JPH02144716A - Electrostatic coupling system transparent coordinate input device - Google Patents

Abstract

PURPOSE:To decrease the noises on a CRT screen and at the same time to improve the cost properties and the transparency by grounding one of both ends of an electrode line of a tablet via a low resistance and at the same time thickening the pattern of a layer near the CRT screen in order to reduce the gap of the pattern. CONSTITUTION:When the tip 10 of a detection pen 9 serving as a coordinate pointing means touches a tablet 1, a switch 11 is turned on and the touch signal is supplied to a sample holding circuit 15, etc., via an input/output port 12. Then the electrostatic coupling is secured between the tip 10 and each electrode at the corresponding position of the tablet 1. This induced voltage is applied to a CPU 8 via an amplifier 13, the port 12, etc. The CPU 8 decides and outputs the absolute coordinates of the tablet 1 via a ROM 17, etc. In such a case, one of both ends of a transparent electrode line 3 of the tablet 1 is grounded via a low resistance (r). At the same time, the pattern of a layer near a CRT screen 5 is thickened to decrease the gap of the pattern. Thus a shielding layer is obtained for reduction of the noises on the screen 5. Furthermore, the cost is also reduced since no other shielding layer is not needed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a coordinate input device, and more particularly to a device for inputting data by attaching a capacitively coupled transparent coordinate input device to a CRT tube surface, LCD display surface, etc. It is something.

[Prior Art] In a conventional capacitive coupling type transparent coordinate input device, electrode wires are arranged at predetermined intervals in two orthogonal directions on a coordinate input board, and A detection electrode is provided on a coordinate indicating means such as an input pen, a force, or a crane that inputs coordinates by contacting a desired position. On the coordinate input board? ! ! Scanning pulses are sequentially applied to the polar lines, and at this time, the induced pulses generated at the detection electrodes of coordinate indicating means such as input pens and cursors are amplified by electrostatic induction, converted digitally, and supplied to calculation means consisting of a microcomputer. ,
This calculating means calculates the contact position of the coordinate indicating means based on the magnitude of the induced pulse at that time.

[Problems to be solved by the invention] By the way, in recent years, as a coordinate input V2U on the CRT screen,
Transparent touch panels are increasingly being adopted. The horizontal line of this highly transparent touch panel is made of ITO (
Many products use an ITO film (indium tin oxide), and the present invention also uses this ITO film, but the ITO film itself has high resistance and easily induces noise from the CRT tube surface, so it is necessary to shield it when using it. It was necessary to provide one layer and ground this shield layer to reduce the influence of tube surface noise. For this reason, there have been problems in that the cost is high and the transparency is also poor.

[Means for Solving the Problems] The present invention has been made to solve the above problems. A tablet comprising a plurality of electrode wires, a control unit that sequentially applies a pulse signal to each electrode wire of the tablet, and a coordinate indicating means that performs signal detection by capacitance coupling with the pulse applied to each electrode of the tablet. and a calculation unit that calculates position coordinates from signals detected by the coordinate indicating means, a resistor that is equivalently grounded to one end of each electrode wire of the tablet, and a resistor that is connected to the CRT, LCD, etc. The present invention proposes a transparent coordinate input device in which the width of the electrode line on the display surface side of the input device is increased.

[Function] The present invention provides a method for connecting one end of the electrode wire of the tablet described above to several hundred Ω.
By enlarging the electrode pattern in the layer near the CRT tube surface and narrowing the gap between the electrodes, the electrode wire to which no pulse is applied acts as a shield layer.

[Embodiment] An embodiment of the present invention will be described with reference to the accompanying drawings. 1st
The figure is a block diagram of the coordinate input device of the present invention, in which electrodes 2 and 3 shown expanded in FIG. 2 are disposed on a tablet 1 to be orthogonal to each other. The electrodes 2 and 3 are made of ITO and are vapor-deposited and etched on the films 4 and 4 as transparent electrodes. As for the spacing between the electrodes 2.3, as shown in FIG. 2, the electrode 3 on the side closer to the CRT 5 is wider and the gap is narrower. As shown in FIG. 3, each of the electrodes 2 and 3 of this tablet 1 is connected at one end to a power supply element (2) via a low resistance .gamma., and is further grounded. These low resistances γ, γ, . . . are connected to X, Y decoder drivers 6.7 provided for each axis direction and controlled by the CPU 8.

Next, when the tip 10 of the detection pen 9 is brought into contact with the tablet 1 as a coordinate indicating means for specifying a desired position on the tablet 1, the switch 11 becomes ○N, and the detection pen 9 is brought into contact with this tablet 1. The input/output boat 12 is notified of the fact that the The contact signal of the detection pen 9 on the tablet 1 from the input/output boat 12 is transmitted to the sample hold circuit 15,
When applied to the AD converter 6, the tip 10 of the detection pen 9 and each electrode 2, 3 at a corresponding position on the tablet 1 are electrostatically inductively coupled, and the generated induced voltage is applied to the amplifier 13,
The signal amplified by this amplifier 13 is passed through the low-cut filter 1
Sample and hold circuit 15, AD converter 16 via 4
are sequentially applied to the input/output port 12. Here, the position of the tablet that the tip 10 of the detection pen 9 is in contact with is supported by the input/output boat 12 and the voltage is applied to the CPU 8 .

The CPU 8 uses the ROM 17 or the RAM 18 to determine the absolute coordinates, relative coordinates, etc. of the tablet, and sends a predetermined coordinate signal to a host computer (not shown) via the input/output port 12.

Coordinate signals are input in this way, but CRT
If the tablet 1 is brought close to the CRT tube surface, electromagnetic waves as noise from the CRT tube surface will be applied to the tablet 1, resulting in a significant decrease in detection accuracy. Therefore, the electrode 2 of low resistance γ shown in FIG.
, 3 to which no pulse is applied will be pulled up to the power supply +■. Equivalently speaking, if the power source impedance is low, the resistor γ is in the same state as if it were connected to ground. (See FIG. 4) Here, the value of the resistor γ depends on the output capacitance of a portion of the driver at the previous stage. Therefore, when no pulse is applied to the electrode wire 3 as shown in FIG. 5, noise from the tube surface of the CRT 5 escapes to the ground via the low resistance γ. Furthermore, CRTS
By making the pattern of the electrode wires 3 near the tube surface thicker and narrowing the gap, a kind of shield layer can be formed.

[Effects of the Invention] Since the present invention has the above configuration, one end of the electrode wire of the tablet is grounded with low resistance.

By making the pattern of the layer close to the CRT tube surface thicker and narrowing the pattern gap, this layer becomes a shield layer and can reduce tube surface noise. Furthermore, issues in terms of cost and transparency have been resolved.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; Fig. 1 is a block diagram, Fig. 2 is a tablet structure diagram, Fig. 3 is a capacitive coupling state diagram, and Figs. 4 and 5 are equivalent circuit diagrams. be. 1...tablet, 2,3...electrode wire, 5...
CRT, 6, 7...decoder driver, 8...
CPU, 9...detection pen, 13...amplifier,
14...Low cutoff filter, 15...Sample hold circuit, 16...AD converter, γ...Low resistance patented Kenroku
Pendel Co., Ltd. No. 1

Claims (1)

[Claims] a tablet disposed close to a display surface of an input device such as a CRT or LCD and comprising a plurality of electrode wires arranged in the direction of coordinate axes; a control section that sequentially applies a pulse signal to each electrode wire of the tablet; A transparent coordinate input device comprising a coordinate indicating means for detecting a signal by capacitance coupling with a pulse applied to each electrode of a tablet, and a calculation section for calculating position coordinates from the signal detected by the coordinate indicating means, A transparent coordinate input device characterized in that a resistor is grounded equivalently to one end of each electrode wire of the tablet, and the width of the electrode wire on the display surface side of the input device such as a CRT or LCD is widened.