JPH0744305A - Coordinate input device - Google Patents

Abstract

PURPOSE:To provide a thin coordinate input device and also to improve the operability of the input device by using the upper electrode of a liquid crystal plate and the lower electrode of a tablet as an input terminal equipment respectively. CONSTITUTION:Electrode wires 22 are set under Electrode wires 23 with prescribed spaces and in two directions (X-axis and Y-axis directions) which are orthogonal to each other on a coordinate axis. These wires 22 and 23 are also used as the electrode wires of a crystal plate. The electrode wire selecting circuits 24 and 25 of X-axis and Y-axis directions respectively apply in sequence the AC signals to the wires 22 and 23 based on the address signals AD1 and AD2 supplied from a control circuit 26. The circuit 26 specifies a coordinate position of a single side (Y-axis direction) and then applies the signal AD2 to the selecting circuit 25. At the same time, the circuit 26 applies simultaneously the AC signals to plural prescribed lower electrode wires. Therefore the detection signals are increased for the lower electrode wires and the coordinates can be easily calculated.

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 for figures, characters and the like. More specifically, by using the upper and lower electrode lines of a liquid crystal display plate also as tablet electrodes,
The present invention relates to a coordinate input device that reduces the thickness of the device and further reduces the parallax between the input position and the display position.

[0002]

2. Description of the Related Art FIG. 7 is a vertical sectional view of a conventional coordinate input device integrated with a liquid crystal. Tablet 5 on the LCD panel 60
0 is provided, and the AC signal applied to the electrode line of the tablet 60 is input to the input wire of the tablet 60 by capacitive coupling with a coordinate pointing device (input pen) that comes into contact with a desired position of the tablet 60 to input coordinates. The position coordinate is detected by the signal generated in the detection electrode. The liquid crystal display board 60
Is a transparent electrode (ITO film) 6 on the upper side of the transparent glass substrate 62.
3 is formed, and the transparent electrode 6 is formed on the lower side of the transparent glass substrate 66.
5 is formed, the liquid crystal layer 64 is enclosed between the transparent glass substrates 62 and 66, and the polarizing plates 67 and 61 are respectively attached to the upper and lower sides. Further, the tablet 50 has a plurality of transparent electrodes 52 formed on a transparent glass substrate 51, a transparent electrode 54 is formed below the transparent glass substrate 55 so as to be orthogonal to the transparent electrodes 51, and a transparent dielectric layer 53. The transparent substrates 51 and 55 are bonded to each other with the film sandwiched therebetween.

[0003]

In the above-mentioned conventional coordinate input device, the thickness of the input device is the sum of the thicknesses of the liquid crystal plate 60 and the tablet 50, so that the thickness becomes thick and it is difficult to make the device thin. And a transparent electrode 52 for coordinate detection,
Since the distance between 54 and the transparent electrodes 63 and 65 for display is large, there is a problem that parallax occurs between the position where the tablet 50 is pointed by the input pen and the position where the tablet 50 is displayed. In addition, the transparent electrodes 52 and 54 for tablets are replaced with the transparent electrodes 63 and 6 for display.
Although it is possible to use the same method as that of 5, the display liquid crystal electrode 6
Since the gap between the electrodes of No. 5 is narrow, it becomes a kind of shield layer and the signal from the transparent electrode 63 becomes small, so that there is a problem that coordinates cannot be detected.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional inconveniences, and a predetermined electrode is formed on an electrode of a dot matrix liquid crystal display panel having a plurality of electrodes arranged in the coordinate axis direction corresponding to the dot pitch. A driving unit for applying an AC signal, an input pen for capacitively coupling the AC signals applied to the respective electrodes to perform signal detection, and an arithmetic unit for calculating position coordinates from the signal detected by the input pen. In the coordinate input device, the AC signal is sequentially applied to the upper electrode line in the X-axis or Y-axis direction of the liquid crystal display panel, and a plurality of X-axis or lower electrode in the Y-axis direction orthogonal to the upper electrode is applied. The AC signal is simultaneously applied to the electrodes (electrode line group) of the book, and the AC signal is sequentially applied to each electrode line group, and the input pen is contacted. Choose a large electrode The coordinate position is set as the standard position, and the lower side proposes a coordinate input device characterized in that the coordinate position is calculated from the potential gradient generated according to the distances from the AC application points of the plurality of electrodes near the contact position of the input pen. It is a thing.

[0005]

In the coordinate input device of the present invention, the display electrode line of the liquid crystal display panel is also used as a tablet for coordinate input. An AC signal is sequentially applied to the orthogonal upper electrode lines and the lower electrode lines are applied. By applying an AC signal to a plurality of electrodes at the same time, the detection signal of the lower electrode wire becomes large, and the calculation of coordinates becomes easy.

[0006]

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a vertical cross-sectional view of a liquid crystal integrated type input device of the present invention, in which an upper transparent electrode 3 is formed below a transparent glass substrate 2 and a lower transparent electrode 5 is formed above a transparent glass substrate 4. , The liquid crystal layer 6 is enclosed between the transparent glass substrates 2 and 4, and the polarizing plates 7 and 8 are respectively provided on the transparent glass substrates 2 and 4.
It is attached to the outside of the top and bottom.

FIG. 2 is an electrical block diagram. Reference numeral 21 is a tablet, and the electrode wires 22 are arranged below the electrode wires 23 at predetermined intervals in two directions (X-axis direction and Y-axis direction) orthogonal to each other on the coordinate axes. The electrode lines 22 and 23 are also used as the electrode lines of the liquid crystal plate.
Reference numerals 24 and 25 are electrode line selection circuits in the X and Y axis directions, respectively, and the electrode line selection circuits 24 and 25 serve both for liquid crystal display and for tablets. The X and Y axis direction electrode selection circuits 24 and 25 sequentially apply AC signals to the electrode lines 22 and 23 according to the address signals AD1 and AD2 supplied from the control circuit 26.

Reference numeral 27 is an input pen which is a coordinate pointing device, and reference numeral 28 is arranged at the tip of the input pen 27 and is held slidably by bringing the input pen 27 into contact with the surface of the tablet 21. It is a detection electrode. Reference code 2
A switch 9 opens and closes according to the contact sliding of the detection electrode 28 on the tablet 21. Reference numeral 30 is a signal processing unit, which includes an amplifier 31, a bandpass filter-32, a detection circuit 33, and an analog-digital converter 34 that amplifies a signal electrostatically coupled to the electrode wires 22 and 23 generated in the detection electrode 28. It is configured. The output of the signal processing unit 30 is connected to the arithmetic circuit 35 in the CPU 36.

Now, the actual operation will be described. The upper electrode wire 22 in which the input pen 27 is arranged on the tablet 21
When the input is made by abutting the vicinity of, the control circuit 26 applies the address signal AD1 to the electrode selection circuit 24, as shown in FIG.
As described above, the AC signal is sequentially applied to the predetermined upper electrode lines of Yp1 to Ypn, and at the same time, the timing pulse TP is supplied to the analog-digital converter 34, and the generation signal of the detection electrode 28 is converted into a signal via the signal processing unit 30. Check for the presence.
If there is an input signal from the signal processing unit 30, the address and signal value of the maximum converted digital value of the electrode line are stored in the memory. This maximum level input signal is
The AC of the upper electrode closest to the contact portion of the input pen 27
This is due to the signal and becomes the upper coordinate position signal.

Next, after the coordinate position on one side (Y-axis direction) is specified, the control circuit 26 applies the address signal AD2 to the electrode selection circuit 25 and, as shown in FIG. 5, predetermined lower electrodes Xp1 to Xpn. An AC signal is simultaneously applied to a plurality of lines (a group of electrode lines), and at the same time, a timing pulse TP is supplied to the analog-digital converter 34, so that the occurrence signal of the detection electrode 28 is detected by the signal processing unit 30. Check. Here, when there is an input signal from the signal processing unit 30, the converted digital value corresponds to the distance between the electrode line group and the detection electrode.

Here, the method of specifying the lower coordinates will be described again with reference to FIG. Xp1 to Xp2 and Xp3 to X of the lower electrode wires arranged in the X axis direction as shown in FIG.
When AC signals are sequentially applied to p4, Xp5 to Xp6 from the electrode selection circuit at the same time, the electrostatic capacitances between the electrode lines and the detection electrodes are C1 + C2, C3 + C4, and C5 + C, respectively.
The value becomes 6, which is inversely proportional to the distance between the detection electrode and the electrode wire and directly proportional to the detection signal. Therefore, rather than applying an AC signal to each electrode line, the signal detected by applying an AC signal to a plurality of electrode lines at the same time becomes larger and a reliable position coordinate can be detected.

In the state of FIG. 3, the detection electrode of the input pen is
Electrode wire groups Xp1 to Xp2, Xp3 to Xp4, Xp5 to X
A signal is generated by capacitive coupling from p6. Electrode wire group Xp
1 to Xp2, Xp3 to Xp4, and Xp5 to Xp6, the distance from the center of each is L, and the electrode line groups Xp1 to Xp
2, the detection signals from Xp3 to Xp4 and Xp5 to Xp6 are the electrode line group Xp closest to the detection electrode of the contacted input pen.
Seen from 3 to Xp4, L1 / L2 = ((L / 2) -Lp)
/ (L / 2) is established. Therefore, Lp is the electrode wire group Xp1
It can be obtained by calculating the detection signals V1, V2, V3 from Xp2, Xp3 to Xp4, Xp5 to Xp6.

FIG. 6 is an electrical block diagram of the second embodiment. Reference numeral 71 is a tablet, and electrode lines 72 and 73 are arranged at predetermined intervals in two orthogonal directions (X-axis direction and Y-axis direction), and the electrode line 73 is arranged on the lower side. . The electrode lines 72 and 73 are also used as the electrode lines of the liquid crystal plate. Reference numerals 74 and 75 are electrode line selection circuits in the X and Y axis directions, respectively, and the electrode line selection circuits 74 and 75 serve both for liquid crystal display and for tablets. The X and Y axis direction electrode selection circuits 74 and 75 are the CPU 86.
Address signal AD1 supplied from the control circuit 76 in the
2, an AC signal is sequentially applied to the electrode lines 72 and 73.

Reference numeral 77 is an input pen which is a coordinate pointing device, and reference numeral 78 is arranged at the tip of the input pen 77 and slidably held by contacting the surface of the tablet 71 of the input pen 77. It is a detection electrode. Reference number 7
A switch 9 opens and closes in accordance with the sliding of the detection electrode 78. Reference numeral 80 is a signal processing unit, which is the detection electrode 78.
And an amplifier 81 for amplifying a signal capacitively coupled to the electrode lines 72 and 73 generated in the above, a bandpass filter-82, a detection signal switching circuit 83, a signal peak timing detection circuit 87, and an analog-digital converter 74. ing. The output of the signal processing unit 80 is connected to the arithmetic circuit 85 in the CPU 86.

When the input pen 77 comes in contact with the vicinity of the upper electrode line 73 arranged on the tablet 71 to perform input, the control circuit 76 causes the electrode selection circuit 74 to send the address signal A
D1 is applied, AC signals are sequentially applied to predetermined upper electrode lines Y0 to Yn as shown in FIG. 4, and at the same time, a switching signal CH is supplied to the detection signal switching circuit 83 to detect the occurrence signal of the detection electrode 78 as a signal peak timing. The timing of the maximum value of the signal is confirmed via the circuit 87. Here, if there is an input signal from the signal processing unit 80, the address of the maximum electrode line is stored in the memory. The address of the electrode line at the maximum level is based on the AC signal of the upper electrode closest to the contact portion of the input pen 77, and becomes the upper coordinate position signal.

Next, after the coordinate position on one side (Y-axis direction) is specified, the control circuit 76 applies the address signal AD2 to the electrode selection circuit 75, and predetermined lower electrodes Xp1 to Xpn as shown in FIG. AC signals are simultaneously applied to a plurality of lines (a group of electrode lines), and at the same time, a switching signal CH is supplied to the detection signal switching circuit 83 and a timing pulse TP is supplied to the analog-digital converter 84, and a signal generated by the detection electrode 78 is processed. The presence or absence of a signal is confirmed via the unit 80. Here, when there is an input signal from the signal processing unit 80, the converted digital value corresponds to the distance between the electrode line group and the detection electrode.

[0017]

Since the present invention has the above-described structure, the upper electrode of the liquid crystal plate and the lower electrode of the tablet are also used as an input terminal device of a figure, character, etc. integrated with the display device. As a result, a thin coordinate input device is realized, and operability is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of the present embodiment.

FIG. 2 is an electrical block configuration diagram.

FIG. 3 is an explanatory diagram of electrostatic coupling between an electrode wire and an input pen.

FIG. 4 is a state diagram of applied signals to the upper electrode.

FIG. 5 is a block diagram of applied signals to the lower electrode.

FIG. 6 is an electrical block configuration diagram of another embodiment.

FIG. 7 is a conventional vertical sectional view.

[Explanation of symbols]

 1 Liquid Crystal Plate 2 Glass Substrate 3 Electrode Line 4 Glass Substrate 5 Electrode Line 6 Liquid Crystal Layer 7 Polarizing Plate 8 Polarizing Plate 10 Glass Substrate 21 Tablet 22 Electrode Line 23 Electrode Line 24 Electrode Line Selection Circuit 25 Electrode Line Selection Circuit 26 Control Circuit 27 Input Pen 28 Detection electrode 29 Switch 30 Signal processing unit 31 Amplifier 32 Band pass filter-33 Detection circuit signal 34 Analog-digital converter 35 Arithmetic circuit 36 CPU 71 Tablet 72 Electrode line 73 Electrode line 74 Electrode line selection circuit 75 Electrode line selection circuit 76 Control Circuit 77 Input Pen 78 Detection Electrode 79 Switch 80 Signal Processor 81 Amplifier 82 Bandpass Filter 83 Detection Signal Switching Circuit 84 Analog-Digital Converter 85 Arithmetic Circuit 86 CPU 87 Detection Circuit Peak Timing Detection Circuit Path

Claims (1)

[Claims] 1. A driving unit for applying a predetermined AC signal to the electrodes of a dot matrix liquid crystal display panel, which has a plurality of electrodes arranged in the coordinate axis direction corresponding to the dot pitch of the liquid crystal, and a driving unit applied to each of the electrodes. In the coordinate input device including an input pen for capacitively coupling with the AC signal and performing signal detection, and a calculation unit for calculating position coordinates from the signal detected by the input pen, X or Y of the liquid crystal display panel is used. An AC signal is sequentially applied to the upper electrode line in the axial direction, and the AC signal is simultaneously applied to a plurality of electrodes on the lower side in the X or Y axis orthogonal to the upper electrode, and the electrode line group The AC signal is sequentially applied to each of them, the coordinate pointing device is contacted, and the electrode having the largest detection signal on the upper side of the obtained detection signals is selected as the coordinate position. The lower side is the contact position of the input pen. AC application of multiple electrodes in the vicinity A coordinate input device characterized by calculating a coordinate position from a potential gradient generated according to a distance from a point.