Abstract:
A packing member for packing an article includes a medium accommodating portion accommodating medium, a non-return valve for passing the medium toward the medium accommodating portion along a longitudinal direction of the medium accommodating portion and for stopping the medium in an opposite direction away from the medium accommodating portion, and a flow path, formed by welding the non-return valve to the medium accommodating portion, for passing the medium. The flow path includes a reference flow path portion extending in the longitudinal direction and an expanding flow path portion having a width larger than that of the reference flow path portion.

Description:
FIELD OF THE INVENTION AND RELATED ART 
       [0001]    The present invention relates to a packaging material for wrapping an object for shipment. More specifically, it relates to a packaging material having a check valve which allows cushioning medium to flow into the cushioning medium storage portions of the packaging material, but prevents the cushioning medium from flowing backward from the cushioning medium storage portions. 
         [0002]    There have been designed various packaging materials, the cushioning medium storage portions of which are formed by welding together two or more flexible sheets. There have also been designed various check valves for these packaging materials. Some of these check valves are designed so that they allow the cushioning medium to flow into the cushioning medium storage portions, but, do not allow the cushioning medium to flow backward from the cushioning medium storage portions. (Japanese Laid-open Patent Application H11-216784). 
         [0003]    The conventional check valves, such as those described above, are provided with a means for making complicated or narrow the passage, or passages, of the check valve to prevent the cushioning medium from flowing backward from the cushioning medium storage portion. Thus, these check valves are problematic in that they are low in the efficiency with which the cushioning medium is injected into the cushioning medium storage portions. As one of the means for preventing the provision of a check valve from losing the efficiency is to increase a check valve in size, and also, to increase in length. This means is problematic in that the employment of this means results in increase in the amount of the check valve material, which results in increase in the check valve cost. 
       SUMMARY OF THE INVENTION 
       [0004]    Thus, the primary object of the present invention is to provide a process cartridge packaging material, which is different from conventional process cartridge packaging materials in the pattern in which a check valve is welded to each of its cushioning medium storage portions, and also, is superior to conventional process cartridge packaging materials, in the efficiency with which cushioning medium can be injected into the cushioning medium storage portions. 
         [0005]    According to an aspect of the present invention, there is provided a packing member for packing an article, said packing member includes a medium accommodating portion accommodating medium; a non-return valve for passing the medium toward said medium accommodating portion along a longitudinal direction of said medium accommodating portion and for stopping the medium in an opposite direction away from said medium accommodating portion; and a flow path, formed by welding said non-return valve to said medium accommodating portion, for passing the medium, said flow path including a reference flow path portion extending in the longitudinal direction and an expanded flow path portion having a width larger than that of said reference flow path portion. 
         [0006]    These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a plan of a piece of packaging material in the first preferred embodiments of the present invention. 
           [0008]      FIG. 2  is a sectional view of one of the cushioning units of the packaging material in the first preferred embodiment. 
           [0009]      FIG. 3  is a plan of one of the cushioning units of the packaging material in the first preferred embodiment. 
           [0010]      FIG. 4  is a plan of the cushioning medium passage of one of the cushioning units of the packaging material in the first preferred embodiment. 
           [0011]      FIG. 5  is a sectional view of one of the cushioning medium storage portions of the packaging material in the first preferred embodiment. 
           [0012]      FIG. 6  is a sectional view of one of the cushioning medium storage portions of a comparative packaging material. 
           [0013]      FIG. 7  is a perspective view of a roll of packaging material in the first preferred embodiment, which is on a metallic rod K 2 . 
           [0014]      FIG. 8  is a perspective view of a folded piece of packaging material in the first preferred embodiment, showing the method for wrapping a cartridge with the packaging material. 
           [0015]      FIG. 9  is a plan of the folded piece of packaging material in the first preferred embodiment, showing the method for wrapping a cartridge with the packaging material. 
           [0016]      FIG. 10  is perspective view of the folded piece of packaging material in the first preferred embodiment, showing the method for wrapping a cartridge with the packaging material. 
           [0017]      FIG. 11  is a plan of one of the cushioning units of the packaging material in the first preferred embodiment. 
           [0018]      FIG. 12  is a sectional view of one of the cushioning units of the packaging material in the first preferred embodiment. 
           [0019]      FIG. 13  is a sectional view of one of the cushioning medium storage portions of the packaging material in the first preferred embodiment. 
           [0020]      FIG. 14  is a sectional view of one of the cushioning medium storage portions of the comparative packaging material. 
           [0021]      FIG. 15  is a plan of one of the cushioning medium storage portions of the packaging material in the third preferred embodiments. 
           [0022]      FIG. 16  is a plan of the cushioning medium passage of one of the cushioning units of the packaging material in the third preferred embodiment. 
           [0023]      FIG. 17  is a plan of the packaging portion proper of the packaging material in the fourth preferred embodiment. 
           [0024]      FIG. 18  is a sectional view of one of the cushioning units of the packaging material in the fourth preferred embodiment. 
           [0025]      FIG. 19  is a cross-sectional view of the cushioning medium storage portion of one of the cushioning units of the packaging material in the fourth preferred embodiment. 
           [0026]      FIGS. 20(   a )- 20 ( c ) are plans of the cushioning medium passage of the check valve of the cushioning units of the packaging material in the fifth preferred embodiment. 
           [0027]      FIGS. 21(   a ) and  21 ( b ) are plans of the cushioning medium passage of the check valve of one of the cushioning units of the packaging material in the fifth preferred embodiment. 
           [0028]      FIGS. 22(   a ) and  22 ( b ) are plans of the cushioning medium passage of the check valve of one of the cushioning units of the packaging material in the fifth embodiment. 
           [0029]      FIG. 23  is a perspective view of the sealed packaging material in accordance with the present invention, which contains a cartridge. 
           [0030]      FIG. 24  is a perspective view of the sealed packaging material in accordance with the present invention, which contains a cartridge. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 1 
     (Packaging Material Structure) 
       [0031]    Referring to  FIGS. 1 and 2 , a packaging material S 1  in this embodiment is made up of two pieces  1  and  2  of flexible plastic film, which are thermally welded in layers. The areas  6 ,  8 , and  9  are the areas of the two films  1  and  2 , by which the two films  1  and  2  are welded. The packaging material S 1  has multiple cushioning medium storage portions  3 , which are placed side by side. Each cushioning medium storage portion  3  is enabled to store cushioning medium, which in this embodiment is air. It is formed by welding the two flexible films  1  and  2  (which hereafter will be referred to simply as films  1  and  2 ) across the welding areas  8 ,  6 , and  9 . It is rectangular, with its longer edges being substantially longer than its shorter edges. Further, each cushioning medium storage portion  3  is separated from the next cushioning medium storage portions by the welding areas  9 . One of the lengthwise ends of the packaging material S 1  is provided with multiple cushioning medium entrances  5  for guiding the external air into each of the multiple cushioning medium storage portions  3  to inflate the cushioning medium storage portions  3 . Further, the outward end of each of the cushioning medium (air) entrance  5  is provided with an air injection opening  11 . Each air entrance  5  is separated from the next ones by the welding areas  7 . The welding areas  9  are roughly parallel to the lengthwise direction of the cushioning medium storage portion  3 , whereas the welding areas  6  and  8  extend in the direction intersectional to the lengthwise direction of the cushioning medium storage portion  3 . The welding area  6  is on the opposite lengthwise end of the packaging material S 1  from where the abovementioned air entrances  5  are present. The films  1  and  2  in this embodiment are flexible, and have three layers. That is, each film is formed by sandwiching a Nylon layer with polyethylene and polypropylene layers. The Nylon layer is very difficult for the cushioning medium to flow through, whereas the polyethylene and polypropylene layers are easy to thermally weld together. 
         [0032]    The first lengthwise end of each cushioning medium storage portion  3  is provided with a check valve  4 , which is positioned across the border between the cushioning medium storage portion  3  and the corresponding cushioning medium entrance  5 . This check valve  4  is for allowing the air to pass only in the direction to enter the cushioning medium storage portion  3 . That is, once the air is introduced into the cushioning medium storage portion  3 , the check valve  4  utilizes the air pressure in the cushioning medium storage portion  3  to prevent the air in the cushioning medium storage portion  3  from flowing backward, that is, toward the air entrance  5 , as shown in  FIG. 2 , which is a sectional view of one of the cushioning units of the packaging material S 1 , at Line B-B in  FIG. 1 .  FIG. 3  is an enlarged sectional view of the combination of the cushioning medium storage portion  3  and corresponding air entrance  5 . 
         [0033]    The details of the structure of the check valve  4  are as shown in  FIGS. 2 and 3 . The check valve  4  is manufactured through the following steps. To the film  2 , the top and bottom check valves  4   a  and  4   b  are thermally welded in advance by the welding areas  12   a - 12   c.  Incidentally, the top and bottom check valves  4   a  and  4   b  are also formed of plastic film. 
         [0034]    Referring again to  FIGS. 1 and 2 , when the films  1  and  2  are welded to each other to form the packaging material S 1 , the top check valve  4   a  is attached to the air entrance portion ( 5 ) of the film  1  by the welding area  10 , whereas the bottom check valve  4   b  is attached to the film  2  by the welding area  10 . The top check valve  4   a  is provided with a seal portion  4   a   1 , which is coated or printed on the top check valve  4   a.  The seal portion  4   a   1  is formed of a material which does not melt at the temperature level at which the two films  1  and  2  are welded across the welding areas  8  and  10 . Therefore, even if heat is applied to the films  1  and  2  across the welding area  10 , it does not occur that the top and bottom check valves  4   a  and  4   b  become welded to each other. Further, even in the welding areas  8 , which is the border area between the air entrance  5  and cushioning medium storage portion  3 , the portions of the top and bottom check valves  4   a  and  4   b,  across which the sealing portion  4   a   1  is present, do not become welded to each other. Therefore, an air passage P 1 , which allows the external air to enter the cushioning medium storage portion  3  through the air entrance  5 , remains secured. Incidentally, the sealing portion  4   a   1  may be coated or printed on the bottom check valve  4   b  instead of the top check valve  4   a.  Even if the sealing portion  4   a   1  is attached to the bottom check valve  4   b,  its functions and performance remains the same. 
         [0035]    The lengthwise direction of the cushioning medium storage portion  3  is roughly the same as the direction in which the air passes through the check valve  4 , enabling therefore the air to be efficiently introduced into the cushioning medium storage portion  3 . 
         [0036]    Next, referring to  FIG. 1 , the width W 1  of each of the air injection openings  11  is narrower than the width W 2  of the border area (connective area) between the cushioning medium storage portion  3  and air entrance  5 . Further, the multiple air injection openings  11  are positioned so that there is virtually no gap between the adjacent two air injection openings  11 , making it possible to reduce in size the air injecting portion of an air injecting apparatus (unshown) for injecting the air into all the air injection openings  11  at the same time. Further, the direction in which the cushioning medium passes through the check valve  4  toward the cushioning medium storage portion  3  is made roughly the same as the direction in which the cushioning medium is introduced through the air injection openings. Therefore, the air is efficiently introduced into the cushioning medium storage portion  3 . Further, because of the above-described structural arrangement, the welding area  7  between the adjacent two air injection openings  11  is tilted, relative to the lengthwise direction of the cushioning medium storage portion, from the border area between the cushioning medium storage portion  3  and the corresponding air entrance  5  toward the central air injection opening  11 . 
       (Detailed Description of Check Valve Structure) 
       [0037]    Here, the welding areas  12   a - 12   c,  across which the top and bottom check valves  4   a  and  4   b  are thermally welded to the film  2  will be described regarding their shapes. 
         [0038]    Referring to  FIG. 4 , a cushioning medium (air) passage  20  for introducing air into the cushioning medium storage portion  3  is formed by thermally welding the top and bottom check valves  4   a  and  4   b  to the film  2  across the welding areas  12   a - 12   c.  Obviously, the width of the cushioning medium (air) passage  20  is less than the width of the check valves  4   a  and  4   b.  Referring to  FIG. 5 , the cushioning medium (air) passage  20  is formed between the top and bottom check valves  4   a  and  4   b,  and it is also obvious that the width of the cushioning medium (air) passage  20  is less than that of the cushioning medium storage portion  3 . That is, as air passes through the cushioning medium (air) passage  20 , the top check valve  4   a  becomes shaped as drawn with double-dot chain lines in  FIG. 5 , which is a sectional view of one of the multiple cushioning units, at Plane A-A in  FIG. 3 . Referring to  FIG. 4 , the cushioning medium (air) passage  20  has a primary portion  20   c,  and wide portions  20   a  and  20   b.  The wide portions  20   a  and  20   b  extend from the primary portion  20   c  in the direction perpendicular to the lengthwise direction of the cushioning medium storage portion  3 . 
         [0039]    The primary portion  20   c  of the cushioning medium passage  20  is formed in the direction parallel to the lengthwise direction of the cushioning medium storage portion  30 . It is the cushioning medium passage for guiding air in the lengthwise direction of the cushioning medium storage portion, and is less in width than the check valves  4   a  and  4   b.  It is formed by the welded areas  12   a   1 ,  12   a   2 ,  12   a   6 , and  12   a   10 , and welding areas  12   b   1 ,  12   b   2 ,  12   b   6 , and  12   b   10 , respectively. Further, the wide portions  20   a  are formed of the portions  12   a   3 - 12   a   5 , and portions  12   a   7 - 12   a   9 , of the welded portion  12   a,  which extend in the direction intersectional to the lengthwise direction of the cushioning medium storage portion  3 . Further, the wide portions  20   b  are formed of the portions  12   a   3 - 12   b   5 , and portions  12   b   7 - 12   b   9 , of the welded portion  12   b,  which extend in the direction intersectional to the lengthwise direction of the cushioning medium storage portion  3 . The presence of these wide portions  20   a  and  20   b  ensures that the check valves  4   a  and  4   b  remain airtightly in contact with each other even after the entering of air into the cushioning medium storage portion  3 , preventing thereby the air from flowing backward. 
         [0040]      FIG. 6  is a cross-sectional view of the cushioning medium storage portion  103  of a comparative packaging material, the cushioning medium passage of which does not have the wide portions. As the cushioning medium storage portion  103  is filled with air, the films  101  and  102  become arcuate in such a manner that the films  102  and  101  are smallest and largest, respectively, in curvature, as shown in  FIG. 6 . However, the top and bottom valves  104   a  and  104   b  are welded in advance while the film  102  is flat, as described above. Thus, as the cushioning medium storage portion  3  is filled with air, the portions  104   a   1  and  104   b   1  of the top and bottom check valves  104   a  and  104   b,  respectively, are made loose from the film  102  and bend inward of the cushioning medium storage portion  3 . As a result, the state of contact between the top and bottom check valves  104   a  and  104   b  becomes less airtight. 
         [0041]    Referring to  FIG. 4 , in order to prevent the occurrence of the above-described problem, the packaging material in this embodiment is provided with welded portions  12   a   3 ,  12   a   5 ,  12   a   7 ,  12   a   9 ,  12   b   3 ,  12   b   5 ,  12   b   7 , and  12   b   9 . The provision of the abovementioned welded portions, which extend in the direction intersectional to the lengthwise direction of the cushioning medium storage portion  3  generates such a force that works in the direction intersectional to the lengthwise direction of the cushioning medium storage  3 , that is, the direction to extend the top and bottom check valves  4   a  and  4   b  in the direction intersectional to the lengthwise direction of the cushioning medium storage  3 . Therefore, the top and bottom check valves  4   a  and  4   b  are not made loose like the portions  104   a   1  and  104   b   1  of the top and bottom check valves  104   a  and  104   b  of the comparative packaging material ( FIG. 6 ) as shown in  FIG. 5 . Therefore, it is ensured that the top and bottom check valves  4   a  and  4   b  remain airtightly in contact with each other. In this embodiment, the cushioning medium passage  20  is provided with two wide portions  20   a  and  20   b  on each side of the primary portion  20   c.  However, the wide portion count on each side may be only one. Further, there is a regulating portion  12   c  on the downstream side of the outlet  20   c   1  of the primary portion  20   c  of the cushioning medium passage  20 . The regulating portion  12   c  turns the air low so that the air flows in the widthwise direction of the cushioning medium storage portion  3 . It is also formed by welding in advance the top and bottom check valves  4   a  and  4   b  to the film  2 . The regulating portion  12   c,  which is formed by welding, also extends in the direction intersectional to the lengthwise direction of the cushioning medium storage portion  3 . Therefore, it also functions to ensure that the top and bottom check valves  4   a  and  4   b  remain airtightly in contact with each other. With the regulating portion  12   c  being structured as described above, as the external introduced through the air entrance  5  is smoothly filled into the cushioning medium storage portion  3 ; the provision of the regulating portion  12   c  does not interfere with the efficiency with which the external air is introduced into the cushioning medium storage portion  3 . Further, since the regulating portion  12   c  changes the direction of the air flow on the downstream side of the outlet  20   c   1  of the primary portion  20   c  of the cushioning medium passage  20  so that the air flows in the widthwise direction of the cushioning medium storage portion  30 , it improves the check valves  4  in terms of the prevention of the back flow of the air from the cushioning medium storage portion  3 . 
         [0000]    (Method for Wrapping Cartridge with Packaging Material) 
         [0042]    Hereafter, referring to  FIGS. 7-13 , the method for wrapping a process cartridge, which is removably mountable in the main assembly of an electrophotographic image forming apparatus, with the packaging material S will be described. Here, an electrophotographic image forming apparatus is an apparatus for forming an image on recording medium, with the use of an electrophotographic image forming method. The examples of an electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (laser beam printer, LED printer, etc., for example), a facsimile apparatus, a wordprocessor, etc. A process cartridge is a cartridge in which at least one processing means among a charging means, a developing means, and a cleaning means, and an electrophotographic photosensitive member, are integrally disposed, and which is removably mountable in the main assembly of an image forming apparatus. 
         [0000]    (1) Separation of Packaging Material S 1  from Roll of Packaging Material S by Cutting 
         [0043]    The packaging material S 1 , that is, a piece of packaging material S, which is wide enough to completely wrap (package) a process cartridge  35  (which will be described later), is cut away from a long roll of packaging material S, which is made up of multiple packaging units having the above described cushioning medium storage portion, check valve  4 , and cushioning medium (air) entrance  5 . In the case of the packaging material S in this embodiment, a pair of scissors K 1  is used to cut the packaging material S to obtain the packaging material S 1  with a proper width. However, a cutter, or a cutting apparatus dedicated to the cutting of the packaging material S, may be used to cut the packaging material S. There is a metallic rod K 2  in the center of the roll of packaging material S, making it easier to unroll the roll of packaging material S by a necessary length, and also, to cut the packaging material S. Moreover, the presence of the metallic rod K 2  makes it easier to set the roll of packaging material S in a preset position of the automatic cutting machine or the like, to cut the packaging material S. 
         [0000]    (2) Processing of Packaging Material S 1  into Pouch ( FIGS. 8-10 ) 
         [0044]    After the cutting of the packaging material S 1  away from the roll of the packaging material S, the packaging material S 1  is folded in half roughly at the center line in terms of the lengthwise direction of the cushioning medium storage portion  3  so that the rear end portion  53  of the cushioning medium storage portion  3 , in terms of the lengthwise direction of the cushioning medium storage portion  3 , is placed in the position shown in  FIG. 8 . 
         [0045]    Then, the top and bottom layers of the folded packaging material S 1  are thermally welded together along both edges (welding areas  12  and  13 ) in terms of the direction perpendicular to the lengthwise direction of the cushioning medium storage portion  3 , as shown in  FIG. 9 . As a result, the packaging material S 1  becomes a pouch, which is open at one of its lengthwise ends. The welding areas  12  and  13  extend in the lengthwise direction of the cushioning medium storage portion  3 . 
         [0000]    (3) Insertion of Cartridge  35  (Object to be Packaged) into Pouch Made of Packaging Material S 1  ( FIG. 10 ) 
         [0046]    Referring to  FIG. 10 , the cartridge  35 , which is the object to be packaged, is to be inserted into the pouch through an opening with which one of the lengthwise end of the pouch is provided. That is, the cartridge  35  is inserted so that its lengthwise direction matches the lengthwise direction of the cushioning medium storage portion  3 . 
         [0047]    Then, the opening  18  is sealed by thermally welding the top and bottom layers of the packaging material S 1  across the welding area  14 , as shown in  FIG. 23 , to prevent the cartridge  35  from popping out of the pouch during the cartridge shipment. The location of the welding area  14  is to be selected so that its position overlaps with the sealing portion  4   a   1 , which was described referring to  FIG. 2 . Welding the top and bottom layers of the packaging material S 1  so that the welding seam runs across the sealing portion  4   a   1  makes it possible to inject the cushioning medium into the cushioning medium storage portion  3  even after the closing of the opening  18 . 
       (4) Injection of Cushioning Medium (FIG. 9) 
       [0048]    Thereafter, the air, which is the cushioning medium in this embodiment, is to be injected into all the cushioning medium storage portions  3  through the cushioning medium injection openings  11  of the cushioning medium (air) entrances  5 ; the air is introduced into each of the cushioning medium storage portions  3  through the corresponding check valve  4 . The reason why the air is introduced after the placement of the cartridge  35  in the pouch made of the packaging material S 1  is that the air introduction into each cushioning medium storage portion  3  inflates the cushioning medium storage portion  3 , which in turn reduces the pouch in internal measurements, which in turn makes it virtually impossible to insert the cartridge  35  into the pouch. In other words, by injecting the air into the cushioning medium storage portions  3  after the insertion of the cartridge  35  into the pouch, the cartridge  35  is securely held in the pouch. Incidentally, in this embodiment, it is air that is introduced as the cushioning medium into the cushioning medium storage portions  3 . However, the cushioning medium selection does not need to be limited to the air. That is, the cushioning medium may be nitrogen gas, oxygen gas, or the like. Nitrogen gas may be a good choice because nitrogen is large in molecular weight, being therefore unlikely to leak from the cushioning medium storage portion  3 , which is made of plastic film or the like. Further, the cushioning medium may be a liquid or a fluid substance other than gaseous substances. 
         [0049]    Next, referring to  FIG. 24 , lastly, the cushioning medium (air) entrances  5  and cushioning medium storage portions  3  are to be completely sealed by welding shut the cushioning medium injection opening  11  ( FIGS. 11 and 19 ) across the welding area  15 . 
       Embodiment 2 
     (Packaging Material Structure) 
       [0050]    In the first preferred embodiment, the check valve  4  had two portions, that is, the top and bottom check valves  4   a  and  4   b.  In this embodiment, however, the check valve  4  has only one valve  4   d.    
         [0051]      FIG. 11  is a plan of one of the multiple cushioning units of packaging material S 1 , as seen from the direction perpendicular to the lengthwise direction of the unit. It shows the central cushioning medium entrance  5  and corresponding cushioning medium storage portion  3 .  FIG. 12  is a sectional view of one of the multiple cushioning units of packaging material S 1 , shown in  FIG. 11 , at Plane C-C in  FIG. 11 , after the introduction of the air into the unit. 
         [0052]    Referring to  FIG. 11 , the film  2  has the check valve  4   d,  which was welded in advance to the film  2  by thermally melting the film  2  across welding areas  12   a - 12   c.    
         [0053]    More specifically, referring to  FIGS. 11 and 12 , when the films  1  and  2  are welded to each other to create the packaging material S, the check valve  4   d  is welded to the film  2  across the welding area  10 , in the cushioning medium entrance  5 . The check valve  4   d  has a sealing portion  4   d   1  made up of a material which does not melt even at the temperature level at which the films  1  and  2  are thermally welded to each other across the welding areas  8  and  9 . The sealing portion  4   d   1  is coated or printed on the check valve  4   d.  Therefore, even if heat is applied to the films  1  and  2  across the welding area  10 , it does not occur that the check valve  4   d  and film  2  becomes welded to each other. Further, even across the welding area  8 , which is the border between the cushioning medium (air) entrance  5  and cushioning medium storage portion  3 , it does not occur that the check valve  4   d  becomes welded to the film  2 , making it possible to secure a passage P 2  through which the air is allowed to enter the cushioning medium storage portion  3  from the cushioning medium (air) entrance  5 . This sealing portion  4   d   1  does not need to be a part of the check valve  4   d;  it may be coated or printed on the film  2 . Even if the sealing portion  4   d   1  is made as a part of the film  2 , its functions remain the same. 
       (Detailed Description of Check Valve Structure) 
       [0054]    The welding areas  12   a - 12   c,  across which the check valve  4   d  is thermally welded to the film  2  are the same in shape as those in the first preferred embodiment. As the check valve  4   d  is thermally welded to the film  2  across the welding areas  12   a - 12   c,  a passage  20  for introducing the air into the cushioning medium storage portion  3  is formed between the check valve  4   d and film  2 . Referring to  FIG. 13 , the width of this passage  20  is obviously less than that of the cushioning medium storage portion  3 , and is formed between the check valve  4   d  and the film  2 . That is, when the air passes through the passage  20 , the check valve  4   d  becomes shaped as indicated by a pair of double-dot chain lines as shown in  FIG. 13 , which is a cross-sectional view of the single cushioning unit, at Plane D-D in  FIG. 11 . 
         [0055]      FIG. 14  is a cross-sectional view of the cushioning medium storage portion  203  of a comparative packaging material, the cushioning medium passage portion of which has no wide portion. As the cushioning medium storage portion  203  is filled with the air, the films  201  and  202  are arcuately bent as shown in  FIG. 14 , in such a manner that the film  202  and check valve  204   d  become smallest and largest, respectively, in curvature. However, the check valve  204   d  is welded in advance when the film  202  is flat, as described before. Therefore, as the cushioning medium storage portion  203  is filled with the air, the check valve  204   d  is made to loosely bent inward of the cushioning medium storage portion  203  across its portion  204   d   1 . As a result, the check valve  204   d  fails to remain airtightly in contact with the film  202 . 
         [0056]    In order to prevent the occurrence of this problem, the films  1  and  2  in this embodiment are welded to each other across the welding areas  12   a   3 ,  12   a   5 ,  12   a   7 ,  12   a   9 ,  12   b   3 , and  12   b   5 ,  12   b   7 , and  12   b   9  of each of the cushioning units of the cushioning material, as the films  1  and  2  in the first preferred embodiment are welded to each other as shown in  FIG. 4 . The provision of the welded portions which extend in the direction intersectional to the lengthwise direction of the cushioning medium storage portion  3  generates such a force that works in the direction to extend the check valve  4  in the direction intersectional to the lengthwise direction of the cushioning medium storage portion  3 . Thus, the provision of the welded portions can keep the interface between the check valve  4  and film  2  airtightly sealed as shown in  FIG. 13 ; it prevents the formation of loose portions, such as those formed in the case of the comparative example as shown in  FIG. 14 . In other words, it keeps the check valve  4   d  and film  2  airtightly in contact with each other. The other structural features and effects are the same as those of the packaging material in the first preferred embodiment. 
       Embodiment 3 
     (Packaging Material Structure) 
       [0057]    In the first preferred embodiment, there was only one cushioning medium passage  20 . The third preferred embodiment is characterized in that each cushioning unit is provided with two cushioning medium passages  21  and  22 . Referring to  FIGS. 15 and 16 , the patterns of the welding areas  24   a - 24   c  across which the check valve  4   e  is thermally welded to the film  2  are such that each cushioning unit is provided with the two cushioning medium passages  21  and  22 , which are positioned side by side. However, the central welding area  24   b  is integration of the welding areas  12   a  and  12   b  in the first preferred embodiment, and is shaped as such. 
         [0058]    To describe in more detail, the primary portion  21   c  of the passage  21  is created by welded portions  24   a   1 ,  24   a   2 ,  24   a   6 , and  24   a   10 , and welded portions  24   b   1 ,  24   b   2 ,  24   b   6 , and  24   b   10 . The primary portion  22   c  of the passage  22  is created by welded portions  24   c   1 ,  24   c   2 ,  24   c   6 , and  24   c   10 , and welded portions  24   b   1 ,  24   b   2 ,  24   b   6 , and  24   b   10 . Thus, in order to form this wide portion  21 b of the passage  21 , the welding area  24   a  is made up of portions  24   a   3 - 24   a   5 , and portions  24   a   7 - 24   a   9 , whereas the welding area  24   b  is made up of portions  24   b   3 - 24   b   5 , and portions  24   b   7 - 24   b   9 . Further, in order to form the wide portions  22   b  of the passage  22 , the welding area  24   c  is made up of portions  24   c   3 - 24   c   5 , and portions  24   c   7 - 24   c   9 , and the welding area  24   b  is provided with portions  24   b   3 - 24   b   5 , and portions  24   b   7 - 24   b   9 . 
         [0059]    Further, the check valve  4   e  is welded across the areas  23   c   1  and  23   c   2 , which are on the downstream end sides of the primary portion  21   c  and  22   c,  respectively, creating a pair of cushioning medium flow regulating portions  23   c   1  and  23   c   2 . The provision of two cushioning medium passages  21  and  22  improves each cushioning unit in cushioning medium injection efficiency. Incidentally, the number of the cushioning medium passages does not need to be limited to two; it may be three or more. 
         [0060]    The other structural features of this embodiment of packaging material in accordance with the present invention are the same as those of the first preferred embodiment. 
       Embodiment 4 
     (Packaging Material Structure) 
       [0061]      FIG. 17  is a plan of one of the multiple cushioning units of the packaging material, as seen from above.  FIG. 18  is a sectional view of one of the multiple cushioning units of the packaging material, which is inflated with air, at Plane H-H in  FIG. 17 .  FIG. 19  is a sectional view of one of the multiple cushioning units of the packaging material, which is inflated with air, at Plane G-G in  FIG. 17 . 
         [0062]    The reason why the check valve in this preferred embodiment is made up of a top check valve  4   f  and a bottom check valve  4   g  is the same as the check valve in the first preferred embodiment is made up of the top and bottom check valves  4   a  and  4   b.  Further, the manner in which the top and bottom check valves  4   f  and  4   g  are thermally welded in advance to the film  2  across the welding areas  12   a - 12   c  of the cushioning medium storage portion  3  is the same as the manner in which the top and bottom check valves  4   a  and  4   b  are thermally welded to the film  2  in the first preferred embodiment. 
         [0063]    The fourth preferred embodiment is different from the first preferred embodiment only in that the packaging material in the fourth embodiment is not provided with a cushioning medium entrance passage, and that the top and bottom check valves  4   f  and  4   g  themselves have the function of the cushioning medium entrances. That is, the top and bottom check valves  4   f  and  4   g  are welded to the film  2  not only across the welding areas  34   a - 34   c,  but also, across the welding areas  34   d - 34   e,  being thereby provided with a cushioning medium (air) injection opening  34   g.  Thus, the air is directly injected into the top and bottom check valves  4   g  and  4   g.  Therefore, the packaging material in this embodiment is superior in cushioning medium injection efficiency to those in the preceding embodiments. 
         [0064]    The shape of the cushioning medium (air) passage  34   f  is the same as that in the first embodiment. 
       Embodiment 5 
       [0065]    The fifth preferred embodiment is different from the preceding embodiments in the shape of the cushioning medium passage. The various shapes for the cushioning medium passage in the fifth embodiments are shown in  FIGS. 20-22 . Basically, each of the primary portions  25   d - 32   d  of cushioning medium passages  25 - 32 , respectively, is made parallel to the lengthwise direction of the cushioning medium storage portion  3 . It is the passage formed between two check valves, or between a check valve and film  2 , to guide the air in the lengthwise direction of the cushioning medium storage portion  3 . Each of the cushioning medium passages  25 - 32  in this embodiment is provided with portions wider than the primary portions  25   d - 32   d.  In order to form these wider portions, the check valve is welded to the film  2  across the welding areas, which extend in the directions intersectional to the lengthwise direction of the cushioning medium storage portion  3 . Further, cushioning medium flow regulating portions  25   c - 32   c  for causing the air to flow in the widthwise direction of the cushioning medium storage portion  3  are provided on the downstream side of the outlet of the primary portions  25   d - 32   d.  These cushioning medium flow regulating portions  25   c - 32   c  are also formed by welding the check valve, or check valves, to the film  2 . They are also provided with the portions which extend in the direction intersectional to the lengthwise direction of the cushioning medium storage portion. 
         [0066]    When manufacturing the packaging material for a process cartridge by welding two pieces of film together, devising in pattern the area, or areas, of one of the films, across which the check valve, or check valves, are welded, can make it difficult for the cushioning medium to leak from the cushioning medium storage portion, and also, can make it easier for the cushioning medium to be injected into the cushioning medium storage portion. Further, it makes it simpler to form the check valve. 
         [0067]    While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims. 
         [0068]    This application claims priority from Japanese Patent Application No. 241019/2008 filed Sep. 19, 2008, which is hereby incorporated by reference.