Device and method for writing on capacitive touch sensor by stylus with conductive head and insulating body

• US 9,081,440 B2
• Filed: 08/17/2011
• Issued: 07/14/2015
• Est. Priority Date: 12/30/2010
• Status: Active Grant

• Current Assignee: eGalax_eMPIA Technology Inc.
• Original Assignee: eGalax_eMPIA Technology Inc.
• Inventors: Chang, Chin-Fu
• Primary Examiner(s): Hicks, Charles V
• Assistant Examiner(s): ZHENG, CHARLES H
• Application Number:
  US13/211,771
• Publication Number:
  US 20120169651A1
• Time in Patent Office: 1,427 Days
• Field of Search: 345/173, 345/174
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

The present invention provides a method and device for writing on a capacitive touch screen, which includes a guarding pattern and a conductive strip pattern exposed from each other, and a stylus. The conductive strip pattern includes a plurality of first conductive strips provided with a driving signal and a plurality of second conductive strips that provide mutual capacitive coupling signals, and the guarding pattern is provided with a DC signal. The stylus has a conductive pen head and a pen body. When the human body holding the pen body is not electrically coupled to the conductive pen head, the location of the conductive pen head can be determined by sufficient change in capacitive coupling caused by the conductive pen head capacitively coupling to the guarding pattern and the conductive strip pattern.

Claims

1. A method for writing on a capacitive touch screen, comprising:

providing a capacitive touch screen, including;

a conductive strip pattern having a plurality of conductive strips exposed from each other, the conductive strip pattern including a plurality of first conductive strips and a plurality of second conductive strips overlapping each other; and

a guarding pattern;

writing on the capacitive touch screen using a stylus with a conductive pen head and an insulating pen body, when the stylus covering both the conductive strip pattern and the guarding pattern and the conductive pen head not electrically coupled to a grounded object holding the insulating pen body, the conductive pen head being capacitively coupled to the conductive strip pattern and the guarding pattern, respectively, causing the conductive strip pattern to generate a change in capacitive coupling; and

providing a driving signal to at least one of the first conductive strips and providing a DC signal to at least one of the first conductive strips not provided with the driving signal and the guarding pattern, and determining the location of the stylus by detecting the change in capacitive coupling on the conductive strip pattern.

2. The method for writing on a capacitive touch screen according to claim 1, wherein there is no other signal sent to the capacitive touch screen by the conductive pen head apart from the capacitive coupling between the conductive pen head and the capacitive touch screen.

3. The method for writing on a capacitive touch screen according to claim 1, wherein the guarding pattern covers the conductive strip pattern.

4. The method for writing on a capacitive touch screen according to claim 1, wherein the guarding pattern includes a plurality of guarding conductive strips, the guarding conductive strips have a plurality of openings, wherein the intervals between the guarding conductive strips expose one of the first conductive strips and the second conductive strips, and the openings expose the other of the first conductive strips and the second conductive strips.

5. The method for writing on a capacitive touch screen according to claim 1, wherein the second conductive strips are on the same layer as the first conductive strips or on a layer further away from an insulating surface layer, wherein the stylus approaches or touches the insulating surface layer, and the guarding pattern is positioned between the insulating surface layer and the conductive strip pattern.

6. The method for writing on a capacitive touch screen according to claim 1, wherein the conductive strip pattern allows that, when a touch range of each external conductive object on the capacitive touch screen is larger than a predetermined condition, the exposed area of the guarding pattern covered by each touch range is larger than the exposed area of the second conductive strips covered by the touch range or larger than the exposed area of the conductive strip pattern covered by the touch range, or the exposed areas of the guarding pattern and the first conductive strips covered by each touch range is larger than the exposed area of the second conductive strips covered by the touch range.

7. The method for writing on a capacitive touch screen according to claim 6, wherein the predetermined condition is a width or an area, and the exposed area of the first conductive strips is greater than the exposed area of the second conductive strips.

8. A capacitive writing system, comprising:

a capacitive touch screen, including;

a conductive strip pattern having a plurality of conductive strips exposed from each other, the conductive strip pattern including a plurality of first conductive strips and a plurality of second conductive strips overlapping each other; and

a guarding pattern;

a stylus with a conductive pen head and an insulating pen body, when the stylus covering both the conductive strip pattern and the guarding pattern and the conductive pen head not electrically coupled to a grounded object holding the insulating pen body, the conductive pen head being capacitively coupled to the conductive strip pattern and the guarding pattern, respectively, causing the conductive strip pattern to generate a change in capacitive coupling; and

a driving/detecting unit for providing a driving signal to at least one of the first conductive strips and providing a DC signal to at least one of the first conductive strips not provided with the driving signal and the guarding pattern, and determining the location of the stylus by detecting the change in capacitive coupling on the conductive strip pattern.

9. The capacitive writing system according to claim 8, wherein there is no other signal sent to the capacitive touch screen by the conductive pen head apart from the capacitive coupling between the conductive pen head and the capacitive touch screen.

10. The capacitive writing system according to claim 8, wherein the guarding pattern covers the conductive strip pattern.

11. The capacitive writing system according to claim 8, wherein the guarding pattern includes a plurality of guarding conductive strips, the guarding conductive strips have a plurality of openings, wherein the intervals between the guarding conductive strips expose one of the first conductive strips and the second conductive strips, and the openings expose the other of the first conductive strips and the second conductive strips.

12. The capacitive writing system according to claim 8, wherein the second conductive strips are on the same layer as the first conductive strips or on a layer further away from an insulating surface layer, wherein the stylus approaches or touches the insulating surface layer, and the guarding pattern is positioned between the insulating surface layer and the conductive strip pattern.

13. The capacitive writing system according to claim 8, wherein the conductive strip pattern allows that, when a touch range of each external conductive object on the capacitive touch screen is larger than a predetermined condition, the exposed area of the guarding pattern covered by each touch range is larger than the exposed area of the second conductive strips covered by the touch range or larger than the exposed area of the conductive strip pattern covered by the touch range, or the exposed areas of the guarding pattern and the first conductive strips covered by each touch range is larger than the exposed area of the second conductive strips covered by the touch range.

14. The capacitive writing system according to claim 13, wherein the predetermined condition is a width or an area, and the exposed area of the first conductive strips is greater than the exposed area of the second conductive strips.