JPH0749740A - Digitizer - Google Patents

Abstract

PURPOSE:To accurately calculate a coordinate position indicated by a position indicator by adjusting relation between each loop coil and division width in accordance with the level of an output signal from an output signal area regarded as a straight line and measuring the order and level values of loop coils generating output signals corresponding to respective divided areas. CONSTITUTION:When the centers of loop coils x(i-3) x (i+2), x (i+3) are respectively set up as C1, C2 and C3, respective output level values OP1, OP2, OP3 exist on respective centers C1, C2, C3. One measuring value is obtained on the left side of the center P1 of the position indicator 2 and two measuring values are obtained on the right side to calculate a straight line passing the points OP2, OP3. A point D having the same level value as the point OP1 on the straight line is found out and then a distance between the points OP1 and D is found out. A half of the distance value expresses the distance from the center position of the loop coil x (i-3) of the position indicator 2 in the x direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digitizer for calculating a pointing position of a pointing device on a tablet based on output signals produced by the action of a large number of loop coils arranged on the tablet and the pointing device. Regarding

[0002]

2. Description of the Related Art FIGS. 6 to 7 are configuration explanatory views showing examples of conventional digitizers. On the tablet of the digitizer in FIG. 6, for example, a group of X-direction loop coils (x1, x2, x3, ...) Sequentially arranged in the X direction and a group of Y-direction loop coil sequentially arranged in the Y direction. (Y1, y
2, y3, ...) Are provided. The X-direction loop coil group is selectively connected to the input side of the voltage amplifier 13 via the X-axis scanner 11, and the Y-direction loop coil group is selectively connected to the output side of the current amplifier 14 via the Y-axis scanner 12. To be done. The output side of the voltage amplifier 13 is connected to the input side of the current amplifier 14 and has a structure capable of forming a so-called closed loop. Therefore, in this specification, these amplifiers are simply referred to as "amplifying means" unless necessary. I will call it. Assuming that the position indicator 2 is positioned on the surface of the tablet 1, the X-side loop coil and the Y-side loop coil, which are arranged close to the coil 21 of the position indicator 2, are the X-side scanner 11 and the Y-side, respectively. Scanner 12
When connected to the input side and the output side of the amplifying means via the, the oscillating system is constituted by the coil 21 of the position indicator, the amplifying means, and the X-side loop coil and the Y-side loop coil connected to the amplifying means. Oscillation is started at the frequency peculiar to the oscillation system triggered by the noise radio wave. The output of the voltage amplifier 13 at this time is input to the utilization circuit 15 and used for position determination. Such an oscillating system is sequentially constructed by switching the respective loop coil groups one after another by the X-axis scanner 11 and the Y-axis scanner 12, and the output of the amplifier is sequentially measured and stored for each individual oscillating system. In this way, since the oscillation output is stored and stored for each oscillation system, that is, along with the rank of each X-side and Y-side loop coil, the output distribution corresponding to the rank of each side loop coil can be obtained. The utilization circuit 15 calculates and determines the position of the position indicator in the X and Y directions from the output distribution result.

FIG. 6 is also displayed on the digitizer tablet shown in FIG.
, The X-direction loop coil group (x1, x2, x3, ...) Sequentially arranged in the X direction and the Y-direction loop coil group (y1, y2, Sequentially arranged in the Y direction).
y3, ...) Is provided. The position indicator 2
Is supplied with power via a cable, and a magnetic field is constantly emitted from the coil 21 toward the surface of the tablet 1. The X-direction loop coil group is selectively connected to the input side of the voltage amplifier 13 via the X-axis scanner 11, and the Y-direction loop coil group is also selectively connected to the input side of the voltage amplifier 14 via the Y-axis scanner 12. It is connected. The outputs of the voltage amplifiers 13 and 14 on the respective sides are respectively input to the utilization circuit 15, and in the X direction, the order of the X direction loop coils and the output voltage level value thereof, and in the Y direction, the Y direction loop. The rank of the coil and the output voltage level value thereof are paired and stored. Therefore, a voltage distribution according to the rank of the loop coils can be obtained in both the X and Y directions, and the coordinate position in the X direction and the Y direction on the tablet designated by the position indicator 2 can be detected.

[0004]

By the way, in each of the above-mentioned devices, the pointing coordinate value of the position pointing device is obtained based on the order of the loop coils in each direction and the distribution of the voltage level thereof. This is based on the assumption that the order of the loop coils and the distribution of their voltage levels can be approximated to a quadratic function. Take out at least three voltage levels of each distribution state (these voltage levels are related to the position based on the order of the loop coil), and calculate the vertex position by a predetermined calculation formula using a quadratic function. I am doing so. However, when the above-mentioned voltage level distribution cannot be approximated to a quadratic function, the calculated position is inaccurate. As an example of the case where a circular coil cannot be approximated to a quadratic function, in the case where a circular coil is used as the position indicator 2, selection or position indication independent of the width W of the loop coil and the diameter of the coil 21 of the position indicator 2 is performed. There are variations in the distance (height) from the tablet surface of the container 2. For example, as shown in FIG. 4, due to fluctuations in the distance h between the position indicator 2 and the tablet surface provided with the plurality of loop coils, h1, h2, h3, As in the case of h4, the output level fluctuates, and depending on its height, it may deviate significantly from the quadratic function. In such a case, the position calculation method using the quadratic function is meaningless. The present invention has been made for the purpose of improving this point, and provides a coordinate position calculating method for accurately calculating a coordinate position indicated by a position indicator regardless of whether or not a quadratic function can be approximated. It is provided.

[0005]

Therefore, in the present invention, when the position indicator is present near the center of the loop coil, the output signal exhibits the maximum or minimum level,
The level of the output signal gradually decreases or increases as the position indicator moves away from the center of the loop coil, and the decrease or increase rate of the output signal is linear at least partially. It can be regarded that the loop coil is symmetrical with respect to the center of the loop coil, and the tablet in which the loop coils are sequentially arranged in a plurality of predetermined directions, a position indicator positioned on the tablet, and the tablet In the digitizer having position calculating means for calculating the position (coordinates) of the position indicator on the tablet based on the output signals generated by the action of the plurality of loop coils and the position indicator, the position calculating means Is an area that can be regarded as a straight line of the output signal and has at least three regions depending on the level of the output signal. Linear region dividing means for dividing the frequency band,
When the position indicator is within the measurement range, the one indicating the output level of each of the divided at least three regions among the output signals by the action of the position indicator and each loop coil, When at least the division adjusting means for adjusting the relationship between the loop coils and the division width of the linear area dividing means and the position indicator are present in the measurement range so that one each is generated, at least three of the divided areas are provided.
Measuring means for measuring the order and the level value of the loop coil which has produced the output signal corresponding to each of the two areas, and the position indication based on the at least three output level values and the order of the loop coil corresponding to these And a means for determining the existing position (coordinates) of the container on the tablet.

[0006]

As shown in FIG. 3, consider a loop coil (for example, x1) having a width W and a position indicator 2. Now, it is assumed that the position indicator 2 has moved from the left end L to the right end R of the loop coil x1. Plotting the level of the output signal corresponding to the position of the position indicator 2 at this time is as shown in the lower part of FIG. The present invention utilizes the following two items in such a case. That is, A. As the position indicator 2 moves from the center to both ends, there is a change area of the output level, but some or all of this change area can be regarded as a straight line, and B. That is, it can be considered that the change regions on both sides with respect to the center line of the loop coil x1 are symmetrical. Generally, a plurality of loop coils shown in FIG. 3 are arranged with their positions shifted in the left-right direction by a predetermined distance, and the levels of a plurality of output signals associated with each loop coil are associated with the position (rank) of the loop coil. If plotted, the curve similar to that shown in the lower part of FIG. 3 can be obtained. If it is possible to know the output level values of three or more points (at least two points on one side and one point on the other side) in the area that can be regarded as a straight line area of such a curve and the rank of the corresponding loop coil, the position indicator 2 It is possible to determine the existence position of. For example, a first straight line is calculated from two points on one side, a second straight line which is symmetrical to this and passes through one point on the other side is calculated, and the intersection point of the first straight line and the second straight line is calculated. By doing so, the position of the position indicator 2 can be calculated.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 and 2 respectively show an apparatus according to an embodiment of the present invention.
FIG. 1 is an explanatory view showing a loop coil configuration on a tablet 1 and an output relationship by the action of these loop coil configurations and a position indicator 2, and FIG. 2 is a schematic diagram schematically showing a position determining method of the present invention. is there. Since the present invention can be implemented by a configuration equivalent to that of the conventional device shown in FIG. 6 or 7,
The following description will be made with reference to the respective configurations shown in both figures.

Please refer to FIG. X on the tablet 1
Loop coils (x1, x
2, x3, ...) Is provided. In the lower diagram of FIG. 1, the level of the output signal generated in each loop coil when the position indicator 2 is moved from the left end to the right end of these loop coil groups is related to the arrangement position (order) of each loop coil. It is a plot. In this case,
When the position indicator 2 is at the center position of each loop coil, the output signal of the loop coil shows the maximum level value, and the output level value gradually decreases as the position indicator 2 moves away from this center position. To go. These maximum level values and the state of decrease thereof are design matters and can be obtained in advance by calculation or experiment. Similarly, the output level variation when the height of the position indicator 2 varies and the distribution corresponding to the order of existence of each loop coil can also be obtained by calculation or experiment.

Based on the results of these calculations or experiments, the linear areas (that is, the maximum level value and the minimum level value) shown in the figure are determined, and the first, second and third areas in these areas are determined. To do. In this specification, the means for performing these means or processing will be referred to as linear area dividing means. At this time, when the position indicator 2 exists in the measurement range, each divided area is adjusted so that at least one output signal of any loop coil exists in each of these divided areas. The adjustment of this divided area is performed by adjusting the width of each loop coil and its deviation (pitch).
P is involved. In this specification, the means for performing these means or processes will be referred to as division adjusting means. In addition,
Apart from this method, the relationship between the output level fluctuation due to the height fluctuation of the position indicator 2 and the fluctuation of the linear region at that time may be stored and stored in the memory of the device in advance based on the above calculation or experiment result. it can. In this case, when measuring the position indicated by the position indicator 2, first, the loop coils on the surface of the tablet 1 are switched one after the other, and the position indicator 2 is moved.
Of the output signals produced by the action of the loop coil and each loop coil, find the one showing the maximum output level value, use the maximum level value as a reference to determine the linear region, and operate the linear region dividing means and the division adjusting means. You can also do it. These decision or processing devices are preset in a utilization circuit 15 similar to that shown in FIG. 6 or 7.

Next, a method for determining the position of the device thus configured will be described. Now, it is assumed that the position indicator 2 exists near the center of the loop coil xi in the measurement range. First, in this case, the apparatus sequentially selects the loop coils, and measures the order of the loop coils and the output level value thereof. At this time, the maximum output level may be recognized and the linear region and the divided regions may be set. This step is similar to the conventional apparatus, except that it also detects in which divided area each of these output levels is determined previously. As shown in the lower part of FIG. 1, when the device selects the loop coil x (i-3), its output level exists in the second region of the linear region as indicated by OP2. The utilization circuit 15 of the apparatus recognizes this and stores the output level value and the loop coil rank. Similarly, when the loop coil x (i + 2) is selected, it is in the first region (OP1) of the linear region, and when the loop coil x (i + 3) is selected, it is in the third region (OP3) of the linear region. Recognize that an output level exists. At each of these recognition times, the utilization circuit 15 of the device determines the rank of each loop coil (x (i-3), x (i + 2) and x (i + 3)).
And their output level values (OP2, OP1 and OP3)
Are paired and stored in the memory. When this recognition is completed, the switching measurement operation of each loop coil is completed. In this case, if each output level value is considered as the output level at the center position of the corresponding loop coil, the output level of the virtual loop coil whose center position is the center of the position indicator 2 as shown by the thick curve in FIG. It can be seen that each is plotted on a curve.

Referring to FIG. In FIG. 2, when the center of the loop coil x (i-3) is C1, the center of the loop coil x (i + 2) is C2, and the center of the loop coil x (i + 3) is C3,
It can be said that each output level value OP1, OP2 and OP3 lies on each center C1, C2 and C3, respectively. 1 to the left of the center P1 of the position indicator 2
Two measurements can be obtained on the right side and on the right side. First, a straight line passing through the points OP2 and OP3 is calculated. Then, a point D having the same level value as the point OP1 on this straight line is obtained.
Next, the distance between OP1 and the point D is obtained. A half value of this distance represents the distance in the X direction from the center position of the loop coil x (i-3) of the position indicator 2. X of each loop coil
Since the directional position is predetermined, the X direction position of the position indicator 2 can be calculated. In this case, a second straight line that is symmetric to the first straight line passing through the two points OP2 and OP3 on the right side and that passes through the point OP1 on the left side is calculated separately, and the position indicator is calculated from the intersection position of these straight lines. You may make it calculate the existing position of 2. The position in the Y direction can be obtained by providing a plurality of loop coils sequentially arranged in the Y direction as described above and performing the same processing. The utilization circuit 15 of the device uses these X and Y
The designated coordinate value on the tablet designated by the position indicator 2 is output from the position obtained from the direction.

In the apparatus of the above-mentioned embodiment, the level value of the output signal corresponding to the position indicator and each loop coil produces the maximum level when the position indicator is present near the center of the loop coil and moves away from the center. According to the above description, the one that gradually decreases is described.
A device such as 241415, that is, a device in which the vicinity of the center of the loop coil represents the minimum output level value can be applied as long as the above two conditions are satisfied. Further, unlike the above-mentioned embodiment, the present invention can also be applied to a device in which a current is sequentially supplied to the loop coil group on the tablet surface and the induced voltage is acquired on the position indicator side. This is because in each case, the output level distribution according to the rank of the loop coil can be obtained.

[0013]

As described above, according to the present invention, regardless of whether or not the output distribution according to the loop coil rank can be approximated to a quadratic function, the position indication can be performed with an accurate and relatively simple structure. It is possible to determine the indicated position coordinates of the vessel.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a relationship between a loop coil array related to an apparatus according to an embodiment of the present invention and an output signal related thereto.

FIG. 2 is a schematic diagram for explaining an example of a position determining method of the device of FIG.

FIG. 3 is a schematic diagram for explaining the principle of the present invention.

FIG. 4 is an explanatory diagram showing a height variation of a position indicator which is one of the disadvantages of this type of digitizer.

FIG. 5 is a schematic diagram for explaining output level fluctuations due to height fluctuations of a tablet and a position indicator.

FIG. 6 is a configuration explanatory view showing a first conventional example.

FIG. 7 is an explanatory diagram of a configuration showing a second conventional example.

[Explanation of symbols]

 1: Tablet 2: Position indicator

Claims (1)

[Claims] 1. An output signal exhibits a maximum or minimum level when a position indicator is present at a position near the center of the loop coil, and the level of the output signal as the position indicator moves away from the center of the loop coil. The output signal gradually decreases or rises, and can be regarded as being at least partially linear or linearly symmetric with respect to the center of the loop coil. A tablet in which the loop coils are sequentially arranged in a predetermined direction, a position indicator positioned on the tablet, and an output signal generated by the action of the loop coils of the tablet and the position indicator. A digitizer having position calculating means for calculating the position (coordinates) of the position indicator on the tablet based on The position calculation means divides an area that can be regarded as a straight line of the output signal into at least three areas according to the level of the output signal, and a linear area division means, when the position indicator exists within the measurement range, Of the output signals produced by the action of the position indicator and the loop coils, one output signal of each of the divided at least three regions is generated so that one output signal is generated in each of the loop coils and the straight line. Division adjusting means for adjusting the relationship with the division width of the area dividing means, and a loop which, when the position indicator is present within the measurement range, produces an output signal corresponding to each of the divided at least three areas. Measuring means for measuring the order of the coils and their level values, based on the above-mentioned at least three output level values and the order of the loop coils corresponding thereto A digitizer having means for determining the existing position (coordinates) of the position indicator on the tablet.