US 6,639,585 B1 · Coordinate reading device · patentgrep

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Abstract

When there exist two X coils that generate voltages of the same values during the X coil-scan operation (yes in S314), the CPU 56 discards the position coordinate table 58a that is already stored in the work area, and reloads a new position coordinate table 58a from the ROM 58, and then stores the position coordinate table 58a in association with the pen attribute data that is detected in S310. Then, the CPU 58 calculates a ratio r between the detected value d and the reference value g in S318, and multiplies, with the ratio r, each voltage difference value DIFF in the reloaded position coordinate table 58a in S320. As a result, the position coordinate table 58a is corrected in correspondence with the lowering of the output level of the alternating magnetic field of the pen 60. The CPU then calculates the X coordinate based on the corrected position coordinate table 58a.

Claims37

Dependent claims

A coordinate reading device for reading a coordinate of a position of a target member, which generates an alternating magnetic field, the coordinate reading device comprising:

a coordinate input sheet that has a coordinate input surface defining a coordinate of a target member that generates an alternating magnetic field;
a loop-wire attaching member that is provided below the coordinate input sheet and that has a plurality of loop wires, each loop wire being capable of producing a signal in response to the alternating magnetic field;
a detection unit that detects the signals from the plurality of loop wires;
a coordinate determination unit that determines a coordinate of the position of the target member based on the signal from at least one of the loop wires that is selected for coordinate determination;
and
a correction unit that controls the coordinate determination unit to determine a corrected coordinate of the position of the target member based on a relationship between a predetermined reference value and the value of the signal from at least one of the plurality of loop wires that is selected for coordinate correction;
wherein the plurality of loop wires include one correction loop wire that is located on a predetermined position on the loop-wire attaching member and that is used exclusively for the correction operation, wherein the correction unit compares the value of the signal from the correction loop wire with the predetermined reference value, and controls the coordinate determination unit to determine the corrected coordinate of the position of the target member based on the compared result.

4 more elements

A coordinate reading device for reading a coordinate of a position of a target member, which generates an alternating magnetic field, the coordinate reading device comprising:

a coordinate input sheet that has a coordinate input surface defining a coordinate of a target member that generates an alternating magnetic field;
a loop-wire attaching member that is provided below the coordinate input sheet and that has a plurality of loop wires, each loop wire being capable of producing a signal in response to the alternating magnetic field;
a detection unit that detects the signals from the plurality of loop wires;
a coordinate determination unit that determines a coordinate of the position of the target member based on the signal from at least one of the loop wires that is selected for coordinate determination;
and
a correction unit that controls the coordinate determination unit to determine a corrected coordinate of the position of the target member based on a relationship between a predetermined reference value and the value of the signal from at least one of the plurality of loop wires that is selected for coordinate correction;
wherein the correction unit includes:
a selection unit that selects, for coordinate correction, at least two loop wires among the plurality of loop wires, based on the relationship between the values of the signals from the at least two loop wires;
a ratio calculation unit that calculates a ratio between the value of the signal from the at least one loop wire in the at least two loop wires selected for coordinate correction and the predetermined reference value;
and
a control unit that controls the coordinate determination unit to determine the corrected coordinate of the position of the target member based on the calculated ratio.

8 more elements

A coordinate reading device for reading a coordinate of a position of a target member, which generates an alternating magnetic field, the coordinate reading device comprising:

a coordinate input sheet that has a coordinate input surface defining a coordinate of a target member that generates an alternating magnetic field;
a loop-wire attaching member that is provided below the coordinate input sheet and that has a plurality of loop wires, each loop wire being capable of producing a signal in response to the alternating magnetic field;
a detection unit that detects the signals from the plurality of loop wires;
a coordinate determination unit that determines a coordinate of the position of the target member based on the signal from at least one of the loop wires that is selected for coordinate determination;
and
a correction unit that controls the coordinate determination unit to determine a corrected coordinate of the position of the target member based on a relationship between a predetermined reference value and the value of the signal from at least one of the plurality of loop wires that is selected for coordinate correction;
wherein the correction unit includes:
a ratio calculation unit that calculates a ratio between the value of the signal from the at least one loop wire selected for coordinate correction and the predetermined reference value;
and
a control unit that controls the coordinate determination unit to determine the corrected coordinate of the position of the target member based on the calculated ratio.

7 more elements

A coordinate reading device for reading a coordinate of a position of a target member, which generates an alternating magnetic field, the coordinate reading device comprising:

a coordinate input sheet that has a coordinate input surface defining a coordinate of a target member that generates an alternating magnetic field;
a loop-wire attaching member that is provided below the coordinate input sheet and that has a plurality of loop wires, each loop wire being capable of producing a signal in response to the alternating magnetic field;
a detection unit that detects the signals from the plurality of loop wires;
a coordinate determination unit that determines a coordinate of the position of the target member based on the signal from at least one of the loop wires that is selected for coordinate determination;
and
a correction unit that controls the coordinate determination unit to determine a corrected coordinate of the position of the target member based on a relationship between a predetermined reference value and the value of the signal from at least one of the plurality of loop wires that is selected for coordinate correction;
wherein the coordinate determining unit determines the coordinate of the position of the target member by converting the value of the signal from the at least one loop wire selected for coordinate determination into a coordinate value by a conversion manner,
wherein the detection unit performs a successive series of scanning operations, each series of scanning operation being for scanningly detecting all the plurality of loop wires, and
wherein the correction unit further includes:
an update timing judging unit that judges, after each scanning operation, whether a conversion manner update timing is reached, by judging whether at least two loop wires among all the loop wires produce signals of the values in a predetermined condition;
and
a control unit that updates the conversion manner, at the conversion manner update timing, based on the relationship between the value of the signal from one of the at least two loop wires and the predetermined reference values, and that controls the coordinate determination unit to determine the corrected coordinate of the position of the target member based on the updated conversion manner.

9 more elements

A coordinate reading device for reading a coordinate of a position of a target member, which generates an alternating magnetic field, the coordinate reading device comprising:

a coordinate input sheet that has a coordinate input surface defining a coordinate of a target member that generates an alternating magnetic field;
a loop-wire attaching member that is provided below the coordinate input sheet and that has a plurality of loop wires, each loop wire being capable of producing a signal in response to the alternating magnetic field;
a detection unit that detects the signals from the plurality of loop wires;
a coordinate determination unit that determines a coordinate of the position of the target member based on the signal from at least one of the loop wires that is selected for coordinate determination;
and
a correction unit that controls the coordinate determination unit to determine a corrected coordinate of the position of the target member based on a relationship between a predetermined reference value and the value of the signal from at least one of the plurality of loop wires that is selected for coordinate correction;
wherein the correction unit further includes:
a storage unit that stores the values of the signals detected from the plurality of loop wires until a corrected-coordinate calculation timing;
a timing judging unit that judges whether the corrected-coordinate calculation timing is reached, by judging whether at least two of the plurality of loop wires produce signals with the values in a predetermined condition;
and
a control unit that controls the coordinate determination unit to determine the corrected coordinate of the position of the target member at the corrected-coordinate calculation timing based on the values of the signals stored in the storage unit.

8 more elements

A coordinate reading device for reading a coordinate of a position of a target member, which generates an alternating magnetic field, the coordinate reading device comprising:

a coordinate input sheet that has a coordinate input surface defining a coordinate of a target member that generates an alternating magnetic field;
a loop-wire attaching member that is provided below the coordinate input sheet and that has a plurality of loop wires, each loop wire being capable of producing a signal in response to the alternating magnetic field;
a detection unit that detects the signals from the plurality of loop wires;
a coordinate determination unit that determines a coordinate of the position of the target member based on the signal from at least one of the loop wires that is selected for coordinate determination;
and
a correction unit that controls the coordinate determination unit to determine a corrected coordinate of the position of the target member based on a relationship between a predetermined reference value and the value of the signal from at least one of the plurality of loop wires that is selected for coordinate correction;
wherein the coordinate determining unit determines the coordinate of the position of the target member by converting the value of the signal from the at least one loop wire selected for coordinate determination into a coordinate value by a conversion manner,
wherein the detection unit performs a successive series of scanning operations, each series of scanning operation being for scanningly detecting all the plurality of loop wires, and
wherein the correction unit further includes:
an update timing judging unit that judges, after each scanning operation, whether a conversion manner update timing is reached, by judging whether at least two of the plurality of loop wires produce signals with the values in a predetermined condition, while preventing the time interval between successive conversion manner update timings from being lower than a predetermined time interval;
and
a control unit that updates the conversion manner at the conversion manner update timing and that controls the coordinate determination unit to determine the corrected coordinate of the position of the target member based on the updated conversion manner.

9 more elements

Dependencies are inferred from the claim text.