JPH05233129A - Coordinate reader - Google Patents

Abstract

PURPOSE:To easily transmit the switch state of a coordinate indicator to a tablet main body and to prolong the life of a battery in the coordinate indicator loading the battery. CONSTITUTION:An oscillation control circuit 12a changes the oscillation frequency of a CR oscillation circuit by the opening/closing of a switch 123. Thus, an oscillation circuit 11 intermittently oscillates and intermittently generates a magnetic field at a period decided by the opening/closing of the switch 123 from a coil 102. Thus, a tablet main body-side counts a period when the generation of the magnetic field from the coordinate indicator stops, and the opening/ closing state of the switch 123 in the coordinate indicator can be detected by the count value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate reading device for inputting coordinates to an information processing device such as a computer, and more particularly to a coordinate reading device applying an electromagnetic induction phenomenon.

[0002]

2. Description of the Related Art As a conventional coordinate reading device, there is JP-A-51-138124 by the present applicant. This coordinate reading device sequentially detects an induction signal induced to a plurality of sense lines laid along the XY orthogonal coordinate axes of the tablet body by the alternating magnetic field generated by the coordinate indicator, and detects the magnitude of the induction signal of each sense line. The coordinates were determined by comparing the heights. Furthermore, the frequency of the alternating magnetic field generated by the coordinate indicator is changed by operating the switch of the coordinate indicator, and the state of the switch of the coordinate indicator is detected by detecting the frequency of the induction signal on the tablet body side. It was

In other coordinate reading devices, the switch state of the coordinate indicator is detected by applying various modulations to the alternating magnetic field generated by the coordinate indicator and demodulating it on the tablet body side. There are also things.

[0004]

However, in this conventional coordinate reading device, the battery life of the coordinate indicator is short because the coordinate indicator incorporates a battery as an energy source and an alternating magnetic field is constantly generated from the coordinate indicator. It was Furthermore, since the frequency of the alternating magnetic field is changed depending on the switch state of the coordinate indicator, the detected induction signal is indicated by the coordinate indicator due to the change of the magnetic coupling coefficient between the coordinate indicator and the tablet body or the characteristics of the bandpass filter of the tablet body. Since it changes depending on the switch state of the vessel, it is necessary to design in consideration of these.

Further, in another conventional coordinate reading device,
It has a drawback that the circuit becomes complicated because a modulation circuit and a demodulation circuit are required. An object of the present invention is to improve the above-mentioned conventional drawbacks by easily transmitting the switch state of the coordinate indicator to the tablet body, and further by reading the coordinate indicator with a longer battery life of the coordinate indicator equipped with a battery. To provide a device.

[0006]

In order to solve the above-mentioned conventional problems, the present invention detects a coordinate indicator for generating a magnetic field and a magnetic field generated by the coordinate indicator to detect a designated position of the coordinate indicator. In a coordinate reading device including a tablet main body, the coordinate indicator is an oscillation circuit,
An oscillation control circuit that controls an oscillation period and a stop period of oscillation of the oscillation circuit and a magnetic field generation circuit that generates a magnetic field by an excitation signal output from the oscillation circuit are provided, and the tablet main body is provided with the coordinate indicator. A magnetic field detecting circuit for detecting a generated magnetic field, coordinate calculating means for calculating coordinates by the magnetic field detected by the magnetic field detecting circuit, and state detecting means for detecting an oscillation state of the oscillation circuit of the coordinate indicator are provided. It is a composition.

[0007]

In the coordinate reading apparatus according to the present invention, an oscillation period and a stop period of the oscillation of the oscillation circuit of the coordinate indicator are provided to intermittently generate a magnetic field from the coordinate indicator, so that the battery of the coordinate indicator equipped with the battery is installed. In addition to extending the life of the tablet, the tablet itself detects the magnetic field during the oscillation period of the oscillation circuit to obtain the coordinates, and the oscillation circuit oscillation period or stop period or its cycle that changes depending on the switch circuit of the coordinate indicator. The state of the switch circuit or the like of the coordinate indicator can be detected by detecting.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of a coordinate reading device according to the present invention. In the figure, 1 is a coordinate indicator, 2 is a tablet body, 10 is a magnetic field generation circuit for generating a magnetic field c from the coordinate indicator 1, 11 is an oscillation circuit for supplying an excitation signal to the magnetic field generation circuit 10, and 12 is an oscillation circuit 11 The oscillation control circuit for controlling the oscillation period and the stop period of the oscillation of 20 is a magnetic field detection circuit for detecting the magnetic field c generated from the coordinate indicator 1, and 21 is a coordinate for calculating coordinates from the magnetic field detected by the magnetic field detection circuit 20. It is a tablet control circuit having a calculating means 22 and a state detecting means 23 for detecting the state of the coordinate indicator 1.

FIG. 2 shows a detailed circuit diagram of the coordinate indicator 1. The oscillation control circuit 12 is a CR oscillation circuit using a well-known CMOS inverter, and includes a capacitor 120 and a resistor 121.
Determines the oscillation frequency and outputs the oscillation control signal a. The oscillation circuit 11 is a well-known ceramic oscillation circuit. The oscillation frequency is determined by the ceramic oscillator 110, the oscillation control signal a controls ON / OFF of oscillation by the NAND gate 111, and the excitation signal b is output.
The magnetic field generation circuit 10 includes a current limiting resistor 100, a capacitor 101, and a coil 102.
1 and the coil 102 form a parallel resonance circuit, the resonance frequency of which is substantially adjusted to the frequency of the excitation signal b, and the coil 102 generates an alternating magnetic field having the frequency of the excitation signal b.

FIG. 3 shows a detailed configuration diagram of the magnetic field detection circuit 20 and the tablet control circuit 21 of the tablet body 2. In the figure, x1 to xm are sense lines laid along the X axis of the XY rectangular coordinate axes, y1 to yn are sense lines laid along the Y axis of the XY rectangular coordinate axes, and 200
Is an X-axis scanning circuit that sequentially selects the sense lines x1 to xm, and 201 is Y that sequentially selects the sense lines y1 to yn.
Axis scanning circuit, 202 amplification circuit, 203 detection circuit, 2
Reference numeral 04 is a smoothing circuit, 210 is a CPU circuit composed of a well-known microcomputer, which has a coordinate calculating means 22 and a state detecting means 23, and 211 is a CP when power is turned on.
A reset circuit for initializing the U circuit 210;
Is an interface circuit that outputs the data of the coordinate reading device generated by the CPU circuit 210 to an external device.

FIG. 4 is a waveform diagram for explaining the operation of this embodiment. FIG. 5 shows a state transition diagram for explaining the operation of this embodiment. The operation of this embodiment will be described below. The oscillation control circuit 12 of the coordinate indicator 1 is composed of a CR oscillation circuit and outputs an oscillation control signal a of 100 Hz. The oscillation circuit 11 is a ceramic oscillation circuit and is a NAND gate 111.
Causes the oscillation control signal a to remain at a high level, for example, 50
It oscillates at 0 kHz and outputs an excitation signal b. The magnetic field generation circuit 10 uses the excitation signal b to output the coils 102 to 10
An alternating magnetic field c of 500 kHz is generated intermittently at 0 Hz. Then, when the coordinate indicator 1 is positioned on the tablet body 2, a small induction signal is generated in the sense line near the coordinate indicator 1 by electromagnetic induction by the magnetic field c generated from the coordinate indicator 1. This induction signal is sent to the CPU circuit 21.
The scan signals (not shown) output from
The signal passes through the axis scanning circuit 200 or the Y-axis scanning circuit 201 and is input to the amplification circuit 202 as an induction signal e, and the waveform is shaped by the detection circuit 203 and the smoothing circuit 204 and input to the CPU circuit 210 as an analog signal f. And CP
Coordinate calculation means 22 and state detection means 23 executed by the program of the microcomputer of the U circuit 210
The coordinates of the coordinate indicator 1 are detected based on the sequentially input analog signals f.

The operations of the coordinate calculating means 22 and the state detecting means 23 will be described below with reference to FIG. For example,
When the coordinate indicator 1 is positioned at the intersection of the sense line x4 and the sense line y4 (portion P in FIG. 3), if the magnetic field of the coordinate indicator 1 is detected by the state detection means 23 described later, the coordinate calculation means 22 is used. Sense lines x2 to x6 and sense lines y2 to y6 from the CPU circuit 210
Scan signals are sequentially output at intervals of 250 [us] (this period is called a coordinate calculation mode).

X-axis scanning circuit 200 and Y-axis scanning circuit 2
01 sequentially scans the sense line based on this scanning signal, and the induction signal e is input from the smoothing circuit 204 to the CPU circuit 210 as an analog signal f. Coordinate calculation means 22
Is an analog signal f sequentially input to the CPU circuit 210.
Is detected and the maximum value of the induction signal of each axis sense line is detected (in this case, sense line x4 and sense line y
4) Further, the coordinates are calculated by comparing the magnitudes of the induction signals of the sense lines before and after that. The details of the coordinate calculation method are described in Japanese Patent Application Laid-Open No. 55-96411 filed by the present applicant, and will not be repeated here. The calculated coordinates are output to an external device via the interface circuit 212 as needed.

When the coordinate calculation mode is completed, the state detection mode is entered next (A in FIG. 5). In the state detection mode, the state detection means 23 detects the maximum value in the immediately previous coordinate calculation mode in the Y-axis sense line (in this case, the sense line y).
4), the scanning signals of the sense lines y2, y4, y6 are sequentially output from the CPU circuit 210 at intervals of 125 [us], and the sense lines y2, y4, y6 are output.
Scanning is repeatedly performed at a cycle of 375 [us].

During this time, when the generation of the magnetic field c from the coordinate indicator 1 is stopped, the guidance signal e is no longer guided, and when the generation of the magnetic field c from the coordinate indicator 1 is started again, the guidance signal e is guided. The detection means 23 uses the analog signal f
Can be detected to restart the excitation of the coordinate indicator 1. Then, the mode shifts to the coordinate calculation mode (B in FIG. 5), and this operation is repeated thereafter.

In the state detection mode, only one axis is scanned, and the scanning time per sense line is shortened. In the state detection mode, it is sufficient to detect only the presence or absence of the analog signal f, and the signal level is accurate. This is because it is not necessary to detect the re-excitation of the coordinate indicator 1 as soon as possible. Also, the sense line y
The reason why three lines are scanned every other line such as 2, y4 and y6 is to correspond to the movement of the coordinate indicator 1.

In the above, the repeated operation of the coordinate calculation mode and the state detection mode has been described for the sake of simplicity. For example, when the power of the coordinate reading apparatus is turned on, the operation is first performed before shifting to these operations. , Coordinate indicator 1
Must be detected on the sense line x4 and the sense line y4. The operation up to the transition to the repetitive operation will be described below. After the power is turned on, the reset signal from the reset circuit 211 is CP.
It is supplied to the U circuit 210, and the CPU circuit 210 is initialized and starts operating (C in FIG. 5). First, the X-axis scanning circuit 2
00 sequentially selects every other sense line x1 to xm by the scanning signal output from the CPU circuit 210, and when the sense line x4 or the sense lines before and after it is scanned, the analog signal f is detected, and the CPU circuit 210
Detects that the coordinate indicator 1 is located near the sense line x4.

Next, the Y-axis scanning circuit 201 sequentially selects every other sense lines y1 to yn, and similarly detects that the coordinate indicator 1 is located near the sense line y4. The operation of detecting the rough position of the coordinate indicator 1 on the tablet described above is called full-screen scanning. It should be noted that since the coordinate indicator 1 intermittently generates a magnetic field during one cycle of scanning of each axis, that is, scanning of the sense lines x1 to xm and the sense lines y1 to yn, the coordinate indicator 1 is scanned once. Must be completed within the excitation period (5 ms).

When the rough position of the coordinate indicator 1 is detected by scanning the entire surface, the above-mentioned state detection mode is entered (D in FIG. 5) and the coordinate calculation mode and the state detection mode are repeated (FIG. 5). A, B). Further, when the coordinate indicator 1 is separated from the tablet body 2 during this period, it is detected that the analog signal f has become equal to or less than a predetermined threshold value in the coordinate calculation mode, and the entire scan is performed (E in FIG. 5). ).

Next, the operation of detecting the state of the switch circuit in the coordinate indicator having the oscillation control circuit having the switch circuit will be described with reference to FIG. FIG. 6 is a circuit diagram showing an embodiment of the oscillation control circuit 12a having a switch circuit. The same symbols as those in FIG. 2 show the same components, and a switch circuit composed of a resistor 122 and a switch 123 is It is connected in parallel to the resistor 121. In the oscillation control circuit 12a of the present embodiment, the oscillation frequency of the CR oscillation circuit is changed by opening / closing the switch 123, and the oscillation control signal a
Change. 100 when switch 123 is open
When the switch 123 is closed, it oscillates at 125 Hz, and an alternating magnetic field of 500 kHz is 100 Hz.
It is generated from the coordinate indicator intermittently at Hz or 125 Hz. Therefore, on the tablet body side, the state detecting means 23 described in the above embodiment counts the period during which the generation of the magnetic field from the coordinate indicator is stopped, and the open / closed state of the switch 123 of the coordinate indicator is detected from this count value. can do.

Next, the operation of detecting the pressurization state of the pressure sensitive element in the coordinate indicator having the oscillation control circuit having the pressure sensitive element will be described with reference to FIG. FIG. 7 is a circuit diagram showing an embodiment of the oscillation control circuit 12b having a pressure-sensitive element. The same symbols as those in FIG. 2 indicate the same elements, and the pressure-sensitive resistance element 124 and the resistance 125 are the resistance 121. Are connected in parallel. In the oscillation control circuit 12b of this embodiment, the oscillation frequency of the CR oscillation circuit changes according to the pressurization state of the pressure-sensitive resistance element 124, and the oscillation control signal a changes. When the pressure-sensitive resistance element 124 is not pressurized, the frequency is 100 Hz. When the pressure-sensitive resistance element 124 is pressurized, its resistance value continuously decreases and at the same time, the frequency of the oscillation control signal a increases. The intermittent period of the alternating magnetic field generated from the coordinate indicator intermittently also changes continuously. Therefore, on the tablet body side, the state detecting means 23 described in the above embodiment counts the period during which the generation of the magnetic field from the coordinate indicator is stopped, and based on this count value, the pressure-sensitive resistance element 124 of the coordinate indicator is added. The pressure state can be detected. The resistor 125 determines the upper limit of the frequency of the oscillation control signal a, and secures the time for the coordinate calculation mode by the coordinate calculation means 22.

FIG. 8 is a circuit diagram showing another embodiment of the oscillation control circuit having a pressure sensitive element. The oscillation control circuit 12c is a well-known CR oscillation circuit that changes the duty of the oscillation control signal a by the diode 126 and the diode 127, and the resistor 121 is used during the high level period of the oscillation control signal a, that is, the oscillation period of the oscillation circuit 11. The low-level period of the oscillation control signal a, that is, the oscillation stop period of the oscillation circuit 11 is determined by the pressure-sensitive resistance element 124. The present embodiment has an advantage that the coordinate calculation mode time is secured because the oscillation period of the oscillation circuit 11 is fixed, and the oscillation stop period of the oscillation circuit 11 can be greatly changed by the pressure sensitive resistance element 124.

Although the embodiment of the oscillation control circuit having the pressure-sensitive element described above has been described by using the pressure-sensitive resistance element as the pressure-sensitive element, the value of the capacitor 120 is changed by using the pressure-sensitive capacitive element. Can also obtain the same effect. Further, although the oscillation control circuits of the embodiments are all configured by the CR oscillation circuit, for example, an inexpensive 4-bit one-chip microcomputer driven by a low voltage is used, and the switch circuit and the pressure-sensitive element are used as inputs to the 4-bit one-chip. It goes without saying that it is also possible to output the oscillation control signal by the program of the microcomputer.

Further, in the oscillation control circuit 12c shown in FIG. 8, even if the switch circuit composed of the resistor 122 and the switch 123 shown in FIG. It goes without saying that it can be detected, but at this time, if the switch 123 is a normally open type switch and the operator turns on the coordinate indicator to correspond to the operation of closing the switch 123, the normal coordinate reading device is in use. Is overwhelmingly longer for the operator to turn off the coordinate indicator than to turn it on,
When the coordinate indicator is switched on, the oscillation stop period is short, and when it is switched off, the oscillation stop period is long, so the actual excitation time of the coordinate indicator can be shortened, and the energy for driving the coordinate indicator can be reduced. It can be minimized and the battery life of the coordinate indicator can be extended. Furthermore, if the switch operation of the coordinate indicator is not performed continuously for a predetermined time, combining the functions such as stopping the power supply to the circuit inside the coordinate indicator will further extend the battery life. it can.

9 and 10 show another embodiment of the state detecting means. 9 is a magnetic field detecting circuit corresponding to another embodiment of the state detecting means, and FIG. 10 is a waveform diagram for explaining the operation of the other embodiment of the state detecting means. The magnetic field detection circuit 20a shown in FIG. 9 corresponds to the magnetic field detection circuit 20 of the embodiment shown in FIG.
The X-axis scanning circuit 20 is provided with an excitation detection-dedicated sense line z.
The part connected to 0 is different. In this way, the magnetic field detection circuit 2
By configuring 0a, the state detection means can detect the oscillation state of the coordinate indicator as shown in FIG. 10 if only the sense line z in the state detection mode is selected, and the oscillation stop period is detected. By doing so, the state of the switch circuit or the pressure-sensitive element of the coordinate indicator can be detected.

Further, instead of detecting the oscillation stop period in the state detecting means, the state of the switch circuit or the pressure-sensitive element of the coordinate indicator can be detected by detecting the oscillation period or the intermittent cycle. Further, in order to control the oscillation of the oscillation circuit by the oscillation control signal, the oscillation control signal may be used as the power supply of the oscillation circuit. The present invention intermittently generates a magnetic field from a coordinate indicator and detects the position and switch state of the coordinate indicator from an induction signal generated in a sense line. Can be variously modified, and also in the magnetic field detection circuit, various modifications such as the shape of the sense line and the number of turns can be considered. Further, in the tablet control circuit as well, it can be easily inferred that various modifications can be considered in the processing procedure of the coordinate calculating means and the state detecting means.

[0027]

As described above, according to the present invention, by providing an oscillation period and a stop period of oscillation of the oscillation circuit of the coordinate indicator and intermittently generating a magnetic field from the coordinate indicator,
Extend the battery life of the coordinate indicator equipped with a battery, further detect the magnetic field in the oscillation period of the oscillation of the oscillation circuit in the tablet body, obtain the coordinates, and without changing or modulating the frequency from the coordinate indicator, The states of the switch circuit and the like of the coordinate indicator can be transmitted simply by turning on / off the oscillation. Therefore, unlike the conventional case, a frequency discriminating circuit and a demodulating circuit are not required, and the coordinate reading device can be configured with a very simple circuit, and an inexpensive coordinate reading device can be provided.

Further, even in a coordinate reading apparatus in which the coordinate indicator is not equipped with a battery and the tablet body and the coordinate indicator are connected by a cable, the cable between the coordinate indicator and the tablet body is only required to supply power. Minimum 2
Since it is composed of a book and the cable can be made thin,
As a coordinate indicator with a cable, a coordinate reading device with excellent operability can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a coordinate reading device according to the present invention.

FIG. 2 is a detailed circuit diagram of a coordinate indicator according to the present invention.

FIG. 3 is a detailed configuration diagram of a magnetic field detection circuit and a tablet control circuit of the tablet body.

FIG. 4 is a waveform diagram illustrating the operation of the embodiment of the present invention.

FIG. 5 is a state transition diagram illustrating the operation of the exemplary embodiment of the present invention.

FIG. 6 is a circuit diagram showing an embodiment of an oscillation control circuit having a switch circuit according to the present invention.

FIG. 7 is a circuit diagram showing an embodiment of an oscillation control circuit having a pressure sensitive element according to the present invention.

FIG. 8 is a circuit diagram showing another embodiment of an oscillation control circuit having a pressure sensitive element according to the present invention.

FIG. 9 is a magnetic field detection circuit corresponding to another embodiment of the state detection means in the present invention.

FIG. 10 is a waveform diagram for explaining the operation of another embodiment of the state detecting means in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coordinate indicator 2 Tablet body 10 Magnetic field generation circuit 11 Oscillation circuit 12 Oscillation control circuit 20 Magnetic field detection circuit 21 Tablet control circuit 22 Coordinate calculation means 23 State detection means 200 X-axis scanning circuit 201 Y-axis scanning circuit 202 Amplification circuit 203 Detection circuit 204 smoothing circuit 210 CPU circuit 211 reset circuit 212 interface circuit

Claims (3)

[Claims] 1. A coordinate reading device comprising a coordinate indicator for generating a magnetic field and a tablet body for detecting a magnetic field generated by the coordinate indicator to detect a pointed position of the coordinate indicator. The tablet body includes an oscillation circuit, an oscillation control circuit that controls an oscillation period and a stop period of oscillation of the oscillation circuit, and a magnetic field generation circuit that generates a magnetic field by an excitation signal output from the oscillation circuit. Is a magnetic field detection circuit that detects a magnetic field generated from the coordinate indicator, a coordinate calculation unit that calculates coordinates from the magnetic field detected by the magnetic field detection circuit, and a state that detects the oscillation state of the oscillation circuit of the coordinate indicator. A coordinate reading device comprising a tablet control circuit having a detection means. 2. The oscillation control circuit has a switch circuit, the oscillation period and the suspension period of the oscillation of the oscillation circuit are controlled by the state of the switch circuit, and the state detection means detects the oscillation state of the oscillation circuit. The state of the switch circuit is detected by performing the operation.
The coordinate reading device described. 3. The oscillation control circuit has a pressure sensitive element, and continuously controls an oscillation period and a stop period of oscillation of the oscillation circuit according to a pressurizing state of the pressure sensitive element, and the state detecting means is configured to 2. The coordinate reading device according to claim 1, wherein the pressing state of the pressure sensitive element is detected by detecting the oscillation state of the oscillation circuit.