KR100361500B1 - Rear screen video projection system - Google Patents

Abstract

The rear projection screen of the projection system according to the present invention comprises: a sheet for focusing incident light; And a lenticular lens having an incident side having a plurality of curvatures and an exit side having an exit angle of the incident light being adjusted by the plurality of curvature regions on the incidence side to increase the transmittance of the light incident through the sheet. There is a characteristic in that.

In addition, according to the present invention as described above, the incidence side of the lenticular lens is composed of a plurality of aspherical regions to improve the processability of the lens, it is possible to widen the wide viewing angle,

In addition, it provides an effect that can improve the brightness and contrast of the image.

Description

Rear projection video screen of projection system {Rear screen video projection system}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection screen of a projection system. In particular, the present invention relates to a projection system in which a vertical viewing angle of a lenticular lens used in a projection screen is enlarged and light efficiency is improved to obtain a bright image and a small pitch. Relates to a rear projection screen.

Recently, with the development of the information industry, the demand for image display means having a larger screen is increasing. However, in the case of a TV receiver, which has been a conventional general image display means, a realistic limitation is required to manufacture a cathode ray tube itself in order to enlarge the screen. Due to factors, there is a limit to enlargement.

Accordingly, in recent years, as the demand for large-screen high-definition images increases, the spread of projection-type devices that enlarge and project small images by using a projection lens is rapidly spreading in display devices. Projection type devices can be divided into rear projection method and front projection method according to the projection method, and the rear projection method is more widely used due to the advantage of seeing a bright screen even in a bright environment. In order to widen the viewing angle in the horizontal and vertical directions, a lenticular lens sheet having a cylindrical shape on both sides is generally used.

In the rear projection method of the projection system as described above, research efforts are being actively conducted to improve the brightness and the viewing angle in order to provide a brighter image.

1 is a view for schematically showing a rear projection apparatus of a general projection system.

Referring to FIG. 1, light emitted from the illumination system 101 passes through the panel 102 and then is projected onto the projection screen 105 via the projection lens 103.

2 is a view showing in detail a lens unit constituting a projection screen in a rear projection screen of a conventional projection system.

Referring to FIG. 2, a lens of a rear projection screen of a projection system includes a fresnel lens 201 for focusing light emitted from an illumination system and a lenticular for diffusing light passing through the fresnel lens 201. (Lenticular) lens 202.

In addition, the lenticular lens 202 has a cylindrical lens 203 formed on the incident side, and an emission-side cylindrical lens 204 is formed on the condensing side of the exit side, and the non-condensing part of the exit side has a black stripe ( Black Stripe) 205.

3 is a view showing that light passing through a conventional lenticular lens having the above configuration is diffused.

However, the rear projection screen of the conventional projection system having the above configuration has a limitation in widening the projection angle with a lenticular lens having a single shape. In detail, the projection in the horizontal direction by using the sectional lenticular lens as in the prior art will be described. The range is narrowed to ± 30 degrees, and a light diffusing agent is added to the lenticular lens 202 in a manner to enlarge the narrow horizontal viewing angle and the vertical viewing angle. Narrower than ± 35 degrees, and the more the light diffusing agent is used, the more scattered light is reflected by the backscattered light reflected back to the incident surface of the lenticular lens 205, thereby reducing the overall light transmittance and decreasing brightness. There is a problem.

In addition, when the lenticular lens has a shape having one curvature as in the related art, the half angle at the lenticular end Becomes small. The smaller the half angle, the more difficult the machining of the mold shape during processing, and the worse the degree of processing, the greater the scattering of the end region, resulting in a decrease in the transmittance of incident light and a reduction in the viewing angle.

The present invention has been made to solve the above problems, and the incidence side of the lenticular lens constituting the rear projection screen of the projection system is composed of various shapes having different curvatures, and the diffusion agent for expanding the horizontal and vertical viewing angles. The purpose of the present invention is to provide a rear projection screen of a projection system having a wide light viewing angle and a bright screen by diffusing the light into the lens and minimizing the area on the lens exit side with black stripe.

1 shows a rear projection device of a typical projection system.

2 shows schematically a rear projection screen of a conventional projection system.

3 is a view showing that light incident on a lenticular lens constituting a rear projection screen of a conventional projection system is emitted through the lens;

4 is a view showing the configuration of the lenticular lens constituting the rear projection screen of the projection system of the present invention and the incident light is emitted through the lens.

5 is a graph showing a formula for implementing the aspherical shape of the lenticular lens shape of the present invention.

6 is a view for explaining the total reflection phenomenon at the exit side of the lenticular lens;

<Description of the symbols for the main parts of the drawings>

101 ... lighting system 102 ... panel

103 ... projection lens 104 ... magnified projection light

105 ... Projection screen 201 ... Fresnel lens

202 ... lenticular lens sheet 203,302,602 ... lenticular lens incident side

204,303,403,603 ... lenticular lens exit side

205,404 ... Black stripe 301,401,601 ... Lenticular lens

402-1 ... first area 402-2 ... second area

402-3 ... Third Area

In order to achieve the above object, a rear projection screen of a projection system according to the present invention comprises: a sheet for focusing incident light; And a lenticular lens having an incident side having a plurality of curvatures and an exit side having an exit angle of the incident light being adjusted by the plurality of curvature regions on the incidence side to increase the transmittance of the light incident through the sheet. It is characterized by that.

Preferably, the light diffusing agent is included in the inside and the output side of the lenticular lens.

In addition, a black stripe is coated on an area of the emission side of the lenticular lens where no light is emitted.

4 is a view showing the configuration of the lenticular lens constituting the rear projection screen of the projection system of the present invention.

4, the rear projection screen of the projection system of the present invention is a fresnel lens (not shown) for condensing the projection light (not shown) and the divergent light of the enlarged image to brighten the entire screen in the viewing range region. And the lenticular lens 401, and the lenticular lens 401 again has the incident side (region 1 402-1, region 2 402-2, and region 3 402-3 having different curvatures). 402 is comprised and it is set as the structure covered by the black stripe 404 except the emission side 403 from which light is radiate | emitted.

The rear projection screen of the projection system of the present invention configured as described above will be described in detail with reference to FIG. 4 with reference to the lenticular lens 401.

The shape of the lenticular lens of the present invention was configured as an aspherical shape, the aspherical shape was implemented by the following equation.

In Equation 1, X is a Seg value for an aspherical surface at a height r from an optical axis, c is a curvature of a lens surface, and k is a Conic constant. In addition, the incidence side shape may be configured as a spherical shape having a conic constant k of 0 in consideration of the ease of mold and production

In addition, Figure 5 is a diagram showing the above equation as a graph.

When the lenticular lens has a shape with one curvature as in the prior art, the half angle at the lenticular end Becomes small. The smaller the half angle, the more difficult the machining of the mold shape during processing, and the worse the degree of processing, the greater the scattering of the end region and the lower the transmittance of incident light. In order to prevent scattering and to enlarge the viewing angle, the pitch of the lenticular lens is divided into the area 1 (402-1), the area 2 (402-2), and the area 3 (402-3), which are emitted to the exit side for each area. The spread angle, which determines the area of light and the viewing angle, was made to be as constant as possible.

A lenticular lens having a plurality of regions having different curvatures on the incident side as described above will be described in more detail with reference to FIG. 4.

First, the light incident on the aspherical lenticular lens of the region 1 402-1 is focused at the first focal point of FIG. 4 and then evenly passes through the center portion including the edge region of the emission side 403. . In particular, the distribution of light causes the density to increase from the center to the edge.

Further, the light incident on the aspherical lenticular lens of the region 2 is focused on the second focal point of FIG. 4 and then passes only the edge region of the emission side 403 (most edge portion of the emission beam of region 1) and a portion of the inner region thereof. To help. In other words, the density of light passing through the center of the exit side 403 is very small or absent.

Finally, the light incident on the aspherical lenticular lens of region 3 is concentrated at the third focal point of FIG. 4 and then concentrated in the edge region of the emission side 403 (most edge portion of the emission light of region 1).

In addition, in the emission side 403 region, the light entering the emission side is internally reflected to avoid the total reflection region in which the emission side region cannot be emitted.

FIG. 6 is a view for explaining a total reflection phenomenon of light at the exit side of the lenticular lens. FIG.

Hereinafter, the total reflection phenomenon at the lenticular lens exit side will be described in more detail with reference to FIG. 6.

First, the total internal reflection condition from the lenticular resin to the air layer follows the following equation.

In Equation 2 Is the angle of incidence of the incident light Is the refractive index of the lenticular resin. here, end Larger internal reflections will occur.

Therefore, the angle incident on the exit side in consideration of the refractive index of the lenticular resin and the curvature of the lenticular lens ( ) If it is made smaller, total internal reflection of incident light can be prevented.

Further, in order to further expand the horizontal and vertical viewing angles of the rear projection screen of the projection system of the present invention, the light diffusing agent is distributed inside or on the exit side of the lenticular lens constituting the rear projection screen.

In distributing the light diffusing agent to the lenticular lens as described above, very small amount of the light diffusing agent is distributed in the shape of the lenticular lens on the incidence side in order to increase the diffusion characteristics and transmittance, and about 5 to 20% of the light diffusing agent on the exit side. Distribute.

Here, the reason for distributing a small amount of light diffusing agent on the incident side and a large amount on the exit side is that when a large amount of light diffusing agent is distributed on the incident side, the amount of light reaching the exit side is reduced. This is for distributing a large amount of the light diffusing agent on the exit side to increase the light diffusion on the exit side.

In addition, black stripe is applied to the entire region in the region where light is not emitted among the exit side of the lenticular in order to prevent the external light from falling off due to reflection and diffusion of the diffusing agent and the lenticular resin. .

As described above, the present invention has been described only in the case of having three regions having different curvatures on the incidence side of the lenticular lens. However, the number of regions may be adjusted as many as necessary for the user.

As described above, according to the rear projection screen of the projection system of the present invention, the incidence side of the lenticular lens can be configured with a plurality of aspherical regions to improve the processability of the lens and widen the viewing angle of the screen.

In addition, there is an effect that can improve the brightness and contrast of the image.

Claims (6)

A sheet for focusing incident light; And a lenticular lens having an incident side having a plurality of curvatures and an exit side having an exit angle of the incident light being adjusted by the plurality of curvature regions on the incidence side to increase the transmittance of the light incident through the sheet. Rear projection screen of a projection system. The method of claim 1, And the curvature of the incidence side of the lenticular lens is symmetric about the center. The method of claim 1, Rear projection screen of the projection system, characterized in that a light diffusing agent is added to the inside or the exit side of the lenticular lens The method of claim 1, The rear projection screen of the projection system, characterized in that the black stripe is applied to the area where the light is not emitted out of the exit side of the lenticular lens. The method of claim 1, The rear projection screen of the projection system, characterized in that the distribution of light on the emission side is adjusted by the plurality of areas formed by the curvature of the incident side, respectively. The method of claim 1, A rear projection screen of the projection system, characterized in that the exit side avoids the total reflection region where the incoming light is internally reflected and exits to the exit side region.