter 119, a liquid crystal panel 121, and a second polarizing plate 1.
A liquid crystal light valve 125 having 23, a projection lens 127 for enlarging and projecting an image, a screen 129, an image input terminal 131 to which an image signal is input, and a signal processing circuit 133 for generating a liquid crystal panel drive signal from the image signal. And is configured.

This conventional projection type liquid crystal projector 101
The operation of is as follows. First, the light source lamp 111 using a halogen lamp, a metal halide lamp, etc.
A predetermined power is supplied from the power supply circuit 113 to emit light.
The light emitted from the light source lamp 111 is controlled and reflected by the parabolic mirror 115 into substantially parallel light emitted in the right direction.

Then, the substantially parallel light obtained from the parabolic mirror 115 is incident on the first polarizing plate 117 in order to limit the polarization direction. The substantially parallel light linearly polarized by the first polarizing plate 117, after passing through a color filter 119 for colorization, is provided with a plurality of liquid crystal cells arranged in a matrix so that the respective optical rotatory powers thereof can be controlled. Incident on the liquid crystal panel 121 equipped with the signal processing circuit 13
A spatial distribution of optical rotatory power for each liquid crystal cell according to the liquid crystal panel drive signal given from 3 is given.

Next, the light having the optical rotatory spatial distribution provided by the liquid crystal panel 121 is made incident on the second polarizing plate 123, and only the light of an arbitrary polarization direction is selectively passed from the second polarizing plate 123. By doing so, the optical rotatory spatial distribution is converted into light having a spatial distribution of light intensity, that is, a spatial distribution of light and dark.

Next, the light that has passed through the second polarizing plate 123 is made incident on the projection lens 127, and enlarged and projected from the projection lens 127 toward the screen 129.

The light emitting state of the light source lamp 111 is as follows.
Due to the influence of gravity, it has a vertically unbalanced emission intensity and color balance, and with this configuration as it is, the image quality is unbalanced vertically and horizontally. Also, depending on the lamp manufacturer and product, a protrusion called a chip for gas filling is arranged near the light emitting part, so diffuse reflection occurs here,
The collimated light is not obtained, and as a result, a large decrease in brightness and uneven color are generated. Further, the brightness curve with respect to the distance from the optical axis obtained by the parabolic mirror 115 is extremely steep as shown in FIG. 7, which prevents the desired image quality from being obtained.

As a means for solving this problem, the improvement means using a fly-eye lens is currently most commonly used. In this method, as shown in FIG. 8, the light emitted from the parabolic mirror 115 is subdivided into a plurality of pieces by the first fly-eye lens 141, and the subdivided lens array has a one-to-one correspondence. The second fly-eye lens 143 is used to provide directivity and illuminates the entire surface of the liquid crystal light valve 125, thereby averaging the luminance imbalance due to the above-mentioned factors and obtaining a high-quality light source illumination. . For example,
Of the light obtained from the parabolic mirror 115, the light in the shaded area in FIG. 8 is incident on the first fly-eye lens and is condensed on the corresponding second fly-eye lens 143. The fly-eye lens 143 has a directivity and irradiates the entire surface of the liquid crystal light valve 125.

The first fly-eye lens 141 and the second fly-eye lens 141
The fly-eye lens 143 is subdivided by a lens array as shown in FIG. 9A having the same aspect ratio as the illumination image shown in FIG. 9B.

[0012]

The illumination device of such a projection type liquid crystal projector is sufficient as a light source device such as an exposure device, which requires uniformity, but is slow with respect to the light beam incident angle. However, there are considerable limitations as an illuminating device of a liquid crystal projector in which the light passing through the liquid crystal light valve is further enlarged and radiated by a projection lens.

The reason for this will be described with reference to FIG. The parabolic mirror 115 is required to have an arbitrary size according to the power and efficiency of the light source lamp 111, but since the manufacturing cost is almost proportional to the area of the opening, if it is made larger than necessary, the cost becomes a problem. The minimum size is the most desirable shape.

The first fly-eye lens 141 and the second
The fly-eye lens 143 is arranged in an arbitrary division according to the parabolic mirror reflection 115 and the liquid crystal light valve 125. When the illumination system is viewed from the liquid crystal light valve 125,
There are a large number of virtual light source distributions that emit light from substantially the center position of each lens array of the first fly-eye lens 141 and the second fly-eye lens 143.

Therefore, at each position of the liquid crystal light valve 125, a luminous flux is incident from the above-mentioned multiple virtual light sources in the range of the angle θ, but the projection lens needs to take almost all the luminous flux into the entrance pupil. This is because the uneven brightness is averaged only after taking in all the light flux and irradiating it.
In addition, the desired light utilization efficiency is achieved. on the other hand,
NA of the projection lens (numerical aperture on the image side)
However, it goes without saying that there is a limit in shape and cost.

Now, the NA of the required projection lens will be calculated assuming that the parabolic mirror 115 and the liquid crystal light valve 125 have the same diagonal dimension. If the effective opening of the parabolic mirror 115 is 100φ, the distance between the electrodes of the light source lamp 111, which is most commonly used at present, is about 3 mm, so that the luminous flux emitted from the parabolic mirror 115 is already ± 5. It has a luminous flux divergence angle a of about degree. Here, the first fly-eye lens 141 and the second fly-eye lens 143 are also 100
If φ is divided into 10 equal parts, the light source seen from the optical axis position of the liquid crystal light valve 125 is a large number of virtual light sources existing in the range of 90φ, and therefore the second fly-eye lens 143 and the liquid crystal light valve The incident angle ψ at the time of an ideal light source when the distance from 125 is L is expressed by the equation (1).

Ψ = ± tan ⁻¹ {(90/2) / L} (1) Here, when L = 200 mm, ψ = ± 12.7 degrees. By simply adding ± 5 degrees due to the above-described light beam divergence angle a to this, θ = ± 17.7 degrees. Therefore, NA required for the projection lens is 0.3 (Fno (index of brightness of optical system) = 1.6). This is a very expensive and very large, i.e. unrealistic projection lens.

In order to solve this problem, it is necessary to secure an unrealistic optical path length or to provide a sufficiently large parabolic mirror 115 for the liquid crystal light valve 125. In order to reduce the size of a liquid crystal panel that is desired, a sacrifice directly related to the aperture ratio, that is, the light utilization efficiency is required. Therefore, it is necessary to avoid many restrictions in developing a product that satisfies all these conditions. It was

The present invention has been made in view of the above problems, and it is possible to realize high-quality illumination at low cost even when a fly-eye lens is used, and to downsize the fly-eye lens. It is an object of the present invention to provide a lighting device for a projection type liquid crystal projector capable of performing the above.

[0020]

To achieve the above object, the present invention provides a light source lamp, an elliptical mirror that reflects and collects light emitted from the light source lamp, and the light obtained from the elliptic mirror is divided into a plurality of pieces. Then, each fly-eye lens illuminates the entire liquid crystal light valve, a condenser lens that controls a plurality of chief rays generated by the fly-eye lens to be substantially parallel light, and the light emitted from this condenser lens is irradiated. In addition, it has a liquid crystal panel arranged in a matrix to control the optical rotation of each, and a liquid crystal light valve that controls the transmission amount of the light emitted from the condenser lens, and a liquid crystal light valve that transmits the liquid crystal light valve. The gist is to have a projection lens for enlarging and projecting the generated light.

In the illuminating device of the projection type liquid crystal projector of the present invention, the light emitted from the light source lamp is condensed using the elliptical mirror. Then, the fly-eye lens splits the light and irradiates the entire light valve, and a plurality of chief rays generated by the fly-eye lens are controlled into substantially parallel light by a condenser lens to be incident on the liquid crystal light valve. The light transmitted through the bulb is projected in an enlarged scale. This allows
High-quality illumination can be realized at low cost, and the fly-eye lens device can be downsized.

Further, the condenser lens may form a plurality of chief rays generated by the fly-eye lens at the entrance pupil position of the projection lens. Further, the fly-eye lens is provided with a single concave lens processing for refracting the light obtained from the elliptical mirror in a direction substantially parallel to the optical axis on the light source lamp side. It is also possible to use a fly-eye lens processing for dividing the light refracted into a plurality of parts into a plurality of parts on the side of the condenser lens. Further, the processing of the single concave lens of the fly-eye lens is performed mainly for the purpose of reducing the amount of refraction on the processing surface of the fly-eye lens, and the processing of the fly-eye lens of the fly-eye lens is performed as described above. You may make it use the structure which incorporated the variation | change_quantity of a single concave lens process. Further, a single concave lens that refracts the light obtained from the elliptical mirror in a direction substantially parallel to the optical axis is provided on the elliptical mirror side of the fly-eye lens, and the fly-eye lens incorporates the variation of the single concave lens. You may make it use what has the different structure. Further, the single concave lens is subjected to a processing mainly intended to reduce the amount of refraction in the fly's eye lens, and the fly's eye lens is configured to incorporate the variation of the single concave lens. May be used. Further, as the fly-eye lens, one that is an assembly of lenses having the same aspect ratio as the liquid crystal panel and having a plurality of types of areas is used. Further, the fly-eye lens is an assembly of lenses having the same aspect ratio as the liquid crystal panel and having a plurality of types of areas, and these lenses have a symmetrical structure about the optical axis. To use. Further, as the fly-eye lens, one that is an assembly of lenses having a plurality of areas with the same aspect ratio as the liquid crystal panel and having a substantially circular shape when combined is used.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of a lighting device of a projection type liquid crystal projector according to the present invention. In the figure, the same components as those shown in FIG. 6 are denoted by the same symbols, and detailed description is omitted.

As shown in FIG. 1, the illuminating device 1 of the projection type liquid crystal projector of the first embodiment includes a light source lamp 11 as a light source, an elliptical mirror 15 for reflecting and condensing light emitted from the light source lamp 11. The light obtained from the elliptical mirror 15 is divided into a plurality of rays, each of which illuminates the entire liquid crystal light valve 125, and the condensing lens 23 which controls the plurality of chief rays generated by the fly eye lens 21 into substantially parallel rays. And a liquid crystal light valve 125 including a first polarizing plate, a color filter, a liquid crystal panel, and a second polarizing plate.

The illumination device 1 of the projection type liquid crystal projector of the first embodiment uses the elliptic mirror 1 to direct the light emitted from the light source lamp 11.
5, the fly-eye lens 21 divides the light so that each illuminates the entire liquid crystal light valve, and the luminance imbalance is averaged. A plurality of chief rays generated by the fly-eye lens 21 are collected. The light is controlled to be substantially parallel light by 23 and is made incident on the liquid crystal light valve 125. Therefore, the number of the fly-eye lens 21 can be one, and the size of the fly-eye lens 21 can be reduced. The light emitted from the liquid crystal light valve 125 enters a projection lens (not shown), is enlarged by the projection lens, and is displayed as an image on a screen (not shown).

The fly-eye lens 21 has a virtual light source having a diameter L1 (a diameter of a circle into which all the light source centers of the virtual light source enter) shown in FIG. 2 and light resistance according to the processing accuracy and projection lens performance. The outer shape L2 (the diameter of the circle into which all the fly-eye lenses 21 are contained) is determined.

The fly-eye lens 21 is a group of convex lenses having the same aspect ratio as that of the liquid crystal panel and having a plurality of types of areas, and the light obtained from the elliptic mirror 15 has a minimum lens array configuration. For the most efficient control so as to have the light utilization efficiency, they are combined so as to have a shape close to a circle as shown in FIG. Further, the fly-eye lenses 21 are arranged symmetrically about the optical axis of the light source lamp 11 so that the unbalanced brightness in the vertical and horizontal directions caused by the structure of the light source is averaged. That is, as shown in FIG. 2, lens Aa in quadrant a, lens Ab in quadrant b, lens Ac in quadrant c, and lens Ad in quadrant d.
And a lens Ba of the quadrant a, a lens Bb of the quadrant b, a lens Bc of the quadrant c, and a lens Bd of the quadrant d have a structure symmetric with respect to the optical axis. The lens Cb, the lens Cc in the quadrant c, and the lens Cd in the quadrant d have an optical axis symmetrical structure, and the lens D in the quadrant a.
a, a lens Db in quadrant b, a lens Dc in quadrant c, and quadrant d
The lens Dd of No. 4 has an optical axis symmetrical structure, and the lens Ea of the quadrant a, the lens Eb of the quadrant b, the lens Ec of the quadrant c, and the lens Ed of the quadrant d have an optical symmetrical structure.

Looking at the fly-eye lens 21 from the liquid crystal light valve 125 is equivalent to irradiation from a plurality of virtual light sources dispersed in an arbitrary range around the optical axis.
Telecentricity (all principal rays are parallel to the optical axis) by arranging the condenser lens 23 at arbitrary positions before and after the liquid crystal light valve 125 so that the principal rays are parallel to the optical axis.
Is improving.

In this manner, the fly-eye lens 21 reduces unevenness in brightness caused by the reflecting mirror (elliptic mirror 15) whose parameter is the distance from the optical axis. In addition, the fly-eye lens 21 is configured to have four quadrants having a symmetrical structure with respect to the optical axis, and has a minimum required lens array configuration to have sufficient light utilization efficiency. By irradiating, the light source lamp 11 can be averaged so as to cancel out the brightness on the optical axis, that is, the unbalanced brightness in the vertical and horizontal directions.
The light emission unevenness caused by is mainly reduced.

Regarding the NA required for the projection lens of the first embodiment, if the radius of the distribution range of the virtual light source of the fly-eye lens 21 is designed to be 30 mm, then ψ = ± tan ⁻¹ {(30/2) /L}=±4.3 degrees, so even if the above-mentioned luminous flux divergence angle of ± 5 degrees is added, θ = ± 9.3 degrees, and NA = 0.16 (conventional 0.3). , Fno represents 3.1 (conventional 1.6), which is a great improvement. Therefore, the cost is remarkably reduced and the shape is remarkably downsized.

As described above, the illuminating device 1 of the projection type liquid crystal projector of the first embodiment condenses the light emitted from the light source lamp 11 by the elliptical mirror 15, and the fly-eye lens 21.
The light is split by means of light to illuminate the entire liquid crystal light valve, the brightness imbalance is averaged, and a plurality of chief rays generated by the fly-eye lens 21 are controlled by the condenser lens 23 to be substantially parallel light, and the liquid crystal is controlled. Since the light is incident on the light valve 125, high-quality illumination can be obtained at low cost, and the fly-eye lens 21 can be miniaturized. Therefore, the illumination device itself of the projection type liquid crystal projector can be miniaturized. it can.

FIG. 3 is a view showing a second embodiment of the illuminating device of the projection type liquid crystal projector according to the present invention. In the figure, the same components as those shown in FIG. 6 are denoted by the same symbols, and detailed description is omitted.

As shown in FIG. 3, if the viewing angle of the liquid crystal light valve 125 is acceptable, the condenser lens 23 forms a principal ray at the entrance pupil position 127a of the projection lens 127 by further shortening the focal length. It is also possible to have a field lens function together. Therefore, in the illumination device of the projection type liquid crystal projector of the second embodiment, the light emitted from the light source lamp 11 is condensed by the elliptical mirror 15.
The fly-eye lens 21 divides the light so that each illuminates the entire liquid crystal light valve 125 to average the luminance imbalance, and the converging lens 23 controls a plurality of chief rays generated by the fly-eye lens 21. The light is made incident on the liquid crystal light valve 125 and an image is formed at the entrance pupil position 127a of the projection lens 127.

Further, when the liquid crystal light valve 125 is relatively large or a sufficient optical path length cannot be obtained, as shown in FIG. 4, the light source lamp 11 side is provided with a concave lens processing 31a and the condenser lens 23. You may use the fly eye lens 31 by which the fly eye lens process 31b was given to the side. In this case, the concave lens processing 31a is processed mainly for refracting in a direction substantially parallel to the optical axis, or is mainly processed for reducing the refraction amount when entering the fly-eye lens processing 31b. To give.

Further, in these cases, as shown in FIG. 5, a plano-concave lens 41 in which the concave lens processing is made independent,
It is also possible to adopt a two-lens configuration including a fly-eye lens 43 having a flat surface on one side. In this case, the lens power of each refracting surface is reduced, so if you apply anti-reflection coating or other high efficiency maintaining means to the necessary refracting surface,
This is particularly useful when the lens power is required due to strict size restrictions.

As described above, in the illuminating device for the projection type liquid crystal projector of the second embodiment, the plurality of chief rays generated by the fly-eye lens 21 are controlled by the condenser lens 23 to be incident on the liquid crystal light valve 125 and projected. Since the image is formed on the entrance pupil position 127a of the lens 127, the function of the field lens can be provided in addition to the effect of the first embodiment, and the cost can be further reduced.

Further, in the above embodiment, the condenser lens 23 for improving the parallelism is added as an optical component, but since one of the conventional expensive fly-eye lenses is abolished, the total cost is improved. Not only is it done,
The area of the fly-eye lens 21 is also reduced to a fraction, and if a configuration that also has a field lens function is possible, it will contribute to a greater cost reduction.

[0038]

As described above, according to the present invention, the light emitted from the light source lamp is condensed by the elliptic mirror, and the light is divided by the fly-eye lens so that each light illuminates the entire liquid crystal light valve. The lens controls the light to be almost parallel and makes it enter the liquid crystal light valve, and the light transmitted through this liquid crystal light valve is enlarged and projected. Therefore, high-quality illumination can be achieved even when a fly-eye lens is used. It can be realized at low cost, and the fly-eye lens can be downsized.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of an illumination device of a projection type liquid crystal projector according to the present invention.

FIG. 2 is a diagram showing a configuration example of a fly-eye lens.

FIG. 3 is a diagram showing a schematic configuration of a second embodiment of an illumination device of a projection type liquid crystal projector according to the present invention.

FIG. 4 is a diagram showing a fly-eye lens that has been subjected to single concave lens processing and fly-eye lens processing.

FIG. 5 is a diagram showing a case where a single concave lens and a fly-eye lens are provided independently of each other.

FIG. 6 is a diagram showing a schematic configuration of a conventional projection type liquid crystal projector.

FIG. 7 is a distribution diagram showing luminance characteristics with respect to a distance from an optical axis of a parabolic mirror.

FIG. 8 is a diagram showing a schematic configuration of an illumination optical system using a conventional fly-eye lens.

FIG. 9 is a diagram showing an example of division of a conventional fly-eye lens.

FIG. 10 is a diagram for explaining a problem of an illumination optical system using a conventional fly-eye lens.

[Explanation of symbols]

 1 Illumination device of projection type liquid crystal projector 11 Light source lamp 15 Elliptical mirror 21 Fly-eye lens 23 Condensing lens 125 Liquid crystal light valve

Claims (9)

[Claims] 1. A fly-eye lens for illuminating a liquid crystal light valve, a light source lamp, an elliptic mirror for reflecting and condensing light emitted from the light source lamp, and dividing the light obtained by the elliptic mirror into a plurality of parts. And a condensing lens for controlling a plurality of chief rays generated by the fly-eye lens to be substantially parallel light, and a matrix for irradiating the light emitted from the condensing lens and controlling each optical rotatory power. A liquid crystal panel arranged in a line, and a liquid crystal light valve for controlling a transmission amount of light emitted from the condenser lens; and a projection lens for enlarging and projecting the light transmitted through the liquid crystal light valve. A lighting device for a projection type liquid crystal projector. 2. The illumination device for a projection type liquid crystal projector according to claim 1, wherein the condenser lens forms an image of a plurality of chief rays generated by the fly-eye lens at an entrance pupil position of the projection lens. . 3. The fly-eye lens has a single concave lens processing for refracting light obtained from the elliptical mirror in a direction substantially parallel to the optical axis on the light source lamp side. The fly-eye lens processing for dividing the light refracted into substantially parallel light into a plurality of rays is applied to the condenser lens side.
An illumination device for a projection type liquid crystal projector according to any one of 1. 4. The processing of the single concave lens of the fly-eye lens is performed mainly for the purpose of reducing the amount of refraction on the processing surface of the fly-eye lens. The illumination device for a projection type liquid crystal projector according to claim 3, wherein the processing is configured to incorporate a variation of the processing of the single concave lens. 5. A single concave lens for refracting light obtained from the elliptical mirror in a direction substantially parallel to the optical axis is provided on the elliptical mirror side of the fly's eye lens, and the fly's eye lens is a variation of this single concave lens. The illumination device for a projection type liquid crystal projector according to claim 1 or 2, wherein the illumination device has a configuration in which components are incorporated. 6. The single concave lens is subjected to a processing mainly intended to reduce the amount of refraction in the fly's eye lens, and the fly's eye lens incorporates a variation of the single concave lens. The illumination device for a projection type liquid crystal projector according to claim 5, wherein 7. The fly-eye lens is an assembly of lenses having a plurality of types of areas with the same aspect ratio as the liquid crystal panel, and the fly-eye lens is any one of claims 1 to 3. Illuminating device for projection type liquid crystal projector. 8. The fly-eye lens is an assembly of lenses having the same aspect ratio as the liquid crystal panel and having a plurality of types of areas, and the lenses have a symmetrical structure with respect to an optical axis. Claim 1 characterized by the above.
An illumination device for a projection type liquid crystal projector according to claim 3. 9. The fly-eye lens is an assembly of lenses having a plurality of types of areas with the same aspect ratio as the liquid crystal panel and having a substantially circular shape when combined. An illumination device for a projection type liquid crystal projector according to any one of 1.