Field sequentially driven liquid crystal display device

• US 20080084521A1
• Filed: 10/05/2007
• Published: 04/10/2008
• Est. Priority Date: 10/06/2006
• Status: Abandoned Application

• Current Assignee: Stanley Electric Company Limited
• Original Assignee: Stanley Electric Company Limited
• Inventors: SUZUKI, Osamu, TSUCHIHASHI, Hiroshi, SUGIYAMA, Takashi
• Application Number:
  US11/973,229
• Publication Number:
  US 20080084521A1
• Time in Patent Office: Days
• US Class Current: 349/70
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: G02F 1/13471 in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells G02F1/13475 takes precedence
• CPC Class Codes: G02F 2202/40 Materials having a particular birefringence, retardation
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources

Abstract

A liquid crystal display device with improved visual recognition is provided which includes: a first liquid crystal cell; a second liquid crystal cell; two cross polarizers disposed on both sides of a two-layer structure panel including the first and second liquid-crystal cells along a normal direction of the substrates;

a light source capable of emitting lights of a plurality of colors; and a control circuit for time sequentially dividing one frame into a plurality of subframes, emitting light of a predetermined color in each subframe, synchronously with light emission, controlling a state of light transmission and light shielding of a plurality of display areas of said two-layer structure panel including said first and second liquid crystal cells, wherein the first and second liquid crystal cells are structured in a mutual optical compensation relation in both a driving state and a non-driving state.

Claims

1. A liquid crystal display device comprising:

a first liquid crystal cell including a first pair of opposing substrates and a first liquid crystal layer held between said first pair of substrates, said first pair of substrates having at least a first pair of pixel electrodes for displaying predetermined characters and figures, and an alignment state of said first liquid crystal layer being capable of being controlled by adjusting a voltage applied across said first pair of pixel electrodes;

a second liquid crystal cell including a second pair of opposing substrates and a second liquid crystal layer held between said second pair of substrates, said second pair of substrates having a second pair of pixel electrodes for completely covering in area said predetermined characters and figures, and an alignment state of said second liquid crystal layer being capable of being controlled by adjusting a voltage applied across said second pair of pixel electrodes;

two cross polarizers disposed on both sides of a two-layer structure panel including said first and second liquid crystal cells along a normal direction of said substrates;

a light source capable of emitting lights of a plurality of colors; and

a control circuit for time sequentially dividing one frame into a plurality of subframes, emitting light of a predetermined color in each subframe, synchronously with light emission, controlling a state of light transmission and light shielding of a plurality of display areas of said two-layer structure panel including said first and second liquid crystal cells,

wherein said first and second liquid crystal cells are structured in a mutual optical compensation relation in both a driving state and a non-driving state.

2. The liquid crystal display device according to claim 1, wherein said control circuit controls in such a manner that said plurality of display areas defined by the electrodes of said first liquid-crystal cell and the electrodes of said second liquid crystal cell take the light transmission state in only one of said subframes or in all said subframes.

3. The liquid crystal display device according to claim 2, wherein if both said first and second liquid crystal cells defining each of said plurality of display areas are in the driving state or non-driving state, each of said display areas enters the light shielding state.

4. The liquid crystal display device according to claim 3, wherein said light source include LED'"'"'s.

5. The liquid crystal display device according to claim 3, wherein said light source emits parallel light.

6. The liquid crystal display device according to claim 3, wherein said light source is a point light source emitting radiative light.

7. The liquid crystal display device according to claim 1, wherein gradation display is performed by controlling the alignment state of the liquid crystal of at least one of said first and second liquid crystal cells to have an intermediate alignment state between the driving state and non-driving state.

8. The liquid crystal display device according to claim 7, wherein said control circuit controls in such a manner that said plurality of display areas defined by the electrodes of said first liquid crystal cell and the electrodes of said second liquid crystal cell take the light transmission state in only one of said subframes or in all said subframes.

9. The liquid crystal display device according to claim 8, wherein if both said first and second liquid crystal cells defining each of said plurality of display areas are in the driving state or non-driving state, each of said display areas enters the light shielding state.

10. The liquid crystal display device according to claim 9, wherein said light source include LED'"'"'s.

11. The liquid crystal display device according to claim 9, wherein said light source emits parallel light.

12. The liquid crystal display device according to claim 9, wherein said light source is a point light source emitting radiative light.

13. A driving method for a liquid crystal display device comprising:

a first liquid crystal cell including a first pair of opposing substrates and a first liquid crystal layer held between said first pair of substrates, said first pair of substrates having at least a first pair of pixel electrodes for displaying predetermined characters and figures, and an alignment state of said first liquid crystal layer being capable of being controlled by adjusting a voltage applied across said first pair of pixel electrodes;

a second liquid crystal cell including a second pair of opposing substrates and a second liquid crystal layer held between said second pair of substrates, said second pair of substrates having a second pair of pixel electrodes for completely covering in area said predetermined characters and figures, and an alignment state of said second liquid crystal layer being capable of being controlled by adjusting a voltage applied across said second pair of pixel electrodes;

two cross polarizers disposed on both sides of a two-layer structure panel including said first and second liquid crystal cells along a normal direction of said substrates;

a light source capable of emitting lights of a plurality of colors; and

a control circuit for time sequentially dividing one frame into a plurality of subframes, emitting light of a predetermined color in each subframe, synchronously with light emission, controlling a state of light transmission and light shielding of a plurality of display areas of said two-layer structure panel including said first and second liquid crystal cells,

wherein the driving method controls in such a manner that a display area entered in the light shielding state in a subframe is made to enter in another subframe.

14. The driving method for a liquid crystal display device according to claim 13, wherein:

each frame includes a first subframe and a second subframe;

an emission color of said light source includes a first color and a second color, and

in a display area different from a display area in which said first color transmits in said first subframe, said second color is made to be transmitted in said second subframe.

15. A driving method for a liquid crystal display device comprising:

a first liquid crystal cell including a first pair of opposing substrates and a first liquid crystal layer held between said first pair of substrates, said first pair of substrates having at least a first pair of pixel electrodes for displaying predetermined characters and figures, and an alignment state of said first liquid crystal layer being capable of being controlled by adjusting a voltage applied across said first pair of pixel electrodes;

a second liquid crystal cell including a second pair of opposing substrates and a second liquid crystal layer held between said second pair of substrates, said second pair of substrates having a second pair of pixel electrodes for completely covering in area said predetermined characters and figures, and an alignment state of said second liquid crystal layer being capable of being controlled by adjusting a voltage applied across said second pair of pixel electrodes;

two cross polarizers disposed on both sides of a two-layer structure panel including said first and second liquid crystal cells along a normal direction of said substrates;

a light source capable of emitting lights of a plurality of colors; and

a control circuit for time sequentially dividing one frame into a plurality of subframes, emitting light of a predetermined color in each subframe, synchronously with light emission, controlling a state of light transmission and light shielding of a plurality of display areas of said two-layer structure panel including said first and second liquid crystal cells,

wherein the driving method controls in such a manner that gradation display is performed by controlling the alignment state of the liquid crystal of at least one of said first and second liquid crystal cells to have an intermediate alignment state between the driving state and non-driving state.

16. The driving method for a liquid crystal display device according to claim 15, wherein:

a display area entered in the light transmission state in one subframe is controlled to enter the light shielding state in another subframe;

each frame includes at least a first subframe and a second subframe;

said light source can emit lights of at least a first color and a second color; and

in a display area different from a display area in which said first color transmits in said first subframe, said second color is made to be transmitted in said second subframe.

17. The driving method for a liquid crystal display device according to claim 15, wherein mixed color display is performed by transmitting light of a primary color in each of said subframes and making a display area enter the light transmission state in a plurality of subframes.