POINTER, POSITION DETECTION APPARATUS AND POSITION DETECTION METHOD

• US 20110193776A1
• Filed: 09/08/2010
• Published: 08/11/2011
• Est. Priority Date: 02/05/2010
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Oda, Yasuo, Yamamoto, Sadao, Sugiyama, Yoshihisa
• Granted Patent: US 8,963,889 B2
• Time in Patent Office: Days
• US Class Current: 345/157
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• 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 3/046 by electromagnetic means

Abstract

A position detection apparatus of the electrostatic coupling type is provided, to detect not only a position of a pointer but also information other than the position information such as, for example, pointer pressure or side switch information. The pointer transmits two codes such that a pressure applied to a pen tip is associated with a time difference between the two codes. A position detector carries out a correlation matching operation between signals generated in reception conductors and correlation calculation codes corresponding to the two codes, to thereby detect a position on a sensor section pointed to by the pointer from a result of the correlation matching operation and based on at least one of the codes. The position detector further includes a pressure calculation circuit for detecting pressure applied to the pointer, which is associated with the time difference between the two codes, from the result of the correlation matching operation calculated by the correlation matching operation and based on the two codes.

Claims

1. A position detection apparatus, comprising:

a pointer including a transmission signal production section, which is configured to produce a signal based on two codes such that a pressure applied to said pointer is associated with a time difference between the two codes, the pointer being configured to transmit the signal produced by said transmission signal production section;

a sensor section including a plurality of first conductors disposed in a predetermined direction and a plurality of second conductors disposed in a direction crossing with the predetermined direction and configured to receive the signal transmitted from said pointer;

a correlation matching operation circuit configured to carry out a correlation matching operation between signals generated in conductors which form the plurality of first conductors and conductors which form the plurality of second conductors and correlation calculation codes corresponding to the two codes;

a position calculation circuit configured to detect a position on said sensor section pointed to by said pointer, based on a result of the correlation matching operation calculated by said correlation matching operation circuit and based on at least one of the codes; and

a pressure calculation circuit configured to detect the pressure applied to the pointer in accordance with the time difference between the two codes, based on the result of the correlation matching operation calculated by said correlation matching operation circuit and based on the two codes.

2. The position detection apparatus according to claim 1, further comprising a selection circuit configured to select a conductor in a predetermined procedure from among the plurality of first conductors and select a conductor in a predetermined procedure from among the plurality second conductors, wherein signals generated in the conductors selected by said selection circuit are supplied to said correlation matching operation circuit.

3. The position detection apparatus according to claim 1, wherein the two codes have the same code pattern.

4. The position detection apparatus according to claim 1, wherein the two codes have code patterns different from each other.

5. The position detection apparatus according to claim 1, wherein said transmission signal production section includes a modulation circuit for modulating the codes, further comprising a demodulation circuit for demodulating signals generated in the conductors which form the plurality of first conductors and the conductors which form the plurality of second conductors.

6. The position detection apparatus according to claim 1, wherein said pointer has a projecting end portion and a pressure detection element configured to detect a pressure applied to the end portion, and wherein the time difference between the codes is set in response to a signal detected by said pressure detection element.

7. The position detection apparatus according to claim 6, wherein said pressure detection element includes a variable capacitor having a capacitance, which varies when said variable capacitor is pressed in response to the pressure applied to the end portion, and the time difference between the codes is controlled in response to a capacitance variation of said variable capacitor.

8. The position detection apparatus according to claim 1, wherein said sensor section includes an excitation coil, and said pointer includes a power production circuit for receiving an excitation signal signaled from said excitation coil to produce power for driving said transmission signal production section provided in said pointer.

9. The position detection apparatus according to claim 1, wherein a hovering state and a pen down state of said pointer can be identified in response to pressure detected by said pressure calculation circuit.

10. The position detection apparatus according to claim 1, wherein the two codes have code patterns different from each other, and a hovering sate and a pen down state of said pointer can be identified by detecting that a code is changed from one code to another code based on a result of the correlation matching operation obtained by supplying the signal transmitted from said pointer to said correlation matching operation circuit.

11. The position detection apparatus according to claim 1, wherein an operation switch is provided on a side face of said pointer, and a code inversion circuit configured to invert the codes in response to an operation of said operation switch is provided in said pointer, and a correlation matching operation of an inverted code signal generated in response to the operation of said operation switch is carried out by said correlation matching operation circuit to thereby allow detection of the operation of said operation switch.

12. The position detection apparatus according to claim 1, wherein an operation switch is provided on a side face of said pointer and, when a signal based on a code corresponding to the operation of said operation switch is produced by said transmission signal production section, a correlation matching operation of the code produced in response to the operation of said operation switch is carried out by said correlation matching operation circuit to thereby allow detection of the operation of said operation switch.

13. The position detection apparatus according to claim 1, wherein the pointer comprises an end portion used for detection of a pointed position and a pressure applied to said pointer projecting from a housing of said pointer, wherein said end portion has conductivity such that a signal produced by said transmission signal production section is transmitted through said end portion.

14. The position detection apparatus according to claim 1, further comprising a code production section configured to produce a predetermined code, and a first changeover section configured to carry out changeover between a supplying process of supplying the code produced by said code production section to the plurality of first conductors disposed in the predetermined direction and a reception process of receiving the signals generated in the plurality of first conductors disposed in the predetermined direction, wherein changeover control between the supplying process and the reception process is carried out alternately by said first changeover section to detect a position on said sensor section pointed to by a second pointer which is different in type from said pointer.

15. The position detection apparatus according to claim 14, further comprising a second changeover section configured to carry out changeover between a signal generated in a first conductor disposed in the predetermined direction and outputted from said first changeover section and another signal generated in a second conductor disposed in a direction crossing with the predetermined direction, time-divisionally, to supply the signals to said correlation matching operation circuit.

16. The position detection apparatus according to claim 14, wherein the code produced by said code production section is different from a code produced by the transmission signal production section provided in said pointer.

17. The position detection apparatus according to claim 1, wherein a plurality of electrode pieces respectively corresponding to a plurality of signals produced by said transmission signal production section are disposed in said pointer in order to transmit the plurality of signals, and the signals are transmitted respectively through said plurality of electrode pieces to be received by said sensor section for detecting an operation state of said pointer.

18. The position detection apparatus according to claim 17, wherein the operation state of said pointer to be detected is at least one of a rotational state of said pointer around a pen tip axis thereof, an inclination of said pointer with respect to a plane formed by said sensor section, and a rotational angle of said pointer projected to the plane formed by said sensor section where said pointer is operated with its pen tip as a reference point.

19. A pointer having an end portion, which projects from a housing for pointing to a position, the pointer comprising:

a transmission signal production section configured to produce two codes such that a pressure applied to said end portion is associated with a time difference between the two codes;

wherein the codes produced by said transmission signal production section are transmitted.

20. The pointer according to claim 19, wherein the two codes have the same code pattern.

21. The pointer according to claim 19, wherein the two codes have code patterns different from each other.

22. The pointer according to claim 19, wherein said transmission signal production section includes a modulation circuit for modulating the codes.

23. The pointer according to claim 19, further comprising a pressure detection element configured to detect a pressure applied to said end portion, wherein the time difference between the codes is set in response to a signal detected by said pressure detection element.

24. The pointer according to claim 23, wherein said pressure detection element is a variable capacitor having a capacitance which varies when said variable capacitor is pressed in response to the pressure applied to said end portion, and the time difference between the codes is controlled in response to a capacitance variation of said variable capacitor.

25. The pointer according to claim 19, further comprising an operation switch provided on a side face of said pointer, and a code inversion circuit configured to invert the codes in response to an operation of said operation switch.

26. The pointer according to claim 19, further comprising an operation switch provided on a side face of said pointer, wherein a code corresponding to the operation of said operation switch is produced by said transmission signal production section.

27. The pointer according to claim 19, wherein said end portion for pointing to a position has conductivity such that at least one code produced by said transmission signal production section is transmitted through said end portion.

28. The pointer according to claim 27, wherein a plurality of codes produced by said transmission signal production section are respectively transmitted through said end portion.

29. The pointer according to claim 19, wherein a plurality of electrode pieces that are configured to respectively transmit a plurality of codes produced by said transmission signal production section are disposed in the proximity of said end portion.

30. A position detection method, comprising:

a code transmission step for transmitting two codes having a time difference therebetween which corresponds to a pressure applied to a pen tip provided on a pointer for position pointing;

a signal reception step for receiving the codes transmitted from the pointer with a plurality of first conductors disposed in a predetermined direction and a plurality of second conductors disposed in a direction crossing with the predetermined direction;

a correlation matching operation processing step for receiving signals generated in conductors which form the plurality of first conductors and conductors which form the plurality of second conductors, and carrying out a correlation matching operation between the received signals and correlation calculation codes corresponding to the two codes;

a position calculation step for detecting a position on a sensor section pointed to by the pointer from a result of the correlation matching operation calculated in the correlation matching operation processing step and based on one of the codes; and

a pressure calculation step for detecting pressure applied to the pointer from the result of the correlation matching operation calculated in the correlation matching operation processing step and based on the two codes.

31. The position detection method according to claim 30, wherein the two codes have the same code pattern.

32. The position detection method according to claim 30, wherein the two codes have code patterns different from each other.

33. A pressure information transmission method, wherein two codes are transmitted such that a time difference therebetween is associated with pressure applied to a projecting end portion of a pointer for pointing to a position.

34. A pointer signal transmission method, comprising:

a code production step for producing a plurality of codes;

a step for supplying the plurality of codes respectively to corresponding ones of a plurality of electrode pieces electrically separated from each other; and

a step for transmitting the plurality of codes from the corresponding ones of the plurality of electrode pieces.