Touch sensitive processing apparatus and system for despreading and method thereof

1. A despreading method being applicable to a touch sensitive screen for rapid recognition of approaching styluses, the touch sensitive screen comprising a plurality of first electrodes being parallel to a first axis and a plurality of second electrodes being parallel to a second axis, the despreading method comprising:

having an analog switch or a digital adder for coupling at least two of the plurality of second electrodes as a synchronization channel for achieving rapid detection rate and allow simultaneous detection of multiple styluses;

despreading a first preamble code of a first signal frame of received signal from the synchronization channel to retrieve a first synchronization information according to a first pseudo noise code, wherein the first signal frame is from a first active stylus approaching the touch sensitive screen;

decoding a first data code behind the first preamble code of received signal from at least one of the plurality of first electrodes in accordance with the first synchronization information and the first pseudo noise code in order to receive information from the first active stylus;

despreading a second preamble code of a second signal frame of received signal from the synchronization channel to retrieve a second synchronization information according to a second pseudo noise code, wherein the second signal frame is from a second active stylus approaching the touch sensitive screen; and

decoding a second data code behind the second preamble code of received signal from at least one of the plurality of first electrodes in accordance with the second synchronization information and the second pseudo noise code in order to receive information from the second active stylus.

2. The despreading method of claim 1 , wherein the first signal frame is from a first active stylus approaching the touch sensitive screen, the first data code comprises at least one type of following information:

a pressure on a tip section of stylus;

sensing value presenting whether a button being pressed or not;

sensing value of attitude of a gyroscope;

sensing value of acceleration of an accelerometer;

sensing value of battery power;

serial number of stylus; and

wireless signal intensity received by stylus.

3. The despreading method of claim 1 , wherein the synchronization channel couples all of the plurality of second electrodes.

4. The despreading method of claim 1 , wherein an electrical signal used for decoding the first data code is from one of the plurality of first electrodes which receives a largest electrical signal amount.

5. The despreading method of claim 1 , wherein an electrical signal used for decoding the first data code is from some of the plurality of first electrodes.

6. The despreading method of claim 1 , further comprising:

calculating a plurality of deviations of signal correlations of the plurality of first electrodes according to the first synchronization information; and

calculating a position of a first active stylus emitting the first signal frame on the second axis according to the plurality of deviations.

7. The despreading method of claim 1 , wherein the first signal frame and the second signal frame have at least some parts concurrently appearing in the signal received by the plurality of first electrodes.

8. A touch sensitive system for despreading and for rapid recognition of approaching styluses, comprising:

a touch sensitive screen, comprising a plurality of first electrodes being parallel to a first axis and a plurality of second electrodes being parallel to a second axis; and

a touch sensitive processing apparatus, connected to the plurality of first electrodes and the plurality of second electrodes, the touch sensitive processing apparatus, comprising an analog switch or a digital adder, configured to perform the following steps comprising:

coupling at least two of the plurality of second electrodes as a synchronization channel for achieving rapid detection rate and allow simultaneous detection of multiple styluses, wherein said coupling is implemented by the analog switch or the digital adder;

despreading a first preamble code of a first signal frame of received signal from the synchronization channel to retrieve a first synchronization information according to a first pseudo noise code, wherein the first signal frame is from a first active stylus approaching the touch sensitive screen;

decoding a first data code behind the first preamble code of received signal from at least one of the plurality of first electrodes in accordance with the first synchronization information and the first pseudo noise code in order to receive information from the first active stylus;

despreading a second preamble code of a second signal frame of received signal from the synchronization channel to retrieve a second synchronization information according to a second pseudo noise code, wherein the second signal frame is from a second active stylus approaching the touch sensitive screen; and

decoding a second data code behind the second preamble code of received signal from at least one of the plurality of first electrodes in accordance with the second synchronization information and the second pseudo noise code in order to receive information from the second active stylus.

9. A touch sensitive processing apparatus for despreading and rapid recognition of approaching styluses, connected to a plurality of first electrodes being parallel to a first axis and a plurality of second electrodes being parallel to a second axis on a touch sensitive screen, the touch sensitive processing apparatus, comprising an analog switch or a digital adder, configured to perform the following steps comprising:

coupling at least two of the plurality of second electrodes as a synchronization channel for achieving rapid detection rate and allow simultaneous detection of multiple styluses, wherein said coupling is implemented by the analog switch or the digital adder;

despreading a first preamble code of a first signal frame of received signal from the synchronization channel to retrieve a first synchronization information according to a first pseudo noise code, wherein the first signal frame is from a first active stylus approaching the touch sensitive screen;

decoding a first data code behind the first preamble code of received signal from at least one of the plurality of first electrodes in accordance with the first synchronization information and the first pseudo noise code in order to receive information from the first active stylus;

despreading a second preamble code of a second signal frame of received signal from the synchronization channel to retrieve a second synchronization information according to a second pseudo noise code, wherein the second signal frame is from a second active stylus approaching the touch sensitive screen; and

decoding a second data code behind the second preamble code of received signal from at least one of the plurality of first electrodes in accordance with the second synchronization information and the second pseudo noise code in order to receive information from the second active stylus.

10. The touch sensitive processing apparatus of claim 9 , wherein the first signal frame is from a first active stylus approaching the touch sensitive screen, the first data code comprises at least one type of following information:

a pressure on a tip section of stylus;

sensing value presenting whether a button being pressed or not;

sensing value of attitude of a gyroscope;

sensing value of acceleration of an accelerometer;

sensing value of battery power;

serial number of stylus; and

wireless signal intensity received by stylus.

11. The touch sensitive processing apparatus of claim 9 , wherein the synchronization channel couples all of the plurality of second electrodes.

12. The touch sensitive processing apparatus of claim 9 , wherein an electrical signal used for decoding the first data code is from one of the plurality of first electrodes which receives a largest electrical signal amount.

13. The touch sensitive processing apparatus of claim 9 , wherein an electrical signal used for decoding the first data code is from some of the plurality of first electrodes.

14. The touch sensitive processing apparatus of claim 9 , further configured to perform the following steps comprising:

calculating a plurality of deviations of signal correlations of the plurality of first electrodes according to the first synchronization information; and

calculating a position of a first active stylus emitting the first signal frame on the second axis according to the plurality of deviations.

15. The touch sensitive processing apparatus of claim 9 , wherein the first signal frame and the second signal frame have at least some parts concurrently appearing in the signal received by the plurality of first electrodes.