JP3637204B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that collects toner remaining after image forming processing and returns the collected toner as recycled toner to a toner replenishing unit that replenishes toner to the developing device.
[0002]
[Prior art]
An electrophotographic copying type image forming apparatus such as a copying machine, a printer, or a facsimile forms an electrostatic latent image on a photoconductor as a uniformly charged image carrier by exposure, optical writing, or the like. The image is visualized using, for example, a two-component developer toner in which a magnetic carrier and a toner are mixed or a one-component developer in which both are integrated, and the visible image is transferred to a transfer material. To obtain a copy.
[0003]
In the image forming apparatus, a cleaning device is provided for removing toner remaining on an image carrier such as a photosensitive member or an intermediate transfer member after a visible image is transferred. In other image forming portions such as a transfer belt and a transfer device that transfers a transfer material having a transferred visible image to a fixing device, toner that has not been finally used for image formation remains. Some are also equipped with a cleaning device. In many conventional image forming apparatuses, the residual toner collected by the cleaning is collected as it is in a disposal bottle and disposed.
[0004]
However, in recent years, effective use of resources has been demanded, and the collected toner has also been required to be reused. Therefore, many recycling mechanisms have been proposed in which the toner collected by the cleaning device is transferred to a developing device or a toner replenishing device.
[0005]
However, when the recycled toner is actually reused, the collected toner contains paper powder, and there are not a few toner nuclei (a toner aggregate) much larger than the appropriate size. For this reason, if such collected toner is returned to the developing device as it is, abnormal images often occur such as white spots and black spots caused by these paper dusts and toner aggregates, and there is a problem in terms of image quality. .
[0006]
In order to solve such a problem, it has been proposed to provide a recycle knit that distinguishes the collected toner into an appropriate toner suitable for recycling and an unsuitable toner that is highly likely to deteriorate the image quality. This recycling unit is intended to separate the recyclable toner that has entered the filter by having the mesh portion into the filter and has passed through the mesh portion, and the paper powder and toner aggregate that cannot pass through the mesh portion.
[0007]
By the way, the recycled toner obtained through the recycling unit is transferred to the toner replenishing section by the toner transfer device. As this toner transfer device, Japanese Patent Application Laid-Open No. 7-219329 discloses a rotor that rotates to move the toner of developer in the axial direction, a passage that encloses the rotor, and a contact between the rotor and the passage. Mixing of toner and air using a screw pump called a MONO pump having a fixed stator to be joined and an air supply means for supplying air for fluidizing the developer moving by the screw pump It is disclosed to transfer air through a flexible pipe.
[0008]
Since this toner transfer device can transfer toner through a flexible pipe or the like, it can be reliably transferred with a simple configuration without any restrictions on the positions of the toner transfer source and transfer destination. There are advantages. In addition, the toner transfer device using a screw pump can be used in a state where a mixture of air and air is fluidized by an air supply means and transported in a state where the toner is stably transferred and is unnecessary for the toner to be transferred. The toner is less likely to agglomerate and heat-seal the transfer toner without giving more stress.
[0009]
In the toner transfer device using the screw pump described above, sealing of the rotor and the stator is indispensable for reliably transporting the toner in the elastic tube as a gas mixture with the gas. The contact surface with the inner peripheral surface must maintain a certain amount of biting. However, the amount of biting decreases with time due to the elongation and wear of the inner peripheral surface of the stator due to the rotational friction between the rotor and the stator, the sealing performance is deteriorated, and the quality of the collected toner is lowered (cannot be conveyed and backflow and scattering occur). For this reason, it is advantageous for extending the life of the toner transfer device using a screw pump to be intermittently driven. Furthermore, since the toner transfer device transfers the recycled toner in a mixed gas state, it is preferably intermittently driven in order to prevent toner scattering in a toner hopper as a toner supply unit that supplies toner to the developing device.
[0010]
[Problems to be solved by the invention]
However, the amount of toner input to the recycling unit varies depending on the user and mode. Therefore, when the intermittent drive of the transfer device is performed at regular intervals, if the time during which the intermittent drive is stopped is set short, the pump may be short-lived and toner may be scattered. In addition, if the stopping time is long, the amount of recycled toner may exceed the toner transfer capability. In this case, the pump may be clogged and the recycling unit may be damaged.
[0011]
The present invention solves the above-described conventional problems and extends the pump life and prevents toner scattering at the toner replenishing portion by performing intermittent drive of the toner transfer device using a screw pump at a good timing. An object of the present invention is to provide an image forming apparatus capable of performing the above.
[0012]
[Means for Solving the Problems]
In order to solve the above-described object, the present invention provides an image forming apparatus that collects toner remaining after image forming processing and returns the collected toner as recycled toner to a toner replenishing unit that replenishes toner to the developing device. A recycling unit for separating the collected toner into recycled toner and waste, a screw pump and an air supply means, and transporting the recycled toner separated from the recycling unit to the toner replenishing unit as a gas mixture with a gas flow And a toner transfer unit that operates intermittently according to the amount of toner input to the recycle unit.
[0013]
The present invention is effective when the operation of the toner transfer means is intermittently driven according to the amount of toner supplied from the toner supply unit to the developing device.
[0014]
Furthermore, in order to solve the above-described object, the present invention collects toner remaining after image forming processing, and returns the collected toner as recycled toner to a toner replenishing unit that replenishes toner to the developing device. In the apparatus, the toner replenishing unit includes a recycling unit that separates the collected toner into recycled toner and waste, a screw pump and an air supply unit, and the recycled toner separated from the recycling unit is used as a gas mixture with a gas flow. A toner transfer means for transferring the toner to the toner supply means, and the operation of the toner transfer means reaches a specified time when the operation cumulative time of the replenishment clutch that operates when toner is replenished from the toner replenishing section, or the operation of the replenishment clutch Even if the accumulated time does not reach the specified time, the accumulated operation time of the main motor of the main unit is regulated. It is characterized in that it is intermittently driven when reaching the time.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view of an image forming apparatus according to the present invention.
[0016]
In FIG. 1, reference numeral 1 denotes a photosensitive drum as an image carrier, and when this photosensitive drum 1 is rotationally driven in the direction of an arrow, image exposure is performed on a portion uniformly charged by a charger 2 (see FIG. 1). (Not shown), and an electrostatic latent image is formed on the photosensitive drum 1. The latent image is visualized as a toner image by the developing device 12. On the other hand, the transfer paper P is conveyed from a paper supply unit (not shown) to the image forming unit via the registration roller 14, and a toner image on the photosensitive drum 1 is transferred by a transfer device having a transfer belt 40. 40 is sent to a fixing device (not shown).
[0017]
The toner that is not transferred to the transfer paper and remains on the photosensitive drum 1 is scraped off by the cleaning blade 31 of the cleaning device 30 and is conveyed to a recycling unit provided on the inner side of the apparatus main body by a conveying screw or the like. The surface of the transfer belt 40 is also soiled by toner on the photosensitive drum 1 and paper dust from the transfer paper. However, the toner and paper dust are scraped off by a belt cleaning device 41 having a cleaning blade 42, and this toner is also conveyed. It is transported to the recycling unit by screws.
[0018]
FIG. 2 is a cross-sectional configuration diagram showing the configuration of the recycling unit 50.
In FIG. 2, reference numeral 51 denotes a casing of the recycling unit 50, and a receiving port 52 for receiving the toner collected by the cleaning devices 30 and 41 is formed on the upper right side of the casing 51. A conveying screw 53 that conveys the collected toner to the left is provided below the receiving port 52, and one end of the conveying screw 53 is connected to the drive shaft 54. The drive shaft 54 protrudes out of the casing, and is externally connected to the drive motor 58 via gears 55, 56 and 57. The other end of the conveying screw 53 is connected to a classification mesh member 60 formed in a cylindrical shape for separating recycled toner and waste toner, and the drive shaft 56, the conveying screw 53, and the classification mesh member 60 are aligned. It is connected to. In this example, the straight drive shaft 56, the conveying screw 53, and the classification mesh member 60 are connected in the horizontal direction.
[0019]
In the classification mesh member 60, a frame 62 formed in a cylindrical shape is fixed to a support shaft 61 that is directly connected to the conveying screw 53, and a mesh 63 is wound around the outer periphery of the frame 62. A cylindrical member 64 having a diameter slightly smaller than the diameter of the mesh 63 is provided on the left side of the classification mesh member 60 in the drawing, and a discharge port 65 for waste toner is formed in the cylindrical member 64.
[0020]
Below the classification mesh member 60, a conveying screw 70 for conveying the recycled toner to the left in the figure is provided. One end of the conveying screw 70 jumps out of the casing and is connected to the shaft 56a of the gear 56 via the clutch 71. ing. A screw pump 72 is provided at the other end of the conveying screw 70.
[0021]
The screw pump 72 includes a female threaded stator 74 formed with a double pitch spiral groove made of an elastic body such as rubber, and a male threaded rotor 73 that is rotatably inserted into the stator 74. The rotor 73 is connected to the other end of the shaft of the conveying screw 70 so as to coincide with the axis. Therefore, when the clutch 71 is turned on, the drive of the drive motor 58 is transmitted to the conveying screw 70 and the screw pump 72. The stator 74 is inserted into a holder 75 to which a casing is attached. The holder 75 fixes the stator 74 so as to cover the periphery of the stator 74. A toner discharge port 76 is formed in the holder 75, and one end of a toner transport tube 77 as a transfer path is fitted into the toner discharge port 76. The toner conveying tube 77 can be a flexible hose or the like. Further, a gap 78 is provided between the inner peripheral surface of the holder 75 and the outer peripheral surface of the stator 74, and this gap 78 communicates with the toner discharge port 76. The holder 75 is provided with an air supply port 79 communicating with the gap 78, and the air supply port 79 is connected to the air pump 80 via an air supply tube 81.
[0022]
Further, as shown in FIGS. 1 and 3, the other end of the toner transport tube 77 is connected to a toner hopper 15 as a toner replenishing unit that replenishes toner to the developing device 12, and the toner hopper 15 receives a signal such as toner density detection. The toner developing device 12 is replenished by operating a clutch (not shown).
[0023]
In the image forming apparatus configured as described above, the collected toner sent to the recycling unit 50 from the receiving port 52 is sent to the classification mesh member 60 by the conveying screw 53, and only the toner that has not aggregated and become large particles is mesh 63. The toner containing the large toner, the paper fiber, and the additive moves to the cylindrical member 64 and falls from the discharge port 65, so that the waste toner such as the recycled toner and the waste toner is removed. It is separated into. The recycled toner that has passed through the mesh 63 and dropped below the classification mesh member 60 is transported to the screw pump 72 by the transport screw 70 and is transported to the toner hopper 15 by the pump. Further, the waste toner falling from the discharge port 65 of the cylindrical member 64 may be directly received by a waste container, or once received, it may be transported to a waste container by an appropriate toner transport means.
[0024]
The image forming apparatus configured as described above is provided with an input toner detector 90 that detects toner input to the unit at the receiving port 52. Then, the collected toner input to the recycle unit 50 is monitored, and the operation of the screw pump 72 and the air pump 80 is controlled in accordance with the input toner amount as described below.
[0025]
FIG. 4 is a control flow for operating the screw pump 72 and the air pump 80 intermittently.
In FIG. 4, when the power of the image forming apparatus is turned on (step 1) and copying is started (step 2), the toner detector 90 detects the input toner to the recycle unit 50 and starts to accumulate the amount (step). 3). Then, it is determined whether the input toner amount has reached the predetermined amount X (step 4). When the predetermined amount X is reached, the screw pump 72 and the air pump 80 are operated for a predetermined time (step 5). Then, the integration of the input toner amount is reset (step 6), and the process returns to step 3 again.
Thus, by operating the screw pump 72 and the air pump 80 when the input toner amount reaches a certain amount, it is possible to extend the life of the screw pump 72 and to prevent the toner popper 15 from scattering the toner.
[0026]
By the way, in the above embodiment, the input toner is detected by the detector 90, but the recovered toner amount can also be estimated from the toner supply amount supplied to the developing device. In the case of a two-component developing device, in order to keep the developer concentration in the developing device constant, the toner is replenished in approximately the same amount as consumed in image formation, and the recovered toner amount is calculated from this toner replenishment amount. I can guess. In other words, it has been empirically found that the amount of collected toner is approximately 1 fixed amount (about 10%) of the consumed toner becomes the collected toner. Therefore, the amount of collected toner is input to the recycling unit 50 by monitoring the toner replenishment amount. The toner amount can be estimated.
[0027]
In FIG. 5, the power supply of the image forming apparatus is turned on (step 1), and when copying is started (step 2), integration of the on time of the replenishment clutch is started (step 3). Next, it is determined whether or not the ON time of the replenishing clutch has reached the specified T time (step 4). When the T time is reached, the screw pump 72 and the air pump 80 are operated for a predetermined time (step 5). Then, the integration of the ON time of the replenishing clutch is reset (step 6), and the process returns to step 3 again.
[0028]
With this configuration, the intermittent drive of the screw pump 72 and the air pump 80 can be controlled without using the input toner detector 90.
By the way, in the above control, there may occur a case where the screw pump 72 and the air pump 80 are not operated for a long time after a copy with little toner replenishment. At this time, in the worst case, there is a risk that the toner is fixed inside the toner conveying tube 77 or the toner is hardened before the screw pump 72. FIG. 6 shows an example of control that can avoid such danger. In this example, the intermittent drive of the screw pump 72 and the air pump 80 is controlled by monitoring the ON time of the replenishing clutch and the ON time of the main motor (not shown) of the apparatus main body.
[0029]
In the example of FIG. 6, only differences from FIG. 5 will be described. In step 3, integration of the ON time of the replenishing clutch and integration of the ON time of the main motor are started. When it is determined in step 4 whether the on time of the replenishing clutch has reached the prescribed T1 time, if the T1 time has been reached, the routine proceeds to step 5, but if the T1 time has not been reached, the main motor on time has been reached. It is determined whether or not the T2 time defined by has been reached (step 7). If the time T2 has been reached, the process proceeds to step 5. If the time T2 has not been reached, the process returns to step 4 again.
[0030]
By controlling in this way, the screw pump 72 and the air pump 80 can be operated if the clutch of the toner hopper 15 is operated and a certain amount of toner is input to the recycling unit 50, and the input toner is very little. Even so, the screw pump 72 and the air pump 80 can be moved from the on-time of the main motor. Therefore, this control can prevent toner sticking in the toner transport tube 77 and the like due to the screw pump 72 and the air pump 80 being stopped for a long period of time.
[0031]
【The invention's effect】
According to the configuration of the first aspect, since the screw pump and the air pump are intermittently operated according to the amount of collected toner input to the recycling unit, the life of the screw pump is extended and toner scattering at the toner supply unit is prevented. can do.
[0032]
According to the configuration of claim 2, in addition to the effect of claim 1, it is possible to know the amount of collected toner input to the recycling unit without using a detector.
[0033]
According to the configuration of claim 3, in addition to the effects of claims 1 and 2, the screw pump and the air pump are moved according to the on time of the main motor even when there is almost no input toner. Toner sticking can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present invention.
FIG. 2 is an explanatory cross-sectional view showing an example of a recycling unit.
FIG. 3 is an external view of the developing device.
FIG. 4 is a flowchart illustrating intermittent drive control in the toner transfer device.
FIG. 5 is a flowchart showing another intermittent drive control in the toner transfer device;
FIG. 6 is a flowchart showing still another intermittent drive control in the toner transfer device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photoconductor 12 Developing device 15 Toner hopper 30 Cleaning device 40 Transfer belt 50 Recycling unit 72 Screw pump 80 Air pump 90 Toner detector

Claims (3)

In an image forming apparatus that collects toner remaining after image forming processing and returns the collected toner as a recycled toner to a toner replenishing unit that replenishes toner to the developing device.
A recycling unit for separating the collected toner into recycled toner and waste, a screw pump and an air supply means are provided, and the recycled toner separated from the recycling unit is transferred to the toner replenishing unit as a mixture with a gas flow. An image forming apparatus comprising: a toner transfer unit, wherein the operation of the toner transfer unit is intermittently driven according to the amount of toner input to the recycle unit.   The image forming apparatus according to claim 1, wherein the operation of the toner transfer unit is intermittently driven according to the amount of toner supplied from the toner supply unit to the developing device. In an image forming apparatus that collects toner remaining after image forming processing and returns the collected toner as a recycled toner to a toner replenishing unit that replenishes toner to the developing device.
A recycling unit for separating the collected toner into recycled toner and waste, a screw pump and an air supply means are provided, and the recycled toner separated from the recycling unit is transferred to the toner replenishing unit as a mixture with a gas flow. A toner transfer means, and when the operation of the toner transfer means reaches a specified time of operation of a replenishment clutch that operates when toner is replenished from the toner replenishing unit, or the operation accumulated time of the replenishment clutch An image forming apparatus that is intermittently driven when an accumulated operation time of a main motor of the apparatus main body reaches a specified time without reaching a specified time .

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