JP2002297303A - Coordinate reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new coordinate reader capable of obtaining also coordinates in a direction vertical to a writing surface by constitution different from that of conventional coordinate reader. SOLUTION: In the coordinate reader, a grid part 17 has a structure of laminating a first group of coils 43 consisting of a plurality of coils parallel to a (y)-axis arrayed with a prescribed pitch in the direction of (y)-axis, a first medium layer 45, a second group of coils 47 consisting of a plurality of coils parallel to an (x)-axis arrayed with a prescribed pitch in the direction of (y)-axis, a second medium layer 49, and a shield plate 51 consisting of an aluminum plate. When the first group of coils 43 and the second group of coils 47 are positioned separated from each other via the first medium layer 45, the output values of signals are different between the first group of coils 43 and the second group of coils 47 because of the difference between distances from the respective groups of coils to a pen. Thus, (z)-coordinates can be obtained based on the difference of these output values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a coordinate reading device.

[0002]

2. Description of the Related Art Conventionally, a coordinate reading apparatus of this type has a structure in which a plurality of loop coils are disposed inside a writing surface, and points on the writing surface are pointed by a pen having an oscillation coil. Utilizing the fact that the signal is guided to the loop coil near the point pointed at the time, the coordinates of the point pointed can be calculated from the arrangement position of the loop coil from which the signal was guided and the output value of the signal. What is configured to calculate is known.

In a coordinate reading device having such a structure, a first loop coil group arranged in parallel with the y-axis at a predetermined interval in the x-axis direction, and a first loop coil group in a predetermined direction in the y-axis direction parallel to the x-axis. Are arranged so as to form a lattice, and the x-coordinate of the point pointed by the first loop coil group is calculated. , The y coordinate of the point pointed is calculated. In general, the first loop coil group and the second loop coil group are arranged so as to be closely overlapped with no gap therebetween, and due to a difference in the distance from the pen to each loop coil group, the first loop coil group and the second loop coil group are arranged. This prevents a difference in sensitivity between the second loop coil group and the second loop coil group.

[0004]

By the way, conventionally,
In this type of coordinate reading apparatus, coordinates (z coordinates) in a direction perpendicular to the writing surface are also obtained. For example, when character recognition of handwritten characters is performed, the pen in the z-axis direction is used. A usage method has been conceived in which a place where the amount of separation is large is recognized as a break between characters.

As a method of obtaining the z coordinate, for example, there is a method of calculating the z coordinate from the amplitude by utilizing the fact that the amplitude of a signal induced when the pen is released is reduced. However, since the amplitude of the induced signal is reduced even when the output of the pen is reduced due to, for example, a decrease in the power supply voltage of the pen, there is a disadvantage that the z coordinate cannot always be obtained accurately. Was.

A passive coordinate reading apparatus having an exciting coil utilizes the fact that the inductance of the pen-side coil changes depending on the distance from the shield plate, and the z coordinate is calculated from the phase change of the induced signal due to this. Although some were found, a phase detection circuit was needed to find the z-coordinate, and there was a problem that the circuit configuration became complicated accordingly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a novel structure which can obtain coordinates in a direction perpendicular to a writing surface by a configuration different from that of the conventional product as described above. A coordinate reading device.

[0008]

Means for Solving the Problems and Effects of the Invention In order to achieve the above object, a coordinate reading apparatus according to the present invention comprises
A first coil group in which a plurality of coils parallel to the axis are arranged at a predetermined pitch in the x-axis direction on a first plane perpendicular to the z-axis, and a plurality of coils parallel to the x-axis in the z-axis A second coil group arranged at a predetermined pitch in the y-axis direction on a second vertical plane and a point at which coordinates are to be read are designated by coordinate designating means for designating a point at which coordinates are to be read. A first signal detecting means for detecting a signal guided to a coil belonging to the first coil group; and a second point for reading a coordinate by the coordinate indicating means. A second signal detecting means for detecting a signal induced by a coil belonging to the first group, and an arrangement position of each coil belonging to the first coil group based on a signal detected by the first signal detecting means. One signal detection means detected The x-coordinate specifying means for obtaining the x-coordinate of the point designated by the coordinate designating means from the relationship with the output value of the signal guided to each of the coils, and a signal detected by the second signal detecting means. In accordance with the relationship between the arrangement position of each coil belonging to the second coil group and the output value of a signal guided to each coil detected by the second signal detection means, the position is designated by the coordinate designation means. A y-coordinate specifying unit that obtains a y-coordinate of a point; an output value of a signal detected by the first signal detection unit; and an output value of a signal detected by the second signal detection unit. Z-coordinate specifying means for obtaining the z-coordinate of the designated point.

According to the coordinate reader having the above-described configuration, when the point at which the coordinates are to be read is designated by the coordinate designating means, the first signal detecting means is guided to the coils belonging to the first coil group. While detecting the signal, the second signal detecting means detects a signal induced in the coil belonging to the second coil group.

Here, the first coil group is arranged on a first plane, while the second coil group is arranged on a second plane, and the first coil group and the second coil group are arranged. Are not arranged exactly like the conventional products. Therefore, the distance from the coordinate indicating means differs between the first coil group and the second coil group, and one coil group (for example, the first coil group) closer to the coordinate indicating means and the other coil farther from the coordinate indicating means. In the group (for example, the second coil group), a proportional relationship is not established with the output change when the coordinate indicating means is gradually moved away from the writing surface, and the ratio between the two is determined by the distance from the coordinate indicating means to the writing surface ( That is, the value corresponds to the z coordinate).

Therefore, the z-coordinate specifying means determines the point designated by the coordinate designating means based on the output value of the signal detected by the first signal detecting means and the output value of the signal detected by the second signal detecting means. Is determined. More specifically, for example, the x-coordinate and y of the point pointed by the coordinate pointing means
If only the z-coordinate is changed without changing the coordinates, and the output ratio between the first coil group and the second coil group is sampled and tabulated for some z-coordinates in advance, this table ( With reference to the sampling value), the z-coordinate specifying means instructs the coordinate instructing means based on the output value of the signal detected by the first signal detecting means and the output value of the signal detected by the second signal detecting means. The z coordinate of the point obtained can be obtained. Further, if an approximate expression indicating the correlation between the output ratio of the first coil group and the second coil group and the z coordinate is obtained from the data sampled as described above, the approximate expression is used to calculate z The coordinate specifying means may determine the z coordinate of the point designated by the coordinate designating means based on the output value of the signal detected by the first signal detecting means and the output value of the signal detected by the second signal detecting means. it can.

The x-coordinate specifying means and the y-coordinate specifying means are provided for the x-coordinate and y-coordinate of the point designated by the coordinate designating means.
Coordinates are determined, and these means may be the same as known means conventionally used in this type of coordinate reading apparatus. More specifically, the x-coordinate specifying means specifies the coil having the largest output based on the signal detected by the first signal detecting means, and determines the arrangement position of the specified coil and some coils (for example, It is sufficient if the x-coordinate is calculated based on the output value of the signal induced by the specified coil and the coils on both sides thereof. The y-coordinate specifying means specifies the coil having the largest output based on the signal detected by the second signal detecting means, and determines the arrangement position of the specified coil and some coils (for example, the specified coil). The y-coordinate may be calculated based on the output value of the signal induced by the coil and the coils on both sides thereof.

According to the coordinate reading apparatus thus constructed, unlike the conventional product, the first coil group and the second coil group output signals due to the difference in the distance from the coordinate indicating means. The z-coordinates can be obtained on the basis of the difference between the output values, since they are arranged at positions separated from each other to such an extent that a difference appears.

The coordinate reading device described above may be further configured as follows. First, the z-coordinate specifying means determines a ratio between a maximum output value Xmax estimated from the signal detected by the first signal detection means and a maximum output value Ymax estimated from the signal detected by the second signal detection means. The z coordinate of the point designated by the coordinate designating means may be obtained based on

Here, the maximum output value Xmax is defined as the signal output from the coil when the x-coordinate of the point pointed by the coordinate designating unit is exactly the center of the coil belonging to the first coil group. Output value. The maximum output value Ymax is an output value of a signal output from the coil when the y coordinate of the point pointed by the coordinate designating unit is exactly the center of the coil belonging to the second coil group. .

When the user points at a point which is coordinate indicating means,
If the x-coordinate or y-coordinate of the point is shifted from the center of the coil, the output value of the signal actually output from the coil becomes weaker than the maximum output value Xmax, but the x-coordinate or y-coordinate of the coil is It is possible to measure in advance how much the center is shifted and the signal output from the coil is weakened. Therefore, if the data measured in advance is tabulated or an approximate expression indicating the correlation between the deviation of the x coordinate or the y coordinate and the output value is obtained from the measured data in advance, the table or the approximate expression is used. Thus, the maximum output value Xmax can be estimated from the signal detected by the first signal detection means, and the maximum output value Ymax can be estimated from the signal detected by the second signal detection means.

The maximum output value Xmax and the maximum output value Ymax estimated in this manner are obtained when the x coordinate or the y coordinate is moved to the center of the coil without changing the z coordinate of the point pointed by the coordinate designating means. Corresponds to the output value of the signal estimated to be output from the coil. The z-coordinate specifying means uses the maximum output value Xmax and the maximum output value Ymax estimated as described above,
The z coordinate of the point specified by the coordinate specifying means is obtained.

As described above, if the output value of the signal detected by the first signal detection means or the second signal detection means is not directly used, but is once converted into the maximum output value Xmax or Ymax, and the ratio is obtained, It is not necessary to consider that the x-coordinate or the y-coordinate of the point pointed by the coordinate designating means deviates from the center of the coil. Specifically, as data necessary for converting the ratio between the maximum output value Xmax and the maximum output value Ymax into the z coordinate, the x coordinate or the y coordinate of the point pointed by the coordinate designating means is measured from the center of the coil. It is only necessary to have data for the case where there is no shift, and x
It is not necessary to have any data for the case where the coordinates or y-coordinates deviate somewhat from the center of the coil.

Therefore, the first signal detecting means or the second signal detecting means
The amount of data required to convert the output value of the signal detected by the signal detection means into the z coordinate can be reduced. Further, since the maximum output value Xmax and the maximum output value Ymax are the largest values among the output values from the coil, the influence of the measurement error can be reduced, and the x coordinate or the y coordinate is slightly shifted from the center of the coil. Z is smaller than the case where the z coordinate is obtained based on the sampling data of the case.
The measurement accuracy of coordinates can be increased.

When the z coordinate is obtained based on the ratio between the maximum output values Xmax and Ymax, even if the output of the coordinate indicating means decreases due to a decrease in the power supply voltage on the coordinate indicating means side, etc.
Since the outputs of the first coil group and the second coil group decrease at the same ratio, the ratio of the maximum output values Xmax and Ymax is not affected, and an appropriate z coordinate is set regardless of the output level of the coordinate indicating means. You can ask. Therefore, a decrease in the output of the coordinate indicating means is not erroneously recognized as being separated from the coil by the coordinate indicating means.

Next, estimation is made from the signal detected by the first signal detecting means when the z coordinate of the point designated by the coordinate designating means is closest to the first coil group and the second coil group. The maximum output value Xmax to be calculated and the maximum output value Ymax estimated from the signal detected by the second signal detection means, so that Ymax / Xmax or Xmax / Ymax is 0.5 or more and 0.9 or less. It is preferable that the first coil group on the first plane and the second coil group on the second plane are arranged via a predetermined gap.

Here, Ymax / Xmax or Xmax
x / Ymax changes when the distance between the first coil group and the second coil group changes, but when Ymax / Xmax or Xmax / Ymax exceeds 0.9, the z coordinate changes relatively greatly. However, since there is no large change in Ymax / Xmax, the resolution in the z-axis direction tends to be too low. On the other hand, when Ymax / Xmax or Xmax / Ymax is less than 0.5, the difference between the resolution in the x-axis direction and the resolution in the y-axis direction tends to be too large. Although the resolution is high, the resolution is relatively low in the y-axis direction. That is, it is disadvantageous in the detection limit of the coordinate value.

On the other hand, Ymax / Xmax or Xmax
When max / Ymax is 0.5 or more and 0.9 or less, the resolution in the z-axis direction does not become excessively low, and the difference between the resolution in the x-axis direction and the resolution in the y-axis direction is also small. Since it does not become extremely large, xyz
The resolution in each direction can be ensured in a well-balanced manner.

Further, from the maximum output value of the signal induced by each coil belonging to the first coil group detected by the first signal detecting means and the x coordinate obtained by the x coordinate specifying means, First maximum output value estimating means for estimating a maximum output value Xmax; a maximum output value of a signal induced by each coil belonging to the second coil group detected by the second signal detecting means; A second maximum output value estimating means for estimating the maximum output value Ymax from the y coordinate obtained by the means.

With such a configuration, the maximum output value Xmax estimated by the first maximum output value estimating means and the second maximum output value Xmax
Using the maximum output value Ymax estimated by the maximum output value estimating means, the z coordinate specifying means can obtain the z coordinate.

[0026]

Next, an embodiment of the present invention will be described with reference to an example. A coordinate reading device to be described as an embodiment of the present invention is incorporated in a notebook 1 as shown in FIG. 1, and the notebook 1 uses a dedicated pen 3 to hand-write characters and pictures on a sheet 5. In this case, a function of reading a locus drawn by the pen 3 and converting the locus into data is provided.
The notebook 1 also has a function of recording / reproducing sound, and is provided with a microphone 7, a speaker 9, a switch group 11 for various operations, and the like. Further, inside the notebook 1, as shown in FIG. 2, a CPU 13, a memory 15, a grid unit 17, a selector unit 19, a first amplifier 21, a detector 23, an A / D converter 25, an FSK demodulation circuit 26, A second amplifier 27, a codec 29, a third amplifier 31, and the like are provided.

Among these components, the pen 3 (coordinate indicating means in the present invention) includes an oscillating coil and an oscillating coil, in addition to a writing mechanism for actually writing characters and pictures on the paper 5 with ink. It incorporates a circuit board on which an oscillation circuit for generating an alternating magnetic field is mounted, a battery for supplying power to the circuit board, a pen pressure switch that is turned on when a predetermined pen pressure is applied to the pen tip, and the like. On the circuit board, the oscillation frequency of the carrier is set to FSK (Frequency) by two kinds of modulation frequencies corresponding to ON / OFF of the pen pressure switch.
An oscillation circuit for performing Shift Keying modulation is incorporated. When the pen pressure switch is turned on, the oscillation circuit operates to generate an alternating magnetic field from the oscillation coil, and thereafter, for a certain period of time (for example, 10 seconds) after the pen pressure switch is turned off. )
The operation of the oscillating circuit is stopped when elapses. Note that an FSK demodulation circuit 26 is provided on the notebook 1 side, and based on a detection value of the FSK demodulation circuit 26,
It is possible to determine whether or not pen pressure is applied to the pen tip.

The CPU 13 is a well-known CPU that executes various controls and data calculations according to programs stored in the memory 15. The CPU 13 executes various processes for realizing a function as a coordinate reading device. Memory 15
Is a device that stores various programs and data. Programs necessary for executing a coordinate reading process described later are stored in the memory 15.

The grid portion 17 is a portion for detecting a trajectory drawn by the pen 3, and as shown in FIG. 3, a surface layer 41 forming a writing surface perpendicular to the z-axis and a plurality of coils parallel to the y-axis. a first coil group 43 arranged at a predetermined pitch in the x-axis direction on a first plane perpendicular to the z-axis;
An intermediate layer 45; a second coil group 47 in which a plurality of coils parallel to the x-axis are arranged at a predetermined pitch in the y-axis direction on a second plane perpendicular to the z-axis; When,
It has a structure in which a shield plate 51 made of an aluminum plate is laminated. The first coil group 43 and the second coil group 47 are each formed by a loop coil known in this type of coordinate reading device. Although the number of loop coils depicted in FIG. 3 is smaller than the actual number to avoid complicating the figure, actually, a larger number of loop coils are provided. The shield plate 51 is provided in order to prevent the sensitivity of the grid portion 17 from changing due to the effect of the material of the object coming to the back side of the grid portion 17. In the present embodiment, the distance dx from the writing surface to the first coil group 43 is 0.2 mm, the distance dy from the writing surface to the second coil group 47 is 1.4 mm, and the distance dy from the writing surface to the shield plate 51. Is 2.8 mm.

The selector section 19 (the first signal detecting means and the second signal detecting means in the present invention) controls the loop coils (the first coil group 43 and the first coil group 43) provided in the grid section 17 in accordance with a control signal from the CPU 13. Second coil group 4
7) is a circuit for scanning and sequentially outputting signals guided to each coil as the pen 3 approaches. The output from the selector unit 19 is input to the CPU 13 via the first amplifier 21, the detector 23, and the A / D converter 25, and the CPU 13 calculates the coordinates of the point pointed by the pen,
Processing for determining ON / OFF of the pen pressure switch is performed.

The codec 29 is a circuit having a function of converting voice, which is analog data, into a digital code that can be stored in the memory 15, and a function of converting the digital code stored in the memory 15 into analog data that becomes voice. is there. The audio signal input from the microphone 7 is input to the CPU 13 through the second amplifier 27 and the codec 29,
Stored in the memory 15. The audio data stored in the memory 15 is read by the CPU 13, and is output as audio from the speaker 9 via the codec 29 and the third amplifier 31.

The grid portion 17 has an important feature in that the first intermediate layer 45 is interposed between the first coil group 43 and the second coil group 47. This first
The intermediate layer 45 includes a first coil group 43 and a second coil group 4.
The height position (z coordinate) of the pen 3 can be detected by providing such a gap. Hereinafter, the mechanism of this height position detection will be described in detail.

FIG. 4 shows various values for the distance dx from the writing surface (front side of the surface layer 41) to the first coil group 43 and the distance dy from the writing surface (front side of the surface layer 41) to the second coil group 47. Then, the thickness dy-dx of the first intermediate layer 45 is set to 0.2 to
FIG. 9 is a graph showing the relationship between the height position (z coordinate) of the pen 3 and the output characteristics from each coil for seven types of grid sections 17 having different values in increments of 0.2 mm up to 1.4 mm.

In this measurement, the x-coordinate of the point pointed by the pen 3 is set to one coil XC selected from the first coil group 43 with the pen 3 in contact with the writing surface.
Is fixed at the position where the output from the
Is fixed at a position where the output from one coil YC selected from the second coil group 47 is maximized with the pen 3 in contact with the writing surface. In this state, only the height (z coordinate) of the pen 3 from the writing surface is changed at a pitch of 2 mm from 0 mm to 8 mm, and the output value Xmax from the coil XC (hereinafter referred to as the maximum output value X)
max), and the output value Ymax from the coil YC
(Hereinafter also referred to as a maximum output value Ymax). The horizontal axis represents the height of the pen 3 from the writing surface, and the vertical axis represents the ratio Y between the maximum output value Xmax and the maximum output value Ymax.
FIG. 4 is a graph obtained by taking max / Xmax.

As is clear from the graph of FIG. 4, the ratio Ymax between the maximum output value Xmax and the maximum output value Ymax is obtained.
Since / Xmax tends to decrease as the height position of the pen 3 from the writing surface increases, if the data having such a tendency is sampled in advance, the maximum output value Xmax and the maximum output value Ymax can be reduced. By measuring or estimating, the height position of the pen 3 from the writing surface can be calculated.

Incidentally, the conventional product is the first coil group 43
And the second coil group 47 are arranged so as to overlap each other with no gap so that they can be regarded as being substantially on the same plane.
Ratio Ymax between maximum output value Xmax and maximum output value Ymax
x / Xmax shows a constant value even if the height position of the pen 3 from the writing surface changes. In the graph of FIG. 4, the inclination of the graph becomes 0 (horizontal), and thus the maximum output is obtained. Value X
Even if the maximum value and the maximum output value Ymax are measured, the height position of the pen 3 from the writing surface cannot be calculated.

The smaller the thickness of the first intermediate layer 45, the closer to the structure similar to that of the conventional product, and the inclination of the graph tends to be small.
It becomes difficult to calculate the height position of the pen 3 from the writing surface. The extent to which the thickness of the first intermediate layer 45 should be increased cannot be unequivocally determined because it depends on the accuracy of the output value of the coil and the like, but from the graph of FIG. The maximum output value Xma when the height from
It is considered that if the thickness of the first intermediate layer 45 is increased until the ratio Ymax / Xmax of x to the maximum output value Ymax becomes 0.9 or less, the inclination of the graph necessary for height detection can be obtained. .

However, if the thickness of the first intermediate layer 45 is excessively large, the absolute value of the maximum output value Ymax becomes too small, and the resolution of the y coordinate is lower than the resolution of the x coordinate. In order to ensure the resolution in each of the xyz directions in a well-balanced manner, when the height of the pen 3 from the writing surface is 0, the ratio Ymax / Xmax between the maximum output value Xmax and the maximum output value Ymax becomes 0.5 or more. The degree is the first
It is desirable to secure the thickness of the intermediate layer 45.

Next, the coordinate reading process executed by the CPU 13 will be described with reference to FIG. The coordinate reading process is periodically (for example, 1
(Every 00 ms). When the coordinate reading process is started, the CPU 13 selects one coil belonging to the first coil group 43 (hereinafter also referred to as X coil) and one coil belonging to the second coil group 47 (hereinafter also referred to as Y coil). Selector unit 19 selects a coil selection signal for selecting
To perform scanning of the X coil and the Y coil (S102).

At this time, the pen 3
When an alternating magnetic field is generated from the oscillating coil, a signal generated by magnetic coupling with the X coil or the Y coil is
The signal is amplified by the first amplifier 21, amplitude-detected by the detector 23, converted to a digital signal corresponding to the amplitude (ie, voltage value) by the A / D converter 25, and
13 is input. Based on this input value, the CPU 13
Checks whether the pen 3 has been detected (S10).
4). Here, if the pen 3 is not detected (S104: N
o) Since the writing with the pen 3 has not been performed, this processing ends.

On the other hand, when the pen 3 is detected (S104:
Yes), the voltage value indicated by the digital signal input by scanning the X coil and the Y coil is stored in the memory 15 in association with the coil number (S10).
6). Then, for the X coil, the maximum voltage value is searched from among the voltage values stored in the memory 15, and the coil number XCn of the X coil that has generated the voltage value is stored in the memory 15 (S108). Calculate coordinates (S11
0).

More specifically, the processing of S110 is the processing shown in FIG. First, the CPU 13 determines the coil number XC
The voltage value En generated by the n X coils is extracted (S20).
2) Extract the voltage value En-1 generated by the X coil of the coil number XCn-1 adjacent to the X coil of the coil number XCn (S204), and locate the voltage value En-1 next to the other of the X coil of the coil number XCn. The voltage value En + 1 generated by the coil having the coil number XCn + 1 is extracted (S206).

The extracted voltage values En, En−1,
En + 1 is, for example, a value having a relationship as shown in FIG. In the graph of FIG. 7, the horizontal axis is the x coordinate, and the vertical axis is the voltage value. Coil numbers XCn, XCn-1, XCn +
Each X coil outputs a voltage value as shown in FIG. 7 according to the x coordinate of the point pointed by the pen 3. In FIG. 7, when the x coordinate of the point pointed by the pen 3 is x, the X coil of the coil number XCn generates a voltage value En, and the X coil of the coil number XCn-1 generates a voltage value En-1.
Is generated, and the coil having the coil number XCn + 1 has the voltage value En
Since +1 is generated, in the processing of S202 to S206,
Each of these values will be extracted.

Subsequently, the CPU 13 determines the voltage values En-1 and E
n + 1 (S208), and if the voltage value En-1 is larger (S208: Yes), -1 is set to the variable SIDE.
Is set (S210), and the voltage value difference E1 = (En) −
(En-1) is calculated (S212), and the voltage value difference E2 =
(En)-(En + 1) is calculated (S214). If the voltage value En-1 is smaller (S208: N
o), the variable SIDE is set to 1 (S216), and the voltage value difference E1 = (En)-(En + 1) is calculated (S21).
8) The voltage value difference E2 = (En) − (En−1) is calculated (S220).

When the values of SIDE, E1, and E2 are obtained in this manner, the key value RX for obtaining the x coordinate is 1000 *
E1 / E2 is calculated (S222). And the key value R
A value closest to X is searched in the position coordinate table shown in FIG. 8, and an offset value OF corresponding to the searched value is searched.
FSET is obtained (S224).

Then, the CPU 13 determines the coil number XCn
X coordinates m of the center of the coil of S210 to S216
The x coordinate x = m + OFFSET * SI of the point pointed by the pen 3 on the basis of the variable SIDE set in the process of step S224 and the offset value OFFSET obtained in the process of step S224.
The DE is calculated (S226). Note that, in the present embodiment, the X coordinate m of the center of the coil having the coil number XCn is set such that a relationship of m = XCn × 70 is established between the coil number XCn and the offset value OFFSET.
According to the position coordinate table shown in FIG.
It is configured to take a value in a range of ET ≦ 35.

When the processing of S202 to S226 is completed, the processing of S110 shown in FIG. 5 is completed, and the CPU 13 subsequently executes the processing of S112 to store the Y coil in the memory 15. The maximum voltage value is searched from the voltage values present, the coil number YCn of the Y coil that generated the voltage value is stored in the memory 15 (S112), and the y coordinate is calculated (S114). The process of S114 is the same as the process of calculating the x-coordinate described above (S110 = S202 to S226), except for the specific difference in numerical data. Detailed description of the processing corresponding to the processing of S226 is omitted.

Subsequently, the CPU 13 executes the FSK demodulation circuit 2
6 is read (S116) and the pen 3 is turned on or off.
It is checked whether it is F (S118). As described above, the pen 3 incorporates an oscillation circuit that FSK modulates the oscillation frequency of the carrier with two modulation frequencies corresponding to ON / OFF of the pen pressure switch. By reading the value of the demodulation circuit 26, the pen 3 is turned on (in a state where the pen pressure is applied) or OF.
F (a state in which pen pressure is not applied) can be determined.

Here, when the pen 3 is ON (S118:
Yes), 0 is set to the z coordinate (S120). If the pen 3 is OFF (S118: No), the z coordinate is detected based on the output values of the X coil and the Y coil (S122). The processing of S122 is described in more detail in FIG.
The processing shown in FIG.

First, the CPU 13 estimates the maximum output value Xmax of the X coil based on the voltage value En generated by the X coil having the coil number XCn (S302). In the present embodiment, the conversion coefficient table shown in FIG. 10A is searched using the offset value OFFSET obtained in the process of S224 as a key value, and the offset value OFFS
A conversion coefficient α corresponding to ET is obtained, and the maximum output value Xmax of the X coil is obtained by multiplying the conversion coefficient α by the voltage value En. The maximum output value Xmax of the X coil thus obtained corresponds to a voltage value estimated to be generated by the X coil of the coil number XCn when the offset value OFFSET = 0.

Subsequently, the CPU 13 determines the coil number YCn
Of the maximum output value Ymax of the Y coil (S30)
4). The specific processing procedure is the same as the processing in S302. The conversion coefficient table shown in FIG. 10B is searched using the offset value for the y coordinate as a key value, and the conversion coefficient β corresponding to the offset value is determined. Calculated, and this conversion coefficient β
Is multiplied by the voltage value generated by the Y coil of the coil number YCn to obtain the maximum output value Ymax of the Y coil. The maximum output value Yma of the Y coil thus obtained
x is the coil number YC when the offset value is 0
This corresponds to a voltage value estimated to be generated by n Y coils.

Subsequently, the ratio Ymax / Xmax between the maximum output value Xmax and the maximum output value Ymax is determined (S30).
6). Then, a value closest to the key value Ymax / Xmax is searched in the z-coordinate table, and a z-coordinate corresponding to the searched value is obtained (S308). The z-coordinate table is one of the graphs illustrated in FIG. 4 (dx = 0.
2, a graph of dy = 1.4) is tabulated, and the ratio Y obtained by the processing of S306 is tabulated.
Once max / Xmax is determined, the z-coordinate corresponding to that value can be specified.

When the processing of S302 to S308 is completed, the processing of S122 shown in FIG. 5 is completed. When the processing of S120 or the processing of S122 is completed, the CPU 13 determines the value x obtained in the processing of S110.
The coordinates, the y coordinate obtained in the processing of S114, and the z coordinate obtained in the processing of S120 or S122 are stored in the memory 15 in a form that can be used in another process (S1).
24). Then, by returning to the process of S102,
This process is repeated, and the trajectory drawn by the pen 3 is sequentially stored by the process of S124.

Incidentally, the trajectory of the pen 3 read in this way is referred to by other processes which are processed in parallel, and is converted into graphic data as it is, stored in the memory 15 as an image, Although the data is converted into text data and stored in a memory by the process of converting it into a code, these processes are executed by the CPU 13 according to an application program using the coordinate reading function, and are not the coordinate reading function itself. Then, the description is omitted.

The above S110 (S202 to S22)
The CPU 13 executing the process 6) corresponds to the x-coordinate specifying means according to the present invention. Further, the CPU 13 that executes the processing of S114 corresponds to the y-coordinate specifying means in the present invention. In addition, S120 or S122 (S302)
The CPU 13 that executes the processing of steps S308 to S308 corresponds to the z-coordinate specifying unit according to the present invention. Further, the above S302
The CPU 13 executing the processing in (1) corresponds to the first maximum output value estimating means in the present invention, and the CPU 13 executing the processing in S304 corresponds to the second maximum output value estimating means in the present invention.

As described above, according to this notebook 1, unlike the conventional product, the first coil group 43 and the second coil group 47 are different from each other in the distance between the pen 3 and the signal of the signal. Since they are arranged at positions apart from each other to such an extent that the output value differs, not only the x-coordinate and the y-coordinate of the point pointed by the pen 3 but also the z-coordinate based on this difference in the output value can be obtained. You can ask.

In determining the z coordinate, the maximum output values Xmax and Ymax are estimated from the output value of the coil without directly using the output value of the coil, and the z coordinate is determined from the estimated value. For each combination pattern (70 × 70) of the x coordinate (70 points in this embodiment) detected by one X coil and the y coordinate (70 points in this embodiment) detected by one Y coil, z Even if a table for calculating the coordinates is not prepared, the offset for the x coordinate detected by one X coil is 0, and the y coordinate detected by one Y coil is used as the table for calculating the z coordinate. Need only be prepared in a table corresponding to the case where the offset is 0. Therefore, effective use of the memory resources can be achieved, and the capacity of the memory 15 does not need to be excessively large.

Further, the data for obtaining the z coordinate from the ratio Ymax / Xmax of the maximum output values Xmax and Ymax is such that the ratio Ymax / Xmax is 0.5 or more and 0.9 or less when the z coordinate is 0. As described above, since the gap between the first coil group 43 and the second coil group 47 is adjusted, the resolution in the z-axis direction is not excessively low as in the case where this value exceeds 0.9. Also, unlike the case where this value is less than 0.5, the difference between the resolution in the x-axis direction and the resolution in the y-axis direction does not become extremely large. Can be secured well.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described specific embodiment.
The present invention can be implemented in various other modes. For example, in the above-described embodiment, an example in which the coordinate reading device of the present invention is incorporated in a notebook has been described. However, the present invention is not limited to this, and various known handwriting input devices, pen touch input devices, etc. The configuration of the present invention can be adopted.

In the above embodiment, in the processing of S302 and S304, in estimating the maximum output value, the coefficients corresponding to all the offset values of the x coordinate or the y coordinate are obtained in advance, and the coefficients are measured. Although the estimated output value is multiplied, the method of estimating the maximum output value may be another method. For example, using three output values, including at least the measured maximum output value,
A function of a curve approximating the correlation between the offset value and the output value may be determined in advance, and the maximum output value may be estimated by applying the three output values to the function.

[Brief description of the drawings]

FIG. 1 is a perspective view of a notebook in which a coordinate reading device is incorporated.

FIG. 2 is a block diagram showing an internal structure of the notebook.

FIG. 3 is an exploded perspective view showing a structure of a grid portion.

FIG. 4 shows the ratio between the pen height and the maximum output value Ymax / Xm
7 is a graph showing a relationship with ax.

FIG. 5 is a flowchart of a coordinate reading process.

FIG. 6 is a flowchart of an x coordinate calculation process.

FIG. 7 is a graph showing a relationship between an x coordinate and an output value from a coil.

FIG. 8 is a table showing a relationship between a value RX calculated from an output value of a coil and an offset value of an x coordinate from a center position of the coil.

FIG. 9 is a flowchart of z coordinate calculation processing.

FIG. 10 shows offset values of the x coordinate from the center position of the coil, and maximum output values Xmax and Ym from the output value of the coil.
9 is a table showing a relationship between conversion coefficients α and β used when estimating ax.

[Explanation of Signs] 1 ... Notebook, 3 ... Pen, 5 ... Paper, 7 ...
Microphone, 9: speaker, 11: switch group, 1
3 ... CPU, 15 ... memory, 17 ... grid section, 19 ... selector section, 21 ... first amplifier,
23 ... detector, 25 ... A / D converter, 26 ...
-FSK demodulation circuit, 27 ... second amplifier, 29 ...
Codec, 31 ... third amplifier, 41 ... surface layer,
43: first coil group, 45: first intermediate layer, 4
7 ... second coil group, 49 ... second intermediate layer, 51
... Shield plate.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B068 AA04 BB14 BC03 BC10 BD02 BE06 CC12 EE04

Claims (4)

[Claims] A first coil group in which a plurality of coils parallel to the y-axis are arranged at a predetermined pitch in the x-axis direction on a first plane perpendicular to the z-axis; Are arranged at a predetermined pitch in the y-axis direction on a second plane perpendicular to the z-axis.
The first coil group is designated by a coordinate group indicating a point from which coordinates are to be read.
First signal detecting means for detecting a signal induced in a coil belonging to the coil group; and guiding to a coil belonging to the second coil group in accordance with a point at which coordinates to be read are designated by the coordinate designating means. A second signal detecting means for detecting a signal to be detected, and a position of each coil belonging to the first coil group and the first signal detecting means, based on the signal detected by the first signal detecting means. X-coordinate specifying means for obtaining the x-coordinate of the point specified by the coordinate specifying means from the relationship between the detected output value of the signal guided to each coil, and a signal detected by the second signal detecting means. Based on the relationship between the arrangement position of each coil belonging to the second coil group and the output value of the signal guided to each coil detected by the second signal detection means, Based on the y-coordinate specifying means for obtaining the y-coordinate of the point indicated by the first signal detecting means, the output value of the signal detected by the first signal detecting means, and the output value of the signal detected by the second signal detecting means. A coordinate reading device comprising: a z-coordinate specifying means for obtaining a z-coordinate of a point designated by the coordinate designating means. 2. The method according to claim 1, wherein the z-coordinate specifying means includes a maximum output value Xmax estimated from a signal detected by the first signal detecting means, and a maximum output value Ymax estimated from a signal detected by the second signal detecting means. 2. The coordinate reading apparatus according to claim 1, wherein a z-coordinate of the point designated by the coordinate designating means is obtained based on a ratio of the coordinate reading means. 3. The system according to claim 1, wherein a z-coordinate of the point designated by said coordinate designating means is estimated from a signal detected by said first signal detecting means in a state in which said z-coordinate is closest to said first coil group and said second coil group. Ymax / Xmax or Xmax with respect to the maximum output value Xmax and the maximum output value Ymax estimated from the signal detected by the second signal detection means.
The first coil group and the second coil group on the first plane are so arranged that x / Ymax is 0.5 or more and 0.9 or less.
3. The coordinate reading device according to claim 1, wherein the second coil group on the flat surface is disposed with a predetermined gap therebetween. 4. 4. The first signal detected by the first signal detecting means.
First maximum output value estimating means for estimating the maximum output value Xmax from the maximum output value of the signal induced to each coil belonging to the coil group and the x coordinate obtained by the x coordinate specifying means; The maximum output value Ymax is estimated from the maximum output value of the signal guided to each coil belonging to the second coil group detected by the second signal detection unit and the y coordinate obtained by the y coordinate specification unit. 4. The coordinate reading apparatus according to claim 1, further comprising a second maximum output value estimating unit that performs the operation.