JPS62257125A - Liquid crystal display plate for projection device - Google Patents

Abstract

PURPOSE:To omit an independent converging Fresnel lens and a reflecting plate by providing substrates where electrodes are formed to the front and rear surfaces of liquid crystal, using a transparent electrode as the electrode on the front surface side and forming the converging Fresnel lens integrally, and forming a reflecting surface on the substrate on the back surface side. CONSTITUTION:When light beams, from a light source 11 are projected on a liquid crystal display plate 9 and electrodes 4 and 5 are selected and impressed with a voltage, dots are formed on liquid crystal to display an image. At this time, a condenser lens 12 diverges the illumination light beams from the light source 11 almost to the contour of the liquid crystal display plate 9. This illumination light beams are converged by the converging Fresnel lens 7 without any waste and projected on the liquid crystal 1, and the light beams are reflected by the electrode 5 and transmitted through the liquid crystal 1 again; and the light beams are converged by the converging Fresnel lens 7 to illuminate almost to the overall diameter of an image forming lens 13, and then projected on a screen 7. Consequently, the reflecting plate need not be provided independently and has its installation position adjusted, and converging Fresnel lens 7 is formed integrally with the transparent substrate 2, so it need not be provided independently and its fitting position need not be adjusted either.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a liquid crystal display panel for a projection device.

2. Description of the Related Art Conventionally, as described in, for example, Japanese Unexamined Patent Publication No. 59-19924, there has been a transmission type projection device that transmits light through a liquid crystal display plate and projects an image on the second liquid crystal display plate onto a screen. In addition to this, there is a reflection type projection device that applies illumination light to a liquid crystal display plate, reflects the illumination light that has passed through the liquid crystal display plate, and projects an image onto a screen by transmitting the illumination light through the liquid crystal display plate again.

However, the above projection apparatus requires an independently manufactured reflector plate to be installed in the optical path. Its installation requires position adjustment. In addition, in order to increase the resolution of images, the size of the liquid crystal display panel is increased, and the size of the dots is reduced and the number of dots is increased. need to be projected onto. Therefore, an independent condensing Fresnel lens must be installed in the optical path. Its installation requires position adjustment, which complicates assembly work and structure.

This invention was made in view of the above points, and it omits the independent condensing Fresnel lens and reflection plate, simplifies the assembly work and structure, and can form clear images with high contrast. An object of the present invention is to provide a liquid crystal display panel for a projection device.

Means for Solving the Problems A substrate on which electrodes are formed on the front and back sides of the liquid crystal is provided, the substrate on the front side is a transparent substrate, the electrode on the front side is a transparent electrode, and the transparent substrate on the front side is made to be a transparent substrate. A condensing Fresnel lens is integrally formed on the substrate, and a reflective surface is formed on the substrate on the rear side.

Therefore, the illumination light emitted from the front is focused by the condensing Fresnel lens, transmitted through the liquid crystal, reflected by the reflective surface, transmitted through the liquid crystal again, and then condensed by the condensing Fresnel lens and projected again. However, by integrally forming the condensing Fresnel lens on the transparent substrate and forming the reflective surface on the rear substrate, the independent condensing Fresnel lens and reflecting plate can be omitted. Furthermore, since the illumination light passes through the liquid crystal twice, it is possible to form a clear image with high contrast.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 3. Transparent substrates 2 and 3 are bonded to the front and back surfaces of a liquid crystal 1 on a rectangular plate.

On the back side of the front transparent substrate 2, there are many strip-shaped transparent electrodes 4.
are formed in parallel, and a large number of strip-shaped electrodes 5 are formed in parallel in a direction perpendicular to the transparent electrode 4 on the front surface of the transparent substrate 3 on the back side. These electrodes 5 are formed of metal foil such as aluminum and serve also as a reflective surface. Further, on the front surface of the front transparent substrate 2, a transmission type condensing Fresnel lens 7, which has a large number of annular grooves 6 arranged concentrically, is integrally formed. The distance between the transparent substrates 2.3 is determined by a rectangular spacer 8 that recesses the liquid crystal 1.

The liquid crystal display panel 9 configured in this manner is housed in the back of the housing 10 as shown in FIG. is held in the housing 10. A screen 14 is provided in front of the housing 10.

In such a configuration, when the light beam from the light source 11 is applied to the liquid crystal display plate 9 and a voltage is applied to selected electrodes 4 and 5, dots are formed on the liquid crystal 1 and an image is displayed. At this time, the condenser lens 12 diffuses the illumination light from the lights W and 11 to an extent that exactly matches the outline of the liquid crystal display panel 9. This illumination light is efficiently focused by the condensing Fresnel lens 7 and irradiated onto the liquid crystal 1, reflected by the electrodes 5, and transmitted through the liquid crystal 1 again. The light is focused and projected onto the screen 14 so as to illuminate the whole area.

In this way, an image is projected. The condensing Fresnel lens 7 condenses the illumination light from the light 1111 just in front of the liquid crystal 1 and irradiates the entire surface of the liquid crystal 1, while condensing the light rays reflected by the electrodes 5. It becomes possible to condense the light so that it irradiates the entire aperture of the image lens 13, and the electrode 5 serving as a reflective surface reflects the illumination light efficiently. Furthermore, the electrode 5 is connected to the liquid crystal 1
Because it is in close contact with the back of the camera, the reflected image will not shift. Therefore, even if a liquid crystal 1 with a large area and a large number of small dots is used, the resolution of the projected image can be improved. Moreover, since the illumination light passes through the liquid crystal 1 twice, the contrast of the image can be increased and the outline can be made clear. Furthermore, by using the @pole 5 as a reflective surface, there is no need to separately provide a reflective plate and adjust its installation position, and the condensing Fresnel lens 7 can also be placed on the transparent substrate 2.
Since it is integrally formed with the main body, there is no need to install it separately and adjust the mounting position. Furthermore, the condensing Fresnel lens 7 is located just in front of the liquid crystal 1, and in front of it is a light source 11 and an imaging lens 1.
3, the optical path length can be shortened and space can be saved.

Note that since the electrode 5 does not transmit light, an opaque substrate may be used in place of the transparent substrate 3 on the back surface.

Next, a second embodiment of the present invention will be described based on FIG. 4. The same parts as those in the above embodiment will be designated by the same reference numerals, and the description thereof will be omitted (the same applies hereinafter). In this embodiment, a reflective surface 15 made of metal foil is formed on the entire back surface of a transparent substrate 3, and a transparent electrode 16 is formed on the front surface of the transparent substrate 3.

Therefore, the reflective surface 1 formed on the entire back surface of the transparent substrate 3
By reflecting the illumination light by the electrodes 5, the reflection efficiency can be further improved compared to the case where the electrodes 5 arranged with even a slight gap are used as reflective surfaces as in the above embodiment.

As a modification, the back surface of the reflective surface 15 may be covered with a protective layer 17 as shown in FIG.

This protective layer 17 is formed, for example, from the same material as the transparent substrate 3 by means such as double molding.

Effects of the Invention Since the present invention is constructed as described above, the illumination light irradiated from the front is focused by the condensing Fresnel lens, transmitted through the liquid crystal, reflected by the reflective surface, transmitted through the liquid crystal again, and recondensed by the condensing Fresnel lens. A lens condenses and projects light, but by integrally forming a condensing Fresnel lens on the front transparent substrate and a reflective surface on the back substrate, it is possible to create an independent system that requires adjustment of the mounting position. The condensing Fresnel lens and the reflecting plate can be omitted, thus simplifying the assembly work and structure, and furthermore, the reflecting surface can be brought close to the back of the liquid crystal to prevent the reflected image from shifting. Moreover, since the illumination light passes through the liquid crystal twice, it is possible to form a clear image with high contrast.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a longitudinal side view, FIG. 2 is a plan view, and FIG. 3 is a longitudinal side view showing a reduced image projection state. 4 are longitudinal sectional side views showing a second embodiment of the invention, and FIG. 5 is a longitudinal sectional side view showing a modification thereof.

Claims (1)

[Claims] A substrate on which electrodes are formed is provided on the front and back surfaces of the liquid crystal, the substrate on the front side is a transparent substrate, the electrode on the front side is a transparent electrode, and a condensing Fresnel lens is integrally formed on the transparent substrate on the front side. 1. A liquid crystal display panel for a projection device, characterized in that a reflective surface is formed on the substrate on the rear side.