IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0397121
(2009-03-03)
|
등록번호 |
US-8243033
(2012-08-14)
|
우선권정보 |
GB-0112332.2 (2001-05-21); GB-0205116.7 (2002-03-05) |
발명자
/ 주소 |
- Ely, David T. E.
- Foote, Geoffrey
- Haines, Julian
- McCaughan, Gareth J.
|
출원인 / 주소 |
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
5 인용 특허 :
148 |
초록
▼
A low-cost x-y digitizing system for use in consumer electronic devices, such as portable digital assistants, mobile telephones, web browsers and the like. The digitizer includes a resonant stylus, an excitation winding for energizing the resonant stylus and a set of sensor windings for sensing the
A low-cost x-y digitizing system for use in consumer electronic devices, such as portable digital assistants, mobile telephones, web browsers and the like. The digitizer includes a resonant stylus, an excitation winding for energizing 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 digitizer windings and novel excitation and processing circuitry.
대표청구항
▼
1. A position detector comprising: first and second relatively movable members, the first member comprising an electromagnetic resonator which, when energized, is operable to generate a resonator field which varies with time at a resonant frequency of the resonator; the second member comprising a se
1. A position detector comprising: first and second relatively movable members, the first member comprising an electromagnetic resonator which, when energized, is operable to generate a resonator field which varies with time at a resonant frequency of the resonator; the second member comprising a sensor winding operable to sense the resonator field and operable to output a sensed signal in response, wherein the sensed signal varies with time at said resonator frequency and varies with the relative position of said first and second members;excitation circuitry operable to generate a time varying excitation electromagnetic field comprising a sequence of excitation pulses, for energizing said resonator;processing circuitry operable to process said sensed signal to determine the relative position of said first and second members and to estimate the resonant frequency of said resonator; andcontrol circuitry operable to control said excitation circuitry and said processing circuitry to operate:(i) in a first stage in which said excitation circuitry is operable to generate an excitation field comprising a first number of excitation pulses at a predetermined excitation frequency and in which said processing circuitry is operable to process the resulting sensed signal to estimate the resonant frequency of said resonator; and(ii) in a second stage in which said excitation circuitry is operable to generate an excitation field comprising a second, greater number of excitation pulses substantially at the resonant frequency estimated in said first stage, and in which said processing circuitry is operable to process the resulting sensed signal to determine the relative position of said first and second members and/or to determine a more accurate estimate of the resonant frequency of said resonator. 2. The position detector of claim 1, wherein said control circuitry is operable to control said processing circuitry so that in said first stage, said processing circuitry is operable to process said sensed signal over a period of time corresponding to a third number of excitation pulses and, in said second stage, to cause said processing circuitry to process the sensed signal over a period of time corresponding to a fourth number, which is greater than said third number, of excitation pulses. 3. The position detector of claim 1, wherein said second member comprises a plurality of sensor windings, wherein said plurality of sensor windings includes said sensor winding, each sensor winding being operable to generate a respective sensed signal that varies with time at said resonator frequency and that varies with the relative position of said first and second members, and wherein said processing circuitry is operable to process the sensed signal output from each sensor winding of said plurality of sensor windings. 4. The position detector of claim 1, wherein said processing circuitry comprises: a first mixer for mixing the sensed signal with a first time varying mixing signal having said excitation frequency to generate a first mixed signal;a first integrator for integrating the first mixed signal over a time period corresponding to a third number of said excitation pulses, to generate a first signal value;a second mixer for mixing the sensed signal with a second time varying mixing signal having said excitation frequency, the second time varying mixing signal having a phase offset relative to said first time varying mixing signal, to generate a second mixed signal; anda second integrator for integrating the second mixed signal over a time period corresponding to the third number of said excitation pulses, to generate a second signal value. 5. The position detector of claim 4, wherein said processing circuitry is operable to process said first and second signal values to estimate the resonant frequency of said resonator and is operable to process at least one of said first and second signal values to determine the relative position between said first and second members, and wherein said control circuitry is operable to control said excitation circuitry and said processing circuitry so that: (i) in said first stage said processing circuitry processes the resulting first and second signal values to estimate the resonant frequency of said resonator; and(ii) in said second stage said processing circuitry processes the resulting first and second signal values to determine said more accurate estimate of the resonant frequency of said resonator and to process the resulting at least one of said first and second signal values to determine the relative position of said first and second members. 6. The position detector of claim 1, wherein said sensor winding comprises first and second loops of conductor which are arranged in succession along a measurement direction and connected so that an EMF induced in the first loop by a common background alternating magnetic field opposes the EMF induced in the second loop. 7. The position detector of claim 1, wherein said excitation circuitry is capacitively or magnetically coupled to said resonator. 8. The position detector of claim 1, wherein said control circuit is operable to control said processing circuitry such that in said second stage, said processing circuitry processes the resulting sensed signal to determine the relative position of said first and second members and to determine the more accurate estimate of the resonant frequency of said resonator. 9. The position detector of claim 1, wherein said control circuitry is operable to compare signals sensed by said sensor winding in said first stage with a threshold and is operable to inhibit the performance of said second stage in dependence upon a comparison result. 10. The position detector of claim 1, wherein said control circuitry is operable to vary the number of excitation pulses generated during said second stage. 11. The position detector of claim 1, wherein said first member has a plurality of operating states, each state being associated with a different resonant frequency of said resonator, and wherein said processing circuitry is operable to compare said estimated resonant frequency with stored information to determine a current operating state of said first member. 12. A position detector comprising: first and second relatively movable members, the first member comprising an electromagnetic resonator which, when energized, is operable to generate a resonator field that varies with time at a resonant frequency of the resonator; the second member comprising a sensor winding operable to sense the resonator field and operable to output a sensed signal in response, wherein the sensed signal varies with time at said resonator frequency and varies with the relative position of said first and second members;excitation circuitry operable to generate a time varying excitation electromagnetic field comprising a sequence of excitation pulses, for energizing said resonatorprocessing circuitry operable to process said sensed signal over a period of time corresponding to a number of excitation pulses, to estimate the resonant frequency of said resonator and to determine the relative position between said first and second members; andcontrol circuitry operable to control said excitation circuitry and said processing circuitry to operate:(i) in a first stage in which said excitation circuitry is operable to generate an excitation field comprising a sequence of excitation pulses at a predetermined excitation frequency and in which said processing circuitry is operable to process said sensed signal over a period of time corresponding to a first number of excitation pulses, to estimate the resonant frequency of said resonator; and(ii) in a second stage in which said excitation circuitry is operable to generate an excitation field comprising a sequence of excitation pulses substantially at the resonant frequency estimated in said first stage, and in which said processing circuitry is operable to process said sensed signal over a period of time corresponding to a second greater number of excitation pulses, to determine a more accurate estimate of said resonant frequency of said resonator and/or to determine the relative position between said first and second members. 13. The position detector of claim 12, wherein said control circuitry is operable to compare signals sensed by said sensor winding in said first stage with a threshold and is operable to inhibit the performance of said second stage in dependence upon a comparison result. 14. The position detector of claim 12, wherein said control circuitry is operable to vary the number of excitation pulses transmitted during said second stage. 15. The position detector of claim 12, wherein said first member has a plurality of operating states, each associated with a different resonant frequency of said resonator, and wherein said processing circuitry is operable to compare the estimated resonant frequency with stored information to determine a current operating state of said first member. 16. Excitation and processing electronics for use with a position detector used to determine the position of a resonator relative to at least one sensor conductor, the resonator being operable to generate a time varying resonator signal at a resonant frequency of the resonator and the sensor conductor being operable to sense the resonator signal and to output a sensed signal at said resonator frequency, wherein the sensed signal varies with the relative position between said resonator and said sensor conductor, the excitation and processing circuitry comprising: excitation circuitry operable to generate a time varying excitation electromagnetic field comprising a sequence of excitation pulses, for energizing said resonator;processing circuitry operable to process said sensed signal to estimate the resonant frequency of said resonator and to determine the relative position between said resonator and said sensor conductor; andcontrol circuitry operable to control said excitation circuitry and said processing circuitry to operate:(i) in a first stage in which said excitation circuitry is operable to generate an excitation field comprising a first number of excitation pulses at a predetermined excitation frequency and in which said processing circuitry is operable to process the resulting sensed signal to estimate the resonant frequency of said resonator; and(ii) in a second stage in which said excitation circuitry is operable to generate an excitation field comprising a second, greater number of excitation pulses substantially at the resonant frequency estimated in said first stage, and in which said processing circuitry is operable to process the resulting sensed signal to determine the relative position of said resonator and said sensor conductor and/or to determine a more accurate estimate of the resonant frequency of said resonator. 17. Excitation and processing electronics for use with a position detector used to determine the position of a resonator relative to at least one sensor conductor, the resonator being operable to generate a time varying resonator signal at a resonant frequency of the resonator and the sensor conductor being operable to sense the resonator signal and to output a sensed signal at said resonator frequency, wherein the sensed signal varies with the relative position between said resonator and said sensor conductor, the excitation and processing circuitry comprising: excitation circuitry operable to generate a time varying excitation electromagnetic field comprising a sequence of excitation pulses, for energizing said resonator;processing circuitry operable to process said sensed signal over a period of time corresponding to a number of said excitation pulses, to estimate the resonant frequency of said resonator and to determine the relative position between said resonator and said sensor conductor; andcontrol circuitry operable to control said excitation circuitry and said processing circuitry to operate:(i) in a first stage in which said excitation circuitry is operable to generate an excitation field comprising a number of excitation pulses at a predetermined excitation frequency, in which said processing circuitry is operable to process said sensed signal over a period of time corresponding to a first number of excitation pulses, to estimate the resonant frequency of said resonator; and(ii) in a second stage in which said excitation means is operable to generate an excitation field comprising a number of excitation pulses substantially at the resonant frequency estimated in said first stage, and in which said processing circuitry is operable to process said sensed signal over a period of time corresponding to a second, greater number of excitation pulses, to determine a more accurate estimate of said resonant frequency of said resonator and/or to determine the relative position between said first and second members. 18. A method performed by a position detector comprising first and second relatively movable members, the first member having an electromagnetic resonator which, when energized, is operable to generate a resonator field that varies with time at a resonant frequency of the resonator; the second member having a sensor conductor operable to sense the resonator field and operable to output a sensed signal in response, wherein the sensed signal varies with time at said resonator frequency and varies with the relative position of said first and second members, the method comprising: generating a time varying excitation electromagnetic field comprising a sequence of excitation pulses, for energizing said resonator;processing said sensed signal to determine the relative position of said first and second members and to estimate the resonant frequency of said resonator; andcontrolling said generating and said processing to operate:(i) in a first stage in which said generating generates an excitation field comprising a first number of excitation pulses at a predetermined excitation frequency and in which said processing processes the resulting sensed signal to estimate the resonant frequency of said resonator; and(ii) in a second stage in which said generating generates an excitation field comprising a second, greater number of excitation pulses substantially at the resonant frequency estimated in said first stage, and in which said processing processes the resulting sensed signal to determine the relative position of said first and second members and/or to determine a more accurate estimate of the resonant frequency of said resonator. 19. The method of claim 18, wherein said controlling controls said processing so that in said first stage, said processing processes said sensed signal over a period of time corresponding to a third number of excitation pulses and, in said second stage, said processing processes the sensed signal over a period of time corresponding to a fourth number, which is greater than said third number, of excitation pulses. 20. The method of claim 18, wherein said controlling compares signals sensed by said sensor conductor in said first stage with a threshold and is operable to inhibit the performance of said second stage in dependence upon a comparison result. 21. A method performed by a position detector comprising first and second relatively movable members, the first member having an electromagnetic resonator which, when energized, is operable to generate a resonator field that varies with time at a resonant frequency of the resonator; the second member having a sensor conductor operable to sense the resonator field and operable to output a sensed signal in response, wherein the sensed signal varies with time at said resonator frequency and varies with the relative position of said first and second members, the method comprising: generating a time varying excitation electromagnetic field comprising a sequence of excitation pulses, for energizing said resonator;processing said sensed signal to determine the relative position of said first and second members and to estimate the resonant frequency of said resonator; andcontrolling said generating and said processing to operate:(i) in a first stage in which said generating generates an excitation field comprising a number of excitation pulses at a predetermined excitation frequency, in which said processing processes said sensed signal over a period of time corresponding to a first number of excitation pulses, to estimate the resonant frequency of said resonator; and(ii) in a second stage in which said generating generates an excitation field comprising a number of excitation pulses substantially at the resonant frequency estimated in said first stage, and in which said processing processes said sensed signal over a period of time corresponding to a second, greater number of excitation pulses, to determine a more accurate estimate of said resonant frequency of said resonator and/or to determine the relative position between said first and second members. 22. The method of claim 21, wherein said processing processes said first and second signal values to estimate the resonant frequency of said resonator and to process at least one of said first and second signal values to determine the relative position between said first and second members, and wherein said controlling controls said generation and said processing so that: (i) in said first stage said processing processes the resulting first and second signal values to estimate the resonant frequency of said resonator; and(ii) in said second stage said processing processes the resulting first and second signal values to determine said more accurate estimate of the resonant frequency of said resonator and to process the resulting at least one of said first and second signal values to determine the relative position of said first and second members. 23. The method of claim 21, wherein said controlling compares signals sensed by said sensor conductor in said first stage with a threshold and is operable to inhibit the performance of said second stage in dependence upon a comparison result. 24. The method of claim 21, wherein said first member has a plurality of operating states, each state being associated with a different resonant frequency of said resonator, and wherein said processing compares said estimated resonant frequency with stored information to determine a current operating state of said first member.
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