This patent application is based on and claims priority pursuant to 35 U.S.C. §119 to Japanese Patent Application No. 2013-053040, filed on Mar. 15, 2013, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.
1. Technical Field
This invention generally relates to an image forming apparatus, such as a copier, a printer, a facsimile machine, and a multifunction peripheral (MFP) having at least two of coping, printing, facsimile transmission, plotting, and scanning capabilities.
2. Description of the Background Art
In image forming apparatuses, latent images formed on an image bearer such as a photoreceptor are developed with developer including at least toner. As toner is thus consumed in image development, toner is supplied by a toner replenishing device provided in the image forming apparatus. For example, JP-2012-133349-A proposes a configuration in which the toner replenishing device transports toner from a toner bottle to a developing device.
There are cylindrical toner bottles having a spiral protrusion protruding inward from an inner circumferential face thereof, and there are toner replenishing devices that include a temporary reservoir to temporarily store toner supplied from the toner bottle. Such a toner replenishing device further includes a first toner conveyance device to transport toner from the toner bottle to the temporary reservoir and a second conveyance device to transport toner from the temporary reservoir to the developing device. The first toner conveyance device is constructed of a bottle driving motor to rotate the toner bottle, the spiral protrusion formed in the inner circumferential face of the toner bottle, and the like.
In the state in which the toner bottle is mounted in the toner replenishing device, the toner bottle is rotated by driving force of the bottle driving motor. Then, toner is transported by the spiral protrusion to an opening formed in the toner bottle and supplied to the temporary reservoir.
The second conveyance device is constructed of a toner conveying screw, a driving motor to rotate the toner conveying screw, and the like. When the toner conveying screw is rotated by the driving motor, toner in the temporary reservoir is transported to an toner outlet and further to the developing device.
In such configurations including the temporary reservoir, even when almost all toner in the toner bottle is used up, toner can be supplied from the temporary reservoir to the developing device for a certain period, thus enabling printing operation.
Additionally, typically a toner amount detector is provided to an inner wall of the temporary reservoir to detect the presence of toner at a predetermined height (i.e., level), thereby detecting the amount of toner in the temporary reservoir. According to detection results generated by the toner amount detector, toner is supplied from the toner bottle to the temporary reservoir to keep the amount of toner in the temporary reservoir at a predetermined amount.
In view of the foregoing, one embodiment of the present invention provides an image forming apparatus that includes an image bearer on which a latent image is formed, a developing device to develop with developer the latent image formed on the image bearer, a developer container to contain developer, a temporary reservoir to temporarily store developer supplied from the developer container and having an outlet to discharge the temporarily stored developer to the developing device, a first conveyance device to transport developer from the developer container to the temporary reservoir, a second conveyance device to transport developer from the temporary reservoir to the developing device, a first developer amount detector to detect an amount of developer in the temporary reservoir, and a controller to control driving of the first conveyance device based on a detection result generated by the first developer amount detector and data relating to driving of the second conveyance device.
A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
In describing preferred embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve a similar result.
There is the possibility of erroneous detection when toner is not present around the toner amount detector or the toner amount detector is out of order. It may be erroneously detected that the toner amount in the temporary reservoir is below the predetermined amount when the amount is still greater than the predetermined amount.
In this case, according to the erroneous detection result generated by the toner amount detector, toner supply to the temporary reservoir is kept. Accordingly, there are risks that the amount of toner supplied to the temporary reservoir exceeds the capacity thereof and that the temporary reservoir overflows with toner, causing toner leak.
An aim of the embodiment described below is to inhibit the temporary reservoir from overflowing with developer even when it is erroneously detected that the amount of developer in the temporary reservoir is smaller than the predetermined amount.
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views thereof, and particularly to
It is to be noted that the suffixes Y, M, C, and K attached to each reference numeral indicate only that components indicated thereby are used for forming yellow, magenta, cyan, and black images, respectively, and hereinafter may be omitted when color discrimination is not necessary.
A basic configuration of the image forming apparatus according to the present embodiment is described below.
The image forming apparatus 200 includes four process units 1Y, 1C, 1M, and 1K (i.e., image forming units) for forming yellow, cyan, magenta, and black toner images. The process units 1Y, 1C, 1M, and 1K have a similar configuration except that the color of toner used therein is different.
In the configuration shown in these drawings, the process unit 1Y includes two units, namely, a photoreceptor unit 2Y and a developing device 7Y. The photoreceptor unit 2Y and the developing device 7Y can be united into the process unit 1Y as shown in
The developing device 7Y is formed as a modular unit (i.e., a developing unit) that can be separated from the photoreceptor unit 2Y when removed from the apparatus body.
The photoreceptor unit 2Y includes a drum-shaped photoreceptor 3Y, a drum cleaning device 4Y, a discharger, and a charging device 5Y.
The charging device 5Y serving as a charging member causes a charging roller 6Y to uniformly charge the surface of the photoreceptor 3Y that is rotated clockwise in
It is to be noted that the charging member is not limited thereto. For example, the charging member may include, instead of the charging roller 6Y, a different charging member such as a charging brush disposed close to or in contact with the photoreceptor 3Y. Yet alternatively, chargers such as a scorotron charger to uniformly charge the photoreceptor 3Y by a charger method may be used. An optical writing unit 20 (shown in
The developing device 7Y further includes a second chamber 14Y provided with a density sensor 10Y to detect the density of toner or the concentration of toner in developer, a second conveying screw 11Y, a developing roller 12Y serving as a developer bearer, and a doctor blade 13Y serving as a developer regulator. The density sensor 10Y may be a magnetic permeability sensor.
Two-component developer including magnetic carrier and negatively charged toner is contained in the first and second chambers 9Y and 14Y that together form a circulation channel.
Driven by a driving unit, the first conveying screw 8Y transports developer inside the first chamber 9Y to the proximal side in
The second conveying screw 11Y inside the second chamber 14Y rotates and transports developer to the distal side in
The developing roller 12Y includes a developing sleeve 15Y that rotates counterclockwise in
A part of developer transported by the second conveying screw 11Y is scooped onto the surface of developing sleeve 15Y due to magnetic force exerted by the magnet roller 16Y. The doctor blade 13Y is disposed across a predetermined gap from the surface of the developing sleeve 15Y and adjusts the layer thickness of developer carried on the developing sleeve 15Y, after which developer is transported to a development range facing the photoreceptor 3Y. Then, toner adheres to the electrostatic latent image formed on the photoreceptor 3Y. Thus, a yellow toner image is formed on the photoreceptor 3Y. After yellow toner therein is thus consumed, yellow developer is returned to the second conveying screw 11Y as the developing sleeve 15Y rotates.
Developer transported to the downstream end of the second chamber 14Y by the second conveying screw 11Y is returned through a communicating opening 19Y into the first chamber 9Y. Thus, yellow developer is circulated inside the developing device 7Y.
In
The controller 100 stores in the RAM 102 target values Vtref for the respective colors that are targets of voltages output from the density sensor 10Y and other density sensors 10C, 10M, and 10K provided to the developing devices 7C, 7M, and 7K, respectively.
For supplying yellow toner, the controller 100 compares the voltage output from the density sensor 10Y with the target value Vtref for yellow and controls a drive device 180 for driving a toner replenishing device 160 (shown in
Then, yellow toner is supplied to the first chamber 9Y to compensate for the decrease in the concentration of yellow toner consumed in image development. Thus, the concentration of yellow toner in developer contained in the second chamber 14Y can be kept in a predetermined or desirable range. Similar toner supply control is performed in the developing devices 7C, 7M, and 7K.
Also connected to the controller 100 is a toner amount detector 150 that is provided to the toner replenishing device 160 and configured to detect the amount of toner inside a sub-hopper 163.
Referring back to
In other process units 1 as well, toner images are formed on the respective photoreceptors 3 and primarily transferred onto the intermediate transfer belt 41.
The optical writing unit 20 is disposed beneath the process units 1 in
It is to be noted that the optical writing unit 20 directs the laser beams L emitted from a light source to the respective photoreceptors 3 via multiple optical lenses and mirrors while deflecting the laser beams L with a polygon mirror 21 rotated by a motor. Instead of the above-described configuration, a light scanning mechanism employing a light-emitting diode (LED) array may be used.
Beneath the optical writing unit 20 in
When the first feed roller 31a is rotated counterclockwise in the drawing by a driving unit, the top sheet P in the sheet tray 31 is fed to a sheet feed channel 33 extending vertically on the right in the drawing.
When the second feed roller 32a is rotated counterclockwise in the drawing by the driving unit, the top sheet P in the sheet tray 32 is fed to the sheet feed channel 33.
Multiple pairs of conveyance rollers 34 are provided in the sheet feed channel 33, and the sheet P is sandwiched between the conveyance rollers 34 and transported upward in
A pair of registration rollers 35 is provided at the downstream end of the sheet feed channel 33 in the direction in which the sheet P is conveyed (hereinafter “sheet conveyance direction”). The pair of registration rollers 35 stops rotating immediately after the sheet P is sandwiched therebetween and then forwards the sheet P to a secondary-transfer nip timed to coincide with image formation.
A transfer unit 40 is disposed above the process units 1. The transfer unit 40 rotates the intermediate transfer belt 41 counterclockwise in
The transfer unit 40 includes a belt cleaning unit and first and second brackets in addition to the intermediate transfer belt 41. The transfer unit 40 further includes four primary-transfer rollers 45Y, 45C, 45M, and 45K, a secondary-transfer backup roller 46, a driving roller 47, an auxiliary roller 48, and a tension roller 49.
While being stretched around these rollers, the intermediate transfer belt 41 is rotated counterclockwise in
As the intermediate transfer belt 41 rotates and passes through the four primary-transfer nips sequentially, the yellow, cyan, magenta, and black toner images are transferred from the photoreceptors 3Y, 3C, 3M, and 3K and superimposed one on another on the outer circumferential face of the intermediate transfer belt 41, thus forming a four-color toner image on the intermediate transfer belt 41.
The secondary-transfer backup roller 46 sandwiches the intermediate transfer belt 41 together with a secondary-transfer roller 50 disposed on the outer side of the loop thereof, thus forming a secondary-transfer nip therebetween.
The registration rollers 35 forward the sheet P clamped therebetween to the secondary-transfer nip, time to coincide with the four-color image on the intermediate transfer belt 41.
In the secondary-transfer nip, due to the effects of the secondary-transfer electrical field formed between the secondary-transfer roller 50 and the secondary-transfer backup roller 46 and nip pressure, the four-color toner image is transferred secondarily from the intermediate transfer belt 41 onto the sheet P at a time. Then, the four-color toner image becomes a full color toner image (hereinafter “multicolor toner image”) on the while sheet P.
Then, the belt cleaning unit removes toner remaining on the intermediate transfer belt 41 after the intermediate transfer belt 41 passes the secondary-transfer nip. It is to be noted that the belt cleaning unit removes toner with a cleaning blade that contacts the front surface (outer circumferential surface) of the intermediate transfer belt 41.
It is to be noted that the first bracket of the transfer unit 40 pivots a predetermined rotational angle around the axis of rotation of the auxiliary roller 48 in accordance with on-off driving of a solenoid.
In the present embodiment, the first bracket is rotated a small rotational angle counterclockwise in the drawing by the driving of the solenoid in monochrome image formation. With this rotation, the primary-transfer rollers 45Y, 45M, and 45C revolve counterclockwise in the drawing around the axis of rotation of the auxiliary roller 48, thereby disengaging the intermediate transfer belt 41 from the photoreceptors 3Y, 3M, and 3K.
Then, monochrome images are formed by driving only the process unit 1Y out of the four process unit 1. This operation can eliminate wear of the process units 1Y, 1M, and 1Y resulting from unnecessary driving thereof during monochrome image formation.
Above the secondary-transfer nip in the drawing, a fixing device 60 to fix toner images on sheets of recording media is provided. The fixing device 60 includes a pressure roller 61 and a fixing belt unit 62. Inside the pressure roller 61, a heat source such as a halogen lamp is provided.
The fixing belt unit 62 includes a fixing belt 64, a heating roller 63 including a heat source 63a such as a halogen lamp, a tension roller 65, a driving roller 66, and a temperature detector.
The fixing belt 64, which is an endless belt, is stretched around the heating roller 63, the tension roller 65, and the driving roller 66 and rotated counterclockwise in the drawing. While rotating, the fixing belt 64 is heated by the heating roller 63 from the back side (inner face). The pressure roller 61 rotates clockwise in
Outside the loop of the fixing belt 64, a temperature sensor is disposed facing the outer face of the fixing belt 64 across a predetermined clearance to detect the surface temperature of the fixing belt 64 immediately before entering the fixing nip. The results of detection are transmitted to a fixing power supply circuit.
The fixing power supply circuit turns on and off power supply to the heat source 63a inside the heating roller 63 and the heat source inside the pressure roller 61 according to the detection results generated by the temperature sensor. Thus, the surface temperature of the fixing belt 64 is kept at, for example, about 140°.
After passing through the secondary-transfer nip, the sheet P leaves the intermediate transfer belt 41 and enters the fixing device 60. While the sheet P is nipped in the fixing nip of the fixing device 60 and transported upward in
Subsequently, the sheet P is discharged by a pair of discharge rollers 67 outside the image forming apparatus. The sheets P discharged by the discharge rollers 67 are sequentially stacked on a stack portion 68 formed on an upper face of the apparatus body.
Substantially cylindrical toner bottles 38Y, 38C, 38M, and 38K serving as toner containers for containing yellow, cyan, magenta, and black toners, respectively, are provided in a bottle mount above the transfer unit 40. It is to be noted that the term “cylindrical” used in this specification is not limited to round columns but also includes polygonal prisms.
The respective color toners in the toner bottles 38Y, 38C, 38M, and 38K are supplied to the developing devices 7Y, 7C, 7M, and 7K in the process units 1Y, 1C, 1M, and 1K as required. The toner bottles 38Y, 38C, 38M, and 38K can be installed in and removed from the apparatus body separately from the process units 1Y, 1C, 1M, and 1K.
As described above with reference to
The toner supply inlet 17Y is disposed in an upstream portion of the second chamber 14Y in the direction indicated by arrow B shown in
The toner bottle 38 shown in
The tubular container body 138 includes a spiral protrusion 138c protruding inward from an inner circumferential face thereof. The spiral protrusion 138c extends from a first end side 138a (shown in
An opening 138d into which the nozzle receiver 139 is inserted is formed in an end face on the second end side 138b of the container body 138. Further, scooping portions 138e and 138f are formed on the second end side 138b. Toner transported by the spiral protrusion 138c accumulates in a lower part of the second end side 138b. Additionally, there are toner accumulating in the lower part of the second end side 138b from the beginning. The scooping portions 138e and 138f scoop such accumulating toner upward in the container body 138 as the container body 138 rotates. Further formed on the second end side 138b is a gear 143 to which driving force for rotating the container body 138 is transmitted. The gear 143 is formed integrally with the container body 138.
In the present embodiment, the scooping portions 138e and 138f are arranged to oppose to each other with their phases shifted by 180 degrees. Although the two scooping portions 138e and 138f are provided in the present embodiment, instead, only one of scooping portions 138e and 138f may be provided. Alternatively, four multiple scooping portions may be arranged with their phases shifted by 90 degrees. Yet alternatively, five or more scooping portions may be provided. The number and shape of the scooping portions can be designed freely as long as the scooping portions can supply toner from above to the supply inlet 139b and the powder inlet 170, to be described later.
The nozzle receiver 139 is substantially cylindrical and extends in a longitudinal direction of the container body 138. As shown in
On the outer circumferential face of the nozzle receiver 139, a pair of slits 139c is formed, extending in the longitudinal direction of the nozzle receiver 139. The slits 139c are opposed to each other. The supply inlet 139b is formed in the outer circumferential face of the nozzle receiver 139 and extends long in the longitudinal direction of the nozzle receiver 139.
The nozzle receiving mouth 139a and the supply inlet 139b communicate with each other in the nozzle receiver 139. The supply inlet 139b is formed to present, at least partly, in a movable range of the shutter 140. A ring-shaped seal member 144 constructed of, for example, sponge is attached inside the nozzle receiving mouth 139a to inhibit leak of toner.
The shutter 140 is shaped like a plug (i.e., tubular) and inserted into the nozzle receiver 139. A pin 141 penetrates the shutter 140 in the direction of diameter. As the pin 141 is supported in each slit 139c of the nozzle receiver 139, the shutter 140 is supported movably in the longitudinal direction of the nozzle receiver 139.
A coil spring 142 serving as a biasing member is interposed between an end face 139d of the nozzle receiver 139, which is on the side opposite the nozzle receiving mouth 139a, and the shutter 140.
The shutter 140 is urged by the coil spring 142 to a position to close the nozzle receiving mouth 139a (hereinafter “closing position”), as shown in
The shutter 140 is configured such that when the conveying nozzle 162 is inserted into the nozzle receiver 139, the shutter 140 slides into the container body 138 from the closing position shown in
In the present embodiment, the opening area of the supply inlet 139b extends to a position adjacent to the nozzle receiving mouth 139a. Accordingly, the nozzle receiving mouth 139a and the supply inlet 139b are closed when the shutter 140 is at the closing position. By contrast, if the supply inlet 139b is positioned closer to the end face 139d, only the nozzle receiving mouth 139a is closed when the shutter 140 is at the closing position.
The toner bottle 38 configured as described above is installed by sliding the toner bottle 38 from a proximal side to a distal side of the apparatus body with the second end side 138b of the container body 138s located on a distal side of the container mount.
It is to be noted that, in
The toner replenishing device 160 includes the toner bottle 38, the conveying nozzle 162, and a conveyance channel 161. The conveyance channel 161 is connected to the conveying nozzle 162 and the developing device 7 for transporting toner supplied to the conveying nozzle 162 to the developing device 7.
The conveying nozzle 162 is arranged on the distal side of the container mount (the apparatus body) to be opposed to the shutter 140 that is inserted into the container mount.
The sub-hopper 163 for storing toner to be transported by the conveying nozzle 162 is provided between the conveying nozzle 162 and the conveyance channel 161, and the toner is supplied to the conveyance channel 161 via the sub-hopper 163.
Additionally, the toner amount detector 150 to detect the amount of toner in the sub-hopper 163 is provided to an inner wall of the sub-hopper 163. Use of a piezoelectric sensor or an optical sensor as the toner amount detector 150 is advantageous in that toner amount detection can be attained at a lower cost.
As shown in
The conveying nozzle 162 includes a tubular nozzle section 165 to be inserted into the nozzle receiver 139 of the toner bottle 38, a connection channel 166 connecting the nozzle section 165 and the sub-hopper 163, and a conveying screw 167 disposed in the nozzle section 165 for transporting toner supplied from the toner bottle 38 to the connection channel 166. The conveying nozzle 162 further includes a seal member 168 and a coil spring 169 as a biasing member. The seal member 168 contacts the seal member 144 of the shutter 140, thereby forming a sealing face.
The nozzle section 165 extends in the longitudinal direction of the toner bottle 38 and has an outer diameter insertable into the nozzle receiver 139 from the nozzle receiving mouth 139a. The powder inlet 170 (shown in
The length of the nozzle section 165 is set so that the powder inlet 170 can be opposed to the supply inlet 139b when the nozzle section 165 is inserted into the nozzle receiver 139.
The connection channel 166 is formed integrally with a base end of the nozzle section 165 located on the opposite side of the powder inlet 170, and communicates with the nozzle section 165. The powder inlet 170 is formed in a top face of the nozzle section 165.
A screw section of the conveying screw 167 extends from the end of the nozzle section 165 to the connection channel 166, and the conveying screw 167 is rotatably supported by the nozzle section 165. The seal member 168, formed of sponge and shaped like a ring, is attached to a holder 171 supported movably in the longitudinal direction on the outer circumferential face of the nozzle section 165.
A first end 169a of the coil spring 139 is latched on a spring receiving member 172 held on the outer circumferential face of the nozzle section 165. A second end 169b of the coil spring 169 is latched on the holder 171 that is held slidably on the outer circumferential face of the nozzle section 165 and rotatably about the axis center. In this state, the coil spring 169 urges the seal member 168 toward the seal member 144 (in a direction in which the holder 171 moves away from the spring receiving member 172).
The powder inlet 170 (shown in
The drive device 180 of the toner replenishing device 160 will be described. As shown in
The driving motors 182A and 182B are rotated for a certain period of time by the controller 100 when the controller 100 detects a toner supply signal with the toner bottle 38 mounted in the container mount.
In the toner replenishing device 160 shown in
In addition, in the toner bottle 38, since the nozzle receiver 139 is fixed to and integrated with the container body 138, relative positions therebetween is established once the nozzle receiver 139 is fixed. Thus, the relative positions are arranged such that, when the nozzle receiver 139 is fixed to the container body 138, at least the supply inlet 139b is opposed to the scooping portion 138e or 138f of the container body 138 and located at a position where toner lifted by the scooping portion 138e or 138f drops.
In the configuration shown in
With reference to
While the toner bottle 38 is transported or stored before being mounted to the container mount, the nozzle receiving mouth 139a is closed by the shutter 140 urged by the coil spring 142. That is to say, the toner bottle 38 is in an almost sealed state as communication is blocked between the nozzle receiving mouth 139a and the supply inlet 139b.
From this state, as shown in
When the toner bottle 38 is further moved to the distal side, as shown in
The toner bottle 38 stops moving when fully housed in the container mount and the first end side 138a of the container body 138 is rotatably supported by a support, and occupies a mounted position.
The shutter 140 is further slid into the toner bottle 38 by the nozzle section 165 until the toner bottle 38 occupies the mounted position. By the toner bottle 38 occupying the mounted position, the shutter 140 stops sliding and occupies the open position as shown in
At that time, not only the nozzle receiving mouth 139a but also the supply inlet 139b is opened. Then, as shown in
In the toner bottle 38 configured as described above, the nozzle section 165 of the conveying nozzle 162 having the powder inlet 170 is inserted into the second end portion of the container body 138. The toner bottle 38 further includes the nozzle receiver 139 having the nozzle receiving mouth 139a for supplying the toner in the container body 138 to the powder inlet 170. The toner bottle 38 further includes the shutter 140 supported by the nozzle receiver 139 to open and close the nozzle receiving mouth 139a. The shutter 140 slides in response to insertion of the nozzle section 165 into the nozzle receiver 139 to open and close the nozzle receiving mouth 139a and the supply inlet 139b. With this configuration, the nozzle receiving mouth 139a and the supply inlet 139b are kept closed until the nozzle section 165 is inserted into the nozzle receiver 139.
When the shutter 140 slides in response to insertion of the nozzle section 165 into the nozzle receiver 139, the nozzle receiving mouth 139a is opened, and the shutter 140 pushes toner accumulating around the supply inlet 139b to the inner side of the toner bottle 38. Consequently, space is secured around the supply inlet 139b, which enables reliable supply of toner to the powder inlet 170. Thus, the toner contained in the toner bottle 38 can be reliably discharged to the outside the toner bottle 38, while inhibiting leak and scattering of toner.
When the image forming apparatus 200 is actuated with the toner bottle 38 mounted in the container mount and a toner supply signal is outputted from the controller 100, the driving motors 182A and 182B shown in
When the driving motor 182A is driven, drive force thereof is transmitted to the gear 143 via the gear 184, thus rotating the toner bottle 38. Simultaneously, the drive force of the driving motor 182A is also transmitted via the gear 183 to the conveying screw 167 in the nozzle section 165, and the conveying screw 167 rotates in a direction to transport the toner to the connection channel 166.
By contrast, when the driving motor 182B is driven, driving force thereof is transmitted via the gear 185 shown in
When the toner bottle 38 rotates, the toner contained therein is transported to the second end side 138b by an action of the spiral protrusion 138c and then is mixed with toner accumulated in the lower part of the second end portion.
The relative positions of the supply inlet 139b formed in the nozzle receiver 139 and the scooping portion 138f of the toner bottle 38 do not change when the toner bottle 38 rotates. Accordingly, as shown in
That is, the toner in the toner bottle 38 is supplied into the nozzle section 165 only in a period during which the powder inlet 170 of the nozzle section 165 and the supply inlet 139b of the nozzle receiver 139 overlap while the toner bottle 38 makes one rotation.
The toner supplied into the nozzle section 165 is transported by the conveying screw 167 toward the connection channel 166 and drops on the connection channel 166. The dropped toner is fed into the conveyance channel 161 via the sub-hopper 163 shown in
The conveying screw 167 is disposed in the nozzle section 165 that is inserted into the nozzle receiver 139 of the toner bottle 38. The conveying screw 167 extends from an interior of the toner bottle 38 to the outside of the toner bottle 38 and can actively discharge toner from the toner bottle 38.
Transporting toner inside the toner bottle 38 by the conveying screw 167 to the sub-hopper 163 is advantageous in that toner conveying capability from the toner bottle 38 to the sub-hopper 163 can be maintained regardless of the amount of toner in the sub-hopper 163. Accordingly, almost all toner contained in the toner bottle 38 can be used.
In image forming apparatuses such as printers, typically, toner inside developing devices is consumed as images are formed. As the amount of toner inside the developing device decreases, image density decreases. Accordingly, the device is refilled with toner (i.e., refill toner) to compensate for the amount of toner consumed. Refill toner is stored in a separate component (toner bottles 38 here). In such a configuration, a toner conveyance mechanism is provided to supply the refill toner from the toner bottle to the developing device. The amount of toner thus conveyed is often controlled by the amount of driving (for example, driving time) of a driving motor of the toner conveyance mechanism.
When toner is conveyed linearly (at one draft) from the toner bottle to the developing device, it is possible that the amount of toner conveyed is different from a target amount, due to the fluidity of toner and the like, depending on environments, the structure of toner conveyance, and conveyance route. In view of the foregoing, it is proposed to provide an intermediate toner container, such as a sub-hopper, between the toner bottle and the developing device to control the amount of toner supplied to the developing device.
The amount of toner supplied can be controlled more accurately by separating a second conveyance device to transport toner from the sub-hopper to the developing device from a first conveyance device to transport toner from the toner bottle to the sub-hopper and driving the first and second conveyance devices separately. This configuration can better meet usage environments of users and thus is convenient for users.
The toner conveyance amount to the developing device directly relates to image quality and has significant effects on image quality particularly in configurations in which two-component developer is used.
In configurations in which the first and second conveyance devices are not driven separately (i.e., not controlled separately), it is desirable that toner recovery action, the necessity of which arises in replacement of toner bottles, is not started during image formation. If toner recovery action is executed, productivity decreases since image formation is not feasible during toner recovery action. It is to be noted that “toner recovery action” used here means operation for compensating for the shortage of toner in the conveyance channel and the toner bottle that arises as toner is transported from the toner bottle to the sub-hopper.
By contrast, driving the first and second conveyance devices separately is advantageous in that toner recovery action can be executed independently while the function to maintain a desirable image quality secured. That is, conveyance of toner to the developing device, which contributes to image quality, is secured. Therefore, image formation productivity does not decrease.
Additionally, while control of toner conveyance from the sub-hopper to the developing device, which directly relates to image quality, is designed carefully, that from the toner bottle to the sub-hopper is simple. Since the conveyance of toner from the toner bottle to the sub-hopper does not directly contribute to image quality, it does not matter as long as the amount of toner in the sub-hopper is sufficient for conveyance of toner to the developing device.
Generally, toner conveyance from the toner bottle to the sub-hopper is controlled according to a toner amount detector provided to an inner wall of the sub-hopper to detect the amount of toner in the sub-hopper. When the detected amount of toner in the sub-hopper falls below a predetermined amount, toner is supplied thereto from the toner bottle.
However, there is the possibility of erroneous detection when toner is not present around the toner amount detector or the toner amount detector is out of order. That is, it may be erroneously detected that the toner amount in the sub-hopper is below the predetermined amount although the amount of toner therein is greater than the predetermined amount.
In cases where the toner amount detector erroneously detects that the amount of toner is greater although no toner remains in the sub-hopper, toner is not transported from the toner bottle to the sub-hopper. If this situation continues, image quality is affected. For example, image density decreases. In this case, the toner conveyance device and the like are not damaged, and the situation can be handled.
However, the opposite situation may cause damage. That is, if toner amount detector erroneously detects that the amount of toner is smaller in spite of a sufficient amount of toner stored in the sub-hopper, toner conveyance from the toner bottle to the sub-hopper is repeated until it detects that the amount of toner is sufficient.
If the amount conveyed to the sub-hopper from the toner bottle exceeds the capacity of the sub-hopper, there arise risks that the sub-hopper overflows with toner, causing toner leak, and damage is caused in components of the second conveyance device for toner conveyance from the toner bottle to the sub-hopper. In other words, that situation is fatal to the image forming apparatus, and recovery is difficult.
The inventors of the present invention recognize that this greatly relates to the toner conveyance capability from the toner bottle to the sub-hopper. When the amount of toner remaining in the toner bottle becomes small, typically the amount of toner discharged from the toner bottle becomes small, which makes it difficult to use up all of toner remaining in the toner bottle. Therefore, currently, there are mechanisms to actively discharge toner inside the toner bottle to use up toner stored inside the toner bottle.
In configurations without such a mechanism to actively discharge toner from the toner bottle, even if an amount of toner exceeding the capacity is supplied to the sub-hopper, toner is not materially supplied to the sub-hopper above a certain level. Specifically, although the toner conveyance device tries to keep supplying toner from the toner bottle to the sub-hopper when the sub-hopper becomes full, toner is not materially supplied thereto since the toner conveyance capability is not high.
By contrast, configurations provided with such a mechanism to actively discharge toner from the toner bottle are aimed at actively transporting toner from the toner bottle to the sub-hopper, and the capability to supply toner from the toner bottle to the sub-hopper is high. The inventors of the present invention have found that, even if the sub-hopper becomes full with toner exceeding the capacity, the mechanism keeps supplying toner to the sub-hopper as long as the controller continues to instruct toner conveyance. In other words, even if the sub-hopper is crammed up with toner, the mechanism keeps supplying toner to the sub-hopper until the toner amount detector sends to the controller a signal indicating that the amount of toner in the sub-hopper is proper. Then, there is a risk that the channel of toner conveyance extending from the toner bottle to the sub-hopper is crammed up with toner, and toner is pressed to solidify. Consequently, toner leaks from the sub-hopper, or the toner conveyance device is damaged.
In view of the foregoing, in the image forming apparatus 200 according to the present embodiment, the controller 100 controls driving of the first conveyance device using data relating to driving of the second conveyance device, in addition to the detection results generated by the toner amount detector 150, indicating the detected amount of toner in the sub-hopper 163.
It is to be noted that, in the present embodiment, the driving motor 182A, the conveying screw 167, the spiral protrusion 138c protruding inward from the inner circumferential face of the toner bottle 38, and the like together form the first conveyance device. Additionally, the driving motor 182B, the conveying screw 161B, and the like together form the second conveyance device.
Additionally, “data relating to driving of the second conveyance device” includes data of driving of the conveying screw 161B by the driving motor 182B, data that suggests that conveying screw 161B is driven, and the like.
In the present embodiment, even if the toner amount detector 150 detects that the amount of toner in the sub-hopper 163 is smaller than the predetermined amount, the first conveyance device is not driven when the second conveyance device has not yet driven after the previous conveyance of developer (i.e., toner) from the toner bottle 38 to the sub-hopper 163.
With this control, toner is not transported from the toner bottle 38 to the sub-hopper 163 when the amount of toner in the sub-hopper 163 is equal to or greater than the predetermined amount although the toner amount detector 150 erroneously detects that the amount of toner in the sub-hopper 163 is smaller than that. Accordingly, this control can inhibit the inconvenience that the amount conveyed to the sub-hopper 163 from the toner bottle 38 exceeds the capacity of the sub-hopper 163, thus inhibiting overflow of the sub-hopper 163 with toner and damage to the toner conveyance mechanism.
Next, descriptions are given below of control of toner replenishing performed by the toner replenishing device 160 according to the present embodiment.
At S1, the controller 100 starts controlling toner conveyance from the toner bottle 38 to the sub-hopper 163, triggered by a print job start signal, at a predetermined timing, or in a predetermined cycle.
At S2, the controller 100 acquires a detected toner remaining amount indicating the amount of toner remaining in the sub-hopper 163 based on the detection results generated by the toner amount detector 150 provided to the inner wall of the sub-hopper 163 and then compares the detected toner remaining amount with a predetermined threshold for the toner remaining amount. Then, the controller 100 determines whether to execute toner conveyance from the toner bottle 38 to the sub-hopper 163.
When the detected toner remaining amount is equal to or greater than the threshold therefor (No at S2), toner conveyance from the toner bottle 38 to the sub-hopper 163 is deemed unnecessary, and the controller 100 completes the control of toner conveyance from the toner bottle 38 to the sub-hopper 163 at S5.
It is to be noted that when the detected toner remaining amount is not available, toner conveyance from the toner bottle 38 to the sub-hopper 163 is deemed unnecessary. That is, it is deemed that the amount of toner in the sub-hopper 163 is greater than the threshold therefor.
By contrast, when the detected toner remaining amount is smaller than the threshold therefor (Yes at S2), toner conveyance from the toner bottle 38 to the sub-hopper 163 is deemed necessary. At S3 the controller 100 judges whether or not the conveying screw 161B has been driven based on the data relating to driving of the conveying screw 161B. Alternatively, the controller 100 presumes whether or not the conveying screw 161B has been driven based on data suggesting that conveying screw 161B is driven.
It is to be noted that data relating to driving of the conveying screw 161B includes driving time of the driving motor 182B, rotational frequency thereof, and the like. The data suggesting that conveying screw 161B is driven includes the amount of toner discharged from the developing device 7 (i.e., image data of printed images). As such data relating to (or suggesting) driving of the conveying screw 161B, for example, data acquired after the previous toner conveyance from the toner bottle 38 to the sub-hopper 163 can be used.
When it is judged or presumed that the conveying screw 161B has not been driven (No at S3), the controller 100 sets the amount of toner to be transported to the sub-hopper 163 to zero (0). Then, at S5, the control of toner conveyance is completed without transporting toner from the toner bottle 38 to the sub-hopper 163.
It is to be noted that, when the data relating to (or suggesting) driving of the conveying screw 161B is not input to the controller 100, the controller 100 judges that the conveying screw 161B has not driven and sets the necessary amount of toner transported to the sub-hopper 163 to zero (0) as described above.
By contrast, when it is judged or presumed that the conveying screw 161B has been driven (Yes at S3), the controller 100 calculates the amount of toner to be transported to the sub-hopper 163.
It is to be noted that the amount of toner to be transported can be either fixed value or variable. For example, that is a fixed amount with which the toner conveyance amount becomes stable. In this case, the fixed amount can be smaller than an estimated amount of toner discharged from the developing device 7. Additionally, the amount of toner to be transported may be variable with its upper limit set to the estimated amount of toner discharged from the developing device 7, calculated from the driving amount (estimated driving amount) of the conveying screw 161B.
At S4, the toner conveyance device to transport toner to the sub-hopper 163 is driven. Specifically, the driving motor 182A is turned on for a time period T1 (ms) corresponding to the amount of toner to be transported calculated by the controller 100, and the conveying screw 167 transports toner from the toner bottle 38 to the sub-hopper 163.
It is to be noted that, when toner conveyance from the toner bottle 38 to the sub-hopper 163 is completed properly, the above-described sequence of control operation is repeated as required. If toner conveyance from the toner bottle 38 to the sub-hopper 163 is ended abnormally, error handling, such as error log recording or error message display, is performed, and the sequence of control operation is completed.
In the second embodiment described below, control of toner conveyance from the sub-hopper 163 to the developing device 7 is performed in parallel to control of toner conveyance from the toner bottle 38 to the sub-hopper 163.
In the present embodiment, toner conveyance from the toner bottle 38 to the sub-hopper 163 and that from the sub-hopper 163 to the developing device 7 are controlled separately using controllers 100A and 100B (see
[Control of Toner Conveyance from the Sub-Hopper 163 to the Developing Device 7]
Referring to
At S11, the controller 100B starts controlling toner conveyance from the sub-hopper 163 to the developing device 7, triggered by a print job start signal, at a predetermined timing, or in a predetermined cycle.
At S12, the amount of toner to be transported to the developing device 7 is calculated based on at least one of printed image data and data indicating the amount of toner in the developing device 7 (for example, detection results generated by the density sensor 10 of magnetic permeability detection type).
It is to be noted that, as the data indicating the amount of toner in the developing device 7, use of toner density (or concentration of toner in developer) inside the developing device 7 is desirable to accurately determine and control the amount of toner transported.
At S13, the controller 100B determines whether to execute toner conveyance from the sub-hopper 163 to the developing device 7 according to the calculated amount of toner to be transported to the developing device 7.
When the amount of toner to be transported is zero (0), toner conveyance to the developing device 7 is deemed unnecessary (No at S13). At S16, the control operation is completed without performing toner conveyance from the sub-hopper 163 to the developing device 7.
By contrast, when the amount of toner to be transported is not zero (Yes at S13), toner conveyance to the developing device 7 is deemed necessary. At S14, the toner conveyance device to transport toner to the developing device 7 is driven. Specifically, the driving motor 182B is turned on for a time period T2 (ms) corresponding to the calculated amount of toner to be transported, and the conveying screw 161B transports toner from the sub-hopper 163 to the developing device 7.
Additionally, as S15, driving data of the driving motor 182B resulting from toner conveyance from the sub-hopper 163 to the developing device 7 is stored in the memory device such as the RAM 102. The stored driving data of the driving motor 182B is used by the controller 100A at S3′ in
When toner conveyance from the sub-hopper 163 to the developing device 7 is completed properly at S16, the above-described sequence of control operation is repeated as required. If toner conveyance from the sub-hopper 163 to the developing device 7 is ended abnormally, error handling, such as error log recording or error message display, is performed, and the sequence of control operation is completed.
[Control of Toner Conveyance from the Toner Bottle 38 to the Sub-Hopper 163]
Referring to
In the present embodiment, toner conveyance from the toner bottle 38 to the sub-hopper 163 and that from the sub-hopper 163 to the developing device 7 are controlled by an identical controller, namely, the controller 100 shown in
[Control of Toner Conveyance from the Sub-Hopper 163 to the Developing Device 7]
At S21, the controller 100 starts controlling toner conveyance from the sub-hopper 163 to the developing device 7, triggered by a print job start signal, at a predetermined timing, or in a predetermined cycle.
At S22, the amount of toner to be transported from the sub-hopper 163 to the developing device 7 is calculated based on at least one of printed image data and data indicating the amount of toner in the developing device 7 (for example, detection results generated by the density sensor 10 of magnetic permeability detection type).
At S23, the controller 100 determines whether to execute toner conveyance from the sub-hopper 163 to the developing device 7 according to the calculated amount of toner to be transported to the developing device 7.
When the amount of toner to be transported is zero (0), toner conveyance to the developing device 7 is deemed unnecessary (No at S23). At S26, the control operation is completed without performing toner conveyance from the sub-hopper 163 to the developing device 7.
By contrast, when the amount of toner to be transported is not zero (Yes at S23), toner conveyance to the developing device 7 is deemed necessary. At S24, the toner conveyance device to transport toner to the developing device 7 is driven. Specifically, the driving motor 182B is turned on for a time period T2 (ms) corresponding to the calculated amount of toner to be transported, and the conveying screw 161B transports toner from the sub-hopper 163 to the developing device 7.
Additionally, at S25 shown in
When toner conveyance from the sub-hopper 163 to the developing device 7 is completed properly, the above-described sequence of control operation is repeated as required.
[Control of Toner Conveyance from the Toner Bottle 38 to the Sub-Hopper 163]
At S31, the controller 100 starts controlling toner conveyance from the toner bottle 38 to the sub-hopper 163 triggered by a print job start signal, at a predetermined timing, or in a predetermined cycle.
At S32, based on the detected toner remaining amount in the sub-hopper 163, the controller 100 calculates the amount of toner to be transported from the toner bottle 38 to the sub-hopper 163. At that time, the controller 100 further retrieves the data relating to driving of the driving motor 182B stored at S25.
At S33, the controller 100 determines whether to execute toner conveyance from the toner bottle 38 to the sub-hopper 163 based on the result of comparison of the detected toner remaining amount in the sub-hopper 163 with the threshold, the retrieved data of driving of the driving motor 182B, and the like.
The controller 100 determines that toner conveyance from the toner bottle 38 to the sub-hopper 163 is necessary (Yes at S33) when requirements 1) the detected toner remaining amount is smaller than the threshold and 2) it is determined or presumed that the conveying screw 161B has been driven, are satisfied.
At S34, the toner conveyance device to transport toner to the sub-hopper 163 is driven. Specifically, the driving motor 182A is turned on for a time period T3 (ms) corresponding to the calculated amount of toner to be transported, and the conveying screw 167 transports toner from the toner bottle 38 to the sub-hopper 163.
It is to be noted that, when toner conveyance from the toner bottle 38 to the sub-hopper 163 is completed properly at S37, the above-described sequence of control operation is repeated as required.
Additionally, as S35, data relating to driving of the driving motor 182A resulting from toner conveyance from the toner bottle 38 to the sub-hopper 163 is stored in the memory device such as the RAM 102. The stored data relating to the driving of the driving motor 182A is used in calculation of the amount of toner remaining in the toner bottle 38 (at S36).
By contrast, when the detected toner remaining amount is not smaller than the threshold or it is determined or presumed that the conveying screw 161B is not driven (No at S33), the control operation is completed without transporting toner from the toner bottle 38 to the sub-hopper 163 at S37.
At that time, the above processing is not sufficient in configurations, such as the second embodiment, that include the separate controllers 100A and 100B to control toner conveyance from the toner bottle 38 to the sub-hopper 163 and that from the sub-hopper 163 to the developing device 7, respectively. Specifically, in cases where the controllers 100A and 100B are independent of each other, an additional step is necessary when each controller has not yet acquired necessary data.
By contrast, when the controller 100 controls both of toner conveyance from the toner bottle 38 to the sub-hopper 163 and that from the sub-hopper 163 to the developing device 7, the controller 100 itself governs acquisition of necessary data. Accordingly, timing of input and output, in particular, the order of control processes, can be managed properly.
Additionally, since the single controller 100 controls driving of multiple conveyance devices such as the conveying screw 167 and the conveying screw 161B, the configuration of the controller 100 can be simplified. Additionally, it is desirable to use the data relating to driving of the conveying screw 161B for the control data of driving of the conveying screw 167 since data input and output can be relatively easy when the control operation is executed by the single controller 100.
Further, error handling can be easier since failure in inputting data to the controller 100 can be limited to errors such as output error of the toner amount detector 150.
It is to be noted that the steps in the above-described flowcharts may be executed in an order different from that in the flowchart.
Still further, the aforementioned control methods may be embodied in the form of an apparatus, method, system, computer program and computer program product, including, but not limited to, any of the structure for performing the methodology illustrated in the drawings. The program may be stored on a computer readable media and is adapted to perform any one of the aforementioned methods when run on a computer device (a device including a processor). Thus, the storage medium or computer readable medium, is adapted to store information and is adapted to interact with a data processing facility or computer device to perform the method of any of the above mentioned embodiments.
The various configurations according to the present inventions can attain specific effects as follows.
Aspect A: An image forming apparatus includes an image bearer, such as the photoreceptor 3, a developing device to develop a latent image formed on the image bearer with developer such as toner, a developer container such as the toner bottle 38 to store developer used by the developing device, a temporary reservoir, such as the sub-hopper 163, to temporarily store developer supplied from the developer container and having an outlet to discharge the temporarily stored developer to the developing device, a first conveyance device, such as the conveying screw 167, to transport developer from the developer container to the temporary reservoir, a second conveyance device, such as the conveying screw 161B, to transport developer from the temporary reservoir to the developing device, and a first developer amount detector, such as the toner amount detector 150, to detect the amount of developer in the temporary reservoir.
The image forming apparatus further includes a first controlling unit, such as the controller 100A, to control driving of the first conveyance device based on data relating to driving of the second conveyance device and a detection result generated by the first developer amount detector.
In the above-described embodiment, the first controlling unit controls the first toner conveyance device to transport developer from the developer container to the temporary reservoir using, in addition to the detected amount of toner inside the temporary reservoir, data relating to driving of the second conveyance device to transport developer from the temporary reservoir to the developing device.
When the requirements of 1) the first developer amount detector detects that the amount of developer in the temporary reservoir is smaller than the predetermined amount and 2) the second conveyance device has been driven after the previous conveyance of developer to the temporary reservoir are satisfied, the first toner conveyance device is driven, thereby transporting developer from the developer container to the temporary reservoir. The amount of developer transported to the temporary reservoir at that time can be similar to the amount of developer transported from the temporary reservoir to the developing device by the second conveyance device. The amount can be obtained based to the data relating to driving of the second conveyance device.
With this operation, the amount of developer transported by the first toner conveyance device to the temporary reservoir does not exceeds the capacity of the temporary reservoir, and the amount of developer in the temporary reservoir can be kept at or above the predetermined amount.
By contrast, after the first toner conveyance device transports developer to the temporary reservoir, the amount of developer in the temporary reservoir does not decrease unless developer is supplied from the temporary reservoir to the developing device. Even if the first developer amount detector detects that the amount of developer in the temporary reservoir is smaller than the predetermined amount, there is a possibility that the amount of developer in the temporary reservoir is equal to or greater than the predetermined amount in a case where the second conveyance device has not yet transported developer from the temporary reservoir. Therefore, even if the requirement 1) is satisfied, the first toner conveyance device is not driven as long as the second conveyance device has not been driven after the previous conveyance of developer to the temporary reservoir.
With this operation, even in cases where the first developer amount detector erroneously detects that the amount of developer in the temporary reservoir is smaller than the predetermined amount in spite of the sufficient amount of developer therein, developer is not transported to the temporary reservoir, and the temporary reservoir can be protected from overflowing with developer.
Aspect B: In aspect A, the image forming apparatus further includes a second developer amount detector, such as the density sensor 10, to detect the amount of developer in the developing device, an image data acquisition unit, such as the controller 100, to acquire image data used to form the latent image, and a second controlling unit, such as the controller 100B, to control driving of the second conveyance device based on the image data acquired by the image data acquisition unit and a detection result generated by the second developer amount detector.
This configuration can secure image quality since the driving of the second conveyance device is controlled based on data to secure image quality.
Aspect C: In aspect B, a single controller includes the first controlling unit and the second controlling unit. With this configuration, since the single controller controls driving of multiple conveyance devices, the control configuration can be simplified as described above. Additionally, it is desirable to use the data relating to driving of the second conveyance device to control the first toner conveyance device since data input and output can be relatively easy when the control operation is executed by the common controller.
Aspect D: In any of aspects A, B, and C, the first toner conveyance device is configured such that capability to transport developer conveyance from the developer container to the temporary reservoir can be maintained regardless of the amount of developer in the temporary reservoir. With this configuration, developer contained in the developer container can be used up as described above.
Aspect E: In any of aspects A, B, C, and D, developer includes at least toner, and the data indicating the amount of developer in the developing device includes the density of toner (or the concentration of toner in developer). With this configuration, the amount of toner to be transported can be accurately determined and controlled.
Aspect F: In any of aspects A, B, C, D, and E, the first developer amount detector can be a piezoelectric sensor or an optical sensor provided to an inner wall of the temporary reservoir. With this configuration, the amount of developer can be detected at a lower cost and easily.
Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the disclosure of this patent specification may be practiced otherwise than as specifically described herein.
Number | Date | Country | Kind |
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2013-053040 | Mar 2013 | JP | national |