IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0506884
(2002-11-22)
|
등록번호 |
US-7406393
(2008-07-29)
|
우선권정보 |
GB-0205116.7(2002-03-05); GB-0209372.2(2002-04-24); WO-PCT/GB02/02387(2002-05-21); GB-0212699.3(2002-05-31) |
국제출원번호 |
PCT/GB02/005247
(2002-11-22)
|
§371/§102 date |
20050322
(20050322)
|
국제공개번호 |
WO03/075213
(2003-09-12)
|
발명자
/ 주소 |
- Ely,David Thomas Eliot
- McCaughan,Gareth John
- Foote,Geoffrey
|
출원인 / 주소 |
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
32 인용 특허 :
141 |
초록
▼
A low cost x-y digitising system is described for use in consumer electronic devices, such as portable digital assistants, mobile telephones, web browsers and the like. The digitiser includes a resonant stylus, an excitation winding for energising the resonant stylus and a set of sensor windings for
A low cost x-y digitising system is described for use in consumer electronic devices, such as portable digital assistants, mobile telephones, web browsers and the like. The digitiser includes a resonant stylus, an excitation winding for energising the resonant stylus and a set of sensor windings for sensing the signal generated by the stylus, from which the x-y position of the stylus is determined. A novel stylus design is described together with novel digitiser windings and novel excitation and processing circuitry.
대표청구항
▼
The invention claimed is: 1. A frequency determining system comprising: a signal generator operable, when energised by an alternating excitation signal, to generate an alternating response signal of predetermined but unknown frequency and whose amplitude varies in dependence upon the difference in
The invention claimed is: 1. A frequency determining system comprising: a signal generator operable, when energised by an alternating excitation signal, to generate an alternating response signal of predetermined but unknown frequency and whose amplitude varies in dependence upon the difference in frequency between the excitation signal and the response signal; an energising circuit operable to generate first and second excitation signals at first and second different excitation frequencies for energising said signal generator; a receiver operable to receive a first response signal generated by said signal generator when energised by said first excitation signal and a second response signal generated by said signal generator when energised by said second excitation signal; a processing circuit operable to process each of the first and second response signals received by said receiver to generate first and second amplitude measures indicative of the amplitudes of the corresponding response signals; and a determining circuit operable to determine a frequency measure indicative of the frequency of the alternating response signals generated by said signal generator using said first and second amplitude measures. 2. A system according to claim 1, wherein said processing circuit comprises: a mixing circuit operable to mix the first response signal with first and second mixing signals to provide first and second mixed signals and operable to mix the second response signal with third and fourth mixing signals to provide third and fourth mixed signals; and a combining circuit operable to combine the first and second mixed signals to provide said first amplitude measure and operable to combine the third and fourth mixed signals to provide said second amplitude measure. 3. A system according to claim 2, wherein said signal generator is a first signal generator and further comprising a second signal generator operable to generate said first, second, third and fourth mixing signals. 4. A system according to claim 3, wherein said second signal generator is operable to generate said mixing signals so that said first and second mixing signals are in phase quadrature and so that the said third and fourth mixing signals are in phase quadrature. 5. A system according to claim 4, wherein said second signal generator is operable to generate said first and second mixing signals at a frequency corresponding to said first excitation frequency and is operable to generate said third and fourth mixing signals at a frequency corresponding to said second excitation frequency. 6. A system according to claim 5, wherein said processing circuit is operable to process at least said first and second mixed signals to determine a phase measure which varies with the difference in frequency between the mixing signals and the respective response signal and wherein said determining circuit is operable to determine said frequency measure in dependence upon said amplitude measure and said phase measure. 7. A system according to claim 6, wherein said phase measure cyclically varies with the difference in frequency between the frequency of the alternating response signal and the corresponding mixing signals and wherein said determining circuit is operable to use said first and second amplitude measures to resolve the cyclic ambiguity associated with said phase measure. 8. A system according to claim 2, wherein said combining circuit is operable to combine said first and second mixed signals by taking the sum of the squares of the first and second mixed signals, to provide said first amplitude measure. 9. A system according to claim 2, wherein said combining circuit is operable to combine said third and fourth mixed signals by taking the sum of the squares of the third and fourth mixed signals, to provide said second amplitude measure. 10. A system according to claim 1, wherein said determining circuit is operable to determine an amplitude ratio by taking the ratio of the first and second amplitude measures and is operable to determine said frequency measure using said amplitude ratio. 11. A system according to claim 10, wherein said determining circuit is operable to determine said frequency measure in dependence upon a result of a non-linear function of said amplitude ratio. 12. A system according to claim 11, wherein said determining circuit is operable to determine said frequency measure in dependence upon a result of a logarithmic function of said amplitude ratio. 13. A system according to claim 11, wherein said determining circuit is operable to determine said frequency measure in dependence upon a result of an arc tangent function of said amplitude ratio. 14. A system according to claim 11, wherein said determining circuit is operable to determine said frequency measure by applying the result of said non-linear function to a predetermined linear transformation. 15. A system according to claim 14, wherein said determining circuit is programmable so that said predetermined linear transformation can be varied. 16. A system according to claim 11, wherein said determining circuit is programmable so that said non-linear function can be varied. 17. A system according to claim 1, wherein said energising circuit is operable to generate first and second electromagnetic signals at said first and second different excitation frequencies for energising said signal generator. 18. A system according to claim 1, wherein said signal generator is operable to generate alternating electromagnetic response signals when energised by said excitation signal. 19. A system according to claim 1, wherein said signal generator comprises a resonator. 20. A system according to claim 19, wherein said resonator is an electromagnetic resonant circuit. 21. A system according to claim 20, wherein said electromagnetic resonant circuit comprises a coil and a capacitor. 22. A system according to claim 1, wherein said signal generator is passive. 23. A system according to claim 1, wherein said signal generator is provided separate from but is electromagnetically coupled to said receiver. 24. A system according to claim 23, wherein said signal generator and said receiver are relatively movable. 25. A system according to claim 24, further comprising position processing circuitry operable to process at least one of said first and second response signals to determine the relative position between said signal generator and said receiver. 26. A system according to claim 1, wherein said signal generator is operable to vary the frequency of said response signal in dependence upon the value of a variable and wherein said determining circuit is operable to determine the value of said variable from the determined frequency measure. 27. A system according to claim 26, wherein said signal generator comprises an electrically resonant circuit and a component for varying the inductance, capacitance or resistance of the resonant circuit. 28. A system according to claim 27, wherein said component comprises a ferrite element which is displaceable relative to an inductance coil of said resonant circuit and wherein the position of said ferrite element relative to said coil is moved in dependence upon the value of said variable in order to vary the inductance of said coil and hence the resonant frequency of said resonant circuit. 29. A system according to claim 1 wherein said energising circuit is operable to generate said first excitation signal during a first time interval and is operable to generate said second excitation signal during a second time interval after said first time interval. 30. A system according to claim 29, wherein said processing circuit is operable to process the first response signal during a third time interval between said first and second time intervals and is operable to process said second response signal during a fourth time interval after said second time interval. 31. A system according to claim 1, wherein said energising circuit is operable to generate three or more excitation signals at respective different excitation frequencies, wherein said receiver is operable to receive three or more response signals generated by said signal generator when energised by the respective three or more excitation signals, wherein said processing circuit is operable to process said three or more response signals to generate three or more amplitude measures indicative of the amplitudes of the corresponding response signals; and wherein said determining circuit is operable to determine said frequency measure using said three or more amplitude measures. 32. A system according to claim 31, wherein said processing circuit is operable to process the first, second and third response signals to generate first, second and third processed signals respectively, wherein said processing circuit comprises a combining circuit operable to combine the first and second processed signals to remove a common offset from the first and second processed signals to provide a first combined signal and to combine the second and third processed signals to remove a common offset from the second and third processed signals and to provide a second combined signal, and wherein said processing circuit is operable to determine said first and second amplitude measures using said first and second combined signals. 33. An apparatus according to claim 1, wherein said receiver is operable to receive three or more response signals generated by said signal generator when energised by three or more excitation signals, wherein said processing circuit is operable to process said three or more response signals to generate three or more amplitude measures indicative of the amplitudes of the corresponding response signals; and wherein said determining circuit is operable to determine said frequency measure using said three or more amplitude measures. 34. An apparatus according to claim 33, wherein said processing circuit is operable to process the first, second and third response signals to generate first, second and third processed signals respectively, wherein said processing circuit comprises a combining circuit operable to combine the first and second processed signals to remove a common offset from the first and second processed signals to provide a first combined signal and to combine the second and third processed signals to remove a common offet from the second and third processed signals and to provide a second combined signal, and wherein said processing circuit is operable to determine said first and second amplitude measures using said first and second combined signals. 35. A positioning system comprising first and second relatively moveable members, the first member comprising a signal generator operable, when energised by an alternating excitation signal, to generate an alternating response signal of predetermined but unknown frequency and whose amplitude varies in dependence upon the difference in frequency between the excitation signal and the response signal; and the second member comprising: an energising circuit operable to generate first and second excitation signals at first and second different excitation frequencies for energising said signal generator; a receiver operable to receive a first response signal generated by said signal generator when energised by said first excitation signal and a second response signal generated by said signal generator when energised by said second excitation signal; a processing circuit operable to process each of the first and second response signals received by said receiver to generate first and second amplitude measures indicative of the amplitudes of the corresponding response signals; a determining circuit operable to determine a frequency measure indicative of the frequency of the alternating response signals generated by said signal generator using said first and second amplitude measures; and a positioning circuit operable to process at least one of the first and second response signals to determine the relative position between the first and second members. 36. A positioning system according to claim 35, wherein said signal generator is operable to vary the frequency of said response signal in dependence upon a status of the first member and wherein said second member further comprises a second determining circuit operable to determine the status of said first member using the determined frequency measure. 37. A positioning system according to claim 36, wherein said first member comprises a position pointer, wherein said second member comprises an x-y digitising tablet and wherein said signal generator is operable to vary the frequency of said response signal when the position pointer is brought into contact with an x-y digitising surface of said tablet. 38. A positioning system according to claim 35, wherein said processing circuit comprises: a mixing circuit operable to mix the first response signal with first and second mixing signals to provide first and second mixed signals and operable to mix the second response signal with third and fourth mixing signals to provide third and fourth mixed signals; and a combining circuit operable to combine the first and second mixed signals to provide said first amplitude measure and operable to combine the third and fourth mixed signals to provide said second amplitude measure.
※ AI-Helper는 부적절한 답변을 할 수 있습니다.