KR100493175B1 - Phosphor cleaning method for the back substrate and the front substrate of the field emission display device - Google Patents

Abstract

A phosphor cleaning method of a back substrate and a front substrate of a field emission display device according to the present invention includes a back substrate having a field emitter array having a micro tip; And a front substrate on which a phosphor is coated on a transparent electrode by using a mixed solution containing a fluorescent material and a predetermined organic solvent. (A) In the vacuum chamber, the back substrate and the phosphor are coated. Removing carbon organic substances remaining on the front substrate with a cleaning gas; And (b) exhausting residual gas in the vacuum chamber; and (b) next to (c), (c) bonding the back substrate and the front substrate to form a display element; (D) adsorbing the display element with a mixed gas in the vacuum chamber; And (e) exhausting residual gas in the vacuum chamber; further comprising: a back substrate on which a field emitter array having a micro tip is formed, and a front substrate on which a phosphor is coated on a transparent anode; By removing the remaining organic material, the luminous efficiency of the phosphor is increased, and the cause of micro tip contamination is eliminated, thereby extending the life of the display device.

Description

Phosphor cleaning method for the back and front substrates of the field emission display device

According to the present invention, in the manufacture of a field emission display, organic materials remaining on phosphors on a back substrate and a front substrate of a field emission display device having a field emitter array having a micro tip are formed. The present invention relates to a method of cleaning phosphors on a back substrate and a front substrate of a field emission display device to be removed.

1 is a schematic cross-sectional view of a general field emission display device. As shown in the drawing, the field emission display device has a structure in which the rear substrate 11 and the front substrate 12 which are spaced apart at regular intervals to face each other are sealed.

The cathode 111, the insulating layer 112, the gate 113, and the micro tip 114 are formed on the rear substrate 11. On the opposite surface of the back substrate of the front substrate 12, an anode 121 is formed in a stripe shape, and a phosphor 122 is coated on the anode 121.

The field emission display device having such a configuration uses a field emission in which electrons stick out by a strong electric field formed around the micro tip 114, unlike a vacuum tube that uses thermal emission to emit electrons.

That is, a strong electric field is formed at the micro tip 114 by the voltage difference between the cathode 111 and the gate 113, and electrons concentrated at the micro tip 114 are emitted to the outside by the tunneling effect. . The emitted electrons are accelerated by the voltage applied to the anode 121 and collide with the phosphor 122 with high energy. The phosphor 122 having the electrons collided is excited to emit light of a predetermined color.

In manufacturing such a field emission display device, the phosphor 122 is formed on an anode (generally, an ITO transparent electrode) 121 by electrophoresis, spin coating, screen printing, or the like.

Electrophoresis method is a method of depositing the surface of the fluorescent material by the electric charge, and the process will be described with reference to FIG. 2.

As shown in FIG. 2, the lines respectively connected to the positive electrode and the negative electrode of the power supply 20 are disposed in the container 21 at a predetermined distance from each other. An electrode plate 22 is connected to a line connected to the anode of the power supply, and a front substrate 23 having a transparent electrode is connected to a line connected to the cathode. The predetermined mixed liquid 24 is put in the container 21.

The mixed solution 24 is formed by mixing a fluorescent substance, a metal salt for causing surface charges on the fluorescent substance, and an organic solvent. In addition, formic acid, which is a conductive substance, is added, and glycerin or the like is added as a stabilizer.

When the mixed liquid 24 prepared as described above is filled in the container 21 and a predetermined voltage is applied to the power source 20, the metal salt in the container 21 is ionized, and the negative ions are absorbed by the electrode plate 22. The cation is absorbed to the surface of the fluorescent material. The fluorescent materials absorbing the cations are charged with a surface charge, which is attracted to the cathode of the power supply 20. Then, it is applied to the transparent electrode of the front substrate 23 connected to the cathode.

However, since the phosphor 122 is used by mixing an organic component such as an organic solvent, an organic binder, and the like with a fluorescent material, a problem that residual carbon organic material is formed after the phosphor 122 is coated on the anode 121. This happens.

In addition, when the field emission display device operates, pollutant gas is generated by oxidation of the phosphor, and the chemical formula thereof is as follows.

[Formula 1]

[Formula 2]

Formula 1 uses a compound of zinc sulfide (ZnS) to form green and blue phosphors (wherein Zn _colloid is zinc metal), and Formula 2 is yttrium oxysulfide (Y ₂ O ₃₎ to form a red phosphor. In the operation of the field emission display device using the compound of), an oxidation reaction is caused by the collision of electron beams to generate sulfur dioxide (SO ₂ ) gas.

That is, the residual organic substances act as various pollutants to lower the luminous efficiency of the phosphor 122. In particular, when the residual organic substances are positioned in the path where the electron beam is irradiated, energy incidence to the fluorescent substance 122 is disturbed, thereby lowering the luminous efficiency.

In addition, if the time for which the electron beam is irradiated to the remaining organic material is long, there is a problem that the remaining organic material is gasified to damage the micro tip 114 of the back substrate to reduce the overall performance of the field emission display device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the rear substrate and the front substrate of the field emission display device which remove organic substances remaining on the back substrate of the field emission display device and the front substrate coated with the phosphor on the transparent anode. It is an object of the present invention to provide a phosphor cleaning method.

According to the present invention in order to achieve the above object, a back substrate having a field emitter array having a micro tip; And a front substrate on which a phosphor is coated on a transparent electrode by using a mixed solution containing a fluorescent material and a predetermined organic solvent. (A) In the vacuum chamber, the back substrate and the phosphor are coated. Removing carbon organic substances remaining on the front substrate with a cleaning gas; And (b) evacuating the residual gas in the vacuum chamber. A method of cleaning phosphors on a back substrate and a front substrate of a field emission display device is provided.

Preferably, after the step (b), (c) bonding the back substrate and the front substrate to form a display element; (D) adsorbing the display element with a mixed gas in the vacuum chamber; And (e) exhausting the residual gas in the vacuum chamber.

Preferably, in the step (a), the cleaning gas comprises at least one of a mixed gas of helium and nitrogen, an argon gas, a mixed gas of hydrogen and nitrogen, and in the step (a), the cleaning gas is 300 to Heating to 400 ° C. injects 30 L of the cleaning gas per minute into the vacuum chamber for 30 minutes.

Preferably, in the step (d), the mixed gas is a sulfide gas, and in the step (d), the mixed gas is heated to 350 to 450 ° C. to inject 1 to 10 ppm of the mixed gas into the vacuum chamber. Characterized in that.

In addition, according to another type of the invention, the back substrate is formed a field emitter array having a micro tip; And a front substrate on which a phosphor is coated on a transparent electrode by using a mixed solution containing a fluorescent material and a predetermined organic solvent. Bonding the rear substrate and the front substrate to form a display device; (B) adsorbing the display element with a mixed gas in the vacuum chamber; And (c) evacuating residual gas in the vacuum chamber. A method of cleaning phosphors on a back substrate and a front substrate of a field emission display device is provided.

Preferably, in the step (b), the mixed gas is a sulfide gas, and the mixed gas is heated to 350 to 450 ° C. to inject 1 to 10 ppm of the mixed gas into the vacuum chamber.

Hereinafter, the phosphor cleaning method of the back substrate and the front substrate of the field emission display device according to the present invention will be described in detail with reference to the accompanying drawings.

According to the phosphor cleaning method of the back substrate and the front substrate of the field emission display device according to the present invention, first, a back substrate on which a field emitter array having a micro tip is formed, and a phosphor is coated by electrophoresis as described above. Form the front substrate.

Here, the phosphor of the front substrate is zinc sulfide (ZnS): copper (Cu), aluminum (Al), which is a green phosphor, zinc sulfide (ZnS): silver (Ag), which is a blue phosphor, and yttrium, which is a red phosphor. Oxisophite (Y ₂ O ₂ S): Europium (Eu) fluorescent materials are prepared in the following composition, respectively.

First, 10 ml of aluminum nitrate (Al (NO ₃ ) ₃ ), which is a metal salt, 500 ml of isopropyl alcohol (IPA), and a stabilizer, as a charging agent, were applied to 35 g of the red, green, and blue fluorescent materials described above. 6 ml of glycerin and the like are mixed. Next, it is separated into two round flasks, filled into an ultrasonic container and stirred for 40 minutes, and 5-6 drops of formic acid (CH ₂ O ₂ ) are added with a conductive aid to adjust the conductivity of the solution and pour into the container. Then, the process as described above is performed once more to prepare a mixed solution of 1 L to pour the container. Next, the plating solution prepared as above is put into an ultrasonic container, and stirring is performed before performing the fluorescent film coating process by electrophoresis.

Since the phosphor coating process is the same as the prior art process of the electrophoresis method shown in Figure 2 will be omitted.

In this way, the front substrate coated with the phosphor and the back substrate are moved to a vacuum chamber, and a cleaning gas is injected into the vacuum chamber while maintaining a high temperature to remove carbon organic substances remaining in the phosphors of the back substrate and the front substrate, respectively. . This process will then be described in more detail with reference to the vacuum chamber shown in FIG. 3.

As shown in FIG. 3, in the vacuum chamber 40, the support 41 is connected to the negative terminal of the power source 42, and the gas generator 43 is connected to the positive terminal of the power source 42. have. The chamber 40 is connected with a vacuum pump 44 for maintaining the interior in a high vacuum state.

The front substrate 45 coated with the phosphor and the rear substrate 45a are placed on the support 41 in the chamber 40 without bonding, and a predetermined voltage is applied to the power supply. Then, the positive ions of the gas from the gas generating unit 43 is accelerated toward the cathode to sputter the front substrate 45 and the rear substrate 45a. Then, the organic material remaining on the back substrate 45a and the phosphor of the front substrate 45, that is, residual carbon contaminants, is gasified and removed by the cation of the gas.

Here, the cleaning gas injected from the gas generator 43 is composed of a helium / nitrogen mixed gas, an argon gas, or a hydrogen / nitrogen mixed gas, and the cleaning gas is heated by heat of 300 to 400 ° C. 30 l of cleaning gas per minute is injected into the vacuum chamber 40 for 30 minutes. In this invention, it is preferable to apply the temperature of 350 degreeC.

When gas cleaning is performed, residual carbon pollutants remaining in the phosphors on the back substrate and the front substrate are gasified by the cleaning gas and discharged under vacuum, thereby increasing the luminous efficiency of the phosphor.

That is, the organic material remaining during formation of the back substrate and the organic material added during phosphor formation are reduced in carbonization and coking, and the emission of electron beams is stabilized.

Next, the display element 46 in which the residual gas in the vacuum chamber 40 is exhausted and the back substrate on which the field emitter array having the micro tip is formed and the front substrate on which the phosphor is applied are bonded are bonded in the same manner as described above. Is placed in the vacuum chamber 40, and 1 to 10 ppm of sulfide gas (H ₂ S) is injected while heating the mixed gas with heat of 350 to 450 ° C., and the display element 46 of the front substrate on which the back substrate is bonded and the phosphor is formed. ). In this invention, it is preferable to apply the heating temperature of 450 degreeC, and 1 ppm of sulfide gas.

Next, the pre-poisoned back substrate 45a and the front substrate 45 in the vacuum chamber 40 are adsorbed to the bonded display element 46 and the remaining gas in the remaining vacuum chamber 40 is exhausted.

Sulfur dioxide gas generated by oxidation reaction with a phosphor by electron beam collision when a small amount of elemental sulfur is adsorbed on the surface of the back substrate on which the field emitter array is formed by poisoning of sulfide gas (H ₂ S). By preventing contamination of the microtip by the microparticles, the activation of the microtips is stabilized, the electron beam emission is stabilized for a long time, and the luminance is increased.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited only to the Examples described below.

Example 1

Zinc sulfide (ZnS): green fluorescent substance (Cu), aluminum (Al), zinc sulfide (ZnS): blue fluorescent substance (silver), and yttrium oxysulfide (Y ₂ O ₂ S) which is red fluorescent substance ): 10 ml of aluminum nitrate (Al (NO ₃ ) ₃ ), a Group IIIA metal salt, and 6 ml of glycerin as an organic solvent, 500 ml of isopropyl alcohol (IPA) in 35 g of each of the three fluorescent materials of Europium (Eu) After mixing into two round flasks, filling them in an ultrasonic container, stirring them for 40 minutes, and adding 5-6 drops of formic acid (CH ₂ O ₂ ) as a conductive aid to adjust the conductivity of the solution and pour into the container. Then, the process as described above is performed once more to prepare a mixed solution of 1 L to pour the container. Next, the plating solution prepared as above is put into an ultrasonic container, and stirring is performed before performing the fluorescent film coating process by electrophoresis. Then, the phosphor was coated on the transparent electrode of the front substrate by an electrophoresis method in which a phosphor was applied to the transparent electrode by applying a predetermined voltage. Next, the back substrate on which the field emitter array having a micro tip is formed by the cleaning method according to the present invention and the front substrate on which the phosphor is applied are placed in a vacuum chamber without bonding. Helium / nitrogen mixed gas, argon gas, or hydrogen / nitrogen mixed gas was injected and cleaned. Then, only the green phosphor was selected and the amounts of each component of the phosphor were examined.

Comparative Example 1

After forming a back substrate having a field emitter array having a micro tip and a front substrate coated with a phosphor on a transparent electrode by the same method as in Example 1, the green phosphor was not cleaned. Only bays were selected and the amount of each component of the phosphor was examined.

TABLE 1

As can be seen from Table 1, the carbon component was significantly reduced than before the cleaning operation, and the concentrations of sulfur and zinc were increased.

That is, by performing the phosphor cleaning method of the back substrate and the front substrate of the field emission display device according to the present invention, carbon, which is a residual pollutant of the coated phosphor, was reduced, and the surface of the phosphor was relatively clean, thereby increasing the concentration of sulfur and zinc. You can see that.

Example 2

Zinc sulfide (ZnS): copper (Cu), aluminum (Al), a green fluorescent substance, zinc sulfide (ZnS): silver (Ag), a blue fluorescent substance, and yttrium oxy, a red fluorescent substance, in the same manner as in Example 1. Sulphide (Y ₂ O ₂ S): 10 ml of aluminum nitrate (Al (NO ₃ ) ₃ ), a Group IIIA metal salt, and 6 ml of glycerin as a stabilizer in 35 g of each of the three fluorescent materials of Europium (EU) 500 ml of propyl alcohol (IPA) was mixed, separated into two round flasks, filled into an ultrasonic container, stirred for 40 minutes, and 5-6 drops of formic acid (CH ₂ O ₂ ) was added as a conductive aid to improve the conductivity of the solution. Adjust and courage. Then, the process as described above is performed once more to prepare a mixed solution of 1 L to pour the container. Next, the plating solution prepared as above is put into an ultrasonic container, and stirring is performed before performing the fluorescent film coating process by electrophoresis. Then, a front substrate on which the phosphor is coated is formed on the transparent electrode by an electrophoresis method in which a phosphor is applied to the transparent electrode by applying a predetermined voltage, and a back substrate on which a field emitter array having a micro tip is formed. Are bonded to form a display element. After that, the display element was placed in a vacuum chamber, and the emission current after the sulfide gas (H ₂ S) was adsorbed and the light emission luminance were examined after 1000 hours of light emission experiment.

Comparative Example 2

After the phosphors on the front substrate and the back substrate formed by the same method as in Example 2 were bonded to form a display element, the emission current was examined after a change in emission current and a 1000-hour light emission experiment without adsorption of sulfide gas.

TABLE 2

As can be seen from Table 2, after the phosphor on the front substrate and the back substrate are bonded to form a display element, sulfide gas is adsorbed on the display element to change the emission current and emit light after 1000 hours of light emission experiment. When irradiated, the emission current after 1 hour of initial stage decreased compared with the case where no sulfide gas was adsorbed to a display element. However, it can be seen that as time passes, the emission current increases by adsorption of sulfide gas.

It can be seen that the electron beam emission is stabilized for a long time during operation by adsorbing a small amount of sulfur element on the surface of the back substrate to prevent contamination by sulfur dioxide gas generated by the oxidation reaction of the phosphor. After the long time light emission of the display element, the brightness is also increased.

According to the phosphor cleaning method of the back substrate and the front substrate of the field emission display device according to the present invention, a back substrate on which a field emitter array having a micro tip is formed, and a front surface coated with phosphor on a transparent anode By removing the organic material remaining on the substrate, the luminous efficiency of the phosphor is increased, and the cause of micro tip contamination is eliminated, thereby extending the life of the display device.

1 is a cross-sectional view schematically showing a general field emission display device;

2 is a view for explaining a process of applying a phosphor by electrophoresis;

3 and 4 schematically illustrate a vacuum chamber used in the phosphor cleaning method of the back substrate and the front substrate of the field emission display device according to the present invention.

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

20 ... Power 21 ... Container

22 ... electrode plate 24 ... phosphor mixture

23. Front substrate with transparent electrode

40 ... vacuum chamber 41 ... support

43 ... gas generator 44 ... vacuum pump

45. Front substrate coated with phosphor on transparent electrode

45a ... backplane

46 ... Display element bonded field emitter array and front board

Claims (8)

A back substrate having a field emitter array having a micro tip; And a front substrate on which a phosphor is coated on a transparent electrode by using a mixed solution containing a fluorescent material and a predetermined organic solvent. (A) removing, in a vacuum chamber, carbon organic substances remaining on the rear substrate and the front substrate to which the phosphor is applied, as a cleaning gas; (B) evacuating the residual gas in the vacuum chamber; (C) bonding the rear substrate and the front substrate to form a display element; (D) adsorbing a mixed gas to the display device in the vacuum chamber; And (E) exhausting the residual gas in the vacuum chamber; and a method of cleaning the phosphor of the back substrate and the front substrate of the field emission display device. The method of claim 1, wherein in step (a), The cleaning gas may include at least one of a mixed gas of helium and nitrogen, an argon gas, a mixed gas of hydrogen and nitrogen, and the phosphor cleaning method of the back substrate and the front substrate of the field emission display device. The method of claim 1, wherein in step (a), The cleaning gas is heated to 300 to 400 ℃ the cleaning gas of the back substrate and the front substrate of the field emission display device, characterized in that for 30 minutes injecting the cleaning gas 30 minutes per minute into the vacuum chamber. The method of claim 1, wherein in the step (d), The mixed gas is a sulfide gas, the method of cleaning the phosphor of the back substrate and the front substrate of the field emission display device. The method of claim 1, wherein in the step (d), The mixed gas is heated to 350 to 450 ℃ to inject the mixed gas of 1 to 10ppm into the vacuum chamber phosphor cleaning method of the back substrate and the front substrate of the field emission display device. A back substrate having a field emitter array having a micro tip; And a front substrate on which a phosphor is coated on a transparent electrode by using a mixed solution containing a fluorescent material and a predetermined organic solvent. (A) bonding the back substrate and the front substrate to form a display device; (B) adsorbing a mixed gas to the display element in the vacuum chamber; And (C) exhausting the residual gas in the vacuum chamber; phosphor cleaning method of the back substrate and the front substrate of the field emission display device. The method of claim 6, wherein in the step (b), The mixed gas is a sulfide gas, the method of cleaning the phosphor of the back substrate and the front substrate of the field emission display device. The method of claim 6, wherein in the step (b), The mixed gas is heated to 350 to 450 ℃ to inject the mixed gas of 1 to 10ppm into the vacuum chamber phosphor cleaning method of the back substrate and the front substrate of the field emission display device.