JP3967179B2 - Developer supply device and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developer supply device and an image forming apparatus using a powder pump.
[0002]
[Prior art]
In a conventional image forming apparatus, a toner storage container such as a toner bottle or a toner cartridge is set in the main body of the image forming apparatus, and toner is supplied from the container to the developing unit. Since the conventional toner transfer technology is based on a mechanical auger means, the toner replenishing device and the toner storage container have to be installed at a position integrated with or very close to the developing device.
[0003]
On the other hand, the applicant of the present application has previously proposed a toner replenishing device that replenishes toner from a toner storage container to a developing device by a suction type powder pump without using a mechanical auger means.
[0004]
In some toner replenishing devices using the powder pump, toner collected from an image carrier (photosensitive member) by a cleaning device is reused. FIG. 3 is a cross-sectional configuration diagram for explaining a toner recycling mechanism in a conventional toner replenishing device using a powder pump.
[0005]
In FIG. 3, new (unused) toner is stored in the toner cartridge 20. A powder pump 40 is attached to the developing device 10. A cleaning device 9 is attached to an image carrier (not shown) to which toner is applied from the developing device and the latent image is developed. The toner transport tube 56 from the toner cartridge 20 and the toner transport tube 57 from the cleaning device 9 are connected to a merging pipe 59 and further connected to the powder pump 40 by a toner transport tube 58.
[0006]
The new toner in the toner cartridge 20 is agitated and fluidized by the air supplied from the air pump 30A. The new toner is sucked by the powder pump 40 and supplied to the developing device 10. The supply timing and supply time of the new toner are controlled by controlling the powder pump 40 and the air pump 30A by the control unit of the image forming apparatus main body.
[0007]
On the other hand, the recycled toner collected from the image carrier by the cleaning device 9 is easily sucked by supplying air to the toner discharge portion 9a of the cleaning device from the air pump 30B in a timely manner, and is sucked by the powder pump 40. , Supplied to the developing device 10. The supply timing and supply time of the recycled toner are controlled by controlling the powder pump 40 and the air pump 30B by the control unit of the main body of the image forming apparatus.
[0008]
Then, the amount of new toner that needs to be supplied to the toner consumed in the developing device 10 and the recycled toner collected by the cleaning device 9 should be discharged from the cleaning device in order to prevent clogging in the cleaning device. In accordance with the recycled toner, the powder pump 40 and the air pumps 30A and 30B are operated by the control unit of the main body of the image forming apparatus.
[0009]
[Problems to be solved by the invention]
However, the pressure difference during operation of the powder pump 40 due to the difference in length between the new toner conveyance tube 56 and the recycled toner conveyance tube 57 on the upstream side of the merging pipe 59, and the toner difference due to the height difference between the nozzle 51 and the toner discharge portion 9a. Powder to attract new toner due to differences in ease of suction, differences in the state of toner existing in the nozzle 51 and the toner discharge portion 9a (difference in ease of suction such as fluidized state), differences in toner amount, etc. Even if the body pump 40 is operated, only the recycled toner is sucked, and conversely, even if the powder pump 40 is operated to suck the recycled toner, only new toner is sucked. There was a problem.
[0010]
It is very difficult to set or control the above conditions (the length of the toner transport tube, the height difference between the nozzle 51 and the toner discharge portion 9a, the toner state difference, etc.) so that the required toner can be sucked as intended. It is.
[0011]
The present invention provides a toner replenishing device and an image forming apparatus that can solve the above-described problems in a toner replenishing device using a powder pump and can reliably select and replenish new toner and recycled toner. Let it be an issue.
[0012]
[Means for Solving the Problems]
According to the present invention, there is provided a developer replenishing device for replenishing a developer to a developing device of an image forming apparatus by a suction type powder pump, wherein the developer replenishing device is connected to a developer storage container of the image forming apparatus. A new developer transport tube for replenishing the new developer and a recovered developer transport tube for replenishing the recovered developer connected to the developer recovery device for recovering the developer from the image carrier of the image forming apparatus in the developer supply device merging has been being contacted to the suction type powder pump, wherein the merging portion of the new developer the collected developer conveying pipe and the conveying pipe, the recovery when closing the new developer conveying tube the developer conveying pipe is opened, the recovered developer conveying pipe switching means for opening the new developer conveying pipe when the developer conveying pipe closes provided Rutotomoni, except when replenishment of the new developer, the switching Means to close the new developer transport pipe Be solved by previously switching to the state of opening the serial recovered developer conveying pipe.
[0014]
According to the present invention, the above problem is solved by an image forming apparatus comprising the developer replenishing device according to claim 1.
[0015]
In order to solve the above problems, the present invention proposes to include a plurality of developing devices, and to include a plurality of the developer replenishing devices corresponding to the plurality of developing devices.
In order to solve the above problems, the present invention proposes that the plurality of developing devices are arranged at different heights.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional configuration diagram showing an outline of a full-color printer as an example of an image forming apparatus to which the present invention is applied. This color printer has a configuration in which a sheet feeding unit 2 is disposed at the lower part of the apparatus main body 1 and an image forming unit 3 is disposed above the sheet feeding unit 2. The image forming unit 3 is provided with a transfer belt device that is disposed so as to be inclined so that the side that receives the fed paper is on the bottom and the paper discharge side of the paper on which image formation has been completed is on the top. The transfer belt device has an endless transfer belt 12 wound around a plurality of rollers, in this example, four rollers 11, and along the upper running side of the transfer belt 12, magenta (M), Four image forming units 4M, 4C, 4Y, and 4Bk for cyan (C), yellow (Y), and black (Bk) are arranged in parallel.
[0017]
Each of the image forming units 4M, 4C, 4Y, 4Bk has a photosensitive drum 5 as an image carrier, and the photosensitive drum 5 is rotationally driven in a clockwise direction in the drawing by a driving unit (not shown). Around the photosensitive drum 5, a charging roll 6, a cleaning device 9, a developing device 10 and the like as a charging unit are provided. The developing device 10 is a two-component developing device that uses a developer composed of toner and carrier, and the toner is replenished by a toner replenishing device described later according to the amount of consumed toner. Between the charging roll 6 and the developing device 10 is an optical writing position where the photosensitive drum 5 is irradiated with laser light from the optical writing device 8 disposed above the image forming unit.
[0018]
The image forming operation of the color printer shown in FIG. 1 will be described using the magenta image forming unit 4M.
The photosensitive drum 5 charged by the charging roll 6 is driven by an LD (laser diode) (not shown) to irradiate the polygon mirror 8a with laser light, and the reflected light is passed through the cylinder lens or the like. Optical writing of an optical image to be developed with magenta toner is performed by the optical writing device 8 guided upward. By this writing, an electrostatic latent image is formed on the photosensitive drum 5 based on image data sent from a host machine such as a personal computer, and the latent image becomes a visible image of magenta toner by the developing device 10.
[0019]
On the other hand, a sheet designated as a transfer material is fed from the sheet feeding unit 2, and the fed sheet is once abutted against a registration roller 13 provided on the upstream side in the conveyance direction of the transfer belt 12. Then, the sheet is fed onto the transfer belt 12 in synchronism with the visible image, and reaches the transfer position facing the photosensitive drum 5 by running of the belt. At this transfer position, a visible image of magenta toner is transferred to the paper by the action of the transfer roll 14 disposed on the back side of the transfer belt 12.
[0020]
In the same manner as the above image forming operation, in the other image forming units 4C, 4Y, and 4Bk, visible images are formed by the respective toners on the surfaces of the respective photosensitive drums 5, and these visible images are conveyed by the transfer belt 12. Each time the sheet to be transferred arrives at each transfer position, the transfer is performed. Therefore, in this color printer, a full-color image is superimposed and transferred onto a sheet in a short time almost the same as that of monochrome. The transferred paper is separated from the transfer belt 20 and fixed by the fixing device 15. The sheet after fixing is normally discharged out of the apparatus as it is, but at this time, the sheet is reversed and discharged onto the discharge tray 16 provided on the upper surface of the apparatus main body 1. Backside paper discharge is an almost indispensable condition for the printer to arrange prints in page order.
[0021]
As described above, the color printer of this example includes four image forming units 4M, 4C, 4Y, and 4Bk for magenta (M), cyan (C), yellow (Y), and black (Bk). Each image forming unit is provided with a developing device 10 that performs development with each color toner. Each color toner supplied to each color developing device 10 is individually stored in four cartridges, and the cartridge storing black toner is larger than the other three cartridges. The four toner cartridges are juxtaposed in the lateral direction of the apparatus in the color printer of this example, and are shown as cartridges 20 in the upper right corner in FIG. In FIG. 1, since three cartridges other than those for black toner appear to overlap, only one is shown by a solid line, and the black toner cartridge is shown by a two-dot chain line.
[0022]
FIG. 2 is a cross-sectional configuration diagram showing an outline of a toner replenishing device in the color printer of this example. A toner replenishing device is provided for each color image forming unit. The black image forming unit 4Bk has a toner cartridge larger than the other, and the length of the new toner transport tube 56 is different because the position of each color image forming unit is different. For the same reason, one is described here as a representative.
[0023]
As shown in FIG. 2, the developing device 10 is provided with a powder pump 40 as a toner suction means at the top thereof, and the toner from the toner cartridge 20 passes through the transport tube by the suction pressure of the powder pump 40. To be replenished. As the powder pump 40, a suction type uniaxial eccentric powder pump is used. The powder pump 40 includes a rotor 41 made of a screw eccentric with a material having rigidity such as metal, and a stator 42 that is made of an elastic material such as rubber and is fixed in the shape of a double screw. And a holder 43 made of a resin material or the like that wraps them and forms a powder conveyance path. In the rotor 41, a gear 44 fixed to a drive shaft 41 a connected by a pin joint meshes with a drive gear (not shown) of the developing device 10. The gear 44 is provided with an electromagnetic clutch (not shown) as an intermittent means for interrupting the rotational drive by the drive gear.
[0024]
In the toner replenishing device configured as described above, the single-shaft eccentric screw pump that is the powder pump 40 is capable of continuous quantitative transfer at a high solid-gas ratio, and is accurate in proportion to the rotational speed of the rotor 41. It is known that a transfer amount of toner can be obtained. Therefore, when a toner replenishment command is issued by image density detection or the like, the powder pump 40 is operated, and the requested amount of toner is replenished to the developing device 10.
[0025]
On the other hand, the toner cartridge 20 is set in a cartridge setting unit (not shown) provided in the printer main body. The nozzle 51 attached to and supported by the cartridge set portion has a single tube structure, and a pointed member 52 having a section formed in a conical shape or a spherical shape is provided on the upper portion by integral molding or fixing, and this pointed end. Subsequent to the member 52, a pipe 53 serving as an air supply path and a toner supply path is provided. The conduit 53 is provided with a toner connection port 54 that is bent to the left in the drawing at the lowermost end of the nozzle 51 and to which a new toner transport tube 56 is connected. The pipe 53 is provided with an air connection port 55 that is bent to the right in the drawing above the toner connection port 54.
[0026]
In this example, the air connection port 55 is connected to an air pump 30 </ b> A as an air supply source via an air transfer pipe 31. When the air pump 30 is operated, air is ejected from the lower side into the toner cartridge 20 through the air transfer pipe 31 and the pipe line 53 from the pump. The air blown into the toner cartridge 20 passes through the toner layer stored therein to fluidize the toner while stirring, and the toner is joined to the new toner transport tube 56 by the suction pressure of the powder pump 40. Replenishment is made through the tube 60 and the toner transport tube 58.
[0027]
On the other hand, the color printer of this example is provided with a recycling mechanism for collecting and reusing the transfer residual toner on the photoreceptor 5 of each image forming unit. That is, in FIG. 1, a cleaning device 9 is provided to be attached to the photosensitive drum 5. The cleaning device 9 is provided with a toner discharge portion 9a as shown in FIG. The recycled toner transport tube 57 is connected to the discharge portion 9a, and the recycled toner transport tube 57 is connected to the merge pipe 60, so that the toner collected by the cleaning device 9 can be supplied to the developing device 10 again. Yes. An air transfer pipe 32 from the air pump 30B is connected to the toner discharge portion 9a, and the toner supplied to the toner discharge portion 9a is easily sucked by the powder pump 40 by the air supplied from the air pump 30B. Yes.
[0028]
The merging pipe 60 joins the new toner conveying tube 56 from the toner cartridge 20 and the recycled toner conveying tube 57 from the cleaning device 9 to connect to the toner conveying tube 58 and to communicate with the powder pump 40. However, the junction pipe 60 of this example is provided with a switching valve 61 at the junction.
[0029]
Switching valve 61, the valve protrusion 61a to the shaft portion to be rotated (swung) by the motor 62 is one that is突接, and can rotate in the arrow K ₁ or K ₂ directions. When the motor 62 is a stepping motor, for example, the rotation direction and the rotation amount thereof, that is, the rotation direction and the rotation amount of the valve protrusion 61a can be easily controlled. Control of the motor 62 can be controlled by a control unit of the printer main body. Note that the same operation can be performed by a driving means other than the stepping motor, such as a solenoid.
[0030]
Now, when the valve protrusion 61a is rotated by a predetermined amount in the arrow K ₁ direction, recycled toner transport path from the cleaning device 9 is closed, the new toner conveyance path from the toner cartridge 20 is opened. Conversely, when the valve boss 61a is rotated by a predetermined amount in the arrow K ₂ direction, the new toner conveyance path from the toner cartridge 20 is closed, recycled toner transport path from the cleaning device 9 is opened.
[0031]
When supplying new toner required for the developing device, the switching valve 61 (the valve boss 61a) is rotated in the arrow K ₁ direction, closing the recycle toner conveying path. Subsequently, the air pump 30A is operated to fluidize the toner in the toner cartridge 20, and the powder pump 40 is operated to supply new toner to the developing device 10.
[0032]
On the other hand, when supplying the recycled toner to the developing device, the switching valve 61 (the valve boss 61a) is rotated in the arrow K ₂ direction, closing the new toner conveying path. Then, the air pump 30B is actuated in a timely manner so that the recycled toner is easily sucked in the toner discharge portion 9a, and the powder pump 40 is activated to supply the recycled toner to the developing device 10.
[0033]
In the printer of this example, the supply of the new toner and the supply of the recycled toner are almost alternately repeated during the image forming operation. However, the supply time (that is, the supply ratio) of each of the new toner and the recycled toner can be set or changed (controlled) at an appropriate ratio. The amount of new toner supplied to the developing device is preferably calculated by detecting the toner density in the developing device after the recycled toner is supplied to the developing device.
[0034]
Here, in the printer of this example, except when the supply of new toner is rotated changeover valve 61 (the valve boss 61a) in the arrow K ₂ directions, so that keep closing the new toner conveying path. As a result, the recycled toner from the cleaning device 9 continuously discharged during image formation can be preferentially sucked so as to prevent the clogging phenomenon due to the collected toner in the cleaning device 9 in advance. I have to.
[0035]
As described above, in the printer of this example, the switching valve 61 is provided at the junction (merging pipe 60) of the new toner conveyance path and the recycled toner conveyance path of the toner replenishing device, so that the new toner or the recycled toner can be reliably obtained. Can be selected and supplied to the developing device.
[0036]
In the configuration of FIG. 2, the air pump 30A for the new toner (toner cartridge 20) and the air pump 30B for the recycled toner (cleaning device 9) are provided separately. In the selective supply operation, since the operations of the two air pumps 30A and 30B do not overlap, it is possible to share one air pump (for the toner cartridge 20 and the cleaning device 9). By using one air pump, it is possible to contribute to cost reduction and downsizing of the apparatus.
[0037]
The fact that the new toner and the recycled toner can be reliably selected and supplied according to the present invention is particularly effective in the case of a configuration in which a plurality of image forming units are inclined and arranged as in the color printer of this example.
[0038]
That is, in a configuration in which a plurality of image forming units are arranged at an inclination, the position of the developing device (powder pump attached to) of each image forming unit is different, so new toner from each color toner cartridge to each developing device. There is a difference in the length of the transfer tube 56. Further, there is a difference in height difference between the nozzle 51 at the bottom of the toner cartridge and the toner discharge portion 9a of the cleaning device for each image forming unit. Therefore, the pressure difference during operation of the powder pump 40 due to the difference in length between the new toner transport tube 56 and the recycled toner transport tube 57 in each image forming unit, or the height of the nozzle 51 and the toner discharge portion 9a in each image forming unit. Depending on the difference in the ease of toner suction due to the difference, the length of the toner transport tube, the height difference between the nozzle 51 and the toner discharge portion 9a, etc. can be adjusted so that the required toner can be sucked as intended by all image forming units. It cannot be set. However, according to the present invention, it is possible to reliably select and supply new toner and recycled toner in each image forming unit even when there is a difference in conditions as described above in each image forming unit.
[0039]
As mentioned above, although this invention was demonstrated by the example of illustration, this invention is not limited to this.
For example, the configuration of the powder pump is not limited to that illustrated in FIG. Further, the shape and configuration of the toner cartridge are also arbitrary. Of course, the developing device can also have an appropriate configuration. The number of colors, that is, the number of image forming units is also arbitrary. Furthermore, the developer to be used is not limited to two components including toner and carrier, and may be one component.
[0040]
When a plurality of image forming units are provided, their heights may be different or the same. Of course, the image forming apparatus is not limited to a printer, and may be a copying machine or a facsimile.
[0041]
【The invention's effect】
According to the developer supply device of the first aspect or the image forming apparatus of the second aspect , the new developer and the recovered developer can be reliably selected and supplied to the developing device.
[0042]
Also, except when replenishing the new developer, the switching means is switched to a state in which the new developer transport pipe is closed and the recovered developer transport pipe is opened, so that the recovery continuously discharged during image formation is performed. It can be in a state where the developer can be replenished with priority. Thereby, it becomes possible to prevent the clogging phenomenon in the developer collecting means.
[0043]
According to the configuration of the fourth aspect, in the image forming apparatus including the plurality of developing devices and the developer replenishing device, there is a difference in the length of the developer conveyance path for each developing device by having the plurality of developing devices. However, regardless of the length of the conveyance path, the new developer and the recovered developer can be reliably selected and supplied to each developing device.
[0044]
According to the configuration of claim 5, even when a plurality of developing devices are arranged at different heights, the new developer and the recovered developer are surely selected and replenished to each developing device regardless of the height difference. Can do.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram showing an outline of a full-color printer as an example of an image forming apparatus to which the present invention is applied.
FIG. 2 is a cross-sectional configuration diagram illustrating an outline of a toner supply device in the full-color printer.
FIG. 3 is a cross-sectional configuration diagram for explaining a toner recycling mechanism in a conventional toner replenishing device using a powder pump.
[Explanation of symbols]
1 Color printer device body 4 Image forming unit 9 Cleaning device (developer recovery device)
DESCRIPTION OF SYMBOLS 10 Developing device 20 Toner cartridge 30A, B Air pump 40 Powder pump 56 New toner conveyance tube 57 Recycled toner conveyance tube 58 Toner conveyance tube 60 Junction pipe 61 Switching valve 61a Valve protrusion

Claims (4)

A developer replenishing device for replenishing the developing device of the image forming apparatus of the developer by suction type powder pump, is connected to the developer container of the image forming apparatus in the container new developer for replenishing new The suction-type powder pump is connected to a developer conveying pipe and a collected developer conveying pipe connected to a developer collecting apparatus for collecting the developer from the image carrier of the image forming apparatus and replenishing the collected developer. In the developer replenishing device in contact with
When the new developer transport pipe is closed at the junction of the new developer transport pipe and the recovered developer transport pipe , the recovered developer transport pipe is opened, and when the recovered developer transport pipe is closed Rutotomoni provided a developer conveying tube switching means for opening the new developer conveying pipe,
A developer replenishing apparatus, wherein the switching means is switched to a state in which the new developer transport pipe is closed and the recovered developer transport pipe is opened except when a new developer is replenished. An image forming apparatus comprising the developer supply device according to claim 1. The image forming apparatus according to claim 2 , comprising a plurality of developing devices, and a plurality of the developer replenishing devices corresponding to the plurality of developing devices. The image forming apparatus according to claim 3 , wherein the plurality of developing devices are arranged at different heights.

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