JPH08202491A - Digitizer - Google Patents

Abstract

PURPOSE: To provide a position coordinate calculating method which is similar to others by adjusting the width of the loop coil at a part corresponding to a position where the magnetic field produced by a position indicater varies. CONSTITUTION: An area is divided into an area where the intensity of the magnetic field produced by the position indicator is represented as e0, an area where it is represented as e1, and an area where it is represented as e2, and loop coils are arranged corresponding to the respective areas. Namely, the width of the loop coil corresponding to the area of e0 is w0, the width of the loop coil corresponding to the area of e1 is w1, and the width of the loop coil corresponding to the area of e2 is w2. They are related so that w1≈w2.e2/e1 and w0≈w1.e1/e0. Consequently, the tilt components of the straight areas of the output signals of the respective loop coils can be made nearly equal and the position calculating method which is similar to conventional examples can be utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention determines the position coordinate of a position indicator on a tablet based on an output signal from the action of a position coil and a loop coil group arranged in relation to the position on the tablet. It relates to a digitizer that is adapted to calculate. More specifically, it relates to a digitizer in which the magnitude of the action of the position indicator and the loop coil group of the tablet is not constant depending on the position of the position indicator.

[0002]

2. Description of the Related Art As a digitizer of this type, there is a digitizer described in Japanese Patent Application No. 6-141227 filed by the applicant of the present application. The digitizer will be described below with reference to FIGS. Here, FIG. 2 is a schematic explanatory view showing the arrangement of the loop coil group on the tablet, FIGS. 3 and 4 are schematic explanatory views showing the position determination principle of this device,
FIG. 5 is an explanatory diagram for explaining the arrangement of the linear region by the loop coil group shown in FIG. 2, FIG. 6 is an explanatory diagram showing the problems of this device, and FIG. 7 is an overall configuration diagram of this digitizer. is there.

First, the overall construction and operation of this digitizer will be described with reference to FIG. The tablet 1 has a plurality of X-direction loop coil groups (A
1, A2, A3, ..., B1, B2, B3, ...)
And a plurality of Y-direction loop coil groups (C1, C2, C3, ..., D1, D2, D3, ...
・) Positioning loop coil group consisting of and is arranged. X direction loop coil group loop coils A1, A2,
As indicated by the solid line in FIG. 2 (hereinafter referred to as the solid line loop coil group), A3, ..., The long side conductor on the right side of the loop coil A1 and the long side conductor on the left side of the loop coil A2,
The long side conductor on the right side of the loop coil A2 and the loop coil A3
, The left long-side conductor of the loop coil A3, the left long-side conductor of the loop coil A3, and the left long-side conductor of the loop coil A4 are electrically insulated from each other and are arranged in contact with or overlapping each other. Similarly, the loop coils B1, B2, B3, ... Of the X-direction loop coil group have a length on the right side of the loop coil B1 as shown by a broken line in FIG. 2 (hereinafter, referred to as a broken line loop coil group). The side conductor and the left long side conductor of the loop coil B2, the right side long conductor of the loop coil B2 and the left side long conductor of the loop coil B3, the right side long side conductor of the loop coil B3 and the left side length of the loop coil B4. Edge conductor,
.. are arranged in a state of being electrically insulated from each other and contacting or overlapping. The solid line loop coil group and the broken line loop coil group are arranged so as to be shifted from each other by a half pitch. In addition, each loop coil group in the Y direction is similarly arranged.

As shown in FIG. 7, two loop coil groups in each direction are respectively connected to the X-axis scanner 11 and the Y-axis scanner 12 and selected by an address control signal from the control means 15. , A summing amplifier 132, 162 and a subtracting amplifier 131,
161 and the amplifier groups 13 and 16 on the respective sides. The output signals of the X-side voltage amplifier group 13 and the Y-side voltage amplifier group 161 are data including position information in the respective directions, as will be described later, and are therefore transmitted to the control means 15. In this case, the output signal of the summing amplifier 132 of the X-side amplifier group 13 and the Y-side amplifier group 1 are used in this embodiment.
6 and the output signal of the summing amplifier 162 can be selectively connected to the input side of the current amplifier 14.

Further, in the apparatus of this embodiment, the peripheral coil 101 is arranged so as to surround the loop coil group on the tablet 1. This surrounding coil 1
01 is connected to the output side of the current amplifier 14. Here, the addition amplifiers 132 and 162 of the amplifier groups 13 and 16 on the respective sides add signals generated in the selected two loop coil groups, and subtraction amplifiers 131 and 16 are added.
1 performs subtraction of the signals generated in the selected two loop coil groups, and the current amplifier 14 is configured as a saturation amplifier that produces the maximum output even when the input signal is extremely small. ing.

The position pointing device 2 comprises a coil L as a position pointing element, first and second capacitors 221, 222 and a switch 23. A plurality of different LC circuits (loads on the position indicating element L) can be selected by the user turning the switch 23 on and off. Therefore, when the position indicator 2 (position indicating element L) is positioned on the surface of the tablet 1, a loop coil on one side arranged in close proximity, for example, a pair of X-direction loop coils (position determining element) is controlled. In response to a command from the means 15, the summing amplifier 132 of the X-side amplifier group 13 is transmitted via the X-axis scanner 11.
When connected to the input side of, the "loop coil pair in the proximity position", "the subtraction amplifier 132 of the X side amplifier group 13",
A connection system of the "current amplifier 14", the "surrounding coil 101", the "position indicating element L" and the "loop coil pair in the close position" is formed. Such a connection system is oscillated at a specific frequency triggered by ambient noise radio waves. In this specification, a connection system capable of such oscillation will be referred to as an oscillation system. As described above, since the current amplifier 14 is a saturation amplifier, even if the output of the summing amplifier 132 on the X side is small, it is amplified to the maximum output value, so that a stable oscillation state can be obtained quickly. You can

Such an oscillating state acts to generate a stable magnetic field from the "position pointing element L of the position pointing device 2" in this embodiment. Then, the signal generated in the loop coil group on the other side under the stable magnetic field from the position pointing element L in this oscillation state is used. The signal produced in the loop coil group on the other side contains information related to the distance between each position determining element and the position indicating element. In this specification, such outputs will be referred to as "position-related signals". According to a command from the control means 15, one side is fixed as an oscillation system, and the position determining element on the other side is switched one after another by using the scanner on the other side to sequentially obtain different "position-related signals". , The pointing position coordinates of the position pointing device 2 on the tablet 1 can be obtained.

Next, the position coordinate determining operation of this apparatus will be described in detail with reference to FIGS. It should be noted that detailed X-direction position detection and Y-direction position detection of the position indicated by the position indicator 2 (position indicating element L) on the tablet 1 include many similar operations. The position detection operation will be described, and the detailed position detection operation in the Y direction will be described as necessary.

Now, the two loop coils A3 and A4 shown in FIG.
(This is the same as the loop coils C3 and C4 in the Y direction). These loop coils A3,
A4s are arranged in contact with each other in an insulated state (actually, the opposite long sides of the respective loop coils are overlapped). While the position pointing element L of the position pointing device 2 is generating a stable magnetic field, these loop coils A3, A4
Letting VA3 and VA4 be the output voltages when traversing each other, these signals VA3 and VA4 change as shown in FIG. The output level curve by the action of the loop coils of A3 and A4 and the position indicating element L of the position indicator 2 becomes "maximum (or minimum)" when the position indicating element L exists near the center of each loop coil, The position indicating element L gradually decreases (or increases) as it deviates from the center. This decreasing (or increasing) region can be regarded as a substantially linear changing region.

The overlapping portion of the loop coil A3 and the loop coil A4 is set in the X direction (generally, the arrangement direction of the loop coil).
When the negative linear region of the signal VA3 shown in FIG. 3 is (-ax + b), the positive linear region of the signal VA4 is (ax + b). This is because the loop coil X3 and the loop coil X4 are made of the same material and have the same shape, and are simply arranged at different positions. Both signals VA3 and VA
The absolute value of the "sum" of 4 is a constant value 2b, and the "difference" of these signals is 2ax. That is, regarding the two loop coils A3 and A4 shown in FIG. 2, when the position indicating element L exists in both linear regions of the loop coils A3 and A4,
The absolute value of the "sum" of both signals shows a constant value, and the "difference" of both signals is expressed as a linear function of the position X (or Y) in both the straight regions. Therefore, as shown in FIG. 5, coordinates can be read in a wide range by sequentially arranging such linear regions in the position determining direction.

In this case, the "sum" of both signals
The absolute value of is smaller (or larger) than the position indicating element L when the position indicating element L is out of the linear region. Therefore, it can be said that the absolute value of this "sum" shows the maximum (or minimum value) in this linear region. Since this apparatus uses the above-mentioned position determination principle, the "sum" and "difference" of the signals generated in the loop coils in which the opposing long-side conductors are arranged close to each other are obtained to determine the position indicating element L The indicated coordinate value can be obtained.

The detailed position determination procedure of this device is as follows. 1. "Stable Y-side Oscillation System Specific Stage" The control means 15 commands the Y-axis scanner 12 to sequentially select and connect adjacent loop coil pairs in the Y direction. Therefore, in this operation, the selected Y-direction loop coil pair and the summing amplifier 1 of the Y-side voltage amplifier group 16 are selected.
62, the current amplifier 14, the surrounding coil 101, and the Y-side connection system including the selected Y-direction loop coil pair are sequentially formed. When the position pointing element L of the position pointing device 2 is present in the vicinity of the selected Y-direction loop coil pair, these connection systems form an oscillation system triggered by ambient noise radio waves and are selected. Oscillation starts at an intensity according to the distance between the Y-direction loop coil pair and the position indicating element L. Output of these oscillation systems (output of summing amplifier 162)
Is input to the control means 15 shown in FIG. Control means 1
5 compares the outputs of the Y-side oscillation systems by the Y-direction loop coil pairs whose arrangement positions are sequentially different. Then, the order of the Y-side oscillation system, that is, the Y-side loop coil, whose output shows the maximum value (stable oscillation operation) is specified.

2. "Induction Signal Acquisition Stage of Pair of X-Direction Positioning Elements" Now, when the order of the oscillating system which has generated the maximum oscillating output by the above operation, that is, the Y-direction loop coil at that time is specified, " Operation of "guidance signal acquisition step of X-direction position determining element pair" is started. The control means 15 fixes the loop coil pairs in the Y direction to the ones specified above, and selects the pair of adjacent loop coil pairs in the X direction by sequentially changing the order. (See FIG. 2). Due to the oscillation of the Y-side oscillation system that generates the maximum oscillation output, a stable magnetic field is generated from the position pointing element L of the position pointing device 2, and a stable action is applied to the selected X-direction loop coil pair. It becomes a state.

During this period, the control means 15 issues a command to the X-axis scanner 11 to sequentially select adjacent X-direction loop coil pairs, and at the same time, selects the output signal of the summing amplifier 132 of the X-side voltage amplifier group 13, that is, the selection. The [sum] signals generated in the X-direction position determining element (loop coil) pair are sequentially captured. The "order of the selected X-direction loop coil pair" and the "sum" data of the induction signals thereof are sequentially stored in pairs in the built-in memory of the control means 15.

4. "X-direction position determining step" Next, the control means 15 performs the "X-direction position determining step". A plurality of Xs acquired and stored by the operation described above
The following operation is performed on the "sum" data of the directional loop coil pair.

1) The absolute values of the "sum" data obtained by the adjacent X-direction loop coils are successively calculated, and the rank of the X-direction loop coil pair that gives the maximum calculation result is specified. That is, for each “sum” data, for example, in FIG.
Referring to the first set of "absolute value of sum of output data of loop coil A1 and loop coil A2 adjacent to this loop coil A1 in the same set", and second set of "loop coil B1 and this "Absolute value of sum of output data of loop coil B1 adjacent to loop coil B1 in the same set", first output "loop coil A2 and output data of loop coil A3 adjacent to this loop coil A2 in the same set" The absolute value of the sum of the output data of the loop coil B2 and the output data of the loop coil B3 which is adjacent to the loop coil B2 in the same group, and the first set of the "loop coil A3". And this loop coil A3 and the adjacent loop coil A in the same set.
The absolute value of the sum of the output data of 4 ”, ...
The order of the loop coil pair that gives the maximum calculation result is specified. Now, as shown in FIG. 2, the first loop coil A
Assuming that the absolute value of the “sum” of the outputs of the adjacent loop coils A4 of the same set as the output of No. 3 becomes the maximum, the position indicator 2
It can be seen that the position indicating element L of exists in the linear region indicated by A3A4.

2) Find the "difference" between the outputs of the identified X-direction loop coil pair. Control means 1 shown in FIG.
5 connects the X-axis scanner 11 to the previously specified rank pair (rank pair that produced the largest "sum" data). And X
The output of the subtracting amplifier 132 of the side voltage amplifier group 13 is taken in, and the “difference” between the outputs of the respective X-direction loop coils of the above specified rank pair is obtained. For example, according to FIG.
"Output by loop coil A3" and "loop coil A4
The difference in “output by” appears as the output of the subtraction amplifier 132. This "difference" output is the linear area A3A specified above.
4 shows the position in the X direction within 4. The absolute position of the linear region A3A4 in the X direction is known because the arrangement position of the loop coil or the like is determined in advance. Therefore, by performing this operation, the position indicating element L
The absolute position of X in the X direction can be obtained.

5. "Stable X-side oscillation system specifying step" This operation corresponds to the "stable X-side oscillation system specifying step" described above.
Each operation is exactly the same as the above operation except that the direction is different. This is an operation for recognizing the oscillation system that generates the maximum oscillation output in each oscillation system in the X direction in order to determine the position in the Y direction. In this case, in practice, the X-direction loop coil pair that is close to the position indicator 2 can be recognized to some extent in the previous "sum" signal acquisition step of the X-direction loop coil pair. Select the maximum for the X-direction loop coil pair without staring from the beginning (for example, the loop coil pair close to the rank of the X-direction loop coil pair that generated the maximum "sum" signal in the previous operation) (max. It is also possible to specify the order of the pair of X-direction loop coils that are stable oscillation systems. By operating in this way, the selection operation for the X-direction loop coil can be minimized and the position determination speed can be improved. 6, "Y-direction position determining element pair guidance signal acquisition stage",
"Y-direction position determination step" The operations in these steps are also the same as those described above, except that the directions are different. By executing each of the above operation modes, X of the position pointing element L of the position pointing device 2 is X.
The Y coordinate value can be determined.

[0019]

In the device having the above-mentioned operation, it is premised that the magnetic field generated by the position pointer is substantially the same at any position on the tablet. This is because when the magnetic field of the position indicator is different, the output due to this action varies depending on the position where the position indicator is present. In the conventional device utilizing the combination of the surrounding coil 101, the loop coil group (sense coil group) in each direction, and the position indicator as described above, as shown in FIG.
1 has a characteristic that the magnetic field acting on the position indicator becomes larger as the position is closer to 1. Therefore, in the conventional device, the region close to the surrounding coil 101 is used as the dead space. The present invention has been made to improve this point.

[0020]

Therefore, according to the present invention, when the position indicator and the loop coil are electromagnetically coupled to each other, the position indicator exists in the widthwise center of the loop coil. A loop coil configured to output a maximum or minimum signal that substantially linearly decreases or increases from the maximum or minimum as the position indicator is displaced from the widthwise center to the end of the loop coil. In a digitizer for determining the position of the position indicator on the tablet by using a linearly decreasing or increasing portion of a signal generated in each loop coil. In order to compensate for the variation in the magnitude of the electromagnetic coupling action between each of the loop coils on the tablet and the tablet, the tag corresponding to the position of the position indicator where the variation occurs. The loop coil on Rett varied in width with the other configured to linearly decreasing or increasing signal is generated having substantially the same gradient component and linearly decreases or signal increases occurring other loop coil,
It is characterized in that the signals generated in all the loop coils for obtaining the position of the position indicator on the tablet are linearly decreasing or increasing signals having substantially the same gradient components.

[0021]

By adjusting the width of the loop coil in the portion corresponding to the portion where the magnetic field emitted by the position indicator fluctuates, the gradient component of the signal generated in the loop coil is made equal to the gradient component of the signal generated in the other loop coil. It should be With this configuration, the same position coordinate calculation method can be used.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG. Here, the upper diagram of FIG. 1 shows the state of the magnetic field generated by the position indicator, and the interrupted diagram of FIG. 1 shows the width of the loop coil corresponding to the portion where the magnetic field generated by the position indicator becomes large. 2 is an explanatory view showing an example of a loop coil arrangement that is smaller than the loop coil of FIG. 1, and the drawing in the lower part of FIG.

As shown in the upper diagram of FIG. 1, the magnitude of the magnetic field generated by the position indicator is divided into a region represented by e0, a region represented by e1, and a region represented by e2. Loop coils are arranged corresponding to the regions. That is, as shown in the middle diagram of the figure, the width of the loop coil corresponding to the area represented by e0 is set to w0, and the width of the loop coil corresponding to the area represented by e1 is set to the area represented by w1 and e2. The width of the corresponding loop coil is w2. These relationships are almost “w1≈w2 · e2 / e1” and “w0≈w1 · e1 / e0”.

With such a configuration, as shown in the lower diagram of FIG. 1, the inclination components of the linear region of the output signal of each loop coil can be made the same, and the position calculating method similar to the prior art example can be performed. Can be used. In addition, as shown in the lower diagram of FIG. 1, the “sum” signal of the signals generated in the adjacent loop coils by shifting (for example, adding the bias voltage) the signals appearing in each loop coil is set to 0 (zero). be able to. In this case, in order to eliminate the error near the end of each linear region, one or more sets of loop coil groups similar to the loop coil group shown in the middle diagram of FIG. 1 are prepared, and as shown in FIG. It is desirable to dispose the loop coil groups so that their positions are displaced from each other.

In the embodiment described above, the digitizer of the type in which the output signal due to the interaction with each loop coil produces the maximum output level when the position indicator 2 exists near the center of the loop coil has been described. , JP-A-3
It is also applicable to a digitizer such as that shown in -241415, that is, a digitizer that produces a minimum output level when a position indicator exists near the center of a loop coil and gradually increases the output level as it approaches an end. It's clear. In this case, the smallest "sum" signal may be selected.

[0026]

As described above, according to the present invention, even if the acting magnetic field from the position indicator fluctuates depending on the place (position), the width of the loop coil corresponding to the fluctuating position is increased / decreased. Since the linear region of the signal generated in the coil is set to have a gradient component that is substantially the same as the gradient of the linear region of the signal generated in another loop coil, the same position coordinate calculation method as in the other cases can be implemented.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating the configuration and operation of a device according to a first embodiment of the present invention.

FIG. 2 is a layout diagram of loop coils of a conventional device.

FIG. 3 is a schematic diagram showing a position determination principle of the present invention and a conventional device.

FIG. 4 is a linear region diagram of the present invention and a conventional device.

FIG. 5 is an explanatory diagram showing disadvantages of the conventional device.

FIG. 6 is an overall configuration diagram of the present invention and a conventional device.

[Explanation of symbols]

 1: Tablet 2: Position indicator

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[Procedure amendment]

[Submission date] November 7, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art As a digitizer of this type, there is a digitizer described in Japanese Patent Application No. 6-141227 filed by the applicant of the present application. Hereinafter, the digitizer will be described with reference to Figures 2-6. Here, FIG. 2 is a schematic explanatory view showing the arrangement of the loop coil group on the tablet, FIGS. 3 and 4 are schematic explanatory views showing the position determination principle of this device,
FIG. 5 is an explanatory view showing a problem of this device, and FIG. 6 is an overall configuration diagram of this digitizer.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

[0003] First, referring to FIG. 6 illustrating the overall configuration and operation of the digitizer. The tablet 1 has a plurality of X-direction loop coil groups (A
1, A2, A3, ..., B1, B2, B3, ...)
And a plurality of Y-direction loop coil groups (C1, C2, C3, ..., D1, D2, D3, ...
・) Positioning loop coil group consisting of and is arranged. X direction loop coil group loop coils A1, A2,
As indicated by the solid line in FIG. 2 (hereinafter referred to as the solid line loop coil group), A3, ..., The long side conductor on the right side of the loop coil A1 and the long side conductor on the left side of the loop coil A2,
The long side conductor on the right side of the loop coil A2 and the loop coil A3
, The left long-side conductor of the loop coil A3, the left long-side conductor of the loop coil A3, and the left long-side conductor of the loop coil A4 are electrically insulated from each other and are arranged in contact with or overlapping each other. Similarly, the loop coils B1, B2, B3, ... Of the X-direction loop coil group have a length on the right side of the loop coil B1 as shown by a broken line in FIG. 2 (hereinafter, referred to as a broken line loop coil group). The side conductor and the left long side conductor of the loop coil B2, the right side long conductor of the loop coil B2 and the left side long conductor of the loop coil B3, the right side long side conductor of the loop coil B3 and the left side length of the loop coil B4. Edge conductor,
.. are arranged in a state of being electrically insulated from each other and contacting or overlapping. The solid line loop coil group and the broken line loop coil group are arranged so as to be shifted from each other by a half pitch. In addition, each loop coil group in the Y direction is similarly arranged.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

As shown in FIG. 6 , two loop coil groups in each direction are connected to the X-axis scanner 11 and the Y-axis scanner 12, respectively, and are selected by an address control signal from the control means 15. , A summing amplifier 132, 162 and a subtracting amplifier 131,
161 and the amplifier groups 13 and 16 on the respective sides. The output signals of the X-side voltage amplifier group 13 and the Y-side voltage amplifier group 161 are data including position information in the respective directions, as will be described later, and are therefore transmitted to the control means 15. In this case, the output signal of the summing amplifier 132 of the X-side amplifier group 13 and the Y-side amplifier group 1 are used in this embodiment.
6 and the output signal of the summing amplifier 162 can be selectively connected to the input side of the current amplifier 14.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The overlapping portion of the loop coil A3 and the loop coil A4 is set in the X direction (generally, the arrangement direction of the loop coil).
When the negative linear region of the signal VA3 shown in FIG. 3 is (-ax + b), the positive linear region of the signal VA4 is (ax + b). This is because the loop coil X3 and the loop coil X4 are made of the same material and have the same shape, and are simply arranged at different positions. Both signals VA3 and VA
The absolute value of the "sum" of 4 is a constant value 2b, and the "difference" of these signals is 2ax. That is, regarding the two loop coils A3 and A4 shown in FIG. 2, when the position indicating element L exists in both linear regions of the loop coils A3 and A4,
The absolute value of the "sum" of both signals shows a constant value, and the "difference" of both signals is expressed as a linear function of the position X (or Y) in both the straight regions. Therefore, as shown in FIG. 4 , by sequentially arranging such linear regions in the position determining direction, the coordinates can be read in a wide range.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

The detailed position determination procedure of this device is as follows. 1. "Stable Y-side Oscillation System Specific Stage" The control means 15 commands the Y-axis scanner 12 to sequentially select and connect adjacent loop coil pairs in the Y direction. Therefore, in this operation, the selected Y-direction loop coil pair and the summing amplifier 1 of the Y-side voltage amplifier group 16 are selected.
62, the current amplifier 14, the surrounding coil 101, and the Y-side connection system including the selected Y-direction loop coil pair are sequentially formed. When the position pointing element L of the position pointing device 2 is present in the vicinity of the selected Y-direction loop coil pair, these connection systems form an oscillation system triggered by ambient noise radio waves and are selected. Oscillation starts at an intensity according to the distance between the Y-direction loop coil pair and the position indicating element L. Output of these oscillation systems (output of summing amplifier 162)
Is input to the control unit 15 shown in FIG. Control means 1
5 compares the outputs of the Y-side oscillation systems by the Y-direction loop coil pairs whose arrangement positions are sequentially different. Then, the order of the Y-side oscillation system, that is, the Y-side loop coil, whose output shows the maximum value (stable oscillation operation) is specified.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

[0019]

In the device having the above-mentioned operation, it is premised that the magnetic field generated by the position pointer is substantially the same at any position on the tablet. This is because when the magnetic field of the position indicator is different, the output due to this action varies depending on the position where the position indicator is present. In the conventional device utilizing the binding between peripheral coil 101 as previously described and each direction loop coil group (sense coil group) and the position indicator, as shown in FIG. 5, the position indicator is around coil 10
1 has a characteristic that the magnetic field acting on the position indicator becomes larger as the position is closer to 1. Therefore, in the conventional device, the region close to the surrounding coil 101 is used as the dead space. The present invention has been made to improve this point.

[Procedure Amendment 7]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

FIG.

[Figure 3]

[Figure 4]

[Figure 5]

[Fig. 2]

[Figure 6]

Claims (1)

[Claims] 1. When the position indicator and the loop coil are electromagnetically coupled to each other, the position indicator outputs a maximum or minimum signal when the position indicator is present in the widthwise center of the loop coil. A loop coil configured to output a signal that linearly decreases or increases from the maximum or minimum according to the displacement from the center to the end in the width direction of the loop coil is arranged on a plurality of tablets in relation to position. In a digitizer for determining the position of the position indicator on the tablet by using the linearly decreasing or increasing portion of the signal generated in each loop coil, electromagnetic coupling between the position indicator and each loop coil on the tablet In order to compensate the fluctuation of the magnitude of the action, the width of the loop coil on the tablet corresponding to the position of the position indicator where the fluctuation occurs is made different from other widths. The position of the pointing device on the tablet is obtained by arranging so that a linearly decreasing or increasing signal having almost the same slope component as the linearly decreasing or increasing signal generated in another loop coil is generated. The digitizer characterized in that the signals generated in all the loop coils are linearly decreasing or increasing signals having almost the same gradient component.