JPH1124171A - Screen for liquid crystal projection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an external light reflection component having an adverse effect on contrast and to improve the contrast under external light further by constituting a screen so that the external light reflection component can be absorbed. SOLUTION: A 1/4 wavelength plate 35 having polarizing characteristic to rotate the axis of polarization of the incident light of the external light reflection component reflected by a lenticular lens 31 by 45 deg. is provided on the surface of a polarizing plate 34 on the lens 31 side. In such a case, the place 34 has an arrangement relationship to be aligned with the axis of polarization rotated by the plate 35. Therefore, the external light reflection component from the lens 31 is a component straight advancing to the plate 34 by 90 deg. after it is made incident on the plate 35 again and the axis of polarization is rotated by 45 deg., whereby most of the external light reflection component is absorbed by the plate 34 and attenuated. Thus, the contrast under the external light is greatly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projection screen used for a projection type display such as a rear projection type liquid crystal projection television.

[0002]

2. Description of the Related Art In recent years, with the demand for a small-sized and light-weight display device having a large screen, a projection type liquid crystal image display device using a liquid crystal panel has attracted attention. By using a liquid crystal panel, a projection-type liquid crystal image display device can be smaller and lighter than a conventional projection-type image display device using a CRT, and can easily realize a large-screen display. . In addition, there is an advantage that troublesome convergence adjustment is not required and there is no influence of geomagnetism. For these reasons,
2. Description of the Related Art At present, a projection type liquid crystal image display device employing a liquid crystal is rapidly spreading.

[0003] Such a projection type liquid crystal image display device is generally called a projection type display. For example, a front projection type liquid crystal projector for projecting an image displayed on a liquid crystal panel and projecting it on a screen, There is a rear projection type liquid crystal projection television which mounts a projector in a main body and projects an image on a screen such as a screen using an optical system mirror. In particular, a rear-type system such as a liquid crystal projection television can be made thinner than a rear-projection type system using a CRT, so that future demand is expected.

In general, a rear projection type liquid crystal image display device is
Compared with a front projection type image display device, it is possible to view an image displayed on a screen such as a screen even in a slightly bright room, but in order to make the projected image brighter and more recognizable, more It is desirable to further improve the brightness. Usually, to improve brightness,
As is well known, it is necessary to improve not only the luminance of the light source but also the light collection efficiency and the light use efficiency of the optical system device and the screen device in the apparatus.

FIG. 3 is an overall configuration diagram showing an example of the above-mentioned rear projection type liquid crystal projection television.
3A is a side view, and FIG. 3B is a front view. FIG.
For the optical system shown therein, only three light beams are shown for simplification.

As shown in FIG. 3A, a conventional rear projection type liquid crystal projection television 1 has a liquid crystal projector 2 disposed below the device 1.

This liquid crystal projector 2 has a liquid crystal panel 5
A light source lamp 3 for irradiating and projecting an image formed on
A reflector 4 for controlling and reflecting the light emitted from the light source lamp 3 to substantially parallel light; and a liquid crystal panel 5 (also referred to as a liquid crystal light valve) for forming an image based on the input source and transmitting an image formed by the light irradiated by the reflector 4. Say)
And a phase difference plate 6 for limiting the angle of the image light transmitted through the liquid crystal panel 5, and a projection lens 7 for enlarging and projecting the image light from the liquid crystal panel 5 transmitted through the phase difference plate 6. I have.

An optical system mirror 8 is provided on the back of the liquid crystal projection television 1. The optical system mirror 8 reflects the projected image light projected by the projection lens 7 at an optimum angle, and a screen 9 Irradiate on the surface of.

The screen 9 magnifies and forms the irradiation light projected by the projection lens 7 and reflected by the optical system mirror 8.

Normally, in the liquid crystal projection television 1 having the above configuration, the light emitted from the light source lamp 3 is controlled and reflected by the reflector 4 into substantially parallel light, and the liquid crystal panel 5 is irradiated. Thereafter, the angle of the image light formed by the liquid crystal panel 5 is limited by the phase difference plate 6, that is, after unnecessary light is removed, the image light is enlarged and projected by the projection lens 7.
The projected image light is reflected by the optical system mirror 8 and then enlarged and formed on the screen 9. Therefore, by operating as described above, it is possible to display an image based on the image source on the screen 9, and the viewer can display the image displayed on the screen 9 from the near side in FIG. You can watch.

By the way, in consideration of the improvement of the brightness of the displayed image, a screen 9 of a liquid crystal projection television (also referred to as a liquid crystal projection screen) is considered in order to improve the light collecting efficiency and the light use efficiency. Has been made. FIG. 4 shows a specific configuration example of the screen 9 used in a general liquid crystal projection television.

As shown in FIG. 4, the screen 9 comprises a lenticular lens 10 for widening the viewing angle and a Fresnel lens 11 for improving the peripheral light quantity. Further, on the front side of the lenticular lens 10, a polarizing plate 1 with an adhesive having a thickness of 120 μm is formed on the back side.
The acrylic plate 13 to which 2 is attached is stuck. In this case, the polarizing plate 12 is attached to the acrylic plate 13 so as to match the polarization axis of the projection light from the projection lens 7.

With such a configuration, the projection light is transmitted through the polarizing plate 12 (screen 9) by the polarizing plate 12 that matches the polarization axis of the projection light from the projection lens 7, and is incident from the acrylic plate 13. Light (random light), that is, external light that is so-called scattered light, is also shielded by the polarizing plate 12 and can be reduced by half, and as a result, the contrast (brightness) under external light can be improved.

However, under the current situation where the size of the screen is increased and the size of the liquid crystal projector including the liquid crystal panel is reduced, higher image quality and higher luminance are desired. For this reason, how to increase the brightness of the screen is also being studied.

As described above, external light from the outside of the screen may greatly affect the contrast. The external light can be reflected by the deflecting plate 12 so as to reduce the influence on the screen by half. However, if it is more detailed, the external light is reflected on the surface of the acrylic plate 12 adhered to the deflecting plate 12. The light component reflected as described above and the light component transmitted through the deflecting plate 12 and reflected on the surface of the lenticular lens 10 and transmitted through the deflecting plate 12 again.

Therefore, the conventional screen 9 has a problem that the outward reflection component transmitted through the deflecting plate 12 cannot be reduced. In order to further improve the contrast in the outward direction, there is a problem. There is a need for a solution to this problem.

[0017]

As described above, in the conventional liquid crystal projection screen, one of the external light components that affect the contrast is determined by the surface of the acrylic plate attached to the deflection plate. Although it can be reduced by reflection, the other light component is transmitted through the deflecting plate, reflected on the surface of the lenticular lens, and transmitted through the deflecting plate again, so that it cannot be reduced sufficiently. However, there is a problem that the contrast under external light cannot be effectively improved.

In view of the above, the present invention has been made in view of the above problems, and is configured to be able to absorb an external light reflection component that has an adverse effect on contrast, thereby reducing the external light reflection component to reduce the external light reflection component. It is an object of the present invention to provide a liquid crystal projection screen capable of further improving contrast.

[0019]

According to a first aspect of the present invention, there is provided a liquid crystal projection screen for irradiating a liquid crystal panel with light from a light source and projecting image light formed by the liquid crystal panel through a projection lens. In a liquid crystal projector configured to project and display on a screen, the screen is configured by combining a lenticular lens and a Fresnel lens, and a screen member on which light from the projection lens is projected to a back surface, and a front side of the screen member. And a polarizing plate attached to a surface of the polarizing plate on the lenticular lens side, which has a polarization characteristic of rotating the polarization axis of the external light reflection component reflected by the lenticular lens by 45 °, and has the polarization axis Is coincident with the transmission axis of the polarizing plate.
It is characterized by comprising a four-wavelength plate and an acrylic plate attached to the surface of the polarizing plate.

According to the first aspect of the present invention, on the lenticular lens side surface of the polarizing plate, there is provided a polarization characteristic for rotating the polarization axis of the incident light of the external light reflection component reflected by this lenticular lens by 45 °. A quarter-wave plate is provided. In this case, the polarizer plate is configured to match this polarization axis. For this reason, since the external light reflection component reflected by the lenticular lens is incident on the １ ／ wavelength plate again, the polarization axis is rotated by 45 °, and becomes a component orthogonal to the polarizing plate by 90 °. Most of this external light component is absorbed and attenuated by the polarizing plate.
Thereby, most of the external light component reflected on the surface of the lenticular lens can be attenuated, and as a result, the contrast under external light can be further improved.

[0021] In the liquid crystal projection screen according to the present invention as set forth in claim 2, the quarter-wave plate and the polarizing plate are adhered by laminating. The plate has a characteristic of transmitting the projection light from the projection lens and conversely reducing the external light reflection component of the lenticular lens using the polarization characteristic of the quarter-wave plate. Things.

According to a second aspect of the present invention, the １ ／
Since the wave plate and the polarizing plate are attached by lamination, the workability can be facilitated. In addition, the polarizing plate,
Since it has the property of transmitting the projection light from the projection lens and conversely reducing the external light reflection component by the lenticular lens using the polarization characteristics of the １ ／ wavelength plate, the same as in the above invention It is possible to improve contrast under external light.

[0023]

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

FIG. 1 shows an embodiment of a liquid crystal projection screen according to the present invention, and is an overall configuration diagram showing a configuration example of a rear projection type liquid crystal projection television equipped with the screen. Is a side view, FIG.
(B) is a front view. In FIG. 1, the same components as those of the apparatus shown in FIG. 3 are denoted by the same reference numerals, and for the optical system shown in FIG. It is shown.

As shown in FIG. 1A, in a rear projection type liquid crystal projection television 20 equipped with a liquid crystal projection screen 30 of the present invention, a liquid crystal projector 22 is provided at a lower part in the main body of the device 20. I have.

The liquid crystal projector 22 includes a light source lamp 3 for irradiating and projecting an image formed on the liquid crystal panel 5.
A reflector 4 for controlling and reflecting light emitted from the light source lamp 3 into substantially parallel light; and a liquid crystal panel 5 (liquid crystal light) for forming an image based on the input source and transmitting an image formed by the light irradiated by the reflector 4. And a projection lens 7 for enlarging and projecting an image transmitted from the liquid crystal panel 5.

An optical system mirror 8 is provided on the rear surface of the liquid crystal projection television 20. The optical system mirror 8 reflects the projection image projected by the projection lens 7 at an optimum angle to the present invention. Irradiation is performed on the surface of the liquid crystal projection screen 30. Screen 30
Forms an enlarged image of the irradiation light projected by the projection lens 6 and reflected by the optical system mirror 8.

The liquid crystal projection television 2 having the above configuration
At 0, the light emitted from the light source lamp 3 is controlled and reflected by the reflector 4 into substantially parallel light to irradiate the liquid crystal panel 5, and then the image formed on the liquid crystal panel 5 by the projection lens 7 is enlarged and formed on the screen 30. Image. Therefore, by such an operation, it is possible to display an image based on the image source on the screen 30, and the viewer can view the image displayed on the screen 30 from the near side in FIG. can do.

By the way, in the liquid crystal projection screen 30 mounted on the liquid crystal projection television 20, unlike the conventional technique (see FIG. 3), the external light reflection component is further reduced so that the contrast (luminance) under the external light is reduced. Has been made to further improve The configuration of such a liquid crystal projection screen of the present invention will be described with reference to FIG.

FIG. 2 is an exploded perspective view showing the structure of the liquid crystal projection screen 30 according to the present invention mounted on the liquid crystal projection television shown in FIG.

As shown in FIG. 2, the liquid crystal projection screen 30 of the present invention has a lenticular lens 31 for widening the viewing angle, a Fresnel lens 32 for improving the peripheral light amount, and a screen damage from outside the screen. Acrylic plate 33 having a function of protecting a screen for preventing the image, a polarizing plate 34 having predetermined polarization characteristics provided on the back surface of the acrylic plate 33, and further provided on the back surface of the polarizing plate 34 And a quarter-wave plate (also referred to as a phase difference plate) 35 provided to reduce the external light reflection component.

The quarter-wave plate 35 is provided by performing lamination (lamination processing) on the back surface of the polarizing plate 34. The quarter-wave plate 34 has a polarization axis of 45 °. It has optical system characteristics for rotating.

The arrangement relationship of the optical system between the polarizing plate 34 and the 波長 wavelength plate 35 is such that the polarization axis rotated by 45 ° by the 波長 wavelength plate 34 and the polarization axis of the polarizing plate 34 The １ ／ wavelength plate 35 is adhered (laminated) in this arrangement to form an improved polarizing plate 34.

On the surface of the polarizing plate 34 opposite to the surface on which the 1/4 wavelength plate 35 is adhered, the acrylic plate 33 for preventing the screen is laminated and adhered as described above. It has become. That is, this acrylic plate 33
Has a function as a protection plate for protecting the screen of the screen 30, and by providing the acrylic plate 34, it is possible to prevent the screen 30 from being damaged by the viewer shown in FIG. is there.

In the screen 30 according to this embodiment, the lenticular lens 31 and the Fresnel lens 32 are laminated and adhered to each other to form a screen member, and the lenticular lens 3 of the screen member is formed.
The polarizing plate plate 34 and the acrylic plate 33 are laminated and adhered to the screen member so that the quarter-wave plate 35 is arranged on one surface side, so that the liquid crystal projection screen 30 in this embodiment is provided. And

Therefore, according to the above configuration, the 波長 wavelength plate 35 is disposed on the front side of the lenticular lens 35, and then the polarizing plate 34 and the acrylic plate 33 are disposed as described above. Because it is
The external light component reflected by the lenticular lens 35 after passing through the acrylic plate 33 and the polarizing plate 34 is absorbed by the 波長 wavelength plate 35. As a result, the external light reflected component is greatly reduced, and the contrast is reduced. Can be improved as compared with the related art.

In the laminating operation of the quarter-wave plate 35 to the polarizing plate 34, the quarter-wave plate 35 is laminated so as to be finished with a thickness dimension capable of securing the optical system characteristics in the present embodiment. This processing operation can be easily performed without complexity.

Next, the operation of the liquid crystal projection screen 30 configured as described above will be described in detail.

Now, the image light formed on the liquid crystal panel 5 is enlarged and projected from the projection lens 7 of the liquid crystal projector 22,
It is assumed that the light is irradiated onto the surface of the liquid crystal projection screen 30 via the optical system mirror 8. At this time, the projection light is incident on the quarter-wave plate 35 via the Fresnel lens 32 and the lenticular lens 31, and then the polarization axis is rotated by 45 ° by the quarter-wave plate 35 and is incident on the polarizing plate 34. I do.

Then, since the polarization axis of the polarizing plate 34 coincides with the 波長 wavelength plate 35, the incident light passes through the polarizing plate 34 at a small attenuation rate, and the surface of the acrylic plate 33 Illuminated on the screen 30
The image light is focused on the image. That is, the projection image light to be displayed on a normal screen can be displayed normally without reducing the contrast.

On the other hand, as shown in FIG.
External light may be incident from the viewer side of the camera. In this case, the external light whose incident polarization axis is random light is reflected by the surface of the acrylic plate 33 or transmitted through the acrylic plate 33.

Thereafter, the external light component transmitted through the acrylic plate 33 is incident on the polarizing plate 34, and the external light component orthogonal to the polarization axis of the polarizing plate 34 is absorbed by the polarizing plate 34. . However, the external light component whose polarization axis is coincident passes through the polarizer plate 34, and thereafter, the external light component becomes 1
The light is reflected by the surface of the lenticular lens 31 via the quarter-wave plate 35 and enters the quarter-wave plate 35 again.

Then, the external light component incident on the quarter-wave plate 35 has a polarization axis of 45
By rotating by 90 °, the component becomes a component orthogonal to the polarizing plate 34 at 90 °, and is absorbed by the polarizing plate 34. This allows
Of the external light components, most of the external light components transmitted through the polarizing plate 34 and reflected on the surface of the lenticular lens 31 can be attenuated. As a result, the contrast under external light is more effective than before. Can be improved.

For example, it is assumed that the external light reflection reduction effect in the screen device of the embodiment is calculated. Then, the component of the external light component transmitted through the polarizing plate 34 is:
If the component reflected on the surface of the lenticular lens 31 is 10%, it is possible to attenuate most of the external light reflected component of about 5% of the external light component. The surface reflection of the acrylic plate 33 is about 4
% Of the external light component, so that the total external light reflectance of 9% can be improved to only 4% of the acrylic plate surface reflectance. That is, the external light reflection component can be reduced to approximately half.

Therefore, according to the present embodiment, it is impossible for the conventional screen (see FIG. 4) to reduce the external light component transmitted through the polarizing plate and reflected by the lenticular lens among the external light reflected components. It was possible, but 1/4
By providing the wavelength plate 34 on the lenticular lens side surface of the polarizing plate, it becomes possible to absorb and attenuate most of the reflection component. As a result, approximately half of the external light reflection component can be reduced, and the effect that the contrast under external light can be further improved can be obtained.

Also, due to the structure of the optical system, the retardation plate 6 provided in the conventional liquid crystal projector 2 (see FIG. 3)
Can be eliminated, so that there is also an effect that it is possible to contribute to cost reduction by reducing the number of parts.

[0047]

As described above, according to the present invention,
By arranging a quarter-wave plate 35 on the back surface of the polarizing plate 34 and arranging the same, most of the external light component transmitted through the polarizing plate and reflected on the surface of the lenticular lens is absorbed and attenuated. And as a result,
It is possible to reduce half of the external light reflection component. Thereby, an effect is obtained in which the contrast under external light can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a liquid crystal projection screen according to an embodiment of the present invention and illustrating an overall configuration of a liquid crystal projection television.

FIG. 2 is an exploded perspective view showing a configuration of a liquid crystal projection screen of the present invention.

FIG. 3 is a configuration diagram showing the entire configuration of a conventional liquid crystal projection television.

FIG. 4 is an exploded configuration perspective view showing the configuration of a conventional liquid crystal projection screen.

[Explanation of symbols]

20 ... rear projection type liquid crystal projection television, 22 ...
Liquid crystal projector, 3 ... light source lamp, 4 ... reflector,
5 liquid crystal panel, 7 projection lens, 8 optical system mirror,
Reference numeral 30 denotes a liquid crystal projection screen, 31 denotes a lenticular lens, 32 denotes a Fresnel lens, 33 denotes an acrylic plate, 34 denotes a polarizing plate, and 35 denotes a 波長 wavelength plate.

Claims (2)

[Claims] 1. A liquid crystal projector in which light from a light source is applied to a liquid crystal panel, and image light formed by the liquid crystal panel is projected and displayed on a screen via a projection lens, wherein the screen includes a lenticular lens and a Fresnel lens. A screen member on which light from the projection lens is projected on the back surface; a polarizing plate disposed on the front side of the screen member; and a surface of the polarizing plate plate on the lenticular lens side. A 波長 wavelength plate having a polarization characteristic of rotating the polarization axis of the external light reflection component reflected by the lenticular lens by 45 ° and having the polarization axis coincident with the transmission axis of the polarizing plate; An acrylic plate attached to the surface of the polarizing plate. Screen for projection. 2. The quarter-wave plate and the polarizing plate are attached by laminating, and the polarizing plate transmits projection light from the projection lens, 2. The liquid crystal projection screen according to claim 1, wherein the screen has a characteristic of reducing an external light reflection component of the lenticular lens using polarization characteristics of the quarter-wave plate.