JPH0348885A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain a compact and high-performance device by synthesizing the modulated light beams of respective primary colors modulated by respective reflection type liquid crystal display elements in an identical direction by plural dichroic mirror surfaces and emitting the synthesized light beam in a direction perpendicular to an incident direction by the plane of polarization and separation. CONSTITUTION:The 1st, the 2nd and the 3rd reflection type liquid crystal display elements for modulating primary colors 1, 2 and 3 are arranged in parallel with three surfaces of a dichroic prism 17, and the respective primary colors separated by 1st and 2nd dichroic mirror surfaces 4 and 5 are made incident on the corresponding elements 1, 2 and 3, polarized and modulated to be reflected. The modulated light beams of the respective primary colors modulated by the respective reflection type liquid crystal display elements are synthesized by the mirror surfaces 4 and 5 of the dichroic prism in the identical direction and made incident on the plane of polarization and separation 6. Then, only the component obtained by modulating the light to be 2nd polarized light emits 1st, 2nd and 3rd primary color modulated light beams 13, 14 and 15 in the direction nearly perpendicular to the incident direction by the plane 6.

Description

[Detailed Description of the Invention] [Industrial Application Field] Liquid crystal display elements are widely applied as low power consumption flat panel displays and light bulbs for projection. In particular, color liquid crystal projectors that independently modulate three primary colors using three liquid crystal display elements and project them compositely using an optical system have advantages over conventional projectors using CRTs, such as being smaller, lighter, lower cost, and easier to operate. It has been put into practical use. This color LCD projector is equivalent to a direct-view type when viewed from behind the projection surface (rear projection method), and can be applied not only to a large screen front projection (front projection method) but also to all display applications. . The present invention relates to a color liquid crystal display device for a color liquid crystal projector that can be used in all such display applications.

[Conventional technology and its issues]

Figure 2 is a commercially available color LCD projector-V.
This is an example of a color liquid crystal display device used for this purpose.Basically, three transmissive liquid crystal display elements for modulating one primary color (a transmissive liquid crystal display element 21 for modulating the first primary color, a transmissive liquid crystal display element 21 for modulating the second primary color) Transmissive liquid crystal display element 22, third primary color modulation transmissive liquid crystal display element 26, four dichroic mirror surfaces (dichroic mirror surface A: 24, dichroic mirror surface B:
25, dichroic mirror surface C: 26, dichroic mirror surface D: 27. Three reflective surfaces (reflective surface A: 29,
Reflective surface B: 30, reflective surface C: 31), and incident light consisting of at least three primary colors, a first primary color, a second primary color, and a third primary color, is used for first primary color modulation, second primary color modulation, It has a function of modulating with at least three liquid crystal display elements for modulating the third primary color, combining the modulated light of the first primary color, the second primary color, and the third primary color and outputting the resultant light in the same direction. That is, the first
The primary color incident light 62 passes through the dichroic mirror surface A: 24, is reflected by the reflective surface A: 29, and enters the first primary color modulation transmissive liquid crystal display element 21. The second primary color incident light 66 is reflected by dichroic mirror surface A: 24 and dichroic mirror surface B: 25, and enters the second primary color modulation transmission type liquid crystal display element. The third primary color incident light 64 is reflected by dichroic mirror surface A: 24, and dichroic mirror surface B: 25.
is transmitted, reflected by reflective surface B: 30 and reflective surface C: 61, and enters the third primary color modulation transmission type liquid crystal display element. The modulated light of each primary color modulated by each primary color modulation liquid crystal display element is synthesized by a dichroic mirror surface C: 26 and a dichroic mirror surface D: 27, which are orthogonal to each other, formed on the dichroic prism 28 to produce first primary color modulated light. 66, second primary color modulated light 67, and third primary color modulated light 68.

A projector constructed of three transmissive liquid crystal display elements for modulating one primary color, four dichroic mirror surfaces, and two reflective surfaces is also commercially available.

The drawbacks of the conventional example are that it requires a large number of expensive optical components such as dichroic mirror surfaces and reflective surfaces, resulting in high cost and large size.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color liquid crystal display device for a color liquid crystal projector that can be configured with a small volume and a small number of optical components.

[Means to solve the problem]

In the present invention, the incident light is separated into the first polarized light and the second polarized light by a polarization separation surface arranged at approximately 45 degrees with respect to the direction of incidence, and only one of the polarized lights is transmitted, and each primary color is transmitted. The first and second dichroic ink mirror surfaces formed on the dichroic prism cause the three surfaces of the dichroic prism to be arranged substantially parallel to each other.
Modulated light of each primary color is incident on a reflective liquid crystal display element for primary color modulation, a reflective liquid crystal display element for second primary color modulation, or a reflective liquid crystal display element for third primary color modulation, and is modulated by each reflective liquid crystal display element. are again combined in the same direction by the first and second dichroic mirror surfaces formed on the dichroic prism, and are incident on the polarization separation surface,
The configuration is such that the light is emitted in a direction substantially perpendicular to the direction of incidence by the polarization separation surface. In this configuration, only one dichroic prism and one polarization separation surface are required as optical components, and the cost of the optical components is approximately halved. In addition, the volume is only two to three times that of the conventional example.

〔Example〕

FIG. 1 shows an embodiment of a color liquid crystal display device of the present invention.

Basically, three reflective liquid crystal display elements for modulating one primary color (
Dichroic prism 17 (first dichroic mirror surface 4, Second dichroic mirror surface 5. Consists of one polarization separation surface 6. Incident light composed of three primary colors: a first primary color, a second primary color, and a third primary color 7.8.9.1
0.11.12 is separated into a first polarized light 7.9.11 and a second polarized light 8.1o, 12 by a polarization separation surface 6 arranged at approximately 45 degrees with respect to the incident direction, and either one of the polarized lights ( Here, only the first polarized light is transmitted. In this embodiment, the polarization separation surface 6 is formed by a multilayer film coating, and the polarization prism 16
formed on top. Subsequently, the light enters a dichroic prism 17 consisting of a first dichroic mirror surface 4 and a second dichroic mirror surface 5 that are arranged at approximately 45 degrees with respect to the direction in which the light travels. Here, the first dichroic mirror surface reflects only the first primary color and transmits the second and third primary colors. Also, the second dichroic mirror surface is the third dichroic mirror surface.
Only the primary colors are reflected, and the first and second primary colors are transmitted. The reflective liquid crystal display element 1 for first primary color modulation, the reflective liquid crystal display element 2 for second primary color modulation, and the reflective liquid crystal display element 3 for third primary color modulation are arranged parallel to the three surfaces of the dichroic prism 170, Each of the primary colors separated by the first dichroic mirror surface 4 and the second dichroic mirror surface 5 enters the corresponding primary color modulation reflective liquid crystal display element 1.2.3, undergoes polarization modulation, and is reflected.

The modulated light of each primary color modulated by each reflective liquid crystal display element is again combined in the same direction by the first and second dichroic mirror surfaces 4.5 on the dichroic prism, enters the polarization separation surface 6, and is combined in the same direction by the first and second dichroic mirror surfaces 4.5 on the dichroic prism. Only the components modulated into two polarized lights are separated into first primary color modulated light 16 and second primary color modulated light 14 in a direction almost perpendicular to the incident direction by the polarization separation surface B.
, is emitted as third primary color modulated light 15.

The polarizing prism 16 and the dichroic prism J17 are bonded together to reduce reflection loss.

If the three primary color modulation reflective liquid crystal display elements are also bonded to the dichroic prism, reflection loss can be further reduced.

〔Effect of the invention〕

As is clear from the above embodiments, the present invention provides a compact and low-cost color liquid crystal display device for a color liquid crystal projector that has never been seen before.

In terms of volumetric evaluation, the total number of guichroic mirror surface areas (prisms), reflecting surfaces, and polarization separation surfaces is roughly proportional to the volume. In the conventional example shown in FIG. 2, the total number is 6 (dichroic mirror surface 2, dichroic prism 1, reflective surface 3), and in other conventional examples, the total number is 6 (dichroic mirror surface 4, reflective surface 2).

In contrast, in the embodiment of the present invention shown in FIG. 1, the total number is two (one dichroic prism, one polarization separation surface), and the volume is one-half to one-third of that of the conventional example.

The cost of optical components can also be evaluated based on the total number, and the present invention can reduce the cost by half compared to the conventional example.

Although not described in the embodiments, the invention does not depart from the invention even if optical parts such as a reflector or lens are added to the basic structure of the invention to bend the optical path or change the distance or area.

[Brief explanation of drawings]

FIG. 1 is an optical path diagram showing an embodiment of a color liquid crystal display device of the present invention, and FIG. 2 is an optical path diagram showing a conventional color liquid crystal display device. 1... Reflective liquid crystal display element for first primary color modulation, 2
...Reflective liquid crystal display element for second primary color modulation, 6.
...Reflective liquid crystal display element for third primary color modulation, 6...
...Polarization separation surface, 17...Dichroic prism.

Claims (1)

[Claims] Incident light consisting of at least three primary colors, a first primary color, a second primary color, and a third primary color, for first primary color modulation, second primary color modulation,
A color liquid crystal display device that has a function of modulating light with at least three liquid crystal display elements for modulating the third primary color, combining the modulated light of the first primary color, the second primary color, and the third primary color and outputting the modulated light in the same direction. Therefore, the incident light has an angle of about 4 with respect to the direction of incidence.
The polarized light is separated into the first polarized light and the second polarized light by the polarization separation plane arranged at 5 degrees, and only one of the polarized lights is transmitted.
and a second dichroic mirror surface, the first dichroic prism is arranged substantially parallel to the three surfaces of the dichroic prism.
Modulated light of each primary color is incident on a reflective liquid crystal display element for primary color modulation, a reflective liquid crystal display element for second primary color modulation, or a reflective liquid crystal display element for third primary color modulation, and is modulated by each reflective liquid crystal display element. are again combined in the same direction by the first and second dichroic mirror surfaces formed on the dichroic prism, and are incident on the polarization separation surface,
A color liquid crystal display device characterized by a polarization separation plane that emits light in a direction substantially perpendicular to the direction of incidence.