Patent Application
20120319561
This application claims priority under 35 U.S.C. §119(a) from Korean Patent Application No. 10-2011-0059166, filed on Jun. 17, 2011 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.
1. Technical Field
Apparatuses and methods consistent with exemplary embodiments of the present inventive concept relate to a field emission panel, a liquid crystal display and a field emission display having the same.
2. Description of the Related Art
A field emission material is a material that emits electrons if an electric field is formed around the material in a vacuum atmosphere. A representative example of a field emission material is a carbon nano tube (CNT). A panel that generates light using such a field emission material can be fabricated and applied to a backlight unit of a liquid crystal display (LCD) and an image implementation panel of a field emission display (FED). Hereinafter, such a type of panel will be called a “field emission panel”.
The field emission panel includes an upper plate and a lower plate which are arranged in parallel to each other. A phosphor layer is provided on the upper plate, and electron emission elements formed of a filed emission material are provided on the lower plate, so that white light or a color image is generated from the phosphor layer when electrons emitted by the electron emission elements collide with the phosphor layer.
In general, the lower plate of the field emission panel includes a glass plate and an insulating layer arranged on an upper surface of the glass plate, and accommodation grooves for accommodating electron emission elements are formed on the insulating layer through an exposure and etching process. Further, the accommodation grooves generally have a pattern that is composed of plural rows and columns.
However, since conventional methods for forming the above-described accommodation grooves typically include processes for forming the insulating layer and for performing the exposure and etching, such methods are disadvantageous in fabrication time and cost. Further, because the accommodation grooves may have a pattern that is composed of plural rows and columns, the lower plate may have limitations in quantity of accommodated electron emission elements, and these limitations may cause the lifespan of the field emission panel to be shortened.
Exemplary embodiments according to the present inventive concept have been made to address at least the above problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of an exemplary embodiment provides a field emission panel, a liquid crystal display and a field emission display having the same, which can reduce the fabrication time and cost and increase the lifespan thereof
According to one aspect of an exemplary embodiment, a field emission panel includes a lower plate emitting electrons and an upper plate generating white light or a color image through collision with the electrons, wherein the lower plate includes plural field emission elements; plural cathode electrodes and plural gate electrodes forming an electric field for electron emission from the electron emission elements; and a glass plate supporting the electron emission elements, the cathode electrodes, and the gate electrodes. The gate electrodes are arranged on an upper surface of the glass plate, and the glass plate has plural accommodation grooves for accommodating the plural electron emission elements and the plural cathode electrodes.
The plural accommodation grooves may be concavely formed from the upper surface of the glass plate.
The plural accommodation grooves may be in a stripe shape, and may be extended along a width direction of the glass plate.
The plural accommodation grooves may be arranged at equal intervals.
Each of the accommodation grooves may have a bottom surface and a pair of side surfaces neighboring the bottom surface.
The cathode electrode may be arranged on the bottom surface of the accommodation groove, and the electron emission element may be arranged on the cathode electrode.
The electron emission element may be arranged to surround the cathode electrode as a whole.
A barrier layer may be provided on a lower side of the cathode electrode to prevent oxygen ions generated from the glass plate from being delivered to the cathode electrode or the electron emission element.
The barrier layer may be made of a silicon nitride (SiNx), silicon dioxide (SiO2), or bismuth (Bi)-based glass frit.
The barrier layer may have a thickness of 500 Å or more.
The barrier layer may exist only on the bottom surface of the accommodation groove.
The barrier layer may be extended to cover at least a part of each of the side surfaces of the accommodation groove.
A charge prevention film may be provided between the cathode electrode and the barrier layer to prevent the electrons generated from the electron emission element from being charged in the barrier layer.
The charge prevention film may be made of a chromium oxide (Cr2O3).
The charge prevention film may have a specific resistance of 105 Ω·cm or more.
The charge prevention film may have a secondary electron emission coefficient of one (1) or less on a driving condition of 300 V.
It is preferable that a thickness of the charge prevention film be equal to or larger than a thickness of the barrier layer.
The charge prevention film may exist only on the bottom surface of the accommodation groove.
The charge prevention film may be extended to cover at least a part of each of the side surfaces of the accommodation groove.
The gate electrode may have through-holes through which the electrons emitted from the electron emission elements pass.
The electron emission element may be made of carbon nano tube.
According to an aspect of another exemplary embodiment, a display apparatus including a field emission panel according to one aspect of an exemplary embodiment is provided. In particular, the display apparatus may be a liquid crystal display that the field emission panel uses as a backlight unit or a field emission display that the field emission panel uses as an image panel.
The above and other aspects, features and advantages of the present inventive concept will be more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:
Hereinafter, exemplary embodiments according to the present inventive concept are described in detail with reference to the accompanying drawings.
First,
A field emission panel 100 includes an upper plate 110, a lower plate 120, and a sealing member 130. The upper plate 110 and the lower plate 120 are arranged in parallel to each other, and are spaced apart from each other. The sealing member 130 is adhered to the upper plate 110 and the lower plate 120 by seal frits to seal a space between the upper plate 110 and the lower plate 120.
The upper plate 110 includes a first glass plate 111, an anode electrode 112, and a phosphor layer 113.
The first glass plate 111 is formed of a glass material which allows light transmission, and is in a rectangular plate shape. An anode electrode 112 and a phosphor layer 113 are sequentially layered on the inner surface of the first glass plate 111. The anode electrode 112 forms an electric field between the anode electrode 112 and a gate electrode 180 to be described later, and electrons that are emitted from electron emission elements 170 can be accelerated toward the upper plate 110 by the electric field. The accelerated electrons collide with the phosphor layer 113 and light (i.e., white light or a color image) is generated from the phosphor layer 113.
The lower plate 120 includes a second glass plate 130, barrier layers 140, charge prevention films 150, cathode electrodes 160, electron emission elements 170, and gate electrodes 180.
The second glass plate 130 is made of a glass material, and is in a rectangular plate shape. As illustrated in
As illustrated in
The barrier layer 140 is accommodated in the accommodation groove 132, and is arranged on the bottom surface 133 of the accommodation groove 132. Further, the barrier layer 140 is formed to be extended along the length direction (that is, the Z direction) of the accommodation groove 132. Accordingly, as seen from the Y direction, the barrier layer 140 is in a stripe shape.
In exemplary embodiments, the barrier layer 140 may be made of a silicon nitride (SiNx), silicon dioxide (SiO2), or bismuth (Bi)-based glass frit material, and may be formed by a process such as deposition (for example, sputtering) or screen printing. In some exemplary embodiments, the barrier layer 140 may have a thickness of 500A or more. The barrier layer 140 protects the cathode electrodes 160 and the electron emission elements 170 from oxygen ions O2− that are generated on the second glass plate 130 when the gate electrodes 180 are adhered to the upper surface 131 of the second glass plate 130 by anodic bonding.
The charge prevention film 150 is accommodated in the accommodation groove 132 of the second glass plate 130, and is formed on the barrier layer 140. In the same manner as the barrier layer 140, the charge prevention film 150 is formed to be extended along the length direction of the accommodation groove 132 (that is, the Z direction), and thus the charge prevention film 150 is in a stripe shape as seen from the Y direction.
In exemplary embodiments, charge prevention film 150 may be made of a chromium oxide (Cr2O3) material, and may be formed by a process such as, for example, deposition or screen printing. The charge prevention film 150 performs a function of preventing the electrons emitted from the electron emission elements 170 from being charged in the lower barrier layer 140. In some exemplary embodiments, the charge prevention film 150 may have a resistivity value of 105 Ω·cm or more. Since the electrons are prevented from being charged in the barrier layer 140 by the charge prevention film 150, arcing is prevented from occurring between the barrier layer 140 and the side surfaces 134 and 135 of the accommodation groove 132. In some exemplary embodiments, the thickness of the charge prevention film 150 is equal to or larger than the thickness of the barrier layer 140. In some exemplary embodiments, the charge prevention film may have a secondary electron emission coefficient of one (1) or less on a driving condition of 300V.
The barrier layer 140 and the charge prevention film 150 may exist only on the bottom surface 133 of the accommodation groove 132 as illustrated in
The cathode electrode 160 is accommodated in the accommodation groove 132 of the second glass plate 130, and is arranged on the charge prevention film 150. In the same manner as the barrier layer 140 and the charge prevention film 150, the cathode electrode 160 is formed to be extended along the length direction of the accommodation groove 132 (that is, Z direction), and thus the cathode electrode 160 is in a stripe shape as seen from the Y direction.
The cathode electrode 160 forms an electric field for the electron emission from the electron emission elements 170 between the cathode electrode 160 and the gate electrode 180. In exemplary embodiments, the cathode electrode 160 may be made of a silver (Ag) or aluminum (Al) material that has a relatively low resistance. Further, the cathode electrode 160 may be formed by a process such as, for example, deposition or screen printing, and in some embodiments, the cathode electrode 160 may have a thickness of 3000 Å or more. As illustrated in
The electron emission element 170 is accommodated in the accommodation groove 132 of the second glass plate 130, and is arranged on the cathode electrode 160 to surround the cathode electrode 160 as a whole. Since the electron emission element 170 surrounds the cathode electrode 160, the cathode electrode 160 is not exposed to the outside, and thus the arcing is prevented from occurring between the cathode electrode 160 and the side surfaces 134 and 135 of the accommodation groove 132.
The electron emission element 170 is formed to be extended along the length direction of the accommodation groove 132 (that is, the Z direction), and thus the electron emission element 170 is in a stripe shape as seen from the Y direction. Since the electron emission element 170 having the stripe shape is extended over the whole length of the accommodation groove 132, the quantity of accommodated electron emission elements per unit area of the field emission panel 100 can be increased. Accordingly, the field emission panel 100 generally has a longer lifespan than general field emission panels adopting electron emission elements having other shapes (such as, for example, a dot shape).
The electron emission element 170 is formed of a material that emits electrons when an electric field is formed around the electron emission element 170, that is, a field emission material. In this exemplary embodiment, the electron emission element 170 is formed of a carbon nano tube (CNT) material, and in other alternative exemplary embodiments, the electron emission element 170 may be formed of another field emission material, such as, for example, graphite, graphite nano fiber, diamond, diamond-like carbon (DLC), fullerene, or silicon nano-fiber. The electron emission element 170 may be formed by a process such as, for example, deposition or screen printing, and as illustrated in
Electrons are emitted from the electron emission element 170 by the electric field that is formed between the gate electrode 180 and the cathode electrode 160, and the emitted electrons are accelerated toward the upper plate 110 by the electric field that is formed between the anode electrode 112 and the gate electrode 180.
The gate electrode 180 is supported on the upper surface 131 of the second glass plate 130. The gate electrode 180 has a rectangular stripe shape. Further, the gate electrode 180 is extended along the direction (that is, the X direction) that is perpendicular to the length direction of the accommodation groove 132 (that is, the Z direction). Plural through-holes 181 are formed on the gate electrode 180, and the electrons emitted from the electron emission element 170 pass the accommodation groove 132 through the through-holes 181.
In some exemplary embodiments, the gate electrode 180 may be formed of a material having small resistance, such as, for example, silver (Ag) or aluminum (Al), and in this embodiment, the gate electrode 180 is formed of aluminum (Al). As described above, the gate electrode 180 forms the electric field for the electron emission together with the cathode electrode 160, and forms the electric field for accelerating the emitted electrons together with the anode electrode 112. In some exemplary embodiments, the gate electrode 180 may be adhered to the upper surface 131 of the second glass plate 130 by an adhesive material (for example, paste) or by anodic bonding.
Next,
First, as illustrated in
In comparison to the field emission panel in the related art, in which the insulating layer is formed on the second glass plate as a whole and the accommodation grooves are formed by exposing and etching the insulating layer, the field emission panel 100 according to this exemplary embodiment according to the present inventive concept, in which the accommodation grooves 132 are formed by directly etching the second glass plate 130, can reduce the numbers and cost of the fabricating processes.
Next, as illustrated in
In exemplary embodiments, the barrier layers 140 and the charge prevention films 150 may be formed, for example, by deposition (for example, sputtering) or screen printing. The screen printing process has a disadvantage in that gas may be generated in a process of firing paste, but also has an advantage in that its fabricating cost is reduced in comparison to the sputtering process.
Next, as illustrated in
In exemplary embodiments, the cathode electrodes 160 may be formed by a deposition process or by a screen printing process. In some exemplary embodiments, the cathode electrodes 160 may have a thickness of 3000 Å or more. Further, in some exemplary embodiments, the electron emission elements 170 may be formed by the screen printing process.
Last, as illustrated in
Presently, the anodic bonding method will be described. As illustrated in
Next,
A liquid crystal display 1 includes a housing 10, a liquid crystal panel 20, and a field emission panel 100 according to the above-described exemplary embodiments.
The housing 10 accommodates internal components of the display 1 that include the liquid crystal panel 20 and the field emission panel 100. The housing 10 includes a front housing 11 and a rear housing 12.
The liquid crystal panel 20 includes a color filter substrate 21 on which a color filter layer (not illustrated) is formed and a thin film transistor substrate 23 on which thin film transistors are formed, and a liquid crystal layer 22 fills in the space between the two substrates 21 and 23. Further, the color filter substrate 21 and the thin film transistor substrate 23 are sealed together by sealant 24.
The field emission panel 100 is arranged on the rear surface of the liquid crystal panel 20, and generates and irradiates white light toward the liquid crystal panel 20. In particular, the field emission panel 100 is used as a backlight unit. The white light that is irradiated toward the liquid crystal panel 20 passes through the liquid crystal layer 22 with its transmission rate adjusted, and then is converted into a color image by the color filter substrate 21.
Lastly,
A field emission display 2 includes a housing 30 and a field emission panel 100 according to the above-described embodiments.
The housing 30 accommodates internal components of the display 2 that include the field emission panel 100. The housing includes a front housing 31 and a rear housing 32.
The field emission panel 100 is used as a display panel that implements a color image without help of the backlight unit. Accordingly, the phosphor layer that is formed on the upper plate 110 of the field emission panel 100 includes a large number of phosphors that are arranged in a pattern that corresponds to a pattern of pixels so as to implement the color image.
While exemplary embodiments according to the present inventive concept have been shown and described, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention, as defined by the appended claims. The exemplary embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the present inventive concept is defined not by the detailed description of the exemplary embodiments, but by the appended claims, and all differences within the scope will be construed as being included in the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-0059166 | Jun 2011 | KR | national |
