KR20060092501A - An optical sheet and a reflection type high gain projection screen using the same - Google Patents

Abstract

In order to solve the problem that the projected image from one spot light source is different from the center and left and right sides of the reflective screen, the luminance difference is different. Combined adjacently, the optical sheet finely processed into semi-transparent or transparent resin in two pairs of left and right sides and high brightness reflective screen using the same

Optical Sheet, Reflective Screen, Front Screen

Description

Brightness Enhancement Optical Sheet and High Brightness Reflective Screen Using the Same {AN OPTICAL SHEET AND A REFLECTION TYPE HIGH GAIN PROJECTION SCREEN USING THE SAME}

1 is a perspective view of the use of a general projector and a reflective screen and a projection angle.

2 is an illustration of a preferred screen reflection angle.

3 is an exemplary view of light reflection of semicircular embossing and triangular prism sheets.

4 is a horizontal cross-sectional view and a three-dimensional shape view of the luminance-improving optical sheet of the present invention.

5 is a view illustrating an incident angle between a light source projected from a single light source projector and a screen.

6 is an exemplary view of light reflection having a semicircular uneven shape.

7 is a diagram illustrating light reflection when the incident angle of the luminance-improving optical sheet of the present invention is 0 degrees.

8 is an exemplary view of light reflection when the luminance improving optical sheet of the present invention is 15 degrees.

9 is a cross-sectional view of the high brightness reflective screen of the present invention.

10 is a light analysis diagram when the incident angle of the luminance-improving optical sheet of the present invention is 0 degrees.

11 is a light distribution diagram when the incident angle of the luminance-improving optical sheet of the present invention is 0 degrees.

12 is a light analysis diagram when the brightness improvement optical sheet of the present invention is 15 degrees.

13 is a light distribution at 15 degrees of the luminance improving optical sheet of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an optical sheet capable of having the intended optical characteristics through refraction, diffusion, scattering, and reflection of light. When using a projection display such as a projector or a projector, the material of the screen surface is a very important factor that determines the image quality. to be.

In the case of a transmissive screen, a Fresnel sheet is generally adopted to move the light projected from the projector or projector to the viewer in the direction of the viewer, and a light diffuser having a small particle is added to form an image while penetrating the screen. A prism sheet, a lenticular sheet, a lens array sheet, etc., are used for the purpose of concentrating and scattering light to ensure a clear viewing angle toward the viewer.

However, in a reflective screen projecting from the front of the screen, the projector or projector uses a high-brightness projector or projector due to different projection angles between the center of the screen and the left and right sides of the screen while projecting onto the screen using a single light source at one point. When the brightness of the center and the side is severely different, a problem arises, and when the high-brightness reflector is made by forming a glass bead or a micro lens, a micro prism, a glass hemisphere, etc. on the surface to enable retroreflection, the viewing angle becomes narrow or There is a problem that a clear screen can be obtained only at a certain point.

These problems are difficult to manufacture a high-brightness reflective screen that can be used during the day by making it impossible to maximize the reflectance of the reflective surface in the reflective screen and the use of a high brightness image light source.

Among conventional reflective screens, a projector, a curvature spherical screen that forms a whole surface of the screen in consideration of the projection angle of the projector, and provides a high-bright screen image by placing the projector or projector within the focus of the surface is known. In the case of different sizes of screen manufacturing, it is difficult to produce a curved surface, the screen image is formed into a curved surface, it is difficult to select the location of the projector or projector, and the phenomenon that the image formed on the screen is distorted.

In general, in the use of a high-brightness reflective screen, the position where the projector or the projector is used is backed away from the center of the screen, fixed to the ceiling, or used on a table, and the viewer spreads back and forth around the screen. High-brightness reflective displays that use pyramids, lenses, glass beads, micro lenses, and prisms among the reflective screens have strong retroreflective properties, so the clearest screen can be obtained where the projector is installed. The location where there is a problem that can not see the clear screen. This problem occurs more seriously as the reflectance is higher, the brightness of the light source is brighter, the larger the left and right of the screen, and the shorter the screen distance from the light source is.

In general, the projection angle of the projector or projector projecting through one light source, the position of the viewer, the position of the screen, and the like are shown in FIG. 1. When the short throw lens is used for projectors and projectors, the distance between the screen and the light source may be very short, but the image distortion is severe and is not commonly used, and it is generally used within 2 to 5 m.The left and right projection angles (13a) of the light source are 20 degrees from the center. Within, 40 degrees left and right.

In addition, when installed on the ceiling, the light source is installed higher than the screen to generate a viewer's position and a constant vertical angle (13c), which is generally within 20 degrees of the screen. The vertical projection angle can be easily corrected by tilting the projector up or down, tilting the screen up, or by tilting the surface in one direction.

However, the left and right projection angles are different from the center to both the left and right sides, so that in the case of the reflective high gain screen, the center is very bright and darkens toward the periphery. White matte screens with smooth screen surface and low reflectivity do not feel the difference in brightness between the center and the side by reflecting in the forward direction, but the difference in luminance occurs when the reflective surface such as lens or glass is applied to the screen surface. .

In addition, when the screen material having a high reflectance is used, if the viewer's position is wide from side to side, the luminance is different according to the viewer's position, making it difficult to use in various places. Therefore, the light reflection form of the ideal screen should have a reflection angle 21a of about 20 to 45 degrees from the center on all surfaces as shown in FIG.

In the transmissive screen projecting from the rear side, the Fresnel lens, which collects the light projected from the left and right side to the viewer, is arranged on the rear side so that the light can go straight to the viewer's direction. It is difficult because it needs to be manufactured, and when applied to the reflective screen, the projected light passes through the incident and reflected twice, and the scattering layer is required separately to secure the viewing angle. Therefore, the effect of the Fresnel lens sheet cannot be applied. .

 In general, optical sheets are known to form spherical, rectangular, triangular, semi-circular embosses to secure brightness and viewing angle for the purpose of light condensing and scattering on transparent resin sheets. Referring to the reflection patterns of the triangular prism-shaped optical sheet and the semi-circular emboss sheet, which are generally used among the optical sheets, the semi-circular emboss 30a and 30b of FIG. The viewing angle becomes very narrow. Also, in the case of triangular prism shape (31a, 31b), the light source 34a projected from the front side is reflected to the front through the adjacent inclined surface (35a), and the reflection efficiency is very high, but if it goes to the side (34b) in the opposite direction of the incident light source When reflected from the front (35b), the brightness drops sharply. When the hemispherical lens is finely arranged, high condensing and reflection is possible from the front side, but the viewing angle is narrowed due to the lens shape, and the undesired place may be the brightest.

Therefore, when a wide light source is projected from side to side using a single light source, one or more three-dimensional patterns may be finely processed and attached to give optical characteristics in a desired direction on a reflective surface. Basically, the sphere collects light with a specific focus on the incident light source, and has a characteristic of total reflection when the internal scattered light is out of the threshold. The spherical outer surface may have various angles contiguous with the incident light and may be refracted to scatter light. In addition, the triangular prism shape may be focused in a specific direction in consideration of the angle of incidence, and may be directed in a direction in which the internally expressed light is adjusted by adjusting the inclination angle.

Recent projectors use a high light source for daytime without blackouts, and the digital screen improves the aspect ratio to 16: 9, widening the left and right, pursuing larger screens, and wider and larger screens at shorter projection distances. Since the reflective screen has a high reflectance, the reflecting screen has the same reflectance at the center portion and the left and right side portions, and can secure a certain viewing angle and provide uniform luminance.

Therefore, the present invention utilizes the property of going straight, refracting, reflecting, diffusing and scattering of light projected from a single light source, and uniform luminance to a single sheet through incident, refracting, reflecting and scattering at the center and side portions of the reflective screen surface. The present invention provides a luminance improving optical sheet capable of providing a distribution and a high luminance reflective screen using the same.

The present invention relates to the shape of an optical sheet that can be applied to a reflective screen surface, etc., and combines a three-dimensional pattern of a triangle and a sector with a cut surface adjacent to one side thereof, so that two left and right sides are finely formed into one pair. It consists of a vertically processed luminance improved optical sheet and a high luminance reflective screen which is completed by tackifying a luminance improved optical sheet containing a small amount of a small particle diffusion agent on a reflective surface having a high reflectance such as aluminum.

The present invention utilizes the physical properties of the transparent resin, that is, refraction and scattering, and enables uniform luminance distribution over the entire reflective screen surface by using curved, inclined surfaces, and reflective surfaces having high reflectivity of spherical and triangular prisms. . As the reflecting surface of the luminance-improving optical sheet of the present invention, all reflecting surfaces having high reflectivity, such as aluminum, mirrors, sheets coated with reflecting materials, can be applied, and materials such as low reflectance fabrics applied to video display devices are also applicable. If you do this, you can create a video image evenly.

The luminance-improving optical sheet of the present invention forms the same fine pattern on the entire surface of the transparent or semi-transparent resin 40a in FIG. 4 to be refracted and reflected by the light source and go straight at a predetermined angle in the viewer's direction to be the same in the center and side surfaces. Two left (41a, 42a) and right (41b, 42b) pieces are combined by adjacently combining a three-dimensional pattern of triangles 42a and 42b and a fan-shaped (41a and 41b) in the horizontal direction so as to have luminance. It is formed by. When the patterns are arranged adjacent to each other, the cross section has a V-shaped groove formed by interlocking triangles and a Y-shaped groove formed by engaging the hemispheres, and the inclined surfaces 42a and 42b and the curved surfaces 41a and 41b are constantly arranged side to side. And the three-dimensional shape 40b arranged vertically. Inclination angle ta (43c) of the inclined surface, radius cr (45) of the curved surface, center angle ca (43a), arc length cl (41a), thickness t (44) of the sheet, pitch p (47) of the three-dimensional pattern, plastic resin The refractive index n, the reflectance rn of the reflecting surface, etc. may be important factors for determining the brightness improvement effect and the image quality of the brightness improvement optical sheet of the present invention.

The refractive index n of a plastic resin or other transparent material is a very important factor because it is the first refraction and reflection upon incidence and the second refraction while expressing the luminance improving optical sheet of the present invention. The material can be applied, but it is preferable to apply the three-dimensional pattern in consideration of the overall size and pitch, the thickness of the sheet.

The higher the refractive index n and the larger the inclination angle ta, the total reflection of the incident light source on the curved surface and the inclined surface may reduce the reflection efficiency. If the inclination angle is too small, the desired reflection angle may not be obtained. The path of the incident light varies depending on the thickness t of the three-dimensional pattern, so the inclination angle ta must be designed in consideration of the refractive index n of the material.

The larger the center angle ca and the radius cr of the curved surface, the closer to the lens shape may cause a problem of narrowing the viewing angle. Considering the overall shape of the three-dimensional pattern, the thickness t of the sheet and the depth of the pattern (the radius of the surface is the same as the depth of the pattern; cr), the pitch p of the overall pattern can be determined.

In the case of the optical sheet to be applied to the image screen, the projection device has 1024 × 768 pixels and the screen size is 2214mm wide and 1245mm wide based on 100-inch 16: 9 ratio, so the minimum pixel shown is 2.16mm wide. It is preferable to design the depth of the pattern to 200 mu m or less in one dimension, the thickness t of the sheet to be 400 mu m or less, which is a multiple, and the pitch p of the overall three-dimensional pattern to 600 mu m or less.

The reflectance (rn) may vary depending on the purpose of using the optical sheet, but the higher the reflectance is, the higher the luminance can be, but the light transmittance, scattering pattern, etc. of the optical sheet should be taken into consideration. Should be reduced.

In general, plastic resins, which are easy to manufacture, are easy to apply in terms of transmittance and uniformity, and when a material having a specific refractive index is determined, the overall size of the three-dimensional pattern and the refractive index, reflection, and scattering of the optical sheet can be obtained within the optical sheet based on the specific refractive index. By adjusting the thickness, inclination angle, center angle, arc length, etc., it is possible to design a luminance improvement optical sheet with uniform luminance. The light projected by the light source is refracted when the light is incident within the threshold of 36 to 50 degrees in the transparent resin sheet having a refractive index of 1.3 to 1.7, and is reflected on the surface of a highly reflective material, and then touches the curved or inclined surface again so that the light within the critical angle is Secondary refraction and scattering are displayed, and light outside the critical angle is totally reflected in the resin sheet to be scattered, extinguished, or exposed to a specific surface.

In FIG. 5, when the light is projected from a single light source 50 and touches the screen surface 51, light is generated between the surface of the screen as opposed to the center of the light toward the left and right sides. A degree (incident angle of 0 degree) is formed (52), but the angle is widened toward the left and right so that the left and right edges 53c of the screen achieve the maximum angle in general projector or projector use. All light projected from a single light source has a certain angle on the surface where the light hits, and a continuous incident angle is formed from the center to the left and right edges on the screen forming the wide image. However, the maximum angle of incidence on the surface of the screen is within 10 to 20 degrees, depending on the general structure of the projector or projector equipment, with about 15 degrees on one side and 30 degrees on the left and right. The left and right projection angles of the projector or projector are adjustable within a certain range, but not continuously within all ranges. Therefore, it is common to adjust the position of the projector back and forth according to the size of the screen. Since the adjustment of the left and right projection angles remains within a certain range, the incident angle of the screen also falls within a certain range.

FIG. 6 illustrates a light scattering pattern in the form of a vertical stripe semicircular irregularity and a shape of a hemisphere lens array formed on an existing reflective screen surface. In the case of the finely protruded semicircle emboss, when the incident angle is 0 degrees, the light source incident into the semicircle is first refracted, concentrated in the focus by the lens-shaped semicircle, and then reflected and returned to the projected light source direction. The light reflected and scattered toward the projected light source has a very narrow viewing angle within a certain angle depending on the lens shape and thickness.

The shape of hemispherical lens array is formed by coating semi-circular glass flakes on the screen surface. The reflection shape is the same as the hemispherical reflection surface, and the luminance distribution is formed evenly in front of the screen, but the reflection angle is narrow. Since the reflection is concentrated in the direction of the light source, when the projector is installed on the ceiling, there is a problem of creating a maximum brightness near the ceiling where no viewer is present.

 In FIG. 7, when the incident angle of the light source incident on the luminance-improving optical sheet of the present invention is 0 degrees, the light 76a incident on the left curved surface 72 converges to the curved focal point, and is reflected back to the viewer from the curved surface and the inclined plane boundary surface. Scattered within the range of 20 to 30 degrees (77b), the light 76b incident on the left inclined surface 73 is refracted to the left, reflected and touched to the left curved surface 72 to be gathered back to the virtual focus and scattered at a certain angle range The straight 77a in the direction of the viewer inside.

The same incident light 76c on the right inclined plane 74 is refracted to the right, and is reflected and touched to the right curved surface 75 to collect and scatter to a virtual focal point. ) The light 76d incident on the right curved surface 75 is also focused and reflected in the sheet, and reaches the boundary between the right curved surface and the inclined surface to be scattered 77c in the front within a predetermined angle range.

This light scattering distribution is not a form of total reflection in the front, but evenly reflected within the range of less than 30 degrees left and right to prevent excessive glare from the front, there is no problem of dropping the luminance at an excessively wide reflection angle, and the desired viewing angle It can be secured.

In FIG. 8, when the incident angle of the light source incident on the luminance-improving optical sheet of the present invention is 15 degrees (in general, the angle of incidence of the screen edge portion), the light 86a incident on the left curved surface 82 shifts the focus in the sheet to the right. While touching the left inclined surface 83, the scattering (87b) to the front in a predetermined angle range at the bottom of the inclined surface. According to the angle of incidence, the light incident on the left curved surface reflects and moves to the lower portion along the left inclined surface, but has a similar light scattering distribution within the left inclined range.

The light 86b incident on the left inclined surface 83 at 15 degrees is partially reflected by incidence by adding the angle of the inclined surface, and is refracted and reflected to the left, moving to the upper left side of the curved surface, and scattering again while collecting the virtual focal front and front. ) The light 87a scattered from the upper left surface is scattered from the center to the left by a predetermined angle, and the light 86c incident on the right inclined surface 84 is refracted by the angle of incidence due to the angle of the inclined surface, and is reflected by the reflective surface. The light hits the right curved bottom portion 85 and scatters 87d into the right virtual focal space, and some light is partially reduced and dissipated and partially expressed while totally reflecting inside the threshold.

The distribution of the light scattered from the four inclined and curved parts is concentrated within a certain angle range, so that the front reflection efficiency is high, and the luminance is uniformly distributed in the incident angle range within a certain range to create an even luminance distribution across the entire screen.

In the case of the luminance-improving optical sheet of the present invention, the semi-circular uneven vertical stripe embossing sheet having high luminance at the center portion is formed evenly from the center portion to the side surface at about 80% of the front luminance that may be provided. Rather, the frontal luminance increases within a 10% range toward the side, reducing the bright central portion, making it suitable for high brightness reflective screens.

Reflective display devices that can improve luminance, including luminance improvement sheets, can improve the function by adhering to a high brightness screen with a narrow viewing angle, a traffic sign that can be reflected in one direction, and a super large screen on the right and left. A semi-transparent luminance improvement sheet may be adhesively coated on a surface having a high reflectance such as a mirror to be used as a high luminance reflective display device.

The structure of the high-brightness reflective screen to which the luminance-improving optical sheet of the present invention is applied is composed of the luminance-improving optical sheet 90, the light diffusing agent 91, the high-efficiency reflective surface 92, and the supporting surface 93 in FIG. 9.

Reflective screens have a disadvantage in that glare occurs due to excessive reflection when a surface having a high reflectance is used, and images are not formed, and a reduction in viewing angle due to reflection becomes a problem. However, by applying the luminance improving optical sheet, it is possible to secure a viewing angle within the application range of the screen and to display a clear image by using high reflection efficiency.

Light incidence and reflection are equally contained by uniformly including a predetermined amount of light diffusing agent 91 alone or mixed with fine bead particles, aluminum powder, calcite particles, carbon black, graphite, aniline black, cyanine black, and the like, which are known in the luminance improving optical sheet. When scattering, light is diffused from the inside to form a first phase, a second phase is formed on a reflective surface such as aluminum, and light is scattered on a sheet surface to form a third phase, thereby making a clear and bright image.

Although the type and application density of the light diffusing agent may vary depending on the type of reflecting surface, the transparency of the optical sheet, and the thickness of the optical sheet, the even luminance distribution function of the luminance improving optical sheet is not degraded to create a highly efficient reflective screen. Can be. In addition, as the material of the reflecting surface 92 applied to the high-brightness reflective screen of the present invention, it is possible to provide a uniform reflecting surface such as aluminum and mirror, and the particle size is larger than the three-dimensional shape of the luminance improving optical sheet. A fabric in which small glass beads are applied to the surface by a reflective surface in the form of a concave lens is also possible.

In the high luminance reflective screen of the present invention, it is preferable to adhere the luminance improving optical sheet to a hard metal surface, but since it forms a uniform luminance distribution within a predetermined angle, a highly efficient reflecting surface is coated on the surface of the fabric, and the luminance improving optical is applied thereon. The sheet can also be applied to screens that can be glued to rolls up to 40 mm in diameter and released.

For example, a transparent acrylic resin having a refractive index of 1.49 is processed into a 0.2 mm thick sheet, and the length of one three-dimensional pattern, that is, a pitch of 375 µm, a radius of 125 µm, and an inclined surface adjacent to a fan shape having a center angle of 90 degrees has an inclination angle of 45 degrees and a length of An inclined surface of 88.4 µm is connected in a V shape, and the length of the inclined surface is 125 µm. Next to the inclined surface, curved surfaces of the same size are formed adjacent to each other to form a three-dimensional pattern.

The thickness of the supporting resin layer is 75 占 퐉 so as to support the projection portion having a three-dimensional shape as a whole, and to allow light incident on the left mirror surface to be scattered through the adjacent left slope surface while undergoing refraction and reflection of the reflection surface. If the thickness of the supporting resin layer is so large that the incident light is scattered out of the adjacent inclined surface, the scattering pattern is rapidly changed, making it difficult to expect an even luminance distribution.

On the back side of the optical sheet, a reflective surface of high reflectivity, such as aluminum or a mirror, is attached to reflect the incident light so that the incident light source may scatter from adjacent slopes or curved surfaces. The light incident on the optical sheet in the front (incident angle 0 degrees) is concentrated within 36 degrees of the left and right while refracting, reflecting, and scattering. In the same way, the left and right edges of the screen generally have an angle of 15 degrees with the light source, and the incident light at 15 degrees is concentrated within 42 degrees in an acrylic resin sheet having a refractive index of 1.49. The scattering form of the embodiment is shown in FIG. 10 at the front side and at the side surface at FIG. Each light distribution is shown in FIGS. 11 and 13, respectively.

Therefore, the shape of the light emitted from the surface of the luminance improvement sheet is uniformly distributed within about 30 to 45 degrees around the front surface at the center and the left and right sides, and the difference in the reflection angles of the light emitted from the center and the left and right side edges is within 5 degrees. It will move within a very narrow range. Thus, a wide viewing angle is provided to the viewer from side to side with respect to the front of the screen, and uniform luminance is provided.

The effect of the present invention is to reduce the difference in brightness between the central portion and the left and right side portions by using a single sheet of luminance improved optical sheet, thereby enabling a high brightness flat reflective display device using a reflective surface having a high reflectance, and the conventional viewing angle is narrow and the brightness is reduced. Compensating for the disadvantages of not being equal, it is possible to provide a large left and right wide screen with equal brightness.

Like a Fresnel lens, it does not need a prism pattern with concentric circles from the center, so that manufacturing cost can be lowered and it can be easily applied to reflective display devices of various sizes. In addition, it is possible to use as a high-brightness reflective display device by sticking the luminance improvement optical sheet to a mirror or aluminum reflective surface of high reflectance, so that it can be used for large screens, traffic signs, ultra-large TVs, indoor and outdoor advertising structures.

The high brightness reflective screen of the present invention overcomes the disadvantages of the reflective screen and can be used in daytime, so it can be widely used as an image display device by applying a projector and a projector, a space problem of a transmissive screen, a viewing angle problem of a reflective screen, By solving the problem of returning to the light source, the projector can express bright and clear images with a low light quantity projector.

Claims (4)

In an optical sheet that refracts, diffuses, and scatters light in a direction intended as a transparent or translucent material such as glass or plastic resin, a three-dimensional shape having horizontal cross sections on one surface thereof as triangles 42a and 42b and sectors 41a and 41b. By combining the fine patterns of adjacent to each other in a pair of two left and right sides in a vertical process to attach the reflective surface provides a high reflection, uniform luminance distribution, and wide viewing angle in the entire surface within a certain incident angle range Optical sheet, characterized in that The light emitting device of claim 1, further comprising fine light-diffusing particles inside the luminance-improving optical sheet and adhered to a reflective layer having high reflectivity such as aluminum or a mirror as a reflective surface, and having high brightness, the same brightness in the entire surface, and a wide viewing angle. High-brightness reflective screen characterized by having  According to claim 1, wherein the horizontal cutting plane is a triangular and fan-shaped three-dimensional pattern adjacent to each other adjacently formed by dividing the left and right patterns from the center and evenly distributed from the center to the left and right sides Optical sheet, characterized in that The optical sheet according to claim 1, wherein a uniform luminance distribution is possible by vertically arranging three-dimensional fine patterns having a triangular cross section and a sector shape.

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