LIQUID CRYSTAL DISPLAY DEVICE

• US 20080273142A1
• Filed: 05/02/2008
• Published: 11/06/2008
• Est. Priority Date: 05/02/2007
• Status: Active Grant

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Hirota, Shoichi, Sugita, Tatsuya
• Granted Patent: US 7,728,922 B2
• Time in Patent Office: Days
• US Class Current: 349/62
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133557 Half-mirrors
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors

Abstract

The present invention provides a liquid crystal display device in which increase in manufacturing costs is minimized and the utilization rate of illumination light emitted by a backlight source is also improved.

A pixel electrode is formed at the intersection of each signal line and each gate line on the liquid-crystal-layer side of a first transparent substrate. A color filter is provided for each pixel electrode on the liquid-crystal-layer side of a second transparent substrate. A dichroic half mirror is provided for each of the color filters.

Claims

1. A liquid crystal display device, comprising:

a first transparent substrate;

a second transparent substrate;

a liquid crystal layer located between the first and second transparent substrates;

a backlight source located on the side of the first transparent substrate that is opposite to the liquid crystal layer;

a plurality of signal lines, a plurality of gate lines, and a plurality of sub-pixels, which are formed in matrix form on the liquid-crystal-layer side of the first transparent substrate, each of the sub-pixels including a transistor and a pixel electrode for transmitting an image signal voltage to the liquid crystal layer and being located at each intersection of the signal lines and the gate lines;

an optical film located on the backlight-source-side of the first transparent substrate;

a color filter provided for each of the sub-pixels and located on the liquid-crystal-layer side of the second transparent substrate; and

an optical film located on the side of the second transparent substrate that is opposite to the liquid crystal layer,

wherein illumination light emitted from the backlight source is phase-modulated by driving the liquid crystal layer, and the illumination light having the modulated phase is transmitted through the color filter to display a color image,

the liquid crystal display device being characterized in that a dichroic half mirror is formed between the first and second transparent substrates for each of the color filters.

2. The liquid crystal display device according to claim 1, wherein

the dichroic half mirror is located between the first transparent substrate and the liquid crystal layer.

3. The liquid crystal display device according to claim 2, wherein

the dichroic half mirror is located between the first transparent substrate and a layer including the transistors.

4. The liquid crystal display device according to claim 3, wherein

the dichroic half mirror functions as a protective layer to prevent an ionic impurity from diffusing from the first transparent substrate to the transistors.

5. The liquid crystal display device according to claim 4, wherein

the dichroic half mirror includes a silicon nitride material and a silicon oxide material.

6. The liquid crystal display device according to claim 1, wherein

the dichroic half mirror has a laminated structure including five layers in which layers each having a material with a high refractive index and layers each having a material with a low refractive index are alternately laminated until the number of laminated layers becomes five in total;

and

among the five layers, a third layer that is laminated thirdly has portions with mutually-different thicknesses based on the color filters.