JPH0424720A - Scanning system for coordinate reader - Google Patents

Abstract

PURPOSE:To make correction amount resolution for inclination correction fine by amplifying a second-order peak by increasing gain in the case of second-order peak detection for a fixed amount, and increasing the information amount of the second-order peak. CONSTITUTION:A control part 6 selects a sense line in a rectangular area with a sense position, where a coordinate indicator 1 exists, as a center and executes a scan processing for reading an inductive voltage, peak detection processing for calculating the sense line position of the peak detection and second-order peak detection position decision processing for calculating the position where the second-order peak is generated. On the other hand, an amplification control processing is executed for applying an instruction to an amplifier 5 so as to increase the gain for the fixed amount in order to amplify the induced voltage, and a second-order peak detection processing is executed to read the second- order peak amplified by the amplification processing while applying the calculated sense line position. Thus, an absolute amount is enlarged in the difference of the second-order peak, and the correction resolution for correcting inclination can be made fine.

Description

[Detailed description of the invention] C Industrial application field] The present invention relates to a coordinate reading device.

[Prior Art] In a coordinate reading device that electromagnetically couples a coordinate indicator and a tablet, it is known that errors occur in coordinate detection due to the angle formed between the coil built into the coordinate indicator and the tablet surface. There is.

Coordinate detection errors due to inclination will be briefly explained with reference to FIGS. 3 and 4. FIG. 3 shows the coil position and induced voltage when the coordinate indicator is perpendicular to the tablet surface. The indicated position 8 indicated by the coordinate indicator is located at the center of the coil 7. Since the coil is located at the center of the second grain of the sense line 3, the voltages induced in the first grain and the third grain of the sense line 3 are equal. FIG. 4 shows a case where the coordinate indicator is tilted with respect to the tablet surface, and as in FIG. 3, it indicates the indicated position 8, but it is not at the center of the coil 7. Since the coil 7 is located between the second and third grains of the sense line 3, the voltages induced in the sense 547301 grain and the third grain are not equal. Therefore, when the coordinate indicator is tilted, an error occurs in which the coordinate values move in the direction in which the coordinate indicator is tilted rather than the actually indicated position.

One method for correcting this error is to use a secondary peak. The correction method will be briefly explained using the 51st section. Fifth
Figure (al) is a distribution diagram of the induced voltage when the coordinate indicator is perpendicular to the tablet surface. As shown in the figure, the maximum induced voltage is generated near the coordinate indicator, but it is also below the peak in the surrounding area. A local maximum value (secondary peak) with a small amplitude occurs.

This is due to the negative phase component of the coil.

If the coordinate indicator is vertical, the secondary peaks on both sides are equal. Figure 5 (bl is a distribution diagram of induced voltage when the coordinate indicator is tilted with respect to the tablet surface. When the coordinate indicator is tilted, the secondary peak on the tilted side becomes larger, and the opposite The secondary peaks on both sides become smaller.If the secondary peaks on both sides are each pipr, the difference between the secondary peaks is ag=abs (pl pr).

If the error amount in the case of the coordinate indicator's head is X is xa, and the difference between the secondary peaks is agx, the correction resolution is cons t-"
It becomes Xa+agX.

The correction amount cal due to the difference in secondary peaks is determined from the following equation.

cal=agXconst In this way, the difference between the secondary peaks on both sides is used to correct the error due to the slope.

Conventional coordinate reading devices read out the secondary peak by amplifying it at the same gain level as the peak.

[Problems to be Solved by the Invention] In the conventional method of reading out a secondary peak amplified with the same gain as the peak, the amplitude of the read out secondary peak was small. Therefore, the absolute amount of the difference between the secondary peaks is small,
The correction resolution became large, making it impossible to perform delicate corrections.

Therefore, the present invention amplifies the induced voltage at the secondary peak detection position by increasing it by a certain amount higher than the peak detection gain, thereby increasing the absolute amount of the difference between the secondary peaks, thereby performing correction for correcting the slope. The purpose was to improve the resolution.

[Means for Solving the Problems 2] In order to solve the above problems, the present invention provides a coordinate indicator that indicates a coordinate reading point, a tablet that is electromagnetically coupled to the coordinate indicator, and a sense line installed on the tablet. a scanning section that selects one sense line at a time and reads out the voltage induced in the sense line; an amplifier that amplifies the induced voltage read out by the scanning section; In a coordinate reading device that includes a control section that controls gain, the control section selects a sense line in a rectangular area centered on the sense line position where the coordinate indicator is present, and performs a scanning operation that reads the induced voltage. 2. Processing, peak detection processing to find the peak detection sense line position where the peak was detected within the rectangular area, and peak detection sense line position obtained by the peak detection processing.
The determination process is performed at the secondary peak detection position to determine the position where the next peak occurs, and the amplifier is used to increase the gain by a certain amount in order to amplify the voltage induced at the sense line position determined by the secondary peak detection position determination process. An amplification control process for giving an instruction, and a secondary peak detection process for giving the scanning section the sense line position determined by the secondary peak position determination means and reading the secondary peak amplified by the amplification process.

[Effect]

In the coordinate reading device configured as described above, a minimum number of sense lines are scanned to calculate coordinates by scanning processing, and voltages induced in the sense lines are read out. In the peak detection process, the position of the peak detection sense line where the largest voltage is read out of the induced voltages read out by the scanning process is determined. The secondary peak position determination process determines a secondary peak detection position based on the peak detection sense line position determined by the peak detection process. The amplification control process instructs the amplifier to increase the gain by a certain amount in order to amplify the voltage induced at the sense line position determined by the secondary peak detection position determination process. The sense line position determined by the determining means is given to the scanning section, and the secondary peak amplified by the amplification control process is read. In this way, since the information amount of the secondary peak is increased, the correction resolution of the slope can be made finer.

〔Example〕

Embodiments of the coordinate reading device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a coordinate reading device according to the present invention. The scanning unit 4 scans the sense line 3 instructed by the control unit 6.
is selected, and the voltage induced by the coordinate indicator] is taken in and passed through the amplifier 5 to the control unit 6. Each process within the control section 6 will be explained with reference to the flowchart in FIG. FIG. 2 is a schematic flowchart of the control unit, and the present invention is realized by five processes: scanning process s1, peak detection process S2, secondary peak detection position determination process s3, amplification control process S4, and secondary peak detection process S5. are doing.

(Scanning Process 31) In the scanning process s1, zero lines (in this example, five lines) of nx on one axis are centered around the previously detected peak detection sense line position.
n sense lines are scanned and the voltage induced on each sense line is read.

(Peak Detection Process s2) The peak detection process s2 determines the peak detection sense line positions pax and Pay from which the maximum value is read out of the induced voltages in the rectangular area (nXn) read by the scanning process s1.

(Secondary peak detection position determination process 53) The secondary peak detection position determination process s3 is the peak detection process s
The peak detection sense line position Pa determined by 2
Secondary peak appearance positions Pal and Po2 located at a certain distance from x, , Pay and Pax, , Pay by experiment
Find the sense line position where the secondary peak exists. In this example, the sense line pi is 6.35 mm,
Coil diameter 5mm, height from sense line to coil 4
．． 5 mm, Po1=3, Po2-4.

According to experiments, it has been confirmed that the secondary peak is included in these two ranges. The second method for finding the sense line position where the secondary peak exists is as follows.

al= (Pax+Pol, Pay) a 2= (Pa x+Po 2. Pay) a3=
(Pax-Po1.Pay) a4-(Pax-Po2.Pay) a5= (Pax, Pay+Po1) a6= (Pax, Pay+Po2) a7= (Pax, Pay-Pot) a8= (Pax, Pay-Po2) (Amplification Control processing S4) The amplification control processing s4 is a secondary peak detection position determination processing s3.
Instruct the amplifier to amplify the voltage induced at the sense line position determined by a certain amount higher than the gain when the peak was detected.

(Secondary peak detection process 55) In the secondary peak detection process S5, the sense line position determined in the secondary peak detection position determination process s3 is instructed to the sequential scanning unit, and the induced voltage is extracted. The extracted voltage values are applied to each adjacent detection position (al and a2, a3 and a4, a5 and a6
, al and a8), and the larger voltage value is adopted as the secondary peak.

FIG. 6 is an induced voltage distribution diagram, and the secondary peak 11 shown in the induced voltage distribution diagram of the device according to the present invention in FIG. It can be seen that the absolute amount of the difference between the secondary peaks is larger than that of the conventional device.

〔Effect of the invention〕

As described above, in the present invention, the gain at the time of secondary peak detection is increased by a certain amount to amplify the secondary peak, and the amount of information of the secondary peak is increased. Therefore, the absolute amount of difference between the secondary peaks becomes large, and it is necessary to correct the slope. The correction amount resolution can be made finer.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a coordinate reading device according to the present invention;
Fig. 2 is a schematic flowchart of the control unit according to the present invention, Figs. 3 and 4 are explanatory diagrams for explaining coordinate detection errors due to the inclination of the coordinate indicator, and Fig. 5 is an induced voltage due to the inclination of the coordinate indicator. FIG. 6 is a diagram showing the distribution of induced voltage in the device according to the present invention and the conventional device. 1...Coordinate indicator 2...Tablet 3...Sense line 4...Scanning unit 5...Amplifier 6...Control unit sl...Scanning process s2...Peak detection process s3...2 Next peak detection position determination process s4...Amplification control process s5...Second peak detection process and above Applicant Seiko Electronics Co., Ltd. Agent Patent attorney Takayuki Hayashi Reading the seat HI by the crossbar invention! ? 1. Block diagram of 1st circle 1. Schematic processing flowchart of 1111 part according to the present invention 1.
2nd K i death indication 1-7 position induced voltage coordinate indicator g) #JI coordinate detection error explanatory diagram (if there is an inclination) 4th [71 1st peak (" 1st peak (1 no) induced Voltage σ) 21 plot (if there is a slope h) 5th factor

Claims (1)

[Claims] A) a coordinate indicator that indicates a coordinate reading point, b) a tablet that is electromagnetically coupled to the coordinate indicator, and c) a sense line laid on the tablet that selects one by one. , a scanning unit that reads the voltage induced in the sense line; d) an amplifier that amplifies the induced voltage read out by the scanning unit; e) instructing the scanning unit which sense line to select; f) the control section selects a sense line in a rectangular area centered on the sense line position where the coordinate indicator is located, and scanning processing for reading the voltage; g) peak detection processing for determining the position of the peak detection sense line where the largest induced voltage (hereinafter referred to as peak) is detected within the rectangular area; Based on the peak detection sense line position, find the position where a signal that exists around the peak, has a maximum amplitude, and has a phase opposite to the peak (hereinafter referred to as a secondary peak) occurs.2
i) an amplification control process that instructs the amplifier to increase the gain by a certain amount in order to amplify the voltage induced at the sense line position determined by the secondary peak detection position determination process; , j) a scanning method of a coordinate reading device, comprising: a secondary peak detection process of supplying the sense line position determined by the secondary peak position determination means to the scanning unit and reading the secondary peak amplified by the amplification control process; .