JP2006091468A - Light transmission body, light diffusion plate and screen for projector apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light diffusion plate which is very easily manufactured and has a remarkably increased diffusion efficiency. <P>SOLUTION: The light diffusion plate 10 is composed by providing a lot of recessed parts 11a, 11b, 11c and 11d or the like formed of a part of the inner face of a substantially spherical body on the light emitting side of a prescribed base material composed of a prescribed transparent film or the like. In the light diffusion plate 10, on which a lot of recessed parts 11a, 11b, 11c and 11d or the like are formed on the light emitting side, the incident light which is made incident on the peripheral part rather than a critical angle at an recessed part is not totally reflected but emits through adjacent recessed parts. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light transmissive body that transmits incident light, a light diffusing plate using the light transmissive body, and a projector apparatus screen using the light diffusing plate.

  In recent years, so-called overhead projectors and slide projectors have been widely used as display devices for presenting materials to audiences at meetings and the like. In general households, video projectors and movie film projectors using liquid crystals are becoming popular. As a display device, a so-called liquid crystal display device is also spreading.

  In such various projector devices and liquid crystal display devices, a light diffusing plate is provided to diffuse image light projected on a screen and light emitted from a fluorescent tube. Such a light diffusing plate is usually configured by laying fine convex lenses, more specifically, spherical beads on the order of 10 μm to several hundred μm on the surface.

  As a technique related to such light diffusion, techniques described in, for example, Patent Document 1 and Patent Document 2 have been proposed.

JP-A-10-282315 JP 2000-158450 A

  Specifically, Patent Document 1 discloses a light diffusing plate suitable for a transmissive screen and a manufacturing method thereof. In particular, this light diffusing plate has a fine concavo-convex shape that refracts and diffuses light rays on one surface on which light is incident, and the other surface on the observation side is substantially flat so that it substantially conforms to the fine concavo-convex shape. A light absorption layer is formed on the surface. Thereby, in this light diffusing plate, the diffusion effect can be increased and the effect of reducing external light reflection can be increased with a small transmission loss.

  Patent Document 2 discloses a method for manufacturing a light control member used in an image device such as a liquid crystal rear projector device or a liquid crystal display panel. In particular, the light control member manufacturing method includes expanding a concavo-convex shape by stretching a mold having a concavo-convex shape and being stretchable, and transferring the enlarged concavo-convex shape to the light control member or the light control member. The manufacturing mold is formed. Thereby, in this light control member manufacturing method, the light directivity can be easily adjusted to set the light diffusing action to an optimum state.

  By the way, the incident light on the interface on the light exit side is refracted or totally reflected according to the incident angle and the refraction ratio. Here, consider the parallel light that enters the spherical surface perpendicular to the light diffusion plate using the conventional acrylic spherical beads BZ. In this case, for example, as shown in FIG. 9, the incident light L1 incident near the center of each convex portion forming the spherical surface is refracted and emitted to the observation side, but a sphere having a critical angle of 42 ° or more. Incident light L2 and L3 incident on the peripheral portion repeats total internal reflection and does not exit to the observation side. For this reason, the conventional light diffusing plate using the spherical beads BZ has a problem in that the amount of light reaching the observer is reduced and the efficiency is poor.

  Further, in the conventional techniques including the above-mentioned Patent Document 1 and Patent Document 2, since both of the concave and convex shapes are formed, a portion where the area is suddenly narrowed on the surface perpendicular to the incident light occurs, Since total reflection occurs at such a location, there is a problem that a sense of inefficiency cannot be denied.

  The present invention has been made in view of such circumstances, and a light transmitting body and a light diffusing plate that can be manufactured extremely easily and can greatly improve the diffusion efficiency, and the light diffusing plate. An object of the present invention is to provide a screen for a projector device used.

  The light transmitting body according to the present invention that achieves the above-described object is a light transmitting body that transmits incident light, and is characterized in that a large number of recesses are formed in at least one interface.

  In such a light transmitting body according to the present invention, since a large number of recesses are formed in at least one interface, incident light incident on the peripheral portion is not totally reflected at a certain angle than a critical angle in a certain recess, and is adjacent to each other. The light is emitted through the concave portion. That is, in the light transmitting body according to the present invention, the ratio of incident light being refracted and emitted to the outside can be increased.

  Specifically, in the light transmitting body according to the present invention, the concave portion is formed on the light emitting side, and a large number of convex portions corresponding to the concave portion are formed on the light incident side.

  Here, such a concave portion can be formed so as to have a partial shape of a substantially spherical inner surface. The light transmitting body according to the present invention having such concave portions can be manufactured by inverting an original plate constituted by laying micro convex lenses on a predetermined base material.

  Specifically, the light transmitting body according to the present invention can be manufactured by applying a predetermined resin on the original plate and peeling off a predetermined film coated on the resin. Here, as the resin, it is desirable to use an ultraviolet curable resin, and the manufacturing can be facilitated. In addition, it is preferable to use a polyethylene terephthalate film as the film, and the light transmitting body according to the present invention can be obtained by irradiating the polyethylene terephthalate film coated on the ultraviolet curable resin with ultraviolet rays. It can be manufactured by peeling off the terephthalate film.

  Thereby, the light transmission body concerning this invention can be manufactured cheaply without using an expensive metal mold | die at all.

  Moreover, the light transmitting body according to the present invention uses a mount of a light diffusing plate configured by laying micro convex lenses on a predetermined base material instead of the film, and the ultraviolet curable resin is applied to the mount side. Can also be manufactured. As described above, in the light transmitting body according to the present invention, the light diffusion degree can be easily improved by using the conventional light diffusion plate as the mount of the ultraviolet curable resin.

  Furthermore, the recess may be formed to have a partial shape on the inner surface of the spheroid. Thereby, the light transmission body according to the present invention can emit incident light efficiently and improve the diffusivity, and can produce a screen having a wide viewing angle at low cost. The light transmitting body according to the present invention having such concave portions can be manufactured by inverting an original plate constituted by laying micro convex lenses on a predetermined base material.

  Specifically, the light transmitting body according to the present invention includes a predetermined resin on a concave group produced by applying a predetermined resin on the original plate and peeling off a predetermined film coated on the resin. It can be manufactured using a mold produced by applying a solution and solidifying the coated surface downward. Here, it is preferable to use a synthetic resin mold or an electroforming mold as the mold.

  Moreover, what was produced using the raw material which can be extended | stretched as said type | mold can also be used. The light transmitting body according to the present invention is manufactured using a temporary mold in which the mold is extended in a direction perpendicular to the major axis direction of the spheroid and the cross-sectional shapes of the recesses perpendicular to the interface and perpendicular to each other are different. Can do. More specifically, the light transmitting body according to the present invention can be manufactured using a main mold transferred twice based on the temporary mold. The ratio of the major axis to the minor axis of the ellipse, which is the shape of the stretched interface, is preferably 1.2 to 2.0.

  Furthermore, the light transmitting body according to the present invention can be manufactured by using a mold that is prepared by applying a predetermined resin solution on the original plate and solidifying the coated surface downward. Also in this case, it is preferable to use a synthetic resin mold or an electroforming mold as the mold.

  And also in this case, what was produced using the raw material which can be extended | stretched can be used as said type | mold. That is, the light transmissive body according to the present invention extends the mold in a direction perpendicular to the major axis direction of the spheroid, produces a temporary mold having different sectional shapes of the recesses perpendicular to the interface and perpendicular to each other. It can be manufactured using the main mold transferred twice based on the mold. The ratio of the major axis to the minor axis of the ellipse, which is the shape of the stretched interface, is preferably 1.2 to 2.0.

  As described above, the light transmitting body according to the present invention can narrow the viewing angle only in the vertical direction, which may have a narrow viewing angle, by extending the halfway mold in one direction, thereby realizing high luminance. it can.

  The light diffusing plate according to the present invention that achieves the above-described object is a light diffusing plate that diffuses incident light, and a plurality of concave portions are formed at a predetermined base material and at least one interface of the base material. It is characterized by comprising a light transmitting body.

  Furthermore, a projector device screen according to the present invention that achieves the above-described object is a projector device screen that projects image light from the projector device, and a large number of screens are provided at a predetermined base material and at least one interface of the base material. It is characterized by comprising a light diffusing plate having a light transmitting body in which a concave portion is formed.

  In such a light diffusing plate and projector apparatus screen according to the present invention, since a large number of concave portions are formed at at least one interface of the base material, incident light that has entered the peripheral portion more than the critical angle at a certain concave portion. Is emitted through the adjacent recess without being totally reflected. That is, in the light diffusing plate and the projector device screen according to the present invention, it is possible to increase the rate at which incident light is refracted and emitted to the outside.

  In the present invention, an optical product that can emit light that has been emitted in an unnecessary direction by total reflection at the interface in a necessary direction and can greatly improve the diffusion efficiency is manufactured extremely easily. be able to.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  This embodiment is a light diffusing plate suitable for use in projector screens and liquid crystal display devices. In particular, this light diffusing plate reduces the region where incident light is totally reflected by providing a large number of concave portions on the light emitting side formed in a convex shape in the conventional light diffusing plate. .

  First, the light diffusion plate shown as the first embodiment will be described.

  For example, as shown in FIG. 1, the light diffusing plate 10 generally emits a parallel light L emitted from a predetermined light source 21 and incident on a parallel light L formed by a predetermined optical system 22 such as a Fresnel lens. It is used for applications that diffuse in various directions.

  As shown in FIGS. 2 and 3, the light diffusing plate 10 has a large number of concave portions 11a having a substantially spherical inner surface on the light emitting side of a predetermined substrate made of a predetermined transparent film or the like. 11b, 11c, 11d,... Are provided. That is, the light diffusing plate 10 is not formed in a convex shape on the light emitting side, but is formed in a concave shape, unlike a light diffusing plate using a minute convex lens such as a conventional spherical bead. Accordingly, the light diffusing plate 10 has a large number of convex portions 12a, 12b, 12c, 12d,.

  In such a light diffusing plate 10, the incident light L1 incident on the vicinity of the center of the concave portion 11a is refracted and emitted toward the observation side, as in the case of the light diffusing plate using the conventional convex lens, and is critical in the concave portion 11b. Incident light L <b> 2 that enters the vicinity of the angle of 42 ° is totally reflected. However, in such a diffusing plate 10, the incident light L3 incident on the peripheral portion with respect to the critical angle in the concave portion 11c is emitted to the observation side through the adjacent concave portion 11d. Therefore, in such a diffuser plate 10, the rate at which incident light is emitted to the observation side increases.

  Such a light diffusing plate 10 can be manufactured by using a conventional light diffusing plate in which a minute convex lens such as a spherical bead is spread on a predetermined substrate as an original, and inverting it. That is, the light diffusing plate 10 is obtained by applying an ultraviolet curable resin on an original plate made of a conventional light diffusing plate, coating the ultraviolet curable resin with a polyethylene terephthalate film, and irradiating the polyethylene terephthalate film with ultraviolet rays. It can manufacture by peeling the said polyethylene terephthalate film.

  Moreover, the light diffusing plate 10 can also be manufactured by using a conventional light diffusing plate instead of the polyethylene terephthalate film and applying an ultraviolet curable resin to the mount side.

  As described above, the light diffusing plate 10 can be easily formed with a large number of recesses 11a, 11b, 11c, 11d,... By transferring the light diffusing plate to an ultraviolet curable resin using a conventional light diffusing plate as an original plate. It can be manufactured at low cost without using any expensive mold. Moreover, in the light diffusing plate 10, the light diffusivity can be easily improved by using a conventional light diffusing plate as a mount of the ultraviolet curable resin.

  Now, in order to compare the influence of light transmission in the case where the diffuser plate having the convex portion formed on the conventional light emitting side and the diffuser plate having the concave portion according to the present invention are adopted by the present applicant, An optical field simulation by the so-called FDTD method (Finite Difference Tome Domain Method) was performed (unsteady state). Note that the FDTD method is a technique for differentiating Maxwell's equations in time and space, updating the electromagnetic field in the analysis space in time using a so-called leapfrog algorithm, and obtaining the time response of the output point.

  As shown in FIG. 4 (a), the model shows a diffuser plate with a convex portion formed on the light exit side, and FIG. 4 (b) shows the diffuser plate with a concave portion formed on the light exit side. The light field was calculated only for the traveling direction of light when plane wave pulse light (wavelength λ = 530 nm) was incident from below. The refractive index of the diffusion plate was n = 1.4, and the refractive index on the light exit side was n = 1.0 assuming air.

  FIG. 5 (a) shows the result for the diffuser plate with the convex portion formed on the light output side, and FIG. 5 (b) shows the result for the diffuser plate with the concave portion formed on the light output side. From these figures, in the diffuser plate in which the convex portion is formed on the light emitting side, a considerable amount of light stays inside the diffuser plate, whereas the concave portion is formed on the light emitting side. In the diffusion plate, it can be seen that almost no light stays inside the diffusion plate. That is, as a result, in the diffuser plate in which the convex portion is formed on the light emitting side, there is many phenomenon that light is returned to the inside of the convex portion by total reflection, whereas a concave portion is formed on the light emitting side. The diffusion plate is nothing but the fact that the probability that light is emitted to the outside is high.

  As described above, in the light diffusing plate 10, the configuration in which a large number of minute convex lenses are conventionally juxtaposed is reversed, and a large number of concave lenses are juxtaposed to form an unnecessary direction due to total reflection at the interface. The emitted light can be emitted in a necessary direction, and highly efficient light transmission can be realized.

  Next, the light diffusion plate shown as the second embodiment will be described. The light diffusion plate shown as the second embodiment can further improve the light diffusion plate by further improving the light diffusion plate shown as the first embodiment. Specifically, the light diffusing plate shown as the second embodiment is formed into a substantially spherical inner surface shape by further applying a resin to the light diffusing plate shown as the first embodiment. The concave group is a concave group having a partial shape on the inner surface of the spheroid, and the viewing angle is widened. In addition, this light diffusing plate is made of silicon rubber or the like, and stretched in one direction, thereby narrowing the viewing angle in the stretching direction and realizing high luminance.

  As shown in FIGS. 6 and 7, the light diffusing plate 50 includes a plurality of concave portions 51 a, 51 b, which are partly formed on the inner surface of the spheroid, on the light emitting side of a predetermined substrate made of a predetermined transparent film or the like. 51c, 51d,... Are provided. Accordingly, the light diffusion plate 50 has a large number of convex portions 52a, 52b, 52c, 52d,.

  In such a light diffusing plate 50, incident light L4 incident on the recesses 51a, 51b, 51c, 51d,... Is refracted and emitted to the observation side, but the distance from the incident surface to the emission surface is long. Therefore, the horizontal distance from the incident position to the emission position becomes longer. That is, in the light diffusing plate 50, the viewing angle can be widened as compared with the case where a concave portion having a partial shape on the substantially spherical inner surface is formed.

  Such a light diffusing plate 50 can be manufactured by using a conventional light diffusing plate in which fine convex lenses such as spherical beads are spread as an original plate and inverting it. That is, in manufacturing the light diffusing plate 50, a predetermined synthetic resin is formed on the concave group obtained by inverting the conventional light diffusing plate in the process of manufacturing the light diffusing plate 10 shown as the first embodiment. The solution is applied and solidified with the application surface down. Thereby, since the synthetic resin solution gathers downward by its own weight, the amount of the synthetic resin increases toward the lower part, and a concave spheroid group is formed. The light diffusing plate 50 can be manufactured by manufacturing a replica from the inversion type manufactured as described above.

  The light diffusing plate 50 can also be manufactured by applying a synthetic resin solution in the vicinity of the top of spherical beads on a conventional light diffusing plate using a roller and solidifying the coated surface downward. In this case, since the synthetic resin solution gathers downward due to its own weight, the amount of the synthetic resin increases toward the lower part, and a convex spheroid group is formed. The light diffusing plate 50 can be manufactured by making a replica using this spheroid group as a mold.

  As described above, the light diffusing plate 50 efficiently emits incident light by making the shape of the numerous concave portions 51a, 51b, 51c, 51d,... And a screen with a wide viewing angle can be manufactured at low cost.

  By the way, in the light diffusing plate 50, the symmetrical viewing angle is not realized, but the viewing angle in the vertical direction with respect to the interface may be narrow, and it is desirable that only the viewing angle in the horizontal direction is wide. Therefore, in the light diffusing plate 50, the viewing angle change can be realized by using a moldable material such as silicon rubber as the above-described mold manufactured as a replica.

  That is, in manufacturing the light diffusing plate 50, a stretchable synthetic resin mold is produced, and the synthetic resin mold is stretched in a direction orthogonal to the major axis direction of the spheroid. As a result, the opening shape of the recesses 51a, 51b, 51c... Is deformed into an elliptical shape instead of a circular shape, for example, as shown in FIG. That is, in manufacturing the light diffusing plate 50, temporary molds having different sectional shapes of the recesses perpendicular to each other and perpendicular to the interface serving as the light emitting surface are manufactured. At this time, as an elliptical interface, the ratio of the major axis to the minor axis of the ellipse is preferably about 1.2 to 2.0. The light diffusing plate 50 can be manufactured by using the main mold transferred twice based on the temporary mold.

  As described above, the light diffusion plate 50 can narrow the viewing angle only in the vertical direction, which may have a narrow viewing angle, by extending the halfway mold in one direction, thereby realizing high luminance. it can.

  As described above, in the light diffusing plates 10 and 50 shown as the embodiment of the present invention, at least one of the interfaces, particularly the light emitting side interface, is formed of a substantially spherical inner surface or a partial shape of the inner surface of the spheroid. By forming a large number of recesses or recesses that extend the short-axis cross section of the spheroid, light that was emitted in an unnecessary direction by total reflection at the interface can be emitted in the required direction, and high efficiency Light transmission can be realized. Therefore, the projector screen and the liquid crystal display device to which the diffusion plates 10 and 50 are applied can realize extremely good image quality.

  The present invention is not limited to the embodiment described above. For example, in the above-described embodiment, it has been described that the light diffusion plates 10 and 50 are manufactured using an ultraviolet curable resin. However, the present invention is not limited to an ultraviolet curable resin, but a thermosetting resin or a two-component mixed resin. Etc. can also be used.

  Moreover, in embodiment mentioned above, although demonstrated as what manufactures the light diffusing plates 10 and 50 using a polyethylene terephthalate film, this invention is an acrylic resin film and polycarbonate property instead of a polyethylene terephthalate film. A resin film or the like may be used.

  Furthermore, in the above-described embodiment, the light diffusion plate 50 is described as being manufactured using a mold made of synthetic resin. However, the present invention may be manufactured using a mold formed by electroforming.

  Furthermore, in the above-described embodiment, the light diffusing plate that diffuses the incident light has been described. However, the present invention is not limited to the light diffusing plate, but is applied to a predetermined optical component that transmits the incident light. It can also be provided as a permeator.

  Thus, it goes without saying that the present invention can be modified as appropriate without departing from the spirit of the present invention.

It is a figure for demonstrating the use of the light diffusing plate shown as embodiment of this invention. It is a principal part side view explaining the structure of the light diffusing plate shown as the 1st Embodiment of this invention. It is a perspective view explaining the structure of the light diffusing plate. It is a figure explaining the model used in the light field simulation by FDTD method, Comprising: It is a side view of the diffusion plate model in which the convex part was formed in the light emission side. It is a figure explaining the model used in the optical field simulation by FDTD method, Comprising: It is a side view of the diffusion plate model in which the recessed part was formed in the light emission side. It is a figure which shows the simulation result using the model shown to Fig.4 (a). It is a figure which shows the simulation result using the model shown in FIG.4 (b). It is a principal part side view explaining the structure of the light diffusing plate shown as the 2nd Embodiment of this invention. It is a perspective view explaining the structure of the light diffusing plate. It is a principal part top view explaining the structure of the same light diffusing plate. It is a principal part side view explaining the structure of the conventional light diffusing plate.

Explanation of symbols

10, 50 Light diffusing plate, 11a, 11b, 11c, 11d, 51a, 51b, 51c, 51d,... Recessed part, 12a, 12b, 12c, 12d, 52a, 52b, 52c, 52d,. 21 light source, 22 optical system

Claims (22)

A light transmitting body that transmits incident light,
A light transmissive body, wherein a plurality of recesses are formed on at least one interface. The concave portion is formed on the light emitting side,
The light transmitting body according to claim 1, wherein a plurality of convex portions corresponding to the concave portions are formed on the light incident side.   The light transmitting body according to claim 1, wherein the concave portion has a partial shape of a substantially spherical inner surface.   2. The light transmitting body according to claim 1, wherein the light transmitting body is manufactured by inverting an original plate constituted by laying micro convex lenses on a predetermined base material.   The light transmitting body according to claim 4, wherein the light transmitting body is manufactured by applying a predetermined resin on the original plate and peeling off a predetermined film coated on the resin.   The light transmitting body according to claim 5, wherein the resin is an ultraviolet curable resin. The film is a polyethylene terephthalate film,
The light transmitting body according to claim 6, wherein the polyethylene terephthalate film is peeled off by irradiating ultraviolet rays on the polyethylene terephthalate film coated on the ultraviolet curable resin.   7. The light according to claim 6, wherein instead of the film, a mount of a light diffusing plate configured by laying micro convex lenses on a predetermined base material is used, and the ultraviolet curable resin is applied to the mount side. Permeant.   The light transmitting body according to claim 1, wherein the concave portion has a partial shape on the inner surface of the spheroid.   10. The light transmitting body according to claim 9, wherein the light transmitting body is manufactured by inverting an original plate configured by laying micro convex lenses on a predetermined base material.   A predetermined resin is applied on the original plate, and a predetermined resin solution is applied onto the concave group produced by peeling off the predetermined film coated on the resin, and the application surface is set downward to solidify. The light transmissive member according to claim 10, wherein the light transmissive member is manufactured using a mold manufactured by the method.   The light transmitting body according to claim 11, wherein the mold is a synthetic resin mold or an electroforming mold. The mold is made using a stretchable material,
12. The light according to claim 11, wherein the mold is manufactured using temporary molds that extend in a direction orthogonal to the major axis direction of the spheroid and have different sectional shapes of the recesses perpendicular to the interface and orthogonal to each other. Permeant.   The light transmitting body according to claim 13, wherein the light transmitting body is manufactured using a main mold transferred twice based on the temporary mold.   The light transmitting body according to claim 13, wherein the ratio of the major axis to the minor axis of the ellipse, which is the shape of the stretched interface, is 1.2 to 2.0.   The light transmitting body according to claim 10, wherein the light transmitting body is manufactured using a mold manufactured by applying a predetermined resin solution on the original plate and solidifying the coating surface downward.   The light transmitting body according to claim 16, wherein the mold is a synthetic resin mold or an electroforming mold. The mold is made using a stretchable material,
17. The light according to claim 16, wherein the mold is manufactured using temporary molds that extend in a direction orthogonal to the major axis direction of the spheroid and have different sectional shapes of the recesses perpendicular to the interface and orthogonal to each other. Permeant.   The light transmitting body according to claim 18, wherein the light transmitting body is manufactured using a main mold transferred twice based on the temporary mold.   19. The light transmitting body according to claim 18, wherein the ratio of the major axis to the minor axis of the ellipse that is the shape of the stretched interface is 1.2 to 2.0. A light diffusing plate for diffusing incident light,
A predetermined substrate;
A light diffusing plate, comprising: a light transmitting body having a plurality of recesses formed on at least one interface of the substrate. A projector device screen for projecting image light from the projector device,
A predetermined substrate;
A projector device screen, comprising: a light diffusing plate having a light transmitting body in which a plurality of recesses are formed on at least one interface of the substrate.