Abstract:
In a manufacturing method of forming a hermetically sealed container by bringing a pair of substrates into intimate contact via a supporting frame between them, one of the substrates is warped in a depressurized atmosphere before getting into intimate contact and is thereby separated from the other substrate so as to evacuate inside of the hermetically sealed container by releasing the depressurized atmosphere therein. Relative positions of the substrates are restored by having the warp undone thereafter. Therefore, it is possible to achieve evacuation inside the hermetically sealed container without causing the relative positions of the substrates to deviate.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a manufacturing method and a manufacturing apparatus of an envelope of an image displaying apparatus and so on.  
         [0003]     2. Related Background Art  
         [0004]     Japanese-Patent Application Laid-Open No. S06-196094 discloses a manufacturing method of a vacuum displaying apparatus with a glass container having display surface glass and substrate glass deposited with low melting glass, the method comprising stages of assembling the glass container having low melting point rod glass placed between display glass and the substrate glass, evacuating internal air of the glass container from a gap provided thereon, and melting and seal-bonding the low melting point rod glass in a state of remaining evacuated as-is.  
         [0005]     Japanese Patent Application Laid-Open No. 2001-28241 discloses a manufacturing method of an image displaying apparatus of seal-bonding via a joining member a first substrate having phosphor excitation means placed thereon and a second substrate having a phosphor glowing by phosphor excitation means placed thereon, the method comprising a heating process of heating the first and second substrates and joining member up to a sealing temperature in a chamber while holding the first and second substrates between first and second heating means with their sealing portions not in contact and evacuating inside of the chamber, and a seal-bonding process of seal-bonding the first and second substrates via the joining member by bringing their sealing portions into contact in a state of having the inside of the chamber evacuated. According to the manufacturing method disclosed by Japanese Patent Application Laid-Open No. 2001-28241, the evacuation and heating process are performed in the state of holding the two substrates at a desired distance not to bring them into contact.  
         [0006]     According to the configuration disclosed by Japanese Patent Application Laid-Open No. 2001-28241, it is necessary, for the sake of holding the first and second substrates without bringing their sealing portions into contact, to fix at least one of the substrates to position adjusting means with a fixture or the like, and move the entire fixed substrate by the position adjusting means in a direction for separating from the other substrate so as to form a gap between the substrates.  
         [0007]     In the case of the configuration for moving the entire substrate fixed on the position adjusting means with a fixture or the like in the direction for separating from the other substrate, however, it generates a wasteful clearance (dead stroke) larger than a sufficient clearance for evacuating a space between the substrates. As for such a configuration generating the dead stroke, a manufacturing apparatus becomes more complicated and larger correspondingly and additional traveling time of the substrate is correspondingly required so that reduction in manufacturing time is interrupted.  
       SUMMARU OF THE INVENTION  
       [0008]     Thus, an object of the present invention is to provide a manufacturing method and a manufacturing apparatus of an envelope capable of evacuating a space between substrates without generating a dead stroke between the substrates. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIGS. 1A, 1B  and  1 C are diagrams showing a process flow and an overview configuration of a manufacturing method of an image displaying apparatus according to an embodiment of the present invention;  
         [0010]      FIGS. 2A, 2B  and  2 C are diagrams showing. stepwise a manufacturing process of an envelope according to an embodiment of the present invention;  
         [0011]      FIG. 3  is a diagram showing a process of positioning a rear plate and a face plate;  
         [0012]      FIGS. 4A and 4B  are diagrams showing a state in the process shown in  FIG. 2B ;  
         [0013]      FIGS. 5A and 5B  are diagrams showing a heating mechanism of a plate applied to the manufacturing method and a manufacturing apparatus of the image displaying apparatus according to an embodiment of the present invention; and  
         [0014]      FIGS. 6A and 6B  are diagrams showing a positioning spring for positioning and fixing two plates. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]     A manufacturing method of an envelope of the present invention is the method of forming a hermetically sealed container by seal-bonding edge portions of a pair of substrates via a supporting frame between them in a depressurized atmosphere comprising a process of warping the edge portions of at least one of the pair of substrates and separating it from the other substrate in the depressurized atmosphere before performing the seal-bonding.  
         [0016]     A manufacturing apparatus of the envelope of the present invention is the apparatus for forming a hermetically sealed container by seal-bonding edge portions of a pair of substrates via a supporting frame between them in a depressurized atmosphere comprising separating means for warping the edge portions of at least one of the pair of substrates and separating it from the other substrate.  
         [0017]     According to the manufacturing method of the envelope of the present invention, it is possible, just by warping the edge portions of one of the substrates, to generate a gap between the substrates or extend a clearance between them so as to evacuate a space between the substrates through the gap.  
         [0018]     According to the manufacturing apparatus of the envelope of the present invention, it is possible, just by warping the edge portions of one of the substrates by the separating means, to generate a gap between the substrates or extend a clearance between them so as to evacuate a space between the substrates through the gap.  
         [0019]     As described above, according to the present invention, it is possible to evacuate the space between the substrates without generating a dead stroke between the substrates.  
         [0020]     Next, embodiments of the present invention will be described by referring to the drawings.  
         [0021]     A manufacturing method and a manufacturing apparatus of an envelope of the present invention include the manufacturing methods and manufacturing apparatuses of a glass container having two sheets of glass bonded together And vacuum-sealed, an image displaying apparatus incorporating electron-emitting devices or an image displaying apparatus such as a plasma display. In particular, the manufacturing method and manufacturing apparatus of the image displaying apparatus are desirable forms of application of the present invention in terms of cost reduction.  
         [0022]     The embodiments of the present invention will be described by exemplifying the image displaying apparatus incorporating the electron-emitting device and a phosphor film having electrons emitted by the electron-emitting device irradiated thereon. A concrete description thereof will be given by using  FIGS. 1A  to  1 C,  FIGS. 2A  to  2 C and  FIG. 3 .  
         [0023]      FIGS. 1A  to  1 C are diagrams showing a process flow and an overview configuration of the manufacturing method of the image displaying apparatus according to an embodiment of the present invention.  FIG. 1A  is a flow chart showing the process flow of the manufacturing method of the image displaying apparatus according to this embodiment.  FIG. 1B  is a perspective view showing the overview configuration of the image displaying apparatus according to this embodiment.  FIG. 1C  is a sectional view at a line  1 C to  1 C shown in  FIG. 1B .  
         [0024]     First, the configuration of the image displaying apparatus according to this embodiment will be described by referring to  FIGS. 1B and 1C . The image displaying apparatus according to this embodiment is configured by an envelope  90  incorporating a rear plate  81  as a substrate configuring an electron source substrate  80  having multiple electron-emitting devices  87  placed on a top surface thereof and having wirings  88 ,  89  connected to the electron-emitting devices  87  implemented thereon, a face plate  82  as a substrate having a phosphor film  84 , a metal back  85  and a nonvolatile getter  9  configured on a surface opposed to the rear plate  81  of a glass substrate  83 , and a supporting frame  86  for oppositely placing the rear plate  81  and face plate  82  with mutually predetermined spacing. Each joining portion of the plates  81 ,  82  and supporting frame  86  is mutually bonded by using frit glass or In.  
         [0025]     According to this embodiment, supports called spacers  205  are placed between the rear plate  81  and the face plate  82 . It is thereby possible to configure the envelope  90  strong enough against atmospheric pressure even in the case where the image displaying apparatus is a so-called large-area panel. As for the envelope  90 , its size, board thickness of the plates  81 ,  82  and placement of the spacers  205  are appropriately designed depending on mechanical conditions such as an atmospheric-pressure-resistant structure for the sake of keeping the inside vacuum.  
         [0026]     It is general to use a substrate made of a low-cost blue plate glass as the rear plate  81 . In that case, however, it is desirable to form a 0.5 μm-thick silicon dioxide film on the substrate as a sodium block layer by a sputter technique. It is also possible to create the rear plate  81  with glass having little sodium component, a quartz substrate or a non-alkali substrate. As for the plasma display, it is possible to use PD-200 (Asahi Glass Co., Ltd.) appropriately as the rear plate  81 , which is electric glass having little alkali component.  
         [0027]     It is general to use the low-cost blue plate glass as the face plate  82  as with the rear plate  81 . However, this embodiment uses PD-200 (Asahi Glass Co., Ltd.) which is the electric glass for the plasma display having little alkali component. This glass material has no glass coloring phenomenon occurring in the case of display use. If the board thickness is 3 mm or so, it has a sufficient shielding effect of suppressing leakage of a soft X-ray generated secondarily even in the case of being driven at an accelerating voltage of 10 kV or more.  
         [0028]     It is also general to use the low-cost blue plate glass as the material of the spacers  205 . It is selected according to the use of the envelope  90 . In the case where position accuracy of the spacers  205  is required, it is desirable to match a thermal expansion coefficient by using the same material as the glass to be bonded together. The spacers  205  should be in a plate-like, column-like, square-column-like or sheet-like form suited to the use, and the number of placements thereof should also be appropriately set up according to the use. In the case of the image displaying apparatus incorporating the electron-emitting devices  87 , the spacers  205  are designed to suit an electron orbit.  
         [0029]     As for joining members  5  and  6  (refer to  FIGS. 2A  to  2 C for joining the plates  81 ,  82  and supporting frame  86 , the frit glass having a comparable thermal expansion coefficient as the plates  81 ,  82  or a low melting metal such as In, In—Ag or In—Sn is used. Either different materials or the same material may be used for the joining members  5  and  6 . It is desirable, by way of example, to use In or In—Ag for, both the joining members  5  and  6 .  
         [0030]     It is sufficient to have the joining members  5  and  6  applied to at least one of the plates  81 ,  82  and supporting frame  86 . The joining member&#39;s  5  and  6  are applied so that total thickness before joining the plates  81 ,  82  and supporting frame  86  becomes sufficiently more than that after joining them. According to this embodiment, they are applied so that the thickness of an In film formed by the joining members  5  and  6  after joining becomes 300 μm.  
         [0031]     The face plate  82  has the phosphor film  84 , metal back  85  and nonvolatile getter  9  formed on the surface opposed to the rear plate  81  of the glass substrate  83  so that this portion becomes an image display area. The position for placing the nonvolatile getter  9  on the face plate  82  is on a black conductive body  91  between the metal back  85  and the phosphor film  84  of the face plate  82 . It is desirable to place the nonvolatile getter  9  evenly all over the image display area.  
         [0032]     It is possible to form the nonvolatile getter  9  on the face plate  82  by using a material of which major component is Ti by a vacuum deposition method such as an electron beam or a sputter. According to this embodiment, film thickness of the nonvolatile getter  9  is 800 Å (80 nm). However, the placement position and film thickness of the nonvolatile getter  9  are not limited to the above but may be appropriately designed and set up.  
         [0033]     Next, a manufacturing process of the envelope according to this embodiment will be described by referring to  FIG. 1A ,  FIGS. 2A  to  2 C, and  FIG. 3 .  FIGS. 2A  to  2 C are diagrams showing stepwise the manufacturing process of the envelope according to this embodiment, and  FIG. 3  is a diagram showing the process of positioning the rear plate and the face plate.  
         [0034]     First, the rear plate (RP)  81  and the face plate (FP)  82  are prepared (step  1 ).  
         [0035]     Next, as shown in  FIG. 2A , the rear plate  81  is mounted on a lower support member  4 , a joining member  5  is applied to a predetermined position on the rear plate  81 , and the supporting frame  86  is mounted on the applied joining member  5 , and then a joining member  6  is applied to the top surface of the supporting frame  86 . The joining member is also applied to the portion joined to the top surface of the supporting frame  86  of the face plate  82 . In is used as the joining members according to this embodiment. Furthermore, the spacers  205  are placed at a predetermined position on the rear plate  81 . And the members such as the supporting frame  86 , spacers  205  and joining members  5 ,  6  are implemented in a seal bonding chamber (not shown) for manufacturing the envelope  90  so as to finish a preparatory process (step  2 ). In this case, the face plate  82  is held by arms  7  between the rear plate  81  having the supporting frame  86  and spacers  205  provided thereon and an upper support member  8  in the seal bonding chamber. The arms  7  function as separating means for warping the edge portions of the face plate  82  and separating it from the supporting frame  86 .  
         [0036]     Next, according to this embodiment, vacuum baking is performed on baking conditions of 400 degrees C. and 1 hour (step  3 ). These baking conditions are appropriately set up according to the, use of the envelope  90  to be made. In this case, a clearance is provided between the mutually seal-bonded plates  81  and  82  by warping at least one of the two plates  81  and  82  to be convex to the other so as to sufficiently evacuate the space between the plates  81  and  82 . According to this embodiment, as shown in  FIG. 2B , corners of the face plate  82  are held by the arms  7  to warp the face plate  82  so that its underside opposed to the rear plate  81  becomes convex. In this case, the space between the plates  81  and  82  is sufficiently evacuated even in the vicinity of the center if there is a clearance of 1 mm or so between the plates  81  and  82  around their circumferences irrespective of whether or not the vicinity of the center of the warped face plate  82  is in contact with the spacers  205  then.  
         [0037]     Thereafter, as shown in  FIG. 2C , the arms  7  are lowered to place the face plate  82  on the supporting frame  86 , and the seal bonding is performed at a temperature for melting the joining members  5  and  6  (step  4 ). According to this embodiment, the seal bonding process was performed on condition that the temperature of the plates  81  and  82  was within 160 degrees C. ±5 degrees C.  
         [0038]     Here, in the case where the envelope  90  to be made is a color image displaying apparatus, it is necessary to perform positioning of the plates  81  and  82  when lowering the arms  7  to place the face plate  82  on the supporting frame  86  as shown in  FIG. 2C  so that phosphors of colors of the phosphor film  84  correspond to the electron-emitting devices  87  on the plate  81 . For that reason, according to this embodiment, mutual positioning of the plates  81  and  82  is sufficiently performed by using a positioning apparatus  200  (refer to  FIG. 3 ) for performing the mutual positioning of the plates  81  and  82 . The positioning apparatus  200  moves at least one of the plates  81  and  82  to the other so as to perform positioning in vertical and horizontal directions (XY directions) and a rotation direction (θ direction) in a plane of the plate. In the case of the configuration having no electron-emitting device or phosphor placed on the plates, the accuracy required of the positioning of the plates is not so high and so the positioning apparatus  200  described above is not always necessary.  
         [0039]     On the seal bonding, a required degree of vacuum is 1×10 −6  [Torr] (approx. 1.3×10 −4  [Pa]) or less. Furthermore, there are the cases where a getter process is performed in order to maintain the degree of vacuum in the envelope  90  after the seal bonding. Here, the getter process is a process of, immediately before or after seal-bonding the envelope  90 , heating the getter placed in advance at a predetermined position (not shown) in the envelope  90  by a heating method such as resistance heating or high-frequency heating so as to form an evaporated film (not shown). In this case, the major component of a getter member is ordinarily Ba or the like, and it is possible, by an absorptive action, of the evaporated film formed as described above, to maintain the degree of vacuum in the envelope  910  at 1×10 −5  to 1×10 −7  [Torr] (approx. 1.3×10 −3  to 1.3×10 −5  [Pa]) for instance.  
         [0040]      FIGS. 4A and 4B  are diagrams showing a state in the process shown in  FIG. 2B , where  FIG. 4A  is a sectional view thereof and  FIG. 4B  is a plan view viewing the face plate of  FIG. 4A  from above.  FIG. 4B  shows the arms  7  as partially seen through.  
         [0041]     According to this embodiment, the face plate  82  is held by the four arms  7  at the four corners thereof to move the face plate  82  vertically while warping it. It is possible, in such a configuration, to keep warping the face plate  82  with its own weight so as to secure conductance between the two vacuum-sealed plates  81  and  82 . Consequently, it is possible to seal-bond the plates  81  and  82  mutually in the state of having their internal space well evacuated. According to this embodiment, no particular control or apparatus is required other than the arms  7  for moving the face plate  82  vertically and the apparatus for driving them. Therefore, it is possible to reduce the cost of the apparatus for making the envelope  90 .  
         [0042]     The positions for the arms  7  to hold the face plate  82  are set up appropriately depending on the size and board thickness of the face plate  82 . The positions for the arms  7  to hold the face plate  82  are not limited to the four locations at the four corners. It is also possible to have a configuration in which, while holding the face plate  82  with the arms  7  as if lifting it, a member for pushing the center of the face plate  82  downward is further provided separately. According to this configuration, it is possible to further warp the face plate  82  by pushing the center of the face plate  82  downward in the state of holding the four corners of the face plate  82  with the arms  7 .  
         [0043]      FIGS. 5A and 5B  are diagrams showing a heating mechanism of the plate according to another embodiment of the manufacturing method and manufacturing apparatus of the image displaying apparatus of the present invention, where  FIG. 5A  is a plan view and  FIG. 5A  is a front view.  
         [0044]     In the example shown in  FIGS. 5A and 5B , heaters  100  for heating the face plate  82  are placed opposite one another on the plate by being divided vertically and horizontally into three blocks, that is, nine blocks in total. In the case where the face plate  82  consists of the above-mentioned glass substrate, the edge portions warp on heating the face plate  82  and so the gap is generated at the edge portions between the face plate  82  and the rear plate  81 . For that reason, it is possible to evacuate the space between the plates  81  and  82  through the gap in the seal bonding process. Therefore, the heaters  100  function as separating means for warping the edge portions of the face plate  82  and separating it from the supporting frame  86 .  
         [0045]     The heaters  100  may be either set up to uniformly heat the face plate  82  or set up to provide temperature distribution to the face plate  82 . In particular, it is effective, for the sake of warping the edge portions of the face plate  82 , to heat the edge portions of the face plate  82  more strongly than the center thereof. Therefore, it is desirable to render heating by the heaters  100  of blocks  2 ,  5  and  8  for heating the edge portions of the face plate  82  stronger than the heating by the heaters for heating the center. According to this embodiment, the heaters  100  get heated to generate a temperature difference of 50 degrees C. at the maximum between the area of the block  5  as the center of the face plate  82  and the other areas in a vacuum baking process. However, the temperature difference becomes ±5 degrees C. or less before the seal bonding process.  
         [0046]     This embodiment uses sheath heaters as the heaters  100 . However, lamp heaters may be used instead of them. The above described the configuration in which the heaters  100  heat the face plate  82 . It is also possible, however, to have the configuration in which the rear plate  81  is heated or both the plates  81  and  82  are heated by the heaters. It is also possible, as described above, to thus heat the plate with the heaters in combination with warping of the plate by holding at least the four corners of the plate with the arms.  
       Embodiments  
       [0047]     Hereunder, the manufacturing method of the envelope of the present invention will be described in detail by taking up concrete embodiments.  
       First Embodiment  
       [0048]     In this embodiment, the envelope was made by using a rear plate and a face plate both made of a blue plate glass of 900 mm×580 mm in length and breadth and 2.8 mm in thickness, spacers made of a blue plate glass of 1 mm×1 mm in length and breadth and 0.5 mm in thickness, and a supporting frame of 900 mm×580 mm in length and breadth with a surrounding wall of 4 mm in breadth and 0.2 mm in height (thickness). Raw glass substrates having no electron-emitting device, phosphor film or getter formed thereon were used for the rear plate and face plate respectively. The spacers were placed with 30-mm pitches. In was applied to the joining portions of the plates and the supporting frame.  
         [0049]     The temperature during the vacuum baking process was 200 degrees C. During that time, the positions at 5 mm from the corners of the face plate as the upper plate were supported by the arms, and the face plate was lifted to the height of 3 mm from the top surfaces of the spacers placed on the rear plate to warp it so as to render its underside convex. After thus performing the baking for one hour, the envelope was made by seal-bonding the rear plate and face plate via the supporting frame.  
       Second Embodiment  
       [0050]     To give a description of this embodiment by referring to  FIGS. 1A  to  1 C, the envelope as an image displaying apparatus was made by using the rear plate  81  having an SiO 2  film of 3000 Å (300 nm) in thickness formed and electron-emitting devices and wirings further formed on the plate made of PD-200 (Asahi Glass Co., Ltd.) which is electric glass of 900 mm×580 mm in length and breadth and 2.8 mm in thickness, the face plate  82  having the phosphor film  84  and getter  9  formed on the plate made of PD-200 (Asahi Glass Co., Ltd.) which is electric glass of 900 mm×580 mm in length and breadth and 2.8 mm in thickness, the supporting frame  86  made of the blue plate glass of 830 mm×510 mm in length and breadth with a surrounding wall of 4 mm in breadth and 1.3 mm in thickness, and the spacers  205  having an antistatic film (not shown) formed on a surface of PD-200 (Asahi Glass Co., Ltd.) which is the electric glass of 780 mm in length and 200 μm in breadth and 1.6 mm in height. In was used as the joining member of the plates  81  and  82  and the supporting frame  86 . The thickness of the joining member was 300 μm before the seal bonding and 150 μm after the seal bonding.  
         [0051]     The temperature during the vacuum baking process was 400 degrees C. During that time, the positions at 5 mm from the corners of the face plate  82  as the upper plate were supported by the arms, and the face plate  82  was lifted to the height of 3 mm from the top surfaces of the spacers placed on the rear plate  81  to warp it so as to render its underside convex. After thus performing the baking for one hour, the envelope as the image displaying apparatus was made by seal-bonding the rear plate  81  and face plate  82  via the supporting frame  86 .  
       Third Embodiment  
       [0052]     In this embodiment, the center of the upper face plate  82  was heated by the heaters  100  in the vacuum baking process so that it becomes about 50 degrees C. higher than the other portions. In was applied only to the joining portions of the rear plate  81  and the supporting frame  86  (the frit glass was applied to the joining portions of the face plate  82  and the supporting frame  86 ). Otherwise, the envelope as the image displaying apparatus was made as in the case of the second embodiment.  
       Fourth Embodiment  
       [0053]     In this embodiment, the centers of both the plates  81  and  82  were heated by the heaters in the vacuum baking process so that they become about 50 degrees C. higher than the other portions. Furthermore, the upper face plate  82  was lifted by the arms  7  to warp it and render its underside convex, and the lower rear plate  81  was warped by using an unshown mechanism to render its upper surface convex. Such a mechanism can be configured, for instance, by providing a pin (not shown) projectable to push the center of the rear plate  81  upward to the lower support member  4  shown in  FIGS. 2A  to  2 C. In this case, such a pin functions as the separating means for warping the edge portions of the rear plate  81  and separating it from the supporting frame  86 .  
         [0054]     In was applied to the joining portions of the plates  81 ,  82  and the supporting frame  86 . Otherwise, the envelope as the image displaying apparatus was made as in the case of the second embodiment.  
       Fifth Embodiment  
       [0055]     Before putting it in the seal bonding chamber, this embodiment used a positioning spring (refer to  FIGS. 6A and 6B ) capable of moving the two plates  81 ,  82  only heightwise (in a superposing direction) so as to fix their mutual positions.  
         [0056]      FIGS. 6A and 6B  are diagrams showing the positioning spring for positioning and fixing the two plates. As shown in  FIGS. 6A and 6B , a positioning spring  180  is in a clip-like form, and is formed to be able to sandwich the plates  81 ,  82  joined to the top and under surfaces of the supporting frame  86 .  
         [0057]     The plates  81 ,  82  are mutually aligned by the positioning apparatus  200  shown in  FIG. 3 , and are mutually positioned thereafter, for instance, by mounting two positioning springs  180  on one side of the plates  81 ,  82  as shown in  FIG. 6B . To keep that positioning state, a cementing material such as Aron Ceramics of Toagosei Co., Ltd. is applied to the contacting portions of the positioning springs  180  and the plates  81 ,  82 , and is hardened and fixed at 120 degrees C. The positioning springs  180  are built into a product in the state of thus being fixed on the plates  81 ,  82 , and so they should desirably have the same thermal expansion coefficient as the plates  81 ,  82 . For that reason, according to this embodiment, the positioning spring  180  is configured by a nickel alloy having the same thermal expansion coefficient as PD-200 (Asahi Glass Co., Ltd.) which is the material of the plates  81  and  82 .  
         [0058]     Otherwise, the envelope as the image displaying apparatus was made as in the case of the second embodiment.  
       Sixth Embodiment  
       [0059]     Before putting it in the seal bonding chamber, this embodiment used a positioning spring (refer to  FIGS. 6A and 6B ) capable of moving the two plates  81 ,  82  only heightwise (in the superposing direction) so as to fix their mutual positions. And in the vacuum baking process, the face plate  82  was warped while holding the face plate  82  above and apart from the rear plate  81  not to be in contact with the spacers  205  on the rear plate  81 . Thereafter, the envelope as the image displaying apparatus was made as in the case of the second embodiment.  
       Seventh Embodiment  
       [0060]     Before putting it in the seal bonding chamber, this embodiment prepared seven sets of the two plates  81 ,  82  having their mutual positions fixed with the positioning spring (refer to  FIGS. 6A and 6B ) capable of moving them only heightwise (in the superposing direction). And the seven sets were collectively seal-bonded by a batch processing apparatus capable of simultaneously putting them therein. Otherwise, the envelope as the image displaying apparatus was made as in the case of the fifth embodiment.  
         [0061]     This application claims priority from Japanese Patent Application No. 2004-243622 filed Aug. 24, 2004, which is hereby incorporated by reference herein.