JP7532086B2 - Image forming apparatus and cartridge - Google Patents

Description

The present invention relates to an image forming apparatus using an electrophotographic method, an electrostatic recording method, or the like, and a cartridge that is removably mounted to the main body of the image forming apparatus.

Conventionally, image forming devices using electrophotography have been widely used as copiers, printers, facsimiles, and multifunction machines having multiple functions thereof. In such image forming devices, a process is adopted in which the surface of a photosensitive drum as an image carrier is charged, exposed by a laser scanner to form an electrostatic latent image, a toner image is formed by a developing device using toner, and the toner image is transferred onto a sheet to make it visible. Parts such as the photosensitive drum involved in such an image formation process have a short lifespan compared to the lifespan of other members built into the device body. For this reason, image forming devices in which such short-life parts are unitized as a drum cartridge (hereinafter referred to as a cartridge), which is detachable from the device body and can be replaced according to their lifespan, have become widespread (see Patent Document 1). In such image forming devices, for example, a sensor or other parts or units (hereinafter referred to as units) that require regular maintenance such as cleaning may be detachably mounted near the mounting position of the cartridge.

JP 2017-44845 A

However, in the image forming device described in Patent Document 1, when replacing a unit that is removably attached near a cartridge, it was necessary to remove the cartridge, replace the unit, and then reattach the cartridge. This meant that the unit replacement work required a lot of labor and was complicated.

The present invention aims to provide an image forming device and cartridge that can improve the ease of replacing a unit, even after the cartridge and unit have been installed.

The image forming apparatus of the present invention comprises an apparatus main body, a cartridge having an image carrier rotatable around a rotation axis and removably arranged relative to the apparatus main body along the rotation axis direction of the image carrier , and a unit removably arranged relative to the apparatus main body along the rotation axis direction of the image carrier, wherein the cartridge has a door, and the door is movable to a first position where at least a portion of the door overlaps with the unit when viewed along the rotation axis direction, upstream of the mounting direction of the unit when mounted to the apparatus main body, and a second position forming an opening through which the unit can pass when mounted or removed along the rotation axis direction .

The cartridge of the present invention is a cartridge having an image carrier rotatable around a rotation axis , and is removably attached to the main body of the device along the rotation axis direction of the image carrier , and is characterized in that it has a door that is movable upstream of the attachment direction of a unit removably attached to the main body of the device along the rotation axis direction of the image carrier to a first position where at least a portion of the unit overlaps with the unit when viewed along the rotation axis direction, and a second position separated from the unit when viewed along the rotation axis direction.

The present invention improves the ease of replacing a unit, even after the cartridge and unit have been installed.

1 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment. FIG. 2 is a side view showing a large-diameter photosensitive drum and an exhaust duct according to the first embodiment. 2 is a perspective view showing the drum cartridge in a state where a door is in a closed position in the image forming apparatus according to the first embodiment. FIG. 4 is a front view showing the drum cartridge and the first detection unit in a state where the door is in a closed position in the image forming apparatus according to the first embodiment. FIG. 2 is a perspective view showing the drum cartridge and the first detection unit in a state where the door is in an open position in the image forming apparatus according to the first embodiment. FIG. 13 is a front view showing a drum cartridge and a first detection unit in a state where a door is in a closed position in an image forming apparatus according to a second embodiment. FIG. FIG. 11 is a perspective view showing a drum cartridge and a first detection unit in a state where a door is in a closed position in an image forming apparatus according to a second embodiment. FIG. 11 is a perspective view showing a drum cartridge and a first detection unit in a state where a door is in an open position in an image forming apparatus according to a second embodiment.

First Embodiment
A first embodiment of the present invention will be described in detail below with reference to Figures 1 to 5. In this embodiment, a tandem-type full-color printer is described as an example of an image forming apparatus 1. However, the present invention is not limited to a tandem-type image forming apparatus 1, but may be an image forming apparatus of another type, and is not limited to being full-color, but may be monochrome or monocolor.

[Image forming apparatus]
As shown in FIG. 1, the image forming apparatus 1 is an electrophotographic full-color printer having image forming units PY, PM, PC, and PK of four colors (yellow, magenta, cyan, and black) in the apparatus main body 1a. In this embodiment, the image forming units PY, PM, PC, and PK are arranged along the rotation direction R2 of an intermediate transfer belt 40 described later in an intermediate transfer tandem system. The image forming apparatus 1 forms a toner image (image) on a recording material S in response to an image signal from a document reading device (not shown) connected to the apparatus main body 1a or a host device such as a personal computer connected to the apparatus main body 1a so as to be able to communicate with the apparatus main body 1a. Examples of the recording material S include sheet materials such as paper, plastic film, and cloth. In this embodiment, as shown in each figure, the front side of the image forming apparatus 1 is represented as the front direction F, the back side (back side) as the rear direction B, the left side as the left direction L, the right side as the right direction R, the upper side as the upper direction U, and the lower side as the lower direction D. The mounting direction of a drum cartridge 50 (described later) with respect to the apparatus main body 1a is designated as a rear direction B, and the removal direction is designated as a front direction F.

The image formation process will be described. First, the image forming units PY, PM, PC, and PK will be described. In this embodiment, the toner colors of the image forming units PY, PM, PC, and PK are yellow, magenta, cyan, and black, and among these, only the image forming unit PK has a different configuration. The image forming units PY, PM, and PC are configured almost identically except for the toner colors. Therefore, in the following, the black image forming unit PK and the yellow image forming unit PY will be described as examples, and the description of the other image forming units PM and PC will be omitted.

The image forming unit PK mainly includes a large-diameter photosensitive drum 2, a charging device 3, an exposure device 4, a developing device 5, and a cleaning device 6 having a cleaner blade 6a. The large-diameter photosensitive drum 2 and the cleaning device 6 are attached to a frame 51 and are unitized as a drum cartridge 50, which is an example of a cartridge. The drum cartridge 50 has a large-diameter photosensitive drum 2 that can rotate relative to the device main body 1a, and is provided in a manner that allows it to be attached and detached in the front-rear direction to the device main body 1a. In this embodiment, the drum cartridge 50 is described as being attachable and detachable in the front-rear direction to the device main body 1a, but this is not limited to this, and it may be attachable and detachable in the left-right direction or the up-down direction. After this drum cartridge 50 is attached to the device main body 1a of the image forming device 1, the charging device 3 is attached.

The image forming unit PY mainly includes a small diameter photosensitive drum 12, a charging roller 13, an exposure device 14, a developing device 15, and a cleaning device 16 having a cleaner blade 16a. The small diameter photosensitive drum 12, the charging roller 13, and the cleaning device 16 are unitized as a drum unit 17. The drum unit 17 and the developing device 15 are unitized as a process cartridge 18.

The process cartridge 18 is attached and detached while moving in the direction of the rotation axis of the small diameter photosensitive drum 12 (width direction W), which is the front-rear direction of the device body 1a, following the guide rail 20 attached to the device body 1a. The guide rail 20 is provided on both sides of the process cartridge 18 in the left-right direction X of the device body 1a, and has a drum guide portion 21 and a development guide portion 22. The drum guide portion 21 is provided facing the right direction R side of the cleaning device 16, and guides the right direction R side of the process cartridge 18 when the process cartridge 18 is attached to the device body 1a. The development guide portion 22 is provided facing the left direction L side of the development device 15, and guides the left direction L side of the process cartridge 18 when the process cartridge 18 is attached to the device body 1a. The guide rail 20 is fastened to the frame 1b constituting the device body 1a of the image forming device 1 with fastening members such as screws 23. In addition, the guide rail 20 has a protrusion 24 that protrudes upward U beyond the screw 23 to prevent it from getting caught on the screw 23 when attaching other components.

The image forming apparatus 1 is equipped with a control unit 10 for performing various controls such as the image forming operation described below. The operation of each part of the image forming apparatus 1 is controlled by the control unit 10 provided in the image forming apparatus 1. The series of image forming operations are controlled by the control unit 10 in accordance with the operation unit of the device main body 1a or each input signal via the network. The control unit 10 has a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. as an arithmetic control means. The CPU controls each part of the image forming apparatus 1 while reading a program corresponding to the control procedure stored in the ROM. The RAM stores working data and input data, and the CPU performs control by referring to the data stored in the RAM based on the above-mentioned programs, etc.

The image forming operation of the image forming apparatus 1 will be described below. In this embodiment, one large diameter photosensitive drum 2 and three small diameter photosensitive drums 12 are provided as photosensitive drums serving as image carriers. The large diameter photosensitive drum 2 is uniformly charged on its surface by a charging device 3 using a corona charging method, and the small diameter photosensitive drums 12 are uniformly charged on their surfaces by a charging roller 13 using a contact charging method. When the charging device 3 using the corona charging method charges the surface of the large diameter photosensitive drum 2, ozone may be generated.

Therefore, the image forming apparatus 1 is provided with an air circulation device 30 for removing the ozone generated by the charging device 3 from the vicinity of the large-diameter photosensitive drum 2. The air circulation device 30 has an air supply fan 31, an air supply duct 32 arranged on the upper part of the charging device 3, an exhaust duct 34 having one or more intake ports 33, an exhaust fan 35 arranged in the exhaust duct 34, and an ozone filter 36. The exhaust duct 34 is arranged downstream of the rotation direction R1 of the large-diameter photosensitive drum 2 of the charging device 3. The air taken in from the air supply fan 31 by the air circulation device 30 flows through the air supply duct 32 and is sent to the charging device 3. The air sent to the charging device 3 flows near the outer circumferential surface of the large-diameter photosensitive drum 2, passes through the exposure position, and then flows through the exhaust duct 34, which has been decompressed by the exhaust fan 35 from the intake port 33, and is discharged outside the machine via the ozone filter 36.

In addition to charging the opposing large-diameter photosensitive drum 2, the charging device 3 may also generate ions. The generated ions float downstream in the rotation direction R1 of the large-diameter photosensitive drum 2 due to the air flow that exhausts ozone and the rotation of the large-diameter photosensitive drum 2. If the ions float near the exposure position of the large-diameter photosensitive drum 2 and attach to the electrostatic latent image formed on the large-diameter photosensitive drum 2, the part that was discharged by exposure may be charged again, which may cause image defects. To prevent this, a conductive sheet 38 is provided that is grounded on the surface of the exhaust duct 34 that faces the large-diameter photosensitive drum 2 (see Figure 2), and the ions are attracted to the exhaust duct 34 side to collect the floating ions.

In addition, a potential sensor 39 is attached to the exhaust duct 34 between the exposure position and the development position of the large-diameter photosensitive drum 2. The potential sensor 39 detects the surface potential of the large-diameter photosensitive drum 2 in order to improve the in-plane uniformity of the latent image potential. If the distance between the sensor surface of the potential sensor 39 provided in the exhaust duct 34 and the conductive sheet 38 is short, the detection accuracy of the potential sensor 39 deteriorates. Therefore, in this embodiment, as shown in FIG. 2, a recess 34a is provided in the approximate center of the width direction W of the surface of the exhaust duct 34 facing the large-diameter photosensitive drum 2, and the potential sensor 39 is provided near the recess 34a. As a result, the conductive sheet 38 provided in this recess 34a is provided away from the sensor surface of the potential sensor 39.

A black image signal is input to the exposure device 4, and yellow, magenta, and cyan image signals are input to the exposure device 14. The exposure devices 4 and 14 irradiate the drum surface with laser light in accordance with the image signal, neutralizing the charge and forming an electrostatic latent image. The electrostatic latent images formed on the large diameter photosensitive drum 2 and the small diameter photosensitive drum 12 are developed into toner images using yellow, magenta, cyan, and black toners by the respective developing devices 5 and 15. The toner images developed on the large diameter photosensitive drum 2 and the small diameter photosensitive drum 12 are sequentially primarily transferred to the intermediate transfer belt 40, which is an example of an intermediate transfer body, by the primary transfer roller 8 that forms a primary transfer nip portion T1 with the large diameter photosensitive drum 2 and the small diameter photosensitive drum 12, respectively.

That is, the intermediate transfer belt 40 rotates in contact with the large diameter photosensitive drum 2, forming a primary transfer nip T1 between the large diameter photosensitive drum 2 and the intermediate transfer belt 40. The primary transfer roller 8 is an example of a transfer means, and transfers the toner image formed on the large diameter photosensitive drum 2 to the intermediate transfer belt 40. As a result, a full-color toner image is formed on the surface of the intermediate transfer belt 40. Note that, although the intermediate transfer body is the intermediate transfer belt 40 in this embodiment, it is not limited to this, and an intermediate transfer roller may also be used.

Downstream of the primary transfer roller 8 facing the large-diameter photosensitive drum 2 in the rotation direction R2 of the intermediate transfer belt 40, a first detection unit 41, which is an example of a first density detection unit as a unit, is arranged. The first detection unit 41 is a registration density detection unit provided to detect the toner density on the surface of the intermediate transfer belt 40, and has a registration detection sensor and a density sensor, which are arranged corresponding to the positions of the registration patch and the gradation patch. When the drum cartridge 50 is installed, the first detection unit 41 is arranged so as to be arranged in the first region Ar1, which is the region on the lower direction D side of the cleaning device 6, the upper direction U side of the intermediate transfer belt 40, and the right direction R side of the large-diameter photosensitive drum 2. That is, the first detection unit 41 is arranged in the first region Ar1, which is at least partially surrounded by the large-diameter photosensitive drum 2, the intermediate transfer belt 40, and the cleaning device 6. The first detection unit 41 is also detachably provided along the width direction W with respect to the device main body 1a.

A second detection unit 42, which is an example of a second density detection unit as a unit, is arranged upstream of the primary transfer roller 8 facing the large-diameter photosensitive drum 2 in the rotation direction R1 of the large-diameter photosensitive drum 2. The second detection unit 42 is provided to read the toner density, particularly the gradation patch, on the surface of the large-diameter photosensitive drum 2. The second detection unit 42 is arranged between the developing device 5 and the primary transfer nip portion T1. When the drum cartridge 50 is installed, the second detection unit 42 is arranged so as to be arranged in the second area Ar2, which is an area on the lower direction D side of the developing device 5, the upper direction U side of the intermediate transfer belt 40, and the left direction L side of the large-diameter photosensitive drum 2. That is, the second detection unit 42 is arranged in the second area Ar2, which is at least partially surrounded by the large-diameter photosensitive drum 2, the intermediate transfer belt 40, and the developing device 5. The second detection unit 42 is also detachably arranged along the width direction W with respect to the device main body 1a.

The residual toner on the large diameter photosensitive drum 2 and the small diameter photosensitive drum 12 is scraped off by the cleaner blades 6a and 16a, transported through the cleaning devices 6 and 16, and collected in a collected toner box (not shown). That is, the cleaning device 6, which is an example of a cleaning means, cleans the residual toner adhering to the large diameter photosensitive drum 2 after the toner image formed on the large diameter photosensitive drum 2 is transferred to the intermediate transfer belt 40.

Meanwhile, the recording material S conveyed from a sheet feeding section (not shown) is sent to the secondary transfer section 43 in synchronization with the toner image on the intermediate transfer belt 40. The toner image on the intermediate transfer belt 40 is secondarily transferred to the recording material S at the secondary transfer section 43, and the recording material S is sent to the fixing section 44. After the toner image is fixed to the recording material S by heat and pressure at the fixing section 44, the recording material S sent to the fixing section 44 is discharged outside the machine.

[Drum Cartridge]
3 to 5, the drum cartridge 50 of the black image forming unit PK has a frame 51, a large-diameter photosensitive drum 2 rotatably mounted on the frame 51, and a cleaning device 6 fixed to the frame 51. The frame 51, which is an example of a housing, has a front side plate 52 provided on the front direction F side of the width direction W, a rear side plate 53 provided on the rear direction B side, and a central stay 54 connecting the front side plate 52 and the rear side plate 53 in the width direction W. The front side plate 52 and the rear side plate 53 support the large-diameter photosensitive drum 2 and the cleaning device 6 by sandwiching them in the width direction W.

A positioning member 55 for supporting the rotation shaft of the large-diameter photosensitive drum 2 is provided on the side surface of the front side plate 52 in the forward direction F. The front side plate 52 is provided with a grip portion 56 that protrudes in the forward direction F to pull out the drum cartridge 50, and a door 60.

[door]
The configuration and operation of the door 60 will be described in detail below. The door 60 is provided on the front side plate 52, and is provided so as to be openable (movable) by swinging between a closed position (see FIGS. 3 and 4) which is a first position, and an open position (see FIG. 5) which is a second position. That is, in a state in which the drum cartridge 50 and the first detection unit 41 are mounted, the door 60 is disposed upstream in the mounting direction (rear direction B) of the first detection unit 41. When viewed from the width direction W, the closed position of the door 60 is a position where at least a part of the door 60 overlaps with the first detection unit 41, and the open position of the door 60 is a position separated from the first detection unit 41. In this embodiment, the door 60 is disposed so that at least a part of the door 60 overlaps with the first region Ar1 (see FIG. 4) when viewed from the width direction W in the closed position. In addition, when viewed from the width direction W, the door 60 in the closed position is positioned outside the outer peripheral surface downstream of the primary transfer nip portion T1 in the rotation direction R1 of the large diameter photosensitive drum 2, and between the cleaning device 6 and the intermediate transfer belt 40.

The door 60 is pivotally mounted on the front plate 52 by a rotating shaft 61 whose rotation center line is in the vertical direction. As shown in FIG. 4, the rotating shaft 61 is mounted on the right side R of the rotation center C of the large diameter photosensitive drum 2 and on the left side L of the cleaning device 6 when viewed from the width direction W. When the door 60 is pivoted forward in the F direction and positioned in the open position as shown in FIG. 5, an opening 62 is formed in the lower right part of the front plate 52. At this time, the door 60 and the first detection unit 41 do not overlap when viewed from the width direction W, so the first detection unit 41 can be attached to and detached from the device main body 1a by passing through the opening 62. In this way, the opening 62 is formed by opening the door 60, and the first detection unit 41 can be attached and detached without removing the drum cartridge 50.

When the door 60 is swung toward the rear direction B and positioned in the closed position as shown in Figures 3 and 4, the opening 62 (see Figure 5) is closed. At this time, the door 60 and the first detection unit 41 overlap when viewed from the width direction W, so the first detection unit 41 cannot be attached or detached. When the first detection unit 41 is attached, the door 60 is positioned in the closed position, which prevents the first detection unit 41 from being removed by mistake and suppresses the intrusion of light and dust into the first detection unit 41.

In this embodiment, the door 60 opens in the forward direction F, preventing the door 60 from interfering with the attached first detection unit 41, and shortening the distance between the front side plate 52 and the first detection unit 41 allows the drum cartridge 50 to be made smaller. Note that in this embodiment, the door 60 opens in the forward direction F, but this is not limited to this, and the door 60 may open in the rear direction B. Alternatively, the rotation shaft 61 is not limited to being attached with the vertical direction as the longitudinal direction, and may be attached with the horizontal direction X or an oblique direction as the longitudinal direction. Furthermore, the door 60 is not limited to being opened and closed by swinging, and may be opened and closed by sliding along the front side plate 52, for example.

The front side plate 52 is provided with a biasing spring 63 made of a torsion coil spring, which is an example of a biasing means that biases the door 60 from the open position toward the closed position. By providing the biasing spring 63, the door 60 is automatically returned to the closed position when there is no need for the opening 62 to be formed. When attaching or detaching the first detection unit 41, the user opens the door 60 against the biasing spring 63. Even if the user forgets to close the door 60 after attaching or detaching the first detection unit 41, it closes automatically, so the first detection unit 41 can be blocked by the door 60.

As shown in FIG. 4, the bottom surface 60a of the door 60 is positioned so as to be on the same plane (on plane S1 in FIG. 4) as the bottom surface 52a of the front plate 52 of the frame 51 of the drum cartridge 50 and the bottom surface (not shown) of the rear plate 53. Therefore, when the drum cartridge 50 is removed from the device body 1a and placed on a flat surface such as a workbench, the frame 51 and the door 60 come into contact with the flat surface. This allows the door 60 to function as legs for the drum cartridge 50, and allows the drum cartridge 50 to maintain a stable position so that it does not fall over when placed.

As described above, the drum cartridge 50 of this embodiment has a door 60 that can be opened and closed between a closed position where at least a portion of the door 60 overlaps with the first detection unit 41 when viewed from the width direction W, and an open position where the door 60 is separated from the first detection unit 41. Therefore, when the door 60 is in the open position, the door 60 and the first detection unit 41 do not overlap when viewed from the width direction W, so the first detection unit 41 can be attached to and detached from the device main body 1a by passing through the opening 62. This makes it possible to eliminate the need to remove the drum cartridge 50 even after the drum cartridge 50 and the first detection unit 41 are attached to the device main body 1a, improving the ease of replacement of the first detection unit 41.

In addition, according to the drum cartridge 50 of this embodiment, the bottom surface 60a of the door 60, the bottom surface 52a of the front plate 52 of the frame body 51, and the bottom surface (not shown) of the rear plate 53 are arranged on the same plane S1. Therefore, when the drum cartridge 50 is placed on a flat surface, the door 60 functions as the legs of the drum cartridge 50, and the drum cartridge 50 placed on the flat surface can be stably maintained in a stable position so that it does not fall over. Moreover, when the drum cartridge 50 is placed on a flat surface, the door 60 is automatically positioned in the closed position by the biasing spring 63. Therefore, for example, even if the center of gravity of the drum cartridge 50 is on the cleaning device 6 side and the shape is such that it is likely to fall over toward the cleaning device 6, the door 60 can make it difficult for the drum cartridge 50 to fall over toward the cleaning device 6.

In the image forming device 1 of the present embodiment described above, the first detection unit 41 is applied as a unit that is detachable from the device main body 1a, but this is not limited to this, and detachable peripheral units and members of the drum cartridge 50 can be applied. Also, in the image forming device 1 of the present embodiment, the device main body 1a has the charging device 3 and developing device 5, but this is not limited to this, and the drum cartridge 50 may have the charging device 3 and developing device 5 as a process cartridge.

In addition, in the drum cartridge 50 of this embodiment, the bottom surface 60a of the door 60, the bottom surface 52a of the front plate 52 of the frame body 51, and the bottom surface (not shown) of the rear plate 53 are arranged on the same plane S1, but this is not limited to the above. For example, the bottom surface 60a of the door 60 may be located on the upper direction U side of the bottom surface 52a of the front plate 52 of the frame body 51 and the bottom surface (not shown) of the rear plate 53. In this case, when the drum cartridge 50 is placed on a flat surface, the door 60 will not come into contact with the flat surface.

Second Embodiment
Next, a second embodiment of the present invention will be described in detail with reference to Figures 6 to 8. This embodiment differs from the first embodiment in that a second detection unit 42 is used as a unit that is detachable from the device main body 1a. However, other configurations are the same as those of the first embodiment, so the same reference numerals are used and detailed description is omitted.

In this embodiment, as shown in Figures 6 to 8, the drum cartridge 150 of the black image forming unit PK has a frame 51 (see Figure 3), a large-diameter photosensitive drum 2 rotatably mounted on the frame 51, and a cleaning device 6 fixed to the frame 51. A positioning member 55 for supporting the rotation shaft of the large-diameter photosensitive drum 2 is provided on the side surface of the front plate 52 in the forward direction F. The front plate 52 is provided with a grip portion 56 that protrudes in the forward direction F to pull out the drum cartridge 150, and a door 160.

[door]
The configuration and operation of the door 160 of this embodiment will be described in detail below. The door 160 is provided on the front side plate 52 and is provided so as to be openable (movable) by swinging between a closed position (see FIGS. 6 and 7) which is a first position and an open position (see FIG. 8) which is a second position. That is, in a state in which the drum cartridge 150 and the second detection unit 42 are mounted, the door 160 is disposed upstream of the mounting direction (rear direction B) of the second detection unit 41. When viewed from the width direction W, the closed position of the door 160 is a position where at least a part of the door 160 overlaps with the second detection unit 42, and the open position of the door 160 is a position separated from the second detection unit 42. In this embodiment, the door 160 is disposed so that at least a part of the door 160 overlaps with the second region Ar2 (see FIG. 6) when viewed from the width direction W in the closed position. In addition, when viewed from the width direction W, the door 160 in the closed position is located outside the outer peripheral surface upstream of the primary transfer nip portion T1 in the rotation direction R1 of the large diameter photosensitive drum 2, and between the developing device 5 and the intermediate transfer belt 40.

The door 160 is pivotally mounted on the front plate 52 by a rotating shaft 161 with the vertical direction as the center of rotation. As shown in FIG. 6, the rotating shaft 161 is mounted on the left side L side of the center of rotation C of the large diameter photosensitive drum 2 and on the right side R side of the developing device 5 as viewed from the width direction W. When the door 160 is pivoted forward in the F direction and positioned in the open position as shown in FIG. 8, an opening 162 is formed in the lower part of the front plate 52 in the left direction L. At this time, the door 160 and the second detection unit 42 do not overlap as viewed from the width direction W, so the second detection unit 42 can be attached to and detached from the device main body 1a by passing through the opening 162. In this way, the opening 162 is formed by opening the door 160, and the second detection unit 42 can be attached and detached without removing the drum cartridge 150.

When the door 160 is swung toward the rear direction B and positioned in the closed position as shown in Figs. 6 and 7, the opening 162 (see Fig. 8) is closed. At this time, the door 160 and the second detection unit 42 overlap when viewed from the width direction W, so the second detection unit 42 cannot be attached or detached. When the second detection unit 42 is attached, the door 160 is positioned in the closed position, which prevents the second detection unit 42 from being removed by mistake and suppresses the intrusion of light and dust into the second detection unit 42.

In this embodiment, the door 160 opens in the forward direction F, preventing the door 160 from interfering with the attached second detection unit 42, and shortening the distance between the front side panel 52 and the second detection unit 42 makes it possible to reduce the size of the drum cartridge 150.

The front side plate 52 is provided with a biasing spring 163 made of a torsion coil spring, which is an example of a biasing means for biasing the door 160 from the open position toward the closed position. By providing the biasing spring 163, the door 160 is automatically returned to the closed position when there is no need for the opening 162 to be formed. When attaching or detaching the second detection unit 42, the user opens the door 160 against the biasing spring 163. Even if the user forgets to close the door 160 after attaching or detaching the second detection unit 42, it closes automatically, so the second detection unit 42 can be blocked by the door 160.

As shown in FIG. 6, the bottom surface 160a of the door 160 is positioned so as to be on the same plane (on plane S1 in FIG. 6) as the bottom surface 52a of the front panel 52 of the frame 51 of the drum cartridge 150 and the bottom surface (not shown) of the rear panel 53 (see FIG. 3). Therefore, when the drum cartridge 150 is removed from the device main body 1a and placed on a flat surface such as a workbench, the frame 51 and the door 160 come into contact with the flat surface. This allows the door 160 to function as legs for the drum cartridge 150, and allows the drum cartridge 150 to maintain a stable posture so that it does not fall over when placed.

As described above, the drum cartridge 150 of this embodiment has a door 160 that can be opened and closed between a closed position where at least a portion of the door 160 overlaps with the second detection unit 42 when viewed from the width direction W, and an open position where the door 160 is separated from the second detection unit 42. Therefore, when the door 160 is in the open position, the door 160 and the second detection unit 42 do not overlap when viewed from the width direction W, so the second detection unit 42 can be attached to and detached from the device main body 1a by passing through the opening 162. This makes it possible to improve the workability when replacing the second detection unit 42, without the need to remove the drum cartridge 150, even after the drum cartridge 150 and the second detection unit 42 are attached to the device main body 1a.

In the image forming apparatus 1 of the present embodiment described above, the second detection unit 42 is applied as a unit that can be attached to the device main body 1a, and the door 160 is provided on the drum cartridge 150, but this is not limited to the above. For example, both the first detection unit 41 and the second detection unit 42 may be applied as units that can be attached to the device main body 1a. In this case, the drum cartridge is provided with both a door 60 (see FIG. 4) that allows the first detection unit 41 to be attached and detached, and a door 160 (see FIG. 6) that allows the second detection unit 42 to be attached and detached.

In the drum cartridges 50, 150 of the first and second embodiments described above, the door 60, 160 is provided to allow the first detection unit 41 or the second detection unit 42 provided near the primary transfer nip T1 to be attached and detached, but this is not limited to the above. The drum cartridge may be provided with a door that allows the unit provided near the drum cartridge 50, 150 to be attached and detached at a position other than the vicinity of the primary transfer nip T1.

1...image forming apparatus, 1a...apparatus main body, 2...large diameter photosensitive drum (image carrier), 3...charging device (charging means), 4...exposure device (exposure means), 5...developing device, 6...cleaning device (cleaning means), 8...primary transfer roller (transfer means), 40...intermediate transfer belt (intermediate transfer body), 41...first detection unit (unit, first concentration detection unit), 42...second detection unit (unit, second concentration detection unit), 50, 150...drum cartridge (cartridge), 51...frame (housing), 52a...bottom surface, 60, 160...door, 60a, 160a...bottom surface, 62, 162...urging spring (urging means), Ar1...first region, Ar2...second region, B...rear direction (mounting direction), T1...primary transfer nip portion (transfer nip portion), W...width direction (rotation axis direction).

Claims (8)

A device body,
a cartridge having an image carrier rotatable about a rotation axis and detachably provided in the main body of the apparatus along the rotation axis of the image carrier ;
a unit that is detachably provided in the apparatus main body along a rotation axis direction of the image carrier,
The cartridge has a door,
the door is movable between a first position where at least a part of the door overlaps with the unit when viewed from a line of sight along the rotation axis direction, on the upstream side of the installation direction of the unit when the unit is installed in the device body, and a second position where the door forms an opening through which the unit can pass when it is installed or removed along the rotation axis direction .
1. An image forming apparatus comprising: The door is disposed so that a bottom surface thereof is flush with a bottom surface of the housing of the cartridge.
2. The image forming apparatus according to claim 1, a biasing means for biasing the door from the second position toward the first position;
3. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. the device main body includes an intermediate transfer body that rotates in contact with the image carrier and forms a transfer nip between the intermediate transfer body and the image carrier, and a transfer unit that transfers a toner image formed on the image carrier to the intermediate transfer body;
the cartridge has a cleaning unit that cleans off residual toner adhering to the image carrier after the toner image formed on the image carrier is transferred to the intermediate transfer body,
the unit is disposed in a first area at least a part of which is surrounded by the image carrier, the intermediate transfer body, and the cleaning means;
The door is disposed so that at least a portion of the door overlaps with the first region when viewed from the rotation axis direction in the first position.
4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. the unit is a first concentration detection unit that detects a toner concentration on a surface of the intermediate transfer body;
5. The image forming apparatus according to claim 4. the device main body includes a developing device that develops an electrostatic latent image formed on the image carrier into a toner image, an intermediate transfer body that rotates in contact with the image carrier and forms a transfer nip between the image carrier and the intermediate transfer body, and a transfer means that transfers the toner image formed on the image carrier to the intermediate transfer body;
the unit is disposed in a second area at least a part of which is surrounded by the image carrier, the intermediate transfer body, and the developing device;
The door is disposed at the first position so as to overlap at least a portion of the door with the second region when viewed from the rotation axis direction.
4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. the unit is a second concentration detection unit that detects a toner concentration on a surface of the image carrier;
7. The image forming apparatus according to claim 6, A cartridge has an image carrier that is rotatable around a rotation axis , and is detachably provided in a main body of an apparatus along a rotation axis of the image carrier ,
a door that is movable between a first position where at least a part of the door overlaps with the unit when viewed from a line of sight along the rotation axis direction, and a second position that is separated from the unit when viewed from a line of sight along the rotation axis direction, on the upstream side of the mounting direction of the unit that is detachably mounted to the device body along the rotation axis direction of the image carrier;
A cartridge characterized by:

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