Image forming apparatus

Abstract

To provide an image forming apparatus capable of suppressing discharge of ozone generated from a corona charger to the outside of the apparatus with a simple configuration.SOLUTION: The image forming apparatus 1 includes the drum unit 31 detachably attached to the drum-unit accommodating section 21 through the opening 27 formed in the apparatus main body 3. The drum unit 31 includes a photoreceptor drum 41, a corona charger 43 for corona-charging the photoreceptor drum 41, and a drum cover 47 which is rotatable between a protection posture for covering the photoreceptor drum 41 and an exposure posture for exposing the photoreceptor drum 41. When the drum unit 31 is attached to the drum unit accommodating portion 21, the drum cover 47 pivots from the protection attitude to the exposure attitude and closes the flow path that allows the periphery of the charger 43 to communicate with the outside of the apparatus main body 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus equipped with a corona charger that charges a photosensitive drum. [Background technology]

[0002] In an image forming apparatus equipped with a corona charger, it is necessary to take measures to prevent ozone generated during corona charging from being discharged outside the apparatus.

[0003] For example, the image forming apparatus described in Patent Document 1 is equipped with a charger exhaust duct equipped with a filter. Also, the image forming apparatus described in Patent Document 2 is equipped with a shielding part that makes the space from the ozone exhaust space to the intake port of the ozone exhaust duct, together with the photosensitive drum, a closed ozone retention space. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-015991 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-241175 Summary of the Invention [Problem to be solved by the invention]

[0005] The image forming apparatus disclosed in Patent Document 1 requires an electrification exhaust duct and a filter, which increases the number of parts and leads to increased costs. Also, the image forming apparatus disclosed in Patent Document 2 requires the creation of an ozone retention space, which increases the size of the apparatus.

[0006] SUMMARY OF THE INVENTION In consideration of the above circumstances, an object of the present invention is to provide an image forming apparatus with a simple configuration that can suppress the emission of ozone generated from a corona charger to the outside of the apparatus. [Means for solving the problem]

[0007] In order to achieve the above object, the image forming apparatus of the present invention is an image forming apparatus comprising a drum unit that is removably mounted in a drum unit housing through an opening formed in the apparatus main body, the drum unit comprising a photosensitive drum, a corona charger that corona charges the photosensitive drum, and a drum cover that is rotatable between a protective position that covers the photosensitive drum and an exposed position that exposes the photosensitive drum, and the drum cover is characterized in that when the drum unit is mounted in the drum unit housing, it rotates from the protective position to the exposed position to block a flow path that connects the periphery of the charger with the outside of the apparatus main body.

[0008] In the present invention, the device main body has an enclosed space, and the drum cover forms an exhaust path that connects the periphery of the charger to the enclosed space when the drum unit is attached to the drum unit accommodating section and rotated to the exposed position.

[0009] In the present invention, the device further includes an ejection tray on which paper sheets that have been ejected after image formation are stacked and which opens and closes an opening formed in the device main body, and the sealed space is a space for the drum unit to move, which is provided between the opening and the drum unit accommodating section. [Effects of the Invention]

[0010] According to the present invention, the air containing ozone generated in the charger can be retained inside the main body of the apparatus by the drum cover, so that the amount of ozone discharged outside the main body of the apparatus can be reduced. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a front view showing a configuration of an image forming apparatus according to an embodiment of the present invention; [Figure 2] 1 is a perspective view showing a drum unit in an image forming apparatus according to an embodiment of the present invention; [Figure 3] 1 is a cross-sectional view showing a drum unit in an image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

[0013] First, the overall configuration of the image forming apparatus 1 will be described with reference to Fig. 1. Fig. 1 is a front view schematically showing the internal configuration of the image forming apparatus 1. The symbols Fr and Rr used in the following drawings indicate the front side and the rear side, respectively.

[0014] The device body 3 of the image forming device 1 contains a paper feed cassette 5 that stores paper, a paper feed device 7 that feeds paper from the paper feed cassette 5, an image forming section 9 that forms a toner image on paper using an electrophotographic method, a fixing device 11 that fixes the toner image to the paper, a discharge device 13 that discharges paper, and a discharge tray 15 on which the discharged paper is stacked.

[0015] A paper feed cassette housing section 17 that houses a paper feed cassette 5 is formed at the bottom inside the device main body 3. Furthermore, a developing unit housing section 19 that houses a developing unit 33 (described later) is formed above the rear of the paper feed cassette housing section 17. Furthermore, a drum unit housing section 21 that houses a drum unit 31 (described later) is formed above the developing unit housing section 19.

[0016] Furthermore, a front opening 23 that communicates with the paper feed cassette housing 17 is formed at the bottom of the front surface of the device body 3. Furthermore, a paper discharge opening 25 that faces forward is formed on the top surface of the device body 3. Furthermore, an upper opening 27 for inserting and removing the drum unit 31 and the developing unit 33 is formed on the top surface of the device body 3 below the discharge opening 25. The upper opening 27 is closed by the discharge tray 15. The discharge tray 15 is rotatable, and the upper opening 27 is opened by rotating it upward. Furthermore, rails 29 that lead from the upper opening 27 to the developing unit housing 19 and the drum unit housing 21 are formed on the inner surfaces of the left and right side panels of the device body 3.

[0017] First, we will explain the paper feed cassette 5. The paper feed cassette 5 is attached to the paper feed cassette housing section 17 so as to be removable through the front opening 23 of the device main body 3. The paper feed cassette 5 contains sheets of paper on which images are formed.

[0018] Next, we will explain the paper feeder 7. The paper feeder 7 is located above the rear of the paper feed cassette housing unit 17. The paper feeder 7 feeds paper from the paper feed cassette 5 attached to the paper feed cassette housing unit 17.

[0019] Next, we will explain the image forming unit 9. The image forming unit 9 is made up of a drum unit 31, a developing unit 33, and an exposure device 35. The drum unit 31 and the developing unit 33 are removably attached to the drum unit housing section 21 and the developing unit housing section 19. The exposure device 35 is fixed to the apparatus main body 3.

[0020] First, the drum unit 31 will be described with reference to Figures 2 and 3. Figure 2 is a perspective view showing the drum unit 31, and Figure 3 is a cross-sectional view showing the drum unit 31. As shown in Figure 3, the drum unit 31 includes a photosensitive drum 41, a corona charger 43, a transfer roller 45, a drum cover 47, and a drum housing 49 that supports these components.

[0021] 2, the drum housing 49 has a main body portion 49A and a fixed portion 49B arranged parallel to each other. The main body portion 49A supports the photosensitive drum 41, the corona charger 43, the transfer roller 45, and the drum cover 47. The fixed portion 49B is provided with a handle, a positioning portion for positioning with the drum unit accommodating portion 21, and the like. Furthermore, a guide pin 51 is provided on the side surface of the fixed portion 49B.

[0022] As shown in FIG. 3, photosensitive drum 41 is rotatably supported by main body 49A. Corona charger 43 and transfer roller 45 are arranged around photosensitive drum 41 at a predetermined interval in the circumferential direction of photosensitive drum 41. A transfer nip is formed between photosensitive drum 41 and transfer roller 45. Photosensitive drum 41 is exposed from two spaces along the circumferential direction between corona charger 43 and transfer roller 45. One space (referred to as the anti-fixed portion side space) faces the side opposite fixed portion 49B, and the other space (referred to as the fixed portion side space) faces fixed portion 49B.

[0023] The drum cover 47 will now be described. The drum cover 47 covers the photosensitive drum 41 exposed from the space on the opposite side to the fixed portion. A rotation shaft 53 is provided at the upper end of the drum cover 47 (the end on the corona charger 43 side). The rotation shaft 53 is rotatably supported by the main body 49A on both sides of the space on the opposite side to the fixed portion of the main body 49A. When the drum cover 47 is rotated downward around the rotation shaft 53, the space on the opposite side to the fixed portion is closed, as shown by the solid lines in FIGS. 2 and 3, and the photosensitive drum 41 is protected (this is the protected position). When the drum cover 47 is rotated upward around the rotation shaft 53, the space on the opposite side to the fixed portion is opened, as shown by the two-dot chain line in FIG. 3, and the photosensitive drum 41 is exposed (this is the exposed position).

[0024] 2, a coil portion of a torsion coil spring 55 is fitted onto the rotary shaft 53. The torsion coil spring 55 biases the drum cover 47 toward the protective position. The rotary shaft 53 is also provided with an opening / closing lever 57 extending radially of the rotary shaft 53. When the opening / closing lever 57 is pressed, the drum cover 47 rotates from the protective position to the exposed position.

[0025] Without the drum cover 47, when the drum unit 31 is removed from the device main body 3, the photosensitive drum 41 is exposed from the space opposite the fixed portion, which could cause the photosensitive drum 41 to come into contact with other components. As described below, the drum unit 31 is attached to the drum unit housing 21 by gripping the handle of the fixed portion 49B and inserting the drum unit 31 into the device main body 3 with the main body portion 49A facing forward. At this time, the photosensitive drum 41 could come into contact with the device main body 3 and be damaged. Therefore, providing the drum cover 47 protects the photosensitive drum 41. Although the photosensitive drum 41 is also exposed from the space on the fixed portion 49B side, the fixed portion 49B is located outside this space, making it less likely to come into contact with other components. When the drum unit 31 is attached to the drum unit housing 21, the photosensitive drum 41 exposed from the space on the fixed portion side faces backward in the installation direction and therefore does not come into contact with the device main body 3. Therefore, even if the photosensitive drum 41 is exposed from the space on the fixed portion side, no major problem occurs.

[0026] The drum unit 31 is removably mounted in the drum unit accommodating section 21 through the upper opening 27 of the device main body 3. In detail, the drum unit 31 is mounted in the drum unit accommodating section 21 by gripping the handle of the fixing section 49B of the drum housing 49, engaging the guide pin 51 with the rail 29 with the main body section 49A first, and moving the drum unit 31 along the rail 29.

[0027] Furthermore, as the drum unit 31 is moved into the drum unit housing 21, the opening / closing lever 57 of the drum cover 47 eventually comes into contact with a contact piece (not shown) provided on the device main body 3. Then, as the drum unit 31 is moved further, the opening / closing lever 57 is pressed by the contact piece, and the drum cover 47 begins to rotate to the exposed position. When the drum unit 31 is attached to the drum unit housing 21, the drum cover 47 rotates completely to the exposed position.

[0028] Next, the developing unit 33 will be described. As shown in FIG. 1, the developing unit 33 includes an agitating roller, a supply roller, a developing roller, and a developing housing that supports these rollers and contains developer. All rollers are rotatably supported in the developing housing. A portion of the outer circumferential surface of the developing roller is exposed through an opening formed in the developing housing.

[0029] The developing unit 33 is removably mounted in the developing unit accommodating section 19 through the upper opening 27 of the apparatus main body 3. Guide pins (not shown) are provided on the left and right side plates of the developing housing. The developing unit 33 is mounted in the developing unit accommodating section 19 by engaging these guide pins with the rails 29 and moving the developing unit 33 along the rails 29.

[0030] When the developing unit 33 is attached, a portion of the outer peripheral surface of the developing roller exposed from the opening of the developing housing faces, with a predetermined gap between them, a portion of the outer peripheral surface of the photosensitive drum 41 exposed from the drum housing 49 of the drum unit 31. A gap is formed between the developing unit 33 and the drum unit 31, allowing the laser light emitted from the exposure device 35 to pass through.

[0031] Next, a description will be given of the exposure device 35. The exposure device 35 is disposed in front of the developing unit housing portion 19 and below the upper opening 27.

[0032] Next, we will explain the fixing device 11. The fixing device 37 includes a heating roller and a pressure roller, and forms a fixing nip between the two rollers. The fixing device 37 is disposed above the drum unit housing 21 with a predetermined gap therebetween.

[0033] Next, the discharge device 13 will be described. The discharge device 13 includes a pair of discharge rollers. The discharge device 13 is disposed inside the discharge opening 25.

[0034] Furthermore, the apparatus main body 3 is formed with a transport path 61 along which the paper is transported from the paper feed device 7 through the transfer nip of the image forming unit 9 and the fixing nip of the fixing device 11 toward the discharge device 13.

[0035] 1, when the drum unit 31 and the developing unit 33 are installed in their respective storage compartments 21 and 19, a space S is formed below the discharge tray 15, surrounded by the drum unit 31, the developing unit 33, the exposure device 35, the fixing device 11, and the discharge tray 15. As described above, this space S is provided between the upper opening 27 and the developing unit storage compartment 19 and the drum unit storage compartment 21. This space S is the space within which the drum unit 31 and the developing unit 33 move.

[0036] The image forming operation of the image forming apparatus 1 having the above configuration will be described. Paper fed from the paper feed cassette 5 by the paper feed device 7 is transported to the image forming unit 9 along the transport path 61. In the image forming unit 9, a toner image is formed on the paper. Specifically, in the drum unit 31, the photosensitive drum 41 is corona-charged by the corona charger 43 to a predetermined potential. Then, the exposure device 35 irradiates the photosensitive drum 41 with laser light based on image data. This forms an electrostatic latent image on the photosensitive drum 41. In the development unit 33, the toner contained in the development housing is stirred and charged with the developer by the stirring roller, and the charged toner is supplied to the development roller by the supply roller and held on the development roller. The held toner is supplied to the electrostatic latent image formed on the photosensitive drum 41, and the electrostatic latent image is developed into a toner image. The toner image is transferred from the photosensitive drum 41 to the paper at the transfer nip.

[0037] The paper on which the toner image has been formed is transported along transport path 61 to fixing device 11, where the toner image is fixed to the paper at the fixing nip of fixing device 11. The paper on which the toner image has been fixed is discharged by discharge device 13 from discharge port 25 to discharge tray 15.

[0038] As described above, when the drum unit 31 is installed in the drum unit housing 21, the drum cover 47 is rotated to the exposed position. As shown in FIG. 1, the drum cover 47 rotates forward of the transfer nip and the fixing nip. At this time, it is preferable that the drum cover 47 abuts against the housing of the fixing device 11 or the like. As a result, the transport path 61 is blocked from the space around the corona charger 43.

[0039] For this reason, air containing ozone generated during corona charging by corona charger 43 does not flow into transport path 61, but is guided from around corona charger 32 by drum cover 47 and flows mainly into transfer space S (see arrow F1 in FIG. 1). If drum cover 47 does not block transport path 61 from the space around corona charger 43, a flow path (see arrow F2 in FIG. 1) is formed that runs from around corona charger 43 through transport path 61 to discharge port 25. The air containing ozone may ride on the air current generated by the transport of paper and be discharged to the outside through flow path F2.

[0040] 1, however, this flow path F2 is blocked by the drum cover 47. Furthermore, the drum cover 47 forms an exhaust path F1 that runs from the periphery of the corona charger 43, passing below the fixing device 11, and toward the transfer space S. Air containing ozone generated by the corona charger 43 is guided to the transfer space S through this exhaust path F1. The ozone guided to the transfer space S remains in the transfer space S and disappears over time.

[0041] As described above, according to the image forming apparatus 1 of the present invention, the air containing ozone generated by the corona charger 43 can be retained within the device main body 3, thereby reducing the amount of ozone emitted outside the device main body 3.

[0042] A drum unit 31 configured as shown in FIG. 2 requires a drum cover 47 to protect the photosensitive drum 41. In the present invention, by providing this drum cover 47 in a rotatable manner, it is possible to protect the photosensitive drum 41 when necessary and block the ozone flow path when the drum unit 31 is attached to the drum unit housing 21 and protection is not required. Therefore, there is no need to add a new member to block the ozone flow path. Furthermore, since the transfer space S where ozone-containing air remains is an existing space, there is no need to provide a new space for ozone retention. Furthermore, since the drum cover 47 automatically rotates to the exposed position when the drum unit 31 is attached to the drum unit housing 21, the mechanism for rotating the drum cover 47 can be simplified.

[0043] The enclosed space in which ozone remains may be other spaces (for example, the paper feed cassette housing portion 17) in addition to the space S in which the drum unit 31 and the developing unit 33 move.

[0044] Although the present invention has been described with reference to specific embodiments, the present invention is not limited to the above embodiments, and those skilled in the art may modify the above embodiments without departing from the scope and spirit of the present invention. [Explanation of symbols]

[0045] 1. Image forming device 3. Device body 15 Output tray 21 Drum unit housing 27 Upper opening 31 Drum unit 41 Photosensitive drum 43 Corona charger 47 Drum Cover S Moving space (closed space)

Claims

1. An image forming apparatus including a drum unit that is removably mounted in a drum unit housing through an opening formed in a device body, The drum unit is A photosensitive drum; a charger for corona-charging the photosensitive drum; a drum cover that is rotatable between a protection position that covers the photosensitive drum and an exposure position that exposes the photosensitive drum, an image forming apparatus characterized in that, when the drum unit is installed in the drum unit accommodating section, the drum cover rotates from the protective position to the exposed position to block a flow path connecting the periphery of the charger to the outside of the apparatus main body.

2. The device body has an enclosed space, 2. The image forming apparatus according to claim 1, wherein the drum cover forms an exhaust path that connects the periphery of the charger to the sealed space when the drum unit is attached to the drum unit accommodating section and rotated to the exposed position.

3. The printer further includes a discharge tray on which paper sheets discharged after image formation are stacked and which opens and closes the opening, 3. The image forming apparatus according to claim 2, wherein the sealed space is a space for moving the drum unit provided between the opening and the drum unit housing portion.

Images