JP2001142646A - Eraser for coordinate input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eraser for a coordinate input device which can use a plurality of erasure ranges differently with a natural feeling of use despile its simple configuration and which is excellent in operation efficiency. SOLUTION: The upper part of the eraser 40 is covered with an outer case 41, coils LA, LB, LC and LD are provided at four corners A to D inside, respectively, and a button battery 43 and a circuit board 42 are provided at the central part. An inner case 44 holding an erasure pad 45 is provided at a lower part while being supported by a spring 49 in a rockable way, and switches SWA, SWB, SWC and SWD at four corners are turned on in accordance with a position where the pad 45 comes into contact. One or two coils L among the coils LA, LB, LC and LD transmit a signal at a prescribed period in accordance with a switch SW turned on. A writing panel 10 provided with a loop coil 23 magnetically coupled to the coils L receives a signal of the eraser 40, detect an erasure position and an erasure area, and erases recorded electronic data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eraser for a coordinate input device capable of setting an erasure range.

[0002]

2. Description of the Related Art For example, when a character or a figure is drawn on a board on which a plurality of loop coils are laid by an electronic pen which is a marker pen having an oscillation coil, magnetic coupling with a magnetic field formed by the oscillation coil of the electronic pen. A coordinate reading device such as an electronic blackboard has been proposed in which the coordinates of the trajectory of the electronic pen and the attributes of the pen are read by the board via the loop coil and recorded as digital data. In such a coordinate reading device, the coordinate position of the locus is read by pressing the pad surface against the board and wiping the board using an eraser having an oscillation coil like an electronic pen, and the coordinate position of the locus is read and already recorded. Digital data could be erased. This eraser indicates a position on the board and erases digital data in its locus, and its shape is generally circular so that the attitude direction of the eraser can be ignored. The structure of the circular eraser can be simplified because erasing may be performed within a predetermined distance from the center point without considering the posture of the eraser. In addition, if you prepare one with a large area of the wiping surface and one with a small area, you can erase a wide area at once with a large area, or correct and rewrite a small area with a small area. You can also delete them. Further, for example, in an invention such as an eraser for an electronic blackboard described in Japanese Patent Publication No. 6-9023, the eraser is formed in a rectangular shape or a similar shape to make it easier to use, and an eraser corresponding to the shape of the eraser is used. The range can be read. Further, in the reading in partial use of the eraser, there is an advantage that the eraser can be erased around a predetermined side by turning on / off the switch, and an eraser excellent in operability can be obtained.

[0003]

However, in the case of a circular eraser, apart from the electronic pen, two different wiping areas are used.
It is necessary to use more than one eraser, and there is a problem that the erasing operation becomes complicated for the user since these are used while being changed and used. Further, in a normal blackboard or whiteboard eraser, a rectangular blackboard eraser is generally used, and there is a problem that a rectangular shape can be used more naturally than a circular shape as an operational feeling. On the other hand, in the eraser for an electronic blackboard described in Japanese Patent Publication No. 6-9023, the shape is rectangular and the operational feeling is better than that of a circular shape. In addition, there is a problem in that the structure becomes complicated, for example, an infrared transmission unit is provided to specify the eraser range of the eraser separately from the detection of the coordinate position.

The present invention has been made to solve the above-mentioned problems, and has a simple configuration, a plurality of erasure ranges can be selectively used by one eraser, and a coordinate input device having a natural feeling of use and excellent operability. The purpose is to provide an eraser.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, there is provided an eraser for a coordinate input device, comprising: a transmitting unit having an oscillation coil for generating an alternating magnetic field of a predetermined frequency; A receiving section having a board section on which a plurality of loop coils capable of magnetic coupling with an alternating magnetic field are laid, and coordinates for reading and electronically recording coordinates of a trajectory of the transmitting section drawn on the board section. An eraser for a coordinate input device that is brought into contact with the board unit in an input device and erases a record input by the transmission unit based on the coordinates of the contacted portion, and generates an alternating magnetic field that can be distinguished from each other. A plurality of oscillation coils to be contacted, a contact surface contacting the board portion, and a plurality of pressure detecting means for detecting that the contact surface has contacted the board portion, the plurality of pressure detecting means Little At least one of the plurality of oscillating coils, when detecting that the contact surface abuts on the board portion, determines the information on the erasing range of the recording specified from the combination of the detection of the pressure detecting means. The combination is transmitted to the receiving unit.

[0006] The eraser of the coordinate input device according to this configuration includes a plurality of pressure detecting means for detecting that the contact surface has contacted the board portion, and at least one of the pressure detecting means is turned on. Is detected, the erasure range can be specified based on the combination. Furthermore, the specified erasure range can transmit information of the erasure range to the receiving unit in a predetermined combination of a plurality of oscillation coils that generate alternating magnetic fields that can be distinguished from each other. Different erase ranges can be used properly. Therefore, an eraser of the coordinate input device having a natural operation feeling and excellent operability can be provided.

According to a second aspect of the present invention, in addition to the configuration of the eraser of the coordinate input device according to the first aspect, the contact surface is rectangular, and the pressure detecting means and the oscillation are provided. The coils are respectively arranged at the four corners of the contact surface, and the erasing range is based on the entire surface of the rectangle, a fixed range based on each side, or each vertex based on a combination of detections by the pressure detecting means. One of the erasure ranges of the predetermined range is specified, and the oscillation coil transmits the information of the erasure range to the receiving unit by oscillating the information in a specific combination.

[0008] The eraser of the coordinate input device according to this configuration is provided with a rectangular abutment surface that is easy to grasp and easy to use by the user. Since it is possible to selectively use each side and a range based on each vertex, it is possible to provide an eraser of a coordinate input device having a natural operation feeling and excellent operability.

According to a third aspect of the present invention, in addition to the configuration of the eraser for the coordinate input device according to the first or second aspect, the oscillation coil for transmitting the erasure range to the receiving unit. Are characterized in that they are time-divided in a predetermined cycle and are sequentially alternately oscillated.

[0010] In the eraser of the coordinate input device according to this configuration, the oscillating coil for transmitting the erasure range to the receiving unit is time-divided at a predetermined cycle and oscillates alternately, so that the receiving unit detects different signals simultaneously. There is no need to perform the processing, the burden of performing a complicated mechanical configuration and complicated processing is reduced, and the configuration of the receiving unit can be simplified.

According to a fourth aspect of the present invention, in addition to the configuration of the eraser of the coordinate input device according to the second or third aspect, the eraser of the coordinate input device corresponds to the state of the pressure detecting means arranged at four corners. The oscillation coils to be oscillated are a maximum of two oscillation coils.

[0012] In the eraser of the coordinate input device according to this configuration, the number of oscillation coils that oscillate according to the state of the pressure detection means arranged at the four corners is a maximum of two oscillation coils. Is further reduced, high-speed processing becomes possible, and an eraser of a coordinate input device having better tracking performance can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an eraser for a coordinate input device according to the present invention will be described.
The eraser 40 will be described as an example with reference to the accompanying drawings. FIG. 1 is an external perspective view showing a main configuration of an electronic blackboard 1 which is a coordinate input device. As shown in the figure, the electronic blackboard 1
Is a pen 60 as a transmitting unit and a writing panel 1 as a receiving unit.
0 and an eraser 40.

First, the main configuration of the pen 60 will be described with reference to FIG. FIG. 3 is an explanatory diagram showing the internal structure of the pen 60, and FIG. 8 is an explanatory diagram showing the electrical configuration of the pen 60 shown in FIG.

As shown in FIG. 3, the pen 60 has a cylindrical body 61a and a lid 61c detachably attached to the rear end of the body 61a. Body part 6
1a, a coil L1, an ink cartridge 63 that can be taken out in a direction indicated by an arrow F2, a pen tip 62 inserted into the ink cartridge 63, and a coil L
A circuit board 69 on which an oscillating circuit for generating an alternating magnetic field from 1 is mounted, and a battery 70 as a power supply for supplying electricity to the circuit board 69 are provided. The coil L1 is formed into an annular shape by being wound 200 times to an inner diameter of about 15 mm and a length of about 15 mm. In addition, writing surface 2
1a (see FIG. 1), and is disposed at a distance of about 20 mm from the tip of the pen tip 62 in contact with the pen tip 62.

Between the ink cartridge 63 and the circuit board 69, there is provided a push button type switch 67 for supplying and shutting off electricity to the circuit board 69 and the like. The switch 67 connects the pen tip 62 to the writing surface 21.
a, the ink cartridge 63 is turned on when the ink cartridge 63 moves in the direction shown by the arrow F1.
I do. That is, the alternating magnetic field is generated from the coil L1 only when the pen 60 is writing on the writing surface 21a.

As shown in FIG. 8, the circuit mounted on the circuit board 69 (see FIG. 3) includes a pen 60 (see FIG. 3) such as the color of the ink and the thickness of the pen tip 62 (see FIG. 3). A CR oscillation circuit 69e in which a different modulation frequency fm is set for each attribute (hereinafter referred to as a pen attribute);
An LC oscillation circuit 69c that oscillates a carrier wave that carries a signal oscillated from the oscillating circuit.
(Frequency Shift Keying) and an FSK circuit 69d for performing modulation. The oscillation frequency of the carrier is determined by the coil L1 which is the inductance and the capacitors C2 and C3 which are the capacitances of the LC oscillation circuit 69c, and the modulation frequency fm
Is determined by a capacitor C5 which is a capacitance constituting the CR oscillation circuit 69e, a resistor R2, and a variable resistor R3. Further, the frequency shift of the carrier oscillation frequency is determined by the capacitance of the capacitor C4, which is the capacitance of the FSK circuit 69d.

The relationship between the pen attribute and the modulation frequency fm is set as shown in FIG. 10A for explaining the relationship. In FIG. 10A, “thin” means the pen tip 62
(See FIG. 3) indicates that the pen is thin, and “thick” indicates that the pen tip 62 is thick. For example, “black thick” indicates a pen whose pen tip 62 is thick and uses black ink. In addition,
The eraser 40 has four coils L _A , L _B , L _C , L
_D (hereinafter, referred to as a coil L unless otherwise specified), and an eraser 40 is used to calculate an erasure range of the eraser 40 based on a signal generated in the loop coil 23 by an alternating magnetic field generated from the coil. The four coils L _A , L _B , L _C , and L _D are also assigned different modulation frequencies fm, and are identified as the pen 60.

In FIG. 8, a switch 67 (see FIG. 3)
Is turned on, the electricity of the battery 70 (see FIG. 3) is supplied to each circuit, and the output of the integrated circuit IC3 of the CR oscillation circuit 69e switches the gate of the MOS FET of the FSK circuit 69d and oscillates from the LC oscillation circuit 69c. Carrier is C
The frequency is modulated by the signal oscillated from the R oscillation circuit 69e. In the present embodiment, the center frequency of the carrier is
410 kHz, and the frequency shift is ± 15 kHz. In the present embodiment, the integrated circuit IC1 is TC7SLU04F manufactured by Toshiba, and the integrated circuits IC2 and IC
C3 is TC7SLU04 manufactured by Toshiba. Also, M
The OS FET is 2SK2158. The resistors R1 and R2 are both 1 MΩ, and the variable range of the variable resistor R3 is 0.
Ω to 1 MΩ. Capacitors C2, C3, C4, C5
Are 2700pF, 1000pF and 270p, respectively.
F, 100 pF. Further, the battery 70 is connected to the LR 44
And its voltage is about 1.5V.

Next, the configuration of the writing panel 10 of the electronic blackboard 1 which is the receiving unit of the coordinate input device according to the present embodiment will be described with reference to FIGS. FIG. 2 is an explanatory diagram showing a state in which a personal computer (hereinafter abbreviated as PC) 100 and a printer 200 are connected to the electronic whiteboard 1 shown in FIG.

The electronic blackboard 1 includes a writing panel 10, a pen 60 for writing on the writing surface 21a, and an eraser 40 for erasing the written locus and data indicating the locus. . The writing panel 10 includes a frame 11 having a frame shape, and the writing panel main body 20 is incorporated in the frame 11. A plate-like base 12 is attached to the lower end of the front surface of the frame 11 along the lower end so as to project to the front surface. On the upper surface of the table 12, a plurality of stand-shaped recesses 12a for accommodating the pen 60 are formed. On the right side of the concave portion 12a, a flat portion 12 for placing the eraser 40 of the present invention is provided.
b is formed.

On the front right side of the frame 11, an operation unit 30 is provided.
Is provided. The operation unit 30 has a speaker 31 for reproducing sounds such as an operation sound and a warning sound, and a seven-segment page number in which data indicating the content written on the writing surface 21a (hereinafter abbreviated as writing data) is stored. A page number display LED 32 displayed by an LED, a page return button 33 for returning one page each time the button is pressed, a page forward button 34 for forwarding one page each time the button is pressed, and one page each time the stored writing data is pressed. Delete button 3
5, a printer output button 36 that is pressed to output the stored writing data to the printer 200, and a P button that is pressed to output the stored writing data to the PC 100.
C output button 37 and input warning L for warning of input failure
ED39a and battery warning LED39 that warns of running out of battery
b and a power button 38 pressed to activate the electronic blackboard 1.

A battery case 14 for accommodating four C-size batteries 14a serving as a power source of the electronic blackboard 1 is provided at a lower portion of the front surface of the frame 11, and a lid 14b is opened and closed on the front surface of the battery case 14. Mounted as possible. On the right side of the battery case 14, a volume control knob 13c of the speaker 31 is provided.
On the right side, connectors 13b and 13a are provided. The plug 13 of the connection cable 204 connected to the printer 200 is connected to the connector 13b, and the connection cable 1 connected to the PC 100 is connected to the connector 13a.
04 plug 102 is connected. In other words, electronic blackboard 1
The writing data indicating the contents written on the writing surface 21a of P
Monitor 10 output to C100 and provided in PC 100
3, the content written on the electronic whiteboard 1 can be viewed. Further, it is also possible to output handwriting data to the printer 200 and print the contents handwritten on the electronic blackboard 1 on the printing paper 203.

As shown in FIG. 1, metal fittings 15, 15 for hanging the electronic blackboard 1 on a wall are attached to both ends of the upper end of the back surface of the frame 11. In the present embodiment, the height H1 of the writing surface 21a is 900 mm, and the width W1 is 600 mm. The frame 11 and the base 12 are made of a synthetic resin such as PP (polypropylene) so as to be lightweight, and the total weight of the electronic blackboard 1 is 10 kg.
It is as follows.

Next, the structure of the writing panel main body 20 will be described with reference to FIG. FIG. 4 shows the writing panel body 20.
It is explanatory drawing which shows each component. Writing panel body 20
Has a structure in which a writing sheet 21 having a writing surface 21a, a plate-shaped panel 22, a frame-shaped mounting panel 24 on which a loop coil 23 is laid, and a plate-shaped back panel 25 are sequentially stacked. In this embodiment, the writing sheet 21
Is formed by a PET (polyethylene terephthalate) film bonded to a thickness of 0.1 mm,
The panel 22 is formed of acrylic resin, ABS (acrylonitrile-butadiene-styrene copolymer), PC (polycarbonate) or the like to a thickness of 3.0 mm. The mounting panel 24 is formed of a foamed resin material such as styrene foam to have a thickness of 40 mm, and the back panel 25 is formed of a conductive material such as aluminum to have a thickness of 1.0 mm. Furthermore, the entire thickness of the frame 11 that holds each end of the writing panel main body 20 is 50 mm.

Next, the configuration of the loop coil 23 will be described with reference to FIG. FIG. 5A is an explanatory view showing a part of the configuration of the loop coil 23 shown in FIG. 4, and FIG. 5B is a diagram showing the loop coil 23 shown in FIG.
FIG. 4 is an explanatory diagram showing a width P1 and an overlapping pitch P1 × 1/2. In the following description, a loop coil arranged in the X-axis direction among the loop coils 23 is referred to as an X coil,
Loop coils arranged in the Y-axis direction are called Y coils. As shown in FIG. 5A, the pen 60 is moved in the X-axis direction.
And m X coils X1 to Xm for detecting the X coordinate of the (X, Y) coordinate of the eraser 40 are arranged;
In the Y-axis direction, Y1 to Yn for detecting the Y coordinate
N coils are arranged orthogonal to the X coil. The X coil and the Y coil are each formed in a substantially rectangular shape, and the lengths of the long sides of the rectangular portion are P2X and P2, respectively.
Y.

As shown in FIG. 5B, the length of the short side of the rectangular portion of the X coil is formed to have a width P1, and the pitch between adjacent X coils is one half of the width P1. Each is overlapped. Each of the Y coils is also formed to have a width P1, and adjacent Y coils are each overlapped at a pitch of half the width P1. Each terminal 23a of the X coil is connected to the X coil switching circuit 50a, and each terminal 23b of the Y coil is connected to the Y coil switching circuit 50b (hereinafter collectively referred to as the X and Y coil switching circuit 50a). (See FIG. 9). As an example, in this embodiment, P1 = 50 mm, P2X = 6
80 mm, P2Y = 980 mm. Also, m = 2
2, n = 34. Further, both the X coil and the Y coil are formed of a copper wire having a diameter of 0.345 mm and having an insulating film layer (for example, an enamel layer) on the surface.

Next, the position coordinate table 58a for detecting the position coordinates of the pen 60 on the writing surface 21a will be described with reference to FIGS. FIG. 6A is an explanatory diagram showing a part of the X coils X1 to X3, and FIG.
6A is a graph showing the relationship between the voltage ex generated in the X coils X1 to X3 shown in FIG. 6A and the distance in the width direction x. FIG. 6C is a graph showing the relationship between the X coils X1 to X3 shown in FIG. 9 is a graph showing a voltage difference between mutually adjacent loop coils of X3. FIG. 7A is an explanatory diagram showing the position coordinate table 58a in the form of a graph, FIG. 7B is an explanatory diagram of the position coordinate table 58a, and FIG. FIG. 9 is an explanatory diagram showing a storage state of a value.

In FIG. 6, the centers of the X coils X1, X2, and X3 are c1, c2, and c3, respectively.
The voltages generated at X2 and X3 are ex1, ex2,
ex3. As shown in FIG.
ex3 is the center c1 to c3 of the loop coil 23, respectively.
, And has a monomodal property that becomes smaller as the end in the longitudinal direction approaches. In addition, each coil is overlapped with a half width of P such that its own null point, that is, the point where the voltage becomes 0 is outside the center of the adjacent coil.
In FIGS. 5A, 5B, and 6A, the width is slightly reduced to make it easy to see how the loop coils 23 overlap. As shown in FIG. 6C, the voltage difference between the mutually adjacent loop coils 23 of the X coils X1 to X3 has a maximum value on the centers c1 to c3 of the loop coils 23, respectively. The graph becomes zero at the midpoint between the loop coil 23 and the long side of the loop coil 23, that is, the midpoint of the portion where the adjacent loop coil 23 overlaps.

For example, in FIG. 6C, (ex1-e
x2), the right half of the graph (the part shown by the solid line) is X
Distance between the center c1 of the coil X1 and the intermediate point Q2 of the portion where the X coil X2 is overlapped (1/2 of the overlap pitch,
That is, the relationship between (1/4 of P) and (ex1-ex2) is shown. Now, if the pen 60 exists at the point Q2,
If (ex1-ex2) is detected, the distance ΔX1 from the center c1 to the point Q2 can be detected, so that the X coordinate of the point Q2 can be obtained. In this embodiment, the coil width P1
Is 50 mm, so that P1 / 4 = 12.5 mm. For example, when the right half (portion shown by a solid line) of the graph showing (ex1-ex2) in FIG. 6C is converted into 8-bit digital data, the graph shown in FIG. 7A is obtained. When this graph is converted into a table format, FIG.
The position coordinate table 58a shown in FIG. The position coordinate table 58a is stored in the ROM 58 (see FIG. 9) or the like, and is used for calculating the position coordinates of the pen 60.

Next, the main electrical configuration and control contents of the electronic whiteboard 1 will be described with reference to FIGS. 9, 10B and 11. FIG. FIG. 9 is an explanatory diagram showing the electrical configuration of the electronic whiteboard 1 by blocks, and FIG. 10B is an explanatory diagram showing signals at points A, B, and C in FIG. FIG.
1 is a flowchart showing main control contents executed by the CPU 56 shown in FIG. CPU provided in control unit 3
When detecting that the power button 38 (see FIG. 1) is pressed and the power is turned on (step (hereinafter abbreviated as S) 100: Yes), the control program 56 and the position coordinate table 58a stored in the ROM 58 (FIG. 7 (B)
(See S200), and performs a coordinate reading / pen information detection process (S300).

Here, the coordinate reading process will be described with reference to FIG. 9 along the flowchart of FIG. 12 showing the flow. The CPU 56 outputs a coil selection signal A (see FIG. 10B) for sequentially selecting the X coils X1 to Xm via the input / output circuit (I / O) 53 to the X coil switching circuit 50a.
To perform scanning of the X coils X1 to Xm (S302). Subsequently, a signal generated by magnetic coupling between the alternating magnetic field generated from the coil L1 of the pen 60 and one of the X coils is amplified by the amplifier 50c, and the amplified signal B (see FIG. 10B) is An unnecessary band is filtered by a pass filter (BPF) 50 d, and the amplitude is detected by an amplitude detection circuit 51. Subsequently, the amplitude-detected signal C (see FIG. 10B) is
The signal is converted into a digital signal corresponding to the amplitude, that is, the voltage value by the A / D conversion circuit 52, and is input to the CPU 56 via the input / output circuit 53.

Subsequently, the CPU 56 determines that the pen 60 has been detected (S304: Yes), scans the X coils X1 to Xm, and converts the voltage values e1 to em indicated by the input digital signals to the values shown in FIG. 7C. As shown in (5), it is sequentially stored in the voltage value storage area 59a of the RAM 59 in association with the coil number of the X coil (S306). Then CP
U56 calculates the X coordinate of pen 60 based on each voltage value stored in voltage value storage area 59a by the following procedure (S308). First, the maximum voltage value e among the voltage values e1 to em stored in the voltage value storage area 59a.
After selecting max, the coil number (hereinafter referred to as max) of the X coil that generated the voltage value emax is stored in the RAM.
59. For example, as shown in FIG. 6A, the pen 60 exists at the position of the point Q3, and as shown in FIG. 6B, the voltage value e from the X coils X1, X2, X3 respectively.
1, e2 and e3 occur, the maximum voltage value e2
And the coil number 2 of the X coil that generated the voltage value e2 is stored in the RAM 59 as max. Then, the CPU 56 determines the voltage value emax ± on both sides of emax.
1 is determined, and the coil number (hereinafter, referred to as max2) of the X coil that has generated the determined voltage value is stored in the RAM 59.

In the example shown in FIG. 6, the larger of the voltage values e3 and e1 of the X coils on both sides of e2 is determined to be e3, and the coil number 3 of the X coil that generated the voltage value e3 is m.
ax2 is stored in the RAM 59. Subsequently, the CPU 56
Are the coil numbers max and m stored in the RAM 59
ax2, the coil number max2 is the coil number m
It is determined from ax whether it is present in the + direction or the − direction of the X axis. And when max2 ≧ max,
The variable SIDE is set to 1, and if max2 <max, the variable SIDE is set to -1. In the example shown in FIG. 6, when pen 60 is at Q3, max = 2 and max2 =
3, max2> max, and the variable SIDE
Is set to 1. Subsequently, the CPU 56

DIFF = e (max) −e (max2) (1)

Is calculated, and the position coordinates closest to the calculated DIFF are read out from the position coordinate table 58a stored in the ROM 58, and set as OFFSET. Subsequently, the CPU 56

X = (P1 / 2) × max + OFFSET × SIDE (2)

Is calculated to obtain the X coordinate X1. here,
(P1 / 2) × max is the X of the center of the coil number max.
Indicates coordinates. In the example shown in FIG. 6, the expression (2) is expressed as X = (P
）) + 2+ (e2−e3) × 1, and the X coordinate of the position of the point Q3 is away from the center c2 of the X coil X2 in the positive direction of the X axis by (e2−e3), for example, ΔX2. Coordinates. Then, the CPU 56 scans each Y coil (S310), and stores the voltage value detected from each Y coil in the Y coil voltage value storage area 5 of the RAM 59.
9a (S312). Subsequently, the CPU 56 calculates the Y coordinate of the pen 60 using the same method as the above-described calculation of the X coordinate in S308 (S314).

Next, an electrical configuration and control for the CPU 56 to determine the pen attribute will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 13 shows an FSK demodulation circuit 55.
FIG. 14 is an explanatory diagram showing the electrical configuration of FIG.
14 is an explanatory diagram showing signal waveforms appearing at various parts of the FSK demodulation circuit 55 (see FIG. 9) shown in FIG.

FIG. 15A shows an output signal (hereinafter, referred to as a CR signal) of the CR oscillation circuit 69e (see FIG. 8).
The output signal of the LC oscillation circuit 69c (refer to FIG. 8) (hereinafter referred to as a carrier signal) and the output signal of the limiter circuit 54 (refer to FIG. 9) (hereinafter referred to as a limiter output signal).
FIG. 14 is an explanatory diagram showing a relationship between the count value and a count value K by a count circuit 55a (see FIG. 13). FIG. 15B is an explanatory diagram showing how the count value K stored in the shift register 55b (see FIG. 13) shifts.

FIG. 16A shows an absolute value comparator 55.
f (see FIG. 13) and the CPU 5
FIG. 16 is an explanatory diagram showing the relationship with the determination cycle of FIG.
(B) is an explanatory diagram showing how the count value K by the counter 55g moves. FIG. 17 is a flowchart showing the operation of S318 in FIG.
Count circuit 5 constituting FSK demodulation circuit 55 in FIG.
FIG. 18A is a flowchart showing the flow of processing (pen attribute detection processing 1) from 5a to the absolute value comparator 55f. FIG. 18A shows the counter 55 in S318 in FIG.
FIG. 18 is a flowchart showing the flow of the processing of FIG.
(B) is a flowchart showing the flow of the processing of the adder 55i in S318 of FIG. Note that FIG.
The carrier signal shown in (A) has, for example, a center frequency of 410 kHz and a frequency deviation of ± 15 k as described above.
Hz, but in order to make the explanation easy to understand, FIG.
In (A), the frequency shift is exaggerated.

First, FSK for detecting pen attributes
The features of the demodulation circuit 55 will be described with reference to FIG. In the example shown in FIG. 15A, the carrier signal has a high frequency (for example, 425 kHz) during the low level of the CR signal.
z), and is modulated to a low frequency (for example, 395 kHz) during the high level. For this reason,
Assuming that the period of the limiter output signal during the low level of the CR signal is TB, the period of the limiter output signal during the high level of the CR signal is TC longer than TB. Therefore, the count value K for one cycle of the limiter output signal by the count circuit 55a increases when the CR signal changes from a low level to a high level, and decreases when the CR signal changes from a high level to a low level.

That is, by detecting the timing at which the count value K by the count circuit 55a changes, C
The rising or falling timing of the R signal can be detected. Since the time from the change of the count value K to the next change corresponds to a half cycle of the CR signal, if one cycle of the change time of the count value K is measured, Since the period can be obtained, the pen attribute can be detected. Where FSK
An outline of the operation of each component of the demodulation circuit 55 will be described.
The count circuit 55a measures the count value K, and outputs a shift register 55b, a first weighted average circuit 55c, a second weighted average circuit 55d, a subtractor 55e, and an absolute value comparator 5
5f detects the change timing of the count value K, and the counter 55g, the register 55h, and the adder 55i measure the cycle in which the count value K changes. And the CPU 56
Determines the pen attribute based on the added value output from the adder 55i (S318 in FIG. 12).

Next, the operation of the FSK demodulation circuit 55 will be described in detail. The signal output from the band-pass filter 50 d is converted by the limiter circuit 54 into a square wave limiter output signal shown in FIG. 14 and output to the FSK demodulation circuit 55. Then, upon detecting the rise of the limiter output signal, the FSK demodulation circuit 55 (S10 in FIG. 17: Y
es), counting of the cycle of the limiter output signal is started using the system clock (CLK) (S12), and when the next rise of the limiter output signal is detected (S14: Y)
es), the count value K is output to the shift register 55b (S16), and the count value K is reset (S18).
That is, the count circuit 55a measures the length TB or TC of one cycle of the limiter output signal.

In this embodiment, the shift register 55
15B, as shown in FIG. 15B, the count value K for one cycle of the limiter output signal is stored for eight cycles of K1 to K8, and every time the newest count value K is taken in, the oldest count value K is stored. Discard and shift each count value K one by one. The first weighted average circuit 55c calculates a weighted average value from the latest count value K stored in the shift register 55b to the third newest count value K, and calculates the weighted average value (hereinafter, referred to as the first weighted average value). ) Is output to the subtractor 55e. The second weighted average circuit 55d calculates a weighted average value from the oldest count value K stored in the shift register 55b to the third oldest count value K, and calculates the weighted average value (hereinafter, referred to as a second average value).
It is called the weighted average. ) Is output to the subtractor 55e.

The subtractor 55e calculates a difference Δm between the first weighted average value and the second weighted average value, and outputs the difference Δm to the absolute value comparator 55f (S20 in FIG. 17). For example, in FIG. 15A, when the first weighted average circuit 55c calculates the weighted average value of the count values K1 to K3, and the second weighted average circuit 55d calculates the weighted average value of the count values K6 to K8, Since the count values K7 and K8 of the count values K6 to K8 are obtained by counting the period TC longer than the period TB of the limiter output signal, the second weighted average value is larger than the first weighted average value. Therefore,
By detecting that the second weighted average value has become larger than the first weighted average value, it is possible to detect a change point of the period of the CR signal. In other words, if the period of the changing point of the period of the CR signal is detected, the period of the CR signal can be detected, so that the information of the pen attribute can be recognized.

As described above, since the count values K counted at different times in time are weighted and averaged by the weighted averaging circuit, even if a certain count value K is affected by noise, the influence is reduced.

Next, the processing from the absolute value comparator 55f to the adder 55i will be described with reference to FIG. In FIG. 16, 〜 indicates the count value K by the counter 55g. The absolute value comparator 55f calculates the difference Δ
m is compared with a preset threshold value m1, and it is determined whether or not the difference Δm is equal to or greater than the threshold value m1 (FIG. 17).
(S22), when it is determined that the difference Δm is equal to or larger than the threshold value m1 (S22: Yes), the threshold determination output is changed from a low level to a high level (S24). That is, it is determined that the cycle of the limiter output signal has changed (the rising edge of the CR signal has been detected). For example, FIG.
The count value K by the count circuit 55a of the shorter cycle TB of the limiter output signal shown in FIG.
If the count value K is 16 and the threshold value m1 is 2, since the count values K1 to K6 are all 10, the first weighted average value = (K1 + K2 + K3) / 3 = 10. Since the count values K7 and K8 are both 16,
Second weighted average value = (K6 + K7 + K8) / 3 = 42/3
= 14, and the difference Δm = 10−14 = −4.

The first weighted averaging circuit 55c and the second
A weighted averaging circuit 55d, a ratio of the carrier frequency (the oscillation frequency of the LC oscillation circuit 69c) to the modulation frequency fm,
The decision is made based on the complexity of the circuit. The count value K held by the shift register 55b, that is, the number of periods of the limiter output signal is determined by the ratio of the frequency of the system clock to the frequency of the carrier, and the frequency of the system clock is large enough to discriminate the change in the frequency. Set to

Therefore, since (absolute value of difference Δm = 4)> (threshold value m1 = 2), the threshold value judgment output changes from low level to high level (S24 in FIG. 17). This high level state indicates that the absolute value of the difference Δm is equal to the threshold value m1
The above is maintained until the absolute value comparator 55f determines. When the calculation range of the first weighted averaging circuit 55c and the second weighted averaging circuit 55d reaches a portion passing through the edge of the CR signal, the period of the limiter output signal becomes constant. Since both the second weighted averaging circuits 55d calculate the weighted average value of the count value K in the same cycle, the subtraction value by the subtractor 55e becomes 0, and the threshold value determination output remains in the high level state.

On the other hand, when the counter 55g detects that the threshold value judgment output has changed from the low level to the high level (S30 in FIG. 18A: Yes), the time when the judgment output is at the high level, that is, The half cycle of the judgment output is counted using the system clock (S32). Let the count value be K ((B1) in FIG. 16B).
When the absolute value comparator 55f determines that the difference Δm is equal to or larger than the threshold value m1 (S2 in FIG. 17).
2: Yes), the threshold determination output is changed from the high level to the low level (S24). That is, it is determined that the cycle of the limiter output signal has changed (the falling edge of the CR signal has been detected). Thereby, the counter 55g
Detects that the threshold determination output has changed from the high level to the low level (S34: Ye in FIG. 18A).
s) As shown in (B2) of FIG. 16B, the count value is output to the register 55h (S36). Subsequently, the counter 55g resets the count value (S3
8) Count the time during which the threshold value judgment output is at the low level, that is, the half cycle of the threshold value judgment output (S32 via circle B). The count value is used.

Subsequently, when the adder 55i determines that the timing at which the count value K is held in both the counter 55g and the register 55h, that is, the addition timing (S50 in FIG. 18B: Yes), the counter 55g holds the count. The count value and the count value held by the register 55h are added (S52), and the added value is output to the CPU 56 (S56). At this time, the counter 55g outputs the count value to the register 55h as shown in (B3) of FIG. 16B (S36 of FIG. 18A). Then, the CPU 56 reads the value of the FSK demodulation circuit 55 via the input / output circuit 53, that is, the added value (see S316 and FIG. 13 in FIG. 12), and determines the pen attribute based on the read added value (S31).
8). For example, when the added value is 245, FIG.
It is determined that the pen attribute is black thick as shown in FIG. The CPU 56 stores the pen attributes and the XY coordinates in the RAM 59 in association with each other. The writing data stored in this manner is output to, for example, the printer 200 (see FIG. 2) and printed in black. The PC 100 (FIG. 2)
) And is displayed in black on the monitor 103 (see FIG. 2). That is, the writing data can be reproduced according to the pen attribute.

Subsequently, the adder 55i adds the count value of the register 55h and the count value of the counter 55g and outputs the result to the CPU 56 ((B) in FIG. 16B).
3)). Thereafter, every time the threshold determination output changes, the count value K of the counter 55g is output to the register 55h, and the adder 55i outputs the count value K of the counter 55g and the count value K held in the register 55h.
Are repeated, and the cycle of outputting the added value to the CPU 56 is repeated. That is, as shown in FIG. 16B, the adder 55i adds the latest count value K counted by the counter 55g and the immediately preceding count value K held in the register 55h, and adds the result. To output to the CPU 56, as shown in FIG.
Determines the pen attribute based on the latest count value K and the sum of the previous count value K every half cycle of the threshold value determination output. Therefore, even if the scan of the loop coil 23 is performed in the middle of the threshold determination output, for example, between times t0 and t1 in FIG. Even if the added value of (t2 to t4) is not taken, the added value of one cycle from time t2 to t4, which is a half cycle after time t1, may be taken, so that the pen attribute can be determined at high speed.

If the eraser 40 is not continuously detected (S319: No in FIG. 12), the pen attributes and the XY coordinates are stored in association with each other (S320), and the X coil scan (S302) is performed again. The processing is repeated from the procedure. If the eraser 40 is detected continuously (S3
19: Yes), coordinate reading / pen information detection processing (FIG. 11)
(S300) ends (end), and the procedure moves to the next eraser process (S400).

As described above, when the eraser 40 is not continuously detected (S319: No in FIG. 12), the X and Y coil scans (S302, S310) are repeated, and
, The pen 60 is applied to the writing surface 21a, the pen 60 is detected for the first time (S304: Yes), the pen 60 is separated from the writing surface 21a, and the pen 60 is no longer detected (S304: No). The pen attributes of the pen 60 and the XY coordinates are stored in a locus storage area (not shown) of the RAM 59 in association with each other (S320). The position of the pen 60 is sequentially stored in the trajectory storage area as an X coordinate and a Y coordinate together with a pen attribute in a dot matrix aligned in the X-axis and Y-axis directions. In this way,
Coordinate reading / pen information detection processing shown in FIG. 11 (S300)
Is completed, next, the eraser process (S400)
Is performed.

The eraser process (S400) is a process for erasing writing data input by the pen 60 and electronically stored in the RAM 59 (see FIG. 9) of the writing panel 10 by defining an erasing area. Here, first, the eraser 40 in the electronic blackboard 1 of the present embodiment will be described in detail.

FIG. 19 is a diagram of the eraser 40 viewed from above. FIG. 20 is a cross-sectional view taken along the line II of the eraser 40 shown in FIG. Here, the outer case 41 side of the eraser 40 is set to the upper side. As shown in FIG. 19, the eraser 40 has an aspect ratio of about 2:
3 is formed in a rectangle. In the following description, FIG.
9, the upper left corner is a corner A, the upper right corner is a corner B,
The lower left corner is called a corner C, and the lower right corner is called a corner D. Upper eraser 40 covers the rectangular parallelepiped outer case 41 made of plastic downwardly opened as shown in FIG. 20, the four corners of the corner portions A, B, C, the D, the coil L _A, L _B , L _C and L _D are provided. The coils L _A , L _B , L _C , and L _D are oscillating coils each having an inductance in which a conductor covered with an enamel layer is wound about 200 times around a cylindrical resin pipe. The coils L _A , L _B , L _C , L _D are connected to the transmission signal generator 48.
a, 48b, 48c, and 48d (hereinafter referred to as a transmission signal generator 48 unless otherwise specified) (see FIG. 22) (see FIG. 22).
See).

The switches SW _A , SW _B , which are pressure detecting means, are provided inside the coils L _A , L _B , L _C , L _D.
SW _C and SW _D (hereinafter, referred to as a switch SW unless otherwise specified) are provided. Switch S
_{W A, SW B, SW C} , SW D is a limit switch of the push plunger type which arranged a plunger downward, turned on by pressing from below, it is turned off by a return spring (not shown) unless pressed.

At the upper center of the eraser 40, a button battery 43 as a power supply is arranged. The button battery 43 is composed of an LR 44 having a voltage of about 1.5V. Below the button battery 43, a circuit board 42 on which a control circuit 46 and the like are mounted is arranged. Further, a spring 49 is mounted below the circuit board 42. In addition, outer case 4
Inside 1, an inner case 44 is loosely fitted and mounted so that a lower part protrudes, and a central portion of an upper end thereof is swingably supported by a spring 49. The inner case 44 is a resin member having a rectangular parallelepiped shape whose entire lower part is open. Inside the inner case 44, an erasing pad 45 molded from a material such as a substantially rectangular parallelepiped felt is fitted so as to protrude downward. The erasing pad 45 is used for the writing surface 21.
a (see FIG. 1) is a member for wiping and erasing the ink image drawn by the pen 60 (see FIG. 1).

Inner case 44 supporting erase pad 45
As described above, the upper part of the center is supported by the spring 49 so as to be swingable, and the upper four corners A, B, C, and D of the inner case 44 are provided with the switches SW _A , S
W _{B, SW} C, configured so as to contact the plunger of the SW _D.

FIG. 25 is a diagram showing a state in which the entire surface of the erase pad 45 of the eraser 40 shown in FIG. 20 is pressed against the writing surface 21a. As shown in FIG.
When the entire surface of the erase pad 45 of 0 is pressed against the writing surface 21a, the spring 49 is compressed via the inner case 44, and at the same time, the switches SW _A , SW _B , disposed at the four upper corners of the inner case 44. SW _C , SW _D (see FIG. 19)
Is pressed by the inner case 44 from below, and the switch S
_{W A, SW B, SW C} , all SW _D is turned on.

FIG. 26 shows the eraser 4 shown in FIG.
FIG. 20 is a diagram showing a state in which a side connecting a corner A (see FIG. 19) and a corner C of the erase pad 45 of 0 is pressed against the writing surface 21a. As shown in FIG. 26, the erase pad 45 of the eraser 40
When the side connecting the corner A and the corner C is pressed against the writing surface 21a, the spring 49 is compressed via the inner cover 44, and at the same time, the inner case 44 is inclined, and the corner A and the corner C are moved. the switch _SW a, SW _C disposed in the corner on the side connecting, is pressed against the inner case 44 from below, the switch _SW a, SW
Only _C is turned on, and the switches SW _B and SW _D are kept off.

FIG. 27 shows the erase pad 45 of the eraser 40.
Is a schematic diagram showing a state in which a corner portion A of FIG.
FIG. As shown in FIG.
Is pressed against the writing surface 21a.
5, the corner A of the inner case 44 (see FIG. 20) is pressed.
And the switch SW disposed at the corner A_AOnly the inner case
44 and is turned on, and the other switches are turned on.
Switch_B, SW_C, SW _DIs kept off
You.

FIG. 21 shows a switch SW_A, SW_B, SW
_C, SW_DOf the erasure range determined by the combination of
It is a schematic diagram which shows an example. For example, switch SW_A, S
W_B, SW_C, SW_DIf all are turned on,
Erasing range E shown in FIG. 21 surrounded by corners A, B, C, and D
A₁Range. On the other hand, switch SW_AOnly turned on
In such a case, the corner A of the erase pad 45 is actually
The range to be erased further depends on the shape and material of the erase pad 45.
It may vary depending on the hardness, the degree of settling, the strength of pressing, etc.
Of the actual erase range due to trial and error
Erase electronically recorded data to match
Range EA₄Set. Also, switch SW_B, SW_D
Is turned on, the erase range EA₃Is the switch S
W_C, SW _DIs turned on, the erase range EA₂But
It is set to be deleted. Note that the diagonal lines
Switch_AAnd SW_DOnly or SW_BAnd SW_Cof
It is theoretically not possible for the
Switch_A, SW_B, SW _C, SW_DIs the mounting position
Only the switch SW on the diagonal line is turned off.
It may be assumed that the In such a case,
Although it is conceivable that the data is not erased as
Now, it is assumed that the entire surface of the erase pad 45 is pressed.
do. Similarly, four switches SW_A, SW_B, SW
_C, SW_DWhen three switches SW are turned on
The same processing is performed.

FIG. 23 shows the writing surface 2 of the writing panel body 20.
FIG. 2 is a diagram showing an example of an erasing range EA in 1a. Here, the switches SW _A , SW _B , SW _C , SW _D
Both the range to be erased and the area to which the specified range to be moved is to be erased are called erase ranges. The erasing range EA set as described above will be specifically described. For example, when the contact portion TP is at the corners A, B, C, and D as in the eraser 40a, the erasing pad 45 (FIG. 21) is used. parts total of the reference) are trajectories passing through is recognized as the deletion range EA _1, data in this portion is erased. The recognition, as eraser 40b, contact portion TP is, the corner portion B, and a D are corners B, as the partial erase range EA ₃ is a trajectory region around the side connecting the D passes And this part of the data is erased. Furthermore, the contact portion TP like the eraser 40c
If only the corner portion A, the portion predetermined area around the corner portion A is the locus passing through is recognized as the deletion range EA _4, data in this portion is erased.

Here, FIG._A, SW
_B, SW_C, SW_DON / OFF combination and in that case
The coil L that oscillates_A, L_B, L_C, L_DPairs of
It is a conversion table adapted. Note that the coil L_A,
L_B, L_C, L_DWill be described later. Smell on the table
The numbers in the vertical column labeled CASE
It is a number for organizing the set. 0 to 15 each
The rows in are referred to as case 0 to case 15, respectively.
I do. SW indicates a switch SW that is turned on.
The vertical columns labeled A, B, C, D respectively
Switch SW_A, SW_B, SW_C, SW_DRepresents each column
Indicates that the switch SW marked with a circle is turned on.
For example, in case 0, the switch SW_A, SW_B,
SW_C, SW _DAre not turned on. In addition,
Switch 1, switch SW_DOnly that it is turned on
And And it was described as ERASE TYPE
The rightmost column shows the type of erasure in each case.
You.

First, in case 0, since none of the switches SW is turned on, the erase pad 45 (FIG. 21)
Is not pressed against the writing surface 21a (see FIG. 23), the type of erasure is NONE, and the erasure range EA does not exist. In each of the cases 1, 2, 4, and 8, only one switch SW is turned on, and the type of erasing is POINT in which erasing is performed using a corner of the erasing pad 45 having the turned on switch SW. A predetermined range centered on the corners A, B, C, and D is the erasing range EA.
It is said. In the cases 3, 5, 10, and 12, the two switches SW of the adjacent corners are turned on, and the sides AB, BD, and CD connecting the corners of the switches SW of the erase pad 45 that are turned on. , AC, and erase type LINE, and edges AB, BD, CD, AC
A predetermined range centered on is set as the erasing range EA. In case 15, all of the four switches SW are turned on, and the entire erase pad 45 is pressed against the writing surface 21a so as to be erase type PLANE. The entire erase pad 45 has an erase range EA. Is done. In cases 6 and 9, two switches SW at opposing corners are turned on, and in cases 7, 11, 13 and 14, three switches SW are turned on. In this case, as described above. It is assumed that the entire surface of the erasing pad 45 is pressed against the writing surface 21a for erasing, and the type of erasing is (PLANE).

Therefore, the eraser 40 is connected to the switch S
_{W A, SW B, SW C} , the SW _D, eraser pad 45
Is pressed against the writing surface 21a, and the portion of the erasing pad 45 for erasing the ink image drawn on the writing surface 21a can be detected. That is, by the combination of the switches SW _A , SW _B , SW _C , and SW _{D which} are turned on,
All over the erase pad 45 or sides AB, BD, C
Either D or AC, or any of vertices A, B, C, and D can be used to detect whether erasure has occurred. Therefore, if the erasure range of the record is obtained based on the result of this detection, the pen 60 is placed on the writing surface 21a electronically recorded on the RAM 59 (see FIG. 9) of the writing panel 10 (see FIG. 1).
(Refer to FIG. 1), it becomes possible to delete a corresponding portion of the data of the locus drawn and input. Then, the writing surface 21a
And the RAM of the writing panel 10
It is possible to prevent the inconvenience that the electronically recorded data matches the data 59 and a discrepancy occurs between them.

Next, the erase range EA detected as described above
Is transmitted to the writing panel 10 which is a receiving unit.
You. Here, FIG. 22 shows a circuit configuration of the eraser 40.
FIG. As shown in FIG.
The circuit of 0 is a control circuit 46 and a button connected thereto.
Battery 43 and switch SW_A, SW_B, SW_C, SW _D
And transmission signal generators 48a, 48b, 48c, 48d
And the respective transmission signal generators 48a, 48b, 48
c, coil L connected to 48d_A, L_B, L_C, L_D
And an oscillation circuit 47.

The control circuit 46 includes a switch SW_A, S
W_B, SW_C, SW_DTo detect the on / off status of
Based on the combination, the conversion table (see FIG. 29)
Oscillating coil L_A, L_B, L_C, L_DAnd select
Each transmission only when the selected coil actually oscillates
Power is supplied to the signal generators 48a, 48b, 48c, 48d.
Control to supply. The transmission signal generator 48
Signal generator 48a is coil L _AThe transmission signal generator 48b
Is coil L_BThe transmission signal generator 48c has a coil L
_CAnd the transmission signal generator 48d has the coil L_DTo each
Connected. Selected to transmit by control circuit 46.
The transmission signal generator 48 connected to the coil L
Is assigned to each coil L.
At a specific frequency (see FIG. 10 (A)).
The signal oscillates the coil L. Therefore, the coil
L_A, L_B, L_C, L_DAre common carrier frequencies
Oscillating, but modulated at different unique frequencies
FSK recovery of the writing panel 10 which is a receiving unit
The adjustment circuit 55 (see FIG. 9) enables identification.

The electrical configuration of the transmission signal generators 48a, 48b, 48c, 48d for oscillating and modulating the carrier wave is basically the same as the electrical configuration of the pen 60 (see FIG. 8). Although not shown, the LC oscillation circuit 69c, the CR oscillation circuit 69e, and the FSK circuit 69d shown in FIG.
Correspond to the transmission signal generators 48a, 48b, 48c, 48d, and the power control function of the push button type switch 67 is built in the control circuit 46. Therefore, the CR oscillation circuit 69e can change the frequency generated by changing the capacitance of the capacitor C5 and the resistance values of the resistor R2 and the variable resistor R3, as well as the transmission signal generators 48a, 48b,
By setting the capacitance and resistance value of a capacitor and a resistor (not shown) corresponding to the capacitor C5, the resistor R2, and the variable resistor R3 in 48c and 48d to predetermined values, the respective coils on the side of the writing panel 10 as the receiving unit are set. L can be identified. The button battery 43 is a power source for the control circuit 46, the transmission signal generator 48, and the oscillation circuit 47. The oscillation circuit 47, described later coil _L A,
L _B, a circuit _{for L C,} and generates the period T to oscillate alternately L _D, a circuit of CR oscillator circuit 69e equivalent to the configuration of FIG. 8.

As described above, in the configuration of the electronic whiteboard 1 of the present embodiment, it is difficult to process a plurality of input signals at the same time. Further, in order to enable the processing, a writing panel 1 serving as a receiving unit is required.
Since the 0 side of the structure and process are complicated, in the present embodiment, the coil _{L A, L B, L C} , L D , by oscillating alternately by time division each without oscillate simultaneously, The processing load on the writing panel 10 as the receiving unit is reduced.

The four coils L_A, L_B, L_C, L
_DEverything, switch SW_A, SW _B, SW_C, SW_D
When they are oscillated in response to the ON of
Even if they oscillate sequentially, from the eraser 40 at the same position,
A set of continuous signals is sent to the writing panel 10 as a receiving unit
Must be received by scanning. Therefore, writing
The processing load on panel 10 is increased. However, four times
Of each coil L and its position coordinates must be detected at the same time.
If it is, the exact position cannot be recognized. Therefore, eraser 4
If the speed of change of position 0 is high, a position detection error will occur.
Would. Therefore, in the eraser 40 of the present embodiment,
Four coils L_A, L_B, L_C, L_DTwo of the
Or only one coil L is oscillated alternately, or one coil
By continuously oscillating the laser L, the processing of the writing panel 10 is performed.
It is configured to reduce the processing burden and to speed up the processing.
Hereinafter, the procedure for selecting the coil L to be oscillated will be described.
explain about.

Here, the conversion table of FIG. 29 will be described again. As described above, the control circuit 46 controls the switch S
_{W A, SW B, SW C} , on the SW _D, by detecting the off, on the basis of the combination, divided into 16 different cases, they had done the type of erasing in each case. Then, assuming that there are two coils L to be oscillated, four switches SW _A , SW _B , and S are used only based on the information.
W _C, and the state of the SW _D, can not tell the writing panel 10 side is a receiving part of all of the position information. Therefore, in case 0 in which none of the switches SW in which the erase type is NONE in the previous type is not turned on, cases 1, 2 and 2, in which only one switch SW each of which is of the erase type POINT are turned on. In the case of cases 4, 5, 10, 12 in which the two switches SW of the adjacent corners, which are of the erase type LINE, are turned on, in the case of 4, 8, 10, the coils L of up to two are oscillated. It is identified by the writing panel 10.

On the other hand, in case 15 where the erase type is PLANE and all four switches SW are turned on,
2 of the opposite corner where the type of erasure is (PLANE)
Cases 6 and 9 in which three switches SW are turned on and cases 7, 11, 13, and 1 in which three switches SW are turned on
In the case of No. 4, even if the two coils L are oscillated, the writing panel 10 cannot identify them. However, in Cases 6 and 9, and Cases 7, 11, 13, and 14, the erase type PLANE in which all four switches SW are uniformly turned on.
The processing can be performed by setting the type of erasure (PLANE) regarded as equivalent to the above. That is, in the case of the cases 6, 9 and the cases 7, 11, 13, and 14, since the corners which are opposed to each other on the diagonal line are always included, the eraser 40 is located at the position having the diagonal line connecting these two corners. It is assumed that there is an erase area EA on the entire surface of the erase pad 45 based on the position.
Is calculated. In case 15 in which all the four switches SW are set to the erase type PLANE and all four switches SW are turned on, cases 3 and 5, in which two switches SW of the adjacent corners each set to the erase type LINE are turned on. 1
Oscillating coil L to distinguish it from 0, 12
Is a combination of the coils L _A and L _D or the coils L _B and L
_A distinction can be made by combining _C. In this embodiment, oscillates alternately in combination coils L _A, L _D. That is, when one switch SW is turned on at one vertex or two switches at a side, the coil L at the same position is oscillated as it is. In addition, when it is regarded as the whole surface or the whole surface, the coils L that oscillate are limited to two by oscillating the diagonal coils L.

According to the switch SW thus turned on,
The two coils L selected by the following procedure are generated in the following procedure.
And is received by the writing panel 10 (see FIG. 1). Figure
Reference numeral 24 denotes a timing at which the eraser 40 causes the coil L to oscillate.
And the timing at which the writing panel 10 scans
It is a timing chart shown. The eraser 40 is described above.
The coil L that oscillates like_A, L_B,
L_C, L_DSelect one or two from. Select here
When two coils L are obtained, (a), (c),
As shown in (d), the oscillation circuit 47 (see FIG. 22)
It is oscillated alternately in synchronization with the signal of period T
You. When one coil L is selected, (A)
The same coil L is continuously oscillated as shown in FIG. here
Then, the writing panel 10 serving as a receiving unit (hereinafter, referred to as
Lower receiver) is t₁Start scanning from time
Then, in (A), the oscillation coil L_ADeparts from
Signal f _AIs received and the same as in the case of the pen 60
Coil L_ACoordinates (x, y) are read and the pen attributes
Corresponding coil L_A, L_B, L_C, L_DKind of read
Can be Hereinafter, FSK demodulation for identifying the type of the coil L
The signal read by the circuit 55 (see FIG. 9) is denoted by id.
Say. id is the coil L_A, L_B, L_C, L_DCorresponding to
Id_A, Id_B, Id_C, Id_DFour types are set
You. t₁Scan with id₁As id_AIs RA
M59 (see FIG. 9), and (x₁, Y
₁) Is stored.

Next, the next scan is performed at time t ₂ at which the interval T 'has elapsed from the time t _1. Here, T ′, which is the sampling time of the scan, is equal to the coil L within the same cycle as compared to the cycle T in which the coil L is oscillated.
The second scan is not performed during the oscillation of
In order to avoid reading the oscillation signal of the coil L of the next next cycle by skipping the oscillation signal of the coil L of the next cycle,
j <T ′ <Ti (where T′'T). Here, since hitting the switching timing Tk of the oscillation time t ₂ exactly coil L, valid data is not read in the scan at time t ₂ "nodat
a ". In this case, since the oscillation signal of the continuous coil L can not be collected, the data E ₁ stored is read in the previous time t ₁ is discarded. And time t ₃
Made again third time scan in, id _A is read as _{id 3, (x 3, y} 3) as coordinates is again stored in the RAM59 are read. Subsequently fourth time scan at time _{t 4} is performed, id _A is read as id _4, as coordinates _(x 4, _{y 4)} are read. This scan is repeated a predetermined number of times until valid continuous coil data E is obtained.

[0078] If you get the data E of the coil L consecutive this manner (in FIG. 12 S319: Yes), S400 eraser treatment (Fig. 11 based on the data _{E 4,} 3
0) is performed. Here, since id _A was continuously obtained, the coordinates (x
₃ , y ₃ ) only at a predetermined corner A around the writing surface 21
It is determined that Case 8 has contacted a. Subsequently, if data E of case 8 is subsequently input, an area connecting them is set as an erasure range EA, and data such as characters is erased.

Similarly, in the case of (a), as shown in the conversion table of FIG. 29, the case 5 connecting the corners B and D, which are short sides, and in the case of (c), the corner which is a long side In the case 3 connecting the parts C and D, and in the case of (d), it is determined that the entire surface of the erasure pad 45 is pressed against the writing surface 21a, and the data such as characters in the respective erasure ranges EA are erased. .

The eraser 40 of the electronic blackboard 1 of the present embodiment
Since the writing panel 10 is configured as described above,
The following functions are provided. Here, FIG.
FIG. 30 is a flowchart showing a procedure for oscillating clock signals,
12 is a flowchart showing details of the eraser process in S400 of FIG. Hereinafter, description will be given along these flowcharts. The following procedure can be basically realized by a combinational logic circuit.

First, when the power of the eraser 40 is turned on,
The process is started (start in FIG. 28), and it is determined whether any of the switches SW is turned on (S1). If none of the switches SW is turned on (S
1: No), and enters a standby state (S1: No → S1). If any switch SW is ON (S1: Ye
s) Based on the switch SW that is turned on, the coil L that oscillates is selected by the conversion table shown in FIG.
2). Here, if there is one oscillating coil L (S
3: Yes), the selected coil L is continuously oscillated in the cycle T (S4). When the number of oscillating coils is not one, that is, two (S3: No),
The two coils L are oscillated alternately in a cycle T (S5). Here, if the ON switch SW is not changed (S
6: No), the oscillation is continued as it is, and if the switch SW that has been turned on is changed (S6: Yes), the oscillation of the coil L is stopped (S7). And S again
The process from 1 is repeated. Then, the process is stopped by turning off the power.

The signal oscillated by the coil L from the eraser 40 and transmitted is processed in the writing panel 10 as follows. This will be described below with reference to the flowchart of FIG. When the coordinate reading / pen information detection processing ends in S300 of FIG. 11 as described above, the eraser processing of S400 starts (start of FIG. 30). When the process is started, it is determined whether or not continuous data E of the eraser 40 is obtained by the above-described scan. If there is no data E of the eraser 40 (S401: No),
The processing ends (ends), and the flow shifts to the page processing of S500 in FIG. Here, if the data E of the continuous eraser 40 is read (S319: Yes in FIG. 12) and stored (S401: Yes), the data E of the continuous attribute is read using the conversion table shown in FIG. The erase type is determined (S402), and the erase range EA is calculated based on the coordinates of the continuous data E and the erase type (S404). Then, the calculated erasure range E
The corresponding portion of the electronic data input by the pen 60 based on A and recorded in the RAM 59 (see FIG. 9) is erased (S406). Then, the values of the X coil, Y coil scan, and FSK demodulation circuit 55 are read (S40).
8) It is determined whether data E of the continuous eraser 40 has been read further (S401). If data E of the continuous eraser 40 is continuously read, the type of erasure is determined (S402). A new erasure range EA is calculated so as to be continuous with the previous erasure range EA (S404), and is erased (S406). Then, scanning is performed again (S408), and the data E of the eraser 40 is read.
As long as is input continuously (S401: Yes), S4
02 to S408 are repeated, and when the continuous data E of the eraser 40 is no longer detected (S401: N
o), the eraser process (S400) of FIG. 11 ends (end), and the process proceeds to the page process (S500).

Here, returning to the flowchart of FIG. 11, the description will be continued with reference to FIG. Eraser processing (S40
When 0) ends, the CPU 56 returns to the page return button 3
3. When the page feed button 34 and the delete button 35 are pressed, page processing such as returning, sending, or deleting stored writing data in page units (S50).
Perform 0). In the page processing, the CPU 56 operates the operation unit 3
Switching signals generated by the operation of various buttons (see FIG. 1) provided at 0 are fetched via the I / F circuit 57, and the page storing the position coordinate data stored in the RAM 59 is returned in page units. Page processing such as sending or deleting the position coordinate data in page units. Further, the CPU 56 converts the position coordinate data of the target page from the position data stored in the RAM 59 into an appropriate format, and
And a data output process (S600) for outputting to the printer 200 (see FIG. 2).

Further, the CPU 56 operates the audio circuit 31a based on a switching signal generated when various buttons are pressed, and emits operation sounds such as "P" and "P" from the speaker (SP) 31. The voice output process is executed (S700).
The processing from 0 to S700 is repeated (return, S10
0 to S700).

Since the eraser 40 of the electronic whiteboard 1 according to the embodiment of the present invention has the above-described configuration and operation, it has the following effects. That is, there are provided switches SW _A , SW _B , SW _C and SW _D which are pressure detecting means arranged at four corners for detecting that the erasing pad 45 as the contact surface has contacted the writing surface 21 a as the board portion. In a state where at least one detection switch is detected to be turned on, there is an effect that the erasing range EA can be specified based on the combination. Furthermore the identified deletion range EA, the coil L _A is a plurality of oscillation coils for generating distinguishable alternating magnetic field to each _other, L _B,
L _C, writing panel 1 _{L D} is a receiver at a predetermined combination
Since the information of the erasure range EA can be transmitted to 0,
There is also an effect that different erase ranges EA can be properly used even with one eraser 40. for that reason,
There is an effect that the eraser 40 of the coordinate input device having a natural operation feeling and excellent operability can be obtained.

The outer case 41 of the eraser 40 is used.
It is a rectangle that is easy for
The switch 45 is formed in a rectangular shape and the switch SW_A, SW_B,
SW _C, SW_DBased on the combination of detection of
Use a range based on each side and each vertex
Because it can be divided, it has a natural operation feeling and excellent operability
It can be used as the eraser 40 of the coordinate input device
Has the effect.

The erasure range EA is set on the writing panel 1 as a receiving unit.
Coil L to send to 0_A, L_B, L _C, L_DIs the predetermined
It is time-divided in period T, and it is written
Panel 10 needs to detect and process different signals at the same time.
Reduces the burden of performing complex mechanical configurations and complex processing
Thus, the configuration of the writing panel 10 can be simplified.
This has the effect.

[0088] Moreover, of the four oscillator coil, four switches _{SW A, SW B, SW C} , SW D coil _L A corresponding to the state _of, L _B, L C, to oscillate includes a _{L D} Thus, a plurality of erasure ranges EA can be transmitted to the writing panel 10 and a range corresponding to the erasure ranges can be erased, so that a more natural operation feeling and excellent operability can be achieved. There is also.

The four switches SW _A , SW _B , S
W _C, the coil oscillates in response to the state of the SW _{D L} A,
By using a maximum of two coils L for L _B , L _C , and L _D , the processing load on the writing panel 10 can be further reduced, high-speed processing can be performed, and an eraser for a coordinate input device with better followability can be achieved. There is an effect that it can be set to 40.

Although the present invention has been described based on one embodiment, the present invention is not limited to the above-described embodiment. For example, a mechanical pressure switch is used as a pressure detecting means. As described above, if the pressure can be detected by some method, such as detecting the movement of the erasing pad as the contact surface using a piezoelectric element, a pressure-sensitive diode, or an optical sensor to detect that the pressure has been applied, It can be easily inferred that various improvements and changes can be made without departing from the spirit of the present invention.

[0091]

As is apparent from the above description, according to the eraser of the coordinate input device according to the first aspect of the present invention, a plurality of pressure detecting means for detecting that the contact surface has contacted the board portion are provided. In addition, in a state where it is detected that at least one or more pressure detecting units are turned on, there is an effect that the erasing range can be specified based on the combination. Furthermore, the specified erasure range can transmit information of the erasure range to the receiving unit in a predetermined combination of a plurality of oscillation coils that generate alternating magnetic fields that can be identified from each other. Another effect is that different erase ranges can be used properly. Therefore, there is an effect that an eraser of a coordinate input device having a more natural operation feeling and excellent operability can be provided.

According to the eraser of the coordinate input device according to the second aspect of the present invention, in addition to the effect of the eraser of the coordinate input device according to the first aspect of the present invention, the shape is easy for the user to grasp and use. A rectangular contact surface, and based on the combination of the detection of the pressure detection means, the entire rectangular surface, each side,
Since it is possible to selectively use the range based on each vertex, there is an effect that an eraser of a coordinate input device having a natural operation feeling and excellent operability can be provided.

According to the eraser of the coordinate input device of the third aspect of the present invention, in addition to the effect of the eraser of the coordinate input device of the first or second aspect of the present invention, the oscillation coil for transmitting the erasure range to the receiving unit. However, since the signals are time-divided at a predetermined cycle and sequentially oscillated alternately, the receiving unit does not need to detect and process different signals at the same time, and the burden of performing a complicated mechanical configuration and complicated processing is reduced. This has the effect that the configuration can be simplified.

According to the eraser of the coordinate input device according to the fourth aspect of the present invention, in addition to the effect of the eraser of the coordinate input device of the second or third aspect of the present invention, the pressure detecting means disposed at the four corners Oscillation coils that oscillate according to the state of (2) are a maximum of two oscillation coils, so that the processing load on the receiving unit is further reduced, and high-speed processing becomes possible
There is an effect that an eraser of a coordinate input device with better followability can be provided.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a main configuration of an electronic blackboard 1 which is a coordinate input device.

FIG. 2 is an explanatory diagram showing a state in which a personal computer 100 and a printer 200 are connected to the electronic whiteboard 1 shown in FIG.

FIG. 3 is an explanatory diagram showing an internal structure of a pen 60.

FIG. 4 is an explanatory view showing each component of the writing panel main body 20;

FIG. 5A is an explanatory view showing a configuration of the loop coil 23 shown in FIG. 4 with a part thereof omitted; (B) It is explanatory drawing which shows the width | variety P1 of the loop coil 23 shown in FIG.

FIG. 6A is an explanatory view showing a part of X coils X1 to X3. 7B is a graph illustrating a relationship between a voltage ex generated in the X coils X1 to X3 illustrated in FIG. 6A and a distance in a width x direction. 7C is a graph showing a voltage difference between mutually adjacent loop coils of the X coils X1 to X3 shown in FIG.

FIG. 7A is an explanatory diagram showing a position coordinate table 58a in a graph. (B) It is explanatory drawing of the position coordinate table 58a. (C) It is explanatory drawing which shows the storage state of the detection value detected from each X coil.

FIG. 8 is an explanatory diagram showing an electrical configuration of the pen 60 shown in FIG.

FIG. 9 is an explanatory diagram showing the electrical configuration of the electronic blackboard 1 by blocks.

FIG. 10A illustrates a relationship between a pen attribute and a modulation frequency fm. (B) It is explanatory drawing which shows the signal in point A, B, and C in FIG.

11 is a flowchart showing main control contents executed by a CPU 56 shown in FIG.

FIG. 12 is a flowchart illustrating a flow of a coordinate reading process.

13 is an explanatory diagram illustrating an electrical configuration of an FSK demodulation circuit 55. FIG.

14 is an explanatory diagram showing signal waveforms appearing at various parts of the FSK demodulation circuit 55 shown in FIG.

FIG. 15A shows an output signal of a CR oscillation circuit 69e;
FIG. 9 is an explanatory diagram showing a relationship among an output signal of an LC oscillation circuit 69c, an output signal of a limiter circuit 54, and a count value K by a count circuit 55a. (B) is an explanatory diagram showing how the count value K stored in the shift register 55b shifts.

16A is an explanatory diagram showing a relationship between a threshold determination output by an absolute value comparator 55f and a determination cycle of a CPU 56. FIG. (B) It is explanatory drawing which shows a mode that the count value K by the counter 55g moves.

FIG. 17 is an FSK demodulation circuit 5 in S318 of FIG. 12;
5 is a flowchart showing a flow of processing (pen attribute detection processing 1) from a count circuit 55a to an absolute value comparator 55f constituting No. 5;

FIG. 18A is a flowchart showing the flow of processing of a counter 55g in S318 of FIG. FIG. 13B is a flowchart showing the flow of processing of the adder 55i in S318 of FIG.

FIG. 19 is a view of the eraser 40 as viewed from above.

FIG. 20 is a cross-sectional view taken along the line II of the eraser 40 shown in FIG. 19;

FIG. 21 is a schematic diagram illustrating an example of an erase range determined by a combination of ON states of switches SW _A , SW _B , SW _C , and SW _D ;

FIG. 22 is a block diagram showing a configuration of a circuit of the eraser 40.

FIG. 23 is a diagram illustrating an example of an erasing range EA on the writing surface 21a of the writing panel main body 20.

FIG. 24 is a timing chart showing a timing at which the eraser 40 oscillates a coil L and a timing at which the coil L is scanned by the writing panel 10;

FIG. 25 shows an erase pad 45 of the eraser 40 shown in FIG. 20;
FIG. 4 is a diagram showing a state in which the entire surface of the image is pressed against the writing surface 21a.

FIG. 26 shows an erase pad 45 of the eraser 40 shown in FIG. 20;
FIG. 4 is a diagram showing a state where a side connecting a corner A and a corner C is pressed against the writing surface 21a.

FIG. 27 is a schematic perspective view showing a state in which a corner A of an erase pad 45 of the eraser 40 is pressed against the writing surface 21a.

FIG. 28 is a flowchart showing a procedure for oscillating a coil L.

[29] switches _{SW A, SW B, SW C} , on the SW _D, a combination of off, the coil _L A which oscillates when _the, L _B, L C, the conversion table that associates the combination of _{L D} is there.

FIG. 30 is a flowchart showing details of the eraser process of S400 in FIG. 11;

[Explanation of symbols]

Reference Signs List 1 electronic blackboard 10 writing panel 20 writing panel main body 21a writing surface 23 loop coil 40 eraser 41 outer case 42 circuit board 43 button battery 44 inner case 45 erasing pad 46 control circuit 47 oscillation circuit 48, 48a, 48b, 48c, 48d transmission signal generator 49 the spring 56 CPU 58 ROM 59 RAM 60 pen _{SW, SW A, SW B,} SW C, SW D switches _{L, L A, L B,} L C, L D coil

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 17, 1999 (1999.11.
17)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 24

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) G06F 3/03 325 G06F 3/03 325D

Claims (4)

[Claims] A transmitting unit having an oscillation coil for generating an alternating magnetic field of a predetermined frequency; and a receiving unit having a board unit on which a plurality of loop coils capable of being magnetically coupled with the alternating magnetic field are provided. In the coordinate input device that reads the coordinates of the trajectory of the transmission unit drawn on the board unit and electronically records the coordinates, the transmission unit is brought into contact with the board unit based on the coordinates of the contacted part. An eraser for a coordinate input device for erasing an input record, wherein a plurality of oscillation coils that generate alternating magnetic fields that can be identified from each other, a contact surface that contacts the board unit, and the contact surface is the board. A plurality of pressure detecting means for detecting contact with the board portion, wherein at least one of the plurality of pressure detecting means detects that the contact surface has come into contact with the board portion; means The information erasing range of said recording identified from a combination of detection, eraser coordinate input device and transmits to the receiver by a combination of the plurality of oscillation coils. 2. The contact surface has a rectangular shape, the pressure detecting means and the oscillation coil are respectively arranged at four corners of the contact surface, and the erasing range is determined by a combination of detection by the pressure detecting means. Based on the whole rectangle, a certain range based on each side,
Alternatively, any one of the erasure ranges of a certain range based on each vertex is specified, and the oscillation coil transmits the information of the erasure range to the reception unit by oscillating the information in a specific combination. An eraser for the coordinate input device according to claim 1. 3. The coordinates according to claim 1, wherein the oscillating coil for transmitting the erasure range to the receiving unit is time-division-divided at a predetermined cycle, and sequentially oscillates. Input device eraser. 4. The coordinate input device according to claim 2, wherein a maximum of two oscillation coils are oscillated in accordance with the state of said pressure detecting means arranged at four corners. Equipment eraser.