JP2002072687A - Developing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing apparatus preventing developer from adhering to an electrifying roller by properly setting the relation between the abutting pressure of a supply roller on a developer carrier and the abutting pressure of the electrifying roller on the developer carrier. SOLUTION: In this developing apparatus, the abutting pressure P1 of the electrifying roller on the developer carrier is made smaller than the abutting pressure P2 of the supply roller on the developer carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic apparatus for forming an image by arranging a charging means, an image writing means, a developing means (developing device), etc. around an image forming body in a copying machine, a printer, a facsimile or the like. The present invention relates to a developing device used for photographic image formation, and more particularly to a developing device in which a non-magnetic one-component developer is used as a developer.

[0002]

2. Description of the Related Art Conventionally, a non-magnetic one-component developer (hereinafter simply referred to as toner) has been used as a developer in a developing device used for developing an electrostatic image used in electrophotographic image formation such as a copying machine, a printer, and a facsimile. And has various advantages. However, the developing means is a movable developer carrying means for carrying and transporting the developer and supplying the developer to an image forming body (for example, a photosensitive drum used for electrophotography). It is difficult to uniformly apply an appropriate amount to the developer carrier (developing roller). Conventionally, a thin layer of developer is formed on the developing roller by a developer regulating member (blade) in contact with the developing roller, and a developing area is formed. And develops the latent image on the image forming body. But with this method,
After development, there is a problem that a development ghost remains on the development roller and a ghost image is generated in a print image.

In order to solve the above-mentioned problems, the present inventors have developed a supply roller for supplying a developer (toner) to a developer carrier (developing roller), a supply roller for supplying the developer (toner), and a thinner member for regulating the developer. A charge roller that charges the toner on the layered developing roller to equalize the charge of the toner, and removes the charge on the toner on the development roller after development, and improves the collection by supplying the toner on the development roller. Japanese Patent Application No. 11-131263 has proposed a developing device for uniformly applying a non-magnetic one-component developer (toner) to a developer carrier using a roller or the like to prevent a ghost image.

[0004]

However, in the developing device proposed above, the adhesive force between the developer carrier (developing roller) and the developer (toner) is different from the electrical adhesive force due to frictional charging and the physical adhesive force. Has (mechanical) adhesion.
The physical adhesion is determined by the contact pressure between the supply roller and the developer carrier and the contact pressure between the developer regulating member and the developer carrier. Since the driving force is opposed to each other, the driving torque is increased, so that the contact pressure between the supply roller and the developer carrier of the supply roller, which should be set to be equal to or less than the specified value, and the developer roller of the charging roller and the charge removing roller are different. Due to the relationship with the contact pressure, the adhesion of the developer (toner) to the charging roller and the charge elimination roller becomes stronger at the position of the charging roller and the charge elimination roller than the adhesion of the developer (toner) to the developer carrier. The developer adheres to the neutralizing roller,
There is a problem that the charging roller and the discharging roller are contaminated and do not work properly.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and sets the charging roller by appropriately setting the contact pressure between the supply roller and the developer carrier and the contact pressure between the charging roller and the developer carrier. In addition to preventing the developer from adhering to the developing roller, the developing roller can be developed by setting an appropriate relationship between the contact pressure of the supply roller with the developer carrier and the contact pressure of the discharging roller with the developer carrier. It is a first object of the present invention to provide a developing device for preventing the adhesion of an agent.

In the developing device proposed above,
In order to prevent the developer (toner) from adhering to the charging roller or the charge removing roller that is driven and rotated in contact with the developer carrier (developing roller), the developer (toner) is attached to the surface of the charging roller or the charge removing roller. ) Is preferable, but the releasability from the developer (toner) on the surface of the charging roller or the charge removing roller is good with the releasability from the developer (toner) on the surface of the developer carrier. If it is too high, there arises a problem that the charging roller and the discharging roller slip.

The present invention also solves the above-mentioned problems, and maintains the releasability from the developer (toner) on the surface of the charging roller to prevent the developer (toner) from adhering to the charging roller. A developing device that prevents slippage of the charge elimination roller while maintaining the releasability from the developer (toner) on the charge elimination roller surface and preventing the developer (toner) from adhering to the charge elimination roller. The second purpose is to provide.

In the developing device according to the above proposal,
If the developer (toner) adheres to the charging roller or the charge eliminating roller, there arises a problem that the charging roller or the charge eliminating roller does not function properly.

The present invention also solves the above-mentioned problems, prevents the developer (toner) from adhering to the charging roller and the charge eliminating roller, allows the charging roller and the charge eliminating roller to function normally, and improves the service life. A third object is to provide a developing device.

[0010] In the developing device according to the above proposal,
The charge amount of the developer (toner) changes depending on the use environment conditions and use frequency. In this case, as a result, the gradation of the image changes. Therefore, as described above, the developer carrying member (developing roller) is provided with a charging roller so as to suppress a change in the amount of charge and obtain a stable image without a change in gradation. The resistance also changes depending on the use environment conditions, the use frequency, and the like, and the amount of charge at the time of charging by the charging roller does not stabilize, changes from an appropriate value, and the gradation of the image changes.

The present invention also solves the above-mentioned problems, and stabilizes the charge amount when charging by the charging roller even if the use environment conditions and the use frequency change. It is a fourth object of the present invention to provide a developing device that does not cause the problem.

[0012]

The first object of the present invention is to provide a developer carrier which holds and rotates a thin layer of a non-magnetic one-component developer, and supplies and collects the developer to and from the developer carrier. A supply roller, a developer regulating member that regulates the amount of developer on the developer carrier, and a charging roller that controls the amount of charge of the developer on the developer carrier. Contact pressure P between roller and developer carrier
1 is a developing device (first invention) characterized in that it is smaller than a contact pressure P2 between the supply roller and the developer carrier, and holds a thin layer of non-magnetic one-component developer. A rotating developer carrier, a supply roller for supplying and collecting the developer to and from the developer carrier, a developer regulating member for regulating the amount of developer on the developer carrier, and the developer carrier In the developing device having the charge removing roller for removing the charge amount of the developer, the contact pressure P3 between the charge removing roller and the developer carrier is a contact pressure between the supply roller and the developer carrier. This is achieved by a developing device (second invention), which is smaller than P2.

A second object of the present invention is to provide a developer carrier which holds and rotates a thin layer of non-magnetic one-component developer, and a supply roller which supplies and collects the developer to and from the developer carrier. A developing device having a developer regulating member that regulates an amount of a developer on the developer carrier, and a charging roller that controls a charge amount of the developer on the developer carrier; A charging roller driving unit that is driven at a constant speed with the developer carrier is provided, and the releasability of the charging roller from the developer is higher than the releasability of the developer carrier from the developer. A developing device (third invention), a developer carrier that rotates while holding a thin layer of non-magnetic one-component developer, and a supply that supplies and collects the developer to and from the developer carrier. Roller and regulates the amount of developer on the developer carrier In a developing device having an image material regulating member and a charge removing roller for removing charge of the developer on the developer carrying member, a charge removing roller driving unit for driving the charge removing roller at a constant speed with the developer carrying member is provided. In addition, the developing device (fourth invention) is characterized in that the releasability of the charge removing roller from the developer is higher than the releasability of the developer carrier from the developer. You.

A third object of the present invention is to provide a developer carrier which holds and rotates a thin layer of a non-magnetic one-component developer, and a supply roller which supplies and collects the developer to and from the developer carrier. A developer regulating member that regulates the amount of developer on the developer carrier, a charging roller that controls the amount of charge of the developer on the developer carrier, and a developer accommodating section that accommodates the developer. A conveying roller for conveying the developer from the developer accommodating portion, wherein the charging roller has a charging roller cleaning unit for removing the developer adhered to the surface, and the developer removed from the charging roller. Developing device (fifth invention) characterized by providing a charging roller-removed developer conveying means for conveying the developer to the developer accommodating portion, and a developing device which holds and rotates a thin layer of non-magnetic one-component developer. Agent carrier and A supply roller that supplies and recovers the developer to and from the developer carrier, a developer regulating member that regulates the amount of developer on the developer carrier, and a charge amount of the developer on the developer carrier. In a developing device having a charge elimination roller for charge elimination, a developer accommodating portion for accommodating the developer, and a conveyance roller for conveying the developer from the developer accommodating portion, the charge elimination roller removes the developer adhering to the surface. A developing device (sixth invention) characterized in that the developing device further comprises a discharging roller cleaning means for transferring the developer removed from the discharging roller to the developer accommodating portion, and a discharging roller removing developer conveying means for conveying the developer removed from the discharging roller to the developer accommodating section. Is done.

A fourth object of the present invention is to provide a developer carrier which holds and rotates a thin layer of non-magnetic one-component developer, and a supply roller which supplies and collects the developer to and from the developer carrier. A developer regulating member that regulates the amount of developer on the developer carrier; and a charging roller that controls the amount of charge of the developer on the developer carrier. This is achieved by a developing device (seventh invention) wherein the bias is changed in accordance with the use environment conditions or the use frequency.

[0016]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope.

An image forming process and each mechanism of an embodiment of an image forming apparatus using a developing device according to the claims of the present invention will be described with reference to FIG. FIG. 1 is a sectional view of a main part of a color image forming apparatus showing an embodiment of an image forming apparatus using a developing device common to the claims of the present invention.

In FIG. 1, reference numeral 10 denotes a photosensitive drum which is an image forming body for each color, 11 denotes a scorotron charger which is charging means for each color, 12 denotes an exposure optical system which is image writing means for each color, and 13 Denotes a developing device that is a developing unit for each color,
Reference numeral 4a denotes an intermediate transfer belt which is an intermediate transfer member, and 14c denotes a first transfer member for transferring a toner image on the image forming member for each color to the intermediate transfer member.
The primary transfer unit 14g is a second transfer unit that re-transfers the toner image on the intermediate transfer member to a transfer material.
A next transfer unit, 14m is a charge eliminator that is a charge elimination unit of the transfer belt, 14b is a pressing elastic plate that is a pressing unit of the transfer belt,
17 is a fixing device as a fixing unit, 190 is a photoconductor cleaning device as an image forming body cleaning unit for each color,
An intermediate transfer member cleaning device 190a is an intermediate transfer member cleaning unit.

In this embodiment, a photosensitive drum 10 as an image forming body for each color, a scorotron charger 11 as a charging unit for each color, an exposure optical system 12 as an image writing unit for each color, The developing device 13 as a developing unit and the photoreceptor cleaning device 190 as an image forming body cleaning unit form a set of these units for each color of yellow (Y), magenta (M), cyan (C), and black (K). Are formed on the intermediate transfer belt 14a with respect to the rotation direction of the intermediate transfer belt 14a rotated counterclockwise as indicated by the arrow in FIG. Are arranged in the order of Y, M, C, and K according to.

Photosensitive drum 10 as an image forming body for each color
Is formed by forming an organic photoreceptor layer (OPC) having an overcoat layer (protective layer) on the outer periphery of a cylindrical metal substrate formed of, for example, an aluminum material on the outer periphery of the metal substrate. In the grounded state, the photosensitive drum 10 for each color is rotated in a clockwise direction indicated by an arrow in FIG. 1 by a photosensitive member drive motor (not shown).

The organic photoreceptor layer comprises a charge generating material (CGM)
And a charge transport layer (CTL) containing a charge transport material (CTM) as a main component. The organic photoreceptor layer comprises a charge generation material (CGM) and a charge transport material (C
(TM) in one layer, and the photosensitive layer having the single-layer structure or the two-layer structure usually contains a binder resin.

The scorotron charger 11, which is a charging means for each color, has the same polarity as the toner (toner at the time of development) used by the control grid and corona discharge electrode maintained at a predetermined potential. The charging action (minus charging in the present embodiment) is performed by the corona discharge of (negative polarity), and a uniform potential, for example, about -750 V is applied to the photosensitive drum 10. As the corona discharge electrode of the scorotron charger 11, a saw-tooth electrode or a needle electrode can also be used.

Exposure optical system 1 as image writing means for each color
2 indicates that the exposure position on the photosensitive drum 10 is the photosensitive drum 1 with respect to the scorotron charger 11 for each color described above.
It is arranged around the photosensitive drum 10 so as to be located on the downstream side in the rotation direction of 0. The exposure optical system 12 rotationally scans a laser beam emitted from a laser light source (not shown) with a rotary polygon mirror (not shown), and comprises an fθ lens (not shown), a reflection mirror (not shown), and the like, and is separate. Image exposure (image writing) of the photosensitive layer of the photosensitive drum 10 according to image data of each color read by the image reading device and stored in the memory to form an electrostatic latent image on the photosensitive drum 10 for each color I do. -75 charged uniformly on the photosensitive drum 10
With respect to the non-image portion potential (white portion potential) of about 0 V, the image portion potential (black portion potential) of the latent image portion (image portion) subjected to image exposure (image writing) is set to about −50 V.

The developing device 13, which is a developing means for each color,
In this embodiment, yellow (Y), magenta (M), cyan (C), and black (K) negatively charged non-magnetic one-component developers (toners) are accommodated, respectively, At the development position, the photosensitive drum 10 rotates in the forward direction with respect to the rotating direction of the photosensitive drum 10 at the developing position. JIS A) Resistance 1
0 urethanes ⁷ Omega · cm, a developing roller 131 as a developer bearing member formed of solid rubber such as silicon, the developing roller 131, the developing time, the toner having the same polarity to be used (this embodiment At minus polarity)
By applying a developing bias voltage of, for example, about -250 V at a direct current voltage, the one-component reversal development is performed by contact, and a latent image portion of about -50 V on the photosensitive drum 10 is applied to the negative image on the developing roller 131. Attach polar toner,
Form a toner image. A supply roller 132, which is a toner supply member, is provided in contact with the development roller 131, and the supply roller 132 supplies and collects toner to the development roller 131. The charge amount of the toner used at the time of development is preferably about 10 to 30 μC / g.

As the non-magnetic one-component developer (toner) used in the developing device 13, a spherical insulating toner obtained by the same method as the conventional toner can be used. Spherical toners are preferred for enhancing developability and obtaining high quality images. Preferred toners are polymers of resins such as styrene resins, vinyl resins, ethylene resins, rosin modified resins, acrylic resins, polyamide resins, epoxy resins, polyester resins, and resins such as fatty acid waxes such as palmitic acid and stearic acid. An average particle diameter of 20 μm or less, preferably 10 μm, which can be produced by a method similar to a conventionally known method for producing toner particles by adding a coloring component such as a color pigment and a charge controlling agent and the like, if necessary, to the agent.
Hereinafter, it is particularly preferable that the particles be 7 μm particles. If necessary, a fluidizing agent for improving the fluidity of the particles and a cleaning agent useful for cleaning the surface of the image forming body are mixed. As a fluidizing agent, colloidal silica, silicone varnish, metal soap or a nonionic surfactant can be used, and as a cleaning agent,
Surface active agents such as fatty acid metal salts, organic group-substituted silicon, and fluoric acid can be used.

Intermediate transfer bell which is a belt-shaped intermediate transfer member
G has a volume resistance of 10¹²-10 ^FifteenΩ · cm endless base
Are modified polyimide, thermosetting polyimide
, Ethylene tetrafluoroethylene copolymer, polyolefin
Engineering of vinylidene disulfide, nylon alloy, etc.
Conductive material dispersed in plastic, thickness 0.1-1.
Outside the 0 mm semiconductive film substrate, preferably
Fluorine film with a thickness of 5 to 50 μm
Two-layer seamless belt with element coating
It is. Other base materials for the intermediate transfer belt 14a include
And a conductive material such as silicone rubber or urethane rubber.
Spread the semiconductive rubber belt with a thickness of 0.5 to 2.0 mm
Can also be used. The intermediate transfer belt 14a is driven
Stretched in contact with the roller 14d and the driven roller 14e.
During image formation, an intermediate transfer member driving motor (not shown) is used.
The drive roller 14d is rotated by the drive of
Of the pressing elastic plate 14b disposed on the upstream side of the
The intermediate transfer belt 14a is pressed against the photosensitive drum 10.
In this state, the intermediate transfer belt 14a is
Rotated clockwise.

The primary transfer device 14c, which is the first transfer means for each color, is preferably constituted by a corona discharger, and the photosensitive drum 10 for each color is sandwiched by the intermediate transfer belt 14a.
And a transfer area for each color (unsigned) between the intermediate transfer belt 14a and the photosensitive drum 10 for each color.
To form The primary transfer device 14c for each color has
Polarity opposite to toner (positive polarity in this embodiment)
By applying a primary transfer bias voltage of, for example, a high DC voltage of about +5 kV to form a transfer electric field in the transfer area, the toner image on the photosensitive drum 10 for each color is transferred onto the intermediate transfer belt 14a. Transcribe.

A secondary transfer device 14g, which is a second transfer means for retransferring the color toner image on the intermediate transfer member onto the transfer material, is constituted by a corona discharger, and is provided at the end of the intermediate transfer belt 14a. Provided opposite to the drive roller 14d that is grounded with the belt 14a interposed therebetween, and has the opposite polarity (positive polarity in the present embodiment) to the toner during retransfer.
By applying a secondary transfer bias voltage of, for example, a high DC voltage of about +6 kV to form a transfer electric field in the transfer area, the superimposed color toner images on the intermediate transfer belt 14a are collectively printed on the recording paper P. And transcribe.

The static eliminator 14m, which is a static elimination means for each color,
Preferably, the primary transfer unit 1 is constituted by a corona discharger.
The charge of the intermediate transfer belt 14a charged by 4c is removed.

The pressing elastic plate 14b, which is a pressing means for the belt-shaped intermediate transfer member, is formed by a rubber blade such as urethane, and is disposed upstream of the transfer position for each color. The photosensitive drum 10 is pressed.

A fixing device 17 serving as a fixing means includes a fixing roller 17 having a heater inside at least one of the rollers.
a, and a pressure roller 17b. The toner image on the transfer material is fixed by applying heat and pressure between the fixing roller 17a and the pressure roller 17b.

The photosensitive member cleaning device 190 as an image forming member cleaning unit for each color is provided on the photosensitive drum 10 for each color by a photosensitive member cleaning blade 191 provided as a photosensitive member cleaning member provided in the photosensitive member cleaning device 190. Clean the transfer residual toner.

The intermediate transfer member cleaning device 190a, which is an intermediate transfer member cleaning means, is
The intermediate transfer belt 14a is provided by an intermediate transfer member cleaning blade 191a, which is provided opposite to the driven roller 14e that is grounded with an intermediary a, and is an intermediate transfer member cleaning member provided in the intermediate transfer member cleaning device 190a.
The upper transfer residual toner is cleaned.

Next, the image forming process (image forming step) will be described. By starting a photoconductor drive motor (not shown) at the start of image recording, the photoconductor drum 10 of the yellow (Y) image forming unit 100 is rotated clockwise as indicated by an arrow in FIG. , The application of a potential to the Y photoconductor drum 10 is started.

After the Y photoreceptor drum 10 is applied with a potential, the Y exposure optical system 12 starts image writing with a first color signal, that is, an electric signal corresponding to the Y image data, and the Y photoreceptor is exposed. Y of the original image on the surface of the body drum 10
An electrostatic latent image corresponding to the image is formed.

The latent image is reversely developed in a contact state by a developing roller 131 of a Y developing device 13, and a yellow (Y) toner image is formed on the photosensitive drum 10 in accordance with the rotation of the Y photosensitive drum 10. Is formed.

The Y toner image formed on the Y photoreceptor drum 10 as the image forming body by the above-described image forming process is transferred to the Y transfer area (no symbol) in the Y transfer area (no symbol). The image is transferred onto the intermediate transfer belt 14a by the primary transfer device 14c.

Next, the intermediate transfer belt 14a is synchronized with the Y toner image, and a potential is applied by the charging action of the M scorotron charger 11 by the magenta (M) image forming unit 100, and the M exposure optical system is used. Image writing is performed by the second color signal, that is, an electrical signal corresponding to the M image data by the M 12, and the M image is formed on the M photoconductor drum 10 by the reversal development of the contact by the developing roller 131 of the M developing device 13. In the M transfer area (no symbol), the M primary transfer unit 14c, which is the first transfer unit, forms the M toner image by superimposing the M toner image on the Y toner image. .

By the same process, the image is synchronized with the superposed toner image of Y and M, and is formed by the third color signal formed on the photosensitive drum 10 of C by the image forming unit 100 of cyan (C). The C toner image corresponding to the C image data is transferred from the top of the Y and M toner images by the C primary transfer unit 14c, which is the first transfer unit, in the C transfer area (no symbol). A toner image of C is formed on the photosensitive drum 10 of K by the black (K) image forming unit 100 in synchronism with the toner image of Y, M, and C. The K toner image corresponding to the K image data based on the fourth color signal is transferred by the K primary transfer unit 14c as the first transfer unit in the K transfer area (no sign). From the top of the C toner image Over image is formed by overlapping, Y, M, color toner image overlay C and K are formed on the transfer belt 14a.

The transfer residual toner remaining on the peripheral surface of the photosensitive drum 10 for each color after the transfer is cleaned by the photosensitive member cleaning blade 191 of the photosensitive member cleaning device 190 which is the image forming member cleaning means for each color. .

In synchronization with the formation of the superimposed color toner image on the intermediate transfer belt 14a, the recording paper P is transferred from a paper feed cassette (not shown) as a transfer material storage means via a timing roller 15b as a transfer material feed means. The secondary transfer unit 14g, which is a second transfer unit, is conveyed to a transfer area (no symbol) of a secondary transfer unit 14g, and is applied with a DC voltage having the opposite polarity (positive polarity in the present embodiment) to the toner. ,
The superimposed color toner images on the intermediate transfer belt 14a are collectively transferred onto the recording paper P.

The recording paper P on which the color toner image has been transferred is
The charge is removed by a charge removing electrode 16b, which is a separating means formed of a sawtooth electrode plate, conveyed to the fixing device 17, and heat and pressure are applied between the fixing roller 17a and the pressure roller 17b, so that the recording paper P After the toner image is fixed,
The sheet is discharged to a tray (not shown) outside the apparatus.

The untransferred toner remaining on the peripheral surface of the intermediate transfer belt 14a after the transfer is an intermediate transfer body cleaning device which is an intermediate transfer body cleaning means provided opposite the driven roller 14e with the intermediate transfer belt 14a interposed therebetween. 190
The cleaning is performed by the intermediate transfer member cleaning blade 191a.

The image forming unit 100 for each color of the image forming apparatus of FIG. 1 will be described in detail in a later embodiment with respect to the rotation direction of the photosensitive drum 10 on the downstream side of the developing device 13 for each color. As described above, the density detection sensor DSa is provided as density detection means for measuring the density of the reference patch for each color.

In the above, the transfer material is conveyed on an intermediate transfer belt 14a, which is a belt-shaped intermediate transfer member, and the toner image formed by the image forming unit 100 for each color is transferred by the first transfer means for each color. The color toner image is sequentially transferred onto the transfer material, and a superimposed color toner image is formed on the transfer material.
You may make it fix. In this case, transfer by the second transfer unit is unnecessary. Alternatively, a configuration may be employed in which monochrome image formation is performed using only one image forming unit.

Embodiment 1 A developing device according to claims 1 to 4 of the present invention will be described with reference to FIG. FIG. 2 shows a first embodiment of the present invention.
FIG. 5 is an enlarged cross-sectional configuration diagram of a developing device according to Nos. 1 to 4.

According to FIG. 2, the developing device 13 which is a developing means for each color includes yellow (Y), magenta (M), cyan (C) and black (K), and in this embodiment, negatively charged. A non-magnetic one-component developer (toner) is accommodated, respectively, and comes into contact with (contacts) the peripheral surface of the photosensitive drum 10. At the developing position, the rotation direction (clockwise direction in FIG. 2) Forward direction (counterclockwise direction in FIG. 2)
And a developing roller 131 that rotates. Developing roller 13
1, a supply roller 132, which is a toner supply member, is provided.
Supply of toner from the developing roller 131 and collection of toner from the developing roller 131 are performed. The supply roller 132 is provided in the supply section in parallel with the developing roller 131, and
1 (counterclockwise in FIG. 2).

The developing roller 131, which is a developer carrier,
For example, a hardness of 45 ° (JIS)
In A), it is formed of a solid rubber such as urethane or silicon having a volume resistance of 10 ⁷ Ω · cm. At the time of development, the developing roller 131 is applied with a developing bias VB1 having the same polarity as the toner polarity to be used (minus polarity in the present embodiment) and a DC voltage of about -250 V to perform one-component inversion development of contact. The developing roller 1 is applied to a latent image portion (image portion) on the photosensitive drum 10 which has an image portion potential of about −50 V.
The toner of the negative polarity on 31 is attached to form a toner image on the latent image portion on the photosensitive drum 10.

Supply roller 132 as a toner supply member
Is formed on the outside (outer peripheral surface) of a conductive metal core (unsigned) such as stainless steel by forming a foamed rubber layer (unsigned) having a volume resistance of 10 ⁶ Ω · cm with a foamed rubber such as urethane or silicon. A developing drive motor (not shown) is configured to face the rotation (counterclockwise in FIG. 2) of the developing roller 131 that comes into contact with the developing roller 131, and is forcibly driven in the opposite direction (counterclockwise in FIG. 2) at the contact position. . At the time of development, a supply roller bias VK1 of a DC voltage of about -500 V having the same polarity (minus polarity in the present embodiment) as the polarity of the toner to be used is applied to the supply roller 132.

The blade 133, which is a developer regulating member,
For example, the blade 133 is a band-shaped elastic plate made of stainless steel having a thickness of about 0.1 mm, and the blade 133 is disposed with its tip directed to the upstream side in the rotation direction of the developing roller 131. This is a so-called counter type developer regulating member that regulates the height and amount of the layer). The blade 133 may be a so-called trail-type developer regulating member whose tip is disposed downstream in the rotation direction of the developing roller 131. With this blade 133, one layer or two layers are formed on the developing roller 131.
A developer layer as thin as about two layers is formed.

A hopper portion 134, which is a developer accommodating portion for containing the developer, is surrounded by a developing casing 138. Inside the hopper portion 134, a lever-shaped stirring member that rotates counterclockwise in FIG. 134a, the stirring member 134a is rotated in accordance with the development operation, and the developer in the hopper portion 134 is stirred and carried out, and the developer is supplied.

The developing casing 138 includes a hopper 134
Although formed along the operation area of the agitating member 134a inside, there is a protruding portion 138a protruding outward near the developing roller 131, and the blade 133 is mounted and supported on the protruding portion 138a. The developer discharged from the hopper 134 is frictionally charged between the developing roller 131, the blade 133, and the supply roller 132.

A charging roller 136 serving as a developer charging unit
Is provided in the vicinity of the photosensitive drum 10 in contact with the developing roller 131 and upstream of the developing area in the rotation direction of the developing roller 131. The charging roller 136 is made of a conductive sponge-like elastic body around a conductive cored bar and has a volume resistance of 10%.
^A first layer of ⁵ Ω · cm or less, and a surface (outer peripheral surface) of the first layer
Is an elastic roller constituted by a second layer as a thin protective layer having a volume resistance of 10 ⁶ Ω · cm or more. The charging roller 136 is a developing roller 1 that carries a toner layer before development.
31 is rotated via the toner layer. The charging roller 136 has the same polarity (minus polarity in the present embodiment) as the toner pole to be used. For example, a DC voltage of about −600 V, a frequency (Hz) of about 1 kHz, and a peak-to-peak voltage (V _{p− p} ) applies a charging roller bias VT1 on which an AC voltage of about 4 kV _pp is superimposed to generate an oscillating electric field between the developing roller 131 and the charging roller 136. The nonmagnetic one-component developer (toner) is charged by an oscillating electric field generated between the developing roller 131 and the charging roller 136.

A discharging roller 135 serving as a developer discharging means
Is provided in the vicinity of the entrance of the developing casing 138 on the downstream side in the rotation direction of the developing roller 131 in the developing area. The static elimination roller 135 has a conductive sponge-like elastic body in which conductive carbon powder is dispersed around a conductive core metal, and has a high resistance (10 ⁶ to 10 ¹⁰ Ω) on the surface.
/ Cm ² ) is an elastic roller covered with a thin protective layer. The charge removing roller 135 abuts on the developing roller 131 via the toner layer collected after the development is completed, and is driven to rotate.
The neutralizing roller 135 has the same polarity (minus polarity in this embodiment) as the toner pole to be used, for example, -100 V
To a DC voltage of about 1 kHz frequency (Hz),
An elimination roller bias VJ1 on which an AC voltage having a peak-to-peak voltage (V _pp ) of about 1 kV _pp is applied to generate an oscillating electric field between the developing roller 131 and the elimination roller 135. The developing roller 131 and the one-component developer (toner) are discharged by AC discharge of an oscillating electric field generated between the developing roller 131 and the discharging roller 135, and the one-component developer (toner) from the supply roller 132 to the developing roller 131 is discharged. ) And the recovery of the one-component developer (toner) from the developing roller 131 to the supply roller 132 is performed satisfactorily.

In the above configuration, the developing roller 131,
Supply roller 132, charging roller 136, and discharging roller 1
35 and the like are generally driven unitarily by a developing drive motor (not shown) through a drive system (not shown). The adhesive force between the developing roller 131 and the developer (toner) includes the above-described electric adhesive force due to frictional charging and the physical (mechanical) adhesive force. The contact pressure of the roller 131 and the contact pressure of the blade 133 and the developing roller 131 are determined.
31, the contact pressure (contact pressure P2) of the supply roller 132 with the developing roller 131, which is forcibly driven to increase the driving torque, and the developing roller 1 of the charging roller 136.
Due to the relationship with the contact pressure (contact pressure P <b> 1) with the developing roller 31, the adhesive force of the developer (toner) to the charging roller 136 becomes stronger than the adhesive force of the developer (toner) to the developing roller 131 at the position of the charging roller 136. The developer adheres to the charging roller 136, and the charging roller 136 is contaminated and does not operate normally.

For this reason, the charging roller 136 shown in FIG.
The contact pressure P1 between the developing roller 131 and the supply roller 1
Setting (P1 <P2) smaller than the contact pressure P2 between the developing roller 131 and the developing roller 131 can prevent the developer (toner) from being properly formed on the developing roller 131 (one or two thin layers). Toner layer formation) and the charging roller 13
The contact pressure P1 is preferably 3 × P1 with respect to the contact pressure P2.
By setting <P2, it is possible to form an appropriate layer of the developer (toner) on the developing roller 131 (form a thin layer of about one or two layers) and to form the developer (toner) on the charging roller 136. It has been experimentally confirmed that it is more preferable to prevent the adhesion of the toner.

Specifically, the contact pressure P2 of the supply roller 132 to the developing roller 131 is 500 to 2000 g / c.
It is preferably set to about m ² , preferably about 1000 to 1500 g / cm ^{2 in} order to form a thin layer by the supply roller 132 and to perform collection and supply. Contact pressure P
Is greater than 2000 g / cm ² , the load torque on the developing drive motor (not shown) becomes too high. In addition to this, charging the contact pressure P1 to the developing roller 131 of the roller 136, 50~700g / cm ^2, preferably about developer to be developing roller 131 set to about 100 to 200 g / cm ² (Toner) layer formation (1)
Layer or a thin toner layer of about two layers) and prevent the developer (toner) from adhering to the charging roller 136. Contact pressure P1 is 50 g / cm ²
In the following case, the charging roller 136 and the developing roller 131 may be out of contact with each other.

As described above, by setting the contact pressure of the charging roller with the developer carrier (developing roller) lower than the contact pressure of the supply roller with the developer carrier, the developer at the charging roller position (Toner) has a stronger adhesive force with the developer carrier, prevents the toner from adhering to the charging roller, makes it difficult for the charging roller to be contaminated, and provides a developing device in which the charging roller operates normally. It becomes possible.

The contact pressure (contact pressure P2) of the supply roller 132 with the developing roller 131, which is forcibly driven in opposition to the developing roller 131 and increases the driving torque, and the developing roller 131 of the charge removing roller 135 with the developing roller 131. Due to the relationship with the contact pressure (contact pressure P3), at the position of the charge eliminating roller 135, the adhesive force of the developer (toner) to the charge eliminating roller 135 becomes stronger than the adhesive force of the developer (toner) to the developing roller 131. The developer adheres to the toner, and the charge removing roller 135 is contaminated and does not function normally.

For this reason, the discharging roller 135 shown in FIG.
The contact pressure P3 between the developing roller 131 and the supply roller 1
Setting (P3 <P2) smaller than the contact pressure P2 between the developing roller 131 and the developing roller 131 can prevent the developing roller 131 from forming an appropriate layer of developer (toner) (one or two thin layers). (Toner layer formation), and
The contact pressure P3 is preferably 3 × P3 with respect to the contact pressure P2.
By setting <P2, it is possible to form an appropriate layer of the developer (toner) on the developing roller 131 (form a thin toner layer of about one or two layers) and to form the developer (toner) on the discharging roller 135. It has been experimentally confirmed that it is more preferable to prevent the adhesion of the toner.

Specifically, the contact pressure P2 of the supply roller 132 against the developing roller 131 is 500 to 2000 g / c.
It is preferably set to about m ² , preferably about 1000 to 1500 g / cm ^{2 in} order to form a thin layer by the supply roller 132 and to perform collection and supply. Contact pressure P
Is greater than 2000 g / cm ² , the load torque on the developing drive motor (not shown) becomes too high. In addition to this, the contact pressure P1 to the developing roller 131 of the discharging roller 135, 50~700g / cm ^2, preferably about developer to be developing roller 131 set to about 100 to 200 g / cm ² (Toner) layer formation (1)
Layer or a thin toner layer of about two layers) and prevent the developer (toner) from adhering to the charge eliminating roller 135. Contact pressure P1 is 50 g / cm ²
In the following cases, a case may occur in which the discharging roller 135 and the developing roller 131 are not in contact with each other.

As described above, the contact pressure of the charge eliminating roller with the developer carrying member (developing roller) is set lower than the contact pressure of the supply roller and the developer carrying member, so that the developer at the position of the charge eliminating roller is adjusted. (Toner) has a stronger adhesive force with the developer carrying member, prevents the toner from adhering to the charge eliminating roller, makes it difficult for the charge eliminating roller to be contaminated, and provides a developing device in which the charge eliminating roller operates normally. It becomes possible.

Embodiment 2 A developing device according to claim 5 or 6 of the present invention will be described with reference to FIG. 3 or FIG. FIG. 3 is an enlarged cross-sectional configuration diagram of a developing device according to claim 5 or 6 of the present invention, and FIG. 4 is a diagram illustrating driving of a charging roller and a charge removing roller in FIG.

According to FIG. 3 or FIG. 4, as shown in FIG. 3, the developing device 13 which is a developing means for each color includes yellow (Y), magenta (M), cyan (C) and black (K).
In the present embodiment, a negatively charged non-magnetic one-component developer (toner) is accommodated, respectively, and comes into contact with (contacts) the peripheral surface of the photosensitive drum 10. Developing roller 13 that rotates in the rotating direction (clockwise in FIG. 3) and in the forward direction (counterclockwise in FIG. 3)
1 is provided. A supply roller 132, which is a toner supply member, is provided in contact with the developing roller 131.
By 2, the supply of the toner to the developing roller 131 and the collection of the toner from the developing roller 131 are performed. The supply roller 132 is provided in the supply section in parallel with the developing roller 131, and is rotated in the same direction as the developing roller 131 (counterclockwise in FIG. 3).

The developing roller 131, which is a developer carrier,
For example, a hardness of 45 ° (JIS)
In A), it is formed of only a single layer of solid rubber such as urethane or silicon having a volume resistance of 10 ⁷ Ω · cm without a surface protection layer, and is rotated counterclockwise in FIG. 3 by a developing drive motor Ma. During development, with respect to the developing roller 131,
A developing bias VB1 of the same polarity as the toner polarity to be used (minus polarity in the present embodiment) and a DC voltage of about -250 V is applied to perform one-component inversion development of contact.
A negative polarity toner on the developing roller 131 is attached to a latent image portion (image portion) having an image potential of about −50 V on the photosensitive drum 10, and a toner image is formed on the latent image portion on the photosensitive drum 10. To form

Supply roller 132 serving as a toner supply member
Is formed on the outside (outer peripheral surface) of a conductive metal core (unsigned) such as stainless steel by forming a foamed rubber layer (unsigned) having a volume resistance of 10 ⁶ Ω · cm with a foamed rubber such as urethane or silicon. The rotation of the developing roller 131 abutted by the developing drive motor Ma through a driving system (not shown) (FIG. 3)
(Counterclockwise direction in FIG. 3), and is forcibly driven in the opposite direction (counterclockwise direction in FIG. 3) at the contact position. At the time of development, a supply roller bias VK1 of a DC voltage of about -500 V having the same polarity (minus polarity in the present embodiment) as the polarity of the toner to be used is applied to the supply roller 132.

The blade 133, which is a developer regulating member,
For example, the blade 133 is a band-shaped elastic plate made of stainless steel having a thickness of about 0.1 mm, and the blade 133 is disposed with its tip directed to the upstream side in the rotation direction of the developing roller 131. This is a so-called counter type developer regulating member that regulates the height and amount of the layer). The blade 133 may be a so-called trail-type developer regulating member whose tip is disposed downstream in the rotation direction of the developing roller 131. With this blade 133, one layer or two layers are formed on the developing roller 131.
A developer layer as thin as about two layers is formed.

A hopper portion 134, which is a developer accommodating portion for storing the developer, is surrounded by a developing casing 138. Inside the hopper portion 134, a lever-shaped stirring member which rotates counterclockwise in FIG. 134a, the stirring member 134a is rotated in accordance with the development operation, and the developer in the hopper portion 134 is stirred and carried out, and the developer is supplied.

The developing casing 138 includes a hopper 134
Although formed along the operation area of the agitating member 134a inside, there is a protruding portion 138a protruding outward near the developing roller 131, and the blade 133 is mounted and supported on the protruding portion 138a. The developer discharged from the hopper 134 is frictionally charged between the developing roller 131, the blade 133, and the supply roller 132.

A charging roller 136 serving as a developer charging unit
Is in contact with the developing roller 131 and has a drive circuit as described later.
And the upstream side in the rotation direction of the developing roller 131 in the developing area.
In the vicinity of the photosensitive drum 10. Charging roller 1
36 is a conductive core made of aluminum or stainless steel
Around the conductive core metal, for example, urethane rubber.
Carbon black, graphite, iron black (Fe_ThreeO_Four) Etc.
Mixed, volume resistance is 10 ^FiveΩ · cm or less conductive
The conductive sponge-like elastic body.
Adhesion of developer (toner) to outer surface (outer peripheral surface) of conductive material
Coating or coating with a fluorine-based resin material to prevent
And a release layer RLa having a thickness of about 10 to 100 μm.
The elastic roller is formed by providing the elastic roller. Charging roller 13
6 has the same polarity as the toner pole to be used (in the present embodiment,
Is a negative polarity), for example, a DC voltage of about -600 V
The frequency (Hz) is about 1 kHz and the peak-to-peak voltage
(V_{p- p}) Is 4kV_ppCharger with superimposed AC voltage
Roller bias VT1 to charge the developing roller 131
An oscillating electric field is generated between the roller and the roller 136. This development
Vibration generated between roller 131 and charging roller 136
The non-magnetic one-component developer (toner) is charged by the electric field.

As described above, the developer (toner) is applied to the charging roller 136 which is rotated by being brought into contact with the developing roller 131 formed without the surface protective layer using only the single layer of urethane or solid rubber such as silicon. ) Is attached to the surface of the charging roller 136 to prevent the release layer RL from adhering.
a is preferably provided to release the developer (toner). However, as in the conventional case, the charging roller 136 is brought into contact with the developing roller 131 carrying the toner layer before development via the toner layer and is driven by the charging roller 136. In the case of a configuration in which the toner is rotated, the release layer RLa is provided to improve the releasability from the developer (toner) on the surface of the charging roller 136 and the releasability from the developer (toner) on the surface of the developing roller 131. If the height is too high, the charging roller 136 slips.

Therefore, as described above, the charging roller 13
6 is provided with a release layer RLa, and the release property between the charging roller 136 and the developer (toner) is formed only with a single layer of solid rubber such as urethane or silicon without a surface protection layer. The developer (toner) of the developing roller 131 to be contacted is set higher than the releasability from the developer (toner) to prevent the developer (toner) from adhering to the charging roller 136, and as shown in FIG. A developing drive motor Ma;
A developing roller driving gear Gx that is attached to one end of the central axis (no symbol) of the developing roller 131 and that rotates the developing roller 131 through a driving system (not shown) by a developing driving motor Ma; The charging roller driving gear Ga is provided as charging roller driving means, and the charging roller 136 is driven to rotate by the charging roller driving gear Ga. The gear ratio between the developing roller driving gear Gx and the charging roller driving gear Ga is made equal to the ratio between the outer diameter of the developing roller 131 and the outer diameter of the charging roller 136, and the charging roller 136 is developed at the same speed as the developing roller 131. Roller 131
In the rotation direction (counterclockwise in FIG. 4) and in the forward direction (clockwise in FIG. 4).

As described above, by providing the charging roller driving means, the releasability from the developer (toner) on the surface of the charging roller by the release layer is maintained, and the adhesion of the developer (toner) to the charging roller is prevented. However, it is possible to provide a developing device that prevents the charging roller from slipping.

Further, a discharging roller 1 serving as a developer discharging means is provided.
Reference numeral 35 is provided in contact with the developing roller 131 and near the entrance of the developing casing 138 on the downstream side of the developing area in the rotation direction of the developing roller 131. The static elimination roller 135 is made of a conductive core made of aluminum or stainless steel, and a conductive sponge-like elastic body of, for example, urethane rubber around the conductive core. A fluorine-based resin material is applied or coated on the outer surface (outer peripheral surface) of the elastic body to prevent the developer (toner) from adhering, and a release layer RLb having a layer thickness of about 10 to 100 μm is provided. An elastic roller formed by The charge removing roller 135 comes into contact with the developing roller 131 via a toner layer collected after development is completed, and is driven and rotated as described later. The neutralizing roller 135 has the same polarity as the toner pole to be used (minus polarity in the present embodiment), for example, a DC voltage of about -100 V, a frequency (Hz) of about 1 kHz, and a peak-to-peak voltage (V _pp ). Is applied with a discharging roller bias VJ1 on which an AC voltage of about 1 kV _pp is superimposed, and a developing roller 131 is applied.
An oscillating electric field is generated between the discharge roller 135 and the discharge roller 135. The developing roller 131 and the one-component developer (toner) are discharged by AC discharge of an oscillating electric field generated between the developing roller 131 and the discharging roller 135, and the one-component developer (toner) from the supply roller 132 to the developing roller 131 is discharged. ) And the recovery of the one-component developer (toner) from the developing roller 131 to the supply roller 132 is performed satisfactorily.

As described above, the developer (toner) is applied to the static elimination roller 135, which is made of only a single layer of solid rubber such as urethane or silicon and is rotated in contact with the developing roller 131 formed without the surface protection layer. ) Is attached to the surface of the charge removing roller 135 to prevent the release layer RL from adhering.
b, it is preferable to have releasability from the developer (toner). However, as in the related art, the discharging roller 135 is brought into contact with the developing roller 131 carrying the toner layer before development via the toner layer and is driven by the toner. In the case of a configuration in which the developer is rotated, by providing the release layer RLb, the releasability from the developer (toner) on the surface of the discharging roller 135 and the releasability from the developer (toner) on the surface of the developing roller 131 are improved. If the height is also high, the discharging roller 135 will slip.

Therefore, as described above, the charge removing roller 13
5 is provided with a release layer RLb, and the release property between the charge removing roller 135 and the developer (toner) is formed only with a single layer of solid rubber such as urethane or silicon without a surface protection layer. The developer (toner) of the developing roller 131 to be contacted is set higher than the releasability from the developer (toner) to prevent the developer (toner) from adhering to the charge eliminating roller 135, as shown in FIG. A developing drive motor Ma;
A developing roller driving gear Gx that is attached to one end of the central axis (no symbol) of the developing roller 131 and that rotates the developing roller 131 through a driving system (not shown) by a developing driving motor Ma; The driving roller Gb is provided as a discharging roller driving unit, and the discharging roller 135 is driven to rotate by the discharging roller driving gear Gb. The ratio between the developing roller driving gear Gx and the discharging roller driving gear Gb is made equal to the ratio between the outer diameter of the developing roller 131 and the outer diameter of the discharging roller 135, and
5 is rotated at the same speed as the developing roller 131 in the rotation direction (counterclockwise in FIG. 4) and the forward direction (clockwise in FIG. 4) of the developing roller 131.

As described above, by providing the discharging roller driving means, the releasing property of the releasing layer from the developer (toner) on the surface of the discharging roller is maintained and the adhesion of the developer (toner) to the discharging roller is prevented. However, it is possible to provide a developing device in which the neutralization roller is prevented from slipping.

Embodiment 3 A developing device according to claim 7 or 8 of the present invention will be described with reference to FIG. FIG. 5 shows a seventh embodiment of the present invention.
FIG. 9 is an enlarged cross-sectional configuration diagram of a developing device according to or 8.

According to FIG. 5, the developing device 13 which is a developing means for each color includes yellow (Y), magenta (M), cyan (C) and black (K). A non-magnetic one-component developer (toner) is accommodated, respectively, and comes into contact with (contacts) the peripheral surface of the photosensitive drum 10. At the developing position, the rotation direction of the photosensitive drum 10 (clockwise direction in FIG. 5) Forward direction (counterclockwise direction in FIG. 5)
And a developing roller 131 that rotates. Developing roller 13
1, a supply roller 132, which is a toner supply member, is provided.
Supply of toner from the developing roller 131 and collection of toner from the developing roller 131 are performed. The supply roller 132 is provided in the supply section in parallel with the developing roller 131, and
1 (counterclockwise in FIG. 5).

The developing roller 131, which is a developer carrying member,
For example, a hardness of 45 ° (JIS)
In A), it is formed of a solid rubber such as urethane or silicon having a volume resistance of 10 ⁷ Ω · cm. At the time of development, the developing roller 131 is applied with a developing bias VB1 having the same polarity as the toner polarity to be used (minus polarity in the present embodiment) and a DC voltage of about -250 V to perform one-component inversion development of contact. The developing roller 1 is applied to a latent image portion (image portion) on the photosensitive drum 10 which has an image portion potential of about −50 V.
The toner of the negative polarity on 31 is attached to form a toner image on the latent image portion on the photosensitive drum 10.

Supply roller 132 as toner supply member
Is formed on the outside (outer peripheral surface) of a conductive metal core (unsigned) such as stainless steel by forming a foamed rubber layer (unsigned) having a volume resistance of 10 ⁶ Ω · cm with a foamed rubber such as urethane or silicon. And is forcibly driven in the opposite direction (counterclockwise direction in FIG. 5) at the contact position by the developing drive motor (not shown) in opposition to the rotation (counterclockwise direction in FIG. 5) of the developing roller 131 that comes into contact. . At the time of development, a supply roller bias VK1 of a DC voltage of about -500 V having the same polarity (minus polarity in the present embodiment) as the polarity of the toner to be used is applied to the supply roller 132.

The blade 133, which is a developer regulating member,
For example, the blade 133 is a band-shaped elastic plate made of stainless steel having a thickness of about 0.1 mm, and the blade 133 is disposed with its tip directed to the upstream side in the rotation direction of the developing roller 131. This is a so-called counter type developer regulating member that regulates the height and amount of the layer). The blade 133 may be a so-called trail-type developer regulating member whose tip is disposed downstream in the rotation direction of the developing roller 131. With this blade 133, one layer or two layers are formed on the developing roller 131.
A developer layer as thin as about two layers is formed.

A hopper portion 134, which is a developer accommodating portion for storing the developer, is surrounded by a developing casing 138. Inside the hopper portion 134, a lever-shaped stirring member which rotates counterclockwise in FIG. 134a, the stirring member 134a is rotated in accordance with the development operation, and the developer in the hopper portion 134 is stirred and carried out, and the developer is supplied.

The developing casing 138 includes a hopper 134
Although formed along the operation area of the agitating member 134a inside, there is a protruding portion 138a protruding outward near the developing roller 131, and the blade 133 is mounted and supported on the protruding portion 138a. The developer discharged from the hopper 134 is frictionally charged between the developing roller 131, the blade 133, and the supply roller 132.

Charging roller 136 as a developer charging means
Is provided in the vicinity of the photosensitive drum 10 in contact with the developing roller 131 and upstream of the developing area in the rotation direction of the developing roller 131. The charging roller 136 is made of a conductive sponge-like elastic body around a conductive cored bar and has a volume resistance of 10%.
^A first layer of ⁵ Ω · cm or less, and a surface (outer peripheral surface) of the first layer
Is an elastic roller constituted by a second layer as a thin protective layer having a volume resistance of 10 ⁶ Ω · cm or more. The charging roller 136 is a developing roller 1 that carries a toner layer before development.
31 is rotated via the toner layer. The charging roller 136 has the same polarity (minus polarity in the present embodiment) as the toner pole to be used. For example, a DC voltage of about −600 V, a frequency (Hz) of about 1 kHz, and a peak-to-peak voltage (V _{p− p} ) applies a charging roller bias VT1 on which an AC voltage of about 4 kV _pp is superimposed to generate an oscillating electric field between the developing roller 131 and the charging roller 136. The nonmagnetic one-component developer (toner) is charged by an oscillating electric field generated between the developing roller 131 and the charging roller 136.

A developer (toner) is applied to the charging roller 136.
If the toner adheres, the charging roller 136 does not function normally. Therefore, a charging roller cleaning blade 136a is provided as charging roller cleaning means for contacting the charging roller 136 and removing the developer (toner) attached to the surface of the charging roller 136. . The developer (toner) removed from the charging roller 136 is transferred to the developer transport pipe 1 for removing the charging roller.
The developer is transferred again to the hopper section 134 serving as a developer accommodating section by the charging roller removing developer transporting screw 136b as a charging roller removing developer transporting means through 36c. The developer (toner) returned to the inside of the hopper unit 134 by the charging roller removing developer conveying screw 136b.
Is agitated by the unused developer (toner) and the agitating member 134a inside the hopper section 134, and then reused.

As described above, by providing the charging roller cleaning means, the developer (toner) adhered to the charging roller is removed, the charging roller functions normally, and the developer (toner) adhered to the charging roller is removed. It is possible to provide a developing device that is reused and has a longer service life.

Further, a discharging roller 1 serving as a developer discharging means is provided.
Reference numeral 35 is provided in contact with the developing roller 131 and near the entrance of the developing casing 138 on the downstream side of the developing area in the rotation direction of the developing roller 131. The static elimination roller 135 has a conductive sponge-like elastic body in which conductive carbon powder is dispersed around a conductive cored bar, and has a surface with a high resistance (10 ⁶ to 10).
The elastic roller has a configuration covered with a thin protective layer of ¹⁰ Ω / cm ² ). The charge removing roller 135 abuts on the developing roller 131 via the toner layer collected after the development is completed, and is driven to rotate. The neutralizing roller 135 has the same polarity (minus polarity in this embodiment) as the toner pole to be used.
A DC bias voltage of about 0 V is applied with a neutralizing roller bias VJ1 in which an AC voltage having a frequency (Hz) of about 1 kHz and a peak-to-peak voltage (V _pp ) of about 1 kV _pp is applied. An oscillating electric field is generated between them. The developing roller 131 and the one-component developer (toner) are neutralized by an AC discharge of an oscillating electric field generated between the developing roller 131 and the neutralizing roller 135, and the supply roller 13 is discharged.
The supply of the one-component developer (toner) from the developing roller 131 to the developing roller 131 and the collection of the one-component developer (toner) from the developing roller 131 to the supply roller 132 are performed satisfactorily.

A developer (toner) is applied to the charge eliminating roller 135.
If the toner adheres, the static elimination roller 135 does not function normally. Therefore, the static elimination roller cleaning blade 135a which is a static elimination roller cleaning unit that contacts the static elimination roller 135 and removes the developer (toner) attached to the surface of the static elimination roller 135 is provided. . The developer (toner) removed from the charge removing roller 135 is transferred to the developer transfer pipe 1 for removing the charge removing roller.
The developer is transferred to the hopper section 134, which is a developer accommodating portion, by the developer-transfer roller-removed developer conveying screw 135b serving as a static-removal-roller-removed developer conveying unit through 35c. The developer (toner) returned to the inside of the hopper unit 134 by the developer transfer screw 135b for removing the charge removing roller.
Is agitated by the unused developer (toner) and the agitating member 134a inside the hopper section 134, and then reused.

As described above, by providing the discharging roller cleaning means, the developer (toner) adhered to the discharging roller is removed, the discharging roller functions normally, and the developer (toner) adhered to the discharging roller is removed. It is possible to provide a developing device that is reused and has a longer service life.

Embodiment 4 A developing device according to claim 9 or 10 of the present invention will be described with reference to FIGS. 6 to 8 and Table 1. FIG.
FIG. 7 is an enlarged cross-sectional configuration diagram of a developing device according to claim 9 or 10 of the present invention. FIG. 7 is a diagram illustrating a reference patch. FIG. 8 is a control block diagram of a supply roller bias. Shows a supply roller bias table with relative humidity versus number of prints.

According to FIGS. 6 to 8, as shown in FIG. 6, the developing device 13 as a developing means for each color includes yellow (Y), magenta (M), cyan (C) and black (K).
In the present embodiment, a negatively charged non-magnetic one-component developer (toner) is accommodated, respectively, and comes into contact with (contacts) the peripheral surface of the photosensitive drum 10, and the developing device 13.
The rotation direction of the photosensitive drum 10 at the developing position (see FIG. 6)
And a developing roller 131 that rotates in the forward direction (counterclockwise in FIG. 6). A supply roller 132, which is a toner supply member, is provided in contact with the developing roller 131,
The supply roller 132 supplies the toner to the developing roller 131 and collects the toner from the developing roller 131. The supply roller 132 is provided in the supply unit in parallel with the developing roller 131, and is rotated in the same direction as the developing roller 131 (counterclockwise in FIG. 6). The developing device 13 is rotated in the rotation direction of the photosensitive drum 10 (clockwise direction in FIG. 6).
A light emitting device PD1 and a light receiving device PD2 using, for example, a photocoupler to measure the image density
Density detection sensor DSa as density detection means comprising
Is provided.

The developing roller 131, which is a developer carrier,
For example, a hardness of 45 ° (JIS)
In A), it is formed of a solid rubber such as urethane or silicon having a volume resistance of 10 ⁷ Ω · cm. At the time of development, the developing roller 131 is applied with a developing bias VB1 having the same polarity as the toner polarity to be used (minus polarity in the present embodiment) and a DC voltage of about -250 V to perform one-component inversion development of contact. The developing roller 1 is applied to a latent image portion (image portion) on the photosensitive drum 10 which has an image portion potential of about −50 V.
The toner of the negative polarity on 31 is attached to form a toner image on the latent image portion on the photosensitive drum 10.

Supply roller 132 serving as a toner supply member
Is formed on the outside (outer peripheral surface) of a conductive metal core (unsigned) such as stainless steel by forming a foamed rubber layer (unsigned) having a volume resistance of 10 ⁶ Ω · cm with a foamed rubber such as urethane or silicon. And is forcibly driven in the opposite direction (counterclockwise direction in FIG. 6) at the contact position by the developing drive motor (not shown) in opposition to the rotation (counterclockwise direction in FIG. 6) of the developing roller 131 that contacts. . At the time of development, a supply roller bias VK1 of a DC voltage of about -500 V having the same polarity (minus polarity in the present embodiment) as the polarity of the toner to be used is applied to the supply roller 132.

The blade 133, which is a developer regulating member,
For example, the blade 133 is a band-shaped elastic plate made of stainless steel having a thickness of about 0.1 mm, and the blade 133 is disposed with its tip directed to the upstream side in the rotation direction of the developing roller 131. This is a so-called counter type developer regulating member that regulates the height and amount of the layer). The blade 133 may be a so-called trail-type developer regulating member whose tip is disposed downstream in the rotation direction of the developing roller 131. With this blade 133, one layer or two layers are formed on the developing roller 131.
A developer layer as thin as about two layers is formed.

A hopper section 134, which is a developer accommodating section for storing the developer, is surrounded by a developing casing 138. Inside the hopper section 134, a lever-shaped stirring member which rotates counterclockwise in FIG. 134a, the stirring member 134a is rotated in accordance with the development operation, and the developer in the hopper portion 134 is stirred and carried out, and the developer is supplied.

The developing casing 138 includes a hopper 134
Although formed along the operation area of the agitating member 134a inside, there is a protruding portion 138a protruding outward near the developing roller 131, and the blade 133 is mounted and supported on the protruding portion 138a. The developer discharged from the hopper 134 is frictionally charged between the developing roller 131, the blade 133, and the supply roller 132.

Charging roller 136 as developer charging means
Is provided in the vicinity of the photosensitive drum 10 in contact with the developing roller 131 and upstream of the developing area in the rotation direction of the developing roller 131. The charging roller 136 is made of a conductive sponge-like elastic body around a conductive cored bar and has a volume resistance of 10%.
^A first layer of ⁵ Ω · cm or less, and a surface (outer peripheral surface) of the first layer
Is an elastic roller comprising a second layer as a thin protective layer having a volume resistance of 10 ⁶ Ω · cm or more. The charging roller 136 is a developing roller 1 that carries a toner layer before development.
31 is in contact with the toner layer 31 via the toner layer and is driven to rotate. The charging roller 136 has the same polarity (minus polarity in the present embodiment) as the toner pole to be used. For example, a DC voltage of about −600 V, a frequency (Hz) of about 1 kHz, and a peak-to-peak voltage (V _{p− p} ) applies a charging roller bias VT1 on which an AC voltage of an appropriate value according to the use environment conditions and the use frequency is applied, and generates an oscillating electric field between the developing roller 131 and the charging roller 136. The nonmagnetic one-component developer (toner) is charged by an oscillating electric field generated between the developing roller 131 and the charging roller 136.

In the developing device 13, the charge amount of the developer (toner) changes depending on the use environment conditions and the use frequency. Further, the resistance of the charging roller 136 also changes depending on the use environment conditions, the use frequency, and the like, and the charge amount at the time of charging by the charging roller does not stabilize and changes from an appropriate value. As a result, the gradation of the image changes, and therefore, as shown in FIG.
A counter CT is provided as a counting means for counting the number of uses (the number of prints) by the counter CT, and a humidity sensor HSa, for example, is provided inside the image forming apparatus as an environmental condition detecting means for detecting a use environment condition. The humidity sensor (HSa) measures the internal humidity (relative humidity (RH%)) and changes the value of the peak-to-peak voltage (V _pp ) of the AC voltage of the charging roller bias VT1 according to the values of the humidity sensor HSa and the counter CT. I do.

More specifically, as described above, the polarity (the toner in the present embodiment) is the same as that of the toner (toner during development) used by the scorotron charger 11 (see FIG. 1, not shown in FIG. 6). The photoconductor drum 10 is given a uniform potential of, for example, -700 V by corona discharge of (polarity), an image is written by the exposure optical system 12, and a negative polarity DC voltage, for example, -250 is applied to the developing roller 131.
V is applied, and a negative DC voltage, for example, -500 V, is applied to the supply roller 132 to develop the image to an appropriate image density. The image density is determined by the relative humidity (use environment conditions) and the number of prints (use frequency). Is changed. For this reason, the reference patch pattern previously stored in the ROM of the storage unit is written on the photosensitive drum 10 by the exposure optical system 12 through the control unit, and the image on the photosensitive drum 10 is developed by the developing device 13. The density, for example, the density of the reference patch ND having five levels (five levels) as shown in FIG. 7 is measured by the density detection sensor DSa. However, when the variation between the machines is small, a reference table corresponding to a predetermined condition is stored in the storage unit without performing the density measurement using the reference patch pattern for each machine, and this is stored in the storage unit. Is used to set conditions.

The operating environment conditions and the number of prints (frequency of use) were changed by experiments in advance, and the peak-to-peak voltage (V _pp ) of the AC voltage of the charging roller bias VT1 applied to the charging roller 136 for each level was changed. Measures the values and tabulates them as a reference table in the ROM of the storage unit
Stored in Table 1 shows a reference table of level 3, which is the median value of the reference patch ND and is an appropriate density value.

[0102]

[Table 1]

In Table 1, each set point is used by interpolation. Depending on the use environment conditions (relative humidity) and use frequency (number of prints) of the image forming apparatus,
Using the reference table of level 3 shown in Table 1 in the ROM of the storage unit, the setting is changed to the value of the peak-to-peak voltage (V _pp ) of the AC voltage of the charging roller bias VT1 according to the relative humidity and the number of prints. The fluctuation of the charge amount is suppressed, and the developing roller 13
1, the charge amount of the developer (toner) is an appropriate value, that is, 10 to 30 which is the preferable charge amount of the developer (toner) used in the development described in the developing device 13 of FIG.
The charge amount is about μC / g.

Further, at the time of maintenance or power-on of the image forming apparatus described with reference to FIG. 1, a reference patch ND is formed on the photosensitive drum 10, and level 3 image density data is measured by the density detection sensor DSa. And level 3
In the case where the image density differs from the original proper image density, for example, when the relative humidity is 50% and the image density data of level 3 is deep and the density is about level 4 when the number of prints is 5000, the data is shown in Table 1. The peak-to-peak voltage (V _pp ) and the set value of 2.5 kV _pp are stored in the ROM
Is reset to an appropriate value of 2.5 kV _pp or less using the lookup table of level 2 in FIG. When the image density data is light and has a density of about level 2, the peak-to-peak voltage (V _pp ) shown in Table 1 and the set value of 2.5 kV _pp are referred to the level 4 in the ROM described above. Using a table, reset to an appropriate value of 2.5 kV _pp or more.

As described above, even if the use environment conditions and the use frequency change, the amount of charge at the time of charging by the charging roller is made stable and appropriate, and the developing device which does not change the image gradation is provided. Becomes possible.

[0106]

According to the first or second aspect, the contact pressure of the charging roller with the developer carrier (developing roller) is set lower than the contact pressure of the supply roller with the developer carrier. At the position of the charging roller, the developer (toner) has a stronger adhesive force with the developer carrier, and prevents the developer from being attached to the charging roller. Thus, it is possible to provide a developing device.

According to the third or fourth aspect, the contact pressure of the charge eliminating roller with the developer carrier (developing roller) is set lower than the contact pressure of the supply roller with the developer carrier.
At the position of the static elimination roller, the developer (toner) has a stronger adhesive force with the developer carrying member, and prevents adhesion to the static eliminator roller, thereby making it difficult for the static eliminator roller to be contaminated. Thus, it is possible to provide a developing device.

According to the fifth aspect, by providing the charging roller driving means, the releasability of the releasing layer from the developer (toner) on the charging roller surface is maintained, and the developer (toner) is transferred to the charging roller. It is possible to provide a developing device that prevents the charging roller from slipping while preventing adhesion.

According to the sixth aspect, by providing the discharging roller driving means, the releasing property of the releasing roller from the developer (toner) on the discharging roller surface is maintained, and the developer (toner) is transferred to the discharging roller. It is possible to provide a developing device that prevents the static elimination roller from slipping while preventing adhesion.

According to the seventh aspect, by providing the charging roller cleaning means, the developer (toner) adhered to the charging roller is removed, so that the charging roller functions normally and the developer (adhesive developer) ( (Toner) can be reused, and a developing device with an improved service life can be provided.

According to the eighth aspect of the present invention, by providing the static elimination roller cleaning means, the developer (toner) adhered to the static elimination roller is removed, the normal operation of the static elimination roller and the adhesion developer (toner) of the static elimination roller are achieved. (Toner) can be reused, and a developing device with an improved service life can be provided.

According to the ninth or tenth aspect, even when the use environment conditions, the use frequency, and the like change, the amount of charge at the time of charging by the charging roller is stable and appropriate, and the image gradation changes. It is possible to provide a developing device without any.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a color image forming apparatus showing an embodiment of an image forming apparatus using a developing device common to the claims of the present invention.

FIG. 2 is an enlarged cross-sectional configuration diagram of a developing device according to claims 1 to 4 of the present invention.

FIG. 3 is an enlarged cross-sectional configuration diagram of a developing device according to claim 5 or 6 of the present invention.

FIG. 4 is a diagram showing driving of a charging roller and a discharging roller of FIG. 3;

FIG. 5 is an enlarged cross-sectional configuration diagram of a developing device according to claim 7 or 8 of the present invention.

FIG. 6 is an enlarged cross-sectional configuration diagram of a developing device according to claim 9 or 10 of the present invention.

FIG. 7 is a diagram showing a reference patch.

FIG. 8 is a control block diagram of a supply roller bias.

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13 developing device 14a intermediate transfer belt 14c primary transfer device 14g secondary transfer device 15b timing roller 131 developing roller 132 supply roller 133 blade 134 hopper section 134a stirring member 135 static elimination roller 135a Static elimination roller cleaning blade 135b Static elimination roller removed developer transport screw 135c Static elimination roller removed developer transport pipe 136 Charging roller 136a Charge roller cleaning blade 136b Charge roller removed developer transport screw 136c Charge roller removed developer transport pipe 138 Developing casing CT Counter DSa Density detection sensor Ga Charging roller driving gear Gb Static elimination roller driving gear Gx Developing roller driving gear HSa Humidity sensor Ma Developing drive Over data ND reference patch P recording paper RLa, RLb release layer VB1 developing bias VJ1 discharging roller bias VK1 supply roller bias VT1 charging roller bias

Continued on front page F term (reference) 2H077 AA37 AC02 AC04 AC16 AD06 AD13 AD17 AD23 AD35 AE01 AE03 AE04 AE08 CA10 CA19 DA03 DA18 DA22 DB14 EA14 EA15 FA13 FA22 FA25 GA13 GA17

Claims (10)

[Claims] 1. A developer carrier that holds and rotates a thin layer of non-magnetic one-component developer, a supply roller that supplies and recovers the developer to and from the developer carrier, A developer regulating member that regulates the amount of the developer and a charging roller that controls the amount of charge of the developer on the developer carrier, wherein a contact between the charging roller and the developer carrier is performed. Pressure P1
Is the contact pressure P between the supply roller and the developer carrier.
A developing device characterized by being smaller than 2. 2. The developing device according to claim 1, wherein the contact pressure P1 satisfies 3 × P1 <P2 with respect to the contact pressure P2. 3. A developer carrier that holds and rotates a thin layer of non-magnetic one-component developer, a supply roller that supplies and collects the developer to and from the developer carrier, A developer regulating member that regulates the amount of the developer, and a charge removing roller that removes the charge amount of the developer on the developer carrier, wherein the contact between the charge removing roller and the developer carrier is performed. Pressure P3
Is the contact pressure P between the supply roller and the developer carrier.
A developing device characterized by being smaller than 2. 4. The developing device according to claim 3, wherein the contact pressure P3 satisfies 3 × P3 <P2 with respect to the contact pressure P2. 5. A developer carrier that holds and rotates a thin layer of non-magnetic one-component developer, a supply roller that supplies and collects the developer to and from the developer carrier, A developer regulating member that regulates the amount of developer, and a charging roller that controls the amount of charge of the developer on the developer carrier, wherein the charging roller is moved at a constant speed with the developer carrier. A developing device, further comprising: a charging roller driving unit for driving, wherein the releasability of the charging roller from the developer is higher than the releasability of the developer carrier from the developer. 6. A developer carrier that holds and rotates a thin layer of non-magnetic one-component developer, a supply roller that supplies and recovers the developer to and from the developer carrier, A developer regulating member that regulates the amount of developer, and a static elimination roller that neutralizes the charge amount of the developer on the developer carrier, wherein the static elimination roller is moved at a constant speed with the developer carrier. A developing device, further comprising: a discharging roller driving unit for driving, wherein a releasing property of the discharging roller from the developer is higher than a releasing property of the developer carrier from the developer. 7. A developer carrier that holds and rotates a thin layer of non-magnetic one-component developer, a supply roller that supplies and recovers the developer to and from the developer carrier, A developer regulating member that regulates the amount of developer, a charging roller that controls the amount of charge of the developer on the developer carrier, a developer accommodating section that accommodates the developer, and a developer accommodating section. A developing device having a transport roller that transports the developer, wherein the charging roller has a charging roller cleaning unit that removes the developer attached to the surface, and the developer removed from the charging roller is stored in the developer storage unit. A developing device comprising a charging roller-removed developer conveying means for conveying. 8. A developer carrier that holds and rotates a thin layer of non-magnetic one-component developer, a supply roller that supplies and recovers the developer to and from the developer carrier, A developer regulating member that regulates the amount of developer, a charge eliminating roller that eliminates the charge amount of the developer on the developer carrier, a developer accommodating section that accommodates the developer, and a developer accommodating section. A developer roller having a transport roller for transporting the developer, wherein the static elimination roller has static elimination roller cleaning means for removing the developer adhered to the surface, and the developer removed from the static elimination roller is stored in the developer accommodating portion. A developing device, comprising: a discharging roller-removed developer conveying means for conveying. 9. A developer carrier that holds and rotates a thin layer of non-magnetic one-component developer, a supply roller that supplies and recovers the developer to and from the developer carrier, A developer regulating member that regulates the amount of developer, and a charging roller that controls the amount of charge of the developer on the developer carrying member. A developing device characterized in that the developing device changes according to the frequency of use. 10. The developing device according to claim 9, wherein said applied bias is changed according to measured image density data.