JP3364288B2 - Rear projection screen - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection type screen comprising a Fresnel lens sheet and a lenticular lens sheet used as a screen of a projection television, a microfilm reader or the like. More specifically, the present invention relates to a rear-projection screen having a high luminance, suppressing a moiré phenomenon, and having a wide vertical viewing range. 2. Description of the Related Art In a rear projection type projection television or the like, a Fresnel lens is used so that the brightness and uniformity of the screen can be obtained and a certain bright image can be observed even when obliquely viewed. A screen composed of a sheet and a lenticular lens sheet is used. As such a rear projection type screen, as shown in FIG. 6, a transmission type screen in which a lens surface 3 of a Fresnel lens sheet 1 is arranged on a lenticular lens sheet 2 side is generally used, and its luminance is reduced. Various devices have been devised so that the image can be observed in a wide range as well as in a wide range. For example, in order to widen the viewing angle in the horizontal direction, Japanese Patent Application Laid-Open No. 57-165830, Japanese Patent Application Laid-Open No. 57-207235, and Japanese Patent Application
No. 33, Japanese Patent Application Laid-Open No. 58-176628, etc., a method in which part of incident light is totally reflected by a part of a vertical lenticular lens and emitted to the observation side. Has been achieved by On the other hand, in order to widen the viewing angle in the vertical direction, a method of mixing a diffusing agent into the Fresnel lens sheet 1 or the lenticular lens sheet 2 or forming a diffusing agent layer has been used. However, such diffusion by a diffusing agent does not diffuse light only in the vertical direction, but diffuses light in all directions.Thus, it is not possible to sufficiently expand the viewing angle in the vertical direction, which is very inefficient. At the same time, when the concentration of the diffusing agent is increased, there is a problem that the total light transmittance and the gain (G ₀ ) decrease, and the luminance and the contrast decrease. [0004] Accordingly, Japanese Patent Laid-Open No.
100723, JP-A-58-134627, JP-A-59-48744, JP-A-4-539
No. 94, etc., use a second lenticular lens sheet formed with a horizontal lenticular lens, or form a vertical lenticular lens on the observation side,
A method of using a lenticular lens sheet formed with a lateral lenticular lens on the light source side, a method of forming a lateral lenticular lens on the light source side of the Fresnel lens sheet, and the like have been proposed. A method of diffusing light in the vertical direction to widen the viewing angle in the vertical direction has been used. However, the conventional lateral lenticular lens has a relatively large pitch of several hundred μm, so that the moire phenomenon occurs due to the effect of the concentric lens pattern of the Fresnel lens and the curvature of the lenticular lens. Since the radius is larger than the pitch, there is a problem that the viewing angle is not sufficiently expanded in the vertical direction. Therefore, an object of the present invention is to provide a rear projection screen screen which has a high total light transmittance and a high gain (G ₀ ), suppresses the moiré phenomenon, and can enlarge the vertical viewing range. is there. [0006] In view of the above-mentioned problems of the prior art, the present inventors have made intensive studies on the shape of the lateral lenticular lens, and as a result, have set a specific pitch. The inventors have found that the moire phenomenon can be suppressed and the viewing angle in the vertical direction can be increased by setting the pitch and the radius of curvature in a specific relationship, and the present invention has been achieved. That is, the rear projection type screen of the present invention is a rear projection type screen including a Fresnel lens sheet on which a Fresnel lens is formed, and a lenticular lens sheet on which a vertical lenticular lens is formed on an emission surface side, On the incident surface side of the Fresnel lens sheet and / or lenticular lens sheet, the pitch is 1/10 to 4 of the pitch of the Fresnel lens.
/ 5, and lateral lenticular lens pitch 0.01~0.1mm the pitch (p) and the radius of curvature (r) satisfies the following equation (1) is formed, the Fresnel lens sheet
At least one of a sheet and a lenticular lens sheet.
On the other hand, 0.5 to 2% by weight of a light diffusing agent is mixed . [0007] As shown in FIG. 1 or FIG. 2, the rear projection type screen of the present invention has a Fresnel lens sheet 1 having a Fresnel lens 3 formed on the exit surface side, and a vertical lenticular lens 4 formed on the exit surface side. Lenticular lens sheet 2. The Fresnel lens sheet 1 of the present invention is made of a synthetic resin having good light transmittance such as an acrylic resin, a polycarbonate resin, an olefin resin, a styrene resin, a vinyl chloride resin or a mixed resin thereof, and is cast. Molding method, injection molding method,
It is manufactured by a commonly used method such as a heat press molding method or a method using an active energy ray-curable resin. Exit side of Fresnel lens sheet 1 (observation side)
Is formed with a circular Fresnel lens 3. The circular Fresnel lens 3 may be arranged so that its center coincides with the center of the screen, or may be arranged so that the center is shifted. [0008] Lenticular lens sheet 2 of the present invention
Is composed of a synthetic resin having good light transmission properties such as an acrylic resin, a polycarbonate resin, an olefin resin, a styrene resin, a vinyl chloride resin or a mixture thereof, and is formed by an extrusion molding method, a casting molding method, It is manufactured by a commonly used method such as an injection molding method or a hot press molding method. Vertical lenticular lens 4 formed on the exit surface side of lenticular lens sheet 2
The lens shape is not particularly limited, and a commonly used shape of a lenticular lens having an arc-shaped cross section such as a semicircular cross section or a semi-elliptical cross section can be used. As the lenticular lens 4 of the present invention, in order to widen the viewing angle in the horizontal direction, a part or all of the lens constituting the lenticular lens 4 is
The lens is designed in a lens shape such that a part of the incident light is once totally reflected and then emitted to the observation side, that is, as shown in FIG.
It is preferable to alternately arrange lenses 7 having
According to such a lenticular lens 4, the lens 7
The light incident on the total reflection surface 8 of the light incident on the surface is totally reflected and spreads right and left from the arc-shaped top surface 9, and the light incident on the circular lens 6 and the arc-shaped top surface 9 is The light is emitted in the same manner as a general circular lens with a cross section, and the emitted light is integrated so that the viewing angle can be widened over a considerably wide range from the center. The inclination of the total reflection surface 8 can be set according to the refractive index of the material to be used. For example, when methacrylic resin is used, the inclination may be about 70 to 80 degrees. When the lateral lenticular lens 5 is formed on the Fresnel lens sheet 1 as the lenticular lens sheet 2 of the present invention, a double-sided lenticular lens sheet having a vertical lenticular lens also formed on the incident surface side. Can also be used. further,
For the purpose of improving the contrast of the image, an external light absorbing layer can be formed in the light opaque portion of the lenticular lens 4. Further, in the present invention, when the pitch of the circular Fresnel lens 3 is set to 1 in order to suppress the moire phenomenon caused by the circular Fresnel lens 3 of the Fresnel lens sheet 1 and the vertical lenticular lens 4 of the lenticular lens sheet 2, The pitch of the lenticular lens 4 is N + 0.35 to 0.43, and N + 0.
It is preferable to be in the range of 55 to 0.73, 1 / (N + 0.35 to 0.43) or 1 / (N + 0.55 to 0.73). Here, N is a natural number of 1 to 12. In the rear projection screen of the present invention comprising the Fresnel lens sheet 1 and the lenticular lens sheet 2 as described above, at least one of the Fresnel lens sheet 1 and the lenticular lens sheet 2 has a lens on the incident surface side. pitch (p) is 1 / 10-4 / 5 of the pitch of the Fresnel lens _{(p f),}
It is characterized in that a lateral lenticular lens 5 is formed such that the pitch (p) and the radius of curvature (r) satisfy the following expression (1). ## EQU3 ## As described above, by forming the lateral lenticular lens 5, the incident light is first spread in the vertical direction by the horizontal lenticular lens 5, and then is spread in the horizontal direction by the vertical lenticular lens 4. Become
The horizontal and vertical viewing angles can be simultaneously enlarged. Further, the lateral direction of the lens pitch of the lenticular lens 5 (p) of the Fresnel lens pitch _(p f)
By setting the pitch (p) and the radius of curvature (r) so as to satisfy the relationship of the above equation (1), the viewing angle in the vertical direction is sufficiently widened. At the same time, the occurrence of the moire phenomenon by the lateral lenticular lens 5 and the Fresnel lens 3 can be suppressed, and a screen having a wide viewing angle without the moire phenomenon can be provided. When the lens pitch (p) of the lateral lenticular lens 5 exceeds 4/5 of the pitch of the Fresnel lens ( _pf ), the occurrence of the moire phenomenon due to interference with the Fresnel lens 3 becomes remarkable, and conversely, less than 1/10. the processing is for poor productivity will be very difficult. Further, considering the workability of the lateral lenticular lens 5 and the effect of suppressing the moire phenomenon, the lens pitch of the lateral lenticular lens 5 is preferably in the range of 0.01 to 0.1 mm . [0014] On the other hand, p / r is not the total light transmittance and the gain _{(G 0)} is a bright image decreases is obtained exceeds 0.8, the vertical inverse to p / r is less than 0.4 This is because the expansion of the viewing angle becomes insufficient. The lateral lenticular lens 5 of the present invention
May be a convex lenticular lens as shown in FIG. 4 or a concave lenticular lens as shown in FIG. The lens pitch (p) or radius of curvature (r) of the lateral lenticular lens is
It may be constant from the top to the bottom of the screen, or may be changed randomly or regularly as needed. For example, when the radius of curvature (r) of the lateral lenticular lens 5 formed near the upper portion and the lower portion of the screen is made smaller than that of the other portions, the vertical direction near the upper portion and the lower portion is reduced. Of the viewing angle can be increased. Further, when the screen is installed at a relatively high position, the vertical viewing angle only at the upper part of the screen may be widened. Therefore, the radius of curvature (r) of the lateral lenticular lens 5 formed near the upper part may be reduced. What is necessary is just to form so that it may be small. Further, the lateral lenticular lens 5 may be formed on the entire incident surface of the Fresnel lens sheet 1 or the lenticular lens sheet 2, but may be formed only on a specific part as needed. In the present invention, the lateral lenticular lens 5 may be formed on either the Fresnel lens sheet 1 or the lenticular lens sheet 2,
Forming it on the incident surface side of the Fresnel lens sheet 1 is preferable because stray light or the like generated in the Fresnel lens sheet 1 can be prevented and generation of a rainbow or the like can be prevented. The lateral lenticular lens 5 of the present invention is formed by a method such as an extrusion molding method, a casting molding method, an injection molding method, a hot press molding method, or a method using an active energy ray-curable resin such as ultraviolet rays. Can be. In the rear projection type screen of the present invention, by forming the lenticular lens 5 in the horizontal direction as described above, the diffusivity in the vertical direction is imparted, so that the use amount of the light diffusing agent can be reduced. And the brightness and contrast can be improved by increasing the total light transmittance and the gain (G ₀ ), but from the viewpoint of suppressing the occurrence of moire phenomenon and reflection in the Fresnel lens 3 and the vertical lenticular lens 4. , Fresnel lens sheet 1 and
And at least one of the lenticular lens sheets 2 has a total light transmittance of 0.5 to 2 % by weight , a gain (G ₀ ),
A small amount of the light diffusing agent Ru is mixed <br/> within a range that does not impair the contrast. The light diffusing agent is not particularly limited, and a known diffusing agent can be used.For example, silica, calcium carbonate, barium sulfate, titanium oxide, alumina, zinc oxide, inorganic fine particles such as glass, a crosslinked polymer, etc. Organic fine particles and the like can be mentioned. Further, instead of mixing the light diffusing agent into the sheet, a light diffusing agent layer in which the light diffusing agent is mixed may be formed, or fine irregularities may be formed on the surface of the Fresnel lens sheet or the lenticular lens sheet. It may be formed. Further, in addition to the light diffusing agent, additives such as a tinting agent, a flame retardant, a light stabilizer, and a heat deterioration preventing agent can be added as needed. The present invention will be described below in detail with reference to examples. Example 1 An acrylic resin plate having a refractive index of 1.492 and a thickness of 3 mm and containing 1% by weight of silica powder having an average particle size of 10 μm was used, and one surface thereof was as shown in FIG. Pitch 0.4
A vertical lenticular lens 4 in which a lens 6 having a circular section 6 mm in diameter and a lens 7 having a total reflection surface 8 having a pitch of 0.3 mm are alternately arranged.
A horizontal lenticular lens 5 having a curvature radius of 0.13 mm and having a circular arc cross section was formed by hot press molding, and a lenticular lens sheet 2 was obtained. On the other hand, the refractive index is 1.4.
92, a Fresnel lens sheet 1 in which a circular Fresnel lens 3 having a pitch of 0.13 mm was formed on one surface of the acrylic resin plate having a thickness of 3 mm by hot press molding. The obtained lenticular lens sheet 2 and Fresnel lens sheet 1 were, as shown in FIG.
A rear projection type in which the Fresnel lens sheet 1 is installed on the light source side so that the Fresnel lens 3 is on the emission surface side, and the lenticular lens sheet 2 is installed on the observation side such that the vertical lenticular lens 4 is on the emission surface side. Assembled the screen. When this rear-projection screen was attached to a Pioneer 50-inch projection television and the image was observed, the vertical directivity (αV) was 12 °, the viewing angle in the vertical direction was wide, the total light transmittance was 52%, and the gain was 52%. A bright screen with (G ₀ ) of 4.5 was obtained. Also, the rainbow,
It was a uniform screen with almost no double image and no moiré phenomenon. Example 2 Using an acrylic resin plate having a refractive index of 1.492 and a thickness of 3 mm, a circular Fresnel lens 3 having a pitch of 0.13 mm was formed on one surface and a pitch of 0.08 mm was formed on the other surface.
A horizontal lenticular lens 5 having a radius of curvature of 0.13 mm and a circular arc cross section was formed by hot press molding, and a Fresnel lens sheet 1 was obtained. On the other hand, an acrylic resin plate having a refractive index of 1.492 and a thickness of 3 mm containing 1% by weight of silica powder having an average particle diameter of 10 μm was used, and a pitch of 0.4 mm as shown in FIG. Vertical lenticular lens 4 in which lenses 6 each having a circular cross section and lenses 7 having a total reflection surface 8 having a pitch of 0.3 mm are alternately arranged.
Was formed by hot press molding to obtain a lenticular lens sheet 2. The obtained lenticular lens sheet 2 and Fresnel lens sheet 1 were, as shown in FIG.
A rear projection type in which the Fresnel lens sheet 1 is installed on the light source side so that the Fresnel lens 3 is on the emission surface side, and the lenticular lens sheet 2 is installed on the observation side such that the vertical lenticular lens 4 is on the emission surface side. Assembled the screen. When this rear-projection screen was attached to a Pioneer 50-inch projection television and the image was observed, the vertical directivity (αV) was 12 °, the viewing angle in the vertical direction was wide, the total light transmittance was 52%, and the gain was 52%. A bright screen with (G ₀ ) of 4.5 was obtained. Also, the rainbow,
It was a uniform screen with almost no double image and no moiré phenomenon. Comparative Example 1 An acrylic resin plate having a refractive index of 1.492 and a thickness of 3 mm and containing 3% by weight of silica powder having an average particle size of 10 μm was used, and one surface thereof was as shown in FIG. Pitch 0.4
A lenticular lens sheet 2 was obtained by forming a vertical lenticular lens 4 in which lenses 6 having a circular section 6 mm in diameter and lenses 7 having a total reflection surface 8 with a pitch of 0.3 mm were alternately arranged by hot press molding. On the other hand, using an acrylic resin plate having a refractive index of 1.492 and a thickness of 3 mm,
A Fresnel lens sheet 1 in which a circular Fresnel lens 3 having a pitch of 0.13 mm was formed on one surface thereof by hot press molding was obtained. The obtained lenticular lens sheet 2 and Fresnel lens sheet 1 were, as shown in FIG.
A rear projection type in which the Fresnel lens sheet 1 is installed on the light source side so that the Fresnel lens 3 is on the emission surface side, and the lenticular lens sheet 2 is installed on the observation side such that the vertical lenticular lens 4 is on the emission surface side. Assembled the screen. When this rear projection screen was attached to a Pioneer 50-inch projection television and the image was observed, the vertical directivity (αV) was 8 °, the viewing angle in the vertical direction was narrow, the total light transmittance was 44%, and the gain was 44%. (G
₀ ) was as low as 3.0, and the luminance and contrast were low. Comparative Example 2 An acrylic resin plate having a refractive index of 1.492 and a thickness of 3 mm and containing 1% by weight of silica powder having an average particle size of 10 μm was used, and one of the surfaces was as shown in FIG. Pitch 0.4
A vertical lenticular lens 4 in which lenses 6 each having a circular cross section of 1 mm and a lens 7 having a total reflection surface 8 having a pitch of 0.3 mm are alternately arranged.
A horizontal lenticular lens 5 having a curvature radius of 0.13 mm and having a circular arc cross section was formed by hot press molding, and a lenticular lens sheet 2 was obtained. On the other hand, the refractive index is 1.4.
92, a Fresnel lens sheet 1 in which a circular Fresnel lens 3 having a pitch of 0.13 mm was formed on one surface of the acrylic resin plate having a thickness of 3 mm by hot press molding. The lenticular lens sheet 2 and the Fresnel lens sheet 1 obtained as shown in FIG.
A rear projection type in which the Fresnel lens sheet 1 is installed on the light source side so that the Fresnel lens 3 is on the emission surface side, and the lenticular lens sheet 2 is installed on the observation side such that the vertical lenticular lens 4 is on the emission surface side. Assembled the screen. When this rear-projection screen was attached to a Pioneer 50-inch projection television and an image was observed, the vertical directivity (αV) was 15 degrees, the viewing angle in the vertical direction was wide, the total light transmittance was 55%, and the gain was 55%. A bright screen with (G ₀ ) of 5 was obtained. However, the occurrence of the moire phenomenon by the Fresnel lens 4 and the lateral lenticular lens 5 was remarkable. Comparative Example 3 An acrylic resin plate having a refractive index of 1.492 and a thickness of 3 mm and containing 1% by weight of silica powder having an average particle diameter of 10 μm was used, and one surface thereof was formed as shown in FIG. Pitch 0.4
A vertical lenticular lens 4 in which lenses 6 each having a circular section 6 mm in diameter and lenses 7 having a total reflection surface 8 having a pitch of 0.3 mm are alternately arranged.
A lateral lenticular lens 5 having a curvature radius of 0.23 mm and having a circular arc cross section was formed by hot press molding, and a lenticular lens sheet 2 was obtained. On the other hand, the refractive index is 1.4.
92, a Fresnel lens sheet 1 in which a circular Fresnel lens 3 having a pitch of 0.13 mm was formed on one surface of the acrylic resin plate having a thickness of 3 mm by hot press molding. The obtained lenticular lens sheet 2 and Fresnel lens sheet 1 were, as shown in FIG.
A rear projection type in which the Fresnel lens sheet 1 is installed on the light source side so that the Fresnel lens 3 is on the emission surface side, and the lenticular lens sheet 2 is installed on the observation side such that the vertical lenticular lens 4 is on the emission surface side. Assembled the screen. When this rear-projection screen was attached to a Pioneer 50-inch projection television and the image was observed, the vertical directivity (αV) was 5.3 ° and the vertical viewing angle was not sufficient. Comparative Example 4 An acrylic resin plate having a refractive index of 1.492 and a thickness of 3 mm and containing 1% by weight of silica powder having an average particle size of 10 μm was used, and one surface thereof was as shown in FIG. Pitch 0.4
A vertical lenticular lens 4 in which lenses 6 each having a circular section 6 mm in diameter and lenses 7 having a total reflection surface 8 having a pitch of 0.3 mm are alternately arranged.
A lateral lenticular lens 5 having a curvature radius of 0.05 mm and an arc-shaped cross section was formed by hot press molding to obtain a lenticular lens sheet 2. On the other hand, the refractive index is 1.9.
42, a 3 mm thick acrylic resin plate was used to obtain a Fresnel lens sheet 1 in which a circular Fresnel lens 3 having a pitch of 0.13 mm was formed on one surface thereof by hot press molding. The lenticular lens sheet 2 and the Fresnel lens sheet 1 obtained as shown in FIG.
A rear projection type in which the Fresnel lens sheet 1 is installed on the light source side so that the Fresnel lens 3 is on the emission surface side, and the lenticular lens sheet 2 is installed on the observation side such that the vertical lenticular lens 4 is on the emission surface side. Assembled the screen. When this rear-projection screen was attached to a Pioneer 50-inch projection television and the image was observed, the vertical directivity (αV) was 20 ° and the vertical viewing angle was wide, but the total light transmittance was 49%. , The gain (G ₀ ) was as low as 1.5, and the luminance and contrast were low. The rear projection type screen of the present invention has a high total light transmittance and a high gain (G ₀ ) and a high verticality by forming a lateral lenticular lens having a specific range of pitch and radius of curvature. This makes it possible to enlarge the visual field range in the direction and to obtain an excellent image in which the moire phenomenon is suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial perspective view schematically showing a configuration of a rear projection screen of the present invention. FIG. 2 is a partial perspective view schematically showing another configuration of the rear projection type screen of the present invention. FIG. 3 is a partial sectional view showing the shape of a vertical lenticular lens of the present invention. FIG. 4 is a partial sectional view showing the shape of a lateral lenticular lens of the present invention. FIG. 5 is a partial sectional view showing another shape of the lateral lenticular lens of the present invention. FIG. 6 is a partial perspective view schematically showing the configuration of a conventional rear projection screen. [Description of Signs] 1: Fresnel lens sheet 2: Lenticular lens sheet 3: Fresnel lens 4: Vertical lenticular lens 5: Horizontal lenticular lens 6: Round lens 7: Lens having total reflection surface 8: Total reflection Surface 9: Arc-shaped top surface

Claims (1)

(57) [Claims 1] A rear projection screen including a Fresnel lens sheet having a Fresnel lens formed thereon and a lenticular lens sheet having a vertical lenticular lens formed on an exit surface side. there are, on the incident surface side of the Fresnel lens sheet and / or a lenticular lens sheet, the pitch is 1/10 of the pitch of the Fresnel lens
A 4/5 horizontal direction of the lenticular lens pitch 0.01~0.1mm the pitch (p) and the radius of curvature (r) satisfies the following equation (1) is formed, the Fresnel lens
Sheet and lenticular lens sheet
A rear projection screen , wherein 0.5 to 2% by weight of a light diffusing agent is mixed in one side. (Equation 1)