Electrically erasable writing surface

• US 7,136,048 B2
• Filed: 02/19/2002
• Issued: 11/14/2006
• Est. Priority Date: 02/19/2002
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Kangas, Jari A., Yrjänäinen, Jukka, Hautanen, Jukka
• Primary Examiner(s): Nguyen, Jimmy H.
• Application Number:
  US10/078,684
• Publication Number:
  US 20030156099A1
• Time in Patent Office: 1,729 Days
• Field of Search: 345/173, 345/175, 345/174, 345/177, 178 1803- 1806, 178/19.24
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures

Abstract

An electrically erasable writing surface is provided. The writing surface includes a bistable display layer that responds to electrical and mechanical inputs. A touch pad is located above or below the display layer. The writing surface facilitates writing complex characters and increases accuracy by displaying a user input created by a passive stylus.

Claims

1. An electronic device comprising:

a display layer comprising electrically and mechanically sensitive display material having at least two stable optical states, wherein each of the two stable optical states are maintained without the application of an electrical excitation, and wherein said layer changes optical states of a portion of said display material to create an image corresponding to mechanical pressure;

a touch pad physically coupled to the display layer, the touch pad configured to convert said mechanical pressure into an electrical output; and

a processor configured to cause said device to;

blank said display layer prior to receiving said mechanical pressure;

apply character recognition to said image;

display a corresponding character on a second output display in response to successful recognition of said image; and

remove said image from said portion of said display material at a predetermined amount of time after said successful recognition.

2. The device of claim 1, wherein the display material comprises liquid crystal material.

3. The device of claim 2, wherein the liquid crystal material comprises cholesteric liquid crystal material.

4. The device of claim 2, wherein the liquid crystal material comprises twisted nematic liquid crystal material.

5. The device of claim 2, wherein the display material comprises polymer dispersed throughout the liquid crystal material.

6. The device of claim 1, further including a flexible substrate located above the display layer.

7. The device of claim 6, further including a transparent electrode located between the flexible substrate and a first side of the display layer.

8. The device of claim 7, further including a reflective layer located below a second side of the display layer.

9. The device of claim 8, wherein the reflective layer comprises an electrode.

10. The device of claim 1, wherein the display material comprises a suspended particle material.

11. The device of claim 1, further including a driver module coupled to the display layer and configured to apply a field to reset the state of the display material.

12. The device of claim 11, wherein the field comprises an electric field.

13. The device of claim 11, wherein the field comprises a magnetic field.

14. The device of claim 1, wherein the display layer is positioned in an overlapping relationship with the touch pad.

15. The device of claim 1, further including an output display electrically coupled to the touch pad.

16. The input device of claim 15, wherein the output display comprises the display material.

17. The device of claim 1, further including a keypad.

18. An electronic device comprising:

an optical output section;

a mechanical input section comprising;

a display layer comprising electrically and mechanically sensitive display material having at least two stable optical states, wherein each of the two stable optical states are maintained without the application of an electrical excitation, and wherein said layer changes display states at locations where a passive stylus contacts said display layer during user input;

a transparent and flexible touch pad physically coupled to the display layer and positioned in an overlapping relationship with the display layer, the touch pad configured to convert mechanical pressure received by the display layer from a passive stylus into an electrical output; and

a processor configured to cause said device to;

display a prompt on said optical output section requesting said user input;

receive said user input via said passive stylus on said mechanical input section; and

display a corresponding character in said optical output section and apply a second blanking field to erase said display layer in response to recognizing said user input as a character.

19. The device of claim 18, further comprising:

a key pad section comprising pressure sensitive keys.

20. The device of claim 18, wherein the optical output section comprises a display electrically coupled to the touch pad.

21. A mobile terminal comprising:

an output display; and

a mechanical input device comprising;

a display layer comprising electrically and mechanically sensitive display material having at least two stable optical states, wherein each of the two stable optical states are maintained without the application of an electrical excitation, wherein said layer changes display states at locations on said layer where mechanical pressure user input is received;

a touch pad physically coupled to the display layer, the touch pad configured to convert said mechanical pressure into an electrical output; and

a processor configured to cause said mobile terminal to;

display a prompt on said output display requesting user input;

apply a first blanking field to erase data from said display layer of said mechanical input device; and

display a corresponding character in said output display and apply a second blanking field to erase said display layer in response to recognizing said user input as a character.

22. The mobile terminal of claim 21, wherein the output display is integrated with the mechanical input device.

23. The mobile terminal of claim 22, wherein the output display comprises at least a portion of the display layer.

24. The mobile terminal of claim 21, wherein the display material comprises liquid crystal material.

25. The mobile terminal of claim 24, wherein the liquid crystal material comprises cholesteric liquid crystal material.

26. The mobile terminal of claim 24, wherein the liquid crystal material comprises twisted nematic liquid crystal material.

27. The mobile terminal of claim 21, further including a character recognition module coupled to the touch pad.

28. A method of operating an input device having an electrically and mechanically sensitive display layer having at least two stable optical states and physically coupled to a touch pad, the method comprising:

(a) receiving at the display layer and the touch pad a mechanical pressure;

(b) in response to (a) changing an optical state of the display layer and maintaining the optical state without applying an excitation to the display layer;

(c) at the touch pad, in response to (a), converting the mechanical pressure to an electrical output;

(d) performing character recognition to determine whether said mechanical pressure defined a character; and

(e) in response to successful character recognition, displaying a corresponding character on a second display area of said input device and applying a blanking field to reset said changed optical state of the display layer.