JP2001183641A - Reflective display panel and projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display technology capable of providing excellent reflectance and suppressing photoconductivity even when light with high illuminance is made incident. SOLUTION: A micro lens array is arranged on an incident light side substrate of a reflective display panel. The incident light is condensed on a pixel reflection plane through the micro lens array. The light is not made incident between respective pixel reflection planes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection-type panel having a good use efficiency of a light emitted from a lamp, a high transmittance, and a high light resistance, and a display device using the same.

[0002]

2. Description of the Related Art As a prior art of a display panel aiming at improvement of light utilization efficiency of light emitted from a lamp and improvement of light resistance, there is, for example, a technique described in JP-A-11-109305.

According to the technique described in this publication, a liquid crystal display panel is of a reflection type, and a polymer liquid crystal,
A polarizing layer made of a dichroic dye is provided, and light transmitted through the polarizing layer is incident on the light reflecting layer.

In this prior art, the display panel is a reflection type liquid crystal display panel, so that the aperture ratio (the ratio of the light reflection area to the total display area in the reflection type liquid crystal display panel) is higher than that of the transmission type liquid crystal display panel. Can be increased, and the utilization efficiency of the light emitted from the lamp can be improved. By providing a polarizing layer inside the panel, it is also possible to prevent double reflection and overlapping of reflected light with reflected light from adjacent pixels. Further, the switching transistors for driving the pixels are arranged behind the reflection layer and the wiring portion of each pixel, and it is considered that light entering between the pixels does not directly irradiate the transistors.

[0005]

However, the configuration described in the above-mentioned prior art, Japanese Patent Application Laid-Open No. H11-109305, has the following problems. That is, there is a narrow gap between the reflective layers of the reflective liquid crystal display panel, but a certain gap, and the light incident thereon becomes useless light that is not used for image display. In addition, light incident from the gap is reflected on each wiring, each electrode, and the like in many cases, and becomes stray light. When the stray light enters a channel portion of a transistor that drives a pixel,
The transistor causes a photo leak, and as a result, the display panel does not display a correct image. Also, the stray light causes the temperature of the display panel to rise.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display technique which solves the above-mentioned problems and eliminates light between the reflective layers of the display panel, thereby improving light use efficiency and increasing luminance.
It is another object of the present invention to provide a display technology capable of reducing stray light entering each reflective layer and preventing a pixel drive transistor from malfunctioning due to a photo capacitor, and capable of providing a high-brightness and high-quality image.

[0007]

According to the present invention, there is provided a reflective display panel having a liquid crystal layer disposed between a pixel electrode forming substrate and a common electrode forming substrate.
A microlens array having a positive power is arranged on the surface of the common electrode forming substrate or inside the substrate. With this configuration, the irradiation light from the lamp that has entered the common electrode forming substrate is condensed on each light reflection surface formed on the pixel electrode substrate by the microlens array provided on the substrate. The light condensed on the reflection surface is reflected on the reflection surface, passes through the microlens of the common electrode substrate again, enters a projection lens or the like, and becomes image projection light. Thereby, the irradiation light from the lamp does not enter between the reflection surfaces forming each pixel, so that the efficiency of use of the lamp irradiation light can be improved and the occurrence of photo-cons in the pixel transistor can be prevented. Further, the temperature rise of the display panel can be reduced.

In the case where the display panel is not a liquid crystal display panel, but is a reflection type display panel having a structure in which a transparent substrate is arranged to face a micromirror array surface of a micromirror array substrate, incident light of the display panel is incident on the transparent substrate. The light is focused on each micromirror surface of the micromirror array substrate by the microlens array formed on the substrate surface. The light condensed on the mirror surface is reflected by the mirror surface, passes through the microlens on the transparent substrate again, enters a projection lens or the like, and becomes image projection light. Thereby, the irradiation light from the lamp does not enter between the mirror surfaces forming each pixel, and it is possible to improve the use efficiency of the lamp irradiation light and to prevent the occurrence of photo-cons in the pixel transistor. The temperature rise of the display panel can be reduced.

[0009]

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

FIG. 1 is a schematic sectional view of a first embodiment of a reflective display panel according to the present invention. In FIG. 1, 1 is a pixel electrode substrate, and 2 is a common electrode substrate. A pixel electrode driving transistor 4 is formed on the inner surface of the pixel electrode substrate 1, and a reflective pixel electrode 5 is formed above the transistor 4 via an insulating material 8 or the like. The reflective pixel electrode 5 and the transistor 4 are connected by a wiring section 6 or the like. An alignment film 7 is formed on the surface of the reflective pixel electrode 5. On the other hand, the common electrode substrate 2 is configured by a composite substrate of a transparent base substrate 10 and a microlens array substrate 11. In addition, an alignment film or the like 1 is provided on the inner surface of the transparent base substrate 10.
2 are formed.

A liquid crystal layer 3 is provided between the pixel electrode substrate 1 and the common electrode substrate 2. Light incident on a reflective display panel (reflective liquid crystal display panel) having such a configuration
1 and 13-2 are condensed by the microlenses 11-1 and 11-2 near the central portion 15 of the light reflecting surface of the reflective pixel electrode 5, then reflected at the central portion 15 and again reflected by the microlenses. The light enters the lenses 11-1 and 11-2 and becomes the outgoing lights 14-1 and 14-2 of the liquid crystal display panel. As described above, the incident light 13 on the reflective display panel according to the first embodiment of the present invention.
Since -1 and 13-2 are almost incident on the vicinity 15 of the central part of the light reflecting surface of the pixel electrode 5, there is no incident light between the reflecting surfaces 9. Therefore, the incident lights 13-1 and 13-2 can be efficiently reflected light, and when the display panel of this configuration is applied to a projector or the like, the projection screen can be a high-brightness projection screen.

Further, since there is almost no light incident between the reflection surfaces 9, generation of stray light on the back surface of the reflection type pixel electrode 5 and near the pixel electrode driving transistor 4 can be suppressed. There is no invading light incident on 4. Therefore, even when high illuminance light is incident on the liquid crystal display panel of the present invention, the pixel transistor 4 does not generate a photo capacitor, and a high quality image can always be displayed. In addition, since there is no incident light or intrusion light between the reflection surfaces 9,
An effect of suppressing a rise in temperature in the vicinity of the pixel electrode 5 is also produced, and also a rise in temperature of the reflective liquid crystal display panel is reduced.

FIG. 2 is a diagram schematically showing the display panel and parts near the display panel when the first embodiment of the reflection type display panel according to the present invention is applied to a liquid crystal projector.

The display panel is a liquid crystal display panel, and a polarizing beam splitter 1 is provided on the light input / output side of the liquid crystal display panel.
The configuration is such that a 6, 1/2 wavelength plate 18 is arranged. In such a configuration, after the non-polarized light 20 emitted from a lamp (not shown) is incident on the beam splitter 16 and the S-polarized light 21 is removed on the back surface 17 for the polarized light, only the P-wave polarized light 1 / The P-polarized light enters the two-wavelength plate 18 and, when transmitted through the wavelength plate 18, changes the oscillation direction by 90 degrees and then enters the liquid crystal display panel. The polarized light 23 incident on the liquid crystal display panel undergoes modulation corresponding to a video signal, and becomes light 24 emitted from the liquid crystal display panel. The light 24 emitted from the liquid crystal display panel is incident on the polarization beam splitter 16 after the vibration direction is changed by 90 degrees by the half-wave plate 18,
At 7, the S-wave polarization is emitted in the direction of the screen (not shown) and becomes image light 25. The P-polarized light 26 transmitted straight through the polarized light back surface 17 is usually a lamp (not shown).
There is also a configuration in which the light goes to the direction and becomes unused, but is reflected near the lamp and then re-entered into the polarizing beam splitter for reuse.

In this configuration, a half-wave plate 18 disposed between the liquid crystal display panel and the polarizing beam splitter 16 is provided.
Has the function of cutting unnecessary light such as surface reflection of the light incident surface of the liquid crystal display panel and reflection at the interface between the microlens array substrate 11 and the transparent base substrate 10, and is useful for improving the contrast of the projected image. When there is no problem of the generation of the unnecessary light, the wave plate 18 may not be used.

With such an optical system configuration, the light incident on the liquid crystal display panel is efficiently converted into image light by the liquid crystal display panel or the like, and the liquid crystal display panel does not generate a photo-con. With a display device to which the display panel is applied, high-brightness and high-quality images can be obtained.

FIG. 3 is a sectional view of a reflective display panel according to a second embodiment of the present invention. The main difference between the second embodiment and the first embodiment is that the power of each microlens 33-1 and 33-2 of the microlens array substrate 33 is weaker than in the first embodiment. Another difference is that the thickness of the liquid crystal layer 3 is reduced. Accordingly, for example, the peripheral incident lights 36-1 and 36-2 of the microlens 33-1 are not condensed at the center 15 of each reflection surface, but are condensed at points 15-1 and 15-2 slightly away from the center 15. I do. Micro lens 3
When the powers of 3-1 and 33-2 are weakened, the incident angles of the incident light beams 37-1 and 37-2 on the liquid crystal layer 3 are perpendicular to the incident angles on the liquid crystal layer 3 in the first embodiment. Since the angles are close to each other, it is effective in maintaining the contrast display characteristics of the reflective liquid crystal display panel.

FIG. 4 is a schematic sectional view of a third embodiment of the reflective display panel according to the present invention.

The difference between the third embodiment and the first embodiment is that the power of each of the microlenses 35-1 and 35-2 of the microlens array substrate 35 is stronger than that of the first embodiment. Or the thickness of the liquid crystal layer 3 is increased. Thereby, for example, the micro lens 35-1
Are not condensed at the center 15 of each reflecting surface, and points 15-3, 15
Focus on -4. In addition, the peripheral incident lights 38-1 and 38-
In some cases, the outgoing lights 39-1 and 39-2 corresponding to No. 2 may pass through a microlens 35-2 adjacent to the microlens 35-1. In this case, the outgoing lights 39-1 and 39-2
2 does not become effective light for forming an image. However, the incident light other than the peripheral part of the micro lens 35-1 is 3
9-3 is condensed in the vicinity of the reflecting surface 15, and the reflected light exits through the incident microlens 35-1 and is used for image formation. As described above, in the configuration of the third embodiment,
Although there is no effect from the viewpoint of improving the light use efficiency, it is effective in preventing the occurrence of photo-cons in the liquid crystal display panel because it is possible to prevent the intrusion of the incident light between the reflection surfaces 9.

FIG. 5 is a schematic sectional view of a fourth embodiment of the reflective display panel according to the present invention. The first embodiment shown in FIG. 1, the second embodiment shown in FIG. 3, and the third embodiment shown in FIG.
The reflective display panel of each embodiment is a liquid crystal panel, but the reflective display panel of the fourth embodiment is a panel using a micromirror, and displays the surface angle of the micromirror corresponding to each pixel. This is a display panel compatible with an optical system configuration of a system in which the reflected light when the surface angle of the mirror is a predetermined angle is taken in as image light by changing in response to a signal.

The structure of the reflection type display panel shown in FIG. 5 includes a micromirror array substrate 40 on which micromirrors 41, 42, 43, 44, etc. corresponding to respective pixels are arranged, a transparent base substrate 30, and a microlens array substrate. This is a configuration in which a counter substrate 60 composed of a composite substrate 50 and a counter substrate 50 is arranged to face each other at a constant interval.

Light emitted from the lamp 61 is incident on the opposite substrate 60 of the reflective display panel. Light incident on the opposing substrate 60, for example, the incident light 70-1, 70-2, 70-3
Is incident on the microlens 52 formed on the counter substrate 60, is condensed by the microlens 52, and is condensed almost at the center of the surface of the micromirror 42. Each of the micromirrors 41, 42, 43, 44, etc. performs an operation of changing the surface angle with respect to the reference plane 45 according to each pixel drive signal, and the micromirror 42 operates according to the pixel drive signal. , The setting of −α degrees with respect to the reference plane 45,
Then, the light condensed on the mirror is emitted in the direction of 2α degrees with respect to the optical axis of the incident light. The light traveling in that direction is applied to the microlens 5 disposed adjacent to the microlens 52.
The light exits from the opposite substrate through 1. Optical axis of incident light and angle 2
A projection lens 62 is arranged in the direction of α, and the emitted light is taken in by the projection lens 62 and projected on a screen. However, in the above configuration, the distance L between each microlens center and the distance D between each microlens and each corresponding micromirror are the refractive index of the transparent base substrate,
Although it is necessary to make corrections in consideration of the refractive index of the microlens array substrate, the refractive index of other panel constituent materials, and the like, it is basically necessary to satisfy the relationship of L = Dtan (2α).

The other incident light on the opposite substrate 60, for example, the incident light 70-4, 70-5, 70-6 enters the micro lens 53 formed on the opposite substrate 60 and is condensed by the micro lens 53. Under the action, the light is condensed almost at the center of the surface of the micro mirror 43. Here, as a result of the micro mirror 43 operating in response to the pixel drive signal, the micro mirror 43 becomes α degrees with respect to the reference plane 45, and the light condensed on the mirror 43 becomes −2α degrees with respect to the incident optical axis. Emit in the direction. The light that has traveled in that direction exits the counter substrate 60 through the microlens 54 disposed adjacent to the microlens 53, and does not basically reach the screen.

In the above display panel configuration, although there is a gap between the micromirrors, it is possible to prevent light from entering the gap. Therefore, it is possible to prevent a transistor that drives each micromirror from malfunctioning due to a photo capacitor. Also, since almost all the microlens transmitted light is collected on the micromirror surface,
Light use efficiency can be improved.

FIG. 6 is a diagram showing a main part of an optical system of a projection type display apparatus to which a fourth embodiment of a reflection type display panel according to the present invention is applied. Light emitted from the lamp 61 is transmitted through the infrared and ultraviolet cut filters 63, and almost only visible light is transmitted through the condenser lens 64 and then enters the reflective display panel 80. Micro mirrors 66-1, 66-2, 66-
The angles 3, 66-4, and 66-5 change according to the pixel drive signal, and as a result, the reflected light from the mirror becomes
The image advances in two directions, other directions, and the like, and an image is formed on the screen 65.

In the above description of the fourth embodiment, when light transmitted through a microlens and incident on a reflective display panel is reflected by a micromirror and emitted from the display panel, it is disposed adjacent to the microlens on which the light is incident. The case where the light is emitted through the microlens described above has been described. However, the present invention is not limited to such a case.
The light may be emitted from every other or every third microlens. At this time, the micro lens center distance L and the distance D between each micro lens and each corresponding micro mirror are basically 2L = D tan (2
α), 3L = Dtan (2α), and 4L = Dtan (2α). In the above description, the fly-eye type microlens corresponding to one pixel is described as a microlens array, but the microlens is not limited to this and may be a lenticular lens type microlens. . However, in the case of a lenticular lens type microlens, the pixel arrangement of the display panel may be lower than the fly-eye type in terms of light collection efficiency and prevention of unnecessary light from entering between pixels depending on the display panel to be applied. It is necessary to apply in consideration of such conditions.

[0027]

As described above, according to the present invention, in the case of a liquid crystal display panel, the light emitted from the lamp does not enter between the reflection surfaces forming the pixels, and the light emitted from the lamp is not emitted. This is effective for both improving the light use efficiency and preventing the occurrence of photo-cons in the pixel transistors. Further, it is effective in reducing the temperature rise of the display panel.

Also, in the case of a micromirror type display panel, the irradiation light from the lamp does not enter between the mirror surfaces forming each pixel, thereby improving the use efficiency of the lamp irradiation light and improving the efficiency of the pixel transistor. This is effective for both prevention of photocon generation. This configuration is also effective in reducing the temperature rise of the display panel.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a first embodiment of a reflective display panel of the present invention.

FIG. 2 is a diagram schematically showing the display panel and parts near the display panel when the first embodiment of the reflection type display panel of the present invention is applied to a liquid crystal projector.

FIG. 3 is a schematic sectional view of a second embodiment of the reflective display panel of the present invention.

FIG. 4 is a schematic sectional view of a reflective display panel according to a third embodiment of the present invention.

FIG. 5 is a schematic sectional view of a fourth embodiment of the reflective display panel of the present invention.

FIG. 6 is a schematic diagram of a main part of an optical system of a projection display device to which a fourth embodiment of the reflection display panel of the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pixel electrode substrate, 2, 32, 34 ... Common electrode substrate, 3 ... Liquid crystal layer, 4 ... Pixel electrode drive transistor, 5 ... Reflection type pixel electrode, 6 ... Wiring part etc. 7, 12 ... Alignment film etc. 8: insulating material, 9: between light reflecting surfaces, 10, 30: transparent base substrate, 11, 35, 50: microlens array substrate, 11-1, 11-2, 33-1, 33-2, 35-1 ,
35-2, 51, 52, 53, 54... Microlenses, 13-1, 13-2, 36-1, 36-2, 38-1,
38-2, 38-3: liquid crystal panel incident light, 14-1, 14-2: liquid crystal panel output light, 15: near the center of the light reflection surface, 15-1, 15-2, 15-3, 15-4 , 15-5 ...
Each part of the light reflecting surface, 16: polarized beam splitter, 17: polarized light back surface, 18: half-wave plate, 20: non-polarized irradiation light, 21, 25: S-polarized light, 22, 26: P-polarized light, 40 ... Micro mirror array substrate, 41, 42, 43, 44, 66-1, 66-2, 66-
3, 66-4, 66-5: micro mirror, 60: reflective display panel opposite substrate, 61: lamp, 62: projection lens, 63: infrared and ultraviolet cut filter, 64: condenser lens, 65: screen, 70-1, 70-2, 70-3, 70-4, 70-5,
70-6: Reflective display panel opposite substrate incident light, 80: Reflective display panel.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/00 360 G09F 9/00 360N 360D H04N 5/74 H04N 5/74 BF term (Reference) 2H088 EA13 HA15 HA20 HA25 HA26 HA28 KA30 MA20 2H091 FA01X FA10X FA11X FA14Y FA28X FA29X FA41X GA13 LA03 LA04 LA30 MA07 5C058 AA06 AA18 BA05 BA08 EA01 EA26 EA27 5G435 AA00 AA02 AA12 BB12 BB16 BB17 GG03 DD03 DD02

Claims (4)

[Claims] 1. A reflective display panel having a liquid crystal layer disposed between a pixel electrode forming substrate and a common electrode forming substrate, wherein a microlens array having a positive power is provided on the substrate surface of the common electrode forming substrate or inside the substrate. A reflective display panel, comprising: 2. A reflective display panel in which a transparent substrate is arranged to face a micromirror array surface of a micromirror array substrate, wherein a microlens array having a positive power is arranged on the substrate surface of the transparent substrate or inside the substrate. A reflective display panel characterized by the following. 3. The reflection type display panel according to claim 2, wherein a deflection angle of each micromirror with respect to a reference plane at the time of operation of the panel is ± α degrees, and a distance between the micromirror surface and the microlens is D. Let the microlens pitch be L, n
Is a positive integer, n · L is substantially equal to D · tan (2α). 4. A projection type display device comprising the reflection type display panel according to claim 1, 2 or 3, wherein a display image of the panel is enlarged and projected on a screen by a projection lens. .