JPS6138976A - Projection type display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in projection display devices.

[Prior art]

Projection type display devices that can display moving images have traditionally used projection type CRTs (Television Society Journal WOL8
8. A1. (1984) P, 11), those using liquid crystal 9-ite pulp (optical volume 18 eA
(1984) I', 52), those using electro-optic ceramics (1 Japa regarding PLZTK),
n 5ociety of Appl.

Phys, voL44. (1975) P, 87) and the like are known. Both simply project and enlarge an image onto a screen.

[Problem that the invention seeks to solve]

In the prior art described above, light is irradiated onto a screen placed at an image formation position, and the light is scattered there to localize the image, and ambient light is similarly scattered on the screen. As a result, the black level increases in bright environments, leading to a decrease in contrast. Furthermore, when using a light pulp that emits a light beam with polarization characteristics, conventional screens designed for light beams that do not have polarization characteristics do not make effective use of the polarization characteristics.

The present invention is intended to solve these problems, and its purpose is to provide a projection display device with high contrast.

[Means for solving problems]

In order to solve the above problems, the present invention provides a screen of a projection display device with polarization characteristics.

[Effect]

To describe the effects of the present invention, since the screen has polarization characteristics, firstly, it effectively absorbs ambient light, lowers the black level, and increases display contrast. Conventional screens that have isotropic characteristics with respect to ambient light (for example, transparent screens coated with dyes) absorb ambient light uniformly. In contrast, the present invention directs the absorption axis of the screen in the direction of the polarized light component contained in a larger amount among the polarized light components on the surrounding surface, and selectively absorbs the polarized light component.

Second, when the output light from the image forming means has polarization characteristics, a screen having polarization characteristics selectively transmits or reflects the output light having polarization characteristics. Therefore, more components harmful to display can be removed than with an isotropic screen, and a high-contrast image can be localized on the screen. Furthermore, if the image forming means emits light that originally has polarization characteristics, an image that is the intensity distribution of the light can also appear on the screen.

〔Example〕

Example 1 Example 1 is a light pulp using electro-optic effect.
This is an example using a liquid crystal display panel (hereinafter referred to as TFTnCD) in which a 900 twisted nematic liquid crystal (hereinafter referred to as TN) is driven by a thin film transistor ('1'111T) array. FIG. 1 is a diagram showing its configuration. Light from a light source 1 is condensed by a condenser lens 2, and then passed through a polarizing plate 8.
It enters the TFTLCD4 through the TFTLCD4. All of the source light has a polarized component until it enters the polarizing plate 8 , but is limited to the polarized component of the transmission axis 5 by the polarizing plate 3 . TFTL
The polarization component of the light beam incident on the CD 4 is rotated for each pixel according to the displayed image. The process up to this point is the same as a normal TN liquid crystal display panel. In a normal TN liquid crystal display panel, polarization components are limited by a nearby analyzer.
A display image is generated, and in this embodiment, the light beam passes through a projection lens 6 and then enters a screen polarizing plate 7, which is an analyzer. The light beam modulated by the TFTLCD and given polarization characteristics is imaged on the light scattering plate 8 by the projection lens. Polarizing plate 7Fi transmission axis 5 close to light scattering plate 8
Since the beam is oriented as shown in FIG. 1, the amount of transmitted light is determined here. A screen consisting of a polarizing plate 7 and a light scattering plate 8 acts on incident light having polarization characteristics to form a projected image.

Another function is to absorb ambient light 9 and lower the black level. 10 indicates the ambient light reflected by the screen without being absorbed, and 23f'i indicates the ambient light transmitted through the screen. Further, 11 is an eye representing an observer. In this case, the direction of the transmission axis 5 of the polarizing plate 7 is determined by assuming that the ambient light has many horizontally polarized components. The light scattering plate used here is a milky-white translucent acrylic plate, but it would be even better if it was a light scattering plate of a devised flat lens type, such as the one used in the projection television device using the projection CRT described above. Effective. Note that the polarizing plate is a general one that is commercially available.

The configuration and drive of TE'TLCD are di
gcat (198B) P, 156 Nikkei Electronics A258 (1981) P, 164.

In this example, T'FTLCD is used as light pulp.
However, any electro-optic effect that can modulate polarization characteristics can be used instead.

Example 2 Example 2 is an example of a full-color projection display device using a reflective light valve. As in Example 1, a TE'TLCD was used as the light valve, the configuration of which is shown in FIG. In order to achieve full color, the light source light is separated into eight primary colors, red (R), green (G), and blue < B, by dichroic mirrors (blue mirror 12, red mirror 13), and the 'rFTLCD4 modulates the light of each color. It is done. A polarizing plate 8 is placed between the reflecting mirror 14 and the TFTLCD,
The transmission axis is adjusted to match the LCD panel. The light reflected by the mirror 14 and modulated by the TIFTLCD is combined by the dichroic mirror, passes through the projection lens 6, and forms an image on the screen. The screen is composed of a polarizing plate 7 and a light scattering plate 8. Further, reference numeral 15 denotes a mirror for bending the light from the light source, and is positioned so as not to emit the output light from visitors.

In the case of the second embodiment, as in the first embodiment, the screen functions to form a projected image and absorb ambient light, thereby enabling display with high contrast.

Further, when the optical system has a complicated optical system as shown in FIG. 2, flare such as scattering is likely to occur. However, if the screen has polarizing properties, the polarizing plate 7 can cut out most of the flare that is harmful to the contrast.

Regarding the full-color display button, there are not only the method shown in Fig. 2, but also a method of installing a color filter for each pixel, a method of projecting the three primary colors onto a screen separately, etc., but the present invention has a screen with polarization characteristics. Since the contrast between each color can be increased, it is possible to obtain a vivid display with high color purity.

Example 8 Example 8 is a case where a projection type CRT is used as the image forming means. FIG. 8 shows a cross-sectional view of a system using a transmission screen. The light beam emitted from the projection type c RT 16 passes through the projection lens 6, is reflected by the mirror 14, and forms an image on the screen 17. Ambient light 9 is absorbed by the screen 17 but has a reflected component 10.

Transparent components remain, which causes a decrease in contrast. Using a screen with polarizing properties according to the invention, selective absorption of ambient light 9 takes place. By matching the polarization characteristics to the polarization characteristics of ambient light, it absorbs ambient light more effectively than one that performs isotropic absorption.

In addition, projection type CR, which is an image forming means that does not have polarization characteristics,
A polarizer may be installed at T to extrinsically impart polarization characteristics.

Example 4 Example 4 is an example of an integrated transparent screen.

A polarizing plate 18 dyed with iodine and uniaxially stretched, the cross section of which is shown in FIG. 4, is embossed with a roller 19 having a scattering surface shape so that the surface scatters light. The projection display device can be configured in the same manner as in Examples 1 to 8.

Example 5 Example 5 is a case where a reflective screen is used. Fifth
The figure shows an example of the configuration. Since the projection device can be the same as in Examples 1 to 8, the screen will be explained. A cross section of the reflective screen 21 is shown in FIG. One reflective layer, on which the polarizing plate 7 is closely attached on the reflective layer ρ, must not disturb polarized light and must have diffusive properties.

These are contradictory demands and a compromise must be found.5
Aluminum foil with a roughened surface is suitable for this purpose. In addition, it has a concave mirror-like curve in consideration of directivity. Since the polarizing plate 7 on the front surface selectively absorbs ambient light, it is possible to lower the black level and increase the contrast, similar to a transmissive screen.

〔Effect of the invention〕

As described above, according to the present invention, contrast is improved by a screen that selectively absorbs ambient light. Furthermore, since projection light having one polarization characteristic is selected for display, harmful scattering components and flare can be reduced, and a projection display device with better contrast can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a main configuration diagram of the present invention, in which a TFTLCD is used as an image forming means. FIG. 2 is a block diagram of a pull-color display device using a TFTLCD according to the present invention. FIG. 8 is a sectional view of a display device using the projection type CRT of the present invention. FIG. 4 is a diagram simply showing the cross section and manufacturing method of the transmission screen of the present invention. FIG. 5 is a cross-sectional view of the reflective screen of the present invention and a projection system using the same. 4-,,TF'TLCD 6・Φ・Projection lens 7e...Polarizing plate 8...Light scattering plate 16...Projection type CRT 17...Polarizing transmission screen 18...Integrated transmission screen 21 ...Polarized reflective screen Figure 1 Figure 4 Figure 5 Procedural amendment (voluntary) 1985 9 3E1 1. Display of the incident 1988 Patent Application No. 157012 2. Projection display of the title of the invention Applicant 3: Relationship with the case of the person making the amendment Applicant: 411 Suwa Seikosha Co., Ltd., 2-4-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo (236). Ka Asui Tsuneya Nakamura 2-6-21-5, Kyobashi, Chuo-ku, Tokyo 104 Number of inventions increased by amendment 6, Procedure amendment subject to amendment (method) % formula % "Polarized light component of surrounding table" Correct it to "polarized component of ambient light". 2. Specification, page 5, lines 5-6 ``This is an example used. Figure 1 is a diagram of its configuration.Optics 1
``This is an example of a rear projection display device using the light from''. Figure 1 shows its configuration. 1 is a light source, 2 is a condenser lens for condensing light, a projection lens 6, Together with the screen, it forms a projection optical system. 4 is a TFTLC!D, and its configuration and drive are the same as those described in J. Aigest (1983) p. 156 and Aperture Electronics A258 (1981) p. 164. 3 is a polarizing plate, and in the example shown in FIG. It consists of a scattering plate 8. The transmission axis 5 of the polarizing plate 7 is set to transmit the least polarized component of the ambient light 9, which in this example is oriented vertically. To explain, the light from light source 1 is corrected to ``. 5. On page 5, line 9 of the specification, the phrase "all have polarized light components," should be amended to "all polarized light components, but." 46 Specification, page 6, lines 17 to 19 “TFT
The configuration regarding LOD is equivalent. ” will be deleted. 5. In the specification, page 7, line 1, ``We have adopted an electric lamp that can adjust the polarization characteristics.'' ”. & Specification, page 8, lines 1 to 2 [Formation of projected image, ~ is possible. '' should be corrected to ``It functions to form a projected image and absorb it.'' Z Specification, page 9, lines 11-12, ``Example 4 shows a cross section.'' has been replaced with ``A transmission screen integrated with a polarizing plate can also be used as a projection type display device. The cross-section of the integrated transmission screen is shown.'' a. Specification, page 10, lines 12 to 18, "[Effects of the invention] ~ can be obtained." is replaced with "[Effects of the invention] As described above, according to the present invention, ambient light can be selected. By using a screen that has polarization properties that absorb light, it is possible to prevent contrast degradation due to scattering of ambient light, flare, etc. Furthermore, if the light emitted from the light pulp has polarization properties, the screen itself can form an image (light The screen can also cut unnecessary scattering flare from the optical system and selectively display only the image information light.As a result, the black level can be lowered and images with excellent contrast can be displayed. It is possible to obtain a projection type display device.'' 9. Claims m- are separate from the claims. that's all

Claims (7)

[Claims] (1) A projection type display device that performs display by forming an image on an image screen, wherein the screen on which the light emitted from the image forming means forms an image has a polarizing property. (2) The projection type display device according to claim 1, wherein the image forming means is a light valve using an electro-optic effect. (3) The projection type display device according to claim 1, wherein the image forming means is a projection type CRT. (4) The projection type display device according to claim 1, wherein the screen comprises a light scattering plate in close contact with or close to a polarizing plate that transmits linearly polarized light. (5) The projection type display device according to claim 1, wherein the screen is a linearly polarizing plate having light scattering properties. (6) The projection type display device according to claim 1, wherein the screen comprises a linear polarizing plate and a reflective film. (7) The projection type display device according to claim 1, wherein the screen has a polarization characteristic in a direction that absorbs the wired polarization component that is most distributed in the surrounding light.