JPS63123018A - Projection type liquid crystal display device - Google Patents

Abstract

PURPOSE:To suppress a decrease in the quantity of light transmitted through a projection optical system and to obtain a bright display image by projecting visible light which is polarized by a polarization beam splitter and a lambda/4-wavelength plate upon a liquid crystal display panel which is operated by an image information writing means. CONSTITUTION:The visible light from a light source 21 is polarized by the polarization beam splitter 24 and its S polarized component is converted by the lambda/4-wavelength plate 35 into circular polarized light, which is projected on the liquid crystal display panel 25. The panel 25 is operated by the image information writing means consisting of a laser 26, a beam splitter 33, and a liquid crystal driving circuit 29 to reflect the light from the wavelength plate 35, and the reflected light is further converted by a wavelength plate 35 into P polarized light, which is passed through the splitter 24 to form a color image on a screen 32 through filters 31 of respective colors. The visible light becomes the S polarized light which is a half in quantity through the splitter 24 and the P polarized light of the wavelength plate 35 is passed as it is, so the reduction in the quantity of light is only a half. Consequently, a bright display image is obtained without increasing the quantity of light of the light source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device, and particularly to a projection type liquid crystal display device having a projection optical system.

[Conventional technology]

As a conventional projection type liquid crystal display device, for example,
-126396 is known. A conventional device of this kind, as shown in FIG.
Light from a projection light source 1 consisting of a tungsten lamp, a xenon lamp, etc. has its heat rays removed by a heat ray cut filter 2, is converted into parallel rays by a condenser lens 3, and enters a semi-transparent mirror (half mirror) 4. It is supposed to be done.

Approximately 1/2 of the amount of light incident on the half mirror 4 passes through the half mirror 4 as it is, and the remaining 1/2 of the amount of light is reflected and irradiated onto the liquid crystal display panel 5.

Each liquid crystal display panel 5 receives laser light from a laser 6 through a modulator 7. Deflector8. -1 via beam splitter 13
--The light beam is incident on the liquid crystal drive circuit 9, and image information is written by driving the liquid crystal drive circuit 9. The arrangement of smectic liquid crystals within the liquid crystal display panel changes depending on the image information. When the light from the half mirror 4 enters the liquid crystal display panel 5, this incident light is guided to the smectic liquid crystal, and after being reflected by the AQ reflector, the reflected light of the optical image according to the arrangement of the liquid crystal is transmitted to the half mirror 4. It is designed to emit to the side. After passing through the half mirror 4, this reflected light is colored and enlarged through a projection lens 10 and a color filter 11, and then combined on a screen 12, so that an image is displayed on the screen 12. . Each liquid crystal display panel 5 and color filter 11 each have three
They are provided corresponding to each color element of the primary colors, and a color image is displayed on the screen 12.

[Problem that the invention seeks to solve]

However, in the conventional apparatus, the projection optical system includes the projection light source 1. Condenser lens 3. Since the half mirror is composed of a 4g projection lens 10, when the light reflected by the liquid crystal display panel 5 enters the half mirror 4, 1/2 of this light amount is reflected to the 8 projections on the projection lens 10 side. is 1-
The amount of light is further reduced by ]/2 when transmitted from the liquid crystal display panel 5 to the projection lens 10 side via the half mirror 4. Therefore, the amount of light incident on the projection lens 1o is 1/4 of the amount of light incident on the half mirror 4 from the light source 1.
decreases to Further, the amount of light transmitted through the color filter 11 is reduced by the color filter 11. Therefore, in such an optical system, a dark image is displayed on the screen 12. In order to brighten the image on the screen 12, it was necessary to increase the amount of light from the projection light source 1.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a projection type liquid crystal display device that can suppress a decrease in the amount of light propagating through a projection optical system. .

[Means for solving problems]

In order to achieve the above object, the present invention includes a liquid crystal element group between a transparent electrode and a reflection plate, guides incident light from the transparent electrode side to the liquid crystal element group, and generates reflected light of an optical image according to the arrangement of the liquid crystal elements. A liquid crystal display panel that emits light, an image information writing means that writes image information to the liquid crystal display panel, an image display board that receives light from the liquid crystal display panel and displays an image, and a light ray generator that generates visible light. , polarizes the incident light from the light beam generator and reflects only the S-polarized component toward the liquid crystal display panel, and polarizes the incident light from the liquid crystal display panel and transmits only the P-polarized component toward the image display panel. polarizing beam splitter;
Projection comprising a retardation plate that circularly polarizes the S-polarized light reflected by the polarizing beam splitter and transmits it to the liquid crystal display panel side, and converts the circularly polarized light from the liquid crystal display panel into P-polarized light and transmits it to the polarizing beam splitter side. This is a type of liquid crystal display device.

[Effect]

When visible light is generated from the light beam generator, this visible light is incident on the polarizing beam splitter. This incident light is polarized by a polarizing beam splitter, and only the S-polarized component is reflected toward the liquid crystal display panel. This S-polarized light is circularly polarized by a retardation plate and enters the liquid crystal display panel. The light incident on the liquid crystal display panel is reflected by the liquid crystal display panel and then enters the retardation plate. At this time, the circularly polarized light is converted into P-polarized light and enters the polarizing beam splitter. P incident on the polarizing beam splitter
The polarized light is transmitted as it is to the image display plate, and a light image corresponding to the arrangement of the liquid crystal elements is displayed on the image display plate.

〔Example〕

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

FIG. 1 shows the configuration of a preferred embodiment of the present invention. In FIG. 1, a projection light source 21 as a light beam generator
It consists of a lamp, such as a xenon lamp, whose spectral distribution curve has a continuous spectrum almost similar to that of sunlight in the wavelength region of visible light.

The projection light emitted from the projection light source 21 is converted into light having a continuous spectrum only in the visible light wavelength range by removing components in the near-infrared to infrared wavelength range, which are heat rays. is converted into parallel light. The projected light converted into parallel light by the condenser lens 23 is reflected toward the polarized crystal display panel 25, and the P-polarized light component is transmitted as is. For this reason, the polarizing beam splitter 2
Only the S-polarized light component having an amount of 1/2 of the projected light incident on the LCD panel 4 is irradiated onto the liquid crystal display panel 25 via the λ/4 wavelength plate 35.

The λ/4 wavelength plate 35 functions as a retardation plate that converts linearly polarized light into circularly polarized light and polarizes circularly polarized light into linearly polarized light, and polarizes the S-polarized light from the polarizing beam splitter 24 into circularly polarized light to display the liquid crystal display. The circularly polarized light irradiated onto the panel 25 and reflected by the liquid crystal display panel 25 is converted into P-polarized light.

As shown in FIG. 2, the liquid crystal display panel 25 includes a glass substrate 25B and a smectic liquid crystal layer 25E.

It has a glass substrate 25I, and a transparent electrode 25C2 light distribution film 25 is provided between the glass substrate 25B and the smectic liquid crystal layer 25E.
A light distribution film 25F is formed between the smectic liquid crystal layer 25E and the glass substrate 25I.

An AQ reflection film 25G and a laser light absorption film 25H are formed. A visible light non-reflection film 25A is mounted on the surface of the glass substrate 25B, and a laser light non-reflection film 25J is mounted on the surface of the glass substrate 25I. The liquid crystal display panel 25 receives laser light from a laser 26 through a modulator 27. It is irradiated via a deflector 28 and a beam splitter 33. This liquid crystal display panel 25 utilizes the thermo-optic effect, in which the molecular arrangement of the liquid crystal changes during the process of heating the smectic liquid crystal with a laser beam from the laser 26 and cooling it after being subjected to a thermal treatment. There is.

Then, the voltage from the liquid crystal element drive circuit 29 is applied to the transparent electrode 25.
When G is applied, reflected light of an optical image corresponding to the arrangement of the liquid crystal elements is emitted with respect to the incident light from the transparent electrode 25G side. That is, the liquid crystal display panel 25 includes a laser 26, a modulator 27 . Deflector 28. beam splitter 3
3. Image information is written by an image information writing means consisting of a liquid crystal element drive circuit 29. Note that the deflector 28 is a polygon mirror.

It has a galvanometer mirror, and the laser beam from the laser 26 is
- Scanning is performed in the Y direction.

The light reflected by the liquid crystal display panel 25 is polarized into P-polarized light by the λ/4 wavelength plate 35, and then passes through the polarizing beam splitter 24 as it is, passes through the projection lens 309 and the color filter 31, and is projected onto the screen 32 as an image display board. The irradiated six color filters 31 are red.

They are set up in correspondence with the color elements of the three primary colors of green and blue.
Projection lens 309 Color filter 31. The light that has passed through is expanded and colored, and is imaged on the screen 32 as a color image.

Note that when writing image information on each liquid crystal display panel 25, a method is adopted in which the output light of the laser 26 is divided into three parts by a beam splitter 332 and a reflecting mirror 34 corresponding to the three primary colors red, green, and blue.

As described above, in this embodiment, the S-polarized light having an amount of 1/2 of the projected light incident on the polarization beam splitter 24 from the projection light source 21 is reflected toward the λ/4 wavelength plate 35 side and transmitted to the liquid crystal display panel 25. The reflected light from the liquid crystal display panel 25 is converted into P-polarized light by the λ/4 wavelength plate 35, and the P-polarized light component is transmitted through the polarization beam splitter 24, so that the amount of light from the projection light source 21 is reduced to 1. The screen 32 is irradiated to the extent that the amount of light decreases by /2, and the decrease in the amount of light of the projection optical system can be suppressed.

Here, when displaying a color image on the screen 32, it is not possible to significantly improve color reproducibility just by suppressing the decrease in the light amount of the projection optical system, so in this embodiment, λ/4 A configuration for adjusting the spectral characteristics of the wavelength plate 35 and the color filter 31 is supported.

That is, as shown in FIG. 3, the spectral characteristics of the λ/4 wavelength plate 35 are characteristic a for red and characteristic a for green.

Blue exhibits characteristic C, and each color element has a transmittance peak value in a specific wavelength range. Therefore, in this example,
In the spectral characteristics of the λ/4 wavelength plate 35 and the color filter 31, in order to make the peak wavelength range of transmittance almost coincide, red is used as shown in FIG.

The color filters 31 for green and blue are each configured with a filter having a characteristic dje#f.

From FIG. 4, the half-value width of the color filter 31 is as wide as about 70 nm, and brightness is emphasized, but the λ/4 wavelength plate 3
Since the peak characteristics of the color filter 31 and the color filter 31 are almost the same, both the brightness and stimulus purity of the image displayed on the screen 32 can be improved. or,
When the color range g of the device in this example was measured, as shown in FIG. 5, a color range g wider than that of the conventional device was obtained. Therefore, the color range and stimulation purity can be significantly improved compared to conventional devices. Furthermore, it was confirmed that the brightness of the image displayed on the screen 32 was about 1.7 times brighter compared to the conventional device.

FIG. 6 shows the configuration of another embodiment of the present invention12) It is.

In this embodiment, the light beam generator 40 that projects light to the beam splitter 24 is composed of red, green, and blue projection light sources,
The color filter 31 is removed from the projection optical system,
Since the other configurations are the same as those in the first figure, the same or corresponding parts are given the same reference numerals and their explanation will be omitted.

The light beam generation m40 is generated by a single projection light source 21. as shown in FIG. It consists of a heat ray cut filter 22° condenser lens 23, two dichroic mirrors 56, 57, and two mirrors 5]. The radiation light emitted from the projection light source 21 has a heat ray portion removed by a heat ray cut filter 22, and is converted into parallel light by a condenser lens 23.

This parallel emitted light is separated into blue light and yellow light by the dichroic mirror 56, and the blue light is reflected by the mirror 51 and radiated from the blue light generator 40 to the beam splitter 24.

On the other hand, the yellow light transmitted through the dichroic mirror 56 is separated into red light and green light by the dichroic mirror 57, and the green light is reflected by the mirror 51 and irradiated to the green beam splitter 24 via the green light generator 40. Ru. Further, the red light transmitted through the dichroic mirror 57 is sent from the red light beam generator 40 to the red beam splitter 24.
is irradiated to.

In this way, in this embodiment, the light from the single projection light source 21 is projected to each beam splitter 24, so it is possible to reduce the temperature rise due to the energy of the projected light from the polarizing beam splitter 24, and The device can be made smaller.

Further, in this embodiment, as shown in FIG. 8, the spectral characteristics of the λ/4 wavelength plate 35 for red, green, and blue are given by
, b, and Q, and red as dichroic mirrors 56 and 57.

Since the spectral characteristics of green and blue having the characteristic 1y Jy k are used, the peak wavelength ranges of the spectral transmittance of the λ/4 wavelength plate 35 and the dichroic mirror 56 and 57 almost match, improving the brightness of the image. be able to.

Furthermore, when the color range of the apparatus in this example was measured, the measurement results shown in FIG. 9 were obtained. That is,
The color range Q of the device in this example was wider than the color range m of the conventional device, and the color range and stimulus purity were significantly improved. It was also confirmed that the brightness of the image was approximately 1.8 times that of the conventional device.

〔Effect of the invention〕

As described above, according to the present invention, since the reduction in the light amount of the projection optical system is suppressed, the displayed image can be brightened without increasing the light amount of the projection light source.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the present invention, Fig. 2 is a cross-sectional view of a liquid crystal display panel, Fig. 3 is a spectral transmittance characteristic diagram of a λ/4 wavelength plate, and Fig. 4 is a λ/4 wavelength diagram. A spectral transmittance characteristic diagram of a plate and a color filter, FIG. 5 is a diagram for explaining the color range of the device according to the present invention, FIG. 6 is a configuration diagram of another embodiment of the present invention, and FIG. An explanatory diagram of the configuration of the light beam generator 40, FIG.
Spectral transmittance characteristic diagram of 4-wave plate and dichroic mirror,
FIG. 9 is a diagram for explaining the color range of the apparatus according to the present invention, and FIG. 10 is a configuration diagram of a conventional example. 21... Projection light source, 24... Polarizing beam splitter, 25... Liquid crystal display panel, 26... Laser, 31
...Color filter, 32...Screen, 35...
λ/4 wavelength plate, 40...Light beam generator, 56.57...
・Dichroic mirror.

Claims (1)

[Claims] 1. A liquid crystal element that includes a liquid crystal element group between a transparent electrode and an opposite plate, guides incident light from the transparent electrode side to the liquid crystal element group, and emits reflected light of a light image according to the arrangement of the liquid crystal elements. a panel, an image information writing means for writing image information on the liquid crystal display panel, an image display board for receiving light from the liquid crystal display panel and displaying an image, a light ray generator for generating visible light, and a light ray generator. a polarizing beam splitter that polarizes incident light from the liquid crystal display panel side and reflects only the S-polarized component toward the liquid crystal display panel side, and polarizes the incident light from the liquid crystal display panel side and transmits only the P-polarized component toward the image display panel side; , S reflected by the polarizing beam splitter
A projection type liquid crystal comprising: a retardation plate that circularly polarizes polarized light and transmits it to a liquid crystal display panel side, converts the circularly polarized light from the liquid crystal display panel into P-polarized light and transmits it to a polarization beam splitter side. Display device. 2. In the invention described in claim 1, each of three liquid crystal display panels, polarizing beam splitters, retardation plates, and light beam generators is provided, and each polarizing beam is provided between each polarizing beam splitter and the image display plate. A color filter is arranged that transmits only light in a specific wavelength range out of the light transmitted through the beam splitter, and each retardation plate has spectral characteristics corresponding to each color element of the three primary colors, and each retardation plate and each color filter A projection type liquid crystal display device characterized in that the peak wavelength ranges of the spectral transmittances of are almost the same. 3. In the invention set forth in claim 1, each of three liquid crystal display panels, three polarizing beam splitters, and three retardation plates is provided, and the light beam generator includes a single light source and the light from the light source in three primary colors. It has a plurality of dichroic mirrors that separate visible light into visible light and project it onto each polarizing beam splitter. Each retardation plate and each dichroic mirror have spectral characteristics corresponding to each color element of the three primary colors. A projection type liquid crystal display device characterized in that the peak wavelength ranges of the spectral transmittances of the mirrors are almost the same.