Device and method for pointer system of digitizer tablet

• US 7,176,907 B2
• Filed: 10/23/2002
• Issued: 02/13/2007
• Est. Priority Date: 05/24/2002
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Waltop International Corp.
• Inventors: Chao, Ching-Chuan, Hsu, Chung-Wen
• Primary Examiner(s): Lefkowitz; Sumati
• Assistant Examiner(s): PHAM, TAMMY T
• Application Number:
  US10/277,752
• Publication Number:
  US 20030217871A1
• Time in Patent Office: 1,574 Days
• Field of Search: 345/173, 345/174, 345/179, 345/19, 345178- 9, 178/19.01, 178/19.03, 178/20.1, 178/20.2, 178/20.3, 178/20.4, 178/18.01
• US Class Current: 345/179
• 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 a pointer system of a digitizer tablet device, which comprises a digitizer tablet and a wireless pointer device, said digitizer tablet having a plurality of electromagnetic inductive loops arranged in order, said wireless pointer device having an energy-storing resonant circuit, said method comprising the following steps:

(A) emitting a first signal from an m^th inductive loop on the digitizer tablet, and causing the resonant circuit of the wireless pointer device to emit a resonant signal after resonation and energy storing, wherein m is a positive integer;

(B) receiving said resonant signal by an (m−

n)^th inductive loop on the digitizer tablet, wherein n is an integer;

(C) progressively increasing a value of (m−

n) and repeating steps (A) and (B) until the (m−

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

(D) changing the frequency of the resonant signal emitted by the wireless pointer device by changing a variable inductance and capacitance such that the frequency of the resonant signal increases when the tip of the wireless pointer device is pressed against the digitizer tablet device, and decreases when the key switch on the wireless pointer device is pressed; and

,

(E) calculating a coordinate position on the digitizer table of the wireless pointer device according to the frequencies of the resonant signals received by the (m−

n)^th to (m−

n+i)^th 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) globally scanning the digitizer tablet to initially identify that the wireless pointer device is relatively closer to a certain inductive loop on the digitizer tablet, said inductive loop initially identified to be closer to the wireless pointer device being said m^th inductive loop.

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

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

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

n)^th to (m−

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

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

6. The signal transmitting method of claim 1, wherein said plurality of inductive loops receive amplitude information and frequency information of said resonant signal.

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 is a batteryless digital pen.

9. The signal transmitting method of claim 1, wherein starting terminals of three inductive loops are included in one set of inductive loops.

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

11. A pointer system for a digitizer tablet device comprising:

a) a wireless pointer device having a tip and a key switch; and

b) a digitizer tablet, which further comprises;

i) a plurality of electromagnetic inductive loops oriented in X-axis and Y-axis directions of a coordinate system, each forming specific inductive scope;

ii) an analog switch and selecting circuit connected with said electromagnetic inductive loops and controlling induction of the electromagnetic inductive loops in X-axis and Y-axis directions in said electromagnetic inductive loops through a microprocessor, including a number of switches equal to the number of said plurality of electromagnetic inductive loops;

iii) 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 loops, the amplifying circuit amplifying and then outputting the signals;

iv) a filtering circuit, receiving signals output by said amplifying circuit and outputting filtered signals to said microprocessor;

v) a waveform amplitude regulating circuit, receiving signals output by said filtering circuit and outputting amplitude regulated signals to said microprocessor;

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

vii) a power supply circuit in the wireless pointer device receiving a pulse wave controlling signal and a pulse wave signal of predetermined frequency output by said microprocessor, an energy source of the wireless pointer device is supplied by said pulse wave signal and said electromagnetic inductive loops, wherein said wireless pointer device changes resonant frequency by changing a variable inductance and capacitance such that the frequency of the resonant signal increases when the tip of the wireless pointer device is pressed against the digitizer tablet device, and decreases when the key switch on the wireless pointer device is pressed; and

viii) a tri-state driving circuit receiving an 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 loops for enhancing said pulse wave signal;

wherein, said microprocessor controls and receives signals of said waveform amplitude regulating circuit and said frequency/voltage converting circuit, and processes the signals received to determine the X-axis and Y-axis position of the wireless pointer device on the digitizer tablet.

12. The pointer system for a digitizer tablet of claim 11, wherein said wireless pointer device is a wireless digital pen.

13. The pointer system for a digitizer tablet of claim 11, wherein said wireless pointer device is a batteryless and wireless pointer device.

14. The pointer system for a digitizer tablet of claim 11, wherein said wireless pointer device is a batteryless and wireless digital pen.

15. The pointer system for a digitizer tablet of claim 11, wherein a variation of intensity of resonant signals induced by the inductive loops is in a linear relationship.

16. The pointer system for a digitizer tablet of claim 11, wherein start terminals of three inductive loops are included in one set of inductive loops.

17. The pointer system for a digitizer tablet of claim 11, wherein said amplifying circuit is controlled by a suppressing signal of said microprocessor for determining signals sent to said filtering circuit.

18. The pointer system for a digitizer tablet of claim 11, wherein said filtering circuit includes a high pass filtering circuit.

19. The pointer system for a digitizer tablet of claim 11, wherein the wireless pointer device comprises a resonant circuit in which a variable inductance and a plurality of capacitance are connected in parallel, said resonant circuit inducting and receiving electromagnetic energy provided by inductive loops of the digitizer tablet as source of energy;

the wireless pointer device further comprising key switch connected in series with one of the plurality of capacitance and a stylus connected with said variable inductance, such that when the key switch is switched off, a resonant frequency of the resonant circuit will be decreased, and when the stylus is pressed down, a variation of said variable inductance will increase the resonant frequency of resonant circuit.

20. A method for transmitting signals between a digitizer tablet and a wireless pointer device, wherein a plurality of electromagnetic inductive loops are oriented in X-axis and Y-axis directions of a coordinate system in the digitizer tablet induct electromagnetic signals, including conducting a full scan of said digitizer tablet to detect the wireless pointer device, thereafter conducting a partial scan after the full scan identifies an inductive loop where said wireless pointer device is located, the position determined by a first inductive loop having a most intensive induction among said plurality of inductive loops, said first loop emitting signals repeatedly and for a plurality of times at a first time interval;

said wireless pointer device carrying out energy-storing and resonating processes and then emitting corresponding resonant signals, wherein said wireless pointer device changes resonant frequency by changing a variable inductance and capacitance such that the frequency of the resonant signal increases when the tip of the wireless pointer device is pressed against the digitizer tablet device, and decreases when the key switch on the wireless pointer device is pressed; and

a plurality of inductive loops located close to the first inductive loop receiving said resonant signals at a second time interval.

21. The signal transmitting method of claim 20, wherein said plurality of sets of inductive loops receive amplitude information and frequency information of said resonant signal.

22. The signal transmitting method of claim 20, wherein said wireless pointer device is a wireless digital pen.

23. The signal transmitting method of claim 20, wherein said wireless pointer device is a batteryless digital pen.

24. The signal transmitting method of claim 20, wherein start terminals of three sets of inductive loops are included in one set of inductive loops.