JPH0447320A - Wireless coordinate reading device to detect height information - Google Patents

Abstract

PURPOSE:To precisely obtain height information by constituting a coordinate indicator so that it resonates with an exciting signal by providing a metallic plate under a sense line board on which plural exciting line groups and plural sense line groups are over-lapped and arranged. CONSTITUTION:In a process to give an AC signal sequentially to the exciting line group 2 and simultaneously select the sense line group 3, if the coordinate indicator 10 is placed in the vicinity of a selected exciting line and a selected sense line, an induced signal is generated in the sense line. On the other hand, the inductance of a built-in coil 11 in the coordinate indicator 10 is changed according to distance between the coil 11 and the metallic plate arranged under the sense line board 1. The change of this inductance changes the resonance frequency of a resonance circuit which the coil 11 constitutes, and changes the phase of the induced signal. A phase detection circuit 8 detects the phase of the induced signal induced in the sense line, and makes it a phase signal, and a control circuit 9 inputs this phase signal, and converts it into the height information. Thus, the height information can be highly precisely detected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a coordinate reading device that inputs coordinates to an external device such as a computer, and in particular, the present invention relates to a coordinate reading device that inputs coordinates to an external device such as a computer. This relates to a wireless coordinate reading device that does not require

[Summary of the Invention] The present invention sequentially applies an AC signal to a plurality of excitation lines laid on a sense line board, and at the same time sequentially selects a sense line, and a coordinate indicator having a resonant circuit including a coil and a capacitor is installed on the sense line board. When the coordinate indicator is placed in a wireless coordinate reading device that obtains coordinate values from the induced signal induced in the sense line by electromagnetic coupling between the excitation line, coil, and sense line, the height information of the position where the coordinate indicator is placed. The purpose of the present invention is to realize a coordinate reading device that can also detect.

To this end, in the present invention, a metal plate is provided below the sense line plate, and a phase detection circuit that detects the phase of the induced signal induced into the sense line and a control circuit that converts the detected phase signal into height information are provided. A coordinate reading device was constructed.

As the coil built into the coordinate indicator moves away from the metal plate placed on the sense line plate, the inductance of the coil changes and the phase of the induced signal changes.Using this, the phase signal is detected and the height is determined. We are trying to convert it into information.

[Prior Art] As a technique for obtaining height information in a coordinate reading device, a technique that utilizes the amplitude of a guidance signal is known. FIG. 8 is an explanatory diagram thereof.

The excitation line 102 and the sense line 103 are arranged orthogonally to form the sense line plate 101, and the excitation line 102
An alternating current signal is applied to the sense line 103, and the induced signal induced on the sense line 103 is observed. The coordinate indicator 104 is a coil 105
It has a built-in resonant circuit using a capacitor.

When the coordinate indicator 104 is placed on the sense line plate 101 as shown in the figure, the sense line
A guidance signal is generated on 3. If the coordinate indicator 104 is directly above the sense line plate 101, the amplitude of the guidance signal will be large, and if it is away from the sense line plate 101, the amplitude will be small (
If you amplify and detect the induced signal and measure the amplitude,
This allows the height information of the coordinate indicator to be obtained.

[Problems to be Solved by the Invention] The above explanation describes the principle, and in reality, a plurality of excitation lines 102 and sense lines 103 are provided to form the sense line plate 101, and the coordinate indicator 104 is connected to the sense line. The board 101 is placed at any position on the plane. It is not placed at a fixed point as shown in FIG.

For this reason, in the technology that uses the amplitude of the guidance signal as height information, the position on the plane where the coordinate indicator is placed is difficult to determine. There was a problem in that the amplitude also changed due to the change in height, making it impossible to detect height information with high accuracy.

For example, the coordinate indicator 104
As the sense line 103 moves, the amplitude of the induced signal becomes maximum at the center of the sense line 103 and decreases as it moves toward the periphery, as shown in FIG.

The present invention has been made to solve the above-mentioned problems in the conventional technology. The main purpose is a wireless coordinate reading device that does not require a signal line connection between the coordinate reading device and the coordinate indicator, and can also detect height information of the position where the coordinate indicator is placed. The purpose is to realize a wireless coordinate reading device, and a more specific objective is to realize a wireless coordinate reading device that can detect height information with high accuracy without being affected by position.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, a plurality of excitation line groups and a plurality of sense line groups are arranged in an overlapping manner! The coordinate indicator is placed on the sense line board and has a resonant circuit made up of a coil and a capacitor. In a wireless coordinate reading device that obtains the coordinate values of the position where the coordinate indicator is placed from the guidance signal guided to the sense line, a metal plate placed on the sense line plate, an AC signal given to the excitation line group, and a sense Input the guidance signal guided to the line,
A phase detection circuit that detects the phase of the guidance signal and outputs it as a phase signal and controls each part of the coordinate reading device, inputs the phase signal, and detects the position where the coordinate indicator is placed on the sense line board. A coordinate reading device was constructed by providing a control device for converting to height information.

[Function] In the coordinate reading device configured as described above, in the process of sequentially applying an AC signal to the excitation line group and selecting the sense line group at the same time, a coordinate indicator is placed near the selected excitation line and sense line. is placed, an induced signal is generated on the sense line.

On the other hand, the inductance of the coil built into the coordinate indicator changes depending on the distance between the coil and the metal plate placed on the sense line plate. This change in inductance causes a change in the resonant frequency of the resonant circuit constituted by the coil, and causes a change in the phase of the induction signal.

The phase detection circuit detects the phase of the induced signal induced into the sense line and uses it as a phase signal, and the control circuit inputs this phase signal and converts it into height information.

[Embodiment] (Configuration of coordinate reading device according to first embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

First, the configuration will be explained. FIGS. 1, 2, and 3 show configuration diagrams of a coordinate reading device according to the present invention.

In FIG. 1, 1 is a sense line plate on which an excitation line group 2 and a sense line group 3 are laid. The excitation line group 2 and the sense line group 3 form a folded loop and are arranged at regular intervals. In the first embodiment, the excitation line group 2 and the sense line group 3 are arranged orthogonally.

Although not shown in FIG. 1, as shown in the cross-sectional view of the sense line plate in FIG. 2, a metal plate 13 is placed below the sense line plate 1 with a spacer 14 in between.

4 is an excitation scanning circuit to which each excitation line of the excitation line group 2 is connected. The excitation scanning circuit 4 is composed of a plurality of electronic switching elements such as analog switches, and is adapted to apply an excitation signal ds supplied from an excitation circuit 6, which will be described later, to one selected excitation line.

5 is a sense scanning circuit to which each sense line of the sense line group 3 is connected. Like the excitation scanning circuit 4, it is composed of electronic switching elements, and one of the sense lines is selected and connected to an amplification detection circuit 7 and a phase detection circuit 8, which will be described later.

6 is an excitation circuit. An excitation clock dc is inputted from the control circuit 9 described in 11i, which is waveform-shaped and amplified to be output as an excitation signal ds.

Reference numeral 7 denotes an amplification/detection circuit that amplifies and detects the induced signal i3 induced into the sense line group 3 and outputs an amplitude signal as of the induced signal. This circuit is used to calculate coordinate values.

8 is a phase detection circuit that detects the phase signal ps of the induction signal is. A detailed configuration diagram is shown in FIG.

81 is an amplifier circuit, and 82 is a comparator. The induction signal js is inputted to the amplifier circuit 81 from the sense scanning circuit 5 . The output of the comparator 82 is the exclusive OR circuit 83
connected to one input of the

The excitation clock dc is input to the other input of the exclusive OR circuit 83, and the output is connected to an integrating circuit 84 composed of a resistor and a capacitor. In this circuit, the excitation clock dc is used as a reference phase signal, and the phase of the induction signal is is detected as a voltage signal charged in the integrating circuit 84.

The configuration of the phase detection circuit 8 shown in this embodiment is a circuit that detects the phase difference of the induction signal is with respect to the excitation clock dc, and cannot detect a lead or a lag.However, as a design matter, phase detection is required. It is also conceivable that the induced signal advances compared to the reference signal and exhibits delayed behavior due to the way the reference signal is taken, the phase inversion caused by the circuit, the delay, etc.

In such a case, a circuit for detecting phase lead/lag may be provided, and this circuit can be easily realized.

The configuration of the phase detection circuit is not essential to the present invention, and the circuit is not limited to this circuit as long as it detects the phase difference between two signals.

Let's return to Figure 1 and continue the explanation. The control circuit 9 controls each part, inputs and calculates each signal, and obtains coordinate values and height information. The excitation scanning circuit 4 has a drive address dad for instructing the excitation line to be selected.
rs is given to the sense scanning circuit 5, and a sense address 5adrs indicating the sense line to be selected is given to the sense scanning circuit 5. Further, an amplitude signal as is inputted to calculate coordinate values, and a phase signal ps is inputted to calculate height information. This control circuit 9 is realized by a microprocessor, and each calculation process is performed by a program.

The coordinate indicator 10 is constituted by a resonant circuit including a coil 11 and a capacitor 12. The resonant frequency of this resonant circuit is set around the frequency of the excitation clock dc, but does not necessarily have to match.

(About the scanning and coordinate calculation operations of the coordinate reading device) Next, the operations will be described. First, the operation of selecting the excitation line group 2 and the sense line group 3 and the coordinate calculation operation will be explained.

The control circuit 9 outputs a drive address dadrs to select one of the excitation lines. As a result, the excitation diagram Ia
The output of 6 is connected to the selected excitation line, which generates an alternating magnetic field. While selecting one excitation line, the control circuit 9 outputs the sense address 5adrs to sequentially select the sense line group 3,! ! The selected sense line is connected to the amplification detection circuit 7 and the phase detection circuit 8. The control circuit 9 repeats this operation, which is called "scanning".

If the coordinate indicator 10 is not on the sense line plate 1, no signal will be induced to the selected excitation line because the excitation line group 2 and the sense line group 3 are perpendicular to each other. When the indicator 10 is placed on the sense line plate l, a guidance signal is is induced to each sense line of the sense line group 3 in accordance with the positional relationship between the sense line plate l and the coordinate indicator 10. This is due to the effect of tm coupling between the excitation line, coil 11, and sense line.

FIG. 4 shows the guidance signal is as a scanning timing diagram. Taking FIG. 1 as an example, the excitation line group 2 is scanned from the top to the bottom of the figure, and the sense line group 3 is scanned from the left to the right of the figure. The position p of the coil 11 is located in the area where the excitation line d2 and the sense line s2 intersect.

Now, when the excitation line dO and the sense line sO are selected, that is, when the area where they intersect is far away from the position p of the coil 11, the induction signal is
is not observed.As the region where the excitation line and the sense line intersect approaches the position p of the coil, the induced signal i$ becomes larger, and becomes maximum when the excitation line d2 and the sense line s2 are selected. The guidance signal is has a distribution as shown in the timing diagram of FIG.

The induced signal is is converted into an amplitude signal as by the amplification/detection circuit 7.
, and its magnitude is read by the control circuit 9. Since the method of calculating coordinates is not the gist of the present invention, the details will be omitted, but 1. The control circuit 9 receives signals 1spXisxlSisxh, 1sy as shown in the timing diagram of FIG.
The coordinate values of the position where the coordinate indicator 10 is placed are calculated from the amplitude signal of ls 1syh.

(About the operation of calculating height information) Next, the operation of calculating height information will be explained.

In the zero-line coordinate reading device, which is known to change the inductance when metal approaches the coil, a metal plate 13 is placed below the sense line plate 1. Therefore, when the coordinate indicator 10 moves up and down on the sense line plate 1, the inductance of the coil 11 changes. The gist of the present invention is to capture this change in inductance and convert it into height information.

The control circuit 9 scans the sense line plate 1 as described above, during which the induced signal is is input to the phase detection circuit 8 and converted into a phase signal ps.

In FIG. 9, which explains the operation of the phase detection circuit 8 using the timing diagram of FIG. 5, dC is an excitation clock, ds is an excitation signal, and is is an induction signal.

When the coordinate indicator 10 is placed directly above the sense line plate 1, that is, at a height O, the guiding signal is is guided with a constant phase difference with respect to the excitation signal ds.

The process by which the guidance signal is is processed will be explained. First, the guided signal is is amplified by the amplifier circuit 81 in the phase detection circuit 8, and further converted into a square wave by the comparator 82, resulting in a shaped guided signal wave ip. The induced signal shaped wave ip and the excitation clock dc are phase-detected by an exclusive OR circuit 83 to become a detected signal pp. Furthermore, the detection signal pp is converted into a DC signal by an integrating circuit 84 and a phase signal p3
It becomes.

The inductance of the coil decreases as it approaches the metal plate. Therefore, conversely, as the coordinate indicator 10 moves away from the sense line plate 1, the inductance of the coil 11 increases, and as a result, the resonant frequency of the resonant circuit decreases. This effect has an influence in the direction of delaying the phase of the induction signal is. In FIG. 5, the guiding signal js
h is the result when the coordinate indicator 10 is separated from the sense line board 1, and shows that it lags behind the guidance signal is when the coordinate indicator IO was placed directly above the sense line board 1. There is. This signal is similarly converted into a phase signal psh by the phase detection circuit 8.As is clear from the operation of the 0 circuit, the magnitude of the phase signal psh is larger than the phase signal ps, and it can be seen that a change in phase can be detected.

The control circuit 9 converts the phase signal pS into an A/
D-transform it, take in its size, and then convert the signal i used to calculate the coordinates as shown in Figure 4.
The phase signal ps when sp occurs is employed as phase information for calculating height information.

The timing at which the phase signal ps is adopted is the above signal isp.
It is not limited to the case where the induced signal occurs, but phase detection is possible as long as the induced signal is generated, so sampling at a specific timing is sufficient. However, considering the S/N, the isp It is preferable to detect the phase of .

When the tendency of the phase signal ps with respect to height is illustrated, the curve is not a straight line as shown in FIG. 1, and the phase signal ps does not become height information as it is. By inputting ps, this is converted into height information.

Although the details are omitted, it is easy to memorize the trend of height and phase shown in Fig. 6 in the form of a conversion table, input the phase signal ps, and draw the conversion table to find the height. be able to.

(Configuration of coordinate reading device according to second embodiment) The gist of the present invention is that the inductance of the coil changes depending on the distance from the metal plate placed under the sense line plate, and this changes between the excitation line, the coil, and the sense line 3. The height information is obtained by detecting changes in the phase of the induced signal caused by electromagnetic coupling between the two. Therefore, the arrangement of the excitation line and the sense line is not limited to the first embodiment. .

FIG. 7 is a block diagram of the second embodiment. As shown in FIG. 0, in this embodiment, the excitation line group 22 is not perpendicular to the sense line group 3 but is arranged in the same direction. Furthermore, the two overlap in part. The other configurations are similar to the first embodiment.

With the sense line plate 21 configured in this way, the excitation circuit 4
Select one excitation line and give an excitation signal by
When one sense line that overlaps this excitation line is selected at the same time, an induced signal is generated in this sense line due to electromagnetic coupling with the excitation line.

The difference from the first embodiment is that a guidance signal is generated even if the coordinate indicator 10 is not on the sense line plate 21. However, when the coordinate indicator 10 is placed on the sense line plate 21, the coupling becomes stronger and a larger induced signal is generated. Therefore, coordinate values can be determined by observing the amplitude of the guidance signal, and a phase signal for calculating height information can also be detected.

Since the induced signal is the sum of the signal coupled through the coil and the signal coupled directly to the excitation line, the phase signal is the first
When compared with the example shown in FIG. However, while the phase of the signal directly coupled to the excitation line group is constant, the phase of the signal coupled via the coil remains constant due to the distance from the metal plate placed below the sense line plate. Therefore, height information can be calculated from the phase signal in the same way as in the first implementation θ.

[Effects of the Invention] As explained above, in the present invention, a metal plate is provided under a sense line plate in which a plurality of excitation line groups and a plurality of sense line groups are arranged in an overlapping manner, and a coordinate finger device is connected to an excitation signal. Since it is configured to resonate, the height of the position where the pedestal indicator is placed is determined from the phase of the induced signal due to electromagnetic coupling between the excitation line, the coordinate indicator, and the sense line σ. Therefore, since the amplitude information of the induced signal is not used,
We were able to implement a wireless coordinate reading device that can accurately obtain height information without being affected by position.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a first embodiment of a wireless coordinate reading device according to the present invention, Fig. 2 is a cross-sectional view of a sense line plate, Fig. 3 is a block diagram of a phase detection circuit, and Fig. 4 is a block diagram of a guided signal. Generation timing diagram, Figure 5 is a timing diagram of phase detection operation,
Fig. 6 is a graph showing the change in phase signal with respect to height, Fig. 7 is a configuration diagram of the second embodiment, Fig. 8 is an explanatory diagram of the conventional height detection technology, and Fig. 9 is the amplitude of the induced signal. It is a distribution map of 1...Sense line plate 2...Excitation line group 3...Sense line group 4...Excitation scanning circuit 5...Sense scanning circuit 6... - Excitation circuit 7... Amplification detection circuit 8... Phase detection circuit 9... Control circuit 10... Coordinate indicator 11... Coil 12...・More than capacitor

Claims (1)

[Scope of Claims] a. A sense line plate in which a plurality of excitation line groups and a plurality of sense line groups are arranged one on top of the other; b. A coordinate indicator placed on the sense line plate and having a resonant circuit including a coil and a capacitor. and sequentially applying an alternating current signal to the excitation line group and sequentially selecting the sense line group,
A wireless coordinate reading device that obtains coordinate values of a position where the coordinate indicator is placed from a guidance signal guided to the sense line, c. a metal plate disposed under the sense line plate; d. the excitation line group. a phase detection circuit that inputs the alternating current signal given to the sense line and the guided signal guided to the sense line, detects the phase of the guided signal, and outputs it as a phase signal; e. Controls each part of the coordinate reading device; Detecting height information, further comprising a control device that inputs the phase signal and converts the phase signal into height information of a position where the coordinate indicator is placed on the sense line plate. wireless coordinate reading device.