US 6,784,876 B1 · Coordinate reading device · patentgrep

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Abstract

Y coil Y1 is mounted on the attachment panel 24 so that its long sides Y1f and Y1g follow the front surface 24n, and is bent at a first edge 24a1 onto an edge surface 24a, and is further bent at a second edge 24a onto a rear surface 24b. Even if the pen moves to near an edge portion of the writing surface, the signal generated by long sides Y1f, Y1g will have a little influence from a signal generated from the short side Y1d. When the X coordinate calculated in S1306 is judged to be a coordinate in the X axis edge (S1308:YES), then an X axis edge flag is set in S1310 and a correction coefficient K that corresponds to the distance of the pen from the edge of the Y coil is extracted in S1312 by referring to a correction table. When the Y coils are scanned in S1314, if the X axis edge flag is judged to be set (S1316:YES), then in S1318, all of the values detected for the Y coils in S1314 are multiplied by the correction coefficient K. In S1320, the Y coordinate is calculated based on the corrected detected values. With this configuration, the error caused by influence from the short sides of the Y coils can be corrected so that the Y coordinate can be accurately obtained.

Claims29

Dependent claims

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

a base member having a front surface, a rear surface, a pair of opposite side surfaces, each of which connects the front surface and the rear surface, a pair of opposite edges being defined between the front surface and the pair of side surfaces;
a plurality of loop wires provided on the base member, each loop wire being capable of producing an electric signal in response to an alternating magnetic field generated from a target which is located in front of the front surface, each loop wire having at least one edge portion,
each loop wire being provided on the front surface of the base member, and having a pair of first sides that extend on the front surface in a direction substantially perpendicular to the pair of opposite edges and at least one second side that extends in another direction substantially parallel with the pair of opposite edges to connect the pair of first sides therebetween, the at least one second side defining the at least one edge portion,
each of the at least one second side being located on either one of a corresponding side surface and the rear surface, with the first side being bent at a corresponding edge of the base member in a direction toward the rear surface with a bending amount that separates the second side away from the corresponding edge by a distance that is equal to the bending amount, thereby causing each loop wire to produce a corrected signal when the target is located in the corresponding edge portion of the loop wire;
and
a detection unit that detects levels of the signals generated from the plurality of loop wires, thereby determining a coordinate of the position of the target.

3 more elements

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

a base member having a front surface, a rear surface, a pair of opposite side surfaces, each of which connects the front surface and the rear surface, a pair of opposite edges being defined between the front surface and the pair of side surfaces;
a plurality of loop wires provided on the base member, each loop wire being capable of producing an electric signal in response to an alternating magnetic field generated from a target which is located in front of the front surface, each loop wire having at least one edge portion,
each loop wire being provided on the front surface of the base member, and having a pair of first sides that extend on the front surface and at least one second side connecting the pair of first sides therebetween, the at least one second side defining the at least one edge portion,
the at least one second side being located on either one of a corresponding side surface and the rear surface, with the first side being bent at a corresponding edge of the base member in a direction toward the rear surface with a bending amount that causes each loop wire to produce a corrected signal when the target is located in the at least one edge portion of the loop wire;
and
a detection unit that detects levels of the signals generated from the plurality of loop wires, thereby determining a coordinate of the position of the target,
wherein the at least one edge portion has a pair of edge portions, the at least one second side has a pair of second sides connecting the pair of first sides therebetween, the pair of second sides defining the pair of edge portions, each of the pair of second sides being located on either one of the corresponding side surface and the rear surface, with the first side being bent at the corresponding edge of the base member in a direction toward the rear surface, thereby causing each loop wire to produce a corrected signal when the target is located in either one of the pair of edge portions of the loop wire,
wherein an input plate is provided over the front surface of the base member,
wherein the target has a magnetic-field generating portion generating the alternating magnetic field, the magnetic-field generating portion having a pair of opposite sides, the target being located on the input plate with the pair of opposite sides being arranged along a direction normal to the input plate, and
wherein a distance, defined along the direction normal to the input plate and defined between the second sides of each loop wire and the portion where the loop wire is bent at the edges of the base member, is set longer than a distance between the loop wire and one of the pair of opposite sides of the magnetic-field generating portion that is nearer to the input plate than the other when the target is placed on the input plate.

7 more elements

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

a base member;
a plurality of loop wires provided on the base member, each loop wire being capable of producing an electric signal in response to an alternating magnetic field generated from a target, each loop wire having at least one edge portion;
a detection unit that detects levels of the signals generated from the plurality of loop wires, thereby determining a coordinate of the position of the target;
and
a corrected-edge-coordinate determination unit including a storage unit storing a correction coefficient whose value changes according to a distance of the target from a predetermined position of each loop wire that is defined in each of the at least one edge portion, the corrected-edge-coordinate determination unit determining a corrected coordinate of the target position by using the correction coefficient, thereby determining a corrected coordinate of the position of the target when the target is located in each of the at least one edge portion of a loop wire.

2 more elements

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

a base member;
a plurality of loop wires provided on the base member, each loop wire being capable of producing an electric signal in response to an alternating magnetic field generated from a target, each loop wire having at least one edge portion, the plurality of loop wires including:
a group of X coils having a plurality of X loop coils, each X loop coil being capable of being magnetically coupled to the alternating magnetic field so as to induce an electric voltage, each X loop coil extending in a predetermined Y direction, the plurality of X loop coils being arranged in a predetermined X direction, which is substantially perpendicular to the predetermined Y direction, to be parallel with one another and to be partly overlapped with one another, the plurality of X loop coils including at least one border X loop coil which is located at at least one end portion of the group of X coils in the predetermined X direction;
and
a group of Y coils having a plurality of Y loop coils, each Y loop coil being capable of being magnetically coupled to the alternating magnetic field so as to induce an electric voltage, each Y loop coil extending in the predetermined X direction, the plurality of Y loop coils being arranged in the predetermined Y direction to be parallel with one another and to be partly overlapped with one another, the plurality of Y loop coils including at least one border Y loop coil which is located at least one end portion of the group of Y coils in the predetermined Y direction;
a detection unit that detects levels of the signals generated from the plurality of loop wires, thereby determining a coordinate of the position of the target, the detection unit including:
a coil scanning unit that scanningly detects voltages induced in all the X loop coils in the group of X coils and in all the Y loop coils in the group of Y coils;
and
a coordinate determination unit that determines a set of an X coordinate value and a Y coordinate value, which is indicative of a position of the target, based on values of the voltages induced at the X and Y loop coils,
wherein the group of X coils has the at least one edge portion in the predetermined Y direction and the group of Y coils has the at least one edge portion in the predetermined X direction, the at least one edge portion in the group of X coils being defined within the at least one Y border loop coil but not within at least one first reference Y loop coil that is located adjacent to the Y border loop coil, the at least one edge portion in the group of Y coils being defined within the at least one border X loop coil but not within at least one first reference X loop coil that is located adjacent to the X border loop coil,
wherein a voltage induced in each X loop coil decreases when the target enters each edge portion of the corresponding X coil, and a voltage induced in each Y loop coil decreases when the target enters each edge portion of the corresponding Y coil,
further comprising:
an edge table that stores data of a correction value for correcting the decrease in the voltage induced in each of the X loop coils and the Y loop coils, the edge table storing data of a correction value for X coordinate values and Y coordinate values;
a voltage correction unit that is capable of correcting the voltage values, scanningly detected for the X and Y loop coils, for determining one of the X coordinate value and the Y coordinate value, by a correction value that is retrieved from the edge table based on the other one of the X coordinate value and the Y coordinate value determined by the coordinate determination unit;
an edge judging unit that judges whether either one of the X coordinate value and the Y coordinate value determined by the coordinate determination unit indicates that the target is located within one edge portion of the other one of the X and Y loop coil groups;
and
an edge correction unit that corrects, when the target is judged to be located within one edge portion of the X loop coil group, determines a Y coordinate of the location of the target based on the voltage values corrected by the voltage correction unit and that corrects, when the target is judged to be located within one edge portion of the Y loop coil group, determines a X coordinate of the location of the target based on the voltage values corrected by the voltage correction unit.

14 more elements

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

a base member;
a plurality of loop wires provided on the base member, each loop wire being capable of producing an electric signal in response to an alternating magnetic field generated from a target, each loop wire having at least one edge portion, the plurality of loop wires including:
a group of X coils having a plurality of X loop coils, each X loop coil being capable of being magnetically coupled to the alternating magnetic field so as to induce an electric voltage, each X loop coil extending in a predetermined Y direction, the plurality of X loop coils being arranged in a predetermined X direction, which is substantially perpendicular to the predetermined Y direction, to be parallel with one another and to be partly overlapped with one another, the plurality of X loop coils including at least one border X loop coil which is located at at least one end portion of the group of X coils in the predetermined X direction;
and
a group of Y coils having a plurality of Y loop coils, each Y loop coil being capable of being magnetically coupled to the alternating magnetic field so as to induce an electric voltage, each Y loop coil extending in the predetermined X direction, the plurality of Y loop coils being arranged in the predetermined Y direction to be parallel with one another and to be partly overlapped with one another, the plurality of Y loop coils including at least one border Y loop coil which is located at at least one end portion of the group of Y coils in the predetermined Y direction;
a detection unit that detects levels of the signals generated from the plurality of loop wires, thereby determining a coordinate of the position of the target, the detection unit including:
a coil scanning unit that scanningly detects voltages induced in all the X loop coils in the group of X coils and in all the Y loop coils in the group of Y coils;
and
a coordinate determination unit that determines a set of an X coordinate value and a Y coordinate value, which is indicative of a position of the target, based on values of the voltages induced at the X and Y loop coils,
wherein the coordinate determination unit includes:
a maximum voltage coil detection unit that detects a maximum voltage X loop coil that induces a maximum voltage among all the X loop coils and that detects a maximum voltage Y loop coil that induces a maximum voltage among all the Y loop coils;
and
a second maximum voltage coil detection unit that detects a second maximum voltage X loop coil that induces a second maximum voltage among all the X loop coils and that detects a second maximum voltage Y loop coil that induces a second maximum voltage among all the Y loop coils;
wherein the coordinate determination unit determines a set of an X coordinate value and a Y coordinate value, which is indicative of a position of the target, based on the values of the maximum voltage induced at the maximum voltage X loop coil and of the second maximum voltage induced at the second maximum voltage X loop coil and based on the values of the maximum voltage induced at the maximum voltage Y loop coil and of the second maximum voltage induced at the second maximum voltage Y loop coil, and
wherein the plurality of X loop coils further includes at least one first reference X loop coil and at least one second reference X loop coil, the at least one first reference X loop coil being located next to the X border loop coil, the at least one second reference X loop coil being located next to the at least one first reference X loop coil,
wherein the plurality of Y loop coils further includes at least one first reference Y loop coil and at least one second reference Y loop coil, the at least one first reference Y loop coil being located next to the Y border loop coil, the at least one second reference Y loop coil being located next to the at least one first reference Y loop coil,
wherein the coordinate determination unit includes:
a border judging unit that judges whether or not the target is located in one of border portions along the X and Y directions, the border portion along the X direction being defined within the at least one border X loop coil but not within the at least one first reference X loop coil, the border portion along the Y direction being defined within the at least one Y border loop coil but not within the at least one first reference Y loop coil,
the border judging unit including:
a first comparison unit that performs a first X judgment for the maximum voltage X loop coil when the maximum voltage X loop coil is one of the at least one border X loop coil, the first X judgment being for comparing, with a predetermined reference value, a value of a voltage induced at a second reference X loop coil for the maximum voltage X loop coil, to thereby determine that the target is located in a corresponding border portion along the X direction when the value of the voltage at the second reference X loop coil is lower than the predetermined reference value,
the first comparison unit performing a first Y judgment for the maximum voltage Y loop coil when the maximum voltage Y loop coil is one of the at least one border Y loop coil, the first Y judgment being for comparing, with the predetermined reference value, a value of a voltage induced at a second reference Y loop coil for the maximum voltage Y loop coil, to thereby determine that the target is located in a corresponding border portion along the Y direction when the value of the voltage at the second reference Y loop coil is lower than the predetermined reference value;
an adding unit that performs an X adding operation when the target is judged to be located in one border portion along the X direction, the X adding operation being for calculating a sum of a value of the maximum voltage induced at the maximum voltage X loop coil and a value of the voltage induced at the second reference X loop coil, the adding unit performing a Y adding operation when the target is judged to be located in one border portion along the Y direction, the Y adding operation being for calculating a sum of a value of the maximum voltage induced at the maximum voltage Y loop coil and a value of the voltage induced at the second reference Y loop coil;
a border table storing data of a plurality of coordinate values in correspondence with a plurality of possible voltage sum values;
and
a border coordinate determination unit that performs an X coordinate determining operation to determine an X coordinate of the target when the target is located in one border portion along the X direction, the X coordinate determining operation being for referring to the border table based on a value of the sum obtained by the X adding operation, thereby reading a value of an X coordinate that is stored in the border table in correspondence with the value of the sum obtained by the X adding operation, the border coordinate determination unit performing a Y coordinate determining operation to determine a Y coordinate of the target when the target is located in one border portion along the Y direction, the Y coordinate determining operation being for referring to the border table based on a value of the sum obtained by the Y adding operation, thereby reading a value of a Y coordinate that is stored in the border table in correspondence with the value of the sum obtained by the Y adding operation.

22 more elements

Dependencies are inferred from the claim text.