Image forming apparatus provided with process cartridge and toner cartridge detachably mountable therein

An image forming apparatus includes: a main casing including a cover; a process cartridge including a second toner conveying part; a transfer belt; a toner cartridge including a first toner conveying part; a secondary transfer member; and a fixing unit. The cover opens and closes an opening of the main casing by pivotally moving about a pivot axis. The transfer belt and toner cartridge are positioned upward of the process cartridge. The secondary transfer member contacts the one end of the transfer belt. The pivot axis and fixing unit are closer to the one end than to the other end of the transfer belt in the orthogonal direction. The second toner conveying part has a second opening in communication with a first opening of the first toner conveying part. The second opening is opposite the developing roller with respect to the photosensitive drum in the orthogonal direction.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2015-073409 filed Mar. 31, 2015. The entire content of the priority application is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electrophotographic type image forming apparatus, and a process cartridge mountable in the image forming apparatus.

BACKGROUND

An intermediate transfer type image forming apparatus has been known as an electrophotographic type image forming apparatus. The intermediate transfer type image forming apparatus includes a process cartridge provided with a photosensitive drum, and a transfer belt in contact with the photosensitive drum. A toner image formed on the surface of the photosensitive drum is transferred onto the transfer belt, and then the toner image is transferred onto a sheet from the transfer belt.

As such a type of image forming apparatus, there has been proposed an image forming apparatus including a process kit provided with a photosensitive drum and a developing unit, an intermediate transfer belt positioned on the process kit, a toner container positioned beside the intermediate transfer belt and accommodating toner to be supplied to the developing unit, a secondary transfer roller in contact with a front end portion of the intermediate transfer belt, and a fixing unit positioned above the secondary transfer roller.

This image forming apparatus is configured to remove the process kit from the apparatus in a diagonally upward and forward direction by upwardly retracting the intermediate transfer belt away from the process kit after the fixing unit and the secondary transfer roller are retracted forward away from the intermediate transfer belt.

SUMMARY

In view of the foregoing, it is an object of the disclosure to provide an improved image forming apparatus and a process cartridge mountable in the image forming apparatus.

In order to attain the above and other objects, according to one aspect, the disclosure provides an image forming apparatus including: a main casing; a process cartridge; a transfer belt; a toner cartridge; a secondary transfer member; a fixing unit; a first toner conveying part; and a second toner conveying part. The main casing has an opening. The main casing includes a cover configured to pivotally move about a pivot axis to open and close the opening. The process cartridge is detachably mountable in the main casing. The process cartridge includes a photosensitive drum and a developing roller. The transfer belt is positioned upward of the process cartridge and in contact with the photosensitive drum when the process cartridge has been mounted in the main casing. The transfer belt has one end and another end in an orthogonal direction orthogonal to a vertical direction and an axial direction of the photosensitive drum. The pivot axis is positioned closer to the one end of the transfer belt than to the another end of the transfer belt in the orthogonal direction. The toner cartridge is configured to accommodate toner to be supplied to the process cartridge and detachably mountable in the main casing. The toner cartridge is positioned upward of the process cartridge when the process cartridge and the toner cartridge have been mounted in the main casing. The secondary transfer member is in contact with the one end of the transfer belt. The fixing unit includes a heating body and a pressure body. The fixing unit is positioned closer to the one end of the transfer belt than to the another end of the transfer belt in the orthogonal direction. The first toner conveying part is provided at the toner cartridge and has a first opening. The second toner conveying part is provided at the process cartridge and has a second opening configured to communicate with the first opening. The second opening is positioned opposite the developing roller with respect to the photosensitive drum in the orthogonal direction.

According to another aspect, the disclosure provides a process cartridge detachably mountable in an image forming apparatus and including a developing roller and a photosensitive drum. The image forming apparatus includes: a main casing; a transfer belt; a toner cartridge; a secondary transfer member; and a fixing unit. The main casing has an opening. The main casing includes a cover configured to pivotally move about a pivot axis to open and close the opening. The transfer belt is positioned upward of the process cartridge and in contact with the photosensitive drum when the process cartridge has been mounted in the main casing. The transfer belt has one end and another end in an orthogonal direction orthogonal to a vertical direction and an axial direction of the photosensitive drum. The pivot axis is positioned closer to the one end of the transfer belt than to the another end of the transfer belt in the orthogonal direction. The toner cartridge is configured to accommodate toner to be supplied to the process cartridge and detachably mountable in the main casing. The toner cartridge is positioned upward of the process cartridge when the process cartridge and the toner cartridge have been mounted in the main casing. The toner cartridge includes a first toner conveying part having a first opening. The secondary transfer member is in contact with the one end of the transfer belt. The fixing unit includes a heating body and a pressure body. The fixing unit is positioned closer to the one end of the transfer belt than to the another end of the transfer belt in the orthogonal direction. The process cartridge is detachably mountable in the main casing and further includes a second toner conveying part having a second opening. The second opening is configured to communicate with the first opening and positioned opposite the developing roller with respect to the photosensitive drum.

DETAILED DESCRIPTION

An image forming apparatus1according to one embodiment will be described with reference to the accompanying drawings, wherein like parts and components are designated by the same reference numerals to avoid duplicating description. Directions referred to in the following description are based on directions indicated in the drawings.

1. Overall Structure of Image Forming Apparatus

As shown inFIG. 1, the image forming apparatus1is a laser printer. The image forming apparatus1includes a main casing2formed with an opening2A (FIG. 12); a plurality of (four) process cartridges3; a plurality of (four) toner cartridges18(FIG. 9); a scanning unit4; a belt unit5; a secondary transfer roller6as an example of a secondary transfer member; a fixing unit7; and a reading unit26.

The main casing2is box-shaped, and is provided with a cover8and a supply tray9.

As shown inFIG. 12, the opening2A is positioned at an upper end portion of the main casing2to provide communication between an interior and exterior of the main casing2in a vertical direction. The opening2A allows the plurality of process cartridges3to pass therethrough.

As shown inFIG. 1, the cover8is disposed at the upper end portion of the main casing2. The cover8has a plate shape that is elongated in a front-rear direction (an example of an orthogonal direction). The cover8is supported at an upper end portion of the belt unit5. The cover8is pivotally movable together with the belt unit5about an axis of shaft parts86A of a pivot member86(described later) between an open position opening the opening2A (FIG. 12) and a closed position closing the opening2A (FIG. 1). The pivot axis of the cover8(i.e. axis of the shaft parts86A) is positioned rearward of the cover8.

The supply tray9is disposed at a lower end portion of the main casing2. The supply tray9is configured to accommodate sheets P.

The plurality of process cartridges3is detachable from and attachable to the main casing2. When attached to the main casing2, the four process cartridges3are arrayed in the front-rear direction with a space between neighboring process cartridges3. Each process cartridge3can be detached from the main casing2to an outside through the opening2A as shown inFIG. 12. As shown inFIG. 3A, each of the four process cartridges3includes a drum unit10and a developing unit11.

The drum unit10includes a photosensitive drum12and a charging roller13as an example of a charging member.

The photosensitive drum12is positioned at an upper end portion of the drum unit10. The photosensitive drum12has a cylindrical shape that extends in a left-right direction (an example of an axial direction).

The charging roller13is positioned downward of the photosensitive drum12. The charging roller13is in contact with a lower end portion of the photosensitive drum12. The charging roller13is configured to charge a surface of the photosensitive drum12.

The developing unit11is positioned diagonally forward and downward of the photosensitive drum12. The developing unit11includes a developing roller15, a supply roller16, and a blade17.

The developing roller15is positioned at an upper end portion of the developing unit11. The developing roller15is in contact with a front end portion of the photosensitive drum12. The developing roller15is configured to supply toner to the photosensitive drum12.

The supply roller16is positioned diagonally forward and downward of the developing roller15. The supply roller16is in contact with a lower-front end portion of the developing roller15. The supply roller16is configured to supply toner to the developing roller15.

The blade17is positioned diagonally rearward and downward of the developing roller15. The blade17is in contact with a lower-rear end portion of a roller portion15A (described later) of the developing roller15. The blade17is configured to regulate a thickness of a toner layer formed over a surface of the developing roller15.

As shown inFIGS. 2 and 9, the plurality of toner cartridges18are positioned diagonally upward and rightward of the plurality of process cartridges3, respectively. The plurality of toner cartridges18is detachable from and attachable to the main casing2. In a state where the process cartridges3and the toner cartridges18are attached to the main casing2, the toner cartridges18are positioned upward of the corresponding process cartridges3. Each of the toner cartridges18is generally box-shaped having a bottom wall formed in an arcuate shape. Each toner cartridge18is configured to accommodate therein toner. Toner accommodated in the toner cartridge18is conveyed to the corresponding developing unit11.

As shown inFIG. 1, the scanning unit4is positioned downward of the four process cartridges3. The scanning unit4is configured to irradiate a laser beam L based on image data. The laser beam L is incident on the surface of each photosensitive drum12, passing between the developing unit11and the corresponding charging roller13.

The belt unit5is positioned upward of the four process cartridges3when the process cartridges3are attached to the main casing2. The belt unit5extends in the front-rear direction. The belt unit5includes a first roller19positioned at a rear end portion of the belt unit5; a second roller20positioned at a front end portion of the belt unit5; a third roller21positioned diagonally forward and downward of the first roller19; a transfer belt22; and a plurality of (four) primary transfer rollers23.

The transfer belt22is looped over the first roller19, the second roller20, and the third roller21. The transfer belt22has a lower portion that is in contact with the four photosensitive drums12. The transfer belt22is circularly movable around the first roller19, the second roller20, and the third roller21such that the lower portion of the transfer belt22is moved rearward.

The four primary transfer rollers23are arrayed in the front-rear direction between the second roller20and the third roller21, with a space between neighboring primary transfer rollers23. The primary transfer rollers23are positioned upward of the corresponding photosensitive drums12, with the transfer belt22interposed therebetween.

The secondary transfer roller6is positioned rearward of the first roller19. The secondary transfer roller6is in contact with a rear end portion (an example of one end in the orthogonal direction) of the transfer belt22. The secondary transfer roller6nips the transfer belt22in cooperation with the first roller19.

The fixing unit7is positioned upward of the rear end portion of the transfer belt22and the secondary transfer roller6. That is, the fixing unit7is positioned closer to the rear end portion of the transfer belt22than to a front end portion of the transfer belt22in the front-rear direction. The fixing unit7includes a heating roller24as an example of a heating body, and a pressure roller25as an example of a pressure body in pressure contact with the heating roller24.

The reading unit26is positioned above the main casing2. More specifically, the reading unit26is positioned upward of the cover8with a gap therebetween. The reading unit26is a flat-bed type image scanner. The reading unit26is configured to read image data from an original document.

Upon start of an image-forming operation in the image forming apparatus1, the scanning unit4irradiates the laser beam L, so that the surfaces of the photosensitive drums12are exposed to the laser beam L. Thus, electrostatic latent images based on image data are formed on the surfaces of the photosensitive drums12, respectively.

Then, toner is supplied onto the electrostatic latent images on the surfaces of the photosensitive drums12by the corresponding developing rollers15. Thus, toner images are carried on the surfaces of the respective photosensitive drums12.

Then, the toner images on the surfaces of the photosensitive drums12are transferred onto the transfer belt22.

In the meantime, the sheets P are supplied from the supply tray9one at a prescribed timing to a position between the transfer belt22and the secondary transfer roller6. The toner image on the transfer belt22is transferred onto the sheet P when the sheet P passes between the transfer belt22and the secondary transfer roller6.

Subsequently, the sheet P is heated and pressed when the sheet P passes between the heating roller24and the pressure roller25. Thus, the toner image carried on the sheet P is thermally fixed onto the sheet P.

Then, the sheet P is delivered onto the cover8.

2. Process Cartridge

As shown inFIGS. 3A and 8A, each of the process cartridges3includes the drum unit10, the developing unit11, and a second toner conveying part51.

(1) Drum Unit

As shown inFIGS. 3A, 3B, and 5, the drum unit10includes a left side plate31L, a right side plate31R, a drum cleaner32, and a handle33.

The left side plate31L is positioned at a left end portion of the drum unit10. The left side plate31L extends both in the vertical direction and in the front-rear direction. The left side plate31L includes a support part35.

The support part35is positioned at an upper end portion of the left side plate31L. The support part35has a cylindrical shape that extends in the left-right direction. A left end portion of the photosensitive drum12is rotatably fitted into the support part35.

The right side plate31R is positioned at a right end portion of the drum unit10. The right side plate31R has a configuration the same as that of the left side plate31L. A right end portion of the photosensitive drum12is rotatably fitted into the support part35of the right side plate31R.

As shown inFIGS. 6 and 7, the drum cleaner32is positioned rearward of the photosensitive drum12and the charging roller13. The drum cleaner32is positioned between the left side plate31L and the right side plate31R. The drum cleaner32is spaced apart from the right side plate31R. A left end portion of the drum cleaner32is connected to the left side plate31L, while a right end portion of the drum cleaner32is connected to the right side plate31R through a connecting wall34at a lower end portion thereof. The drum cleaner32includes an accommodation part37having an opening37A and an opening37B; a blade38; an auger screw36; and a seal39.

The accommodation part37has a flattened box shape and is elongated both in the vertical direction and in the left-right direction. The accommodation part37has a lower wall37C that slopes rearward toward a top side thereof.

The opening37A is positioned at an upper end portion of the accommodation part37. The opening37A penetrates a front wall of the accommodation part37in the front-rear direction. The opening37A faces a rear portion of a circumferential surface of the photosensitive drum12.

The opening37B is positioned at a lower-right end portion of the accommodation part37. The opening37B penetrates the lower wall37C of the accommodation part37.

The blade38is positioned at an upper end portion of the drum cleaner32. The blade38has a plate shape that is elongated both in the vertical direction and in the left-right direction. The blade38is attached to a front surface of the accommodation part37on a lower edge portion of the opening37A. An upper end portion of the blade38is positioned within the opening37A and in contact with the rear portion of the circumferential surface of the photosensitive drum12.

The auger screw36is positioned at a lower end portion of the accommodation part37. The auger screw36extends in the left-right direction.

The seal39is attached to a lower-rear surface of the lower wall37C of the accommodation part37on an edge portion of the opening37B. The seal39has a rectangular frame-like shape. The seal39surrounds the opening37B. The seal39is formed of a sponge, for example.

As shown inFIG. 3A, the handle33is positioned at an upper-front end portion of the drum unit10. The handle33is pivotally movable between an upright position (indicated by dashed lines inFIG. 3A) extending vertically upward, and an inclined position (indicated by solid lines inFIG. 3A) inclined forward from the upright position.

(2) Developing Unit

As shown inFIGS. 3A and 4, the developing unit11is positioned between the left side plate31L and the right side plate31R. The developing unit11is pivotally movable about a support shaft48(described later) between a contact position (FIG. 8A) in which the developing roller15is in contact with the photosensitive drum12, and a separated position (FIG. 8B) in which the developing roller15is separated from the photosensitive drum12.

The following description of the developing unit11will be based on the developing unit11being in its contact position.

The developing unit11includes a frame40, the developing roller15, the supply roller16, the blade17, an auger screw47, a plurality of seals46, and the support shaft48.

The frame40has a box shape with an upper-rear opening. The frame40includes a left side wall41L, a right side wall41R having an opening41A, a lower wall42, a front wall43, and a rear wall44.

The left side wall41L is positioned at a left end portion of the developing unit11. The left side wall41L is positioned rightward of the left side plate31L and spaced apart from the left side plate31L. The left side wall41L extends both in the vertical direction and in the front-rear direction. The left side wall41L includes a support part45L.

The support part45L is positioned between a left end portion of the auger screw47and a left end portion of the developing roller15. The support part45L protrudes rightward from a right surface of the left side wall41L. The support part45L has a plate shape that extends in the left-right direction.

The right side wall41R is positioned at a right end portion of the developing unit11. The right side wall41R is positioned leftward of the right side plate31R and spaced apart from the right side plate31R. The right side wall41R extends both in the vertical direction and in the front-rear direction. The right side wall41R includes a support part45R.

The opening41A is positioned at a lower-rear end portion of the right side wall41R. The opening41A penetrates the right side wall41R in the left-right direction. The opening41A has a circular shape in a side view.

The support part45R is positioned between a right end portion of the auger screw47and a right end portion of the developing roller15. The support part45R protrudes leftward from a left surface of the right side wall41R. The support part45R has a plate shape that extends in the left-right direction.

The lower wall42constitutes a lower wall of the developing unit11. The lower wall42is positioned between the left side wall41L and the right side wall41R. The lower wall42extends both in the left-right direction and in the front-rear direction. A left edge of the lower wall42is connected to a lower edge of the left side wall41L, while a right edge of the lower wall42is connected to a lower edge of the right side wall41R.

The front wall43constitutes a front wall of the developing unit11. The front wall43extends upward from a front edge of the lower wall42. A left edge of the front wall43is connected to a front edge of the left side wall41L, while a right edge of the front wall43is connected to a front edge of the right side wall41R.

The rear wall44constitutes a rear wall of the developing unit11. The rear wall44extends upward from a rear edge of the lower wall42. A left edge of the rear wall44is connected to a rear edge of the left side wall41L, while a right edge of the rear wall44is connected to a rear edge of the right side wall41R.

(2-2) Developing Roller

The developing roller15includes the roller portion15A and a shaft15B.

The roller portion15A constitutes an outer circumferential portion of the developing roller15in a radial direction of the developing roller15. The roller portion15A extends in the left-right direction. The roller portion15A has a cylindrical shape.

The shaft15B constitutes a center portion of the developing roller15in the radial direction of the developing roller15. The shaft15B extends in the left-right direction. The shaft15B has a columnar shape. The shaft15B is inserted into an interior of the roller portion15A such that an outer circumferential surface of the shaft15B is in contact with an inner circumferential surface of the roller portion15A. A left end portion of the shaft15B protrudes further leftward than a left end face of the roller portion15A and is rotatably supported at the left side wall41L. Similarly, a right end portion of the shaft15B protrudes further rightward than a right end face of the roller portion15A and is rotatably supported at the right side wall41R.

(2-3) Supply Roller

The supply roller16includes a roller portion16A and a shaft16B.

The roller portion16A constitutes an outer circumferential portion of the supply roller16in a radial direction of the supply roller16. The roller portion16A extends in the left-right direction. The roller portion16A has a cylindrical shape. The roller portion16A is in contact with a lower-front end portion of the roller portion15A.

The shaft16B constitutes a center portion of the supply roller16in the radial direction of the supply roller16. The shaft16B extends in the left-right direction. The shaft16B has a columnar shape. The shaft16B is inserted into an interior of the roller portion16A such that an outer circumferential surface of the shaft16B is in contact with an inner circumferential surface of the roller portion16A. A left end portion of the shaft16B protrudes further leftward than a left end face of the roller portion16A and is rotatably supported at the left side wall41L. Similarly, a right end portion of the shaft16B protrudes further rightward than a right end face of the roller portion16A and is rotatably supported at the right side wall41R.

The blade17includes a support plate17A and a contact part17B.

The support plate17A has a plate shape that is elongated both in the front-rear direction and in the left-right direction. The support plate17A is formed of metal, for example. A rear end portion of the support plate17A is supported at an upper end portion of the rear wall44.

The contact part17B is supported on an upper surface of the support plate17A at a front end portion thereof. The contact part17B has a plate shape that is elongated in the left-right direction. The contact part17B is formed of rubber, for example. The contact part17B is in contact with a lower portion of an outer circumferential surface of the developing roller15.

The auger screw47is positioned rearward of the supply roller16and downward of the developing roller15. The auger screw47extends in the left-right direction.

The plurality of seals46includes a seal46A that seals a gap between a left end of the support plate17A and the support part45L; a seal46B that seals a gap between the left end of the support plate17A and a left end portion of the roller portion15A; a seal46C that seals a gap between a right end of the support plate17A and the support part45R; and a seal46D that seals a gap between the right end of the support plate17A and a right end portion of the roller portion15A. The seals46each have a plate shape that extends in the left-right direction. The seals46are formed of a sponge, for example.

(2-7) Support Shaft

The support shaft48is positioned at an upper end portion of the developing unit11. The support shaft48has a columnar shape that extends in the left-right direction. The support shaft48extends through the upper end portion of the developing unit11. A left end portion of the support shaft48protrudes further leftward than the left side wall41L and is rotatably supported at an upper end portion of the left side plate31L. Similarly, a right end portion of the support shaft48protrudes further rightward than the right side wall41R and is rotatably supported at an upper end portion of the right side plate31R.

(3) Second Toner Conveying Part

As shown inFIGS. 6 and 8A, the second toner conveying part51is positioned at a right end portion of the process cartridge3. The second toner conveying part51is positioned between the right side plate31R and the drum cleaner32, and is also positioned between the right side plate31R and the developing unit11. The second toner conveying part51includes a third toner conveying part52, a fourth toner conveying part53, a connecting member54, and a screw58.

The third toner conveying part52is positioned rearward of the photosensitive drum12. The third toner conveying part52is positioned between the right side plate31R and the drum cleaner32. The third toner conveying part52is supported at the drum unit10. The third toner conveying part52includes a wall part55having a second opening55A, a tubular part56, and a seal59.

The wall part55is positioned between an upper-rear end portion of the right side plate31R and an upper-rear end portion of the drum cleaner32. The wall part55has a plate shape that extends in the left-right direction. A right edge of the wall part55is connected to a left surface of the right side plate31R. A left edge of the wall part55is connected to a right surface of the drum cleaner32. The wall part55slopes forward toward a top side thereof.

The second opening55A is positioned at a center portion of the wall part55in the left-right direction. The second opening55A is positioned opposite the developing roller15with respect to the photosensitive drum12in the front-rear direction. That is, the second opening55A is positioned rearward of the photosensitive drum12. Further, the second opening55A is positioned further rightward than the developing roller15(FIG. 4). Further, the second opening55A is positioned further rightward than a corresponding discharge opening106A (described later) (FIG. 2). The second opening55A penetrates the wall part55.

The tubular part56is positioned downward of the wall part55. The tubular part56extends downward from an edge of the second opening55A on a lower-front surface of the wall part55.

The seal59is attached to an upper-rear surface of the wall part55on an edge portion of the second opening55A. The seal59has a rectangular frame-like shape. The seal59surrounds the second opening55A. The seal59is formed of a sponge, for example.

As shown inFIGS. 4 and 8A, the fourth toner conveying part53is positioned downward of the photosensitive drum12. The fourth toner conveying part53extends in the front-rear direction. The fourth toner conveying part53is positioned rightward of the charging roller13(FIG. 3A). That is, the fourth toner conveying part53overlaps the charging roller13when viewed in the left-right direction. The fourth toner conveying part53is supported at the developing unit11. A front end portion of the fourth toner conveying part53is connected to a lower-rear end portion of the right side wall41R and is in communication with the opening41A. A rear end portion of the fourth toner conveying part53is positioned downward of the third toner conveying part52. The rear end portion of the fourth toner conveying part53is bent upward to extend upward, and faces a lower end portion of the tubular part56. A portion of the fourth toner conveying part53that extends in the front-rear direction constitutes a second portion of the second toner conveying part51.

The screw58is positioned inside the fourth toner conveying part53. The screw58is a coil formed of metal, for example. A front end portion of the screw58is connected to a right end portion of the auger screw47.

As shown inFIGS. 6 and 8A, the connecting member54is provided to surround a lower end portion of the third toner conveying part52and a rear end portion of the fourth toner conveying part53. The connecting member54is formed of an elastic material such as sponge or rubber, for example. The connecting member54has a cylindrical shape. The lower end portion of the third toner conveying part52is inserted into an upper end portion of the connecting member54. The rear end portion of the fourth toner conveying part53is inserted into a lower end portion of the connecting member54. With this arrangement, the connecting member54connects the fourth toner conveying part53to the third toner conveying part52such that the fourth toner conveying part53is movable relative to the third toner conveying part52. The tubular part56of the third toner conveying part52, a portion of the rear end portion of the fourth toner conveying part53that extends upward, and the connecting member54constitute a first portion of the second toner conveying part51.

3. Main Casing

As shown inFIGS. 2 and 10, the main casing2includes a casing80having an opening80A; a frame81; a plurality of (four) support parts82; a plurality of (four) main-casing toner conveying parts83; a belt cleaner93; a toner discharge part84; an accommodation part85; and the pivot member86.

(1) Casing and Frame

As shown inFIG. 2, the casing80constitutes an exterior of the main casing2. The casing80has a box shape. The casing80is formed of resin, for example. The casing80includes a side cover87.

The opening80A is positioned at an upper-right end portion of the casing80. The opening80A is positioned rightward of the support parts82. The opening80A penetrates a right wall of the casing80in the left-right direction.

The side cover87is positioned at the upper-right end portion of the casing80. The side cover87has a plate shape that extends in the vertical direction. The side cover87is pivotally movable about a lower end thereof between an open position (indicated by dashed lines inFIG. 2) that opens the opening80A and a closed position (indicated by solid lines inFIG. 2) that closes the opening80A.

The frame81is disposed inside the casing80. The frame81is formed of metal, such as stainless steel or steel, for example. The frame81includes a left side plate71L; a right side plate71R having a plurality of (four) insertion holes71A and an insertion hole71B (FIG. 9); a lower plate72, a left positioning plate73L having a plurality of (four) recessed parts73A; and a right positioning plate73R having a plurality of (four) recessed parts73A.

The left side plate71L is positioned inside the casing80and at a left end portion of the casing80. The left side plate71L is elongated both in the vertical direction and in the front-rear direction. The left side plate71L includes a plurality of (four) main-casing guide parts74(FIG. 12).

As shown inFIG. 12, the main-casing guide parts74are positioned on an inner surface (right surface) of the left side plate71L. The main-casing guide parts74have a U-shape in a side view with a top opening. The main-casing guide parts74extend in a direction from upper front to lower rear. That is, each of the main-casing guide parts74slopes forward toward a top side thereof. Each main-casing guide part74receives the support part35of the left side plate31L. The main-casing guide part74guides the support part35of the left side plate31L into the recessed part73A of the left positioning plate73L. With this configuration, the main-casing guide parts74guide the process cartridges3when the process cartridges3are mounted in and removed from the main casing2. The four main-casing guide parts74are arrayed at intervals in the front-rear direction.

The right side plate71R is positioned inside the casing80and at a right end portion of the casing80. The right side plate71R is positioned rightward of the left side plate71L and spaced apart from the left side plate71L. The right side plate71R has the same shape as the left side plate71L, except that the insertion holes71A and the insertion holes71B are formed. Each main-casing guide part74of the right side plate71R receives the support part35of the right side plate31R. The main-casing guide part74of the right side plate71R guides the support part35of the right side plate31R into the recessed part73A of the right positioning plate73R.

As shown inFIGS. 2 and 9, the insertion holes71A are positioned diagonally upward and rearward of the corresponding process cartridges3when viewed in the left-right direction. The plurality of insertion holes71A are arrayed at intervals in the front-rear direction. The insertion holes71A penetrate the right side plate71R in the left-right direction. The insertion holes71A have a circular shape in a side view.

As shown inFIG. 9, the insertion hole71B is positioned at a lower-rear end portion of the right side plate71R. The insertion hole71B penetrates the right side plate71R in the left-right direction. The insertion hole71B has a circular shape in a side view.

As shown inFIG. 2, the lower plate72is positioned downward of the scanning unit4. The lower plate72extends in the left-right direction. A left edge of the lower plate72is connected to the left side plate71L. A right edge of the lower plate72is connected to the right side plate71R.

The left positioning plate73L is positioned between the left side plate71L and the scanning unit4. The left positioning plate73L is elongated both in the vertical direction and in the front-rear direction. A lower end portion of the left positioning plate73L is bent leftward and connected to the lower plate72.

As shown inFIGS. 2 and 12, the recessed parts73A of the left positioning plate73L are positioned at an upper end portion of the left positioning plate73L. The recessed parts73A are recessed downward from an upper edge of the left positioning plate73L. The recessed parts73A have a U-shape with a top opening. The four recessed parts73A are arrayed at intervals in the front-rear direction.

The right positioning plate73R is positioned between the right side plate71R and the scanning unit4. The right positioning plate73R has the same shape as the left positioning plate73L.

(2) Toner Cartridge, Support Part, and Main-Casing Toner Conveying Part

As shown inFIGS. 2 and 9, each of the toner cartridges18includes a first agitator91, and a first toner conveying part92having a first opening92A.

The first agitator91is positioned inside the toner cartridge18at its a lower-rear end portion. The first agitator91is configured to convey toner accommodated in the toner cartridge18toward the first toner conveying part92.

The first toner conveying part92is positioned at a lower-front end portion of the toner cartridge18. The first toner conveying part92extends downward from a front end portion of the toner cartridge18. The first toner conveying part92has a square cylindrical shape. The first toner conveying part92includes a second agitator92B.

The first opening92A is formed on a rear wall of the first toner conveying part92at a lower end portion thereof. The first opening92A penetrates the rear wall at the lower end portion of the first toner conveying part92in the front-rear direction.

The second agitator92B is positioned inside the first toner conveying part92at the lower end portion thereof. The second agitator92B is configured to convey toner in the first toner conveying part92toward the first opening92A.

The plurality of support parts82is positioned diagonally upward and rightward of the plurality of process cartridges3, respectively. Each support part82has an arcuate shape that conforms to a part of a lower wall of the toner cartridge18.

The plurality of main-casing toner conveying parts83is positioned downward of the plurality of support parts82, respectively. Each main-casing toner conveying part83connects the first toner conveying part92and the second toner conveying part51. Each main-casing toner conveying part83includes a wall part61having an opening61A, a first part62, and a second part63.

The wall part61is positioned downward of a front end portion of the support part82. The wall part61extends in the vertical direction. An upper edge of the wall part61is connected to a front edge of the support part82.

The opening61A is formed on the wall part61at its lower end portion. The opening61A penetrates the wall part61in the front-rear direction. The opening61A can communicate with the first opening92A of the toner cartridge18.

The first part62is positioned rearward of the wall part61. The first part62extends diagonally downward and rearward from a rear surface of the wall part61on an edge portion of the first opening92A. The first part62has a square cylindrical shape.

As shown inFIGS. 2 and 10, the second part63extends leftward from a lower end portion of the first part62. The second part63has a cylindrical shape. The second part63includes a wall64having a third opening64A, and an auger screw65.

The wall64is positioned at a left end portion of the second part63at a lower-front end portion thereof. The wall64slopes forward toward a top side thereof. The wall64has a plate shape that extends in the left-right direction. The wall64includes a seal66.

The third opening64A is positioned at a center portion of the wall64. The third opening64A penetrates the wall64. The third opening64A can communicate with the second opening55A of the process cartridge3.

The seal66is attached to a lower-front surface of the wall64on an edge portion of the third opening64A. The seal66has a rectangular frame-like shape. The seal66surrounds the third opening64A. The seal66is formed of a sponge, for example. The seal66contacts the seal59of the process cartridge3.

The auger screw65is positioned inside the second part63. The auger screw65extends in the left-right direction.

(3) Belt Cleaner, Toner Discharge Part, and Accommodation Part

As shown inFIG. 11, the belt cleaner93is positioned at a front end portion of the belt unit5. The belt cleaner93includes an accommodation part94having an opening94A and an opening94B; a blade95; and an auger screw97.

The accommodation part94has a box shape that is elongated in the left-right direction.

The opening94A is positioned at an upper end portion of the accommodation part94. The opening94A penetrates a rear wall of the accommodation part94in the front-rear direction. The opening94A faces the front end portion of the transfer belt22.

The opening94B is positioned at a right end portion of the accommodation part94. The opening94B penetrates a lower wall of the accommodation part94in the vertical direction.

The blade95is positioned at an upper end portion of the belt cleaner93. The blade95has a plate shape that is elongated both in the vertical direction and in the left-right direction. The blade95is attached to a rear surface of the accommodation part94on a lower edge of the opening94A. An upper edge of the blade95is positioned within the opening94A and contacts a front portion of an outer surface of the transfer belt22.

The auger screw97is positioned inside the accommodation part94at a lower end portion thereof. The auger screw97extends in the left-right direction.

As shown inFIGS. 2 and 11, the toner discharge part84is positioned between the right positioning plate73R and the scanning unit4. The toner discharge part84includes a main part101; an auger screw105; a connecting part102having an opening102A; a plurality of (four) connecting parts103; and a connecting part104.

The main part101is positioned between right end portions of the process cartridges3and the lower plate72. The main part101is elongated in the front-rear direction. The main part101has a cylindrical shape.

The auger screw105is positioned inside the main part101. The auger screw105extends in the front-rear direction.

The connecting part102is connected to the belt cleaner93. The connecting part102extends upward from a front end portion of the main part101. The connecting part102has a cylindrical shape. An upper wall of the connecting part102has an arcuate shape that conforms to a shape of a lower wall of the belt cleaner93.

The opening102A is positioned at an upper end portion of the connecting part102. The opening102A penetrates the upper wall of the connecting part102in the vertical direction. The opening102A can communicate with the opening94B of the belt cleaner93.

The connecting parts103are connected to the process cartridges3, respectively. The plurality of connecting parts103is positioned rearward of the connecting part102. The plurality of connecting parts103is arrayed at intervals in the front-rear direction. The plurality of connecting parts103extends upward from an upper portion of a circumferential wall of the main part101. Each connecting part103has a cylindrical shape. The connecting part103includes a wall part106having the discharge opening106A.

The wall part106is positioned at an upper end portion of the connecting part103. The wall part106slopes rearward toward a top side thereof. The wall part106has a plate shape that extends in the left-right direction. The wall part106includes a seal107.

The discharge opening106A is positioned at a center portion of the wall part106. The discharge opening106A penetrates the wall part106. The discharge opening106A can communicate with the opening37B of the process cartridge3.

The seal107is attached to an upper-front surface of the wall part106on an edge portion of the discharge opening106A. The seal107has a rectangular frame-like shape. The seal107surrounds the discharge opening106A. The seal107is formed of a sponge, for example. The seal107contacts the seal39of the process cartridge3.

As shown inFIGS. 9 and 11, the connecting part104is connected to the accommodation part85. The connecting part104extends downward from a rear end portion of the main part101, and is bent rightward at its lower end portion to extend rightward. A right end portion of the connecting part104protrudes further rightward than the right side plate71R through the insertion hole71B formed in the right side plate71R. The connecting part104has a cylindrical shape.

As shown inFIGS. 2 and 9, the accommodation part85is positioned between a lower end portion of the right side plate71R and a lower end portion of a right wall of the casing80. The accommodation part85has a box shape that is elongated in the front-rear direction. An upper-rear end portion of the accommodation part85is in communication with the right end portion of the connecting part104.

(4) Pivot Member

As shown inFIGS. 9 and 12, the pivot member86is positioned at an upper-rear end portion of the main casing2. The pivot member86is fixed to a rear end portion of the belt unit5, and is pivotally movably supported at an upper-rear end portion of the left side plate71L and an upper-rear end portion of the right side plate71R. The pivot member86includes a pair of shaft parts86A, a pair of arms86B, and a support shaft86C.

One of the shaft parts86A is disposed at a left end portion of the pivot member86, while the other of the shaft parts86A is disposed at a right end portion of the pivot member86. The pair of shaft parts86A overlaps the fixing unit7when viewed in the left-right direction. The left shaft part86A is pivotally movably supported at the upper-rear end portion of the left side plate71L. The right shaft part86A is pivotally movably supported at the upper-rear end portion of the right side plate71R. The shaft parts86A have a cylindrical shape that extends in the left-right direction.

One of the arms86B is disposed at the left end portion of the pivot member86, while the other of the arms86B is disposed at a right end portion of the pivot member86. The left arm86B is positioned leftward of the left side plate71L and extends diagonally forward and downward from a peripheral surface of the left shaft part86A. The right arm86B is positioned rightward of the right side plate71R and extends diagonally forward and downward from a peripheral surface of the right shaft part86A. The arms86B have a plate shape.

The support shaft86C has a columnar shape that extends in the left-right direction. The support shaft86C extends through the rear end portion of the belt unit5in the left-right direction. A left end portion of the support shaft86C is connected to a lower-front end portion of the left arm86B, while a right end portion of the support shaft86C is connected to a lower-front end portion of the right arm86B.

The reading unit26is connected to the shaft parts86A of the pivot member86through connecting parts (not shown). Accordingly, the cover8, the belt unit5, and the reading unit26are pivotally movable together about the axis of the shaft parts86A of the pivot member86.

4. Conveyance of Toner

(1) Toner Supply to Developing Unit

As shown inFIG. 9, toner accommodated in the toner cartridge18is conveyed toward the first toner conveying part92as the first agitator91rotates. Then, toner conveyed into the first toner conveying part92is supplied to the first part62of the main-casing toner conveying part83through the first opening92A and the opening61A as the second agitator92B rotates. Toner supplied into the first part62falls diagonally rearward and downward inside the first part62due to gravity.

Toner fallen diagonally rearward and downward inside the first part62is then conveyed leftward inside the second part63by the auger screw65, as shown inFIG. 2.

Subsequently, toner conveyed leftward inside the second part63is supplied into the third toner conveying part52of the second toner conveying part51through the third opening64A and the second opening55A, as shown inFIGS. 8A and 10.

Then, toner supplied into the third toner conveying part52is supplied to the rear end portion of the fourth toner conveying part53through the connecting member54due to gravity, as shown inFIG. 8A. Toner supplied to the fourth toner conveying part53is then supplied into the frame40through the opening41A by the screw58.

Then, as shown inFIG. 4, toner supplied into the frame40is conveyed rightward by the auger screw47. In this way, toner is supplied into the lower-rear end portion in the frame40.

Thereafter, as shown inFIG. 3A, in the image-forming operation described above, the supply roller16supplies toner to the developing roller15, and toner carried on the developing roller15is supplied onto an electrostatic latent image on the surface of the photosensitive drum12.

(2) Collection of Waste Toner

In the above-described image-forming operation, the surface of the photosensitive drum12is cleaned by the drum cleaner32after a toner image on the surface of the photosensitive drum12is transferred onto the transfer belt22.

At this time, as shown inFIGS. 6 and 7, waste toner remaining on the surface of the photosensitive drum12can be scraped off by the blade38of the drum cleaner32, and is accommodated in the accommodation part37.

The waste toner accommodated in the accommodation part37is conveyed rightward inside the accommodation part37by the auger screw36.

Then, as shown inFIG. 11, the waste toner in the accommodation part37is supplied into the corresponding connecting part103of the toner discharge part84through the opening37B and the discharge opening106A.

The waste toner supplied into the connecting part103falls downward inside the connecting part103due to gravity to be supplied into the main part101. The waste toner supplied into the main part101is conveyed rearward inside the main part101by the auger screw105.

Thereafter, as shown inFIGS. 9 and 11, the waste toner is accommodated in the accommodation part85through the connecting part104.

Further, in the above-described image-forming operation, waste toner remaining on the surface of the transfer belt22is also cleaned by the belt cleaner93, and is accommodated in the accommodation part85sequentially through the connecting part102, the main part101, and the connecting part104.

5. Mounting and Removing of Process Cartridge

Next, operations for mounting and removing the process cartridges3relative to the main casing2will be described.

When the process cartridges3have been mounted in the main casing2as shown inFIGS. 2 and 10, the seal59of each process cartridge3is in contact with the seal66of the corresponding main-casing toner conveying part83. That is, the second opening55A of the process cartridge3is in communication with the third opening64A of the main-casing toner conveying part83. In other words, the second opening55A of the process cartridge3is in communication with the first opening92A of the corresponding toner cartridge18through the main-casing toner conveying part83. Further, the seal39of the process cartridge3is in contact with the seal107of the corresponding connecting part103of the toner discharge part84. That is, communication between the opening37B of the process cartridge3and the discharge opening106A of the toner discharge part84is provided.

At this time, the process cartridge3is in its first position.

To remove any of the process cartridges3from the main casing2, a user first pivotally moves the process cartridge3clockwise in a right side view about a rotational axis of the photosensitive drum12, as shown inFIG. 12.

Through this movement, the seal59of the process cartridge3is separated from the seal66of the corresponding main-casing toner conveying part83while moving rearward and downward. Accordingly, communication between the second opening55A of the process cartridge3and the third opening64A of the main-casing toner conveying part83is interrupted. That is, communication between the second opening55A of the process cartridge3and the first opening92A of the corresponding toner cartridge18is interrupted. Further, the seal39of the process cartridge3is separated forward from the seal107of the corresponding connecting part103of the toner discharge part84. Accordingly, communication between the opening37B of the process cartridge3and the discharge opening106A of the toner discharge part84is interrupted.

At this time, the process cartridge3is in its second position.

Then, the user pulls the process cartridge3diagonally upward and forward from the main casing2. The process cartridge3is moved diagonally upward and forward along the main-casing guide parts74, and separated from the main casing2through the opening2A.

Through this operation, the process cartridge3can be completely removed from the main casing2.

To mount the process cartridge3in the main casing2, the user mounts the process cartridge3in the main casing2by performing the operation to remove the process cartridge3from the main casing2described above in reverse.

That is, the user inserts the process cartridge3into the main casing2through the opening2A. Then, the process cartridge3moves diagonally rearward and downward along the main-casing guide parts74. With this movement, the support parts35of the process cartridge3are fitted into the recessed parts73A of the left positioning plate73L and the right positioning plate73R.

Next, the user pivotally moves the process cartridge3counterclockwise in a right side view about the rotational axis of the photosensitive drum12.

Then, as shown inFIG. 10, the seal59of the process cartridge3contacts the seal66of the corresponding main-casing toner conveying part83, and the seal39of the process cartridge3contacts the seal107of the corresponding connecting part103of the toner discharge part84.

Through this operation, the process cartridge3can be completely mounted in the main casing2.

(1) According to the image forming apparatus1, as shown inFIGS. 2 and 9, the main-casing toner conveying part83that supplies toner accommodated in the toner cartridge18to the process cartridge3is disposed diagonally upward and rearward of the process cartridge3.

Further, as shown inFIG. 8A, the process cartridge3has the second opening55A that communicates with the third opening64A of the main-casing toner conveying part83. The second opening55A is positioned opposite the developing unit11relative to the photosensitive drum12. That is, the second opening55A is positioned at the rear end portion of the process cartridge3.

Accordingly, as shown inFIG. 12, in a state where the opening2A is exposed, the process cartridge3can be mounted in and removed from the main casing2so as to pass forward of the main-casing toner conveying part83without interfering with the main-casing toner conveying part83, by manipulating the process cartridge3from a front side of the main casing2.

As a result, the process cartridge3can be smoothly mounted in and removed from the main casing2from an upper-front side thereof despite the configuration in which the toner cartridge18is positioned further upward than the process cartridge3.

Further, according to the image forming apparatus1, as shown inFIG. 12, the shaft parts86A are disposed at positions overlapping the fixing unit7when viewed in the left-right direction, and the cover8and the belt unit5are integrally pivotally moved upward about the axis of the shaft parts86A of the pivot member86to open the opening2A.

Accordingly, the opening2A can be exposed through one action, and thus, the process cartridge3can be more smoothly mounted in and removed from the main casing2.

(2) According to the image forming apparatus1, as shown inFIG. 8A, the fourth toner conveying part53of the second toner conveying part51is disposed downward of the photosensitive drum12.

Accordingly, the fourth toner conveying part53can be efficiently disposed by using a space downward of the photosensitive drum12.

(3) According to the image forming apparatus1, as shown inFIGS. 3A and 8A, the fourth toner conveying part53of the second toner conveying part51overlaps the charging roller13when viewed in the left-right direction.

Accordingly, the fourth toner conveying part53can be efficiently disposed by using a space rightward of the charging roller13.

(4) According to the image forming apparatus1, as shown inFIGS. 4 and 8A, the second opening55A of the second toner conveying part51is positioned further rightward than the developing roller15.

Accordingly, toner can be supplied to the process cartridge3at a position outward of the developing roller15in the left-right direction.

(5) According to the image forming apparatus1, as shown inFIGS. 8A and 8B, the developing unit11is pivotally movable relative to the drum unit10between the contact position and the separated position. Further, the second toner conveying part51includes the third toner conveying part52that has the second opening55A and is supported at the drum unit10, and the fourth toner conveying part53that is connected to the developing unit11and is movable relative to the third toner conveying part52.

Accordingly, in a state where the second toner conveying part51is connected to the developing unit11, the developing unit11can move between the contact position and the separated position.

(6) According to the image forming apparatus1, as shown inFIGS. 8A and 8B, the second toner conveying part51includes the connecting member54that connects the third toner conveying part52and the fourth toner conveying part53.

Accordingly, the third toner conveying part52and the fourth toner conveying part53can be reliably connected to each other by the connecting member54.

As a result, toner can be reliably conveyed inside the second toner conveying part51.

(7) According to the image forming apparatus1, the connecting member54is formed of a sponge.

Accordingly, as shown inFIGS. 8A and 8B, when the developing unit11moves between the contact position and the separated position, the connecting member54can be elastically deformable to follow the movement of the fourth toner conveying part53by the elasticity of the sponge.

As a result, the third toner conveying part52and the fourth toner conveying part53can be more reliably connected to each other by the connecting member54.

(8) According to the image forming apparatus1, as shown inFIGS. 10 and 12, the process cartridge3can pivotally move inside the casing80about the rotational axis of the photosensitive drum12between the first position providing communication between the third opening64A of the main-casing toner conveying part83and the second opening55A, and the second position interrupting communication between the third opening64A of the main-casing toner conveying part83and the second opening55A.

Accordingly, the process cartridge3can be removed from the main casing2after communication between the third opening64A of the main-casing toner conveying part83and the second opening55A is interrupted by placing the process cartridge3in the second position inside the main casing2.

Further, when the process cartridge3is mounted in the main casing2, the process cartridge3is placed in the first position to allow the second opening55A to communicate with the third opening64A of the main-casing toner conveying part83after the process cartridge3is inserted into the main casing2.

As a result, the process cartridge3can be more smoothly mounted in and removed from the main casing2in a state where the third opening64A of the main-casing toner conveying part83is out of communication with the second opening55A.

(9) According to the image forming apparatus1, as shown inFIG. 12, the main casing2includes the main-casing guide parts74that slope forward toward top sides thereof. The process cartridge3is guided by the main-casing guide parts74when mounted in and removed from the main casing2.

Accordingly, the process cartridges3can be reliably mounted in and removed from the main casing2without interfering with the main-casing toner conveying part83as the main-casing guide parts74guide the process cartridge3so that the process cartridge3passes in front of the main-casing toner conveying part83.

As a result, the process cartridge3can be more smoothly mounted in and removed from the main casing2.

(10) According to the image forming apparatus1, as shown inFIG. 2, the main casing2includes the main-casing toner conveying part83that connects the first toner conveying part92of the toner cartridge18and the second toner conveying part51of the process cartridge3.

Accordingly, even if the toner cartridge18is disposed away from the process cartridge3, the toner cartridge18can be connected to the process cartridge3by the main-casing toner conveying part83.

As a result, degree of freedom in layout of the toner cartridge18and the process cartridge3can be enhanced.

(11) According to the image forming apparatus1, as shown inFIG. 10, the main-casing toner conveying part83includes the wall64having the third opening64A that faces the second opening55A. The wall64slopes forward toward a top side thereof.

Accordingly, communication between the second opening55A and the third opening64A can be easily interrupted by moving the second opening55A diagonally rearward and downward.

Specifically, in the process cartridge3, the second opening55A is positioned at an upper-rear end portion of the process cartridge3. Hence, the second opening55A can be moved diagonally rearward and downward by pivotally moving the process cartridge3clockwise in a right side view. Consequently, communication between the second opening55A and the third opening64A can be easily interrupted.

Further, as shown inFIG. 12, the main-casing guide parts74that guide mounting and removing of the process cartridge3relative to the main casing2extends in a direction from upper front to lower rear. That is, a contacting direction between the seal59of the process cartridge3and the seal66of the main-casing toner conveying part83is substantially perpendicular to a mounting-removing direction of the process cartridge3.

Accordingly, in a state where the seal59of the process cartridge3is in contact with the seal66of the main-casing toner conveying part83, the process cartridge3cannot be moved diagonally upward and forward due to friction between the seal59and the seal66.

However, the seal59can be easily separated from the seal66by pivotally moving the process cartridge3clockwise in a right side view. Thus, the process cartridge3can smoothly be removed from and mounted in the main casing2.

(12) According to the image forming apparatus1, as shown inFIG. 11, the main casing2includes the toner discharge part84connected to the drum cleaners32. The toner discharge part84has the discharge openings106A. The discharge opening106A is positioned opposite the corresponding developing roller15with respect to the corresponding photosensitive drum12in the front-rear direction. In other words, the discharge opening106A is positioned diagonally rearward and downward of the corresponding photosensitive drum12.

Accordingly, connection between the drum cleaners32and the toner discharge part84can be easily interrupted by moving the corresponding process cartridges3forward.

As a result, the process cartridge3can be smoothly mounted in and removed from the main casing2.

(13) According to the image forming apparatus1, as shown inFIGS. 2 and 11, the second opening55A is positioned further rightward than the discharge opening106A.

Accordingly, toner can be supplied to the process cartridge3at a position outward of the discharge opening106A in the left-right direction.

In the above-described embodiment, the secondary transfer roller6is exemplified as the secondary transfer member. However, an endless belt may be employed in place of the secondary transfer roller6.

In the above-described embodiment, the charging roller13is exemplified as the charging member. However, a non-contact type charger that does not require contact with the photosensitive drum12, such as a scorotron charger, may be used in place of the charging roller13.

While the description has been made in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that many modifications and variations may be made therein without departing from the spirit of the disclosure.