LCD TV and projection-based backlight system used therefor

• US 7,411,635 B2
• Filed: 10/15/2007
• Issued: 08/12/2008
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Himax Technologies Incorporated
• Original Assignee: Himax Technologies Incorporated
• Inventors: Chen, Yen Chen, Li, Kuo Yuin
• Primary Examiner(s): Nelms; David C.
• Assistant Examiner(s): Chung; David Y
• Application Number:
  US11/872,581
• Publication Number:
  US 20080036929A1
• Time in Patent Office: 302 Days
• Field of Search: 349/5, 349/9
• US Class Current: 349/5
• CPC Class Codes: H04N 5/66 Transforming electric information into light information scanning details H04N3/00
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 5/7408 Direct viewing projectors, e.g. an image displayed on a video CRT or LCD display being projected on a screen
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

An LCD TV includes a housing, an LCD screen panel disposed on the front side of the housing, a first mirror disposed on the back side of the housing and a projection-based backlight system disposed in a lower cabinet of the housing, wherein the projection-based backlight system provides polarized light for the LCD screen panel through the first mirror. The projection-based backlight system can provide uniformly polarized light and increase polarization efficiency as well as be easily achieved by using low-cost optical components.

Claims

1. A liquid crystal display (LCD) device, comprising:

a liquid crystal display (LCD) screen panel for producing images; and

a projection-based backlight system comprising

a light source for supplying a light beam;

polarizing means for polarizing the light beam supplied by the light source to obtain a polarized light beam; and

a first projection lens for enlarging the polarized light beam received from the polarizing means and projecting the enlarged polarized light beam onto the LCD screen panel;

wherein the polarizing means comprises;

a polarizing beam splitter having a light input side for receiving the light beam, a first split-light side adjacent to the light input side, a second split-light side opposite to the light input side, and a light output side opposite to the first split-light side, the polarizing beam splitter being configured to split the light beam into first polarization light to pass directly through the second split-light side for the first projection lens and second polarization light to be directed toward the first split-light side.

2. The device as claimed in claim 1, wherein the first polarization light is P-polarization light and the second polarization light is S-polarization light.

3. The device as claimed in claim 1, wherein the polarizing means further comprises:

a second mirror configured to reflect the second polarization light;

a half waveplate configured to receive the second polarization light from the second mirror and to convert the second polarization light into third polarization light; and

a second projection lens configured to receive the third polarization light from the half waveplate and to project the third polarization light to the LCD screen panel.

4. The device as claimed in claim 3, wherein the first polarization light and the third polarization light are the same polarization.

5. The device as claimed in claim 3, wherein the polarizing means further comprises:

a condenser lens disposed between the light source and the polarizing beam splitter; and

a relay lens disposed between the condenser lens and the polarizing beam splitter;

wherein the condenser lens is configured to condense the light beam, and the relay lens is configured to direct the condensed light beam for the polarizing beam splitter.

6. The device as claimed in claim 5, wherein the polarizing means further comprises:

two lens arrays having a plurality of lenses respectively and being configured to receive the light beam from the light source and to compensate the light beam for the condenser lens, wherein the two lens arrays are disposed opposite to each other and both are disposed between the light source and the condenser lens.

7. A projection-based backlight system for an LCD TV having an LCD screen panel, comprising:

a light source for supplying light;

two lens arrays having a plurality of lenses respectively and being disposed opposite to each other, and both disposed adjacent to the light source and configured to receive the light from the light source and to compensate the light;

a condenser lens disposed adjacent to the lens arrays and configured to condense the compensated light;

a relay lens disposed adjacent to the condenser lens and configured to direct the condensed light;

a polarizing beam splitter having a light input side facing the relay lens for receiving the directed light, a first split-light side adjacent to the light input side, a second split-light side opposite to the light input side, and a light output side opposite to the first split-light side, the polarizing beam splitter configured to split the directed light into first P-polarization light to pass directly through the second split-light side and S-polarization light to be directed toward the first split-light side;

a first projection lens disposed adjacent to the second split-light side of the polarizing beam splitter and configured to receive the first P-polarization light and to project the first P-polarized light to the LCD screen panel;

a second mirror disposed adjacent to the first split-light side and configured to reflect the S-polarization light;

a half waveplate disposed adjacent to the second mirror and configured to receive the S-polarization light from the second mirror and to convert the S-polarization light into second P-polarization light; and

a second projection lens disposed adjacent to the half waveplate and configured to receive the second P-polarized light from the half waveplate and to project the second P-polarized light to the LCD screen panel.