JPS6299824A - Error correcting method for coordinate reading device - Google Patents

Abstract

PURPOSE:To detect a coordinate position with high accuracy by calculating position information and tilt information from the voltage induced on each sense line from a coordinate detecting unit and correcting an error produced by positions and tilts of a coordinate indicator and the sense line. CONSTITUTION:The voltage induced on the sense lines are supplied to a CPU 3 from a coordinate unit 1 consisting of those sense lines, a scan circuit, an interface, etc. Then the CPU 3 calculates the position information with (Vpx-Vp-1x)/(Vpx+Vp+1x)=Q and based on those voltages Vp, V+px and V-px induced on the sense lines and the voltages induced at the periphery of these sense lines. Furthermore the CPU 3 calculates the tilt information on a coordinate indicator from (V-px+V-px-1+V-px-2)/(V+px+V+px+1+V+p-x+2)=R. Thus the CPU 3 calculates the accurate coordinate value from the data on a correcting circuit 7 and a ROM table 4 and delivers it to an external device 6 of a CAD system, etc. via an I/F 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coordinate reading device using induced electromotive force, and more particularly to a coordinate reading device equipped with means for correcting errors caused by the tilt of a coordinate indicator.

[Summary of the invention]

The present invention calculates the reading error when the coordinate indicator is tilted from the voltage induced in each sense line from the coordinate detection unit, calculates position information, tilt information, and error information, and calculates the reading error when the coordinate indicator is tilted. Highly accurate position detection is performed by correcting errors caused by the position with respect to the sense line and errors caused by the tilt of the coordinate indicator.

[Conventional technology]

Conventionally 9 As a correction means when an operator tilts the coordinate indicator to input when reading graphical information such as a drawing etc. 9 The present applicant published Japanese Patent Publication No. 59-35069 as a position correction means, as a tilt correction means. Japanese Patent Publication No. 59-20156 has been proposed.

[Problem that the invention seeks to solve]

There is a close relationship between the position of the coordinate indicator and the voltage induced in the sense line, and when the coordinate indicator is tilted, the voltage induced in the sense line is equal to the voltage induced in the sense line even if the tilt is constant. It changes depending on the position. Therefore, the method previously proposed by the two applicants was insufficient for accurate orthographic calculation.

Furthermore, if the distance between the sense lines becomes wider,
As the induced voltage becomes smaller and the S/N ratio deteriorates, calculation accuracy also deteriorates, and there is a possibility that accurate correction cannot be performed.

[Means for solving problems]

In order to solve the above problems, the present invention calculates the positional information of the sense line and the coordinate indicator and the weighting of the error amount due to the inclination of the coordinate indicator based on this position information. It is now possible to perform accurate correction by multiplying the amount of inclination.

[Effect]

The position information of the coordinate indicator is subtracted from the first ROM table, and the third ROM table is subtracted from the result of this first ROM table and held as error information. This error information is multiplied by the result of the second ROM table that holds the tilt information of the coordinate indicator.

At this time, the second ROM table is drawn using the sum of the secondary peak and a plurality of voltages induced around this peak. Through the above processing, an accurate error amount is calculated, and the first
Correction was performed by adding or subtracting an error amount to the position information that is the result of the ROM table.

〔Example〕

Hereinafter, nine embodiments of the present invention will be described based on the drawings and the like.

FIG. 1 is a schematic diagram showing the configuration of the present invention. From the coordinate detection unit 1, which is composed of a sense line, a scanning circuit, an interface, etc., a voltage induced to the sense line as shown in FIG. 3 is generated. (Beak Vpx, secondary peak V+px, v-pz) and other voltages induced in each sense line are input to the CPU 3. This CPU3 receives Vp, V+px, and V- induced by the sense line.
Based on the voltage induced at and around px, (Vpx −
The position information is calculated by Vp-1x)/(vpx+vp+1x)-Q. The details are described in Japanese Patent Publication No. 59-35069 and will therefore be omitted.

Furthermore, CPU3 is (V-px + V-pX-1+
V −px−2) / (V+px + V+px+1
+ V + px + 2 ) ” H calculates the tilt information of the coordinate indicator 2 In the present invention, the sum of the voltages induced near the secondary peak is used as data to improve the S/N when calculating the tilt information. However, the basic concept is described in Japanese Patent Publication No. 59-20156, so it will be omitted here.The correction circuit 7, as shown in FIG. It changes depending on the position of the coil 15 of the device (Vpx −Vp−Lx) /
(Vpx +Vp+1: )-Q is corrected. As shown in Fig. 6, which shows the change in the calculation result due to the slope of Q, when it is tilted in one direction, C
2 It has been found through experiments that when tilted in the opposite direction to the child direction, the calculation result has a curve like b. Therefore, in the correction circuit 7, the amount of deviation of the calculation result that changes depending on the slope is calculated using experimental values, and the weighting of the error amount corresponding to the correction straight line as shown in FIG. 7 is stored in the third ROM table. . This correction straight line changes depending on the installation conditions of the sense line. ROM table 4 is.

1st. It consists of a second ROM table.

Then, the CPU 3 calculates accurate coordinate values based on the data from the correction circuit 7 and the memory circuit 4, and calculates the correct coordinate values via the I/F.
Output to external equipment such as a system.

Focusing on Figure 2, Section 5. 6th. A case in which the coordinate indicator is tilted in one direction of X will be specifically explained using FIG. The CPU 3 calculates the Q value based on the voltage induced in the sense line, but for convenience, if the Q value is 0.5, as can be seen in Figure 6, the position information in the first ROM table is Since it has a value expressed by a curve, it holds position information from ■ to ■. At this time, a third ROM table O (seventh
) is also referenced at the same time, and the value of the error amount ratio ■ is held as position information within one pitch. Furthermore, the CPU 3 also calculates the R value and calculates the second R value having the value represented by the curve shown in FIG.
The direction and amount of inclination are calculated using the OM table, but in this case as well, since the R value is set to 05 for convenience, 36 degrees is calculated, and a value corresponding to -36 degrees is held as the inclination information. As a result of the above, in order to actually correct the curve of the Q value that has changed like the curve C (Figure 6), the slope information is multiplied by the value of the error amount ratio. The correct position is calculated by performing correction and subtracting from the position information since the slope is -.

Although the above example has been described for the X direction, the same can be obtained for the Y direction as well.

〔Effect of the invention〕

According to the present invention, it is possible to appropriately correct both the position error due to the relative position of the coordinate indicator and the sense line and the calculated coordinate error due to the tilt of the coordinate indicator, so that more accurate position detection is possible. became.

Furthermore, since the R value was calculated by the sum of multiple values in the vicinity of the secondary peak, the S/N could also be improved.

The effect based on actual measurements is shown in FIG. 8, and an improvement of about 1000 μm was observed when the inclination angle of the coordinate indicator was 145 degrees.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of the present invention. FIG. 2 is a 70-chart showing the operation. FIG. 3 is a schematic diagram of voltages induced in each sense line obtained by the coordinate detection unit. FIG. 4 is a diagram showing the positional relationship between the sense line and the coil of the coordinate indicator. Figures 5, 6 and 7
The figure shows the second ROM, the first (7) ROM, and the third ROM.
OM+7) Contents 3...CPU 4...ROM table 15...Coil and above Applicant Seiko Electronics Industries Co., Ltd. Agent Patent attorney Tsutomu Mogami (and 1 other person) Mizohiro Group 7 Figure 1 Masterpiece Show Flow Nazoot No.? Figure & 1 S-bone conduction 'In, (One-way cross-section Figure 3 Q99 ℃ Wind-up roof') A relation Figure 4 Contents of 3rd RO-

Claims (1)

[Claims] (a) A coordinate detection unit formed by laying a plurality of sense lines; (b) A coordinate indicator comprising a coil having means for generating an alternating magnetic field and detecting a position on the tablet. (c) a CPU that calculates position and tilt information based on the voltage induced in the sense line; (d) a ROM table that stores data corresponding to coordinate positions based on the position and tilt information; and (e) coordinates. A method for correcting errors in a coordinate reading device, comprising: another ROM table storing data for correcting positional information caused by tilting of an indicator.