JP2000131762A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a projection type display device to be specially applied to a single-plate color filterless type liquid crystal projector, to assemble it by simple assembling work and to make the whole shape thereof compact. SOLUTION: An illumination optical system is formed of the optical system condensing illumination light beams LR, LG and LB, forming the plural light source images of one illumination light beam (LR, LG and LB), superposing incident light beams forming the respective light source images and illuminating a liquid crystal display panel. By the illumination optical system, the plural light beams LR, LG and LB are spatially separated and made incident.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display apparatus, and more particularly, to a single-panel color filterless liquid crystal projector. According to the present invention, an illumination optical system is formed by condensing illumination light to form a plurality of light source images of one illumination light, and superimposing incident light forming each light source image to illuminate a liquid crystal display panel. In this illumination optical system, a plurality of illumination lights can be spatially separated and incident, so that they can be assembled by a simple assembly work.
In addition, the overall shape can be reduced in size.

[0002]

2. Description of the Related Art Conventionally, in a projector as an image display device, light transmitted or reflected by a spatial modulation element is projected on a screen or the like to project and display an image by the spatial modulation element. I have. This type of projector is considered to be suitable for displaying a large screen as compared with a normal display device using a cathode ray tube, a direct-view type liquid crystal display, and the like, because a display image with a desired magnification can be formed. .

Some of such projectors use a liquid crystal display panel as a spatial modulation element.
A projector using such a liquid crystal display panel employs a method of forming a color image using three liquid crystal display panels (a three-panel liquid crystal projector) and a method of using one liquid crystal display panel. (A single-panel liquid crystal projector).

Among them, the three-panel type liquid crystal projector is
The illumination light emitted from the white light source is separated into red, blue, and green wavelength bands, and the illumination light of each of these wavelength bands is supplied to a liquid crystal display panel driven by red, blue, and green color signals, respectively. The transmitted light or the reflected light of each liquid crystal display panel is projected onto the screen in a superimposed manner.

On the other hand, in a single-panel type liquid crystal projector, a liquid crystal display panel is formed by sequentially arranging liquid crystal cells operated by red, blue, and green color signals sequentially, and each liquid crystal of the liquid crystal display panel is formed. In addition to selectively supplying red, blue, and green illumination light corresponding to the cells, the transmitted light or the reflected light of each liquid crystal cell is projected onto a screen.

In such a single-panel type liquid crystal projector, the overall shape can be simplified and the overall shape can be further reduced as compared with a three-panel type liquid crystal projector.

In such a single-panel type liquid crystal projector, a color filter corresponding to each liquid crystal cell is arranged as means for selectively supplying red, blue, and green illumination light corresponding to each liquid crystal cell. And those in which white illumination light is separated into red, blue, and green wavelength illumination light and selectively incident on a corresponding liquid crystal cell (Japanese Patent Application Laid-Open No. 4-60538).

In the latter liquid crystal projector (hereinafter referred to as a single-panel color filterless type liquid crystal projector), the loss due to the color filter can be avoided.
The use efficiency of illumination light can be improved as compared with the former liquid crystal projector.

FIG. 9 is a schematic diagram showing this single-panel color filterless type liquid crystal projector. In the liquid crystal projector 1, a light source 2 is formed by surrounding a discharge lamp 3 such as a metal halide lamp or a xenon lamp with a reflector 4, and emits white illumination light.
The convex lens 5 condenses the illumination light emitted from the light source 2 and enters the end face of the transparent rod 6. The transparent rod 6
A type of light integrator that equalizes the distribution of the quantity of incident light. The illumination light that enters from one end face propagates through the interior while being totally reflected by the side face, and exits from the other end face, resulting in a light quantity distribution of the illumination light. Uniform. Convex lens 7
Converges and emits the illumination light emitted from the other end face of the transparent rod 6.

The color separation mirrors 8B, 8G, and 8R are dichroic mirrors, and are sequentially arranged on the optical path of the illumination light emitted from the convex lens 7 with different inclinations. Here, the color separation mirrors 8B, 8G, and 8R selectively reflect illumination light in a predetermined wavelength band, respectively.
The illumination light of the remaining wavelength band is selectively transmitted. As a result, the color separation mirrors 8B, 8G, and 8R separate the white illumination light into the blue wavelength band, the green wavelength band, and the red wavelength band, and emit the light in substantially the same direction. In the illumination light in the green wavelength band and the red wavelength band, the illumination light is emitted such that the emission directions differ by a predetermined angle.

The liquid crystal display panel 9 is a liquid crystal display panel applied to a single-plate color filterless system, and operates in response to red, blue, and green color signals in the horizontal direction on the paper as shown in FIG. The liquid crystal cells R, B, and G that emit transmitted light obtained by intensity-modulating incident light are sequentially and cyclically arranged. The microlens 10 as a light beam separating means is an aggregate of microlenses, and one microlens is arranged for one set of red, blue and green liquid crystal cells in the liquid crystal display panel 9. Thus, the microlens 10 selectively emits blue, green, and red illumination light emitted from the color separation mirrors 8B, 8G, and 8R from different directions to the corresponding liquid crystal cells. In FIG. 10, the description of the polarizing filter is omitted.

The lenses 11 and 12 project the transmitted light of the liquid crystal display panel 9 onto a screen. Thereby, in the single-panel color filterless liquid crystal projector 1, each liquid crystal cell of the liquid crystal display panel 9 can be driven by a corresponding color signal to project a desired image on a screen.

In such a single-panel color filterless liquid crystal projector, the color separation mirrors 8B and 8B are used.
Configuration using dispersive elements instead of G and 8R
73517), a configuration using a hologram element (Japanese Unexamined Patent Application Publication No.
146066) has also been proposed.

FIG. 11 is a schematic diagram showing a liquid crystal projector in which multi-lens arrays 22 and 23 are used in place of the transparent rod 6 to make the light quantity distribution of illumination light uniform.

Here, the multi-lens arrays 22 and 23
In FIG. 12, micro lenses are arranged in an array as shown in a plan view and a side view. In the configuration shown in FIG. 12, this arrangement is uniformly repeated two-dimensionally. is there. In the liquid crystal projector 21, for example, multi-lens arrays 22 and 23 having the same shape are arranged separately on the optical path. At this time, the multi-lens array 22
And 23 are substantially equal to the focal length of the minute lenses constituting the multi-lens array 22 on the light source 2 side.
The illumination light of substantially parallel rays is incident on the multi-lens array 22 on the light source 2 side.

In the liquid crystal projector 21, a pair of convex lenses 24 and 25 are arranged on the optical path on the multi-lens array 23 side. Accordingly, in the liquid crystal projector 21, the optical image of the light source 2 is formed near each multi-lens array 23 by each of the micro lenses of the multi-lens array 22, and the illumination light emitted from the optical image of each of the micro lenses is displayed on the liquid crystal display. The liquid crystal display panel 9 is uniformly illuminated by being superposed on the panel 9.

[0017]

By the way, such single-panel color filterless liquid crystal projectors 1, 21 are used.
, It is necessary to arrange the color separation mirrors 8B, 8G, 8R and the like with high accuracy. That is, if the accuracy is poor, it becomes difficult to correctly enter only the illumination light corresponding to the liquid crystal cell, and the color purity on the display screen is reduced. As a result, in the liquid crystal projectors 1 and 21 of this type, there is a problem that the assembling work is complicated and requires time.

Further, due to the characteristics of the color separation mirrors 8B, 8G, and 8R, the arrangement positions of the color separation mirrors 8B, 8G, and 8R are limited.

FIG. 13 and FIG. 14 are characteristic curves showing the reflectance of the color separation mirror that selectively reflects the long wavelength side band and the short wavelength side band, respectively. As shown in FIGS. 13 and 14 based on the incident angle θ = 45 degrees, the half-value wavelength of the transmittance and the reflectance of the color separation mirror changes depending on the incident angle.

On the other hand, as shown in FIGS. 15 and 16, in a non-telecentric optical system in which the principal ray is not parallel to the optical axis of the optical system, the incident angle of the illumination light differs in each part of the color separation mirror. Become.

That is, in FIG. 15, in a state where the principal ray is inclined by an angle θ with respect to the optical axis of the optical system, the illumination light is transmitted through the color separation mirror, and then enters the upper portion of the liquid crystal display panel via the convex lens. Is the case. FIG. 16 shows a case in which the illumination light passes through the color separation mirror and then enters the lower part of the liquid crystal display panel via the convex lens in a state where the principal ray is inclined by the angle θ with respect to the optical axis of the optical system. . Here, each liquid crystal display panel has an angle φ with respect to the principal ray.
The case where the illumination light is incident due to the spread of the light is shown. As a result, when the color separation mirror is arranged in the non-telecentric optical system, the wavelength band of the illumination light reflected by each part is slightly different, and this difference in the wavelength band is observed as color unevenness on the screen. Become.

In order to prevent color unevenness, in this type of liquid crystal projector, as shown in FIG. 17, a color separation mirror must be arranged in a telecentric optical system in which the principal ray is parallel to the optical axis. However, there is a problem that the overall configuration becomes large accordingly.

The present invention has been made in view of the above points, and is a single-panel color filter-less type liquid crystal projector that can be assembled by a simple assembling operation and that can reduce the overall shape. It is intended to propose a type display device.

[0024]

According to the present invention, there is provided an illumination optical system which collects illumination light to form a plurality of light source images of one illumination light, and forms each light source image. By illuminating the liquid crystal display panel with superimposed incident light, the illumination light is guided to the liquid crystal display panel. At this time, a plurality of illumination lights are spatially separated and incident.

The illumination light is condensed to form a plurality of light source images of one illumination light, and the incident light forming each light source image is superimposed to illuminate the liquid crystal display panel, thereby guiding the illumination light to the liquid crystal panel. In this case, if a plurality of illumination lights are spatially separated and incident at this time, each illumination light will enter each liquid crystal cell of the liquid crystal display panel with a different inclination. This allows the illumination light to enter each liquid crystal cell at a predetermined inclination without using the color separation mirror, and allows the illumination light corresponding to the liquid crystal cell to enter, thereby eliminating the use of the color separation mirror. Thus, the assembling work can be simplified and the overall shape can be reduced in size.

[0026]

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

(1) Configuration of Embodiment FIG. 1 is a schematic diagram showing a liquid crystal projector according to an embodiment of the present invention. In this liquid crystal projector 41, the same components as those of the liquid crystal projector 21 described above with reference to FIG. 11 are denoted by the corresponding reference numerals, and duplicate description will be omitted.

In the liquid crystal projector 41, the light sources 42R, 42G, and 42B are constituted by laser light sources, respectively, in a direction corresponding to the repetition direction of the liquid crystal cell for red, green, and blue in the liquid crystal projector 41. Arranged in the red wavelength band,
A laser beam of a predetermined wavelength in a green wavelength band and a blue wavelength band is emitted as illumination light for red, green, and blue.

The concave lenses 43R, 43G and 43B emit laser beams LR, LG and LB emitted from the respective light sources 42R, 42G and 42B by divergent light, and the subsequent convex lenses 44R, 44G and 44B emit laser beams by the divergent light. The beam is incident on the multi-lens array 22 by the parallel light of LR, LG and LB. Thereby, each concave lens 43R, 43G, 43B and the corresponding convex lens 44
R, 44G, and 44B constitute a magnifying lens system that enlarges and emits a laser beam, respectively.

Thus, each of the illumination light LR, LG, LB
As shown in FIG. 2, the concave lens 43R, 43G, 43B and the convex lens 44
R, 44G, and 44B are regions ARLR, ARLG formed on the incident surface and the outgoing surface of the multi-lens array 22 by dividing the incident surface and the outgoing surface into three corresponding to the arrangement of the light sources 42R, 42G, and 42B. , ARLB, respectively, so that the corresponding illumination light LR, LG, LB is incident thereon, and no other illumination light is incident on other adjacent regions. In the liquid crystal projector 41, a light shielding plate or the like is appropriately disposed between the light beams of the illumination lights LR, LG, and LB for this purpose.

Thus, in the liquid crystal projector 41, the illumination lights LR, LG, LB of the red, green, and blue wavelength bands are spatially separated according to the arrangement of the liquid crystal cells in the liquid crystal display panel 9. Is incident on the multi-lens array 22 on the light source 2 side, and the illumination light by the optical image formed by each minute lens of the multi-lens array 22 is superimposed on the liquid crystal display panel 9.

(2) Operation of Embodiment In the above configuration, in the liquid crystal projector 41 (FIG. 1), illumination light LR, LG, LB by a laser beam is emitted from the light sources 42R, 42G, 42B, and each concave lens 43R , 43G, 43B and the corresponding convex lens 44
The beam diameters of these illumination lights LR, LG, LB are enlarged by a magnifying lens system composed of R, 44G, 44B and converted into substantially parallel rays.

Further, in the liquid crystal projector 41,
The illumination light LR, LG, and LB are spatially separated and are incident on the multi-lens array 22 according to the arrangement corresponding to the arrangement of the liquid crystal panels in the liquid crystal display panel 9 (FIG. 2). Illumination light LR, LG, L incident on each minute lens by the minute lens
The light source image of B is formed near the multi-lens array 23 that follows.

In the liquid crystal projector 41, the illuminating lights LR and L forming the respective light source images formed in this manner.
G and LB are followed by the multi-lens array 23 and the convex lens 2
The illumination light LR, LG, and LB that are guided to the liquid crystal display panel 9 by 4 and 25 and form each light source image overlap each other and enter the liquid crystal display panel 9.

At this time, each of the illumination lights LR, LG, LB is spatially separated, and after being incident on the multi-lens array 22 in an arrangement corresponding to the arrangement of the liquid crystal panels in the liquid crystal display panel 9, the subsequent multi-lens By being guided to the liquid crystal display panel 9 by the array 23 and the convex lenses 24 and 25, the liquid crystal display panel 9 comes from directions corresponding to the arrangement of the liquid crystal cells.

That is, as shown in FIGS. 3, 4 and 5, the light path of the illumination light incident on each part of the microlenses constituting the multi-lens array 22 is shown in FIG.
In the case where the illumination lights LR, LG, and LB are spatially separated by the arrangement corresponding to the arrangement of the liquid crystal panels and are incident on the multi-lens array 22, the illumination lights LR and LG incident on the liquid crystal display panel 9 , LB can be controlled. Here, FIG. 3 shows the optical path of the illuminating light incident on the center of each of the micro lenses constituting the multi-lens array 22, and FIGS. 4 and 5 similarly show the light paths on the lower and upper portions of each of the micro lenses. The optical path of the illumination light is shown.

From these optical path diagrams, it can be seen that the illumination light emitted from each micro lens of the multi-lens array 22 has a larger incident angle to the liquid crystal display panel 9 as the height of each micro lens from the optical axis increases. I understand. Further, it can be seen that the illumination lights LR, LG, LB that are respectively incident from the upper part, the central part, and the lower part of the multi-lens array 22 are incident on the respective regions of the liquid crystal display panel 9 at different incident angles.

Thus, in the liquid crystal projector 41, the illumination light LR, LG, LB corresponding to each liquid crystal cell of the liquid crystal display panel 9 can be selectively incident by the microlenses 10 arranged on the front surface of the liquid crystal display panel 9. This makes it possible to form a display image by projecting the intensity-modulated light emitted from each liquid crystal cell onto the screen by the convex lenses 11 and 12 (see FIG. 11).

Thus, in the liquid crystal projector 41, the illumination light corresponding to each liquid crystal cell can be incident without using the color separation mirror (FIGS. 9 and 11). The complexity of the operation can be eliminated, and a high-quality display image can be formed even when the assembly accuracy is reduced. In addition, since the color separation mirror can be omitted, the overall configuration can be simplified and downsized.

In each of the illumination lights LR, LG, LB, the liquid crystal display panel 9 is uniformly illuminated by the original function of the multi-lens arrays 22, 23, whereby a high-quality display image can be formed. .

(3) Effects of the First Embodiment According to the above configuration, the light sources 42R, 42G,
Illumination light LR, L by the laser beam generated in 2B
G and LB are spatially separated and incident on the multi-lens array 22 in an arrangement corresponding to the arrangement of the liquid crystal panels in the liquid crystal display panel 9, so that each wavelength band can be used without using a color separation mirror. Illumination light LR, LG, LB
Are emitted toward the liquid crystal display panel 9 at different angles, and illumination light corresponding to each liquid crystal cell of the liquid crystal display panel 9 can be selectively incident. Therefore, since the color separation mirror does not need to be used, the overall shape can be reduced in size and simplified, the mounting accuracy can be reduced, and the assembling work can be simplified accordingly.

(4) Other Embodiments In the above-described embodiments, each of the light sources 42
Illumination light L by laser beam at R, 42G, 42B
Although the case where R, LG, and LB are generated has been described, the present invention is not limited to this, and as shown in FIG. 6 in comparison with FIGS. The splitting mirrors 52B, 52G, and 52R separate the illumination lights LR, LG, and LB in the blue, green, and red wavelength bands, and spatially separate the illumination lights LR, LG, and LB to separate the multi-lens array 22. May be incident.

In the above-described embodiment, the multi-lens array 2 in which the micro lenses are uniformly arranged two-dimensionally.
Although the case where the liquid crystal projector is configured using 2 and 23 has been described, the present invention is not limited to this, and as shown in FIG. 7 in comparison with FIG. 1, each illumination light LR, LG, LB
May be formed at the boundary of the area where no microlenses are arranged. In this way, as shown in FIG. 8, when the illumination light LR, LB, and LG incident on one micro lens constituting the micro lens 10 are viewed, the illumination light LR incident on one micro lens, The luminous fluxes of LB and LG can be separated by a predetermined angular interval α. As a result, the corresponding illumination light can be surely selectively incident on the liquid crystal cell, and accordingly, the color purity of the displayed image can be improved and the quality can be improved.

In this case, the multi-lens array 22 on the light source side and the remaining multi-lens array 23 may be separated for each illumination light.

In the above-described embodiment, the case where the light sources 42R, 42G, and 42B are constituted by the laser light sources has been described. However, the present invention is not limited to this. Can be widely applied.

Further, in the above-described embodiment, the respective illumination lights are one-dimensionally arranged corresponding to the arrangement of the liquid crystal cells in the liquid crystal display panel, and spatially separated to enter the multi-lens array 22. I mentioned the case,
The present invention is not limited to this, and each illumination light may be two-dimensionally arranged in correspondence with the liquid crystal display panel, and may be spatially separated and incident on the multi-lens array 22.

In the above embodiment, the case where a pair of multi-lens arrays is used has been described.
The present invention is not limited to this. For example, when a multi-lens array having a configuration in which the pair of multi-lens arrays is integrated is used, the point is to collect the incident light and form a plurality of light source images of the incident light. Also, it is widely applied to a case where an illumination optical system which is an optical system on a light source side is formed so that an incident light forming each light source image is superimposed to illuminate a liquid crystal display panel. The same effect as in the above-described embodiment can be obtained by illuminating light being spatially separated and incident.

[0048]

As described above, according to the present invention, a liquid crystal display panel is formed by condensing illumination light to form a plurality of light source images of one illumination light, and superimposing incident light forming each light source image. An illumination optical system is formed by the optical system to be illuminated. In this illumination optical system, a plurality of illumination lights are spatially separated and incident, so that they can be assembled by a simple assembling work, and the overall shape is reduced in size. can do.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a liquid crystal projector according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a relationship between a multi-lens array and illumination light.

FIG. 3 is a schematic diagram illustrating an optical path of illumination light incident on the center of each minute lens of the multi-lens array.

FIG. 4 is a schematic diagram illustrating an optical path of illumination light incident on a lower portion of each micro lens of the multi-lens array.

FIG. 5 is a schematic diagram showing an optical path of illumination light incident on each microlens of the multi-lens array.

FIG. 6 is a schematic diagram illustrating a liquid crystal projector according to another embodiment using a white light source.

FIG. 7 is a schematic diagram illustrating a liquid crystal projector according to another embodiment in which a multi-lens array is separated.

8 is a schematic diagram showing an optical path of illumination light for one liquid crystal cell in the liquid crystal projector of FIG.

FIG. 9 is a schematic diagram illustrating a conventional liquid crystal projector.

FIG. 10 is a cross-sectional view illustrating a relationship between a microlens and a liquid crystal display panel.

FIG. 11 is a schematic diagram illustrating a conventional liquid crystal projector using a multi-lens array.

FIG. 12 is a plan view and a side view showing a multi-lens array.

FIG. 13 is a characteristic curve diagram showing characteristics of a dichroic mirror that reflects light on a long wavelength side.

FIG. 14 is a characteristic curve diagram showing characteristics of a dichroic mirror that reflects light on the short wavelength side.

FIG. 15 is a schematic diagram illustrating an optical path of illumination light incident on an upper portion of a liquid crystal display panel in a non-telecentric optical system.

FIG. 16 is a schematic diagram illustrating an optical path of illumination light incident on a lower portion of a liquid crystal display panel in a non-telecentric optical system.

FIG. 17 is a schematic diagram illustrating an optical path of illumination light incident on a liquid crystal display panel in a telecentric optical system.

[Explanation of symbols]

1, 21, 41, 51, 61 ... a liquid crystal projector,
2, 42B, 42G, 42R: light source, 9: liquid crystal display panel, 10: micro lens, 22, 23: multi-lens array

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 EA13 EA15 EA19 FA16 FA18 HA22 HA25 HA28 MA05 MA16 5C060 AA02 BA04 BC01 DA01 GA02 GB01 GB05 GB10 HC01 JB06 5G435 AA17 AA18 BB12 BB17 CC12 DD02 DD04 GG01 GG27 GG09 GG26

Claims (5)

[Claims] 1. A light source for emitting a plurality of illumination lights having different wavelength bands, and liquid crystal cells corresponding to the plurality of illumination lights are sequentially arranged in a circulating manner, and the amount of incident light is controlled and emitted in each liquid crystal cell. A liquid crystal display panel, and an illumination optical system that guides the plurality of illumination lights to corresponding liquid crystal cells by making incident angles of the plurality of illumination lights on the liquid crystal display panel different, and the illumination optical system includes: The illumination light is condensed to form a plurality of light source images of the one illumination light, and the liquid crystal display panel is illuminated by superimposing incident light forming each of the light source images, thereby converting the illumination light to the liquid crystal. A projection display device, comprising: an optical system for leading to a display panel; wherein the plurality of illumination lights are spatially separated and incident on the optical system. 2. The projection display device according to claim 1, wherein the light source emits three illumination lights in a wavelength band corresponding to three primary colors of light. 3. The projection display device according to claim 1, wherein the light sources are three laser light sources that emit laser beams in wavelength bands corresponding to three primary colors of light. 4. The projection display device according to claim 1, wherein the light source generates the plurality of illumination lights from white light by a color separation unit. 5. A light source for emitting light in a wavelength band corresponding to three primary colors of light.
The projection display device according to claim 1, wherein the projection type display device includes one light emitting diode.