JP2008070745A - Image forming apparatus - Google Patents

Abstract

In an image forming apparatus, a position of a photosensitive drum is not easily displaced in a housing, and an image can be appropriately formed on a recording sheet.
A photosensitive drum 2 is formed at a terminal end portion of a guide groove 31 by fitting a portion in the vicinity of the end of a rotating shaft 2a into a guide groove 31 formed in a frame portion 30 inside the housing. The spring 35 is urged toward the positioning portion 31a by being in contact with the positioning portion 31a and positioned at a predetermined position, and is mounted inside the housing. In the vicinity of the positioning portion 31a of the guide groove 31, a tapered portion 31b is formed so that the width dimension of the guide groove 31 becomes smaller as the positioning portion 31a is approached. The rotating shaft 2a is mounted so as not to be displaced from a predetermined position inside the housing because the vicinity of the end of the rotating shaft 2a is close to the tapered portion 31b in a state where the photosensitive drum 2 is mounted. Shaking of the body drum 2 is suppressed.
[Selection] Figure 3

Description

  The present invention relates to an electrophotographic image forming apparatus that forms an image by transferring a toner image formed on a photosensitive drum onto a recording sheet.

  In an image forming apparatus that forms (prints) an image on recording paper by an electrophotographic method, the toner image formed on the photosensitive drum is recorded by conveying the recording paper sandwiched between the photosensitive drum and a transfer roller. Transfer on paper. As such an image forming apparatus, there is an image forming apparatus in which a deteriorated photosensitive drum can be replaced with another photosensitive drum due to an increase in the number of integrated prints.

  The replacement of the photosensitive drum will be described with reference to FIG. FIG. 4 shows an example of a frame portion inside a housing of a conventional image forming apparatus. The frame portion 80 is formed with a guide groove 81 into which the rotation shaft 82a of the photosensitive drum 82 can be fitted from the outside of the apparatus. The width dimension of the guide groove 81 is formed larger than the diameter of the rotation shaft 82a so that the rotation shaft 82a can be easily fitted. The photosensitive drum 82 is a device that opens a lid or the like provided on the surface of the casing, and slides the rotating shaft 82a along the guide groove 81 toward the inside of the casing with the inside of the casing exposed. It is configured to be attachable to the main body. An arrow S in FIG. 4 indicates a sliding direction when the photosensitive drum 82 is mounted. A positioning portion 81 a for positioning the rotation shaft 82 a is formed at the end portion of the guide groove 81. In addition, a spring 85 formed so as to overhang the guide groove 81 is provided above the guide groove 81. In the vicinity of the positioning portion 81a of the spring 85, the rotation shaft 82a is directed toward the side edge below the guide groove 81 and the positioning portion 81a in a state where the rotation shaft 82a is positioned in the vicinity of the positioning portion 81a. It is formed to be energized. That is, in the photosensitive drum 82, as shown in the drawing, the rotating shaft 82a that is slid along the guide groove 81 while deforming the spring 85 is in contact with the side edge portion or the positioning portion 81a below the guide groove 81. It is attached to the inside of the housing in a state of being in contact with and biased by the spring 85. The photosensitive drum 82 is removed by pulling the rotating shaft 82 a along the guide groove 81 while deforming the spring 85. In this image forming apparatus, by urging the rotation shaft 82a using only the integrally formed spring 85, it is simple and low-cost without using another member to urge the rotation shaft 82a. It is configured.

  By the way, the photosensitive drum 82 is mounted so that the rotating shaft 82a is urged only by the spring 85 to such an extent that the photosensitive drum 82 can be attached and detached, so that force is applied to the photosensitive drum 82 during the printing operation. In some cases, the rotating shaft 82a is displaced upward from the mounted position while slightly deforming the spring 85, and the photosensitive drum 82 may be rattled. When rattling occurs on the photosensitive drum 82, for example, the distribution of the clamping pressure between the photosensitive drum 82 and the transfer roller is different, so that the recording paper is skewed or the surface of the photosensitive drum 82 is exposed. The laser beam may not be properly irradiated, and printing defects may occur.

  Here, for example, Patent Document 1 shows a configuration in which an inclined surface is provided on an arm that biases the shaft of the photosensitive drum in the guide groove end direction in the image forming apparatus to prevent the photosensitive drum from rattling. ing. Patent Document 2 discloses an image forming apparatus configured to position a process cartridge by biasing a process cartridge positioning pin obliquely toward an end surface of a guide groove by an arm biased by a spring. ing. However, these configurations use an arm member to press the shaft or positioning pin of the photosensitive drum against the end surface of the guide groove, and when applied to an image forming apparatus having a simple configuration as described above, the manufacturing cost is low. It will be high.

  Further, in Patent Document 3, in the image forming apparatus, a protrusion provided on the process cartridge separately from the rotation shaft of the photosensitive drum comes into contact with an inclined portion formed on the frame portion, thereby rotating the rotation shaft. A configuration is shown in which is pressed toward the end of the guide groove. However, in such a configuration, it is necessary to provide a protrusion at a location different from the rotation axis. For example, when the photosensitive drum is configured to be detachable as a small cartridge, it is effective. In some cases, rattling of the photosensitive drum cannot be suppressed.

In Patent Document 4, the end portion of the guide groove is formed to be inclined downward, and the cartridge of the photosensitive drum is in a state where the rotation shaft of the photosensitive drum is fitted in the end portion of the guide groove. The attached image forming apparatus is shown. Patent Document 5 discloses an image forming apparatus in which a tapered surface is formed in a concave portion of a coupling member for rotating a drum and is stably fitted to a protrusion on the rotating shaft side of the photosensitive drum. ing. However, these Patent Documents 4 and 5 do not show an effective configuration for preventing rattling of the photosensitive drum caused by displacement of the rotation shaft of the photosensitive drum.
JP-A-10-171300 JP-A-8-6471 JP 2002-108173 A JP 2003-84647 A JP 2005-107413 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an image forming apparatus having a simple configuration in which the position of a photosensitive drum is not easily displaced inside a housing and an image can be appropriately formed on a recording sheet. The purpose is to do.

  In order to achieve the above-mentioned object, the invention of claim 1 includes a housing, a paper feed tray attached to the housing and on which recording paper is placed, and a recording paper placed on the paper feeding tray. A recording paper transport mechanism that transports the image inside the housing, an image forming unit that is arranged inside the housing and forms an image on the recording paper transported by the recording paper transport mechanism, and controls each part of the apparatus to control the image on the recording paper. The image forming unit is arranged to be rotatable about a rotation axis so that the main scanning direction substantially orthogonal to the recording paper conveyance direction is the longitudinal direction, and the image forming unit is photosensitive on the surface. A photosensitive drum on which a body layer is formed; a charging unit that charges the surface of the photosensitive drum substantially uniformly; and a scanning unit that forms a latent image by irradiating the surface of the photosensitive drum while scanning a laser beam. And a latent image is formed on the surface of the photosensitive drum. A developing device that forms a toner image by attaching toner to the exposed portion, and a surface of the photosensitive drum facing the surface of the photosensitive drum at a predetermined transfer position downstream of the developing device in the rotational direction of the photosensitive drum. A transfer roller provided to transfer the toner image formed on the surface of the photosensitive drum onto the recording paper; and applying a predetermined heat and pressure to the recording paper on which the toner image is transferred to fix the toner image on the recording paper. A guide roller having a width dimension larger than a diameter of an end portion of the rotating shaft and fitted in the vicinity of the end portion of the rotating shaft. A frame portion having a groove is provided, and each guide groove is in contact with the vicinity of the end of the rotation shaft fitted in the guide groove to regulate the position of the rotation shaft. A positioning part is provided, and each frame is Each of the portions is integrally formed with a spring that urges a rotating shaft arranged along each guide groove toward one side edge of the guide groove and the positioning portion. The photosensitive drum is urged by the spring so that the vicinity of each end portion of the rotation shaft is in contact with one side edge portion of the guide groove and the positioning portion, respectively. It is held in the guide groove in a state and is mounted at a predetermined position inside the housing, and from the mounted state, by sliding the rotating shaft along the guide groove while deforming the spring, In the image forming apparatus configured to be detachable from the apparatus main body, among the other side edge portions of the respective guide grooves, a portion near the positioning portion has a guide as it approaches the positioning portion. A tapered portion formed so as to be close to the rotation shaft when the photosensitive drum is at the predetermined position is provided so that the width of the groove is narrow, and the photosensitive drum is at the predetermined position. In the mounted state, the vicinity of each end portion of the rotating shaft abuts on the tapered portion, so that the displacement of the rotating shaft from the predetermined position is restricted, so that the recording paper can be properly used. An image can be formed.

  According to a second aspect of the present invention, a photosensitive member is provided on the surface of the apparatus so as to be rotatable about a rotation axis so that a main scanning direction substantially orthogonal to the recording paper conveyance direction is a longitudinal direction. A photosensitive drum having a layer formed thereon, exposing the photosensitive layer to form a latent image on the surface of the photosensitive drum, and developing the latent image by attaching toner to the surface of the photosensitive drum. And an image forming apparatus for forming an image on the recording paper by transferring and fixing the toner on the surface of the photosensitive drum to the surface of the recording paper, the side of the housing having the rotating shaft A frame portion is provided with a guide groove in which a portion near the end portion of the rotating shaft is fitted, and the guide groove is in contact with the vicinity of the end portion of the rotating shaft fitted in the guide groove and rotates the rotation portion. It is formed at the positioning part that regulates the position of the moving shaft and in the vicinity of the positioning part. A biasing member that biases a portion near the end of the rotating shaft toward the positioning portion, the taper portion being formed so that the width of the guide groove becomes narrower as approaching the positioning portion. In addition, the rotating shaft is in contact with the tapered portion in a state where the photosensitive drum is urged by the urging member and is in contact with the positioning portion and is mounted at a predetermined position. The displacement from the predetermined position is restricted.

  According to a third aspect of the present invention, in the second aspect of the present invention, the urging member is an integrally formed spring.

  According to the first aspect of the present invention, the guide groove of the guide groove is moved closer to the positioning portion near the positioning portion of the side edge portion where the rotating shaft does not contact with the rotating shaft mounted. A taper portion is provided so that the width is narrow, and in a state where the photosensitive drum is mounted at a predetermined position, the vicinity of each end portion of the rotation shaft abuts the taper portion, so that the rotation shaft Displacement from the predetermined position is restricted. Accordingly, rattling of the photosensitive drum is less likely to occur during printing, and an image can be appropriately formed on the recording paper. And since the taper part is formed in each guide groove which the both ends vicinity of a rotating shaft fits, it becomes hard to generate | occur | produce rattling of a photosensitive drum. In addition, the springs for energizing the vicinity of both ends of the rotating shaft are integrally formed, and the rattling of the photosensitive drum can be suppressed with a simple configuration and a low manufacturing cost with a small number of parts. This makes it possible to form an image properly.

  According to the second aspect of the present invention, the taper portion formed so that the width of the guide groove becomes narrower toward the positioning portion is provided in the vicinity of the positioning portion in the guide groove, and the photosensitive drum is In a state where the rotating shaft is mounted at a predetermined position, the vicinity of each end of the rotating shaft comes into contact with the tapered portion, thereby restricting the displacement of the rotating shaft from the predetermined position. Accordingly, rattling of the photosensitive drum is less likely to occur during printing, and an image can be appropriately formed on the recording paper.

  According to the invention of claim 3, since the photosensitive drum is mounted by urging the vicinity of the end of the rotating shaft by the integrally formed spring, the number of parts is small and the manufacturing cost is low. As a result, the rattling of the photosensitive drum can be suppressed, and an image can be formed properly.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of an image forming apparatus according to this embodiment. The image forming apparatus 1 is a so-called laser beam printer, which is connected to, for example, an external personal computer, and forms an image on the recording paper P by electrophotography based on image data sent from the personal computer. (Print). The image forming apparatus 1 includes a paper feed cassette (paper feed tray) 110 that is disposed at the bottom of the housing 100 and on which the recording paper P is placed substantially horizontally, and is ejected from the housing 100 provided at the top of the housing 100. The recording paper P loaded thereon, the recording paper transport mechanism 20 that transports the recording paper P loaded in the paper feed cassette 110 into the housing 100, and the recording paper transport mechanism 20. An image forming unit 10 that forms an image on the recording paper P and an electronic circuit having, for example, a CPU, ROM, RAM, and the like, and controls the operation of each unit of the apparatus and prints the image on the recording paper P 40. An opening / closing lid 100a is pivotally supported on the rear surface of the casing 100 so as to be openable / closable with respect to the casing 100. By opening the opening / closing lid 100a, the image forming unit 10 is exposed to the outside, and maintenance work or the like is performed. It is configured to be able to do. The paper feed cassette 110 is provided so as to be drawable with respect to the housing 100. The image forming apparatus 1 is configured such that the recording paper P can be loaded and placed by pulling out the paper feed cassette 110 from the housing 100. Instead of the paper feed cassette 110, a paper feed tray fixed to the housing 100 may be provided so that the recording paper P can be loaded from the outside.

  The recording paper transport mechanism 20 includes a pickup roller 21 disposed above the paper feed cassette 110, a transport roller 22 that transports the recording paper P inside the housing 100, and the recording paper P on the top of the housing 100. The paper discharge roller 23 is disposed at the downstream end of the conveyance path, and includes a motor (not shown) for driving these rollers. A recording paper guide 15 for changing the transport direction along the recording paper P is disposed on the upper and lower portions of the housing 100 on the back side. The pickup roller 21 abuts on the uppermost recording paper P placed on the paper feed cassette 110 and rotates to bring the recording paper P into the housing 100 along the recording paper guide 15. Feed the paper. The fed recording paper P is transported to the image forming unit 10 by the transport roller 22, and after an image is formed by the image forming unit 10, the recording paper P is discharged onto the paper discharge unit 120 by the paper discharge roller 23. .

  The image forming unit 10 includes a photosensitive drum 2 having a photosensitive layer formed on the surface, a cleaner 3, a charger (charging means) 4, a scan unit 5, a developing brush (developing device) 6, a transfer roller 7, and a transfer roller 7. On the other hand, the fixing roller 8 is disposed on the downstream side in the conveyance direction of the recording paper P. These photosensitive drums 2, rollers, and the like are arranged inside the casing 100 so that the main scanning direction substantially orthogonal to the conveyance direction of the recording paper P (indicated by an arrow B in the figure) is the longitudinal direction. ing.

  The cleaner 3 removes toner and paper powder before one stroke (one rotation) adhering to the surface of the photosensitive drum 2 and cleans the surface of the photosensitive drum 2. The charger 4 uniformly charges the surface of the photosensitive drum 2 cleaned by the cleaner 3. In this image forming apparatus 1, the photosensitive drum 2, the cleaner 3, and the charger 4 are all attached to a common housing as the photosensitive unit 50, and are exchangeably mounted inside the housing 100. That is, even when the number of times of cumulative printing increases and the photosensitive drum 2 reaches the end of its service life, it is possible to print again by replacing only the photosensitive unit 50 with another one.

  The scan unit 5 irradiates the laser beam L while scanning the surface of the photosensitive drum 2 charged by the charger 4, thereby forming a latent image on the surface of the photosensitive drum 2. The scan unit 5 is powered by a power supply device (not shown), and a drive voltage for emitting the laser beam L is applied by the power supply device. The developing brush 6 is detachably mounted inside the housing 100 as a toner cartridge 60 together with a toner tank 6a filled with toner, and the toner adheres to the surface of the photosensitive drum 2 where the latent image is formed. To form a toner image. When printing on the recording paper is repeated and the amount of toner in the toner tank 6a decreases, the printing can be further repeated by replacing the toner cartridge 60 with another one having a large amount of remaining toner. ing.

  The transfer roller 7 is provided so as to face the surface of the photosensitive drum 2 at a predetermined transfer position downstream of the developing brush 6 in the rotation direction of the photosensitive drum 2 (in the direction of arrow R in the figure). The transfer roller 7 is attached to a roller holding member 71 fixed to the opening / closing lid 100a. The transfer roller 7 rotates while pressing the recording paper P against the surface of the photosensitive drum 2 to charge the surface of the recording paper P, and the toner image formed on the surface of the photosensitive drum 2 is transferred to the recording paper P. Transfer on top of. A transfer voltage for charging the surface of the recording paper P is applied to the transfer roller 7 from a power supply device. The recording paper P on which the image is formed on the surface by the transfer roller 7 is conveyed to the fixing roller 8. The fixing roller 8 fixes the toner by applying heat and pressure to the recording paper P while sandwiching the recording paper P between the fixing roller 8 and the pressing roller 8a disposed opposite thereto. Heat for fixing the toner is supplied from a heater (for example, a halogen lamp) built in the fixing roller 8. The heater generates heat when a fixing voltage is applied by the power supply device. The photosensitive drum 2, the transfer roller 7, the fixing roller 8, and the pressing roller 8 a are transmitted with driving force by the motor of the recording paper transport mechanism 20, so that the recording paper P is moved at a predetermined speed inside the housing 100. It is configured to be conveyed.

  Next, mounting of the photosensitive unit 50 to the image forming apparatus 1 will be described. FIG. 2 shows a state where the open / close lid 100a of the image forming apparatus 1 is opened, and FIGS. 3A and 3B show a mounting portion of the photoconductor unit 50. FIG. As shown in FIG. 2, for example, resin frame portions 30 are disposed on both side portions inside the housing 100. Although only one frame portion 30 is shown in the figure, the other frame portion 30 is also configured in a substantially bilaterally symmetrical shape.

  The rotating shaft 2a of the photosensitive drum 2 protrudes from both sides of the photosensitive unit 50. The frame portion 30 is formed with guide grooves 31 having a width dimension larger than the diameters of both ends of the rotating shaft 2a and capable of fitting the rotating shaft 2a. Since the guide groove 31 is formed to have a width dimension larger than the diameter of the rotation shaft 2a, the rotation shaft 2a can be easily fitted into the guide groove 31 when the photoreceptor unit 50 is mounted from the outside as will be described later. It is configured so that it can be worn. The guide groove 31 is formed in a substantially horizontal direction from the back side of the housing 100 to the front side. The back surface side of the housing 100 of the guide groove 31 is open toward the outside of the housing 100. Further, as shown in FIG. 3A, the end of the rotation shaft 2 a is attached to the end portion of the guide groove 31 on the front surface side of the housing 100 with the rotation shaft 2 a fitted in the guide groove 31. The positioning part 31a is formed so that the part vicinity site | part may contact | abut. A tapered portion 31b formed so that the width of the guide groove 31 becomes narrower as it approaches the positioning portion 31a is provided in the vicinity of the positioning portion 31a in the side edge portion above the guide groove 31. Yes. The tapered portion 31b has a diameter of a circle inscribed in the lower end surface of the tapered portion 31b, the positioning portion 31a, and the lower edge portion of the guide groove 31, or the rotational shaft 2a. It is formed to be slightly larger than the diameter. In addition, a spring (biasing member) 35 is formed in the vicinity of the positioning portion 31a of the guide groove 31 to abut against the rotating shaft 2a and bias the rotating shaft 2a.

  As shown in the drawing, the spring 35 is, for example, a torsion spring, and the rotating shaft 2a is held in a state where a spring portion 35a wound in a substantially circular shape is held in a portion of the frame portion 30 above the end portion of the guide groove 31. Are arranged so as to be twisted in a substantially perpendicular plane. The spring 35 is arranged in a state where one arm portion 35b of the spring 35 is supported by the frame portion 30 so that the spring 35 does not rotate due to displacement upward. And the sliding contact part 35c which is the other arm part of the spring 35 is comprised so that a repulsive force may be acted downward when it is displaced upwards. As shown in the figure, when the spring 35 is in a natural state, the sliding contact portion 35c is arranged such that the distance from the lower side edge portion of the guide groove 31 is smaller than the diameter of the end portion of the rotating shaft 2a. The central portion of the slidable contact portion 35 c is formed so as to project substantially horizontally toward the guide groove 31. Of the sliding contact portion 35c, a portion near the spring portion 35a is formed in an oblique direction so as to face a corner portion formed by the lower side edge portion of the guide groove 31 and the positioning portion 31a. A pressing portion 35d is provided.

  As shown in the drawing, the photosensitive unit 50 has a portion in the vicinity of both end portions of the rotation shaft 2a fitted in the guide groove 31 from the back side of the casing 100, and the front of the casing 100 (in the direction of arrow S in the figure). ) Along the guide groove 31. At this time, the vicinity of the end of the rotating shaft 2a is in sliding contact with the sliding contact portion 35c projecting toward the guide groove 31 in the spring 35 of the guide groove 31 and the lower side edge portion of the guide groove 31. The sliding portion 35c is slid while being displaced upward. Then, as shown in FIG. 3B, the photosensitive unit 50 is slid, and the vicinity of the end of the rotating shaft 2a is in contact with the lower side edge of the guide groove 31 and the positioning portion 31a. Thus, the photosensitive unit 50 is positioned at a predetermined position where the printing operation can be performed. At this time, the deformation of the spring 35 is slightly restored from the state in which the rotating shaft 2a is in sliding contact with the sliding contact portion 35c, and the pressing portion 35d is in contact with the upper rear portion of the vicinity of the end of the rotating shaft 2a. The restoring force of the spring 35 acts on the rotating shaft 2a toward the front lower side (in the direction of arrow F in the figure). That is, the restoring force of the spring 35 urges the vicinity of the end portion of the rotating shaft 2a so as to contact the lower side edge portion of the guide groove 31 and the positioning portion 31a. Is held in a state where it is positioned at a predetermined position where the printing operation is possible, and is mounted inside the housing 100. In the photosensitive unit 50, the opening / closing lid 100a is opened from the state of being mounted inside the housing 100, and the rotating shaft 2a is deformed in the guide groove 31 while the spring 35 is deformed in the opposite direction to that at the time of mounting. Can be removed from the main body of the image forming apparatus 1.

  As described above, in the present embodiment, since the tapered portion 31b is formed in the vicinity of the positioning portion 31a on the side edge portion above the guide groove 31, the photosensitive unit 50 is mounted in a predetermined position. The rotating shaft 2a is close to the lower surface of the tapered portion 31b. Accordingly, the vicinity of each end of the rotating shaft 2a abuts on the tapered portion 31b, so that the displacement of the rotating shaft 2a from the predetermined position is restricted. Therefore, even when the photosensitive drum is driven during printing or the recording paper P is transported between the photosensitive drum 2 and the transfer roller 7, rattling of the photosensitive drum 2 is less likely to occur. An image can be appropriately formed on the recording paper P. Since the tapered portion 31b is formed in each guide groove 31 into which the vicinity of both ends of the rotating shaft 2a is fitted, rattling of the photosensitive drum 2 is less likely to occur. Further, since the springs 35 for energizing the vicinity of both end portions of the rotating shaft 2a are integrally formed, the number of parts is small, and the backlash of the photosensitive drum 2 is maintained with a simple and low manufacturing cost. It is possible to form an image properly by suppressing the sticking.

  In addition, this invention is not limited to the structure of the said embodiment, A various deformation | transformation is possible suitably in the range which does not change the meaning of invention. For example, the guide grooves may be formed in different directions instead of the substantially horizontal direction. Further, the photosensitive drum may be configured not to be incorporated in the photosensitive unit, but to be attached to the frame portion of the housing as a single photosensitive drum. Furthermore, the taper portion may be formed only on one side of the housing so as to be close to one end portion of the rotation shaft in a state where the photosensitive drum is mounted on the housing. In other words, in the present invention, the taper portion is formed so as to be close to the vicinity of the end portion of the rotation shaft of the photosensitive drum, and the rotation of the rotation shaft is made difficult to suppress the rattling of the photosensitive drum. By doing so, an image can be formed properly.

1 is a side view showing an example of an image forming apparatus according to an embodiment of the present invention. The perspective view which shows the time of mounting | wearing with the photoreceptor unit of an apparatus same as the above. (A) is a side view showing a state in which the photosensitive unit is slid in order to mount the photosensitive unit on the apparatus, and (b) is a side view showing a state in which the photosensitive unit is mounted on the apparatus. FIG. 6 is a side view showing a mounting structure of a photosensitive drum in a conventional image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photosensitive drum 4 Charger (charging means)
DESCRIPTION OF SYMBOLS 5 Scan unit 6 Developing apparatus 7 Transfer roller 8 Fixing roller 10 Image forming part 20 Recording paper conveyance mechanism 30 Frame part 31 Guide groove 31a Positioning part 31b Taper part 35 Spring (biasing member)
40 Control unit 100 Case 110 Paper feed cassette (paper feed tray)
L Laser beam P Recording paper

Claims (3)

A housing,
A paper feed tray attached to the housing and on which recording paper is placed;
A recording paper transport mechanism for transporting the recording paper placed on the paper feed tray into the housing;
An image forming unit disposed inside the housing and forming an image on the recording paper conveyed by the recording paper conveying mechanism;
A control unit that controls each part of the apparatus to form an image on recording paper,
The image forming unit includes:
A photoconductive drum having a photoconductive layer formed on a surface thereof, which is rotatably arranged around a rotary axis so that a main scanning direction substantially orthogonal to a recording paper conveyance direction is a longitudinal direction;
Charging means for charging the surface of the photosensitive drum substantially uniformly;
A scanning unit that forms a latent image by irradiating the surface of the photosensitive drum with a laser beam; and
A developing device for forming a toner image by attaching toner to a portion of the surface of the photosensitive drum on which a latent image is formed;
A toner image formed on the surface of the photosensitive drum is recorded at a predetermined transfer position downstream of the developing device in the rotation direction of the photosensitive drum so as to face the surface of the photosensitive drum. A transfer roller for transfer onto the paper;
A fixing roller for fixing the toner image on the recording paper by applying predetermined heat and pressure to the recording paper on which the toner image has been transferred,
Frame portions each having a width dimension larger than the diameter of the end portion of the rotating shaft and having guide grooves into which the vicinity of the end portion of the rotating shaft is fitted are formed on both side portions inside the casing. Arranged,
Each guide groove is provided with a positioning portion that abuts in the vicinity of the end portion of the rotation shaft fitted in the guide groove and regulates the position of the rotation shaft.
Each of the frame portions includes a spring that is integrally formed and urges a rotation shaft disposed along the guide groove toward one side edge portion of the guide groove and the positioning portion. Installed,
The photosensitive drum is biased by the spring so that adjacent portions of both end portions of the rotating shaft are in contact with one side edge portion and the positioning portion of the guide grooves, respectively. The apparatus main body is held in the guide groove and is mounted at a predetermined position inside the housing, and the rotating shaft is slid along the guide groove while deforming the spring from the mounted state. In the image forming apparatus configured to be removable from
When the photosensitive drum is in the predetermined position so that the width of the guide groove becomes narrower in the vicinity of the positioning portion in the other side edge portion of each guide groove so as to approach the positioning portion. A tapered portion formed so as to be close to the rotation shaft is provided,
In a state where the photosensitive drum is mounted at the predetermined position, the vicinity of each end of the rotating shaft abuts on the tapered portion, thereby restricting the displacement of the rotating shaft from the predetermined position. Thus, an image forming apparatus is configured so that an image can be appropriately formed on a recording sheet. A photoconductor having a photoconductor layer formed on the surface thereof, which is arranged in the housing of the apparatus so as to be rotatable about a rotation axis so that a main scanning direction substantially orthogonal to the conveyance direction of the recording paper is a longitudinal direction. Equipped with a drum,
The photosensitive layer is exposed to form a latent image on the surface of the photosensitive drum, the toner is attached to the surface of the photosensitive drum on which the latent image is formed and developed, and the toner on the surface of the photosensitive drum is removed. An image forming apparatus for forming an image on a recording paper by transferring and fixing the recording paper on the surface of the recording paper,
A frame part in which a guide groove into which a portion near the end of the rotating shaft is fitted is disposed on a side part inside the housing,
The guide groove is formed in a position near the end of the rotation shaft fitted in the guide groove and restricts the position of the rotation shaft, and in the vicinity of the positioning portion. A taper portion formed so that the width of the guide groove becomes narrower as it approaches,
An urging member that urges a portion near the end of the rotating shaft toward the positioning portion;
In a state where the photosensitive drum is urged by the urging member and abuts on the positioning portion and is mounted at a predetermined position, the rotation shaft abuts on the taper portion, so that a predetermined position of the rotation shaft is reached. An image forming apparatus configured to be restricted from being displaced. The image forming apparatus according to claim 2, wherein the biasing member is an integrally formed spring.

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