KR20040083121A - Dual liquid crystal display using of dual front light - Google Patents

Abstract

PURPOSE: A dual liquid crystal display device using dual front lights is provided to mount front lights at both sides of a transmissive LCD for realizing the dual LCD. CONSTITUTION: A dual liquid crystal display device using dual front lights includes an LC panel(301), first and second polarization plates(304,305) attached to both sides of the LC panel with an angle of 90°, a first front light(302) attached to a front surface of the LC panel, and a second front light(303) attached to a rear surface of the LC panel. The LC panel has TN-mode liquid crystal. As the front light is turned on, the LC panel becomes black for the display of the rear surface. In the other case, the LC panel becomes black. If the second front light is turned on, the LC panel becomes black for the display of the front surface. In the other case, the LC panel becomes white.

Description

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

The present invention relates to a dual liquid crystal display using dual front lights, and more particularly, to a dual liquid crystal display using dual front lights that can implement dual liquid crystal display devices by providing front lights on both sides of a transmissive liquid crystal display. .

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 display devices, unlike display elements that emit light by themselves, such as electro-luminescence (EL), cathode ray tube (CRT), and light emitting diode (LED), emit light by themselves. 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 making it thin and light due to the volume and weight of the backlight, and it is pointed out that excessive power consumption of the backlight is a disadvantage. R & D is underway.

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. The reflective liquid crystal panel (Diffusing reflective electrode) of the lower portion of FIG. 2 is formed in 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. The reflector 203 reflects the light beam toward the light guide plate 202, and the reflector 204 prevents the light beam from leaking from the light guide plate 202.

Here, since the upper surface of the light guide plate 202 is a prism pattern, the light guide plate 202 changes a traveling path of light incident obliquely to the light guide plate 202 with respect 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.

An object of the present invention is to provide a dual liquid crystal display using dual front lights that can implement a dual liquid crystal display by providing front lights on both sides of the transmissive liquid crystal display.

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.

3 is a diagram schematically illustrating a structure of a dual liquid crystal display using dual front lights according to the present invention.

4 schematically illustrates 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;

6 is a view showing an example in which a dual liquid crystal display using a dual front light according to the present invention is applied.

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

301 --- liquid crystal panel 302 --- first front light

303 --- second front light

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 formed by injecting liquid crystal between the upper plate and the lower plate;

First and second polarizing plates respectively attached to both surfaces of the liquid crystal panel;

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

Its feature is that it includes a second front light attached to the rear portion of the liquid crystal panel.

In particular, the liquid crystal of the liquid crystal panel is characterized in that the TN mode.

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, a TFT (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 the BM (Black Matrix: BM), color filter layer, and common electrode on the upper plate. This feature is characterized in that it is formed.

Here, in particular, when the first front light is in an ON state, the liquid crystal panel is implemented in black and is displayed on the rear part.

Here, in particular, when the first front light is in an OFF state, it is characterized in that it is embodied as white of the liquid crystal panel and displayed on the rear part.

Here, in particular, when the second front light is in an ON state, the liquid crystal panel is implemented in black and is displayed on the front part.

Here, in particular, when the second front light is in an OFF state, it is characterized in that it is embodied as white of the liquid crystal panel and displayed on the front part.

According to the present invention as described above, dual liquid crystal display devices may be realized by providing front lights on both sides of the transmissive liquid crystal display device.

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

3 is a view schematically illustrating a structure of a dual liquid crystal display using dual front lights according to the present invention. As shown therein, a liquid crystal panel 301 formed by injecting liquid crystal between the upper and lower plates; First and second polarizers 305 and 305 respectively attached to both sides of the liquid crystal panel; A first front light (302) attached to the front portion of the liquid crystal panel (301); And a second front light 303 attached to the rear portion of the liquid crystal panel 301.

The liquid crystal panel 301 is a transmissive type and is provided with a first substrate (thin film transistor substrate) and a second substrate (color filter substrate) facing 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, and square pixel electrodes contacting the drain electrodes of the TFTs are surrounded by the gate bus lines and the data bus lines. It is formed in the form of each.

The other second substrate (color filter substrate) facing the transparent substrate on which the plurality of pixel electrodes is formed has a BM (Black Matrix: BM), a color filter layer, and a common electrode formed on an inner surface of the transparent substrate.

When one gate bus line and one data bus line of the liquid crystal panel configured as described above are selected and a voltage is applied, only a TFT (Thin Film Transistor (TFT)) to which the voltage is applied is turned on, and the on TFT is turned on. Charges are accumulated in the pixel electrode connected to the drain electrode of to change the angle of the liquid crystal molecules between the common electrode and the common electrode.

Therefore, an electric field applied to liquid crystal molecules having dielectric anisotropy is transmitted to block or transmit light to display an image or an image. Herein, the liquid crystal is TN (Twist Nematic) mode.

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 are attached to both surfaces of the liquid crystal panel at 90 ° to each other.

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, uniaxial (uniaxial) or biaxial (biaxial) is used as the compensation plate.

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

In the light guide plate, 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.

On the other hand, Figure 4 is a diagram schematically showing the display when the first front light 302 according to the present invention in the on state. As shown in the drawing, when the first front light 302 is on and the liquid crystal panel 301 is in a normally white mode, the light is not applied to the liquid crystal panel 301. The path of the second polarizing plate 305 provided with light passing through the first polarizing plate 304 provided on one surface of the liquid crystal panel 301 is twisted along the liquid crystal molecules array 90 degrees to the other surface of the liquid crystal panel 305 Will pass).

That is, light passes through the state where no voltage is applied as described above.

However, in the state where the voltage is applied to the liquid crystal panel 301, the liquid crystal molecules rise along the direction of the electric field and transmit the light passing through the first polarizing plate 304 to the crossed second polarizing plate 305 as it is. Is blocked by the polarizer. In other words, light is blocked when a voltage is applied.

By selectively applying the voltage, light passing through the liquid crystal panel 301 may be adjusted to display a desired screen on the rear surface 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, when the second front light 303 is on and the liquid crystal panel 301 is in a normally white mode, the light is not applied to the liquid crystal panel 301. The path of the light passes through the first polarizing plate 304 provided with the light passing through the second polarizing plate 305 provided on one surface of the liquid crystal panel twisted along the arrangement of the liquid crystal molecules. Done.

That is, light passes through the state where no voltage is applied as described above.

However, in the state where the voltage is applied to the liquid crystal panel 301, the liquid crystal molecules rise along the direction of the electric field and transmit the light passing through the second polarizing plate 305 to the crossed first polarizing plate 304 as it is. Blocked by the polarizer. In other words, light is blocked when a voltage is applied.

By selectively applying the voltage, the light passing through the liquid crystal panel 301 may be adjusted to display a desired screen on the front of the liquid crystal panel.

Therefore, the front or rear display of the liquid crystal panel 301 is displayed depending on whether the first front light 302 or the second front light 303 is lit.

6 is a diagram illustrating an example in which a dual liquid crystal display using dual front lights according to the present invention is applied. As shown in the figure, when applied to a dual mobile phone is possible to implement a lightweight thin dual mobile phone because it is displayed on the front and rear of the liquid crystal panel.

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 using the dual front light according to the present invention may implement the dual liquid crystal display by providing the front lights on both sides of the transmissive liquid crystal display.

In addition, since only one liquid crystal panel is applied, a lightweight thin display can be realized.

Claims (8)

A liquid crystal panel formed by injecting liquid crystal between the upper plate and the lower plate; First and second polarizing plates respectively attached to both surfaces of the liquid crystal panel; A first front light attached to a front portion of the liquid crystal panel; And a second front light attached to a rear portion of the liquid crystal panel. The method of claim 1, The liquid crystal of the liquid crystal panel is a dual liquid crystal display using a dual front light, characterized in that the TN mode. The method of claim 1, And the first and second polarizing plates are attached to both surfaces of the liquid crystal panel at 90 ° to each other. The method of claim 1, In the lower panel of the liquid crystal panel, TFTs (Thin Film Transistors) (TFTs), which function as switching elements, are formed at the intersections of the gate bus lines and the data bus lines, respectively. Dual LCD using dual front lights, characterized in that. The method of claim 1, And the liquid crystal panel is implemented in black when the first front light is in an ON state, and the liquid crystal panel is displayed on a rear surface thereof. The method of claim 1, The dual liquid crystal display using the dual front light, characterized in that the first front light is turned off (OFF) is implemented in white of the liquid crystal panel is displayed on the rear portion. The method of claim 1, If the second front light is in the ON state, the liquid crystal panel is implemented in black and is displayed on the front part of the dual liquid crystal display using the dual front light. The method of claim 1, The dual liquid crystal display using the dual front lights, if the second front light is off (OFF) state is implemented in white of the liquid crystal panel is displayed on the front.