JP2008209593A - Method for ultrasonically welding developing cartridge case - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for ultrasonically welding a developing cartridge case with high welding strength, and with less dimensional variation, even in the case of welding a large-sized developing cartridge case. <P>SOLUTION: The ultrasonic welding method of the developing cartridge case is to ultrasonically weld the developing cartridge case used for an electrophotographic image forming apparatus. When the developing cartridge case is ultrasonically welded, the pressure of a horn pressed against the developing cartridge case is 200 to 700 kPa, and also, the amplitude of the leading end of the horn is 40 to 80 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic welding method for a developing cartridge housing used in an electrophotographic image forming apparatus.

  In an image forming apparatus using an electrophotographic method such as a copying machine or a laser beam printer, a plurality of process means such as an image carrier and a developing device, or a charging device, a cleaning device, etc. are integrated into a unit. Some have a process cartridge. The process cartridge has a structure in which a plurality of process means such as a photosensitive drum and a developing device can be integrally attached to and detached from the image forming apparatus main body, and this structure facilitates maintenance of the image forming apparatus. Have

  In general, a developing device (hereinafter, also referred to as a developing cartridge) included in a process cartridge has a developing cartridge housing as a housing that stores a developer and supplies the developer to a developing roller.

  Other image forming apparatuses do not take the form of a process cartridge, but have a configuration in which a single developing cartridge provided with a developing cartridge housing is detachable from the image forming apparatus.

  These developing cartridge casings are usually formed by bonding a plurality of molded products made of resin or the like, and are configured as sealed casings so that the developer does not scatter to the surrounding process means.

  In the welding of a developing cartridge housing used in an image forming apparatus for forming an image on a normal size paper up to A4 size, there are many that employ an ultrasonic welding method. However, in an image forming apparatus that forms an image on a large size sheet such as A3 size, the size of the developing cartridge becomes large, and therefore, it becomes a problem whether or not the bonding portion of the developing cartridge housing can have sufficient welding strength. .

  The vibration welding method is often used for welding large parts that require sufficient welding strength. However, in the welding by the vibration welding method, there is a problem that the pressure at the time of welding is strong, and thus there is a problem that the joining portion is easily displaced, and there is a problem that the production efficiency is poor because the welding machine is large and inline processing is difficult.

  The ultrasonic welding method has characteristics that damage to parts is less than that of the vibration welding method, and the apparatus is small, so that it is suitable for welding small parts and easy in-line processing.

  The points to be noted when performing ultrasonic welding are dimensional variation due to deformation of parts during welding and insufficient welding strength. In particular, in the welding of a developing cartridge housing used in an image forming apparatus capable of forming an image on a large size paper such as A3 size, there is a problem that a variation in dimensions at the time of molding becomes large. There is a problem that a member to be moved easily shifts. The displacement of the members to be welded leads to dimensional variation and insufficient welding strength, and the insufficient welding strength causes problems such as peeling of the joint and toner leakage.

  As a countermeasure against these problems, a technique has been disclosed in which protrusions and grooves are provided on two members to be welded in order to suppress dimensional variations during welding and improve the welding strength (see, for example, Patent Document 1).

  In the technology of Patent Document 1, in the developing cartridge housing of the process cartridge, a protrusion is provided on one member to be welded, a groove is provided on the other member, and the protrusion and the groove are fitted at the time of welding. It is intended to improve the strength by suppressing dimensional variation during welding.

  However, due to the recent demand for miniaturization of image forming apparatuses, miniaturization of individual members is also strictly required, and it may be difficult to design projections and grooves on the welding surface of the developing cartridge housing. is there. In addition, in order to fit the protrusion and the groove, it is necessary to strictly manage the variation in member dimensions, which leads to an increase in manufacturing cost.

  Furthermore, since the size of the welded portion is strictly limited due to the miniaturization of the individual members, it is difficult to increase the size of the welded portion of the developing cartridge housing used for forming a large size image such as A3 size. For this reason, if the pressing force of the horn is increased for the purpose of giving a sufficient welding strength to the welded portion, there is a risk of causing a shift and conversely causing a phenomenon that the welding strength is insufficient.

  On the other hand, for the purpose of downsizing the roll film cartridge member to be welded, the shape of the welding horn and the welding conditions (horn pressure: 5-35 kg · f, amplitude: 10-45 μm) without providing a rib for joining the member A technique of performing welding by combining with (see, for example, Patent Document 2) is disclosed.

However, the welding member described in Patent Document 2 is an invention for a small member having a length of 40 mm or less and a diameter of 23 mm or less. For a member having a width exceeding 300 mm, such as the developing cartridge housing of the present invention, this welding member is used. Under certain conditions, it is difficult to ensure dimensional accuracy and strength.
JP-A-9-101734 Japanese Patent Laid-Open No. 7-244359

  The present invention provides an ultrasonic welding method of a developing cartridge housing that solves the above-described problems and has a small welding size and high welding strength even for a large developing cartridge housing. Objective.

  The object of the present invention can be achieved by the following constitution.

1. In the ultrasonic welding method of the developing cartridge housing for welding the developing cartridge housing used in the electrophotographic image forming apparatus using ultrasonic waves,
When welding using the ultrasonic wave, the pressure of the horn pressed against the developing cartridge housing is 200 kPa or more and 700 kPa or less, and the amplitude of the tip of the horn is 40 μm or more and 80 μm or less. An ultrasonic welding method for the developing cartridge housing.

  2. 2. The developing cartridge housing ultrasonic welding method according to 1, wherein the developing cartridge housing is a developing cartridge housing used in an image forming apparatus capable of forming an image on A3 size paper.

  According to the present invention, by performing welding without applying a large pressing pressure to the horn at the time of welding, it is possible to perform appropriate welding with less deviation of the welding portion even for a large size developing cartridge housing. As a result, a developing cartridge housing having a high welding strength with little variation in dimensions during welding can be manufactured in-line.

  Although the present invention will be described based on the illustrated embodiment, the present invention is not limited to the embodiment.

  First, an image forming apparatus according to the present invention will be described.

  FIG. 1 is a schematic diagram showing an overall configuration of a full-color image forming apparatus which is one embodiment of an image forming apparatus according to the present invention.

  In the full-color image forming apparatus shown in FIG. 1, a charging brush 111 that uniformly charges the surface of the photosensitive drum 10 to a predetermined potential around the photosensitive drum 10 that is rotationally driven, and the photosensitive drum 10 A cleaner 112 for scraping off the remaining toner is provided.

  Further, a laser scanning optical system 20 for scanning and exposing the photosensitive drum 10 charged by the charging brush 111 with a laser beam is provided. The laser scanning optical system 20 includes a laser diode, a polygon mirror, and an fθ optical element. It is well known. Print data for each of yellow, magenta, cyan, and black is transferred from the host computer to the control unit of the full-color image forming apparatus. The laser scanning optical system 20 sequentially outputs the laser beam as a laser beam based on the print data for each color, scans and exposes the photosensitive drum 10, and thereby the static image for each color is formed on the photosensitive drum 10. Electro latent images are sequentially formed.

  A full-color developing device 30 that supplies toner of each color to the photosensitive drum 10 on which the electrostatic latent image is formed to perform full-color development includes four color-development developing cartridges 13Y, 13M, 13C, 13Bk. Four developing cartridges 13Y, 13M, 13C, and 13Bk containing non-magnetic one-component toners of four colors of yellow, magenta, cyan, and black rotate around the support shaft 33, and each developing cartridge 13Y, 13M, 13C and 13Bk are guided to positions facing the photosensitive drum 10. Hereinafter, the four developing cartridges 13Y, 13M, 13C, and 13Bk are collectively referred to as the developing cartridge 13.

  Further, in each of the developing cartridges 13Y, 13M, 13C, and 13Bk in the full-color developing device 30, a toner regulating member (not shown) is pressed against the outer peripheral surface of a developer carrier (developing roller) 131 that rotates and conveys toner. Yes. The toner regulating member regulates the amount of toner conveyed by the developing roller 131 and charges the conveyed toner. In the full color developing device 30, two toner regulating members may be provided in order to appropriately regulate and charge the toner conveyed by the developing roller.

  Then, whenever the electrostatic latent image of each color is formed on the photosensitive drum 10 by the laser scanning optical system 20 as described above, the full-color developing device 30 is rotated around the support shaft 33 as described above. Let The developing cartridges 13Y, 13M, 13C, and 13Bk containing the corresponding color toners are sequentially guided to positions facing the photosensitive drum 10 by the rotation of the full-color developing device 30. Each developing roller 131 in the guided developing cartridges 13Y, 13M, 13C, and 13Bk is brought into contact with the photosensitive drum 10 to be charged on the photosensitive drum 10 on which electrostatic latent images of each color are sequentially formed. Each color toner is supplied one after another for development.

  Further, an endless intermediate transfer belt 40 that is rotationally driven is provided as an intermediate transfer body 40 at a position downstream of the full-color developing device 30 in the rotation direction of the photosensitive drum 10. The intermediate transfer belt 40 is driven to rotate in synchronization with the photosensitive drum 10. The intermediate transfer belt 40 is pressed by a rotatable primary transfer roller 41 and comes into contact with the photosensitive drum 10. A secondary transfer roller 43 is rotatably provided at a portion of the support roller 42 that supports the intermediate transfer belt 40, and the recording material S such as recording paper is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43. It has come to be.

  Further, a cleaner 50 that scrapes off the toner remaining on the intermediate transfer belt 40 is provided in a space between the full-color developing device 30 and the intermediate transfer belt 40 so as to be able to contact with and separate from the intermediate transfer belt 40. ing.

  The paper feeding means 60 that guides the recording material S such as plain paper to the intermediate transfer belt 40 includes a paper feeding tray 61, a paper feeding roller 62, and a timing roller 63. The sheet feeding tray 61 accommodates the recording material S, the sheet feeding roller 62 feeds the recording material S accommodated in the sheet feeding tray 61 one by one, and the timing roller 63 is an image formed on the intermediate transfer belt 40. The recording material S is fed in between the intermediate transfer belt 40 and the secondary transfer roller 43 in synchronization with the above.

  Thus, the recording material S sent between the intermediate transfer belt 40 and the secondary transfer roller 43 is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43, and the toner image is pressed and transferred from the intermediate transfer belt 40. Is done.

  On the other hand, the recording material S on which the toner image has been pressed and transferred as described above is guided to the fixing device 70 by the conveying means 66 constituted by an air suction belt or the like. The toner image transferred by the fixing device 70 is fixed on the recording material S, and then the recording material S is discharged onto the upper surface of the apparatus main body 100 through the vertical conveyance path 80.

  Next, the operation of forming a full color image using this full color image forming apparatus will be specifically described.

  First, the photosensitive drum 10 and the intermediate transfer belt 40 are rotationally driven in the respective directions at the same peripheral speed, and the photosensitive drum 10 is charged to a predetermined potential by the charging brush 11.

  The photosensitive drum 10 thus charged is exposed to a yellow image by the laser scanning optical system 20 to form an electrostatic latent image of the yellow image on the photosensitive drum 10. Thereafter, the yellow toner charged by the toner regulating member as described above is supplied from the developing cartridge 13Y containing the yellow toner in the photosensitive drum 10 to develop the yellow image. The intermediate transfer belt 40 is pressed by the primary transfer roller 41 against the photosensitive drum 10 on which the yellow toner image is formed, and the yellow toner image formed on the photosensitive drum 10 is primarily transferred to the intermediate transfer belt 40. Let

  After the yellow toner image is transferred to the intermediate transfer belt 40, the full-color developing device 30 is rotated about the support shaft 33 as described above, and the developing cartridge 13M containing magenta toner is moved to the photosensitive drum 10. Lead to the opposite position. As in the case of a yellow image, the laser scanning optical system 20 exposes a magenta image to the charged photosensitive drum 10 to form an electrostatic latent image, and this electrostatic latent image is accommodated with magenta toner. Development is performed by the developing cartridge 13M. The developed magenta toner image is primarily transferred from the photosensitive drum 10 to the intermediate transfer belt 40, and in the same manner, exposure, development, and primary transfer of a cyan image and a black image are sequentially performed. In this way, a yellow, magenta, cyan, and black toner image is sequentially superimposed on the intermediate transfer belt 40 to form a full-color toner image.

  When the final black toner image is primarily transferred onto the intermediate transfer belt 40, the recording material S is sent between the secondary transfer roller 43 and the intermediate transfer belt 40 by the timing roller 63. The recording material S is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43, and the full color toner image formed on the intermediate transfer belt 40 is secondarily transferred.

  Then, a full color toner image is secondarily transferred onto the recording material S, the recording material S is guided to the fixing device 70 by the conveying means 66, and the transferred full color toner image is fixed by the fixing device 70. . Thereafter, the recording material S is discharged to the upper surface of the apparatus main body 100 through the vertical conveyance path 80.

  Next, the developer cartridge 13 uses, for example, a two-component developer composed of toner and carrier or a one-component developer composed only of toner as the developer, and supplies the toner to the surface of the photosensitive drum 10. Then, development is performed.

  FIG. 2 is a view for explaining the configuration of the embodiment of the developing cartridge according to the present invention. The developing cartridge of this embodiment is an example using a one-component developer. FIG. 2A is a perspective view illustrating an example of a developing cartridge, and FIG. 2B is a cross-sectional view illustrating an example of a developing cartridge. The developing cartridge 13 in this embodiment has a configuration used for an image forming apparatus capable of forming an image on A3 size paper.

  The developing cartridge 13 has a configuration in which a predetermined amount of toner is accommodated in a part where components such as a developing roller are arranged. The developing cartridge 13 supplied in the form of a cartridge is loaded at a predetermined position in the image forming apparatus, and then the developer stored therein is supplied to the photosensitive drum for development. When a predetermined number of images are formed and the developer runs out, it is removed from the apparatus and a new developing cartridge 13 is loaded.

  2B, the developing cartridge 13 has a buffer chamber 132 adjacent to the developing roller 131 described above, a developing cartridge housing 133 adjacent to the buffer chamber 132, and the like. The developing cartridge housing 133 includes a housing lower portion 133a and a housing upper portion 133b, and is ultrasonically welded.

  The developing roller 131 has a conductive cylindrical base and an elastic layer formed using a substance such as silicone rubber on the outer periphery of the base.

  In the drawing, a toner state detection unit 241 corresponding to detection means for detecting information related to toner is disposed immediately above the developing roller 131. The toner state detection unit 241 uses, for example, an optical sensor, a CCD, or the like, detects toner constituting the toner layer formed on the developing roller 131, and transmits a detection signal to a control device (not shown) of the image forming apparatus. To do.

  In the buffer chamber 132, a blade 134 as a toner regulating member is disposed in pressure contact with the developing roller 131. The blade 134 regulates the charge amount and adhesion amount of the toner on the developing roller 131. Further, it is possible to further provide an auxiliary blade 135 for assisting the regulation of the toner charge amount and adhesion amount on the developing roller 131 on the downstream side of the blade 131 with respect to the rotation direction of the developing roller 131.

  A supply roller 136 is pressed against the developing roller 131. The supply roller 136 is rotationally driven in the same direction as the developing roller 131 (counterclockwise direction in the figure) by a motor (not shown). The supply roller 136 has a conductive cylindrical base and a foam layer formed of urethane foam or the like on the outer periphery of the base.

  The developing cartridge housing 133 contains toner T that is a one-component developer. The developing cartridge housing 133 is provided with a rotating body 137 for stirring the toner. A film-like conveying blade is attached to the rotator 137, and the toner is conveyed by the rotation of the rotator 137 in the direction of the arrow. The toner conveyed by the conveying blades is supplied to the buffer chamber 132 via a passage 138 provided in a partition wall that separates the developing cartridge housing 133 and the buffer chamber 132. The shape of the conveying blade is bent while the toner is conveyed in front of the rotating direction of the blade as the rotating body 137 rotates, and returns to a straight state when the left end of the passage 138 is reached. Thus, the toner is supplied to the passage 138 by returning the shape of the blade straightly through the curved state.

  The passage 138 is provided with a valve 321 for closing the passage 138. This valve is a film-like member, one end of which is fixed to the upper right side of the passage 32 of the partition wall, and when toner is supplied from the developing cartridge housing 133 to the passage 138, the valve is pushed rightward by the pressing force from the toner. 138 can be opened. As a result, toner is supplied into the buffer chamber 132.

  Further, a regulating member 322 is attached to the other end of the valve 321. The regulating member 322 and the supply roller 136 are arranged so as to form a slight gap even when the valve 321 closes the passage 138. The regulating member 322 adjusts the amount of toner accumulated at the bottom of the buffer chamber 132 so as not to be excessive, so that a large amount of toner collected from the developing roller 131 to the supply roller 136 does not fall on the bottom of the buffer chamber 132. Adjusted.

  In the developing cartridge 13, the developing roller 131 is rotationally driven in the arrow direction during image formation, and the toner in the buffer chamber 132 is supplied onto the developing roller 131 by the rotation of the supply roller 136. The toner supplied onto the developing roller 131 is charged and thinned by a blade 134 and an auxiliary blade 135 and then conveyed to a region facing the image carrier to develop an electrostatic latent image on the image carrier. Provided. The toner that has not been used for development returns to the buffer chamber 132 as the developing roller 131 rotates, and is scraped and collected from the developing roller 131 by the supply roller 136.

  The developing cartridge housing 133 according to the embodiment of the present invention is a member constituting the developing cartridge 13 included in the process cartridge. The process cartridge has a configuration in which an electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member) and a developing cartridge or at least one of a charger or a cleaning device is added thereto.

  The length of the developing cartridge housing 133 in the direction of the rotation axis of the developing roller 131 is formed to be substantially the same as the length of the developing roller 131 in order to uniformly supply toner onto the developing roller 131. The length of the developing roller 131 in the present embodiment is at least 300 mm so that an image can be formed on A3 size paper, and the length of the developing cartridge housing 133 is also substantially the same. Is formed.

  The process cartridge is detachably attached to the main body of the image forming apparatus, and the driving force is transmitted by the combination of the main body side driving force transmitting means and the process cartridge side driving force transmitting means provided in the image forming apparatus main body.

  FIG. 3 is a cross-sectional view for explaining a welding method by an ultrasonic welding method of the developing cartridge housing 133 according to the present invention. FIG. 3A is a diagram showing the housing lower portion 133a and the housing upper portion 133b before welding, and FIG. 3B is a diagram showing a state of the developing cartridge housing 133 during welding processing.

  In FIG. 3A, the developing cartridge housing 133 is a sealed housing by bonding a housing lower portion 133a constituting the lower portion and a housing lower portion 133b constituting the lower portion. Adhesion is performed by ultrasonic welding, and the welded portions Ya1 and Ya2 of the housing lower portion 133a and the welded portions Yb1 and Yb2 of the housing upper portion 133b are welded.

  The casing lower portion 133a and the casing upper portion 133b are molded using an amorphous resin or a crystalline resin. As an amorphous resin, acrylonitrile / butadiene / styrene resin (ABS resin), polycarbonate, polymethyl methacrylate, XT polymer, modified PPE resin, polyamideimide, polyarylate, polyetherimide, polyethersulfone, general-purpose polystyrene, Polysulfone, polyvinyl chloride, styrene / acrylonitrile resin and the like are used. Examples of the crystalline resin include polyoxymethylene, cellulose, fluorine polymer, ionomer, liquid crystal polymer, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyethylene, TPX polymer, polyphenylene sulfide, and polypropylene.

  In FIG.3 (b), Ha and Hb are the horns of a welding machine, Ua and Ub are the stand of the jig | tool holding the housing | casing lower part 133a.

  The welding procedure is as follows. First, the housing lower part 133a is installed on the jig cradle Ua, Ub. The housing upper part 133b is placed on the housing lower part 133a so as to match. Finally, the horns Ha and Hb of the welding machine are pressed from the back surface of the welding parts Yb1 and Yb2 of the upper part 133b of the casing to weld them.

  The welding condition of the developing cartridge housing 133 according to the present invention is such that the pressure for pressing the horn of the welding machine is smaller and the amplitude of the horn tip is larger than the welding condition of the roll film cartridge member in the above-mentioned Patent Document 2. ing. According to this welding condition, it is possible to perform welding having a high welding strength with little variation in dimensions at the time of welding even for a large developing cartridge casing 133 having a length exceeding 300 mm.

1. Members to be welded: upper housing part 133b and lower housing part 133a (see FIG. 3 for the cross-sectional shape, and the length (rotating shaft direction of developing roller 131) is 430 mm)
2. Material of the material to be welded: ABS (acrylonitrile butadiene styrene) resin (with 20% glass fiber)
3. Welding machine: Ultrasonic welding machine 2000d (manufactured by Branson)
4). Welding conditions: Weld time 0.25 to 0.3 s, hold time 0.3 s
About the pressure of a horn, and the amplitude of a horn tip, it describes in Examples 1-6 and Comparative Examples 1-4 (Example 1).
1. Horn pressure: 200kPa
2. Horn tip amplitude: 60 μm
(Example 2)
1. Horn pressure: 300kPa
2. Horn tip amplitude: 60 μm
(Example 3)
1. Horn pressure: 500kPa
2. Horn tip amplitude: 60 μm
Example 4
1. Horn pressure: 700kPa
2. Horn tip amplitude: 60 μm
(Example 5)
1. Horn pressure: 500kPa
2. Horn tip amplitude: 40 μm
(Example 6)
1. Horn pressure: 500kPa
2. Horn tip amplitude: 80 μm
(Comparative Example 1)
1. Horn pressure: 500kPa
2. Horn tip amplitude: 35 μm
(Comparative Example 2)
1. Horn pressure: 500kPa
2. Horn tip amplitude: 85 μm
(Comparative Example 3)
1. Horn pressure: 150kPa
2. Horn tip amplitude: 60 μm
(Comparative Example 4)
1. Horn pressure: 750 kPa
2. Horn tip amplitude: 60 μm
(Evaluation methods)
1. Welding strength: 10 kg of static load was applied for 5 minutes in the direction in which the housing upper portion 133b and the housing lower portion 133a of the developing cartridge housing 133 after welding were pulled up and down, and the results were visually confirmed.

  2. Dimensional stability: The amount of displacement between the housing upper portion 133b and the housing lower portion 133a was measured, and if the displacement amount was 0.5 mm or less, it was judged as acceptable.

  The results of the experiment are shown in Table 1.

  As can be seen from Table 1, the range in which there is no problem in the strength and dimensional stability of the welding is the range where the horn pressure is 200 to 700 kPa (Examples 1 to 4), and more preferably the range is 300 to 500 kPa. . Similarly, the range in which there is no problem in the result of welding is a range where the amplitude of the horn tip is 40 to 80 μm (Examples 5 to 6), and more preferably a range of 50 to 70 μm.

  About Examples 1-6, both the welding strength and dimensional stability were satisfactory, and the determination was acceptable.

  On the other hand, in Comparative Examples 1 and 3, the occurrence of a gap in the welded portion was visually confirmed, the welding strength was insufficient, and the determination failed. In Comparative Examples 2 and 4, the amount of deviation between the case upper portion 133b and the case lower portion 133a was 0.8 to 1.0 mm, and there was a problem in the strength and dimensional stability of the welding, and the determination was rejected.

1 is a schematic diagram illustrating an overall configuration of a full-color image forming apparatus that is one of representative embodiments of an image forming apparatus according to the present invention. FIG. 4 is a diagram for explaining a configuration in an embodiment of a developing cartridge according to the present invention. It is sectional drawing for demonstrating the welding method by the ultrasonic welding method of the developing cartridge housing | casing 133 which concerns on this invention.

Explanation of symbols

13, 13Y, 13M, 13C, 13Bk Developing cartridge 30 Developing device 133 Developing cartridge housing 133a Housing lower portion 133b Housing upper portion Ha, Hb Welding machine horn Ua, Ub Jig base Ya1, Ya2 Housing lower portion 133a Welding part Yb1, Yb2 Welding part of housing upper part 133b

Claims (2)

In the ultrasonic welding method of the developing cartridge housing for welding the developing cartridge housing used in the electrophotographic image forming apparatus using ultrasonic waves,
When welding using the ultrasonic wave, the pressure of the horn pressed against the developing cartridge housing is 200 kPa or more and 700 kPa or less, and the amplitude of the tip of the horn is 40 μm or more and 80 μm or less. An ultrasonic welding method for the developing cartridge housing. 2. The method for ultrasonic welding of a developing cartridge case according to claim 1, wherein the developing cartridge case is a developing cartridge case used in an image forming apparatus capable of forming an image on A3 size paper.

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