Electronic shelf label

• US 6,914,648 B2
• Filed: 09/18/2002
• Issued: 07/05/2005
• Est. Priority Date: 09/19/2001
• Status: Expired due to Fees

• Current Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Original Assignee: Optrex Corporation (Kyocera Corporation)
• Inventors: Niiyama, Satoshi, Suehiro, Noriko
• Primary Examiner(s): Chowdhury, Tarifur R.
• Assistant Examiner(s): KIM, RICHARD H
• Application Number:
  US10/245,640
• Publication Number:
  US 20030053014A1
• Time in Patent Office: 1,021 Days
• Field of Search: 349/74, 349/76, 349/78, 349/172, 349/169, 349/73
• US Class Current: 349/78
• CPC Class Codes: G02F 1/133397 for suppressing after-image or image-sticking
• CPC Class Codes: G02F 1/13473 for wavelength filtering or for colour display without the use of colour mosaic filters
• CPC Class Codes: G02F 1/13478 based on selective reflection
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal
• CPC Class Codes: G09G 2300/0486 Cholesteric liquid crystals, including chiral-nematic liquid crystals, with transitions between focal conic, planar, and homeotropic states
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals

Abstract

There are provided at least two liquid crystal panels 10, 20 including the liquid crystals developing a memory effect, the liquid crystal developing a memory effect on a side opposite to a viewer side has a selective reflection wavelength set at 615-665 nm, the liquid crystal developing a memory effect on the viewer side has a selective reflection wavelength set at 490-540 nm, and a color filter having a certain transmission property is provided between the liquid crystal developing a memory effect on the viewer side and the liquid crystal developing a memory effect on the side opposite to the viewer side.

Claims

1. A liquid crystal display element comprising

at least two electrodes and

two chiral nematic liquid crystal layers having two different selective reflection wavelengths and

a color filter,

wherein each chiral nematic liquid crystal layer is capable of developing at least two different stable optical states without applying voltage to said liquid crystal layer,

at least three colors, comprising white and red, are obtainable in each pixel or each segment of said liquid crystal display element,

the purity of said red color is adjusted by said color filter and

said white color is produced only by mixing the two different selective reflection wavelengths.

2. The liquid crystal display element according to claim 1 wherein at least four colors are obtainable in each pixel or each segment of said liquid crystal display element.

3. The liquid crystal display element according to claim 1 wherein said colors further comprise a black color.

4. The electronic liquid crystal display element according to claim 1 wherein said colors further comprise a green color.

5. The liquid crystal display element according to claim 1 wherein said colors further comprise a blue color.

6. The liquid crystal display element according to claim 1 wherein the difference between the center wavelength of a selective reflective color in a planar state of one liquid crystal layer and the center wavelength of a selective reflective color in a planar state of the other liquid crystal layer is equal to or greater than 50 nm.

7. The liquid crystal display element according to claim 1 wherein one of said liquid crystal layers has a center wavelength in a planar state that is less than or equal to 550 nm.

8. The liquid crystal display element according to claim 1 further comprising a layer, sandwiched between two chiral nematic liquid crystal layers, capable of absorbing a certain wavelength.

9. The liquid crystal display element according to claim 1 wherein at least two colors display the price information in the same background color.

10. The liquid crystal display element according to claim 1 wherein a segment type electrode is arranged to display an information on price and/or incidental matter.

11. The liquid crystal display element according to claim 1 wherein a segment type electrode is arranged to display an information on price and/or incidental matter and another segment type electrode is arranged to display a background color.

12. The liquid crystal display element according to claim 1 wherein dot-matrix type electrodes are arranged to display an information on price and/or incidental matter.

13. The liquid crystal display element according to claim 1 wherein both a segment type electrode and dot-matrix type electrodes are arranged to display an information on price and/or incidental matter.

14. The liquid crystal display element according to claim 1 wherein said white color is developed by mixing two selective reflective colors produced by the planar states of the two chiral nematic liquid crystal layers.

15. The liquid crystal display element according to claim 1 wherein a signal comprising information on price and/or incidental matter to be displayed is inputted to the liquid crystal display element by a wireless communication device.

16. The liquid crystal display element according to claim 15 wherein said wireless communication device comprises an IR communication technique.

17. The liquid crystal display element according to claim 15 wherein said wireless communication device comprises a radio-frequency communication technique.

18. The liquid crystal display element according to claim 1 wherein the display element further comprises a battery for a power supply to drive said chiral nematic liquid crystal layer.