JPH04100002A - Projection type display device - Google Patents

Abstract

PURPOSE:To prevent the loss of the quantity of light due to reflection and to obtain a bright image on a screen by sticking transparent glass plates coated with reflection preventive films on the incidence-side and projection-side polarizing elements of a liquid crystal light valve. CONSTITUTION:There are the polarizing elements 2 and 3 on the incidence side and projection side of the transmission type liquid light valve 1 which is used as the projection type display device and the transparent glass plates coated with the reflection preventive films are stuck on the incidence-side surfaces of the polarizing elements 2 and 3. Consequently, the loss of the quantity of transmitted light is less than that when only polarizing plates are used and the display image becomes bright. Similar effect is obtained by sticking the reflection preventive glass plates on only one polarizing plates or both the incidence and projection surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a projection display device that displays images using a transmissive liquid crystal light valve.

[Prior Art] FIG. 3 is a block diagram of a transmissive liquid crystal light valve and a polarizing element in a conventional projection display device. Polarizing f-factors are arranged on the input side and the output side of the light valve.

[Problems to be Solved by the Invention] In the conventional projection display device as described above, reflection on the surfaces of the polarizing elements on the incident side and the output side reduces the light I that passes through these optical members, and the projection This is an obstacle to brightening the image on the screen when the light is reflected, and it is difficult to directly coat the surface of the polarizing element with an anti-reflection film to prevent this reflection due to manufacturing problems. there were.

Therefore, the present invention was made to solve such problems, and is a projection type that can obtain a bright image on a screen by preventing loss of light amount due to reflection on the surface of a polarizing element. The purpose is to provide a display device.

[Means for Solving the Problems 1] A projection display device according to the present invention is constructed by bonding optical elements coated with an antireflection film to polarizing elements disposed on the incident side and the output side of a transmissive liquid crystal light valve. be.

[Example] FIG. 1 shows an example of the present invention. There are polarizing elements 2 and 3 on the incident side and output side of a transmissive liquid crystal light valve 1 used in a projection display device. Glass plates are glued together.

The polarizing element is a plastic film-like polarizing plate chip with an adhesive on one side, and the glass plate and the polarizing plate are bonded together by this adhesive.

FIG. 2 shows another embodiment of the present invention, in which two transparent glass plates coated with antireflection films are bonded together with polarizing plates having adhesives on both sides sandwiched therebetween.

In the conventional example shown in Figure 3, only a polarizing plate (polarizing element) is arranged.
In this case, the amount of transmitted light is lost due to external reflection on the incident side surface of the polarizing plate and internal reflection on the exit side surface, which is an obstacle to making the projection screen brighter. This is because the difference in refractive index between air and the polarizing plate is relatively large, and to reduce this reflection it is good to coat the surface with an anti-reflection film, but it is not possible to coat the polarizing plate itself with an anti-reflection film. The problem is that it is difficult to manufacture.

Therefore, the embodiments shown in Figs. 1 and 2 suppress the loss of the amount of transmitted light due to reflection without applying an antireflection film to the polarizing plate itself. In the embodiment shown in FIG. 1, the measures are taken only on the incident side.

In the example, since there is an anti-reflection film on the interface between the transparent glass plate attached to the polarizing plate and the air, the reflection that normally occurs at the interface between glass and air, which is about 4%, is reduced to less than 1% (multilayer coating). case). “This is the same for external reflection on the input side and internal reflection on the output side.As for the relationship between the transparent glass plate and the polarizing plate, assuming that the adhesive bonding does not impede the transmission of light, Since there is no difference in the refractive index of glass, adhesive, and polarizing plate in air, the loss due to reflection at these interfaces is small.Therefore, there is little need for an antireflection film here. ,
Even if a transparent glass plate is coated with an anti-reflection film on only one side that comes into contact with the air, it will not affect the overall effect much.

This time, in order to reduce the loss of transmitted light due to reflection from optical elements where it is difficult to directly attach an anti-reflection film, we used a method of bonding other optical elements with anti-reflection films and small differences in refractive index. , this method applies not only to polarizing plates, but also to
Similar effects can be obtained using other optical elements of a display device.

[Effect of the invention 1] As described above, according to the present invention, since the transparent glass plate coated with an antireflection film is bonded to the polarizing plates disposed on the incident side and the output side of a transmission type liquid crystal light valve, polarized light This has the effect that the loss of the amount of transmitted light due to reflection is smaller than in the case of only a plate, and the displayed image becomes brighter.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, and FIG. 3 is a block diagram of a conventional example.・Transmission type liquid crystal light valve ・Entrance side polarizing element (polarizing plate with adhesive on one side) ・Output side polarizing element (polarizing plate with adhesive on one side) ・Transparent glass plate with anti-reflection film Input side polarizing element (polarizing plate with adhesive on both sides) Plate) Output side polarizing element (polarizing plate with adhesive on both sides) Input side polarizing element (polarizing plate without adhesive) - Output side polarizing element (polarizing plate without adhesive) Light source projection lens and above Applicant: Seiko Epson Corporation

Claims (1)

[Scope of Claims] A projection type display device that irradiates light from a light source onto a transmissive liquid crystal light valve using a light guide means and a light condensing means, and projects image light formed by the liquid crystal light valve, comprising: a liquid crystal light valve. Projection characterized in that a transparent glass plate coated with an anti-reflection film is attached to the incident side, the output side, or both of at least one polarizing element of the incident side polarizing element and the output side polarizing element. Type display device.