JPH0440512A - Coordinate reader - Google Patents

Abstract

PURPOSE:To precisely read a coordinate even if an input pen is inclined and use by providing two circuits incorporated to the input pen and arranging one circuit on the axial direction of the input pen and in a position at a first distance from the tip of the pen, and the other circuit on the same axial direction and in a position at a second distance from one circuit. CONSTITUTION:A first circuit 23 embedded crosswise in a read table and at least two second circuits 27 incorporated to the input pen 24 are provided. One circuit 28 is arranged on the axial direction 30 of the input pen and in the position at the first distance from the tip 25 of the pen, and the other circuit 29 on the same axial direction 30 and in the position at the second distance from one circuit 28. Then, a first coordinate P1 recognized between one circuit, 28 and the first circuit 23, a second coordinate P2 recognized between the other circuit 29 and the first circuit 23 and the coordinate P4 of the tip of the pen based on the first and second distances are obtained. Thus, the coordinate can precisely be read even if the input pen is inclined and used.

Description

[Detailed Description of the Invention] C Overview] Regarding a coordinate reading device using a pen-shaped input device, the purpose of the invention is to read the coordinates with high accuracy even when the input pen is used at an angle. In the coordinate reading device that reads the coordinate position of the table surface based on changes in alternating magnetic field or capacitance between a first circuit embedded in the input pen and a second circuit installed in the input pen, the second circuit is connected to at least two circuits. Provided with one
one circuit on the axis of the input pen and the first circuit from the pen tip.
and the other circuit is arranged at a second distance from the one circuit on the same axis, and between the one circuit and the first circuit. The pen tip coordinates are determined based on the first coordinates recognized between the other circuit and the first circuit, the second coordinates recognized between the other circuit and the first circuit, and the first and second distances.

[Industrial application field]

The present invention relates to a coordinate reading device, and particularly to a coordinate reading device using a pen-type input device.

Coordinate reading devices such as tablets and digitizers are used as devices for inputting coordinates of figures, character positions, etc. into computers in real time.

These are distinguished by the size of the canilia.

In general, tablets use a pen-shaped input device, while digitizers often use a magnifying glass-shaped input device called a free-moving cursor. It reads the coordinates of that location with high accuracy.

By the way, a pen-shaped input device has the same shape as a writing instrument, so it fits easily in the hand, and is superior to a loupe-shaped input device in terms of operational feel.

[Prior Art] For example, as shown in FIG. 4, a conventional pen-type input device uses an input pen 12 that is placed at an arbitrary position on a reading table 11 in which a number of alternating current magnetic field generating lines 10 are embedded in a crosswise pattern. Place the tip of the pen on the magnetic field detection line 1 inside the pen to detect changes in the alternating magnetic field.
3, the input pen 16 can be placed at any position on a reading table 15 in which a number of electrodes 14 are buried in a cross-shaped manner, as shown in FIG. A "capacitive coupling method" is known in which the coordinates of the pen tip are read by applying the tip of the pen and detecting changes in capacitance between the electrode 17 inside the pen and the electrode 14 inside the table. In addition, among the electromagnetic induction type devices, there is also a device that is the opposite of the above, in which the magnetic field detection line is placed inside the table and the alternating current magnetic field generation line is placed inside the pen.

In either method, the tip of the input pen needs to be sharp, so a magnetic field detection line 13 (
Alternatively, electrodes 17) are arranged.

[Problem to be solved by the invention]

However, in such conventional pen-type input devices, the magnetic field detection line 13 (or electrode 17) is arranged inside the pen shaft, which is away from the pen tip, so that when the input pen is used at an angle, However, there were problems with the system, such as errors in reading the coordinates, and there were issues that needed to be resolved in terms of improving accuracy.

This will be explained with reference to FIG. Now input pen 12
When you tilt the pen at an arbitrary angle and point at an arbitrary position a on the table 11 with the pen tip, the coordinate position detected by the magnetic field detection line 13 inside the pen will be perpendicular to the table 11 through the center of the magnetic field detection line 13. The intersection point between the descending line and the surface of the table 11 is indicated. In other words, even though I intended to input the coordinates of position a, the coordinates of position A shifted by a distance d were actually input, and the distance d was
It increases in proportion to the slope of 0.

By the way, such a problem can be solved by holding the input pen perpendicular to the table surface. However, when holding a writing instrument in the hand, it is common sense that the writing instrument is tilted to some extent with respect to the surface of the paper, so such a measure is not desirable in terms of usability. Incidentally, even in the case of the capacitive coupling method, such a problem similarly occurs as shown in FIG. 7.

The present invention was made in view of these problems, and
The purpose is to be able to read coordinates with high accuracy even when using the input pen at an angle.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention provides a reading table based on a change in alternating magnetic field or capacitance between a first circuit embedded in a cross shape inside the reading table and a second circuit built in the input pen. In a coordinate reading device for reading coordinate positions on a surface, at least two of the second circuits are provided, one circuit is disposed on the axis of the input pen and at a position at a first distance from the pen tip, and the other circuit is disposed on the axis of the input pen and at a position at a first distance from the pen tip. characterized in that they are arranged on the same axis and at a position a second distance from the one circuit, and a first coordinate recognized between the one circuit and the first circuit, and the other circuit. The pen tip coordinates are determined based on the second coordinates recognized between the first circuit and the first circuit, and the first and second distances.

[Effect]

In the present invention, the distance between the first coordinate and the second coordinate (abbreviated as B) changes depending on the magnitude of the tilt of the input pen. For example, when the tilt is zero, B becomes zero; As the slope increases, B increases.

The inclination of the input pen (abbreviated as θ) is determined by cos θ−B/R, where R is the distance between one circuit and the other circuit, and this R is known (second distance).

Therefore, the pen tip coordinates are determined from θ and the first distance.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a diagram showing an embodiment of a coordinate reading device according to the present invention, and is an example applied to an electromagnetic induction system.

First, the configuration will be explained. In FIG. 1, reference numeral 20 denotes a reading table, and a large number of alternating current magnetic field generating lines 22 are buried in an intersecting manner just below the table surface 21 of the reading table 20. In addition, only the alternating current magnetic field generation lines 22 arranged in one direction are shown in the drawing.

All the alternating current magnetic field generating VAs 22 including those not shown constitute the first circuit 23 as a whole.

The input pen 24 has a second circuit 27 inside a cylindrical case 26 having a sharp pen tip 25 at the end. The other circuit 29 consists of two coil-shaped magnetic field detection wires. These two circuits 28 and 29 are both arranged so that their coil centers coincide with the axis 30 of the cylindrical case 26 passing through the pen tip 25 (the axis of the input pen), and one of the circuits 28 and 29 is the first known value from the pen tip 25.
The other circuit 29 is separated from one circuit 28 by a known second distance (hereinafter referred to as D2).

The two circuits 28 and 29 are connected to an arithmetic circuit 33 via lead wires 31 and 32, and the arithmetic circuit 33 receives signals from a control circuit (path shown) that scans the magnetic field distribution of the first circuit 23 in the x-y direction. A first calculation unit 34 that calculates the first coordinates c or less, P, ) based on the scanning signal and the reading signal from the one circuit 28; The second based on
A second calculation unit 35 that calculates coordinates (hereinafter referred to as p2), the D
a first signal generating section 36 that generates a signal representing 1, the D2
The second signal generator 37 generates a signal representing , and calculates the tilt angle (hereinafter referred to as ○) of the input pen 24 based on P2 and D2, and calculates the pen tip coordinates (hereinafter referred to as ○) based on θ, P, and , Px).

Here, Pl and P2 are the magnetic field positions when the scanning magnetic field of the table surface 21 is located directly below one circuit 28 and the other circuit 29 in the vertical direction.

In such a configuration, if the input pen 24 is held so that the axis 30 is perpendicular to the table surface 21,
Since e=Q, both coordinates (PI, P2) correctly match the pen tip coordinate Px.

On the other hand, if the pen 24 is tilted even slightly, the distance L 1 z between the two coordinates (p+, P2) will change proportionally depending on the degree of the tilt. Therefore, the pen tip coordinates PX can be calculated by, for example, the method described below.

Distance tEjfL+ between pen tip coordinate P and first coordinate P1
+ is (Scashi LXI) -ri, cosθ...
・・・・■Also, the distance L1□ between the first coordinate P1 and the second coordinate P2 is (Scashi L, □)−D2 cO3θ ・・・・・・
■Thus, D+/Dz − (Square r-x+)/(Scale 1.1□)...
■ (Vector Lx+) ・・・・・・■z)-P
z P+ ......■X -P (Vector L From the above formula ■, (vector L+z) - D2/D+X (hex i・le LX,) ......■ Therefore, PX = P+ -CDI /D2 x (pz −P
I) )・・・・・・■ It can be found.

In addition, if DI"Dz, DI -2xp+ p2...
...■, which is preferable because it can be processed using integer calculations.

As described above, according to the above embodiment, accurate pen tip coordinates Px can be obtained even when the input pen is used at an angle. For example, when applied to a digitizer with a resolution of 0.025 mm, DI- Under the condition of Dz, the error caused by the tilt of the input pen can be suppressed to below the resolution.

Also, the inclination of the input pen when an error of 0.025 mm occurs is cos
θ - 0,025 mm / 5 mm θ - 89.713 degrees, which means that when the input pen is held vertically, it can be detected only by 0.287 degrees.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may be the opposite of the above example in which the AC magnetic field generation line is placed on the input pen side and the AC magnetic field detection line is placed on the reading table side. It can be applied without any problems, and can also be applied to the "capacitive coupling method" in which the electrode 41 is placed on the reading table 40 side and the electrodes 43 and 44 are placed on the input pen 42 side, as shown in FIG. can. In this system, the electrode 41 on the side of the reading table 40 constitutes the first circuit, and the two electrodes 43, 44 on the side of the input pen 42 form the first circuit.
constitute one circuit and the other circuit, respectively, to constitute a second circuit.

Further, the present invention is particularly effective when applied to a device that also uses a liquid crystal display device as shown in FIG.

In general, the surface of the liquid crystal display device 50 is covered with a protective glass 51, and due to the influence of "parallax" due to the thickness of the glass (GT: including the thickness of the liquid crystal protective film), measurements are taken due to the tilt of the input pen 52. This is because errors tend to be larger. In this case, calculations may be performed that take into account the glass thickness (GT).

Actually, from the previous model ■～■, (vector Lx+) = DI /D2 x (vector L1□)...
・■ If the distance between the coordinates Pff (target coordinates) on the extension line of the pen tip 53 and the pen tip coordinates PX is Lax, then GT-
(Screen L3x) tanθ ...... [phase], and from the formula [phase] and the previous formula
1゜) p, - (Hel. Lx+) (Vector L++x) ・・・・・・0 Above formula ■@
From, P3=P DI /D2 X (vector L+z) GT/
(D2 X sine)× (vector L, 2) −p, −(DI /D2) +GT/ (D2 ((Scashi L12) /I)z ]・
...[phase].

Also, if D+=Dz, P3=P.

El +GT/ (D2 XS i ne)
] FIG. 7 is a conceptual cross-sectional view of the electrostatic coupling method.

× (Hector L12) ······[phase] becomes.

(Effects of the Invention) According to the present invention, as configured as described above, coordinates can be read with good accuracy even when the input pen is used at an angle.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the coordinate reading device according to the present invention, FIG. 2 is a block diagram showing a second embodiment of the coordinate reading device according to the present invention, and FIG. 3 is a block diagram showing the second embodiment of the coordinate reading device according to the present invention. Figures 4 to 7 are diagrams showing the conventional example, Figure 4 is a conceptual plan view of its electromagnetic induction method, and Figure 5 is its electrostatic A conceptual plan view of the coupling method, Fig. 6 is a conceptual sectional view of the electromagnetic induction method, 20... Reading table, 23... First circuit, 24... Input pen , 25... Pen tip, 27... Second circuit, 28... One circuit, 29... Other circuit, 30... Axis vA <Axis of input pen), Dl...
・First distance, D2... Second distance, P,... First coordinate, P2... Second coordinate, PX... Pen tip coordinate, θ・・・(Round angle)

Claims (2)

[Claims] (1) A coordinate reading device that reads the coordinate position on the table surface based on changes in the alternating magnetic field or capacitance between a first circuit embedded in a cross shape inside the reading table and a second circuit built into the input pen. At least two of the second circuits are provided, one circuit is arranged on the axis of the input pen and at a first distance from the pen tip, and the other circuit is arranged on the same axis and at a position of the first one. A coordinate reading device characterized in that it is arranged at a position a second distance from a circuit. (2) A first coordinate recognized between the one circuit and the first circuit, and a second coordinate recognized between the other circuit and the first circuit.
The coordinate reading device according to claim 1, wherein the pen tip coordinates are determined based on the coordinates and the first and second distances.