Device and method for pointer system of digitizer tablet

• US 20030217871A1
• Filed: 10/23/2002
• Published: 11/27/2003
• Est. Priority Date: 05/24/2002
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Aiptek International Incorporated (Aiptek Incorporated)
• Inventors: Hsu, Chung-Wen, Chao, Ching-Chuan
• Granted Patent: US 7,176,907 B2
• Time in Patent Office: Days
• US Class Current: 178/18.01
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

The invention, an improved device and method for the pointer system of a digitizer tablet, is to repetitiously emit signals sequentially from a specific set of inductive loop when the position pointed by the wireless pointer device is located within a range formed by this specific set of inductive loop induced most intensively during a locally scanning process. After a transient energy storage of the wireless pointer device, corresponding resonant signals are emitted out and are received sequentially by several sets of inductive loop located on the digitizer tablet in the neighborhood of this specific set of inductive loop and, by these signals, the wireless pointer device'"'"'s coordinate position on the digitizer tablet is calculated out relatively. Thereby, the intensities of the resonant signals received by these several sets of inductive loop will be displayed as a linear distribution, such that the calculation formula for coordinate position and the design for relative circuit elements may be simplified greatly, and the production cost and the power consumption may further be lowered down effectively.

Claims

1. A signal transmitting method for the pointer system of digitizer tablet, which comprises a digitizer tablet and a wireless pointer device, said digitizer tablet having a plurality of sets of electromagnetic inductive loop arranged in order, said wireless pointer device having energy-storing resonant circuit, said method comprising the following steps:

(A) emitting a first signal from a m^th set of inductive loops on digitizer tablet, and emitting a resonant signal from resonant circuit of wireless pointer device after resonation and energy storing, m being a positive integer;

(B) receiving said resonant signal with the (m−

n)^th set of inductive loops on digitizer tablet, n being a integer;

(C) increasing value of (m-n) progressively, repeating above-mentioned steps (A) and (B) till the (m−

n+i)^th set of inductive loops receives said resonant signal, i being a positive integer;

(D) calculating relative coordinate position on digitizer tablet of wireless pointer device according to resonant signals received by the (m−

n)^th to (m−

n+i)^th set of inductive loops on said digitizer tablet.

2. The signal transmitting method of claim 1, wherein the following step is further included before step (A):

(A0) proceeding global scan to initially identify that wireless pointer device is relatively closer to certain inductive loop on digitizer tablet, said inductive loop initially identified to be closer to wireless pointer device being said m^th inductive loop.

3. The signal transmitting method of claim 1, wherein when value of (m−

n) is lower than 1, step (B) will be omitted.

4. The signal transmitting method of claim 1, wherein intensity of resonant signals received by the (m−

n)^th to (m−

n+i)^th set of inductive loops changes according to linear relationship.

5. The signal transmitting method of claim 1, wherein i=2n+1.

6. The signal transmitting method of claim 1, wherein said wireless pointer device is inducted by said a plurality of sets of inductive loops according to variation of frequency.

7. The signal transmitting method of claim 1, wherein said wireless pointer device is a wireless digital pen.

8. The signal transmitting method of claim 1, wherein said wireless pointer device changes resonant frequency by changing inductance and capacitance.

9. The signal transmitting method of claim 1, wherein said wireless pointer device is a batteryless digital pen.

10. The signal transmitting method of claim 1, wherein starting terminals of next three other sets of inductive loops can be included in one inductive loop.

11. The signal transmitting method of claim 1, wherein a variable inductive circuit is further included in wireless pointer device.

12. The signal transmitting method of claim 1, wherein the wireless pointer device has a resonant circuit in which variable inductance several capacitances are in parallel connection, said resonant circuit inducting and receiving electromagnetic energy provided by inductive loops of digitizer tablet as source of energy;

the wireless pointer device also has a key switch in series connection with one of the capacitances and a stylus connected with said variable inductance;

when the key switch is switched off, resonant frequency of resonant circuit will be decreased, and when the pen nib is pressed down, variation of said variable inductance will increase the resonant frequency of resonant circuit.

13. A pointer system of digitizer tablet comprising:

a wireless pointer device; and

a digitizer tablet, which further comprises;

an electromagnetic inductive loop, having several inductive loops in X-axis and Y-axis directions of coordinate system, each forming specific inductive scope;

an analog switch and selecting circuit, being connected with said electromagnetic inductive loop and being able to control induction of electromagnetic inductive loops in X-axis and Y-axis directions in said electromagnetic inductive loop through a microprocessor, number of switches being set up according to number of said inductive loops;

an amplifying circuit, receiving a suppressing signal of said microprocessor and output inductive signals from said analog switch and selecting circuit and said electromagnetic inductive loop, amplifying and then outputting the signals;

a filtering circuit, receiving signal output by said amplifying circuit and outputting filtered signal to said microprocessor;

a waveform amplitude regulating circuit, receiving signal output by said filtering circuit and outputting an amplitude regulated signal to said microprocessor;

a frequency/voltage converting circuit, receiving signal output by said filtering circuit and converting it into a voltage signal, sending said voltage signal to said microprocessor for processing, the signal being saved temporarily in said microprocessor after being processed;

a power supply circuit of wireless pointer device, receiving a pulse wave controlling signal and pulse wave signal of specific frequency output by said microprocessor, and the energy source of the said wireless pointer device is supplied by the function of said pulse wave signal of specific frequency and said electromagnetic inductive loop; and

a tri-state driving circuit, receiving output from said power supply circuit of said wireless pointer device and outputting two sets of inverting signals of logical level respectively to said analog switch and selecting circuit and said electromagnetic inductive loop for enhancing said pulse wave signal of certain frequency;

wherein, said microprocessor being able to control and receive signal of said waveform amplitude regulating circuit and said frequency/voltage converting circuit, and process signal received.

14. The pointer system of digitizer tablet of claim 13, wherein said wireless pointer device is a wireless digital pen.

15. The pointer system of digitizer tablet of claim 13, wherein said wireless pointer device is a battery less wireless pointer device.

16. The pointer system of digitizer tablet of claim 13, wherein said wireless pointer device is a battery less wireless digital pen.

17. The pointer system of digitizer tablet of claim 13, wherein said wireless pointer device changes resonant frequency by changing inductance and capacitance.

18. The pointer system of digitizer tablet of claim 13, wherein said a plurality of sets of inductive loops induced by said wireless pointer device, position pointed out by said pointer device being in a pre-set section formed by certain set of inductive loops having the most intensive induction among said several sets of inductive loops, said certain set of inductive loops emitting signal repeatedly and for a plurality of times, energy-storing and resonating process being carried out on said signal by the wireless pointer device that then emits corresponding resonant signal, and a plurality of sets of inductive loops located close to said certain set of inductive loops receive said resonant signal transmitted by wireless pointer device respectively and orderly.

19. The pointer system of digitizer tablet of claim 18, wherein variation of intensity of resonant signals induced by the several sets of inductive loops is in linear relationship.

20. The pointer system of digitizer tablet of claim 13, wherein the start terminals of three sets of inductive loops can be included in one set of inductive loops.

21. The pointer system of digitizer tablet of claim 13, wherein said amplifying circuit can be controlled by a suppressing signal of said microprocessor for deciding signal sent to said filtering circuit.

22. The pointer system of digitizer tablet of claim 13, wherein said filtering circuit includes a high pass filtering circuit.

23. The pointer system of digitizer tablet of claim 13, wherein a full scan on coordinate position of location pointed out by said wireless pointer device is proceeded by said digitizer tablet;

after inductive loop where pointer device is located is identified by the full scan, a partial scan is then proceeded.

24. The pointer system of digitizer tablet of claim 13, wherein the wireless pointer device has a resonant circuit in which variable inductance several capacitances are in parallel connection, said resonant circuit inducting and receiving electromagnetic energy provided by inductive loops of digitizer tablet as source of energy;

the wireless pointer device also has a key switch in series connected with one of the capacitances and a stylus connected with said variable inductance;

when the key switch is switched off, resonant frequency of resonant circuit will be decreased, and when the stylus is pressed down, variation of said variable inductance will increase the resonant frequency of resonant circuit.

25. A method for transmitting signal between digitizer tablet and wireless pointer device applied in pointer system of digitizer tablet, electromagnetic inductive loops in X-axis and Y-axis directions of coordinate system being set on a circuit board in digitizer tablet that can induct electromagnetic signal, a full scan being proceeded before said digitizer tablet induct and detect wireless pointer device, a partial scan being proceeded after the full scan identifies the inductive loop where said wireless pointer device locates, position pointed out by said pointer device being in a pre-set section formed by the first set of inductive loops having the most intensive induction among said several sets of inductive loops, said first set of inductive loops emitting signal repeatedly and for several times at a first time interval, said wireless pointer device carrying out energy-storing and resonating process and then emitting corresponding resonant signal, and several sets of inductive loops located close to the first set of inductive loops receiving said resonant signal at a second time interval.

26. The signal transmitting method of claim 25, wherein said wireless pointer device is inducted by said a plurality of sets of inductive loops according to variation of frequency.

27. The signal transmitting method of claim 25, wherein said wireless pointer device is a wireless digital pen.

28. The signal transmitting method of claim 25, wherein said wireless pointer device changes resonant frequency by changing inductance and capacitance.

29. The signal transmitting method of claim 25, wherein said wireless pointer device is a battery less digital pen.

30. The signal transmitting method in claim 25, wherein the start terminals of three sets of inductive loops can be included in one set of inductive loops.