Cholesteric liquid crystal writing board

Patent metadata

Field	Value
Publication number	US-10509250-B2
Application number	US-201816004772-A
Country	US
Kind code	B2
Filing date	Jun 11, 2018
Priority date	Apr 19, 2018
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

A cholesteric liquid crystal writing board comprises a cholesteric liquid crystal device, a photo-sensing array layer and a mode control unit. The photo-sensing array layer is disposed at one side of the light-emitting surface of the cholesteric liquid crystal device. The photo-sensing array layer comprises a plurality of gate control lines and a plurality of mode control lines. The mode control unit comprises a main control circuitry and a plurality of mode switches coupled to the main control circuitry. Each mode switch is coupled to one of the mode control lines correspondingly. The gate control lines intersect with the mode control lines so as to define a plurality of light sensing areas arranged in an array. Each light sensing area has a switch element and a light-sensing element. The main control circuitry controls each mode switch to be switched between a voltage output mode and a voltage write mode.

First claim

What is claimed is:

1. A cholesteric liquid crystal writing board, comprising:
a cholesteric liquid crystal device comprising a cholesteric liquid crystal layer, wherein the cholesteric liquid crystal device has a light-entering surface and a light-emitting surface disposed corresponding to the light-entering surface;
a photo-sensing array layer disposed at one side of the light-emitting surface of the cholesteric liquid crystal device, wherein the photo-sensing array layer comprises a plurality of gate control lines and a plurality of mode control lines, the gate control lines and the mode control lines are intersected to define a plurality of light-sensing areas arranged in an array, and each of the light-sensing areas is configured with a switch element and a light-sensing element;
a mode control unit comprising a main control circuitry and a plurality of mode switches coupled to the main control circuitry, wherein each of the mode switches is coupled to one of the mode control lines correspondingly, and the main control circuitry controls each of the mode switches to be switched between a voltage output mode and a voltage write mode; and
a sensing signal processing unit coupled to the photo-sensing array layer through the mode switches, wherein when each of the mode switches is in the voltage output mode, at least one of the light-sensing elements of the photo-sensing array layer senses a luminous flux change so as to generate a sensing signal, and the sensing signal processing unit receives the sensing signal and generates position data of the light-sensing element, which generates the sensing signal, in the photo-sensing array layer accordingly.

2. The cholesteric liquid crystal writing board according to claim 1 , wherein the sensing signal processing unit generates an erasing signal according to the position data and transmits the erasing signal to the main control circuitry of the mode control unit, and after receiving the erasing signal, the main control circuitry outputs a mode control signal accordingly to one or more of the mode switches corresponding to the position data so as to switch the one or more of the mode switches to the voltage write mode.

3. The cholesteric liquid crystal writing board according to claim 2 , wherein the cholesteric liquid crystal device further comprises a plurality of liquid crystal control areas, and the main control circuitry further outputs a voltage signal according to the erasing signal and transmits the voltage signal to the liquid crystal control area corresponding to the position data through the one or more of the mode switches for partially or entirely morphologically changing cholesteric liquid crystals corresponding to the liquid crystal control areas.

4. The cholesteric liquid crystal writing board according to claim 3 , wherein the light-sensing area corresponds to at least one or more of the liquid crystal control areas.

5. The cholesteric liquid crystal writing board according to claim 1 , wherein the sensing signal processing unit further outputs a display control signal according to the position data, and the cholesteric liquid crystal writing board further comprises:
a communication unit coupled to the sensing signal processing unit, wherein the communication unit receives the display control signal and transmits the display control signal to an electronic device.

6. The cholesteric liquid crystal writing board according to claim 5 , wherein the display control signal is transmitted to the electronic device when the gate control lines are conducted.

7. The cholesteric liquid crystal writing board according to claim 5 , wherein the display control signal is transmitted to the electronic device during a blanking time after the gate control lines are conducted.

8. The cholesteric liquid crystal writing board according to claim 5 , wherein the display control signal comprises a signal for controlling the electronic device to display a writing track.

9. The cholesteric liquid crystal writing board according to claim 5 , wherein the display control signal comprises a signal for controlling the electronic device to erase a writing track.

10. The cholesteric liquid crystal writing board according to claim 1 , wherein the luminous flux change is generated after at least partial of the cholesteric liquid crystal layer has a morphologically change caused by a pressing action.

11. The cholesteric liquid crystal writing board according to claim 1 , wherein the luminous flux change is generated after the light-entering surface of the cholesteric liquid crystal device is irradiated by a light.

12. The cholesteric liquid crystal writing board according to claim 1 , wherein the mode switch is switched to the voltage output mode within a frame time, and is switched to the voltage write mode within another frame time.

13. The cholesteric liquid crystal writing board according to claim 1 , wherein a control end of the switch element connects to one of the gate control lines, a first end of the switch element connects to one of the mode control lines, a second end of the switch element connects to one end of the light-sensing element, and the other end of the light-sensing element connects to a reference voltage.

14. The cholesteric liquid crystal writing board according to claim 1 , wherein the cholesteric liquid crystal device further comprises a first substrate and a second substrate opposite to the first substrate, the cholesteric liquid crystal layer is disposed between the first substrate and the second substrate, the cholesteric liquid crystal device further comprises a first transparent electroconductive layer disposed on a surface of the first substrate facing toward the cholesteric liquid crystal layer, and the cholesteric liquid crystal device further comprises a second transparent electroconductive layer disposed on one side of the second substrate facing toward the cholesteric liquid crystal layer.

15. The cholesteric liquid crystal writing board according to claim 14 , wherein the first transparent electroconductive layer comprises a plurality of first electrodes extending in a first direction and separately disposed, the second transparent electroconductive layer comprises a plurality of second electrodes extending in a second direction and separately disposed, and the first direction is different from the second direction.

16. The cholesteric liquid crystal writing board according to claim 15 , wherein the cholesteric liquid crystal device further comprises a plurality of liquid crystal control areas, and when viewing from a top of the light-entering surface, the first electrodes are crossed with the second electrodes and their intersections are disposed in correspondence to the liquid crystal control areas.

17. The cholesteric liquid crystal writing board according to claim 14 , wherein the cholesteric liquid crystal device further comprises a plurality of liquid crystal control areas, the second transparent electroconductive layer comprises a plurality of electrode blocks, and the electrode blocks are disposed in correspondence with the liquid crystal control areas.

18. The cholesteric liquid crystal writing board according to claim 14 , wherein the cholesteric liquid crystal device further comprises a plurality of liquid crystal control areas, the first transparent electroconductive layer and the second transparent electroconductive layer comprise a plurality of electrode blocks, and the electrode blocks are disposed in correspondence with the liquid crystal control areas.

19. The cholesteric l

Assignees

• Iris Optronics Co Ltd

Inventors

• Liao Chi-Chang
• Liu Shu-Shien
• Pai Tsung-Ming
• Wang Fu-Ming

Classifications

• G02F1/13718

  based on a change of the texture state of a cholesteric liquid crystal · CPC title

• G02F1/134336

  Matrix · CPC title

• G02F1/133 Primary

  Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements (arrangements or circuits for control of liquid crystal elements in a matrix, not structurally associated with these elements G09G3/36) · CPC title

• B43L1/00

  Repeatedly-usable boards or tablets for writing or drawing (drawing-boards B43L5/00) · CPC title

• G02F1/13306

  Circuit arrangements or driving methods for the control of single liquid crystal cells (G02F1/132, G02F1/133382 take precedence) · CPC title