JPH10257413A - Image display device, light source device and liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the influence of scattering light on a liquid crystal display device transmitting a rectangular pixel opening through a microlens array. SOLUTION: A lamp 2 is arranged at the focal position of reflector 3. The Z direction of the optical axis is irradiated with light collimated from the reflector 3. At such a time, the lamp 2 is arranged vertically to the Z axis of the optical axis, namely, in the direction of the Y axis. Thus, the scattered light is enlarged in the Y-axis direction and reduced in the X-axis direction. Therefore, the influence of scattering is reduced by matching the Y-axis direction of larger scattering and the lengthwise direction of pixel opening on the liquid crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image display device used for a projector or the like that projects light using a spatial modulation element such as a liquid crystal, a light source device thereof, and a liquid crystal projector.

[0002]

2. Description of the Related Art As shown in FIG. 5A, a projection television projects light from the front toward a screen S and views an image from a projection direction, as shown in FIG. 5B. There is a rear projection system in which light is projected onto the screen from the back using a pair of mirrors M1 and M2, and an image is viewed from the surface. In such a projection television, a CRT or a liquid crystal is used for a projector portion. FIG. 6 is a diagram showing a configuration of a projector using a liquid crystal. The difference between the front type and the rear type is only the presence or absence of a mirror, and the principle configuration is the same. In this figure, a lamp 2 such as a metal halide lamp is disposed at a focal position of a reflector 3. The reflector 3 has a parabolic mirror and converts light into parallel light. A liquid crystal display panel 6 sandwiched between polarizers 4 and 5 is disposed in front of the reflector 3, and a screen 8 through a projection lens 7.
It is configured to project light thereon.

FIG. 7 is a sectional view and a front view showing a structure of a light source portion. As shown in these figures, the metal halide lamp 2 is arranged at the focal position of the reflector 3 of the rotating parabolic mirror with the longitudinal direction of the lamp facing the optical axis direction.

FIG. 8 shows a first conventional liquid crystal display panel 21 using a microlens array 11 to improve the luminance. The microlens array is configured by arranging fine convex lenses 12 in a matrix, and the lens of the microlens array 11 is opposed to each pixel of the liquid crystal display panel 21. The liquid crystal display panel 21 is composed of a glass substrate 25 on which a grid-like black matrix region 23 and a transparent electrode 24 on which wiring for driving the TFT 22 is provided and a glass substrate 26 on which a common full-surface electrode is formed. The liquid crystal material 27 is sealed between them. A portion of the transparent electrode 24 surrounded by the black matrix region 23 is a pixel opening 28, and each lens 12 of the microlens array 11 is arranged to face each pixel opening 28 of the liquid crystal display panel 21. .

When the microlens array 11 is not used, as shown in FIG. 9A, a part of the light beam incident on the liquid crystal display panel is shielded by the black matrix region 23, so that the light use efficiency is reduced. However, the brightness of the image display device decreases. On the other hand, when the microlens array 11 is used, light rays incident on each lens 12 of the microlens array 11 are condensed in each pixel opening 28 of the liquid crystal display panel as shown in FIG. 28 can be transmitted. The use efficiency of light is improved by using the micro lens array 11 in this manner,
The brightness of the image display device can be increased.

Next, a second conventional example of the liquid crystal projector disclosed in JP-A-4-60538 will be described.
In this liquid crystal projector, as shown in FIG. 10, light emitted from a light source is transmitted to dichroic mirrors 31R, 31G, 3G.
1B. Dichroic mirror 31R, 31
G and 31B reflect three colors of red, green, and blue, respectively, of the incident light and transmit the other light to split the light. The split light is incident on the liquid crystal display panel 33 via the microlens array 32. FIG.
Are R, G, B emitted from the dichroic mirror 31
FIG. 3 is an enlarged view of three pixels of a microlens array 32 and a liquid crystal display panel 33 on which light is incident. The dichroic mirror 31 tilts the red light R at -α, the green light G at 0, and the blue light B at + α. LCD panel 33
Have different pixel openings 3 corresponding to the three primary colors of RGB, respectively.
4B, 34G, and 34R are arranged as shown in the figure.
Since the directions of the three colors of RGB light are different, one microlens transmits the adjacent R, G, B pixel openings. In this way, the light use efficiency can be improved without using a color filter. Thus, the light transmitted through the liquid crystal display panel 33 is configured to be projected on the screen 8 by the Fresnel lens 35 and the projection lens 7.

[0007]

However, the metal halide lamp used as the light source is not a perfect point light source as shown in FIG. 7, and its shape becomes larger when the luminance is increased. In particular, the light emitting portion is longer than the thickness of the lamp, and in order to increase the luminance, the length of the light emitting portion needs to be longer, and there is a disadvantage that the spread angle increases. For this reason, as shown in FIGS. 9 and 11, even if light is condensed by using a microlens array and allowed to pass through the pixel aperture, the light cannot be sufficiently stopped due to the spread of light from the light source. For example, as shown in FIG. 12, if the spread angle of the light incident on the microlens array 11 is ± Δθ, and if the distance between the microlens array 11 and the pixel opening 28 is L1, the light spot W at the pixel opening will be It is shown by the following equation. W = 2Δθ · L1 Therefore, when W is equal to or larger than the actual pixel aperture of the liquid crystal display panel, there is a disadvantage that the amount of light shielded around the aperture increases and the light utilization efficiency decreases.

In a liquid crystal projector in which the direction of light is changed by light of different colors as in the second conventional example, the light of each color incident on the microlens array 32 has a predetermined angle, that is, 0 and ± α from each other ±
Similarly, in the case of having a spread of θ, there is a disadvantage that the light use efficiency is reduced if the spread angle Δθ is large. Further, there is a disadvantage that the light is mixed due to the spread of the light from the light source and the color reproducibility is reduced.

The present invention has been made in view of such a conventional problem, and an object thereof is to make it possible to easily pass through a pixel opening of a liquid crystal display even if light spreads. .

[0010]

According to the first aspect of the present invention, there is provided a linear light source having a predetermined length, collimating means for collimating the light source to convert the light into parallel light, and a plurality of pixels each having a pixel opening which is long in one direction. And a microlens array composed of microlenses for converging the collimated light to each pixel aperture of the spatial modulation element, and an optical axis of light emitted from the collimating means. And the longitudinal direction of the light source is vertical, and the longitudinal direction of the light source is arranged so as to correspond to the longitudinal direction of the pixel opening of the spatial light modulator.

According to a second aspect of the present invention, the microlens array is constituted by a set of rectangular microlenses corresponding to a longitudinal direction of a pixel opening of the spatial light modulator. is there.

According to a third aspect of the present invention, there is provided a linear light source having a predetermined length, collimating means for collimating the light source to convert the light source into parallel light, and separating the collimated light into three primary colors. A light demultiplexing element that splits into three directions of collimated light having different emission angles, a spatial modulation element that is long in one direction surrounded by a black matrix, and has a grid-like pixel opening arranged for each of three colors, Microlenses corresponding to each of the three color pixels in the pixel aperture of the spatial modulation element are formed, and light emitted from the optical demultiplexing element is condensed by the microlens and corresponds to each of the emission angles. A microlens array in which the distance between the microlens and the pixel opening is set so as to pass through the pixel opening of color, and the optical axis of the light emitted from the collimating means and the light source A longitudinal and vertical, it is characterized in that the longitudinal direction of the light source is arranged so as to correspond to the longitudinal direction of the opening of the space modulation element.

According to a fourth aspect of the present invention, there is provided a linear light source having a predetermined length, and collimating means for collimating the light source to convert the light into parallel light. The light source is arranged so as to be perpendicular to a longitudinal direction of the light source.

According to a fifth aspect of the present invention, there is provided an image display device according to any one of the first to third aspects, which is disposed on an emission side of the image display device.
It has a projection lens for projecting transmitted light on a screen.

[0015]

FIG. 1 is a front view and a sectional view showing the structure of a light source according to an embodiment of the present invention. Also in this embodiment, as in the above-described conventional example, a metal halide lamp 2 is used as a light source, and a reflector 3 of a rotating parabolic mirror is used as collimating means for converting light from the light source into parallel collimated light. This metal halide lamp 2 is arranged at the focal position of the reflector 3. In this embodiment,
Optical axis (Z axis) emitted from the reflector 3 of the rotating parabolic mirror
The longitudinal direction of the lamp is arranged in a vertical direction (for example, the Y-axis direction). In this way, the light emitted from the reflector 3 has a larger divergence angle in the Y-axis direction as shown in the figure, and can have a smaller divergence angle in the X-axis direction perpendicular thereto.

FIG. 2 is a diagram showing the overall configuration of a liquid crystal projector using this light source. The same parts as those in the above-described conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, the Y direction of the light source is arranged so as to be in the longitudinal direction of the pixel opening of the liquid crystal display panel 5, and the light of the light source is transmitted through a predetermined optical system as shown in FIG. Light enters the display panel. With a liquid crystal display panel for color display,
Three primary colors of RGB are formed in a rectangular shape, and these form one pixel of a square shape. That is, as shown in FIG. 3, on the upper surface of the first glass substrate 41, a grid-like black matrix region 43 provided with wiring for driving the TFT 42 and a transparent electrode 44 are formed. The liquid crystal material 46 is sealed between the upper surface and the glass substrate 45 on which the front common electrode is formed. A portion of the transparent electrode 44 surrounded by the black matrix region 43 is a pixel opening 47, and has a 3
Pixels of primary colors are configured adjacently. 3 of these RGB
One pixel is formed by color pixels, and a color filter is arranged in front of each pixel. Glass substrate 45
A microlens array 48 in which rectangular microlenses corresponding to the respective pixels are arranged in an amount corresponding to the pixel apertures is formed on the upper surface, so that light is incident on the respective pixels. Since the three color pixels forming each pixel are formed in a rectangular shape as described above, the optical system is arranged such that the longitudinal direction of the rectangular shape is aligned with the Y-axis direction at which light is dispersed. In this way, the influence of light dispersion can be reduced. Therefore, even when the luminance is increased by using a relatively large metal halide lamp as a light source, the influence of light dispersion can be reduced, and light can be used effectively.

Next, a second embodiment of the present invention will be described. In this embodiment, as shown in the second conventional example described above, dichroic mirrors 31R, 31G, 31D
The light is dispersed using B, and the incident direction of the light is changed in accordance with the color of each light so that the light passes through the pixel opening. In this embodiment, as shown in FIG. 4A, the XZ direction of the liquid crystal display panel, and FIG. 4B, the YZ direction, the red light R is -α, the green light G is 0, and the blue light B is + α. Due to having a direction, light passing through the same microlens passes through the pixel aperture corresponding to each color. Also in this case, the influence of light dispersion can be reduced by setting the Y-axis direction where light dispersion is large to the longitudinal direction of each lens.

In this embodiment, a metal halide lamp as a light source is arranged at the focal position of the reflector 3 as shown in FIG. 1, but another linear light source may be used. It goes without saying that the collimating means can be constituted by using a focusing lens for focusing light instead of the reflector 3.

[0019]

As described above in detail, according to the first to third aspects of the present invention, even when a lamp having a certain direction is used as a light source for an image display device, the influence of the spread is also used. Can be minimized, and the effect of improving the light use efficiency can be obtained. According to the fourth aspect of the invention, it is possible to generate collimated light having a large light spread only in a specific direction. According to the fifth aspect of the invention, there is obtained an effect that a liquid crystal projector having high luminance can be realized by using such a liquid crystal display device.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view and a front view of a light source according to a first embodiment of the present invention from different directions.

FIG. 2 is a perspective view showing a configuration of the liquid crystal projector according to the first embodiment of the present invention.

FIG. 3 is a perspective view illustrating a configuration of a liquid crystal panel of the image display device according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a light incident direction and a light convergence on a liquid crystal of an image display device according to a second embodiment.

FIG. 5 is a schematic diagram showing an outline of a projector using a liquid crystal.

FIG. 6 is a configuration diagram illustrating an overall configuration of a liquid crystal projector.

FIG. 7 is a sectional view and a front view showing a light source of a conventional liquid crystal projector.

FIG. 8 is a perspective view showing a microlens array adjacent to a liquid crystal display panel according to a first conventional example.

FIG. 9 is an explanatory diagram for explaining a utilization efficiency of light incident on a conventional microphone lens array.

FIG. 10 is a configuration diagram showing an overall configuration of a liquid crystal projector according to a second conventional example.

FIG. 11 is an explanatory view showing a microlens array adjacent to a liquid crystal display panel according to a second conventional example and light transmission therethrough.

FIG. 12 is a diagram showing a light spot at a pixel aperture due to light distribution of a light source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal projector 2 Metal halide lamp 3 Reflector 4,5 Polarizing plate 7 Projection lens 8 Screen 11,32,48 Micro lens array 12,29 Lens 21,33,40 Liquid crystal display panel 22,42 TFT 23,43 Black matrix 24,47 Transparent electrode 25, 26, 41, 45 Glass substrate 27, 46 Liquid crystal material 28, 34R, 34G, 34B Pixel aperture 31R, 31G, 31B Dichroic mirror

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09F 9/00 360 G09F 9/00 360N H04N 9/31 H04N 9/31 C

Claims (5)

[Claims] 1. A linear light source having a predetermined length, collimating means for collimating the light source to convert the light into parallel light, a spatial modulation element in which a plurality of pixels having a pixel opening long in one direction are arranged, and the collimator A microlens array comprising a microlens for condensing light on each pixel aperture of the spatial light modulator, wherein an optical axis of light emitted from the collimator and a longitudinal direction of the light source are perpendicular to each other; An image display device, wherein a longitudinal direction of the image display device is arranged so as to correspond to a longitudinal direction of a pixel opening of the spatial light modulator. 2. The image display device according to claim 1, wherein the microlens array is formed by a set of rectangular microlenses corresponding to a longitudinal direction of a pixel opening of the spatial light modulator. 3. A linear light source having a predetermined length, collimating means for collimating the light source to convert the light into parallel light, and separating the collimated light into three primary colors and emitting light at different angles according to the colors. And a light demultiplexing element that splits the light into collimated light.
A light output from the optical demultiplexing element, comprising: a spatial modulation element having a lattice-shaped pixel opening arranged for each of three colors; and microlenses respectively corresponding to the three color pixels of the pixel opening of the spatial modulation element. And a microlens array in which the distance between the microlens and the pixel opening is set so as to pass through the pixel opening of the corresponding color according to the exit angle while condensing the light by the microlens. An image display device, wherein the optical axis of the light emitted from the means is perpendicular to the longitudinal direction of the light source, and the longitudinal direction of the light source is arranged so as to correspond to the longitudinal opening of the spatial light modulator. 4. A light source comprising: a linear light source having a predetermined length; and collimating means for collimating the light source to form parallel light, wherein an optical axis of light emitted by the collimating means and a longitudinal direction of the light source are defined. A light source device characterized by being arranged vertically. 5. A liquid crystal projector, comprising: a projection lens arranged on the emission side of the image display device according to claim 1, for projecting transmitted light on a screen.