Front Light Unit and Image Display Device

Patent metadata

Field	Value
Publication number	US-2018045902-A1
Application number	US-201615553924-A
Country	US
Kind code	A1
Filing date	Feb 26, 2016
Priority date	Feb 26, 2015
Publication date	Feb 15, 2018
Grant date	—

Abstract

A front light unit of an embodiment comprises: a light source unit for an image display device; a light guide unit for guiding light incident from the light source unit and outputting the guided light to a display unit; and a holographic optical element unit being opposite to the display unit and disposed on the light guide unit. Therefore, the present invention can adjust the direction of light output from the light source unit and increase the quantity of light transferred to the display unit, using a pattern formed in the holographical optical element unit, thereby improving the efficiency of light supplied from the light source unit and reducing the sizes of the light unit and the display device including the same.

First claim

1 . A front light unit comprising:
a light source unit; a light guide unit that guides light incident thereon from the light source unit so that the light is transferred to a display unit; and a holographic optical element unit disposed on the light guide unit so as to be opposite the display unit, wherein the holographic optical element unit includes a base substrate and hologram patterns formed on the base substrate, and wherein the hologram patterns in a center region of the holographic optical element unit and the hologram patterns in marginal regions surrounding the center region are different from each other.

2 . (canceled)

3 . The front light unit according to claim 1 , wherein the holographic optical element unit has a larger refractive index than the light guide unit.

4 . The front light unit according to claim 1 , wherein the hologram patterns collimate light emitted from the light guide unit.

5 . The front light unit according to claim 1 , wherein the hologram patterns are stripe patterns that are periodically repeated.

6 . The front light unit according to claim 5 , wherein the hologram patterns transmit only light polarized in one direction.

7 . (canceled)

8 . The front light unit according to claim 1 , wherein the light guide unit converts light incident thereon from the light source unit into a surface light source.

9 . The front light unit according to claim 1 , wherein the light source unit is disposed near at least one side surface of the light guide unit.

10 . An image display device comprising:
a display unit for displaying an image; a pentaprism disposed in front of the display unit in order to change a path of light emitted from the display unit and to transmit the light; and a virtual image optical unit for changing a path of light emitted from the pentaprism in order to provide a magnified virtual image corresponding to an image displayed on the display unit for an observer, wherein the virtual image optical unit includes a condensing lens that collects light emitted from the pentaprism and a reflection mirror formed to be inclined in front of the condensing lens in order to reflect light that ha passed through the condensing lens.

11 . The image display device according to claim 10 , further comprising:
a lens integrally formed at a light-incident surface and a light-emitting surface of the pentaprism.

12 . (canceled)

13 . The image display device according to claim 10 , wherein the reflection mirror has a reflection surface that is oriented toward the observer so that the light reflected by the reflection mirror is transferred toward the observer.

14 . The image display device according to claim 10 , wherein the virtual image optical unit includes:
a reflection mirror that reflects light emitted from the pentaprism; and a condensing lens that collects light emitted from the reflection mirror.

15 . The image display device according to claim 14 , wherein the reflection mirror has a reflection surface that is oriented toward the observer so that the light reflected by the reflection mirror is transferred toward the observer.

16 . The image display device according to claim 10 , wherein the virtual image optical unit includes:
a polarizing mirror that selectively transmits light emitted from the pentaprism in accordance with a polarized component; and a reflection mirror that reflects light that has passed through the polarizing mirror back to the polarizing mirror.

17 . The image display device according to claim 16 , wherein the polarizing mirror is formed to be inclined so that the light reflected by the reflection mirror is transferred toward the observer.

18 - 20 . (canceled)

21 . An image display device comprising:
a front light unit that emits light; a reflective-type display unit that receives the light emitted from the front light unit and generates image light; and a virtual image optical unit that converts the image light generated by the display unit into a virtual image, wherein the virtual image optical unit includes: a lens unit that transmits the image light; at least one virtual-image-converting mirror that converts the image light supplied from the lens unit into a virtual image; and a beam splitter disposed between the lens unit and the at least one virtual-image-converting mirror.

22 . The image display device according to claim 21 , wherein the reflective-type display unit is a reflective-type liquid crystal display device.

23 . The image display device according to claim 21 , wherein the reflective-type display unit is a liquid-crystal-on-silicone (LCoS) display.

24 . The image display device according to claim 21 , wherein the lens collimates light emitted from the front light unit.

25 . The image display device according to claim 21 , wherein the beam splitter selectively transmits light emitted from the display unit in accordance with a polarized component.

26 . The image display device according to claim 21 , wherein the beam splitter has a reflection surface that is oriented toward the observer so that the light reflected by the virtual-image-converting mirror is transferred toward the observer.

Assignees

• Lg Innotek Co Ltd

Inventors

• Lee Sang Hun
• Kim Min
• Kim Tae Kyung
• Jang Jung In

Classifications

• G02B6/34

  utilising prism or grating {(G02B6/293 takes precedence)} · CPC title

• G02F1/133615

  Edge-illuminating devices, i.e. illuminating from the side · CPC title

• G02B6/4204 Primary

  the coupling comprising intermediate optical elements, e.g. lenses, holograms (encapsulated active devices H01S5/02208) · CPC title

• G02B2027/0174

  holographic · CPC title

• G02B6/27

  with polarisation selective and adjusting means · CPC title