JPH09166782A - Liquid crystal display with back light of field-emission type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unnecessitate a linear light source to be a surface light source, to increase the uniformity of the luminance of a light ray and to reduce the light loss for forming a back light by forming a surface light source by using a FED used as a back light source by using a two polar type FED field-emission type display element including a specified anode part and a cathode part. SOLUTION: A cathode part 200A iscomposed of a substrate 201, a lower electrode 202 arranged on the substrate 201 and a thin film discharge element 203 formed on the electrode 202. An anode part 200B is composed of a transparent plate 206 and a fluorescent body 204 on an adjusting electrode 205 and the cathode part 200A and the anode part 200B are opposed to each other and keep a fixed interval. When a voltage is applied on the FED electrodes 202 and 205, electrons are emitted from the the front surface of the emission element, the fluorescent body 204 is excited and light is emitted. The emitted light passes through a transparent plate 206 of FED, the transmissivities of red, green, blue colors selected by color filters of the liquid crystal cell are controlled by the liquid crystal cell and colors are reproduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight of a liquid crystal display device (hereinafter referred to as an LCD), and more specifically, it replaces a linear fluorescent lamp used in a conventional backlight for an LCD with a super fluorescent lamp. The present invention relates to an LCD having a field emission display device backlight, which uses a film-type field emission display device (hereinafter referred to as FED) as an LCD backlight.

[0002]

2. Description of the Related Art Recently, an LCD has been widely used as a display device instead of a cathode ray tube.
Is light and thin, has low power consumption, and has good compatibility with LSI, so C
Penetrating the RT or printed material area, clock, computer, T
V, Notebook type computer (Notebook Compute
r), widely used in telephones. The structure of the currently used TFT-LCD has a structure in which a color filter is arranged inside a liquid crystal cell filled with liquid crystal between two glass substrates and a backlight is installed on the back surface of the liquid crystal cell.

The TFT-LCD reproduces colors by controlling the light transmittance of red, green and blue selected from a backlight unit through a color filter by the liquid crystal inside the liquid crystal cell. The chromaticity at this time depends on the spectrum of the backlight, and a uniform luminance distribution of the backlight unit is required. At this time, the backlight used in the TFT-LCD should be compatible with the display device using the TFT-LCD by using a fluorescent lamp with a linear light source such as a straight tube, a U-shaped tube, and a W-shaped tube having a diameter of several mm. It is used as a surface light source.
As an example of a technique for forming a surface light source using the fluorescent lamp of the linear light source, there is a method using a light pipe.

In the light guide plate type backlight structure, a linear fluorescent lamp is located at an end of the light guide plate, a reflection plate is installed under the light guide plate, and a diffusion plate is installed over the light guide plate. There is. Part of the light emitted from the linear fluorescent lamp is guided along the light guide plate to form a surface light source. At this time, a dot-shaped pattern is formed on one or both surfaces of the light guide plate to compensate for a part of the amount of light that changes depending on the distance from the light source. To make it more uniform.

[0005]

However, in the light guide plate type backlight for forming the surface light source, the light loss is essentially large and the brightness uniformity is low in the process of converting the linear light source into the surface light source. There was a problem of becoming. Further, there is a problem that there is a structural limit in reducing the thickness and the weight.

[0006]

SUMMARY OF THE INVENTION The present invention was devised to solve a fundamental problem of a TFT-LCD by utilizing an existing light guide plate type backlight. In the case of a TFT-LCD that uses a light source, the light loss is essentially large in the process of converting the linear light source into a surface light source,
In addition to the problem of low uniformity of brightness, the existing backlight has structural limitations to reduce the thickness and weight, which limits the manufacturing of TFT-LCDs to ultra-light and ultra-thin. The purpose is to solve the problem that there is.

To achieve the above object, the present invention provides a TF
In a backlight used for a T-LCD, an adjustment electrode formed on a transparent plate, an anode portion including a phosphor formed on the adjustment electrode, and a lower electrode formed on a predetermined portion of a substrate, A cathode portion is formed on at least a portion of the lower electrode and includes a thin film type emission device that emits electrons from the surface of the lower electrode and the adjustment electrode when a voltage is applied to the lower electrode and the adjustment electrode. The feature is that a bipolar FED is used.

Further, in the present invention, in a backlight used for a TFT-LCD, a control electrode disposed on a part or more of a transparent plate and a fluorescent light formed and disposed on a part or more of the control electrode. An anode part composed of a body, and a lower electrode formed on a predetermined part of the substrate including a part or more of the part on the substrate or the substrate surface;
A triode type FED including a cathode portion made of an insulator that maintains a constant gap while electrically insulating the chip emission element and the gate electrode and the lower electrode and the gate electrode.
Is another feature. That is, when a voltage is applied to the electrodes of the FED, electrons are emitted from the surface of the emission element located at the cathode portion due to the electric field between the electrodes.

The electrons emitted from the emission element stimulate the phosphor in the anode portion to emit light, and the emitted light passes through the transparent plate (upper substrate) of the FED to cause the color of the liquid crystal cell. Colors are reproduced after controlling the light transmittance of red, green, and blue selected by a filter by a liquid crystal cell.

As described above, according to the present invention, there is no light loss when the FED used as a back light source does not need to be a surface light source and forms a surface light source to form a back light, and there is no light loss. Uniformity can be increased.

Another advantage of the present invention is that since the FED used in the backlight is ultrathin, the TED is ultrathin.
It becomes possible to manufacture an FT-LCD, and even if the FED is manufactured in a large area, there is almost no optical loss and high brightness and uniformity can be maintained. Therefore, a large-area TFT-LCD can be manufactured. become able to do. Also, a wide luminance range can be easily adjusted only by adjusting the voltage applied to the adjustment electrode.

[0012]

1 and 2 show a conventional TFT-L.
It is the figure which showed the backlight of the light guide plate system used for CD. FIG. 1 shows that the fluorescent lamp 101 is provided at the end of the light guide plate 103.
, A reflection plate 102 is located below the light guide plate 103, and a diffuser plate is located above the light guide plate 103.
r) is a front sectional view of the backlight in which the r) 104 is arranged. FIG. 2 is a perspective view in which the diffusion plate 104 shown in FIG. 1 is cut and slightly raised.

The light guide plate type backlight 100 is
A part of the light emitted from the linear fluorescent lamp 101 is coated along the light guide plate 103 to form a surface light source, and one or both of the surfaces of the light guide plate 103 has a dot-shaped pattern (not seen). ) Is formed to compensate for a part of the light amount that changes depending on the distance from the light source. Also, the diffusion plate 104 on the light guide plate 103 makes the brightness more uniform.

However, in the light guide plate type backlight, there is a problem that the light loss is essentially large and the uniformity of luminance is low in the process of converting the linear light source into a surface light source. Further, in the conventional backlight, there is a structural limit in reducing the thickness and weight, and there is a limit in manufacturing the TFT-LCD in an ultralight and ultrathin manner.

3 to 5 show a TFT-L according to the present invention.
FIG. 3 shows the structure of a bipolar FED used in a backlight for a CD, and FIG.
3 is a perspective view of a polar FED 200. FIG. The structure of the bipolar FED 200 used in the backlight is the cathode part 20.
0A and the anode part 200B. Cathode part 200
A is composed of a substrate 201, a lower electrode 202 arranged on the substrate 201, and a thin film type emission device 203 formed on the lower electrode 202, and an anode portion 200B.
Is composed of a transparent plate 206, an adjusting electrode 205 arranged on the transparent plate 206, and a phosphor 204 on the adjusting electrode 205. The cathode portion 200A and the anode portion 20
OBs face each other and maintain a gap of several hundreds of μm.

The cathode portion 200A and the anode portion 200B
In order to maintain a certain distance from the transparent plate 206 in the anode portion 200B and a predetermined portion of the cathode portion 200A on the substrate 201, a spacer 207 is additionally arranged. As a material of the spacer 207, metal, ceramics, polyimide or the like can be used. Cathode part 2 provided by the spacer 207
The space between 00A and the anode part 200B is 10 ^-6 Torr
A moderate vacuum must be maintained.

Further, as the material of the lower electrode 202, it is possible to use a metal thin film having a thickness of several thousand Å. The metal thin film is formed by sputtering or vacuum deposition. Further, as a material of the thin film type emission element 203,
Negative (-) electron affinity or low work function (work functio
The materials designated n) are suitable for the purposes of the invention.

A diamond thin film is an example of the thin film type emitting device material used in the present invention. Here, the term thin film is synthesized by chemical vapor deposition such as plasma CVD, physical vapor deposition such as sputtering or ion beam, and laser ablation (or pulse laser deposition (Pulsed Laser Deposition)). Is a general term for the diamond thin film and diamond-like carbon (Diamond-like carbon). But also.

Here, the diamond thin film is
It does not mean that its constituent elements consist of pure carbon only, and that carbon is the main component of hydrogen, metal, or metalloid (meta).
lloid) is included. In general, pure diamonds
The graphite is shown as a p ³ bond structure and is insulative, while pure graphite is shown as a sp ² bond structure and delocalized electrons (del
Since it has ocalized electron), it becomes conductive. However, the thin film here does not mean that the bonds between carbons are pure sp ³ hybrid bonds, and a mixture of sp ¹ , sp ^2, etc. bonds is also possible. is there.

Further, the composition ratio of the constituent elements of the diamond is atomic% (atomic%), the following formula Cx-Hy-Mz (where C is carbon, H is hydrogen, M is Cr, Mo, W,
From transition metals such as V, Nb, Ta, Ti, Zr and Hf,
At least one and 60 ≦ x ≦ 100, 0 ≦ y ≦ 40,0
≦ z ≦ 40 and x + y + z = 100). The material of the adjusting electrode 205 is an ITO thin film that is transparent to visible light, and this ITO thin film is formed on a transparent plate 206 such as transparent glass. A phosphor 204 is formed on the control electrode 205.
Are formed and arranged.

FIG. 4 shows the ABC shown by the broken line in FIG.
The D portion is shown, and the cathode portion 200A and the anode portion 20 are shown.
It is an enlargement of OB. FIG. 5 shows the emission device 2 of FIG.
FIG. 23 is an enlarged view of an EFGH portion, which is a broken line portion indicated by 03, and is an enlarged view showing the position of a spacer 207 placed between the cathode portion 200A and the anode portion 200B. When the FED has a large area, a plurality of the spacers 207 are installed.

In FIG. 6, a voltage is applied from a power supply unit 208 between the lower electrode 202 of the cathode portion 200A and the adjusting electrode 205 of the anode portion 200B shown in FIG. 20 electrons from the surface of
9 shows the state in which 9 is released. The thin film type emitting device 203
The electrons 209 emitted from collide with the phosphor 204 to excite the phosphor 204, and light 210 is emitted. At this time, the emitted light 210 becomes a flat light source with uniform brightness. Also, the brightness of the emitted light 210 is controlled by the adjustment electrode 2
It is possible to easily adjust in a wide luminance range by adjusting the voltage applied to 05.

FIG. 7 shows an arrangement in which a reflection film 211 is additionally formed on the phosphor 204 of the anode part 200B from the bipolar FED used in the backlight shown in FIG. The reflective film 211 improves the brightness of the bipolar FED. At this time, as the material of the reflective film 211,
An Al film widely known from the existing CRT manufacturing technology is used. However, at this time, the thickness of the Al thin film must be sufficiently thin so that the accelerated electrons 209 can pass through the Al thin film and excite the phosphor 204.

Further, the voltage applied to the adjusting electrode 205 is in the range of several tens of kV, and within the range of the voltage, it is possible to use the well-known phosphor for CRT having a high luminous efficiency. . As described above, the bipolar FED is used for the TFT
-Can be used as a backlight for LCD,
It is also possible to use a triode FED with other backlights.

8 to 10 show a TFT according to the present invention.
1 shows a chip-type 3-pole FED, which is an example of a 3-pole FED used in a backlight for an LCD. Figure 8 shows the TFT
FIG. 6 is a perspective view of a chip-type 3-pole FED 300 used in a backlight for LCD. The chip type 3-pole FE
The structure of D300 has a cathode part 300A and an anode part 300.
Divided into B. The cathode portion 300A includes a substrate 301, a lower electrode 302 disposed on the substrate 301, one or more chip emission devices 303 formed on the lower electrode 302, and a gate electrode 305 serving to extract electrons.
And an insulator 304 that maintains a constant gap while electrically insulating the lower electrode 302 and the gate electrode 305.

The anode part 300B is composed of a transparent plate 308, an adjusting electrode 307 arranged on the transparent plate 308, and a phosphor 306 formed on the adjusting electrode 307. The cathode part 300A and the anode part 300B face each other to maintain a gap of several hundreds of μm. or,
In order to maintain a constant distance between the anode part 300B and the cathode part 300A, the transparent plate 308 of the anode part 300B is maintained.
A spacer 309 is additionally arranged between a predetermined portion of the substrate 301 and a predetermined portion of the cathode portion 300A on the substrate 301. As a material of the spacer 309, metal, ceramic, or polyimide is used. As in the case of FIG. 3, the anode portion 300
The space between B and the cathode portion 300A must maintain a vacuum.

As the material of the lower electrode 302, it is possible to use metal or silicon having a thickness of several thousand Å. This metal thin film is formed by sputtering or vacuum evaporation. The emission element 303 has a conical or pyramid shape, and the electron emission characteristics depend on the sharpness of the tip. In addition, the sharper the tip, the easier the electric field is concentrated near the tip and the easier the electron emission. The micromeme chip of about micrometer (μm) can be manufactured mainly by an inclined metal vapor deposition method using an electron beam vapor deposition apparatus, isotropic or anisotropic etching of a silicon single crystal. .

As another material of the chip emission device 303, a negative (-) electron affinity or a low work function is used.
A material exhibiting a ction) can be used. Since the diamond thin film is the same as the description of FIG. 3, the description thereof will be omitted. In addition, the adjustment electrode 307 and the phosphor 30
Since 6 is also the same as the description of the bipolar FED, the description thereof is omitted.

FIG. 9 shows the ABC indicated by the broken line in FIG.
FIG. 3 is an enlarged cross-sectional view of an anode portion 300B and a cathode portion 300A, which is an enlarged view of a portion D. FIG.
8 is an enlarged plan view of an EFGH portion shown by a broken line in FIG. Show.

FIG. 11 shows a lower electrode 302 of the cathode portion 300A of the chip type three-pole FED 300 shown in FIG.
A voltage is applied from the first power supply device 310 between the gate electrode 305 and the gate electrode 305 to emit electrons 312, and the lower electrode 30
2 and the adjustment electrode 307 are also applied with a voltage from the second power supply device 311 so that the tip emitting device 30 of the cathode portion 300A can be prevented.
3 shows a state in which electrons 312 emitted from No. 3 are accelerated to the anode part 300B.

The electrons 312 emitted from the chip emission device 303 are the control electrodes 3 to which a higher voltage is applied.
The electrons 312 accelerated toward 07 collide with the phosphor 306 to excite the phosphor 306, and the light 31
3 is released. At this time, the emitted light 313 becomes a flat light source with uniform brightness. Also, the brightness of the emitted light 313 can be easily adjusted in a wide brightness range by adjusting the voltage applied to the gate electrode 305 and the adjustment electrode 307.

Next, FIG. 12 shows an arrangement in which a reflective film 314 is additionally formed on the phosphor 306 of the anode portion 300B of the chip type three-pole FED 300 according to the present invention. The reflective layer 314 serves to improve brightness. As the material of the reflective film 314, an Al thin film is used as in the bipolar FED.

As described above, when the two-pole type or three-pole type FED is used in the backlight for the TFT-LCD according to the present invention, it is possible to enhance the brightness uniformity in the backlight as compared with the conventional one. Further, since the FED does not require a process of forming a surface light source, it is possible to prevent light loss generated in the process of forming a surface light source. Therefore, it is easy to thin the film and increase the area without loss of brightness uniformity and light utilization.
It is possible to provide a backlight for a TFT-LCD having a simple structure in which the brightness can be easily adjusted.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a structure of a backlight used in a conventional TFT-LCD.

FIG. 2 is a perspective view showing a state in which a diffusion plate is separated from the backlight of FIG.

FIG. 3 is a perspective view of a bipolar FED used in a backlight of a TFT-LCD according to the present invention.

FIG. 4 is a partial front cross-sectional view showing an enlarged ABCD portion shown by a broken line in FIG.

5 is a partial cross-sectional view showing a state in which an EFGH portion shown by a broken line in FIG. 3 is cut downward.

6 is a bipolar FE used in the backlight of FIG.
FIG. 7 is a partial front cross-sectional view showing a state in which electrons and light are emitted by applying a voltage between the adjustment electrode and the lower electrode of D.

7 is a bipolar FE used in the backlight of FIG.
FIG. 6 is a partial front cross-sectional view showing a state in which a reflective film is installed on the anode part of D.

FIG. 8 is a perspective view of a triode FED used in the backlight of the TFT-LCD according to the present invention.

9 is a partial front cross-sectional view showing an enlarged ABCD portion indicated by a broken line in FIG.

10 is a partial cross-sectional view showing a state in which the EFGH portion shown by the broken line in FIG. 8 is cut downward.

11 is a three-pole F used in the backlight of FIG.
FIG. 7 is a partial front cross-sectional view showing a state in which electrons and light are emitted by applying a voltage between a control electrode, a lower electrode and a gate electrode of the ED.

FIG. 12 is a three-pole F used in the backlight of FIG.
FIG. 3 is a partial front cross-sectional view showing a state in which a reflective film is installed on the anode portion of ED.

[Explanation of symbols]

 100 Backlight 101 Fluorescent Lamp 102 Reflector 103 Light Guide Plate 104 Diffuser 200A, 300A Cathode Part 200B, 300B Anode Part 201, 301 Substrate 202, 302 Lower Electrode 203 Thin Film Emitting Element 204, 306 Phosphor 205, 307 Control Electrode 206 , 308 Transparent plate 207, 309 Spacer 208 Power supply device 209, 312 Electrons 210, 313 Light 211, 314 Reflective film 303 Chip emission device 304 Insulator 305 Gate electrode 310 First power supply device 311 Second power supply device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Choi Jong Ogg Seoul, Songpag, Karak 1 Dong (No address displayed) Karak Apartment 108-108 (72) Inventor Kim Han, Kyonggido, Yongin City, Republic of Korea Sugaup, Phongdukchon (No street number) Hyundai Apartment 101-801

Claims (20)

[Claims] 1. A control electrode formed on a transparent plate, an anode portion made of a phosphor formed on the control electrode, a lower electrode formed on a predetermined portion of a substrate, and formed on the lower electrode. Power supply for applying a voltage between the lower electrode of the cathode portion and the adjustment electrode of the anode portion in order to emit electrons from the cathode portion of the emitter portion and the emission element of the cathode portion. A liquid crystal display device having a backlight of a field emission display device composed of the device. 2. The liquid crystal display device according to claim 1,
A spacer is formed in the space between the cathode portion and the anode portion.
r) is installed, a liquid crystal display device having a backlight of a field emission display element. 3. The liquid crystal display device according to claim 1,
The liquid crystal display device having a backlight of a field emission display device, wherein the emission device is a diamond thin film. 4. The liquid crystal display device according to claim 1, wherein the emission element is a polycrystalline diamond thin film, and a backlight for a field emission display element is provided. Liquid crystal display device to have. 5. The liquid crystal display device according to claim 1 or 3, wherein the emission element uses amorphous diamond, and a backlight for a field emission display element is provided. Liquid crystal display device to have. 6. The liquid crystal display device according to claim 1, wherein the emission element is amorphous, a mixture of amorphous and crystalline, or a transition metal.
A liquid crystal display device having a back light of a field emission display element, characterized by using a diamond thin film containing a. 7. The liquid crystal display device according to claim 1 or 3, wherein the component ratio of the constituent elements of the emission element is atomic% and the following formula Cx-Hy-Mz (where C is Carbon, H is hydrogen, M is Cr, Mo, W,
From transition metals such as V, Nb, Ta, Ti, Zr and Hf,
At least one and 60 ≦ x ≦ 100, 0 ≦ y ≦ 40,0
≦ z ≦ 40, and x + y + z = 100) is used, and a liquid crystal display device having a backlight of a field emission display device is used. 8. The liquid crystal display device according to claim 1,
The liquid crystal display device having a backlight of a field emission display device, wherein the transparent plate is glass. 9. The liquid crystal display device according to claim 1,
The liquid crystal display device having a backlight of a field emission display device, wherein the substrate is a glass or silicon wafer. 10. The liquid crystal display device according to claim 1, further comprising a reflective film additionally formed and arranged on the phosphor of the anode portion, thereby forming a backlight for a field emission display device. Liquid crystal display device. 11. An adjusting electrode formed on a transparent plate, an anode portion made of a phosphor formed on the adjusting electrode, a lower electrode formed on a predetermined portion of a substrate, and formed on the lower electrode. One or more chip emitting devices, a cathode portion formed of a gate electrode formed on the lower electrode via an insulator that electrically insulates the lower electrode and maintains a constant gap, A first electrode for applying a voltage to the lower electrode and the gate electrode of the cathode portion to emit electrons from the chip emitting device.
A power supply device, a second power supply for applying a voltage between a lower electrode of the cathode part for accelerating electrons emitted from the chip emission device to an anode part, and a control electrode of the anode part. A liquid crystal display device having a backlight of a field emission display device composed of the device. 12. The liquid crystal display device according to claim 11, wherein a spacer is arranged between the cathode portion and the anode portion, and the liquid crystal display device has a backlight of a field emission display element. 13. The liquid crystal display device according to claim 11, wherein the material of the chip emission device is diamond, and the liquid crystal display device has a backlight of a field emission display device. 14. The liquid crystal display device according to claim 11 or 13, wherein a polycrystalline diamond thin film is used as a material of the chip emission element. Liquid crystal display device with backlight. 15. The liquid crystal display device according to claim 11 or 13, wherein the chip emission element is made of amorphous diamond. Liquid crystal display device with backlight. 16. The liquid crystal display device according to claim 11 or 13, wherein the material of the chip emission element includes an amorphous material, a mixture of an amorphous material and a crystalline material, or a transition metal. Liquid crystal display device having a back light of a field emission display element characterized by using a diamond. 17. The liquid crystal display device according to claim 11 or 13, wherein the material of the chip emission element has the following formula Cx-Hy-Mz (wherein the component ratio of constituent elements is atomic%). However, C is carbon, H is hydrogen, M is Cr, Mo, W,
From transition metals such as V, Nb, Ta, Ti, Zr and Hf,
At least one and 60 ≦ x ≦ 100, 0 ≦ y ≦ 40,0
≦ z ≦ 40, and x + y + z = 100) is used, and a liquid crystal display device having a backlight of a field emission display device is used. 18. The liquid crystal display device according to claim 11, wherein the transparent plate is glass, and which has a backlight of a field emission display element. 19. The liquid crystal display device according to claim 11, wherein the substrate is a glass or a silicon wafer and has a backlight of a field emission display device. 20. The liquid crystal display device according to claim 11, further comprising a reflective film additionally formed and arranged on the phosphor of the anode portion, thereby forming a backlight for a field emission display device. Liquid crystal display device.