JP2004184680A - Toner replenishing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner replenishing apparatus realizing the improvement of the efficiency of maintenance work by smoothly carrying toner from a toner storage part to a developing device by air and eliminating soiling by toner. <P>SOLUTION: In the toner replenishing apparatus, the mixture fluid of the toner and the air is carried to a toner separation part from the toner storage part by a fluid carrying means for supplying toner, the toner is separated from the air at the toner separation part, and the developing device is replenished with the toner from the toner separation part. The replenishing apparatus has a fluid carrying means for refluxing toner to reflux the mixture of the toner and the air, not separated perfectly from each other, from the toner separation part to the toner storage part. Then, the replenishing apparatus is constituted to detect and control the revolving speed of a pump motor constituting the fluid carrying means for supplying the toner and the fluid carrying means for refluxing the toner. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a toner supply device for an electrophotographic image forming apparatus.
[0002]
[Prior art]
In a high-speed image forming apparatus or a color image forming apparatus, there is a problem that it is difficult to arrange the toner storing section near the developing device because the volume of the toner storing section for storing the toner becomes large.
[0003]
As a means for solving such a problem, a toner replenishing technique has been developed in which toner is transported from a toner storage section to a developing device by a toner transport method called air transport that can transport toner to a distant place. Reference 1, Patent Document 2, Patent Document 3, Patent Document 4, etc.).
[0004]
The basic configuration of a toner replenishing device using air conveyance includes a toner storage unit, a fluid conveyance unit that conveys a mixed fluid of toner and air from the toner storage unit, and a toner separation unit that separates toner from the conveyed mixed fluid. Etc.
[0005]
In many cases, a part of the air separated from the toner is returned to the fluid conveying means without being released to the outside. The toner separating section is provided with a filter for preventing the toner from scattering to the outside, and only a part of the air is released to the outside to adjust the pressure in the conveying path.
[0006]
[Patent Document 1]
JP-A-7-219329 (column 5, line 2 to line 7)
[0007]
[Patent Document 2]
JP-A-10-97130 (column 10, line 5 to line 14)
[0008]
[Patent Document 3]
JP-A-10-268641 (Claims)
[0009]
[Patent Document 4]
JP-A-10-299672 (Claims)
[0010]
[Problems to be solved by the invention]
In each of the toner replenishing techniques disclosed in the above-mentioned publications and other publications, a mixed fluid of toner and air is transported from a toner reservoir to a developing device by a fluid transporting unit such as a pump. However, in the related art, the toner is transported only to a toner separating unit disposed at a position sufficiently distant from the toner storing unit by a fluid transporting unit including a pump that transports a mixed fluid of air and toner. May not be sufficient, resulting in poor conveyance. For this purpose, it is necessary to increase the size of the pump. However, when the size is increased, the amount of exhaust air to the outside through the filter provided in the toner separation unit increases, the amount of toner adhering to the filter increases, and the filter needs to be quickly inspected. A troublesome operation such as clogging occurs and toner scattering may occur, and a filter must be replaced at the time of periodic inspection. Further, the pressure balance is lost due to variations in the number of revolutions of the pump motor and the like, and a difference from the outside air pressure is generated, which also causes toner scattering.
[0011]
An object of the present invention is to solve the above-mentioned problems in the conventional toner supply technology using air conveyance, remove a filter that directly contacts the outside air, set a toner conveyance destination as a closed space, and perform rotation control of a pump motor. It is therefore an object of the present invention to provide a toner replenishing apparatus which does not require filter replacement and has improved maintenance by keeping the pressure of the entire air recirculation system as constant as possible.
[0012]
[Means for Solving the Problems]
The above object can be achieved by the following configurations.
[0013]
(1) A mixed fluid of toner and air is transported from the toner storage section to the toner separation section by a toner supply fluid transport section, and the toner separation section separates the toner and air from the toner separation section. A toner replenishing device having a toner recirculating fluid conveying means for conveying the toner to the toner storage unit and recirculating a mixture of the residual toner and air which cannot be completely separated from the toner separating unit to the toner storing unit. And a recirculation path from outside air to a hermetically closed state, and detects and controls the number of rotations of a toner supply fluid transport unit and a pump motor constituting the toner recirculation fluid transport unit (first invention) ).
[0014]
(2) A mixed fluid of toner and air is transported from the toner storage section to the toner separating section by a toner supply fluid transporting section, and the toner separating section separates the toner and air from the toner separating section. A toner recirculating fluid transporting means for transporting the toner to the toner separating section and recirculating a mixture of the residual toner and air which cannot be separated from the toner separating section to the toner storing section. Has a toner transport path, at least a part of which is formed of a flexible pipe made of resin or rubber, a metal member is adhered to at least a part of the pipe, and the member is A toner replenishing device characterized by being grounded (second invention).
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
An example of an embodiment of the present invention will be described with reference to the drawings. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms.
[0016]
FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus having the toner supply device of the present invention.
[0017]
In FIG. 1, the automatic document feeder 20 conveys the documents placed on the document feed tray one by one to a reading position and stacks the read documents on a document discharge tray.
[0018]
The document reading unit 21 reads a document image and generates digital image data.
The image forming unit 22 forms an image on recording paper by an electrophotographic method.
[0019]
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 arranged around the drum-shaped photoconductor 1. Below the image forming unit 22, a paper feed unit 23 having a plurality of recording paper storage units is provided, and feeds recording paper to the image forming unit 22. Reference numeral 10 denotes a manual paper feed unit. The recording paper fed from the paper feeding unit 23 or the manual paper feeding unit 10 is supplied between the photoconductor 1 and the transfer device 5 by the registration roller 11, fixed by the fixing device 8, and discharged to the paper output tray 12. Is done.
[0020]
In response to the clockwise rotation of the photoconductor 1, a toner image is formed on the photoconductor 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 to recording paper by the transfer device 5. The recording paper to which the toner image has been transferred is discharged to a discharge tray 12 after being subjected to a fixing process in the fixing device 8.
[0021]
The developing device 4 develops the electrostatic latent image on the photoconductor 1 with a two-component developer containing a toner and a carrier or a one-component developer containing no toner or a toner and an additive without a carrier. The developing device 4 contains a predetermined amount of developer. When a two-component developer is used, the toner consumed by the development is supplied from a toner storage unit 24 described below, and The toner concentration of the developer is always maintained at a predetermined value. In a developing device using a one-component developer, the amount of the developer in the developing device is always maintained at a predetermined amount by the same toner replenishment.
[0022]
A toner container 31 is attached to the toner storage section 24. The toner storage unit 24 includes a toner hopper 30 and a funnel-shaped toner / air mixing chamber 35, and includes a toner separation unit 60 disposed near the developing device 4 and a toner storage unit provided at a position distant from the developing device 4. 24 is connected by pipes 40 to 43 which are transport pipes. At least a part of the material of the pipes 40 to 43 is a flexible member made of silicone rubber or fluorine resin, and at least a part of the pipe is made of a metal pipe.
[0023]
Next, the toner supply device will be described with reference to FIGS.
FIG. 2 shows a toner replenishing device of the image forming apparatus shown in FIG. 1, and FIG. 3 shows a toner storing section.
[0024]
The toner replenishing device includes the toner storage unit 24, pumps 501 and 502 as fluid supply means for toner supply and toner recirculation, a toner separation unit 60, and pipes 40 to 43 serving as a toner conveyance path.
[0025]
In FIG. 3, a cylindrical toner container 31 is attached to the toner storage portion, and the toner container 31 is rotated by a motor 38 so that the toner falls from the toner container 31 to the toner hopper 30 through the opening 30 a. The toner hopper 30 is provided with a rod-shaped agitating member 32 having a plurality of U-shaped portions formed thereon, and a transport screw 34 provided below.
[0026]
The rotation of the motor 39 rotates the stirring member 32 and the screw 34, and the toner drops from the toner hopper 30 to the mixing chamber 35 through the opening 30 b.
[0027]
Since air is fed into the mixing chamber 35 via a pipe 43 as described later, a fluid in which toner and air are mixed is formed.
[0028]
FIG. 4 is a sectional view of the structure of the diaphragm pump.
Pumps 501 and 502 composed of a diaphragm pump shown in FIG. 4 are used as the toner supply / toner recirculation fluid transport means, and any known pump such as a screw pump disclosed in JP-A-7-219329 is used. A pump, a fan, or the like can be used. The pump 501 constitutes a toner supply fluid conveying means for conveying a mixed fluid of toner and air from the mixing chamber to the toner separating section, and the pump 502 transfers the toner and air which cannot be separated from the toner separating section to the mixing chamber. This constitutes a toner circulating fluid transport unit that circulates the toner. Further, in the illustrated example, the pumps 501 and 502 having the same structure are used, but different pumps may be used for the toner supply fluid transport unit and the toner recirculation fluid transport unit.
[0029]
Next, the pumps 501 and 502 will be described with reference to FIG. The pumps 501 and 502 have the same structure as shown in FIG.
[0030]
The intake port of the pump 501 is connected to the pipe 40, and the 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 by an inner wall 51 into an intake chamber 50a and an exhaust chamber 50b. ) Is provided with a valve 54.
[0031]
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. The diaphragm 52 is driven by an eccentric rotating member 56 driven by a motor 55, and is shown by a solid line and a dotted line. Transform into a state.
[0032]
The eccentric rotary member 56 is rotated by the pump motor 55a (55b), and the rotation causes the diaphragm 52 to be deformed between a state shown by a solid line and a state shown by a dotted line, thereby changing the volume of the intake chamber 50a and reducing the pressure in the intake chamber 50a. Increase or decrease. Due to the increase or decrease of the pressure, the valves 53 and 54 are deformed into the state shown by the solid line and the state shown by the dotted line, respectively, and transport the fluid in one direction as shown by the arrow.
[0033]
Conventionally, the pressure balance between the pipe 41 and the pipe 42 may be lost due to a variation in the number of revolutions of the pump motor 55a (55b) or the like. Part of the air was released to the outside to adjust the air pressure. However, as described above, the filter is clogged at an early stage, toner is scattered, and a troublesome operation of regular replacement of the filter is required.
[0034]
The first invention is characterized in that the device structure does not require such a troublesome operation such as filter replacement.
[0035]
That is, in the supply and recirculation path of the toner sealed from the outside air, the pump motor 55a (55b) has its rotation speed detected by, for example, an optical tachometer 57 as a detection means. By controlling the rotation speed to a predetermined value, a smooth air flow can be obtained, the pressure in the toner supply and the circulation path can be kept constant, and the filter required for adjusting the pressure difference from the outside air can be removed. Can be eliminated. The ratio of the rotational speeds of the pump motors 55a to 55b is set based on data obtained by experiments in advance so that the intake and exhaust volumes of both pump motors are substantially the same, and controlled according to the rotational speed ratio program. The pump motors 55a and 55b rotate according to a command from the unit 58.
[0036]
Next, the toner separating unit 60 will be described.
FIG. 5 is a cross-sectional view showing the structure of the toner separating section.
The toner separating section 60 has an outer wall 61 forming the outer diameter of the toner separating section 60, an inner wall 65 for separating the inside of the toner separating section 60 into an introduction chamber 60A and an exhaust chamber 60B, and an auxiliary inner wall 66.
[0037]
An air inlet 62 is provided in the introduction chamber 60A, and an air outlet 63 is provided in the exhaust chamber 60B. The auxiliary inner wall 66 guides the fall of the toner and suppresses the rise of the toner in the introduction chamber 60A. A stirring member 67 having wings and a screw 68 for conveying the toner in the axial direction are provided below the toner separating unit 60. The mixed fluid of the toner and the air is introduced from the air introduction port 62 into the introduction chamber 60A as indicated by an arrow W1, and falls as indicated by W2. Although the mixed fluid is filled in the introduction chamber 60A, the mixed fluid is partially raised as shown by an arrow W3 and transferred to the exhaust chamber 60B by receiving the pressure by the fluid transfer force by the pump 502 (see FIG. 2). Due to the specific gravity of the toner and the action of the auxiliary inner wall 66, the toner concentration in the mixed fluid that rises in the direction indicated by the arrow W3 decreases, and the fluid becomes almost fluid. The mixed fluid in the exhaust chamber 60B is discharged from the air discharge port 63 as shown by an arrow W4.
[0038]
As shown in the drawing, the vertical path 65A and the vertical section 64A of the inner wall 65 form a communication path in which the mixed fluid meanders. Due to such a meandering communication path, the toner content in the discharged air has a low value. The vertical portions 65A and 64A are cylindrical, and have a configuration in which the cylinder of the vertical portion 64A is disposed within the cylinder of the vertical portion 65A.
[0039]
As shown in FIG. 2, the mixing chamber 35, the pumps 501 and 502, and the toner separating unit 60 are connected by pipes 40, 41, 42, and 43.
[0040]
The mixed fluid is conveyed by the pump 501 from the mixing chamber 35 to the pump 501 as indicated by an arrow X1 and from the pump 501 to the toner separating unit 60 as indicated by an arrow X2 to supply toner. The air circulates from the toner separating section 60 to the pump 502 as shown by, and from the pump 502 to the mixing chamber 35 as shown by the arrow X4. Then, the toner is separated in the toner separating unit 60, and the toner is supplied to the developing device 4 (see FIG. 1) by the screw 68.
[0041]
According to a second aspect of the present invention, it is possible to prevent a problem that the toner is charged due to friction while the toner is conveyed inside the pipe, and the conveyance of the toner is prevented due to the adhesion of the toner in the pipe. For this purpose, the pipe is made of a resin having a predetermined electric resistivity or less, and a metal ground member 44 is wound around the pipe, or a metal pipe 45 is used in the middle of the pipe, and the ground is used. It is characterized by improved points.
[0042]
The toner supply device shown in FIGS. 2 to 5 operates as follows.
The amount of toner in the toner hopper 30 is detected by a toner sensor 33 using a piezo element, and when the toner level falls below the level detected by the toner sensor 33, a motor 38 operates to transfer the toner from the toner container 31 to the toner hopper 30. Replenish.
[0043]
In response to a replenishment signal for replenishing toner to the developing device 4 from control means (not shown), the motor 39 shown in FIG. 3 is operated to drive the stirring member 32 to stir the toner in the toner hopper 30 and to drive the screw 34. The toner is dropped into the mixing chamber 35. In response to the supply signal, the pump motors 55a and 55b operate and the pumps 501 and 502 operate. By the operation of the pumps 501 and 502, an airflow is generated in the mixing chamber 35 to mix the toner and the air, and the mixed fluid is conveyed to the toner separating unit 60 via the pipes 40 and 41 by the conveying force of the pump 501.
[0044]
The toner separated by the toner separating section 60 is supplied to the developing device 4 by the screw 68. Further, the mixture of the toner and the air that cannot be completely separated flows back to the mixing chamber 35 via the transport pipes 42 and 43 by the transport force of the pump 502.
[0045]
【The invention's effect】
By controlling the pump motor, which operates the pumps of the toner supply fluid transport unit and the toner recirculation fluid transport unit, to a predetermined number of revolutions, the pressure change in the toner transport path sealed from the outside air is reduced, and the toner is smoothly distributed. Can be conveyed, so that a conventional filter that causes toner scattering is not required, and troublesome operations such as filter replacement during maintenance can be omitted.
[0046]
Further, by taking measures to prevent the ground member from being charged, the toner can be smoothly transported.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus having a toner supply device according to the present invention.
FIG. 2 shows a toner supply device of the image forming apparatus shown in FIG.
FIG. 3 shows a toner storage section.
FIG. 4 is a sectional view of the structure of the diaphragm pump.
FIG. 5 is a cross-sectional view illustrating a structure of a toner separating unit.
24 Toner storage unit 30 Toner hopper 35 Mixing chambers 40, 41, 42, 43 Pipe 44 Ground members 55a, 55b Pump motor 60 Toner separation unit 501, 502 Pump

Claims (3)

The mixed fluid of toner and air is transported from the toner storage section to the toner separating section by a toner supply fluid transporting section, the toner is separated from the air in the toner separating section, and the toner is transferred from the toner separating section to the developing device. A toner supply and recirculation path in a toner replenishing apparatus having a toner recirculation fluid conveyance unit for conveying and recirculating a mixture of residual toner and air that cannot be completely separated from the toner separation unit to the toner storage unit A toner replenishing device for detecting the number of rotations of a pump motor constituting a toner supply fluid transport unit and a toner recirculation fluid transport unit. The mixed fluid of toner and air is transported from the toner storage section to the toner separating section by a toner supply fluid transporting section, the toner is separated from the air in the toner separating section, and the toner is transferred from the toner separating section to the developing device. In a toner replenishing apparatus having a toner recirculating fluid conveying unit for conveying and recirculating a mixture of residual toner and air that cannot be completely separated from the toner separating unit to the toner storing unit, each conveying unit includes It has a transport path, at least a part of each transport path is made of a flexible pipe made of resin or rubber, and a metal member is attached to the outside of at least a part of the pipe, and the member is grounded. A toner supply device. 3. The toner replenishing device according to claim 2, wherein at least a part of the pipe is formed of a metal pipe, and the metal pipe is grounded.

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