JP2005062503A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a toner replenishment device in which frequency of noise caused by a toner supply/reflux conveying means is minimized and which is friendly in terms of office environment. <P>SOLUTION: The image forming apparatus includes the toner replenishment device. The toner replenishment device conveys fluid of a mixture of toner and air to a toner separation part from a toner storage part by a toner supply fluid conveying means, separates the toner and the air in the toner separation part, conveys the toner from the toner separation part to a development device. The toner replenishment device has a toner flux fluid conveying means for returning the mixture of unseparated residual toner and air to the storage part from the toner separation part. The image forming apparatus is characterized in having a control means which performs control so that the toner supply/reflux fluid conveying means is driven only during the formation of images. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a toner replenishing device of an electrophotographic image forming apparatus.

  Conventionally, in a high-speed image forming apparatus and a color image forming apparatus, since a large amount of toner is consumed in a short time, it is necessary to increase the volume of the toner storage part that stores the toner. There is a problem that it is difficult to arrange them in the space of the machine.

  As a means for solving such a problem, a toner storage section is provided at a location away from the developing device, and a mixed fluid of toner and air, which is capable of conveying the toner far away, is used, for example, a diaphragm pump Discloses a technique for conveying the toner toward the developing device.

  The basic configuration of the toner replenishing device using the air transport includes a toner storage unit, a mixing chamber in the toner storage unit for mixing air and toner, and a toner for transporting a mixed fluid of toner and air from the mixing chamber. A supply fluid conveying means, a toner separating portion for separating the toner from the conveyed mixed fluid, a toner circulation fluid conveying means for returning a part of the air separated from the toner to the mixing chamber without releasing it to the outside, and the like. There are many things of composition.

In the toner supply technology by air conveyance as described above, toner scattering may occur due to the pressure difference between the mixed gas sent to the developing device and the gas returned to the mixing chamber from the developing device, and this pressure difference is adjusted. This technique is also disclosed as publicly known (see, for example, Patent Document 1).
JP 2000-137376 A

  However, noise generated during operation of a drive motor (usually 1000 to 6000 rpm) and a pump, which are toner supply / circulation conveying means for circulating the mixed fluid, is a problem that impairs the office environment.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus having a toner replenishing device that is friendly to the office environment by reducing the frequency of noise generated from the toner supply / circulation conveying means as much as possible.

  A mixed fluid of toner and air is transported from the toner reservoir to the toner separator by the toner supply fluid transport means, the toner separator separates the toner and air, and the toner is transported from the toner separator to the developing device. And an image forming apparatus comprising a toner replenishing device having a toner recirculation fluid conveying means for recirculating a mixture of residual toner and air that could not be separated from the toner separation portion to the toner storage portion. 2. The image forming apparatus according to claim 1, further comprising a control unit that controls the circulating fluid conveying unit to be driven only when image formation is being performed.

  The noise generated by the toner replenishing device is not noticeable because it is mixed with the noise at the time of image formation of the main body of the apparatus. Further, since the toner is not conveyed during idling, the frequency of noise generation of the toner replenishing device is reduced.

  An example of an embodiment of the present invention will be described with reference to the drawings. The description in this column does not limit the technical scope of the claims or the meaning of terms.

  FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus having a toner replenishing device of the present invention.

  In FIG. 1, an automatic document feeder 20 conveys documents placed on the document feeding table one by one to a reading position and accumulates the read documents on a document discharge tray.

  The document reading unit 21 reads an image of a document and generates digital image data.

  The image forming unit 22 forms an image on recording paper by an electrophotographic method.

  In the image forming unit 22, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, a separation device 6, and a cleaning device 7 are disposed around the drum-shaped photoconductor 1. Below the image forming unit 22, a paper feeding unit 23 having a plurality of recording paper storage units is provided to feed the recording paper to the image forming unit 22. Reference numeral 10 denotes a manual sheet feeder. The recording paper fed from the paper feeding unit 23 or the manual paper feeding unit 10 is supplied between the photosensitive member 1 and the transfer device 5 by the registration roller 11, fixed by the fixing device 8, and discharged to the paper discharge tray 12. Is done.

  Corresponding to the clockwise rotation of the photoreceptor 1, a toner image is formed on the photoreceptor 1 by charging by the charging device 2, image exposure by the exposure device 3, and development by the developing device 4. The formed toner image is transferred onto the recording paper by the transfer device 5. The recording sheet on which the toner image has been transferred is subjected to a fixing process in the fixing device 8 and then discharged onto a discharge tray 12.

  The developing device 4 develops the electrostatic latent image on the photoreceptor 1 with a two-component developer containing toner and a carrier or a one-component developer containing no toner or a toner and an additive. A predetermined amount of developer is stored in the developing device 4, and when a two-component developer is used, toner consumed by development is supplied from a toner storage unit 24 described below, The toner density of the developer is always maintained at a predetermined value. In a developing device using a one-component developer, the amount of developer in the developing device is always maintained at a predetermined amount by the same toner replenishment.

  As shown in FIG. 1, in the present invention, the toner reservoir 24 is provided at another position away from the developing device 4. A toner container 31 is attached to the toner reservoir 24, and a toner hopper 30 that guides the toner supplied from the toner container 31 and a funnel-like part that mixes the supplied toner with air generated by a pump described later. The toner separation unit 60 and the toner storage unit 24 disposed in the vicinity of the developing device 4 are connected by pipes 40 to 43 which are transport pipes. The pipes 40 to 43 are at least partly flexible members made of silicone rubber or fluororesin, and metal pipes may be used at least partly.

  Next, the toner supply device will be described with reference to FIGS.

  2 shows a toner replenishing device of the image forming apparatus shown in FIG. 1, and FIG. 3 shows a toner reservoir.

  2 and 3, the toner replenishing device includes a toner reservoir 24, pumps 501 and 502 as toner supply / circulation conveying means, pump motors 55a and 55b, a toner separator 60, pipes 40 to 43, and the like.

  A cylindrical toner container 31 is attached to the toner reservoir 24, and the toner container 31 is rotationally driven by a motor 38, whereby the toner falls from the toner container 31 to the toner hopper 30 through the opening 30a. The toner hopper 30 is provided with a rod-like stirring member 32 formed with a plurality of U-shaped portions and a spiral conveying screw 34 at the bottom. Note that toner supply from the toner container 31 to the toner hopper 30 is performed while the apparatus main body is operating and idling regardless of the operation of the pumps 501 and 502 when the toner amount becomes equal to or less than the toner level sensor 33 in the toner hopper 30. .

  In the toner supply to the mixing chamber 35, the stirring member 32 and the screw 34 are rotated by the rotation of the motor 39, and the toner falls from the toner hopper 30 to the mixing chamber 35 through the opening 30b.

  Since air is fed into the mixing chamber 35 through the pipe 43 as will be described later, a fluid in which toner and air are mixed is formed.

  FIG. 4 is a sectional view of the structure of the diaphragm pump.

  5 is a plan view seen from the direction of arrow E in FIG.

  The toner supply / circulation fluid conveying means in the present embodiment uses pumps 501 and 502 having the same structure, each of which is a diaphragm type pump. The screw pump disclosed in Japanese Patent Laid-Open No. 7-219329 is used. It is also possible to use any known pump, fan or the like.

  As shown in FIG. 2, the pump 501 conveys the mixed fluid of toner and air from the mixing chamber 35 to the toner separation unit 60 through the pipes 40 and 41 as indicated by arrows X1 and X2. The pump 502 circulates residual toner that could not be separated from the air from the toner separation unit 60 to the mixing chamber 35 through the pipes 42 and 43 as indicated by arrows X3 and X4.

  The mixed fluid transported via the pipes 40 and 41 by the transport force of the pump 501 is sent to the toner separation chamber 60 where the separated toner is accumulated. The accumulated toner is dropped into the toner storage buffer 47 by the conveying screw 68, and the toner is supplied to the developing device 4 when necessary.

  In the illustrated example, pumps 501 and 502 having the same structure are used, but different structures may be used for the toner supply fluid transfer means and the toner circulation fluid transfer means.

  In FIG. 4, D indicates a pump unit. The pump unit D is composed of a pump 501 (502), a pump motor 55a (55b) integral with the eccentric rotating member 56, a frame body 58 that supports them, and the like, and two sets of toner supply and toner circulation are the same. A pump unit D having a structure is provided and attached to a frame 70 of an image forming apparatus (hereinafter also referred to as an apparatus main body).

  Next, the pumps 501 and 502 will be described.

  An intake port of the pump 501 is connected to the pipe 40, and an exhaust port is connected to the pipe 41. An intake port of the pump 502 is connected to the pipe 42 and an exhaust port is connected to the pipe 43. The pump chamber formed by the outer wall 50 is partitioned into an intake chamber 50a and an exhaust chamber 50b by an inner wall 51. A valve 53 is provided at the intake port of the intake chamber 50a, and a vent hole (a vent port provided in the inner wall 51). ) Is provided with a valve 54.

  A part of the outer shape of the pumps 501 and 502 is formed by a diaphragm 52 formed of an elastic body made of rubber, and the diaphragm 52 is driven by an eccentric rotating member 56 driven by a pump motor 55a (55b) and is shown by a solid line. And the state shown by the dotted line. Accordingly, the volume of the intake chamber 50a is changed to increase or decrease the pressure in the intake chamber 50a. As the pressure increases or decreases, the valves 53 and 54 are displaced to positions indicated by solid lines and dotted lines, respectively, and the mixed fluid is conveyed in one direction as indicated by arrows.

  Now, when the toner density of the developer in the developing device 4 falls below a predetermined density, a density sensor (not shown) provided in or near the developing device 4 detects it, and a control unit that is a control means that receives the signal The CON rotates the screw 49 so as to supply the toner to the developing device 4 and supplies the toner in the toner storage buffer 47 to the developing device 4. When the toner density of the developer recovers to a predetermined density, the toner supply command is canceled and the toner supply from the toner storage buffer 47 is stopped.

  The toner storage buffer 47 is provided with a piezo sensor 44, and the toner is maintained at a predetermined level or higher, and when the level becomes lower than the level, a signal from the piezo sensor 44 is transmitted to the control unit CON, and the control unit CON receives the pump motor 55a. 55b, the motor 39, and the drive units of the screws 34 and 68 are commanded to operate.

  That is, the motor 39 shown in FIG. 3 is activated to drive the stirring member 32 to stir the toner in the toner hopper 30 and to drive the screw 34 to drop the toner into the mixing chamber 35. The pump motors 55a and 55b In operation, the pumps 501 and 502 are activated. By the operation of the pumps 501 and 502, an air flow is generated in the mixing chamber 35 to mix the toner and air, and the mixed fluid is transported to the toner separation unit 60 through the transport pipes 40 and 41 by the transport force of the pump 501. .

  The toner separated by the toner separation unit 60 is conveyed to the toner storage buffer 47 by the rotation of the screw 68. Further, the mixed fluid of toner and air that could not be separated is circulated to the mixing chamber 35 through the conveying pipes 42 and 43 by the conveying force of the pump 502.

  The air conveyance as described above generates considerable noise, and if the air conveyance happens to be performed during idling other than during the image forming process (operation of the apparatus main body), the office environment may be lowered.

  An object of the present invention is to contribute to the improvement of the office environment by making the noise generated at the time of toner conveyance including the operation sound of the pump unit D inconspicuous.

  That is, by controlling so that the toner transport process by the pump unit is performed while the apparatus main body is being driven at the time of image formation, the noise of the toner transport is made inconspicuous, and when idling is relatively quiet, the pump unit The frequency of noise generation can be reduced by a method that does not operate D.

  FIG. 6 shows a flowchart of the operation process of the apparatus main body and the toner supply device.

  In FIG. 6, S1 to S5 are set as the period of the image forming operation. When the apparatus main body is in an idling state capable of copying, the copy button is pressed in step S1, and the piezo sensor 44 of the toner storage buffer 47 is used for toner in step S2. The presence or absence of the remaining amount is detected. If the toner remaining amount is detected as “present” at this time, image formation is continued in step S4, transfer is performed on the recording sheet in step S5, fixing and paper ejection are performed in step S5, and the process returns to idling. On the other hand, when it is detected in step S2 that the remaining amount of toner is “none”, the toner replenishing device starts operating in parallel with the image forming process in response to a command from the control unit CON in step 3. If the toner amount reaches a predetermined level in the toner storage buffer 47 during the image forming process, the replenishment is stopped. When the image forming process is completed and the idling state is reached without reaching the predetermined level, the toner replenishing device (pump unit) stops the operation and starts again at the next image forming to continue the toner replenishment. To do.

  Therefore, the noise of the toner replenishing device is not noticeable because it is mixed with the noise at the time of image forming of the main body of the apparatus, and the toner is not replenished during idling. Decrease.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus having a toner supply device. 2 shows a toner replenishing device of the image forming apparatus shown in FIG. A toner reservoir is shown. It is sectional drawing of the structure of a diaphragm pump. It is the top view seen from the arrow E direction of FIG. 2 is a flowchart of an operation process of an apparatus main body and a toner supply device.

Explanation of symbols

24 toner storage unit 30 toner hopper 35 mixing chamber 40, 41, 42, 43 pipe 44 piezo sensor 47 toner storage buffer 55a, 55b pump motor 58 frame body 501, 502 pump 60 toner separation unit CON control unit

Claims (2)

A mixed fluid of toner and air is transported from the toner reservoir to the toner separator by the toner supply fluid transport means, the toner separator separates the toner and air, and the toner is transported from the toner separator to the developing device. And an image forming apparatus comprising a toner replenishing device having a toner recirculation fluid conveying means for recirculating a mixture of residual toner and air that could not be separated from the toner separation portion to the toner storage portion. 2. The image forming apparatus according to claim 1, further comprising a control unit that controls the circulating fluid conveying unit to be driven only when image formation is being performed. The image forming apparatus according to claim 1, wherein the toner supply from the toner container to the toner storage unit can be performed during an image forming operation and idling.

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