KR20120074424A - Fluorescence liquid crystal display device - Google Patents

Abstract

PURPOSE: A fluorescent liquid crystal display device is provided to make light of a backlight unit directly incident on a fluorescent panel not through a liquid crystal panel. CONSTITUTION: A fluorescent liquid crystal display device includes a backlight unit(100), a fluorescent panel(200), and a liquid crystal panel(300). The backlight unit includes a plurality of light emitting diodes(100a). The fluorescence panel is formed on the backlight unit. The liquid crystal panel is formed on the fluorescent panel. Light of the light source of the backlight unit is directly incident on the fluorescent panel not through the liquid crystal panel.

Description

Fluorescent Liquid Crystal Display {FLUORESCENCE LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a liquid crystal display device, and more particularly, to a fluorescent liquid crystal display device capable of improving light efficiency.

As the information society develops, the demand for display devices is increasing in various forms. In response to this, various flat panel display devices such as liquid crystal display device (LCD), plasma display panel (PDP), electro luminescent display (ELD), and vacuum fluorescent display (VFD) have been studied. It is used as a display device.

Among them, the liquid crystal display is the most widely used, replacing the CRT (Cathode Ray Tube) for mobile image display due to the excellent image quality, light weight, thinness, and low power consumption. In addition to the mobile use, various developments have been made for televisions and monitors for receiving and displaying broadcast signals.

The liquid crystal display device has a structure in which liquid crystal is filled between the upper and lower substrates. Since the liquid crystal molecules are thin and long in structure and have directivity in the arrangement, when the electric field is applied to the liquid crystal layer, the alignment direction of the liquid crystal molecules can be controlled.

When an electric field is applied to the liquid crystal display, the liquid crystal molecules are moved by the electric field applied to the liquid crystal layer, and the light transmittance is changed to express an image or a character. Such liquid crystal display devices have been spotlighted as next generation advanced display devices due to their excellent image quality, light weight, and low power consumption.

On the other hand, the liquid crystal panel does not emit light by itself and requires a separate light source. Generally, a backlight unit is provided under the liquid crystal panel to irradiate light to the liquid crystal panel.

However, the white light incident on the liquid crystal panel from the backlight unit passes only light having a specific wavelength through the color filters of red, green, and blue colors of the liquid crystal panel. That is, since the liquid crystal display uses only one third of the white light, the light loss is large.

Accordingly, in order to overcome the above disadvantages, a fluorescent liquid crystal display device having a structure of exciting a phosphor with UV (Ultra Violet) has been developed. Fluorescent liquid crystal display is a device that displays an image using visible light generated by irradiating the phosphor with low wavelength band such as UV (Ultra Violet) light or blue light. great.

A general fluorescent liquid crystal display device includes a liquid crystal panel, a fluorescent panel formed on the liquid crystal panel, and a backlight unit provided under the liquid crystal panel. However, the general fluorescent liquid crystal display device has low light efficiency because light emitted from the light source of the backlight unit passes through the upper and lower polarizing plates formed on and below the liquid crystal panel, respectively, and then enters the fluorescent panel.

The present invention has been made to solve the above problems, to provide a fluorescent liquid crystal display device that can improve the light efficiency by forming a fluorescent layer under the liquid crystal panel, an object thereof.

A fluorescent liquid crystal display device of the present invention for achieving the above object comprises a backlight unit having a plurality of light emitting diodes; A fluorescent panel formed on the backlight unit; And a liquid crystal panel formed on the fluorescent panel.

The light emitting diode emits UV light or blue light.

The fluorescent panel includes a first substrate and a fluorescent layer formed on the first substrate.

The fluorescent panel further includes a band pass filter formed under the fluorescent layer.

Further comprising a UV cut filter formed on the liquid crystal panel.

The UV blocking filter absorbs or reflects UV from external light incident to the fluorescent panel.

The liquid crystal panel includes a second substrate and a third substrate facing each other; A liquid crystal layer formed between the second substrate and the third substrate; And a pixel electrode formed on the second substrate and a common electrode formed on the third substrate.

The liquid crystal panel further includes an upper polarizer and a lower polarizer, respectively formed on the upper and lower portions of the liquid crystal panel.

The liquid crystal panel may include a pixel electrode formed on the lower polarizer; A third substrate facing the lower polarizer; A common electrode formed on the third substrate; And a liquid crystal layer formed between the pixel electrode and the common electrode.

In the fluorescent liquid crystal display of the present invention as described above, light emitted from the backlight unit does not enter the fluorescent panel after passing through the liquid crystal panel, but is directly incident to the fluorescent panel, thereby improving light efficiency.

1 is a cross-sectional view of a fluorescent liquid crystal display device according to a first embodiment of the present invention.
2 is a table comparing light efficiency of a general fluorescent liquid crystal display and a fluorescent liquid crystal display of the present invention.
3A and 3B are data obtained by measuring luminance of a general liquid crystal display and a fluorescent liquid crystal display of the present invention.
4 is a cross-sectional view of a fluorescent liquid crystal display device according to a second embodiment of the present invention.

Hereinafter, the fluorescent liquid crystal display of the present invention will be described in detail with reference to the accompanying drawings.

First Embodiment

1 is a cross-sectional view of a fluorescent liquid crystal display device according to a first exemplary embodiment of the present invention, and FIG. 2 is a table comparing light efficiency of a general fluorescent liquid crystal display device and a fluorescent liquid crystal display device of the present invention. 3A and 3B are data obtained by measuring luminance of a general liquid crystal display and a fluorescent liquid crystal display of the present invention.

As shown in FIG. 1, the fluorescent liquid crystal display according to the first exemplary embodiment of the present invention includes a backlight unit 100, a fluorescent panel 200 formed on the backlight unit 100, and a fluorescent panel 200. And a liquid crystal panel 300.

That is, in the fluorescent liquid crystal display of the present invention, the fluorescent panel 200 is formed on the backlight unit 100 so that light emitted from the light source of the backlight unit 100 does not pass through the liquid crystal panel 300. ), The light efficiency can be improved.

The backlight unit 100 includes a plurality of light emitting diodes 100a, a circuit board (not shown), and a diffusion plate (not shown). The diffusion plate (not shown) has a function of injecting light emitted from the light emitting diode 100a into the fluorescent panel 200 with uniform luminance.

The light emitting diode 100a is preferably a UV LED (Ultra Violet Light Emitting Diode) for emitting UV (Ultra Violet) light or a blue LED for emitting blue light. UV light is ultraviolet rays having a wavelength band of 200 nm to 400 nm, and blue light has a wavelength band of 400 nm to 500 nm.

The fluorescent panel 200 includes a fluorescent layer composed of a red fluorescent layer 220a, a green fluorescent layer 220b, and a blue fluorescent layer 220c formed in each of a first substrate 210 and a pixel region on the first substrate 210. 220) includes. Although not shown, the pixel region is partitioned from the neighboring pixel region by the light shielding layer.

When the light emitting diode 100a is a blue LED, the red fluorescent layer 220a is formed of a fluorescent material expressing red using blue light, and the green fluorescent layer 220b is a fluorescent light expressing green using blue light. The blue fluorescent layer 220c is formed of a fluorescent material expressing blue color using blue light. When the light emitted from the backlight unit 100 enters the fluorescent panel 200, the fluorescent layer 220 is formed. It is excited and light is generated.

The fluorescent panel 200 further includes a band pass filter 230 formed under the fluorescent layer 220. The band pass filter 230 selectively transmits the wavelength of the light emitted from the backlight unit 100 and cuts off the rest. The band pass filter 230 may be formed above or below the first substrate 210 to selectively inject light into the fluorescent layer 220 to improve color purity.

The liquid crystal panel 300 includes a second substrate 310 and a third substrate 350 facing each other, and a liquid crystal layer 330 formed between the second substrate 310 and the third substrate 350. Specifically, the second substrate 310 is formed at the intersection of a plurality of gate lines (not shown), data lines (not shown), gate lines (not shown), and data lines (not shown) that cross each other to define pixel regions. And a thin film transistor including a gate electrode (not shown), an active layer (not shown), a source electrode (not shown), and a drain electrode (not shown), and a pixel electrode electrically connected to the drain electrode (not shown). 320. The common electrode 340 is formed on the third substrate 350.

The second substrate 310 may have a top gate structure in which a gate electrode (not shown) is positioned above the active layer (not shown), and a gate electrode (not shown) is positioned below the active layer (not shown). It may be a bottom gate structure. In addition, although the thin film transistor is formed on the second substrate 310 in the drawing, the thin film transistor may be formed on the third substrate 350 and the common electrode may be formed on the second substrate 310.

Upper and lower polarizers 300b and 300a are respectively formed on the upper and lower portions of the liquid crystal panel 300. In addition, the UV blocking filter 370 is formed on the upper polarizing plate 300b. The UV blocking filter 370 functions to block UV that may be incident on the fluorescent panel 200 from the outside.

In general, since the external light includes UV, the fluorescent layer 220 may emit light by external light. As described above, when the fluorescent layer 220 emits light irrelevant to the display of the screen by external light, contrast may be lowered.

Therefore, the UV blocking filter 370 is formed as a chemical blocking agent that absorbs UV or a physical blocking agent that reflects and disperses the incoming UV, thereby preventing the fluorescent layer 220 from being excited and emitting light due to external light.

Chemical blockers include para-aminobenzoic acid derivatives, cinnamate derivatives, salicylic acid derivatives, benzophenone and derivatives thereof, anthranilate and derivatives thereof. . Physical barriers include zinc oxide, titanium oxide, iron oxide, magnesium oxide and the like.

The UV blocking filter 370 as described above may prevent UV, which irritates the fluorescent layer 220, causing unnecessary light emission, to be incident on the fluorescent layer 220.

Referring to FIG. 2, in the general fluorescent liquid crystal display device, the luminance of the red fluorescent layer and the green fluorescent layer is 183 cd / m 2 and 1583 cd / m 2, respectively. Are 303 cd / m 2 and 2564 cd / m 2, respectively. That is, the light efficiency of the fluorescent liquid crystal display device of the present invention is improved by about 1.6 times or more as compared with the general fluorescent liquid crystal display device. This is because, in the fluorescent liquid crystal display of the present invention, light emitted from the backlight unit is directly incident on the fluorescent panel.

In addition, as shown in FIG. 3A, the TN mode (Twisted Nematic Mode) liquid crystal display has a small viewing angle, resulting in uneven luminance of the liquid crystal display. Therefore, in order to prevent this, the liquid crystal display device compensates the viewing angle by forming a viewing angle compensation film on the upper and lower portions of the liquid crystal panel, respectively. Therefore, in the liquid crystal display, a process of attaching the viewing angle compensation film is added, thereby increasing the manufacturing cost.

However, the fluorescent liquid crystal display has a uniform luminance even in the TN mode as shown in FIG. 3B. That is, the fluorescent liquid crystal display does not need to attach a separate viewing angle compensation film in order to improve the viewing angle, so that the manufacturing cost can be reduced compared to the liquid crystal display, and the thickness of the liquid crystal display is thinner.

Second Embodiment

4 is a cross-sectional view of a fluorescent liquid crystal display according to a second exemplary embodiment of the present invention.

According to the second exemplary embodiment of the present invention, a pixel electrode is formed on a lower polarizing plate, except that the components are identical to those of the fluorescent liquid crystal display according to the first exemplary embodiment.

As shown in FIG. 4, in the fluorescent liquid crystal display according to the second exemplary embodiment, the pixel electrode 320 of the liquid crystal panel 400 is formed on the lower polarizer 300a. That is, the liquid crystal panel 300 of FIG. 1 has the second and third substrates 310 and 350 of FIG. 1, but the liquid crystal panel 400 of the second embodiment has only the third substrate 350. . Therefore, the manufacturing cost can be reduced and the thickness of the fluorescent liquid crystal display device can be reduced.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Will be apparent to those of ordinary skill in the art.

100: backlight unit 100a: light emitting diode
200: fluorescent panel 210: first substrate
220: fluorescent layer 220a: red fluorescent layer
220b: green fluorescent layer 220c: blue fluorescent layer
230: band pass filter 300, 400: liquid crystal panel
300a: lower polarizer 300b: upper polarizer
310: second substrate 320: pixel electrode
330: liquid crystal layer 340: common electrode
350: third substrate 370: UV cut filter

Claims (9)

A backlight unit having a plurality of light emitting diodes;
A fluorescent panel formed on the backlight unit; And
And a liquid crystal panel formed on the fluorescent panel. The method of claim 1,
The light emitting diode is a fluorescent liquid crystal display device that emits UV light or blue light. The method of claim 1,
The fluorescent panel includes a first substrate and a fluorescent layer formed on the first substrate. The method of claim 3, wherein
The fluorescent panel further includes a band pass filter formed under the fluorescent layer. The method of claim 1,
And a UV cut filter formed on the liquid crystal panel. The method of claim 5, wherein
The UV blocking filter may absorb or reflect UV light from external light incident to the fluorescent panel. The method of claim 1,
The liquid crystal panel includes a second substrate and a third substrate facing each other;
A liquid crystal layer formed between the second substrate and the third substrate; And
And a pixel electrode formed on the second substrate and a common electrode formed on the third substrate. The method of claim 1,
And a top polarizer and a bottom polarizer respectively formed on the upper and lower portions of the liquid crystal panel. The method of claim 8,
The liquid crystal panel may include a pixel electrode formed on the lower polarizer;
A third substrate facing the lower polarizer;
A common electrode formed on the third substrate; And
And a liquid crystal layer formed between the pixel electrode and the common electrode.

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