JPS5917829B2 - Fukushiyakiniokel Jikiburashigenzouhou Oyobi Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic brush developing method and a magnetic brush developing device in electrophotography or electrostatic recording.

5. The magnetic brush development method is a type of dry development method that uses a two-component developer with iron powder as a carrier, which is attracted by a magnet, creating a so-called magnetic brush! This is a developing method in which ears of paper called riichi are formed and the ears are brought into contact with an electrostatic latent image on a recording medium to visualize the latent image.

The device has a developing roller equipped with a non-magnetic sleeve having a width comparable to the width of the recording medium, and a magnet housed in the sleeve over its entire width,
Either rotate one side of the sleeve or the magnet, or
Alternatively, by rotating both of them together or by rotating them in reverse, the developer contained in the developer container is attracted to the sleeve 1 and conveyed, and at a predetermined development position, the electrostatic charge on the recording medium is Development is carried out by contacting the latent image.

In conventional magnetic brush development methods and equipment, typically
Although one developing roller is used, it is difficult to faithfully reproduce a so-called fa original with low contrast and to obtain a copy image free from background smudges.

This is because the quality of the developed copy image changes slightly depending on the position of the magnet placed in the developing roller relative to the electrostatic latent image, so in order to obtain sufficient reproducibility for any original. This is because it was difficult to set the position of the magnet, and the position had to be set based on an average document. Another object of the present invention is to provide a magnetic brush that can exhibit an excellent cleaning effect in a device that also uses a magnetic brush developing device as a cleaning device for removing developer remaining on a recording medium after transfer. An object of the present invention is to provide a developing device.

The present invention will be described below with reference to the drawings. Figure 1 shows
An embodiment of the present invention is shown in which two developing rollers, a first developing roller 2 and a second developing roller 3, are installed on the surface of a photosensitive drum 1 that rotates in the direction of the arrow around a point 01 from the drum entrance side. are located close together. The first developing roller 2 includes a non-magnetic sleeve 4 that rotates in the direction of the arrow around a point 02, and a magnet roller 5 that is fixedly provided within the sleeve 4. has eight poles, and the position of any magnetic pole, for example, the N pole, is in the direction perpendicular to the surface of the photoreceptor 1, that is, the position of the N pole is
It is located on a straight line connecting the center 0 of the sleeve 4 and the center 02 of the sleeve 4.

On the other hand, the second developing roller 3 includes a sleeve 6 that rotates in the opposite direction to the first developing roller 2 around a point 03, and a magnet roller 7 that is rotatably and fixedly provided in the sleeve 6. The magnetic roller 7 also has eight poles, but the magnetic poles are located in a direction perpendicular to the surface of the photoreceptor 1, that is, on a straight line connecting the center 01 of the photoreceptor 1 and the center 03 of the sleeve 6. It is located away from the.

In other words, the direction perpendicular to the surface of the photoreceptor 1 is at a position midway between adjacent magnetic poles of the magnetic roller 7. In the vicinity of each developing roller 2 and 3,
Hoppers 9, 10 for containing developer 8 and adjustable doctor blades 11, 12 for regulating the thickness of the magnetic brush are provided. As is clear from FIG. 1, the developer 8 accommodated in the hopper 19 forms a magnetic brush 13 on the first developing roller while being regulated by the doctor blade 11. The agent 8 forms a magnetic brush 14 on the second developing roller 3 while being regulated by the doctor blade 12, and the electrostatic latent image on the photoreceptor 1 is brought into contact with the magnetic brushes 13 and 14 formed by these two developing rollers. 〇 As shown in Fig. 2, some of the lines of magnetic force emitted from the N pole are dissipated into the air, and some of them reach the S pole.

Therefore, the developer retention force at the magnetic pole portions is weak, and the developer retention force is strong at the intermediate portion between the magnetic poles, supported by the magnetic lines of force. In one embodiment of the present invention shown in FIG.
3 is in contact with the surface of the photoconductor, that is, located in the direction perpendicular to the surface of the photoconductor, so the developer holding power in this area is weak, and even in the latent image area with low surface potential on the photoconductor. It will be fully developed. On the other hand, the background portion with a lower surface potential is also developed, resulting in increased background smearing. However, the position of the magnetic pole of the magnetic roller 7 provided on the second developing roller 3 is different from that of the magnetic pole brush 14.
Since the middle part of the adjacent magnetic pole is located at the position where the magnetic pole contacts the surface of the photoreceptor, the developer holding power in this part is strong and the developer adhering to the background part can be scraped off. and eliminates background stains.

However, if the developer retention force is too strong, the developer adhering to the image area will also be scraped off, so the magnetic roller 7 provided on the second developing roller 3 is rotatable. The middle part of the magnetic pole can be adjusted closer to the magnetic pole part. In this invention, developing rollers are provided separately in the developing section, and the developer retention force at the developing position of one developing roller disposed on the recording medium entrance side is equal to the developer retention at the developing position of the other developing roller. In addition to the above-mentioned embodiments, other embodiments may be considered since the development is performed with a weaker force than the above-mentioned embodiments.

For example, this can also be achieved by making the magnetic force of the magnet of one developing roller disposed on the photoreceptor entry side weaker than the magnetic force of the magnet of the other developing roller.
In addition, if these developing devices are also used as cleaning devices to remove developer remaining on the photoreceptor after transfer, the cleaning process is performed by two developing rollers, instead of the conventional one. The residual developer can be removed more efficiently than when using a developing roller.

In this case, when the embodiment shown in FIG. 1 is used, the magnetic roller 15 of the first developing roller 2 is rotatably supported, and in the cleaning process, the magnetic brush 13 is used similarly to the second developing roller 3. The holding force of the magnetic brush (developer) may be strengthened by adjusting the intermediate portions of adjacent magnetic poles to be located at the position where the magnetic brushes contact the surface of the photoreceptor.

As described above, according to the present invention, the developing rollers are provided separately in the developing section, and the developer retention force at the developing position of one developing roller disposed on the recording medium entrance side is equal to that at the developing position of the other developing roller. Since the developer is developed with a weaker retention force than the developer, sufficient reproducibility can be obtained for any type of original, and copy images with no background smudges and particularly excellent reproducibility for fa originals can be obtained. can get.

Further, if the above-mentioned developing device is also used as a tarnishing device for removing the developer remaining on the recording medium after transfer, an excellent and efficient cleaning effect can be achieved.

Note that the recording medium used in the present invention is not limited to a drum-shaped recording medium, and it goes without saying that it can also be applied to a belt-shaped recording medium.

Further, the rotation of the sleeve is not limited to the above embodiment.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, and FIG.
The figure is an explanatory diagram for explaining the difference in developer holding power in the above embodiments. 1... Photosensitive drum, 2... First developing roller, 3... Second developing roller, 4, 6...
...Non-magnetic sleeve, 5, 7... Magnet roller 1, 8... Developer, 9, 10...
...Hopper 11,12...Doctor blade, 13,14...Magnetic brush, 01...
... Center of the photosensitive drum, 02 ... Center of the first developing roller, 03 ... Center of the second developing roller.

Claims (1)

[Claims] 1. A developer is attracted onto the roller by a developing roller equipped with a magnet in a non-magnetic sleeve, and a magnetic brush formed thereby is brought into contact with an electrostatic latent image on a recording medium. In the magnetic brush development method in a copying machine that performs development,
Developing rollers are provided separately in the developing section, and the developer retention force of one of the developing rollers disposed on the recording medium entrance side at the developing position is weaker than the developer retaining force of the other developing roller at the developing position. A magnetic brush development method for a copying machine, which is characterized in that development is performed using a magnetic brush. 2. In a copying machine in which a developer is attracted onto the roller by a developing roller equipped with a magnet in a non-magnetic sleeve, and a magnetic brush formed by this is brought into contact with an electrostatic latent image on a recording medium to perform development. In the magnetic brush development method,
Developing rollers are provided separately in the developing section, and the arbitrary magnetic pole position of the magnet of one developing roller disposed on the recording medium entry side is positioned in a direction perpendicular to the surface of the recording medium, and the magnet of the other developing roller is positioned in a direction perpendicular to the recording medium surface. A magnetic brush development method for a copying machine, characterized in that development is performed by shifting the position of a magnetic pole from a direction perpendicular to the surface of a recording medium. 3 In a copying machine in which developer is attracted onto the roller by a developing roller equipped with a magnet in a non-magnetic sleeve, and the magnetic brush formed thereby is brought into contact with an electrostatic latent image on a recording medium to perform development. In the magnetic brush development method,
A developing unit is provided with separate developing rollers, and development is carried out by making the magnetic force of the magnet of one of the developing rollers placed on the recording medium entry side weaker than the magnetic force of the magnet of the other developing roller. Magnetic brush development method for copying machines. 4 In a copying machine in which developer is attracted onto the roller by a developing roller equipped with a magnet in a non-magnetic sleeve, and a magnetic brush formed by this is brought into contact with an electrostatic latent image on a recording medium to perform development. In the magnetic brush development method,
1. A magnetic brush developing device for a copying machine, characterized in that developing rollers are provided separately in each developing section, and the developing rollers in the developing section also serve as cleaning rollers for removing developer remaining on a recording medium.