JP3111281B2 - Coordinate reading device and its scanning method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coordinate reading device.

[Conventional technology]

2. Description of the Related Art In a coordinate reading device that electromagnetically couples a coordinate indicator and a tablet, it is known that an error occurs in coordinate detection due to an angle between a coil built in the coordinate indicator and a tablet surface.

First, the scanning method of the conventional coordinate reading device will be described with reference to FIG.

A plurality of rectangular sense lines are laid on the tablet 2 at a fixed laying pitch (sense line pitch) along the coordinate detection direction of the two-dimensional XY coordinate system. In the drawing, the horizontal direction is the X direction, the vertical direction is the Y direction, and the sense lines whose long sides are arranged in the Y direction in the X direction are Y sense lines, and the sense lines whose long sides are arranged in the X direction in the Y direction are shown. Called X sense line.

Reference numeral 1 denotes a coordinate indicator for indicating a reading position on the tablet 2. The coordinate indicator 1 has a coil (not shown) therein, and induces an induction signal on the sense line by electromagnetically coupling with the sense line.

The sense lines are selected one by one according to an instruction signal given from a control circuit (not shown). One of the X and Y sense lines generates an AC magnetic field, and the other sense line generates electromagnetic induction with the coordinate indicator 1. To derive an induction signal based on The control circuit selectively scans the sense line,
The guidance signal is input, and the coordinates of the position indicated by the coordinate indicator 1 are calculated based on the guidance signal.

In such a coordinate reading device that scans the sense lines, when the coordinate indicator enters the reading range from outside the reading range, all the sense lines are first detected in order to detect the presence of the coordinate indicator. Scan. Then, when the presence of the coordinate indicator is detected by this scanning, thereafter, only the sense lines in a narrow range near the present position are scanned, and this is repeated at a constant cycle.

An example of the scanning process will be specifically described. First, the control circuit determines a 9 × 9 area to be scanned this time around the position of the coordinate indicator detected in the previous one-cycle scanning.
Then, first, the lowermost Y sense line in which the black rectangular areas are arranged is selected. In this state, the control circuit sequentially selects nine X sense lines. Therefore, one Y sense line and one X sense line are simultaneously selected at a time. The area where the two sense lines intersect is shown as a black rectangular area.

If a coordinate indicator is placed on this intersection area, electromagnetic coupling occurs between the coordinate indicator and the AC magnetic field generated from one of the sense lines, and an induction signal is induced on the other sense line. If this processing is repeated for the nine sense lines in the Y direction, an induced signal is observed in the 9 × 9 area. Then, coordinates are calculated based on the guidance signal input here.

Another type of coordinate reading device generates a magnetic field from a coordinate indicator, induces a guidance signal along with an X direction sense line and a Y direction sense line, and detects coordinates independently in the X direction and the Y direction. is there. In this case, nine sense lines are scanned in the X direction and the Y direction, respectively, centering on the position of the previously detected coordinate indicator, and guidance signals guided to each sense line are input.

Next, referring to FIG. 3 and FIG. 4, in the coordinate reading apparatus of the system for scanning the sense lines as described above,
The coordinate detection error due to the inclination will be briefly described. Third
FIGS. 4 and 5 show a sense line 3 for inducing an induction signal.
And a relation between the induced signal and the position of the sense line.

FIG. 3 shows the coil position and the induced voltage when the coordinate indicator is perpendicular to the tablet surface. The designated position 8 designated by the coordinate indicator is located at the center of the coil 7.
Since the coil is located at the center of the second sense line 3, the voltages induced in the first and third sense lines 3 are equal. FIG. 4 shows a case where the coordinate indicator is inclined with respect to the tablet surface.
Is not at the center of the coil 7. Coil 7
Is located between the second and third sense lines 3, the voltages induced in the first and third sense lines 3 are not equal. Therefore, when the coordinate indicator is tilted, an error occurs in which the coordinate value moves in a direction in which the coordinate indicator is tilted from the position actually pointed.

As a method for correcting this error, there is a method using a secondary peak. The correction method will be briefly described with reference to FIG. FIG. 5A 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 in the vicinity of the coordinate indicator, but a local maximum value (secondary peak) having a smaller amplitude than the peak is also generated in the surrounding area. 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. FIG. 5B is a distribution diagram of the induced voltage when the coordinate indicator is inclined with respect to the tablet surface. When the coordinate indicator is tilted, the secondary peak on the tilted side increases and the secondary peak on the opposite side decreases. The difference due to the inclination is corrected using the difference between the secondary peaks on both sides.

In order to read the secondary peak, the conventional coordinate reading device scans a square area sense line including an area where the secondary peak can be detected as shown in FIG. 6, and reads the secondary peak.

[Problems to be solved by the invention]

In the conventional method of scanning the sense lines in the square area including the area from which the secondary peak can be read, the number of sense lines to be scanned is large. Accordingly, a long processing time for detecting one coordinate is required.

Accordingly, it is an object of the present invention to perform scanning only for a coordinate calculation area and a secondary peak detection area which are required at a minimum, omit scanning of an extra sense line, and perform scanning for coordinate detection at a high speed.

[Means for solving the problem]

In order to solve the above problem, in a first configuration of a scanning method according to the present invention, a coordinate indicator for indicating a coordinate reading point, and a plurality of sense lines electromagnetically coupled to the coordinate indicator are arranged in a coordinate detection direction. A coordinate reading device connected to the plurality of sense lines, the scanning unit selectively scanning the sense lines in accordance with an instruction, and a control unit instructing the scan unit to select a sense line to be selected. In the scanning process, a plurality of sense lines required for coordinate calculation are selectively scanned around a position near the position where the coordinate indicator is present, and a guidance signal guided to the plurality of sense lines is input with the selective scanning. And a peak detection for obtaining a position of a latest peak detection sense line at a position where the coordinate indicator is present, based on the guide signal input by the scanning process. Output processing; a secondary peak detection position determination processing for obtaining a sense line position at which a secondary peak induction signal is generated based on the peak detection sense line position obtained by the peak detection processing; and a secondary peak detection position determination And a secondary peak detection process for inputting a secondary peak induction signal to the scanning unit by applying the sense line position obtained by the process to realize the scanning method of the coordinate reading device.

Further, as a second configuration, in the first configuration,
In the peak detection processing, a position of a peak detection sense line may be obtained by detecting a peak guidance signal that is a maximum guidance signal among guidance signals input by the scanning processing.

As a third configuration, in the first or second configuration, in the secondary peak detection position determination processing, the positions of a plurality of adjacent sense lines near the position where the secondary peak occurs are determined. In the detection processing, a plurality of sense line positions determined by the secondary peak detection position determination processing are given to the scanning unit, and a guide signal guided to the selected plurality of sense lines is input. The next peak may be detected.

As a fourth configuration, in the third configuration,
The plurality of adjacent sense lines near the position where the secondary peak occurs may be two sense lines.

Further, as a fifth configuration, in the third or fourth configuration, the secondary peak detection processing detects the largest one of the plurality of guidance signals input at each position as a secondary peak. You may.

Further, as sixth to eighth configurations, the first
In the fifth to fifth configurations, the tilt angle information of the coordinate indicator may be further obtained based on the secondary peak, and the coordinate value of the position indicated by the coordinate indicator may be corrected based on the tilt angle information. It may be. Further, in obtaining the tilt angle information based on the secondary peak, the tilt angle information can be obtained based on the component of the difference between the secondary peaks.

Further, in the first configuration of the coordinate reading device according to the present invention, a coordinate indicator for designating a coordinate reading point and a plurality of sense lines electromagnetically coupled to the coordinate indicator are laid along the coordinate detection direction. A coordinate reading device, comprising: a tablet; a scanning unit connected to the plurality of sense lines, for selectively scanning the sense line according to an instruction; and a control unit for instructing the scanning unit to select a sense line to be selected. The coordinate reading device is configured to execute the scanning method based on the first to fifth configurations.

In the second configuration of the coordinate reading device according to the present invention, a coordinate indicator for indicating a coordinate reading point and a plurality of sense lines electromagnetically coupled to the coordinate indicator are laid along the coordinate detection direction. A coordinate reading device, comprising: a tablet; a scanning unit connected to the plurality of sense lines, for selectively scanning the sense line according to an instruction; and a control unit for instructing the scanning unit to select a sense line to be selected. The coordinate reading device is configured by executing the scanning method based on the sixth to eighth configurations and further providing a unit for outputting tilt angle information to the outside.

[Action]

In the coordinate reading device configured as described above, the peak detection processing obtains the peak detection sense line position closest to the position where the coordinate indicator is present, based on the guidance signal input by the scanning processing. In the determination processing, a secondary peak detection position is obtained based on the peak detection sense line position obtained by the peak detection processing. The secondary peak detection process scans the sense line near the secondary peak based on the secondary peak detection position and inputs the secondary peak.

Therefore, in order to input a secondary peak, unnecessary sense lines are not scanned, and only the minimum number of sense lines are scanned. Therefore, scanning for coordinate detection can be performed at high speed.

Further, since the secondary peak detected in this way has information on the tilt angle of the coordinate indicator, the tilt angle information of the coordinate indicator can be calculated based on the secondary peak, and further, the tilt angle can be calculated. Based on the information, the inclination error based on the inclination of the coordinate indicator of the coordinate value can be corrected. The tilt angle information can be output to the outside by an output unit.

〔Example〕

Hereinafter, embodiments of a coordinate reading device according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a coordinate reading device according to the present invention. Like the conventional coordinate reading device, the tablet 2 is provided along the coordinate detection direction of the two-dimensional XY coordinate system.
A plurality of rectangular sense lines 3 are laid at a constant laying pitch (sense line pitch). In the figure, the horizontal direction is the X direction and the vertical direction is the Y direction. The sense lines whose long sides are arranged in the Y direction in the X direction are Y sense lines, and the sense lines whose long sides are arranged in the X direction in the Y direction. X sense line.

1 is a coordinate indicator having a coil (not shown) inside,
The induction signal is induced in the sense line 3 by electromagnetically coupling with the sense line 3.

The sense line 3 is connected to the scanning unit 4. The scanning unit 4 is also connected to the control unit 5, selects a sense line specified by the control unit 5, inputs a guidance signal guided to the sense line, and outputs the guidance signal to the control unit 5. The scanning unit connected to the X sense lines is called an X scanning unit, and the scanning unit connected to the Y sense lines is called a Y scanning unit. Note that, depending on the configuration, an excitation circuit that supplies an excitation signal for generating an AC magnetic field on the sense line may be connected to the scanning unit.

The control unit 5 outputs the signal for selecting the sense line 3 to the scanning unit 4 as described above, and inputs the guide signal, and based on the guide signal, the coordinates of the position indicated by the coordinate indicator 1; Calculate the inclination of the coordinate indicator.

The present invention is based on electromagnetic induction as described above,
The present invention can be implemented in a coordinate reading apparatus that scans a plurality of sense lines.

The processing in the control unit 5 is as shown in the schematic flowchart of FIG. As shown in the figure, the processing of the control unit 5 is composed of a scanning processing s1, a peak detection processing s2, a secondary peak detection position determination processing s3, and a secondary peak detection processing s4. Hereinafter, each process will be described.

(Scanning process s1) In the scanning process s1, like the conventional coordinate reading device,
When the presence of the coordinate indicator is detected within the reading range, only the sense lines in a narrow range near the present position are scanned. An n × n (five in this embodiment) n × n sense lines on one axis are scanned around the peak detection sense line position detected last time, and an induced signal is input to each sense line.

The range of five lines is a range necessary for calculating coordinate values. In the conventional coordinate reading apparatus, nine ranges are scanned, but this is to include up to the secondary peak. The range required to calculate the coordinate values is a design item determined in consideration of the method of calculating the coordinate and the followability to the movement when the coordinate indicator moves on the tablet. Although the number is not limited to five as described above, in any case, for the purpose of the present invention, the range must be narrower than the range including the secondary peak.

The Y scanning unit and the X scanning unit sequentially select a Y sense line and an X sense line, as in the conventional coordinate reading device. The rectangular area blacked out in FIG. 1 is the intersection area of the two selected X and Y sense lines. If a coordinate indicator is placed on the intersection area and, for example, an alternating magnetic field is generated from one of the sense lines and electromagnetically coupled to the coordinate indicator, an induction signal is induced on the other sense line.
If this process is repeated for the five sense lines in both the X and Y directions, an induced signal is observed in the 5 × 5 region. The guidance signal input here is used for coordinate calculation.

In a coordinate reading device that generates a magnetic field from a coordinate indicator, the X direction and the Y direction can be detected independently. In this case, the peak detection sense line detected last time is used in each of the X direction and the Y direction. What is necessary is to scan n sense lines centering on the position, and to input an induced signal to each sense line.

(Peak Detection Processing s2) Next, in the peak detection processing s2, the peak detection sense line positions Pax and Pay that read the maximum value from the induced voltages of the rectangular area (n × n) read by the scanning processing s1 are determined. Ask. Here, Pax indicates a sense line position in the X direction, and Pay indicates a sense line position in the Y direction. Hereinafter, similarly, the notation such as the position of the sense line is in a two-dimensional coordinate system.

(Secondary peak detection position determination processing s3) Next, in the secondary peak detection position determination processing s3, the peak detection sense line position (Pax, Pay) obtained by the peak detection processing s2 and the distance substantially constant from this position are determined. A sense line position where a secondary peak is expected is determined based on a predicted secondary peak appearance distance.

The position at which the appearance of the secondary peak is expected is determined by the sense line pitch, the coil diameter of the coordinate indicator 1, the height from the sense line 3 to the coil, and the inclination of the coordinate indicator, and can be obtained by experiment. . At this time, since the sense lines exist only discretely at every sense line pitch, the expected position is generally between two sense lines.

In this embodiment, the sense line pitch is 6.35 mm and the coil diameter is
Since the height from the sense line to the coil was 4.5 mm, the expected secondary peak appearance distance was expressed as the number of sense lines from the peak detection sense line position, and Po1 = 3, P
o2 = 4. According to experiments, the secondary peak is located two distances away from the peak detection sense line position,
That is, it was confirmed that the sense line was included in the third or fourth sense line. The equation for finding the position of the sense line where the secondary peak exists is as follows.

a1 = (Pax + Po1, Pay) a2 = (Pax + Po2, Pay) a3 = (Pax-Po1, Pay) a4 = (Pax-Po2, Pay) a5 = (Pax, Pay + Po1) a6 = (Pax, Pay + Po2) a7 = (Pax) , Pay-Po1) a8 = (Pax, Pay-Po2) Here, am (m = 1 to 8) is a code for indicating each sense line position. The control unit 5 calculates the detection position of the secondary peak by calculating this equation.

(Secondary peak detection processing s4) Next, in the secondary peak detection processing s4, the sense line position am (m = 1 to m) obtained in the secondary peak detection position determination processing s3.
8) to the sequential scanning unit 4 to input the voltages vm (m = 1 to 8) induced at the respective sense line positions. The input voltage value vm is calculated for each adjacent detection position (a1 and a
2, a3 and a4, a5 and a6, a7 and a8) voltage values (v1 and v2, v3
And v4, v5 and v6, v7 and v8), and the larger voltage value is adopted as the secondary peak.

Now, the time required for scanning will be shown in comparison with a conventional coordinate reading device. The scanning time per sense line varies depending on the frequency characteristics of the circuit for processing the induction signal, the conditions for digital processing, and the like.
The description will be made assuming that about 0 μsec to 200 μsec is required.

In the conventional coordinate reading device, 9 × 9 =
Since 81 scans are performed, the required scanning time is 1215
0 μsec to 16200 μsec were required. On the other hand, in the coordinate reading apparatus according to the present invention, 5 × 5 + 8 = 33 scans are required, and the required scan time is reduced from 4950 μsec to 6600 μsec.

In the above-described embodiment, the case where the position where the appearance of the secondary peak is expected is assumed to be one of the two adjacent sense lines has been described. When the allowable tilt angle is increased, the appearance position of the secondary peak may extend over three sense lines. In such a case, 2
In the next peak detection position determination process s3, three sense lines may be selected. Conversely, if the allowable tilt angle is reduced, the secondary peak may be observed with one sense line. In such a case, it is apparent that one sense line should be selected in the secondary peak detection position determination processing s3.

To reiterate, the scanning range for detecting the secondary peak varies depending on the above conditions, so that an experiment may be performed for each condition and set based on the information obtained from the experiment.

The secondary peak detected in this manner has information on the tilt angle of the coordinate indicator. Thus, for example, 2
Using the difference between the next peaks, the inclination angle information of the coordinate indicator can be obtained from this. If there is an error in the coordinate value of the indicated position due to the inclination of the coordinate indicator, the error can be corrected based on the inclination angle information obtained from the secondary peak. In some cases, the tilt angle information may be output to an external device together with the coordinate values so that the external device can use the information.

〔The invention's effect〕

As described above, according to the present invention, the secondary peak appearance position is obtained from the coordinate value detected by the coordinate detection unit, and scanning is performed only on the minimum sense lines required for coordinate calculation and inclination correction, so that high-speed coordinate detection can be performed.

[Brief description of the drawings]

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 a coordinate detection error due to the inclination of the coordinate indicator, and FIG. 5 is an induced voltage due to the inclination of the coordinate indicator. Induced voltage distribution diagram explaining the distribution change of
FIG. 6 is an explanatory diagram of the sense line scanning by the conventional scanning method. 1 Coordinate indicator 2 Tablet 3 Sense line 4 Scanning unit 5 Control unit 6 Sense line scanning range s1 Peak detection processing s2 Secondary peak detection position determination processing s3 ... Secondary peak detection processing

Claims (10)

(57) [Claims] 1. a) a coordinate indicator for designating a coordinate reading point; b) a tablet having a plurality of sense lines electromagnetically coupled to the coordinate indicator laid along a coordinate detection direction; A coordinate reading device connected to a plurality of sense lines and selectively scanning the sense line according to an instruction; and d) a control unit for instructing the scan unit to select a sense line to be selected. A scanning process of selectively scanning a plurality of sense lines required for coordinate calculation around the position where the indicator is present, and inputting a guidance signal guided to the plurality of sense lines with the selective scanning; f) A peak detection process for obtaining a position of a latest peak detection sense line at a position where the coordinate indicator is present, based on the guidance signal input by the scanning process; and g) detecting the peak. A secondary peak detection position for finding at least two sense line positions at a predetermined distance along the coordinate detection direction from the position of the peak detection sense line determined by the processing and at which a secondary peak induction signal is generated. Determination processing; h) providing the at least two sense line positions determined by the secondary peak detection position determination processing to the scanning unit, and presenting before and after the peak detection sense line along a coordinate detection direction; A secondary peak detection process of inputting a guidance signal of a secondary peak having a maximum amplitude at each position. 2. The peak detecting process according to claim 1, wherein a peak guiding signal which is a maximum guiding signal is detected from the guiding signals input by said scanning process, and a position of a peak detecting sense line is obtained. Item 4. A scanning method of the coordinate reading device according to Item 1. 3. The secondary peak detection position determining process determines a position of a plurality of adjacent sense lines near a position where a secondary peak induction signal is generated based on the position of the sense line obtained by the peak detection process. The secondary peak detection process includes: providing the plurality of sense line positions determined by the secondary peak detection position determination process to the scanning unit; and inputting a guidance signal guided to the selected plurality of sense lines. 3. A scanning method for a coordinate reading device according to claim 1, wherein a secondary peak is detected based on these induction signals. 4. A plurality of adjacent sense lines near a position where a secondary peak occurs are two adjacent sense lines near a position where a secondary peak occurs. Scanning method of the coordinate reading device. 5. The secondary peak detecting process according to claim 3, wherein a maximum guide signal is detected as a secondary peak among a plurality of guide signals input at each position. Scanning method of the coordinate reading device. 6. The scanning of the coordinate reading apparatus according to claim 1, further comprising an inclination angle calculating process for obtaining information on an inclination angle of said coordinate indicator with respect to said tablet based on said secondary peak. Method. 7. A tilt angle calculating process for obtaining tilt angle information of the coordinate indicator with respect to the tablet based on the secondary peak, and based on tilt angle information obtained by the tilt angle calculating process.
6. The scanning method of the coordinate reading device according to claim 1, further comprising: a tilt error correction process for correcting a coordinate value of a position indicated by the coordinate indicator. 8. The tilt angle calculating process according to claim 6, wherein tilt angle information of the coordinate indicator with respect to the tablet is obtained based on a component of the difference between the secondary peaks. The scanning method of the coordinate reading device. 9. A tablet comprising: a) a coordinate indicator for designating a coordinate reading point; b) a tablet on which a plurality of sense lines electromagnetically coupled to the coordinate indicator are laid along a coordinate detection direction; A coordinate reading device that is connected to a plurality of sense lines and selectively scans the sense line according to an instruction; and d) a control unit that instructs the scan unit to select a sense line to be selected. A coordinate reading apparatus for executing a process based on the scanning method according to any one of claims 1 to 5. 10. A tablet comprising: a) a coordinate indicator for designating a coordinate reading point; b) a tablet having a plurality of sense lines electromagnetically coupled to the coordinate indicator laid along a coordinate detection direction; A coordinate reading device that is connected to a plurality of sense lines and selectively scans the sense line according to an instruction; and d) a control unit that instructs the scan unit to select a sense line to be selected. 9. A coordinate reading apparatus, comprising: f) means for executing processing based on the scanning method according to claim 6; and f) outputting the tilt angle information to an external device.