JP2007304399A - Rear projection screen and rear projection type display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rear projection screen which is superior in optical performance and can satisfactorily suppress glittering. <P>SOLUTION: The rear projection screen 10 comprises a lenticular lens sheet 12, disposed at the incident side of making light incident thereto and diffuses the incident light in the horizontal direction; and a diffraction diffusion sheet 13, disposed on the emission side of emitting light from the lenticular lens sheet 12 and diffuses the incident light in the vertical direction by diffraction effect, wherein the lenticular lens sheet 12 has lenses 122, disposed on incident side and diffuse incident light in the horizontal direction and a light-shielding pattern 123 disposed on the light-emitting surface side, and the diffraction diffusion sheet 13 diffuses incident light so that vertical viewing angle α (1/2 angle) becomes 7° to 22°. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rear projection type screen and a rear projection type display device.

  Conventionally, in a rear projection type display device, an optical image from a cathode ray tube (CRT), a liquid crystal panel, or the like is projected from a rear surface of a rear projection type screen using a projection lens, thereby projecting a large screen. An image is displayed. This rear projection screen generally has a Fresnel lens sheet and a lenticular lens sheet. The Fresnel lens sheet has a function of condensing light rays in the direction of the observer, and the lenticular lens sheet has a function of diffusing light rays from the Fresnel lens sheet in the horizontal direction and the vertical direction. The Fresnel lens sheet narrows the image light so as to fall within a certain angle range, and the lenticular lens sheet widens the image light transmitted through the Fresnel lens sheet to an appropriate angle range.

  In the conventional rear projection type screen, a front plate is often provided in addition to the Fresnel lens sheet and the lenticular lens sheet. The front plate protects the front surface of the rear projection type screen and prevents dust from adhering to the lens sheet. The front plate functions as a light diffusion sheet by mixing a light diffusion material. In addition, there is a screen in which a front plate and a lenticular lens sheet are bonded to form an integral structure.

  Thus, glare (scintillation) is likely to occur due to the light diffusing material mixed in the front plate. In particular, in a small rear projection display device such as an MD display device (MD-PTV; Micro Display Projection Television), glare caused by the light diffusing material becomes significant. An example of technology for suppressing glare in such a small rear projection display device has been proposed in Patent Document 1 or the like, but it is difficult to sufficiently reduce glare even with these technologies.

On the other hand, in the rear projection display device, light transmittance is regarded as important as well as light diffusibility. For example, Patent Documents 2 to 4 disclose a screen using a light control film having an angle dependency in haze in order to achieve both light diffusibility and light transmittance. Even if the light control films disclosed in Patent Documents 2 to 4 are used, it is difficult to obtain sufficient optical performance such as viewing angle characteristics and external light contrast required for the screen.
JP-A-8-313865 Japanese Patent Laid-Open No. 3-127042 Japanese Patent Laid-Open No. 4-0777728 JP 2005-316354 A

As described above, the conventional rear pitcher type screen has a problem that it is difficult to sufficiently secure optical performance and sufficiently suppress glare.
The present invention has been made in view of such problems, and an object thereof is to provide a rear projection type screen and a rear projection type display device that are excellent in optical performance and can sufficiently suppress glare.

  The rear projection screen according to the present invention is disposed on an incident side where light enters, and is disposed on an exit side where light is emitted from the lenticular lens sheet, and a lenticular lens sheet that diffuses incident light in the horizontal direction. A rear projection type screen having a diffraction diffusion sheet for diffusing incident light in a vertical direction by a diffraction effect, wherein the lenticular lens sheet is disposed on the incident side, and a lens array for diffusing incident light in a horizontal direction; The diffraction diffusion sheet diffuses incident light so that the vertical viewing angle α (1/2 angle) is 7 ° or more and 22 ° or less. With such a configuration, the optical performance is excellent and glare can be sufficiently suppressed.

  Further, the diffraction diffusion sheet has a vertical viewing angle β (1/3 angle) of 1.2 times or more and 1.4 times or less of the vertical viewing angle α (1/2 angle). Thereby, it is possible to prevent the brightness difference from being noticeable.

  Suitably, the said vertical viewing angle (beta) (1/3 angle | corner) can be 10 degrees or more and 28 degrees or less. Thereby, an optical characteristic can be improved more.

  Furthermore, in the diffraction diffusion sheet, the vertical viewing angle γ (1/10 angle) is not less than 2.0 times and not more than 2.5 times the vertical viewing angle α (1/2 angle). Thereby, it is possible to prevent the brightness difference from being noticeable.

  Suitably, the said vertical viewing angle (gamma) (1/10 angle | corner) can be made into 17 degrees or more and 40 degrees or less. Thereby, it is possible to prevent the brightness difference from being noticeable.

  The rear projection screen according to the present invention includes a Fresnel lens sheet that narrows the projection light within a certain angle range.

  A rear projection display device according to the present invention includes the lenticular lens sheet and the diffraction diffusion sheet according to any one of claims 1 to 5. With such a configuration, the optical performance is excellent and glare can be sufficiently suppressed.

  According to the present invention, it is possible to provide a rear projection screen and a rear projection display device that are excellent in optical performance and can sufficiently suppress glare.

The rear projection screen according to the present invention diffuses light using a diffraction sheet, and a rear projection display device is configured by combining a projection lens such as a CRT or a liquid crystal panel with the screen.
The best mode for carrying out the present invention will be described below with reference to the drawings.
Embodiment 1 of the Invention
First, a rear projection screen according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic perspective view showing one configuration example of a rear projection screen according to the present invention. FIG. 2 is a schematic cross-sectional view showing a configuration example of a rear projection type screen according to the present invention.

  As shown in FIG. 1, the rear projection screen 10 includes a Fresnel lens sheet 11, a lenticular lens sheet 12, and a diffraction diffusion sheet 13. A Fresnel lens sheet 11, a lenticular lens sheet 12, and a diffraction diffusion sheet 13 are sequentially arranged from the image light projection side to the image light emission side. In other words, these members are arranged in order from the back surface to the front surface of the rear projection screen 10.

  The Fresnel lens sheet 11 has, for example, a sheet shape and is made of plastic. The Fresnel lens 112 has a sawtooth shape with a sharp tip, and is disposed on one surface of the base material 111 of the Fresnel lens sheet 11. Further, the Fresnel lens 112 is uneven toward the image light emitting side.

  The lenticular lens sheet 12 is a sheet for forming a horizontal viewing angle (horizontal viewing angle) of the screen. The lenticular lens sheet 12 has, for example, a sheet shape and is made of plastic. The lenticular lens 122 has a convex shape with a C-shaped cross section, and is disposed on one side of the base material 121 of the lenticular lens sheet 12. Further, the lenticular lens 122 is uneven toward the image light projection side. Accordingly, the lenticular lens 122 of the lenticular lens sheet 12 faces the Fresnel lens 112 of the Fresnel lens sheet 11. In other words, the two lens sheets 11 and 12 are overlapped with the lenses 112 and 122 facing each other.

  The light shielding pattern 123 that blocks light is arranged in parallel on a flat surface opposite to the lens surface of the lenticular lens 122, and is formed in a non-condensing region where image light does not pass. The lenticular lens sheet 12 may be formed by extrusion molding using an acrylic or styrene resin or the like, and the lens 122 may be molded from an ultraviolet curable resin or the like on a base sheet such as a PET film. . Various functional layers such as AR, AS, and AG may be formed on the front surface of the lenticular lens sheet 12.

The diffraction diffusion sheet 13 is a diffraction sheet that diffuses light by the diffraction effect of light. Specifically, the diffractive diffusion sheet 13 is a sheet for forming a vertical viewing angle (vertical diffusibility), whereas the lenticular lens sheet 12 constitutes a horizontal diffusion characteristic. Specifically, the vertical viewing angle α (1/2 angle) of the diffraction diffusion sheet 13 is preferably 7 ° to 22 °. When the vertical viewing angle α (1/2 angle) is smaller than 7 °, the vertical viewing angle becomes excessively narrow, so that the upper and lower ends become dark and the vertical viewing angle α (1/2 angle) is 22 °. If it is larger, the brightness in the front direction is insufficient.
The vertical viewing angle β (1/3 angle) and the vertical viewing angle γ (1/10 angle) are in a specific range with respect to the vertical viewing angle α (1/2 angle) so that hot bands and luminance steps are not noticeable. It is preferable to be within. Preferably, β = α × (1.2 to 1.4) and γ = α × (2.0 to 2.5), but from the same viewpoint as the vertical viewing angle α (1/2 angle). The vertical viewing angle β (1/3 angle) is more preferably 10 ° to 28 °, and the vertical viewing angle γ (1/10 angle) is more preferably 17 ° to 40 °.

  Specifically, as shown in FIG. 2, the diffraction diffusion sheet 13 has surface irregularities 130, and the surface irregularities 130 generate a diffraction effect. The surface irregularities 130 are arranged on the surface on the side from which the light incident on the diffraction diffusion sheet 13 is emitted, but the surface irregularities 130 may be arranged on the incident side surface. The surface unevenness 130 can be formed in a stripe shape extending in the horizontal direction, but the pitch of each unevenness is appropriately designed. Furthermore, the surface irregularities 130 may be formed in a lattice shape extending in the vertical direction and the horizontal direction. In this case, the diffraction diffusion sheet 13 is not only in the vertical direction but also in the horizontal direction along with the lenticular lens sheet 12. Contributes to properties. Further, the surface irregularities 130 may have a shape inclined with respect to the horizontal direction and the vertical direction of the screen.

Such a diffraction diffusion sheet 130 can be formed as follows, for example. FIG. 3 shows an example of the manufacturing process of the diffraction diffusion sheet 13. Note that FIG. 3 shows a process of forming a part of the surface irregularities 130 shown in FIG. 2 so that this manufacturing process can be easily understood.
As shown in FIG. 3A, a resist layer 32 is formed on the substrate 31. Examples of the forming method include a spin coat method, a dipping method, a roll method, and a dry film resist bonding. The resist used as the resist layer 32 may be either a positive resist or a negative resist.

  As shown in FIG. 3B, a mask 33 such as an emulsion mask or a chrome mask is formed on the range layer 32. At this time, the alignment of the mask 33 is performed in order to align the second resist layer 34 and the resist layer 32 formed in a later process. After alignment of the mask 33, light such as ultraviolet rays or laser beams is irradiated, and the resist layer 32 is exposed using the mask 33. As shown in FIG. 3C, a resist pattern 34 is formed by developing using a predetermined developer corresponding to the mask 33 used for exposure.

  As shown in FIG. 3D, a conductive film 35 is formed along the obtained resist pattern 34 using gold, silver, platinum, copper, aluminum or the like. Examples of the method for forming the conductive film 35 include a vacuum deposition method and a sputtering method. As shown in FIG. 3E, along the surface of the resist pattern 34 on which the conductive film 35 is formed, a metal such as nickel, nickel-cobalt alloy, copper, or gold is deposited by plating to form a metal structure 36. Form. Examples of plating methods include electrolytic plating and electroless plating.

  As shown in FIG. 3F, the surface irregularities 130 of the diffraction diffusion sheet 13 are formed using the metal structure 36 as a mold. Examples of this forming method include injection molding, press molding, monomer cast molding, solvent cast molding, roll transfer method by extrusion molding, and the like. In particular, injection molding is preferable from the viewpoint of productivity and mold transferability. Further, when the surface unevenness 130 is formed by injection molding using the metal structure 36 having a predetermined dimension selected as a mold, the shape of the metal structure 36 can be reproduced on the surface unevenness 130 with a high transfer rate. As a method for confirming the transfer rate, there are methods using an optical microscope, a scanning electron microscope (SEM), a transmission electron microscope (TEM), and the like.

  As described above, the rear projection screen 10 according to the present invention forms a relatively wide horizontal viewing angle by diffusing light in the horizontal direction using the lenticular lens sheet 12. On the other hand, a relatively narrow vertical viewing angle is formed by diffusing light in the vertical direction using the diffraction diffusion sheet 13. By combining these sheets 12 and 13, the rear projection type screen 10 having an excellent balance between horizontal diffusibility and vertical diffusibility can be realized. In particular, a diffraction diffusion sheet 13 having a diffraction effect is used for light diffusion in the vertical direction without using a front plate mixed with a light diffusion material. Therefore, glare caused by the light diffusing material can be suppressed, and blurring of the image can be reduced.

  Furthermore, since the light shielding pattern 123 is provided on the lenticular lens sheet 12, the contrast performance can be improved. This effect is achieved by the light shielding pattern 123 shielding stray light or suppressing reflection of external light. Particularly, in the case of the combination of the present invention, the diffraction diffusion sheet 13 diffuses light by diffraction, so that backscattering is suppressed, and the diffraction diffusion sheet 13 is arranged on the observation side with respect to the light shielding pattern 123. However, it is not visually recognized as whitish. Therefore, in the rear projection screen 10 according to the present invention, the improvement in contrast performance is remarkable.

Embodiment 2 of the Invention
In the first embodiment, the case where the diffraction diffusion sheet 13 realizes the diffraction effect by the surface unevenness 130 has been described. However, the invention is not limited thereto, and the diffraction diffusion sheet 13 may be a sheet having the diffraction effect. As another example of the diffraction diffusion sheet 13, it is also possible to configure by stacking layers having different refractive indexes in multiple layers. Specifically, a sheet base material is formed by laminating layers having different refractive indexes. When surface irregularities are formed on this sheet substrate, the optical path length of light passing through the recessed portion is different from the optical path length of light passing through the top and side portions of the protruding portion. Thereby, the sheet base material has a diffraction effect, and the diffraction diffusion sheet 13 can be formed. In addition, the diffraction diffusion sheet 13 using a plurality of layers having different refractive indexes can be formed by a method disclosed in, for example, Patent Document 4.

  In this embodiment, the case where the light diffusing material is not mixed in the diffraction diffusion sheet 13 has been described. However, the present invention is not limited to this, and the light diffusing material may be mixed within a range where glare can be allowed. In this embodiment, the lenticular lens sheet 12 in which the lens 122 is provided on the light incident side is described. However, the lenticular lens sheet in which the light shielding pattern 123 is formed not only on the incident side but also on the output side. Any other lens may be provided between the light-shielding patterns 123 on the emission side.

It is a perspective schematic diagram which shows one structural example of the rear projection type screen which concerns on this invention. It is a cross-sectional schematic diagram which shows one structural example of the rear projection type | mold screen which concerns on this invention. It is a cross-sectional schematic diagram which shows an example of the manufacturing process of the diffraction diffusion sheet which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Back projection type screen 11 ... Fresnel lens sheet, 111 ... Base material, 112 ... Fresnel lens 12 ... Lenticular lens sheet, 121 ... Base material, 122 ... Lenticular lens,
123 ... Light-shielding pattern 13 ... Diffraction diffusion sheet 130 ... Surface irregularity 31 ... Substrate 32 ... Resist layer 33 ... Mask 34 ... Resist pattern
35 ... conductive film, 36 ... metal structure

Claims (7)

A lenticular lens sheet that is disposed on an incident side where light enters and diffuses incident light in a horizontal direction;
A rear projection type screen provided with a diffraction diffusion sheet that is disposed on an emission side where light is emitted from the lenticular lens sheet and diffuses incident light in a vertical direction by a diffraction effect,
The lenticular lens sheet is
A lens array disposed on the incident side and diffusing incident light in a horizontal direction;
A light-shielding pattern disposed on the exit surface side,
The diffraction diffusion sheet is a rear projection screen that diffuses incident light so that a vertical viewing angle α (1/2 angle) is 7 ° or more and 22 ° or less.   The diffraction diffusion sheet has a vertical viewing angle β (1/3 angle) of 1.2 times or more and 1.4 times or less of the vertical viewing angle α (1/2 angle). Rear projection screen.   The rear projection screen according to claim 2, wherein the vertical viewing angle β (1/3 angle) is 10 ° or more and 28 ° or less.   The diffraction diffusion sheet has a vertical viewing angle γ (1/10 angle) of 2.0 to 2.5 times the vertical viewing angle α (1/2 angle). The rear projection type screen according to any one of the above.   5. The rear projection type screen according to claim 4, wherein the vertical viewing angle [gamma] (1/10 angle) is not less than 17 [deg.] And not more than 40 [deg.].   The rear projection type screen according to claim 1, further comprising a Fresnel lens sheet that narrows the projection light within a range of a certain angle.   A rear projection display device comprising the lenticular lens sheet according to claim 1 and a diffraction diffusion sheet.

Images