Position sensor
First Claim
Patent Images
1. A position indicator for use with a position detector, the position indicator comprising:
- a housing;
a moveable nib extending from the housing and moveable relative to the housing between a retracted position and an extended position;
a sensing coil;
a flux linkage element which extends at least partially through the coil;
wherein said sensing coil and said flux linkage element are mounted for relative movement with the movement of said nib, whereby the inductance of said coil is changed with the movement of said nib; and
a magnetically permeable washer whose position is fixed relative to said sensing coil and which is arranged relative to the flux linkage element so that the distance between said washer and said flux linkage element varies with the movement of said nib relative to the housing.
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Accused Products
Abstract
A low cost x-y digitizing system is described 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.
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Citations
18 Claims
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1. A position indicator for use with a position detector, the position indicator comprising:
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a housing; a moveable nib extending from the housing and moveable relative to the housing between a retracted position and an extended position; a sensing coil; a flux linkage element which extends at least partially through the coil; wherein said sensing coil and said flux linkage element are mounted for relative movement with the movement of said nib, whereby the inductance of said coil is changed with the movement of said nib; and a magnetically permeable washer whose position is fixed relative to said sensing coil and which is arranged relative to the flux linkage element so that the distance between said washer and said flux linkage element varies with the movement of said nib relative to the housing. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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2. A stylus for use with a position detector, the stylus comprising:
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an elongate housing; a moveable nib mounted at one end of the housing for axial movement relative thereto in a first direction from a retracted position to an extended position and in a second, opposite direction from the extended position to the retracted position; a sensing coil; a first flux linkage element which extends at least partially through the sensing coil; wherein the sensing coil and the first flux linkage element are mounted for relative movement with the movement of said nib, whereby the inductance of said coil is changed with the movement of said nib; and a second flux linkage element whose position is fixed relative to said sensing coil and which is arranged relative to the first flux linkage element so that the distance between said first and second flux linkage elements varies with the movement of said nib relative to the housing; wherein the nib comprises a shank with an enlarged head at one end and a tip at its other end, the head comprising a first axially facing abutment surface facing away from the tip; and wherein movement of the nib relative to the housing in said second direction is limited by said first abutment surface of said head coming into contact against a second abutment surface which is fixed within the housing. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification