JPH06250786A - Matrix type display panel and coordinate input device using the same - Google Patents

Abstract

PURPOSE:To enable two-dimensional manual input using only surface layer electrodes of the matrix type display panel by providing electrodes in twin constitution on the surface layer side of the matrix type display panel, and scanning a display and surface layer electrode group and a surface layer electrode group on a time-division basis. CONSTITUTION:An LCD panel 1 consists of a liquid crystal layer, common electrode layers which are provided on both its sides by arraying plural long electrodes in a column direction, a segment electrode layer formed by arraying plural long electrodes in a top direction, and two polarizing plates which are provided further on both sides. A driving pulse is supplied to each segment electrode in order to detect a row coordinate, and then potential variation is generated at a finger tip when the electrode potential of an indicated part varies. This signal is larger and larger as the coupling capacity between the finger and driving electrode is larger and larger, so the position indicated with the finger can be known from the peak of the detection signal. When a column coordinate is detected, right and left segment electrodes are scanned on a time- division basis.

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 using a matrix type display panel.

[0002]

2. Description of the Related Art Conventionally, coordinate input using a display panel has been tried. In particular, in coordinate input using a pen with a code, a resolution of about 0.3 mm can be realized. However, considering the coordinate input in the portable device, it is troublesome to take out the stored pen every time it is used, and it is convenient to be able to point with a finger if it is about menu selection, but it is convenient to input manually using the display panel. Could not be realized.

In order to solve this problem, according to Japanese Patent Application No. 5-016114 proposed by the present applicant, the drive signal of the display panel is extracted by using the human body as a signal path.
There is a coordinate input device integrated with a display device that realizes manual input.

An example of this coordinate input device will be described below with reference to the drawings. FIG. 8 shows a schematic configuration of a conventional coordinate input device. In FIG. 8, 1 is a display panel represented by an LCD panel, 2 is a common electrode driver, 3 is a segment electrode driver, 4 is a controller, and 5 is a coordinate detection circuit.

The LCD panel 1 comprises a liquid crystal layer, a common electrode layer in which a plurality of long electrodes x provided on both sides thereof are arranged in a column direction, and a segment electrode layer in which a plurality of long electrodes y are arranged in a row direction. Further, it is composed of two polarizing plates provided on both sides thereof.

This LCD panel is used for both display and coordinate detection, but its driving is performed in a time division manner.

First, the display operation of the LCD panel will be briefly described. In the display period, the common electrode is scanned line by line for each of the left and right segment electrode groups, and a signal voltage corresponding to the scan line is applied to the segment electrodes all at once to display an arbitrary image. When a TN cell is used as the liquid crystal element, the polarization direction does not rotate when a signal voltage is applied, and the polarization direction is 90 degrees when no signal voltage is applied.
Rotate once. If the polarization direction of the first polarizing plate and the polarization direction of the second polarizing plate are orthogonal to each other, the light from the backlight is transmitted when no signal voltage is applied.

Next, the coordinate detecting operation will be described. In inputting the coordinates, for example, as shown in FIG. 4, the main body is held with the left hand and the right hand is used for the instruction. At this time, the left hand is touching the input terminal of the detection circuit. The input terminal may be a pen tip that is stored. The coordinates are detected by transmitting the drive signal of the LCD panel obtained by the right hand to the detection circuit through the human body.

In detecting the row coordinates, the common electrodes x1, x2, ... Xn are set to appropriate electric potentials, and the segment electrodes y1, y2 ,. At this time, the drive signal of the segment electrode is extracted by using the electrostatic capacitance between the finger. For example, as shown in FIG. 9, each segment electrode y1,
When a drive signal is applied to y2, ... Yn, a potential change like Y in the figure occurs at the fingertip. At this time, the larger the coupling capacitance between the finger and the drive electrode, the larger the detected signal. This signal is input to the input terminal of the detection circuit through the human body. The detection circuit detects the row coordinates based on the peak of the input signal.

Similarly, in detecting the column coordinates, the segment electrodes y1, y2, ... Yn are set to appropriate electric potentials,
The column coordinates are detected by scanning the common electrodes x1, x2, ... Xn and detecting the peak of the detected signal. The change in the detection signal at this time is indicated by X.

[0011]

However, in the above structure, the coupling between the back layer electrode and the finger is as small as about 1/10 of the coupling between the surface layer electrode and the finger, and noise generated by the human body is generated. Drive signal of the back electrode is high S /
It is very difficult to take out with N. Therefore, it is necessary to provide an average value circuit in order to cancel the noise generated by the human body that has no correlation with the detection signal, and to detect the peak position after taking an average of about 30 times.

Therefore, there is a problem that the coordinate input speed is slowed down to take the average, and a relatively high speed AD converter is required to realize the average value circuit, resulting in an increase in cost. .

In view of the above problems, the present invention provides a method for realizing a two-dimensional manual input using a matrix type display panel without an average value circuit.

[0014]

In order to solve the above-mentioned problems, the coordinate input device of the present invention has a structure in which the electrodes on the surface layer side of the matrix type display panel to be used are made up of two rows, and the display and the surface layer electrode group 1 are scanned. The scanning of the surface layer electrode group 2 is performed in a time division manner.

[0015]

According to the present invention, by utilizing only the surface layer electrode for the coordinate detection by the above-mentioned constitution, the detection signal by the back layer electrode having a weak signal strength can be omitted.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A coordinate input device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the outline of the configuration of the coordinate input device in the embodiment of the present invention. In FIG. 1, 1 is a display panel represented by an LCD panel, 2 is a common electrode driver, 3 is a segment electrode driver, 4
Is a controller, and 5 is a detection circuit.

The LCD panel 1 includes a common electrode layer in which a liquid crystal layer and a plurality of long electrodes x provided on both sides thereof are arranged in a column direction, and a segment electrode layer in which a plurality of long electrodes y are arranged in a row direction. Further, it is composed of two polarizing plates provided on both sides thereof. Here, an LCD panel having a double structure in which the length of the segment electrode is half the length in the row direction is used, and the LCD panel is divided and driven.

Like the conventional example, this LCD panel is used for both display and coordinate detection, and each operation is performed in time division. Since the display operation is exactly the same as the conventional example, the description thereof will be omitted, and the coordinate detection operation will be described.

First, when detecting the row coordinates, the common electrode is set to an appropriate potential and the segment electrode on the front side is scanned as in the conventional example. The signal is taken out by using the capacitance between the finger. For example, when a drive pulse is applied to each of the segment electrodes y1, y2, ... Yn as shown in FIG. 2, a potential change occurs at the fingertip when the electrode potential of the indicated portion changes. That is, this signal becomes larger as the coupling capacitance between the finger and the drive electrode becomes larger, so that the position pointed by the finger can be known from the peak of the detection signal. For example, when it is on the segment electrodes 31 to 60, it becomes as shown in FIG. This signal is input to the input terminal of the detection circuit through the human body, the detection circuit detects the peak of the signal, and the row coordinates are obtained.

When detecting the column coordinates, the left and right segment electrodes are detected by time-divisional scanning. When the segment electrodes are driven as shown in FIG. 2, when the position where the finger is placed is α, β, γ on the panel (see FIG. 1), the detection signals in each case are the detection signals α, β. ,
It becomes like γ. When a finger is placed on the left side of the panel, a signal is detected by scanning the segment electrode yL on the left side, and when a finger is placed on the right side of the panel, a signal is detected by scanning the segment electrode yR on the right side. When a finger is placed in the center, the left and right segment electrodes yL,
Signals can be detected in any of the yR scans, and column coordinates can also be detected.

By using the coordinate input device according to the present embodiment, it becomes possible to manually input, for example, a push button of a telephone as shown in FIG. 3 or select a menu.

As described above, the display panel is arranged so that the segment electrode layer is on the front side by using the LCD panel having a double structure, and the display, the scanning of the segment electrode group 1 and the scanning of the segment electrode group 2 are time-shared. By doing so, it is possible to detect the two-dimensional coordinates by using only the surface electrode having a high signal intensity without using the electrode of the back layer having a low signal intensity.

Next, the coordinate input device of the second embodiment will be described which is provided with means for widening the central area of the coordinate input device of the first embodiment.

In order to solve this problem, two types of segment electrode lengths are prepared as shown in FIG. 5, and the left and right segment electrodes are alternately covered near the center. When the coordinate input device is configured using such a display panel, a detection signal can be obtained by scanning either of the left and right segment electrodes in a region where the left and right segment electrodes appear alternately.

By changing the length of the segment electrode as described above, the width of the detection region can be changed arbitrarily, and the three obtained regions can be moved arbitrarily.

Further, in the conventional LCD panel having a double structure, a large brightness difference appears near the center, but by adopting the structure as described above, the density becomes half and the brightness change becomes small.

Next, the coordinate input device of the third embodiment for the purpose of enhancing the resolution in the column direction will be described.

In order to solve the above problems, a display panel having segment electrodes of several kinds of length is used.

For example, an LCD panel having a structure in which segment electrodes having three types of lengths are arranged in order as shown in FIG. 6 will be described. In the region of α in the figure, the number of segment electrodes A on the right side is 3 and the number of segment electrodes B on the left side is 0. Therefore, the ratio of the signal obtained by scanning the segment electrode group A and the signal obtained by scanning the segment electrode B is 3: 0. Similarly, the signal ratio in each region of β, γ, and δ is as shown in (Table 1).

[0031]

[Table 1]

As described above, by using the display panel having the segment electrodes of plural kinds of lengths, when the ratio of the detection signals obtained when the left and right segment electrode groups are scanned is measured, the resolution in the column direction can be obtained. It will be possible to improve.

Next, a coordinate input device according to a fourth embodiment for reducing the number of segment electrode drivers used will be described.

In order to solve the above-mentioned problem, a display panel having both a double-structured portion and a single-structured portion is used. An example of such a coordinate input device is shown in FIG.

Since the size of the finger is fixed, the manual input does not need to be highly accurate, and the resolution in the column direction is originally low, so the resolution in the row direction need not be so high. Therefore, it is possible to reduce the number of segment drivers to be used by adopting a two-series configuration so that the coordinates can be detected only in a necessary portion and a single configuration for the rest.

As described above, by using the liquid crystal having a single or double structure, it is possible to add a two-dimensional manual input function at a relatively low cost.

In the above-mentioned four embodiments, an example of pointing with a finger is shown. However, as long as the induced voltage due to the drive signal of the display panel can be detected, a metallic pen that conducts electricity is held in the hand. If it is okay to instruct by inputting, it is possible to input using an indicator with a code.

[0038]

As described above, according to the present invention, the two liquid crystal panels are used, the coordinate detection period is provided independently of the display period, and the two groups of segment electrode drivers are time-divisionally scanned during the coordinate detection period. As a result, two-dimensional manual input is possible using only the segment electrodes on the surface layer.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a coordinate input device according to a first embodiment of the present invention.

FIG. 2 is an operation timing chart of the coordinate input device according to the first embodiment of the present invention.

FIG. 3 is a plan view of a usage example of the coordinate input device according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a use state of the coordinate input device according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram of a coordinate input device according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of a coordinate input device according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of a coordinate input device according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram of a conventional coordinate input device.

FIG. 9 is an operation timing chart of the coordinate input device in the conventional example.

[Explanation of symbols]

 1 Display Panel 2 Common Electrode Driver 3 Segment Electrode Driver 4 Controller 5 Detection Circuit 6 Liquid Crystal Layer 7 Common Electrode Layer 8 Segment Electrode Layer 9 First Polarizing Plate 10 Second Polarizing Plate 11 Backlight

Claims (4)

[Claims] 1. An electrode layer 1 comprising an electrode group 1 in which a plurality of long electrodes are arranged in parallel and an electrode group 2 in which a plurality of long electrodes are arranged on an extension line of each long electrode of the electrode group 1. And the electrode layer 1
Is arranged at an intersection of an electrode layer 2 composed of an electrode group in which a plurality of long electrodes are arranged in parallel in a direction orthogonal to the long electrodes and each of the two long electrodes of the electrode layer 1 and the electrode layer 2. Matrix display panel composed of a large number of display elements, an electrode driver for driving the electrodes, a controller for controlling the electrode drivers, and an induced voltage at an input instruction point by a drive signal of electrodes on the display panel. And a coordinate detection circuit for detecting the coordinates of the input designated point, the display panel is arranged so that the electrode layer 1 is on the front side, and display, scanning of the electrode group 1 of the electrode layer 1, A coordinate input device characterized in that the scanning of the electrode group 2 is performed in a time division manner. 2. An electrode group 1 in which a plurality of long electrodes of a plurality of different lengths are arranged in parallel, and a large number of long electrodes in the electrode group 1.
The electrode layer 1 including the electrode group 2 arranged on the extension line of each long electrode, and the electrode group in which a plurality of electrodes arranged in a direction orthogonal to the long electrodes of the electrode layer 1 are arranged in parallel. A matrix type display panel comprising: an electrode layer 2; and a plurality of display elements arranged at respective intersections of the long electrodes of the electrode layer 1 and the long electrodes of the electrode layer 2. 3. A matrix type display panel according to claim 2, an electrode driver for driving each electrode, a control circuit for controlling the electrode driver, and an input instruction point by a drive signal of an electrode on the display panel. And a coordinate detection circuit that detects the coordinates of the input instruction point from the induced voltage of the display panel, the display panel is arranged so that the electrode layer 1 is on the front side, and display, scanning of the electrode group 1 of the electrode layer 1, electrode A coordinate input device characterized in that scanning of group 2 is performed in a time division manner. 4. The matrix type display panel according to claim 2, wherein each column of the electrode layer 1 has a portion formed by one long electrode and a portion formed by two long electrodes. .