Abstract:
A vacuum container includes a getter filled with a gettering material for maintaining a vacuum condition, and includes a getter support which includes a control plate member, a support leg and a holder. The getter support is arranged in the spreading direction of the getter material in order to limit the directions of the spreading of the getter material. This structure reduces the number of relevant components, simplifies the procedure of fabrication and maintains the degree of vacuum.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a vacuum container or vacuum envelope and a display device where a vacuum state is maintained by spreading getter materials in a vacuum casing such as a vacuum envelope or enclosure. Characteristic examples of such a display device are a vacuum-type video display with electron emitter elements such as a field emission display (referred to as “FED” hereinafter), a vacuum fluorescent display (VFD), and a field emission (FE) sensor. 
   2. Description of the Prior Art 
   As liquid crystal displays have commonly been used as flat-panel displays, they may be replaced by FEDs. 
     FIG. 11  is a cross sectional view of a conventional FED with electron emitter elements. The FED has a vacuum envelope  18  composed of an electron emission substrate  25  and a light emitter substrate  26  where the two substrates  25  and  26  are air-tightly joined to each other by a spacer  3 . The electron emission substrate  25  is provided thereon with a pattern of wiring layer  12 , electron emitter elements  13 , a pattern of insulating layer  14 , and lead electrodes  15 , and the light emitter substrate  26  is provided thereon with an opposite pattern of anode layers  16  and a pattern of fluorescent layers  17 . A getter chamber  20  of a box-like shape is provided on the back side of the electron emitter substrate  25  of the vacuum envelope  18 . The getter chamber  20  is communicated via an exhaust aperture  23  with the interior of the vacuum envelope  18  and the getter chamber  20  includes a getter  4  held under pressure by a spring  21 . 
   The getter  4 , as shown in  FIG. 12 , comprises a getter material  6  filled in an annular, nickel plated metallic frame  5  for gettering action. The getter material  6  may be a powder alloy of, for example, BaAl 4 . In process, the air in the vacuum envelope  18  and the getter chamber  20  is discharged out through from the exhaust aperture  24  of the getter chamber  20  and an exhaust tube  22 . Then, when the exhaust tube  22  has been sealed, the vacuum envelope  18  and the getter chamber  20  are turned to and maintained in a vacuum state. As the getter  4  is heated by means of such as a high-frequency induction heating method (not shown), the getter material  6  is vapor deposited on an inner surface portion of the getter chamber  20  to form a getter film  19 . The vacuum state in the vacuum envelope  18  and the getter chamber  20  is maintained in a higher degree of vacuum, so that the emission of electrons from the electron emitter elements  13  can stably be carried out. 
   It is essential for the display device having the above described arrangement to maintain the vacuum state to such a higher degree of vacuum in the vacuum envelope that electrons can steadily be emitted at high efficiency and lower currents. For increasing the vacuum state to a high degree of vacuum, the effect of the getter absorbing gases is utilized. However, since the getter is directly supported by the spring  21  in the vacuum envelope, the getter material can hardly be controlled for spreading while being heated and vaporized by high-frequency heating. As a result, undesired conductive regions will be developed in the vacuum envelope. For eliminating the drawback, the getter chamber is located beneath the vacuum envelope but such a location thus may interrupt the flat-panel configuration of the display device. Note here that the undesired conductive regions are developed by portions of the getter material spread and deposited on a display area thus to establish undesired connection between the electrodes which are not to be electrically connected. 
   SUMMARY OF THE INVENTION 
   The present invention is developed for solving the foregoing drawback and its object is to provide a vacuum container such as a vacuum envelope and a display device where a getter is arranged in the vacuum envelope so as to reduce the number of relevant components, simplify the process of fabrication, inhibit declination in the degree of vacuum, and suppress the spreading of getter flushes in directions. 
   For solving the foregoing drawback, there is provided a vacuum container according to claim  1  of the present invention which has a getter with a getter material provided therein for maintaining the degree of vacuum, comprising: a getter support consisting mainly of a control plate member, a support leg, and a holder and arranged at the spreading direction of the getter material for controlling the spreading of the getter material in desired directions. 
   The vacuum container according to claim  1  of the present invention can control the spreading of the getter material in directions. This allows the getter to be disposed within the vacuum container. Also, as a getter chamber required in the prior art is eliminated, the vacuum container can be shaped flat. 
   The vacuum container according to claim  1  of the present invention may be modified, as defined in claim  2 , wherein while the control plate member has a hollow space, the holder holds the getter with its spreading side located at an opening of the hollow space of the control plate member and the control plate member is fixedly anchored by the support leg in the vacuum container. 
   The vacuum container according to claim  2  of the present invention permits at least a primary portion of the spreading of the getter material of the getter to be controlled by the getter support during the evaporation of the getter material and also a secondary portion of the spreading to be deposited on the inner wall of the vacuum container. 
   The vacuum container according to claim  2  of the present invention may be modified, as defined in claim  3 , wherein while the getter material released from the getter is reflected on the control plate member and flied out from the control plate member, the control plate member is arranged for permitting the getter material to reflect at least two times on the control plate member. 
   The vacuum container according to claim  3  of the present invention permits at least the secondary portion of the spreading of the getter material of the getter to be controlled by the getter support during the evaporation of the getter material and also a tertiary portion of the spreading, if any, to be deposited on the inner wall of the vacuum container. 
   The vacuum container according to claim  1  of the present invention may be modified, as defined in claim  4 , wherein when the control plate member is a combination of a conical shape and a cylindrical shape with the hollow space so that its longitudinal cross section includes the vertex and the center of the base of the conical shape, assuming that the bottom of the cylindrical shape is a and the side of the cylindrical shape is b, the angle at the vertex of the control plate member is equal to or smaller than two times a reverse tangent tan −1 (b/a) of the angle defined by the two sides a and b and the spreading side of the getter is held by the holder to stay within an isosceles triangle of which the base is equivalent to the base of the cylindrical shape and the angle at each end of the base is expressed by tan −1 (b/a) 
   The vacuum container according to claim  4  of the present invention permits at least a secondary portion of the spreading of the getter material of the getter to be controlled by the getter support during the evaporation of the getter material and also a tertiary portion of the spreading, if any, to be deposited on the inner wall of the vacuum container. 
   The vacuum container according to claim  2  of the present invention may be modified, as defined in claim  5 , wherein the control plate member has an opening of the hollow space arranged to have a polygonal or arcuate shape in the cross section. 
   The vacuum container according to claim  5  of the present invention can fabricate the control plate member with ease and enhance the effect of getter pumping thus maintaining a higher level of vacuum. 
   The vacuum container according to claim  2  of the present invention may be modified, as defined in claim  6 , wherein the getter support is made of at least a metallic material. 
   The vacuum container according to claim  6  of the present invention can endure the effect of high-frequency heating during the gettering. 
   The vacuum container according to claim  1  of the present invention may be modified, as defined in claim  7 , wherein two or more of the getter supports are provided. 
   The vacuum container according to claim  7  of the present invention can maintain a higher level of vacuum therein and may be increased in the dimensions. 
   The vacuum container according to claim  1  of the present invention may be modified, as defined in claim  8 , wherein the support leg holds two or more of the control plate member. 
   The vacuum container according to claim  8  of the present invention can reduce the number of relevant components. 
   There is provided a display device according to claim  9  of the present invention which has a getter with a getter material provided therein for maintaining the degree of vacuum, comprising: a getter support including a control plate member, a support leg, and a holder and the getter support is arranged at the spreading direction of the getter material for controlling the spreading of the getter material in desired directions. 
   The display device according to claim  9  of the present invention permits the spreading of the getter material to be controlled in directions. This allows the getter to be disposed in the display device. As a getter chamber required in the prior art is eliminated, the display can be shaped flat. 
   The display device according to claim  9  may further comprises, as defined in claim  10  of the present invention: an electron emitter substrate having at least a pattern of wiring layer, electron emitter elements, a pattern of insulating layer, and lead electrode all provided on a first glass substrate; a light emitter substrate having at least anodes and fluorescent layers all provided on a second glass substrate; and a spacer provided between the electron emitter substrate and the light emitter substrate so that the electron emitter substrate and the light emitter substrate can be spaced by a predetermined distance from each other. 
   The display device according to claim  10  of the present invention permits the spreading of the getter material to be controlled in directions. This allows the getter to be disposed in the display device. As a getter chamber required in the prior art is eliminated, the display can be shaped flat. 
   The display device according to claim  9  may be modified, as defined in claim  11  of the present invention, wherein the control plate member has a hollow space, the holder holds the getter with its spreading side located at an opening of the hollow space of the control plate member, and the control plate member is fixedly anchored by the support leg in the display device. 
   The display device according to claim  11  of the present invention permits at least a primary portion of the spreading of the getter material of the getter with the getter support to be controlled by the getter support during the evaporation of the getter material and also a secondary portion of the spreading to be deposited on the inner wall of the display device, hence inhibiting the display area from receiving the spreading and developing unwanted electrical conduction. 
   The display device according to claim  11  may be modified, as defined in claim  12  of the present invention, wherein while the getter material released from the getter is reflected on the control plate member and flied out from the control plate member, the control plate member is arranged for permitting the getter material to reflect at least two times on the control plate member. 
   The display device according to claim  12  of the present invention permits at least a secondary portion of the spreading of the getter material of the getter to be controlled by the getter support during the evaporation of the getter material and also a tertiary portion of the spreading, if any, to be deposited on the inner wall of the display device. 
   The display device according to claim  9  may be modified, as defined in claim  13  of the present invention, wherein when the controlling member is a combination of a conical shape and a cylindrical shape with the hollow space so that its longitudinal cross section includes the vertex and the center of the base of the conical shape, assuming that the bottom of the cylindrical shape is a and the side of the cylindrical shape is b, the angle at the vertex of the control plate member is equal to or smaller than two times a reverse tangent tan −1 (b/a) of the angle defined by the two sides a and b and the spreading side of the getter is held by the holder to stay within an isosceles triangle of which the base is equivalent to the base of the cylindrical shape and the angle at each end of the base is expressed by tan −1 (b/a). 
   The display device according to claim  13  of the present invention permits at least the secondary portion of the spreading of the getter material of the getter to be controlled by the getter support during the evaporation of the getter material and also a tertiary portion of the spreading, if any, to be deposited on the inner wall of the display device. 
   The display device according to claim  11  of the present invention may be modified, as defined in claim  14  of the present invention, wherein the control plate member has an opening of the hollow space arranged to have a polygonal or arcuate shape in the cross section. 
   The display device according to claim  14  of the present invention can fabricate the control plate member with ease thus to favorably provide the effect of getter pumping and maintain a higher level of vacuum. 
   The display device according to claim  11  may be modified, as defined in claim  15  of the present invention, wherein the getter support is provided between the electron emitter substrate and the light emitter substrate and the opening of the control plate member is at least not smaller than the size of the getter. 
   The display device according to claim  15  of the present invention needs not to change its thickness for providing the getter support. This allows the display device to be thinned in the size. 
   The display device according to claim  11  may be modified, as defined in claim  16  of the present invention, wherein the getter support is made of at least a metallic material. 
   The display device according to claim  16  of the present invention can endure the effect of high-frequency heating during the gettering. 
   The display device according to claim  9  may be modified, as defined in claim  17  of the present invention, wherein two or more of the getter supports are provided. 
   The display device according to claim  17  of the present invention can maintain a higher level of vacuum and be increased in the size. 
   The display device according to claim  9  may be modified, as defined in claim  18  of the present invention, wherein the support leg holds two or more of the control plate members. 
   The display device according to claim  18  of the present invention can reduced the number of relevant components. 
   The display device according to claim  9  may be modified, as defined in claim  19  of the present invention, wherein the getter support is located on the outer side of a display area of the display device. 
   The display device according to claim  19  of the present invention can maintain the vacuum state to a uniform level, thus inhibiting uniformity errors in the display. 
   The display device according to claim  9  may be modified, as defined in claim  20  of the present invention, wherein the getter supports are provided opposite to each other so as to sandwich the display area therebetween. 
   The display device according to claim  20  of the present invention can maintain the vacuum state to a uniform level, thus inhibiting uniformity errors in the display. 
   The display device according to claim  10  may be modified, as defined in claim  21  of the present invention, wherein the side of the getter where the getter material is exposed faces the electron emitter elements and the getter support is provided between the getter and the electron emitter elements so that spreading particles of the getter material are collided at least once with the control plate member or reflected at least once on the control plate member. 
   The display device according to claim  21  of the present invention permits at least a primary portion of the spreading of the getter material of the getter to be controlled by the getter support during the evaporation of the getter material and also a secondary portion of the spreading to be deposited on the inner wall of the display device, hence inhibiting the display area from receiving the spreading and developing unwanted electrical conduction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross sectional view of a display device according to Embodiment 1 of the present invention; 
       FIGS. 2A and 2B  are cross sectional views of an electron emitter substrate; 
       FIGS. 3A and 3B  are cross sectional views of the display device according to Embodiment 1 of the present invention; 
       FIGS. 4A and 4B  are schematic views of a control plate member in Embodiment 2 of the present invention; 
       FIG. 5  is a cross sectional view of a display device according to Embodiment 2 of the present invention; 
       FIGS. 6A ,  6 B and  6 C are longitudinally cross sectional views of the controlling member showing the vertex and the center of a base of a conical shape; 
       FIG. 7  is an explanatory view showing an arrangement of getter supports in Embodiment 2 of the present invention; 
       FIGS. 8A ,  8 B, and  8 C are views showing a procedure of fabricating the getter support; 
       FIGS. 9A ,  9 B, and  9 C are views showing another procedure of fabricating the getter support; 
       FIGS. 10A ,  10 B, and  10 C are views showing a further procedure of fabricating the getter support; 
       FIG. 11  is a cross sectional view of a conventional vacuum container; and 
       FIG. 12  illustrates a plan view and a cross sectional view of a evaporation-type getter. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   (Embodiment 1) 
   Embodiment 1 of the present invention will be described referring to  FIGS. 1 ,  2 ,  3 , and  12 . 
     FIG. 1  is a cross sectional view of a display device according to Embodiment 1 of the present invention,  FIGS. 2A and 2B  are cross sectional views of an electron emitter substrate and light emitter substrate  26 , respectively, and  FIGS. 3A and 3B  show the display device including a getter support according to Embodiment 1 of the present invention. 
   In  FIGS. 1 and 3A , the getter support  7  is illustrated in a perspective manner, not a cross sectional manner, for clarifying its interior. The cross section of the getter support  7  is shown in FIG.  3 B. 
   As shown in  FIGS. 1 ,  2 , and  3 , the display device comprises a spacer  3 , a getter  4 , the getter support  7 , electron emitter substrate  25 , and light emitter substrate  26 . The electron emitter substrate  25  has a first glass substrate  1  arranged on which a pattern of wiring layer  12 , electron emitter elements  13 , a pattern of insulating layers  14 , and lead electrodes  15  are provided in a sequence. The light emitter substrate  26  has a second glass substrate  2  on which transparent anodes  16  made of e.g. ITO (indium tin oxide) and a pattern of fluorescent layer  17  made mainly of e.g. ZnO: Zn materials are sequentially formed. The spacer  3  is arranged of a rectangular frame and assembled together and located between the electron emitter substrate  25  and the light emitter substrate  26  opposite to each other, thus forming a vacuum envelope  18 . The getter support  7  comprises a support leg  8 , a control plate member  9 , and a holder  10 . The getter support  7  is provided for controlling the direction of spreading of the getter material  6 . 
   As described with reference to  FIG. 12 , the getter  4  has a structure in which a getter material  6  is filled in a nickel plated, annular metallic frame  5  for gettering action. The getter  4  has two sides, one for a getter spreading side where the getter material  6  is exposed and the other of a back side where the getter material  6  is not exposed. The getter material  6  may be a powder alloy of, for example, BaAl 4 . After air in the vacuum envelope  18  has been discharged from an exhaust aperture (not shown) provided in the vacuum envelope  18 , the vacuum envelope  18  is sealed off with its exhaust aperture closed and thus remains in a vacuum state. Then, the getter material  6  is heated and vaporized by means of high-frequency induction heating (not shown). This causes the getter material  6  to be deposited as a getter layer on the inner wall of the vacuum envelope  18 . Accordingly, as the vacuum state in the vacuum envelope  18  is enhanced, electrons can be emitted in stable from the electron emitter elements  13  in the display device. 
     FIG. 2A  is a cross sectional view of the electron emitter substrate  25 . For example, the wiring layer  12  of a highly conductive material such as Au is patterned on the first glass substrate  1  made of a uniform thickness of 1 to 2 mm, of a light transmissive soda lime glass material and the lead electrodes  15  made of Cr are provided on an insulating layer  14  formed on the wiring layer  12 . The soda lime glass material has a softening point of substantially 700° C. The electron emitter elements  13  are made of, for example, molybdenum (Mo), which acts as cool cathodes each having a conical shape called spindle type and having a uniform height in a degree of 1 micrometer. These may generally be deposited by a thin film forming manner such as sputtering. The lead electrode  15  is partially removed by, e.g., ion etching, to provide substantially oval apertures  15   a  of 1 to 2 μm in diameter through which the electron emitter elements  13  are exposed. The insulating layer  14  made of silicon dioxide (SiO 2 ) is deposited generally over the upper surface of the wiring layer  12  except for the portions of forming the electron emitter elements  13 . The lead electrodes  15  are thus located on the insulating layers  14 . The wiring layer  12  and the lead electrodes  15  are electrically insulated from each other by the insulating layer  14 . 
     FIG. 2B  is a cross sectional view of the light emitter substrate  26 . This substrate  26  like the electron emitter substrate  25  has a second glass substrate having a uniform thickness of 1 to 2 mm, made of a light transmissive soda lime glass material and arranged over which the transparent anodes  16  are provided. The fluorescent layers  17  are deposited on the surface of the anodes  16 . The soda lime glass material has a softening point of substantially 700° C. The anode  16  is made of ITO (indium tin oxide). The anode  16  is deposited to a thickness of 1 μm by a thin film forming manner such as sputtering and has a sheet resistance of not higher than 10 Ω/□ thus being high in the conductivity. The pattern of fluorescent layers  17  comprises of pixel segments, each pixel segment including three primary colors R (red), G (green), and B (blue). The fluorescent layer  17  is made of a material such as ZnO:Zn or ZnS:Ag which can emit visible light upon excited by electrons and may be deposited to a thickness of 5 μm by a manner such as thick-film screen printing. 
   As explained briefly, the electron emitter element  13  includes an emitter and a gate arranged wherein when the gate develops an electric field, the emitter impinges electrons towards the fluorescent layer  17  of the anode  16  which acts as a collector. 
     FIG. 3A  shows a cross sectional view of the electron emitter substrate  25  having the getter support  7  provided thereon. The getter  4  is supported by the getter support  7  at a predetermined location on the electron emitter substrate  25  fabricated as shown in FIG.  2 A. 
   The getter support  7  includes the control plate member  9  of a conical shape of which the diameter of the bottom is at least greater than the outer diameter of the getter  4 . The getter  4  is mounted to the holder  10  so that the getter material  6  is deposited on the inner side of the control plate member  9 . The support leg  8  is located for holding the control plate member  9  in the vacuum envelope  18 . The control plate member  9  is not limited to the conical shape and may have a pyramid shape with a polygonal base such as a triangular pyramid. 
     FIG. 3B  is a cross sectional view of a portion of an FED using the getter support  7 . As apparent from  FIG. 3B , the display device comprises the first glass substrate  1 , second glass substrate  2 , spacer  3 , getter  4 , getter support  7 , and a display area  27 . The display area  27  includes the wiring layer  12 , electron emitter elements  13 , insulating layers  14  and lead electrodes  15  as shown in FIG.  2 A. in the case where the getter support  7  is used in the FED, when the getter material  6  is evaporated to be spread, at least a primary portion of the spread getter material  6  can be controlled by the getter support  7 . A secondary portion of the spread getter material can also be directed and deposited on the inner wall of the vacuum envelope  18  including the spacer  3 . The evaporated getter material  6  can be prevented from spreading to the display area  27 , which thus remains free from undesired electrical conduction. It is assumed that an n-th dimension (n&gt;0) of the spreading of the getter material  6  means the getter particles after reflected (n−1) times on the control plate member  9  or the inner wall of the vacuum envelope  18 . 
   It is also desired that the spreading side of the getter  4  where the getter material  6  is exposed faces towards the display area  27  while the line between the center of the getter  4  and the vertex of the conical shape of the control plate member  9  in the getter support  7  extends across the display area  27 . The positional relationship between the getter  4  and the getter support  7  permits the display area  27  to remain free from undesired electrical conduction. 
   As described above, the vacuum envelope  18  of this embodiment can be used as a vacuum container or namely a housing of a display device. Also, the display device may be an image display device for displaying images. 
   (Embodiment 2) 
   Embodiment 2 of the present invention will be described referring to the relevant drawings. A getter support having a control plate member which is different from that of Embodiment 1 is explained referring to  FIGS. 4 ,  5 , and  6 . 
     FIGS. 4A and 4B  show a schematic construction of the control plate member in Embodiment 2 of the present invention,  FIG. 5  is a cross sectional view of the display device of Embodiment 2, and  FIGS. 6A ,  6 B and  6 C show a construction of the control plate member  9  illustrating the vertex of its conical shape and the center of its base. 
     FIG. 4A  is a perspective view of the control plate member  9 . As shown, the control plate member  9  comprises a conical portion and a cylindrical portion having a hollow space  9   a .  FIG. 4B  is a cross sectional view of the control plate member  9  showing the vertex of the conical region and the center of base region. As shown, the cylindrical portion has a diameter “a” and a height “b”. The angle at the vertex of the control plate member  9  is two times greater than a reverse tangent, tan −1 (b/a), of the angle defined by the side “a” and the side “b”. The getter  4  is hence held by the holder  10  so that its spreading side stays in an isosceles triangle of which the base is equivalent to the base “a” of the conical shape and the angle at each end of the base is expressed by tan −1 (b/a). The angle α shown in  FIG. 4B  is equivalent to tan −1 (b/a). 
     FIG. 5  is a cross sectional view showing a part of an FED which employs the getter support  7  including the control plate member  9  shown in  FIGS. 4A and 4B . As shown in  FIG. 5 , the FED comprises a first glass substrate  1 , a second glass substrate  2 , a spacer  3 , a getter  4 , a getter support  7 , and a display area  27 . The display area  27  includes a pattern of wiring layer  12 , electron emitter elements  13 , a pattern of insulating layers  14  and lead electrodes  15  such as shown in FIG.  2 A. In the present embodiment, as shown in  FIG. 5 , when the getter material  6  is evaporated, the getter support  7  enables the primary and secondary portions of the spreading of the getter material  6  from the getter  4  to at least reflect or collide against the control plate member  9 , and therefore the spreading of the getter material can be effectively controlled. Also, the getter support  7  enables to control deposition of a tertiary portion of the spreading, if any, on the inner wall of the vacuum envelope  18  including the spacer  3  and to inhibit any deposition on the display area  27 , thus minimizing leak currents and avoiding unwanted electrical conduction between the electrodes. Consequently, the getter support  7  in the FED according to this embodiment can highly be effective in the function. 
     FIG. 6A  is a longitudinally cross sectional view of a control plate member  9  where the angle of its vertex is two times greater than tan −1 (b/a). The control plate member  9  has a pentagonal shape ABCDE in the longitudinal cross section. The side AB is “a” while the side AE and the side BC are equal to “b”. The line AC and the line BE intersect each other at a point F. The angle α is equivalent to tan −1 (b/a). The angle DCA and the angle DEB are 90 degrees. 
   Referring to  FIG. 6A , the spreading of the getter material  6  will be explained with the getter  4  located outside the isosceles triangle ABF in the control plate member  9 . In case that the getter material  6  of the getter  4  is discharged from the inner side of the line BE and collided at the point E or a location on the control plate member  9  distanced slightly from the point E towards the vertex D, its incident angle is smaller than 90 degrees or the angle BED. This allows the getter material  6  to be flied out from the control plate member  9  as denoted by a dotted line  30 . In case that the getter material  6  is discharged from the inner side of the line AC and collided at the point C or a location on the control plate member  9  distanced slightly from the point C towards the vertex D, the getter material  6  can be flied out from the control plate member  9  in the same manner. 
   With the getter  4  located on the inner side from the isosceles triangle ABF in the controlling member  9 , the secondary portion of the spreading of the getter material  6  can be deposited on the inner wall of the vacuum envelope  18  including the spacer  3 . When the getter  4  is located within the isosceles triangle ABF, at least the secondary portion of the spreading of its getter material  6  is reflected or collided against the control plate member  9 , and the getter support  7  can control up to the secondary portion of the spreading. 
     FIG. 6B  is a cross sectional view of a control plate member where the angle at the vertex of its conical shape is smaller than two times the inverse tangent tan −1 (b/a). The longitudinal cross section of the controller member  9  is a pentagonal shape ABCDE. The length of the side AB is “a” while the length of the side AE and the side BC is “b”. The angle β is smaller than the angle α and smaller than tan −1 (b/a). It is assumed that the line extending from the point C at a right angle to the side CD intersects with the side AE at a point G. It is also assumed that the line extending from the point E at a right angle to the side DE intersects with the side BC at a point H. The line CG and the line EH intersect each other at a point I. 
   As explained above, with the getter  4  located on the inner side than the pentagon ABHIG in the control plate member  9 , the secondary portion of the spreading of the getter material  6  can be deposited on the inner wall of the vacuum envelope  18  including the spacer  3 . When the getter  4  is located within the pentagon ABHIG, at least the secondary portion of the spreading of its getter material  6  is reflected or collided against the control plate member  9 , and the getter support  7  can control up to the secondary portion of the spreading. 
     FIG. 6C  is a cross sectional view of a control plate member where the angle at the vertex of its conical shape is greater than two times the inverse tangent tan −1 (b/a). The longitudinal cross section of the control plate member  9  is a pentagonal shape ABCDE. The length of the side AB is “a” while the length of the side AE and the side BC is “b”. The angle γ is greater than the angle α and greater than tan −1 (b/a). It is assumed that the line extending from the point C at a right angle to the side CD intersects with the side AB at a point J. It is also assumed that the line extending from the point E at a right angle to the side DE intersects with the side AB at a point K. The line CJ and the line EK intersect each other at a point L. 
   As explained above, with the getter  4  located on the outer side of the triangle JKL but within the control plate member  9 , the secondary portion of the spreading of the getter material  6  can be deposited on the inner wall of the vacuum envelope  18  including the spacer  3 . When the getter  4  is located within the triangle JKL, at least the secondary portion of the spreading of its getter material  6  is reflected or collided against the control plate member  9 , and the getter support  7  can control up to the secondary portion of the spreading. 
   It is understood that the longitudinal cross section defined by the vertex and the center of the base of the conical shape of the control plate member  9  includes the getter  4 . 
   It is desired that the spreading side of the getter  4  where the getter material  6  is exposed faces towards the display area  27  and the line extending from the center of the getter  4  and the vertex of the control plate member  9  in the getter support  7  intersects with the display area  27 . The positional relationship between the getter  4  and the getter support  7  can inhibit the display area  27  from unwanted electrical conduction at higher effectiveness. 
   The vacuum envelope  18  is not limited to the housing of a display device but may be used as a vacuum container. 
   Another modification of the support leg will be explained. 
   In Embodiment 1, a single getter support  7  is provided in the vacuum envelope  18 . Two or more of the getter supports  7  may be provided in the vacuum envelope  18 .  FIG. 7  is an explanatory view illustrating an arrangement of the plural getter supports  7 . When groups of the getter supports  7  are provided in the vacuum envelope  18 , each group may be held by a corresponding support leg  8  to minimize the number of components as shown in FIG.  7 . Also, as two opposite groups of the getter supports  7  are located on both sides of and sandwich the display area  27 , the vacuum state in the vacuum envelope  18  can favorably be maintained uniform. Moreover, as the getter supports  7  are located outside of the display area  27  in the vacuum envelope  18 , they can never disturb the display area  27  thus ensuring the uniformity of the vacuum state in the vacuum envelope  18 . 
   According to this embodiment of the present invention, the getter  4  is provided in the vacuum envelope  18  prior to the step of completing the vacuum envelope  18  and can employ a evaporation type of the getter material which is higher in the getter effect than a non-evaporation type, e.g. N301 (made by Toshiba). 
   The spacer  3  is a rectangular frame of which the dimensions correspond to the size of the electron emitter substrate  25  and the light emitter substrate  26 . More particularly, the spacer  3  is provided at both, upper and lower, sides with a uniform thickness, substantially 2 mm, of fritted glass. 
   When the electron emitter substrate  25 , the light emitter substrate  26 , and the spacer  3  have been assembled together in high accuracy and heated to a predetermined temperature under the vacuum state, the vacuum envelope  18  or the display device is fabricated (See FIG.  1 ). 
   A method of fabricating the getter support will now be described referring to  FIGS. 8A  to  8 C. 
     FIGS. 8A ,  8 B, and  8 C illustrate a pre-assembled form, an assembling form, and an assembled form of the getter support  7 , respectively. In this case, a stainless steel material of 0.07 mm thick is used. The getter support  7  comprises a getter  4 , support leg  8 , control plate member  9 , and holder  10 . As shown in  FIG. 8B , the holder  10  is joined by welding to the back side of the getter  4  where the getter material  6  is not exposed. Then, the holder  10  and the control plate member  9  are joined to each other by welding and the control plate member  9  and the support leg  8  are joined to each other by welding. This is followed by bending the holder  10  so that the side of the getter  4  where the getter material  6  is exposed is located at the opening of the control plate member  9  and then folding the support leg  8  so that the getter support  7  sits in the vacuum envelope  18  as shown in FIG.  8 C. As two distal ends of the support leg  8  are folded inwardly as shown in  FIG. 8C , they remain not injuring any of the first glass substrate  1 , the second glass substrate  2 , and the spacer  3 . 
   Preferably, as shown in  FIG. 3A , the getter support  7  is anchored so that the opening of the control plate member  9  comes opposite to the wiring layer  12  and the electron emitter elements  13 . 
   Another method of fabricating the getter support will be explained referring to  FIGS. 9A  to  9 C. 
     FIGS. 9A ,  9 B, and  9 C illustrate a pre-assembled form, an assembling form, and an assembled form of the getter support  7 , respectively. In this case, a stainless steel material of 0.07 mm thick is used. The getter support  7  comprises a support leg  8 , a controlling member  9 , and a holder  10  assembled together as a single unit, as shown in FIG.  9 A. The control plate member  9  has a slit  11  provided therein for forming a conical shape. As shown in  FIG. 9B , the holder  10  is joined by welding to the back side of the getter  4  where the getter material  6  is not exposed. The both sides of the slit  11  of the control plate member  9  is overlapped and welded each other to form a conical shape. This is followed by bending the holder  10  so that the side of the getter  4  where the getter material  6  is exposed is located at the opening of the control plate member  9  and then folding the support leg  8  so that the getter support  7  sits in the vacuum envelope  18 . As two distal ends of the support leg  8  are folded inwardly as shown in  FIG. 9C , they remain not injuring any of the first glass substrate  1 , the second glass substrate  2 , and the spacer  3 . 
   Preferably, as shown in  FIG. 3A , the getter support  7  is anchored so that the opening of the controlling member  9  comes opposite to the wiring layer  12  and the electron emitter elements  13 . 
   A further method of fabricating the getter support  7  will be explained referring to  FIGS. 10A  to  10 C. 
     FIGS. 10A ,  10 B, and  10 C illustrate a pre-assembled form, an assembling form, and an assembled form of the getter support  7 , respectively. In this case, a stainless steel material of 0.07 mm thick is used. The getter support  7  comprises a support leg  8 , a control plate member  9 , and a holder  10  assembled together in a single unit. The control plate member  9  is shaped to a desired 3-dimensional configuration by drawing. As shown in  FIG. 10B , the holder  10  is joined by welding to the back side of the getter  4  where the getter material  6  is not exposed. This is followed by bending the holder  10  so that the side of the getter  4  where the getter material  6  is exposed is located at the opening of the control plate member  9  and then folding the support leg  8  so that the getter support  7  sits in the vacuum envelope  18  as shown in FIG.  10 C. As two distal ends of the support leg  8  are folded inwardly as shown in  FIG. 10C , they remain not injuring any of the first glass substrate  1 , the second glass substrate  2 , and the spacer  3 . 
   Preferably as shown in  FIG. 3A , the getter support  7  is anchored so that the opening of the control plate member  9  comes opposite to the wiring layer  12  and the electron emitter elements  13 . 
   According to the materials, construction, and steps of the present invention, when the getter is disposed in the vacuum envelope  18 , its supporting construction can be minimized in the number of components and its related method of fabricating a display device can be reduced in the number of steps. Therefore, the vacuum envelope  18  or the display device using the same will be improved in the degree of vacuum while the spreading of the getter material therein is controlled in desired directions. As the direction of the spreading of the getter material is controlled, the getter can favorably be disposed within the vacuum envelope  18  or the display device to be finished. Also, since a getter chamber required in the prior art is not needed, the vacuum envelope  18  or the display device can be made flat. 
   As set forth above, the vacuum container of the present invention has a getter provided therein while the number of components is minimized, the procedure of fabrication is simplified, the degree of vacuum is improved, and the spreading of getter flushes is controlled in directions. As the spreading of getter particles is controlled, the getter can be disposed within the vacuum container. Since a getter chamber required in the prior art is not needed, the vacuum container can be shaped flat. 
   Moreover, the display device of the present invention has a getter provided therein while the number of components is minimized, the procedure of fabrication is simplified, the degree of vacuum is improved, and the spreading of getter flushes is controlled in directions. As the spreading of getter particles is controlled, the getter can be disposed within the display device. Since a getter chamber required in the prior art is not needed, the display device can be shaped flat. 
   The present disclosure relates to subject matter contained in priority Japanese Patent Application No. 2000-228830, filed on Jul. 28, 2000, the contents of which is herein expressly incorporated by reference in its entirety.