This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from an application earlier filed in the Korean Intellectual Property Office on 31 Oct. 2005 and there duly assigned Serial No. 10-2005-0103511.
1. Field of the Invention
The present invention relates to a vacuum vessel, and in particular, to a vacuum vessel which has built-in spacers for spacing first and second substrates apart from each other by a predetermined distance, and an electron emission display device using the vacuum vessel.
2. Description of the Related Art
Generally, electron emission devices are classified into those using hot cathodes as an electron emission source and those using cold cathodes as the electron emission source. There are several types of cold cathode electron emission devices, including a field emitter array (FEA) type, a metal-insulator-metal (MIM) type, a metal-insulator-semiconductor (MIS) type, and a surface conduction emitter (SCE) type.
Although the electron emission devices are differentiated by specific structure depending upon the types thereof, they all basically have electron emission regions formed on a substrate, and driving electrodes for controlling the on/off and amount of electron emission from the electron emission regions. The electron emission devices can be used as an electron emission structure for a light source, such as a backlight or an image display device.
With the typical structure of the electron emission display device using the electron emission device, electron emission regions and driving electrodes are formed on a first substrate, and phosphor layers are formed on a surface of a second substrate facing the first substrate together with an anode electrode that keeps the phosphor layers at a high potential state. The first and the second substrates are sealed together at their peripheries using a sealing member, and the interior thereof is exhausted to form a vacuum vessel so that the electrons can be fluently emitted and migrated therein. A strong compression force is applied to the vacuum vessel due to the pressure difference between the interior and exterior thereof. A plurality of spacers are provided within the vacuum vessel to prevent vacuum vessel from breaking due to the compressive force. The spacers are attached to any one of the first the second substrates using an adhesive layer, and placed within the active area along with the electron emission regions and the phosphor layers.
With such a vacuum vessel, when spacers are fitted to one of the first and the second substrates and the interior thereof is evacuated, the spacers and the other of the first and the second substrates spaced apart from each other without an intervening adhesive layer are held tightly in contact with each other so that an impact is applied to the spacers, and the spacers are liable to be broken due to this impact.
The electron emission display device further has a non-active area located between the active area and the sealing member that does not serve to display an image. With the distribution of the stresses applied to the first and the second substrates after the exhausting, the stress applied to the non-active area is greater than the stress applied to the active area. This is because the structure for absorbing and withstanding the pressure of the two substrates is not present in the non-active area. Accordingly, cracks are likely to occur in the vacuum vessel due to the relatively large stress in the non-active area.
As spacers are attached to the substrate using an adhesive layer, the adhesion thereof with respect to the substrate is relatively weak. Consequently, some spacers are inclined or detached from the substrate during the exhausting process so that the pressure applied to the vacuum vessel is not uniformly distributed. As a result, the inclined spacers can block the paths of the electron beams, thus deteriorating the display characteristic. Moreover, as the wall type spacers have a high sectional aspect ratio and a long length, they are prone to twisting. For this reason, in a vacuum vessel using the wall type spacers, the spacers are likely to be twisted or inclined after the exhausting. Therefore, what is needed is an improved design for a vacuum vessel and an electron emission display device having the same that is better able to withstand and absorb the pressure caused by the vacuum vessel while overcoming the above problems.
It is therefore an object of the present invention to provide an improved design for a vacuum vessel and an improved design for an electron emission display employing the vacuum vessel.
It is also an object of the present invention to provide a vacuum vessel which inhibits the breakage of spacers due to the impact applied thereto during the exhausting process, and an electron emission display device using the vacuum vessel.
It is yet an object of the present invention to provide a vacuum vessel which reduces the stress applied to the non-active area of first and second substrates to thus inhibit the occurrence of cracks in the vacuum vessel.
It is still another object of the present invention to provide a vacuum vessel which heightens the adhesion of the spacers with respect to the first or the second substrate to thus prevent the spacers from being inclined or detached from the substrate, and an electron emission display device using the vacuum vessel.
These and other objects can be achieved by a vacuum vessel and an electron emission display device employing the same as follows.
According to one aspect of the present invention, there is provided a vacuum vessel that includes a first and a second substrate facing each other and extending across both an active area and a non-active area surrounding the active area, a sealing member arranged at peripheries of the first and the second substrates and adapted to maintain a vacuum between the two substrates, a plurality of wall type spacers arranged between the first and the second substrates while extending across the active area and a plurality of spacer supports arranged in the non-active area between the first and the second substrates, the plurality of spacer supports including a plurality of grooves adapted to receive the ends of respective ones of the plurality of wall type spacers, each spacer support having a height identical to or greater than a height of the plurality of wall type spacers.
Each of said plurality of spacer supports can include one of said plurality of grooves that is adapted to accommodate one end of one of said plurality of wall type spacers, each of said plurality of wall type spacers corresponding to two of said plurality of spacer supports, one for each end of said one of said plurality of wall type spacers. The vacuum vessel can include two spacer supports, each of said two spacer supports including a plurality of grooves adapted to accommodate ends of corresponding ones of said plurality of wall type spacers. A distance between a pair of the plurality of grooves that are arranged opposite to each other with one of said plurality of wall type spacers arranged between can be larger than a length of said one of said plurality of wall type spacers. A height difference between each of said plurality of wall type spacers and each of said plurality of spacer supports can be no more than 10% of a height of each of said plurality of wall type spacers. The vacuum vessel can also include an adhesive adapted to attach the plurality of spacer supports to one of the first and the second substrates.
According to another aspect of the present invention, there is provided and electron emission display device that includes a first and a second substrate facing each other and extending across both an active area and a non-active area surrounding the active area, an electron emission unit arranged within the active area and on the first substrate, a light emission unit arranged within the active area and on the second substrate, a sealing member arranged at peripheries of the first and the second substrates and adapted to maintain a vacuum between the two substrates, a plurality of wall type spacers arranged between the first and the second substrates while extending across the active area and a plurality of spacer supports arranged in the non-active area between the first and the second substrates, the plurality of spacer supports including a plurality of grooves adapted to receive the ends of respective ones of the plurality of wall type spacers, each spacer support having a height identical to or greater than a height of the plurality of wall type spacers.
Each of said plurality of spacer supports can include one of said plurality of grooves that is adapted to accommodate one end of one of said plurality of wall type spacers, each of said plurality of wall type spacers corresponding to two of said plurality of spacer supports, one for each end of said one of said plurality of wall type spacers. The electron emission display device can include two spacer supports, each of said two spacer supports including a plurality of grooves adapted to accommodate ends of corresponding ones of said plurality of wall type spacers. A distance between a pair of the plurality of grooves that are arranged opposite to each other with one of said plurality of wall type spacers arranged between can be larger than a length of said one of said plurality of wall type spacers. A height difference between each of said plurality of wall type spacers and each of said plurality of spacer supports can be no more than 10% of a height of each of said plurality of wall type spacers. The electron emission display device can also include an adhesive adapted to attach the plurality of spacer supports to one of the first and the second substrates. The electron emission unit can include a plurality of electron emission regions adapted to emit electrons and a driving electrode adapted to control the emission of electrons from the plurality of electron emission regions, the light emission unit can include a plurality of phosphor layers and an anode electrode adapted to apply a high potential to the plurality of phosphor layers.
According to still yet another aspect of the present invention, there is provided an electron emission display device that includes a first substrate spaced apart from and facing a second substrate and spanning an active area and a non-active area surrounding the active area, an electron emission unit arranged on the first substrate within the active area, a light emission unit arranged on the second substrate within the active area, a sealing member arranged at peripheries of the first and the second substrates and in the non-active area, the sealing member being adapted to maintain a vacuum between the first and the second substrates, a plurality of wall type spacers arranged between the first and the second substrates and extending across the active area, the plurality of wall type spacers being adapted to keep said first substrate spaced apart from the second substrate and to absorb and withstand a pressure in the active area acting on the first and the second substrates due to said vacuum between the first and the second substrates and a plurality of spacer supports arranged within the non-active area between the first and the second substrates at ends of ones of the plurality of wall type spacers, the plurality of spacer supports being adapted to keep said first substrate spaced apart from said second substrate and to absorb and withstand a pressure in the non active area acting on the first and the second substrates due to said vacuum between the first and the second substrates.
Each of the plurality of spacer supports can be wider than each of the plurality of wall type spacers. Each of the plurality of spacer supports can be taller than each of the plurality of wall type spacers by no more than 10% of a height of each of the plurality of wall type spacers. The plurality of wall type spacers can have a stripe pattern. Each of the plurality of spacer supports can include one groove adapted to receive one end of one of said plurality of wall type spacers. Each of the plurality of spacer supports can include a plurality of grooves adapted to receive one end of a corresponding plurality of wall type spacers.
A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:
Turning now to
An electron emission unit is provided on the surface of the first substrate 2 that faces the second substrate 4 and serves to emit electrons toward the second substrate 4. A light emission unit is provided on the surface of the second substrate 4 that faces the first substrate 2 and serves to emit visible rays when impinged by the electrons emitted from the electron emission unit, thus producing the visible image for the display.
Turning now to
The electron emission regions 14 are made out of a material that can emit electrons upon application of an electric field under a vacuum atmosphere. Examples of such materials that can be used in the electron emission regions 14 are carbonaceous material and nanometer-sized material. Specific examples of materials that can be used in the electron emission regions 14 include carbon nanotubes, graphite, graphite nanofiber, diamond, diamond-like carbon, C60, silicon nanowire or a combination thereof. The cathode electrodes 8 and the gate electrodes 10 function as driving electrodes for controlling the emission of the electron emission regions 14.
Although the gate electrodes 10 are shown in
Reverting back to the scenario where the gate electrodes 10 are formed over the cathode electrodes 8, a focusing electrode 16 is formed on top of the gate electrodes 10 and on top of the first insulating layer 12. This focusing electrode 16 serves as the third electrode. A second insulating layer 18 is placed under the focusing electrode 16 to insulate the focusing electrode 16 from the gate electrodes 10. Openings are formed in the second insulating layer 18 and in the focusing electrode 16 to allow electron beams to pass.
In a variation to the above, the anode electrode 24 can instead be made out of a transparent conductive material such as indium tin oxide (ITO). When the anode electrode 24 is transparent, the anode electrode is situated on a side of phosphor layers 20 and the black layers 22 facing the second substrate 4. Further, the anode electrode 24 can be patterned to have a plurality of separate portions. Again alternatively, the anode electrode 24 can be formed as a double-layered structure having a transparent conductive material-based layer and a metallic material-based layer.
The structures of the electron emission unit 26 and the light emission unit 28 are in no way limited to that illustrated or described. Furthermore, the electron emission display device according to the present invention is in no way limited to the FEA type device, but can be another type, such as an SCE type, an MIM type or an MIS type and still be within the scope of the present invention.
The area of the first and the second substrates 2 and 4 where the electron emission unit 26 and the light emission unit 28 are located (i.e., the area where the image is produced) is referred to the active area 30. The non-active area 32 is located external to the active area 30, between the active area 30 and the sealing member 6. An exhaust port, electrode wires and a getter (not shown) are provided in the non-active area 32.
With the above-described structure, a plurality of wall type spacers 34 are arranged between the first and the second substrates 2 and 4 while extending across the active area 30. Spacer supports 36 are further arranged at each end of each of the wall type spacers 34. The spacer supports 36 are located within the non-active area 32 and contain grooves 38 that receive ends of the spacers 34.
As illustrated in
As illustrated in
The height of the spacer supports 36 can be the same as the height of the spacers 34 or can be slightly taller than the spacers 34. The spacer supports 36 serve to absorb and withstand the pressure applied to the first and the second substrates 2 and 4 in the non-active area 32. The case where the height of the spacer supports 36 are the same as that of the spacers 34 is illustrated in
When the height of the spacer supports 36′ is established to be larger than that of the spacers 34, the spacer supports 36′ bear the brunt of the pressure applied to the first and the second substrates 2 and 4 in the non-active area 32 while the spacers 34 bear the brunt of the pressure applied to the first and the second substrates 2 and 4 in the active area 30, thus preventing excessive stress from occurring in the non-active area 32. Accordingly, even after the exhausting process is completed, the first and the second substrates 2 and 4 remain in a stable state, and the stress difference between the active area 30 and the non-active area 32 is minimized. Furthermore, when the height of the spacer supports 36′ are larger than that of the spacers 34 as in
Turning now to
As shown in
As the first impact is applied to the spacer supports 36′ rather than to the spacers 34 during the exhausting process of the vacuum vessel, the spacer supports 36′ reduce the impact applied to the spacers 34 so that the spacers 34 are effectively prevented from being broken or inclined due to the impact applied thereto during the exhausting process. The height difference between the spacer supports 36′ and the spacers 34 is preferably 10% or less of the height of the spacers 34, so that an occurrence of a crack occurrence in the second substrate 4 due to the height difference between the spacer supports 36′ and the spacers 34 can be avoided.
Meanwhile, compared to the spacers 34, since the spacer supports 36′ are located in the non-active area 32, the spacer supports 36′ can be designed to have a larger width than the spacers 34. Preferably, the spacer supports 36′ are formed as wide as possible provided that the spacer supports 36′ do not result in an increase of weight for the vacuum vessel and for the electron emission display device.
Turning now to
Turning now to
One additional design consideration of the present invention pertains to the distance between opposite support spacers. As shown in
The spacers 34 can be made out of any of ceramic, glass, glass-ceramic mixture, ceramic tape, ceramic sheet, or ceramic reinforced glass. The spacer supports 36, 36′ and 36″ can be made out of a material having a thermal expansion coefficient identical to or close to that of the spacers 34. The support spacers 36, 36′ and 36″ can thus be made out of the same material as the spacers 34.
Although exemplary embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concept herein taught which may appear to those skilled in the art will still fall within the spirit and scope of the present invention, as defined in the appended claims.
Number | Date | Country | Kind |
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10-2005-0103511 | Oct 2005 | KR | national |
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