JPH0618870A - Projection type display device - Google Patents

Abstract

PURPOSE:To provide the projection type display device for realizing high screen luminance on a screen, while avoiding such problems as durability of a light source and a display element and power consumption by suppressing intensity of an irradiation light. CONSTITUTION:A distance (d) between an opening part plane and a micro-lens plane satisfies a relation of (1/2) (Pp-Kp)/(tan(phimax)--2tan(thetamax))<=d<=Kp/tan(thetamax) with respect to picture element width (Pp), opening part width (Kp), an illumination light incident distribution angle (thetamax), and an emitting side optical system maximum fetching angle (phimax), by which an effective numerical aperture is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device which obtains an image by projecting an optical image formed on a display element onto a screen by irradiating illumination light, and more particularly to a display panel. The present invention relates to a projection display device that requires high brightness for a projected image despite its small size.

[0002]

2. Description of the Related Art In recent years, a projection type display device having excellent characteristics such as a large screen, light weight, small size and low cost has been attracting attention as an alternative to the direct view type display device. In particular, a projection display device using a transmissive liquid crystal display element, which has features such as low power consumption, low driving voltage, light weight, and small size, has been put to practical use in projector TVs, overhead projectors, etc., and its practical range is further expanded. It's starting.

However, in the projection type display device, since a high intensity irradiation light is required to realize high brightness on the screen, the durability of the light source is reduced and the power consumption is increased. The display element has various problems such as deterioration of characteristics due to heat and light. In particular, in a projection display device using a liquid crystal display element, the display element tends to be further downsized, and accordingly, irradiation light of higher intensity is required. Since there is a large temperature dependence and the driving means is sensitive to light irradiation due to the optical property effect, the heat generated by the irradiation light and the effect of the irradiation light itself on the image quality and its change over time become a serious problem. ing.

Therefore, as a means for improving the brightness on the screen without increasing the intensity of the irradiation light, a method of disposing a microlens, which is an optical means having a positive focal length, on the light incident side of the display element is devised. Was done. this is,
The loss light radiated to the light-shielding portion of the display element is focused on the pixel aperture portion and is effectively used. In other words, the actual aperture ratio (geometric aperture ratio) of the display element is In addition, the effective aperture ratio (effectively used illumination light / total illumination light) is improved.

However, in the conventional structure, since the transparent substrate having the microlenses formed on the surface thereof is disposed in close contact with the surface of the display element, the plane between the plane where the microlenses are present and the plane where the picture elements are present is located. The distance is defined by conditions such as the substrate thickness of the display element, which is determined by the constraint on the strength of the display panel, and is not the optimum design for improving the effective aperture ratio. For this reason, since the illumination light has a constant incident distribution angle (θmax) due to the requirement of increasing the incident light flux for the purpose of increasing the accuracy of the incident side optical system and the screen brightness, a considerable amount of light is also applied to the pixel light shielding part. Was still irradiated, and the effect of improving the effective aperture ratio was insufficient.

[0006]

As described above, in the conventional structure, the effect of improving the effective aperture ratio is not sufficiently obtained.
In order to achieve high screen brightness on the screen, strong illumination light is still required, and the durability of the light source is reduced as described above, power consumption is increased, and the characteristics of the display element due to heat and light are deteriorated. There are problems such as. Therefore, an object of the present invention is to provide means for realizing high screen brightness while avoiding problems in durability and power consumption by improving the effective aperture ratio.

[0007]

In order to achieve this object, the present invention has a plane in which a pixel opening in which illumination light is incident exists and a positive focal length arranged corresponding to the pixel. The pixel width (Pp) and aperture width (Kp) when the distance (d) between the planes where the optical means (microlens) exists is viewed from at least one direction, the illumination light incident distribution angle (θma)
x), and the maximum capture angle (φmax) of the output side optical system, (1/2) (Pp-Kp) / (tan (φmax) -2tan (θmax)) ≦ d ≦ (1/2) Kp /
It is set so as to satisfy the relationship of tan (θmax).

[0008]

By constructing the projection type display element in the above range, the illumination light to the display panel can be efficiently sent to the pixel aperture, so that the effective aperture ratio can be maximized. It will be possible. As a result, it is possible to realize a projection display device with extremely high light utilization efficiency.

[0009]

EXAMPLE FIG. 1 shows a graph showing the region of the distance (d) between the aperture plane and the microlens plane proposed by the present invention.

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIG. Here, a liquid crystal display element including a liquid crystal layer, an electrode group for applying a voltage to the liquid crystal layer, and a TFT that is a means for changing the applied voltage as an optical shutter means for controlling the illumination light transmittance. Was used.

Reference numeral 101a is a convex microlens which is an optical means having a positive focal length for converging the illumination light, and has a convex lens shape. 100a is a display element side transparent substrate, convex microlenses 101a is a display element side transparent substrate 100a
Many are formed in a matrix on the surface of. This surface is the microlens plane 101p. 100b is an incident side transparent substrate, and a convex microlens of the display element side transparent substrate 100a.
The transparent substrate 100 is formed in close contact with the surface on the side of 101a. 201 is a picture element, and a plurality of convex microlenses are arranged on the display element in a matrix and face each other.
Corresponds to 101a.

Reference numeral 211 denotes a light-transmitting opening provided in each picture element 201, and is defined as a portion surrounded by a light-shielding portion 212 for light-shielding and on which illumination light enters. Reference numeral 213 is a counter electrode which is one of the liquid crystal voltage applying electrodes. 210 is a counter substrate, on which an opening 211, a light shielding part 212, and a counter electrode 213 are formed on the surface. This surface is the opening plane 211p. 221
Is another picture element electrode serving as a liquid crystal voltage applying electrode and forms a capacitance between the opposing electrodes 213.

A TFT 222 is connected to the picture element electrode 221 as a liquid crystal applied voltage changing means. 220 is an array substrate on which a pixel electrode 221 and a TFT 222 are formed. It should be noted that many other structures described above are formed on the array substrate 220 in order to drive the TFT 222, but since they are not directly related to the present invention, description thereof is omitted here. The counter substrate 210 and the array substrate 220 are a counter electrode 213 and a pixel electrode 2
21 and the liquid crystal layer 230 between them.
Is enclosed.

Reference numeral 200 denotes a liquid crystal display element, which comprises a counter substrate 210, an array substrate 220 and a liquid crystal layer 230. The transparent substrate 100 and the liquid crystal display element 200 are bonded to each other on the display element side transparent substrate 100a side and the counter substrate 210 side to form the display panel 300. 400 is the illumination light, with a constant incident distribution angle θ
Display panel 30 from the transparent substrate 100 side with (≦ θmax)
Incident on 0.

In the structure of this embodiment, by dividing the transparent substrate into two pieces, while keeping d at an appropriate value,
It is possible to maintain the strength of the display panel. The various parameters related to the present invention are within the range presented by the present invention described above, and specifically are as follows.

D = 400 μm Kp = 42 μm Pp = 72 μm θmax = 2 ° φmax = 16 ° This display panel was actually irradiated with illumination light and the effective aperture ratio was evaluated by measuring the illuminance. 35% → Effective aperture ratio was 72%, showing a clear effect of improving the effective aperture ratio.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. Convex microlens 10
1a is formed directly on the surface of the counter substrate 210, there is no display element side transparent substrate, and the incident side transparent substrate 100b is the counter substrate 21.
It is placed in close contact with the surface of the 0-shaped convex microlens 101a side. Other configurations and various parameters were the same as in Example 1. Even in this configuration, the geometrical aperture ratio was 35% → the effective aperture ratio was 66%, showing a clear effect of improving the effective aperture ratio.

(Embodiment 3) A third embodiment of the present invention will be described with reference to FIG. Convex microlens 10
1a is formed on the incident side transparent substrate 100b, there is no display element side transparent substrate, and the incident side transparent substrate 100b is in direct contact with the counter substrate 210 on the convex microlens 101a side. Other configurations and various parameters were the same as in Example 1. Even in this configuration, the geometrical aperture ratio was 35% → the effective aperture ratio was 67%, showing a clear effect of improving the effective aperture ratio.

(Embodiment 4) A fourth embodiment of the present invention will be described with reference to FIG. The ion irradiation microlens 101b is formed on the display element side transparent substrate 100a by a change in the refractive index due to ion irradiation. Other configurations and various parameters were the same as in Example 1. Even in this configuration, the geometric aperture ratio was 35% → the effective aperture ratio was 61%, and a clear effect of improving the effective aperture ratio was observed.

(Embodiment 5) A fifth embodiment of the present invention will be described with reference to FIG. The ion irradiation microlens 101b is formed on the counter substrate 210 by a change in the refractive index due to ion irradiation. Other configurations and various parameters were the same as in Example 2. Even in this configuration, the geometrical aperture ratio was 35% → the effective aperture ratio was 57%, and a clear effect of improving the effective aperture ratio was observed.

(Embodiment 6) A sixth embodiment of the present invention will be described with reference to FIG. The ion irradiation microlens 101b is formed on the incident side transparent substrate 100b by a change in the refractive index due to ion irradiation. Other configurations and various parameters were the same as in Example 3.
Even in this configuration, the geometrical aperture ratio was 35% → the effective aperture ratio was 59%, and a clear effect of improving the effective aperture ratio was observed.

[0022]

The distance (d) between the plane in which the pixel aperture is present and the plane in which the optical means (microlens) is present is
By defining the range of the present invention, it is possible to realize a significant improvement in the effective aperture ratio that cannot be achieved by the conventional microlens structure, and to adjust the irradiation light within the range in which the characteristics of the light source and the display element are kept to the maximum. While suppressing the strength,
It enables to obtain high screen brightness.

[Brief description of drawings]

FIG. 1 is a graph showing a region of a distance (d) between an aperture plane and a microlens plane proposed by the present invention.

FIG. 2 is an optical path diagram for explaining the effect of improving the effective aperture ratio by a microlens.

FIG. 3 is a configuration diagram of a display panel according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of a display panel according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a display panel according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of a display panel according to a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram of a display panel according to a fifth embodiment of the present invention.

FIG. 8 is a configuration diagram of a display panel according to a sixth embodiment of the present invention.

FIG. 9 is a block diagram of a conventional display panel.

[Explanation of symbols]

 100 Transparent substrate 100a Incident side transparent substrate 100b Display element side transparent substrate 101 Micro lens 101a Convex micro lens 101b Ion irradiation micro lens 101p Micro lens plane 200 Liquid crystal display element 201 Picture element 210 Opposed substrate 211 Opening 211p Opening plane 212 Light blocking 213 Counter electrode 220 Array substrate 221 Pixel electrode 222 TFT 300 Display panel 400 Illumination light

Claims (1)

[Claims] 1. A display element having a plurality of apertures arranged in a matrix on a plane and having a light shutter means for controlling the transmittance of incident illumination light, and a positive focal length corresponding to the apertures. In a projection display device comprising a plurality of optical means having a matrix arranged in a matrix on a transparent substrate, the distance between the plane where the opening is present and the plane where the optical means is present (d ) Is the pixel width (Pp) and the opening width (Kp) in at least one direction, the illumination light incident distribution angle (θmax), and the exit side optical system maximum acceptance angle (φm).
ax), (1/2) (Pp-Kp) / (tan (φmax) -2tan (θmax)) ≦ d ≦ (1/2) Kp /
A projection display device characterized by satisfying the relationship of tan (θmax).