Patent Publication Number: US-2006012301-A1

Title: Vacuum getter chamber

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates in general to a structure of a vacuum getter chamber, and more particularly, to a vacuum getter chamber using a new getter installed in a vacuum getter structure, so as to provide a sufficient vacuum level during vacuuming process. Thereby, the electron beam generated from the cathode electrode can impinge phosphor of the anode electrode within a cavity to generate light.  
      The conventional vacuum display such as the vacuum fluorescent display (VFD) as disclosed in U.S. Pat. No. 5,635,795, cathode ray tube (CRT), field-emission display (FED) as disclosed in U.S. Pat. No. 6,084,344 provides a vacuum cathode in which a free path is formed allowing an electron beam generated from a cathode electrode to propagate, so as to impinge the phosphor of an anode electrode to generate light.  
      The vacuum level of the above vacuum display is typically kept at 10 −5  to 10 −7  torr. Although the vacuum level of cavity can be maintained by packaging the cavity, leakage is still unavoidable. The source of the leakage includes the package material, the internal material of the vacuum device such as the coating of the cathode and anode electrodes, electron-emission source, and phosphor, for example. The leakage source during operation includes the heat of phosphor excited by the electron beam. Such type of leakage may even poison the material of the electron-emission source or the phosphor to affect the luminescent efficiency.  
      Therefore, to maintain the vacuum level of the cavity, a getter box has been installed in the vacuum chamber, and a getter is disposed in the vacuum chamber. The getter is normally composed of barium compound. By activation process, pure barium can be released to attach to a large area of the getter chamber, such that the leakage can be absorbed by the pure barium effectively.  
      The activation process for barium has to be performed at a temperature higher than 700° C., and the barium has to be disposed at a specific area. Therefore, to avoid affecting or activating other members such as the electron-emission source or the phosphor, the barium is located at a place remote to the effective display area. As a result, the ineffective area of the display is increased; and consequently, the available display area is reduced.  
     BRIEF SUMMARY OF THE INVENTION  
      Brand new vacuum getter structure and getter are provided to provide gas guide, so as to reduce vacuuming time, cost and the total thickness. Therefore, the overall thickness of the display can be minimized, and the insufficient vacuum level at the corner of the flat-panel structure can also be resolved. Further, the vacuum getter structure can be used as a reinforcing rib of the display, such that the strength of the cathode panel structure is increased. This is advantageous in fabricating a large-area flat panel display. Further, the glass cracking problem caused by local high temperature during the tip-off process can be overcome. In addition, the locations for disposing the getter are reduced to increase vacuum level. As the activation temperature of the getter is relatively lower, the internal materials of the display will not be affected by the activation process. Therefore, the ineffective display area is reduced.  
      Accordingly, a flat panel display provided by the present invention includes a display member, a getter and a chamber. The display member has an anode plate and a cathode plate forming a chamber therebetween, wherein the cathode plate includes at least two apertures extending therethough. The getter is distributed on a first surface of the cathode plate between the apertures. Moreover, the chamber member is mounted on the cathode plate to form a getter chamber, the chamber member covering the apertures and the getter therein.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above objects and advantages of the present invention will be become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:  
       FIG. 1  is perspective view of a vacuum getter structure;  
       FIG. 2  is a side view of the vacuum getter structure;  
       FIG. 3  shows the application of the vacuum getter structure to a panel of a flat panel display;  
       FIG. 4  illustrates assembly of the vacuum getter structure and the panel of the flat panel display; and  
       FIG. 5  shows a cross sectional view of  FIG. 4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to  FIGS. 1 and 2 , as provided, the vacuum getter structure is applied to a panel of a flat panel display such as a field-emission display to provide is a vacuum getter structure, in which a free path is established after vacuuming process. Therefore, an electron beam generated by the cathode electrode of the panel can propagate along the free path to impinge the phosphor of the anode electrode.  
      The vacuum getter chamber  1  is formed by thermal pressing a flat panel glass. Alternatively, glass paste ejection is used to form a curved stripe structure or a flat-panel structure. The internal surface of the vacuum getter chamber  1  is recessed upwardly to form a getter chamber  11 . The vacuum getter chamber  1  has a hole  12  in communication with the getter chamber  11 .  
      The space encompassed by the getter chamber  11  and the cathode plate (not shown) has a vertical depth, preferably but optionally, larger than 2.5 millimeters to provide good gas conduction coefficient.  
      Referring to FIGS.  3  to  5 , the vacuum getter structure  1  and the panel  2  are connected together, and vacuum process is performed. A plurality of apertures  31  is formed on the cathode plate  3  of the panel  2 . The apertures  31  extend through the cathode plate  3  to form channels communicating the getter chamber  11  and a space between the cathode plate  3  and the anode plate  4 . The getter  6  is distributed between the apertures  31  and  31  along the vacuum getter structure  1 . Preferably but optionally, the getter  6  is discretely arranged along the getter chamber  11 . In this embodiment, barium alloy St22 provided by SAES is used as the getter  6  because its activation temperature is about 450° C. In addition, the activated barium alloy will not generate large-area barium powders attached to the getter chamber  11 . The configuration of the barium alloy can be designed according to the getter chamber or other gas collecting/absorbing metal.  
      The getter  6  is attached to the cathode plate  3  between the holes  31  and  31 ′ by glass glue. The vacuum getter structure  1  is then attached to the cathode plate  3  to cover the apertures  31  and the getter  6 . A tube member  13  is installed at the hole  12  of the vacuum getter structure  1  to connect the getter chamber  11  to an external vacuum device. Thereby, a chemical vacuum state can be formed within the vacuum getter structure  1 , and a free path is formed between the cathode plate  3  and the anode plate  4 , such that an electron beam generated by the cathode plate  3  can propagate along the free path to impinge the phosphor of the anode plate  4  to generate light.  
      The above embodiment of vacuum getter structure has at least the following advantages:  
      1. The curved vacuum getter structure  1  provides gas guide to reduce vacuuming time, so as to reduce the cost.  
      2. The design of the getter chamber  11  minimizes the overall thickness of the flat panel display.  
      3. The elongate large-area gas collecting chamber resolves the problem of insufficient vacuum level at the corners.  
      4. The vacuum getter structure  1  is also functioning as structurally reinforcing rib, such that the elongate large-area gas collecting chamber enhances the strength of the cathode plate. Therefore, the glass cracking problem caused by local high temperature during tip-off process is overcome.  
      5. The function matches the long, thin type getter. The number of locations to distribute the getter is reduced. Therefore, the vacuum level can be enhanced. Further, as the thickness of the getter chamber is not limited to 2.5 mm, the thin and light requirement of the flat panel display will not be affected.  
      6. The getter is only disposed along the side of the cathode plate  3 , and the activation temperature is low, such that the internal material will not be affected, and the available display area is increased.  
      While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those of ordinary skill in the art the various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.