JPH08227103A - Projection type display device - Google Patents

Abstract

PURPOSE: To provide a projection type liquid crystal display element where brightness is improved and irregular luminance on one display pixel is completely reduced, and by which a high-quality display picture is obtained. CONSTITUTION: This projection type display device is equipped with an elliptical condensing mirror 5, a light source 4 arranged near the 1st focal point of an ellipsoid, a collimator lens 6 having a focal point near the 2nd focal point of the ellipsoid, and an optical modulation element array constituted by two- dimensionaly arranging an optical modulation element 2 having a lens array on the collimator lens 6 side and having area S. When it is assumed that the length of a light emitting part is L, the square of the ratio of the minor axis to the major axis of an ellipse is μ, the focal length of the lens 6 is (f), a distance between the lens array and the aperture part of the modulation element 2 is (m), and refractive index between the lens array and the modulation element is (n), an expression is satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying an image based on a video signal, and more particularly to a projection display device for displaying an image on a reflective or transmissive screen and a projection display device. The present invention relates to a light modulation element array.

[0002]

2. Description of the Related Art At present, a plasma light emitting panel and a liquid crystal panel are drawing attention as a small and lightweight flat panel display device which replaces a CRT display device. This flat display device can be classified into a self-luminous type that emits light by itself in a display operation and a transmittance control type that controls the transmittance of light incident from an independent light source in a display operation. For example, the plasma emission panel belongs to the self-emission type, and the liquid crystal panel belongs to the transmittance control type. In particular, the transmittance control type display device represented by this liquid crystal panel is considered to be a favorite of the next generation display device, and its technical development is being advanced in various practical fields.

A general liquid crystal panel, as represented by a twisted nematic (TN) type introduced in a liquid crystal device handbook, uses a polarizing plate to make linearly polarized light birefringent or optical rotatory. It is characterized in that it is incident on the liquid crystal layer shown.

A projection type display device 901 using such a liquid crystal panel, as shown in FIG. 1, is a liquid crystal panel 911-corresponding to each color of red (R), green (G) and blue (B). R, 911-G, 911-B, and a light source 921 for irradiating the liquid crystal panels 911-R, 911-G, 911-B, and a parabolic condenser mirror 931 for converting the light source light from the light source 921 into parallel light. A light source optical system having
The liquid crystal panels 911-R, 911-G, and 911-B are configured by a projection optical system having a projection lens 941 for projecting transmitted light on the screen.

In the case of a projection type display device, improvement of brightness is an important issue. From this viewpoint, a microlens array is arranged in a liquid crystal panel to improve the effective aperture ratio, or a polarizing plate is used in the liquid crystal layer. Attempts have been made to use unnecessary polymer-dispersed liquid crystals.

[0006]

By the way, in the above-mentioned projection type display device 901, the light source light is collimated by using a parabolic condensing mirror and is incident on the liquid crystal panel. In this case, since the electrode part of the light source and the like are shadowed, the angular distribution of the light incident on the liquid crystal panel becomes large, and the parallel component is missing as shown in FIG. Therefore, there is a problem that the effect for improving the effective aperture ratio by disposing the microlens on the light incident axis side of the liquid crystal panel cannot be sufficiently achieved.

The object of the present invention is to improve the brightness and to sufficiently reduce the unevenness of brightness in one display pixel plane.
An object of the present invention is to provide a projection type display device capable of obtaining a high quality display image.

Another object of the present invention is to provide a light modulation element array used in the projection type display device.

[0009]

In order to solve the above-mentioned problems, the present invention (Claim 1) is directed to an optical modulation means for controlling the light transmittance mainly using the birefringence or optical rotatory power of light,
A light source optical system that guides light source light from a light source to the light modulator,
And a projection type display device having a projection optical system for projecting the modulated light modulated by the light modulating means onto a screen, wherein the light source optical system controls a light source and a converging angle of the light source light from the light source. A light source light control means, and the light source light control means, means for condensing the light source light from the light source,
A projection-type display device comprising: a diaphragm unit arranged near a position where the light from the light source is condensed, and a collimator lens.

Further, according to the present invention (claim 2), an elliptical focusing mirror having a concave reflecting surface on a part of the substantially elliptical surface, a light source arranged in the vicinity of the first focal point of the elliptic surface, and a first elliptic surface. Projection display device including a collimator lens having a focal point in the vicinity of two focal points, a light modulator element array having a lens array on the collimator lens side and two-dimensionally arranging light modulator elements having an area S, and a projection lens Where L is the length of the light emitting portion of the light source, μ is the square of the ratio of the minor axis and the major axis of the ellipse of the elliptical focusing mirror, f is the focal length of the collimator lens, and the distance between the lens array and the aperture of the modulator. Where m is the refractive index between the lens array and the modulator, and the following expression is satisfied.

[0011]

(Equation 7)

According to the present invention (claim 3), in the projection type display device (claim 2), the light ray direction is corrected near the second focus of the ellipsoidal surface or between the second focus position and the collimator lens. There is provided a projection type display device comprising an optical element for

Further, the present invention (Claim 4) provides a projection type display device characterized by satisfying the following expression in the projection type display device (Claim 3).

[0014]

(Equation 8)

Θ ₁ : arctan ((μ / (1-μ))) θ ₂ : angle of light emitted from the optical element that corrects the light ray direction when the light of θ ₁ is incident on the optical element that corrects the light ray direction Further, the present invention (Claim 5) has, in the projection type display device (Claim 4), an adjusting mechanism for adjusting a spatial intensity distribution of a light flux from the light source light by an optical element for correcting the light ray direction. A projection type display device is provided.

According to the present invention (Claim 6), in the projection display device (Claim 2), the elliptical light converging mirror is placed between the elliptic light converging mirror and the light modulator array device. There is provided a projection type display device characterized in that a condensing mirror having a part of a substantially spherical concave surface as a reflecting surface is arranged as described above.

Further, according to the present invention (claim 7), in the projection type display device (claim 2), the light is emitted from the light source arranged between the light source and the second focal point position of the elliptical surface. Means for splitting the light into two polarized waves orthogonal to each other,
A means for aligning a polarization plane of one polarization wave of the two polarization waves with a polarization plane of the other polarization wave, and a condensing means for condensing the polarization plane near the second focus position of the ellipsoid. Provided is a projection type display device.

The present invention (claim 8) is the projection type display device (claim 2), wherein the lens array is
There is provided a projection type display device having a focal position on an optical path farther from the light source than a position of a light shielding member defining an opening area of the light modulation element.

Further, according to the present invention (claim 9), in the projection type display device (claim 2), a light source light control means composed of an optical diaphragm is provided in the vicinity of the second focal point of the ellipsoid, and the optical diaphragm is provided. The following formula is provided, where D is the diameter of the projection display device.

[0020]

[Equation 9]

Further, according to the present invention (claim 10), in the projection display device (claim 2), the light emitted from the light source is dependent on the wavelength of the light between the light source and the light modulation element array. Directional spectroscopic means for giving different traveling directions, and at least one pair of modulation elements having different wavelength distributions of incident light exist in the modulation element group composed of a plurality of modulation elements. As described above, between the modulator elements of the modulator element group, there is provided a spectral imaging means for spatially separating, and each modulator element is driven by a drive signal corresponding to the color of the incident light. Projection display device.

According to the present invention (claim 11), in the projection type display device (claim 10), between the lens which is the spectral image forming means and a member which defines a display area of the modulation element array device. When the thickness of a certain N optical media is t _i and the refractive index is n _i (i = 1 to N), the distance between the centers of the display contributing portions of two adjacent modulation elements in the modulation element group is ΔA, and a projection type display characterized in that there is at least one pair of two modulation elements that satisfy the following equation, where θ ₀ is the angle difference between the light incident on each of the two modulation elements in the atmosphere. Provide a device.

[0023]

[Equation 10]

According to the present invention (Claim 12), in the projection display device (Claim 10), one of the modulation elements in the modulation element group is in the atmosphere of light supplied by the direction spectroscopic means. The projection type display device is characterized in that the angle spread θ _w at satisfies the following expression.

Θ _w <2θ _{0 Further} , according to the present invention (Claim 13), in the projection type display device (Claim 10), one modulation element in the modulation element group is supplied by the direction spectroscopic means. Projection type, characterized in that the width a of the portion of the modulator that does not contribute to the display and the width b of the portion that contributes to the display satisfy the relationship of the following formula with respect to the angular spread θ _w of the light in the atmosphere. A display device is provided.

Θ _w <θ ₀ (2a + b) / (a + b) Further, according to the present invention (Claim 14), in the projection type display device (Claim 13), the light is dispersed by the direction spectroscopic means of the optical diaphragm. width D _w of the aperture in that direction,
Provided is a projection-type display device characterized by satisfying the relationship shown in the following formula, where f is the focal length of the collimator lens.

[0027]

[Equation 11]

According to the present invention (Claim 15), in the projection display device (Claim 10), the thickness of N media between the imaging optical system and the modulator is t _i , When the refractive index is n _i (i = 1 to N), the angle θ _wa defined in the width W _a of the modulator shown in the following formula (a) and the θ _c shown in the following formulas (b) and (c). , And θ _s defined in the following expression (d) for the minimum circle diameter ΔA _max including the centers of the display contributing parts of all the modulation elements, the F value of the projection lens is Provided is a projection type display device characterized by satisfying (e).

[0029]

(Equation 12)

According to the present invention (claim 16), in the projection type display device (claim 10), an aperture stop is provided in the projection lens, and an area having a wavelength distribution of transmittance is provided in the aperture stop. Provided is a projection type display device characterized by being provided.

The present invention (Claim 17) includes, in the projection display apparatus (Claim 9), illuminance detecting means for detecting the brightness on or around the screen, and the light source light control means is provided with the illuminance detecting means. Provided is a projection type display device which controls a converging angle of the light source light based on an output of an illuminance detecting means.

According to the present invention (claim 18), in the projection display device (claim 9), there is provided a display panel driving means for supplying a video signal to the display panel, and the light source light control means is for the video image. Provided is a projection type display device which controls a converging angle of the light source light based on a brightness level of a signal.

According to the present invention (claim 19), in the projection type display device (claim 9), the F of the projection optical system is used.
The light source light control means includes an F value detection means for detecting a value, and the light source light control means provides a projection type display device for controlling a converging angle of the light source light based on the F value.

The present invention (Claim 20) provides the projection type display device (claim 2) which uses a light source which is not subjected to frost processing.

The present invention (Claim 21) provides the projection type display device which is the DC lighting light source or the AC lighting light source in the projection type display device (Claim 2).

Further, according to the present invention (claim 22), an elliptical focusing mirror having a concave reflecting surface on a part of a substantially elliptical surface is disposed in the vicinity of the first focal point of the elliptical surface of the elliptical focusing mirror and has a length of Light modulation having a light source having a light emitting portion of L, a collimator lens having a focal point near the second focal point of the elliptical surface and having a focal length of f, and a light modulation element having a lens array on the collimator lens side two-dimensionally In a light modulation element array used for a projection type display device including an element array and a projection lens, the distance between the lens array and the aperture of the modulation element is m, and the refractive index n between the lens array and the modulation element is Provided is a light modulation element array used in a projection type display device that satisfies the following expression, where S is the area of the element.

[0037]

(Equation 13)

According to the present invention (claim 24), in the light modulation element array (claim 23), there is provided an optical element for correcting the light ray direction, and when the light ray direction is corrected, a projection satisfying the following formula is satisfied. Provided is an optical modulation element array used in a display device.

[0039]

[Equation 14]

Θ ₁ : arctan ((μ / (1-μ))) θ ₂ : The angle of light emitted from the optical element that corrects the light ray direction when the light of θ ₁ is incident on the optical element that corrects the light ray direction According to the conventional projection type display device, the parallel light component of the light beam incident on the liquid crystal panel is lost due to the following reason, and the light having a large converging angle is incident. That is, since the light source having a certain finite light emission length is arranged perpendicularly to the parabolic condensing mirror, as shown in FIG. Is missing.
In addition, since the light source used in the conventional projection display device is subjected to a diffusion treatment called frost treatment on the surface of the quartz glass tube in order to reduce the color unevenness and the brightness unevenness, Larger ingredients increase.

However, such an incident optical system is not so problematic when it is used for a modulation element such as a liquid crystal which simply modulates incident light without having an ordinary microlens. When arranging a microlens array to reduce the transmittance loss due to the light shielding area of the liquid crystal panel, it is necessary to make more parallel light incident on the liquid crystal panel in order to improve the effective light transmittance. is there.

Therefore, in the projection type display apparatus of the present invention, as shown in FIGS. 3 (a), 3 (b) and 3 (c), the light modulation element 2 having the light source light condensing means composed of the microlens 1 With respect to the distance m between the microlens array 1 and the modulation area defining area, the refractive index n of the optical medium 3 between the microlens array 1 and the modulation area defining area, and the modulation element area S, the light emission length of the light source 4 By optimizing L, the shape parameters (major axis, minor axis) of the elliptical focusing mirror 5, and the focal length of the collimator lens 6, the effect of improving the effective aperture ratio by the microlens 1 can be enhanced.

It is important that the light flux has a predetermined angular distribution as long as the light source used in the projection display device is not a point light source. According to the present invention, the light source 4 is arranged in the vicinity of the first focus of the elliptical condenser mirror 5, the light source light is condensed in the vicinity of the second focus, and the substantially parallel light is converted into the light modulation element via the collimator lens 6. It is configured to lead to 2.

In order to achieve high brightness, which is an important item of the projection type display device, the parallelism of the incident light is increased, that is, the condensing light is taken into consideration, considering only the effect of improving the effective aperture ratio of the microlens 1. In order to reduce the angle, for example, a diaphragm means may be arranged near the second focus position of the elliptical focusing mirror 5,
When the focal length of the collimator lens 6 is increased, the total luminous flux incident on the light modulation element 2 is reduced, and high brightness cannot be achieved immediately.

That is, it is necessary to optimize the parameter size of the light source optical system by the parameter size of the light modulation element 2 having the microlens 1. In fact, the converging angle distribution of the incident light on the liquid crystal panel surface in the optical configuration of the present invention is as shown in FIG. 2, which is lower than that of the conventional parabolic mirror and the frosted light source. It is possible to reduce the high-convergence angle component without missing the converging angle component, and further to enhance the effective aperture ratio improving effect of the microlens without lowering the luminous flux.

Here, the outline of the optical system and the optical modulator of the present invention will be described.

The ellipse has two focal points, and the elliptical focusing mirror 5 having this shape has the light source 4 placed at the first focal position.
Has a function of condensing the light of the second focus position on the other side.

Here, when the light source 4 which is not subjected to the frost processing is arranged near the first focus of the elliptical mirror 5 and an image of the light source is formed near the other second focus, the size of the image is as follows. Conceivable. As the light source, it is desirable to use a light source that has not been subjected to frost processing from the viewpoint that the light emitting point is not enlarged by the frost processing.

That is, let us consider the diameter of the light source image that can be formed at the second focus position of the other ellipse when the light source is at the first focus of the elliptical mirror 5 as shown in FIG. 3 (a). At this time, the longitudinal direction of the arc or filament of the light source is assumed to be parallel to the optical axis of the ellipse.

As shown in FIG. 3A, when the major axis of the elliptical mirror 5 is 2A and the minor axis is 2B, the equation of the ellipse is expressed by the following equation (1).

X ² / A ² + y ² / B ² = 1 (1) Here, the optical axis of the ellipse, which is considered to have the strongest intensity of the light beam from the light source 4 irradiating the elliptic mirror 5, Consider the direction perpendicular to. The distance h from a certain focal point of the light source 4 to the position where vertical light is irradiated on the elliptical mirror 5 is expressed by the following equation (2).

H = B ² / A (2) Further, the distance W between the focal points is expressed by the following equation (3).

[0053]

(Equation 15)

Since the image reflected from the mirror 5 is considered to grow in proportion to the distance, the length L of the light source 4 is increased.
Is enlarged to the next size at the position of the second focal point.

[0055]

[Equation 16]

At this time, as shown in FIG.
Since light is obliquely incident on the position of the second focal point, the diameter Q ₁ in the direction perpendicular to the optical axis is 1 / cos with respect to the irradiation angle θ ₁ .
θ becomes ₁ time.

From the above consideration, the diameter Q ₁ of the image formed at the second focal point of the ellipse of the elliptical mirror 5 is given by the following equation (5).
Represented by

[0058]

[Equation 17]

However, μ = (B / A) ² .

This relational expression is obtained by greatly simplifying the light emission characteristics of the light source 4, but when experiments were conducted using several light sources and mirrors, the results were as shown in FIG. In FIG. 4, μ = (B / A) ² is plotted on the horizontal axis, and the ratio (Q ₁ / L) between the light source image diameter and the interelectrode distance is plotted on the vertical axis.

Considering using the coefficient α as in the following equation (6), it is slightly deviated from the above equation (5) where α = 1.
It is considered that this is because the light emission of the actual light source has a width in the direction perpendicular to the arc. From this experimental result, the actual image diameter Q ₁ is given by the following equation (6), and the value of α is 1
It is about 1.2.

[0062]

(Equation 18)

When the light source is arranged with the longitudinal direction parallel to the ellipse mirror (perpendicular to the optical axis of the ellipse mirror), the actual image diameter Q ₁ is expressed by the following equation (7). To be done.

[0064]

[Formula 19]

Further, it is effective to insert an optical element at the position of the light source image Q ₁ to control the direction of light rays diverging from the light source image to extend the focal length of the collimator lens and reduce display unevenness. Is. As an optical element that corrects such a ray direction, a convex or concave conical lens or
It suffices to insert one or more grating lenses.

Further, by controlling the positions of these optical elements, it is possible to control the illuminance unevenness of the light incident on the modulation element array, and consequently the brightness unevenness at the time of projection. Further, the optical element for correcting the direction of the light rays is provided in order to reduce uneven illuminance caused by the influence of the light source electrode portion or the like on the liquid crystal panel surface, which occurs when the light source is arranged perpendicularly to the elliptical condenser mirror. Is also effective.

In this case, the size of the light source image as seen from the collimator lens side is equivalently increased or decreased depending on the characteristics of the optical element in view of the geometrical optical conservation of the optical quantity. That is,
Geometric spread in source image
The maximum divergence angle θ _max1 of the angle of the light beam emitted from the light source image is
_When converted to _max2 , it seems that the light emitting area is increased by the change in the angle.

That is, as shown in FIG. 5, the divergence angle of the light from the light source image when there is no optical element is θ _max1 , and the divergence angle of the light emitted from the optical element is θ _max2 . If the divergence angle is θ ₁ and the angle at which the optical element corrects the direction of the light ray is Δθ, the divergence angle θ _{2 of the} light emitted from the optical element is
It becomes as shown in the following formula (8).

Q ₂ = Q ₁ · tan θ _max1 / tan θ _max2 (8) Now, by arranging a collimator lens for the divergent light from the light source image as described above, the light rays are made substantially parallel. You can That is, as shown in FIG. 3A, by arranging the lens 6 having a focus near the light source image viewed from the display panel side, it is possible to irradiate the display panel with parallel light rays. Of course, this light ray has an angular distribution corresponding to the size of the light source image, although it is parallel. This angular distribution is given by the following equation (9) from the size Q of the light source image and the focal length f of the collimator lens 6.

Θ = tan ⁻¹ (Q / 2f) (9) Now, when the lens array 1 a is arranged on the light incident side of the light modulation element array such as the TN liquid crystal panel, the lens array 1 a
A light source image is formed by the individual microlenses inside. When considering the intensity of light transmitted through the light modulation element 2, what is particularly important is the light intensity distribution on the surface on which the modulation element 2 is arranged. That is, the surface on which the modulation element 2 is arranged is, for example, between two glass substrates in the case of a normal TN liquid crystal panel, and the light transmission area on this surface is particularly important.

As shown in FIG. 3B, the distribution of light on this surface is expressed by the following equation (1) with respect to the angle θ of the incident light.
It is represented by 0).

W _p = 2 m · tan θ _n (10) where θ _n is the angle distribution θ of the incident light refracted by the refractive index n of the optical medium 3 between the lens array 1 a and the modulation element 2. The resulting angular distribution is expressed by the following formula (11).
Represented by

Θ _n = sin ⁻¹ (sin θ / n) (11) Next, consider the relationship between the light that has passed through the microlens and one modulation element in the modulation element array. Hereinafter, one of the modulation elements is called a pixel. As shown in FIG. 3C, the pixel of the modulation element array such as a liquid crystal panel is required to have a light transmission width smaller than the width of the pixel, and more preferably smaller than the width of the opening. . That is, it is desirable that the area through which light can be transmitted be smaller than the area fraction per pixel. Therefore, the intensity of transmitted light can be increased by making the intensity of light incident on the area of the light transmitting area stronger than that of the area of the light non-transmitting area. For this purpose, the width W _p in the above equation (10) needs to be equal to or less than the interval P at which the pixels are arranged. That is, W _p <P (12).

Now, this condition will be considered in more detail. Although it is W _p described above, the arrangement interval also depends on the form and direction of the pixel arrangement. For example, a typical lattice arrangement (stripe arrangement) in a liquid crystal panel as shown in FIG.
, The spacing is W _{y in} the vertical direction, W _{x in the} horizontal direction, and W _t in the diagonal direction. When the angular distribution of light rays incident on the pixel is symmetrical and uniform with respect to the optical axis of the microlens, circular light is incident on the incident surface of the pixel.

At this time, in order for the illuminance of the incident light in this circle to be stronger than in the case of a uniform illuminance distribution without a microlens, the following formula (13) is used rather than the area of one pixel. , It is necessary that the area of the circle is small.

Π (W _p / 2) ² <W _x · W _y (13) Similarly, even if the pixel is arranged in another arrangement or the angle distribution of incident light is asymmetrical and biased, If the available area is S _angle and the area of one pixel is S _pixel , the following expression (14) needs to be established.

S _angle ≦ S _pixel (14) Next, it is considered whether the smaller S _angle is, the better. First, that the S _angle is small means that the angle distribution width θ of the incident light or the distance m between the microlens and the pixel is small. However, in order to reduce θ, the size of the light emitting portion of the light source may be reduced,
It is necessary to suppress the aberration of the collimator lens. However, in general, a light source with a small light emitting portion often deteriorates the light emitting efficiency and the life, and it can be considered that the characteristics are deteriorated by reducing the light emitting portion.

As for the aberration of the collimator lens, a lens having a low aberration generally increases the cost, which is not desirable. Also, regarding the distance between the microlens and the pixel, it is necessary to shorten
It is necessary to reduce A, and this increases the angle of the light emitted from the pixel, which causes a reduction in the efficiency of designing the projection optical system. That is, it is better that the S _angle is large from these viewpoints.

Therefore, S _angle and the area S of the pixel opening are
Considering _A , if S _angle becomes smaller than S _A and all the light incident on the modulation element can be collected and transmitted through the opening, there is no need to further reduce S _angle .

In reality, the shape of the opening and the shape of the image formed on the pixel by the incident light do not necessarily match, so that the width W _{p of} the image should be equal to that of the opening in order to make all the rays incident on the opening. It suffices if it is less than the minimum width A _min . That is, for example, the distribution of the incident light is uniformly incident on the optical axis with a constant angular distribution θ, and the distribution of the circular incident light having a diameter W _p is formed on the pixel, and the opening is formed as shown in FIG. In the case of a rectangular shape as shown in FIG.
_{If x} is equal to W _p, and W _p = A _x (15) and the position of the incident light distribution and the aperture are completely overlapped, all the light can be transmitted. Also,
On the contrary, if W _p is made smaller than this, the amount of transmitted light does not increase, and conversely the above-mentioned disadvantages increase.

In practice, it may be necessary to make W _p smaller than A _x to some extent in consideration of the distribution of incident light and the alignment margin with the opening. Therefore, W _p
The minimum value of should be set slightly smaller than A _x .

As the actual alignment margin, the alignment accuracy in the liquid crystal panel assembling process can be referred to. In the case of a liquid crystal panel, the alignment accuracy is about ± 2 to ± 5 μm. If a microlens is formed on this with the same accuracy, ±
An error of 4 to ± 10 μm occurs. That is, 8 to 20
An alignment margin of μm is required. Considering this, W _p = A
It may be _x − (8 to 20) (μm).

That is, when a rectangular opening is considered in a rectangular pixel as shown in FIG. 6, the length of the short opening side is set to A.
_{When m} , the following formula (16) is established.

A _m − (8 to 20) μm ≦ W _p and π (W _p / 2) ² <W _x · W _y (16)

(Equation 20)

That is, since W _p = mQ / (f · n), the diameter of a circle having the same area as the pixel, that is, the following formula

[Equation 21]

The parameters of the major axis A and the minor axis B of the elliptical condenser mirror, the light emitting length L of the light source, the focal length f of the collimator lens, and the refraction between the microlens and the pixel are set so that W _p is made smaller than that. High efficiency can be achieved by setting the rate n and the distance m between the microlens and the pixel.

In addition to the above, as shown in FIG. 7, from the viewpoint of effectively utilizing the light component which is not reflected by the elliptical condenser mirror 5 and is not condensed at the second focus, the elliptical condenser mirror 5 is used. The light source light can be used more effectively by arranging the circular condenser mirror 7 so as to face it and returning the reflected light to the center of the light source.

In this structure, in order to reduce the unevenness of illuminance on the surface of the liquid crystal panel 8 and to shorten the effective light emission length, the light source electrodes are arranged horizontally with respect to the elliptical condenser mirror 5. In this case, when the light emitted from the light source 4 to the liquid crystal panel side cannot be effectively used, it is particularly effective to use the circular condenser mirror 7.

It goes without saying that even in the configuration in which the light source electrode is arranged perpendicular to the elliptical condenser mirror 5, it is effective for high brightness. Further, as in the present invention, in the configuration in which the light source light is condensed at the second focus by the elliptical condenser mirror 5, the opening of the circular condenser mirror 7 that is placed opposite can be made small, so that the efficiency is improved. It also has the effect of increasing. In FIG. 7, reference numeral 9 is a field lens and 10 is a conical lens.

When using a light source having a long distance between electrodes of the light source 4, or when using a frosted light source 4,
Since the angular distribution of the converging angle of the incident light on the liquid crystal panel is widened, the aperture control means is arranged near the second focus of the elliptical converging mirror 5 as mounted on the display device shown in FIG. 9 described later. By doing so, it suffices to remove the high-focusing-angle component and increase the parallelism. By doing so, it is possible to obtain a sufficient effect of improving the effective aperture ratio of the microlens.

Further, the aperture control means arranged in the vicinity of the second focus can freely control the converging angle distribution of the light incident on the liquid crystal panel and also control the illuminance unevenness incident on the liquid crystal panel. it can. If the aperture diameter is made small, the converging angle can be made small and the illuminance unevenness incident on the liquid crystal panel can be made small. However, by reducing the aperture diameter, the effect of reducing the effective aperture ratio of the microlens can be increased, but since the total luminous flux is reduced,
The screen illuminance at the time of projection decreases.

For this reason, the aperture diameter is controlled according to the illumination environment of the projection type display device. For example, in the case of use in a dark room, the aperture diameter is made smaller so as to reduce the unevenness of illumination than the projected illumination. However, when viewing in a bright room, you can use it to increase the aperture diameter in order to gain projection illuminance rather than uneven illuminance.

It goes without saying that the aperture control means may control not only the brightness of the room but also the brightness signal of the image. In addition, when trying to achieve a large screen by arranging a plurality of rear projection type display devices, it is problematic that the illuminance in the peripheral area between the projection type display devices is large. It is preferable to use a method of controlling the aperture diameter to be small.

However, from the viewpoint of achieving a bright projection type apparatus, since the problem that the total luminous flux decreases when the parallelism of the light source light is actually improved as described above, It is necessary to utilize the synergistic effect of the improvement effect of the microlens to cause the light flux with the optimum parallelism to enter the display panel, and the average diameter D (m) when using this diaphragm means is also the same as above. The distance L (m) between the nodal point of the collimator lens 6 and the center of the diaphragm forming the light source light control means, and the area of the pixel is S (m ² ).
And the distance m (m) between the node of the microlens and the pixel aperture is set so that the relationship of the following formula (17) is satisfied with respect to the refractive index n of the medium between the microlens and the aperture. By setting, it is possible to optimize the brightness improvement by the microlens.

[0095]

[Equation 22]

Further, as shown in FIG. 8, means for splitting the light emitted from the light source between the light source and the diaphragm means into two polarization waves of P wave and S wave which are orthogonal to each other, and
By providing means for matching one polarized wave front of the polarized wave with the other polarized wave front and means for condensing the diaphragm means, it is possible to increase the light intensity incident on the display panel, and a bright projection display device. Can be achieved.

Further, by using the above structure, in the ordinary polarization conversion optics in which the polarization conversion element is only arranged between the light source and the display panel, the angle distribution of the incident light on the display panel is not uniform, so that It is possible to solve the problem that it cannot be applied to a display panel equipped with a lens, and it is possible to control luminance unevenness by a diaphragm means or an optical element that corrects the light beam direction.

Further, as shown in FIG. 9, color separation means, means for making each color light incident on the display panel at a desired angle, and each color light imaged on each color pixel as shown in FIG. By providing such a means, it is possible to project a color image by using one display panel having no color filter. Therefore, the light resistance of the color filter does not pose a problem, and the light loss due to the color filter does not occur, so that the brightness can be increased.

A case where three dichroic mirrors are used as the directional spectroscopic means for making the color separation means and the liquid crystal panel enter at a desired angle will be described with reference to FIG. Of course, the dichroic mirror can be replaced by a prism. As shown in FIG. 10, the dichroic mirrors 11a, 11b, 11c that reflect the white light collimated by the collimator lens 6, for example, only blue, green, and red, respectively.
The angle of the light of each color incident on the liquid crystal panel can be controlled by controlling the angle at which the respective mirrors 11a, 11b, 11c are arranged using.

For example, white light with a width D _w is incident, reflected by three mirrors arranged at an angle of about θ = 45 degrees, and incident on the liquid crystal panel with an angle of about 90 degrees changed. . Green light is incident almost perpendicularly to the liquid crystal panel, whereas blue light and red light are incident at different angles by positive and negative angles Δθ, but those lights are in the same range at the position of the liquid crystal panel. It is designed to be incident on.

For this purpose, the angles of the three mirrors are inclined by Δθ as shown in FIG. 10, and the center position, that is, the point where the center of the incident light beam and the mirror intersect with each other is from the direction of the incident light beam. The following formulas (18) and (19) respectively
It is necessary to shift by d ₁ and d ₂ shown by.

D ₁ = L _m {tan (θ + Δθ) −tan (θ)} (18) d ₂ = L _m {tan (θ) −tan (θ−Δθ)} (19) L _m is shown in FIG. As shown, it is the distance between the center of the incident light beam and the display panel.

Similarly, when θ is not 45 degrees, it is desirable that the light beams are arranged under the condition that they match each other. Further, although the distances until the three light rays are incident on the display panel are different, since the intensity distribution of the light flux is changed depending on the distance due to a slight non-parallel component of the incident light flux, the optical path lengths of the respective colors are aligned. This is also important from the viewpoint of reducing display unevenness.
When it is desired to give priority to reducing the distance difference between the light fluxes of the respective colors, d ₁ and d ₂ are made smaller than the above equation.

Display is performed by using a microlens as an image forming optical system for guiding the light flux of each color having different angles formed as described above to a desired pixel of the liquid crystal panel. That is, when a plurality of adjacent pixels are called a pixel group (for example, red, green, and blue) on the incident side of the liquid crystal panel, by arranging a microlens for each pixel group, the wavelength in the unit pixel group is increased. By utilizing the fact that the angles of the incident light beams are different depending on, the color display can be realized by driving with the video signals corresponding to the colors incident on the respective different pixels.

The relationship between this spectral imaging optical system and the pixel groups is shown below.

The pixel groups are red R, green G, and blue B.
If the image forming optical system for each pixel group is composed of three pixels corresponding to the three colors, the lens having the size of the pixel group can be used. Light having a wavelength corresponding to R enters the opening of the R pixel, light of the G wavelength enters the opening of the G pixel, and B light enters the opening of the B pixel.

In this case, the relationship between the microlens array which is the image forming optical system, the counter substrate, the light shielding layer, the adhesive layer for adhering the microlenses, and the opening of the pixel is as shown in FIG.

In FIG. 11, it is assumed that the G light is incident on the display panel substantially perpendicularly, and the B light and the R light are incident on the G light at angles of θ _R and θ _B , respectively. This angle θ _R
And size P _{pi xel} size P _lens-- pixel microlens at an incident plane with theta _B is expressed as shown in the following formula (20).

[0109]

(Equation 23)

If the thickness and the refractive index of various materials such as the counter substrate and the adhesive layer between the microlens and the light shielding layer are t _i and n _i , respectively, the openings of the two pixels in the pixel group are formed. The distance between the centers of the two is ΔA, and the angle difference in the atmosphere of the light incident on each of the two pixels is θ.
_{When 0} (θ ₀ = θ _r = −θ _b , θ _g = 0) is satisfied, R, G, and B lights are incident on the openings of the respective pixels when the relationship shown in the following formula (21) is satisfied. To do.

[0111]

[Equation 24]

Actually, there is an angular distribution even in the light of one color supplied from the light source. If this is not sufficiently smaller than the angular distribution for each color created by the directional spectroscopic means, the light that should be made incident on the adjacent pixel is mixed and the colors are mixed, and color reproducibility is obtained for the color separated by the directional spectroscopic means. Deteriorates.

For example, when dividing into three colors of R, G and B,
The magnitude of the angular distribution of each incident light corresponds to the width of the image formed on the light shielding film portion of the incident light. Angle distribution width of incident light θ
_w is an independent R, G, B color without overlapping,
In order to obtain G and B, it is necessary to satisfy the following formula (22).

Θ _w <2θ ₀ (22) More strictly, considering the width a of the light-shielding portion and the width b of the opening, it is considered that the distance ΔA = a + b of the opening of the pixel corresponds to θ _0. For example, the following formula (23) is established.

Θ _w <θ ₀ (2a + b) / (a + b) (23) θ _w is determined by providing a diaphragm near the second focus position of the elliptical focusing mirror or using a light source with a sufficiently short emission length. You can deal with it. In this case, light in an unnecessary angle range can be removed as described above. Needless to say, the smaller θ _w is, of course, advantageous because the light efficiently enters the opening. However, if the light from the light source is largely lost in the light source light control means for that reason, the overall efficiency is rather deteriorated, and therefore it is necessary to optimize the entire display device.

When the angle distribution formed by the direction spectroscopic means is in one plane, the three pixels are arranged in a line. When pixels are arranged in a line as shown in FIG. 12B, a cylindrical lens having a refractive power in one direction can be used. Of course, it goes without saying that it is better to use a lens that also has a refractive power in other directions. For example, a convex lens having a refractive power in all directions may be used.

When a cylindrical lens is used, it is desirable to arrange the lenses so that the directions of the pixels lined up in a line within the pixel group are aligned in the direction of the refractive power.

Further, as shown in FIG. 12C, R, G, and B pixels are arranged every three adjacent pixels in one direction, and R, G, and B pixels are also arranged every three pixels in the vertical direction. In the case of a mosaic type in which is aligned, the positions of the pixels of the three colors are different from each other in the direction perpendicular to the array of the three colors, and the positions where the imaging optical system should be disposed are different from each other, and therefore the lenses must be disposed also in a staggered manner.

Further, as shown in FIG. 12A, it is also possible to use pixels having a triangle type arrangement. In this case, for example, a lens having a spherical convex lens shape that is rotationally symmetric with respect to the center point (optical axis) of the lens is arranged so that the center of the lens overlaps with the center of the opening of the three pixels of the pixel group. Good to do. Then, as the incident light flux, light of three colors having an incident angle which is calculated back from the distance between the central axis of the lens and the center of the aperture of each pixel by using the above equation may be incident.

Although the angle difference of the incident lights of the three colors does not exist in the same plane, if the dichroic mirror described above is used as the direction spectroscopic element, for example, a state where the reflected lights of the three colors deviate in three directions is created. Can be realized.

When such an image forming optical system having a refractive power in all directions is used, the following formula (24) is given for the vertical and horizontal pitches P = P _x and P = P _y of the pixel arrangement. Considering the angle θ _wm that satisfies the following formula (2)
It is necessary to enter a light beam having an angular distribution that satisfies 5).

[0122]

(Equation 25)

Θ <2θ _wm (25) Further, even when the direction spectroscopic means and the spectral imaging means as described above are provided, normal imaging is performed at the boundary between the spectral imaging means formed for each pixel group. If there is a region that does not exist, the light that has entered this portion may behave unintentionally, and light with an unintended wavelength may enter the pixel. Therefore, when the boundary between the spectral image forming means is uncertain, it is desirable to form a light shielding film in this part to suppress the transmission of light.

When a light source optical system including a light source that has not been subjected to the above frost processing, an elliptical focusing mirror and a collimator lens is used and a diaphragm means is arranged near the second focal position, a light beam emitted from the diaphragm Serves as a light source in the form of a diaphragm, which corresponds to the position distribution when incident light is collected by the liquid crystal panel. On the other hand, since the collimator lens corresponds to the image forming optical system, if the P _pixel has a diaphragm shape, the angular distribution of the light flux emitted from this light source can be estimated. On the contrary, it is possible to design the shape of the diaphragm so as to satisfy the above angle condition.

When the color imaging optical system has a refractive power only in a specific direction, that is, when the color imaging optical system has a direction not having a refractive power, the angular distribution in that direction is restricted. Not done. Therefore, considering the case of using a cylindrical lens as the color imaging optical system, for example, the width of the diaphragm that satisfies the above equation is set for the direction having the refractive power, and the width is set wider for the direction perpendicular to it. Can be widened.
Therefore, for example, an elliptical diaphragm or a rectangular diaphragm as shown in FIG. 13 may be used. Also, the aspect ratio is 1:
In the case of a diaphragm other than 1, it is desirable to align the major axis of the light emitting portion of the light source in the direction of the major axis of the diaphragm in order to efficiently focus light on the diaphragm.

It is desirable to use a light source optical system satisfying the above conditions, but even if it is not, a color filter is added to a pixel for a desired wavelength distribution of each color, and color mixture occurs next to each other. Can be prevented. Further, similarly, even when the capability of the direction spectroscopic unit or the spectral imaging unit is insufficient, it is possible to assist the color separation by forming a color filter in the pixel in an auxiliary manner.

Next, the conditions for projecting the light emitted from the liquid crystal panel will be considered.

As the projection optical system, it is necessary to use a projection lens having a sufficiently large entrance pupil diameter in order to efficiently project light emitted from the pixels at different angles.
That is, the angular distribution of the luminous flux emitted from the liquid crystal panel is a combination of the angular distribution θ _{w of} each color generated by the light source, the angular distribution θ _s generated by the direction spectroscopic means, and the angular distribution θ _c generated by the spectral imaging means. It will be a match.

The angular distribution θ _w generated by the light source and the angular distribution θ _c generated by the spectral image forming means are as follows. That is, with respect to the width W _a of the aperture of the pixel of interest and the microlens that is the spectral image forming means, the angular distribution θ _wa of the incident light beam that can pass through both is also shown in the following equation (26). Such a relationship is established (see FIG. 14).

(Equation 26)

The incident angle θ _wa which can be transmitted is compared with the angular distribution θ _w of the light rays incident from the light source, and the smaller incident side is the effective incident angle distribution θ _ew .

When the focal length f of the lens is converted into the focal length f _air in the atmosphere, the angular distribution θ _c generated by the lens which is the spectral image forming means is relative to the focal length f _air and the entrance diameter P of the lens. , As shown in the following formula (27).

Θ _c = 2 tan ⁻¹ {P / (2f _air )} (27) Actual focal length f of lens and focal length f _air in the atmosphere
Is the following formulas (28) and (28) for the thicknesses t _i and the refractive indices n _i (i = 1, 2, ..., N) of the N media through which the light emitted from the lens passes to the focal point. 29).

[0133]

[Equation 27]

Angular distribution of emitted light for a single pixel θ _px
Is represented by the following formula (30).

[0135]

[Equation 28]

The angular distribution of the emitted light from the entire pixel group is the angle θ generated by the direction spectroscopic means in the above θ _px.
s is added. θ _s is obtained by the following formula (31) indicating the diameter ΔA _max of the smallest circle including the centers of the openings of all the pixels in the pixel group that are color-separated.

[0137]

[Equation 29]

ΔA _max is the distance between the furthest pixels in the pixel group, for example, when the pixels in the pixel group are arranged in a straight line. For example, the pixel group is arranged at the apex of an equilateral triangle. When it is composed of pixels, ΔA _max = 2T for the length T of one side of the equilateral triangle.
/ 3.

By using the above θ _s , the final distribution width θ _out of the outgoing light flux can be obtained by the following equation (32).

Θ _out = θ _px + θ _s (32) That is, when three pixels are arranged on a straight line, the maximum inter-pixel distance is 2ΔA, which is twice ΔA. This also corresponds to 2θ ₀ , which is twice θ ₀ . Therefore, in addition to the above θ _px , the final distribution width θ _out of the luminous flux is calculated by the following formula (3
It is represented by 3).

[0141]

[Equation 30]

Further, when the spectral image forming means for the pixels arranged in a triangle is provided, each pixel in the pixel group is not on a straight line, but the maximum distance ΔA between the openings of the three pixels is ΔA.
θ _s can be determined by applying _max to the above equation.

In order to efficiently project the light having the above-mentioned angular distribution of the emitted light, it is desirable that the condensing angle θ _col of the projection lens be larger than the angular distribution θ _out of the emitted light. That is, if the F-number, which is often used as the parameter indicating the characteristics of the projection lens or the photographing lens, is used as the converging angle θ _col , it can be expressed as the following formula (34).

[0144]

[Equation 31]

However, the distribution of the light emitted from the liquid crystal panel θ _out
The F number of the projection lens needs to satisfy the following expression (35) for projecting.

[0146]

[Equation 32]

[0147]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection type liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 15, this projection type liquid crystal display device 10
0 is a three-plate type, that is, three liquid crystal panels 201-R, 201-G for red (R), green (G) and blue (B).
201-B.

The light source optical system of the projection type liquid crystal display device according to the present embodiment has a spheroidal reflecting mirror 121 and this reflecting mirror 1.
A clear type DC lighting type 250W metal halide light source (arc length 3 mm) 111, which is arranged in the vicinity of the first focal point 21 and which is not subjected to frost processing, a cold mirror 131, and a collimator lens 141 are provided.

The light source light from the light source 111 is once condensed near the second focal point by the elliptical reflecting mirror 121, then passes through the cold mirror 131, and is collimated by the collimator lens 141 as parallel light beams in each of the liquid crystal panels 201-R and 201. -G, 2
01-B. A microlens, which is a light source light converging unit, is arranged on the light incident side of each liquid crystal panel, and a field lens and a projection lens are arranged on the emission side of each liquid crystal panel.

Here, as the shape parameters of the elliptical condenser mirror, the major axis A = 60 mm and the minor axis B = 44.72 m.
The distance from the center of the ellipse to the first focus and the second focus is 40 mm, and the focal length of the collimator lens is 1
An optical system configuration of 47 mm was used.

Further, in the projection type liquid crystal display device according to this embodiment, the light source 111 is fixed vertically to the elliptical reflecting mirror 121 because of the simplification of the positional accuracy with respect to the elliptic reflecting mirror 121. Due to the influence of the electrodes and the like of 111, the light flux at the central portion of the light source light becomes small. Therefore, in the light source optical system of the projection type liquid crystal display device according to this embodiment, the light source 1
A convex conical lens 161 (vertical angle 120 °) is arranged on the diaphragm means 151 side between the diaphragm 11 and the diaphragm means 151.

The conical lens 161 acts as an optical element (middle gap correcting element) that corrects the direction of the light beam that prevents the intensity of the central portion of the light beam from being reduced due to being blocked by the electrode portion of the light source. Incidentally, the convex conical lens 161
In addition to the above, a concave cone lens, a lens composed of one or more grating lenses, a diffuser, or the like may be used as long as it guides a light beam that is diverged and is not effectively used. It may be. The apex angle of the conical lens is preferably 100 to 140 degrees, but may be optimized depending on the refractive index of the glass material used for the lens.

Here, when the light source is arranged perpendicularly to the elliptical reflecting mirror, the void correction element is not necessarily used. Further, in FIG. 15, an aperture control means capable of controlling brightness and illuminance unevenness by additionally adding,
The means for detecting screen illuminance or ambient illuminance is also shown.

Next, each liquid crystal panel 201-R, 201-
The arrangement of G and 201-B will be described. The light source light from the light source optical system passes through the UV-IR filter, only the green (G) light is reflected by the first dichroic mirror 411, and the green (G) light is reflected by the second total reflection mirror 413. It is guided to the liquid crystal panel 201-G. And
After the green (G) light passes through the optical liquid crystal panel 201-G,
The light is emitted through the first field lens 415.

Of the light source light transmitted through the first dichroic mirror 411, only the red (R) light is reflected by the second dichroic mirror 417 and is guided to the liquid crystal panel 201-R. Then, the red (R) light transmitted through the liquid crystal panel 201-R is transmitted through the second field lens 419 to the first
The synthesizing mirror 421 synthesizes the green (G) light that has passed through the liquid crystal panel 201-G.

The light source light transmitted through the second dichroic mirror 417 is guided to the liquid crystal panel 201-B, and the blue (B) light transmitted through the liquid crystal panel 201-B is reflected by the third field lens 423 and the third total reflection mirror. A second synthetic mirror 427 is reached via 425, where red (R) is transmitted through the liquid crystal panels 201-G and 201-R and synthesized.
The light and the green (G) light are combined and guided to the projection optical system.

Next, the liquid crystal panels 201-R and 201
-G and 201-B will be described. The liquid crystal panel 2
The configurations of 01-R, 201-G, and 201-B are the same except for the drive system, so that the liquid crystal panel 2 for green (G) is used.
01-G will be described as an example. This liquid crystal panel 201-
G has 100 micron pitch display pixels in the horizontal direction 64
The liquid crystal panel 2 consists of 0 pieces and 480 pieces arranged in the vertical direction.
As shown in FIG. 15, a pair of polarizing plates 203 and 205 are arranged on both main surfaces of 01-G at predetermined intervals so that their polarization axes are substantially orthogonal to each other.

As shown in FIGS. 16 and 17, the liquid crystal panel 201-G has an array substrate 211 and a counter substrate 311.
In between, the TN type liquid crystal 401 is held between the substrates 211 and 311 so as to be twisted by 90 ° via the alignment films 291 and 391.

The array substrate 211 is composed of a 0.7 mm thick transparent glass substrate 210 and a signal line 22 as shown in FIG.
1 and the scanning line 231 are arranged so as to be substantially orthogonal to each other, and a thin film transistor (hereinafter abbreviated as TFT) 241 is arranged near the intersection of the signal line 221 and the scanning line 231. As shown in FIG. 17, this TFT 241 uses the scanning line 231 itself as a gate electrode, and the amorphous silicon thin film 245 as a semiconductor layer on the scanning line 231 via the gate insulating film 243, and the amorphous silicon thin film 245 as a semiconductor layer. In order to protect and suppress parasitic capacitance, a semiconductor protective film 246 made of silicon nitride formed in a self-aligned manner with the scan line 231 is provided.

Further, the TFT 241 has a drain electrode 247 extending from the signal line 221 for electrically connecting the amorphous silicon thin film 245 and the signal line 221 via the n ⁺ type amorphous silicon thin film 248. , ITO (I) disposed in a region surrounded by the signal line 221 and the scanning line 231.
Pixel electrode 2 made of ndium tin oxide)
51 and the amorphous silicon thin film 245 are electrically connected to each other via the n ⁺ -type amorphous silicon thin film 250.
And 49. In this way, the TFT 241 having the inverted stagger structure is formed.

Further, an auxiliary capacitance line 253 for forming an auxiliary capacitance (Cs) between the pixel electrode 251 and the gate insulating film 243 is arranged substantially parallel to the scanning line 231. Furthermore, the TFT 241 and the pixel electrode 25
A protective film 255 is disposed on the first layer 1. In this way, the array substrate 211 is configured.

The counter substrate 311 is composed of a transparent glass substrate 310 having a thickness of 0.7 mm and the TFT 24 of the array substrate 211.
1 and a matrix-shaped light shielding layer 313 made of chromium (Cr) for shielding light around the pixel electrode 251; a protective film 317 disposed on the light shielding layer 313; and a counter electrode made of ITO disposed on the protective film 317. 319 and 319. The liquid crystal panel 201-G configured as described above has achieved an aperture ratio of 36%.

As shown in FIG. 15, a microlens array substrate 511 is attached via an adhesive layer 510 on the main surface of a counter substrate 311 (thickness 0.7 mm). Here, the thickness of the adhesive layer 510 is about 20 μm. The microlens array substrate 511 is composed of a group of condensing lenses 513 corresponding to each display pixel, and the focal position of the condensing lenses 513 is set so as to exist on the glass substrate 210 forming the array substrate 211. The focal length of the microlens in air is 0.6 mm.

Next, an experiment on the effect of improving the brightness of the liquid crystal panel with the microlens constructed as described above in the three-plate type optical system having the above optical parameters will be shown.

First, the nine-point average light flux when using the same optical system but using a liquid crystal panel without a microlens was 249 lm (9-point average light flux is 4
Projecting on a 0 inch screen, as shown in FIG.
It is the luminous flux obtained by multiplying the projection area by the average value of the projected illuminance at the center of nine rectangles, which are obtained by dividing the projection screen into three vertically and horizontally).

On the other hand, in a liquid crystal panel with a microlens, the nine-point average luminous flux is 374 lm, which is about 1.5 times (brightness ratio 54%) improvement in brightness as compared with a liquid crystal panel without a microlens. I found that I could achieve it.
At this time, the value of W _p = m · Q ₂ / (f · n) is 50.3.
It is μm 2 (S / π) is sufficiently smaller than ^1/2 = ^110.6μm (here, theta ₂ in Q ₂ is 30 °).

Next, an experiment was conducted for the case where the distance m between the microlens and the pixel was reduced so as to further reduce the W _p value. The counter substrate thickness is 0.5 in order to reduce m.
The same experiment was conducted with the unit of mm. As a result, the 9-point average luminous flux was 405 lm, which was 1.62 times (effective aperture ratio 59%) as compared with the case of using a liquid crystal panel without a microlens. As described above, by reducing the thickness of the counter substrate, the value of m is reduced and the value of W _p is also reduced, so that the effect of improving the effective aperture ratio by the microlens is increased.

Next, the data of the dependence of the other parameter, the focal length f of the collimator lens, will be shown. In the above optical system, by shortening the focal length of the collimator lens, the light kicked by the collimator lens unit can be suppressed. Therefore, when f = 110 mm, even when a liquid crystal panel without a microlens is used,
The nine-point average luminous flux is 338 lm, which is about 1.35 times.

When the focal length of the collimator lens is shortened, the converging angle of the light incident on the liquid crystal panel becomes large.
The total luminous flux increases. The measurement result of the converging angle with two f values is about 8 degrees (± 4 degrees) in the case of f = 147 mm, and about 12 degrees (± 6 degrees) in the case of f = 110 mm.
(Here, the converging angle is defined as the width of the full angle at which the light intensity is 50% of the peak light intensity). Therefore, although the total luminous flux increases, it is expected that the effect of improving the effective aperture ratio of the microlenses in the panel with microlenses will decrease because the parallelism of the incident light decreases.

Actually, when f = 110 mm and the counter substrate thickness is 0.
In the case of using a liquid crystal panel with a 7 mm microlens, the 9-point average luminous flux is 420 lm, which is brighter than that of 0.7 mm when f = 147 mm, and f = 147 mm.
1.68 compared to the liquid crystal panel without micro lens
Although doubled, the effective aperture ratio is 46%, which is lower than that in the case of f = 147 mm. Shortening f reduces the effect of improving the effective aperture ratio of the microlens because the value of W _p increases, but the total luminous flux to the liquid crystal panel surface becomes 1.35 times as described above. Therefore, the brightness is improved as a whole.

Further, when f = 110 mm, the counter substrate thickness is 0.5.
For 9 mm, the 9-point average luminous flux is 493 lm, which is also brighter than the counter substrate thickness of 0.5 mm at f = 147 mm, and is 1.97 as compared with the case of using a liquid crystal panel without microlenses at f = 147 mm. Doubled. The effective aperture ratio is 53%, and the W _p value is lowered due to the reduction of the counter substrate thickness, and the microlens effect is increased as in the above case. Of course, in any of the above cases. W _p
It goes without saying that <2 (S / π) ^1/2 is satisfied.

FIG. 19 shows measured values showing the effect of the effective aperture ratio due to the microlens effect on the change in the counter substrate thickness that contributes to the distance m between the microlens substrate and the light-shielding region that defines the opening of the modulation element ( Focal length f of collimator lens f = 147 mm). The counter substrate shows a maximum at a thickness of about 0.5 mm, and if it is thicker than that, the effective aperture ratio is significantly reduced. If the counter substrate becomes thicker, the panel aperture ratio (36%) without the microlens is transmitted. It can be seen that the rate decreases.

Here, the light emission length L of the light source also determines W _p . In the above embodiment, the electrode length of 3 mm is used, but it goes without saying that the electrode length may be optimized in consideration of the effect of improving the total luminous flux and the effective aperture ratio of the microlens. May be used,
All parameters including the shape of the elliptical focusing mirror may be optimized.

Here, depending on the shape parameters (major axis A, minor axis B) of the elliptical condenser mirror and the light emission length L of the light source, a focused light diameter Q ₁ at the second focus position or a correction element in the light ray direction is inserted. Although it has been explained that the microlens effect can be optimized by the value of Q ₂ in this case, instead of Q ₁ and Q ₂ , a diaphragm means is arranged in the vicinity of the second focal position so that the light enters the liquid crystal panel. It goes without saying that the control of the light collection angle may be performed.

Assuming that the diameter of the diaphragm means is D, the condition for enhancing the microlens effect is expressed by the following equation (36):
It becomes as shown in (37).

[0176]

[Expression 33]

Here, the converging angle θ _w of the light incident on the liquid crystal panel is obtained from the above D and the focal length f of the collimator lens by the following formula.

Θ _w = 2 tan ⁻¹ (D / 2f) (37) FIG. 20 shows that the maximum illuminance near the center of the screen is 0.498 m ² when the display area is 40 inches and the ratio of width to height is 4: 3. )
The dependence of the peak luminous flux (lm) on the converging angle is shown. The converging angle was changed by controlling the aperture diameter. As shown in FIG. 17, when a liquid crystal panel having no microlens is used (curve a), the peak luminous flux is greatly reduced as the converging angle θ _w is narrowed, but a liquid crystal panel having a microlens is used. In the case (curves b and c), the decrease is small. This is because the smaller the converging angle and the more parallel the incident light, the greater the effect of improving the effective aperture ratio of the microlens.

As described above, the effect of the microlens is that the effective aperture ratio improving effect is enhanced by optimizing the counter substrate thickness (thinning in the above case) corresponding to the pixel size. As shown in FIG.
The fact that the brightness is improved more when the opposing substrate thickness is 0.5 mm (curve c) than when it is mm (curve b) and the decrease in brightness due to the decrease in the light collection angle is small. I understand.

Here, reducing the converging angle of light incident from the liquid crystal panel by using the diaphragm means brings about a decrease in brightness, but has an advantage of reducing unevenness in illuminance of a display image.

Next, the results of measuring the illuminance unevenness of the display image of the three-plate projection display device 100 and the results of measuring the brightness unevenness of the display image of the conventional projection display device 901 shown in FIG. 1 as a comparative example are shown. The results are shown in Table 1 below.
It should be noted that the display image is an entire white display which is enlarged and projected on a screen in a diagonal size of 40 inches, and is displayed on the screen as shown in FIG.
The illuminance at the point was measured by an illuminometer, and the illuminance at the point 5 was displayed as a ratio of 100. In addition, the light collection angles (θ) in the examples are 8 °, 6 °, and 4 °.

Table 1 point 1 point 2 points 3 points 4 points 5 points 6 points 7 points 8 points 9 Example 1 (8 °) 32 61 30 38 100 38 33 60 32 Example 2 (6 °) 42 68 40 47 100 48 45 69 40 Example 3 (4 °) 59 87 57 64 100 65 55 84 56 Comparative example 23 43 24 27 100 26 20 40 24 As shown in Table 1 above, the projection display device 100 according to this example According to the above, it can be seen that, compared with the conventional projection display device, it is possible to obtain a good display image in which the brightness unevenness is extremely small in the central portion and the peripheral portion of the display image.

Therefore, in the projection type display apparatus according to this embodiment, it is visually good that the contrast ratio is higher than the display luminance unevenness in a bright environment, that is, in a bright environment. Since it is recognized as a display image, the converging angle θ _w of the diaphragm means 151 is determined by the diaphragm control means 7.
By using 21, it is possible to control within a sufficiently large range.

Further, in a dark environment where the illuminance on the screen is large, that is, in the dark environment, it is visually recognized that the display brightness unevenness is small, so that the converging angle θ _w is
It is also possible to control the diaphragm means so as to control within a relatively small range where the brightness unevenness is reduced. Further, even when one display image is divided into a plurality of blocks to be displayed, if the condensing angle θ _w is controlled within a relatively small range, the brightness decrease at the joint is less noticeable.

For example, according to the projection type display apparatus 100 in this embodiment, the screen illuminance, which is a slightly dark illumination environment such as various showrooms and AV rooms, is 30 (l).
In the case of x), by setting the converging angle θ _w to 4 to 6 °, while maintaining the contrast ratio of 100: 1 or more, in FIG. %
Since the display brightness unevenness is small and the contrast ratio is high by suppressing the display ratio to 1, a good display image is visually recognized.

When the screen illuminance is 200 (lx), which is the illumination environment in a normal office or a general home, the converging angle θ _w is set to 8 ° or more to
A high peak luminous flux of 0 (lm) or more is obtained, and moreover, as shown in FIG.
By suppressing the decrease in the illuminance at the point 1 with respect to the point 5 at a rate of about 30% at which it is difficult to visually recognize the display unevenness, a good display image is visually recognized.

As described above, according to the projection type display apparatus 100 in this embodiment, the light source optical system is designed so that the condensing angle θ _w becomes smaller as the screen illuminance becomes smaller. By controlling the converging angle θ _w , it is possible to prevent the uneven brightness of the display image and obtain the display illuminance according to the screen illuminance.

In this embodiment, the three-plate projection type display device 100 has been described as an example, but the liquid crystal panel itself is provided with a color filter composed of color portions of at least three primary colors arranged in a stripe shape, a mosaic shape or a delta arrangement. , Fig. 2
1. A single plate type projection display device 10 configured as shown in FIG.
Needless to say, 0 is acceptable.

In addition to this, each liquid crystal panel 201-
Convergence angle θ _{w of the} light source light for each of R, 201-G and 201-B
It is also possible to provide a diaphragm means for controlling the above, and individually control the converging angle θ _w of the light source light for each color. Needless to say, such characteristics can also be applied to the case of using a liquid crystal panel that does not use microlenses.

Further, in this embodiment, the diaphragm means 15
A configuration is also possible in which the condensing angle θ _{w of} 1 is controlled by the aperture control unit 721 according to the environmental illuminance signal ES. In addition, each liquid crystal panel 201-R, 201-G, 201-B
It may be controlled based on the luminance signal of the video signal VS supplied to, or a combination of these may be used.

For example, based on the difference between the temporal average intensity of the luminance signal included in the video signal VS and the blanking level (black level) of the luminance signal, when the difference is small, the converging angle θ.
By controlling the converging angle θ _w to be large when _w is small and the difference is large, it is possible to secure a good display image without depending on the display brightness of the display image.

In this embodiment, the aperture control means 721 controls the aperture diameter D of the aperture means 151 to control the converging angle θ _w , but by moving the aperture means 151 along the optical axis of the light source 111. The effective aperture diameter D may be controlled to control the light collection angle θ _w .

Here, as the light source used in the above-mentioned embodiment, one not subjected to the frost treatment for diffusing the light from the light source was used. This is used because it is effective in increasing the efficiency of collecting the light from the light source to the diaphragm means, but of course, a frosted one may be used. Further, in the above embodiment, a direct current lighting type light source was used as the light source. This is also because the DC lighting type light source is optimal for the above optical system in that the light emission distribution between the anode and the cathode can be made smaller than that of the AC lighting type light source. However, it goes without saying that an AC lighting type light source may be used.

Further, as in the above-mentioned embodiments, the microlenses may be arranged only on the incident side or the emitting side. Microlens array substrate 41 only on the incident side
When 1 is arranged, the light focused by the microlens array substrate 411 near the light shielding layer 313 of the counter substrate 311 is
Since the light diverges thereafter, there is a risk that the light utilization efficiency will be reduced due to kicking of the projection lens. Therefore, when using the microlens array substrate 411, it is important to select the focal position of each condenser lens 413 of the microlens array substrate 411.

That is, it is necessary to select the focal position so that the light source light, which is spread after being converged by each condenser lens 413, is sufficiently contained in each field lens. In particular, if the miniaturization of each field lens is achieved, the focal position of each condenser lens 413 is better to be away from the light incident side.
However, as the focus position of each condenser lens 413 moves away from the light incident side, the effect of the microlens array substrate 411 decreases and the effective aperture ratio of the liquid crystal panel 201-G decreases. Therefore, the focal position of each condenser lens 413 is preferably set inside or outside the substrate on the emission side rather than inside the TN type liquid crystal 401.

Particularly, in this embodiment, since the thickness of the glass substrate 310 of the counter substrate 311 is 0.7 mm or less,
The focus position of each condensing lens 413 is set to be within a distance of 0.8 to 1.1 mm from the microlens array substrate 411, that is, within the glass substrate 210 so that the transmitted light is sufficiently contained in the first field lens 415. Good.

That is, when a microlens is arranged on the incident side of the liquid crystal panel, the light condensed by the microlens diverges after that, as shown in FIGS. 23 (a), (b) and (c). The effective aperture ratio of the projection display device largely depends on the F value of the projection lens. That is, when the focal position of the microlens is shortened, the modulated light after passing through each liquid crystal panel has a large degree of divergence until it enters the projection lens, and the projection lens is used to improve the brightness of the projection display device. It is necessary to increase the lens diameter or to reduce the focal length, resulting in a smaller F value.

23 (a), (b) and (c) show the effective aperture ratio of a projection type display device having a microlens on the vertical axis.
F of effective aperture ratio when F value of projection lens is taken on the horizontal axis
Shows value dependency. Of these, FIG. 23A shows a case where the light source light has a converging angle of 4 degrees, and the curves (A), (B), (C), (D), and (E) are shown in the figure. , The effective focus position of the microlens (considering the refractive index of the counter substrate, etc.) is 0.56 mm, 0.7 mm, 0.84 mm,
The case of 1.05 mm and 1.4 mm is shown. Also,
23B and 23C show the cases where the light source light collection angles are 6 degrees and 8 degrees, respectively. From these figures, it can be seen that when the focal length of the microlens is shortened, the dependency of the F value of the projection lens increases.

In the projection type display device, a zoom type is used as the projection lens in order to enlarge / reduce the projected image. Therefore, when the projection lens is on the wide angle side,
The value is about 4, but it increases to about 5 on the telephoto side. Therefore, in the projection display device, the F of the projection lens is
It is preferable that the brightness of the display image is not easily affected by the fluctuation of the value. That is, when the image is projected from a position greatly separated from the projection display device and the screen, the image is projected on the telephoto side, and in a situation where the peripheral brightness is likely to be lowered due to the magnified projection or the like. In order to reduce the uneven brightness, it is preferable to control the diaphragm diameter by the diaphragm means to be small so as to reduce the brightness unevenness.

As described above, in the projection type display device,
It is not always effective to shorten the focal length of the microlenses, and the total effective position of the microlenses in the projection display device is within the liquid crystal layer or on the emission side substrate (array substrate in this embodiment) side. It is desirable for improving the aperture ratio.

By setting the focal position of the microlens as described above, the design of the lens diameter of the projection lens has a degree of freedom, and the downsizing and cost reduction of the apparatus can be achieved.
Further, by setting the focal length of the microlens as described above, even if the F value of the projection lens fluctuates when enlarging / reducing the display image, fluctuations in the effective aperture ratio of the projection display apparatus can be suppressed. It is possible to obtain a uniform display image brightness.

Incidentally, with respect to the variation of the F value of the projection lens,
In order to secure a more uniform display image, the aperture diameter of the diaphragm means may be controlled according to the variation of the F value. For example, when a long-distance projection is performed and the projection lens is set to the telephoto side, the F value increases and the brightness unevenness increases, but the brightness unevenness decreases by reducing the diaphragm diameter of the diaphragm means to reduce the light collection angle. Can be suppressed. On the contrary, when it is desired to improve the central brightness, the overall brightness can be improved by increasing the aperture diameter of the diaphragm means to increase the light collection angle.

In the curve (c) of FIG. 20, the focal position of the microlens of the curve (b) of FIG. 20 is set to 0.8 mm from the microlens substrate, while the focal position is 1. 4 shows the converging angle dependence of the peak light flux when the F value of the projection lens is 4 mm and is set to 5 on the projection lens side.

From this figure, by making the focal position of the microlens longer, the peak light flux itself is slightly decreased, but the dependence of the peak light flux on the converging angle can be further reduced, and the low converging angle setting is performed. It is also possible to improve the uniformity of display brightness.

Further, in the above embodiment, as the diaphragm control means shown in FIG. 15, the servo motor is built in and the circular opening diameter is changed by the servo motor, but the shape of the opening is a quadrangle or an ellipse. May be Further, the structure may be such that a light shielding plate that shields the upper and lower sides, the right and left sides, or both of the openings is operated by a servo motor.

Considering that the closer the focal position of the microlens is to the light source side, the more the effective aperture ratio when passing through the liquid crystal panel is improved, it is effective to set the glass substrate thickness of the counter substrate thin. Some things have already been explained. Therefore, if the counter substrate thickness is set thin, the focal position of the microlens can be set long without lowering the effective aperture ratio of the liquid crystal panel, which improves the effective aperture ratio of the projection display device. It Moreover, since the focal position of the microlens can be set long, there is an advantage that the effective aperture ratio of the projection display device does not largely depend on the variation of the F value of the projection lens.

By the way, as shown in FIG. 21, in the projection type display device of a single plate type, the back focus length of the projection lens can be shortened because the optical system has a relatively simple structure, and thus the projection lens can be shortened. The F value can be reduced to about 2.2 to 4. Therefore, it is important to optimize the numerical aperture NA (NA = n · sin δ) and the focal length of the microlens according to the F value or the numerical aperture NA of the projection lens. That is, it is desirable that the numerical aperture NA of the microlens is designed to be smaller than the numerical aperture NA of the projection lens so that kicking in the projection lens can be suppressed.

Here, a hollow defect correcting element for correcting the direction of a light beam for reducing the unevenness of illuminance incident on the liquid crystal panel surface will be described. As described above, when the light source is arranged perpendicularly to the elliptical condenser mirror, uneven illuminance occurs. Therefore, in the above embodiment, a conical lens having an apex angle of 120 degrees is used to correct the decrease in the intensity of the central position of the light flux. At this time, due to the effect of correcting the direction of the light beam, the light beam diameter Q ₂ at the second focal position becomes about 2.5 times larger than Q ₁ when the conical lens is not used. Then, the uneven illuminance of the light source whose illuminance at the center is lowered is refracted by both inclined surfaces of the conical lens to correct the light from each inclined surface to the central portion, thereby correcting the void. .

For such correction of the ray direction, the optical characteristics of the conical lens can be replaced by a grating lens. That is, a grating lens having a concentric circular or spiral groove having an inclined surface with a constant angle (apex angle 60 degrees) as shown in the sectional view of FIG. 24 may be used.

FIG. 25 (a) shows the concept of hollow correction when a grating lens having apex angle θ of 60 ° and grooves of 200 μm pitch formed concentrically is used. In the display element using such a grating lens 103, most of the light emitted from the upper half of the left circle 302 on the incident side comes to the lower half of the circle 304 on the right side, and slightly to the upper half of the circle. Things that will arrive will come. In this way, even if the hollow source light 302 is used on the left incident side, the light intensity is reinforced at the center on the right emitting side.

Here, in the central portion of the liquid crystal panel, lights having two kinds of directivity are mixed. Therefore, in order to improve the illuminance distribution and the uniformity of the microlens effect, the apex angle is set so as to reduce the mixture, or the two-element configuration is used as shown in FIG. The grating lenses 203 and 204 may be used.

FIGS. 26A to 26D show the illuminance distribution on the liquid crystal panel surface depending on the position of the grating lens in the case of the single-lens configuration as an example. Here, the value of z is the distance from the second focus position, and the + direction indicates the movement distance to the liquid crystal panel side. In this way, by changing the position of the void correction element, it is possible to control the illuminance distribution, and it is necessary to reduce the illuminance unevenness. For example, in applications such as data projectors, the second focal point of the spheroidal reflector is used. Near the position (z =-
It can be used for moving to z = 10 mm (to the liquid crystal panel side) so as to increase the center strength for video applications. The same thing can be done with a convex conical lens or the like, although the optimum position changes slightly.

Now, an optical system configuration for further improving the efficiency of the optical system having the above configuration will be described. In the above optical system, almost all the light is focused at the second focal position by the elliptical focusing mirror. However, a component that is not reflected or condensed by the elliptical condenser mirror appears on the liquid crystal panel side. for that reason,
As shown in FIG. 7, a circular condensing mirror 7 having an opening may be arranged so as to be opposed to the elliptical condensing mirror in order to effectively use the above-mentioned light components. The effect of improving the total luminous flux was measured by using a circular radius of 60 mm and an opening diameter of 44 mm.

As a result, it was confirmed that an improvement of about 1.2 times could be achieved regardless of the presence or absence of the microlens. At this time, as the light source, a light source that has not been subjected to the frost treatment as described above is used, and it is usually used to efficiently return the light reflected by the circular mirror 7 to the light emitting portion of the light source.
A liquid crystal panel without a heat insulating film was used. Further, as in the above-mentioned embodiment, a DC halide type metal halide lamp having an anode arranged on the liquid crystal panel side was used. DC
In the lighting type, the one in which the anode is arranged on the liquid crystal panel side is preferable because the illuminance distribution is better.

In this composite condensing mirror structure, since the main condensing mirror is an elliptical mirror, light is condensed at the second focal position and the opening of the second circular mirror can be made small, so that the efficiency is high. It is easy to improve the improvement effect. Also,
In this configuration, the light source is not arranged vertically to the elliptical condenser mirror, but is arranged in the horizontal direction to reduce the uneven illuminance caused by the electrode portion acting as a shadow. It is needless to say that it is even more effective when the emitted light component that does not face the mirror is used effectively.

Next, an example of applying the polarization conversion technique as an efficiency improving means in the case of using a light modulation element requiring a polarizing plate such as a TN type liquid crystal to the above optical system will be described.
Since the conventional correction conversion element optical system has a structure for splitting a light beam, it has been difficult to apply it to an optical system using a microlens to improve the effective aperture ratio. Therefore, as a modified example of the present invention, as shown in FIG. 8, a polarization conversion element is provided between the elliptical condenser mirror and its second focal position.
There is an optical system in which a λ / 4 plate, a reflecting mirror, a concave prism, and a conical lens are arranged.

The source light is incident on the polarization conversion element and divided into P-wave and S-wave components, and the S-wave component passes through the λ / 4 plate, is converted to P-wave, and is then reflected by the reflection mirror. Is
The P wave component is reflected by the reflection mirror and is again combined at the second focal position. Then, the liquid crystal panel is similarly irradiated through the collimator lens.

FIG. 8 shows a single liquid crystal panel for the sake of simplicity. With such a configuration, the liquid crystal panel introduces the light, which has the light flux converged at the second focal point position as the point light source, into the panel with the microlens. Therefore, the effect of improving the effective aperture ratio of the microlens is similar to the above. It is characterized in that it is achieved almost uniformly on the panel surface. It goes without saying that a polarizing plate may be provided in front of the liquid crystal panel from the viewpoint of improving the contrast ratio.

Next, an embodiment of a projection type display device which achieves color display with one panel without using a liquid crystal panel with a color filter will be described with reference to FIG.

First, the optical system configuration will be described from the light source side.
A DC lighting 250 W metal halide lamp 4 without frost treatment similar to the above, a white light flux from this light source, an elliptical focusing mirror 5, a circular focusing mirror 7, and a conical lens 1.
The light is focused on the diaphragm by 0 (here, the elliptical condenser mirror, the circular condenser mirror, and the conical lens are the same as those used in the above embodiment). The light flux that has passed through the diaphragm is converted into parallel light rays by the collimator lens group 13. This light beam is incident on the direction spectroscopic means composed of three dichroic mirrors.

The R luminous flux is reflected by the first mirror,
It is incident on a liquid crystal panel having a spectral image forming means by microlenses. Similarly, the G light flux is incident on the spectral imaging means by the second mirror and the B light flux is incident on the spectral imaging means by the third mirror. When TN liquid crystal is used, polarizing plates are arranged before and after the liquid crystal panel.

The R and B light fluxes are about 4.
It is designed to be incident with an angle difference of 8 degrees. Due to these angle differences, as shown in FIG. 23, the light of three colors is divided into three pixels by the microlens and enters the pixels of the display panel. The light flux emitted from the display panel is focused by the field lens, enters the projection lens, and is enlarged and projected on the screen by the projection lens.

Next, the optical construction of the projection type display apparatus according to this embodiment shown in FIGS. 9 and 10 will be described in detail.

First, the liquid crystal panel used was formed by the same method as in the above-mentioned embodiment. The number of pixels is 60μ in the horizontal direction.
1920 pixels at m intervals and 480 pixels at 180 μm intervals in the vertical direction, the diagonal size of the display is 144 m.
It has become m. The number of pixels in the horizontal direction is VGA display (64
The number of pixels is three times the number of pixels (0 pixels), and no color filter is mounted, but pixels corresponding to RGB are arranged. The pixel arrangement is a stripe arrangement, and the pixel group has 3 pixels horizontally.

The spectral image forming means used in this embodiment is a microlens, and as shown in FIG. 12B,
For example, a cylindrical lens is formed on a glass substrate, and a light-shielding film having a width of 20 μm is formed so as to shield light between the lenses. Since the pixel groups are continuous at the same horizontal position in the vertical direction, the apparent spacing is 180 μm.
It has a stripe shape. This is an interval of three horizontal pixels and satisfies the above relational expression.

The focal length is set to 1.4 mm for glass having a refractive index of 1.54. This has a refractive index of 1.5 between the microlens and the pixel.
4, a 1.1 mm-thick counter substrate, and a refractive index of 1.5 of an acrylic adhesive that bonds the microlens and the counter substrate,
Considering a thickness of 0.03 mm, the focal point is set to be closer to the emission side than the pixel portion.

The pixel aperture is 31.5 μm in the horizontal direction and 135 μm in the vertical direction in each pixel.
It has a substantially rectangular shape of m.

In the present embodiment, the light incident on the liquid crystal panel is not affected by the spectral image forming means in the vertical direction, so that the angular distribution of the light flux emitted from the light source is substantially equal to 10 degrees. Incident on. On the other hand, in the horizontal direction showing the refracting power, the light is condensed and diverges after it is emitted from the panel, so that the incident angle to the projection lens is increased. In order to estimate this angle, equation (26) and equation (2
7), the equation (30) is applied to calculate the angular distribution θ _px of the incident light flux for a single pixel.

First, the angular distribution θ _ew = θ _wa of the effective light flux to the liquid crystal panel is _calculated by the equation (26) so that the width W _{a of the} opening is W _a = 3.
From 1.5 μm, θ _ew = 2.5 degrees. Also, the formula (2
From 8), the focal length of the microlens with respect to the medium having the refractive index of 1.54 is 1.4 mm and f _{air is} 0.91 mm. Therefore, the angular distribution θ _c generated by the microlens is _calculated from the effective width P = 160 μm of the microlens.
From Expression 27, θ _c = 10 degrees. Therefore, the effective horizontal incident angle of each pixel is θ _px = 12.5 degrees. Further, the incident angle difference θ _s generated by the direction spectroscopic means is θ _s = 9.6 degrees from the equation (31).

Therefore, in this embodiment, in order to effectively magnify and project these lights, the F value satisfying the equation (35) must be F = 2.6 or less.
= 2.5 bright projection lens was used.

Next, the setting of the diaphragm means of the light source section will be described. The light flux from the light source is condensed at the position of the diaphragm by the elliptical mirror, the circular mirror and the conical lens.
The shape of the light beam emitted from the diaphragm is limited by the diaphragm, and the shape limitation is converted into the angular distribution limitation by the collimator lens. The direction of the arc of the light source (the direction between the electrodes) is oriented in the direction perpendicular to the paper surface of FIG. Further, as shown in FIG. 26, the diaphragm has a rectangular shape that is long in the direction of the arc. From the focal length of the collimator lens of 170 mm, the emitted light flux is approximately parallel to the paper surface of FIG. It is 4 degrees and about 10 degrees with respect to the direction perpendicular to the paper surface. Also, the collimator lens is
It is designed to be achromatic, including the shape of a conical lens.

The white light flux emitted from the collimator lens is reflected by the dichroic mirror arranged at about 45 degrees with respect to the optical axis. These are directional spectroscopic means. In order to satisfy the separation angle of 4.8 degrees required by the relationship between the display panel and the spectral image forming means, the dichroic mirror is 45-4.8 / 2 = 42.6 degrees with respect to the incident light.
The dichroic mirror is 45 + 4.8 / for incident light.
2 = 47.4 degrees. The position of each mirror is 9 from the center of the dichroic mirror.
According to formulas (18) and (19), the mirror is incident on the 7.9 mm light source side and the mirror is incident on the opposite side of the 7.3 mm light source from the center point so that they overlap at the position of the display panel arranged at a distance of 0 mm. They are spaced apart along the direction.

Of the incident light, only the B component is first reflected by the dichroic mirror, then the G component of the light flux transmitted through the dichroic mirror is reflected by the dichroic mirror, and the remaining R component is reflected by the mirror. R
The mirror that reflects the component is a dichroic mirror,
It may also be a total reflection mirror. In this way, white light is split into light beams having the required angle.

According to this embodiment, the maximum projected light flux is 400.
It was possible to achieve a very bright projection display device reaching lm. With a display panel of the same size using an absorption type color filter and using the same light source, 230 l
It was about m, and the present invention could obtain a brightness of about 1.7 times.

In the case of using the color filter, the temperature of the central portion of the screen is likely to be higher than the surroundings due to the light absorption of the color filter, and display unevenness is likely to occur. However, since there is almost no light absorbing element in the display panel portion, cooling can be sufficiently performed by simple air cooling with an electric fan, and display unevenness does not occur.

As described above, a bright and high-performance projection display device with less display unevenness can be realized by the structure of the present invention.

In the above embodiments, the case where the TN liquid crystal is used as the liquid crystal layer has been described, but any liquid crystal layer may be used, and a digital mirror device (DMD) element or the like may be used. . In that case, the difference in the emission angle for each color generated by the direction spectroscopic means becomes a problem.

In these elements, the projection optical system is provided with a diaphragm, but since the emission angle differs depending on the color, a plurality of diaphragms are required for each color. That is, since the emitted light from the liquid crystal panel has an angular distribution for each color, the field lens divides into R, G, and B at the stop position of the projection lens unit, and a stop having openings corresponding to each is required. Becomes At this time, if three aperture stops are simply formed, the remaining two aperture stops other than the apertures corresponding to the respective colors of light are also effective, and desired characteristics cannot be obtained. Therefore, by providing the color filters A, B, and C that match the colors of the respective rays in the diaphragm of the projection optical system, the diaphragm can be operated independently for each color (FIGS. 22A and 22B). reference).

Further, the size of the diaphragm needs to correspond to the angular distribution θ _px of the emitted light of the pixels of each color. This time,
Even if the size of the diaphragm becomes large relative to the interval of the plurality of diaphragms determined by the separation angle θ _s by the direction spectroscopic means and the light emitted from the liquid crystal panel passes through the field lens and reaches the diaphragm of the projection lens unit, R, G In many cases, the colored lights of B and B overlap each other. In this case, A, B, C, D, E
By providing a color filter corresponding to the wavelength distribution of the incident light in each overlapping area of each color or each independent area, the same light collection angle can be set for each color and uniform and excellent characteristics can be obtained. .

Next, a modification of the above embodiment will be described with reference to FIG.

The optical configuration is almost the same as that described above, but after the light source light is collimated by the collimator lens, the infrared rays are removed by the cold mirror and the path is changed by 90 degrees. And the liquid crystal panel has a pixel interval of 180 μm in the horizontal direction and 156 μm in the vertical direction, the number of pixels is 508 in the horizontal direction and 440 in the vertical direction, and the pixel arrangement is a triang arrangement. The opposite substrate thickness is 1.1 mm.

FIG. 27 is a diagram showing how the three primary colors of RGB are exchangeably separated in this embodiment.
Incident light traveling in three directions at an angle of about 8 degrees from the vertical direction with respect to the liquid crystal panel has a position distribution in pixels by the microlens, and each of RGB passes through an appropriate pixel.

Further, in this projection type display device, a bright lens of F = 2.5 is used in order to efficiently project the divergent light generated by the direction spectroscopic means and the spectral imaging means.

Further, although an example in which a mirror inclined at about 45 degrees is used as the direction spectroscopic means has been shown, it goes without saying that other angles can be applied.

Further, as the liquid crystal panel of the above-mentioned embodiment, an active matrix type liquid crystal panel in which a switch element composed of a TFT is provided for each display pixel has been described as an example. However, the TFT is a polycrystalline silicon film or a single film. The switch may be composed mainly of a crystalline silicon film, and the switch element may be an MIM (Metal Ins) other than the TFT.
Alternatively, an element (ultra metal) may be used. Further, as the liquid crystal panel, in addition to the active matrix type liquid crystal panel, a simple matrix type liquid crystal panel in which striped electrodes hold the liquid crystal composition and are arranged substantially orthogonal to each other may be used.

Further, the present invention is not limited to the contents shown in the above-mentioned embodiment, and the display panel is not limited to the TN liquid crystal, and is one which two-dimensionally modulates the light intensity from the light source and is a modulation element array. It is sufficient if the STN liquid crystal or the ferroelectric liquid crystal is used, and it is also possible to use a digital mirror device (DMD) or the like other than the liquid crystal.

Further, as the display device, the projection type display device of the type that projects forward is shown as an example, but as the projection type display device, the direction opposite to the direction in which the image is projected from one surface of the screen is projected. It goes without saying that it is also effective for a rear projection display device that is observed from above.

Further, in the above-mentioned embodiment, as the direction spectroscopic means, the one having the structure of three mirrors is used, but it goes without saying that a prism block, a micro prism, a diffraction grating or the like may be used. It goes without saying that a hologram optical element or the like having both the functions of the direction spectroscopic unit and the spectral image forming unit may be used.

[0249]

As described above, according to the projection type display device of the present invention, it is possible to obtain a display image having high brightness and good display quality without uneven brightness.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a conventional three-panel projection type display device.

FIG. 2 is a characteristic diagram showing a light collection angle distribution of light source light on a liquid crystal panel surface.

FIG. 3 is a diagram for explaining a light source optical system of the projection type display device of the present invention.

FIG. 4 is a characteristic diagram showing the relationship between the ellipticity of an elliptical focusing mirror and Q ₁ / L in the light source optical system of the projection display apparatus of the present invention.

FIG. 5 is a diagram for explaining a light source optical system including an optical element that corrects the light ray direction in the projection display apparatus of the present invention.

FIG. 6 is a diagram showing a pixel structure and a stripe arrangement in the projection display device of the present invention.

FIG. 7 is a diagram showing a light source optical system in which a spherical converging mirror is added to an elliptical converging mirror in the projection type display device of the present invention.

FIG. 8 is a diagram showing an optical system to which a polarization conversion optical system is added in the projection type display device of the present invention.

FIG. 9 is a diagram showing an optical system in which a direction spectroscopic unit and a spectral coupling unit are added in the projection type display device of the present invention.

FIG. 10 is a diagram for explaining the direction spectroscopic means in FIG.

11 is a diagram for explaining the spectral coupling means in FIG.

FIG. 12 is a diagram illustrating a relationship between a pixel array and a spectral coupling unit in the projection display device of the present invention.

13 is a diagram showing the shape of a diaphragm used in the optical system shown in FIG.

FIG. 14 is a diagram illustrating an angular distribution generated by a spectral coupling unit.

FIG. 15 is a diagram schematically showing a three-plate type projection display device according to an embodiment of the present invention.

16 is a plan view showing a part of a liquid crystal panel of the display device shown in FIG.

17 is a cross-sectional view taken along line 17-17 of FIG.

FIG. 18 is a diagram showing illuminance measurement points of a projected display image.

FIG. 19 is a characteristic diagram showing the thickness of the counter substrate and the effective aperture ratio.

FIG. 20 is a characteristic diagram showing the converging angle dependence of the peak light flux.

FIG. 21 is a diagram showing an outline of a single-panel type projection display device according to another embodiment of the present invention.

FIG. 22 is a diagram illustrating spectral characteristics of a color filter inserted in a projection lens entrance part.

FIG. 23 is a characteristic diagram showing the F-number dependence of the effective aperture ratio.

FIG. 24 is a cross-sectional view of a grating lens that corrects the ray direction.

FIG. 25 is a diagram illustrating the principle of a grating lens.

FIG. 26 is a characteristic diagram showing changes in the illuminance distribution with respect to changes in the position of the grating lens.

FIG. 27 is a diagram illustrating the direction of light incident on a liquid crystal panel according to a second modification of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Microlens 2 ... Light modulation element 3 ... Optical medium 4,111 ... Light source 5 ... Elliptical condensing mirror 6 ... Collimator lens 7 ... Circular condensing mirror 8 ... Liquid crystal panel 9 ... Field lens 10 ... Conical lens 100 ... Projection display device 151 ... First diaphragm means 201, 201-R, 201-G, 201-B ... Liquid crystal panel 411 ... Microlens array substrate 413 ... Condensing lens 501 ... Projection lens

Claims (16)

[Claims] 1. A light modulation means for controlling light transmittance mainly using light birefringence or optical rotatory power, a light source optical system for guiding light source light from a light source to the light modulation means,
And a projection type display device having a projection optical system for projecting the modulated light modulated by the light modulating means onto a screen, wherein the light source optical system controls a light source and a converging angle of the light source light from the light source. Light source light control means, the light source light control means, means for condensing the light source light from the light source, diaphragm means arranged in the vicinity of the position where the light source light is condensed,
A projection type display device comprising a collimator lens. 2. An elliptic focusing mirror having a concave reflecting surface on a part of a substantially elliptical surface, a light source arranged near the first focal point of the elliptic surface, and a collimator lens having a focal point near the second focal point of the elliptic surface. , Having a lens array on the collimator lens side and having an area S
In a projection-type display device including a light-modulating element array in which light-modulating elements having two-dimensionally are arranged, and a projection lens, the length of the light-emitting portion of the light source is L, and the short diameter of the ellipse of the elliptical focusing mirror is When the square of the ratio of the major axis is μ, the focal length of the collimator lens is f, the distance between the lens array and the aperture of the modulator is m, and the refractive index n between the lens array and the modulator is:
A projection display device characterized by satisfying the following formula. [Equation 1] 3. The projection type display device according to claim 2, further comprising an optical element for correcting a light ray direction in the vicinity of the second focus of the ellipsoid or between the second focus position and the collimator lens. . 4. The projection display device according to claim 3, wherein the following formula is satisfied. [Equation 2] θ ₁ : arctan ((μ / (1-μ))) θ ₂ : The angle of the light emitted from the optical element that corrects the ray direction when the light of θ ₁ is incident on the optical element that corrects the ray direction. 5. The projection type display device according to claim 4, further comprising an adjusting mechanism for adjusting a spatial intensity distribution of a light beam from the light source light by an optical element that corrects the light ray direction. 6. A condenser mirror, which is arranged between the elliptical condenser mirror and the light modulation element array device so as to face the elliptical condenser mirror, and which has a reflecting surface on a part of a substantially spherical concave surface. The projection type display device according to claim 2, wherein the projection type display device is arranged. 7. A means for branching the light emitted from the light source into two polarized waves orthogonal to each other, which is arranged between the light source and the second focal point position of the ellipsoid, and the two polarized waves. 3. The device according to claim 2, further comprising: a unit that matches a polarization plane of one polarized wave with a polarization plane of the other polarized wave; and a condensing unit that condenses the polarized plane near the second focal position of the ellipsoid. Projection display device. 8. The lens array according to claim 2, wherein the lens array has a focal position on an optical path farther from the light source than a position of a light blocking member that defines an opening region of the light modulation element. Projection type display device. 9. The light source light control means comprising an optical diaphragm is provided in the vicinity of the second focal point of the ellipsoid, and the following formula is satisfied, where D is the diameter of the optical diaphragm. Projection display device. (Equation 3) 10. A directional spectroscopic unit that gives different emission directions to the light emitted from the light source between the light source and the light modulation element array, depending on the wavelength of the light, and the light spectrally dispersed by the directional spectroscopic unit. In the modulation element group consisting of a plurality of modulation elements, there is at least one pair of modulation elements having different wavelength distributions of incident light, and the spatially separated spectral coupling between the modulation elements of the modulation element group. 3. The projection display device according to claim 2, further comprising an image means, wherein each of the modulation elements is driven by a drive signal corresponding to a color of the incident light. 11. The thickness of the N optical media between the lens that is the spectral image forming means and the member that defines the display area of the modulation element array device is t _i , and the refractive index is n _i (i = 1 to
N), the distance between the centers of the display contributing portions of two adjacent modulators in the modulator group is ΔA, and
11. The projection according to claim 10, wherein there are at least one pair of two modulation elements that satisfy the following equation, where θ ₀ is an angle difference between the light incident on each of the two modulation elements in the atmosphere. Type display device. [Equation 4] 12. The angle spread θ _w in the atmosphere of the light supplied by the directional spectroscopic means to one modulation element in the modulation element group satisfies the following expression: The projection display device described. θ _w <2θ ₀ 13. A width a of a portion that does not contribute to the display of the modulation element with respect to the angular spread θ _w of the light supplied by the direction spectroscopic means to one modulation element in the modulation element group in the atmosphere. 11. The projection display device according to claim 10, wherein the width b of the portion that contributes to the display satisfies the relationship of the following expression. θ _w <θ ₀ (2a + b) / (a + b) 14. The relation expressed by the following formula is satisfied, where D _{w is} the width of the stop of the optical stop in the direction separated by the direction separating means and f is the focal length of the collimator lens. The projection type display device according to claim 13. (Equation 5) 15. An N located between the imaging optical system and the modulator.
Let t _{i be} the thickness of each medium, and let n _i (i = 1 to 1) be the refractive index.
N), the width W _{a of the} modulation element shown in the following formula (a)
Θ _wa defined by the following equations (b) and (c)
To indicate theta _c, and are shown in the following formula (d), the diameter of the smallest circle containing the center of the display contribution of all modulation element .DELTA.A _max
The projection display device according to claim 10, wherein the F value of the projection lens satisfies the following expression (e) with respect to θ _s defined with respect to. (Equation 6) 16. The projection display device according to claim 10, wherein the projection lens is provided with an aperture stop, and an area having a transmittance wavelength distribution is provided in the aperture stop.