Patent Application
20240427279
The present disclosure relates to electrophotographic image forming apparatuses such as copying machines and printers.
With an image forming apparatus using an electrophotographic process, a toner image formed on the surface of a photosensitive drum as an image bearing member is transferred to a recording medium by a transfer member and then fixed to the recording medium by a fixing unit.
Japanese Patent Application Laid-Open No. 2001-183905 discusses an image forming apparatus using a cleaner-less method (simultaneous development and cleaning) in which a transfer residual toner remaining on a photosensitive drum is collected by a development device for reuse.
The apparatus main body of an image forming apparatus may be provided with an opening for releasing heat and steam generated in a fixing unit out of the apparatus main body. Preferably, if a foreign substance such as dust enters the apparatus main body from an opening of the apparatus main body, the foreign substance is prevented from adhering to the photosensitive drum. In particular, an image forming apparatus using the cleaner-less method as discussed in Japanese Patent Application Laid-Open No. 2001-183905 includes no cleaning unit for cleaning a residual toner on the photosensitive drum. Therefore, it is more preferable to prevent foreign substances from adhering to the photosensitive drum.
The present disclosure is directed to preventing foreign substances from adhering to a photosensitive drum.
An aspect of the present according to the present application will be described below.
According to an aspect of the present disclosure, an image forming apparatus for forming an image on a recording medium, the image forming apparatus includes an apparatus main body including a discharge portion and a wall disposed on an opposite side to the discharge portion with respect to a horizontal direction, wherein the discharge portion includes a first opening for discharging the recording medium, and the wall includes a second opening, a photosensitive drum stored in the apparatus main body, wherein the photosensitive drum is rotatable and disposed below the first opening and the second opening with respect to a vertical direction, an exposed surface stored in the apparatus main body, wherein the exposed surface is exposed toward a first communication path communicating with the first opening and the second opening and disposed below the first communication path, a plurality of ribs arranged along a rotational axis direction of the photosensitive drum, wherein the plurality of ribs projects from the exposed surface toward the first communication path, and each of the plurality of ribs extends in a direction intersecting with the rotational axis direction, and a receiving surface projecting from the exposed surface toward the first communication path, wherein the receiving surface is upwardly oriented with respect to the vertical direction and faces the first communication path, and the receiving surface extends along the rotational axis direction to connect with the plurality of ribs and is disposed to be positioned above the photosensitive drum with respect to the vertical direction, and wherein the receiving surface is inclined relative to the vertical direction and the horizontal direction so that a leading end of the receiving surface is disposed above a root of the receiving surface connecting with the exposed surface.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Exemplary embodiments of the present disclosure will be described as illustrative in detail below with reference to the accompanying drawings. However, sizes, materials, shapes, and relative arrangements of components according to the following exemplary embodiments are to be modified as required depending on the configuration of an apparatus according to the present disclosure and other various conditions. Therefore, unless otherwise specifically described, the scope of the present disclosure is not limited to the following exemplary embodiments.
An overall configuration of an image forming apparatus 100 will be described below with reference to
In the following descriptions, the vertical direction in a state where the image forming apparatus 100 is disposed on a horizontal surface is referred to as the Z direction. The Z direction is opposite to the gravity direction. The height direction of the image forming apparatus 100 is a direction parallel to the Z direction and opposite to the gravity direction. The direction perpendicularly intersecting with the Z direction, parallel to the rotational axis direction (main scanning direction or longitudinal direction) of the photosensitive drum 1 is referred to as the X direction. The direction perpendicularly intersecting with the X and the Z directions is referred to as the Y direction. The X and the Y directions are parallel to the horizontal direction. For convenience, the positive side in the X direction is referred to as the right-hand side, and the negative side in the X direction is referred to as the left-hand side; the positive side in the Y direction is referred to as the front side, and the negative side in the Y direction is referred to as the rear side; and the positive side in the Z direction is referred to as the upper side, and the negative side in the Z direction is referred to as the lower side.
The image forming apparatus 100 forms an image on the recording medium (sheet) P. The image forming apparatus 100 according to the present exemplary embodiment is a monochromatic laser-beam printer employing the cleaner-less method.
The image forming apparatus 100 includes an apparatus main body 100a. The apparatus main body 100a stores an image forming unit IM, an exposure device 3, a fixing unit 9, a two-sided printing guide (opposed member) 11, and a transfer guide (opening/closing member) 13. More specifically, the apparatus main body 100a includes a housing 100c, and the door 12 openable and closable relative to the housing 100c. The image forming unit IM, the exposure device 3, the fixing unit 9, the two-sided printing guide 11, and the transfer guide 13 are stored in the housing 100c. The apparatus main body 100a includes a control unit (controller) for performing an image forming operation based on image information received from an external apparatus.
The apparatus main body 100a includes a discharge portion 14 having a first opening 14a for discharging the recording medium P, and a wall 16a having a second opening 16 disposed on the opposite side to the discharge portion 14 in the horizontal direction. The wall 16a having the second opening 16 is a part of the door 12. The discharge portion 14 included in the housing 100c includes a discharging roller pair 14b.
The image forming unit IM includes a cylindrical electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 1 as an image bearing member, a charging roller 2 as a charge member, and a development device 4 as a developing unit. The photosensitive drum 1 is rotatable around the rotational axis. The rotational axis direction of the photosensitive drum 1 is parallel to the X direction.
A first communication path CP1 communicating with the first opening 14a and the second opening 16 is formed in the apparatus main body 100a. The photosensitive drum 1 is stored in the apparatus main body 100a and disposed below the first opening 14a, the second opening 16, and the first communication path CP1 in the Z direction.
In addition to the charging roller 2 and the development device 4, the exposure device 3 as an exposure unit, a transfer roller 5 as a transfer unit, and a pre-exposure device 6 are disposed around the photosensitive drum 1. The exposure device 3, the transfer roller 5, and the pre-exposure device 6 can be referred to as a part of the image forming unit IM.
The control unit starts the image forming operation based on the image information from the external apparatus. When the image forming operation is started, the photosensitive drum 1 rotates in the direction of the arrow R1, as illustrated in
The surface of the photosensitive drum 1 is charged to a predetermined potential with a predetermined polarity (negative polarity in the present exemplary embodiment) by the charging roller 2 in contact with the photosensitive drum 1. The surface of the charged photosensitive drum 1 is exposed according to the image information by the exposure device 3. Thus, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 1. The electrostatic latent image is developed at the developing position by the development device 4 to be visualized as a toner image.
The charging roller 2 has an elastic layer made of a conductive elastic member, having a surface roughness Ra of 1.5 to 2.5 μm. The charging roller 2 comes into contact with the surface of the photosensitive drum 1 with a predetermined contact pressure. The position where the charging roller 2 and the photosensitive drum 1 come into contact with each other is referred to as a charging portion. The charging roller 2 is driven by a drive mechanism (not illustrated) so that the circumferential speed of the charging roller 2 becomes 105% of that of the photosensitive drum 1. The shaft of the charging roller 2 is applied with a predetermined direct-current (DC) voltage by a charging voltage power source. According to the present exemplary embodiment, the shaft of the charging roller 2 is applied with a −1,350 VDC voltage as a charging voltage. The surface of the photosensitive drum 1 charged by the charging roller 2 has a predetermined potential (dark portion potential) of −780 V.
The exposure device 3 as a laser scanner device irradiates the photosensitive drum 1 with a laser beam based on the image information to form an electrostatic latent image on the surface of the photosensitive drum 1. According to the present exemplary embodiment, portions on the surface of the photosensitive drum 1 exposed by the exposure device 3 have a predetermined potential (light portion potential) of −100 V. According to the present exemplary embodiment, the surface of the photosensitive drum 1 having the light portion potential is supplied with a toner from the development device 4, and the surface of the photosensitive drum 1 having the dark portion potential is not supplied with a toner from the development device 4.
The development device 4 includes a developing roller 41 as a developer bearing member, a toner supply roller 42 as a developer supply unit, a developer storage chamber 43 for storing a toner, and a development blade 44 as a layer regulation member. The development device 4 includes toner conveyance members for conveying the toner stored in the developer storage chamber 43 to the toner supply roller 42. The toner supplied from the developer storage chamber 43 is supplied to the developing roller 41 by the toner supply roller 42. The development blade 44 is in contact with the developing roller 41. When the developing roller 41 rotates, the toner supplied to the developing roller 41 passes through the contact portion between the development blade 44 and the developing roller 41. As a result, the toner carried by the developing roller 41 is charged to a predetermined polarity (normal charging property), and a toner layer with a predetermined thickness is formed on the surface of developing roller 41.
The toner used is a nonmagnetic one-component toner having a negative polarity manufactured with the suspension polymerization method. The toner has a volume mean particle diameter of 6.0 μm and a negative normal charging polarity.
The developing roller 41 comes into contact with the surface of the photosensitive drum 1 with a predetermined contact pressure. The portion where the developing roller 41 and the photosensitive drum 1 come into contact with each other is referred to as a developing portion. The developing roller 41 is driven by a drive mechanism (not illustrated) so that the circumferential speed of the developing roller 41 becomes 140% of that of the photosensitive drum 1. The shaft of the developing roller 41 is applied with a −380 VDC voltage by a developing voltage power source. In the image forming process, the toner born on the developing roller 41 is developed to the portions on the photosensitive drum 1 having the light portion potential by an electrostatic force generated by a potential difference between the −380 V developing voltage and the −100 V light portion potential of the photosensitive drum 1.
The region on the surface of the photosensitive drum 1 where a toner can be supplied from the developing roller 41 can be referred to as an image forming region on the photosensitive drum 1. The image forming region on the photosensitive drum 1 may be a region that can be exposed by the exposure device 3 or a region corresponding to a toner coat region on the surface of the developing roller 41 coated by the toner.
The transfer roller 5 facing the photosensitive drum 1 comes into contact with the surface of the photosensitive drum 1 with a predetermined contact pressure. Thus, a transfer portion is formed between the transfer roller 5 and the photosensitive drum 1. When the shaft of the transfer roller 5 is applied with a predetermined voltage by a transfer voltage power source at a predetermined timing, the toner image formed on the surface of the photosensitive drum 1 is transferred onto the recording medium P at the transfer portion.
The pre-exposure device 6 exposes the surface of the photosensitive drum 1 having passed the transfer portion but not having reached the charging portion. This resolves uneven surface potentials of the photosensitive drum 1. The toner not having been transferred onto the recording medium P and remaining on the photosensitive drum 1 passes through the charging portion and then is collected by the developing roller 41.
The image forming apparatus 100 includes a tray 10 and a sheet feeding unit 7 as recording medium storage units (sheet storage units) for storing sheets of the recording medium P at the lower portion. The sheet feeding unit 7 includes a pickup roller 7a, a feed roller 7b, and a separation roller 7c.
The pickup roller 7a rotates in contact with the top sheet of the recording medium P stacked on the tray 10 to send the top sheet of the recording medium P from the tray 10. The recording medium P sent out from the tray 10 is further conveyed with each sheet separated at a nip portion (separation nip) between the feed roller 7b and the separation roller 7c.
The apparatus main body 100a includes a conveyance unit 8 including a conveyance roller 8a, a first driven roller 8b, and a second driven roller 8c. The conveyance roller 8a is driven by a motor, and the first driven roller 8b and the second driven roller 8c are driven by the conveyance roller 8a. The recording medium P having passed through the separation nip is conveyed toward the transfer portion by the conveyance roller 8a and the first driven roller 8b in contact with the conveyance roller 8a.
The recording medium P stored in the tray 10 is conveyed to the transfer portion by the sheet feeding unit 7 and the conveyance roller 8 in synchronization with the timing when the toner image formed on the photosensitive drum 1 reaches the transfer portion. The toner image formed on the photosensitive drum 1 is transferred onto the recording medium P by the transfer roller 5 applied with a predetermined transfer voltage by the transfer voltage power source.
The fixing unit 9 configured to heat the recording medium P is disposed above the photosensitive drum 1. The fixing unit 9 includes a heating roller with a built-in heater, and a pressure roller biased toward the heating roller with a predetermined pressure. A conveyance path SP1 is formed downstream of the transfer portion and upstream of the fixing unit 9 in the conveyance direction of the recording medium P. After passing through the transfer portion, the recording medium P conveyed from the photosensitive drum 1 toward the fixing unit 9 passes through the conveyance path SP1.
A second communication path CP2 is formed above the photosensitive drum 1 and below the first communication path CP1. The second communication path CP2 communicates with the conveyance path SP1 and the first communication path CP1.
When the recording medium P conveyed to the fixing unit 9 is heated and pressurized by the fixing unit 9, the toner image transferred onto the recording medium P is fixed to the recording medium P.
The recording medium P with the toner image fixed thereto is discharged out of the apparatus main body 100a from the first opening 14a. The apparatus main body 100a is provided with a sheet discharge tray 15 for stacking sheets of the recording medium P. The recording medium P discharged from the first opening 14a is stacked on the sheet discharge tray 15.
When the recording medium P is heated, steam may be generated from the recording medium P. The steam generated from the recording medium P is discharged out of the apparatus main body 100a through the second opening (exhaust vent) 16. According to the present exemplary embodiment, the apparatus main body 100a (housing 100c) is provided with an upper opening 100d above the first communication path CP1. The upper opening 100d includes a plurality of holes, and steam is discharged out of the apparatus main body 100a through the upper opening 100d.
According to the present exemplary embodiment, the image forming apparatus 100 can perform one-sided printing for forming an image on one side of the recording medium P and two-sided printing for forming an image on both sides of the recording medium P.
When one-sided printing is performed, the recording medium P is conveyed in the P1 direction by the discharging roller pair 14b and then discharged onto the sheet discharge tray 15, as illustrated in
The recording medium P conveyed in the P2 direction passes through the two-sided conveyance path SP2 and then is conveyed to a nip portion between the first driven roller 8b and the conveyance roller 8a by the second driven roller 8c and the conveyance roller 8a. Then, the recording medium P with a toner image formed on the back surface at the transfer portion passes through the fixing unit 9 and then is discharged onto the sheet discharge tray 15.
According to the present exemplary embodiment, the first communication path CP1 is a part of the two-sided conveyance path SP2. The two-sided printing guide 11 and the transfer guide 13 function as guide members for guiding the recording medium P passing through the two-sided conveyance path P2.
The image forming operation on the recording medium P reduces the amount of toner in the development device 4. The image forming apparatus 100 according to the present exemplary embodiment can supply toner from a replenishment container TP attachable to and detachable from the image forming apparatus 100, to the development device 4. As illustrated in
According to the present exemplary embodiment, the sheet discharge tray 15 functions as a cover for openably and closably covering the replenishment receiving member 100R. The sheet discharge tray 15 is movable between a covering position for covering the replenishment receiving member 100R and a replenishing position for exposing the replenishment receiving member 100R. The sheet discharge tray 15 is rotatable to the housing 100c around a rotation center 15a. When the recording medium P discharged from the first opening 14a is stacked on the sheet discharge tray 15, the sheet discharge tray 15 is positioned at the covering position. When sheet discharge tray 15 moves from the covering position to the replenishing position, the sheet discharge tray 15 moves in the direction to approach the first opening 14a. When the sheet discharge tray 15 is at the replenishing position, the first opening 14a is covered by the sheet discharge tray 15 and therefore the discharge of the recording medium P from the first opening 14a and the image forming operation on the recording medium P are limited.
If the recording medium P jams, i.e., if a jam occurs in the image forming apparatus 100, the user performs what is called a jam clearance to take out the recording medium P from the image forming apparatus 100. Therefore, the door 12 and the transfer guide 13 of the image forming apparatus 100 according to the present exemplary embodiment are configured to be openable and closable. The door 12 is rotatable around a rotation center 121, and the transfer guide 13 is rotatable around a rotation center 131 (see
The transfer guide 13 is an opening/closing member movable between a closed position for covering the photosensitive drum 1 and an open position for exposing the photosensitive drum 1. In a state where the transfer guide 13 is at the closed position, the upper end of the transfer guide 13 is positioned above the photosensitive drum 1 with respect to the vertical direction. When the transfer guide 13 supporting the transfer roller 5 is at the closed position, the transfer roller 5 is in contact with the photosensitive drum 1. When the transfer guide 13 is at the open position, the transfer roller 5 is separated from the photosensitive drum 1. The transfer guide 13 is biased from the open position toward the closed position by a spring (not illustrated). The transfer guide 13 may be opened and closed in association with the open/close operation of the door 12.
If the recording medium P jams between the conveyance unit 8 and the fixing unit 9, the user opens the door 12 and moves the transfer guide 13 to the open position, as illustrated in
After completion of the jam clearance, when the transfer guide 13 is moved to the closed position and the door 12 is closed, the image forming apparatus 100 becomes ready to restart the image forming operation.
<Invasion of Foreign substances Such as Dust>
The invasion of foreign substances such as dust into the second opening 16 and the image forming apparatus 100 will be described below with reference to
As described above, the apparatus main body 100a includes the wall 16a having the second opening 16, disposed on the opposite side to the discharge portion 14 in the horizontal direction (see
The second opening 16 is positioned above the photosensitive drum 1 and the fixing unit 9 (more specifically, the fixing nip) with respect to the vertical direction. The range where the image forming region on the photosensitive drum 1 exists overlaps with the range where the second opening 16 exists with respect to the rotational axis direction of the photosensitive drum 1.
The first communication path CP1 communicating with the first opening 14a and the second opening 16 serves as an air path. More specifically, air may flow from the first opening 14a to the second opening 16, as illustrated by the arrow A1 in
The two-sided printing guide 11 is positioned below the first communication path CP1 with respect to the vertical direction and faces the first communication path CP1. When viewed in the rotational axis direction of the photosensitive drum 1, the two-sided printing guide 11 is disposed between the first opening 14a and the second opening 16 in the horizontal direction. The two-sided printing guide 11 is disposed above the photosensitive drum 1 with respect to the vertical direction. When viewed in the rotational axis direction of the photosensitive drum 1, the photosensitive drum 1 is disposed between the first opening 14a and the door 12, i.e., between the first opening 14a and the second opening 16 in the horizontal direction.
If a foreign substance D1 such as dust exists a lot in the air and the flow of air passing through the first communication path CP1 is strong, the foreign substance D1 such as dust may enter the image forming apparatus 100 together with the air passing through the first communication path CP1 and then accumulate on the two-sided printing guide 11. The foreign substance D1 in this case may include the foreign substance D1 entering the image forming apparatus 100 together with the air flowing in the direction of the arrow A1 in
For example, a vibration produced when the door 12 or the transfer guide 13 is closed may cause the foreign substance D1 accumulating on the two-sided printing guide 11 to drop on the negative side of the Z direction from the two-sided printing guide 11. According to the present exemplary embodiment, the transfer guide 13 is biased by a spring, and thus, the vibration generated when the transfer guide 13 is closed tends to be larger than the vibration generated when the door 12 is closed.
In the configuration where the photosensitive drum 1 is disposed below the two-sided printing guide 11, the foreign substance D1 may drop to the vicinity of the photosensitive drum 1.
According to the present exemplary embodiment, for example, in a state where the transfer guide 13 positioned below the two-sided printing guide 11 is at the closed position, the second communication path CP2 is formed between the transfer guide 13 and the two-sided printing guide 11, as illustrated in
The photosensitive drum 1 is exposed when the transfer guide 13 is at the open position. While the transfer guide 13 is being moved from the open position to the closed position, the foreign substance D1 may drop to the vicinity of the photosensitive drum 1.
It has been necessary to replace the photosensitive drum 1 if the image forming apparatus 100 is used in an environment where the foreign substance D1 such as dust exists a lot in the air, the flow air passing through the first communication path CP1 is strong, and toner adhesion is caused by the foreign substance D1 adhering to the photosensitive drum 1, as described above.
A configuration for preventing the adhesion of the foreign substance D1 to the photosensitive drum 1 will be described below with reference to
The two-sided printing guide 11 according to the present exemplary embodiment includes receiving ribs (receiving projections) 11b1 and 11b2.
The receiving ribs 11b1 and 11b2 catch the foreign substance D1 to prevent it from adhering to the photosensitive drum 1. The shape of the two-sided printing guide 11 will be described in more detail below.
The two-sided printing guide 11 stored in the apparatus main body 100A includes an exposed surface 11c exposed toward the first communication path CP1. The exposed surface 11c is disposed below the first communication path CP1. A state where the exposed surface 11c is exposed toward the first communication path CP1 means that the exposed surface 11c is visible from any position in the first communication path CP1. The exposed surface 11c can be said to be an opposed surface facing the first communication path CP1.
As illustrated in
When viewed in the rotational axis direction of the photosensitive drum 1, the apex 11c0 is positioned between the first opening 14a and the second opening 16 in the horizontal direction. As understood from
When viewed in the rotational axis direction of the photosensitive drum 1, the first surface 11cl is closer to the second opening 16 than the apex 11c0 is in the horizontal direction. More specifically, the distance between the first surface 11cl and the second opening 16 is shorter than the distance between the apex 11c0 and the second opening 16 in the horizontal direction. When viewed in the rotational axis direction of the photosensitive drum 1, the second surface 11c2 is closer to the first opening 14a than the apex 11c0 is in the horizontal direction. More specifically, the distance between the second surface 11c2 and the first opening 14a is shorter than the distance between the apex 11c0 and the first opening 14a in the horizontal direction.
The first surface 11cl and the second surface 11c2 are downwardly inclined from the apex 11c0. In other words, the first surface 11cl and the second surface 11c2 downwardly extend in the vertical direction as separating from the apex 11c0 in the horizontal direction. According to the present exemplary embodiment, the first surface 11c1 and the second surface 11c2 each include a curved portion.
As illustrated in
Each of the plurality of first rib 11a1 and each of the plurality of second rib 11a2 extend in a direction intersecting with the rotational axis direction of the photosensitive drum 1. According to the present exemplary embodiment, the first communication path CP1 functions as a conveyance path where the recording medium P is passable. More specifically, the first communication path CP1 is a part of the two-sided conveyance path SP2. The plurality of first ribs 11a1 and the plurality of second ribs 11a2 extend along the conveyance direction of the recording medium P passing through the first communication path CP1, and have a function of guiding the recording medium P passing through the first communication path CP1.
As illustrated in
According to the present exemplary embodiment, the two-sided printing guide 11 has the plurality of receiving ribs 11b1 and the plurality of receiving ribs 11b2. The shapes of the plurality of receiving ribs 11b1 are substantially the same, and the shapes of the plurality of receiving ribs 11b2 are also substantially the same. One or a plurality of receiving ribs 11b1 and one or a plurality of receiving ribs 11b2 may be provided. The two-sided printing guide 11 may have either one of the ribs 11b1 and 11b2.
The top faces of the receiving ribs 11b1 and 11b2 project from the exposed surface 11c toward the first communication path CP1 and face the first communication path CP1. At least a part of the top faces of the receiving ribs 11b1 and 11b2 are positioned immediately below the first communication path CP1. Therefore, the top faces of the receiving ribs 11b1 and 11b2 can receive the foreign substance D1 downwardly dropping from the first communication path CP1.
The top faces of the receiving ribs 11b1 and 11b2 extend along the rotational axis direction of the photosensitive drum 1 to connect with the plurality of second ribs 11a2. This prevents the foreign substance D1 from dropping from the top faces of the receiving ribs 11b1 and 11b2.
The top faces of the receiving ribs 11b1 and 11b2 are positioned above the photosensitive drum 1 with respect to the vertical direction. The top faces of the receiving ribs 11b1 and 11b2 are positioned above the second communication path CP2 with respect to the vertical direction.
As understood from
Although, according to the present exemplary embodiment, the receiving ribs 11b1 and 11b2 are disposed at other than the longitudinal central part of the two-sided printing guide 11, these may be provided in a region including the longitudinal central part. Even if the receiving ribs 11b1 and 11b2 are disposed not to connect with the second ribs 11a2, the foreign substance D1 can be prevented from dropping.
The top faces of the receiving ribs 11b1 and 11b2, the exposed surface 11c, and the plurality of second ribs 11a2 form spaces for storing the foreign substance D1, thus preventing the foreign substance D1 from dropping and adhering to the photosensitive drum 1.
As illustrated in
Although the top faces of the receiving ribs 11b1 and 11b2 may horizontally extend, preferably, the top faces upwardly extend in a direction intersecting with the horizontal and vertical directions. More specifically, the top faces of the receiving ribs 11b1 and 11b2 are preferably inclined relative to the vertical direction and the horizontal direction so that the leading ends of the top faces are positioned above the roots connecting with the exposed surface 11c.
When viewed in the rotational axis direction of the photosensitive drum 1, the first surface 11cl of the exposed surface 11c is positioned between the apex 11c0 and the leading ends of the top faces of the receiving ribs 11b1 and 11b2 in the horizontal direction. Thus, the foreign substance D1 dropping from the first surface 11cl is received by the top faces of the receiving ribs 11b1 and 11b2.
If the foreign substance D1 adheres to the photosensitive drum 1, the foreign substance D1 which may cause the toner adhesion illustrated in
According to the present exemplary embodiment, on the other hand, the second rib 11a2 functions as a guide rib for guiding the recording medium P. The receiving ribs 11b1 and 11b2 extend in the opposite direction of the conveyance direction of the recording medium P from the exposed surface 11c. The projecting height is made shorter than the projection length of the second rib 11a2 projecting from the exposed surface 11c. This prevents the top faces of the receiving ribs 11b1 and 11b2 from coming into contact with the recording medium P.
As illustrated in
Thus, even if the foreign substance D1 drops from the top faces of the receiving ribs 11b1 and 11b2, the foreign substance D1 is prevented from entering the second communication path CP2 and therefore becomes hard to drop to the vicinity of the photosensitive drum 1. The transfer guide 13 is provided with guide ribs for guiding the recording medium P passing through the two-sided conveyance path SP2. The back surface of the transfer guide 13 refers to the surface between the guide ribs of the transfer guide 13.
An effect of the two-sided printing guide 11 according to the present exemplary embodiment will be described below. We compared the adhesion of the foreign substance D1 to the photosensitive drum 1 between a configuration including the two-sided printing guide 11′ according to the comparative example illustrated in
Table 1 illustrates evaluation results of a configuration A including the two-sided printing guide 11 according to the present exemplary embodiment and the comparative example including the two-sided printing guide 11′.
Referring to Table 1, the two-sided printing guide 11 according to the present exemplary embodiment reduces the number of mineral powder particles to about a half of the number according to the comparative example, and provides an effect of preventing the foreign substance D1 on the two-sided printing guide 11 from adhering to the photosensitive drum 1.
According to the present exemplary embodiment, the receiving ribs 11b1 and 11b2, the exposed surface 11c, and the second rib 11a2 are integrally disposed on the two-sided printing guide 11. However, the receiving ribs 11b1 and 11b2, the exposed surface 11c, and the second rib 11a2 may be divided into a plurality of parts.
In addition to the receiving ribs 11b1 and 11b2 disposed on the two-sided printing guide 11, a transfer receiving member 13R (described below) may be disposed on the transfer guide 13. The transfer guide 13 having the transfer receiving member 13R enables preventing the foreign substance D1 dropping from the two-sided printing guide 11 from adhering to the photosensitive drum 1.
A configuration of the transfer guide 13 according to the present exemplary embodiment will be described below with reference to
According to the present exemplary embodiment, the transfer guide 13 includes a plurality of transfer receiving members 13R. The shapes of the plurality of transfer receiving members 13R are substantially the same.
As illustrated in
The transfer guide 13 further includes a plurality of side walls 13c. Each of the plurality of side walls 13c extends along a direction intersecting with the rotational axis direction of the photosensitive drum 1 and connects with the bottom wall 13a, the first side wall 13b, and the second side wall 13e. The plurality of side walls 13c face each other. One of the plurality of side walls 13c is referred to as a third side wall, and the other is referred to as a fourth side wall.
As illustrated in
The bottom wall 13a, the first side wall 13b, the second side wall 13e, and the plurality of side walls 13c are integrally formed on the transfer guide 13 to form the transfer receiving member 13R as a concave portion. More specifically, in a state where the transfer guide 13 is at the closed position, the first side wall 13b, the second side wall 13e, and the plurality of side walls 13c upwardly extend from the bottom wall 13a in the vertical direction. As a result, in a state where the transfer guide 13 is at the closed position, the transfer receiving member 13R as a concave portion is upwardly open with respect to the vertical direction. More specifically, the opening (entrance) of the transfer receiving member 13R is positioned above the bottom wall 13a.
In a state where the transfer guide 13 is at the closed position, the second side wall 13e is positioned between the first side wall 13b and the photosensitive drum 1 in the horizontal direction, and the height of the second side wall 13e is lower than the height of the first side wall 13b.
In a state where the transfer guide 13 is at the closed position, the transfer receiving member 13R is positioned below the first communication path CP1 and above the photosensitive drum 1 with respect to the vertical direction, and the bottom wall 13a faces the two-sided printing guide 11. In a state where the transfer guide 13 is at the closed position, the transfer receiving member 13R is positioned below the second communication path CP2 with respect to the vertical direction, and the bottom wall 13a faces the second communication path CP2.
As a result, the foreign substance D1 passing through the second communication path CP2 is stored in the transfer receiving member 13R, preventing the foreign substance D1 from adhering to the photosensitive drum 1. In a state where the transfer guide 13 is at the closed position, the transfer receiving member 13R is upwardly open with respect to the vertical direction. This prevents the foreign substance D1 received by the transfer receiving member 13R from moving to the photosensitive drum 1 when the transfer guide 13 is closed.
As illustrated in
The transfer receiving member 13R may be disposed below the receiving ribs 11b1 and 11b2 of the two-sided printing guide 11. For example, as illustrated in
The receiving ribs 11b1 and 11b2 are not disposed above the transfer receiving member 13R disposed at the center of the transfer guide 13 with respect to the rotational axis direction of the photosensitive drum 1. More specifically, the position of the transfer receiving member 13R may not overlap with the positions of the top faces of the receiving rib 11b1 and 11b2 with respect to the rotational axis direction of the photosensitive drum 1.
As illustrated in
The upper wall 13d prevents the foreign substance D1 from passing through the second communication path CP2 and adhering to the photosensitive drum 1. The position of the upper wall 13d may overlap with the positions of the top faces of the receiving ribs 11b1 and 11b2 with respect to the rotational axis direction of the photosensitive drum 1.
As illustrated in
According to the present exemplary embodiment, the upper wall 13d and the transfer receiving member 13R are closer to the upper end of the transfer guide 13 than to the rotation center 131 of the transfer guide 13. The upper wall 13d and the transfer receiving member 13R are closer to the first communication path CP1 than to the conveyance path SP1. Therefore, the foreign substance D1 can be received upstream of the second communication path CP2.
In addition to the two-sided printing guide 11 of which the evaluation results are illustrated in Table 1, the transfer guide 13 having the transfer receiving members 13R and the upper walls 13d was used to evaluate the adhesion of the foreign substance D1 to the photosensitive drum 1. In the present evaluation, 0.5 g of mineral powder simulating dust was used as in the evaluation of which the results are illustrated in Table 1.
Table 2 illustrates evaluation results of a configuration B including the two-sided printing guide 11 and the transfer guide 13 according to the present exemplary embodiment and the comparative example illustrated in
Referring to Table 2, the two-sided printing guide 11 and the transfer guide 13 according to the present exemplary embodiment reduce the number of mineral powder particles to about 60% of the number according to the comparative example, preventing the foreign substance D1 on the two-sided printing guide 11 from adhering to the photosensitive drum 1.
As described above, the present disclosure enables preventing the foreign substance D1 from adhering to the photosensitive drum 1. The receiving ribs 11b1 and 11b2 of the two-sided printing guide 11, the transfer receiving member 13R, and the upper wall 13d have a function of preventing the foreign substance D1 from adhering to the photosensitive drum 1. Therefore, if the image forming apparatus 100 is provided with at least any one of the receiving ribs 11b1 and 11b2, the transfer receiving member 13R, and the upper wall 13d, the foreign substance D1 can be prevented from adhering to the photosensitive drum 1. This means that the image forming apparatus 100 does not need to be provided with all of the receiving ribs 11b1 and 11b2, the transfer receiving member 13R, and the upper wall 13d.
The image forming apparatus 100 according to the present exemplary embodiment employs the cleaner-less method not using a cleaning member for cleaning the photosensitive drum 1. However, the present disclosure is also applicable to an image forming apparatus having a cleaning member for cleaning the photosensitive drum 1.
The image forming apparatus 100 according to the present exemplary embodiment uses a laser scanner unit as the exposure device 3. However, the present disclosure is also applicable to an image forming apparatus for exposing the photosensitive drum 1 by using light emitting diodes (LEDs).
The image forming apparatus 100 according to the present exemplary embodiment enables two-sided printing on the recording medium P. More specifically, the first communication path CP1 is a part of the two-sided conveyance path SP2. The present disclosure is also applicable to the image forming apparatus 100 that does not perform two-sided printing on the recording medium P. More specifically, the first communication path CP1 does not need to be a part of the two-sided conveyance path SP2, and the first rib 11al and the second rib 11a2 do not need to function as guide ribs for guiding the recording medium P.
Although the image forming apparatus 100 according to the present exemplary embodiment is a monochromatic printer, the present disclosure is also applicable to color printers.
The present disclosure enables preventing foreign substances from adhering to the photosensitive drum.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2023-103929, filed Jun. 26, 2023, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-103929 | Jun 2023 | JP | national |
