Liquid crystal display with reflective color filters

• US 5,555,114 A
• Filed: 06/07/1995
• Issued: 09/10/1996
• Est. Priority Date: 11/30/1992
• Status: Expired due to Term

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation), Tottori Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation), Tottori Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Suzaki, Takeshi, Narita, Kenichi
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): MILLER, CHARLES LELAND
• Application Number:
  US08/480,731
• Time in Patent Office: 461 Days
• Field of Search: 359/64, 359/65, 359/68
• US Class Current: 349/98
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 2201/34 reflector
• CPC Class Codes: G02F 2201/343 cholesteric liquid crystal reflector

Abstract

A color liquid crystal display includes a cholesteric liquid crystal layer for selectively reflecting at high efficiency circularly polarized light having a specific wavelength, for example, a wavelength corresponding to red, blue or green, a birefringent layer formed on the liquid crystal layer, and a polarize plate formed on the birefringent layer. The birefringent layer includes a pair of electrodes and a nematic liquid crystal layer formed between the electrodes. Circularly polarized light of a specific wavelength that is selectively reflected by the cholesteric liquid crystal layer has its vibration direction rotated by retardation of the birefringent layer 20 when an electric field is not applied to the liquid crystal. When an electric field is applied to the liquid crystal layer, the reflected circularly polarized light is directly transmitted through the birefringent layer. The polarize plate blocks or transmits light according to the vibration direction of the light transmitted through the birefringent layer. This liquid crystal display has high usage efficiency of light and displays color clearly.

Claims

1. A multi/full color liquid display device comprising:

a plurality of color selection layers consisting essentially of a cholesteric liquid crystal for reflecting respectively circularly polarized light of red, blue and green,

an optical layer formed on said color selection layers at a side where said circularly polarized light is reflected, and

a layer formed on said color selection layers, at a side opposite to said optical layer, for absorbing light transmitted through said color selection layers,

wherein said optical layer comprises a single liquid crystal layer consisting essentially of a ferroelectric liquid crystal of uniaxial orientation and covering entirely arranged said plurality of color selection layers, matrix electrodes holding said liquid crystal layer therebetween, a single phase shifting film covering entirely arranged said plurality of color selection layers, and a polarizer,

wherein said optical layer generates at least one of circularly polarized light and elliptically polarized light approximating circularly polarized light for red, blue and green light when said liquid crystal layer is in one of an ON state and an OFF state,

wherein the voltage between said matrix electrodes is different in amount between colors, whereby said optical layer has different retardation for each selection wavelength, and

wherein said optical layer responds to the driving voltage between said matrix electrodes for effecting multi/full color display by light reflected by said plurality of color selection layers.

2. The multi/full color liquid display device according to claim 1, wherein said liquid crystal layer, said phase shifting film and said polarizer are provided on said color selection layers in sequence.

3. The multi/full color liquid crystal display according to claim 1, wherein said phase shifting film, said liquid crystal layer, and said polarizer are provided on said color selection layers in sequence.

4. The full/multi color liquid crystal display according to claim 1, wherein said color selection layers are formed by overlaying layers that respectively reflect light of right rotation and light of left rotation for circular polarization of red, blue and green.

5. A multi/full color liquid crystal display device, comprising:

a plurality of color selection layers consisting essentially of a cholesteric liquid crystal for reflecting respectively circularly polarized light of red, blue and green,

an optical layer formed on said color selection layer at a side on which said circularly polarized light is reflected, and

a layer formed on said color selection layer at a side opposite to said optical layer for absorbing light transmitted through said color selection layers,

wherein said optical layer comprises a single liquid crystal layer consisting essentially of a chiral nematic liquid crystal that covers entirely arranged said plurality of color selection layers for generating circularly polarized light of a low order for light in visible spectrum, matrix electrodes holding said liquid crystal layer therebetween, a single phase shifting film covering entirely arranged said plurality of color selection layers, and a polarizer,

wherein said optical layer generates at least one of circularly polarized light and elliptically polarized light approximating circularly polarized light for red, blue and green light when said liquid crystal layer is in one of an ON state and an OFF state,

wherein the voltage between said matrix electrodes is different in amount between colors, whereby said optical layer has different retardation for each selection wavelength, and

wherein said optical layer responds to a driving voltage between said matrix electrodes for effecting multi/full color display by light reflected by said plurality of color selection layers.

6. The multi/full color liquid crystal display according to claim 5, wherein said liquid crystal layer, said phase shifting film, and said polarizer are provided on said color selection layers in sequence.

7. The multi/full color liquid crystal display according to claim 5, wherein said phase shifting film, said liquid crystal layer, and said polarizer are provided on said color selection layer in sequence.

8. The multi/full color liquid crystal display according to claim 5, wherein said color selection layers are formed by overlaying layers respectively reflecting light in right rotation and light in left rotation for circular polarization of red, blue and green.