Patent Application
20060268404
This application claims, under 35 USC 119, priority of Japanese Application No. 2005-157974 filed May 30, 2005.
1. Field of the Invention
The present invention relates to a rear projection type screen for use in a graphic display device such as a rear projection type projection television or the like.
2. Description of the Background Art
In recent years, a rear projection type projection television has been expanding its market as a graphic display device capable of providing a large-screen image at low cost.
The luminance, contrast, and view angle characteristics of an image projected on a rear projection type projection television is largely influenced by characteristics of a rear projection type screen for use in this rear projection type projection television. Thus, for improved characteristics of the screen, a lenticular lens type has been well known in which divergent light 105 from a projector as shown in
A rear projection type screen of the lenticular lens type has suffered from a problem that, due to a limitation that the lenticular lens sheet can condense light only in one dimensional direction, combined use of two lenticular lens sheets whose ridge lines are orthogonal to each other is required in order to control the emergence angle of light both in the vertical and horizontal directions of the screen, thus resulting in deterioration in the light use efficiency and also an increased number of components used which leads to cost increase. To solve such a problem, a rear projection type screen has been proposed which uses, instead of a lenticular lens sheet, a microlens array sheet with an array of microlenses having an oval surface with different curvatures in the vertical and horizontal directions (J Japanese Patent Laid-Open Publication No. 2000-131506 (Page. 3 in
Furthermore, an example of a rear projection type screen has been disclosed which is configured to be less susceptible to the effect of external light by arranging a louvered light absorbing wall row between a black stripe and a light diffusing sheet (Japanese Patent Laid-Open Publication No. 1999-167167 (Page. 5,
However, the conventional rear projection type screen using the microlens array sheet suffers from a problem that a light blocking layer, that is, a pinhole array is fabricated by printing, a photolithographic method, or a self alignment method, thus making it difficult to provide the light blocking layer with some thickness, which results in difficulty in improving the effect of blocking external light such as an illumination lamp.
On the other hand, the louvered light absorbing wall row suffers from a problem that failure to use it with the black stripe results in a too large aperture in the light transmission direction to sufficiently block external light, thus resulting in an increased number of components used and thus cost increase which leads to high price.
Moreover, the conventional screen suffers from a problem that, due to its tendency to be charged, long-term usage results in image quality degradation caused by, for example, dust adhesion by static electricity.
It is an object of the present invention, concerning a screen using a conventional microlens array, to provide a low-cost rear projection type screen with favorable contrast achieved by improving the effect of blocking external light without deterioration in the luminance and the view angle characteristics, and also to provide a rear projection type screen free from image quality degradation over a long-term period due to its resistance to dust adhesion.
One aspect of the present invention refers to a rear projection type screen including at least: a transparent microlens array sheet formed by arraying a microlens on one surface thereof, the microlens condensing parallelly incident light on a focus, and a directional light absorbing sheet having an aperture which transmits light from a specific direction and absorbs other light. The aperture of the directional light absorbing sheet is a pinhole array having an apertured pinhole arrayed near the focus of the microlens. An aperture part of the pinhole is shaped into a truncated cone.
The use of the directional light absorbing sheet having the pinhole shaped into a truncated cone in this manner permits effective absorption of light obliquely incident with an incidence angle of a certain value or more, such as illumination light, while keeping the aperture at minimum. This permits display of an image with high contrast and also permits focused light from the microlens to efficiently exit, which avoids a reduction in the luminance, thereby resolving the problem described above.
The rear projection type screen is configured such that the shape of the arrayed microlens is either of a square and a rectangle.
This configuration permits efficiently condensing all light from a projector and also permits finely filling even a microlens having different curvatures in the vertical and horizontal directions, thus resulting in improved luminance, thereby resolving the problem described above.
Further, the rear projection type screen is configured such that an interval for the arrayed pinhole is so formed as to become increasingly wider from a central part of the screen toward a peripheral part thereof.
This configuration permits light condensed on the microlens to effectively exit from the pinhole without use of a Fresnel lens for light emitted from the projector, thus providing a low-cost screen with high contrast, thereby resolving the problem described above.
The rear projection type screen is configured such that a surface of the aperture formed by the pinhole array of the microlens array sheet forms a lens surface that is so curved as to be convexed or concaved.
Curving the aperture in this manner permits controlling the spread angle of light exiting from the aperture, thus providing display of an image with a wide view angle, thereby resolving the problem described above.
The rear projection type screen is configured such that an upper bottom surface side of the aperture part shaped into the truncated cone forming the pinhole faces a side of the microlens array sheet, and such that the focus of the microlens is provided near the upper bottom surface.
This configuration prevents external light obliquely incident at a certain angle or more from reaching the aperture surface, thus preventing reflection of the external light on the surface and also permitting an improvement in the contrast, thereby resolving the problem described above.
The rear projection type screen is provided such that diffusing particles dispersed in a transparent resin are disposed inside the pinhole shaped into the truncated cone, or such that, on a surface opposing the microlens of the microlens array sheet, emboss for scattering light is formed on at least the surface exposed by the pinhole.
This configuration diffuses the outgoing light, providing a rear projection type screen with a wide view angle, thereby resolving the problem described above.
Further, the rear projection type screen is configured such that a lower bottom surface of the aperture part shaped into the truncated cone forming the pinhole faces a side of the microlens array sheet, such that a projection shaped into a truncated cone similar to the truncated cone forming the pinhole is formed integrally on a surface opposing the microlens of the microlens array sheet, and such that the projection shaped into the truncated cone fits with the truncated cone forming the pinhole.
Such a configuration permits accurate matching between the aperture position of the pinhole and the focus position of the microlens, thus providing a bright image without losing the luminance, thereby resolving the problem described above.
For the truncated cone forming the pinhole, the upper bottom surface thereof is tilted so that the height thereof is smallest at an end part thereof located farthest from the center of a screen surface. The angle of the tilt is formed so that the truncated cone located farther from the center of the screen has a larger angle of the tilt.
This permits projection light to exit from any point on the screen at a uniform radiation angle without adjusting the light divergence angle by using a Fresnel lens or the like on the light incidence side of the microlens sheet, thus permitting reducing the view angle dependency of the luminance distribution, thereby resolving the problem described above.
The upper bottom surface of the projection shaped into the truncated cone forms a light scattering surface for scattering light.
This permits widening the radiation angle of light exiting from the screen, thus resulting in a screen with a wider view angle, thereby resolving the problem described above.
Further, the exist side surface of the directional light absorbing sheet forms a light scattering surface for scattering light.
This permits reducing the amount of light entering on the view point from the surface of the directional light absorbing sheet, thus resulting in an improved black level on the surface of the directional light absorbing sheet and thus improved contrast of a display image, thereby resolving the problem described above.
The directional light absorbing sheet and the microlens array sheet are formed of thermoplastic polymeric material, and the softening point of the material forming the directional light absorbing sheet is higher than the softening point of the material forming the microlens array sheet. Then, the directional light absorbing sheet and the microlens array sheet are integrally formed by thermal fusion bonding.
This makes easier the fusion bonding between the directional light absorbing sheet and the microlens array. Moreover, the integration of the directional light absorbing sheet and the microlens array permits maintaining a stable relationship between the aperture position and the microlens focus position described above.
The thermoplastic material forming the directional light absorbing sheet is formed by either of dispersing carbon particles or metal particles.
This permits improving the light absorbing effect exerted by the directional light absorbing sheet, thereby resolving the problem described above.
The directional light absorbing sheet is formed of a metal plate having on a surface thereof a light absorbing layer.
This permits easily fabricating the rear projection type screen of the present invention at low cost, thereby resolving the problem described above.
The directional light absorbing sheet and the microlens array sheet are composed integrally by insert molding.
This permits integration of the directional light diffusing sheet and microlens array sheet simultaneously with manufacture thereof, and permits manufacture of a rear projection type screen with stable quality at low cost, thereby resolving the problem described above.
The directional light absorbing sheet has a thickness of approximately 40 μm or more.
This permits maintaining sufficient directivity of the directional light diffusing sheet, thereby resolving the problem described above.
A Fresnel lens sheet for controlling the spread angle of projection light is disposed in front of the light entrance surface of the microlens array sheet.
The use of the Fresnel lens in this manner makes easier manufacture of the rear projection type screen of the present invention, thereby resolving the problem described above.
Any of or all of the directional light absorbing sheet, the microlens array sheet, and the Fresnel lens sheet are formed of antistatic material or subjected to antistatic prevention processing so as to form the rear projection type screen of the present invention.
This prevents each component of the rear projection type screen of the present invention from being charged, thus avoiding deterioration in the screen characteristics due to dust adhesion, thereby resolving the problem described above.
The rear projection type screen of the present invention is not susceptible to the effect external light such as an illumination lamp or the like and also permits projection light from the projector to efficiently exit, thus providing effect that a high-contrast, bright image can be displayed even in a bright room.
Moreover, as a result, a bright image can be obtained even with a light source of a relatively low output, thus providing effect that the life of a light source used for the projector can be increased and also that the life of a liquid crystal display device can be improved as well as the display quality can be stabilized.
Furthermore, as a result, effect is provided that the cost of the rear projection type display device embodying the present invention can be reduced.
Hereinafter, a preferred embodiment implementing a rear projection type screen of the present invention will be described referring to the accompanying drawings.
This rear projection type image display device can provide a brighter image with larger luminance of an optical image from the projector 26 and with higher transmittance of the screen. Moreover, with higher contrast of a projection image from the projector 26, more darkness inside the dark box, and smaller light reflection on the screen external surface, a display area has higher contrast.
It is an object of the present invention to provide a rear projection type screen capable of displaying an image with high luminance and high contrast by improving the transmittance of screen, reducing the brightness inside the dark box, and reducing the reflectance of the screen external surface.
The microlens array sheet 25 is formed by arraying, on at least one side surface thereof, microlenses for condensing parallel light. This surface, where the microlenses are formed, usually forms an aspherical surface; however, it is in many cases formed with a spherical surface which is easy to design and process. Such microlenses are usually arrayed in a matrix form in many cases, but may be alternatively closest-packed by being shifted in a houndstooth form.
On the other hand, the directional light absorbing sheet has a function of transmitting light having an incidence angle within the specific range while blocking any other light. Specifically, the present invention provides structure such that light condensed by the microlens described above is at least transmitted.
To achieve such structure, the directional light absorbing sheet of the present invention has pinholes each having an aperture shaped into a truncated cone, which is formed in a light absorbing substrate. This pinhole is formed near the focus of the microlens described above. Thus, light condensed on the focus by the microlens is transmitted without being interfered by the pinhole described above. Meanwhile, external light also enters the aperture. However, the aperture itself is the pinhole; therefore, the external light can enter inside the screen to a degree corresponding to the aperture ratio thereof, thus reducing effect that the light becomes lost or becomes a noise component inside the rear projection type display device. Furthermore, due to the truncated conical shape of the aperture, an obliquely incident external light component is blocked by the side surface of the truncated cone and thus does not enter inside the screen through the aperture; therefore, this pinhole functions as a pinhole having a practically smaller aperture ratio than a normal pinhole conventionally used. On the other hand, for external light component reflected on the screen surface, for the reason described above, reflection light from the surface of the aperture part becomes practically smaller than the normal pinhole. Thus, the rear projection type screen of the present invention has a higher black level than a conventional rear projection type screen. Consequently, an image displayed on the screen of the present invention can provide high luminance (that is, white level) and a high black level even under the presence of external light, thus providing a high quality image provided with high contrast.
It is another object of the present invention to provide a rear projection type screen that avoids a change in the display image quality with time due to dust adhesion to the screen surface by electrostatic.
That is, in the present invention, the microlens array sheet and the directional light absorbing sheet are formed of antistatic material or subjected to antistatic processing so as not to be charged. Consequently, the screen of the present invention is free from accumulation of dust due to electrostatic charge even under long-term usage and capable of maintaining favorable display quality over a prolonged period.
Specifically, each element used for the rear projection type screen of the present invention is usually formed of polymeric material. The directional light absorbing sheet is fabricated by using polymeric material formed of material containing dye or a colorant or light absorbing material, while the microlens array sheet is formed of transparent polymeric material.
In the directional light absorbing sheet, the carbon particles or a metal powder can be mixed to improve the conductivity. In addition, in the directional light absorbing sheet and the microlens array sheet, a soluble type surfactant agent, a copolymerization type surfactant agent, or a polymer type surfactant agent may be kneaded inside, or surface treatment may be performed by using these agents to provide antistatic material.
The rear projection type screen of the present invention may have the directional light absorbing sheet and the microlens array sheet both formed by, for example, roll molding or press molding, or, depending on the sheet thickness, injection molding. In this operation, for example, performing so-called insert molding, by which directional light absorbing sheet is molded and thereafter the microlens array sheet is superimposed thereon to be subjected to molding processing, permits fabrication by accurately matching the position of the microlens formed on the microlens sheet with the position of the pinhole formed on the directional light absorbing sheet.
In performing such insert molding, in a case where the softening point of the polymeric material forming the directional light absorbing sheet is higher than the softening point of the polymeric material forming the microlens array sheet, a larger degree of freedom in the molding conditions can be provided, and also more favorable accuracy can be provided.
Using what is obtained by forming the directional light absorbing sheet with metallic material such as, for example, aluminum or the like, and providing thereon light absorbing treatment, such as black alumite treatment or the like, can make it easier to perform the insert molding described above.
Hereinafter, embodiments of an illumination device of the present invention will be described in detail referring to the drawings.
The microlens 3 is formed with a spherical surface, an oval surface, or the like with the center of symmetry lying at the center of the divided square or rectangular region. This divided square or rectangular region has a pitch of 100 to 500 μm, and it is preferable that this pitch is typically 150 to 220 μm.
It is desirable that the sheet thickness of the microlens array sheet 1 be approximately 400 μm or more, but it may be smaller than this depending on the refractive index of material used and the pitch of the microlens array.
The region where the microlens 3 is formed is a very small region as described above; therefore, in individual regions of the microlenses 3, a projection image from the projector can be assumed as approximately parallel light.
Parallel light entering from the microlens 3 side is condensed on a predetermined point (focus) at the directional light absorbing sheet side. The focus at this directional light absorbing sheet side is usually located at one point when the microlens 3 is a spherical lens; however, when the microlens 3 is an oval lens, this focus becomes non-point, so that condensation is performed at two different points, i.e., along the longer axis and shorter axis of the oval. However, in either case, these focuses are located near the pinhole 5 where the directional light absorbing sheet 2 is formed. Here, the focus of the microlens 3 is designed to be located inside the directional light absorbing sheet 2, but may be located at the position where this focus matches with the directional light absorbing sheet 2 or the position outside the directional light absorbing sheet 2. Thus, these focuses are set in accordance with the various conditions.
The size (diameter) of the pinhole 5, near the focus of the microlens 3 described above, is almost equal to a beam of incident light condensed by the microlens 3 or is set larger than this beam. This makes all of incident light condensed by the microlens 3 to be transmitted to the outside and also prevents as much as possible external light from entering inside the microlens array sheet 1. The shape of the pinhole 5 is appropriately adapted to be a circle, an oval, a quadrangle (square, rectangle), or the like in accordance with the shape of light focused by the microlens 3.
An aperture 6 of the pinhole 5 is shaped into a truncated cone as shown in
The portion of the directional light absorbing sheet 2 excluding the apertures 6 is formed of light absorbing material, so that light illuminated on the portion excluding the apertures 6 is absorbed and thus not transmitted. Used as this light absorbing material includes: a material obtained by mixing the metal powder or the carbon powder in polymeric material and coloring it, and a material obtained by mixing a black color dye for coloring.
The portion of the aperture 6 of the directional light absorbing sheet 2 is filled with transparent synthetic resin or hollowed, depending on its design. The same material as the microlens array sheet 1 may be used, but usually the ratio of refractive index between the aperture 6 of the directional light absorbing sheet 2 and the microlens array sheet 1 described above is set so that light passing through the pinhole 5 at this boundary toward the outside is deflected in an adequate direction. More specifically, a transparent material is used which has a refractive index determined in relation to the refractive index of the material used for the microlens array sheet 1, that is, the refractive index at which light passing through the pinhole 5 toward the outside is diffused.
Here, a description will be given, referring to a case where the microlens 3 is a spherical lens. Assuming that the center of the spherical surface forming the microlens 3 is C, the light entering toward the center C travels straight directly and passes through a focus F. The position of the focus F is determined by the refractive index of the material forming the microlens array sheet 1, a curvature radius of the microlens 3, and a refractive index of the air. In
On the other hand, light 30 entering the end part of the microlens 3 is refracted by the microlens 3, passes through the focus F, is made incident on a different surface of the microlens array sheet 1, is refracted in accordance with Snell's law, and then exits as a ray 32. The refractive index of the material forming the microlens array sheet 1 is larger than that of a medium (air) at the exit side; therefore, the emergence angle of the ray 32 is wider than the incidence angle thereof on the incidence surface, which permits a wider view angle.
The aperture 6 of the directional light absorbing sheet 2 is shaped into a circular truncated cone. The vertex angle of this circular truncated cone is equal to or larger than the emergence angle of light from the microlens array sheet 1. Thus, light exiting from the microlens array sheet 1 is not absorbed by the directional light absorbing sheet 2 while exiting therefrom.
On the other hand, like external light 35, light entering the screen from an illumination lamp 7 at a large incidence angle is absorbed by the directional light absorbing sheet 2. Even when the incidence angle of this external light is smaller than the vertex angle of the circular truncated cone, all the light excluding those directly entering the pinhole 5 is absorbed by the directional light absorbing sheet 2. In many cases, an interior illumination lamp is provided at the ceiling, and external light from the window and the like also enter from the side surface of the rear projection type display device in many cases. Therefore, it is assumed that a large portion of the external light enters at an incidence angle larger than the vertex angle of the circular truncated cone. Thus, the screen of the present invention absorbs much of external light and thus is capable of achieving a high black level.
Light entering inside the screen through the pinhole 5, which has an incidence angle approximately smaller than the vertex angle of the aperture 6 of the circular truncated cone, is absorbed on the side surface 4 of the aperture 6 of the circular truncated cone and thus is reduced more than light entering inside the screen when a conventional pinhole is employed. That is, light entering inside the dark box of the rear projection type display device can is reduced more than can be achieved by the conventional one.
Consequently, the rear projection type screen of the present invention can improve the contrast of the display image.
Referring to
In
The pinhole 5 formed in the directional light absorbing sheet 2 is provided near the apparent focus Fl. That is, the pinhole 5 is provided near the focus that practically condenses light. The center of this pinhole 5 can be determined by the incidence angle of light entering toward the center C of the microlens 3 and the distance between the center C and the different surface. For example, if the light incidence angle is 30 degrees and the distance between the center C and the different surface is 250 μm, it can be recognized that the center of the pinhole 5 may be so formed in such a manner as to be shifted upward by approximately 145 μm with respect to the one shown in
As shown in
In the embodiment shown in
Furthermore, when mutually different angles of emergence from the screen in the vertical and horizontal directions are provided, that is, when an oval lens is used which has different spherical radiuses for the vertical and the horizontal directions of the microlens 3, optimizing the vertex angles in the vertical and horizontal directions of the square truncated cone of the aperture 6 with respect to the emergence angle described above permits maximizing both the emergence efficiency and the blocking efficiency.
Furthermore, forming the cross section of the aperture 6 into a square truncated cone makes it extremely easier to process a die for forming this shape by press molding or roll forming, which permits manufacture of the directional light absorbing sheet at low cost.
As shown in
As the light diffusing particles, transparent or translucent beads can be used which are formed of transparent polymers such as acrylic resin, polystyrene resin, or the like. The particle diameter and the refractive index of these light diffusing particles can be adjusted to thereby control the diffusion performance of light exiting from the screen. For example, beads of acrylic resin or styrene resin described above are used, those which have a particle diameter of approximately 1 to 20 μm may be provided with adequate particle distribution.
Although not clearly shown in
The projection 12 is formed with a lower bottom surface 13 thereof facing the microlens 3 side, with an upper bottom surface 5 thereof facing the screen surface side, and with a side surface 4 thereof so tilted as to open toward the microlens 3 side.
The projection 12 fits with the pinhole provided in the directional light absorbing sheet 2. The portion of the directional light absorbing sheet 2 excluding the pinhole is formed of light absorbing material.
On the other hand, among parallel light entering the microlens 3, the light 30 entering the peripheral part of the lens is refracted on the surface of the microlens 3 to be thereby condensed on the focus F, refracted on the upper bottom surface of the projection 12, that is, the pinhole, and then exits from the screen surface. Due to the position of the focus F located near the pinhole, the light condensed on the microlens 3 efficiently exits from the screen while being hardly absorbed on the side surface 4 of the aperture of the circular truncated cone formed in the directional light absorbing sheet 2.
On the other hand, external light from the illumination lamp 7 and the like obliquely enters the screen surface as shown by the light 35. Among such external light, the light illuminated on the surface where the pinhole of the directional light absorbing sheet 2 is not formed is directly absorbed by the directional light absorbing sheet 2 without entering inside the screen and also without entering the view point of the observer. In addition, as shown in
Needless to say, the projection shaped into a circular truncated cone is formed so that the rotation center thereof is located near the apparent focus. The amount of shift from the focus F to this apparent focus Fl is determined by the distance between the center C of the curvature radius of the microlens 3 and the focus F and also by the angle formed by the light 33 and a straight line CF. In other words, it is determined by the curvature radius of the microlens 3, the refractive index of the microlens array sheet 1, and the angle formed by the light 33 and the straight line CF.
Therefore, the projection formed on the microlens array sheet 1, in other words, the interval between the pinholes formed in the directional light absorbing sheet 2 is formed increasingly wider at a portion increasingly farther from the center of the screen. This permits efficiently leading all light entering from the projector to the microlens array sheet 1 of the screen of the present invention to the pinhole array formed in the directional light absorbing sheet 2, thereby achieving an image with high luminance.
At this point, there arises a difference in the pixel interval between the central part and the peripheral part of the screen. The degree of this difference is at most several hundreds μm, which does not create any sense of discomfort in an image actually observed.
Providing such structure can, as is the case with the second embodiment, provides the directional light absorbing sheet 2 with anisotropy in the directions within the plane thereof, and can optimize the emergence efficiency even in a case where a microlens array is used which is provided with anisotropy in the vertical and the horizontal radiation angles.
Moreover, shaping the projection and the pinhole aperture into a square truncated cone makes it easier to process a mold for manufacturing these components, thereby achieving a reduction in the manufacturing costs.
Setting the number of steps of the truncated cone shown in
The tilt of the light 33 becomes increasingly larger from the center of the rear projection type screen toward the peripheral part thereof, so that the tilt of the upper bottom surface 20 of the projection also becomes increasingly larger toward the peripheral part of the screen. In other words, the tilt angle of the upper bottom surface 20 described above is formed so that it becomes increasingly smaller at a truncated cone increasingly farther from the center of the screen, and the height of this upper bottom surface 20 is lowest at the end part which is located farthest from the center of the screen surface.
Accordingly, this provides uniform radiation distribution of light exiting from any position of the screen without correcting the spread angle of light from the projector by use of the Fresnel lens as is practiced by a conventional rear projection type screen, thereby permitting a reduction in the view angle dependency on the screen position of an image formed on the screen.
In the present embodiment, the vertex of the convex surface 20a of the projection 12 protrudes from the surface of the directional light absorbing sheet 2. However, needless to say, the vertex of the convex surface 20a may be located at the same level as the surface of the directional light absorbing sheet 2 or may be recessed therefrom. In this case, it is also preferable that the tilt surface of the projection 12 and an aperture tilt surface 4 formed in the directional light absorbing sheet 2 substantially coincide with each other.
In the present embodiment, the vertex of the concave surface 20b of the projection 12 is located at the position recessed from the surface of the directional light absorbing sheet 2. However, needless to say, the vertex of the concave surface 20b may be located at the same level as the surface of the directional light absorbing sheet 2 or may protrude therefrom. In this case, it is also preferable that the tilt surface of the convex part 12 and an aperture tilt surface 4 formed in the directional light absorbing sheet 2 substantially coincides with each other.
Forming the second light scattering surface 22 on the surface of the directional light absorbing sheet 2 causes external light to be diffused on this second light diffusing surface 22, thus avoiding this external light from entering the view point of a person viewing an image, which permits an improvement in the substantial black level on the surface of the directional light absorbing sheet 2. Consequently, a brilliant image can be displayed without causing a reduction in the contrast even in a bright room.
This first light scattering surface 21 effectively functions even in cases such as where the surface of the projection is provided with the tilted upper bottom surface shown in
More specifically, these first light scattering surface 21 and second light scattering surface 22 can be provided by forming on the surface concave and convex structure that is equivalent or slightly larger than the light wavelength level. That is, for example, the first light scattering surface 21 and the second light scattering surface 22 can be fabricated by forming an emboss pattern on the surfaces thereof by using a die whose surface is formed with the emboss pattern. Alternatively, after the screen is processed as shown in
It is preferable that the first light scattering surface 21 have a haze value of approximately 55 to 100%, and the second light scattering surface 22 have a haze value of approximately 35 to 65%.
As the light diffusing particles 23, transparent resin beads as are used in the case of the embodiment 3 can be used.
In the embodiment described above, a description with reference thereto has been given concerning different embodiments between the case where the aperture is so shaped as to widen outwardly as shown in
In each embodiment described above, the directional light absorbing sheet 2 is provided integrally with the microlens array sheet 1, but the directional light absorbing sheet 2 may be provided to an optical component other than the microlens array sheet 1. It can be used for any optical component which is required to achieve efficient emergence of outgoing light. In this case, as the configuration of the directional light absorbing sheet 2, the mode corresponding to each of the optical components is to be provided by adequately selecting from among the embodiments described above. A plurality of the embodiments may be combined together.
This permits efficient emergence of outgoing light while each of the optical components is not influenced by the external light, thus providing a high-contrast, bright image even in the bright room.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-157974 | May 2005 | JP | national |
