JP2001265110A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device forming a high-quality stable image, without causing changes in gradation (change of image density) by stably keeping the electrified amount of developer, even if image density, service environmental conditions and the number of using times are changed. SOLUTION: By applying regulating member bias, which gives the potential difference between a developer carrier and a developer regulating member and also providing a density detection means for detecting the density of the formed image, the value of the regulating member bias is changed, according to the transition of the image density detected by the density detection means in this image forming device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus in which a charging means, an image writing means, a developing means and the like are arranged around an image forming body in a copying machine, a printer, a facsimile or the like. The present invention relates to an image forming apparatus having a developing unit used for formation, and more particularly to an image forming apparatus having a developing unit when a non-magnetic one-component developer is used as a developer.

[0002]

2. Description of the Related Art Conventionally, as one method of forming a multicolor image well, a plurality of image forming bodies, charging means, developing means, etc., of the required number of colors are provided. An apparatus is used in which the obtained single-color toner image is superimposed on an intermediate transfer member (intermediate transfer belt or intermediate transfer drum) or the like to form a color image. As a developing unit used in the image forming apparatus, a developing unit using a non-magnetic one-component developer (toner) is employed. The non-magnetic one-component developer used for this has various advantages. A non-magnetic one-component developer is carried and transported, and a developer carrier (developing roller) using an elastic body, which supplies toner to an image forming body (for example, a photosensitive drum used for electrophotography), is provided. 2. Description of the Related Art A roller is brought into contact with (contacted with) a photosensitive drum to uniformly apply an appropriate amount of toner to the photosensitive drum.

[0003]

However, in the non-magnetic one-component contact developing method using an elastic developer carrier (developing roller), the charge amount (Q) of the non-magnetic one-component developer (toner) is increased. / M) is liable to change, and when the charge amount changes, there is a problem that the gradation (image density) changes as a result. Further, a problem arises that the charge amount of the toner varies depending on the use environment conditions of the image forming apparatus and the number of times of use (frequency of use) of the image formation. In this case, the gradation (image density) also changes as a result.

The present invention solves the above-mentioned problems, and maintains the charge amount of the developer stably even when the image density, the use environment conditions, and the number of times of use change, and provides a high-quality stable image without a change in gradation. It is an object of the present invention to provide an image forming apparatus for forming a formed image.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide an image forming body for carrying a latent image, a developer carrying body for holding a thin layer of a non-magnetic one-component developer, and a developer on the developer carrying body. An image forming apparatus having a developer regulating member for regulating the amount,
A regulating member bias for giving a potential difference between the developer carrier and the developer regulating member is applied, and a density detecting unit for detecting the density of a formed image is provided. This is achieved by an image forming apparatus (first invention) wherein the image density is changed according to the transition of the image density detected by the density detecting means.

It is another object of the present invention to provide an image forming body for carrying a latent image, a developer carrying body for holding a thin layer of a non-magnetic one-component developer, and a regulating amount of the developer on the developer carrying body. In an image forming apparatus having a developer regulating member, a regulating member bias for giving a potential difference between the developer carrying member and the developer regulating member is applied, and an environment detecting means for detecting a use environment is used for the image forming apparatus. This is achieved by an image forming apparatus (second invention) provided inside a forming apparatus, wherein the value of the regulating member bias is changed in accordance with an environmental condition detected by the environment detecting means.

Another object of the present invention is to provide an image forming body for carrying a latent image, a developer carrying body for holding a thin layer of a non-magnetic one-component developer, and regulating the amount of developer on the developer carrying body. In an image forming apparatus having a developer regulating member, a regulating member bias for giving a potential difference between the developer carrying member and the developer regulating member is applied, and counting means for counting the number of times of image formation is provided. The present invention is achieved by an image forming apparatus (third invention) wherein the value of the regulating member bias is changed according to the count number of the counting means.

[0008]

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. Further, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning or technical scope of the terms of the present invention.

An image forming process and each mechanism of an embodiment of the image forming apparatus according to the claims of the present invention will be described.
This will be described with reference to FIG. 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 common to the claims of the present invention.

In FIG. 1, reference numeral 10 denotes a photosensitive drum as an image forming body for each color, 11 a scorotron charger as charging means for each color, 12 an exposure optical system as image writing means for each color, 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.
The next transfer units 14g and 14m are static eliminators as charge elimination means for the transfer belt, 14b is a pressing elastic plate which is a pressing means for the transfer belt, 17 is a fixing device as a fixing means, and 190 is an image forming body cleaning means for each color. A photoconductor cleaning device 190a is an intermediate transfer member cleaning device that is an intermediate transfer member cleaning unit.

In the present embodiment, a photosensitive drum 10 as an image forming body for each color, a scorotron charger 11 as charging means for each color, an exposure optical system 12 as an image writing means 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.

A 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 the corona discharge electrode maintained at a predetermined potential. A charging action (minus charging in the present embodiment) is performed by corona discharge having a negative polarity, and a uniform potential, for example, a uniform potential of −700 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. In accordance with the image data of each color read by the image reading device and stored in the memory, the photosensitive layer of the photosensitive drum 10 is image-exposed to form an electrostatic latent image on the photosensitive drum 10 for each color.

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, and developed on the photosensitive drum 10 respectively. Sometimes, it comes into contact with (contacts with) the peripheral surface of the photoconductor drum 10 and rotates in the forward direction with respect to the rotation direction of the photoconductor drum 10 at the developing position. A) Resistance 10
Urethane of ⁷ Ωcm, formed of solid rubber such as silicon, and provided with a developing roller 131 which is a developer carrying member made of an elastic body, by applying a developing bias voltage of a DC voltage to the developing roller 131, The one-component reversal development of the contact is performed to form a toner image on a latent image portion on the photosensitive drum 10. The developing device 13 includes a developing roller 131.
The blade 133 serving as a developer regulating member for regulating the height and amount of the upper developer layer (toner layer) is
31 is provided. 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 for development is preferably about 5 to 15 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. Preferable toners include polymerization of resins such as styrene resin, vinyl resin, ethyl resin, rosin modified resin, acrylic resin, polyamide resin, epoxy resin, polyester resin, and fatty acid wax 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 composed of particles of 1 to 7 μm. 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.

The intermediate transfer belt 14a, which is an intermediate transfer member, is an endless belt having a volume resistance of 10 ¹² to 10 ¹⁵ Ω · cm, and includes, for example, modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, An outer surface of a semiconductive film substrate having a thickness of 0.1 to 1.0 mm in which a conductive material is dispersed in an engineering plastic such as a nylon alloy is coated with fluorine having a thickness of 5 to 50 μm, preferably as a toner filming preventing layer. Further, it is a seamless belt having a two-layer structure. In addition to the above, the base of the transfer belt 14a has a thickness of 0.1 mm in which a conductive material is dispersed in silicon rubber or urethane rubber.
A semi-conductive rubber belt of 5 to 2.0 mm can also be used. The intermediate transfer belt 14a is stretched in contact with a drive roller 14d and a driven roller 14e, and during image formation, the drive roller 14d is rotated by an intermediate transfer body drive motor (not shown), and the transfer for each color is performed. The photosensitive drum 1 is moved by the pressing elastic plate 14b disposed on the upstream side of the position.
With the intermediate transfer belt 14a pressed to 0, the intermediate transfer belt 14a is rotated in the counterclockwise direction indicated by the arrow in FIG.

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 A DC voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the primary transfer device 14c for each color, and a transfer electric field is formed in the transfer area. The toner image is transferred onto the intermediate transfer belt 14a.

A secondary transfer device 14g, which is a second transfer means for re-transferring the toner image on the intermediate transfer member onto the transfer material, is constituted by a corona discharger, and is provided at an end of the intermediate transfer belt 14a at the intermediate transfer belt 14a. A DC voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the driving roller 14d that is grounded across the recording paper P, and the toner image on the intermediate transfer belt 14a is formed on the recording paper P. Transfer to

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.

Pressing elastic plate 1 as pressing means for the transfer belt
Reference numeral 4b is formed by a rubber blade of urethane or the like, is disposed upstream of the transfer position for each color, and presses the intermediate transfer belt 14a against the photosensitive drum 10 during image formation.

The 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.

A photosensitive member cleaning device 190 as an image forming member cleaning means for each color is provided on a 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 body cleaning device 190a, which is an intermediate transfer body 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 drum 10 starts writing. 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 the developing roller 131 of the Y developing device 13, and a yellow (Y) toner image is formed in accordance with the rotation of the Y photosensitive drum 10.

The Y toner image formed on the Y photoreceptor drum 10 as an 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 is given a potential by the charging action of the M scorotron charger 11 by the magenta (M) image forming unit 100. Image writing is performed by the second color signal, that is, an electrical signal corresponding to 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 a similar process, the image is synchronized with the superposed toner images 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 untransferred toner remaining on the peripheral surface of the photosensitive drum 10 for each color after the transfer is cleaned by a photosensitive member cleaning blade 191 of a photosensitive member cleaning device 190 which is an image forming member cleaning unit for each color. .

In synchronization with the formation of the superimposed color toner image on the transfer belt 14a, recording paper is fed from a paper feed cassette (not shown) as a transfer material storage means via a timing roller (not shown) as a transfer material feeding means. P is conveyed to a transfer area (no sign) of a secondary transfer device 14g, which is a second transfer unit, and a secondary transfer device to which a DC voltage having the opposite polarity (positive polarity in the present embodiment) to the toner is applied. By 14g,
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 transfer residual 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.

In the above, the transfer material is conveyed on an intermediate transfer belt 14a, which is an intermediate transfer member, and the toner images formed by the image forming units 100 for each color are sequentially transferred by the first transfer means for each color. The color toner image may be transferred onto the transfer material, and a superimposed color toner image may be formed on the transfer material and fixed. In this case, transfer by the second transfer unit is unnecessary.

Embodiment 1 A developing device according to any one of claims 1 to 4, a developer regulating member for regulating the amount of developer to a developer carrier provided in the developing device, and a developer which is controlled by a change in image density. The regulating member bias applied to the developer regulating member for stably maintaining the charge amount of the developer on the carrier will be described with reference to FIGS. FIG. 2 is an enlarged cross-sectional configuration diagram of a developing device used in the image forming apparatus of FIG.
FIG. 4 is a diagram showing a development γ curve by the development device, and FIG.
FIG. 4 is a block diagram of control of application of a regulating member bias to a developer regulating member.

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. The developing roller 131 rotates in the direction (counterclockwise in FIG. 2). A supply roller 132, which is a toner supply member, is provided in contact with the developing roller 131. The supply roller 132 supplies toner to the developing roller 131 and collects toner from the developing roller 131. 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. 2). PS1 is a photo sensor as density detecting means for detecting the density of an image formed on the photosensitive drum 10 by a solid black chart.

The developing roller 131, which is a developer carrier,
It has an outer diameter of about 20 mm and a thickness of 5 mm and a hardness of 45 ° (JIS
In A), it is formed by providing a rubber layer (no symbol) of urethane or silicon having a volume resistance of 10 ⁶ Ω · cm. During development,
With respect to the developing roller 131, the same polarity as the toner polarity to be used (minus polarity in this embodiment), and −250
A one-component reversal development is performed by applying a developing bias VB1 of a DC voltage of about V to form a toner image on a latent image portion on the photosensitive drum 10.

Supply roller 132 as a toner supply member
Is a foamed rubber such as urethane or silicon on the outer side (outer peripheral surface) of a conductive core metal (no symbol) such as stainless steel and has a thickness of 4 mm.
mm and a foamed rubber layer (no symbol) having a volume resistance of 10 ⁶ Ω · cm. At the time of development, a supply roller bias VK1 of the same polarity as the toner pole to be used (minus polarity in the present embodiment) and a DC voltage of about -500 V 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). As will be described in detail later, during development, the blade 1
33, a DC biasing member bias VG1 of the same polarity as the toner pole to be used (minus polarity in the present embodiment) is applied. 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. The developing roller 131 is driven by the blade 133.
One or two thin developer layers are formed thereon.

Reference numeral 134 denotes a hopper section containing a developer, which is surrounded by a developing casing 138. Hopper section 134
Inside there is provided a lever-shaped stirring member 134a which rotates counterclockwise in FIG.
The developer in the hopper 134 is agitated and carried out by rotating 4a, and the developer is supplied.

Reference numeral 138 denotes a developing casing. The developing casing 138 is formed along the operation area of the stirring member 134a in the hopper 134, but has a protruding portion 138a protruding outward near the developing roller 131. The blade 133 is attached to and supported by the protrusion 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 density detector having, for example, a light-emitting device PD1 and a light-receiving device PD2 downstream of the developing position of the developing device 13 in the rotation direction of the photosensitive drum 10 as an image forming body and upstream of the transfer position. A photosensor PS1 is provided, and the photosensitive drum 10 is formed by a solid black chart described later.
An image density formed on the upper surface is detected.

FIG. 3 is a graph showing a development γ curve in which the horizontal axis represents the potential difference between the photosensitive drum 10 as an image forming body and the developing roller 131 as a developer carrier, and the vertical axis represents development efficiency. And the photosensitive drum 10 using a solid black chart.
The amount of toner moved from the developing roller 131 onto the photosensitive drum 10 (the amount of developed toner) when the image is formed on the photosensitive drum 10 is determined by the amount of toner supplied to the developing roller 131 during development (supplied by the developing roller 131). (% Of toner) is the development efficiency. Assuming that the rotation ratio between the developing roller 131 and the photosensitive drum 10 is Vs / Vp, the amount of the supplied toner multiplied by the rotation ratio of the developing roller 131 is the supplied toner amount.

As described above, the scorotron charger 11
(See FIG. 1, not shown in FIG. 2.) Corona discharge of the same polarity (minus polarity in the present embodiment) with the toner (toner at the time of development) used by the photosensitive drum 10
Is applied with a uniform potential of, for example, -700 V, and a negative polarity DC voltage, for example, -250 V 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.
33 is a straight line (a) in FIG. 3 when a potential difference is applied between the developing roller 131 and the blade 133 by applying −600 V as the regulating member bias VG 1 to the regulating member 33. FIG. 3 shows a development γ curve when −500 V is applied as the bias VG1 and a potential difference is caused between the developing roller 131 and the blade 133.
A developing γ curve when applying −400 V as a regulating member bias VG1 to the blade 133 and giving a potential difference between the developing roller 131 and the blade 133 is shown by a straight line (c) in FIG. ).

At the time of initial setting, for example, the developing roller 1
The value of the regulating member bias VG1 applied to 31 is -500.
V, and the straight lines (a), (b), (c) in FIG.
Is stored in advance in the ROM of the storage unit in FIG. 4 as a regulating member bias value voltage table of the developing γ curve, and for example, every 5000 prints, an image using a solid black chart is stored. Is formed, and the image density of the toner image on the photosensitive drum 10 at the time of image formation (during operation) is determined by the photo sensor PS as density detection means.
1 to determine whether it is closer to the straight line (b) or closer to the straight line (c) than the straight line (a) of -500 V in accordance with the image density measured (detected) by the photosensor PS1. In accordance with the change in density), the determination is made with reference to the regulating member bias value voltage table (developing γ curve reference table) of the developing γ curve in the ROM, and the value of the regulating member bias VG1 is changed according to a command from the control unit. go. That is, the regulating member bias value voltage table (development gamma curve reference table) of the development gamma curve in the ROM is
It is used as an image density change amount estimating means for estimating the image density change amount, and refers to the developing member γ curve regulating member bias value voltage table (developing γ curve reference table) to change the value of the regulating member bias VG1 according to the image density transition. Change to an appropriate value (switch).

As described above, an appropriate regulating member bias voltage according to the change in image density is applied, the charge amount of the developer is stably maintained, and a high-quality image without a change in gradation (change in image density) is obtained. An image forming apparatus capable of forming a stable image can be provided.

Embodiment 2 A developing device according to claim 2 of the present invention, a developer regulating member for regulating the amount of developer to a developer carrier provided in the developing device, and the number of uses (the number of prints) and the environment Table 1 and FIG. 2 and FIG. 4 show the regulating member bias applied to the developer regulating member for stabilizing the charge amount of the developer on the developer carrying member and maintaining an appropriate image density depending on the conditions. This will be described with reference to FIG. Table 1 shows a regulating member bias value voltage table in terms of relative humidity versus the number of prints.

As described with reference to FIG. 2 of the first embodiment,
The developing device 13 that is a developing unit for each color includes yellow (Y), magenta (M), cyan (C), and black (K).
In the present embodiment, a non-charged non-magnetic one-component developer (toner) of negative charge is stored, respectively, and comes into contact with (contacts) the peripheral surface of the photosensitive drum 10. Developing roller 131 that rotates in the forward direction (clockwise direction in FIG. 2) and the forward direction (counterclockwise direction in FIG. 2)
Is provided. A supply roller 132, which is a toner supply member, is provided in contact with the developing roller 131.
Accordingly, 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. 2).

The developing roller 131, which is a developer carrier,
It has an outer diameter of about 20 mm and a thickness of 5 mm and a hardness of 45 ° (JIS
In A), it is formed by providing a rubber layer (no symbol) of urethane or silicon having a volume resistance of 10 ⁶ Ω · cm. During development,
With respect to the developing roller 131, the same polarity as the toner polarity to be used (minus polarity in this embodiment), and −250
A one-component reversal development is performed by applying a developing bias VB1 of a DC voltage of about V to form a toner image on a latent image portion on the photosensitive drum 10.

Supply roller 132 as a toner supply member
Is a foamed rubber such as urethane or silicon on the outer side (outer peripheral surface) of a conductive core metal (no symbol) such as stainless steel and has a thickness of 4 mm.
mm and a foamed rubber layer (no symbol) having a volume resistance of 10 ⁶ Ω · cm. At the time of development, a supply roller bias VK1 of the same polarity as the toner pole to be used (minus polarity in the present embodiment) and a DC voltage of about -500 V 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). At the time of development, a regulating member bias VG1 of a DC voltage having the same polarity (minus polarity in the present embodiment) as the toner pole to be used is applied to the blade 133. 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. By the blade 133, a thin developer layer of about one or two layers is formed on the developing roller 131.

Reference numeral 134 denotes a hopper section containing a developer, which is surrounded by a developing casing 138. Hopper section 134
Inside there is provided a lever-shaped stirring member 134a which rotates counterclockwise in FIG.
The developer in the hopper 134 is agitated and carried out by rotating 4a, and the developer is supplied.

Reference numeral 138 denotes a developing casing. The developing casing 138 is formed along the operating area of the stirring member 134a in the hopper 134, but has a protruding portion 138a protruding outward near the developing roller 131. The blade 133 is attached to and supported by the protrusion 138a. The developer discharged from the hopper 134 is frictionally charged between the developing roller 131, the blade 133, and the supply roller 132.

As shown in FIG. 4, the image forming apparatus is provided with a counter CT as counting means for counting the frequency of use (the number of uses) of image formation, and the number of uses (the number of prints) is measured by the counter CT. You. In addition, for example, a humidity sensor HS1 is provided as an environmental condition detecting unit for detecting environmental conditions inside the image forming apparatus, and the humidity sensor HS1 measures the internal humidity (relative humidity).

As described above, the scorotron charger 11
(See FIG. 1, not shown in FIG. 2.) Corona discharge of the same polarity (minus polarity in the present embodiment) with the toner (toner at the time of development) used by the photosensitive drum 10
Is applied with a uniform potential of, for example, -700 V, and a negative polarity DC voltage, for example, -250 V is applied to the developing roller 131.
V is applied, and a negative polarity DC voltage, for example, -500 V, is applied to the supply roller 132, and the image density changes depending on the use environment conditions (environmental conditions) and the number of times of use (use frequency). What measured the value of the regulating member bias VG1 applied to the blade 133 according to environmental conditions and the number of times of use (frequency of use) so that the image density was appropriate,
As shown in Table 1 below,

[0058]

[Table 1]

Table 1 shows a regulating member bias value voltage table with relative humidity versus the number of prints at which the image density is appropriate.

The values shown in Table 1 are stored in advance in the ROM of the storage unit of FIG. 4 as a relative member bias value voltage table for the relative humidity versus the number of prints for making the image density appropriate, and the humidity sensor HS1 is stored. According to the environmental conditions and the number of uses (the number of prints) measured (detected) by the counter and the counter CT, the regulating member bias value voltage table (relative humidity versus the number of prints reference table) of the relative humidity versus the number of prints in the ROM is referred to. Then, the value of the regulating member bias VG1 is changed according to a command from the control unit. That is, RO
The regulating member bias value voltage table (relative humidity vs. print number reference table) of the relative humidity in M is used as image density change amount prediction means for predicting the image density change amount. ), The value of the regulating member bias VG1 is changed to an appropriate value (switching is performed) with reference to a regulating member bias value voltage table (relative humidity vs. printing number reference table) of the relative humidity versus the number of prints.

In the above description, the number of times of image formation (use frequency) and environmental conditions (use environment conditions) are referred to the regulating member bias value voltage table (relative humidity vs. print number reference table) of relative humidity versus number of prints. , May be changed individually.

At the same time, in addition to the number of times of image formation (use frequency) and environmental conditions (use environment conditions), Embodiment 1
The developing member gamma curve regulating member bias value voltage table (development gamma curve reference table) in the ROM described above
It is used as an image density change amount estimating means for estimating the image density change amount, and refers to the developing member γ curve regulating member bias value voltage table (developing γ curve reference table) to change the value of the regulating member bias VG1 according to the image density transition. It is preferable to change (switch) to an appropriate value.

As described above, an appropriate regulating member bias voltage according to the environmental conditions is applied, the charge amount of the developer is stably maintained, and high-quality stable without gradation change (image density change). An image forming apparatus in which a formed image is formed can be provided. In addition, an appropriate regulating member bias voltage according to the frequency of use (the number of times of use) is applied, the charge amount of the developer is stably maintained, and high-quality stable without gradation change (image density change). An image forming apparatus in which a formed image is formed can be provided.

[0064]

According to the first or fourth aspect, an appropriate regulating member bias voltage is applied according to a change in image density.
An image forming apparatus in which the charge amount of the developer is stably maintained and a high-quality stable image without a change in gradation (change in image density) can be formed.

According to the second or fourth aspect, an appropriate regulating member bias voltage according to the environmental conditions is applied, the charge amount of the developer is kept stable, and the gradation changes (changes in image density). Thus, an image forming apparatus capable of forming a high-quality stable image free from defects can be realized.

According to the third or fourth aspect, an appropriate regulating member bias voltage is applied according to the frequency of use (the number of times of use), the charge amount of the developer is stably maintained, and the change in gradation (image An image forming apparatus capable of forming a high-quality stable image without a change in density can be realized.

[Brief description of the drawings]

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

FIG. 2 is an enlarged cross-sectional configuration diagram of a developing device used in the image forming apparatus of FIG.

FIG. 3 is a diagram illustrating a development γ curve by a developing device.

FIG. 4 is a control block diagram of a control member bias application to a developer control member.

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13 developing device 14a intermediate transfer belt 131 developing roller 132 supply roller 133 blade 134 hopper section 138 developing casing CT counter HS1 humidity sensor PS1 photo sensor

Continued on the front page F-term (reference) 2H027 DA10 DA14 DA45 DE07 EA04 EA05 EB03 EC03 EC06 EC09 ED09 ED24 EE08 FA28 2H077 AC04 AD06 AD13 AD17 AD23 AD35 AE03 AE10 DA02 DA04 DA18 DA22 DB08 DB14 EA14 EA15 FA13 FA001 GA13 GA17 H9

Claims (4)

[Claims] 1. An image forming body that carries a latent image, a developer carrying body that holds a thin layer of a non-magnetic one-component developer, and a developer regulating member that regulates the amount of developer on the developer carrying body. In the image forming apparatus having the above, while applying a regulating member bias for giving a potential difference between the developer carrying member and the developer regulating member, provided is a density detecting means for detecting the density of the formed image,
An image forming apparatus, wherein the value of the regulating member bias is changed in accordance with the transition of the image density detected by the density detecting means. 2. An image forming body for carrying a latent image, a developer carrying body for holding a thin layer of a non-magnetic one-component developer, and a developer regulating member for regulating an amount of developer on the developer carrying body. In the image forming apparatus having: a regulating member bias for giving a potential difference between the developer carrying member and the developer regulating member, and an environment detecting unit for detecting a use environment is provided inside the image forming apparatus. Wherein the value of the regulating member bias is changed according to an environmental condition detected by the environment detecting means. 3. An image forming body for carrying a latent image, a developer carrying body for holding a thin layer of a non-magnetic one-component developer, and a developer regulating member for regulating an amount of developer on the developer carrying body. An image forming apparatus comprising: a regulating member bias for giving a potential difference between the developer carrying member and the developer regulating member; and a count unit for counting the number of times of image formation is provided. An image forming apparatus that changes the value of the regulating member bias in accordance with the count number by the means. 4. The image processing apparatus according to claim 1, further comprising an image density change amount prediction unit that predicts an image density change amount when the value of the regulating member bias is changed. Image forming device.