KR100843476B1 - Dual liquid crystal display device using of dual front light - Google Patents

Abstract

The present invention discloses a dual liquid crystal display using dual front lights. A dual liquid crystal display using a dual front light according to the present invention includes a liquid crystal panel of a transverse electric field system in which a liquid crystal is injected between an upper plate and a lower plate and drives the liquid crystal by a horizontal electric field; First and second polarizers attached to both surfaces of the liquid crystal panel, respectively; A first front light attached to a front portion of the liquid crystal panel; A second front light attached to a rear portion of the liquid crystal panel; It is characterized in that it comprises a microreflective film provided on at least one of between the first polarizing plate and the first front light or between the second polarizing plate and the second front light.

The dual liquid crystal display device using the dual front light according to the present invention is a liquid crystal panel of the dual liquid crystal display device using a horizontal electric field (IPS: In Plane Switching Mode) or a negative liquid crystal and a vertical alignment film to drive the liquid crystal by a horizontal electric field. By using a vertical alignment mode (VA) in which the long axis of the liquid crystal molecules are vertically aligned with the plane of the alignment layer, a wide viewing angle can be secured.

Front light, liquid crystal panel, micro reflective film, IPS, VA

Description

Dual liquid crystal display using dual front lights {DUAL LIQUID CRYSTAL DISPLAY DEVICE USING OF DUAL FRONT LIGHT}

1 is a view schematically illustrating a structure of a front light unit of a reflective liquid crystal display device according to the related art.

2 is a cross-sectional view of FIG.

FIG. 3 schematically illustrates the structure of a first embodiment of a dual liquid crystal display using dual front lights according to the present invention; FIG.

4 shows schematically what is displayed when the first front light according to the invention is in an on state;

FIG. 5 shows schematically what is displayed when the second front light according to the invention is in an on state;

FIG. 6 is a diagram illustrating a wide viewing angle dependence using a transverse electric field method according to a first embodiment of a dual liquid crystal display using dual front lights according to the present invention. FIG.

FIG. 7 schematically illustrates the structure of a second embodiment of a dual liquid crystal display using dual front lights according to the present invention; FIG.

FIG. 8 is a diagram illustrating a wide viewing angle dependence of a vertical alignment method according to a second embodiment of a dual liquid crystal display using dual front lights according to the present invention; FIG.                 

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

301, 701 --- Liquid crystal panel 302, 702 --- First front light

303, 703 --- 2nd front light 304, 704 --- 1st polarizer

305, 705 --- Second polarizer 306, 706 --- Microreflective film

307, 707 --- 2nd microreflective film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual liquid crystal display device using dual front lights, and in particular, to a liquid crystal panel of a dual liquid crystal display device, in which a horizontal electric field (IPS: In Plane Switching Mode) or a negative type liquid crystal is vertical The present invention relates to a dual liquid crystal display using a dual front light that can secure a wider viewing angle by applying a vertical alignment mode (VA) in which the long axis of the liquid crystal molecules is vertically aligned with the plane of the alignment layer using the alignment layer. .

In general, the liquid crystal display is a flat panel display having advantages of small size, thinness, and low power consumption, and is used as a portable computer such as a notebook PC, office automation equipment, and audio / video equipment.

Such a liquid crystal display device displays an image or an image by controlling an electric field applied to a liquid crystal material having dielectric anisotropy to transmit or block light. Liquid crystal displays differ from the display elements that emit light by themselves, such as electro-luminescence (EL), cathode ray tube (CRT), and light emitting diode (LED). It does not occur and uses external light.

In general, liquid crystal displays are roughly classified into a transmissive type and a reflective type according to a method of using light. The transmissive liquid crystal display device includes a liquid crystal display panel in which a liquid crystal material is injected between two glass substrates, and a backlight for supplying light to the liquid crystal display panel.

However, the transmissive liquid crystal display device has difficulty in thinning and weighting due to the volume and weight of the backlight, and has been pointed out as an excessive power consumption of the backlight. In response to this trend, research and development of a reflective liquid crystal display device that does not use a backlight have been recently conducted.

Since the reflective liquid crystal display device does not have its own light source, it displays an image depending on natural light (or ambient light). Therefore, since a separate backlight is not required, power consumption is low, so it is widely used as a portable display device such as an electronic notebook or personal information terminal.

However, the reflection type liquid crystal display device has a problem in that when the natural light does not have a sufficient amount of light (for example, when the surroundings are dark), the luminance level of the display image is lowered and the displayed information cannot be read. In order to solve this problem, a front light unit (FLU), which is separately installed in the reflective LCD and supplies light beams to the reflective liquid crystal display when the ambient light is dark, is used.

1 is a view schematically illustrating a structure of a front light unit of a reflective liquid crystal display according to the related art, and FIG. 2 is a cross-sectional view of FIG. 1. 1 and 2, the reflective liquid crystal display device includes a reflective liquid crystal panel 101 and a front light positioned above the reflective liquid crystal panel 101 to supply light beams to the reflective liquid crystal panel 101. Unit 102 is provided. A reflective reflective electrode is formed on the reflective liquid crystal panel 101 to reflect natural light (or auxiliary light) incident on the display surface of the liquid crystal panel 101.

The front light unit 102 includes a light source 201 for generating a light beam, a light guide plate 202 for uniformly emitting the light beam toward the display surface of the liquid crystal panel, and a light source 201 in the light source 201. The reflector 203 reflects the generated light beam toward the light guide plate 202, and the reflector 204 prevents the light beam from leaking from the light guide plate 202.

In this case, since the upper surface of the light guide plate 202 has a prism pattern, the traveling path of light incident obliquely to the light guide plate 202 is changed perpendicular to the display surface.

Therefore, the light incident on the light guide plate 202 is incident in the vertical direction of the reflective liquid crystal panel 101 positioned below the light guide plate 202. Light vertically incident on the reflective liquid crystal panel 101 is reflected by the reflective liquid crystal panel 101 and proceeds upwards of the light guide plate 202.

In the present invention, the long axis of the liquid crystal molecules is perpendicular to the alignment layer plane by using an in-plane switching mode (IPS) or a negative type liquid crystal and a vertical alignment layer for driving the liquid crystal by a horizontal electric field on the liquid crystal panel of the dual liquid crystal display device. It is an object of the present invention to provide a dual liquid crystal display using a dual front light that can secure a wider viewing angle by applying a vertical alignment method (VA).

In order to achieve the above object, the dual liquid crystal display using the dual front light according to the present invention,

A liquid crystal panel in which a liquid crystal is injected between the upper plate and the lower plate and drives the liquid crystal by a horizontal electric field;

First and second polarizers attached to both surfaces of the liquid crystal panel, respectively;

A first front light attached to a front portion of the liquid crystal panel;

A second front light attached to a rear portion of the liquid crystal panel;

It is characterized in that it comprises a microreflective film provided on at least one of between the first polarizing plate and the first front light or between the second polarizing plate and the second front light.

In particular, a thin film transistor (TFT) serving as a switching element is formed at the intersection of the gate bus line and the data bus line, respectively, on the lower plate of the liquid crystal panel, and a black matrix (BM) and a color filter layer are formed on the upper plate. There is a characteristic in that it is formed.

In particular, a plurality of pixel electrodes connected to the thin film transistor are formed on the lower plate of the liquid crystal panel, and a plurality of common electrodes are formed to alternate with the pixel electrodes.

In addition, a dual liquid crystal display using a dual front light according to the present invention to achieve the above object,

A vertical alignment liquid crystal panel in which a negative liquid crystal is injected between the upper and lower plates, and the long axis of the liquid crystal molecules is vertically aligned with the alignment layer plane by using the vertical alignment layer;

First and second polarizers attached to both surfaces of the liquid crystal panel, respectively;

A first front light attached to a front portion of the liquid crystal panel;

A second front light attached to a rear portion of the liquid crystal panel;

It is characterized in that it comprises a microreflective film provided on at least one of between the first polarizing plate and the first front light or between the second polarizing plate and the second front light.

In particular, a thin film transistor (TFT), which functions as a switching element, is formed at the intersection of the gate bus line and the data bus line, respectively, on the lower plate of the liquid crystal panel, and a black matrix (BM), a color filter layer, The feature is that a common electrode is formed.

In particular, the first front light is displayed in the rear part of the liquid crystal panel when the ON state, and the second front light is displayed in the front part of the liquid crystal panel when the ON state. have.

Here, in particular, the microreflective film is provided between the first polarizing plate and the first front light so that when the transmitted light by the first front light is displayed on the rear portion of the liquid crystal panel at the same time it is characterized in that it reflects the external light source have.

Here, in particular, the micro-reflective film is provided between the second polarizing plate and the second front light to reflect the external light source at the same time when the transmitted light by the second front light is displayed on the front portion of the liquid crystal panel There is this.

Here, in particular, the microreflective film is provided between the first polarizing plate and the first front light so that the transmitted light by the first front light is displayed on the rear side of the liquid crystal panel, and the microreflective film is formed of the second polarizing plate and the first front light. It is characterized in that it is provided between the two front lights to reflect the external light source at the same time when the transmitted light by the second front light is displayed on the front portion of the liquid crystal panel.

In particular, the first and second polarizing plates are characterized in that they are attached to both sides of the liquid crystal panel at 90 ° to each other.

In particular, the thin film transistor (TFT) formed on the lower plate of the liquid crystal panel is characterized by being formed of an amorphous thin film transistor (TFT).

In particular, the thin film transistor (TFT) formed on the lower plate of the liquid crystal panel is characterized by being formed of a polysilicon thin film transistor (TFT).

According to the present invention, the long axis of the liquid crystal molecules is aligned in the liquid crystal panel of the dual liquid crystal display device using an in-plane switching mode (IPS) or a negative type liquid crystal and a vertical alignment layer in which a liquid crystal is driven by a horizontal electric field. The wide viewing angle can be secured by applying a vertical alignment mode (VA) to be arranged perpendicular to the plane.

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

3 is a diagram schematically illustrating a structure of a first exemplary embodiment of a dual liquid crystal display using dual front lights according to the present invention. As shown in the drawing, a dual liquid crystal display using a dual front light includes a liquid crystal panel 301 of a transverse electric field system in which liquid crystal is injected between an upper plate and a lower plate and drives the liquid crystal by a horizontal electric field; First and second polarizers 304 and 305 attached to both surfaces of the liquid crystal panel 301, respectively; A first front light (302) attached to the front portion of the liquid crystal panel (301); A second front light 303 attached to a rear portion of the liquid crystal panel 301; A first micro reflective film 306 attached between the first polarizing plate 304 and the first front light 302; And a second microreflective film 307 attached between the second polarizer 305 and the second front light 303.

The liquid crystal panel 301 is a transmissive type, and a first substrate (thin film transistor substrate) and a second substrate (color filter substrate) are provided to face each other at a predetermined interval.

In more detail with respect to the liquid crystal panel 301, the first substrate (thin film transistor substrate) has a gate bus line and a data bus line formed on an inner surface of one transparent substrate in a matrix.

Thin film transistors (TFTs), which function as switching elements, are formed at intersections of the gate bus lines and the data bus lines, respectively, and a plurality of common pixels are alternately connected to the pixel electrodes and the pixel electrodes connected to the thin film transistors. An electrode is formed.

Here, the thin film transistor (Thin Film Transistor) formed on the lower plate of the liquid crystal panel 301, the hydrogen of the lattice periodicity according to the crystal state of the semiconductor layer which is an active layer among the constituent elements. An amorphous thin film transistor (amorphous thin film transistor) using amorphous silicon (amorphous silicon), or a polysilicon thin film transistor (poly silicon thin film transistor) using polysilicon (crystalline poly silicon) is applied.

In addition, the other second substrate (color filter substrate) facing the transparent substrate on which the plurality of pixel electrodes is formed has a black matrix (BM) and a color filter layer formed on the inner surface of the transparent substrate.

Meanwhile, in the first embodiment of the present invention, the liquid crystal mode of the in-plane switching mode (IPS) having a good viewing angle characteristic is applied.

More specifically, in the transverse electric field type liquid crystal display, two electrodes are formed on the same substrate in order to drive the liquid crystal molecules in a horizontal state with respect to the substrate, and a voltage is applied between the two electrodes. Generates an electric field in the horizontal direction with respect to. In other words, the long axis of the liquid crystal molecules does not stand on the substrate.

If the voltage is off, the horizontal electric field is not applied. Therefore, no phase shift occurs in the liquid crystal. If the voltage is turned on, the phase shift occurs, so that there is no phase shift of the liquid crystal at the position corresponding to the common electrode and the pixel electrode. The liquid crystal positioned in the section between the electrode and the pixel electrode is arranged in the same direction as the horizontal electric field by a horizontal electric field formed by applying a voltage between the common electrode and the pixel electrode.

That is, in the lateral liquid crystal display device, since the liquid crystal moves by the horizontal electric field, the change in the birefringence of the liquid crystal with respect to the visual direction is small, resulting in a wide viewing angle.

Therefore, when viewed from the front, the transverse electric field type liquid crystal display device may be visible in about 80 to 85 degrees in the up / down / left / right directions.

In addition, first and second polarizing plates 304 and 305 and a compensation plate (not shown) are further provided on both surfaces of the liquid crystal panel 301. Here, the first and second polarizing plates 304 and 305 are attached to both surfaces of the liquid crystal panel 301 by 90 °.

The first and second polarizers 304 and 305 only transmit light that vibrates in one direction to polarize natural light.

The compensation plate (not shown) is to solve the viewing angle problem by compensating the phase change of the light in the liquid crystal molecules in the opposite direction, the compensation plate (not shown) is uniaxial (uniaxial) or biaxial (biaxial) Used.

Meanwhile, in the first front light 302 provided on the front surface of the liquid crystal panel 301, when light is emitted from the light source, the light is incident on the light guide plate to change the linear light source into a uniform surface light source.

In this case, since the upper surface of the light guide plate has a prism pattern, the traveling path of light incident obliquely to the light guide plate is changed perpendicular to the display surface.

The light changed from the light guide plate to the surface light source is scattered by the diffusion plate and transmitted through the liquid crystal cell.

The first and second microreflective films 306 and 307 simultaneously reflect external light when the transmitted light by the first and second front lights 302 and 302 is displayed on the front or rear of the liquid crystal panel.

4 is a diagram schematically illustrating the display when the first front light 302 according to the present invention is in an on state. As shown in the drawing, when the first front light 302 is in an on state, when a sufficient voltage is applied to the liquid crystal molecules initially oriented in the same direction as the transmission axis of any one polarizer, the long axis of the liquid crystal molecules becomes an electric field. Are arranged side by side.

The first and second polarizers are arranged such that their transmission axes are perpendicular to each other, and the rubbing direction of the alignment layer formed on the lower plate is parallel to the transmission axis of any one of the polarizer plates so as to be normally black. .

That is, when no voltage is applied to the device, liquid crystal molecules are arranged to display a black state, and when voltage is applied to the device, the liquid crystal molecules are arranged side by side in an electric field to display white.

Therefore, by selectively applying the voltage to adjust the light passing through the liquid crystal panel 301 to display a desired screen on the rear of the liquid crystal panel 301.

At this time, when displaying the transmissive liquid crystal panel in a place where the external light is bright, the brightness of the light by the first front light 302 is relatively lower than the brightness of the external light, it is difficult to see the screen displayed on the rear of the liquid crystal panel.

Therefore, when the external light is bright by applying a microreflective film between the first polarizing plate 304 and the first front light 302, the external light is reflected by the first microreflective film 306 to provide light efficiency. This is enhanced to view the screen displayed on the rear portion of the liquid crystal panel 301.

5 is a diagram schematically showing what is displayed when the second front light according to the present invention is turned on. As shown in FIG. 2, even when the second front light 303 is in an on state, when a voltage is not applied to the device in a normally black mode, liquid crystal molecules are arranged to display a black state. When voltage is applied to the device, the liquid crystal molecules are arranged side by side in the electric field to display white.

Therefore, by selectively applying the voltage to adjust the light passing through the liquid crystal panel 301 to display a desired screen on the front of the liquid crystal panel.

At this time, when the screen is displayed on the front portion of the liquid crystal panel 301 in a bright place of the external light, a good visibility is provided by the external light reflected by the second microreflective film 307. .

As mentioned above, the front or rear surface of the liquid crystal panel 301 is displayed depending on whether the first front light 302 or the second front light 303 is turned on.

FIG. 6 is a diagram illustrating a wide viewing angle dependence of a transverse electric field method according to a first embodiment of a dual liquid crystal display using dual front lights according to the present invention. As shown in the drawing, it can be seen that the wide viewing angle of the liquid crystal panel to which the lateral electric field system is applied is widened in up, down, left and right.

7 is a diagram schematically illustrating a structure of a second embodiment of a dual liquid crystal display using dual front lights according to the present invention. (Here, FIG. 7 looks the same on the outer surface as in FIG. 3, but the mode applied to the liquid crystal panel is different.) As shown in the drawing, a dual liquid crystal display using a dual front light includes a negative liquid crystal between an upper plate and a lower plate. A vertical alignment liquid crystal panel 701 which is injected and has a long axis of the liquid crystal molecules aligned perpendicular to the alignment layer plane by using the vertical alignment layer; First and second polarizing plates 704 and 705 attached to both surfaces of the liquid crystal panel 701, respectively; A first front light 702 attached to the front portion of the liquid crystal panel 701; A second front light 703 attached to a rear portion of the liquid crystal panel 701; A first micro reflective film 706 attached between the first polarizing plate 704 and the first front light 702; And a second microreflective film 707 attached between the second polarizing plate 705 and the second front light 703.

The liquid crystal panel uses various domain division techniques for forming a multi-domain by using vertical alignment mode (VA), for example, side electrodes, slits, or ribs. ) Can be used to attempt domain division in a single pixel region.

Here, the detailed description of the second embodiment of the present invention will be omitted with reference to the above-described first embodiment of FIGS. 4 and 5.

FIG. 8 is a diagram illustrating a wide viewing angle dependency of a vertical alignment method according to a second embodiment of a dual liquid crystal display using dual front lights according to the present invention. As shown in the drawing, it can be seen that the wide viewing angle of the liquid crystal panel to which the vertical alignment method is applied is widened vertically and horizontally.

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the dual liquid crystal display device using the dual front light according to the present invention is an in-plane switching mode (IPS) or negative type for driving liquid crystals by a horizontal electric field on the liquid crystal panel of the dual liquid crystal display device. By using a vertical alignment method (VA) in which the long axis of the liquid crystal molecules is vertically aligned with the plane of the alignment layer using the liquid crystal and the vertical alignment layer, a wide viewing angle may be secured.

Claims (13)

A liquid crystal panel in which a liquid crystal is injected between the upper plate and the lower plate and drives the liquid crystal by a horizontal electric field; First and second polarizers attached to both surfaces of the liquid crystal panel, respectively; A first front light attached to a front portion of the liquid crystal panel; A second front light attached to a rear portion of the liquid crystal panel; And a first and second micro-reflective films provided between the first polarizing plate and the first front light or between the second polarizing plate and the second front light, respectively. The method of claim 1, A thin film transistor (TFT) serving as a switching element is formed at the intersection of the gate bus line and the data bus line on the lower plate of the liquid crystal panel, and a black matrix (BM) and a color filter layer are formed on the upper plate. Dual liquid crystal display using dual front lights. The method of claim 1, And a plurality of pixel electrodes connected to the thin film transistors on the lower plate of the liquid crystal panel, and a plurality of common electrodes alternately formed with the pixel electrodes. The method of claim 1, If the voltage is turned off to the liquid crystal panel, no horizontal electric field is applied to the liquid crystal panel, so that no phase change of the liquid crystal occurs. If the voltage is on, the liquid crystal positioned in the section between the common electrode and the pixel electrode is in the same direction as the horizontal electric field. Dual liquid crystal display using a dual front light, characterized in that arranged. A vertical alignment liquid crystal panel in which a negative liquid crystal is injected between the upper and lower plates, and the long axis of the liquid crystal molecules is vertically aligned with the alignment layer plane by using the vertical alignment layer; First and second polarizers attached to both surfaces of the liquid crystal panel, respectively; A first front light attached to a front portion of the liquid crystal panel; A second front light attached to a rear portion of the liquid crystal panel; And a first and second micro-reflective films provided between the first polarizing plate and the first front light or between the second polarizing plate and the second front light, respectively. The method of claim 5, A thin film transistor (TFT), which functions as a switching element, is formed at the intersection of the gate bus line and the data bus line on the lower plate of the liquid crystal panel, and a black matrix (BM), a color filter layer, and a common electrode are formed on the upper plate. Dual liquid crystal display using a dual front light, characterized in that formed. The method according to claim 1 or 5, The dual front lights may be displayed on the rear part of the liquid crystal panel when the first front light is ON, and displayed on the front parts of the liquid crystal panel when the second front light is ON. Dual liquid crystal display using. The method according to claim 1 or 5, The first and second microreflective films are provided between the first polarizing plate and the first front light to reflect external light sources simultaneously when the transmitted light by the first front light is displayed on the rear surface of the liquid crystal panel. Dual liquid crystal display using dual front lights. The method according to claim 1 or 5, The first and second microreflective films are provided between the second polarizing plate and the second front light to reflect external light sources simultaneously when the transmitted light by the second front light is displayed on the front surface of the liquid crystal panel. Dual LCD using dual front lights. The method according to claim 1 or 5, The first and second microreflective films are provided between the first polarizing plate and the first front light, so that the transmitted light by the first front light is displayed on the rear side of the liquid crystal panel, and the micro reflective film is the second polarizing plate. And a second front light provided between the second front light and the external light when the transmitted light by the second front light is displayed on the front surface of the liquid crystal panel. The method according to claim 1 or 5, And the first and second polarizing plates are attached to both surfaces of the liquid crystal panel at 90 ° to each other. The method according to claim 2 or 6, The thin film transistor (TFT) formed on the lower plate of the liquid crystal panel is a dual liquid crystal display using a dual front light, characterized in that formed of an amorphous thin film transistor (TFT). The method according to claim 2 or 6, The thin film transistor (TFT) formed on the lower plate of the liquid crystal panel is a dual liquid crystal display using a dual front light, characterized in that formed of a polysilicon thin film transistor (TFT).

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