Patent Application
20240103403
The present disclosure relates to a developing device for developing an electrostatic image formed on an image carrier with developer containing toner and carrier, and to a method of agitating initial developer inside the developing device.
In a developing device discussed in Japanese Patent Application Laid-Open No. 2019-040054, a developer supply opening provided in a developer storage portion is sealed by a sealing member, and a winding shaft that is rotatable to wind up the sealing member and a developer agitation member are coupled through a driving system inside the developing device. In a configuration discussed in Japanese Patent Application Laid-Open No. 2019-040054, before the developing device is used, the sealing member can be manually removed by directly rotating the winding shaft with use of a tool in a state where a gear at an end part of the winding shaft is separated from the driving system inside the developing device.
There exists conventional developing devices having a sealed developer storage chamber in which developer inside the sealed developer storage chamber may be in a compaction state. Depending on transportation and a storage state of the conventional developing device before a sealing member is unsealed (at shipment), the developer may be in a tapping state where the developer is compressed on a downstream side in a conveyance/agitation screw conveyance direction before the developing device is used. In a case where initial startup (initialization operation for development driving) of the developing device is performed while the developing device is in the tapping state, load torque of a motor for rotating a screw conveying and agitating the developer is increased. If the load torque of the motor becomes a predetermined value or more, screw locking may occur to inhibit rotation of the screw in such conventional developing devices.
The present disclosure is directed to a technique for eliminating a tapping state of a developing device before a sealing member is unsealed (at shipment), with a simple configuration.
According to an aspect of the present disclosure, a developing device includes a developer carrier configured to carry developer containing toner and carrier for developing an electrostatic image formed on an image carrier, a first chamber configured to supply the developer to the developer carrier, a second chamber partitioned from the first chamber by a partition and configured to allow circulation of the developer between the second chamber and the first chamber, a first communication portion configured to permit the developer to communicate from the second chamber to the first chamber, a second communication portion configured to permit the developer to communicate from the first chamber to the second chamber, a first conveyance screw disposed in the first chamber and configured to convey the developer in a first direction from the first communication portion toward the second communication portion, a second conveyance screw disposed in the second chamber and configured to convey the developer in a second direction from the second communication portion toward the first communication portion, a pair of sealing members configured to seal the first communication portion and the second communication portion to store initial developer in the second chamber, and a drive transmission gear configured to transmit driving force for rotating the second conveyance screw to the second conveyance screw, wherein the drive transmission gear includes a fitting portion to which a tool to input the driving force for rotating the second conveyance screw to the drive transmission gear is fitted.
According to another aspect of the present disclosure, a method of agitating initial developer inside a developing device, the developing device including a developer carrier configured to carry developer containing toner and carrier for developing an electrostatic image formed on an image carrier, a first chamber configured to supply the developer to the developer carrier, a second chamber partitioned from the first chamber by a partition and configured to allow circulation of the developer between the second chamber and the first chamber, a first communication portion configured to permit the developer to communicate from the second chamber to the first chamber, a second communication portion configured to permit the developer to communicate from the first chamber to the second chamber, a first conveyance screw disposed in the first chamber and configured to convey the developer in a first direction from the first communication portion toward the second communication portion, a second conveyance screw disposed in the second chamber and configured to convey the developer in a second direction from the second communication portion toward the first communication portion, a pair of sealing members configured to seal the first communication portion and the second communication portion to store initial developer in the second chamber, and a drive transmission gear configured to transmit driving force for rotating the second conveyance screw to the second conveyance screw, includes inputting the driving force for rotating the second conveyance screw to the drive transmission gear by using a tool in a state where the first communication portion and the second communication portion are sealed by the pair of sealing members, and agitating the initial developer by rotation of the second conveyance screw by inputting the driving force for rotating the second conveyance screw to the drive transmission gear.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Some exemplary embodiments of the present disclosure are to be described in detail with reference to accompanying drawings. The present disclosure according to the claims is not limited to the exemplary embodiments, and all of combinations of features to be described in the exemplary embodiments are not necessarily essential for the present disclosure. The present disclosure can be implemented in various applications such as a printer, various kinds of printing machines, a copier, a facsimile (FAX), and a multifunctional peripheral.
A first exemplary embodiment is to be described.
In the image forming unit Sa, a yellow toner image is formed on a photosensitive drum 1a (image carrier), and is transferred to the intermediate transfer belt 7. In the image forming unit Sb, a magenta toner image is formed on a photosensitive drum 1b, and is transferred to the intermediate transfer belt 7. In the image forming units Sc and Sd, a cyan toner image and a black toner image are formed on photosensitive drums 1c and 1d, respectively, and are transferred to the intermediate transfer belt 7.
The intermediate transfer belt 7 is stretched on primary transfer rollers 5a, 5b, 5c, and 5d, a counter roller 8, a tension roller 17, and a stretching roller 18, and is driven by the counter roller 8 that also functions as a driving roller, thereby is rotated in a direction of an arrow R7. The toner images of four colors having been transferred to the intermediate transfer belt 7 are conveyed to a secondary transfer portion T2, and are secondarily transferred to a recording medium P that has been taken out from a recording medium cassette 10 and has been conveyed to the secondary transfer portion T2. The recording medium P is supplied to the secondary transfer portion T2 by a feeding conveyance device including a sheet feeding roller, a conveyance roller, and a registration roller (not illustrated).
The recording medium P to which the toner images have been transferred at the secondary transfer portion T2 is heated and pressurized by a fixing device 13 in which a pressurizing roller 15 is pressed to a fixing roller 14. After the toner images are fixed to a front surface of the recording medium P, the recording medium P is discharged out of the apparatus.
The image forming units Sa, Sb, Sc, and Sd have substantially the same configuration except that toner colors used in developing devices 100a, 100b, 100c, and 100d are different from one another. In the following, the image forming unit Sa is to be described, and the image forming units Sb, Sc, and Sd are to be described by replacing a suffix “a” attached to reference numerals of components of the image forming unit Sa with “b”, “c”, and “d”.
The image forming unit Sa includes a charging roller 2a, an exposure device 3a, the developing device 100a, the primary transfer roller 5a, and an auxiliary charging roller 6a that are arranged around the photosensitive drum 1a.
The photosensitive drum 1a includes a negatively-charged photosensitive layer on an outer peripheral surface of an aluminum cylinder, and rotates at a predetermined process speed in a direction of an arrow R1. The charging roller 2a uniformly charges a surface of the photosensitive drum 1a to a negative potential. The exposure device 3a performs scanning with a laser beam by using a rotary mirror, thereby writing an electrostatic image of an image on the charged surface of the photosensitive drum 1a. The developing device 100a develops the electrostatic image formed on the photosensitive drum 1a by using two-component developer containing toner and carrier, thereby forming the toner image on the photosensitive drum 1a.
The primary transfer roller 5a presses an inside surface of the intermediate transfer belt 7 to form a primary transfer portion T1a between the photosensitive drum 1a and the intermediate transfer belt 7. When a positive direct-current voltage is applied to the primary transfer roller 5a, the negative toner image carried by the photosensitive drum 1a is primarily transferred to the intermediate transfer belt 7. The auxiliary charging roller 6a negatively charges transfer residual toner that escapes from being transferred to the recording medium P and remains on the photosensitive drum 1a, and involves resultant toner in next development by the developing device 100a.
A belt cleaner 11 is in contact with the intermediate transfer belt 7 at a position corresponding to the tension roller 17 so that the transfer residual toner attached to the intermediate transfer belt 7 is removed.
As illustrated in
An inside of the developer container 101 is partitioned into a development chamber 101a and an agitation chamber 101b by a vertically-provided partition 103. The two-component developer in which non-magnetic toner, magnetic carrier, and a small amount of external additive are mixed is stored in the development chamber 101a and in the agitation chamber 101b (circulation path).
A magnet 102m that includes a plurality of magnetic poles on a surface of the magnet 102m and is unrotatably supported is disposed inside the development sleeve 102. The developer is carried on the surface of the development sleeve 102 in a state where the carrier as a magnetic material is constrained by a magnetic flux formed between adjacent magnetic poles of the magnet 102m, and the negatively-charged toner is electrostatically constrained on the surface of the positively-charged carrier to form a magnetic brush. A power supply 52 applies an oscillation voltage in which an alternating-current voltage is superimposed on a negative direct-current voltage, to move the negatively-charged toner carried by the magnetic brush to the electrostatic image of the photosensitive drum 1.
As illustrated in
The agitation chamber 101b and the development chamber 101a communicate with each other through openings 107a and 107b provided at respective end parts of the partition 103, thereby forming the circulation path of the developer. The developer is delivered from the agitation chamber 101b (second chamber) to the development chamber 101a (first chamber) through the opening 107a (first communication portion). On the other hand, the developer is delivered from the development chamber 101a (first chamber) to the agitation chamber 101b (second chamber) through the opening 107b (second communication portion). In other words, the opening 107a (first communication portion) permits the developer to communicate from the agitation chamber 101b (second chamber) to the development chamber 101a (first chamber). The opening 107b (second communication portion) permits the developer to communicate from the development chamber 101a (first chamber) to the agitation chamber 101b (second chamber).
In a process in which the developer circulates along the circulation path thus configured while being agitated, friction occurs between toner particles and carrier particles. As a result, the toner is negatively charged and the carrier is positively charged. After the developer is conveyed to a downstream side while being agitated by the agitation screw 104b inside the agitation chamber 101b, the developer flows into the development chamber 101a through the opening 107a of the partition 103. The developer is carried by the development sleeve 102 in a process of being conveyed to the downstream side by the development screw 104a inside the development chamber 101a.
The development screw 104a as an example of a first conveyance screw is rotatably attached in the development chamber 101a as an example of the first chamber. When the development screw 104a rotates, the two-component developer is conveyed from the upstream side toward the downstream side in the development chamber 101a as illustrated by an arrow B.
The agitation screw 104b as an example of a second conveyance screw is rotatably attached in the agitation chamber 101b as an example of the second chamber. When the agitation screw 104b rotates, the two-component developer is conveyed from the upstream side toward the downstream side in the agitation chamber 101b as illustrated by an arrow A.
A toner replenishing mechanism 105 is disposed above an upstream end of the agitation chamber 101b. The toner stored in a toner bottle (not illustrated) is conveyed to the toner replenishing mechanism 105 through a toner conveyance path (not illustrated), and is dropped and replenished into the agitation chamber 101b through a toner replenishing port 106. In the developing device 100, toner of the same type as the initial developer is used as replenishment toner.
A toner charge amount Q/M of the two-component developer is an important parameter for determining a density of a developed image. A weight ratio of the toner (toner density T/D) contained in the two-component developer and the toner charge amount Q/M have correlation.
The toner is charged by contact friction with the carrier. For this reason, the toner charge amount Q/M is increased as contact frequency of the toner with the carrier is increased. Thus, the toner charge amount Q/M of the two-component developer is increased as the toner density T/D is decreased, and the image density when an equivalent electrostatic image is developed is lowered. Accordingly, the toner density T/D of the developer circulating between the development chamber 101a and the agitation chamber 101b is constantly detected by a magnetic permeability sensor T. The toner amount replenished from the toner replenishing mechanism 105 is adjusted so that the toner density T/D becomes substantially constant.
As illustrated in
As illustrated in
The sealing sheet 51a is folded upward from a lower end side while sealing the opening 107a, and a front end of the sealing sheet 51a is fixed to a winding shaft 600. The sealing sheet 51b on an opposite side is similarly folded upward from a lower end side while sealing the opening 107b, and a front end of the sealing sheet 51b is fixed to the common winding shaft 600.
The winding shaft 600 as a sealing sheet unsealing mechanism is coupled to the development sleeve 102 by a gear train so as to receive rotation. Accordingly, along with rotation of the development sleeve 102, the sealing sheets 51a and 51b are wound around the winding shaft 600 to open the openings 107a and 107b, respectively.
The winding shaft 600 automatically tears off the sealing sheets 51a and 51b of the developing device 100 from the openings 107a and 107b without relying on a work by a user. The developing device 100 is started up to a usable state (initialization operation of developing device is completed) by circulating and spreading the developer inside the development chamber 101a and the agitation chamber 101b.
Rotation of the development screw 104a is transmitted by a gear train 160 on a side opposite to the side connected to the coupling 54, to integrally rotate the agitation screw 104b, the development screw 104a, and the winding shaft 600. The development sleeve 102, the development screw 104a, the agitation screw 104b, and the winding shaft 600 form one system of gear train by a gear train 160. When the development screw 104a rotates, an output gear 151 at an end part rotates. An idler gear 150 engaging with the output gear 151 rotates the winding shaft 600 through engagement of the gear 153 and the gear 154 coupled to the winding shaft 600. To secure torque necessary for the winding shaft 600 to tear off the sealing sheet 51a, the gears 153 and 154 are configured to be largely decelerated using a worm gear and a worm wheel.
On the other hand, an agitation screw gear 155 rotating the agitation screw 104b engages with the output gear 151.
These driving gear trains are formed by coupling in the same series, and all of the gears are rotationally driven when the coupling 54 rotates. The same series of gear trains indicates a drive transmission path in which a driving force is transmitted to each of the coupling 54 and the agitation screw 104b, the coupling 54 and the winding shaft 600, and the sheeve gear 171. A gear train branched from the gears in series is considered to be identical to a branching gear, and the gear trains directly engaging with one another are regarded as the same series irrespective of a gear train length after branching and the number of branches.
Operation of a driving mechanism of the developing device 100 is to be described with reference to
The developing device 100 is mounted on the image forming apparatus 200, or the developing device 100 is previously mounted inside the image forming apparatus 200 at shipment. Power is supplied to the driving motor 53 of a driving source M1 provided in the image forming apparatus 200 from a power supply of the image forming apparatus 200. Rotational driving force is transmitted to the development screw 104a through the coupling 54 attached to a shaft end part of the development screw 104a of the developing device 100. In normal rotation, the development screw 104a is rotated in a direction of an arrow 104R illustrated in
A bevel gear 150a is integrally provided at one end side of the idler gear 150 engaging with the output gear 151. A bevel gear 152 is integrally provided at one end side of the worm gear 153. The bevel gears 152 and 150a are disposed such that rotary axes thereof form 90 degrees, and engage with each other. As a result, the rotational force transmitted to the idler gear 150 is transmitted to the worm gear 153 through engagement of the bevel gears 152 and 150a. The worm wheel largely decelerated by the worm gear 153 and the worm wheel 154 rotates in an arrow direction. At this time, the worm gear 153 itself is urged in a direction of an arrow P illustrated in
The worm wheel 154 is coupled to the winding shaft 600 for the sealing sheet 51a so as to integrally rotate, and the winding shaft 600 rotates integrally with the worm wheel 154 in an arrow direction in
However, the developer inside the agitation chamber 101b may be in a compaction state (tapping state) where the developer is compressed on a downstream side in the conveyance direction by the agitation screw 104b before the developing device 100 is used, due to influence of logistics, storage, and the like of the developing device 100 before the sealing sheet 51a is unsealed (at shipment).
In a case where the developer inside the agitation chamber 101b is in the compaction state, resistance of the developer in the compaction state is applied at driving of the agitation screw 104b. In a case where initial startup (initialization operation for development driving) of the developing device 100 is performed while the developing device 100 is in the tapping state, load torque of the driving motor 53 for rotating the agitation screw 104b is increased. If the load toque of the driving motor 53 becomes a predetermined value or more, screw locking may occur to inhibit rotation of the agitation screw 104b.
The load detection unit 58 that detects a current amount of the driving motor 53 to estimate the torque is installed, and driving of the driving motor 53 is stopped when an overload occurs. In particular, in a case where the agitation screw 104b is driven before the sealing member 51 is unsealed as with the present configuration, the developer cannot move in a direction T illustrated in
A configuration for loosening operation before initialization operation for driving (development driving) of the developing device 100 according to a first exemplary embodiment is to be described with reference to
In the first exemplary embodiment, a loosening member 140 for loosening the developer is the agitation screw 104b, and a drive input member 141 for driving the loosening member 140 is the agitation screw gear 155.
The drive input member 141 includes an operation portion 143 for receiving drive from outside. In the first exemplary embodiment, the operation portion 143 is a cross slot provided at an end part of the drive input member 141, and can be driven from outside by a tool (general-purpose tool) fitted to the cross slot, such as a screwdriver having a cross-recess, cross-head, or cross-point. The tool may be a Phillips-head screwdriver.
The loosening member 140, namely, the agitation screw 104b is driven by drive by the tool through the drive input member 141. This makes it possible to loosen the developer in the agitation chamber 101b sealed by the sealing member 51. Examples of the loosening operation of the developing device 100 include a method in which normal rotation and reverse rotation are repeated a plurality of times. As a result, a worker can eliminate the tapping state of the developing device 100 even in the state where the developing device 100 is mounted on the image forming apparatus 200.
The loosening operation of the developing device 100 in the state where the developing device 100 is mounted on the image forming apparatus 200 is to be described. The developing device 100 is mounted on the image forming apparatus 200 in such a manner that a small door 201 inside the image forming apparatus 200 is opened, and the developing device 100 is inserted along a tray 202 in a direction of a rotation axis direction X of the development sleeve 102. Accordingly, the operation portion 143 for receiving external force for the loosening operation of the developing device 100 is required to be positioned at the end part on a front side from which the developing device 100 is inserted in the rotation axis direction X. In a case where the gears (drive transmission members) are provided at the end part of the developing device 100 as in the first exemplary embodiment, it is necessary to provide a cover 144 (developing device cover) at the end part of the developing device 100 in order to protect the worker (service engineer and user). For this reason, to drive the loosening member 140 from outside, a hole (opening) for driving the drive input member 141 is provided on a surface of the cover 144 facing the drive input member 141. Because the opening is provided in the cover 144, the worker can access the operation portion 143 to manually rotate the loosening member 140 in the state where the developing device 100 is mounted on the image forming apparatus 200.
Positional relationship of the development sleeve 102 and the photosensitive drum 1 during the loosening operation of the developing device 100 is to be descried.
To develop the electrostatic image formed on the photosensitive drum 1 to form the toner image on the photosensitive drum 1, it is necessary for the developing device 100 to maintain a distance between a rotation center of the development sleeve 102 and a rotation center of the photosensitive drum 1 to a first distance Y1. Accordingly, in the first exemplary embodiment, the distance Y1 (first distance) is maintained by pressurizing the tray 202 on which the developing device 100 is mounted, by a pressurization member 203 (by putting developing device 100 into pressurized state).
For example, a case where the worker erroneously manually drives the drive input member 141 in a state where the developer is supplied and carried on the development sleeve 102 and the photosensitive drum 1 is stopped is to be considered. In such a case, the development sleeve 102 is also driven through the gears, and the photosensitive drum 1 may be damaged due to contact with the developer carried on the development sleeve 102. For this reason, as illustrated in
In the first exemplary embodiment, as illustrated in
Even in the state where the small door 201 is opened, if the development sleeve 102 is reversely rotated by drive from the outside while the developer is carried on the development sleeve 102, the developer is scraped and accumulated on a sheet 147 provided for preventing the developer from being scattered in
Another exemplary embodiment (second exemplary embodiment) of the present disclosure is to be described. A basic configuration is the same as the configuration according to the first exemplary embodiment. Accordingly, elements having functions and configurations substantially identical or corresponding to the elements according to the first exemplary embodiment are denoted by the same reference numerals, and detailed description of the elements is omitted. Only configuration portions unique to the second exemplary embodiment are to be described in detail.
A configuration in the state where the small door 201 is opened according to the second exemplary embodiment is to be described with reference to
Thus, in the second exemplary embodiment, the operation portion 143 is formed not in the cross slot but in a rectangular groove that is different from the shape of a fastening operation portion 149 of the fastening member 148. Accordingly, the operation portion 143 can be driven only by a flathead screwdriver.
Still another exemplary embodiment (third exemplary embodiment) of the present disclosure is to be described. A basic configuration is the same as the configuration according to the first exemplary embodiment. Accordingly, elements having functions and configurations substantially identical or corresponding to the elements according to the first exemplary embodiment are denoted by the same reference numerals, and detailed description of the elements is omitted. Only configuration portions unique to the third exemplary embodiment are to be described in detail.
Driving of the drive input member 141 by the operation portion 143 and the external force can be performed not only by drive with the tool as in the first exemplary embodiment but also by pulling a seal member wound around the loosening member 140 as illustrated in
The present disclosure is not limited to the above-described exemplary embodiments. Various modifications (including organic combinations of exemplary embodiments) can be made based on the gist of the present disclosure, and are not excluded from the scope of the present disclosure.
In the above-described exemplary embodiments, the image forming apparatus 200 using the intermediate transfer belt 7 as illustrated in
In the state where the developing device is mounted on the image forming apparatus, the tapping state of the developing device can be manually eliminated.
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. 2022-154394, filed Sep. 28, 2022, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-154394 | Sep 2022 | JP | national |
