Toner accomodation chamber and process cartridge

Abstract: A toner accommodation container includes a toner containing portion for containing toner; a toner filling opening, formed in a side surface of said toner containing portion, for filling the toner into said toner containing portion; wherein said filling opening has a non- circular configuration substantially corresponding to a configuration of said side surface.

Description: FIELD OF THE INVENTION AND RELATED ART The present invention relates to a toner accomodation chamber, and a process cartridge. Here, the process cartridge means a cartridge having as a unit an electrophotographic photosensitive member, and charging means, developing means and cleaning means, which is detachably mountable to a main assembly of an electrophotographic image forming apparatus. It may include as a unit an electrophotographic photosensitive member and at least one of charging means, developing means and cleaning means. It may include as a unit developing means and an electrophotographic photosensitive member. And, the electrophotographic image forming apparatus forms an image on a recording material using an electrophotographic image formation process. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (laser beam printer, LED printer or the like), a facsimile machine and a word processor or the like. An electrophotographic image forming apparatus using an electrophotographic process is known which is used with the process cartridge. This is advantageous in that the maintenance operation can be, in effect, carried out by the users thereof without expert service persons, and therefore, the operativity can be remarkably improved. Therefore, this type is now widely used. In an electrophotographic image forming apparatus, a latent image formed on an electrophotographic photosensitive member is developed with the use of developer (hereinafter, "toner"). Since toner is consumed through an image forming process, it must be replenished as needed. For the replenishment of toner, a toner storing container (hereinafter, "toner container") is used. A toner container can be used to replenish a copying machine or the like, as well as the aforementioned process cartridge, with toner, through a simple action. A toner container is provided with a toner filling opening which is sealed with a toner container cap (hereinafter, "container cap"). Generally, a container cap is formed of low density polyethylene (hereinafter, "LDPE") by injection molding. It comprises several ribs which extend between the sealing walls of the container cap and the center portion of the container cap, to reinforce the sealing walls which seal the toner container as they come in contact with the brim portion of the toner filling opening of the toner container. SUMMARY OF THE INVENTION The primary object of the present invention is "to provide a toner accomodation chamber and a plug (cap) capable of securely sealing a toner filling opening, and a process cartridge which employs such a toner accomodation chamber (container). Another object of the present invention is to provide a toner container cap which is not liable to accidentally be dislodged from the toner filling opening of a toner container, a toner container which employs such a toner container cap, and a process cartridge which employs such a toner container. Another object of the present invention is to provide a toner container cap which makes it possible to provide one of the side walls of a toner container with such a toner filling opening that has an effective opening area which is larger than, or at least as large as, the largest effective opening area which can be created using the conventional circular configuration, and which can improve efficiency in toner filling. Another object of the present invention is to provide a toner container with a noncircular toner with a filling opening which corresponds to the configuration of the end wall of the toner container, and a process cartridge which employs such a toner container. These and other objects, features and advantages of the present invention will become more apparent upon a 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 Figure 1 is a perspective view of the main structure of the toner container in the first embodiment of the present invention. Figure 2 presents front and side views of the cap for the toner filling opening in the first embodiment of the present invention. Figure 3 is a perspective view of the main structure of the toner container in the second embodiment of the present invention. Figure 4 presents front and side views of the cap for the toner filling opening in the second embodiment of the present invention. Figure 5 is a perspective view of the main structure of the toner container in the third and fourth embodiments of the present invention. Figure 6 presents front and side views of the cap for the toner filling opening in the third embodiment of the present invention. Figure 7 presents front and side views of the cap for the toner filling opening in the fourth embodiment of the present invention. Figure 8 is a perspective view of the main structure of the toner container in a comparative embodiment. Figure 9 presents front and side view of the cap for the toner filling opening of the comparative toner container. Figure 10 is a schematic drawing which depicts a toner container, and an auger-type toner filling apparatus which is used for toner filling tests. Figure 11 is a side elevation of an electrophotographic image forming apparatus (laser beam printer) to which the present invention is applicable. Figure 12 is an external perspective view of the apparatus illustrated in Figure 11. Figure 13 is a cross-section of a process cartridge usable with the electrophotographic image forming apparatus illustrated in Figure 11. Figure 14 is an external perspective view of the process cartridge illustrated in Figure 13. Figure 15 is a right-hand side view of the process cartridge illustrated in Figure 13. Figure 16 is a left-hand side view of the process cartridge illustrated in Figure 13. Figure 17 is an external perspective view of the process cartridge illustrated in Figure 13, as seen from the left side. Figure 18 is an external perspective view of the process cartridge illustrated in Figure 13, as seen from the bottom right. Figure 19 is a perspective view of the toner container portion of the frame of the process cartridge illustrated in Figure 13. Figure 20 is a perspective view of the developing station portion of the frame of the process cartridge illustrated in Figure 13. Figure 21 is a perspective view of the developing unit portion of the process cartridge illustrated in Figure 13. Figure 22 is a perspective view of the cleaning unit portion of the process cartridge illustrated in Figure 13. Figure 23 is a side view of the side plate of the developing station portion, and the toner container portion, of the process cartridge illustrated in Figure 13. Figure 24 is a perspective view of the toner container portion of the process cartridge illustrated in Figure 13. Figure 25 is a vertical section of the toner sealing portion of the toner container portion of the process cartridge illustrated in Figure 13. Figure 26 is a perspective view of a cap for a toner container. Figure 27 is a section of the toner container cap illustrated in Figure 26. Figure 28 is a top view of the toner container cap illustrated in Figure 26. Figure 29 is a section of a portion of the toner filling opening of the toner container portion of the main structure of the process cartridge illustrated in Figure 13. Figure 30 is a section of a portion of the toner container cap, which engages with the edge of the toner filling opening. Figure 31 is a section of the joint between a toner container cap and the edge of the toner filling opening of the toner container portion. Figure 32 is a section of a portion of a toner container cap, which engages with the edge of the toner filling opening, in a comparative embodiment. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the embodiments of a toner container cap and a toner container in accordance with the present invention, and comparative embodiments thereof, will be described in detail with reference to the drawings. Embodiment 1 The first embodiment of the toner container in accordance with the present invention will be described with reference to Figures 1 and 2. As is evident from Figures 1 and 2, the toner container in this embodiment has a toner filling opening 112 in one of the side walls of the main structure 111, and this opening 112 is sealed with a cap 113, which has substantially the same configuration as that of the opening 112, and is pressed into the opening 112. The contour of the opening 112 is noncircular; it forms compound curvature composed of a combination of various arcs, and naturally, the external contour of the cap 113 forms substantially the same compound curvature. The toner container in this embodiment, as well as the toner containers in the rest of the embodiments and comparative embodiments, are formed of highly impact resistant polystyrene by injection molding. Further, the toner filling opening caps in the following embodiments and comparative embodiments are formed of low density polyethylene or polypropylene by injection molding. However, polypropylene is more desirable as the cap material than low density polyethylene. This is because the stress, which occurs when a cap is pressed into the toner filling opening of a toner container to seal the toner filling opening, is liable to act more on the edge of the toner filling opening than on the cap, and also, because, in the case of a noncircular cap, more attention must be paid to the balance (distribution) of the stress which acts on the cap, than in the case of a circular cap. The capacity of the actual container portion 111, that is, the main structure of the toner container, in this embodiment, excluding the toner filling opening portion, is 691 cc. The capacities of the actual container portions 111 in the rest of the embodiments and the comparative embodiments are the same as the capacity of the actual container portion 111 in this embodiment. Embodiment 2 Next, referring to Figures 3 and 4, different embodiments of the toner container in accordance with the present invention will be described. The toner container in this embodiment has substantially the same structure as that described in the preceding embodiment, and therefore, only the different portions will be described. As is evident from Figures 3 and 4, the contour of the toner filling opening 122 in this embodiment is formed of a combination of straight lines, and arcs which connect the straight lines; in other words, it is substantially polygonal, and a cap 123 is also substantially polygonal. Embodiment 3 Next, referring to Figures 5 and 6, the third embodiment of the toner container in accordance with the present invention will be described. The third embodiment is substantially the same as the first and second embodiments, and therefore, only the different portions will be described. As illustrated in Figures 5 and 6, a toner filling opening 132 is substantially triangular, with the apex portions being rounded, and the contour of a cap 133 is substantially the same as that of the opening 132. Embodiment 4 Next, referring to Figures 5 and 7, the fourth embodiment of the toner container in accordance with the present invention will be described. The toner filling opening of the toner container in this embodiment is the same as the toner filling opening 132 in the third embodiment, and therefore, only the different portions will be described. Referring to Figure 7, the toner container in this embodiment is sealed by pressing a cap 143, which is substantially the same in configuration as the toner filling opening 132 in the third embodiment, into a toner filling opening. The cap 143 is provided with ribs 144, each of which is perpendicularly extended inward from the corresponding side wall of the cap 143. In the above first to fourth embodiments, the effective areas of the toner filling openings 112, 122 and 132 are 860 mm 2 , which is approximately 95 % of the effective opening area 907.9 mm 2 of a conventional circular toner filling opening of the prior art; in other words, it is substantially the same as the effective opening area of the circular toner filling opening of the prior art. As far as the container main structures 111, 121 and 131 are concerned, they are the same in measurement and configuration, except for the toner filling opening portions. Comparative Embodiment 1 Next, referring to Figures 8 and 9, the toner container in the first comparative embodiment will be described. The descriptions of the portions of the toner container main structure in this comparative embodiment, which are the same as those in the first, second and third embodiments, will be omitted. As illustrated in Figures 8 and 9, the toner filling opening 152 in this embodiment is a circular opening, that is, a modified version of the toner filling opening portion of the container main structure 111, 121 and 131 in the first, second, third, or fourth embodiment, in terms of measurement and configuration. Even though an attempt was made to increase the effective area of the toner filling opening 152, a diameter of 25 mm was the largest possible; an effective area of 490.9 mm 2 was the largest. The container main structure 151 in this first comparative embodiment is the same as the container main structures 111, 121 and 131 in the first, second and third embodiments in measurement and configuration, except for the toner filling opening portions. [Toner Filling Speed Test] Toner was actually filled into each toner container described in the preceding embodiments. As for means to fill a toner container with toner, an auger type filling apparatus (Figure 10) was employed. The specifications of the auger are as follows. [Filling Condition 1] Screw revolution: 800 rpm Set pulse: 160,000 pulse External diameter of screw: 28 mm Screw pitch: 32 mm Diameter of screw shaft: 8 mm Internal diameter of filler nozzle: 30 mm [Filling Condition 2] Screw revolution: 400 rpm Remaining specifications are the same as those in the first condition. The toner used for the filling test was single component toner, having an average diameter of 8.5 µm. The amount of the filled toner was 380 g. The results of the filling test are given in the following table. FILLING CONDITIONS TIMES REQUIRED EVALUATION EMB. 1 1 3.6 sec. NO PROBLEM EMB. 2 1 3.6 sec. NO PROBLEM EMB. 3 1 3.6 sec. NO PROBLEM COMP.EMB.1 1 NOT POSSIBLE NOZZLE WAS CLOGGED; TONER WAS FUSED COMP.EMB.2 2 7.2 sec. SLOW SPEED (DOUBLE) As is evident from the table, there was no problem in the cases of the first to third embodiments, and the time it took to fill each container was 3.6 seconds. These results are substantially the same as those for a conventional circular toner filling opening. Further, it was examined whether or not the filler nozzle was clogged adjacent to the toner filling opening, whether or not coarse particles were created, or whether or not the like problems occurred, but no specific problem could be confirmed. On the contrary, in the cases of the first and second comparative embodiments, clogging occurred to the filler nozzle of the toner filling apparatus, causing the toner particles to fuse, under Filling Condition 1 under which the auger revolution was 800 rpm. Therefore, the auger revolution was gradually dropped in decrements of several revolutions from 800 rpm to confirm the number of revolution at which no clogging occurred. The confirmed result was that toner could be filled at 400 rpm without clogging the nozzle. Then, in order to confirm this finding, another toner filling test was conducted using Filling Condition 2 in which the auger revolution was 400 rpm. In this case, filling took 7.2 seconds, which is twice the filling time for the embodiments of the present invention, which is not satisfactory. [Drop Test] In this test, the toner containers described in the first to fourth embodiments were dropped to test whether or not the cap of any of the toner containers became loose, or whether or not toner leaked from any of the toner containers. Dropping Conditions: First, each container was dropped from a height of 90 cm, and then, the height was gradually increased when the preceding drop did not cause any problem. Each container was tested by dropping it once on the corner, three times on the edge, and six times on the wall surface. State of Packaging: Five toner containers were tested for each embodiment, wherein each container was individually packaged. The result was that the loosening of the cap, and toner leak, did not occur in any of the toner containers in the first to fourth embodiments. Further, when the toner containers were dropped from a height of 110 cm, toner leak occurred in the toner containers in the first to third embodiments, at the joint between the toner container cap and the edge of the toner filling opening, but the amount of the toner leak was small enough to create no practical problem. In the case of the toner container in the fourth embodiment, no problem occurred even when it was dropped from the height of 110 cm. The results of the above described filling and dropping tests prove that the toner containers in the first to fourth embodiments have no practical problem in terms of efficiency in toner filling and effectiveness in toner sealing. As described above, according to the preceding embodiments, the level of control in terms of cap dimension can be eased when the contour of the toner filling opening of a toner container is rendered polygonal, compared to when it is rendered noncircular without having straight portions. Further, when the toner filling opening is rendered substantially triangular, the toner filling opening can be expanded into even the narrow corner area of the side wall of the container main structure, and therefore, the effective area of the toner filling opening can be rendered equal to, or larger than, those of the conventional toner filling openings. In other words, the toner filling opening in accordance with the present invention is superior to the conventional round toner filling opening, in terms of efficiency in toner filling. The above described toner filling opening is sealed by pressing into it a polygonal cap having substantially the same contour as the toner filling opening. Further, the polygonal cap is provided with ribs, each of which perpendicularly projects inward from the corresponding sealing wall of the cap, and therefore, the straight portions of the sealing walls of the polygonal cap are prevented from being bent by the stress which occurs in the straight portions of the sealing walls as the cap is pressed into the toner filling opening. Thus, the toner container cap with the ribs can further improve the level of effectiveness in sealing the toner filling opening. Further, when the toner containing portion of a process cartridge is structured as the above described toner container, the process cartridge is improved in terms of compactness, efficiency in toner filling, and efficiency in process cartridge manufacture. As is evident from the preceding embodiments, according to the present invention, the toner filling opening of a toner container is rendered correspondent to the configuration of the side wall of a toner container, and therefore, certain portions of the toner container wall, which cannot be utilized when the configuration of a toner filling opening is round as is the configuration of a conventional toner filling opening, can be utilized to improve efficiency in toner filling, and also, effectiveness in sealing the toner container, as well as efficiency in toner container manufacture, can match or exceed those of the toner container with a round toner filling opening. Next, the embodiments of a process cartridge which employs the above described toner container cap and toner container will be described. In the following description, the "widthwise" direction of a process cartridge B means the direction in which the process cartridge B is installed into, or removed from, the main assembly of an image forming apparatus, and coincides with the direction in which a recording medium is conveyed. The "lengthwise" direction of the process cartridge B means a direction which is intersectional with (substantially perpendicular to) the direction in which the process cartridge B is installed into, or removed from, the main assembly 14. It is parallel to the surface of the recording medium, and intersectional with (substantially perpendicular to) the direction in which the recording medium is conveyed. Further, the "left" or "right" means the left or right relative to the direction in which the recording medium is conveyed, as seen from above. Figure 11 is an electrophotographic image forming apparatus (laser beam printer) which embodies the present invention, depicting the general structure thereof; Figure 12, an external perspective thereof; and Figures 13 - 18 are drawings of process cartridges which embody the present invention. More specifically, Figure 13 is a cross-section of a process cartridge; Figure 14, an external perspective view of the process cartridge; Figure 15, a right-hand side view of the process cartridge; Figure 16, a left-hand side view of the process cartridge; Figure 17, a perspective view of the process cartridge as seen from the top left direction; and Figure 18 is a perspective view of the process cartridge as seen from the bottom left direction. In the following description, the "top" surface of the process cartridge B means the surface which faces upward when the process cartridge B is in the main assembly 14 of the image forming apparatus, and the "bottom" surface means the surface which faces downward. (Electrophotographic Image Forming Apparatus A and Process Cartridge B) First, referring to Figures 11 and 12, a laser beam printer A as an electrophotographic image forming apparatus which embodies the present invention will be described. Figure 13 is a cross-section of a process cartridge which also embodies the present invention. Referring to Figure 11, the laser beam printer A is an apparatus which forms an image on a recording medium (for example, recording sheet, OHP sheet, and fabric) through an electrophotographic image forming process. It forms a toner image on an electrophotographic photosensitive drum (hereinafter, photosensitive drum) in the form of a drum. More specifically, the photosensitive drum is charged with the use of a charging means, and a laser beam modulated with the image data of a target image is projected from an optical means onto the charged peripheral surface of the photosensitive drum, forming thereon a latent image in accordance with the image data. This latent image is developed into a toner image by a developing means. Meanwhile, a recording medium 2 placed in a sheet feeding cassette 3a is reversed and conveyed by a pickup roller 3b, a conveyer roller pairs 3c and 3d, and register roller pair 3e, in synchronism with the toner formation. Then, voltage is applied to an image transferring roller 4 as a means for transferring the toner image formed on the photosensitive drum 7 of the process cartridge B, whereby the toner image is transferred onto the recording medium 2. Thereafter, the recording medium 2, onto which the toner image has been transferred, is conveyed to a fixing means 5 by guiding conveyer 3f. The fixing means 5 has a driving roller 5c, and a fixing roller 5b containing a heater 5a, and applies heat and pressure to the recording medium 2 as the recording medium 2 is passed through the fixing means 5, so that the image having been transferred onto the recording medium 2 is fixed to the recording medium 2. Then, the recording medium 2 is conveyed farther, and is discharged into a delivery tray 6 through a reversing path 3j, by discharging roller pairs 3q, 3h and 3i. The delivery tray 6 is located at the top of the main assembly 14 of the image forming apparatus A. It should be noted here that a pivotable flapper 3k may be operated in coordination with a discharge roller pair 3m to discharge the recording medium 2 without passing it through the reversing path 3j. The pickup roller 3b, conveyer roller pairs 3c and 3d, register roller pair 3e, guiding conveyer 3f, discharge roller pairs 3g, 3h and 3i, and discharge roller pair 3m constitute a conveying means 3. Referring to Figures 13 - 18, in the process cartridge B, on the other hand, the photosensitive drum 7 with a photosensitive layer 7e is rotated to uniformly charge its surface by applying voltage to the charging roller 8 as a photosensitive drum charging means. Then, a laser beam modulated with the image data is projected onto the photosensitive drum 7 from the optical system 1 through an exposure opening 1e, forming a latent image on the photosensitive drum 7. The thus formed latent image is developed with the use of toner and the developing means 9. More specifically, the charging roller 8 is disposed in contact with the photosensitive drum 7 to charge the photosensitive drum 7. It is rotated by the rotation of the photosensitive drum 7. The developing means 9 provides the peripheral surface area (area to be developed) of the photosensitive drum 7 with toner so that the latent image formed on the photosensitive drum 7 is developed. The optical system 1 comprises a laser diode 1a, a polygon mirror 1b, a lens 1c, and a deflective mirror 1d. In the developing means 9, the toner contained in a toner container 11A is delivered to an developing roller 9c by the rotation of a toner feeding member 9b. The developing roller 9c contains a stationary magnet. It is also rotated so that a layer of toner with triboelectric charge is formed on the peripheral surface of the developing roller 9c. The image developing area of the photosensitive drum 7 is provided with the toner from this toner layer, the toner is transferred onto the peripheral surface of the photosensitive drum 7 in a manner to reflect the latent image, visualizing the latent image as a toner image. The developing blade 9d is a blade which regulates the amount of the toner adhered to the peripheral surface of the developing roller 9c and also triboelectrically charges the toner. Adjacent to the developing roller 9c, a toner stirring member 9e is rotatively disposed to circulatively stir the toner within the image developing chamber. After the toner image formed on the photosensitive drum 7 is transferred onto the recording medium 2 by applying voltage with polarity opposite to that of the toner image to the image transferring roller 4, the residual toner on the photosensitive drum 7 is removed by the cleaning means 10. The cleaning means 10 comprises an elastic cleaning blade 10a disposed in contact with the photosensitive drum 7, and the toner remaining on the photosensitive drum 7 is scraped off by the elastic cleaning blade 10a, being collected into a waste toner collector 10b. The process cartridge B is formed in the following manner. First, a toner chamber frame 11 which comprises a toner container (toner storing portion) 11A for storing toner is joined with an image developing chamber frame 12 which houses the image developing means 9 such as an image developing roller 9c, and then, a cleaning chamber frame 13, in which the photosensitive drum 7, the cleaning means 10 such as the cleaning blade 10a, and the charging roller 8 are mounted, is joined with the preceding two frames 11 and 12 to complete the process cartridge B. The thus formed process cartridge B is removably installable into the main assembly 14 of the image forming apparatus A. The process cartridge B is provided with an exposure opening is through which a light beam modulated with image data is projected onto the photosensitive drum 7, and a transfer opening 13n through which the photosensitive drum 7 opposes the recording medium 2. The exposure opening 1e is a part of the cleaning chamber frame 13, and the transfer opening 13n is located between the image developing chamber frame 12 and the cleaning chamber frame 13. Next, the structure of the housing of the process cartridge B in this embodiment will be described. The process cartridge in this embodiment is formed in the following manner. First the toner chamber frame 11 and the image developing chamber frame 12 are joined, and then, the cleaning chamber frame 13 is rotatively joined with the preceding two frames 11 and 12 to complete the housing. In this housing, the aforementioned photosensitive drum 7, charging roller 8, developing means 9, cleaning means 10, and the like, are mounted to complete the process cartridge B. The thus formed process cartridge B is removably installable into the cartridge accommodating means provided in the main assembly 14 of an image forming apparatus. (Housing Structure of Process Cartridge B) As described above, the housing of the process cartridge B in this embodiment is formed by joining the toner chamber frame 11, the image developing chamber frame 12, and the cleaning chamber frame 13. Next, the structure of the thus formed housing will be described. Referring to Figures 13 and 19, in the toner chamber frame 11, the toner feeding member 9b is rotatively mounted. In the image developing chamber frame 12, the image developing roller 9c and the developing blade 9d are mounted, and adjacent to the developing roller 9c, the stirring member 9e is rotatively mounted to circulatively stir the toner within the image developing chamber. Referring to Figures 13 and 20, in the image developing chamber frame 12, a rod antenna 9h is mounted, extending in the lengthwise direction of the developing roller 9c substantially in parallel to the developing roller 9c. The toner chamber frame 11 and the development chamber frame 12, which are equipped in the above-described manner, are welded together (in this embodiment, by ultrasonic wave) to form a second frame which constitutes an image developing unit D (Figure 21). The image developing unit of the process cartridge B is provided with a drum shutter assembly 18, which covers the photosensitive drum 7 to prevent it from being exposed to light for an extended period of time or from coming in contact with foreign objects when or after the process cartridge B is removed from the main assembly 14 of an image forming apparatus. Referring to Figure 16, the drum shutter assembly 18 has a shutter cover 18a which covers or exposes the transfer opening 13n illustrated in Figure 13, and linking members 18b and 18c which support the shutter cover 18. On the upstream side relative to the direction in which the recording medium 2 is conveyed, one end of the right-hand side linking member 18c is fitted in a hole 40g of a developing means gear holder 40 as shown in Figures 14 and 15, and one end of the left-hand side linking member 18c is fitted in a boss 11h of the bottom portion 11b of the toner chamber frame 11. The other ends of the left- and right-hand linking members 18c are attached to the corresponding lengthwise ends of the shutter cover 18a, on the upstream side relative to the recording medium conveying direction. The linking member 18c is made of metallic rod. Actually, the left- and right-hand linking members 18c are connected through the shutter cover 18a; in other words, the left- and right-hand linking members 18c are the left- and right-hand ends of a single piece linking member 18c. The linking member 18b is provided only on one lengthwise end of the shutter cover 18a. One end of the linking member 18b is attached to the shutter cover 18a, on the downstream side, relative to the recording medium conveying direction, of the position at which the linking member 18c is attached to the shutter cover 18a, and the other end of the linking member 18b is fitted around a dowel 12d of the image development chamber frame 12. The linking member 18b is formed of synthetic resin. The linking members 18b and 18c, which are different in length, form a four piece linkage structure in conjunction with the shutter cover 18a and the toner chamber frame 11. As the process cartridge B is inserted into an image forming apparatus, the portion 18c1 of the linking member 18c, which projects away from the process cartridge B, comes in contact with the stationary contact member (unillustrated) provided on the lateral wall of the cartridge accommodating space S of the mains assembly 14 of the image forming apparatus, and activates the drum shutter assembly 18 to open the shutter cover 18a. The drum shutter assembly 18 constituted of the shutter cover 18a and the linking members 18b and 18c is loaded with the pressure from an unillustrated torsional coil spring fitted around a dowel 12d. One end of the spring is anchored to the linking member 18b, and the other end is anchored to the image developing chamber frame 12, so that the pressure is generated in the direction to cause the shutter cover 18a to cover the transfer opening 13n. Referring again to Figures 13 and 22, the cleaning means frame 13 is fitted with the photosensitive drum 7, the charging roller 8, and the various components of the cleaning means 10, to form a first frame as a cleaning unit C (Figure 22). Then, the aforementioned image developing unit D and cleaning unit C are joined with the use of a joining member 22, in a mutually pivotable manner, to complete the process cartridge B. More specifically, referring to Figure 21, both lengthwise (axial direction of the developing roller 9c) ends of the image developing chamber frame 12 are provided with an arm portion 19, which is provided with a round hole 20 which is in parallel to the developing roller 9c. On the other hand, a recessed portion 21 for accommodating the arm portion 19 is provided at each lengthwise end of the cleaning chamber frame (Figure 22). The arm portion 19 is inserted in this recessed portion 21, and the joining member 22 is pressed into the mounting hole 13e of the cleaning chamber frame 13, put through the hole 20 of the end portion of the arm portion 19, and pressed, farther, into the hole 13e of an partitioning wall 13t, so that the image developing unit D and the cleaning unit C are joined to be pivotable relative to each other about the joining member 22. In joining the image developing unit D and the cleaning unit C, a compression type coil spring 22a is placed between the two units, with one end of the coil spring being fitted around an unillustrated dowel erected from the base portion of the arm portion 19, and the other end being pressed against the top wall of the recessed portion 21 of the cleaning chamber frame 13. As a result, the image developing chamber frame 12 is pressed downward to reliably keep the developing roller 9c pressed downward toward the photosensitive drum 7. More specifically, referring to Figure 21, a roller 9i having a diameter larger than that of the developing roller 9c is attached to each lengthwise end of the developing roller 9c, and this roller 9i is pressed on the photosensitive drum 7 to maintain a predetermined gap (approximately 300 µm) between the photosensitive drum 7 and the developing roller 9c. The top surface of the recessed portion 21 of the cleaning chamber frame 13 is slanted so that the compression type coil spring 22a is gradually compressed when the image developing unit D and the cleaning unit C are united. That is, the image developing unit D and the cleaning unit C are pivotable toward each other about the joining member 22, wherein the positional relationship (gap) between the peripheral surface of the photosensitive drum 7 and the peripheral surface of the developing roller 9c is precisely maintained by the elastic force of the compression type coil spring 22a. Since the compression type coil spring 22a is attached to the base portion of the arm portion 19 of the image developing chamber frame 12, the elastic force of the compression type coil spring 22a affects nowhere but the base portion of the arm portion 19. In a case in which the image developing chamber frame 12 is provided with a dedicated spring mount for the compression type coil spring 22a, the adjacencies of the spring seat must be reinforced to precisely maintain the predetermined gap between the photosensitive drum 7 and the developing roller 9c. However, with the placement of the compression type coil spring 22a in the above described manner, it is unnecessary to reinforce the adjacencies of the spring seat, that is, the adjacencies of the base portion of the arm portion 19 in the case of this embodiment, because the base portion of the arm portion 19 is inherently greater in strength and rigidity. (Toner Chamber Frame) Referring to Figures 13, 15, 17, 19, 23 and 24, the toner chamber frame will be described in detail. Figure 23 is a perspective view of the toner chamber frame as seen before a toner seal is welded on, and Figure 24 is a perspective view of the toner chamber frame after toner is fitted in. Referring to Figure 13, the toner chamber frame 11 is constituted of two portions: the top and bottom portions 11a and 11b. Referring to Figure 11, the top portion 11a bulges upward, occupying the space on the left-hand side of the optical system 1 in the image forming apparatus main assembly 14, so that the toner capacity of the process cartridge B can be increased without increasing the size of the image forming apparatus A. Referring to Figures 13, 14 and 17, the top portion 11a of the toner chamber frame 11 has a recessed portion 17, which is located at the lengthwise center portion of the top portion 11a, and serves as a handhold. An operator of the image forming apparatus can handle the process cartridge B by grasping it by the recessed portion 17 of the top portion 11a and the downward facing side of the bottom portion 11b. The ribs 11c extending on the downward facing surface of the bottom portion 11b in the lengthwise direction of the bottom portion 11b serve to prevent the process cartridge B from slipping out of the operator's hand. Referring again to Figure 13, the flange 11a1 of the top portion 11a is aligned with the raised-edge flange 11b1 of the bottom portion 11b, the flange 11a1 being fitted within the raised edge of the flange 11b1 of the bottom portion 11b1, so that the walls of the top and bottom portions of the toner chamber frame 11 perfectly meet at the welding surface U, and then, the top and bottom portions 11a and 11b of the toner chamber frame 11 are welded together by melting the welding ribs with the application of ultrasonic waves. The method for uniting the top and bottom portions 11a and 11b of the toner chamber frame 11 does not need to be limited to ultrasonic welding. They may be welded by heat or forced vibration, or may be glued together. Further, the bottom portion 11b of the toner chamber frame 11 is provided with a stepped portion 11m, in addition to the flange 11b1 which keeps the top and bottom portions 11a and 11b aligned when they are welded together by ultrasonic welding. The stepped portion 11m is located above an opening 11i and is substantially in the same plane as the flange llbl. The structures of stepped portion 11m and its adjacencies will be described later. Before the top and bottom portions 11a and lib of the toner chamber frame 11 are united, a toner feeding member 9b is assembled into the bottom portion 11, and a coupling member lie is attached to the end of the toner feeding member 9b through the hole llel of the side wall of the toner chamber frame 11 as shown in Figure 19. The hole llel is located one of the lengthwise ends of the bottom portion 11b, and the side plate which has the hole llel is also provided with a toner filling opening lid substantially shaped like a right triangle. The triangular rim of the toner filling opening 11d is constituted of a first edge which is one of two edges that are substantially perpendicular to each other, and extends along the joint between the top and bottom portion 11a and 11b of the toner chamber frame 11, a second edge which vertically extends in the direction substantially perpendicular to the first edge, and a third edge, that is, a diagonal edge, which extends along the slanted edge of the bottom portion 11b. In other words, the toner filling opening lid is rendered as large as possible, while being located next to the hole llel. Thus, the toner filling opening lid can be maximized, so that the time required to fill the toner can be minimized. Next, referring to Figure 19, the toner chamber frame 11 is provided with an opening 11i through which toner is fed from the toner chamber frame 11 into the image developing chamber frame 12, and a seal (which will be described later) is welded to seal this opening 11i. Thereafter, toner is filled into the toner chamber frame 11 through the toner filling opening lid, and then, the toner filling opening lid is sealed with a toner sealing cap 11f to finish a toner unit J. The toner sealing cap llf is formed of polyethylene, polypropylene, or the like, and is pressed into, or glued to, the toner filling opening 11d of the toner chamber frame 11 so that it does not come off. Next, the toner unit J is welded to the image developing chamber frame 12, which will be described later, by ultrasonic welding, to form the image developing unit D. The means for uniting the toner unit J and the image developing unit D is not limited to ultrasonic welding; it may be gluing or snap-fitting which utilizes the elasticity of the materials of the two units. Referring to Figure 13, the slanted surface K of the bottom portion 11b of the toner chamber frame 11 is given an angle of  so that the toner in the top portion of the toner chamber frame 11 naturally slides down as the toner at the bottom is consumed. More specifically, it is desirable that the angle  formed between the slanted surface K of the process cartridge B in the apparatus main assembly 14 and the horizontal line Z is approximately 65 deg. when the apparatus main assembly 14 is horizontally placed. The bottom portion 11b is given an outwardly bulging portion 11g so that it does not interfere with the rotation of the toner feeding member 9b. The diameter of the sweeping range of the toner feeding member 9b is approximately 37 mm. The height of the bulging portion 11g has only to be approximately 0 - 10 mm from the imaginary extension of the slanted surface K. This is due to the following reason; if the bottom surface of the bulging portion 11g is above the imaginary extension of the slanted surface K, the toner which, otherwise, naturally slides down from the top portion of the slanted surface K and is fed into the image developing chamber frame 12, partially fails to be fed into the image developing chamber frame 12, collecting in the area where the slanted surface K and the outwardly bulging portion 11g meet. Contrarily, in the case of the toner chamber frame 11 in this embodiment, the toner is reliably fed into the image developing chamber frame 12 from the toner chamber frame 11. The toner feeding member 9b is formed of a steel rod having a diameter of approximately 2 mm, and is in the form of a crank shaft. Referring to Figure 19 which illustrates one end of the toner feeding member 9b, one 9b1 of the journals of the toner feeding member 9b is fitted in a hole 11r which is located in the toner chamber frame 11, adjacent to the opening 11i of the toner chamber frame 11. The other of the journals is fixed to the coupling member 11e (where the journal is fixed to the coupling member lie is not visible in Figure 19). As described above, providing the bottom wall of the toner chamber frame section 11 with the outwardly bulging portion 11g as the sweeping space for the toner feeding member 9b makes it possible to provide the process cartridge B with stable toner feeding performance without cost increase. Referring to Figures 13, 19 and 25, the opening 11i through which toner is fed from the toner chamber frame section 11 into the development chamber frame section is located at the joint between the toner chamber frame section 11 and the development chamber frame section 12. The opening 11i is surrounded by an recessed surface 11k which in turn is surrounded by the top and bottom portions 11j and 11j1 of the flange of the toner chamber frame 11. The lengthwise outer (top) edge of the top portion 11j and the lengthwise outer (bottom) edge of the bottom portion 11j1 are provided with grooves 11n, respectively, which are parallel to each other. The top portion 11j of the flange above the recessed surface 11k is in the form of a gate, and the surface of the bottom portion 11j1 of the flange is perpendicular to the surface of the recessed surface 11k. Referring to Figure 25, the plane of the bottom surface lln2 of the groove lln is on the outward side (toward the image developing chamber frame 12) of the surface of the recessed surface 11k. However, the flange of the toner chamber frame 11 may be structured like the flange illustrated in which the top and bottom portion 11j of the flanges are in the same plane and surround the opening 11i like the top and bottom pieces of a picture frame. Referring to Figure 20, an alphanumeric reference 12u designates one of the flat surfaces of the image developing chamber frame 12, which faces the toner chamber frame 11. The flange 12e which is parallel to the flat surface 12u and surrounds all four edges of this flat surface 12u like a picture frame is provided at a level slightly recessed from the flat surface 12u. The lengthwise edges of the flange 12e are provided with a tongue 12v which fit into the groove lln of the toner chamber frame 11. The top surface of the tongue 12v is provided with an angular ridge 12v1 (Figure 25) for ultrasonic welding. After the various components are assembled into the toner chamber frame 11 and image developing chamber frame 12, the tongue of the image developing chamber frame 12 is fitted into the groove lln of the toner chamber frame 11, and the two frames 11 and 12 are welded together along the tongue 12v and groove 11n (detail will be given later). Referring to Figure 24, a cover film 51, which can be easily torn in the lengthwise direction of the process cartridge B, is pasted to the recessed surface 11k to seal the opening 11i of the toner chamber frame 11; it is pasted to the toner chamber frame 11, on the recessed surface 11k, alongside the four edges of the opening 11i. In order to unseal the opening 11i by tearing the cover film 51, the process cartridge B is provided with a tear tape 52, which is welded to the cover film 51. The cover tape 52 is doubled back from the lengthwise end 52b of the opening 11i, is put through between an elastic sealing member 54 such as a piece of felt (Figure 20) and the opposing surface of the toner chamber frame 11, at the end opposite to the end 52b, and is slightly extended from the process cartridge B. The end portion 52a of the slightly sticking out tear tape 52 is adhered to a pull-tab 11t which is to be grasped with hand (Figures 16, 19 and 24). The pull-tab 11t is integrally formed with the toner chamber frame 11, wherein the joint portion between the pull-tab lit and the toner chamber frame 11 is substantially thin so that the pull-tab 11t can be easily torn away from the toner chamber frame 11. The surface of the sealing member 54, except for the peripheral areas, is covered with a synthetic resin film tape 55 having a small friction coefficient. The tape 55 is pasted to the sealing member 54. Further, the flat surface 12e located at the other of the lengthwise end portions of the toner chamber frame 11, that is, the end portion opposite to the position where the elastic sealing member 54 is located, is covered with the elastic sealing member 56, which is pasted to the flat surface 12e (Figure 20). The elastic sealing members 54 and 56 are pasted on the flange 12e, at the corresponding lengthwise ends, across the entire width of the flange 12e. As the toner chamber frame 11 and the image developing chamber frame 12 are joined, the elastic sealing members 54 and 56 exactly cover the corresponding lengthwise end portions of the flange 11j surrounding the recessed surface 11k, across the entire width the flange 11j, overlapping with the tongue 12v. Further, in order to precisely position the toner chamber frame 11 and the image developing chamber frame 12 relative to each other when they are joined, the flange 11j of the toner chamber frame 11 is provided with a round hole 11r and a square hole 11q which engage with the cylindrical dowel 12w1 and square dowel 12w2, respectively, of the image developing chamber frame 12. The round hole 11r tightly fits with the dowel 12w1, whereas the square hole 11q loosely fits with the dowel 12w2 in terms of the lengthwise direction while tightly fitting therewith in terms of the lengthwise direction. The toner chamber frame 11 and the image ,developing chamber frame 12 are independently assembled as a compound component prior to a process in which they are united. Then, they are united in the following manner. First, the cylindrical positioning dowel 12w1 and square positioning dowel 12w2 of the image developing chamber frame 12 are fitted into the positioning round hole 11s and positioning square hole 11q of the toner chamber frame 11, and the tongue 12v of the image developing chamber frame 12 is placed in the groove lln of the toner chamber frame 11. Then, the toner chamber frame 11 and the image developing chamber frame 12 are pressed toward each other. As a result, the sealing members 54 and 56 come in contact with, being thereby compressed by, the corresponding lengthwise end portions of the flange 11j, and at the same time, a rib-like projections 12z, which are located, as a spacer, at each lengthwise end of the flat surface 12u of the image developing chamber frame 12, are positioned close to the flange 11j of the toner chamber frame 11. The rib-like projection 12z is integrally formed with the image developing chamber frame 12, and is located at both sides, relative to the lengthwise direction, of the tear tape 52, so that the tear tape can be passed between the opposing projections 12z. With the toner chamber frame 11 and the image developing chamber frame 12 being pressed toward each other as described above, ultrasonic vibration is applied between the tongue-like portion 12v and the groove 11n. As a result, the angular ridge 12v1 is melt by frictional heat and fuses with the bottom of the groove 11n. Consequently, the rim portion 11n1 of the groove lln of the toner chamber frame 11 and the rib-like projection 12z of the image developing chamber frame 12 remain airtightly in contact with each other, leaving a space between the recessed surface 11k of the toner chamber frame 11 and the flat surface 12u of the image developing chamber frame 12. The aforementioned cover film 51 and tear tape 52 fit in this space. In order to feed the toner stored in the toner chamber frame 11 into the image developing chamber frame 12, the opening 11i of the toner chamber frame 11 must be unsealed. This is accomplished in the following manner. First, the pull-tab 11t attached to the end portion 52a (Figure 16) of the tear tape 52 extending from the process cartridge B is cut loose, or torn loose, from the toner chamber frame 11, and then, is pulled by the hand of an operator. This will tear the cover film 51 to unseal the opening 11i, enabling the toner to be fed from the toner chamber frame 11 into the image developing chamber frame 12. After the cover film 51 is pulled out of the process cartridge B, the lengthwise ends of the cartridge B are kept sealed by the elastic seals 54 and 56 which are located at the corresponding lengthwise ends of the flange 11j of the toner chamber frame 11. Since the elastic sealing members 54 and 56 are deformed (compressed) only in the direction of their thickness while maintaining their hexahedral shapes, they can keep the process cartridge sealed very effectively. Since the side of the toner chamber frame 11, which face the image developing chamber frame 12, and the side of the image developing chamber frame 12, which faces the toner chamber frame 11, are structured as described above, the tear tape 52 can be smoothly pulled out from between the two frames 11 and 12 by simply applying to the tear tape 52 a force strong enough to tear the cover film 51. As described above, when the toner chamber frame 11 and the image developing chamber frame 12 are united, a welding method employing ultrasonic vibration is employed to generate frictional heat which melts the angular ridge 12v1. This frictional heat is liable to cause thermal stress in the toner chamber frame 11 and the image developing chamber frame 12, and these frames may become deformed due to the stress. However, according to this embodiment, the groove 11n of the toner chamber frame 11 and the tongue 12v of the image developing chamber frame 12 engage with each other across the almost entire length of theirs. In other words, as the two frames 11 and 12 are united, the welded portion and its adjacencies are reinforced, and therefore, the two frames are not likely to be deformed by the thermal stress. As for the material for the toner chamber frame 11 and the image developing chamber frame 12, plastic material is used; for example, polystyrene, ABS resin (acrylonitrile-butadiene-styrene), polycarbonate, polyethylene, polypropylene, and the like. Referring to Figure 13, this drawing is a substantially vertical cross-section of the toner chamber frame 11 of the process cartridge B in this embodiment, and illustrates the interface between the toner chamber frame 11 and the image developing chamber frame 12, and its adjacencies. At this time, the toner chamber frame 11 of the process cartridge B in this embodiment will be described in more detail with reference to Figure 13. The toner held in a toner container 11A is single component toner. In order to allow this toner to efficiently free fall toward the opening 11i, the toner chamber frame 11 is provided with slanted surfaces K and L, which extend across the entire length of the toner chamber frame 11. The slanted surface L is above the opening 11i, and the slanted surface K is in the rear of the toner chamber frame 11 as seen from the opening 11i (in the widthwise direction of the toner chamber frame 11). The slanted surfaces L and K are parts of the top and bottom pieces 11a and 11b, respectively, of the toner chamber frame 11. After the process cartridge B is installed in the apparatus main assembly 14, the slanted surface L faces diagonally downward, and the slanted surface K faces diagonally upward, an angle 3 between the slanted surface K and the line m perpendicular to the interface between the toner chamber frame 11 and the image developing chamber frame 12 being approximately 20 deg. - 40 deg. In other words, in this embodiment, the configuration of the top portion 11a of the toner chamber frame 11 is designed so that the slanted surfaces K and L hold the aforementioned angles, respectively, after the top and bottom portions 11a and 11b of the toner chamber frame 11 are united. This, according to this embodiment, the toner container 11A holding the toner is enabled to efficiently feed the toner toward the opening 11i. (Toner Container Cap) Next, a toner container cap llf will be described. Figures 26, 27 and 28 are perspective, sectional, and top views of the toner container cap 11 in accordance with the present invention. In this embodiment, the configuration of the toner container cap llf is substantially triangular. This toner container cap 11f has a groove portion A1 which is the sealing portion, a bulge A2, the slanted surface A3 of the bulge A2, a bottom wall A4, reinforcement ribs A5, a knob portion A6, a slanted surface A7, a brim portion A8, a slanted internal surface A9, and the like. The groove portion A1 comprises the side wall surface A1a on the top side of the drawing, the bottom surface A1b on the right-hand side of the drawing, and the side wall surface A1c on the bottom side of the drawing. As is evident from Figure 26, the configuration of the toner container cap llf is round at the apex portions A10. The knob portion A6 is where the suction of the suction cup of an assembly robot is applied to pick up the toner container cap 11f when the toner container cap llf is fitted to the toner filling opening lid of a toner container 11A. The width h1 of the bottom surface Alb of the groove portion A1 is rendered less than the thickness h3 of the brim portion B1 of the toner filling opening lid formed in one of the side walls of the main structure 11A1 of the toner container 11A illustrated in Figure 29, so that the toner container 11A is sealed by the toner container cap llf as the brim portion B1 of the toner filling opening lid is forced to wedge into the groove portion A1 of the toner container cap 11f when the toner container cap llf is fitted to the toner filling opening lid. The height d of the bulge A2 (Figure 27) is desired to be in a range of 0.4 mm to 1.0 mm, more desirably, in a range of 0.45 mm to 0.9 mm, because of the distance the brim portion of the toner filling opening 11d must be allowed to wedge into the groove portion A1. The most desirable range is from 0.5 mm to 0.8 mm. The actual height d in this embodiment is 0.7 mm. The slanted surface A3 of the bulge A2 is necessary to allow the toner container cap llf to be smoothly pressed into the toner filling opening 11d in order to cap the toner container 11A. The angle  of the slanted surface A3 is desired to be no less than 30 deg. and no more than 90 deg., more desirably, no less than 45 deg., and most desirably, in a range of no less than 60 deg. and no more than 80 deg. The actual angle of the slanted surface A3 in this embodiment is 70 deg. The thickness h2 of the bottom wall A4 of the toner container cap 11f is rendered less than the basic thickness of the wall of the toner container cap 11f. In this embodiment, the basic thickness of the wall of the toner container cap llf is 1.5 mm, and the thickness h2 of the bottom wall A4 is 1.0 mm. This arrangement is made to minimize the deformation of the toner container cap llf which occurs during the capping of the toner container 11A, so that the creeping the toner container wall, which is liable to occur on the back side of the groove portion A1, can be prevented. As for the reinforcement rib A5, two or more are provided per straight wall portion of the toner container cap llf to prevent the straight wall portions from being bent and declining in sealing ability after the toner container cap 11f is fitted in the toner filling opening 11d. In this embodiment, each straight wall portion is provided with three reinforcement ribs A5. The reinforcement rib 5A is arranged to extend toward the periphery of the toner container cap from the knob portion A6 provided at the center of the toner container cap 11f. The height h4 of the reinforcement rib A5 is desired to be no less than 1.0 mm and no more than 3.0 mm, more desirably, no less than 1.5 mm and no more than 2.5 mm, and most desirably, in a range of 1.8 mm to 2.2 mm. In this embodiment, it is 2.0 mm. The slanted surface A7 and the slanted interior surface A9 are provided to minimize the deformation of the toner container cap 11f which occurs during the capping of the toner container 11A, and also to prevent the creeping which is liable to occur to the back side of the groove portion A1. When a toner container is sealed by allowing the brim portion of the toner filling opening to wedge into the groove portion of the toner container cap 11f as it is in this embodiment, the following materials are desirable as the material for the toner container cap llf in consideration of stability in sealing ability and creep prevention after the capping. First, regarding the hardness of the material, it is desirable that the hardness of the toner container cap llf in Rockwell hardness scale (measured based on JIS-K7202) is less than that of the main structure 11A1 of the toner container 11A. More specifically, the hardness of the toner container cap llf is desired to be in a range of R30 - R80, more desirably, in a range of R40 - R50, and most desirably, R45. In this embodiment, it is R45. As for the hardness of the main structure 11A1 of the toner container 11A, a hardness range of R80 - R150 is desirable, more desirably, in a range of R100 - R140, and most desirably, R120. In this embodiment, it is R125. In terms of the modulus of elasticity relative to bending (measured according to JIS-K7203), it is desirable that the toner container cap llf is less than the main structure 11A1. More specifically, the modulus of elasticity, relative to bending, of the toner container cap llf is desired to be no less than 800 kg/cm 2 and no more than 10,000 kg/cm 2 , more desirably, no less than 1,300 kg/cm 2 and no more than 9,000 kg/cm 2 , and most desirably, 2,000 kg/cm 2 . In this embodiment, it is 1,700 kg/cm 2 . As for the modulus of elasticity, relative to bending, of the container main structure 11A1, it is desired to be no less than 20,000 kg/cm 2 and no more than 30,000 kg/cm 2 , more desirably, no less than 22,500 kg/cm 2 and no more than 28,000 kg/cm 2 , and more desirably, 25,000 kg/cm 2 . In this embodiment, it is 24,500 kg/cm 2 . In order to prevent the creeping after the capping, the yield point (measured according to JIS-K7113) of the material for the toner container cap llf in a tensile strength test is desired to be less than that of the material for the container main structure 11A1. More specifically, the yield point of the toner container cap 11f is desired to be no less than 80 kg/cm 2 and no more than 200 kg/cm 2 , more desirably, no less than 90 kg/cm 2 and no more than 190 kg/cm 2 , and most desirably, 150 kg/cm 2 . In this embodiment, it is 120 kg/cm 2 . As for the yield point for the container mains structure 11A1, it is desired to be no less than 250 kg/cm 2 and no more than 500 kg/cm 2 , more desirably, no less than 260 kg/cm 2 and no more than 400 kg/cm 2 , and most desirably, 270 kg/cm 2 and no more than 320 kg/cm 2 . In this embodiment, it is 270 kg/cm 2 . As for specific materials for the toner container cap 11f, low density polyethylene, for example, is used. As for the material for the container main structure 11A1, HIPS is employed in consideration of the impact to which a toner container is liable to be subjected during the transportation of the toner container. Both the toner container cap llf and the container main structure 11A1 are formed by injection molding. Referring to Figure 29, the toner filling opening 11d of the container main structure 11A1 is provided with a brim portion B1, and a cap guide B2 which serves as an insertion guide during the capping. These portions of the toner filling opening lid are integrally formed with the container main structure 11A1. The brim portion B1 comprises a chamfered top edge portion Bla and a rounded (no more than 0.3) bottom edge portion B1b. Further, referring to Figure 30, the side wall portion A1c of the groove portion A1, on the downward side, of the toner container cap 11f is provided with a straight slanted surface A1c, so that the sealability of the toner container 11A is greatly improved the bottom edge portion B1b of the brim portion B1 of the container main structure 11A1 firmly bite into this slanted surface A1c. In this embodiment, the rounding of bottom edge portion B1b is set at 0.3. Also referring to Figure 30, a referential figure K designates the distance (bite) the container cap llf is forced into the container main structure 11A1. This distance K is desired to be no less than 0.2 mm and no more than 1.0 mm, more desirably, no less than 0.3 mm and no more than 0.9 mm, and most desirably, 0.7 mm. In this embodiment, it is 0.7 mm. The sealed state of the toner container 11A is created by forcing the toner container cap 11f into the toner filling opening 11f of the container main structure 11A1, and in order to prevent the contact between the toner filling opening 11d and the unintended portion of the toner container cap 11f from reducing the airtightness of the capped toner container 11A, the groove portion A1 and the toner filling opening 11d are designed to leave a gap G between the brim portion A1b and the bottom wall A1b of the groove portion A1, as illustrated in Figure 30, after the capping. This gap G is desired to be no less than 0.1 mm and no more than 2.0 mm. In this embodiment, it is set at 0.2 mm. Further, referring to Figure 31, a gap S between the cap guide B2 and the toner container cap 11f is desired to be no less than 0.2 mm and no more than 2.0 mm. In this embodiment, it is 0.3 mm. The essential measurements of the toner container cap 11f and the toner filling opening 11d in this embodiment are given below (Figures 27, 28 and 29). First side wall length of container cap (11) 39.14 (mm) Second side wall length of container cap (12) 49.56 (mm) Third side wall length of container cap (13) 50.41 (mm) Height of container cap (14) 4.50 (mm) Width of container cap brim portion (15) 2.60 (mm) Height of container cap guide (16) 2.80 (mm) The container main structures 11A1 which were formed according to the above specifications were subjected to capping tests, in which they were tested for creeping, and the time it took to fit a toner container cap. They are also subjected to transportation tests, in which they are tested for being leakproof, and tests, in which the amount of stress it took to dislodge the toner container cap 11f from the toner filling opening 11d was determined. The conditions under which the tests were conducted are as follows. (1) Capping test: The pressing time (time it takes to completely insert the toner container cap llf into the toner filling opening 11d) was measured while applying a pressure of 160 kgf to seal the toner container with the toner container cap 11f. Further, the toner container cap 11f, and the toner filling opening 11d of the container main structure 11A1, were checked for the presence of creep. A pressing time of no more than 2.5 seconds is deemed satisfactory for an automatic toner filling apparatus. (2) Transportation test: Toner containers 11A were filled with 460 g of magnetic single component toner having an average particle diameter of 8 µm, and were allowed to free fall from a height of 100 cm, causing them to land on each of six surfaces and four corners. (3) Dislodgment stress test: A stress measuring head was pushed toward the toner filling opening from inside the container main structure 11A1 at a rate of 100 mm/min., and the maximum stress was measured the moment the toner container cap llf became dislodged from the toner filling opening lid. Further, a total of 13 container main structures were produced, which were different in the distance the toner container cap was pressed into the toner filling opening, the bulge angle, the bulge height, the Rockwell hardness, and the like. For performance comparison, a circular toner container cap 11f' illustrated in Figure 32, was produced using low density polyethylene by injection molding. In the case of this comparative toner container cap 11f', the effective area of the toner filling opening 11d' was the same as the toner filling opening 11d described in the preceding embodiments of the present invention; the modulus of elasticity, relative to bending, was 2000 kg/cm 2 ; the height of the rib C1 was 1.75 mm; and the latching portion C2 on one side was 0.15 mm. The results of comparison are given in the following Table 2. According to this table, those in accordance with the preceding embodiments of the present invention have no problem at all in sealing performance. But, among those comparative toner container caps 11f' used in combination with the container main structure 11A1, none was satisfactory across the entire battery of tests. However, even the structures described in the comparative embodiments can be used as satisfactory structures for the toner container cap and the toner container depending on the type of usage. For example, even those which suffer from creeping, that is, those which are inferior in durability, are usable as long as the amount of toner to be contained is small. In other words, the caps and container main structures described in the embodiments of the present invention can afford more latitude in their usage, and are better in toner filling efficiency, than those described in the comparative embodiments. CAP & CONTAINER REMARKS CAP CREEP PRESS FITTING TIMES (sec) TRANS. TEST DISLODGE TEST DIFFERENT FROM EMB. EMB.1 NO 1.2 G 38 2 NO 1 G 30 BT = 0.2 mm 3 NO 1.7 G 52 BT = 0.9 mm 4 NO 1.5 G 46 NA = 30 deg. 5 NO 0.8 G 36 NA = 85 deg. 6 NO 1.1 G 33 NP = 0.4 mm 7 NO 1.9 G 55 NP = 1.0 mm 8 NO 1.1 G 35 RH: CAP = R32 CON = R148 9 NO 1.3 G 41 RH: CAP = R75 CON = R83 10 NO 1.1 G 36 BE: CAP = 840 kg/cm 2 CON = 28990 kg/cm 2 11 NO 1.4 G 40 BE: CAP = 9980 kg/cm 2 CON = 20050 kg/cm 2 12 NO 1.1 G 37 YP: CAP = 80 kg/cm 2 CON = 490 kg/cm 2 13 NO 1.4 G 36 YP: CAP = 190 kg/cm 2 CON = 250 kg/cm 2 COMP. EMB.1 NO 0.6 NG 15 2 NO 0.8 NG 24 BT = 0.15 mm 3 YES(CAP) 2.5NG G 55 BT = 1.2 mm 4 YES(CAP) 2.8NG G 42 NA = 25 deg. 5 NO 0.9 NG 27 NP = 0.35 mm 6 YES(CAP) 3.0NG G 58 NP = 1.05 mm 7 YES(CON) 1.1 G 25 RH: CAP = R85 CON = R75 8 NO 3.0NG G 26 RH: CAP = R85 CON = R155 9 NO 1 NG 24 RH: CAP = R25 CON = R155 10 YES(CON) 1.1 G 26 BE: CAP = 10200 kg/cm 2 CON = 18480 kg/cm 2 11 NO 2.9NG G 27 BE: CAP = 10200 kg/cm 2 CON = 30080 kg/cm 2 12 NO 1 NG 24 BE: CAP = 780 kg/cm 2 CON = 30080 kg/cm 2 13 YES(CON) 1.1 G 25 YP: CAP = 210 kg/cm 2 CON = 240 kg/cm 2 G: GOOD NG: NO GOOD BT: BITE OF CAP NA: NOTCH ANGLE NP: NOTCH PROJECTION RH: ROCKWELL HARDNESS CON: CONTAINER BE: BENDING ELASTICITY YP: YIELD POINT As described above, in terms of pressing time, the toner container 11A described in the embodiments of the present invention were not greatly different from the conventional toner container described in the comparative embodiments, but in terms of being leakproof during the transportation, the former were better than the latter. Further, in terms of the cap dislodgment resistance, the former were twice as good as the latter. Further, the toner container 11A was assembled into a process cartridge, and then, was subjected to the transportation test. The results of the test confirmed that the toner container cap 11f had no problem in sealing effectiveness. In the preceding embodiments of the present invention, the projected shapes of the toner container caps 11f were substantially triangular, but the configuration of the toner container cap 11f may also be circular as illustrated in Figure 33, substantially square as previously described and illustrated in Figure 24, or in the other polygonal or noncircular shape; there is no restriction. Further, the material for the toner container caps 11f was low density polyethylene, and the material for the container main structures 11A1 was impact resistant polystyrene, but there is no specific restriction regarding the material choice as long as the material for the toner container cap 11f is less in terms of Rockwell hardness, modulus of elasticity in bending, yield point, and the like, than the material for the container main structure. For example, a toner container comprising a toner container cap 11f formed of polypropylene, and an container main structure 11A1 formed of the other HIPS, for example, ABS, PPE, or PPO, is also satisfactorily usable. Further, as for the configuration of the reinforcement rib, its lengthwise vertical section may be in a semicircular form which bows downward, as long as its can provide effective reinforcement. These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.

Claims: A toner accommodation chamber comprising: an elongate toner container portion having a pair of end walls, and sidewalls extending longitudinally of the toner container; a sealable supply opening (11i) for supplying toner to a developing device, the supply opening being provided in a sidewall of the container portion; and a filling opening (11d, 112, 122, 132) provided in one of the end walls, wherein said one end wall has a substantially polygonal shape, and said filling opening has a shape substantially corresponding to the shape of said one end wall. A toner accommodation chamber according to claim 1, wherein said one end wall has a substantially triangular shape, and said filling opening (112, 122, 132) has a substantially triangular shape. A toner accommodation chamber according to claim 1 or claim 2, further comprising a plug (113, 123, 133, 143) for plugging said filling opening (112, 122, 132), said plug comprising a polygonal central portion corresponding to the shape of the filling opening, and a rib (144) extending perpendicularly to one side of the polygonal central portion and adjacent said one side. A toner accommodation chamber (111, 121, 131) according to any preceding claim, wherein said filling opening (112, 122, 132) has at least two edges substantially parallel to edges of said one end wall. A toner accommodation chamber (111, 121, 131) according to any of claims 1 to 4, wherein said sidewalls comprise a flat surface extending between said end walls, and wherein said filling opening (112, 122, 132), has at least one straight edge extending parallel to the plane of said flat surface. A toner accommodation chamber (111, 121, 131) according to claim 5, wherein said supply opening (11i) for the egress of toner is formed in said flat surface of the sidewalls. A toner accommodation chamber (111, 121, 131) according to any of claims 4 to 7, wherein at least one of the edges of said filling opening (112, 122, 132) is close to the corresponding edge of the said one end wall. A process cartridge detachably mountable to a main assembly (A) of an electrophotographic image forming apparatus, comprising a toner accommodation chamber according to any preceding claim, and a developing device (12) for developing a latent image on a photosensitive member, wherein the supply opening (11i) of the toner accommodation chamber is arranged so that toner may pass from the toner accommodation chamber to the developing device through the supply opening when the supply opening is unsealed.

Inventors: FUJIWARA YASUO, MORINAGA HIROUMI, NUMAGAMI ATSUSHI, FUJIWARA, YASUO, MORINAGA, HIROUMI, NUMAGAMI, ATSUSHI
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1997
Main classification: G03G15
IPC codes: G03G15