JP3544097B2 - Image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile machine, and more particularly to developing by supplying a dry one-component or dry two-component developer to an electrostatic latent image formed on an image carrier. The present invention relates to an image forming apparatus of a type in which a developer is transferred to a developing unit by a screw pump.
[0002]
[Prior art]
As an electrophotographic image forming apparatus such as a printer, a facsimile, or a copying machine using a dry type one-component or dry type two-component developer, a developing unit that develops an electrostatic latent image formed on an image carrier is separated from the developing unit. A rotor that moves the developer in the axial direction by rotating the toner storage unit, the toner supply unit, the toner transfer unit, and the like at arbitrary positions, and a passage that surrounds the rotor, A screw pump having a fixed stator that is in contact with the rotor and an air supply unit for supplying air for fluidizing the developer moved by the screw pump; An apparatus for forming an image by transferring a mixture of toner and air to a means is known (JP-A-7-219329). Referring to the publication of).
However, in the above-described conventional image forming apparatus, the developer for developing the electrostatic latent image formed on the image carrier is moved from the air supply unit to the screw pump in order to fluidize the developer moved by the screw pump. Under the influence of the humidity of the supplied air and the dust mixed therein, the charge of the developer is changed, and the resulting image has a problem that density unevenness or the like occurs, thereby deteriorating the image quality.
[0003]
[Problems to be solved by the invention]
In the above-described conventional image forming apparatus, the developer for developing the electrostatic latent image formed on the image carrier is supplied from the air supply unit to the screw pump to fluidize the developer moved by the screw pump. There is a problem that the charge of the developer changes due to the influence of the humidity of the air and the dust mixed therein, the density unevenness or the like occurs, and the image quality deteriorates.
Therefore, an object of the present invention is to solve such a problem. That is, when supplying air from the air supply means to fluidize the developer when transferring the developer toward the developing means by the screw pump means, by realizing dehumidification of the air and prevention of dust mixing. It is another object of the present invention to provide an image forming apparatus capable of stabilizing the charge of a developer to prevent a decrease in density or the like and forming a high quality image.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, the electrostatic latent image formed on the image bearing member is supplied with a developer transferred by a screw pump and visualized. an image forming apparatus for forming an image by fixing after transfer on the transfer paper, a developing means for developing by supplying a developer onto the electrostatic latent image formed on said image bearing member, and said developing means A developer storage unit provided separately, a rotor for moving the developer supplied to the developer storage unit in the axial direction by rotating the rotor, and a passage arranged so as to wrap the rotor; screw pump means and a developing agent supply means having a screw supplying the developer to the screw pump means in said developer storing means, said screw pump means having a fixed Stator contacting engagement with An air supply means comprising a fan which is rotatably driven to supply air to fluidize the developer more mobile, and dehumidifying means for dehumidifying the air in which the air supply means for sucking, arranged opposite 2 A single motor that simultaneously drives the screw and the fan by fixing the screw and the fan to two output shafts, respectively, in the axial direction outside the fan fixed to one output shaft of the motor. The dehumidifying means and the air intake are sequentially arranged, the rotor is fixed to the other end of the screw having one end fixed to the other output shaft of the motor, and the rotor is linearly fixed. Air for supplying air sucked from the air intake port through the dehumidifying means by the rotation drive of the fan to the upstream side and the downstream side of the passage in the stator, respectively. Comprising a feeding tube, and the dehumidifying means, and the fan, and the motor, and the screw, the rotor and stator, characterized in that it is arranged in a row sequentially linearly.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a solid drying agent is used as the dehumidifying unit.
According to a third aspect of the present invention, in the image forming apparatus of the second aspect, silica gel is used as the solid desiccant.
According to a fourth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the dehumidifying unit is configured to be detachably attached to the air supply unit by an attaching / detaching unit.
[0005]
[Action]
In the image forming apparatus configured as described above, in claim 1, the developer supplied to the developer storage unit that is provided separately from the developing unit and supplies the developer to the developing unit, When moving to the developing means by the screw pump means, air is supplied from the air supply means to fluidize the developer, and dehumidifying means is used to dehumidify from the air and transfer after preventing the mixing of dust. As a result, the developer for developing the electrostatic latent image formed on the image carrier is sufficiently fluidized by air added in the process of moving by the screw pump means, is dehumidified, and is further dedusted. Since the mixing is also prevented, it is possible to stabilize the charge of the developer and prevent the occurrence of a decrease in density or the like, thereby enabling high-quality image formation.
In Claims 2 and 3, since a solid drying agent (for example, silica gel) is used as the dehumidifying means, the developer for developing the electrostatic latent image formed on the image carrier is supplied by the screw pump means. While being sufficiently fluidized by the air added in the moving process, it is dehumidified by a solid desiccant, and furthermore, the mixing of dust is prevented, so that the charge of the developer is stabilized to prevent the occurrence of concentration reduction, etc. High quality image formation can be made possible.
According to the fourth aspect, the dehumidifying means is detachable from the air supply means by the attaching / detaching means. In addition to the effects of the inventions described above, the dehumidifying means can be replaced with a new one by an easy procedure as necessary. It becomes possible to always maintain the dehumidifying effect.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic overall configuration diagram of an image forming unit of the image forming apparatus of the present invention, FIG. 2 is an external perspective view of a developing unit, and FIG. 3 is a detailed configuration explanatory diagram of a developer storing and supplying unit. In the figure, an image carrier 1 of a drum-shaped photoreceptor is rotatably supported by a side plate (not shown), and is driven to rotate clockwise in the direction of arrow A by drive means (not shown). The image on the carrier 1, the electrophotographic imaging process, after uniformly charged by the charger 7, an electrostatic latent image is performed exposure by the exposure means 8 is supported is formed. The electrostatic latent image formed and carried on the image carrier 1 is magnetically developed in a dry one-component or dry two-component developing system by a dry one-component or dry two-component developer supplied from a developing unit 2. The image is visualized by a brush developing method. The drum-shaped photoconductor of the image carrier 1 may be an endless belt-shaped photoconductor. The developing unit 2 includes a developing roller 2a that supplies a developer to the electrostatic latent image formed and carried on the image carrier 1, a paddle 2b that agitates and transports the developer, a paddle 2c, and a peripheral surface of the developing roller 2a. It comprises a blade 2d for regulating the height of the upper developer layer, and a case 2e for accommodating and holding these. The developer is supplied to the container 2e by a developer supply unit 2f.
[0007]
The developer storage / supply unit 0 includes a developer storage unit 3, a screw pump unit 4, an air supply unit 5, a dehumidification unit 6, and a developer supply unit 9. The developer storing / supplying means 0 has a separate structure from the developing means 2, and the developer storing means 3 is connected to the developer supplying means 9 so as to appropriately supply the developer into the developer supplying means 9. It is arranged. As shown in FIG. 3, the screw pump unit 4 includes a rotor 4 a that is supplied to the developer storage unit 3 and moves the axial direction by rotating the developer supplied from the developer supply unit 9. It has a passage (in-stator passage) 4b arranged so as to enclose it, and a fixed stator 4c which is brought into contact with and engaged with the rotor 4a. The air supply unit 5 is a unit that supplies air for fluidizing the developer moved by the screw pump unit 4 to the transfer path of the developer moved by the screw pump unit 4 and is supplied to the transfer path. The developer is previously dehumidified by the dehumidifying means 6 and is prevented from being mixed with dust. The dehumidifying means 6 uses silica gel 6b as a solid desiccant 6a, and also functions as a filter for preventing dust mixed into the air. The paper supply unit 10 is provided with a plurality of paper supply cassettes containing transfer papers of various sizes. The exposure means 8 is a light source, an optical system having a mirror and the like in an analog optical image forming apparatus, a laser printer, and a laser scanning apparatus having a laser light source and a deflector in a digital image forming apparatus. The optical system is connected to a laser optical system that performs optical writing on the image carrier 1 according to an image signal using an optical system.
[0008]
When the image forming operation is started, the image carrier 1 is charged by the charger 7, and the original image from the exposure unit 8 is exposed to form an electrostatic latent image. This electrostatic latent image is developed by a dry type one-component developer or a dry type two-component developer supplied from the developing unit 2, and a toner image is formed on the image carrier light body 1.
The transfer paper (P) is fed from the paper feeding unit 10, and is transferred onto the transfer paper (P) fed to the transfer position of the nip portion between the image carrier 1 and the transfer device 12 via the registration roller 11. 1 is transferred.
Then, the transfer paper (P) on which the toner image has been transferred is transported from the transfer unit 12 to the fixing unit 13, where the toner image is fixed on the transfer paper (P) by the fixing unit 13, and the transfer paper (P) ) Is discharged via the discharge roller 14 and stored on the discharge tray.
On the other hand, the image carrier 1 after the transfer of the toner image is cleaned by the cleaning unit 15 to remove and collect the residual toner, and is prepared for the next image forming process.
[0009]
In FIG. 3, the developer storing means 3 is provided so as to close the opening 3a with a storing means main body 3c formed in a substantially funnel shape having a supply side opening 3a at an upper part and a discharge side opening 3b at a lower part. It is composed of a lid 3d that can be opened and closed freely. The developer is appropriately supplied from the opening 3a to the inside of the storage unit main body 3c. The toner supply unit (developer supply unit) 9 communicating with the opening 3b of the developer storage unit 3 includes a supply unit main body 9a, a motor 9b, a screw 9c, and the like. It is formed in a funnel shape, and is connected to the storage means main body 3c so as to be connected to the opening 3b at the upper right. The developer supplied to the storage unit main body 3c from the opening 3a flows down from the opening 3b into the supply unit main body 9a by its own weight. A motor mounting member 9d for supporting the motor 9b is mounted on the upper left of the storage means main body 3c. A screw 9c is attached to an output shaft of the motor 9b via a sleeve 9e. The screw 9c penetrates the supply means main body 9a from the upper part to the lower part, and its lower end extends to substantially the same position as the lower end part of the supply means main body 9a. The developer in the supply unit main body 9a is conveyed downward while being stirred by the screw 9c.
[0010]
The screw pump means 4 is connected to the lower end of the developer supply means 9 in communication. Since the rotor 4a is connected to the motor 9b via the screw 9c, the rotor 4a rotates integrally with the rotation of the screw 9c. Around the rotor 4a, a stator 4c formed of an elastic material such as a rubber material is provided so as to wrap the rotor 4a. The stator 4c has a passage 4b through which the rotor 4a sends developer while rotating. Is formed. The stateer 4c is fixedly held by the upper holder 4d and the lower holder 4e.
The upper holder 4d is formed in a cylindrical shape and is connected to the developer supply means 9, and has an air supply port 4f formed at a side portion thereof for connecting a connection portion with the developer supply means 9 and the outside. I have.
The lower holder 4e is formed in a stepped cylindrical shape, and a stator 4c is fitted in the upper space with a gap, and a developer passage 4g for discharging the developer transported by the rotor 4a is provided in a lower portion. Is formed.
An air supply port 4h is formed on the side of the lower holder 4e to communicate the outside with the developer passage 4g.
[0011]
The fan 5a of the air supply means 5 disposed above the motor 9b is driven by a motor 9b (the fan 5a is fixed to an upper output shaft opposed to a lower output shaft to which the screw 9c is fixed). The outside air is sucked in from the air intake port 5b provided at the upper part, and the air discharge port 5c and the air discharge port 5d provided at the side part are two pipes (air supply pipes) indicated by a chain line. Are connected to the air supply port 4f and the air supply port 4h, respectively, and the rotation of the fan 5a causes the holder 4d of the screw pump means 4 to enter the air supply port 4f through the air supply port 4f. Air of about 0.5 to 2 liters / minute is sent into the developer from the developer passage 4g from the air supply port 4h. The dehumidifying means 6 disposed above the air supply means 5 converts the outside air sucked from the air intake port 6e provided at the upper part into a plate filter provided in the main body container 6f or a solid desiccant filled in granular form. 6a (for example, silica gel 6b, which is highly safe and easy to handle and handle), prevents dehumidification and mixing of dust and discharges the air from the air discharge port 6g to the air intake 5b of the air supply means 5. .
[0012]
As the dehumidifying means 6, a low-humidity or high-temperature drier or calcium chloride as a solid desiccant 6a may be used.
However, the drier has a complicated and large-sized apparatus and is costly. Since calcium chloride dissolves when it absorbs moisture, its handling method and recyclability are not as good as those of the silica gel 6b.
The air is dehumidified by the dehumidifying unit 6 and the mixing of dust and the like is prevented, so that the developer is stabilized and its fluidization is promoted, and is sent to the developer supply unit 2f of the developing unit 2.
The amount of air supplied by the air supply means 5 is very small, and this air is discharged outside via the air filter 2g of the developing means 2 after contributing to the transfer of the developer (see FIG. 1). 1 and 2).
[0013]
Another embodiment of the present invention will be described with reference to a cross-sectional view of the developer storage and supply unit in FIG. The same parts as those in the above embodiment are denoted by the same reference numerals and described, but detailed description thereof will be omitted, and thus will not be repeated.
The difference between the developer storage and supply means 100 of this embodiment and the above embodiment is that the storage means main body 103c of the developer storage means 103, which is formed larger instead of the storage means main body 3c of the developer storage means 3, is supplied. A screw pump means 104, a developer supply means 109, and a supply means body 109a are provided in place of the means body 9a, an air supply means 105 is provided in place of the air supply means 5, and a dehumidification means 106 is provided in place of the dehumidification means 6. (The horizontal direction in which the developer flows in a horizontal direction orthogonal to the flowing direction of the developer flowing down the storage unit main body 103c).
[0014]
The storage means main body 103c is formed in a funnel shape, and has an opening 103a at an upper part and an opening 103b at a lower part. An openable / closable lid 103d is provided on the upper part of the storage means main body 103c so as to close the opening 103a.
Below the storage means main body 103c, a supply means main body 109a which is connected to the opening 103b and is formed in a tubular shape is arranged.
The dehumidifying means 106 disposed on the left side of the air supply means 105 is provided with a dehumidifier 106a filled in a main body container 106f to remove the external air sucked from an air intake port 106e provided at the upper part (the device is highly safe and the By passing through a simple silica gel 106b), dehumidification and dust entering are prevented, and the air is discharged from the air discharge port 106g to the air intake 105b of the air supply means 105.
[0015]
FIG. 5 is a cross-sectional view showing a detailed configuration example of the air supply means. The dehumidification means 106 is attached to and detached from the air supply means 105 by a snap-fit type attachment / detachment means 106c such as a patch or a locking claw. And can be exchangeably held.
The solid desiccant 106a is formed into a granular form and is contained in a bag or the like of a container 106d having air permeability and flexibility. By simply dropping the container 106d into the main body container 106f from above, the shape of the solid desiccant 106a becomes It is deformed and filled so as to match the shape in the container 106f, and can be more easily replaced.
[0016]
【The invention's effect】
As described above, according to the first aspect of the present invention, the developer in the developer storage unit provided separately from the developing unit and supplying the developer to the developing unit is supplied to the screw pump unit (rotor). The air supply means supplies fluid for fluidizing the developer when moving to the developing means, and dehumidifies the air by means of the dehumidifying means to prevent the entry of dust. Since the developer is transferred from the developer, the developer for developing the electrostatic latent image formed on the image carrier is sufficiently fluidized by air added in the process of moving by the screw pump means, and is dehumidified. Further, dust is prevented from being mixed, so that the charge of the developer is stabilized to prevent a decrease in density or the like, thereby enabling high quality image formation.
In Claims 2 and 3, since a solid drying agent (for example, silica gel) is used as the dehumidifying means, the developer for developing the electrostatic latent image formed on the image carrier is supplied by the screw pump means. While being sufficiently fluidized by the air added in the moving process, it is dehumidified by a solid desiccant, and furthermore, the mixing of dust is prevented, so that the charge of the developer is stabilized to prevent the occurrence of concentration reduction, etc. High quality image formation can be made possible.
According to the fourth aspect, the dehumidifying means is detachable from the air supply means by the attaching / detaching means. In addition to the effects of the inventions described above, the dehumidifying means can be replaced with a new one by an easy procedure as necessary. It becomes possible to always maintain the dehumidifying effect.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram schematically illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view illustrating a main part of the image forming apparatus according to the exemplary embodiment of the present invention.
FIG. 3 is an explanatory diagram illustrating another main part of the image forming apparatus according to the exemplary embodiment of the present invention.
FIG. 4 is an explanatory diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.
FIG. 5 is an enlarged view illustrating another main part of the image forming apparatus according to another embodiment of the present invention.
[Explanation of symbols]
0 developer storage and supply means, 1 image carrier, 2 development means, 2a developing roller, 2b paddle, 2c paddle, 2d blade, 2e case, 2f developer supply unit, 2g air filter, 3 developer storage means, 3a opening , 3b
Opening, 3c storage means main body, 3d lid, 4 screw pump means, 4a rotor, 4b passage, 4c stator, 4d upper holder, 4e lower holder, 4f air supply port, 4g developer passage, 4h air supply port, 5 air supply Means, 5a fan, 5b air inlet, 5c air outlet, 5d air outlet, 6 dehumidifying means, 6a solid desiccant, 6b silica gel, 6c attaching / detaching means, 6e air inlet, 6f body container, 6g air outlet, Reference Signs List 7 transfer unit, 8 exposure unit, 9 toner supply unit, 9a supply unit main body, 9b motor, 9c screw, 9d motor mounting member, 9e sleeve, 10 paper feed unit, 11 registration roller, 12 transfer unit, 13 fixing unit, 14 Discharge roller, 15 Cleaning means, 103 Developer storing means, 103a opening, 103b opening, 10 c Storage means main body, 103d lid, 104 screw pump means, 104f air supply port, 104g developer passage, 104h air supply port, 105 air supply means, 105c, 105d air discharge port, 106 dehumidification means, 106a solid desiccant, 106b Silica gel, 106c attaching / detaching means, 106d container, 106e air intake port, 106f main body container, 106g air discharge port, 109 developer supply means, 109a supply means main body,

Claims (4)

An image forming apparatus that forms an image by supplying a developer transferred by a screw pump to an electrostatic latent image formed on an image carrier, developing the image, transferring the developed image onto transfer paper, and fixing the image. a is a developing means for developing by supplying a developer onto the electrostatic latent image formed on said image bearing member, a developer storing means provided separately from the above developing unit, the developer reservoir Screw pump means having a rotor for moving the developer supplied to the means in the axial direction by rotating the rotor, and a fixed stator having a passage arranged so as to enclose the rotor and being in contact with and engaged with the rotor; a developer supply unit provided with a screw to be supplied to the screw pump means developer in the developer storage unit, the air for fluidizing the developer moved by the screw pump means An air supply means comprising a fan that is rotated to feed the dehumidifying means for dehumidifying the air in which the air supply means for sucking, respectively the screw and the fan into two output shafts disposed opposite to fixed And one motor that simultaneously drives the screw and the fan,
The dehumidifying means and the air intake are sequentially arranged on the axially outer side of a fan fixed to one output shaft of the motor,
The rotor is fixed in a straight line to the other end of the screw whose one end is fixed to the other output shaft of the motor,
The air supply means includes an air supply pipe for supplying air sucked from the air intake port through the dehumidification means by the rotation drive of the fan to the upstream side and the downstream side of the stator internal passage, respectively.
The image forming apparatus , wherein the dehumidifying means, the fan, the motor, the screw, the rotor and the stator are sequentially arranged in a straight line . The image forming apparatus according to claim 1, wherein a solid desiccant is used as the dehumidifying unit. 3. The image forming apparatus according to claim 2, wherein silica gel is used as the solid desiccant. The image forming apparatus according to claim 1, wherein the dehumidifying unit is configured to be detachable from the air supply unit by a detachable unit.

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