JP4803226B2 - Image forming apparatus and drum unit - Google Patents

Description

  The present invention relates to an image forming apparatus such as a laser printer and a drum unit used in the image forming apparatus.

  In general, in an image forming apparatus such as a laser printer, an electrostatic latent image is first formed on the surface of a photosensitive drum, and a developer image is formed on the surface of the photosensitive drum by supplying a developer from a developing roller. Is done. Then, the sheet passes between the photosensitive drum and the transfer roller to which the transfer current is applied, whereby the developer image on the photosensitive drum is transferred and an image is formed on the sheet.

  By the way, when a developer image is transferred to a sheet smaller than the width (axial length) of the peripheral surface of the transfer roller, such as a postcard, the transfer current flows into a portion of the peripheral surface of the transfer roller that does not contact the sheet. This is known to cause transfer defects. When a transfer failure occurs, the developer that should have been transferred to the paper remains on the surface of the photoconductive drum, so that it is transferred to the subsequent paper or adhered to the surface of the transfer roller, and the back surface of the subsequent paper is removed. There was a problem of getting dirty.

  In order to solve such a problem, for example, Patent Document 1 discloses an image forming apparatus that includes a plurality of transfer rollers having different circumferential widths and switches the transfer rollers according to the width of the paper. According to this, by selecting a transfer roller having an appropriate width according to the width of the paper, it is possible to suppress transfer current from flowing into a portion of the peripheral surface of the transfer roller that does not contact the paper, thereby suppressing transfer failure. be able to.

JP 2006-337454 A (FIGS. 1 and 2)

  However, in the conventional image forming apparatus described above, since the transfer roller is switched according to the width of the sheet, there is a problem that the configuration becomes complicated and the cost increases. In addition, since a configuration for switching a plurality of transfer rollers and transfer rollers is provided, there is also a problem that the apparatus is increased in size.

  Accordingly, an object of the present invention is to reduce the influence of transfer failure when a developer image is transferred to a recording sheet smaller than the width of the peripheral surface of a transfer roller by a method different from the conventional technique.

  In order to achieve the above-described object, an image forming apparatus according to the present invention is an apparatus main body, a photosensitive drum supported by the apparatus main body, a contact with the photosensitive drum, and a developer supplied to the photosensitive drum. And a developing roller that collects the developer remaining on the photosensitive drum, a developing frame that supports the developing roller, a manual feed port that is provided in the apparatus body and supplies a recording sheet from the outside, A pair of sheet width guides configured to be slidable in the width direction of the recording sheet supplied from the manual feed port and restricting the width of the recording sheet, and the pair of sheet width guides are moved in the direction of narrowing the width. And a pressing member that presses the developing frame and presses the developing roller toward the photosensitive drum.

  The image forming apparatus configured in this manner presses the developing frame when the pair of sheet width guides are moved in the direction of narrowing the width, that is, when a recording sheet having a small width is supplied from the manual feed port. And a pressing member that presses the developing roller toward the photosensitive drum. As a result, even if the developer remains on the surface of the photosensitive drum, the developer remaining on the surface of the photosensitive drum is recovered more by pressing the developing roller toward the photosensitive drum more strongly than usual. Scraping).

  The drum unit of the present invention is detachably mounted with a developing frame that contacts the photosensitive drum, supplies the developer to the photosensitive drum, and supports a developing roller that collects the developer remaining on the photosensitive drum. A drum unit that is configured to be movable in a direction in which the photosensitive drum, the photosensitive drum and the mounted developing frame that supports the photosensitive drum are moved toward and away from the developing frame, and the developing frame. An urging member that urges the developing roller toward the photosensitive drum by being urged toward the direction close to the photosensitive drum, and a drum frame that is in contact with and away from the urging member. A pressing member supported so as to be slidable in the axial direction of the developing roller, and the pressing member has an inclined surface capable of contacting the urging member at a tip portion. In addition, an engaged portion that moves the pressing member at least in a direction to contact the urging member by engaging an engaging member that slides in the axial direction of the developing roller provided outside. And the inclined surface is in contact with the urging member so that the pressing member presses the developing frame.

  The drum unit configured in this manner slides toward the urging member when an engagement member provided outside is engaged with the engaged portion, and the inclined surface of the tip portion becomes the urging member. A pressing member that presses the developing frame by contacting is provided. The pressing member presses the developing frame to press the developing roller supported by the developing frame toward the photosensitive drum. As a result, even if the developer remains on the surface of the photosensitive drum, the developing roller can be pressed more strongly toward the photosensitive drum than usual, so that more developer remaining on the surface of the photosensitive drum can be recovered. It becomes possible to do.

  According to the present invention, since the developer remaining on the surface of the photosensitive drum can be collected more by pressing the developing roller toward the photosensitive drum more strongly than usual, the width of the peripheral surface of the transfer roller can be increased. The effect of transfer failure when transferring a developer image to a smaller recording sheet can be reduced.

[First Embodiment]
<Overall configuration of laser printer>
Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a cross-sectional view showing an overall configuration of a laser printer as an example of an image forming apparatus, and FIG. 2 is a cross-sectional view showing a state where a process cartridge is removed from a main body casing by opening a front cover. .

  In the following description, the direction will be described with reference to the user who uses the laser printer. That is, in FIG. 1, the right side toward the paper surface is the “front” side, the left side toward the paper surface is the “back” side, the front side toward the paper surface is the “left” side, and the back side toward the paper surface is “right”. ”Side. In addition, the vertical direction toward the page is the “vertical” direction.

  As shown in FIG. 1, the laser printer 1 forms an image on a feeder unit 4 that supplies a sheet 3 as an example of a recording sheet or a supplied sheet 3 in a body casing 2 that is an example of an apparatus body. An image forming unit 5 is provided.

  The feeder unit 4 is provided at a lower portion in the main body casing 2 and includes a paper feed tray 6, a paper pressing plate 7, a paper transport mechanism 9, and the like having a known configuration. In the feeder unit 4, the sheet 3 in the sheet feeding tray 6 is moved upward (the sheet conveying mechanism 9) by the sheet pressing plate 7 and conveyed to the image forming unit 5 by the sheet conveying mechanism 9.

  The image forming unit 5 mainly includes a scanner unit 16, a process cartridge 17, and a fixing unit 18.

  The scanner unit 16 is provided in the upper part in the main body casing 2 and includes a laser light emitting unit, a polygon mirror, a lens, a reflecting mirror, and the like having a known configuration (not shown). In the scanner unit 16, a laser beam (see a chain line) based on the image data is emitted and scanned at high speed on the surface of the photosensitive drum 27.

  The process cartridge 17 is disposed between the feeder unit 4 and the scanner unit 16 and opens a front cover 2A as an example of an openable / closable cover member provided on the front side of the main casing 2 as shown in FIG. Thus, it can be attached to and detached from the main casing 2. The process cartridge 17 is mainly composed of a developing cartridge 28 and a drum unit 25.

  Returning to FIG. 1, the developing cartridge 28 includes a developing roller 31 having a known configuration, a layer thickness regulating blade 32, a supply roller 33, a toner hopper 34, and the like. The detailed configuration of the developing cartridge 28 will be described later.

  In the developing cartridge 28, toner as an example of the developer in the toner hopper 34 is stirred by the agitator 34 </ b> A and then supplied to the developing roller 31 by the supply roller 33. The toner supplied to the developing roller 31 enters between the layer thickness regulating blade 32 and the developing roller 31 as the developing roller 31 rotates, and is carried on the developing roller 31 as a thin layer having a constant thickness. .

  The drum unit 25 includes a photosensitive drum 27, a charger 29, a transfer roller 30, and the like having a known configuration. The detailed configuration of the drum unit 25 will be described later. In the drum unit 25, the surface of the photosensitive drum 27 is uniformly charged by the charger 29 and then exposed by high-speed scanning of the laser light from the scanner unit 16. Thereby, the potential of the exposed part is lowered, and an electrostatic latent image based on the image data is formed.

  Next, the toner carried on the developing roller 31 is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 27 when the developing roller 31 and the photosensitive drum 27 are in contact with each other. As a result, the electrostatic latent image is visualized and a toner image is formed on the surface of the photosensitive drum 27. Thereafter, the sheet 3 is conveyed between the photosensitive drum 27 and the transfer roller 30, whereby the toner image formed on the surface of the photosensitive drum 27 is transferred onto the sheet 3.

  The fixing unit 18 is provided on the back side of the process cartridge 17 and mainly includes a heating roller 41 and a pressure roller 42 having a known configuration. In the fixing unit 18, the toner image transferred onto the paper 3 is thermally fixed while the paper 3 passes between the heating roller 41 and the pressure roller 42. The sheet 3 on which the toner image has been thermally fixed is conveyed onto a sheet discharge tray 46 by a sheet discharge roller 45.

  Next, a detailed configuration of the process cartridge 17 (the developing cartridge 28 and the drum unit 25) and the main casing 2 which are characteristic portions of the present invention will be described.

<Detailed configuration of process cartridge>
FIG. 3 is a perspective view of the process cartridge, and FIG. 4 is a diagram showing the configuration of the urging member. FIG. 3A shows a state where the developing cartridge is removed, and FIG. 3B shows a state where the developing cartridge is mounted. ).

  As shown in FIG. 3, the developing cartridge 28 includes a developing frame 28 </ b> A that rotatably supports the developing roller 31, the supply roller 33, and the like and forms a toner hopper 34.

  The developing frame 28A has a recess 35 formed on a front side surface (a surface facing the front cover 2A; see FIG. 1). The recess 35 includes a central flat surface 35A in the center in the left-right direction (the axial direction of the developing roller 31) and a pair of inclined surfaces 35B extending from the left and right ends of the central flat surface 35A. The inclined surface 35B is inclined so as to approach the near side (front cover 2A) from the inner side in the left-right direction (the left and right ends of the central plane 35A) toward the outer side.

  The drum unit 25 includes a drum frame 25A that rotatably supports the photosensitive drum 27, the transfer roller 30, and the like. The process cartridge 17 is configured by detachably attaching the developing cartridge 28 (developing frame 28A) to the drum frame 25A. The photosensitive drum 27 is supported on the main body casing 2 via the drum frame 25A when the drum unit 25 (process cartridge 17) is mounted on the main body casing 2.

  Further, the drum unit 25 includes a pair of urging members 26 disposed on the inner surface side of the front wall surface of the drum frame 25A and on both left and right sides so as to face the developing cartridge 28 mounted on the drum frame 25A. As shown in FIG. 4A, the biasing member 26 biases the swing arm 26A supported so as to swing back and forth with respect to the drum frame 25A and the swing arm 26A toward the back side. The coil spring 26B is mainly configured.

  As shown in FIG. 4B, when the developing cartridge 28 is mounted on the drum frame 25A, the developing cartridge 28 causes the swing arm 26A to swing to the near side, thereby compressing the coil spring 26B. Then, the coil spring 26B biases the developing cartridge 28 toward the back side via the swing arm 26A. As a result, the developing roller 31 supported by the developing frame 28A can be urged toward the photosensitive drum 27 disposed on the back side.

  In this way, the urging member 26 urges the developing roller 31 toward the photosensitive drum 27, so that the developing roller 31 and the photosensitive drum 27 can surely come into contact with each other. As a result, the developing roller 31 can supply the toner to the photosensitive drum 27 satisfactorily, and scrapes and collects the toner remaining on the photosensitive drum 27 by slidingly contacting the surface of the photosensitive drum 27. be able to.

  The toner collected by the developing roller 31 is scraped off by the supply roller 33 and then supplied to the developing roller 31 from the supply roller 33 and carried together with the toner in the toner hopper 34, and further the surface of the photosensitive drum 27. Is supplied to the electrostatic latent image.

<Detailed configuration of main casing>
FIG. 5 is a perspective view showing the configuration of the front side of the main casing, and FIG. 6 is a perspective view showing the configuration of the sheet width guide. FIG. It is the figure (b) which shows the state which narrowed the sheet | seat width guide, and the enlarged view (c) which shows a press part.

As shown in FIG. 5, the main body casing 2 includes a front cover 2 </ b> A that can be opened and closed that forms a part of the wall portion, a manual feed port 2 </ b> B provided in the front cover 2 </ b> A, and a manual feed port 2 </ b> B. A pair of sheet width guides 60 </ b> L and 60 </ b> R for regulating the width of the supplied paper (not shown) is provided.
The manual feed port 2B is an opening for supplying paper from the outside, and is formed in a rectangular shape that is long on the left and right.

  The pair of sheet width guides 60L and 60R is a sheet width guide having a known configuration, and is configured to be slidable in the width direction (left-right direction) of the sheet fed from the manual feed port 2B. Specifically, in the pair of sheet width guides 60L and 60R, as shown in FIGS. 6A and 6B, the sheet support portions 61L and 61R are movable along the manual feed port 2B. Therefore, it can slide in the left and right direction.

  More specifically, the sheet width guides 60L and 60R have extending portions 62L and 62R that extend beyond the center in the axial direction (gear 2C) of the developing roller 31 to the opposite side in the left-right direction on the back side of the front cover 2A. ing. The surfaces of the extending portions 62L and 62R facing the gear 2C (the upper surface of the extending portion 62L and the lower surface of the extending portion 62R) are rack gears formed with gear teeth, and rotate on the back surface of the front cover 2A. It meshes with the gear 2C supported so as to be possible (see FIG. 6C). Accordingly, by sliding one of the sheet width guides 60L and 60R, the other also slides in the opposite direction in conjunction with the other.

  A base 63L that extends upward is formed at the tip of the extension 62L, and a base 63R that extends downward is formed at the tip of the extension 62R. As shown in FIG. 6 (c), as an example of a pressing member that protrudes toward the back side at the same position in the vertical direction on the back side surface of each base 63L, 63R, and that has a substantially hemispherical tip. Pressing portions 70L and 70R are provided. The front ends of the pressing portions 70L and 70R are at the same position in the front-rear direction.

<Effects of laser printer>
The operational effects of the laser printer 1 configured as described above will be described. FIGS. 7A and 7B are cross-sectional views for explaining the operation of the laser printer. FIG. 7A is a diagram illustrating a state where a pair of sheet width guides are widened, and FIG. 7B is a diagram illustrating a state where a pair of sheet width guides is narrowed. is there.

  In the laser printer 1, an image is formed by supplying a wide paper (for example, A4 size or letter size paper, paper having the same width as the paper stored in the paper feed tray 6) from the manual feed port 2 </ b> B. In this case, the pair of sheet width guides 60L and 60R (sheet support portions 61L and 61R) are arranged in the vicinity of the left and right ends of the manual feed port 2B as shown in FIG. At this time, the front ends of the pressing portions 70L and 70R are located in the vicinity of the center in the axial direction of the developing roller 31, enter the concave portion 35 of the developing frame 28A, and face each other without contacting the central plane 35A of the concave portion 35. .

  When image formation is performed by supplying paper (for example, a postcard) having a small width from the manual feed port 2B, as shown in FIG. 7B, a pair of sheet width guides 60L and 60R (sheet support portions 61L and 61R). ) In the direction of narrowing the width (inward in the left-right direction). If it does so, each press part 70L and 70R will slide and move toward the left-right direction outer side. In the middle of this, each press part 70L and 70R contact | abuts to the inclined surface 35B. Since the inclined surface 35B is inclined so as to approach the near side from the inner side to the outer side in the left-right direction, the pressing portions 70L, 70R come into contact with each other and slide toward the outer side in the left-right direction. It is pressed toward the back side by 70R.

  When the inclined surface 35B is pressed to the back side, the developing frame 28A on which the inclined surface 35B is formed is pressed to the back side, and the developing roller 31 supported by the developing frame 28A is arranged on the back side. It is pressed toward the body drum 27. The developing roller 31 is constantly urged toward the photosensitive drum 27 by the urging member 26, but is directed toward the photosensitive drum 27 by the sliding movement of the pressing portions 70L and 70R (a pair of sheet width guides 60L and 60R). Will be pressed more strongly than usual.

  As described above, according to the present embodiment, the contact pressure between the developing roller 31 and the photosensitive drum 27 can be increased, so that more toner remaining on the surface of the photosensitive drum 27 is scraped off by the developing roller 31. Can be recovered. As a result, when an image is formed on a sheet smaller than the width of the peripheral surface of the transfer roller 30, a transfer failure occurs, and even if more toner than usual remains on the photosensitive drum 27, this is sufficiently recovered. can do. Therefore, according to the present embodiment, it is possible to reduce the influence of transfer failure when a toner image is transferred onto a sheet smaller than the width of the peripheral surface of the transfer roller 30.

[Second Embodiment]
Next, a second embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 8 is a diagram showing a configuration of a drum unit and a sheet width guide, a partial perspective view (a) and a partial cross-sectional view (b) showing a pressing member in a state where a pair of sheet width guides are expanded, It is the fragmentary perspective view (c) and partial sectional view (d) which show the press member in the state where a pair of sheet width guides were narrowed. In the present embodiment, portions different from the first embodiment will be described in detail, and the same components as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  As shown in FIGS. 8A and 8B, the drum unit 125 includes a photosensitive drum 27, a charger 29, a transfer roller 30, and an urging member 26 in a drum frame 125A, and further urges left and right. Two pressing members 170 are provided corresponding to the members 26 (partially omitted).

  The pressing member 170 mainly includes a pressing pin 171, an engagement plate 172 as an example of an engaged portion, and a coil spring 173. In FIG. 8, only the left pressing member 170 is shown, but the right pressing member 170 is also provided on the right side so as to be symmetrical with the left pressing member 170.

The pressing pin 171 is formed in a rod shape and is supported by the drum frame 125A so as to be slidable in the left-right direction (the axial direction of the developing roller 31). The pressing pin 171 has a pointed inclined surface 171 </ b> A at a tip end portion (an end portion on the outer side in the left-right direction).
The engagement plate 172 is formed in a plate shape, and is fixed near the approximate center of the pressing pin 171 in a state where the front end protrudes to the near side from the near wall surface of the drum frame 125A.
The coil spring 173 is disposed between the drum frame 125 </ b> A and the engagement plate 172 while being passed through the pressing pin 171.

  Of the wall surfaces supporting the swing arm 26A of the urging member 26, the wall surface 125B on the inner side in the left-right direction is formed with a through-hole 125C into which the tip of the pressing pin 171 slid and moved outward in the left-right direction is inserted. ing.

  As shown in FIG. 8C, the pair of sheet width guides 60L and 60R (the sheet width guide 60R is not shown) of the present embodiment are disposed at the distal ends of the extending portions 62L and 62R with respect to the engagement plate 172. Plate-like engagement portions 64L and 64R (engagement members) that are substantially parallel are provided (the engagement portion 64R is not shown).

  According to the configuration as described above, when a sheet having a small width is supplied from the manual feed port 2B and image formation is performed, the pair of sheet width guides 60L and 60R are slid in the direction of narrowing the width. The engaging portions 64L and 64R slide and move outward in the left-right direction. In the middle of this, each engaging part 64L, 64R engages (contacts) with each engaging plate 172, and as shown in FIG. 8C, each engaging plate 172 is moved outward in the left-right direction (biasing member). 26) and slide it toward.

  Thereby, the tip of the pressing pin 171 also slides toward the urging member 26, is inserted into the through hole 125C, and comes into contact with the urging member 26 (swinging arm 26A). Since the tip end portion of the pressing pin 171 is provided with a pointed inclined surface 171A, as shown in FIG. 8D, the inclined surface 171A comes into contact with the swing arm 26A toward the back side. Will swing.

  When the swing arm 26A swings toward the back side, the development frame 28A is pressed toward the back side, so that the developing roller 31 supported by the development frame 28A is pressed toward the photosensitive drum 27. As a result, the developing roller 31 is pressed more strongly toward the photosensitive drum 27 than usual. Therefore, also in the present embodiment, it is possible to reduce the influence of transfer failure when a toner image is transferred to a sheet smaller than the width of the peripheral surface of the transfer roller 30.

  In the present embodiment, when the pair of sheet width guides 60L and 60R is in a narrowed state (see FIG. 6B), the coil spring 173 that is compressed (see FIG. 8C) causes the engagement. A force for moving the joint portions 64L and 64R inward in the left-right direction will act. This force acts in the direction of increasing the width of the pair of sheet width guides 60L and 60R.

  Therefore, in the present embodiment, a configuration is provided in which the movement of the pair of sheet width guides 60L and 60R is locked, and when the movement is at least widened, the pair of sheet width guides 60L and 60R is not released unless the lock is released. It is preferable not to be able to move. Since such a configuration is known, a description of a specific configuration is omitted.

  Incidentally, when the pair of sheet width guides 60L and 60R are slid and moved in the direction of increasing the width, the engaging portions 64L and 64R are slid inward in the left-right direction and separated from the engaging plates 172. . Then, the engagement plate 172 moves inward in the left-right direction due to the action of the coil spring 173, and the pressing pin 171 moves away from the urging member 26 and comes out of the through hole 125C. Thus, the contact between the pressing pin 171 and the swing arm 26A is released, so that the pressing of the developing frame 28A by the swing arm 26A is released, and the pressing of the developing roller 31 by the pressing member 170 is also released.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to above-described embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the above-described embodiment, the configuration in which the photosensitive drum 27 is supported by the main body casing 2 (the apparatus main body) via the drum frame 25A is shown. However, the present invention is not limited to this, and for example, the photosensitive drum is the apparatus. The structure supported directly by a main body may be sufficient.

  In the above-described embodiment, the configuration in which the development cartridge 28 (development frame 28A) is detachably attached to the main body casing 2 in a state where the development cartridge 28 (development frame 28A) is attached to the drum frame 25A is shown. The invention is not limited to this. For example, a configuration in which the development frame is detachably attached to the apparatus main body may be employed.

  In the above-described embodiment, the configuration in which the manual feed port 2B and the pair of sheet width guides 60L and 60R are provided on the openable front cover 2A is shown, but the present invention is not limited to this. For example, a configuration in which a manual feed port and a pair of sheet width guides are provided on a wall portion of the apparatus main body that does not open and close may be employed.

  In the second embodiment described above, the configuration in which the pressing member 170 is provided on the drum frame 25A is shown. However, the present invention is not limited to this, and may be provided on the front cover 2A, for example. It may be provided on the wall that does not open or close.

  In the first embodiment described above, the example in which the concave portion 35 formed in the developing frame 28A is configured by the central plane 35A and the pair of inclined surfaces 35B is shown, but the present invention is not limited to this, and for example, The structure provided only with the inclined surface may be sufficient. It should be noted that the present invention appropriately sets the range in which the inclined surface is formed in the axial direction of the developing roller, the inclination angle, and the like, thereby setting the paper size for pressing the developing roller toward the photosensitive drum, The contact pressure between the developing roller and the photosensitive drum can be adjusted.

  In the above-described embodiment, the biasing member 26 includes the swing arm 26A supported so as to swing back and forth with respect to the drum frame 25A, and the coil spring 26B that biases the swing arm 26A toward the back side. Although an example of the configuration is shown, the present invention is not limited to this. In other words, the member that contacts the developing frame may be configured to be movable in the direction of approaching / separating from the developing frame, and may be configured to slide. Further, the biasing member is not particularly limited as long as the biasing member is configured to be biased toward the direction close to the developing frame. For example, in addition to the coil spring described above, a torsion spring, a leaf spring, or the like is used. There may be.

  In the second embodiment described above, the configuration in which the tip of the pressing pin 171 (the pressing member 170) is a pointed inclined surface 171A is shown, but the present invention is not limited to this, and for example, the tip of the pressing member It is good also considering a part as an inclined surface of the shape which cut | disconnected the cylindrical rod-shaped member diagonally.

  In the second embodiment described above, the plate-like engagement portions 64L and 64R (engagement members) are exemplified, but the present invention is not limited to this, and for example, left and right with respect to the pressing member 170 (engagement plate 172). You may employ | adopt the engaging part (engaging member) of planar view substantially U shape engaged so that it may pinch | interpose from both sides.

  In the second embodiment described above, the plate-like engagement plate 172 is shown as an example of the engaged portion, but the present invention is not limited to this. For example, a bar-like protrusion that extends substantially perpendicular to the pressing pin 171 may be provided, and this protruding part may be used as the engaged part, or the rear end of the pressing pin 171 (the inner end in the axial direction of the developing roller 31). May be the engaged portion.

  In the above-described embodiment, the laser printer 1 is shown as an example of the image forming apparatus. However, the present invention is not limited to this, and may be, for example, a copying machine or a multifunction machine. In the above-described embodiment, the paper 3 such as a thick paper, a postcard, and a thin paper is shown as an example of the recording sheet. However, the present invention is not limited to this, and may be an OHP sheet, for example.

1 is a cross-sectional view illustrating an overall configuration of a laser printer as an example of an image forming apparatus. It is sectional drawing which shows the state which opened the front cover and removed the process cartridge from the main body casing. It is a perspective view of the process cartridge of 1st Embodiment. FIG. 2 is a diagram illustrating a configuration of an urging member, and is a diagram (a) in a state in which the developing cartridge is removed, and a diagram (b) in a state in which the developing cartridge is mounted. It is a perspective view which shows the structure of the near side of a main body casing. FIG. 2A is a perspective view illustrating a configuration of a sheet width guide, FIG. 1A illustrating a state where a pair of sheet width guides is widened, FIG. 2B illustrating a state where a pair of sheet width guides is narrowed, and the first embodiment. It is an enlarged view (c) which shows the press part which concerns on. 4A and 4B are cross-sectional views for explaining the operation of the laser printer, and are a diagram showing a state where a pair of sheet width guides are widened and a diagram showing a state where the pair of sheet width guides are narrowed. It is a figure which shows the structure of the drum unit which concerns on 2nd Embodiment, and a sheet width guide, The partial perspective view (a) and partial sectional view (b) which show the press member in the state which expanded a pair of sheet width guide, It is the fragmentary perspective view (c) and partial sectional view (d) which show the press member in the state where the sheet width guide was narrowed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Main body casing 2A Front cover 2B Manual feed port 3 Paper 25 Drum unit 25A Drum frame 26 Energizing member 26A Swing arm 26B Coil spring 27 Photosensitive drum 28 Developing cartridge 28A Developing frame 31 Developing roller 35B Inclined surface 60L Sheet width guide 60R Seat width guide 62L Extension part 62R Extension part 63L Base part 63R Base part 64L Engagement part 70L Press part 70R Press part 125 Drum unit 125A Drum frame 170 Press member 171 Press pin 171A Inclined surface 172 Engagement plate

Claims (5)

The device body;
A photosensitive drum supported by the apparatus body;
A developing roller that contacts the photosensitive drum, supplies developer to the photosensitive drum, and collects the developer remaining on the photosensitive drum;
A developing frame for supporting the developing roller;
A manual feed port provided in the apparatus body for supplying a recording sheet from the outside;
A pair of sheet width guides configured to be slidable in the width direction of the recording sheet supplied from the manual supply port, and restricting the width of the recording sheet;
And a pressing member that presses the developing frame when the pair of sheet width guides are moved in the direction of narrowing the width and presses the developing roller toward the photosensitive drum. Image forming apparatus. Each of the pair of sheet width guides is formed to extend to the opposite side beyond the center in the axial direction of the developing roller on the back side of the wall portion where the manual feed port is provided. A pressing member is provided;
The developing frame is provided with a pair of inclined surfaces that approach the wall portion from the inner side to the outer side in the axial direction of the developing roller on the surface facing the wall portion.
The image forming apparatus according to claim 1, wherein the pressing member presses the developing frame when the pressing member comes into contact with the inclined surface by the sliding movement of the pair of sheet width guides.   The image forming apparatus according to claim 2, wherein the wall portion provided with the manual feed port is a cover member that can be opened and closed. The urging force is configured to be movable toward and away from the developing frame and urges the developing roller toward the photosensitive drum by being urged toward the developing frame. Comprising a member,
The pressing member is supported so as to be slidable in the axial direction of the developing roller so as to be in contact with or separated from the urging member, and has an inclined surface that can be brought into contact with the urging member at a distal end portion thereof.
Each of the pair of sheet width guides is formed to extend to the opposite side beyond the center in the axial direction of the developing roller on the back side of the wall portion where the manual feed port is provided. An engagement portion is provided that engages with the pressing member and slides the pressing member,
The image forming apparatus according to claim 1, wherein the pressing member presses the developing frame when the inclined surface comes into contact with the urging member by the sliding movement of the pair of sheet width guides. A drum unit that contacts a photosensitive drum, supplies a developer to the photosensitive drum, and detachably mounts a developing frame that supports a developing roller that collects the developer remaining on the photosensitive drum,
A photosensitive drum;
A drum frame that supports the photosensitive drum and the mounted developing frame;
The urging force is configured to be movable toward and away from the developing frame and urges the developing roller toward the photosensitive drum by being urged toward the developing frame. Members,
A pressing member supported so as to be slidable in the axial direction of the developing roller so as to be in contact with and separated from the biasing member with respect to the drum frame;
The pressing member has an inclined surface that can come into contact with the biasing member at the tip, and an engaging member that slides in the axial direction of the developing roller provided outside engages the pressing member. Having an engaged portion for moving the member in a direction to contact at least the biasing member;
The drum unit, wherein the pressing member presses the developing frame when the inclined surface contacts the biasing member.

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