JP4673639B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a copying machine, a facsimile, or the like, for example, a printer, the surface of a photosensitive drum is charged by a charging roller and exposed by an LED head to form an electrostatic latent image. A toner image is formed by electrostatically adhering the toner thinned on the developing roller to the latent image, and the toner image is transferred onto a recording medium by a transfer roller to form an image. Yes. Further, toner remaining on the photosensitive drum after the transfer is removed by a cleaning device.

By the way, the photosensitive drum, the charging roller, the developing roller, the cleaning device, and the like are unitized and are detachably disposed as a developing device with respect to the main body of the printer. It is detachably arranged with respect to the main body. The main body of the developing device includes an outer casing, and the photosensitive drum, the charging roller, the developing roller, the cleaning device, and the like are supported by the outer casing. An LED head is disposed outside the developing device, and light emitted by the LED head is downstream of the charging roller in the rotation direction of the photosensitive drum and upstream of the developing roller. An exposure opening is formed in the cover member of the outer casing so as to irradiate the surface of the outer casing (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-186774

  However, in the conventional printer, when the toner cartridge is replaced, foreign matters such as toner and dust can enter the outer casing through the opening and fall on the photosensitive drum. In this case, the foreign matter on the photosensitive drum may further move to the charging roller side and adhere to the charging roller, or may accumulate at the contact portion between the charging roller and the photosensitive drum.

  As a result, periodic spots, streaks, and the like are formed in the image, and the image quality is degraded.

  The present invention provides an image forming apparatus that solves the problems of the conventional printer, can prevent periodic spots, streaks, and the like from being formed on an image, and can improve image quality. The purpose is to do.

  Therefore, in the image forming apparatus of the present invention, the image bearing member, a charging member that charges the image bearing member, and the exposure device that exposes the surface of the charged image bearing member to form an electrostatic latent image. And a developing device for forming a developer image by attaching a developer to the electrostatic latent image, an image carrier, a charging member, and a developing device, and an exterior provided with an opening for exposure by the exposure device. A housing, a drive unit that rotates the image carrier in a predetermined direction when forming an image, a downstream side of the charging member in a rotation direction of the image carrier, and an upstream side of the opening; A damming member that is disposed in contact with the image carrier and prevents foreign matter dropped on the image carrier through the opening from moving downward and collecting at a contact portion between the image carrier and the charging member; Have.

  According to the present invention, in an image forming apparatus, an image carrier, a charging member that charges the image carrier, and an exposure device that exposes the surface of the charged image carrier to form an electrostatic latent image. And a developing device for forming a developer image by attaching a developer to the electrostatic latent image, an image carrier, a charging member, and a developing device, and an exterior provided with an opening for exposure by the exposure device. A housing, a drive unit that rotates the image carrier in a predetermined direction when forming an image, a downstream side of the charging member in a rotation direction of the image carrier, and an upstream side of the opening; A damming member that is disposed in contact with the image carrier and prevents foreign matter dropped on the image carrier through the opening from moving downward and collecting at a contact portion between the image carrier and the charging member; Have.

  In this case, the foreign matter that is brought into contact with the image carrier on the downstream side of the charging member in the rotation direction of the image carrier and upstream of the opening and falls on the image carrier through the opening is downward. Since the damming member is disposed to prevent the image carrier and the charging member from accumulating at the contact portion, the foreign matter that has entered through the opening is blocked by the damming member. Therefore, the foreign matter does not adhere to the charging member or collect at the contact portion between the charging member and the image carrier. As a result, periodic spots and streaks are not formed on the image, and the image quality can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a printer as an image forming apparatus will be described.

  FIG. 2 is a schematic view of the printer according to the first embodiment of the present invention.

  As shown in the figure, a sheet feeding cassette 11 serving as a medium accommodating portion for accommodating a recording medium (not shown) is disposed at the bottom of the apparatus main body, and one sheet of recording medium is disposed adjacent to the front end of the sheet feeding cassette 11. A paper feeding mechanism for separating and feeding paper is provided. The paper feed mechanism includes paper feed rollers 12 a and 12 b and a separation roller 13, and the recording medium fed by the paper feed mechanism is sent to a transport roller unit 14 disposed at an upper portion, and further a transport roller unit 15. A plurality of image forming units that are transported by the transport belt 17 and form images of black, yellow, magenta, and cyan as the transport belt 17 as the transport member travels. Passes between the developing devices 16Bk, 16Y, 16M, and 16C as the transfer rollers and the transfer rollers 51Bk, 51Y, 51M, and 51C as the transfer devices. The transfer rollers 51Bk, 51Y, 51M, and 51C serve as developer images of the respective colors formed by the photosensitive drums 52Bk, 52Y, 52M, and 52C as image carriers in the developing devices 16Bk, 16Y, 16M, and 16C. The toner image is transferred to the recording medium to form a color toner image.

  Subsequently, the recording medium is sent to a fixing device 18 as a fixing device, and a color toner image is fixed on the recording medium in the fixing device 18 to form a color image. The recording medium discharged from the fixing device 18 is transported by the transport roller 19 and then discharged from the apparatus main body by the discharge transport roller 20.

  In order to expose the surfaces of the photosensitive drums 52Bk, 52Y, 52M, and 52C to form electrostatic latent images, the LED heads 21Bk, 21Y, 21M, and 21C as exposure devices are respectively connected to the developing devices 16Bk, 16Y, and 16M. , 16C.

  Each of the developing devices 16Bk, 16Y, 16M, and 16C is detachably disposed with respect to the printer main body, and for this purpose, an upper cover 23 is disposed on the upper portion of the printer main body so as to be freely opened and closed. The LED heads 21Bk, 21Y, 21M, and 21C are held by the upper cover 23.

  Next, the developing devices 16Bk, 16Y, 16M, and 16C will be described. Since the developing devices 16Bk, 16Y, 16M, and 16C have the same structure, the developing device 16Bk will be described, and the description of the developing devices 16Y, 16M, and 16C will be omitted.

  FIG. 1 is a cross-sectional view showing a main part of the developing device according to the first embodiment of the present invention, FIG. 3 is a cross-sectional view showing the developing device according to the first embodiment of the present invention, and FIG. It is a figure which shows the film member in 1 embodiment.

  The developing device 16Bk includes a photosensitive drum 52Bk, a charging roller 45 as a charging member that uniformly and uniformly charges the surface of the photosensitive drum 52Bk, and a developer carrier that holds toner as a developer. Development roller 46, a toner supply roller 47 as a developer supply roller for supplying toner to the development roller 46, a development blade 48 for uniformly thinning the toner supplied onto the development roller 46, and a photosensitive material after transfer. A cleaning device 49 is provided to remove the toner remaining on the body drum 52Bk.

  The photoconductive drum 52Bk is formed of a conductive base layer made of aluminum or the like and a surface layer made of an organic photoconductor, and the charging roller 45 is made of a semiconductive roll-shaped rubber such as epichlorohydrin rubber on a conductive metal shaft. The developing roller 46 is formed by coating a conductive metal shaft with a semiconductive rubber such as silicone, and the toner supply roller 47 provides toner transportability to the conductive metal shaft. In order to improve, it is formed by coating a rubber formed by adding a foaming agent during kneading.

  The charging roller 45, the developing roller 46, and the cleaning device 49 are disposed in contact with the photosensitive drum 52Bk, and the toner supply roller 47 and the developing blade 48 are disposed in contact with the developing roller 46. A power supply for a developing roller, a power supply for a toner supply roller, and a power supply for a development blade (not shown) are connected to the development roller 46, the toner supply roller 47, and the development blade 48, respectively, and the development roller 46, the toner supply roller 47, and the development blade are connected. A bias voltage is applied to 48.

  Meanwhile, a toner cartridge 26 containing toner is detachably disposed on the main body of the developing device 16Bk. The main body of the developing device 16Bk includes an outer casing 27, and the outer casing 27 includes a base frame member 28 as a first case and a cover member 29 as a second case. The photosensitive drum 52Bk and the charging roller 45 are rotatably supported by side frames (not shown) of the base frame member 28 at both ends in the axial direction. The developing roller 46, the toner supply roller 47, and the developing blade 48 constitute a developing device, and are similarly supported by the side frames at both ends in the axial direction.

  Further, an LED head 21Bk is disposed outside the developing device 16Bk, and light emitted by the LED head 21Bk is sent from the charging roller 45 in the rotation direction of the photosensitive drum 52Bk (rotation direction when forming an image). An opening 30 for exposure is formed in the cover member 29 so as to irradiate the surface of the photosensitive drum 52Bk on the downstream side and on the upstream side of the developing roller 46.

  In the printer configured as described above, at the time of printing, the developing roller 46 and the toner supply roller 47 are both rotated clockwise by a drive motor as a developer supplying drive unit, and the toner supply roller 47 causes the toner to be supplied to the developing roller 46. Is supplied. The toner supplied to the developing roller 46 is sent to the contact portion between the developing roller 46 and the developing blade 48 as the developing roller 46 rotates, and excess toner is scraped off by the developing blade 48 to reduce the thickness. Thereafter, the toner is sent to the photosensitive drum 52Bk as the developing roller 46 rotates.

  On the other hand, the photosensitive drum 52Bk is rotated in a predetermined direction (counterclockwise (in the direction of arrow A in FIG. 1)) by driving a drum motor as a driving unit for image formation, and the photosensitive drum 52Bk Along with the rotation, the surface of the photosensitive drum 52Bk is uniformly and uniformly charged by the charging roller 45, and is exposed by the LED head 21Bk (FIG. 2) to form an electrostatic latent image. The toner on the developing roller 46 is electrostatically attached to the electrostatic latent image to form a toner image.

  Next, the case where the toner cartridge 26 is replaced will be described.

  First, when the upper cover 23 of the printer is opened, the LED head 21Bk is moved upward accordingly, and as a result, a space is formed above the opening 30. The toner cartridge 26 includes a shutter mechanism (not shown) so that the toner does not spill during attachment / detachment. However, the toner cartridge 26 is not perfect and may spill out in the vicinity of the outer casing 27.

  The spilled toner further enters the outer casing 27 through the opening 30 and may fall and accumulate on the photosensitive drum 52Bk. Further, when the toner cartridge 26 is replaced, dust in addition to the toner may enter the outer casing 27 through the opening 30 and may fall and accumulate on the photosensitive drum 52Bk.

  In that case, when the photosensitive drum 52Bk is rotated, foreign matter such as accumulated toner and dust moves to the charging roller 45 side due to vibration of the photosensitive drum 52Bk and adheres to the charging roller 45, or If it accumulates in the contact portion with the photosensitive drum 52Bk, periodic spots, streaks, etc. are formed in the image, and the image quality deteriorates.

  Therefore, the foreign matter that has entered the outer casing 27 may move toward the charging roller 45 toward a predetermined location downstream of the charging roller 45 and upstream of the opening 30 in the rotation direction of the photosensitive drum 52Bk. The film 32 as a blocking member is disposed in contact with the photosensitive drum 52Bk so as not to be present. In this case, the film 32 is adhered to the inner peripheral surface of the cover member 29 so as to come into surface contact with the photosensitive drum 52Bk at the stomach contact (front side from the front end). The film 32 is disposed over at least the width of the printing area of the recording medium in the axial direction of the developing device 16Bk. The film 32 also functions as a prevention member so that foreign matter does not move to the charging roller 45 side.

  As the film 32, a resin made of an elastic body having wear resistance and weather resistance, for example, a urethane film is used. A thin plate 34 made of SUS or polyethylene is attached to the film 32 via the double-sided tape 33 so as not to be wrinkled when the film 32 is attached to the cover member 29 and to improve the adhesion. Further, a double-sided tape 33 with a release paper 35 is attached to the thin plate 34 to be attached to the cover member 29. Therefore, the release paper 35 can be peeled off and the film 32 can be attached to the cover member 29. The film 32, the double-sided tape 33, the thin plate 34 and the release paper 35 constitute a film member 36, and the film 32, the double-sided tape 33 and the thin plate 34 constitute a film laminate.

  As described above, since the foreign matter is blocked by the film 32, the foreign matter does not adhere to the charging roller 45 or collect at the contact portion between the charging roller 45 and the photosensitive drum 52Bk. Therefore, periodic spots and streaks are not formed on the image, and the image quality can be improved.

  The toner blocked by the film 32 passes through the developing roller 46 and is scraped off by the cleaning device 49 as the photosensitive drum 52Bk in FIGS. 1 and 3 rotates as the printer warms up. Therefore, toner does not accumulate on the film 32.

  In the present embodiment, the film 32 is brought into contact with the stomach so as to follow the rotation direction of the photosensitive drum 52Bk. Therefore, the photosensitive member 52Bk does not become a load when rotating the photosensitive drum 52Bk. It does not damage the drum 52Bk or affects the abrasion of the surface layer of the photosensitive drum 52Bk, and is resistant to changes in the usage environment of the printer. Further, the surface potential of the charged photosensitive drum 52Bk is not made nonuniform.

  Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol, and the effect of the same embodiment is used about the effect of the invention by having the same structure. .

  FIG. 5 is a cross-sectional view showing a developing device according to the second embodiment of the present invention, FIG. 6 is a detailed view of a film according to the second embodiment of the present invention, and FIG. 7 is a second embodiment of the present invention. FIG. 8 is a perspective view showing a film attachment state in the second embodiment of the present invention.

  In this case, as shown in FIG. 6, in the length direction of the film 32 as the blocking member, at an equal interval of 50 to 70 [mm], the substantially central portion in the width direction (the double-sided tape 33 on the film member 36, A plurality of holes 37 serving as locked portions having a rectangular shape are formed on the tip side of the film 32 from the portion where the thin plate 34 and the release paper 35 are disposed. On the other hand, on the inner peripheral surface of the cover member 29 as the second case, the surface to which the film 32 is adhered, that is, the position below the adhesion surface, is associated with each hole 37 as a plurality of locking portions. A hook 31 is formed.

  Accordingly, the release paper 35 can be peeled off and the film 32 can be adhered to the cover member 29 in a state in which the hook 37 is moved into the hole 37 and the hole 37 is locked to the hook 31.

  By the way, the sticking direction of the film 32 is a direction in which the film 32 is physically peeled off, and the film 32 may be peeled depending on the use environment of the printer. In this embodiment, the hole 37 is connected to the hook 31. Since the film 32 is stuck in a stopped state, even if the film 32 is peeled off, the film 32 is not caught by the hook 31 and falls on the photosensitive drum 52Bk as an image carrier. Therefore, the printer can be used safely.

  By the way, in each of the above-described embodiments, when the toner cartridge 26 is replaced, the foreign matter that has entered the outer casing 27 through the opening 30 and accumulated on the photosensitive drum 52Bk rotates the photosensitive drum 52Bk. The movement to the charging roller 45 side due to the vibration is prevented.

  On the other hand, each developing device 16Bk, 16Y, 16M, 16C as an image forming unit can be moved up and down and moved up and down as a separation mechanism so that it can be brought into contact with and separated from the conveyance belt 17 as a conveyance member. In a printer having a down mechanism, the photosensitive drums 52Bk, 52Y, 52M, and 52C may rotate in the opposite direction as the developing devices 16Bk, 16Y, 16M, and 16C are moved upward. The foreign matter accumulated on the photosensitive drums 52Bk, 52Y, 52M, and 52C moves to the charging roller 45 side.

  Therefore, a third embodiment of the present invention in which a film 32 is provided in a printer having an up / down mechanism will be described.

  FIG. 9 is a diagram illustrating a state where each photosensitive drum is placed at an image forming position according to the third embodiment of the present invention, and FIG. 10 is a perspective view of an up / down mechanism according to the third embodiment of the present invention. 11 is a diagram illustrating a state in which each photosensitive drum in the third embodiment of the present invention is placed at a non-image forming position.

  As shown in the drawing, the frame 55 of the apparatus main body (only one frame 55 is shown in FIGS. 9 and 11) so that the developing devices 16Bk, 16Y, 16M, and 16C as image forming units are sandwiched between the left and right sides of the printer. The developing devices 16Bk, 16Y, 16M, and 16C are moved along guide grooves 57 and 58 that are formed in parallel to each other on the frame 55. The shafts 40 of the photosensitive drums 52Bk, 52Y, 52M, and 52C are fitted into the guide grooves 57, and the guide grooves 58 are formed so as to protrude from the side frames of the developing devices 16Bk, 16Y, 16M, and 16C. The made shaft 41 is fitted.

  Reference numeral 60 denotes an up / down mechanism. The up / down mechanism 60 includes a pair of slide links 42 and a driving force transmission unit 61 that advances and retracts the slide links 42 in the directions of arrows B and C perpendicular to the up / down direction. A drive motor 68 as an up / down drive unit is provided. The slide link 42 supports each shaft 40 by a guide surface 62. For this purpose, the guide surface 62 includes first and second guide surfaces 62a and 62b, and the developing devices 16Bk, 16Y, 16M, and 16C are conveyed by placing the shafts 40 on the first guide surface 62a. Each developing device 16Bk, 16Y, 16M, and 16C is placed on the transport belt by placing the shaft 40 on the second guide surface 62b, and placing the shaft 40 on the second guide surface 62b. 17 is placed at a non-image forming position which is a second position to be retracted by a predetermined distance from 17.

  The driving force transmission unit 61 urges the rotary shaft 63 extending in a direction orthogonal to the slide link 42, eccentric cams 64 fixed to both ends of the rotary shaft 63, and the slide link 42 in the arrow B direction. The one-way clutch 66 that meshes with the rotary shaft 63 when the biasing member 65 to be brought into contact with the eccentric cam 64 and the developing devices 16Bk, 16Y, 16M, and 16C are placed from the image forming position to the non-image forming position. 66, a gear 67 attached to the rotary shaft 63, and a gear 70 to 72 which are disposed between the drive gear 69 of the drive motor 68 and the gear 67 and constitute a gear train.

  In each of the developing devices 16Bk, 16Y, 16M, and 16C, a drum motor as an image forming drive unit is disposed to rotate the photosensitive drums 52Bk, 52Y, 52M, and 52C as image carriers. In this embodiment, the drum motor of the developing device 16C is also used as the drive motor 68.

  When the drive motor 68 is driven in the direction of arrow D, which is the first direction, during printing, the gear 67 is rotated in the direction of arrow E, and the meshing between the one-way clutch 66 and the rotating shaft 63 is released accordingly. As a result, the slide link 42 moves in the direction of arrow B due to the urging force of the urging member 65 and the weight of the developing devices 16Bk, 16Y, 16M, and 16C, and the developing devices 16Bk, 16Y, 16M, and 16C are moved to the image forming positions. And is brought into pressure contact with the conveyor belt 17.

  Subsequently, when each drive motor 68 is driven in the direction of arrow D, the photosensitive drums 52Bk, 52Y, 52M, and 52C are rotated around the shaft 40 in the direction of forming an image via a gear train (not shown). The charging roller 45 (FIG. 1) as a charging member, the developing roller 46 as a developer carrying member, the transfer rollers 51Bk, 51Y, 51M, 51C as transfer devices, and the like rotate to perform an image forming operation.

  When the drive motor 68 is driven in the direction of arrow G, which is the second direction, during non-printing, the up / down mechanism is actuated to rotate the gear 67 in the direction of arrow H, and the one-way clutch 66 rotates accordingly. The shaft 63 meshes with the shaft 63 and rotates the rotating shaft 63 in the arrow H direction. As the rotary shaft 63 rotates, the eccentric cam 64 is rotated, and the slide link 42 is moved in the arrow C direction against the biasing force of the biasing member 65.

  When the slide link 42 moves, each shaft 40 moves along the guide surface 62 and the guide groove 57 in the arrow F direction, and the shaft 41 moves along the guide groove 58 in the arrow F direction.

  When the developing devices 16Bk, 16Y, 16M, and 16C are retracted from the conveying belt 17 by a predetermined distance, the driving motor 68 is stopped and an appropriate holding current is supplied to cause the developing devices 16Bk, 16Y. , 16M, and 16C are held at the non-image forming positions.

  By the way, as described above, when the driving motor 68 of the developing device 16C is driven in the direction of the arrow D in order to place the developing devices 16Bk, 16Y, 16M, and 16C at the non-image forming positions, the photosensitive drum 52C is The image is rotated in a direction opposite to the direction in which the image is formed. Further, the other photosensitive drums Bk, 52Y, and 52M are also rotated in the reverse direction as the shaft 40 moves along the second guide surfaces 62b.

  In that case, the foreign matter accumulated on the photosensitive drums 52Bk, 52Y, 52M, and 52C moves to the charging roller 45 side. Therefore, in the present embodiment, as in the first and second embodiments, the charging roller 45 in the rotation direction of the photosensitive drums 52Bk, 52Y, 52M, and 52C (the rotation direction when forming an image). A film 32 as a dam member is disposed at a predetermined location on the downstream side and upstream of the opening 30.

  Accordingly, foreign matters accumulated on the photosensitive drums 52Bk, 52Y, 52M, and 52C as the photosensitive drums 52Bk, 52Y, 52M, and 52C rotate in the reverse direction adhere to the charging roller 45, and It does not accumulate at the contact portion with the photosensitive drums 52Bk, 52Y, 52M, and 52C. As a result, periodic spots and streaks are not formed on the image, and the image quality can be improved.

  In each of the above-described embodiments, the LED heads 21Bk, 21Y, 21M, and 21C are used as the exposure apparatus, but a laser-type exposure apparatus can be used. Also in this case, the cover member 29 has an opening 30 through which laser light passes.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

FIG. 2 is a cross-sectional view illustrating a main part of the developing device according to the first embodiment of the present invention. 1 is a schematic diagram of a printer according to a first embodiment of the present invention. It is sectional drawing which shows the developing device in the 1st Embodiment of this invention. It is a figure which shows the film member in the 1st Embodiment of this invention. It is sectional drawing which shows the developing device in the 2nd Embodiment of this invention. It is detail drawing of the film in the 2nd Embodiment of this invention. It is a perspective view which shows the principal part of the outer casing in the 2nd Embodiment of this invention. It is a perspective view which shows the attachment state of the film in the 2nd Embodiment of this invention. FIG. 10 is a diagram illustrating a state in which each photosensitive drum in the third exemplary embodiment of the present invention is placed at an image forming position. It is a perspective view of the up-down mechanism in the 3rd Embodiment of this invention. FIG. 10 is a diagram illustrating a state where each photosensitive drum in the third exemplary embodiment of the present invention is placed at a non-image forming position.

Explanation of symbols

21Bk, 21Y, 21M, 21C LED head 29 Cover member 30 Opening 32 Film 45 Charging roller 46 Developing roller 47 Toner supply roller 48 Developing blade 52Bk, 52Y, 52M, 52C Photosensitive drum 68 Drive motor

Claims (6)

(A) an image carrier;
(B) a charging member for charging the image carrier;
(C) an exposure device that exposes the surface of the charged image carrier to form an electrostatic latent image;
(D) a developer that forms a developer image by attaching a developer to the electrostatic latent image;
(E) an outer casing that houses the image carrier, a charging member, and a developing device, and that has an opening for exposure by the exposure apparatus;
(F) a drive unit that rotates the image carrier in a predetermined direction when forming an image;
(G) The image carrier is disposed on the downstream side of the charging member in the rotation direction of the image carrier and on the upstream side of the opening in contact with the image carrier, and falls on the image carrier through the opening. An image forming apparatus comprising: a blocking member that prevents the foreign matter from moving downward and accumulating in a contact portion between the image carrier and the charging member .   The image forming apparatus according to claim 1, wherein the blocking member is made of a film.   The image forming apparatus according to claim 1, wherein the damming member is locked and attached to the outer casing by a hook. (A) having a separation mechanism for moving the image carrier to an image forming position and a non-image forming position;
(B) The image forming apparatus according to claim 1, wherein the driving unit rotates the image carrier and operates the separation mechanism. (A) The drive unit is a drive motor;
(B) When the driving motor is driven in the first direction, the image carrier is rotated in a direction for forming an image, and when the driving motor is driven in the second direction, the separation mechanism The image forming apparatus according to claim 4, wherein the image forming apparatus is operated. (A) an image carrier;
(B) a charging member for charging the image carrier;
(C) an exposure device that exposes the surface of the charged image carrier to form an electrostatic latent image;
(D) a developer that forms a developer image by attaching a developer to the electrostatic latent image;
(E) an outer casing that houses the image carrier, a charging member, and a developing device, and that has an opening for exposure by the exposure apparatus;
(F) A foreign matter that is disposed between the opening and the charging member and that has fallen onto the image carrier through the opening is prevented from moving downward and entering the contact portion between the image carrier and the charging member. An image forming apparatus comprising: a foreign matter intrusion preventing member.

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