Projection screen

A projection screen includes a reflection layer, a light absorbing structure, a plurality of light diffusion layers, and a lens structure. The light absorbing structure is disposed on the reflection layer and has a plurality of apertures. A part of the reflection layer is exposed via the apertures. The light diffusion layers have a first index of refraction. Each of the light diffusion layer is disposed in the corresponding aperture and contacts the corresponding reflection layer exposed via the corresponding aperture. The lens structure is disposed on the light diffusion layers and the light absorbing structure. A light incidence side of the lens structure includes a plurality of convex lenses. The convex lenses are respectively corresponding with the light diffusion layers. The lens structure has a second index of refraction, and the second index of refraction is smaller than the first index of refraction.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The invention relates to a screen, and especially relates to a projection screen.

(2) Description of the Prior Art

Projection screen is a kind of optics screen used to diffuse projection light from a projector. When direction of the projection light and the luminous flux are fixed, the ratio between luminance of the light reflected by the projection screen and the ideal luminance acceptable by eyes is defined as a luminance coefficient in the direction of the light reflected by the projection screen. The maximum luminance coefficient is defined as the gain of the projection screen, representing the reflection capacity of the projection screen. Generally, to enhance image viewing angle, contrast, and gain, the projection screen is not only required to diffuse the projection light of the projector, but also required to eliminate interference of external light to avoid influence on the image contrast.

FIG. 1is a schematic view of a conventional reflective front projection screen100. Referring toFIG. 1, an opaque substrate110is disposed on the bottom layer of the reflective front projection screen100. A transparent glass ball structure120, and two transparent material layers130and140with different but similar indexes of refraction are disposed on the opaque substrate110orderly. A lens structure150composed by a plurality of lenses arranged continuously is disposed on a surface of the transparent material layer140. One surface of the lens structure150is covered by a black shield layer160.

After entering the projection screen100from another surface of the lens structure150, a projection light R first passes the two transparent material layers130and140with different indexes of refraction, and then enters the glass ball structure120. For the bottom layer of the projection screen100is an opaque base110, the projection light R may be reflected or absorbed. The reflected beam may pass through the glass ball structure120, and exit out of the projection screen100along an emergent light path R2or R3. The glass ball structure120may diffuse the emergent light to increase the image viewing angle. Moreover, the black shield layer160on the lens structure150may absorb external miscellaneous light O to avoid the image contrast reducing by the influence of the external miscellaneous light O.

FIG. 2is a schematic view of another conventional reflective front projection screen200. Referring toFIG. 2, an opaque base210is disposed on bottom layer of the reflective front projection screen200. A transparent glass ball structure220, and two transparent material layers230and240with different but similar indexes of refraction are disposed on the opaque substrate210orderly. A surface250of the transparent material layer240is fabricated into a plane structure.

After entering the projection screen200from the surface250of the transparent material layer240, a projection light L first passes the two transparent material layers230and240with different indexes of refraction, and then enters the glass ball structure220. For the bottom layer of the projection screen200is an opaque base210, the light beam L may be reflected or absorbed. The reflected beam passes through the glass ball structure220, and exits out of the projection screen200along an emergent light path L2or L3. The glass ball structure220may diffuse the emergent light to increase image viewing angle.

However, the reflective front projection screens100and200have following questions respectively:

Firstly, the lens structure150of the reflective front projection screen100inFIG. 1uses the black shield layer160to absorb the external miscellaneous light O, but a part of the emergent light, such as the emergent light along the emergent light path R2, may be absorbed by the black shield layer160, thus light emergent efficiency and the gain of the projection screen may be decreased.

Secondly, though the fabrication of the reflective front projection screen200inFIG. 2is quite simple, it may not prevent the miscellaneous light O. For example, the external miscellaneous light O may enter the projection screen200from the emergent light path L2or L3to decrease the image contrast.

Thus, how to increase the image contrast and the gain of the projection screen is an urgent problem in the technology field.

SUMMARY OF THE INVENTION

Accordingly, the object of the present invention is to provide a projection screen adapted to promote the reflective effect of the projection light from the projector to increase the gain and to abate the external miscellaneous light reflected to the viewer to make the contrast of the projection image better.

In order to achieve one or part of or all the objectives, or to achieve other objectives, the embodiment of the present invention provides a projection screen including a reflection layer, a light absorbing structure, a plurality of light diffusion layers, and a lens structure. The light absorbing structure is disposed on the reflection layer and has a plurality of apertures. A part of the reflection layer are exposed via the apertures. The reflection layer is adapted to reflect a light beam and does not diffuse the light beam.

The light diffusion layers have a first index of refraction. The light diffusion layers are disposed on the same level and on the reflection layer, and each of the light diffusion layers is disposed in the corresponding aperture of the light absorbing structure. Each of the light diffusion layers contacts the corresponding reflection layer exposed via the corresponding aperture. Besides, each of the light diffusion layers has a sand blasting surface to achieve diffusion efficacy, or each of the light diffusion layers has a plurality of light diffusion particles to achieve the same. The light absorbing structure has a plurality of protruding structures disposed on the surface of the light diffusion layers.

The lens structure is disposed on the light diffusion layers and the light absorbing structure. A light incidence side of the lens structure includes a plurality of convex lenses. The convex lenses are corresponding with the light diffusion layers respectively. The lens structure has a second index of refraction, and the second index of refraction of the lens structure is smaller than the first index of refraction of the diffusion layers. Moreover, the focus of each of the convex lenses is located under the reflection layer. The convex lenses are selected from the group consisting of a sphere lens, a paraboloid lens, a polyhedron lens, and a column lens.

In order to achieve one or part of or all the objectives, or to achieve other objectives, the embodiment of the present invention provides a projection screen including a reflection layer, a light absorbing structure, a plurality of light diffusion layers, and a lens structure. The light absorbing structure includes a plurality of light absorbing layers disposed on the reflection layer and having a interval between two opposite light absorbing layers. A part of the reflection layer is exposed via the intervals. Each of the light absorbing layers may be a column with a square section or a taper section and protrudes out of the surfaces of the light diffusion layers.

A plurality of light diffusion layers are disposed on the same level and on the reflection layer, and each of the light diffusion layers is disposed in the corresponding interval and connects adjacently to the corresponding light absorbing structure.

The lens structure is disposed on the light diffusion layers and the light absorbing structure. A light incidence side of the lens structure includes a plurality of convex lenses corresponding with the light diffusion layers respectively. The lens structure has a second index of refraction, and the second index of refraction is smaller than the first index of refraction. Each of the convex lenses is disposed right on the corresponding light diffusion layer.

Comparing with the conventional reflective front projection screen, the light absorbing structure of the embodiment of the present invention may absorb the miscellaneous light effectively to improve the image contrast. The lens structure may converge the projection light from the projector to enhance the brightness. The projection light after being brightened is diffused by the light diffusion layer or reflected after entering the reflection layer to increase the brightness and the image viewing angle of the emerged light from the projection screen.

Above all, the reflective front projection screen of the embodiment of the present invention may not only increase the image contrast, enhance the gain of the projection screen, but also improve the image viewing angle. Thus, the embodiment of the present invention may enhance the visual effects of the sense of the viewer.

DESCRIPTION OF THE PRESENT EMBODIMENTS

Referring toFIG. 3,FIG. 3is a schematic view of the first embodiment of the projection screen300according to the present invention. AsFIG. 3shows, the projection screen300includes a reflection layer310, a light absorbing structure320, a plurality of light diffusion layers330, and a lens structure340. The light absorbing structure320and the light diffusion layers330are disposed on the reflection layer310, and the lens structure340is disposed on the light absorbing structure320and the light diffusion layers330. Notably, the light diffusion layers330are disposed on the same level and on the reflection layer310. The light diffusion layer330and the lens structure340are both transparent. The index of refraction of the lens structure340is smaller than the index of refraction of the light diffusion layer330.

Moreover, the light absorbing structure320of the projection screen300may have a plurality of protruding structures disposed on the surface of the light diffusion layers330. Refer toFIG. 3Afor a schematic view showing the section of the second embodiment of the projection screen301according to the present invention andFIG. 3Bfor a schematic view showing the section of the third embodiment of the projection screen302according to the present invention. The protruding structures321and322of the light absorbing structure320of the projection screens301and302are columns with square section and taper section separately. There are apertures (not shown) formed between columns.

Refer toFIG. 4Afor a c-c′ sectional view of an embodiment of the projection screens300,301, and302inFIG. 3,FIG. 3A, andFIG. 3B. The light absorbing structure320is disposed on the reflection layer310, and has a plurality of the apertures380. The light absorbing structure320is used to absorb the external miscellaneous light O for enhancing the image contrast, and a part of the reflection layer310is exposed via the apertures380. Noticeably, the reflection layer310is suitable for reflecting projection light without being diffused, and has no light diffusion material and light diffusion structure so as to ensure reflecting the projection light R out of the projection screen300, for instance, the emergent light paths R1, R2, and R3. The light diffusion layers330are filled in the apertures380of the light absorbing structure320by filling technology respectively, and contact the exposed part of the reflection layer310. In other words, each of the light diffusion layers330is disposed in the corresponding aperture380of the light absorbing structure320.

Refer toFIG. 4Bfor a c-c′ sectional view of another embodiment of the projection screens300,301, and302inFIG. 3,FIG. 3A, andFIG. 3B. The light absorbing structure320has a plurality of light absorbing layers323disposed on the light reflection layer310, and an interval S between every two opposite light absorbing layers323. A part of the reflection layer310is exposed via the interval S. A plurality of the light diffusion layers330are disposed on the reflection layer310, and the light diffusion layers330are filled in the intervals S respectively. Notably, the light diffusion layers330are disposed on the same level and on the reflection layer310. Each of the light diffusion layers330connects adjacently to the corresponding light absorbing structure320, and contacts the corresponding reflection layer310exposed via the corresponding aperture.

Moreover, the light absorbing layer323may be a column protruding out of the surface of the light diffusion layers330, with a square section or a taper section.

AsFIG. 3shows, the light diffusion layers330may be poly-ester, light diffusion particles or their mixture, and has a first index of refraction. In an embodiment, a plurality of light diffusion particles311and poly-ester are mixed to form the light diffusion layers330. When the projection light R is reflected by the reflection layer310and enters the light diffusion layers330, the emergent angle and the path of the reflection light may be changed by the light diffusion particles331to obtain the light diffusion effects. For example, the reflection light emits along the emergent light paths R1, R2, and R3to increase the distribution area of the reflection light so as to raise image viewing angle.

Refer toFIG. 5for a schematic view showing the section of the fourth embodiment of the projection screen500according to the present invention. The surface of the light diffusion layers330is sandblasted to form a rough surface332. After the projection light R is reflected to pass through the rough surface332, the rough surface332diffuses the emergent light, such as along the emergent light paths R1, R2, and R3so as to raise the image viewing angle.

Referring toFIG. 3, the lens structure340is disposed on the light absorbing structure320and the light diffusion layers330. An light incidence side of the lens structure340faces the projector (not shown) and includes a plurality of convex lenses350corresponding with the light diffusion layers330respectively. Each of the convex lenses350is disposed right on the relative light diffusion layer330. The lens structure340has a second index of infraction, and the second index of infraction of the lens structure340is smaller than the first index of infraction of the light diffusion layers330. Thus, when the projection light enters the light diffusion layers330via the lens structure340, the projection light may be refracted to focus in the center of the light diffusion layers330for avoiding the projection light which enters the light diffusion layers330emitting to the light absorbing structure320at two sides and being absorbed by the light absorbing structure320, so that the gain of the projection screen300may be decreased.

In the present embodiment, the focus of each of the convex lenses350is located under the reflection layer310, so that before being focused, the projection light R enters the light diffusion layer330to be diffused and then exits out of the projection screen300. Moreover, after the projection light R is diffused by the light diffusion layer330, the destructive interference in the emergent light paths R1, R2, and R3may be avoided for achieving a better gain of the projection screen300.

Referring toFIG. 6, the convex lens350of the projection screen300inFIG. 3is replaced with the polyhedron lens351.FIG. 7AtoFIG. 7Dare three dimensional views of various kinds of convex lenses352,353,354, and355. In an embodiment, the sorts of the above-mentioned convex lenses350may be a sphere lens352, a paraboloid lens353, a arc column lens354, a polyhedron column lens355, or combinations of above lenses.

Based on the concept of the present invention, other embodiments may be obtained by various combinations of the structure characters of the projection screens300,301,302, and500in above embodiments. For example, the convex lens350of the projection screen301inFIG. 3Amay be changed from the arc lens to the arc column lens354inFIG. 7C, the light diffusion layer330mixed with the light diffusion particles331in the projection screen302inFIG. 3Bmay be replaced by the sandblasted rough surface332inFIG. 5, or the light absorbing structure320of the projection screen500inFIG. 5may be replaced with the protruding structure322inFIG. 3B, etc.

In summary, the embodiment or the embodiments may have at least one of the following advantages:

Firstly, the light absorbing structure may protrude out of the surface of the light diffusion layer to enhance the effect of absorbing external miscellaneous light and to increase the image contrast.

Secondly, by changing the lens structure, the focus of each of the convex lenses is located under the reflection layer. Because the convex lenses corresponds to the light diffusion layer respectively, the destructive interference generated by the projection light during light-emitting process may be avoided and obtain a better gain of the projection screen.

Thirdly, the light diffusion layer is disposed on the reflection layer to make the reflection light pass through the light diffusion layer so as to change the emergent angle and the path of the reflection light for diffusing light and increasing the image viewing angle.