JP2002196578A - Developing device and image forming apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device using a toner supply member on the surface of which a magnetic brush consisting of two-component developer is formed so that only toner is supplied to a toner carrier from the magnetic brush on the toner supply member and carried on the toner carrier, and restraining the scattering of the toner suspended from the magnetic brush to the outside of the developing device without disturbing a toner layer on the toner carrier. SOLUTION: This developing device 3 is equipped with a developing roller 6 carrying the toner on its surface and carrying it to a developing area opposed to a photoreceptor, and a supply roller 7 carrying the two-component developer including the toner and magnetic particles on its surface, carrying it to a toner supply area opposed to the roller 6 and supplying the toner in the two- component developer to the roller 6. In the device 3, a gap A between the roller 6 and a casing 4 on a downstream side in a toner carrying direction by the roller 6 from the toner supply area is made smaller than a gap B between the roller 7 and the casing 4 on a downstream side in a developer carrying direction by the roller 7 from the toner supply area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., and a developing device used in the apparatus, and more particularly, to visualizing a latent image formed on the surface of an image carrier. The present invention relates to a developing device and an image forming apparatus using the developing device.

[0002]

2. Description of the Related Art Conventionally, as a method for developing a latent image on a latent image carrier, a two-component developing method using a two-component developer containing toner and magnetic particles (hereinafter, referred to as "carrier") has been proposed.
A one-component developing system using a one-component developer containing only toner is known. Among these developing methods, the latter one-component developing method is a method in which a toner carried on the surface of the toner carrier in a uniformly thinned state is opposed to a latent image on the surface of the latent image carrier in a contact or non-contact state, and the latent image is To form a visible image by adhering toner to the surface. On the other hand, in the two-component developing method, a magnetic brush is formed by carrying a two-component developer composed of a toner and a carrier in a brush shape on the surface of a developer carrier having a built-in magnet,
This is to form a visible image by adhering only the toner in the magnetic brush to the latent image on the surface of the latent image carrier.

[0003] Among these developing methods, the one-component developing method does not use a carrier, so that image defects such as development unevenness caused by a magnetic brush of a two-component developer hitting the latent image carrier occur. Therefore, development faithful to the electrostatic latent image can be performed. Therefore, a high-quality image can be obtained, which is advantageous for higher resolution. However, in the one-component developing method, a toner supply roller is slidably contacted with an elastic toner carrier, or a thinning blade is applied to the toner on the toner carrier surface in order to thin the toner on the toner carrier. Are relatively moved in a contact state. For this reason, the toner carrier is easily worn, and the toner on the toner carrier is easily stressed to cause toner filming, which is not good in terms of the durability of the apparatus. Further, since only the toner is continuously agitated in the developing device, the toner is apt to be deteriorated, and it is difficult to obtain the temporal stability of image quality.

In view of the above, a developing method combining the advantages of the two-component developing method and the one-component developing method is adopted. A toner supplying member having a magnetic brush made of a two-component developer formed on the surface thereof is used. A developing device has been proposed in which only the toner is supplied to and carried on the toner carrier by the above magnetic brush (for example, Japanese Patent Laid-Open No. 5-204).
237).

In this developing device, a two-component developer is stirred in the developing device, and a toner supply member (for example, a magnetic roller,
A magnetic brush is formed by carrying a two-component developer on a magnetic brush forming body or the like. The toner in the magnetic brush is charged to a predetermined polarity by friction with the carrier. Then, only the toner charged to a predetermined polarity from the magnetic brush on the toner supply member is moved and carried on a toner carrier (for example, a developing roller, a toner layer holder, etc.). As a result, stress on the toner carrier and the toner is reduced as compared with the one-component developing system, and the same durability as the two-component developing system can be obtained. Further, since the development is performed by the one-component development system, high image quality equivalent to that of the one-component development system can be obtained.

[0006]

However, in a developing device in which the two-component developing system and the one-component developing system are combined, there is a problem that toner scatters from a magnetic brush on a toner supply member. The toner mixed with the carrier and having an electric charge of a predetermined amount or more is attracted to the carrier on the magnetic brush, but the toner having an insufficient charge such as the toner immediately after replenishment is released from the magnetic brush. Then, the toner floating around the magnetic brush rotating at a high speed is scattered outside the developing device by the airflow around the toner carrier. Further, in the developing device of this system, a hysteresis phenomenon after development may occur in the thin toner layer on the toner carrier, and in order to eliminate the phenomenon, the toner concentration in the developer is increased and used. Even when the toner concentration is high, toner floating from the magnetic brush easily occurs. The toner scattered outside the developing device stains the inside of the image forming apparatus, causing problems such as image stains and stains on the operator's hands.

In order to prevent the toner floating from the magnetic brush from scattering out of the developing device, as a conventional technique, the periphery of the magnetic brush on the toner supply member is covered with a casing, and the free end of the casing contacts the toner carrier. There is a known one in which a flexible sheet member that is in contact is fixed to shield between a toner carrier and a casing.

However, if the flexible sheet member is disposed so as to be in contact with the toner carrier downstream of the toner supply area in the toner conveying direction by the toner carrier, the flexible sheet member is placed on the toner carrier. Disturbs the thin layer of the toner used for the development of the image, causing unevenness of the thin layer, streaks, and the like, thereby deteriorating the image quality.

The present invention has been made in view of the above background, and an object of the present invention is to use a magnetic brush made of a two-component developer on a surface of a toner supply member, and a magnetic brush on the toner supply member. In a developing device that supplies and carries only toner to a toner carrier, the developing device can reduce scattering of toner floating from the magnetic brush to the outside of the developing device without disturbing the toner layer on the toner carrier. And an image forming apparatus using the developing device.

[0010]

In order to achieve the above object, the present invention is directed to a toner carrier which carries a toner on a surface thereof and transports the toner to a developing area opposed to an image carrier, a toner and magnetic particles. A toner supply member that carries a two-component developer containing on the surface thereof, conveys the toner in the two-component developer to the toner carrier, and conveys the toner in the two-component developer to the toner carrier. A developing device having an opening in the development region of the body and a casing covering the toner carrier and the toner supply member, wherein the toner is located downstream of the toner supply region in a toner conveying direction by the toner carrier. The gap between the carrier and the casing is larger than the gap between the toner supply member and the casing on the downstream side of the toner supply area in the developer transport direction by the toner supply member. It is characterized in that it has configured to be smaller.

In the developing device according to the first aspect, an airflow is generated around the toner carrier downstream of the toner supply area in the toner transport direction by the toner carrier in the same direction as the toner transport direction. . Further, an airflow is generated around the toner supply member downstream of the toner supply region in the developer transport direction by the toner supply member, toward the inside of the developing device in the same direction as the developer transport direction. Here, when the gap between the toner carrier and the casing is smaller than the gap between the toner supply member and the casing, the airflow flowing toward the outside of the developing device in the gap between the toner carrier and the casing is smaller than that of the toner. The airflow flowing toward the inside of the developing device in the gap between the supply member and the casing increases. For this reason, the toner floating around the magnetic brush is more likely to ride on the airflow flowing toward the inside of the developing device than the airflow flowing outside the developing device. Therefore, the toner floating around the magnetic brush is more easily drawn into the developing device than scattered outside the developing device. As described above, in the present invention, the relationship between the gap between the toner carrier and the casing and the gap between the toner supply member and the casing is defined, so that the airflow toward the inside of the developing device becomes larger than the airflow toward the outside of the developing device. By doing so, it is possible to reduce toner scattering to the outside of the developing device without providing a member that disturbs the thin toner layer used for development on the toner carrier.

According to a second aspect of the present invention, in the developing device of the first aspect, a gap between the toner carrier and the casing at a downstream side of the toner supply area in a toner conveying direction by the toner carrier is 0.1 mm or more. The thickness is set to 1 mm or less.

In the developing device according to the present invention, the gap between the toner carrier and the casing is set to 0.1 mm or more and 1 mm or less. Here, the smaller the distance between the toner carrier and the casing, the less the toner scatters outside the developing device.
If the gap is less than 0.1 mm, the toner carrier may come into contact with the casing to disturb the thin toner layer on the toner carrier or damage the toner carrier. On the other hand, if the gap is large, the airflow around the toner carrier to the outside of the developing device also increases. When the gap is 1 mm or more, the toner floating around the magnetic brush is drawn into the developing device more than scattered outside the developing device. It was confirmed by an experiment that the amount of the toner scattered on the surface was still large. Therefore, by setting the gap to be 0.1 mm or more and 1 mm or less, the floating toner from the magnetic brush can be removed from the gap between the toner carrier and the casing without causing disturbance of the toner layer and damaging the toner carrier. Scattering to the outside can be efficiently reduced.

According to a third aspect of the present invention, in the developing device according to the first or second aspect, a gap between the toner supply member and the casing in a region downstream of the toner supply region in a developer conveying direction by the toner supply member is provided. 0.5mm
As described above, the thickness is set to 2.5 mm or less.

According to a third aspect of the present invention, the gap between the toner supply member and the casing is 0.5 mm or more and 2.5 m or more.
m or less. If the gap is larger than 2.5 mm, the air flow from the toner supply member is weak at a position distant from the surface of the toner supply member, and the floating toner cannot be efficiently drawn into the developing device. Therefore, when the gap between the toner supply member and the casing is set to a size such that the tip of the magnetic brush carried by the toner supply member is conveyed while contacting the casing in the gap, the toner supply member in the gap is provided. Even at a position distant from the surface, the magnetic brush conveyed by the toner supply member reliably generates an airflow toward the inside of the developing device, and the floating toner can be efficiently drawn into the developing device. On the other hand, if the gap between the toner supply member and the casing is too small, the airflow drawn into the developing device is weakened, and the magnetic brush conveyed by the toner supply member overflows from the gap, causing the toner on the upstream side in the conveyance direction to overflow. The developer stays in the supply area and the developer is not properly circulated into the developing device.
Therefore, the gap between the toner supply member and the casing is
It is desired that the magnetic brush be sized so that the vicinity of the tip of the magnetic brush is conveyed while being in contact with the casing. This size varies depending on the particle size of the carrier used for development and the magnetic force of the toner supply member.
When the thickness is 2.5 mm or less, the floating toner from the magnetic brush can be efficiently sucked into the developing device.

The invention according to claim 4 is the invention according to claim 1, 2, or 3.
In the above developing device, the direction in which the toner is transported by the toner carrier in the toner supply region and the direction in which the developer is transported by the toner supply member are the same.

According to the fourth aspect of the present invention, in the toner supply area, the toner transport direction by the toner carrier and the developer transport direction by the toner supply member are the same, so that the toner transport area around the toner carrier is The airflow and the airflow around the toner supply member are stabilized, and the floating toner can be efficiently conveyed. On the other hand, when the directions are opposite to each other, the airflows interfere with each other and are difficult to stabilize as compared with the case in which the directions are the same.

According to a fifth aspect of the present invention, there is provided an image forming apparatus having an image carrier, a latent image forming means for forming a latent image on the image carrier, and a developing means for developing the latent image on the image carrier. In the forming apparatus, a developing device according to any one of claims 1 to 4 is provided as the developing unit.

In the image forming apparatus according to the fifth aspect, the toner released from the magnetic brush of the toner supply member is drawn into the developing device such that the air flow toward the inside of the developing device is larger than the air flow toward the outside of the developing device. Therefore, scattering of toner outside the developing device can be reduced. Therefore, it is possible to prevent the inside of the image forming apparatus from being stained, and to prevent problems such as image stains and operator's hand stains. In addition, since there is no member that comes into sliding contact with the toner carrier on the downstream side of the toner supply region in the toner transport direction by the toner carrier, the toner layer on the toner carrier is not disturbed. Thereby, high quality image quality can be maintained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment in which the present invention is applied to an electrophotographic full-color printer (hereinafter, referred to as "printer") as an image forming apparatus will be described. First, a schematic configuration of the printer according to the present embodiment will be described with reference to FIG. This printer irradiates a photosensitive belt 1 around a photosensitive belt 1 as a latent image carrier with a charging device 2 for uniformly charging the surface of the photosensitive belt 1 and a laser beam modulated based on image information. An exposure device (not shown), a cyan developing device 3C for forming a toner image by attaching a charged toner on a developing roller 6 as a toner carrier to an electrostatic latent image formed on the photosensitive belt 1, and a magenta developing device 3M, yellow developing device 3
Y, a black developing device 3Bk, an intermediate transfer device 20 for transferring the toner image on the photosensitive belt 1 onto an intermediate belt 22 as an intermediate transfer member, and removing the toner remaining on the photosensitive belt 1 after the transfer. The cleaning devices 23 and the like are arranged in order. Here, a latent image forming means for forming an electrostatic latent image on the photoreceptor belt 1 is constituted by the charging device 2 and an exposure device (not shown). Further, the printer feeds the transfer paper 21 from a paper feed tray (not shown) or the like.
A feeder (not shown) for feeding, and an intermediate transfer belt 2
Transfer device 24 that transfers the toner image on transfer paper 2 onto transfer paper 21
And a fixing device 25 for fixing the toner image transferred by the transfer device 24 to the transfer paper 21.

In the printer having the above-described structure, when the image forming cycle is started, first, the photosensitive belt 1 is rotated in the direction of arrow a and the intermediate transfer belt 22 is rotated in the direction of arrow b by a drive motor (not shown). With the rotation of the photosensitive belt 1 and the intermediate transfer belt 22, the formation of the toner image on the photosensitive belt 1 and the transfer of the toner image onto the intermediate transfer belt 22 are repeatedly performed in the order of cyan, magenta, yellow, and black. , Cyan, magenta, yellow, and black toner images on the intermediate transfer belt 22
A full-color image is formed. After the photoreceptor belt 1 is uniformly charged by the charging device 2, first, a laser beam modulated based on cyan image data is scanned and irradiated in the axial direction of the photoreceptor belt by an exposure device (not shown). Thus, a cyan electrostatic latent image is formed on the photoreceptor belt 1. The electrostatic latent image formed on the photoreceptor belt 1 is developed by attaching charged toner by the cyan developing device 3C to become a cyan toner image. The cyan toner image formed on the photosensitive belt 1 is transferred to the intermediate transfer device 2
0 is transferred onto the intermediate transfer belt 22. After the cyan toner image is transferred onto the transfer belt 22, the toner remaining on the photosensitive belt 1 is removed by the cleaning device 23. The surface of the photoreceptor belt 1 that has passed through the cleaning device 23 is uniformly charged by the charging device, and the magenta, yellow, and black image forming processes are sequentially repeated.
As a result, an overlapping toner image of each color is formed on the intermediate transfer belt 22 of the intermediate transfer device 20. On the other hand, the transfer paper 21 is fed and conveyed by a paper feeder (not shown), and is sent and conveyed to a region where the intermediate transfer belt 22 and the transfer device 24 face each other at a predetermined timing. And the transfer device 24
Thus, the full-color toner image on the intermediate transfer belt 22 is transferred onto the transfer paper 21. Next, the transfer paper 21 is separated from the intermediate transfer belt 1 and sent to the fixing device 25.
The transfer paper 21 on which the full-color toner image is fixed by the fixing device 25 is output.

Next, the configuration and operation of the developing device will be described in detail. Here, the four developing devices 3C, 3C
Since the configurations and operations of M, 3Y, and 3Bk are exactly the same, the developing device 3 shown in FIG. 2 will be described below as a representative example. In FIG. 2, a casing 4 of the developing device 3 has an opening such that a developing roller 6 as a toner carrier faces the photosensitive belt 1. Inside the casing 4, from the photoreceptor belt 1 side, a developing roller 6, a supply roller 7 as a toner supply member, a pair of stirring / transport members 10
Are arranged. A two-component developer (hereinafter, referred to as “developer”) 5 containing a toner and a carrier is accommodated in the casing 4. A part of the developer 5 is carried on the supply roller 7 while the toner and the carrier are mixed by the pair of agitating / conveying members 10 and the charge amount of the toner is raised by frictional charging. The supply roller 7 has a fixed magnet inside, and a cylindrical sleeve rotates around the fixed magnet. This sleeve is formed of a nonmagnetic metal such as aluminum. The developer 5 is attracted to the sleeve by the magnetic force, and the sleeve 5 shown in FIG.
It is conveyed with rotation in the direction of the middle arrow d. The layer thickness of the developer 5 carried around the supply roller 7 is regulated by a regulating blade 8 as a layer thickness regulating member. After passing through the regulating blade 8, the developer 5 is conveyed as a magnetic brush 9 having a predetermined thickness. . Although the supply roller 7 itself and the developing roller 6 are not in contact with each other and a predetermined gap is set, the magnetic brush 9 is in contact with the developing roller 6. A bias voltage is applied between the supply roller 7 and the developing roller 6 so as to generate a predetermined potential difference.
The toner in the magnetic brush 9 moves onto the developing roller 6 rotating in the direction of arrow c in FIG. 2, and a thin toner layer is formed on the developing roller 6. The developing roller 6 rotates in the direction of arrow c in FIG. 2 to convey the toner layer to a developing area which is an area facing the photosensitive drum 1, and forms a toner image on the electrostatic latent image formed on the photosensitive drum 1. To form a toner image. Visualize. In the developing device 3, as shown in FIG.
In the toner supply area where the developing roller 6 and the supply roller 7 face each other, the direction in which the toner is transported by the developing roller 6 and the direction in which the developer is transported by the supply roller 7 are the same.

Here, in the developing device 3, toner having an insufficient charge amount, such as toner immediately after replenishment, is released from the magnetic brush 9. Therefore, in the developing device 3, the casing 4 is formed so as to cover the supply roller 7 and the developing roller 6 other than the vicinity of the developing area facing the photoreceptor belt 1 in order to prevent the toner released from the magnetic brush 9 from scattering. Have been. However, the released toner is scattered out of the developing device 3 from the gap between the developing roller 6 and the casing 4 by the airflow accompanying the rotation of the developing roller 6 in the direction of arrow c in FIG.

Therefore, in the developing device 3 according to the present embodiment, the gap (A in FIG. 3) between the developing roller 6 and the casing 4 on the downstream side of the toner supply area in the toner conveying direction of the developing roller 6 is increased. The gap (B in FIG. 3) between the supply roller 7 and the casing 4 on the downstream side of the supply roller 7 in the developer conveyance direction from the region is set to be smaller. Accordingly, the airflow flowing toward the outside of the developing device 3 in the gap (A in FIG. 3) between the developing roller 6 and the casing 4 on the downstream side of the developing roller 6 in the toner conveying direction from the toner supply area is higher than that of the toner supply area. In the gap (B in FIG. 3) between the supply roller 7 and the casing 4 on the downstream side of the supply roller 7 in the developer transport direction, the airflow flowing toward the inside of the developing device 3 increases. Therefore, the floating toner is more likely to ride on the airflow flowing toward the inside of the developing device 3 than the airflow flowing toward the outside of the developing device 3. For this reason, the floating toner becomes easier to be drawn into the developing device 3 than to scatter outside the developing device 3, and the scattering of the toner outside the developing device 3 can be further suppressed.

Here, the smaller the gap (A in FIG. 3) between the developing roller 6 and the casing, the more the scattering of toner out of the developing device 3 can be reduced. However, the gap between the developing roller 6 and the casing 4 (A in FIG. 3) is 0.1
If the diameter is smaller than mm, the developing roller 6 may come into contact with the casing 4 due to the run-out of the developing roller 6 or the like, and the thin toner layer on the developing roller 6 may be disturbed or the developing roller 6 may be damaged. On the other hand, if the gap (A in FIG. 3) between the developing roller 6 and the casing 4 is larger than 1 mm, the airflow toward the outside of the developing device 3 increases, and the developing device 3 passes through the gap (A in FIG. 3). It was confirmed by an experiment that the amount of the toner scattered outside was still large. From the above, the gap (A in FIG. 3) between the developing roller 6 and the casing 4 is set to 0.1 mm or more and 1 m
By setting m or less, the scattering of the floating toner from the magnetic brush 9 to the outside of the developing device 3 can be efficiently suppressed without causing the disturbance of the toner layer and the damage of the developing roller 6.

If the gap (B in FIG. 3) between the supply roller 7 and the casing 4 is too large, the air flow is weakened at a position distant from the surface of the supply roller 7, and the floating toner is efficiently removed from the developing device. 3 can not be pulled into. Therefore, the gap between the supply roller 7 and the casing 4 (FIG. 3)
The middle B) is sized so that the tip of the magnetic brush 9 carried by the supply roller 7 is conveyed while contacting the casing in the gap (B in FIG. 3).
Even at a position away from the surface of the supply roller 7 in the middle B),
An airflow toward the inside of the developing device 3 by the conveyed magnetic brush 9 is reliably generated. On the other hand, if the gap (B in FIG. 3) between the supply roller 7 and the casing 4 is small, the airflow drawn into the developing device 3 is weakened, and the magnetic brush 9 to be conveyed is removed by the gap (B in FIG. 3). ), The developer overflows and stays in the toner supply area on the upstream side, and the developer is not properly circulated into the developing device 3. For these reasons, it is desired that the gap (B in FIG. 3) between the supply roller 7 and the casing 4 be sized so that the vicinity of the tip of the magnetic brush 9 is conveyed while contacting the casing 4. . This size is
Although it depends on the particle size of the carrier particles used for development and the magnetic force of the supply roller 7, it is specifically 0.5 mm or more and 2 m
By setting the range to m, the floating toner from the magnetic brush 9 can be efficiently sucked into the developing device. As described above, the gap between the developing roller 6 and the casing (FIG. 3)
By setting the middle A) and the gap between the supply roller 7 and the casing 4 (B in FIG. 3), scattering of the floating toner outside the developing device 3 can be efficiently suppressed.

Further, the gap (C in FIG. 3) between the developing roller 6 and the casing 4 on the upstream side of the developing roller 6 in the toner conveying direction from the toner supply area is reduced. On the upstream side of the toner supply region in the toner transport direction of the developing roller 6, an airflow is generated around the developing roller 6 toward the toner supply region in the developing device 3. Therefore, on the upstream side in the toner transport direction, the floating toner is transported to the toner supply area along with the airflow. However,
The gap between the developing roller 6 and the casing 4 (C in FIG. 3)
Is too large, the airflow is weak at a position distant from the surface of the developing roller 6, and there is a possibility that the floating toner may scatter outside the developing device 3 from the gap. Therefore, by reducing the gap (C in FIG. 3) between the developing roller 6 and the casing 4 on the upstream side in the rotation direction of the developing roller 6 from the toner supply area, the developing device on the upstream side of the toner supply area in the toner conveyance direction is reduced. (3) The toner can be prevented from scattering outside. More specifically, by setting the gap (C in FIG. 3) between the developing roller 6 and the casing 4 to be 0.1 mm or more and 1 mm or less, the floating from the magnetic brush 9 can be performed without damaging the developing roller 6. It is possible to efficiently suppress the toner from scattering outside the developing device.

Further, a flexible sheet member 11 is fixed to the casing 4 on the upstream side of the toner supply area of the developing roller 6 in the toner conveying direction, and a free end of the flexible sheet member 11 is brought into contact with the developing roller 6. Thus, the space between the developing roller 6 and the casing 4 may be shielded. The flexible sheet member 11
Since the developing roller 6 comes into contact with the toner supply area on the upstream side in the toner transport direction from the toner supply area, the toner layer used for development is not disturbed. Further, since the developing roller 6 and the casing 4 are shielded on the upstream side of the toner supply area in the toner conveyance direction, the toner can be reliably prevented from being scattered outside the developing device 3 on the upstream side of the toner supply area in the toner conveyance direction.

Further, in the above-described developing device, since the toner conveying direction by the developing roller 6 in the toner supplying area and the developer conveying direction by the supplying roller 7 are the same, the air flow around the developing roller 6 and the The airflow of the toner is stabilized, and the floating toner can be efficiently conveyed.

As described above, according to the printer of the present embodiment, the toner is supplied to the developing roller 6 from the magnetic brush 9 on the supply roller 7 by using the supply roller 7 on the surface of which the magnetic brush 9 made of the two-component developer is formed. Developing device 3
Is used, the stress on the developing roller 6 and the toner is reduced, and a high-quality full-color image with good durability and equivalent to that of the one-component developing method can be obtained. Further, scattering of the toner floating from the magnetic brush 9 to the outside of the developing device 3 can be reduced without disturbing the toner layer on the developing roller 6. As a result, it is possible to maintain high-quality image while preventing stains in the printer, image stains, and stains of the operator's hands.

In this embodiment, in the toner supply area where the developing roller 6 and the supply roller 7 face each other, the developing roller 6
Although the description has been made using the developing device in which the toner transport direction of the toner supply direction and the developer transport direction of the supply roller 7 are the same, the present invention is directed to the above-described toner supply area. The present invention is also applicable to the developing device 3 in which the direction of transport of the developer is opposite, and the same effect is obtained.

[0032]

According to the first to fifth aspects of the present invention, a toner supply member having a magnetic brush made of a two-component developer formed on its surface is used, and only the toner is transferred to the toner carrier from the magnetic brush on the toner supply member. In the developing device for supplying and supporting the toner, there is an excellent effect that the scattering of the toner floating from the magnetic brush to the outside of the developing device can be reduced without disturbing the toner layer on the toner carrier.

In particular, according to the second aspect of the invention, the floating toner from the magnetic brush scatters out of the developing device from the gap between the toner carrier and the casing without causing disturbance of the toner layer and damage of the toner carrier. There is an effect that it is possible to efficiently reduce the number of operations.

In particular, according to the invention of claim 3 or 4,
There is an effect that the floating toner from the magnetic brush can be efficiently sucked into the developing device.

In particular, according to the invention of claim 5, there is an excellent effect that high quality image quality can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a printer according to an embodiment.

FIG. 2 is a schematic configuration diagram of a developing device according to the embodiment.

FIG. 3 is an explanatory diagram of each interval between a developing roller and a casing and between a supply roller and a casing in the developing device according to the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor belt 2 charging device 3 developing device 4 developing device casing 5 two-component developer 6 developing roller 7 supply roller 8 regulating blade 9 magnetic brush 10 stirring / transport member 11 flexible seal member 20 intermediate transfer device 21 intermediate transfer Belt 22 Transfer paper 23 Cleaning device 24 Transfer device 25 Fixing device

Continued on the front page (72) Inventor Katsuhiro Aoki 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H077 AC04 AC12 AC16 AD02 AD06 BA08 CA11 EA11

Claims (5)

[Claims] 1. A toner carrier which carries toner on its surface and conveys it to a development area facing the image carrier, and a two-component developer containing toner and magnetic particles is carried on the surface and faces the toner carrier. A toner supply member that conveys the toner in the two-component developer to the toner carrier,
In a developing device having an opening in the developing area of the toner carrier and covering the toner carrier and the toner supply member, a downstream side of the toner supply area in a toner conveying direction by the toner carrier. Wherein the gap between the toner carrier and the casing is smaller than the gap between the toner supply member and the casing on the downstream side of the toner supply area in the developer conveying direction by the toner supply member. Developing device. 2. A developing device according to claim 1, wherein a gap between said toner carrier and said casing at a downstream side of said toner supply area in a toner conveying direction by said toner carrier is 0.1 mm or more and 1 mm or less. A developing device. 3. The developing device according to claim 1, wherein a gap between the toner supply member and the casing in a region downstream of the toner supply region in a developer conveying direction by the toner supply member is 0.5 mm or more. A developing device having a thickness of 2.5 mm or less. 4. The developing device according to claim 1, wherein a direction in which the toner is transported by the toner carrier in the toner supply region and a direction in which the developer is transported by the toner supply member are the same. Developing device. 5. An image forming apparatus comprising: an image carrier; latent image forming means for forming a latent image on the image carrier; and developing means for developing a latent image on the image carrier. An image forming apparatus comprising the developing device according to claim 1 as a developing unit.