Liquid-crystal display lighting system (alternatives)

FIELD: liquid-crystal displays.

SUBSTANCE: proposed liquid-crystal display lighting system has sequentially disposed light source, optical system, optical film, polarization film, and microprism film; optical film is made of transparent material and has at least one optical element incorporating first refracting surface and opposing interconnected second refracting surface and reflecting surface, as well as side surfaces; light source is designed to generate diverging light beams; microprism film is designed to pass some portion of light beams through desired aperture and to reflect some portion of light beams in direction of reflecting surface whose external aperture is practically equal to that of first refracting surface; internal aperture equals that of second refracting surface; reflecting surface is designed to partially depolarize some portion of light reflected by polarization plate and for reflecting this portion of light and some portion of light beams reflected by microprism plate to polarization plate.

EFFECT: reduced angular aperture, enhanced light efficiency.

14 cl, 6 dwg

 

The invention relates to the field of optics, namely, lighting systems, liquid crystal display (LCD) displays, and can be used for the manufacture of LCD displays.

In General, the device of the LCD backlight works as follows. The beam emanating from the light source enters the optical system, which serves for uniform brightness distribution on the surface of LCD panel display. LCD panel works effectively only with linearly polarized light at the input in strictly defined within the angular aperture. Therefore, the light output of the optical system must be polarized and must be limited angular aperture (in most existing systems the angular aperture does not exceed +/-35°) for the most efficient use of light.

In systems with lateral illumination this optical system is called the light guide plate, which provides a diffuse scattering of light at the entrance to the LCD panel. Special optical film, such as film double increase brightness (DBEF) in U.S. patent No. 6760175, widely used for more efficient use of light in the lighting systems of the LCD display.

These films contain a polarizing film which transmits only one polarization component (passing rays are scattered in the angular aperture is, not exceeding 16°) and diffusely reflects the other polarization component. You can increase the optical efficiency of the backlight to the LCD panel through the use of penetrates behind the polarizing film for a partial depolarization of the reflected light and for directing it back to the polarizing film. In systems with lateral illumination for this purpose, for example, often use a mirror located behind the light guide plate.

In the General case, the system of the LCD backlight includes a light source, optical system, optical film, penetrating and a polarizing film.

Closest to the claimed invention is a backlight of the LCD display, is described in U.S. patent No. 6876408. This system includes an optical film that includes the first convex refracting surface and located opposite a second refractive and reflective surfaces connected to each other and made a single flat surface, and the reflecting surface is made diffuse. This system is chosen as the prototype of the claimed invention.

The disadvantage of the prototype is the lack of effective multiple reflections of the radiation in the direction of the polarizer, and the inability to provide limited angles of the th aperture at the entrance polarizer and as a consequence, the low efficiency of light at the entrance to the LCD panel.

Objective of the claimed invention is to provide a backlight LCD display with high optical efficiency by providing partial depolarization penetrating light while providing limited angular aperture at the entrance to the LCD panel.

The technical result of the claimed invention is to reduce the angular aperture of the light beam through the use of two refractive surfaces and the increase in luminous efficiency due to the use of a reflective surface, providing a partial depolarization of the reflected light and its effective reflection in the direction of the LCD panel.

For a better understanding of the present invention the following is a detailed description with the appropriate drawings.

Figure 1 - scheme of the backlight of the LCD monitor with microprism film made according to the invention.

Figure 2 - scheme of the optical film with a flat reflecting surface made according to the invention.

Figure 3 - diagram of the optical film with a reflective surface, made in the form of a surface of the second order according to the invention

4 is a diagram of the system operation of the backlight of the LCD monitor without microprism film made according to the invention.

Figure 5 - the number of the optical film with a reflective and second refractive surfaces, made in the form of surfaces of the second order and having a different radius of curvature according to the invention.

6 is a diagram of the optical film with a reflective and second refractive surfaces, in the form of surfaces of the second order and have the same radius of curvature according to the invention.

In the first case (Figure 4) backlight LCD monitor 1 containing the LCD panel 2 includes a light source 3, the optical system 4, the optical film 5, a polarizing film 6. In the second case (Figure 1), the system further comprises a microprism film 7 disposed between the polarizing film 6 and the LCD panel 2.

In both cases (Fig 1, 2) illumination system 1 projects a polarized light with a limited angular aperture at the input of the LCD panel 2. The optical film 5 is an array of optical elements 8. Each optical element 8 includes the first refractive surface 9, the second refracting surface 10 and the reflective surface 11 and is filled with an optically transparent material (e.g. polycarbonate). Diverging beam 12 emitted by the radiation source 3, and redistribute colliery using the optical system 4, thereby providing a uniform distribution of brightness in the LCD panel 2. Cross-section of the collimated beam 13 extending from the op is practical system 4, reduced first refractive surface 9. Then the beam 13 passes through the refractive surface 10, the aperture of which is considerably smaller than the aperture of the first refracting surface 9 and is approximately equal to the cross section of the beam 13. The beam 13 is refracted a second refractive optical surface 10 and leaving the optical element 8 of the optical film 5, falls on the polarizing film 6. Part of this beam with the desired state of polarization) with virtually no dispersion passes through the polarizing film 6.

In the first version of the system (Figure 1) after passing through the polarizing film 6, the beam is directed to microprism film 7 (beam 16). The remaining 14 (with orthogonal state of polarization) is dissipated in the reflection polarizing film 6 and again falls on the film 5. The beam 16, the last in the direction of the microprism film 7 has a significant divergence. Microprism film 7 flows in the direction of the LCD panel 2 beams with limited angular aperture 18, a portion of the beams 17 is reflected back in the direction of the polarizer 6 and the optical film 5. The reflective surface 11 is designed for reflections and partial depolarization of the beam 14 and the beam 17. The reflective surface 11 has an external aperture, which is almost equal and erture first reflective surface 9. The internal aperture of the reflective surface 11 is almost equal to the aperture of the second refracting surface 10. The ratio of the area of the aperture of the first refracting surface and the square aperture of the second refracting surface should be large enough to ensure a high efficiency of light reflected by a polarizing film 6.

In the second variant of the system (Figure 4) after passing through the polarizing film 6, the beam is directed to the LCD panel 2.

In the first version of the system reflecting surface 11 of the optical film 5 is made flat (Fig.1-3), and the second refracting surface 19 is made either flat (Fig 1, 2), or convex (Figure 3), thus providing the possibility of reducing the distance between the optical film 5 and the polarizer 6 while maintaining uniform irradiation of the surface of the polarizer (3).

In the second variant of the system (Figure 4-6) of the refractive surface 9 and 20 serve to reduce the angular aperture of the beam of rays 13, the reflective surface 21 serves to reduce the angular aperture of the beam 22 reflected from the polarizer 6 (beam 23). The reflective surface 21 can be calculated in the assumption that there is a point light source 24 of the scattered radiation on the surface 25 polarizing film 6 in the center of the cross section of the beam 13 (Figure 4). To the floor is to build a collimated beam after reflection from the reflective surface 21, this surface should be the surface of the second order - the paraboloid. In addition, the first and second refractive surfaces may be a telescopic system, directing the collimated beam to the input polarizing film 6. This is the best way to provide limited angular aperture at the entrance of the LCD panel 2. In addition, the second refracting surface 27 and the reflective surface 21 may have one form (6). This film is the most technologically advanced, while providing limited angular aperture of the beam of rays at the entrance to the LCD panel 2.

Thus, the use of a claimed system illumination allows to increase the light efficiency of the backlight of the LCD panel 2 by providing a high efficiency radiation reflected polarization and microprism film, as well as providing polarized radiation with limited angular aperture at the entrance to the LCD panel.

The above embodiment of the invention has been set forth to illustrate the present invention, and professionals it is clear that various modifications, additions and substitutions, without departing from the scope and meaning of the present invention disclosed in the accompanying claims.

1. Backlight LCD display containing I is i.i.d. sequence, the light source, optical system, optical film, polarizing film and microprism film, thus the optical film is made of svetopropusknaya material and has at least one optical element that includes the first refractive surface and located opposite to it and connected the second refracting surface and reflecting surface, and side surfaces, and the light source is configured to generate a divergent beam, the optical system is arranged to reduce the angular aperture of the beam and the projection beam with a small angular aperture on the first refractive surface, which is made in the form of a surface of the second order with the possibility of reducing the cross-section of the incoming light beam with a small angular aperture due to refraction, and focusing this beam on the second refractive surface, the second refractive surface is made flat, and the aperture of the second refracting surface is much smaller than the aperture of the first refractive surface and the second refractive surface is made with the possibility of sending a beam on a polarizing plate, which is made with the possibility of transmission of part of the beam with the desired state is receiving polarization microprism film, and diffuse reflection part of the world with the state of polarization perpendicular to the desired, on the reflective surface, with microprism film made with the possibility of transmission of part of the beam with the desired aperture and the reflection side of the beam in the direction of the reflective surface, the outer aperture which is almost equal to the aperture of the first refracting surface, and an inner aperture is equal to the aperture of the second refractive surface and the reflective surface is configured to partial depolarization of the light, reflected by a polarizing plate, and the reflection of this part of the world and part of the beam reflected microprism plate, polarizing plate.

2. The system according to claim 1, wherein the first refractive surface, the second refracting surface and a reflecting surface is symmetrical about one axis.

3. The system according to claim 1, wherein the first refractive surface, the second refracting surface and a reflecting surface is symmetrical with respect to the same plane.

4. The system according to claim 1, characterized in that the optical elements of the film are interconnected by lateral surfaces.

5. The system according to claim 1, characterized in that as svetopropusknaya material of the optical film is used polycarbonate.

7. The system according to claim 1, characterized in that the second refracting surface of the optical film is made in the form of a plane.

8. The system according to claim 1, characterized in that the second refracting surface is a surface of the second order.

9. Backlight LCD display containing consistently placed on the light source, optical system, optical film, polarizing film, thus the optical film is made of svetopropusknaya material and has at least one optical element that includes the first refractive surface and located opposite to it and connected the second refracting surface and reflecting surface, and side surfaces, and the light source is configured to generate a divergent beam, the optical system is configured to collimate the beam and the projection beam with a small angular aperture on the first refractive surface, which is made in the form of a convex surface of the second order with the possibility of reducing the cross-section of the incoming light beam with a small angular aperture due to refraction, as well as projection Yes the aqueous beam on the second refracting surface, the second refractive surface is made in the form of a concave surface of the second order, in this case the aperture of the second refracting surface is much smaller than the aperture of the first refractive surface and the second refractive surface is made with the possibility of sending a beam on a polarizing plate, which is made with the possibility of transmission of part of the beam with the desired state of polarization and diffuse reflection part of the world with the state of polarization perpendicular to the desired, on the reflective surface, the reflective surface is made in the form of a concave surface of the second order, while its external aperture is almost equal to the aperture of the first reflective surface and the inner aperture is equal to the aperture of the second refracting surface and reflecting surface made with the possibility of partial depolarization of the light, reflected by a polarizing plate, and the reflection of this part of the world on the polarizing plate.

10. The system according to claim 9, wherein the first refractive surface, the second refracting surface and a reflecting surface is symmetrical about one axis.

11. The system according to claim 9, wherein the first refractive surface, the second refracting surface and reflecting surface symmetric otnositel the same plane.

12. The system according to claim 9, characterized in that as svetopropusknaya material of the optical film is used polycarbonate.

13. The system according to claim 9, characterized in that the first and second refractive surfaces are telescopic system, the guide colliercounty beam of light input polarizing film.

14. The system according to claim 9, characterized in that the reflecting surface is made in the form of a paraboloid.



 

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