JP2001175079A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device where an image of high definition can be obtained by forming an extremely uniform toner thin layer on a developing roll without having carrier intrude into a developing range. SOLUTION: In the image forming device 2, two component developer D is utilized by a developing device 30 installed with a toner T feeding member 32 provided with a magnet inside, a restricting member 35 that is abutted on a developing roll 31 and can be rotated and the developing roll 31 carrying only toner T. Intruding of the carrier C to the developing roll is prevented by the restricting member 35 and only the toner T can be fed.

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 used for a copying machine, a printer, a facsimile, and the like, and more particularly, to a developing roller which supplies toner from a toner container in a developing device. The present invention relates to an image forming apparatus that forms a thin toner layer thereon to develop a latent image.

[0002]

2. Description of the Related Art A developer used in an image forming apparatus for developing a visible image by developing an electrostatic latent image formed on a photoreceptor includes a two-component developer composed of a toner and a carrier and a toner alone. And a one-component developer. Since the one-component developer generally contains a magnetic material that is a black magnetite powder in a toner that is a developer, it is difficult to obtain a developer of a clear color other than black. The development method using a one-component developer is advantageous in terms of miniaturization, cost reduction, and reliability of the developing device. However, the carrier has an average particle diameter of 20 to 100 μm, and the overall surface area is very large, so that the toner can be easily triboelectrically charged. A relatively stable and good recorded image is obtained. Further, since the toner of the two-component developer does not contain a magnetic material and can be superposed and developed, a plurality of developing devices are arranged on the peripheral portion of the photoconductor,
This is advantageous in that the electrostatic latent image is developed a plurality of times and a toner image is superimposed on the photoreceptor to form a multicolor image. However, the magnetic material used for the carrier is an iron powder or an oxide of ferrite, both of which are hard materials, and even if the surface of the carrier is coated with a resin, the developer layer containing the carrier contacts the photoreceptor. When the development is performed, the photosensitive member and the developing roller are likely to be damaged by the influence of friction and the like caused by the filled and compressed developer. Therefore,
There has been proposed a developing device and the like in which only a toner is carried on a developing roller while utilizing frictional charging between a carrier of a two-component developer and a toner.

For example, Japanese Patent Application Laid-Open No. 3-100755 discloses an image forming apparatus in which a two-component developer containing a toner and a carrier is selected, supplied to a toner carrier, and developed, and a regulating member for regulating the developer is used. There has been proposed a developing device which is disposed at a position facing a supply member, and further comprises an elastic body in which a regulating member is in contact with a toner carrier. Further, for example, Japanese Patent Application Laid-Open No. 7-84450 discloses an image forming apparatus in which a two-component developer having a toner and a carrier is selected, supplied to a toner carrier, and developed.

[0004]

However, the above-described developing apparatus has the following problems.
In the developing device disclosed in Japanese Patent Application Laid-Open No. HEI 3-100755, the elastic member serving as the toner regulating member is brought into contact with the toner carrier at one place, so that the toner adheres to the toner carrier and the carrier having a reduced particle size can be regulated. However, there is a problem that the toner is conveyed to the developing area by the toner carrier after passing through the toner regulating member. Further, in the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. H7-84450, there is no thin layer regulating member that comes into contact with the donor roll, and there is a possibility that the carrier easily adheres. There is a problem that it is difficult to obtain a stable uniform thin layer because it depends on the mixing state of the particles.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and mixes and stirs toner and a carrier to form a magnetic brush. In the method of developing an electrostatic latent image on an image carrier by using an image carrier, the development characteristics that are faithful to the latent image in the contact one-component development and the uniform toner charging and maintenance of the supply capability of the two-component development system are used. Thus, a stable developing system is always constructed. Therefore, an object of the present invention is to provide a contact one-component developing method in which a developing roller and an image carrier are in contact via a toner layer, and that carriers having a larger particle diameter than the toner are mixed in the development area, which may damage the image carrier. There is provided an image forming apparatus capable of forming a very uniform thin toner layer on a developing roller without causing a carrier to enter a developing area to significantly reduce image quality, thereby obtaining a high-quality image. That is.

[0006]

According to a first aspect of the present invention, there is provided an image bearing member which rotates in a circumferential direction and an electrostatic latent image formed on the image bearing member. A two-component developer including: a developing device for developing; a transfer device for transferring a toner image developed on the image carrier onto a recording member; and a fixing device for fixing the toner image transferred to the recording member. In the image forming apparatus using the developing device, the developing device is an image forming device including a supply member having a magnet therein, a rotatable regulating member abutting on the developing roller, and a developing roller carrying only toner. is there. The image forming apparatus according to claim 1, wherein the regulating member is made of a magnetic material that generates spontaneous magnetization, and the magnitude of magnetization of the regulating member is smaller than the magnitude of magnetization of the supply member. Device. According to a third aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the regulating member is formed of an elastic member. The invention according to claim 4 is the image forming apparatus according to any one of claims 1 to 3, wherein the regulating member is in contact with a cleaning member. According to a fifth aspect of the present invention, the developing roller is in contact with a developing roller cleaning member for applying a voltage on the downstream side of the developing area in the rotating direction and on the upstream side of supplying the toner to the developing roller. The image forming apparatus according to claim 1, wherein:

[0007]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) According to the first aspect of the present invention, a developing device includes a supply member having a magnet therein, a rotatable regulating member abutting on the developing roller, and a developing roller carrying only toner. This is the image forming apparatus provided. FIG.
FIG. 1 is a configuration diagram schematically illustrating an image forming apparatus according to an embodiment of the present invention. In FIG. 1, a rotating image carrier 20 (hereinafter, referred to as a “photoconductor”) and a charging device 21 for charging the photoconductor 20.
An LD driving unit 11 that performs exposure by laser light, a developing device 30 that develops an electrostatic latent image on the photoconductor 20, and a transfer device that transfers a toner image developed on the photoconductor 20 onto the recording member P And the photoconductor 20 by the cleaning blade 41
The image forming apparatus 2 is constituted by a cleaning device 40 for cleaning the upper residual toner and the like. The operation of image formation will be described. Image data from a computer or the like is transferred to the control unit 2 and controls lighting of the laser beam. The laser beam is applied to the photoconductor 20 of the image forming apparatus 2 to form an electrostatic latent image. Organic photoreceptor 2 in the center
There is a photoreceptor 20 coated with 0 (OPC) on its surface, and rotates in the direction of the arrow. A charging device 23 is provided along the moving direction of the photoconductor 20, whereby the surface of the photoconductor 20 is uniformly charged, and an LD latent image is formed on the surface of the photoconductor 20 by writing the LD light by the LD driving unit 11. Is done. The toner T stored in the developing device 30 is developed along the electrostatic latent image. In the developing device 30,
The surface potential of the photoconductor 20 after the image exposure is set to a predetermined potential,
By applying a developing bias to the developing roller 31, development (reversal development) is performed so that the toner T adheres to the image area of the laser beam irradiation section. Next, the recording member P by the transfer device 22
The recording member P is separated from the photoreceptor 20, and the toner image is fixed by the fixing device 50. The image forming cycle is repeated by repeating these steps.

FIG. 2 is a schematic diagram showing a developing device used in an image forming apparatus according to an embodiment of the present invention. Developing device 30
Is a developing roller 31 provided to face the photoconductor 20.
A regulating member for regulating the toner T layer on the developing roller;
A supply member 32 for supplying the toner T to the developing roller 31,
A stirring member 33 for mixing and stirring the toner T and the carrier C is provided. The developing device 30 operates as follows. The toner supply roller 39 rotates the toner T stored in the toner storage container 90 in response to a signal from a control unit (not shown) to move the toner T from the toner storage container 90 to the developing device 3.
Replenish to zero. The supplied toner T is supplied to the developer D in which the toner T and the carrier C in the developing device 30 are mixed. The replenished toner T is mixed into the developer D by the stirring member 33, and is charged by frictional charging with the carrier C. The toner T (black circles in FIG. 2) is attracted by the electrostatic force to the carrier C (white circles in FIG. 2) charged to opposite polarities, and the magnetic force of the supply member 32 and the magnetic force of the carrier C causes the toner T (on the sleeve) of the supply member 32 It is carried.

The developer D carried on the supply member 32 is regulated by the regulating member 35 and a certain amount of the toner T is transferred to the developing roller 31 by an applied bias voltage or the like, and the rest is returned to the developing device. The distance between the closest part between the regulating member 2 and the supply member 324 is set to 1 mm or less. Especially 5
It is preferably not more than 00 μm. Further, the magnetic pole N1 of the magnet facing the regulating member 35 is positioned at an angle θ inclined upstream of the regulating member 35 in the rotation direction of the supply member 32. Is preferably from 5 to 45 degrees. Thereby, the developer D
Circulating flow can be easily formed. Here, the N and S poles of the magnet need to be the same, but the N and S poles may be opposite poles. The supply member 32 has a nonmagnetic rotatable sleeve-like shape, and has a plurality of magnets disposed therein. The magnet is the regulating member 35
N1, S1, N in the rotation direction of the supply member 32 from the location
2. It has four magnetic poles of S2. Since the magnet is fixed, a magnetic force can be applied when the developer D passes through a predetermined place. The surface of the sleeve is roughened by sandblasting so as to fall within a range of 10 to 20 μmRz. The developer D in which the toner T6 and the carrier C5 are mixed is supplied to the supply member 32 by a magnetic field formed by a magnet.
Carried on top.

The regulating member 35 contacts the magnetic brush of the developer D formed on the supply member 32 at the portion of the development roller 31 facing the supply member 32 and also contacts the development roller 31. The rotation method of each of the regulating member 35, the developing roller 31, and the supply member 32 is as shown by the arrow in FIG. The developing roller 31 contacts the photoconductor 20 and contacts the photoconductor 20.
The above latent image is developed. The contact pressure of the regulating member 35 against the developing roller 31 is optimally considerably lower than the normal pressure for regulating the thin layer in a linear pressure range of 1 to 10 gf / mm.

The developing roller 31 is provided with a developer D
The magnetic brush is formed in the area on the S1 side of the magnet, and is opposed to the photoconductor 20 so as to be in contact with the magnetic brush of the developer D on the supply member 32. The toner T on the developing roller 31 has a temperature of -10 to -40 [mu] C.
/ G range is optimal. The toner T transferred onto the developing roller 31 contacts the regulating member 35 to form a uniform thin layer. At this time, the charging of the toner T is made more uniform, and the entry of the carrier C is prevented.

As a method of forming a thin layer by regulating particles, a rigid or elastic material is used as a developing roller 31 carrying particles.
There are two types, one that makes contact with the rotating body and the other that makes the rotating body make contact as in the present invention, but the difference is considered to be in the contact force and the thin layer regulating effect. Regarding the former, a counter contact method having a high regulation capability is assumed, but there are two types, an edge contact and a belly contact. In the former, the regulation efficiency is extremely high, but there is little margin in forming a uniform thin layer, and vertical stripes are easily generated. In the latter case, since the abdominal contact does not contact the tip, the margin for contact is improved, but the contact area cannot be increased unless the contact force is necessarily increased. Further, it is disadvantageous because it tends to stay in a wedge formed by the tip of the elastic body and the developing roller 3. On the other hand, in the method of contacting the rotating body according to the present invention, even if the contact force on the surface changes even with relatively low contact force, a new surface is always brought into contact, so that the regulating effect can be maintained. It is considered that the regulation efficiency is extremely high by returning the particles.

As the developer D, for example, a carrier C whose core material is ferrite particles and whose surface is coated with a silicone resin or the like, and a toner T whose main component is a thermoplastic resin colored with carbon black Is used. The carrier C is made of a magnetic material such as iron powder, ferrite, and magnetite.
Those coated with a silicone-based or fluorine-based resin or those obtained by dispersing magnetite fine powder or the like in a resin binder such as an acrylic resin are usually used. The resistance of the carrier C is controlled to an appropriate value by the resin coating material and the resin binder, and the durability of the carrier C is improved. The particle size is preferably in the range of 20 to 50 μm. The toner T may be an acrylic, polyester, or epoxy resin containing carbon black, magnetite black pigment, or organic pigments such as copper phthalocyanine, quinacridone, and carmine. Further, in order to improve the characteristics of the toner T, a charge control material (CCA), a wax or the like may be contained. Further, there are toners T to which metal oxides such as silica, titanium oxide, and alumina are added in order to impart fluidity and the like. The particle size of the additive is usually in the range of 0.1 to 1.5 μm. The range of the volume average particle diameter of the toner T is preferably 3 to 12 μm, but if it is 7 μm or less, it can sufficiently cope with a high-resolution image of 1200 dpi or more. The material such as the fat coat of the carrier C and the toner T can be appropriately selected depending on the developing conditions such as the polarity of the photoconductor 20 and the linear velocity of the photoconductor 20.

(Example 1) Photoconductor: negative organic photoconductor Diameter: 50 mm Linear velocity: 200 mm / sec. Developing roller: The surface was coated with silicon rubber to a roughness Rz of 4 μm. Diameter: 16 mm Linear velocity: 300 mm / sec. Restriction member: SUS430 was used to magnetize only the part facing the developing roller. Diameter: 10 mm Linear velocity: 50 mm / sec. Contact pressure: 5 gf / mm Supply member: The surface is made to have a roughness Rz of 15 μm with SUS304. The closest gap to the regulating member is set to 500 μm. Diameter: 18 mm Linear velocity: 50 mm / sec. Angle θ: 15 ° Toner Volume average particle diameter: 7 μm Charge amount: −20 μC / g Carrier Volume average particle diameter: 30 μm As a result of long-term image output under the above conditions, carrier C does not enter the developing roller. A high quality image could be obtained only by the toner T on the developing roller 31.

According to the second aspect of the present invention, the regulating member 35 is provided.
The image forming apparatus 2 is made of a magnetic material that generates spontaneous magnetization, and the magnetization of the regulating member 35 is smaller than the magnetization of the supply member 32. Here the regulating member 3
Among them, iron alloy materials such as ferritic, martensitic stainless steel, and bearing steel are preferable. Further, the one in which a plurality of magnetized patterns are formed on the surface of the regulating member 35 is effective. This is because the toner T on the developing roller 31
This is for completely scraping the carrier C mixed into the control member 35 and transporting the carrier C at the magnetized pitch to reach the magnetic field of the magnet in the supply member 32. Since the magnetic force is stronger in the magnet, the carrier C easily returns to the supply member 32. However, the range of the magnetic force exerted by the regulating member 35 needs to be limited so as not to affect the developer layer. The developing roller 31 is moved relative to a vertical line passing through the center of the regulating member 35 to limit the range of the magnetic force of the magnet of the supply member 32.
The arrangement position of the magnet is set to a position facing the developing roller 31 so as to be located only on the side.

Further, the developing roller 31 is preferably made of a rubber material, and the hardness is preferably in the range of JIS-A hardness of 10 to 70 HS measured by JIS standard (JIS K6301). Further, the diameter of the developing roller 31 is 10 to 30 mm.
Then, the surface is appropriately roughened to have a roughness Rz (ten-point average roughness) of 1 to
4 μm. This value is 13 to 80% of the volume average particle diameter of the toner T6, and the toner T is conveyed without being buried in the surface of the developing roller 31. Here, silicon, butadiene, NBR, hydrin, EPDM, and the like can be used as rubber materials. Further, it is preferable to coat the surface of the developing roller 31 with a coating material in order to stabilize the aging quality. The function of the developing roller 31 is only to carry the toner T, and there is no need to apply a charge to the toner T by frictional charging between the toner T and the developing roller 31 as in the related art. No. 31 suffices to satisfy the surface properties, hardness and dimensional accuracy, so that the selection range of the material is significantly increased.
As a material, a silicon type or a Teflon type is particularly preferable. This is because the former has good charging of the toner T, and the latter has excellent releasability. In addition, a conductive material such as carbon black may be appropriately contained in order to obtain conductivity. The thickness of the coating layer is preferably in the range of 5 to 50 μm, and if it is outside the range, defects such as cracks are likely to occur.

Further, according to a third aspect of the present invention, in the image forming apparatus 2 wherein the regulating member 35 is constituted by an elastic member.
It is. The material properties may be the same as the material composition of the developing roller 3 described above.
A uniform contact, and a more uniform thin layer can be formed.

(Second Embodiment) The invention according to claim 4 is the image forming apparatus 2 in which the regulating member 35 is in contact with a cleaning member 36. FIG. 2 is a configuration diagram schematically showing a developing device used in the image forming apparatus 2 according to an embodiment of the present invention. Control member 35
Cleaning member (hereinafter, "scraper for regulating member")
It is written. ) 36 are arranged and brought into contact with each other. Although the carrier C easily returns to the supply member 32, the toner T easily adheres to the regulating member 35 when used for a long period. This is intended to be removed by abutment of the regulating member scraper 36. As the material, polyurethane, silicone rubber, fluorine rubber or the like having a hardness in the range of JIS-A 50 to 70 HS is preferable.

Example 2 An image output experiment was performed under the same conditions as in Example 1 except that a regulating member scraper 36 described below was provided on the regulating member. Scraper for regulating member: Made of polyurethane rubber Hardness: JIS-A 60HS As a result of long-term image output under the above conditions, toner T does not adhere to the surface of regulating member 35 and carrier C does not enter the developing roller. The developer D could be regulated.

(Third Embodiment) According to a fifth aspect of the present invention, a voltage is applied to the developing roller downstream of the developing region with respect to the rotating direction and upstream of supplying the toner T to the developing roller. FIG. 4 in which the cleaning member to be contacted is
FIG. 9 is a configuration diagram schematically illustrating a developing device used in the image forming apparatus 2 according to an embodiment of the present invention. The developing roller cleaning member 37 is disposed on the developing roller 3 and is brought into contact therewith. Although the undeveloped toner T on the developing roller 31 is used again, it is extremely unlikely that an abnormal image such as an afterimage is generated by surely cleaning the toner T. The developing roller cleaning member 37 can scrape the undeveloped residual toner T very efficiently by applying a voltage so that the roller shape is good and the polarity is opposite to that of the toner T so as to attract the toner T6. The developing roller cleaning member 37 is made of metal such as SUS304, etc.
For example, the rubber material described in the above section can also be used.
The hardness may be in the range of JIS-A 10-199HS. The contact pressure is preferably about 3 to 10 g / mm as a linear pressure. In this embodiment, the diameter of the toner is 10 mn, and the scraped residual toner T is scraped off by a scraper 38 (hereinafter, referred to as a “scraper for a cleaning member”) 38 in contact with a cleaning member 37 for a developing roller. The surface of the developing roller cleaning member 37 can always be kept in a state where the toner T6 does not adhere.

(Embodiment 3) Embodiment 1 is the same as Embodiment 1 except that the following developing roller cleaning member 37 is provided on the developing roller.
An experiment for image output was performed under the same conditions as described above. Cleaning member for developing roller: Core material: SUS304 Surface member: Polyurethane rubber JIS-A 100H
S Abutment pressure: 5 g / mm Voltage: +200 V Cleaning member scraper: made of polyurethane rubber As a result of long-term image output under the above conditions, all undeveloped toner T on developing roller 31 can be scraped off, and new A high-quality image could be stably obtained with the proper toner T.

[0022]

As described above, in the image forming apparatus according to the first aspect, since the contact surface of the regulating member moves, the regulating effect of the toner carrier can be enhanced. Claim 2
In the image forming apparatus described in (1), since the carrier has a strong magnetic property and the carrier returns to the supply member, it is possible to prevent the carrier from adhering to the developing roller. In the image forming apparatus according to the third aspect, since the contact pressure on the surface of the regulating member can be made uniform, a uniform thin layer can be formed. In the image forming apparatus according to the fourth aspect, since the regulating member surface is always new, a uniform thin layer can be maintained. In the image forming apparatus according to the fifth aspect, since the undeveloped toner is scraped off, new toner is always supplied to obtain a high-quality image.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an image forming apparatus 2 according to an embodiment of the invention described in claims 1 to 5;

FIG. 2 is a configuration diagram schematically showing a developing device used in the image forming apparatus 2 according to an embodiment of the present invention described in claims 1, 2 and 3;

FIG. 3 is a configuration diagram schematically showing a developing device used in an image forming apparatus according to an embodiment of the present invention;

FIG. 4 is a configuration diagram schematically showing a developing device used in the image forming apparatus 2 according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 writing device 2 image forming device 3 external device such as computer 4 image reading device 10 interface unit 11 LD driving unit 12 polygon mirror 13 lens 14 mirror 15 image identification unit 20 photoconductor 21 charging device 22 transfer / separation device 24 transport roller Reference Signs List 25 paper feed roller 26 paper feed cassette 30 developing device 31 developing roller 32 toner supply member 33 stirring member 34 spring 35 regulating member 36 regulating member scraper 37 developing roller cleaning member 38 cleaning member scraper 39 toner replenishing roller 40 cleaning device 41 Cleaning blade 50 Fixing device D Developer C Carrier T Toner N Regulatory member internal magnet N pole N1, N2 Supply member internal magnet N pole S1, S2 Supply member internal magnet S pole P Recording member V Power supply

Continued on the front page F term (reference) 2H031 AC03 AC19 AC24 AC33 AE01 AE02 BA04 BB01 2H077 AC04 AC12 AD02 AD06 AD13 AD17 AD31 AD32 AE02 EA03 FA01 FA22

Claims (5)

[Claims] An image carrier that rotates in a circumferential direction; a developing device that develops an electrostatic latent image formed on the image carrier; and a toner image that is developed on the image carrier is transferred onto a recording member. An image forming apparatus using a two-component developer, the developing device comprising: a supply member having a magnet therein; and a developing roller. An image forming apparatus, comprising: a rotatable regulating member that abuts on a developing roller; and a developing roller that carries only toner. 2. The image according to claim 1, wherein the regulating member is made of a magnetic material that generates spontaneous magnetization, and the magnitude of the magnetization of the regulating member is smaller than the magnitude of the magnetization of the supply member. Forming equipment. 3. The image forming apparatus according to claim 1, wherein the regulating member is formed of an elastic member. 4. The image forming apparatus according to claim 1, wherein said regulating member is in contact with a cleaning member. 5. The image forming apparatus according to claim 1, wherein the developing roller is in contact with a developing roller cleaning member for applying a voltage on the downstream side of the developing region with respect to the rotation direction and on the upstream side of supplying the toner to the developing roller. The image forming apparatus according to claim 1, wherein: