JP2005227409A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem associated with long time required for detecting a pressing position in a conventional liquid crystal display device, in which the pressing position is identified by using a capacitance value of a liquid crystal material resulting from a gap between transparent substrates, because in the case the number of pixels is increased, time to check a detection signal is increased. <P>SOLUTION: The liquid crystal display device has a detection signal driving means 2 to apply the signal 12 for detection to transparent electrodes 1, a pressing judging means 3 to judge whether there is a pressing on the liquid crystal display device or not with a signal outputted from the transparent electrodes 1, a switching means 4 arranged between the neighboring transparent electrodes 1 and opens or closes a gap between the neighboring transparent electrodes 1 and a switch controlling means 5 to control the switching means 4, and is constructed so as to form a detection domain 16 comprising a plurality of pixels of the liquid crystal display device with the switching means 4, to detect the pressing position in the domain as a unit, and at the same time, to make the detection domain 16 change corresponding to the display state of the liquid crystal display device. Thereby detection of the pressing position is carried out at high speed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device that detects a pressed position based on a change in the interval between transparent substrates of the liquid crystal display device.

2. Description of the Related Art Conventionally, devices that perform input by touching a display screen, such as mobile terminals and bank automatic deposit payment machines, are widely known. Among these, a resistance film type coordinate input device is widely used.
The resistive film type coordinate input device has a structure in which a touch panel made of two transparent resistive films is arranged on the display device, and the light transmittance is reduced, thereby deteriorating display quality. was there.

  In order to solve this problem, a liquid crystal display device with an input function that uses liquid crystal as a display device and uses the liquid crystal display device itself for input position detection is well known, and many proposals are being made (for example, patents). Reference 1).

A conventional liquid crystal display device disclosed in Patent Document 1 will be described with reference to the drawings. FIG. 4 is a principle diagram showing the conventional liquid crystal display device disclosed in Patent Document 1. In FIG. FIG. 5 is a detection circuit diagram of the conventional liquid crystal display device disclosed in Patent Document 1. In FIG.
In FIG. 4, 50 is the upper transparent electrode, 51 is the lower transparent electrode, and 52 is the equivalent capacity of the liquid crystal material. In FIG. 5, 54 is a comparator, 55 is a resistor, 56 is a reference capacitor, 57 is a detection drive signal, 58 is a reference signal, 59 is a pixel output signal, and 60 is a detection signal. In FIG. 5, the same components as those in FIG. 4 are given the same numbers.

  In general, a liquid crystal display device has a configuration in which a liquid crystal material is filled between two transparent substrates on which transparent electrodes are formed. The liquid crystal material can be regarded as a capacitance equivalently between the transparent electrodes. This is schematically shown in FIG. The equivalent capacitance 52 depends on the dielectric constant of the liquid crystal material and the spacing between the transparent substrates.

  The conventional liquid crystal display device disclosed in Patent Document 1 detects the pressing position by detecting that the distance between the transparent substrates at the pressing position decreases and the equivalent capacity 52 increases accordingly when the display screen is pressed. It is something to identify.

The detection procedure will be described below. First, the liquid crystal display device is provided with a detection period for detecting an input position separately from a display period for performing normal image display. In the display period, a drive signal based on the display image is applied to the transparent electrodes 50 and 51. In the detection period, as shown in FIG. 5, the lower transparent electrode 51 is connected to a resistor 55 grounded on one side, and a detection drive signal 57 is applied from the upper electrode 50.
At this time, the pixel output signal 59 output from the lower transparent electrode 51 depends on the value of the resistor 55 and the value of the equivalent capacitance 52 based on the interval between the transparent substrates. Therefore, the comparator 54 can compare the reference signal 58 that is an output from the reference capacitor 56 having a capacitance value when the transparent substrate is not pressed and the pixel output signal 59 that is an output from each pixel. By pressing the detection signal 60 sequentially, the pressed position can be specified.

JP-A-6-34940 (page 3-4, FIG. 1, FIG. 5)

  However, in the conventional liquid crystal display device disclosed in Patent Document 1, when the number of pixels increases, the time for examining the detection signal 60 increases, and accordingly, the time required for detecting the pressed position increases. There were drawbacks.

  An object of the present invention is to solve the above-described problems, and to provide a liquid crystal display device capable of detecting a pressed position at high speed.

  In order to achieve the above object, the liquid crystal display device of the present invention employs the following structure.

A liquid crystal display in which a liquid crystal material is filled between two transparent substrates on which transparent electrodes are formed, and the liquid crystal display detects a pressing position based on a change in the interval between the transparent substrates that is generated when the liquid crystal display is pressed. A device,
A detection signal driving unit that applies a detection signal to the transparent electrode, a press determination unit that determines whether or not the liquid crystal display device is pressed based on a signal output from the transparent electrode, and between adjacent transparent electrodes Switch means for opening and closing, and switch control means for controlling the switch means,
A detection target area composed of a plurality of pixels of the liquid crystal display device is created by the switch means, and the pressed position is detected in units of the detection target area.

  The liquid crystal display device is characterized by having a plurality of transparent electrodes in each of the X direction and the Y direction.

According to the liquid crystal display device of the present invention, by providing the switch means for opening and closing between the transparent electrodes, this switch means can be controlled to create a detection target region composed of a plurality of pixels of the liquid crystal display device.
On the liquid crystal display device, instead of detecting a uniform pressing position over the entire surface, a detection target area is formed, and the detection of the pressing position is performed in units of the detection target area, thereby speeding up the detection of pressing. be able to.
This is a characteristic part of the present invention, and is very effective when a region that does not require a relatively high resolution and a region that requires a high resolution are mixed on the liquid crystal display device. That is, the detection target area can be enlarged in an area that does not require relatively high resolution, and the detection target area can be reduced in an area that requires high resolution. In this way, by changing the detection target region, it is possible to efficiently detect the pressed position. For this reason, the time required for one detection can be shortened.

  Further, the shape of the detection target region can be freely changed according to the display state of the liquid crystal display device. Thereby, the detection of the pressed position can be further accelerated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a liquid crystal display device of the present invention, FIG. 2 is a cross-sectional view of the liquid crystal display device of the present invention, and FIG. 3 is a schematic diagram of pressure detection of the liquid crystal display device of the present invention. .

[Description of structure: Fig. 1, Fig. 2, Fig. 3]
First, the structure of the liquid crystal display device of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG.
As shown in FIG. 1, 6 is a transparent substrate, 1 is a transparent electrode formed on the upper and lower transparent substrates 6 in the X direction and the Y direction, 2 is a detection signal driving means, and 3 is a press for judging the presence or absence of the press. Determination means 4 is a switch means for opening / closing between adjacent transparent electrodes 1, 5 is a switch control means for controlling the switch means 4, and 16 is a detection target region.
In FIG. 1, the transparent electrode 1 is an example in which several electrodes are displayed in both the X direction and the Y direction. The switch means 4 is mechanically or electrically switched, for example, a mechanical contact switching device or a semiconductor switching element. However, in order to simplify the display in FIG. doing.
As shown in FIG. 2, reference numeral 7 denotes a liquid crystal material filled between the transparent substrates 6. FIG. 2 shows a state where the upper transparent substrate is deformed by pressing from the upper part of the drawing.
As shown in FIG. 3, 8 is an equivalent capacitance based on the liquid crystal material 7 between the transparent electrodes 1, 9 is a resistor, 10 is a settable threshold voltage generator, 11 is a comparator, 12 is a detection signal, and 13 is a region output. A signal, 14 is a threshold signal, and 15 is a determination signal.
2 and 3, the same components as those in FIG. 1 are given the same numbers.

[Description of action]
The operation of the liquid crystal display device of the present invention will be described. First, the principle of coordinate detection as one of them will be described with reference to FIG. The liquid crystal display device has a configuration in which a liquid crystal material 7 is filled between upper and lower transparent substrates 6 on which transparent electrodes 1 are formed in the X direction and the Y direction, respectively, and the liquid crystal material 7 is regarded as an equivalent capacity 8 between the transparent electrodes 1. Can do. The equivalent capacitance 8 depends on the dielectric constant of the liquid crystal material 7 and the distance between the transparent substrates 6. When pressing occurs, the distance between the upper and lower transparent substrates 6 decreases as shown in FIG. 2, and the equivalent capacity 8 increases accordingly. This change in the equivalent capacitance 8 is detected in a detection period in which the pressed position is detected separately from the display period in which normal image display is performed.

Next, the procedure for detecting the pressed position will be described with reference to FIG. In order to detect a press in the detection target region 16 on the display screen, the switch control unit 5 connects the plurality of transparent electrodes 1 in the X direction and the plurality of transparent electrodes 1 in the Y direction that pass through the detection target region 16, respectively. The switch means 4 is controlled. In the example shown in FIG. 1, the switch means 4 has shown the case where it turns ON 2 each in X direction and Y direction.
The detection signal driving unit 2 applies the detection signal 12 to the detection target region 16 through the transparent electrode 1 in the X direction. The pressing determination means 3 receives the output signal from the detection target region 16 through the transparent electrode 1 in the Y direction, and determines the presence or absence of pressing.

Next, operation | movement of the press judgment means 3 is demonstrated using FIG. As shown in FIG. 3, a resistor 9 grounded on one side is connected to the transparent electrode 1 in the Y direction on the output side. As a result, a CR circuit is formed by the equivalent capacitor 8 combined with the detection target region 16 and the resistor 9.
The detection signal 12 applied by the detection signal driving means 2 is output as a region output signal 13 via the CR circuit. The threshold voltage generator 10 is set according to the width of the detection target region 16 and generates a threshold signal 14 based on these settings. The comparator 11 compares the region output signal 13 with the threshold signal 14 and generates a determination signal 15 indicating the presence or absence of pressing.

Usually, the display screen displayed by the user interface of an application often has an area such as an icon that does not require a relatively high resolution and an area such as a handwritten input frame that requires a high resolution.
According to the state of the display screen based on such a request from the application, the switch control unit 5 shown in FIG. 1 can control the switch unit 4 to freely change the shape of the detection target region 16. This is the characteristic part of the present invention.

For example, for a handwritten input frame area that requires high resolution, the switch means 4 is opened to detect the pressed position in pixel units, and for an icon area that does not require relatively high resolution, By connecting the means 4 and enlarging the detection target area 16 to the size of the icon or larger, the user's press can be determined by a single detection by the press determination means 3, and very fast coordinate detection Is possible.

The liquid crystal display device of the present invention has an unprecedented effect that the detection target area for detecting the pressure on the liquid crystal display device can be freely changed according to the display screen.
Since the liquid crystal display device of the present invention can detect a press at a high speed, it is possible to increase the degree of freedom such as the shape and size of the area of the icon and the handwriting input frame displayed on the liquid crystal display device and the layout on the screen. For example, even if a long icon or region is provided in a specific direction on the liquid crystal screen, the pressure detection speed does not decrease.

  The liquid crystal display device of the present invention can freely change the detection target region by controlling the connection of the adjacent transparent electrodes by using the switch means and the switch control means. Since it can be freely changed according to the display state of the apparatus, there is an excellent effect that the pressed position can be detected at high speed. Therefore, the coordinate input device of the present invention can be applied to a portable terminal, a bank automatic deposit payment machine, and the like.

It is a block diagram which shows the liquid crystal display device of this invention. It is sectional drawing which shows the liquid crystal display device of this invention. It is a schematic diagram of the press detection which shows the liquid crystal display device of this invention. It is a principle figure which shows a prior art. It is a detection circuit diagram which shows a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent electrode 2 Detection signal drive means 3 Press judgment means 4 Switch means 5 Switch control means 6 Transparent substrate 7 Liquid crystal material 8 Equivalent capacity 9 Resistance 10 Threshold voltage generator 11 Comparator 12 Detection signal 13 Area output signal 14 Threshold signal 15 Determination signal 16 Detection target area 50 Upper transparent substrate 51 Lower transparent substrate 52 Equivalent capacitance 54 Comparator 55 Resistance 56 Reference capacitance 57 Detection drive signal 58 Reference signal 59 Pixel output signal 60 Detection signal

Claims (2)

A liquid crystal display device in which a liquid crystal material is filled between two transparent substrates on which transparent electrodes are formed, and the liquid crystal display device detects a pressed position based on a change in the interval between the transparent substrates that occurs when pressed. A liquid crystal display device,
A detection signal driving unit that applies a detection signal to the transparent electrode, a pressure determination unit that determines whether or not the liquid crystal display device is pressed based on a signal output from the transparent electrode, and adjacent to the transparent electrode. Switch means for opening and closing between the transparent electrodes, and switch control means for controlling the switch means,
A liquid crystal display device, wherein a detection target region composed of a plurality of pixels of the liquid crystal display device is created by the switch means, and the previous pressing position is detected in units of the detection target region.   The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a plurality of the transparent electrodes in each of an X direction and a Y direction.

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