KR20080015541A - Interactive LCD - Google Patents

Abstract

A bidirectional liquid crystal display device having a touch panel function is disclosed. The bidirectional liquid crystal display device includes a display panel, a light guide plate, a first polarizing plate, and a second polarizing plate. The display panel includes reflection pixels and transmission pixels to display images in both directions. The light guide plate is formed on one side of the display panel to guide light to the display panel to emit light, and a first transparent electrode is formed. The first polarizing plate is spaced apart from the first transparent electrode by a predetermined distance, and a second transparent electrode is formed in electrical contact with the first transparent electrode to generate position information. The second polarizing plate is formed on the other side of the display panel opposite to one side of the display panel on which the light guide plate is formed. Accordingly, the bidirectional liquid crystal display device has a touch panel function and can further improve surface visibility.

Description

Interactive Liquid Crystal Display {DUAL LIQUID CRYSTAL DISPLAY}

1 is an exploded perspective view illustrating a bidirectional liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line II ′ of FIG. 1.

3 is a cross-sectional view illustrating an operation as a touch panel of a bidirectional liquid crystal display according to an exemplary embodiment of the present invention.

4 is a cross-sectional view illustrating a surface treatment film formed on an upper portion of the first polarizing plate illustrated in FIG. 1.

FIG. 5 is a side view of the bidirectional liquid crystal display of FIG. 1. FIG.

6 is a plan view illustrating a portion of the display panel illustrated in FIG. 5 in detail.

7 is a side view illustrating another embodiment of FIG. 5.

<Description of the symbols for the main parts of the drawings>

200: display panel 210: first substrate

220: second substrate 230: liquid crystal layer

240: transmission pixel 250: reflection pixel

400: Light guide plate 410: First electrode

430 dot spacer 500 first polarizing plate

510: second electrode 520: surface treatment film

600: touch panel 610: point light source

800: bidirectional liquid crystal display device

The present invention relates to a bidirectional liquid crystal display device, and more particularly, to a bidirectional liquid crystal display device having a touch panel function.

Recently, in order to efficiently use various display devices including a liquid crystal display device, a touch screen panel (TSP) for inputting a signal to a display surface of a display device without a remote controller or a separate input device has been applied. .

The touch panel detects the position where the hand or the object is in contact with, and receives the content indicated by the touched position as an input signal to drive the liquid crystal display. As a liquid crystal display device having a touch panel does not require a separate input device such as a keypad, its use is increasing mainly on portable electronic devices.

BACKGROUND ART A resistive touch panel is widely used in a liquid crystal display device requiring a small thin film type. Specifically, in the resistive touch panel, when two conductive layers are contacted by pressing a desired point while a voltage is applied to two opposing conductive layers, the resistive touch panel detects a voltage or current change occurring at a contact point and converts the coordinates into coordinate values. It works.

However, as the liquid crystal display includes the touch panel as described above, a problem arises in that the thickness or size of the entire product increases, the optical characteristics decrease, and the manufacturing cost increases. In addition, compared to the light emitted from the liquid crystal display device for displaying an image, as a very strong external light such as direct sunlight is reflected on the surface of the display device, there is a problem that visibility is reduced.

Accordingly, the technical problem of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a two-way liquid crystal display device having a touch panel function while improving visibility and increasing thickness and manufacturing cost.

In order to realize the above object of the present invention, a bidirectional liquid crystal display device includes a display panel, a light guide plate, a first polarizing plate, and a second polarizing plate. The display panel includes a reflection pixel and a transmission pixel to display an image in both directions. The light guide plate is formed on one side of the display panel to guide light to the display panel and to emit light, and a first transparent electrode is formed. The first polarizing plate is spaced apart from the first transparent electrode by a predetermined distance, and a second transparent electrode is formed in electrical contact with the first transparent electrode to generate position information. The second polarizing plate is formed on the other side of the display panel facing the one side.

In this case, it is preferable that a hard coating film for protecting the first polarizing plate and an anti-reflection film for preventing light reflection occurring on the surface of the first polarizing plate are formed on the first polarizing plate.

According to the bi-directional liquid crystal display device, as the image is displayed in both directions using one light and one display panel, the thickness of the bi-directional liquid crystal display device can be reduced, optical properties can be improved, and manufacturing cost can be reduced. . In addition, by implementing a touch panel function using a polarizing plate, the visibility of the bidirectional liquid crystal display device may be improved.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention.

1 is an exploded perspective view illustrating a bidirectional liquid crystal display according to an exemplary embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II ′ of FIG. 1, and FIG. 3 is a bidirectional liquid crystal according to an exemplary embodiment of the present invention. It is sectional drawing which shows operation | movement as a touchscreen of a display apparatus.

1, 2 and 3, the bidirectional liquid crystal display 800 according to the exemplary embodiment of the present invention may include a display panel 200, a point light source 401, a light guide plate 400, and a first polarizing plate 500. ) And a second polarizing plate 700.

The display panel 200 is disposed under the light guide plate 400 and displays an image by using light supplied from the light guide plate 400. The display panel 200 displays the first image using light emitted from the light guide plate 400 and transmitted through the display panel 200, and uses light emitted from the light guide plate 400 and reflected from the display panel 200. To display the second image.

The display panel 200 is coupled to the first substrate 210 and the first substrate 210, and is coupled between the second substrate 220 and the first substrate 210 and the second substrate 220 adjacent to the light unit. The liquid crystal layer 230 is interposed therebetween.

In the present exemplary embodiment, the first substrate 210 is a thin film transistor substrate on which driving elements such as signal lines and thin film transistors are formed, and the second substrate 220 is a color filter substrate on which a color filter for expressing color is formed.

The liquid crystal layer is interposed between the first substrate 210 and the second substrate 220, and the arrangement of the liquid crystal layer 230 is changed by an electric field formed between the pixel electrode and the common electrode. As the arrangement of the liquid crystal molecules included in the liquid crystal layer 230 is changed, the display panel 200 may change an optical transmittance to display an image having a desired gray scale.

The display panel 200 further includes a driving chip 240 for driving the display panel 200. The driving chip 240 generates a driving signal for driving the display panel 200 in response to various control signals applied from the outside.

The point light source 401 is disposed at least one side of the light guide plate 400, and generates light in response to the power applied from the outside. For example, the point light source 401 is formed of a light emitting diode (LED) that generates white light. The number of light emitting diodes may vary depending on the exit angle and the size of the light guide plate 400.

The light guide plate 400 is disposed on the display panel 200 and guides a traveling path of light incident from the point light source 401 to emit light toward the display panel 200. The light guide plate 400 is made of a transparent material to minimize the loss of light. For example, the light guide plate 400 may be made of polymethyl methacrylate (PMMA) having excellent hardness.

The first transparent electrode 410 is formed on the front surface of the light guide plate 400 facing the first polarizer 500. For example, the first transparent electrode 410 may include indium tin oxide (ITO) or indium zinc oxide (IZO), which are transparent conductive materials.

The light guide plate 400 may further include prism patterns 405 formed on the bottom surface of the light guide plate 400. The prism patterns 405 focus the light incident through the side surface of the light guide plate 400 upward to improve front brightness. For example, the prism patterns 405 may be formed in a triangular prism shape on the lower surface or the upper surface of the light guide plate 400.

The first polarizer 500 is spaced apart from the light guide plate 400 by a predetermined interval and is formed on the light guide plate 400. The first polarizer 500 transmits light that vibrates in a specific direction and absorbs light that vibrates in the other direction. Therefore, the first polarizing plate 500 polarizes the light incident from the light guide plate 400 disposed below.

The first polarizer 500 may be deformed by an external touch and may be made of a plastic material having elasticity. In addition, the first polarizing plate 500 is preferably made of a transparent material that can transmit light. For example, the first polarizing plate 500 may be made of a poly vinyl alcohol (PVA) film.

At this time, the first polarizing plate 500 transmits the light vibrating in a specific direction among the light incident from the outside, and absorbs the light vibrating in the remaining direction. Accordingly, the external light is absorbed without being reflected from the surface of the first polarizing plate 500, thereby minimizing interference between the external light and the light emitted from the light guide plate 400.

The second transparent electrode 510 is formed on the front surface of the first polarizer 500 facing the light guide plate 400. For example, the second transparent electrode 510 may include indium tin oxide (ITO) or indium zinc oxide (IZO).

The bidirectional liquid crystal display 800 further includes dot spacers 430 formed between the light guide plate 400 and the first polarizer 500. The dot spacers 430 are formed to be spaced apart from each other by the light guide plate 400 and the optical film 500. In detail, the dot spacers 430 are disposed between the first transparent electrode 410 and the second transparent electrode 510 to fill a predetermined gap between the first transparent electrode 410 and the second transparent electrode 510. Keep it. For example, the dot spacers 430 may be made of an insulating resin material such as epoxy or acrylic resin.

In the present embodiment, the dot spacers 430 are formed on the top surface of the first transparent electrode 410. Alternatively, the dot spacers 430 may be formed on the bottom surface of the second transparent electrode 510.

The light guide plate 400 and the first polarizing plate 500 may be connected by an insulating adhesive 450 formed between both ends of the first transparent electrode 410 and the second transparent electrode 510 to function as a touch panel. For reference, the first and second transparent electrodes 410 and 510 may receive different driving voltages from an external power supply (not shown), respectively.

Specifically, when the upper surface of the first polarizing plate 500 is pressed by the touch T of a pen or finger, the second transparent electrode 510 and the first transparent electrode 410 are in contact with each other and electrically shorted. As a result, a signal having a current amount or a voltage level that varies at the contact point is generated. The touch recognition unit (not shown) connected to the bidirectional liquid crystal display device 800 detects the signal, converts the coordinate into a coordinate value, and operates to recognize the content selected by the touch.

In this case, in order to accurately detect the position of the contact point, it is necessary to prevent the first transparent electrode 410 and the second transparent electrode 510 from contacting at the peripheral portion except for any contact position. For this purpose, the plurality of dot spacers 430 may be arranged to be spaced apart from the first transparent electrode 410.

The second polarizer 700 is disposed under the display panel 200. The second polarizing plate 700 transmits light vibrating in a specific direction and absorbs the remaining light. Therefore, the second polarizing plate 700 polarizes the light passing through the liquid crystal layer 230 of the display panel 200. The second polarizer 700 is attached to the first substrate 210 through an adhesive or an adhesive tape.

For example, the first polarizing plate 500 and the second polarizing plate 700 are disposed so that their transmission axes are perpendicular to each other. On the contrary, the first polarizing plate 500 and the second polarizing plate 700 may be arranged such that transmission axes between them are at an acute angle or may be arranged in parallel with each other.

4 is a cross-sectional view illustrating a surface treatment film formed on an upper portion of the first polarizing plate illustrated in FIG. 1.

3 and 4, it is preferable that a surface treatment film 520 is formed on the first polarizing plate 500 in the present embodiment.

In the bi-directional liquid crystal display 800, as shown in FIG. 3, the same portion is repeatedly pressed by a user's finger or an object. By the repetitive operation as described above, the surface of the first polarizing plate 500 may be damaged. In order to prevent this, the surface treatment film 520 may be formed on the first polarizer 500. The surface treatment film 520 includes a hard coating film 522 and an antireflection film 524.

The hard coat layer 522 is formed on the first polarizer 500 to protect the first polarizer 500. For example, the hard coating layer 522 may be made of polyacrylic material.

 The anti-reflection film 524 is formed on the hard coating film 522 and prevents light incident from the outside of the bidirectional liquid crystal display device 800 from being reflected from the surface of the hard coating film 522. Accordingly, the anti-reflection film 524 may prevent a glare phenomenon occurring on the surface of the first polarizing plate 500 exposed to the outside.

In order to prevent glare, the anti-reflection film 524 preferably has a haze value of a predetermined level or more. The anti-reflection film 524 may include, for example, two or more kinds of scattering materials having different refractive indices. In addition, the anti-reflection film 524 may be, for example, the surface of the anti-reflection film 524 may be formed in a fine concavo-convex shape.

As in the present exemplary embodiment, the surface treatment film 520 may include a hard coating film 522 and an antireflection film 524, and the hard coating film 522 and the antireflection film 524 may be formed of different layers. In contrast, the surface treatment layer 520 may be formed of a single layer that is hard coated and anti-reflected for hardness and reflection reduction.

FIG. 5 is a side view of the bidirectional liquid crystal display of FIG. 1, FIG. 6 is a plan view showing a part of the display panel of FIG. 5 in detail, and FIG. 7 is a side view of another embodiment of FIG. 5.

For reference, since the point light source 401 and the light guide plate 400 of the bidirectional liquid crystal display device 800 serve to emit light toward the display panel 200, the point light source 401 and the light guide plate 400 may be included. The term light unit will be described later as a concept.

5 and 6, the display panel 200 displays an image in both directions using light emitted from the light unit. The bidirectional liquid crystal display 800 according to the present exemplary embodiment has a front light structure in which a light unit is disposed on the display panel 200.

The display panel 200 displays the first image using the light L1 supplied from the light unit and transmitted through the display panel 200, and the light L2 supplied from the light unit and reflected from the display panel 200. To display the second image. The first image and the second image may be the same image or may be different images.

Referring to FIG. 6, the display panel 200 includes transmissive pixels 240 through which light from the light unit is transmitted and reflective pixels 250 through which light from the light unit 200 is reflected. In this case, the transmission pixels 240 and the reflection pixels 250 may be alternately disposed.

The display panel 200 includes a first substrate 210, a second substrate 220 coupled to face the first substrate 210, and a liquid crystal layer disposed between the first substrate 210 and the second substrate 220. (230). In this case, the second substrate 220 is disposed to be adjacent to the light unit.

The first substrate 210 is an array substrate in which thin film transistors (hereinafter referred to as TFTs), which are switching elements, are formed in a matrix form. In detail, the first substrate 210 may include gate lines 213 and data lines 214 defining the transmission pixels 240 and the reflection pixels 250, and the transmission pixels 240 and the reflection pixels. And a thin film transistor 211 and a pixel electrode 216 formed at 250, respectively.

The thin film transistor 211 includes a gate electrode connected to the gate line 213, a source electrode connected to the data line 214, and a drain electrode connected to the pixel electrode 216.

The pixel electrode 216 is made of a transparent conductive material through which light can pass. For example, the pixel electrode 216 is made of indium zinc oxide (IZO) or indium tin oxide (ITO).

The second substrate 220 is a color filter substrate in which an RGB color filter for realizing color is formed in a thin film form. The color filter layer and the common electrode are sequentially formed on the bottom surface of the second substrate 220. In one example, the common electrode is made of a transparent conductive material.

The display panel 200 may further include a reflective film 260 for reflecting light supplied from the light unit. The reflective film 260 is formed on the pixel electrode 216 corresponding to the reflective pixel 250. The reflective film 260 is preferably made of a conductive material having a high light reflectance to reflect light. For example, the reflective film 260 may be made of aluminum-neodymium (AlNd) material.

The display panel 200 having the above configuration displays the first image toward the first substrate 210 using the light L1 of the light unit transmitted through the transmission pixel 240. In addition, the display panel 200 displays the second image in the direction of the second substrate 220 by using the light L2 of the light unit reflected by the reflective film 260 formed on the reflective pixel 250.

In this case, the first polarizer 500 and the second polarizer 700 are disposed above the display panel 200. The first and second polarizers 500 and 700 absorb light oscillating in the polarization axis directions formed in the first and second polarizing plates 500 and 700, and transmit the light oscillating in the direction perpendicular to the polarization axis direction. Through the above-described method, the first and second polarizers 500 and 700 absorb light incident from the outside through the upper and lower portions of the bidirectional liquid crystal display 800, thereby providing visibility of the first and second images. Can be improved.

Second Embodiment of Bidirectional Liquid Crystal Display

Referring to FIG. 7, the bidirectional liquid crystal display 800 according to the present exemplary embodiment has a backlight structure in which a light unit is disposed under the display panel. The display panel 200 displays an image in both directions using light supplied from the light unit. Hereinafter, the same reference numerals are used for components having the same functions and functions as the components of the bidirectional liquid crystal display according to the exemplary embodiment of the present invention illustrated in FIG. Omit.

The display panel 200 includes a first substrate 210, a second substrate 220 coupled to face the first substrate 210, and a liquid crystal layer disposed between the first substrate 210 and the second substrate 220. 230. In the present embodiment, the first substrate 210 is disposed to be adjacent to the light unit.

The display panel 200 further includes a reflective film 260 for reflecting light supplied from the light unit. As the arrangement of the liquid crystal molecules of the liquid crystal layer 230 interposed between the first substrate 210 and the second substrate 220 is changed, the display panel 200 may change an optical transmittance to display an image having a desired gray scale. have. Accordingly, the reflective film 260 may be formed on the bottom surface of the second substrate 220 in correspondence with the reflective pixel 350.

The display panel 200 having the above configuration displays the first image in the direction of the second substrate 220 using the light L1 of the light unit 600 transmitted through the transmission pixel 240. In addition, the display panel 200 displays the second image toward the first substrate 210 by using the light L2 of the light unit 600 reflected by the reflective film 260 formed on the reflective pixel 250. do.

According to the bidirectional liquid crystal display device described above, the thickness of the bidirectional liquid crystal display device can be reduced by displaying an image in both directions using one display panel and one light unit.

In addition, by using one light unit, it is possible to reduce the number of use of the light emitting diode used as a light source, thereby reducing the manufacturing cost.

On the other hand, by implementing the touch panel function using the light guide plate and the polarizing plate, it is possible to form a functional bi-directional liquid crystal display device of low cost and light and simple. In this case, as the polarizing plate is disposed on the uppermost portion of the bidirectional liquid crystal display, external light may be prevented from being reflected from the surface, thereby further improving visibility.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (7)

A display panel including an reflective pixel and a transmissive pixel to display an image in both directions; A light guide plate formed on one side of the display panel to guide light to the display panel and to emit light, wherein the first transparent electrode is formed; A first polarizing plate spaced apart from the first transparent electrode at a predetermined interval and formed with a second transparent electrode electrically contacting the first transparent electrode to generate position information; And And a second polarizing plate formed on the other side of the display panel opposite to the one side. The bidirectional liquid crystal display of claim 1, wherein a hard coating layer is formed on the first polarizing plate to protect the first polarizing plate. The bidirectional liquid crystal display device according to claim 1, wherein an antireflection film is formed on the first polarizing plate to prevent light reflection generated from the surface of the first polarizing plate. The bidirectional liquid crystal display of claim 1, further comprising a dot spacer disposed between the first and second transparent electrodes to maintain a predetermined gap between the first and second transparent electrodes. . The bidirectional liquid crystal display of claim 1, further comprising at least one point light source disposed on a side of the light guide plate to generate light. The display panel of claim 5, wherein the display panel displays a first image using light of the point light source transmitted through the transmission pixel, and a second image using light of the point light source reflected through the reflection pixel. Bi-directional liquid crystal display, characterized in that for displaying. The display panel of claim 6, wherein the display panel A first substrate disposed adjacent to the light guide plate; A second substrate disposed to face the first substrate and having a reflective film corresponding to the reflective pixel; And And a liquid crystal layer interposed between the first substrate and the second substrate.

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