Patent Application
20220382184
The present invention relates to an image forming apparatus using an electrophotographic system, such as a printer, a copying machine, and a facsimile.
There is known an image forming apparatus that supplies toner in the toner container to the development device via the hopper, among image forming apparatuses with an electrophotographic system. Image forming apparatuses with that system use a sensor that detects the quantity of toner in the development device. In response to when the quantity of toner in the development device becomes less than or equal to a predetermined value, the image forming apparatus makes notification as an abnormality message. Detection of decrease in the quantity of toner in the development device can be caused by abnormality in the conveyance mechanism that conveys toner from the hopper to the development device.
Japanese Patent Application Laid-Open No. 2006-220960 discusses an image forming apparatus that uses a method of detecting an abnormality of conveyance in the hopper that supplies toner to the development device. In response to when an abnormality of the quantity of toner in the development device occurs, the apparatus supplies toner from the hopper to the development device for a predetermined time. If there is no abnormality of conveyance in the hopper, the operation of supplying toner to the development device causes toner in the hopper to eventually run out while to increase in the development device. According to Japanese Patent Application Laid-Open No. 2006-220960, in supplying toner to the development device for a predetermined time, the image forming apparatus determines that an abnormality of conveyance of toner occurs in the hopper if the sensor in the hopper continues detecting the presence of toner with no increase in the quantity of toner in the development device.
However, according to Japanese Patent Application Laid-Open No. 2006-220960, the image forming apparatus relies on two sensors to determine abnormality of conveyance in the hopper: one in the hopper and the other in the development device at a distant location from the hopper.
According to an aspect of the present invention, an image forming apparatus includes a toner container configured to accommodate toner, the toner container being provided with an outlet, the toner container including a first conveyance unit configured to discharge toner to an outside of the toner container through the outlet, and an apparatus main body on which the toner container is detachably mounted. The apparatus main body includes a photosensitive drum, a development roller configured to supply toner to the photosensitive drum, a second conveyance unit configured to convey toner toward the development roller, a toner conveyance passage in which the second conveyance unit is provided and which is provided with a receiving inlet to receive toner discharged from the outlet of the toner container, a sensor including a light emitting portion configured to emit light toward an inside of the toner conveyance passage, and a light receiving portion configured to receive light emitted from the light emitting portion and passing through the inside of the toner conveyance passage, the sensor being configured to output a signal based on a quantity of light received by the light receiving portion, an acquisition unit configured to acquire an acquired value based on an output value from the sensor, and a control unit configured to control driving of the first conveyance unit and the second conveyance unit independently and to execute an abnormality detection mode. In the abnormality detection mode, the acquisition unit is configured to acquire a first acquired value after execution of the driving of the second conveyance unit for a first predetermined time in a state where the driving of the first conveyance unit is stopped. In a case where the first acquired value satisfies a first condition, the acquisition unit is configured to further acquire a second acquired value after execution of the driving of the second conveyance unit for a second predetermined time in a state where the driving of the first conveyance unit is stopped. The apparatus main body further includes a notification unit configured to make notification of an abnormality in the toner conveyance passage. In a case where the second acquired value satisfies a second condition, the notification unit is configured to make notification of the abnormality.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
An image forming apparatus 1 according to a first exemplary embodiment will be described.
The image forming apparatus 1 includes process cartridges 6Y, 6M, 6C, and 6Bk (hereinafter referred to as a process cartridge 6) that are detachably mounted on an apparatus main body 1000. The process cartridge 6 includes a photosensitive drum 7, a cleaning blade 10, a charging device 8, and a development device 9. The development device 9 includes a development roller 11 for supplying toner to the photosensitive drum 7, and a toner accommodation unit 99 (first toner accommodation unit) that accommodates toner to be borne by the development roller 11.
The image forming apparatus 1 causes a laser scanner unit 12 to emit laser onto the photosensitive drum 7 based on image information acquired by a control unit 27. The image forming apparatus 1 develops the latent image thereby formed on the photosensitive drum 7 as a toner image with toner supplied from the development roller 11.
The developed toner image is transferred to an intermediate transfer belt 18 by a primary transfer portion 20, each color being sequentially transferred to the toner image, whereby the toner image composed of four colors is formed on the surface of the intermediate transfer belt 18. That toner image is conveyed to a secondary transfer portion 17.
Toner containers 13 (13Y, 13M, 13C, and 13Bk) are arranged under the process cartridge 6. The image forming apparatus 1 includes a toner conveyance device 14 for supplying toner from the toner container 13 to the toner accommodation unit 99 of the development device 9. The toner conveyance device 14 is driven by a toner conveyance driving device 15 arranged under the toner conveyance device 14.
A recording material 4 is accommodated in a cassette 2 in the lower portion of the image forming apparatus 1. Rotation of a pickup roller 3 separates and feeds the recording material 4 one sheet by one sheet. Thereafter, the recording material 4 is conveyed by a registration roller 5 downstream.
Subsequently, an intermediate transfer unit 16 is arranged in the upper portion of the image forming apparatus 1. The intermediate transfer unit 16 is arranged substantially horizontally with the primary transfer portion 20 at the lower. An intermediate transfer belt 18 facing each photosensitive drum 7 is a rotatable endless belt, and is stretched by a plurality of stretching rollers. A primary transfer roller 19 serving as a primary transfer member is arranged on the internal surface of the intermediate transfer belt 18. The primary transfer roller 19, together with each photosensitive drum 7, forms the primary transfer portion 20 with the intermediate transfer belt 18 interposed between the primary transfer roller 19 and each photosensitive drum 7. At each primary transfer portion 20, a voltage is applied to the primary transfer roller 19, and a toner image is transferred from each photosensitive drum 7 to the intermediate transfer belt 18. According to the present exemplary embodiment, the intermediate transfer unit 16 as a unit including the intermediate transfer belt 18, the plurality of stretching rollers that stretches the intermediate transfer belt 18, and each primary transfer roller 19 is detachably mounted on the apparatus main body.
A secondary transfer roller 21 serving as a secondary transfer member is in contact with the intermediate transfer belt 18, and forms, together with a roller on the opposite site, the secondary transfer portion 17 with the intermediate transfer belt 18 interposed between the second transfer roller 21 and the roller on the opposite side. At the secondary transfer portion 17, the toner image transferred on the intermediate transfer belt 18 is secondarily transferred to the recording material 4. Toner that has not been transferred in the secondary transfer and that remains on the intermediate transfer belt 18 is removed by a cleaning unit 22. Toner removed by the cleaning unit 22 is conveyed to a toner collecting container 24 by way of a collected toner conveyance unit 23.
The recording material 4, on which the unfixed toner image is transferred, is further conveyed downstream, and then pressed and heated by a heating unit 25a and pressure roller 25b of a fixing device 25, respectively, which causes toner to melt, whereby the toner image is fixed to the recording material 4. Thereafter, the recording material 4 is discharged to a discharge tray 277 by a discharge roller pair 26. Image formation on the recording material 4 is performed through these series of operations. A mode of performing these series of operations is hereinafter referred to as an “image formation mode”.
The control unit 27 of the image forming apparatus 1 performs overall control of the image forming apparatus 1, and includes one or more central processing units (CPUs), a read-only memory (ROM) that stores programs run by the CPU(s) and data, and a random-access memory (RAM) that is used as a work area of the CPU(s).
Details of the toner conveyance device 14 will be now described with reference to
The toner conveyance unit 900 includes a cylindrical first toner conveyance path 208 (passage, second toner accommodation unit) and an upstream conveyance screw 905 (second conveyance unit). The first toner conveyance path 208 is provided with a receiving inlet 101 in the upper surface thereof and extends in the horizontal direction. The upstream conveyance screw 905 is disposed inside the first toner conveyance path 208 and conveys toner. A toner receiving path 206 that extends downward from the receiving inlet 101 and that extends downstream in the toner conveyance direction of the upstream conveyance screw 905 is provided inside the first toner conveyance path 208.
The upstream conveyance screw 905 includes a shaft portion and a helical blade portion arranged on the outer periphery of the shaft portion. Rotation of the shaft portion and the blade portion in an integrated manner enables conveyance of toner.
The toner conveyance unit 900 includes a cylindrical second toner conveyance path 209 (a cylindrical second toner conveyance passage) that extends upward, and a downstream conveyance screw 904 that is provided inside the second toner conveyance path 209 and that conveys toner upward. The upstream end portion of the second toner conveyance path 209 is connected to the downstream end portion of the first toner conveyance path 208. The upstream conveyance screw 905 and the downstream conveyance screw 904 are driven by the toner conveyance driving device 15. The toner conveyance driving device 15 includes a conveyance motor 405 (second motor) and a driving gear 205 that is driven by the conveyance motor 405 and that transmits driving force to the upstream conveyance screw 905.
The toner conveyance unit 900 includes a light transmitting portion 207 and a sensor 1516. The light transmitting portion 207 includes a light transmitting member 207a (first light transmitting portion) and a light transmitting member 207b (second light transmitting portion) that are arranged to face each other. The sensor 1516 includes a light emitting portion 215 and a light receiving portion 216. The light emitting portion 215 includes a light emitting device 215a and a circuit board 215b provided with the light emitting device 215a. The light receiving portion 216 includes a light receiving device 216a and a circuit board 216b provided with the light receiving device 216a.
The sensor 1516 outputs an output value based on the quantity of light received by the light receiving portion 216. An output value in the present exemplary embodiment is a voltage. The sensor 1516 in the present exemplary embodiment outputs a lower voltage as the quantity of light received by the light receiving portion 216 becomes greater, and outputs a higher voltage as the quantity of light received by the light receiving portion 216 becomes smaller.
Toner is supplied from the toner container 13 to the first toner conveyance path 208 via the receiving inlet 101 and the toner receiving path 206. Toner is conveyed by the upstream conveyance screw 905 through the first toner conveyance path 208 toward the second toner conveyance path 209.
A driving control unit 401 of the control unit 27 controls driving of the conveyance motor 405. The downstream conveyance screw 904 is connected to the most downstream portion of the upstream conveyance screw 905, and rotates in conjunction with the upstream conveyance screw 905. The toner conveyed by the upstream conveyance screw 905 is transferred to the downstream conveyance screw 904, and is conveyed by the downstream conveyance screw 904 toward the development device 9. The driving of the conveyance motor 405 by the driving control unit 401 causes rotational driving of the downstream conveyance screw 904 in conjunction with the upstream conveyance screw 905, whereby toner is conveyed upward. The toner conveyed upward is supplied to the development device 9 in
The control unit 27 performs control to supply toner from the toner container 13 to the first toner accommodation unit 99 of the development device 9 via the toner conveyance unit 900, based on the quantity of remaining toner of the first toner accommodation unit 99 of the development device 9.
The toner that has passed through the toner receiving path 206 of the first toner conveyance path 208 is discharged from the leading end port 206a at the leading end of the toner receiving path 206 toward a region S above the upstream conveyance screw 905.
The light transmitting members 207a and 207b are arranged to fill a hole provided in the wall of the first toner conveyance path 208 in the vicinity of the connection portion between the upstream conveyance screw 905 and the downstream conveyance screw 904.
The arrangement of the light emitting portion 215 and the light receiving portion 216 will be now described. As illustrated in
A cleaning member 217 is disposed in the vicinity of the light transmitting members 207a and 207b.
The rotary shaft 308b is provided with a plurality of arm portions 308d (driving force receiving portions) that is in contact with the blade portion of the upstream conveyance screw 905 and that is used for receiving the driving force. With rotation of the blade portion of the upstream conveyance screw 905, a leading end portion 3080d of each arm portion 308d of the cleaning member 217 is pressed by the blade portion, whereby the cleaning member 217 is rotated. The rotational axis RA2 extends in the direction orthogonal to the rotational axis of the upstream conveyance screw 905.
The rotation of the cleaning member 217 causes the sheet 308a to rub the surfaces of the light transmitting members 207a and 207a. That action removes toner on the light transmitting members 207a and 207b. Toner on the light transmitting members 207a and 207b blocks light even if there is little toner in the region in the optical path, causing higher voltage values output from the sensor 1516. That can cause a detection by the sensor 1516 as an error that toner is excessively accumulated in the first toner conveyance path 208. To prevent that error, the light transmitting members 207a and 207b are cleaned by rotation of the cleaning member 217 on a regular basis.
Subsequently, the toner conveyance driving device 15 will be now described in detail with reference to
As illustrated in
The control unit 27 will be described with reference to
The driving control unit 401 drives the supply motor 404 at timings when toner supply becomes necessary and operates the pump 302. That operation causes toner to be supplied from the toner container 13 to the first toner conveyance path 208. Furthermore, the driving control unit 401 drives the conveyance motor 405 to cause the upstream conveyance screw 905, the cleaning member 217, and the downstream conveyance screw 904 to operate, thereby conveying toner to the development device 9. The driving control unit 401 causes the light emitting device 215a of the light emitting portion 215 to emit light at timings of detection of a state of the first toner conveyance path 208. A voltage, which is an output signal from the light receiving portion 216, is acquired as an acquired value by the acquisition unit 402. The notification unit 403 notifies a user of abnormality of the toner conveyance unit 900 through display of an operation panel 333 of the apparatus main body 1000 illustrated in
In the above-mentioned image formation mode, the control unit 27 can perform first control and second control to control the supply motor 404 (pump 302) so that the quantity of toner supply per unit time from the toner container 13 to the first toner conveyance path 208 becomes a first quantity of supply and a second quantity of supply, respectively. The second quantity of supply is smaller than the first quantity of supply.
Subsequently, an abnormality detection mode for detecting an abnormality of the toner conveyance unit 900 in the present exemplary embodiment will be described with reference to
The condition that toner supplied from the toner container 13 with no toner clogging or no excessive toner accumulation in the toner conveyance unit 900 is conveyed to the development device 9 is hereinafter referred to as “normal”. The condition with toner clogging in the toner conveyance unit 900 is referred to as “abnormal”. The condition that the quantity of toner supplied from the toner container 13 to the toner conveyance unit 900 is greater than the quantity of toner supplied from the toner conveyance unit 900 to the development device 9 and that toner is excessively accumulated in the toner conveyance unit 900 is referred to as “excessive supply”. Possible causes for excessive supply includes the installation environment of the image forming apparatus 1 and tolerances of parts regarding toner conveyance.
The voltage waveform in
The time B is a timing at which time t1 elapses from the time A, and time C is a timing at which time t2 elapses from the time A (t2>t1).
The voltage value rising to High on the cyclic basis between the time A and the time B occurs because the rotation of the cleaning member 217 causes light received by the light receiving portion 216 to be temporarily blocked by the cleaning member 217.
It can be found from the above-mentioned voltage waveform in
The voltage waveform in
The voltage waveform in
Subsequently, an abnormality detection flowchart of the toner conveyance unit 900 will be described with reference to
In
In the second sequence illustrated in
According to the present exemplary embodiment, the abnormality detection mode is divided into two: the first sequence and the second sequence. That contributes to short downtime by not to run the second sequence at the timing when no abnormality is found in the first sequence. In addition, the control unit 27 compares the first accumulated value obtained by accumulating voltage values from the sensor 1516 with the first threshold in step S105. That reduces the effect of variation in voltage values (noise) due to the rotation of the cleaning member 217. Another method may be employed. For example, in step S105, the control unit 27 may compare a first average value obtained by averaging the voltage values for a predetermined period with a third threshold. Similarly, in step S203, the control unit 27 may compare a second average value obtained by averaging the voltage values for a predetermined period with a fourth threshold.
The following method can be used with a configuration of independently driving the cleaning member 217 and the upstream conveyance screw 905. The control unit 27 may stop the driving of the cleaning member 217 at a detection timing with the sensor 1516, and compare a voltage value (first voltage value) itself at a certain timing at the time B or later with a fifth threshold. Similarly, in step S203, the control unit 27 may stop the driving of the cleaning member 217 at a detection timing with the sensor 1516, and compare a voltage value (second voltage value) itself at a certain timing at the time B or later with a sixth threshold.
A second exemplary embodiment according to the present invention will be described. The toner conveyance device 14 according to the second exemplary embodiment will be described in detail with reference to
The sensor 1516 and the light transmitting portion 207 are arranged in the region through which toner discharged from the leading end port 206a of the toner receiving path 206 passes. That configuration allows detection of whether toner is supplied from the toner container 13 to the first toner conveyance path 208. In other words, that configuration allows detection of a remaining toner quantity in the toner container 13. Except for the arrangement of the sensor 1516 and the light transmitting portion 207, the other configurations and operations of the toner conveyance driving device 15 are similar to those of the first exemplary embodiment.
A control unit 270 according to the second exemplary embodiment will be described with reference to the block diagram of
A method of detecting the quantity of remaining toner in the toner container 13 will be now described with reference to
With a large quantity of remaining toner in the toner container 13 as illustrated in
While the supply motor 404 is being driven, the acquisition unit 402 acquires a third accumulated value (third acquired value) obtained by accumulating voltage values (acquired values) output from the sensor 1516 for a predetermined time period. If the third acquired value exceeds a seventh threshold, the remaining toner quantity detection unit 408 determines that there is sufficient toner in the toner container 13. If the third acquired value is below the seventh threshold, the remaining toner quantity detection unit 408 determines that there is a small quantity of toner in the toner container 13 or the toner runs out, and the notification unit 403 notifies the user of the small quantity of toner or the runout of toner.
In the present exemplary embodiment, the sensor 1516 is used in detection of a remaining toner quantity of the toner container 13 and detection of an abnormality in the toner conveyance unit 901.
While the light transmitting portion 207 according to the present exemplary embodiment is disposed so that the light emitting portion 215 and the light receiving portion 216 face each other in the direction orthogonal to the longitudinal direction of the first toner conveyance path 208, the present invention is not limited to that configuration.
Furthermore, the light emitting portion 215 and the light receiving portion 216 are arranged side by side close to the light transmitting portion 207 in the longitudinal direction of the first toner conveyance path 208 outside the first toner conveyance path 208.
The reflective member 220 is disposed to reflect light emitted from the light emitting device 215a of the light emitting portion 215 toward the light receiving element 216a on the light receiving portion 216. That configuration allows light emitted from the light emitting device 215a on the light emitting portion 215 to pass through the light transmitting portion 207, and to be reflected on the reflective member 220 to pass through the light transmitting portion 207 again, and to be received by the light receiving element 216a. Even such a configuration allows detection of the quantity of remaining toner in the toner container 13 according to the second exemplary embodiment and detection of an abnormality in the toner conveyance unit 901 in the second exemplary embodiment. The configuration according to the present modification is also applicable to the configuration according to the first exemplary embodiment.
In the first and second exemplary embodiments, the output value from the sensor 1516 is a voltage value, but may be a current value. Furthermore, as the quantity of light received by the light receiving portion 216 becomes larger in the first and second exemplary embodiments, the output value (voltage value) from the sensor 1516 becomes smaller, but the output value may be reversed such that as the quantity of light received by the light receiving portion 216 becomes larger, the output value from the sensor 1516 becomes larger.
According to the first and second exemplary embodiments, the pump (air) is used as a unit for discharging toner in the toner container 13 from the toner container 13. The configuration however is not limited thereto. A configuration of discharging toner using a conveyance screw may be employed.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention 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. 2021-091609, filed May 31, 2021, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-091609 | May 2021 | JP | national |
