SMALL-ANGLED, PREDETERMINED-POSITIONED AND PREDETERMINED-ORIENTATED LIGHT EMITTING DEVICE OF BACKLIGHT MODULE OF LIQUID CRYSTAL DISPLAY

• US 20080079870A1
• Filed: 11/14/2007
• Published: 04/03/2008
• Est. Priority Date: 03/29/2004
• Status: Abandoned Application

• Current Assignee: Ace. T Corporation
• Original Assignee: Ace. T Corporation
• Inventors: Chung, Chao-Fang, Liu, Yu-Ping, Kazuhiro, Miyashita
• Application Number:
  US11/939,557
• Publication Number:
  US 20080079870A1
• Time in Patent Office: Days
• US Class Current: 349/67
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer

Abstract

A small-angled, predetermined-positioned and predetermined-orientated light emitting device of a backlight module of a liquid crystal display comprises: a plurality of lower prisms; and each lower prism having an emitting face; a light guiding plate (LGP) being integrated with the plurality of lower prisms as an integral unit; a plurality of upper prisms; each upper prism having an entering face and an total reflecting face, an upper prism plate being integrated with a plurality of upper prisms as an integral unit. Emitting light beams nonuniformly distributes from predetermined positions, and each emitted light beam is limited to a small angle range.

Claims

1. A small-angled, predetermined-positioned and predetermined-orientated light emitting device of a backlight module of a liquid crystal display, the LCD backlight module emitting light beams from predetermined positions, limited to small angle range, and pointing to predetermined orientation, the light emitting device comprising:

a plurality of lower prisms; and

each lower prism having an emitting face;

a light guiding plate (LGP) being integrated with the plurality of lower prisms as an integral unit;

wherein a light beam propagating in predetermined angle range inside the lighting guiding plate will transmit through the emitting faces of one lower prism;

wherein the emitting face of the lower prism causes light beams to propagate in predetermined angle ranges inside the LOP and transmits through an emitting face of lower prism;

a plurality of upper prisms;

each upper prism having an entering face and an total reflecting face,

an upper prism plate being integrated with a plurality of upper prisms as an integral unit;

when a light beam transmits into an entering face of one of the upper prisms will be reflected totally from the total reflecting face and then transmitting through upper prism plate in predetermined orientations;

wherein the entering face and an total reflecting face of the upper prism cause light beams to transmit into an entering face thereof are reflected totally from a total reflecting face thereof and transmit through one of the upper prism plates in predetermined orientations;

wherein each of the lower prisms and the upper prisms has a quasi-triangle cross section; and

wherein a light beam propagating in predetermined angles range inside LGP is refracted by a corresponding lower prism and transmits through the emitting face of each lower prism, and across an air gap;

the light beam is incident into, refracted by and transmits into the entering face of a corresponding upper prism;

the light beam propagates inside the upper prism and onto the total reflecting face, and then the light beam is totally reflected from the total reflecting face, and further the totally reflected light beam transmits through the upper prism plate, limited to small angle range, pointing to predetermined orientations, being able to be looked as if those are emitted from corresponding predetermined positions of LGP.

2. The light emitting device according to claim 1, wherein

a range of an angle α

formed by the emitting face and a bottom side of lower prism is;

0<

α

≦

90°

;

a range of an angle ω

of the lower prism'"'"'s emitting face opposite to the angle α

is;

0<

ω

≦

0.5θ

_c;

where θ

_c is a critical angle of the material of the lower prisms;

a range of a vertex angle θ

of upper prism'"'"'s quasi-triangle, which is approximately equal to LGP is;

90°

−

θ

_c≦

θ

≦

180°

−

α

−

ω

;

where θ

_c is critical angle of the material of the lower prism;

α

is angle formed by emitting face and a bottom side of lower prism, and ω

is opposite angle of the emitting face of the lower prism;

a range of a curvature radius of the upper prism'"'"'s entering face r₁ is;

T<

r₁≦

∞

, and

a range of curvature radius of upper prism'"'"'s total reflecting face is;

T<

r₂≦

∞

;

where the T is the shortest distance between LCD substrate and intersecting point of entering face of upper prism and total reflecting face of upper prism.

3. The light emitting device according to claim 2, wherein a length of bottom side of the quasi-triangle of the lower prism contacting the LGP is approximately equal to a distance of an openings of an LCD substrate.

4. The light emitting device according to claim 2, wherein the totally reflected light beams transmitting through the upper prism plate are limited to predetermined angle ranges;

orientations of the angle range point to openings of an LCD substrate.

5. The light emitting device according to claim 2, wherein the totally reflected light beams transmitting through the upper prism plate are limited to a predetermined angle range;

orientations of the angle range including those vertical to the upper prism plate.

6. The light emitting device according to claim 2, wherein lines drawn from borders of the lower prisms and vertical to upper prism plate pass through openings of LCD substrate.

7. The light emitting device according to claim 2, wherein after the light beam transmits through the emitting face of each lower prism and across air gap, the light beam is incident on, refracted by and transmits into the entering face of corresponding upper prism, and the angle formed by a normal line of the total reflecting face of the upper prism and a ray of the light beam propagating inside the upper prism and onto the total reflecting face is equal to or greater than a critical angle of the upper prism material.

8. The light emitting device according to claim 2, wherein after transmitting into upper prism, the light beam is totally reflected by total reflecting face of the upper prism, then transmit through the upper prism plate;

a width of the light beam transmitting through the upper prism plate is approximately equal to a width of the light beam when propagating inside the lower prism, and a direction of the angle range of the light beam transmitting through the upper prism plate includes orientation vertical to upper prism plate.

9. The light emitting device according to claim 2, wherein a curvature center of the entering face and the total reflecting face of upper prism are above a border between the upper prism and the upper prism plate, that is an opposite side of the vertex angle θ

of the quasi-triangle of the upper prism, which is near the LGP.

10. The light emitting device according to claim 2, wherein a length of the bottom side of the quasi-triangle of the lower prism (i.e. border line between each lower prism and LGP) is approximately equal to a distance of two neighboring openings of an LCD substrate, and a line drawn from a border of each two neighboring lower prism and vertical to the upper prism plate will pass through corresponding openings of a LCD substrate.

11. The light emitting device according to claim 2, wherein the angles, formed by normal of the total reflecting face of the upper prism and rays of the light beams propagating inside the upper prism and onto the total reflecting face, are equal to or greater than a critical angle of the upper prism material, and a width of the light beams transmitting through upper prism plate is approximately equal to a width of the light beams when propagating inside lower prism, and directions of angle range of the light beams transmitting through upper prism plate include orientations vertical to the upper prism plate.

12. The light emitting device according to claim 1, wherein a range of opposite angle ω

of lower prism'"'"'s emitting face is;

0<

ω

≦

0.5θ

_c, and

wherein θ

_c is a critical angle of the lower prism'"'"'s material;

a range of vertex angle θ

of upper prism'"'"'s quasi-triangle, which is approximately equal to LGP, is;

90°

−

θ

_c≦

θ

≦

180°

−

α

−

ω

, and

θ

_c is critical angle of the material of the lower prism;

α

is angle formed by the emitting face and the bottom side of lower prism, and ω

is opposite angle of lower prism'"'"'s emitting face.

13. The light emitting device according to claim 12, wherein a length of the bottom side of the quasi-triangle of each lower prism (i.e. a border line between each lower prism and LGP) is approximately equal to a distance of neighboring openings of the LCD substrate;

a lines drawn from borders of each two neighboring lower prisms and vertical to the upper prism plate passes through corresponding openings of the LCD substrate;

a width of the light beams transmitting through the upper prism plate is approximately equal to a width of the light beams when propagating inside lower prism, and directions of angle range of the light beams transmitting through upper prism plate include orientations vertical to the upper prism plate.

14. The light emitting device according to claim 13, wherein a range r₁ of curvature radius of upper prism'"'"'s entering face r₁ is:

T<

r₁≦

∞

, and

a range r₂ of the curvature radius of the reflecting face of the upper prism is;

T<

r₂≦

∞

;

where the T is a shortest distance between the LCD reflecting layer and an intersecting point of an entering face of the upper prism and a total reflecting face of the upper prism.

15. The light emitting device according to claim 14, wherein a curvature center of the entering face and the total reflecting face of upper prism is above the border between upper prism and upper prism plate, that is, an opposite side of the vertex angle θ

of the quasi-triangular of the upper prism, which is near the LGP.

16. The light emitting device according to each individual claim from claim 1, wherein a film or filling layer having a refractive index approximately equal to that of the upper prism is applied between the upper prism plate and the LCD substrate.

17. The light emitting device according to claim 2, wherein a film or filling layer having a refractive index approximately equal to that of the upper prism is applied between the upper prism plate and the LCD substrate.

18. The light emitting device according to claim 12, wherein a film or filling layer having a refractive index approximately equal to that of the upper prism is applied between the upper prism plate and the LCD substrate.

19. The light emitting device according to claim 14, wherein a film or filling layer having a refractive index approximately equal to that of the upper prism is applied between the upper prism plate and the LCD substrate.

20. The light emitting device according to claim 15, wherein a film or filling layer having a refractive index approximately equal to that of the upper prism is applied between the upper prism plate and the LCD substrate.