Touch sensing apparatus and method using different modulated driving signals

• US 8,791,907 B2
• Filed: 08/19/2009
• Issued: 07/29/2014
• Est. Priority Date: 08/19/2009
• Status: Expired due to Fees

• Current Assignee: Silicon Integrated Systems Corporation (Silicon Integrated Systems Corporation Taiwan)
• Original Assignee: U-Pixel Technologies, Inc.
• Inventors: Wu, Hung Wei
• Primary Examiner(s): Nguyen, Chanh
• Assistant Examiner(s): MISTRY, RAM A
• Application Number:
  US12/543,966
• Publication Number:
  US 20110042152A1
• Time in Patent Office: 1,805 Days
• Field of Search: 345/156, 345173-178, 178/18.01, 178/18.03
• US Class Current: 345/173
• 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

Abstract

A touch sensing apparatus utilizes the characteristics of orthogonal vectors is disclosed. A random spread spectrum (RSS) signal or a periodic wave is used to modulate a driving signal so as to driving a row of a sensing array, and the RSS signal or periodic wave is also use to extract touch information of a node from a sensing signal measured from a column of the sensing array. The node is an intersection of the driven row and the measured column. When different RSS signals and/or periodic waves are used to drive multiple rows simultaneously, multipoint touching information can be obtained from the same sensing signal at the same time by respectively using the RSS signals and/or periodic waves to extract touching information of multiple points which are the intersections of the driven rows and the measured column.

Claims

1. A touching sensing apparatus comprising:

a sensing array having multiple rows and multiple columns intersecting with each other to define multiple nodes;

a plurality of driving circuits, each for providing a driving signal, which is modulated by a modulation signal, to drive a row of the sensing array; and

a plurality of sensing circuits, each receiving a sensing signal measured from a column of the sensing array and extracting touching information of a node, which is an intersection of the driven row and the measured column, by using the modulation signal used by a corresponding one of the driving circuits,

wherein there is provided only one row per driving circuit and each row is driven with a different modulated driving signal provided by the driving circuit associated with that row, the modulated driving signal is modulated with a specific pseudorandom (PN) code, the PN code has a characteristic of random spread spectrum, and the sensing signal of the measured column is provided to the respective sensing circuits.

2. The touch sensing apparatus of claim 1, wherein each driving circuit comprises a pseudorandom noise (PN) code generator for providing the PN code as the modulation signal, the respective PN code generators provide different PN codes as the modulation signals.

3. The touch sensing apparatus of claim 1, wherein each driving circuit comprises a periodic wave generator for providing the periodic wave as the modulation signal, the respective periodic wave generators provide periodic waves of different frequencies as the modulation signals.

4. The touch sensing apparatus of claim 3, wherein the different frequencies are separated from each other by an interval of at least 10 kHz.

5. The touch sensing apparatus of claim 3, wherein the periodic waves are square waves.

6. The touch sensing apparatus of claim 3, wherein the periodic waves are sine waves.

7. The touch sensing apparatus of claim 1, wherein some of the driving circuits comprise PN code generators for respectively providing different PN codes, and the other driving circuits comprises periodic wave generators for respectively providing periodic waves of different frequencies.

8. The touch sensing apparatus of claim 7, wherein the PN code generators and the periodic wave generators are arranged alternately.

9. The touch sensing apparatus of claim 7, wherein the periodic waves are square waves of different frequencies.

10. The touch sensing apparatus of claim 7, wherein the periodic waves are sine waves of different frequencies.

11. A method for sensing a plurality of touch events to at least one touch sensing apparatus having a sensing array, the method comprising:

providing a plurality of driving circuits, each driving circuit comprises a pseudorandom noise (PN) code generator and a demodulator;

providing a plurality of driving signals respectively modulated by different modulation signals from each PN code generator to drive a plurality of traces of the sensing array;

the modulation signal including at least one PN code, and the PN code having a characteristic of random spread spectrum; and

respectively using the same modulation signals to extract touching information of the driven traces via each demodulator, wherein

each trace is driven with a different modulated driving signal provided by the driving circuit associated with that trace.

12. The method of claim 11, wherein the modulation signals comprise different random spread spectrum signals.

13. The method of claim 11, wherein the modulation signals comprise periodic waves of different frequencies.

14. The method of claim 11, wherein the modulation signals comprise different random spread spectrum signals and periodic waves of different frequencies.