KR20080079947A - Liquid crystal display device - Google Patents

Abstract

An LCD is provided to reduce lighting delay of a fluorescent lamp by forming a phosphorescence unit in a lower or upper side of the fluorescent lamp, thereby improving quality of an image. An LCD(Liquid Crystal Display) comprises an LC panel(10), a backlight unit(20), a main frame(27), a bottom cover(29) and a top case(25). One or more fluorescent lamps(21) are installed in a lower side of the LC panel, and supply light to the LC panel. A phosphorescence unit(30) supplies light to the fluorescent lamps. In a lower part of the fluorescent lamp, a reflection plate(28) is further installed. The reflection plate reflects light emitted from the fluorescent lamp towards the LC panel.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

1 is an exploded perspective view showing a liquid crystal display device according to a first embodiment of the present invention.

2 is a cross-sectional view showing a liquid crystal display device according to a first embodiment of the present invention.

3 is a conceptual diagram showing a phosphorescence phenomenon.

4 is an exploded perspective view showing a liquid crystal display according to a second embodiment of the present invention.

5 is a cross-sectional view illustrating a liquid crystal display device according to a second embodiment of the present invention.

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

10: liquid crystal panel 20: backlight unit

21 fluorescent lamp 23 optical sheet

25: top case 27: mainframe

28: reflector 29: lower cover

30: phosphor part

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device that can reduce the lighting delay time of the liquid crystal display device.

Recently, with the development of various electronic devices such as mobile phones, PDAs, computers, and large TVs, the demand for flat panel display devices that can be applied thereto is gradually increasing.

Such flat panel displays are being actively researched, such as LCD (Liquid Crystal Display), PDP (Plasma Display Panel), FED (Field Emission Display), VFD (Vacuum Fluorescent Display), but mass production technology, ease of driving means, Liquid crystal displays (LCDs) are in the spotlight for reasons of implementation.

A liquid crystal display device is a display device using optical anisotropy of a liquid crystal, and implements an image by adjusting the light transmittance of the liquid crystal using an electric field.

The liquid crystal display device includes a liquid crystal panel for displaying an image. Since the liquid crystal panel is a non-light emitting device, a backlight unit, which is a separate device for supplying light to the liquid crystal panel, is required.

The backlight unit mainly includes a cold cathode fluorescent lamp (CCFL) and an external electrofluorescent lamp (EEFL).

The fluorescent lamp is provided in the form of a cylindrical transparent tube, the fluorescent material is coated on the inner wall, the electrode is formed on both ends of the tube. Generally, a mixed gas of several tens of torr and a certain amount of mercury are enclosed in the tube.

In such a fluorescent lamp, when a high voltage is applied to the electrode, electrons present in the tube are attracted to the electrode and moved at a high speed. Eventually, the fluorescent lamp collides with the electrode to emit secondary electrons to initiate discharge.

However, if the fluorescent lamp is stored in the dark for a long time, the electrons in the tube are completely lost. Therefore, even when a voltage is applied to the electrode, the electrons in the tube collide with the electrode and the secondary electrons are not easily released, and thus the current does not flow in the tube, resulting in a delay in lighting. It grows with time left in the dark.

The lighting delay causes a problem in the image display of the liquid crystal display when the liquid crystal display is left for a long time in a dark state. That is, since the light is not emitted from the fluorescent lamp to supply light to the liquid crystal panel, the image cannot be displayed.

Accordingly, an object of the present invention is to provide a high quality liquid crystal display device which reduces the lighting delay of a fluorescent lamp used in a liquid crystal display device.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a liquid crystal panel, at least one fluorescent lamp provided on a rear surface of the liquid crystal panel and supplying light to the liquid crystal panel, and supplying light to the fluorescent lamp. Characterized in that it comprises a phosphor.

Liquid crystal display device according to the present invention for achieving the above object is a liquid crystal panel; A light guide plate provided on a rear surface of the liquid crystal panel; A fluorescent lamp provided on at least one side of the light guide plate; And a phosphor that supplies light to the fluorescent lamp.

Liquid crystal display device according to the present invention for achieving the above object is a liquid crystal panel; At least one fluorescent lamp provided on a rear surface of the liquid crystal panel to supply light to the liquid crystal panel; A reflection plate provided below the liquid crystal panel and reflecting light emitted from the fluorescent lamp toward the liquid crystal panel; And a phosphor part formed on the reflector to supply light to the fluorescent lamp.

In the liquid crystal display device using the fluorescent lamp, the light is supplied to the fluorescent lamp using a phosphorescence phenomenon to reduce the lighting delay of the backlight unit.

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

The liquid crystal display according to the present invention is divided into a direct type having a plurality of light sources at the bottom of the liquid crystal panel and an edge type having a light source at one lower side of the liquid crystal panel according to the type of backlight unit for supplying light to the liquid crystal panel. Can be.

In the present invention, the direct type liquid crystal display device will first be described in the first embodiment, and the edge type liquid crystal display device will be described later in the second embodiment.

1 is an exploded perspective view showing a liquid crystal display device according to a first embodiment of the present invention, Figure 2 is a cross-sectional view of the liquid crystal display device according to a first embodiment of the present invention.

1 and 2, a liquid crystal display device according to the present invention includes a liquid crystal panel 10 for displaying an image and a backlight unit 20 for supplying light from the rear surface of the liquid crystal panel 10. And, the main frame (main frame, 27) for supporting the edge of the liquid crystal panel 10, the lower cover (bottom cover, 29) that is located on the back of the backlight unit 20 to receive the backlight unit 20 And a top case 25 coupled to the main frame 27 and fixing the edge of the liquid crystal panel 10 from the top.

Although not shown in the drawing, the liquid crystal panel 10 includes an opposing thin film transistor substrate made of a transparent material such as glass, a color filter substrate, and a liquid crystal layer formed therebetween.

In this case, a gate wiring and a data wiring are formed in a matrix form on the thin film transistor substrate to define pixels, and a thin film transistor (TFT) is formed in each pixel. On the color filter substrate, red, green, and blue color filters and a common electrode are formed around the black matrix.

In addition, the liquid crystal panel 10 is generally provided in a rectangular plate shape having long sides and short sides, and includes a display area where an image is displayed and a non-display area where an image is not displayed. The non-display area is generally formed at the edge of the display area.

A top case 25 is provided on the liquid crystal panel 10 to expose the display area of the liquid crystal panel 10 and to fix the edge of the liquid crystal panel 10.

One side of the liquid crystal panel 10 includes a drive IC 11 electrically connected to the gate wiring formed on the substrate, and a printed circuit board 12 for applying an electrical signal to the wiring and the thin film transistor. .

The signal from the printed circuit board 12 is transferred to the thin film transistors through the wirings of the drive ICs 11, respectively, and the thin film transistors apply a voltage to the pixels according to the signals to drive the liquid crystal layer.

The front and rear surfaces of the liquid crystal panel 10 are provided with a polarizing plate 13 so that light transmitted through the liquid crystal panel 10 is polarized in one direction. The polarizing plates provided on the front surface of the liquid crystal panel 10 and the polarizing plates provided on the rear surface of the liquid crystal panel 10 are disposed so that the polarization axes cross vertically.

On the other hand, the lower portion of the liquid crystal panel 10 is provided with a backlight unit 20 for supplying light to the liquid crystal panel 10, the backlight unit 20 is a fluorescent lamp 21 for generating light and a fluorescent lamp It comprises the optical sheet 23 for guiding the light generated from the (21) toward the liquid crystal panel 10 to increase the efficiency of the light.

The optical sheet 23 is composed of a diffusion sheet 23a, a prism sheet 23b, a protective sheet 23c, and the like, and serves to increase the efficiency of light emitted toward the liquid crystal panel 10.

Here, the diffusion sheet 23a serves to diffuse the light from the fluorescent lamp 21 and supply it to the liquid crystal panel 10. In addition, the prism sheet 23b serves to condense the light diffused from the diffusion sheet 23a in a direction perpendicular to the plane of the upper liquid crystal panel 10, and two sheets are generally used. A protective sheet 23c is provided at the top of the optical sheet to protect the prism sheet 23b that is weak to scratches.

The rear surface of the optical sheet 23 is provided with a plurality of fluorescent lamps 21. The fluorescent lamp 21 may be provided in the form of a cylinder having a central axis, and a fluorescent lamp such as a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL) may be used.

Support sides 24 for fixing the fluorescent lamps are disposed on both sides of the fluorescent lamp 21. One side of the support side 24 is provided with an insertion hole for fixing the fluorescent lamp, both ends of the fluorescent lamp 21 is inserted and fixed.

A lower cover 29 is provided below the liquid crystal panel 10 and the fluorescent lamp 21 to surround and accommodate the fluorescent lamp 21. The lower cover 29 includes a bottom surface 29a disposed in parallel with the liquid crystal panel 10 and a side portion 29b extending upwardly from the bottom surface 29a and facing each other in the longitudinal direction of the fluorescent lamp 21. The pair of side parts are provided with a support side 24 to fix the fluorescent lamp 21.

The bottom surface 29a of the lower cover 29 is provided with a reflector 28 reflecting light emitted from the fluorescent lamp 21 toward the liquid crystal panel 10. The reflecting plate 28 is provided to extend to a pair of side portions 29b facing each other in a direction in which the support side 24 is not provided. The reflecting plate 28 reflects the light emitted in the rear direction of the liquid crystal panel 10 to increase the efficiency of the light.

At the edges of the liquid crystal panel 10 and the backlight unit 20, a main frame 27 fixing and supporting the liquid crystal panel 10 and the backlight unit 20 is provided.

The main frame 27 is formed of a rectangular mold frame having an upper surface and a lower surface of which the inside is empty, and has a stepped surface in the inner direction to form edges of the liquid crystal panel 10 and the optical sheet 23, and the like. I support it.

Phosphor phosphor 30 is provided on the reflecting plate 28 to provide light to the fluorescent lamp. The phosphor part 30 will be described later.

However, when the fluorescent lamp 21 is stored in a dark state for a long time, a phenomenon occurs in that the lighting is delayed by completely disappearing the electrons in the tube. That is, even when a voltage is applied to the electrode, a process in which electrons in the tube collide with the electrode and release secondary electrons does not easily occur, so that the current does not flow in the tube, resulting in a delay in lighting.

This phenomenon increases with time left in the dark state, and electrons are generated by the photoelectric effect only when a voltage of a predetermined level or more is applied to the electrodes to generate secondary electrons, which are then turned on.

Therefore, it is a feature of the present invention that the phosphor 30 for forming electrons in the tube of the fluorescent lamp 21 is provided to prevent the above-described lighting delay. The phosphor part 30 serves to transfer energy for causing the material in the tube of the fluorescent lamp 21 to emit electrons.

3 is a conceptual diagram for explaining the principle of phosphorescence. Referring to the drawings, a phenomenon in which a substance absorbs energy into an excited state and then changes into a ground state while emitting absorbed energy as light is called luminescence.

In this case, the light emission is divided into fluorescence and phosphorescence according to the light emission form.

In general, the excited state of the electrons of organic molecules has a singlet and triplet state according to the spin. When the electrons in the ground state absorb energy, they become excited in a singlet state, and the electrons in the singlet state lose some energy as vibration energy and then fall to the ground state while emitting photons. In this case, the phenomenon that the light falls to the ground state is called fluorescence.

In contrast, phosphorescence is a phenomenon in which a single state of excited state is converted into a triplet state of excited state through intersystem crossing and then falls to the ground state with light.

Both fluorescence and phosphorescence lose some energy by vibrating energy and then make light and convert it to the ground state.

In this case, the phosphorescence is different in that it maintains the excited state for a relatively long time compared to the fluorescence and lasts a long time.

As a result, the light emitted from the phosphor forms electrons in the fluorescent lamp, and the electrons collide with the electrodes in the tube to generate secondary electrons. Secondary electrons then collide with mercury atoms in the tube to generate ultraviolet light. Ultraviolet light excites the fluorescent material applied in the tube in an excited state. The excited fluorescent material is stabilized as the energy state changes to the ground state, and visible light is emitted to finally supply light to the liquid crystal panel.

 In the liquid crystal display according to the exemplary embodiment of the present invention, as shown in FIGS. 2 and 3, a phosphor 30 for providing light to the fluorescent lamp 21 is provided for the reflecting plate 28.

In this case, the position of the phosphor part 30 is not particularly limited, but overlaps the fluorescent lamp 21 vertically downward from the liquid crystal panel 10 in order to minimize light leakage due to the light emitted from the phosphor part 30. It is preferable to be provided at a predetermined position. That is, the liquid crystal panel 10 and the phosphor part 30 are provided to face each other with the central axis of the fluorescent lamp 21 interposed therebetween.

The phosphor part 30 serves to transfer energy for forming the minimum electrons to the fluorescent lamp 21 but is a kind of light source that emits light.

Therefore, when the phosphor 30 is disposed between the fluorescent lamp 21 and the fluorescent lamp 21, since the phosphor may act as a light leakage and the luminance may be non-uniform, the fluorescent lamp 21 is primarily blocked by the fluorescent lamp 21.

In addition, the phosphor part 30 is disposed below the central axis of the fluorescent lamp 21 except for the electrode part. Since the electrodes are positioned at both ends of the fluorescent lamp 21, the phosphor part 30 is close to both ends so as to generate electrons near the electrode. It is preferable that the phosphor part 30 is provided.

However, the position of the phosphor 30 is not limited thereto. If the energy can be generated to generate electrons may be located in the middle of the longitudinal direction of the fluorescent lamp (21).

Here, the phosphor part 30 is intended to form electrons by applying light energy to one or more fluorescent lamps 21 when there are a plurality of fluorescent lamps 21. It contains a substance.

In addition, phosphors emitting light above visible light include CaS: Bi, CaSrS: Bi, ZnS: Cu, ZnCdS: Cu, MAl ₂ O ₄ (M is any one of Ca, Sr, Ba, and Mg), YAlO ₃ ^{: Ce 3 +, Sr (PO} 2) Cl: Eu, Zn 2 GeO 2: Mn, Y 2 O 2 S: at least one compound selected metal or metal oxide from the group consisting of Eu is preferred.

In this case, the phosphor 30 may further include a radioisotope. Radioactive isotopes have a non-luminescent property due to half-life, and thus have an advantage of emitting energy over a long time.

In particular, among radioisotopes, promium (Pm), tritium, and radium (Ra) are preferable.

The wavelength of the light emitted from the phosphor 30 is preferably at least shorter than the infrared wavelength to form electrons in the fluorescent lamp 21.

In particular, since the wavelength of the ultraviolet ray or the blue region is high in energy, electrons can be easily formed by the photoelectric effect, but the present invention is not limited thereto. If necessary, a red light source may be used as the phosphor 30.

In the case of a direct type liquid crystal display device having a plurality of fluorescent lamps 21, when only one fluorescent lamp 21 is lit, the other fluorescent lamps 21 are chained by light emitted from the lit fluorescent lamp 21. Since it is turned on, the phosphor part 30 may be formed in a narrow area. However, it may be provided in a plurality of areas in order to supply sufficient energy.

The phosphor part 30 may be coated and formed like a paint, or may be formed by attaching the reflector 28 to another material as necessary.

As described above, the phosphor 30 is formed on the reflecting plate 28 to supply light to the fluorescent lamp 21 and generate electrons in the tube to light the fluorescent lamp 21. As a result, the lighting delay of the fluorescent lamp 21 is reduced.

In the first embodiment, the phosphor part is formed on the reflecting plate, but the position of the phosphor part is not limited thereto. If necessary, it may be formed on the rear surface of the optical sheet on the upper side of the fluorescent lamp.

On the other hand, the present invention includes not only the phosphor portion formed in the direct type liquid crystal display device but also the phosphor lighting portion formed in the edge type liquid crystal display device to improve the lighting delay.

4 is an exploded perspective view showing a liquid crystal display device according to a second embodiment of the present invention, and FIG. 5 is a cross-sectional view showing a liquid crystal display device according to a second embodiment of the present invention.

In the present embodiment, only portions distinguishing from the above-described first embodiment will be described, and descriptions omitted or summarized will follow the first embodiment and known techniques.

For the convenience of description, the same components will be described with the same reference numerals.

4 and 5, the liquid crystal display according to the second embodiment of the present invention includes a liquid crystal panel 10, a light guide plate 26 provided on a rear surface of the liquid crystal panel 10, and A fluorescent lamp 21 provided on at least one side of the light guide plate 26, and a phosphor 30 for supplying light to the fluorescent lamp 21.

Here, the light guide plate 26 has a light incident surface on which light is incident on at least one side. One side of the light guide plate 26 includes a fluorescent lamp 21 and a lamp housing 25 which surrounds the fluorescent lamp 21 and reflects the light emitted from the fluorescent lamp 21 in the direction of the light incident surface of the light guide plate 26. Is provided.

In the second embodiment of the present invention, a phosphor 30 for supplying light to the fluorescent lamp 21 is formed on the lamp housing 25.

However, the position of the phosphor 30 is not limited to the lamp housing 25 and may be formed on the reflecting plate 28. It may also be formed on other internal appliances as needed.

As described above, according to the exemplary embodiment of the present invention, the lighting delay may be reduced by forming electrons in the fluorescent lamp by the phosphor.

The detailed description of the invention should be construed as an illustration of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be defined by the described embodiments, but should be defined by the claims and their equivalents.

As described above, the liquid crystal display according to the present invention has the following effects.

The liquid crystal display device according to the present invention can implement a high-quality liquid crystal display device having a high light quality by reducing the lighting delay by forming a phosphor to reduce the lighting delay of the fluorescent lamp below or above the fluorescent lamp.

In addition, the liquid crystal display device according to the present invention can be applied to both a direct type or an edge type liquid crystal display device, thereby expanding the field of use of the liquid crystal display device.

Claims (24)

A liquid crystal panel; At least one fluorescent lamp provided below the liquid crystal panel and supplying light to the liquid crystal panel; And And a phosphorescence unit for supplying light to the fluorescent lamp. The method of claim 1, The phosphor part comprises a phosphor material. The method of claim 2, The phosphor part further comprises a radioactive isotope.  The method of claim 3, The radioactive isotope is a liquid crystal display, characterized in that any one of promethium, tritium, radium. The method of claim 1, The phosphorescent material is CaS: Bi, CaSrS: Bi, ZnS: Cu, ZnCdS: Cu, Mal 2 O 4 (M is any of Ca, Sr, Ba and ^{_{Mg), YAlO 3: Ce 3}} +, Sr (PO 2 ) Cl: Eu, Zn ₂ GeO ₂ : Mn, Y ₂ O ₂ S: Eu liquid crystal display device, characterized in that at least one metal compound or metal oxide selected from the group consisting of. The method of claim 1, And a reflecting plate below the fluorescent lamp to reflect the light emitted from the fluorescent lamp in the direction of the liquid crystal panel. And the phosphor part is formed on the reflecting plate. The method of claim 1, An optical sheet for increasing the efficiency of the light incident on the liquid crystal panel is further provided on the fluorescent lamp, And the phosphor part is formed on a rear surface of the optical sheet. The method of claim 1, And the phosphor part is provided to face the liquid crystal panel with the central axis of the fluorescent lamp interposed therebetween. The method of claim 8, And wherein the phosphor part is positioned vertically below the fluorescent lamp and overlaps the fluorescent lamp. The method of claim 8, And the auxiliary light source is positioned near both ends of the fluorescent lamp or below the center of the fluorescent lamp. A liquid crystal panel; A light guide plate provided on a rear surface of the liquid crystal panel; A fluorescent lamp provided on at least one side of the light guide plate; And And a phosphorescent part supplying light to the fluorescent lamp. The method of claim 11, The phosphor part comprises a phosphor material. The method of claim 12, The phosphor part further comprises a radioactive isotope.  The method of claim 13, The radioactive isotope is a liquid crystal display, characterized in that any one of promethium, tritium, radium. The method of claim 11, The phosphorescent material is CaS: Bi, CaSrS: Bi, ZnS: Cu, ZnCdS: Cu, Mal 2 O 4 (M is any of Ca, Sr, Ba and ^{_{Mg), YAlO 3: Ce 3}} +, Sr (PO 2 ) Cl: Eu, Zn ₂ GeO ₂ : Mn, Y ₂ O ₂ S: Eu liquid crystal display device, characterized in that at least one metal compound or metal oxide selected from the group consisting of. The method of claim 11, The light guide plate has a light incident surface on which light is incident on at least one side, And a lamp housing surrounding the fluorescent lamp and reflecting the light emitted from the fluorescent lamp toward the light incident surface of the light guide plate. And the phosphor part is formed in the lamp housing. The method of claim 11, And a reflecting plate provided on a rear surface of the light guide plate to reflect light emitted in a rear direction of the light guide plate to the light guide plate, wherein the phosphor part is formed on the reflecting plate. The method of claim 16, And the phosphor part is formed on an inner surface of the lamp housing opposite to the fluorescent lamp. A liquid crystal panel; At least one fluorescent lamp provided on a rear surface of the liquid crystal panel to supply light to the liquid crystal panel; A reflection plate provided below the liquid crystal panel and reflecting light emitted from the fluorescent lamp toward the liquid crystal panel; And And a phosphor that is formed on the reflector to supply light to the fluorescent lamp. 20. The liquid crystal display of claim 19, further comprising a lower cover disposed under the liquid crystal panel and containing a fluorescent lamp and a reflecting plate to emit light. The method of claim 19, The phosphor part comprises a phosphor material. The method of claim 21, The phosphor part further comprises a radioactive isotope.  The method of claim 22, The radioactive isotope is a liquid crystal display, characterized in that any one of promethium, tritium, radium. The method of claim 21, The phosphorescent material is CaS: Bi, CaSrS: Bi, ZnS: Cu, ZnCdS: Cu, Mal 2 O 4 (M is any of Ca, Sr, Ba and ^{_{Mg), YAlO 3: Ce 3}} +, Sr (PO 2 ) Cl: Eu, Zn ₂ GeO ₂ : Mn, Y ₂ O ₂ S: Eu liquid crystal display device, characterized in that at least one metal compound or metal oxide selected from the group consisting of.

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