JPH05232818A - Developing device - Google Patents

Abstract

PURPOSE:To provide the developing device visualizing a latent image by having toner stuck to it due to difference in potential, where an image of high quality can be obtained with an electrostatic latent image support and a developer layer on a developer carrier not coming into contact with each other, with large degree of freedom in arrangement within the images forming device and in addition, where no image fault is generated due to hysteresis. CONSTITUTION:A toner feeding member 6 magnetically attracting and carrying two component developer including magnetic carrier and the toner is provided. The toner carrier 7, where only the toner is transferred from the toner feeding member 6, is provided in contact with or close to the toner feeding member 6, is proximately with the electrostatic latent image carrier 8, and forming a belt shape supported to be freely rotatably. Furthermore, the toner feeding member 6 is brought into a pressurized contact with the toner carrier 7 so that its surface is made to be recessed shape and is driven so that the two are slid in contact at the pressurized surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing a toner by adhering toner to a latent image formed by a difference in electrostatic potential, and more particularly to a two-component developer in which a magnetic carrier and toner are mixed. The present invention relates to a developing device used.

[0002]

2. Description of the Related Art A variety of developing devices have been disclosed, in which toner is attached to an electrostatic latent image formed by irradiating a photosensitive member with image light so as to make it visible, and these are one-component components using a one-component developer. It is roughly classified into a developing device and a two-component developing device using a two-component developer.

The one-component developing apparatus uses a one-component developer in which a pigment or the like is dispersed in a thermoplastic resin such as styrene resin and is powdered, and a charge control agent is externally added to the developer carrier. A thin layer of the developer is formed on the surface of the developer carrier, and the developer carrier and the electrostatic latent image carrier are arranged so as to be in close contact with each other. An electric field is generated in this proximity portion, and the developer particles fly in the electric field, and are attached to the latent image to be visualized. As described above, in the one-component developing device, since the electrostatic latent image holding member and the developer carrying member are not in contact with each other, it is possible to obtain a high quality image with less disturbance of the developed image and to provide an appropriate developing electric field. As a result, when used in a color image forming apparatus, there is an advantage in that toner images of a plurality of colors can be superposed and developed. However, such a one-component developing device has a low toner charge amount, and a slight change in the toner characteristics causes a change in the thin layer thickness on the developer carrier, or a developer regulating member that forms a thin layer develops. There is a problem that the agent is partially clogged to cause an image defect.

On the other hand, in the two-component developing device, the magnetic carrier and the toner are mixed and sufficiently stirred, so that the toner has a sufficient charge amount and can perform stable development of the density for a long period of time. it can. However, by forming a magnetic brush of developer on the developer carrier and bringing it into contact with the electrostatic latent image carrier, the toner is transferred to the latent image, so that the toner image is not disturbed. In particular, when an attempt is made to form toner images of a plurality of colors in a color image forming apparatus in an overlapping manner, the magnetic brush sweeps and disturbs the already formed toner images.

As described above, the one-component developing device and the two-component developing device have their respective characteristics, and in consideration of these, a developing device having both advantages has been proposed. This is, for example, the "2nd International Conference on Advances in Non-impact Printing" (The
2nd International Congress on Advances in Non-imp
act printing), [American Society of Photographic Engineers (Society
for Photographic Scientists and Engineers)
Washington D. C. , November 8, 1984] by Toshiba, U.S. Pat. No. 3,929,098, and Japanese Patent Laid-Open No. 59-121077. The developing device disclosed in Japanese Patent Laid-Open No. 59-121077 uses a two-component developer and supplies it to the surface of a magnetic roll containing a magnet to form a magnetic brush. The magnetic roll is arranged so as to be close to or in contact with the toner carrier, only the toner of the two-component developer is transferred to the toner carrier, and a thin layer of toner is formed on the surface of the toner carrier. The toner carrier is arranged close to and away from the electrostatic latent image holder, and the toner flies in the electric field generated at the close position and adheres to the latent image to be visualized.

In such a developing device, the toner particles have a sufficient electric charge, which enables stable density development, and the toner carrier and the electrostatic latent image carrier are not in contact with each other to obtain high image quality. be able to.

[0007]

However, the above-mentioned developing device has the following problems. When the developing device as described above is used in the color image forming apparatus, it is necessary to arrange the developing devices so that they can closely face the photoconductor in order to form a plurality of toner images of different colors. I won't. Therefore, a plurality of developing devices are provided so as to be movable, and only the developing device corresponding to the color of the toner image to be developed is sequentially moved to a position close to the photoconductor to develop each color. It has been known. However, in such a color image forming apparatus, it takes time to move the developing device, and the time required to form one color image becomes long. Therefore, it is desirable that a plurality of developing devices are always supported at positions facing the photoconductor, but in the developing device disclosed in Japanese Patent Laid-Open No. 59-121077, a two-component developer is used in addition to the toner carrier. Since it is necessary to provide a magnetic roll that attracts magnetically, there is a problem that the developing device becomes large and it is difficult to dispose all the developing devices around the photoconductor.

Further, in the conventional developing device using the toner carrier and the magnetic roll for transferring the toner to the toner carrier, when the development is carried out a plurality of times successively, the toner on the toner carrier is removed by the previous development. A so-called hysteresis phenomenon occurs in which a density difference is generated in the next development between the consumed portion and the unconsumed portion. In this method, only the toner is transferred from the magnetic brush on the magnetic roll to the toner carrier, and a thin layer of toner is formed, so new toner is supplied without peeling the toner that was not consumed in the previous development. It is due to doing. Therefore, it is possible to eliminate the history by scraping off the toner on the surface of the toner carrier with a scraper or the like after passing through the developing area. However, the toner scraped off by a scraper or the like may cause agglomeration, which makes it difficult to reuse.

The present invention has been made in view of the above problems, and an object thereof is to supply a toner having a sufficient charge amount to a developing area to stably perform high quality development without contact. Provided is a developing device capable of performing the development, which can increase the degree of freedom of arrangement of the developing device even when used in a color image forming apparatus, and can effectively arrange the space in the color image forming apparatus. It is to be. Alternatively, in addition to the above, it is an object of the present invention to provide a developing device that does not cause image defects due to a history phenomenon.

[0010]

In order to solve the above-mentioned problems, the invention according to claim 1 uses a two-component developer containing a magnetic carrier and a toner to form an image on an electrostatic latent image carrier. In a developing device for visualizing the toner by adhering the toner to the formed latent image, the electrostatic latent image holding member is opposed to the electrostatic latent image holding member in close proximity and forms a belt portion rotatably supported by a plurality of supporting members, and the surface is formed. A toner carrier for adhering and transporting the toner to and a cylindrical body rotatably supported in proximity to or in contact with the toner carrier, and magnetically adsorbing the two-component developer on the surface. And a toner supply member capable of forming a thin layer by transferring the toner onto the surface of the toner carrier.

According to a second aspect of the present invention, in the developing device according to the first aspect, the toner is so arranged that the surface of the toner carrier is concave along the peripheral surface of the toner supply member. The supply member is pressed against the toner carrier, and both are driven so that the surface of the toner supply member and the surface of the toner carrier move relatively.

According to a third aspect of the present invention, in the developing device according to the first or second aspect, one of the supporting members of the toner carrier is the belt-shaped toner carrier. The support member is provided at a position facing the electrostatic latent image holder, the support member is fixedly supported, and the belt-shaped toner carrier slides along the surface of the support member.

The toner supply member is capable of adsorbing the two-component developer on the peripheral surface by incorporating a magnet therein, and the magnet does not move even when the cylindrical peripheral surface rotates. It is desirable that the magnet is supported as described above, but the magnet may be rotated. Further, in the developing device according to the second aspect, the rotation direction of the toner supply member is set so that the pressure contact surfaces of the toner supply member and the toner carrier move in opposite directions. desirable. It is desirable that the supporting member, which is fixedly supported at the position where the toner carrier is opposed to the electrostatic latent image carrier, has a smooth curved surface on the sliding surface with the belt-shaped toner carrier.

[0014]

In the developing device according to the first aspect of the present invention, since the toner carrier is belt-shaped, the housing for containing the developer is made a photosensitive member by appropriately selecting the length and the arrangement of the supporting member. Even if the toner carrying member is installed at a distant position, it is possible to develop the toner by holding the toner carrying member in close proximity to the electrostatic latent image holding member. As a result, the restriction on the position where the developing device is arranged is greatly relaxed, and the degree of freedom in designing the image forming apparatus is increased. Further, since it has a toner supply member that magnetically adsorbs the two-component developer and transfers the toner to the surface of the toner carrier, the toner to which sufficient electric charge has been imparted by stirring is applied to the toner carrier. When supplied, the toner can be stably transported to a position where the electrostatic latent image holder and the toner carrier are close to each other. As a result, development with stable density is performed without contact with the electrostatic latent image carrier.

In the developing device according to the second aspect of the invention, the toner supply member is pressed against the surface of the toner carrier, and the surface of the toner carrier is concave along the peripheral surface of the toner supply member. The member and the toner carrier contact each other in a wide range. Further, since the rotation direction and speed are set so that both surfaces move relatively, the surface of the toner carrier is strongly rubbed against the surface of the toner supply member via the magnetic brush of the developer, and The layer of toner remaining on the surface of the carrier is once scraped off and new toner is supplied to form a uniform thin layer of toner. Therefore, the image history on the toner carrier is eliminated.

Further, in the developing device described in claim 3,
Since one of the supporting members of the toner carrier is provided at a position facing the electrostatic latent image carrier and is fixedly supported, the surface of the belt-shaped toner carrier sliding along this surface and the electrostatic latent image carrier are fixed. The fluctuation of the distance from the surface of the image carrier is reduced. As a result, the flying property of the toner to the electrostatic latent image holding member is kept constant, and the density of the developed image is uniform without uneven density.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a developing device which is a first embodiment of the invention described in claim 1 or 2. This developing device uses a two-component developer in which at least a magnetic carrier and toner are mixed, and a housing 1 in which the developer is housed and two mixing augers 2 and 3 in the housing are provided. It has a toner supply member 6 that magnetically attracts and conveys the component developer, and a developer regulating member 5 that regulates the amount of developer adsorbed on the toner supply member. Further, at a portion where the housing 1 is opened to face the photoconductor 8 (electrostatic latent image holder), the photoconductor 8 and the toner supply member 6 are brought close to each other at different positions and supported so as to be orbitable. The belt-shaped toner carrier 7 is formed.

The above two mixing augers 2 and 3 are
The developer is agitated and conveyed in the axial direction, and the developer is agitated and conveyed in the developer agitating and conveying chamber 12 formed in the housing 1 so as to convey the developer in opposite directions. It has become. A partition wall 4 is provided upright between the two mixing augers 2 and 3, and the developer agitating and conveying chamber 1
2 is divided into two parts communicating at both ends, and the developer is conveyed in a circulating manner by the driving of the two mixing augers 2 and 3. As a result, even if the toner is supplied to the end of the mixing auger, the toner is agitated with the magnetic carrier, and the toner concentration and the toner charge amount are kept constant in the width direction of the formed image (direction perpendicular to the paper surface of FIG. 1). To maintain.

The toner supply member 6 is a magnetic roll which is provided at a position facing the developer agitating / conveying chamber 12 and has a magnet whose position is fixed and a cylindrical sleeve which rotates around the magnet. The developer can be magnetically attracted to the surface of the sleeve to be conveyed. The rotating direction of the sleeve is set in the direction of arrow A shown in the figure. The developer regulating member 5 is provided so as to project so that the tip thereof is close to the surface of the toner supply member 6, and comes into contact with the magnetic brush of the developer supplied from the developer agitating / conveying chamber 12 to the toner supply member 6. The amount of developer conveyed to a position near the toner supply member 6 and the toner carrier 7 is regulated.

The toner carrier 7 is made of a thin metal formed on the belt, or a conductive or semiconductive material is applied or adhered to the surface of an insulating plastic belt, and is closed in a ring shape. It is supported by the supporting roller 9 and the driving roller 10 from the inside. The supporting roller 9 is rotatably supported at a position where the toner carrier 7 faces the photoconductor 8, supports the revolving belt-shaped toner carrier 7, and the surface of the toner carrier 7 and the surface of the photoconductor 8 are supported. The distance between and is always kept constant. This distance is usually set to about 100 μm to 500 μm. Further, the drive roller 10 supports the toner carrier 7 so as to be capable of revolving together with the support roller 9, and the rotational drive force is transmitted from a drive device (not shown). The rotation direction is set in the direction of arrow B shown in FIG. 1, and the toner carrier 7 moves in the opposite direction at the position where it is pressed against the peripheral surface of the toner supply member 6.

The supporting roller 9 and the driving roller 10 have a concave shape along the peripheral surface of the toner carrier 7 when the surface of the toner carrier 7 is pressed against the peripheral surface of the toner supplying member 6.
The position is set so that an appropriate tension is introduced into the toner carrier 7. In addition to the above materials, a semiconductive rubber belt, an ultrathin plastic film, or the like can be used as the toner carrier 7. However, when a non-conductive material is used, the supporting roller 9 must be made of a conductive material.

The surface of the photoconductor 8 is uniformly charged and then irradiated with image light to form a latent image due to a difference in electrostatic potential, and the latent image is conveyed to a developing area in the vicinity of the toner carrier 7. Can be done. A DC superimposed AC voltage can be applied to the toner carrier 7 from an AC power supply 13 and a DC power supply 14, so that the toner carrier 7 can be applied.
An alternating electric field is generated in the developing area in which the photoconductor 8 and the photoconductor 8 closely face each other. Further, a DC voltage is applied to the toner supply member 8 from the DC power supply 15 so that a bias voltage is generated between the toner supply member 6 and the toner carrier 7.

In such a developing device, the two-component developer in which the magnetic carrier and the toner are mixed is agitated by the mixing augers 2 and 3 so that the toner is sufficiently charged and is supplied to the toner supply member 6. It On the surface of the toner supply member 6, a magnetic brush of the developer is formed by the magnetic force of the magnet contained in the toner supply member.
When the sleeve on the surface of the toner supply member rotates, the magnetic brush moves, and after the developer regulating member 5 makes the amount of developer uniform, the magnetic brush is conveyed to a position where it is pressed against the toner carrier 7.

Here, the toner carrier 7 is pressed against the surface of the toner supply member 6 through the developer, and both surfaces are set to move in opposite directions. The developer is rubbed against the pressed surface. As a result, the charged toner is transferred to the surface of the toner carrier 7 by the bias voltage to form a thin layer of toner,
The magnetic carrier remains on the surface of the sleeve of the toner supply member 6 due to the attractive force of the magnet in the toner supply member 6.

Further, on the toner carrier 7 placed at the pressure contact position, a portion where the toner is consumed in the previous development and a thin layer of the toner formed in the previous development process where the toner is not consumed remains. Even if there is a portion, since the toner supply member 6 is strongly pressed and rubs against the developer, the thin layer of toner left unused in the previous development process is mechanically disturbed. And mixed with fresh toner to form a new uniform thin layer. At this time, the toner carrier 7
Since the surfaces of the toner supply member 6 and the toner supply member 6 move in opposite directions,
The toner concentration is high on the upstream side in the rotation direction of the toner supply member 6 in both pressure contact areas, and the toner is efficiently supplied to the toner carrier 7 proceeding to the development area, and on the downstream side in the rotation direction of the toner supply member 6. Since the transfer of the toner to the toner carrier 7 progresses, the toner concentration becomes low, which is convenient for scraping off a thin layer of toner that has not been consumed in the previous development.

As described above, when the toner carrier 7 and the toner supply member 6 are in contact with each other over a wide range to form a uniform thin layer of toner having no image history, and this is conveyed to the developing area,
The flying of the toner in the alternating electric field becomes uniform, and the latent image is visualized as an image without density unevenness.

FIG. 2 is a schematic block diagram showing an example of a color image forming apparatus using the developing device of the above embodiment. In this color image forming apparatus, four developing devices 20, 21, 22, and 23 of the above-described embodiment are arranged around a cylindrical photoconductor 30, and magenta, cyan, yellow, and black toners are used, respectively. is there. Further, around the photoconductor 30, the photoconductor 3 is provided on the upstream side of the position where the developing device is arranged.
A charger 24 for uniformly charging the surface of 0, a laser light generator 25 containing a semiconductor laser and a polygonal columnar mirror (polygon rotation mirror) are arranged, and a pre-transfer charger 26 and a transferer are provided on the downstream side. Charger 27, peeling charger 28
And a cleaning device 29 is arranged.

As described above, many devices are densely arranged around the photosensitive member 30 and the range in which the developing device can be arranged is also limited, but the toner carrying members 7a, 7b, 7 are arranged.
Since c and 7d are belt-shaped, it is possible to dispose the housing of the developing device away from the photoconductor 30 in a state where the toner carrier is close to the photoconductor 30, and four developing devices 20 and 21 are provided. , 22 and 23 are arranged at positions spaced apart from the photoconductor 30 at different intervals. As a result, even if a plurality of developing devices capable of stably supplying the toner having a sufficient charge are provided, the developing device does not occupy a large area around the photoconductor 30 and it is necessary to move the developing device during development. Absent. Therefore, it is possible to realize a color image forming apparatus capable of forming a high-quality image at high speed without increasing the size of the entire apparatus.

FIG. 3 is a schematic block diagram showing a developing device according to a second embodiment of the invention described in claim 1 or 2. This developing device is preferably used when the housing 101 is arranged near the photoconductor 8, and a belt-shaped toner carrier 107 is stretched by three supporting members, two of which are rotatably supported. The other supporting rollers 109 and 111 and the other one are driving rollers 110 that are rotationally driven by a driving device (not shown).
The toner carrier 107 includes a supporting roller 111 and a driving roller 1.
It is in pressure contact with the surface of the toner supply member 6 with respect to 10. The structures of the mixing augers 2, 3, the partition wall 4, the developer regulating member 5, the bias power sources 13, 14, 15 and the toner supplying member 6 are the same as those in the first embodiment.

In such a developing device, the housing 101
Can be arranged in a position close to the surface of the photoconductor 8 so that the surface of the toner carrier 107 is pressed against the toner supply member 6 to form a concave shape, and the same effect as that of the first embodiment can be obtained. Obtainable.

FIG. 4 is a schematic configuration diagram showing a developing device which is an embodiment of the invention described in claim 3. In this developing device, a belt-shaped toner carrier 207 is supported by two supporting members so as to face the photoconductor 8 and the toner supply member 6 in close proximity to each other. One of the two supporting members is a fixing member 209 provided at a position facing the photoconductor 8, and the toner carrier 207 slides on the peripheral surface of the fixing member. In addition, the fixing member 209
The sliding surface with respect to the toner carrier 207 is finished in a smooth curve. The other support member is a drive roller 210 provided so as to face the toner supply member 6, and is rotationally driven by a drive device (not shown). As a result, the toner carrier 207 can be rotated in the direction of arrow C shown in FIG. Further, the drive roller 210 is biased by the spring member 17 in a direction away from the fixed member 209, and the biasing force of the spring member 17 introduces tension into the belt-shaped toner carrier 207. ..

A developer pool 16 surrounded by a housing is provided below the portion where the toner carrier 207 and the toner supply member 6 face each other, and the developer is stored in this portion. The mixing augers 2, 3, the partition wall 4, the developer regulating member 5, the toner supply member 6 and the like are the same as those in the first embodiment shown in FIG.

In the developing device as described above, the fixing member 20 that supports the toner carrier 207 at a position facing the photoconductor 8 is provided.
Since the belt-shaped toner carrier 207 slides on this peripheral surface, the distance between the surface of the toner carrier 207 and the photoconductor 8 is always kept constant, and the belt-shaped toner carrier 207 has a rotation member. Variations in the gap due to eccentricity are eliminated. In addition, even if the developer stored in the developer pool 16 comes into contact with the surface of the toner carrier 207 and a thin layer of toner not consumed in the previous developing process remains on the surface of the toner carrier 207, Scraped off, the history phenomenon is resolved.

[0034]

As described above, in the developing device of the present invention, since the toner carrier is belt-shaped, the housing of the developing device is kept stationary while the toner carrier is close to the electrostatic latent image carrier. It can also be arranged at a position distant from the electro-latent image holder, increasing the degree of freedom of arrangement of the developing device. Further, since it has a toner supply member that magnetically adsorbs the two-component developer and forms a thin layer of toner on the surface of the toner carrier,
Development with stable density can be performed without contacting the electrostatic latent image carrier. Therefore, when a plurality of developing devices of the present invention are used in a color image forming apparatus, a high-quality image can be obtained at high speed without increasing the size of the entire apparatus even if the outer dimensions of each are somewhat large. The device can be realized. In addition, the toner supply member is pressed against the surface of the toner carrier to contact in a wide range,
In addition to the above effects, in the developing device in which the surface of the toner carrier is slid relative to the toner carrier, the image history is eliminated without causing toner aggregation, and a uniform thin layer of toner having sufficient electric charge It can be formed on a carrier.
Therefore, it is possible to obtain a developing device capable of performing high-quality development without a history phenomenon. Further, by fixing and supporting a supporting member that supports the belt-shaped toner carrier at a position facing the electrostatic latent image carrier, the gap between the surface of the toner carrier and the photoconductor can be constantly maintained. Therefore, it is possible to perform development without density unevenness.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a developing device according to a first embodiment of the invention described in claim 1 or claim 2.

FIG. 2 is a schematic configuration diagram showing an example of a color image forming apparatus using a plurality of developing devices of the above-described embodiments.

FIG. 3 is a schematic configuration diagram showing a developing device according to a second embodiment of the invention described in claim 1 or claim 2.

FIG. 4 is a schematic configuration diagram showing a developing device which is an embodiment of the invention described in claim 3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Housing 2 Mixing auger 3 Mixing auger 4 Partition wall 5 Developer regulation member 6 Toner supply member 7 Toner carrier 8 Photoconductor (electrostatic latent image carrier) 9 Rotating roller 10 Driving roller 12 Developer stirring transport chamber 13 AC power supply 14 DC power supply 15 DC power supply 24 Charging device 25 Laser light generator 26 Pre-transfer charging device 27 Transfer charging device 28 Stripping charging device 29 Cleaning device 30 Photoreceptor

Front page continuation (72) Inventor Takashi Fuchiwaki 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Business Office (72) Inventor Tomoki Chihara 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd. Ebina Business Office

Claims (3)

[Claims] 1. A developing device for visualizing a latent image formed on an electrostatic latent image carrier by attaching the toner to the latent image by using a two-component developer containing a magnetic carrier and a toner. A toner carrier, which faces the holding member in close proximity and is rotatably supported by a plurality of supporting members, and which conveys the toner by adhering the toner to the surface thereof, and in proximity to or in contact with the toner carrier. And a rotatably supported cylindrical body, the two-component developer is magnetically adsorbed and conveyed on the surface, and the toner is transferred to the surface of the toner carrier to form a thin layer. And a toner supply member that can be used. 2. The developing device according to claim 1, wherein the toner supply member is in pressure contact with the toner carrier so that the surface of the toner carrier is concave along the peripheral surface of the toner supply member. And both are driven so that the surface of the toner supply member and the surface of the toner carrier move relative to each other. 3. The developing device according to claim 1 or 2, wherein one of the support members of the toner carrier is the electrostatic latent image carrier via the belt-shaped toner carrier. A developing device, which is provided at a position facing each other, and in which the support member is fixedly supported, and the belt-shaped toner carrier slides along a surface of the support member.