JP2001282444A - Coordinate input device and coordinate reader - Google Patents

Abstract

(57) [Summary] [Problem] To provide a coordinate input device capable of transmitting information indicating a continuous change amount and many attributes, and to receive a signal transmitted from the coordinate input device and receive the continuous change amount and a large number of attributes. A coordinate reading device capable of detecting attributes is realized. A cycle T1 at which a first frequency f1 of a frequency-shift-modulated signal changes to a second frequency f2 is set to a different cycle depending on the color of the ink of the pen and the thickness of the pen tip. Further, the period T2 at which the second frequency f2 changes to the first frequency f1 is changed according to the pen pressure of the pen. Since the coordinate reading device can measure and determine the periods T1 and T2 using the system clock, the difference between the periods T1 is at least one period of the system clock.
Since the attributes of the pen can be detected, a great many attributes can be set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device capable of transmitting attributes such as ink color and pen tip thickness or information such as writing pressure, a position coordinate of the coordinate input device, and reading of the information. The present invention relates to a coordinate reading device that can be detected.

[0002]

2. Description of the Related Art Conventionally, for example, a coordinate input device shown in FIG. 20 has been known. FIG. 20 is an explanatory diagram showing a configuration of a conventional coordinate reading device. A coordinate reading apparatus shown in FIG. 20 includes a coordinate input sheet 91 having X1 to Xm sense coils for detecting an X coordinate and Y1 to Yn sense coils for detecting a Y coordinate. Scanning circuit 9 for sequentially scanning sense coils
2 and a detection circuit 90 for detecting an induction signal generated in the sense coil and calculating a position coordinate.

A coil 101 for generating an alternating magnetic field
When the pen (coordinate input device) 100 having the contact with the coordinate input sheet 91, an induction signal 97 is induced in the sense coil near the pen 100 by magnetic coupling with the alternating magnetic field generated from the coil 101. Guidance signal 9
7 is input to the detection circuit 90. The induction signal 97 input to the detection circuit 90 is amplified by the amplifier 93,
For example, amplitude detection is performed by the detection circuit 94. Next, A /
The D conversion circuit 95 measures the amplitude of the detected induction signal and outputs the measured value to the CPU 96. And C
The PU 96 sets the pen 10 based on the input digital value.
The position coordinates of 0 are calculated. For example, a calculation method of referring to a position coordinate table in which digital values and position coordinates are associated with each other and selecting position coordinates corresponding to the digital values is used.

As a pen provided in the coordinate reading apparatus as described above, there is known a pen that changes the frequency of an alternating magnetic field output from the pen according to the color of ink (Japanese Patent Laid-Open No. 7-160400). . This pen has a switch for switching the frequency, and the coordinate reading device detects the frequency of the alternating magnetic field output from the pen to detect the color of the ink.

[0005]

However, the above-mentioned conventional coordinate input device and coordinate reading device switch the frequency corresponding to the attribute on the pen side, and the coordinate reading device changes the attribute of the pen according to the magnitude of the received frequency. Because it is a configuration to detect,
There is a problem that a continuous change amount such as writing pressure is transmitted from a pen, and the coordinate reading device cannot receive and detect the continuous change amount. Further, since the frequency band for transmission and reception is limited, there is a problem that many attributes such as the color of the ink and the thickness of the pen tip cannot be set.

Accordingly, the present invention has been made to solve the above-mentioned problems, and there is provided a coordinate input device capable of transmitting information indicating a continuous change amount and a number of attributes, and a coordinate input device transmitting the information. It is an object of the present invention to realize a coordinate reading device capable of detecting the continuous change amount and many attributes by receiving the obtained signal.

[0007]

Means for Solving the Problems, Functions and Effects of the Invention
In order to achieve the above object, according to the first aspect of the present invention, the coordinate input device used in a coordinate reading device that detects a position coordinate of the coordinate input device based on a signal output from the coordinate input device. , A technical means of outputting a signal subjected to frequency shift keying in such a manner that intervals at which the frequency changes corresponds to a plurality of types of information is used.

That is, for example, as shown in FIG.
The period T1 (interval) at which the first frequency f1 of the frequency-shift-modulated signal changes to the second frequency f2 differs depending on the color of the ink of the pen (coordinate input device) 60 and the thickness (attribute) of the pen tip. Set the period. For example, if the thickness is black (the ink color is black and the pen tip is thick), set to 0.24 mS. If the color is red (the ink color is red and the pen tip is thick),
It is set to 0.13 mS (FIG. 10A). Then, the FSK demodulation circuit 55 (FIGS. 9 and 13) provided in the electronic blackboard (coordinate reading device) 1 measures the interval T1 of the signal transmitted from the pen 60 using a system clock (CLK), The CPU 56 determines a pen 60 based on the measured value.
Detect the attributes of Therefore, it is possible to set a very large number of attributes without being limited by the transmission and reception frequency bands.

The second frequency f2 is equal to the first frequency f2.
The cycle T2 (interval) that changes to 1 is changed according to the pen pressure of the pen 60. Since the cycle T2 can be measured by the system clock in the electronic blackboard 1 similarly to the cycle T1, even if the cycle T2 continuously changes according to the pen pressure, the continuous change amount is detected. be able to. Therefore, it is possible to detect a continuously changing pen pressure. As described above, according to the first aspect of the present invention, by outputting a frequency-shift-modulated signal in which intervals at which the frequency changes correspond to a plurality of types of information, the continuous change amount and many attributes can be reduced. It is possible to realize a coordinate input device capable of transmitting the indicated information.

According to the second aspect of the present invention, in the coordinate input device used in the coordinate reading device for detecting the position coordinates of the coordinate input device based on the signal output from the coordinate input device, the interval of the frequency change may be different. A technical means of outputting a signal subjected to frequency shift keying with a duty ratio corresponding to a plurality of types of information is used.

That is, for example, as shown in FIG.
The period (interval) at which the first frequency f1 of the frequency-shift-modulated signal changes to the second frequency f2 is T2, the first frequency f1 changes to the second frequency f2, and the first frequency again. The duty ratio (T2 / T1) when the period (interval) that changes to T1 is T1 is changed according to the pen pressure of the pen 60. Then, the FSK demodulation circuit 55 provided in the electronic blackboard (coordinate reading device) 1 measures the periods T1 and T2 of the signal transmitted from the pen 60 using a system clock, and the CPU 56 performs a measurement based on the measured value. To calculate the duty ratio (T2 / T1) and calculate the pen pressure based on the duty ratio. Therefore, it is possible to detect the continuously changing pen pressure of the pen 60. As described above, according to the second aspect of the present invention, the information indicating the continuous change amount is output by outputting the signal subjected to the frequency shift modulation in which the duty ratio of the interval at which the frequency changes corresponds to the continuous change amount. Can be realized.

According to the third aspect of the present invention, in the coordinate input device used in the coordinate reading device for detecting the position coordinates of the coordinate input device based on the signal output from the coordinate input device, the frequency change interval and A technical means of outputting a signal subjected to frequency shift keying in which the duty ratio of the interval at which the frequency changes corresponds to a plurality of types of information is used.

That is, for example, as shown in FIG.
The first frequency f1 of the frequency-shift-modulated signal changes to the second frequency f2, and the cycle T1 (interval) at which the frequency changes again to the first frequency, that is, the modulation frequency is set to the ink of the pen (coordinate input device) 60. Different intervals are set depending on the color of the pen and the thickness (attribute) of the pen tip. For example, in the case of thick black (the ink color is black and the pen tip is thick), set to 4.1 kHz,
In the case of red thickness (the ink color is red and the pen tip is thick), 7.
Set to 7 kHz. Then, the FSK demodulation circuit 55 provided in the electronic blackboard (coordinate reading device) 1 measures the period T1 of the signal transmitted from the pen 60 using a system clock, and the CPU 56 60 attributes are detected. Therefore, it is possible to set a very large number of attributes without being limited by the transmission and reception frequency bands.

The first frequency f1 is equal to the second frequency f
Period T2 when the period (interval) changing to 2 is T2
And the duty ratio of the cycle T1 (T2 / T1)
It changes according to the pen pressure of 0. Since the cycle T2 can be measured by the system clock on the electronic whiteboard 1 similarly to the cycle T1, the CPU 56 determines the duty ratio (T
2 / T1) can be calculated. Therefore, it is possible to detect the continuously changing pen pressure of the pen 60.
As described above, according to the third aspect of the present invention, a frequency-shift-modulated signal is output by associating the frequency change interval and the duty ratio of the frequency change interval with a plurality of types of information. Thus, it is possible to realize a coordinate input device capable of transmitting information indicating a continuous change amount and many attributes.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of a coordinate input device and a coordinate reading device according to the present invention will be described below with reference to the drawings. In the following embodiments, as a coordinate reading device according to the present invention, a handwriting character, a figure, or the like drawn on a writing surface is electrically read.
A so-called electronic blackboard will be described as an example, and a pen provided on the electronic blackboard will be described as an example of a coordinate input device according to the present invention. [Main Configuration of Electronic Blackboard] First, the main configuration of the electronic blackboard according to the first embodiment will be described with reference to FIGS. FIG. 1 is an explanatory perspective view showing an external appearance of a main structure of the electronic blackboard, and FIG. 2 is an explanatory diagram showing a state in which a personal computer (hereinafter abbreviated as PC) and a printer are connected to the electronic blackboard shown in FIG. is there.

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. A recess 1 having a semicircular cross section for accommodating the pen 60 is provided on the upper surface of the base 12.
2a is formed, and on the right side of the concave portion 12a, a flat portion 12b for placing the eraser 40 and the like is formed.

On the front right side of the frame 11, an operation unit 30 is provided.
Is provided. The operation unit 30 includes a speaker 31 for reproducing sounds such as an operation sound and a warning sound, and a seven-segment page number storing data indicating the contents written on the writing surface 21a (hereinafter abbreviated as writing data). 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 sending one page each time the button is pressed, and one page each time the stored writing data is pressed. Delete button 35 for writing the stored writing data to the printer 200
Printer output button 36 pressed to output to (FIG. 2)
, A PC output button 37 pressed to output the stored writing data to the PC 100 (FIG. 2), a dead battery notification LED 39 for reporting that the battery of the pen 60 is dead, and the electronic blackboard 1 to start or stop. And a power button 38 to be pressed.

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 for controlling the volume of the speaker 31 is provided, and on the right side, connectors 13b and 13a are provided. As shown in FIG. 2, the plug 13 of the connection cable 201 connected to the printer 200 is connected to the connector 13b, and the PC 13 is connected to the connector 13a.
The plug 102 of the connection cable 101 connected to 00 is connected. That is, writing data indicating the contents written on the writing surface 21a of the electronic blackboard 1 is output to the PC 100,
The content written on the electronic blackboard 1 can be viewed on the monitor 100a provided in the C100. 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.

Metal fittings 15, 15 for hanging the electronic blackboard 1 on a wall are provided at both ends at the upper end of the rear surface of the frame 11.
Is installed. In the first embodiment, the writing surface 2
The height H1 of 1a is 900 mm and the width W1 is 600 m
m. Further, the frame 11 and the base 12 are made of a synthetic resin such as polypropylene so as to be lightweight.
The total weight of the electronic blackboard 1 is 10 kg or less. Further, the eraser 40 includes a coil for generating an alternating magnetic field, an oscillation circuit, a battery, and the like.

[Network Configuration] Next, the electronic blackboard 1
FIG. 3 is a block diagram showing the configuration of a network in a case where data communication is performed between the network and another electronic whiteboard 1.
This will be described with reference to FIG. Here, a case where communication is performed between a plurality of rooms provided with the electronic whiteboard 1 in a company or between companies is described as an example. In the room 3 in the company 2, an electronic blackboard 1 and a P connected to the electronic blackboard 1
C100 and a LAN board 103 connected to the PC 100 are provided.
And the PC 100 connected to the electronic whiteboard 1 and the P
A modem 108 connected to C100 is provided. The LAN board 103 provided in each room 3 is LA
It is connected to the hub 105 by an N cable 104. The HUB 105 is connected to a server 106, and the server 106 can be connected to another company 5 via the Internet 300. The modem 108 provided in the room 4 can be connected to another company 5 from the telephone line 109 via the public switched telephone network 301. Although not shown, the other company 5 is provided with an electronic whiteboard 1 communicable via a PC, as in the company 2.

Here, the flow of data in the network will be described. Writing data stored on the electronic blackboard 1 provided in a certain room 3 is transmitted from the PC 100 to the LA.
The data is transmitted to PC 100 in room 3 designated via N board 103 and HUB 105. Then, the person who has received the data can use the monitor 100 provided in the PC 100.
a by displaying the received data on the printer 20 (FIG. 2).
The content of the received data can be viewed by printing on the paper 203 with 0 (FIG. 2). In addition, the handwritten data is stored in, for example, TIFF (Tag Image File).
The file can be attached to the electronic mail as an image file in the format (Format) and transmitted from the server 106 to another company 5 via the Internet 300. This allows
The other company 5 can see the contents of the writing data by decoding the image file attached to the e-mail sent from the company 2.

[Structure of Writing Panel Body 20] Next, the structure of the writing panel body 20 will be described with reference to FIG. FIG. 4 is an explanatory diagram showing each component of the writing panel main body 20. The 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 sense coil 23 is laid, and a plate-shaped back panel 25 are sequentially stacked. It is. In this embodiment, the writing sheet 21 is composed of the bonded PE.
The panel 22 is formed to a thickness of 0.1 mm using a T (polyethylene terephthalate) film, and the panel 22 is formed to a thickness of 3.0 mm using an acrylic resin, ABS (acrylonitrile-butadiene-styrene copolymer), PC (polycarbonate), or the like. Is formed. Also, the mounting panel 24
Is made of a foamed resin material such as styrofoam and has a thickness of 4
The back panel 25 is formed of a conductive material such as aluminum and has a thickness of 1.0 mm. Further, the entire thickness of the frame 11 for holding each end of the writing panel main body 20 is 50 mm.

[Configuration of Sense Coil 23] Next, the configuration of the sense coil 23 will be described with reference to FIG. FIG. 5A is an explanatory view showing a configuration of the sense coil 23 shown in FIG. 4 with a part thereof being omitted, and FIG.
It is explanatory drawing which shows the width | variety and overlap pitch of the sense coil 23 shown to (A). In the following description, among the sense coils 23, the sense coils arranged in the X-axis direction are referred to as X coils, and the sense coils arranged in the Y-axis direction are referred to as Y coils. As shown in FIG. 5A, in the X-axis direction, the X and Y coordinates of the (X, Y) coordinates of the pen 60 and the eraser 40 are set.
There are m X coils X1 to Xm for detecting coordinates, and Y coils for detecting Y coordinates are arranged in the Y-axis direction.
N coils 1 to Yn are arranged orthogonally to the X coil. The X coil and the Y coil are each formed in a substantially rectangular shape, and the length of the long side of the rectangular portion is P
2Y and P2X.

As shown in FIG. 5B, the X coils are each formed to have a width (the length of the short side of the rectangular portion) P1, and adjacent X coils are respectively overlapped at a pitch of P1 / 2. Have been. Each Y coil is also formed to have a width P1, and adjacent Y coils are respectively overlapped at a pitch of P1 / 2. Also, each terminal 23a of the X coil
Are 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 (FIG. 9). In the first embodiment, P1 =
50 mm, P2X = 680 mm, P2Y =
980 mm. Also, m = 22 and n = 33. Further, the X coil and the Y coil both have an insulating coating layer (for example, an enamel layer) on the surface and have a diameter of 0.1 mm.
It is formed of a 35 mm copper wire. FIG.
In (A), the sides of each coil are drawn so as not to overlap in order to make the arrangement of the coils easy to understand, but actually, for example, each Y coil Y is disposed on the long side of the X coil X1.
The short sides of 1, Y2, Y3,... Further, the terminals 23a and 23b are configured so that the interval therebetween is minimized.

[Position coordinate table] Next, the writing surface 21a
A position coordinate table for detecting the position coordinates of the upper pen 60 will be described with reference to FIGS. FIG.
6A is an explanatory view showing a part of the X coils X1 to X3, and FIG. 6B is a diagram illustrating the X coils X1 to X3 shown in FIG.
FIG. 6C is a graph showing the relationship between the voltage generated in FIG. 6A and the distance in the width direction, and FIG. 6C shows the X coils X1 to X shown in FIG.
3 is a graph showing a voltage difference between three mutually adjacent sense coils. 7A is an explanatory diagram showing the position coordinate table as a graph, FIG. 7B is an explanatory diagram of the position coordinate table, and FIG. 7C is an explanatory diagram of the corrected position coordinate table. is there.

In FIG. 6, the center lines of the X coils X1, X2, and X3 are C1, C2, and C3, respectively.
1, X2, and X3 are represented by ex1, ex, respectively.
2, ex3. As shown in FIG.
1 to ex3 are the center C1 to C3 of the sense coil, respectively.
, And has a monomodal property which becomes smaller as approaching the end in the longitudinal direction. In addition, each coil is overlapped at P1 / 2 such that its own null point, that is, points N1 to N6 where the voltages ex1 to ex3 become 0 are outside the center of the adjacent coil. Further, as shown in FIG. 6C, the voltage difference between the mutually adjacent sense coils of the X coils X1 to X3 has a maximum value on the centers C1 to C3 of the sense coils, respectively. The graph becomes zero at the midpoint between the long side of the sense coil and the midpoint of the portion where the adjacent sense coil overlaps.

For example, in FIG. 6C, (ex2-
ex1) (a portion indicated by a solid line) is a distance from the center line C2 of the X coil X2 to an intermediate point Q1 of a portion where the X coil X2 is overlapped (（of the overlap pitch, that is, P1 / 4). And the relationship between (ex2-ex1). now,
If the pen 60 exists at the point Q2, (ex2-ex
If 1) is detected, the distance ΔQ from the center line C2 to the point Q2
Since 2X can be detected, the X coordinate of the point Q2 can be obtained. For example, in FIG. 6C, (ex2-ex
When the voltage difference (ex2-ex1) is converted to 8-bit digital data from the portion (portion drawn by the solid line) showing the characteristic of 1), a graph shown by the solid line in FIG. 7A is obtained.
When this graph is converted into a table format, a position coordinate table 58a shown in FIG. 7B is obtained. The position coordinate table 58a is stored in the ROM 58 (FIG. 9) or the like, and is used for calculating the position coordinates of the pen 60. FIG.
The graph shown by the dashed line in (A) shows the pen pressure and FS
The relationship with the demodulation count number by the K demodulation circuit 55 (FIG. 9) is shown, and this relationship is also stored in the ROM 58 in a table format like a position coordinate table 58a.

Next, the main configuration of the pen 60 will be described with reference to FIG. FIG. 8A is an explanatory diagram showing the internal structure of the pen 60, and FIG. 8B is an explanatory diagram showing the electrical configuration of the pen 60 shown in FIG. 8A. [Internal Structure of Pen 60] The pen 60 is provided with a cylindrical body 61a and a lid 61c detachably attached to the rear end of the body 61a. Inside the body portion 61a, 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 an oscillation for generating an alternating magnetic field from the coil L1. A circuit board 69 on which circuits and the like are mounted and a battery 70 for supplying power to the circuit board 69 are provided. In addition, the ink cartridge 6
Between the circuit board 3 and the circuit board 69, there is provided a push button type switch 67 for supplying and shutting off power to the oscillation circuit and the like. The switch 67 is connected to the pen tip 62
Is pressed against the writing surface 21a (FIG. 1), and turns on when the ink cartridge 63 moves in the direction shown by the arrow F1, and turns off when it returns in the direction shown by the arrow F2. That is, the pen 60
As a result, an alternating magnetic field is generated from the coil L1 when writing is performed on the writing surface 21a. Further, between the switch 67 and the circuit board 69, the writing surface 21a of the pen point 62 is provided.
A pen pressure sensor 68 for detecting a pressing force on (FIG. 1), that is, a pen pressure is provided. In this embodiment,
The pen pressure sensor 68 has a long life and is small,
Since it is preferable to use a pen that frequently performs pen-down and pen-up, a pressure-sensitive sensor whose resistance value changes according to the pen pressure is used. Further, among the pressure-sensitive sensors, a film sensor is used because it is thin and does not take up space inside the pen. The structure of the film sensor is such that a carbon film 68c is pressed against an electrode pattern 68b printed on a PET film 68a with a silver paste, as shown in FIG.

[Electrical Configuration of Pen 60] As shown in FIG. 8B, the circuit mounted on the circuit board 69 has different modulation frequencies for each pen attribute such as ink color and pen tip thickness. Is set, an LC oscillation circuit 69c that oscillates a carrier that carries a signal oscillated from the CR oscillation circuit 69e, and an oscillation frequency of the LC oscillation circuit 69c is determined by a modulation frequency of the CR oscillation circuit 69e. FSK (Frequency Shift Keyin)
g) FSK circuit 69d that performs modulation, that is, frequency shift modulation
It is composed of The oscillation frequency of the carrier is determined by the inductance L1 and the capacitors C1, C2, and C3 constituting the LC oscillation circuit 69c.
The capacitor C5 and the resistor R constituting the R oscillation circuit 69e
2. Variable resistor R3 and diode D of pen pressure sensor 68
1 and D2. The frequency shift of the carrier oscillation frequency is determined by the capacitance of the capacitor C4 of the FSK circuit 69d. Further, the cycle T2 (FIG. 14) indicating the pen pressure is changed by the variable resistor R3.

The relationship between the attribute of the pen 60 and the modulation frequency fm is set as shown in FIG. 10A for explaining the relationship. In FIG. 10A, “thin” indicates that the pen tip 62 (FIG. 8A) is thin, and “thick” indicates that the pen tip 62 is thick. For example, a black pen indicates a pen having a thick pen tip and using black ink. The eraser 40 also has a built-in coil, and calculates the erasure range of the eraser 40 based on the signal generated in the sense coil by the alternating magnetic field generated from the coil.
The modulation frequency fm is also assigned to the eraser 40, and the pen 60
Is identified.

When the switch 67 is turned on, the power of the battery 70 is supplied to each circuit, and the output of the integrated circuit IC4 of the CR oscillation circuit 69e is output to the MOS F of the FSK circuit 69d.
The ET gate is switched, and the carrier oscillated from the LC oscillation circuit 69c is frequency-shift-modulated by the signal oscillated from the CR oscillation circuit 69e. In the first embodiment, the center frequency of the carrier is 410 kHz and the frequency deviation is ± 20 kHz. In the first embodiment, the resistance R1 is 1 MΩ, and the variable range of the variable resistance R3 is 100 KΩ to 1 MΩ. Capacitor C1, C
4 and C5 are 0.1 μF, 0.0015 μF,
100 pF, and both capacitors C2 and C3 are 0.0
033 μF. Further, the battery 70 is LR44 and the voltage is about 1.5V.

[Main Electrical Configuration and Control Contents of Electronic Whiteboard 1] Next, main electrical configurations 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 blackboard 1 by blocks, and FIG.
FIG. 11 is an explanatory diagram showing a signal at point C, and FIG. 11 is a flowchart showing main control contents executed by the CPU 56 shown in FIG. C provided in the control device 50 shown in FIG.
When the PU 56 detects that the power button 38 (FIG. 1) is turned on (step (hereinafter abbreviated as S) 100: Ye
s), initialization such as loading the control program and the position coordinate table 58a (FIG. 7B) stored in the ROM 58 into the work area of the RAM 59 is performed (S20).
0), a coordinate reading / pen attribute detection / pen pressure detection process is executed (S300).

[Coordinate reading process] Here, the coordinate reading process will be described with reference to the flowchart of FIG. The CPU 56 outputs a coil selection signal A (FIG. 10 (B)) for sequentially selecting the X coils X1 to Xm to the X coil switching circuit 50a via the input / output circuit (I / O) 53, so that the X coil 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 (FIG. 9), and the amplified signal (FIG. 10B) is obtained. An unnecessary band is filtered by a band-pass filter (BPF) 50 d, and the amplitude is detected by an amplitude detection circuit 51. Subsequently, the amplitude-detected signal (FIG. 10B) is A / D
The signal is converted into a digital signal corresponding to the amplitude, that is, the voltage value by the conversion circuit 52,
56 is input.

Subsequently, the CPU 56 determines that the pen 60 has been detected (S304: Yes), scans the X coils X1 to Xm, and sets the voltage values e1 to em indicated by the input digital signals in FIG. 7C. As shown in (3), 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.
The RAM 59 selects the coil number (hereinafter referred to as max) of the X coil that has generated the voltage value emax.
To memorize. For example, as shown in FIG. 6, the pen 60 exists at the position Q2, and as shown in FIG. 6B, voltage values e1, e2, e3 from the X coils X1, X2, X3, respectively.
Occurs, the maximum voltage value e2 is selected, and the coil number 2 of the X coil generating the voltage value e2 is set to max.
In the RAM 59. Then, the CPU 56 sets e
The larger of the voltage values emax ± 1 on both sides of max is determined, and the coil number (hereinafter, referred to as max2) of the X coil that generated the determined voltage value is stored in the RAM 59.

In the example shown in FIG. 6B, the larger one of the voltage values e3 and e1 on both sides of e2 is determined, and the larger e1 is determined.
The coil number 1 of the X coil that generated 1 is stored in the RAM 59 as max2. Subsequently, the CPU 56
By comparing the coil numbers max and max2 stored in No. 9 with each other, it is determined whether the coil number max2 exists in the plus direction or the minus direction of the X axis from the coil number max. Then, if max2 ≧ max, the variable S
If IDE is set to 1 and max2 <max,
Set the variable SIDE to -1. In the example shown in FIG. 6B, since max = 2 and max2 = 1, max2
<Max, and the variable SIDE is set to (−1).
Subsequently, the CPU 56

DIFF = e (max) −e (max2) (1)

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

X1 = (P1 / 2) × max + OFFSET × SIDE (2)

Is calculated to obtain an 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. 6B, the expression (2)
1 = (P1 / 2) × 2 + (e2-e1) × (−1), and the X coordinate of the position Q2 corresponds to (e2-e1) in the negative direction of the X axis from the center line C2 of the X coil X2. The coordinates are distances, for example, ΔQ2X apart. And the CPU 56
The scanning of each Y coil is executed (S310), and the voltage value detected from each Y coil is stored in the Y coil voltage value storage area of the RAM 59 (S312). Then CPU5
6 calculates the Y coordinate of the pen 60 using the same method as the calculation of the X coordinate in S308 described above (S314).

[Detection of pen attribute and pen pressure] Next, the CP
The electrical configuration and control for U56 to detect pen attributes and pen pressure will be described with reference to FIGS. FIG. 13 is an explanatory diagram showing an electrical configuration of the FSK demodulation circuit 55 (FIG. 9). FIG. 14 shows an output signal (hereinafter, referred to as a carrier signal) of an LC oscillation circuit 69c of the pen 60 and a CR oscillation circuit 69e. FIG. 4 is an explanatory diagram showing an output signal (hereinafter, referred to as a CR signal). FIG. 14 (A)
FIG. 14B is an explanatory diagram showing a carrier signal and a CR signal when writing is performed with a large pen pressure using the black pen 60 and a small pen pressure. FIG. FIG. 4 is an explanatory diagram showing a carrier signal and a CR signal in a case where writing is performed with a small writing pressure and a case where writing is performed with a small writing pressure. FIG. 15 is an explanatory diagram showing signal waveforms appearing at various parts of the FSK demodulation circuit 55 shown in FIG. FIG. 16A is an explanatory diagram showing a relationship among a CR signal, a carrier signal, an output signal of the limiter circuit 54 (hereinafter, referred to as a limiter output signal), and a count value of the count circuit 55a (FIG. 13). . FIG. 16B is an explanatory diagram showing how the count value stored in the shift register 55b (FIG. 13) shifts. FIG. 17 is a flowchart showing the flow of processing (pen attribute and pen pressure detection processing) from the count circuit 55a to the counter 55g constituting the FSK demodulation circuit 55. The carrier signal shown in FIG. 16A has, for example, a center frequency of 410 kHz and a frequency deviation of ± 20 kHz as described above. However, in FIG. The deviation is exaggerated. Also, here
It is assumed that a black pen 60 is used.

First, the characteristics of the FSK demodulation circuit 55 for detecting pen attributes and pen pressure will be described with reference to FIG. In the example shown in FIG. 16A, the carrier signal is modulated at a high frequency (for example, 430 kHz) during the low level of the CR signal, and is modulated at a low frequency (for example, 390 kHz) during the high level. .
Therefore, assuming that the period of the limiter output signal while the CR signal is at a low level is TB, the period of the limiter output signal while the CR signal is at a high level is TC longer than TB. Therefore, the count value k of 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. The time from when the count value k changes from small to large to the next change from large to small is CR
Since the period T1 (FIG. 14) of the CR signal can be obtained by measuring the half period from the rise to the fall of the signal, the pen attribute can be detected. Also, since the time from when the count value k changes from large to small to the next change from small to large corresponds to a half cycle from the fall to the rise of the CR signal, if the half cycle is measured, Period T2 of CR signal (FIG. 14)
Can be obtained, so that the pen pressure can be detected.

Here, the outline of the operation of each component of the FSK demodulation circuit 55 will be described. The count circuit 55a measures the count value k, shift register 55b, first weighted average circuit 55c, and second weighted average circuit 55d. , Subtractor 55e
The comparator 55f detects the change timing of the count value k, and the counter 55g measures the cycle in which the count value k changes using a system clock (CLK). Then, the CPU 56 detects the pen attribute and the pen pressure based on the count value output from the counter 55g (S318).

Next, the operation of the FSK demodulation circuit 55 will be described in detail. The carrier signal output from the band-pass filter 50d is supplied to the limiter circuit 54 as shown in FIG.
And output to the FSK demodulation circuit 55. Then, the FSK demodulation circuit 55
Detects the rise of the limiter output signal (see FIG. 17).
S10: Yes), the counting of the cycle of the limiter output signal is started using the system clock (CLK) (S1).
2) When the next rising of the limiter output signal is detected (S14: Yes), the count value k is set to the shift register 5
5b (S16), and resets the count value k (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 55b
Is the limiter output signal 1 as shown in FIG.
The count value k for the cycle is stored for eight cycles of k1 to k8,
Every time the newest count value k is fetched, the oldest count value k is discarded, and each count value k is shifted by one. The first weighted averaging circuit 55c includes a shift register 5
The weighted average value from the newest count value stored in 5b to the third newest count value is calculated, and the weighted average value (hereinafter, referred to as the first weighted average value) is calculated by the subtractor 5
Output to 5e. The second weighted average circuit 55d calculates a weighted average value from the oldest count value to the third oldest count value stored in the shift register 55b, and calculates the weighted average value (hereinafter, referred to as a second weighted average value). Is called)
Is output to the subtractor 55e.

As described above, since the count values counted at a time interval are weighted and averaged by the weighted averaging circuit, even if a certain count value is affected by noise, the influence of the noise on the count value to be obtained is reduced. can do. 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,
When the first weighted average circuit 55c calculates the weighted average value of the count values k6 to k8 shown in FIG. 16A and the second weighted average circuit 55d calculates the weighted average value of the count values k1 to k3, the count value Among the counts k6 to k8, the count values k7 and k8 are obtained by counting the period TC longer than the period TB of the limiter output signal, and thus the first weighted average value is larger than the second weighted average value. Therefore, the first
If it is detected that the weighted average value has become larger than the second weighted average value, it is possible to detect the rising edge (change point of the cycle) of the CR signal. Conversely, if it is detected that the first weighted average is smaller than the second weighted average,
It is possible to detect the fall of the R signal (change point of the cycle). The first weighted averaging circuit 55c and the second weighted averaging circuit 55d each provide a frequency (LC
The determination is made based on the ratio between the oscillation frequency of the oscillation circuit 69c) and the modulation frequency, and the complexity of the circuit. Further, the count value held by the shift register 55b, that is, the number of periods of the limiter output signal is determined by the ratio of the system clock frequency to the frequency of the carrier signal, and the system clock frequency can sufficiently discriminate a change in the frequency of the carrier signal. The size is set to (for example, 16 MHz which is about 40 times).

Next, the processing from the absolute value comparator 55f to the counter 55g will be described. The absolute value comparator 55f compares the difference Δm with a preset threshold value m1, determines whether or not the difference Δm is equal to or larger than the threshold value m1 (S22 in FIG. 17). Threshold m
If it is determined that it is 1 or more (S22: Yes), S20
It is determined whether or not the difference Δm calculated in is positive (S24). Here, when the difference Δm is positive, (S2
4: Yes), a falling flag indicating the falling of the CR signal is set (S26), and if the difference Δm is not positive, that is, negative (S24: No), the rising indicating the rising of the CR signal is performed. Set the flag (S2
8). For example, assuming that the count value of the shorter cycle TB of the limiter signal shown in FIG. 16A by the count circuit 55a is 10, the count value of the cycle TC is 16, and the threshold value m1 is 2, the count values k1 to k6 are Since both are 10, the first weighted average value = (k1 + k2 + k3) / 3 =
It becomes 10. The count values k7 and k8 are both 1
6, the second weighted average value = (k6 + k7 + k8)
/ 3 = 42/3 = 14, and the difference Δm = 10−14 = −
Since it is 4 (the difference Δm is negative), the rising flag is set (S28).

Subsequently, the threshold judgment output is changed from the low level to the high level (S30). That is, it is determined that the cycle of the limiter output signal has changed (a falling edge or a rising edge of the CR signal has been detected).
In the above example, (absolute value of difference Δm = 4)> (threshold value m1
= 2), the threshold determination output changes from low level to high level (S30). When the calculation range of the first weighted averaging circuit 55c and the second weighted averaging circuit 55d reaches a portion that has passed through the edge of the CR signal, the period of the limiter output signal becomes constant. Since the weighted average value of the cycle count value is calculated, the subtraction value by the subtractor 55e becomes 0, and the threshold value judgment output becomes a low level state.

The counter 55g counts the second interval in which the judgment output of the absolute value comparator 55f has become high level by using the system clock (CLK2) (S32). Subsequently, the count value is set to S26 or S
The data is output to the CPU 56 via the input / output circuit (I / O) 53 together with the flag data set in step 28 (S3).
4) The flag set in S26 or S28 is reset (S36). Then, the CPU 56 detects a pen attribute based on the input count value and flag data (S318 in FIG. 12). Subsequently, the pen pressure is detected (S
320). For example, if the flag data input first from the counter 55g (FIG. 13) is a falling flag and the flag data input next is a rising flag, the count value input between the two flag data is
This means the pen attribute indicated by the period T1 of the CR signal (FIG. 14). For example, when the count value is 245, the pen attribute is detected to be black (FIG. 10A).

The CPU 56 detects the pen pressure based on the input count value and flag data (S32).
0). For example, when the flag data input first from counter 55g (FIG. 13) is a falling flag and the flag data input next is a rising flag, the count value input between the two flag data is C
This means the pen pressure indicated by the period T2 of the R signal (FIG. 14). The CPU 56 refers to a pen pressure table (not shown) stored in the RAM 59 and detects a pen pressure associated with the count value. And
The CPU 56 stores the pen attribute, the pen pressure, and the XY coordinates in a predetermined storage area of the RAM 59 in association with each other. The writing data stored in this manner is stored in, for example, the printer 20.
0 (FIG. 2) and printed. Also, the PC 100
Is output to the monitor 100a (FIG. 2). For example, in the example described above, a touch corresponding to the black thickness and the detected pen pressure (for example, the density of the locus is high or low)
Printed or displayed on That is, the writing data can be reproduced according to the attribute of the pen 60.

Returning now to the description of FIG.
56 is a page return button 33, a page forward button 34
When the erase button 35 is pressed, page processing such as returning, sending, or erasing the stored writing data in page units is performed (S400). Furthermore, CP
U56 includes various buttons provided on the operation unit 30 (FIG. 1)
The switching signal generated by the operation of I / F circuit 5
7 (FIG. 9), the page storing the position coordinate data stored in the RAM 59 is sent or returned in page units, or page processing such as erasing the position coordinate data in page units is executed. (S40
0). Further, the CPU 56 executes a data output process of converting the position coordinate data of the target page from the position coordinate data stored in the RAM 59 into an appropriate format and outputting the converted data to the PC 100 or the printer 200 (FIG. 2) ( S500).

Further, the CPU 56 operates the audio circuit 31a based on a switching signal generated when various buttons are pressed, and generates an operation sound such as "P" or "P" from the speaker 31. Is executed (S600). Further, the CPU 56 calculates the wiping locus of the eraser 40 based on the voltage generated in the X coil and the Y coil by the alternating magnetic field generated from the coil built in the eraser 40, and stores the calculated position coordinate data in the wiping locus in the RAM 59. An eraser process for deleting from (FIG. 9) is executed (S700).

As described above, if the pen 60 of the first embodiment is used, the period T1 at which the first frequency f1 of the carrier signal changes to the second frequency f2 is set to a different period depending on the attribute of the pen 60. be able to. Moreover, the electronic whiteboard 1 measures the period T1 using the system clock,
Since the attribute of the pen 60 can be detected based on the measured value, the attribute of the pen 60 can be detected if the difference of the cycle T1 is at least one cycle of the system clock. Attribute can be set. Further, by using the pen 60 of the first embodiment, the period T2 at which the second frequency f2 changes to the first frequency f1 can be changed according to the pen pressure of the pen 60. Moreover, since the cycle T2 can be measured by the system clock on the electronic whiteboard 1 in the same manner as the cycle T1, when the cycle T2 is continuous according to the pen pressure, the continuous change amount is detected at a resolution corresponding to the system clock. can do.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 4 is an explanatory diagram showing a pen carrier signal and a CR signal. FIG. 18A is an explanatory diagram showing a carrier signal and a CR signal when writing is performed with a large pen pressure with a black pen and when writing is performed with a small pen pressure.
(B) is an explanatory view showing a carrier signal and a CR signal when writing is performed with a large pen pressure with a red pen and when writing is performed with a small pen pressure. In the pen according to this embodiment, the attribute information of the pen is set to the modulation frequency (period T1), and the duty ratio (T2 / T1) when the period at which the first frequency f1 changes to the second frequency f2 is T2. )
Is changed according to the pen pressure of the pen. And electronic blackboard 1
The FSK demodulation circuit 55 provided in the CPU measures the periods T1 and T2 of the signal transmitted from the pen using the system clock, and the CPU 56 calculates the duty ratio (T2 / T1) based on the measured value. The pen attributes are calculated based on the cycle T1, and the pen pressure is calculated based on the duty ratio.

As described above, if the pen according to the second embodiment is used, the modulation frequency (period T1) of the carrier signal can be set at different intervals depending on the attribute of the pen. In addition, the electronic whiteboard 1 can measure the modulation frequency using the system clock and detect the pen attribute based on the measured value. Therefore, the difference in the cycle T1 is at least one cycle of the system clock. For example, since the attributes of the pen can be detected, a great number of attributes can be set. Also, if the pen of the second embodiment is used, the duty ratio (T2 / T1) between the period T2 at which the first frequency f1 changes to the second frequency f2 and the period T1
Can be changed according to the pen pressure of the pen. Moreover, the duty ratio can also be measured by the system clock on the electronic whiteboard 1 in the same manner as the period T1, and if the duty ratio continuously changes according to the pen pressure, the continuous change amount corresponds to the system clock. It can be detected at the resolution.

In each of the above embodiments, the pen color is described by taking the ink color and the pen tip thickness as an example. However, an ID code for identifying the pen user is set as the attribute. You can also. Further, in each of the above-described embodiments, a pressure-sensitive sensor has been described as an example of the pen pressure sensor 68, but a piezoelectric element may be used. further,
In the embodiments described above, two frequencies f1 and f2 are used, but three or more frequencies may be used. FIG. 18 (C)
By changing the interval at which f2 changes from f2 to f3, other attributes such as a solid line and a dotted line can be similarly identified. In this case, a multi-level signal whose amplitude also changes may be used as the CR signal. By combining the intervals at which the plurality of frequencies change and the duty ratio, many attributes can be transmitted efficiently. By the way, the pen 60 corresponds to the coordinate input device according to the present invention, and the electronic blackboard 1 corresponds to the coordinate reading device. The pen pressure sensor 6
Reference numeral 8 corresponds to the pen pressure detecting means, and the attributes of the pen and the pen pressure correspond to a plurality of types of information.

[Brief description of the drawings]

FIG. 1 is an external perspective explanatory view showing a main configuration of an electronic blackboard according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state where a PC and a printer are connected to the electronic whiteboard shown in FIG. 1;

FIG. 3 is an explanatory diagram showing a block diagram of a network configuration when data communication is performed between the electronic whiteboard 1 and another electronic whiteboard 1;

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

5 (A) is an explanatory view showing a configuration of the sense coil 23 shown in FIG. 4 with a part thereof being omitted, and FIG. 5 (B) is a diagram showing the width of the sense coil 23 shown in FIG. 5 (A). It is explanatory drawing which shows an overlap pitch.

6 (A) is an explanatory view showing a part of X coils X1 to X3, and FIG. 6 (B) is a diagram showing voltages and width directions generated in X coils X1 to X3 shown in FIG. 6 (A). 6 (C) is a graph showing a voltage difference between mutually adjacent sense coils of the X coils X1 to X3 shown in FIG. 6 (A).

FIG. 7A is an explanatory diagram showing the relationship between position coordinates and DIFF, and the relationship between pen pressure and demodulation count; FIG. 7B is an explanatory diagram of a position coordinate table;
FIG. 7C is an explanatory diagram showing a storage state of the voltage value detected from each X coil.

8A is an explanatory diagram showing an internal structure of a pen 60, and FIG. 8B is an explanatory diagram showing an electrical configuration of the pen 60 shown in FIG. 8A.

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

10A is an explanatory diagram illustrating a relationship between an attribute of a pen 60 and a modulation frequency fm, and FIG. 10B is a diagram illustrating FIG.
FIG. 4 is an explanatory diagram showing signals at points 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 executed by the CPU 56 in S300 of FIG. 11;

13 is an explanatory diagram showing an electrical configuration of the FSK demodulation circuit 55 shown in FIG.

14A is an explanatory diagram showing a carrier signal and a CR signal when writing is performed with a large pen pressure using a black pen 60 and when writing is performed using a small pen pressure; FIG. FIG. 4 is an explanatory diagram showing a carrier signal and a CR signal in a case where writing is performed with a large writing pressure with a red pen 60 and a case where writing is performed with a small writing pressure.

FIG. 15 is an explanatory diagram showing signal waveforms appearing at various parts of the FSK demodulation circuit 55 shown in FIG.

FIG. 16A is an explanatory diagram showing a relationship among a CR signal, a carrier signal, a limiter output signal, and a count value of a count circuit 55a, and FIG. 16B is stored in a shift register 55b. FIG. 7 is an explanatory diagram showing a state in which a counted value is shifted.

FIG. 17 is a flowchart showing the flow of processing (pen attribute and pen pressure detection processing) from a count circuit 55a to a counter 55g that constitute the FSK demodulation circuit 55.

FIG. 18A is an explanatory diagram showing a carrier signal and a CR signal when writing is performed with a black pen at a large writing pressure and at a low writing pressure;
FIG. 18B is an explanatory diagram showing a carrier signal and a CR signal when writing is performed with a large pen pressure using a red pen and when writing is performed using a small pen pressure.
(C) is an explanatory diagram showing a carrier signal and a CR signal in a case where writing is performed by a red pen with a small writing pressure by a solid line and in a case where writing is performed by a red pen with a small writing pressure with a dotted line.

FIG. 19 is a plan view showing the structure of a film sensor as the pen pressure sensor 68.

FIG. 20 is an explanatory diagram showing a configuration of a conventional coordinate reading device.

[Explanation of symbols]

 1 electronic blackboard (coordinate reading device) 60 pen (coordinate input device) 68 pen pressure sensor (pen pressure detecting means)

Claims (6)

[Claims] 1. A coordinate input device used in a coordinate reading device for detecting a position coordinate of the coordinate input device based on a signal output from the coordinate input device, wherein an interval at which a frequency changes corresponds to a plurality of types of information. A coordinate input device for outputting a signal subjected to frequency shift keying. 2. The coordinate input device for use in a coordinate reading device for detecting a position coordinate of the coordinate input device based on a signal output from the coordinate input device, wherein a duty ratio of an interval at which a frequency changes is set to a plurality of types of information. A coordinate input device for outputting a signal subjected to frequency shift keying in accordance with the above. 3. The coordinate input device for use in a coordinate reading device for detecting a position coordinate of the coordinate input device based on a signal output from the coordinate input device, wherein a duty of an interval at which the frequency changes and an interval at which the frequency changes are provided. A coordinate input device for outputting a signal subjected to frequency shift keying with a ratio corresponding to a plurality of types of information. 4. A writing pressure detecting means for detecting writing pressure, wherein the plurality of types of information include at least attribute information of a coordinate input device and writing pressure information indicating a writing pressure detected by the writing pressure detecting means. The coordinate input device according to any one of claims 1 to 3, wherein 5. The apparatus according to claim 4, wherein said writing pressure detecting means detects a change in writing pressure as a continuous amount, and changes a duty ratio of an interval at which said frequency changes in accordance with the writing pressure information. The coordinate input device described in. 6. A signal output from the coordinate input device according to any one of claims 1 to 5, and demodulated to detect at least position coordinates of the coordinate input device and the plurality of types of information. A coordinate reading device.