JPH11149216A - Electrophotographic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a decrease in adhesion of recycled toner in an electrophotographic apparatus using a two-component developer composed of a magnetic carrier and a toner, and to reduce the adhesion of the recycled toner. The separated developer is collected to obtain a uniform image free from background contamination and without density unevenness. SOLUTION: An image carrier 10 is formed by adhering toner of a magnetic brush on a developer carrier 20 formed of a two-component developer 16.
While the upper latent image is developed, the developer carrier 2 after the development is developed.
Developing means 13 for separating the developer on the surface of the toner at the developer separating position
Cleaning means 15 for removing the residual toner on the image carrier 10 after transferring the image to the recording medium, toner recycling means 27 for collecting the removed toner to the developing means 13 while stirring, and developing at the developer separating position. Developer collecting means 3 for transporting the developer separated from the developer carrier 20 and mixing it with the recycled toner t in the middle of the toner recycling means 27
0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transferring an image formed on an image carrier such as a photoreceptor by an electrophotographic method, such as a copying machine, a printer, a facsimile, and a multifunction machine using a laser, and The present invention relates to an electrophotographic apparatus that performs recording on a recording medium such as a card and a card. In particular, a magnetic brush is formed on the developer carrier of the developing means using a two-component developer composed of a magnetic carrier and a toner, and the toner of the magnetic brush is attached to develop the latent image on the image carrier. The present invention relates to an electrophotographic apparatus for forming an image on an image carrier.

[0002]

2. Description of the Related Art Conventionally, this type of electrophotographic apparatus has been disclosed in, for example, JP-A-5-249824 and JP-A-5-249.
As described in Japanese Unexamined Patent Application Publication No. 828 and Japanese Unexamined Patent Application Publication No. 8-1144984, it remains on the image carrier after image transfer from the viewpoint of ecological protection such as resource protection and environmental protection, and from the standpoint of reducing running costs. In some cases, the toner is removed by a cleaning unit, and the removed toner is collected by a toner recycling unit to a developing unit and reused.

[0003]

However, when the recycled toner is used to remove residual toner from the image carrier,
For example, it is deformed or pulverized by the cleaning blade of the cleaning means, and various additives on the surface are peeled off, the characteristics are changed and the triboelectric charging ability is reduced,
It could not be attached to the carrier, or even if it could, it could only be attached with very weak adhesion.

For this reason, toner has been scattered by the rotation of the developer carrying member, and has adhered to the surface of the image carrying member, causing background contamination or uneven density, resulting in deterioration of image quality.

[0005] Further, the toner from which the additive has been peeled off has a remarkably reduced fluidity, thereby causing unevenness or aggregation of the toner concentration, causing unevenness in the output image, and causing a dropout phenomenon in a character portion or the like. Sometimes happened.

On the other hand, if the developer is left for a long period of time or the environment changes, charges leak from the developer, the electrostatic adhesion between the magnetic carrier and the toner is released, and the toner separated from the magnetic brush is removed from the developer. It may accumulate immediately below the carrier. The presence of this unrecoverable toner whose behavior is not controlled by a magnetic brush or developing bias promotes background fouling. In recent years, a weakly charged developing process is often employed, and the toner tends to fall more easily.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic apparatus that recycles toner by preventing the adhesion of the recycled toner from lowering and recovering the developer separated from the developer carrier to eliminate background contamination. An object is to obtain a uniform image without density unevenness.

[0008]

Therefore, according to the present invention, there is provided an electrophotographic apparatus comprising a two-component developing device comprising a magnetic carrier and a toner, as in an embodiment described with reference to the following drawings. A magnetic brush is formed on the developer carrier 20 with the two-component developer 16 using the developer 16, and the toner of the magnetic brush is applied to develop the latent image on the image carrier 10, while after the development, Developing means 13 for separating the developer 16 remaining on the developer carrier 20 at a developer separating position b; transferring the image on the image carrier 10 developed by the developing means 13 to a recording medium; Cleaning means 1 for removing toner remaining on carrier 10
5, a toner recycle unit 27 for collecting the toner removed by the cleaning unit 15 into the developing unit 13 while stirring, the developer carrier 20 and the image carrier 1
The developer collecting means 30 which is provided almost immediately below the position 0 and which conveys the developer 16a separated from the developer carrier 20 at the developer separating position b and mixes with the recycled toner t in the middle of the toner recycling means 27. And characterized in that:

According to a second aspect of the present invention, in the electrophotographic apparatus according to the first aspect, as in an embodiment described with reference to FIG. b, the developer removing member 33 is brought into contact with it.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a main part of a laser printer according to the present invention. 10 in the figure
Is a drum-shaped image carrier. As is well known, the charging means 11 and the optical writing means 12 are provided around the image carrier 10.
Developing means 13 transferring means 14 cleaning means 15
And so on.

As the image carrier 10 rotates, first, the surface thereof is uniformly charged by the charging means 11, and then the laser beam L is irradiated by the light writing means 12 to perform writing. An electrostatic latent image is formed on the surface.

Thereafter, when the image carrier 10 passes the developing position as the image carrier 10 rotates, toner is adhered by the developing means 13 to develop the latent image on the image carrier 10. Then, with the rotation of the image carrier 10, the timing is adjusted to the image formed on the image carrier 10, a recording medium such as a sheet or a card is sent below the image carrier 10, and the recording medium is
The image formed on the image carrier 10 is transferred using a transfer unit 14.

The recording medium after the image transfer is conveyed to fixing means (not shown), where the transferred image is fixed by applying, for example, heat and pressure, and then discharged to a paper output unit (not shown). Stack on.

On the other hand, the image carrier 10 after transferring the image is prepared for the next image formation after the toner remaining on the surface thereof is removed by the cleaning means 15 and the charge is removed by the charge removing means (not shown).

In the illustrated laser printer,
In a housing 17 of the developing means 13, a first rotation stirring member 18, a second rotation stirring member 19, and a developer carrier 20 are provided so as to be parallel to the image carrier 10, respectively. A partition plate 21 is provided between the first rotation stirring member 18 and the second rotation stirring member 19. Further, a tip of a layer thickness regulating member 22 is provided on the outer periphery of the developer carrying member 20 so as to face each other.

The developer carrier 20 is configured by providing fixed magnetic poles in a rotating cylindrical non-magnetic sleeve.

In the illustrated laser printer, a two-component developer 16 composed of a magnetic carrier and a toner is housed in a housing 17 and conveyed in one axial direction while being stirred by a first rotation stirring member 18. , Second rotary stirring member 1
In the same manner, the material 9 is also conveyed to the other side in the axial direction while being stirred. Then, the toner is charged to a predetermined charge amount by friction with the magnetic carrier, and adheres to the surface of the carrier particles. The fully charged toner particles are then deposited around the non-magnetic sleeve at the fixed pole.

The thickness of the developer adhered to the developer carrier 20 is regulated by a layer thickness regulating member 22. Then, with the rotation of the developer carrier 20, a magnetic brush is formed with the two-component developer 16 on the developer carrier 20 by the fixed magnetic pole provided therein. The image carrier 1 is changed by the applied developing bias voltage.
An electrostatic field is formed between the image carrier 10 and the developer carrier 20, thereby causing the toner of the magnetic brush to adhere to the latent image on the image carrier 10 and to be developed in the developing area a as shown in FIG.

After the development, the developer remaining on the developer carrier 20 separates and drops from the non-magnetic sleeve at the developer separation position b shown in FIG.

On the other hand, the above-mentioned cleaning means 15 includes a cleaning blade 24. The cleaning blade 24 presses the tip against the surface of the image carrier 10 to scrape off residual toner on the image carrier 10 after image transfer. Then, the toner scraped off by the cleaning means 15 is transported to one side by a transport screw 25 provided in parallel with the image carrier 10.

In the illustrated laser printer, a toner recycling unit 27 is provided on one side of the image carrier 10. The toner recycling unit 27 is configured by housing a transport screw 29 in a pipe 28. And the transport screw 2
In step 5, the toner t conveyed to one side of the image carrier 10 is collected by the developing means 13 while stirring.

In the illustrated laser printer, a developer collecting means 30 is provided almost immediately below the developer carrier 20 and the image carrier 10. The developer collecting means 30 is configured by housing the transport screw 31 in the semi-cylindrical portion 17a of the housing 17, and at the developer separating position b, the developer carrier 20
The developer 16a separated from the toner is conveyed and mixed with the recycled toner t in the middle of the toner recycling means 27.

As shown in FIG. 3, the developer 16a separated and dropped from the developer carrier 20 is returned to the developing unit 13 while being agitated with the recycled toner t by the toner recycling unit 27. After being transported together with the two-component developer 16 while being stirred again by the first rotation stirring member 18, it is also transported while being stirred by the second rotation stirring member 19 in the same manner, and the toner is charged to a predetermined charge by friction with the magnetic carrier. It is charged to an amount and adheres to the surface of the carrier particles.

As shown in FIG. 4, the developer carrier 2
When the developer removing member 33 is brought into contact with the developer separating position b, the developer is reliably separated from the developer carrier 20 after the development, and the separating position is optimized by the developer collecting means 30. Recovery efficiency can be increased.

The developer removing member 33 may be formed of a resin material or a metal material. In consideration of durability, it is preferable to use a metal material. However, when a metal material is used, the developer removing member 33 is electrically connected so that the developing bias does not leak through the developer removing member 33. Must be installed on the float.

The contact angle may be inclined as shown in FIG. 3 or may be vertical.

[0027]

According to the first aspect of the present invention, the recycled toner is collected while being stirred by the toner recycling means, so that the adhesion of the recycled toner due to poor charging can be prevented from lowering.

Further, for example, when left for a long period of time or when the environment changes, the developer separated from the developer carrier can be collected by the developer collecting means. The collected developer is mixed with the recycled toner and conveyed to the developing unit while stirring, so that the developing unit can be charged normally even if mixed with a developer having an appropriate toner concentration.

Thus, it is possible to prevent a decrease in the adhesion of the recycled toner due to poor charging, and to collect the developer separated from the developer carrying member to obtain a uniform image free from background contamination and without density unevenness. .

According to the second aspect of the present invention, since the developer removing member comes into contact with the developer separating position of the developer carrying member, the developer is reliably separated from the developer carrying member after development.
Further, it is possible to improve the collection efficiency of the developer collection unit by setting the separation position to be the best.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a laser printer according to the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a partial plan view thereof.

FIG. 4 is a similar partial enlarged view showing a case where a developer removing member abuts on a developer separating position of a developer carrier in FIG. 2;

[Explanation of symbols]

 Reference Signs List 10 image carrier 13 developing means 15 cleaning means 16 two-component developer 16a developer separated from developer carrier 20 developer carrier 27 toner recycling means 30 developer collecting means 33 developer removing member b developer separating position t Recycled toner

Claims (2)

[Claims] 1. A two-component developer comprising a magnetic carrier and a toner, a magnetic brush is formed on a developer carrier using the two-component developer, and the toner of the magnetic brush is attached to the image carrier to form a magnetic brush. Developing means for developing the latent image and separating the developer remaining on the developer carrier after the development at a developer separating position; and developing the image on the image carrier developed by the developing means on a recording medium. Cleaning means for removing toner remaining on the image carrier after the transfer, toner recycling means for collecting the toner removed by the cleaning means in the developing means while stirring, the developer carrier and the image carrier Almost right under the body,
An electrophotographic apparatus comprising: a developer collecting unit that conveys the developer separated from the developer carrier at the developer separating position and mixes with the recycled toner in the middle of the toner recycling unit. 2. The electrophotographic apparatus according to claim 1, wherein a developer removing member is in contact with a developer separating position of said developer carrier.