JPH045388B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a developing device in an image forming apparatus such as a copying machine or an electrostatic printer that uses electrophotography.

Conventional Structure and Problems There are two types of conventional magnetic brush development methods, such as those used in copying machines, that use a developer consisting of toner and a magnetic carrier: a contact development method and a non-contact development method. The contact development method includes a nonmagnetic sleeve that supports a developer layer on its surface and has a magnet inside, and a photosensitive drum coated with a photosensitive material on a nonmagnetic base. In this structure, a non-magnetic sleeve is provided facing the photosensitive drum at a position where the standing developer comes into contact with the photosensitive drum, with a certain gap therebetween. The principle of this development is that the developer layer on the non-magnetic sleeve is tribo-electrified by rotating a magnet to triboelectrically charge the toner and carrier, and then when the charged toner is positioned with the electrostatic latent image on the photosensitive drum, the latent image is It adheres to the latent image due to electrostatic attraction.

In the non-contact development method, a non-magnetic sleeve that carries a developer layer on its surface and has a magnet inside, and a non-magnetic sleeve and a non-magnetic roller at a position where the developer layer on the non-magnetic sleeve and the non-magnetic roller contact each other. It is composed of a non-magnetic roller that faces each other with a certain gap therebetween, and a photosensitive drum that faces the non-magnetic roller with a certain gap at a position away from the opposing portion.
This development principle works by rotating a magnet to frictionally charge the developer layer on the non-magnetic sleeve and the carrier, and then applying a voltage between the non-magnetic sleeve and the non-magnetic roller to remove the charged toner. The toner is deposited on a non-magnetic roller, and then the toner deposited on the non-magnetic roller flies due to the electrostatic attraction of the electrostatic latent image on the photosensitive drum and adheres to the latent image. Said 2
In order to uniformly adhere the toner onto the photosensitive drum or non-magnetic roller that the spiked developer contacts, one method is to apply the developer layer on the non-magnetic sleeve to the surface of the photosensitive drum or non-magnetic roller. It is necessary to bring the developer layer into contact with the developer layer and increase the contact pressure in a state where the developer layer stands up. However, in order to bring the developer layer into contact with the surface of the photosensitive drum or non-magnetic roller in a spiky state, it is necessary to reduce the gap between the tip of the spiers of the developer layer and the surface of the photosensitive drum or non-magnetic roller to zero. be. Therefore, there was a drawback that the contact pressure was reduced. Furthermore, in order to increase the contact pressure, it is necessary to reduce the gap between the tip of the developer layer and the surface of the photosensitive drum or the nonmagnetic roller to be zero or less.
Therefore, there was a drawback that a part of the tip of the spike did not stand. Therefore, the two methods have the disadvantage that the gap between the non-magnetic sleeve and the photosensitive drum or the non-magnetic roller must be precisely installed, resulting in high assembly costs.

OBJECTS OF THE INVENTION The present invention solves the problems of the prior art, and aims to provide a developing device that does not require highly accurate adjustment and has high image quality.

Structure of the Invention The developing device of the present invention includes a moving body whose surface is coated with a non-magnetic material such as Al, polyester, vinylidene fluoride, zinc oxide, selenium, etc. on the surface of a magnetic material such as Fe or SUM, a non-magnetic toner, and a magnetic material. a first non-magnetic sleeve having a rotating magnet therein and fixed thereon;
The moving body and the non-magnetic sleeve are arranged to face each other with a certain gap therebetween.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows a contact development method of a developing device according to a first embodiment of the present invention, and is an example used in a developing process of a copying machine.

In FIG. 1, 1 is a photosensitive drum of a moving body;
For example, zinc oxide on the surface of the base 2 such as Fe, SUM, etc.
It is provided by coating a photosensitive material which is a dielectric non-magnetic material 1a such as selenium or OPC. 3 is a charger, and depending on the photosensitive material of the photosensitive drum 1, for example, a negative corona in the case of zinc oxide or a positive corona in the case of selenium is supplied to the first high-voltage DC power supply 4.
This is to charge the surface of the photosensitive material of the photosensitive drum 1. Reference numeral 5 denotes an optical section that projects a patterned light image onto the photosensitive drum 1 to form a latent image. Reference numeral 6 denotes a first non-magnetic sleeve, which has a first magnet 7 inside. Further, the first non-magnetic sleeve 6 is provided at a position facing the photosensitive drum 1 with a certain gap, the first non-magnetic sleeve 6 is fixed, and the first magnet 7 is rotated clockwise. . By fixing the first non-magnetic sleeve 6,
The accuracy of the variation in the gap between the photosensitive drum 1 and the first non-magnetic sleeve 6 is improved, and the development characteristics are stabilized. Furthermore, a magnetic carrier 8 is attached to the first non-magnetic sleeve 6 by the magnetic force of the first magnet 7a and is made to stand up. Further, the magnetic carrier 8 facing the photosensitive drum 1 is kept in pressure contact with the surface of the photosensitive drum 1 in a state where it is always standing up due to the magnetic force between the first magnet 7 and the base 2 made of magnetic material. 9 is non-magnetic insulating toner;
10 is a hopper containing insulating toner 9, and has an outlet portion 10a at one end. Reference numeral 11 denotes a toner supply roller, which is made of foamed plastic, for example, and is provided at the outlet portion 10a of the hopper 10. The insulating toner 9 is supplied to the magnetic carrier 8 on the non-magnetic sleeve 6 by the toner supply roller 11, and is frictionally charged with the magnetic carrier 8 by the rotation of the first magnet 7. Reference numeral 12 denotes a prevention plate that prevents the insulating toner 9 and magnetic carrier 8 from scattering.

The operation of the developing device of the first embodiment configured as described above will be explained below.

In FIG. 1, zinc oxide is used as the photosensitive material of the photosensitive drum 1 in order to make the operation easier to understand. A negative corona is applied to the charger 3 by the first high-voltage DC power supply 4 to negatively charge the entire surface of the photosensitive drum 1. Next, a pattern light image is projected onto the optical section 5 onto the negatively charged photosensitive drum 1 to form a latent image. During this time, the insulating toner 9 in the hopper 10 is supplied to the magnetic carrier 8 on the non-magnetic sleeve 6 by the toner supply roller 11, and is positively charged by friction due to the rotation of the magnet 8, and reaches a position facing the photosensitive drum 1. transport. Next, the photosensitive drum 1 rotates, and the negatively charged latent image on the photosensitive drum 1 comes into contact with the positively charged insulating toner 9 on the nonmagnetic sleeve 6 to perform development.

FIG. 2 shows a developing device showing a second embodiment of the present invention. In the figure, 1 is a photoreceptor, 2 is a base, and 3
is a charger, 4 is a first high-voltage DC power supply, 5 is an optical section, 6 is a first non-magnetic sleeve, 7 is a first magnet, 8 is a magnetic carrier, 9 is an insulating toner, 10
10a is a hopper, 10a is an outlet portion, 11 is a toner supply roller, and 12 is a prevention plate, and the above structure is the same as that shown in FIG. The difference from the configuration of the embodiment shown in FIG. 1 is that thirteen collecting means for collecting the magnetic carrier 8 attached to the photosensitive drum 1 are provided.

The recovery means 13 of the second embodiment shown in FIG. It is composed of 16 first doctors, one end of which is in contact with the surface, and the other end of which is opposed to the first nonmagnetic sleeve near the first nonmagnetic sleeve. Further, the second non-magnetic sleeve 14 is provided at a position away from the position where the photosensitive drum 1 and the first non-magnetic sleeve 6 face each other, and at a position with a constant gap from the photosensitive drum 1.
Further, the second non-magnetic sleeve 14 is fixed, the second magnet 15 is rotated counterclockwise, and the first
One end of the doctor 16 is fixed to the hopper.
The developing process of the second embodiment shown in FIG. 2 is basically the same as that of the first embodiment shown in FIG. Therefore, the operation of the recovery means 13 will be explained next. Collection means 13
In the developing process, a part of the magnetic carrier 8 attached to the photosensitive drum 1 is transferred to a second part by the magnetic force of the second magnet 15.
Then, by rotating the second magnet 15, the second non-magnetic sleeve 14 is attracted onto the non-magnetic sleeve 14.
The upper magnetic carrier 8 is conveyed to the first doctor 16, and then the first doctor 16 scrapes off the magnetic carrier 8 and collects it inside the hopper 10.

Next, the recovered magnetic carrier 8 is attracted by the magnetic force of the first magnet 7. Therefore, a toner image without the magnetic carrier 8 can be formed on the photosensitive drum 1. In addition, since the recovery means 13 can fix the second non-magnetic sleeve 14 and the doctor 16 and recover the magnetic carrier 8 into the hopper, the second non-magnetic sleeve 16 and the doctor 16 have a long life. be. Furthermore, since the recovered magnetic carrier is packed onto the first non-magnetic sleeve 6 again, the used carrier 8 is not consumed.

FIG. 3 shows a non-contact developing system of a developing device according to a third embodiment of the present invention, and is an example used in a developing process of a copying machine.

In FIG. 3, reference numeral 1 denotes a photoreceptor in which a photosensitive material is coated on an Al base 2a. 3 is a charger, 4 is a first high voltage DC power supply, 5 is an optical section, 6 is a non-magnetic sleeve, 7 is a first magnet, 8 is a magnetic carrier, 9 is an insulating toner, 10 is a hopper, 10a
11 is a toner supply roller, and 12 is a prevention plate. Reference numeral 17 denotes a magnetic roller of the movable body, for example, a magnetic roller surface such as Fe or SUM is coated with a non-magnetic material 17a of Al or a dielectric non-magnetic material 17a such as polyester or vinylidene fluoride. In this embodiment, a polyester dielectric nonmagnetic material 17a is used. Magnetic roller 17
is provided at a position facing the photosensitive drum 1 with a certain gap therebetween, and is rotated, for example, in a clockwise direction. The first non-magnetic sleeve 6 is provided at a position facing the magnetic roller 6 with a certain gap between the photosensitive drum 1 and the magnetic roller 17, for example. The sleeve 6 is fixed and the first magnet 7 is rotated clockwise. Furthermore, a magnetic carrier 8 is disposed on the first non-magnetic sleeve 6.
are attached by the magnetic force of the first magnet 7 and made to stand up. Further, the magnetic carrier 8 facing the magnetic roller 17 is always pressed against the surface of the magnetic roller 17 in a standing state due to the magnetic force between the first magnet 7 and the magnetic roller 17.

The toner supply roller 11 is made of foamed plastic, for example, and is provided at the exit portion 10a of the hopper 10. The insulating toner 9 accommodated in the hopper 11 is supplied to the magnetic carrier 8 on the first non-magnetic sleeve 6 by the toner supply roller 11, and is frictionally charged with the magnetic carrier 8 by the rotation of the first magnet 7. be. 18 is a second high-voltage DC power supply that applies voltage between the magnetic roller 17 and the non-magnetic sleeve 6 and generates an electric field therebetween.
This makes it easier for the insulating toner 9 on the non-magnetic sleeve 6 to adhere electrostatically to the magnetic roller 17, and makes it difficult for the magnetic carrier 8 to adhere electrostatically. Further, in order to prevent the magnetic carrier 8 from adhering to the magnetic roller 17, the surface of the magnetic roller 17 is coated with a non-magnetic material. The principle is that the magnetic roller 17
is always opposed to the first magnet 7, and is slightly magnetized, making it easier for the magnetic carrier 8 to attract it. but,
When the surface of the magnetic roller 17 is coated with a non-magnetic material 17a, the magnetic carrier 8
The adsorption power of the material becomes weaker and it becomes difficult to adsorb the product. Therefore, the magnetic carrier 8 is less likely to adhere to the surface of the magnetic roller 17. Further, by coating the surface of the magnetic roller 17 with a dielectric non-magnetic material, even if a bias voltage is applied between the magnetic roller 17 and the non-magnetic sleeve 7, there is no fear of leakage between them. Therefore, development characteristics are stabilized. The prevention plate 12 is
This prevents the insulating toner 9 and magnetic carrier 8 from scattering.

The operation of the developing device of the third embodiment configured as described above will be described below.

In FIG. 3, zinc oxide is used as the photosensitive material of the photosensitive drum 1 in order to make the operation easier to understand. A negative corona is applied to the charger 3 by the first high-voltage DC power supply 4 to negatively charge the entire surface of the photosensitive drum 1. Next, a pattern light image is projected onto the negatively charged photosensitive drum 1 by the optical section 5 to form a latent image. During this time, the insulating toner 9 in the hopper 10 is supplied to the magnetic carrier 8 on the non-magnetic sleeve 6 by the toner supply roller 11, and is positively charged by friction due to the rotation of the first magnet 7. transport it to a position facing the In addition, a positive voltage is applied between the magnetic roller 17 and the non-magnetic sleeve 6 by the second high-voltage power supply 18 to the first non-magnetic sleeve side 6, and the positively charged insulating toner is transferred onto the magnetic roller 17. 9 is electrostatically deposited. Next, the photosensitive drum 1 rotates, and the negatively charged latent image on the photosensitive drum 1 is
When facing the positively charged insulating toner 9 on the magnetic roller 17, the insulating toner 9 flies onto the photosensitive drum 1 and can perform development. Therefore, it is possible to perform non-contact development using an insulating toner, which has the advantage of enabling color development.

FIGS. 4 and 5 show developing devices showing fourth and fifth embodiments of the present invention. In the figure, 1 is a photoreceptor, 2a is a base, 3 is a charger, 4 is a first high-voltage power supply, 5 is an optical part, 6 is a first non-magnetic sleeve, 7
1 is a first magnet, 8 is a magnetic carrier, 9 is an insulating toner, 10 is a hopper, 10a is an outlet portion, 11 is a toner supply roller, 12 is a prevention plate, 17 is a magnetic roller, 17a is a non-magnetic material, 18 is the second high-voltage power supply, and the above configuration is the same as the configuration shown in FIG. The difference from the configuration of the embodiment shown in FIG. 3 is that collecting means 19 for collecting the magnetic carrier 8 attached to the magnetic roller 17 and the photosensitive drum 1 is provided. The collecting means 19 of the fourth embodiment shown in FIG.
0 second non-magnetic sleeve, 21 second magnets provided inside it, and second non-magnetic sleeve 20
It consists of 22 first doctors that come into contact with the surface of the blade. Also, for example, the second non-magnetic sleeve 20
The magnetic roller 17 and the first non-magnetic sleeve 6
At a position away from the position facing the magnetic roller 1,
7 and the photosensitive drum 1, and fix the second non-magnetic sleeve 20.
The magnet 21 is rotated counterclockwise, and one end of the first doctor 22 is fixed to the hopper 10. The developing process of the fourth embodiment shown in FIG. 4 is basically the same as that of the third embodiment shown in FIG.

Therefore, the operation of the collecting means 19 will be explained next. The collecting means 19 attracts the magnetic carrier 8 partially attached to the magnetic roller 17 and the photosensitive drum 1 during the development process onto the second non-magnetic sleeve 20 by the magnetic force of the second magnet 21, and then magnet 2
1 rotation, the magnetic carrier 8 on the second non-magnetic sleeve 20 is conveyed to the first doctor 22, and then the first doctor 22 scrapes off the magnetic carrier 8 and collects it inside the hopper 10. . Next, the recovered magnetic carrier 8 is attracted by the magnetic force of the first magnet 8. Therefore, it is possible to form a toner image on the photosensitive drum 1 without the adhesion of the magnetic carrier 8.

The collecting means 19 of the fifth embodiment shown in FIG. 5 is composed of 23 magnetic rollers and 24 second doctors that come into contact with the surface of the magnetic rollers. For example, the magnet roller 23 is provided at a position away from the position where the magnetic roller 17 and the first non-magnetic sleeve 6 face each other, and at a position with a certain gap from the magnetic roller 23 and the photosensitive drum 1. 23 clockwise, and one end of the second doctor 24 to the hopper 1.
It is fixed at 0. The developing process of the fifth embodiment shown in FIG. 5 is the same as that of the third embodiment shown in FIG. Therefore, the operation of the recovery means 19 will be explained next. The collecting means 19 partially collects the magnetic roller 17 during the developing process.
The magnetic carrier 8 attached to the photosensitive drum 1 is attracted onto the magnetic roller 23 by the magnetic force of the magnetic roller 23, and then the magnetic carrier 8 on the magnetic roller 23 is moved to the second doctor 24 by the rotation of the magnetic roller 23. The magnetic carrier 8 is conveyed, and then the magnetic carrier 8 is scraped off by the second doctor 24 and collected inside the hopper 10. Next, the recovered magnetic carrier 8 is attracted by the magnetic force of the first magnet 7. Therefore, it is possible to form a toner image on the photosensitive drum 1 without the adhesion of the magnetic carrier 8. Furthermore, since the recovered magnetic carrier 8 is returned onto the first non-magnetic sleeve 6, the used magnetic carrier 8 is not consumed.

Effects of the Invention In the developing device of the present invention, a magnetic roller 17 is provided between the non-magnetic sleeve 6 and the photosensitive drum 1 at a constant interval from each other, and is further provided opposite to the photosensitive drum 1 and the magnetic roller 17, respectively. A magnetic carrier collecting means 19 is provided, which has an excellent effect in removing unnecessary magnetic carriers. Further, by coating the magnetic surface of the magnetic roller 17 with a dielectric non-magnetic material 17a, it is made difficult for the magnetic carrier to be attracted to the magnetic roller 17. Therefore, high-quality development of only the toner image can be performed.

[Brief explanation of drawings]

1 is a partially sectional side view of a developing device according to a first embodiment of the present invention, FIG. 2 is a partially sectional side view of a developing device according to a second embodiment of the present invention, and FIG. 3 is a partially sectional side view of a developing device according to a second embodiment of the present invention. FIG. 4 is a partially sectional side view of the developing device in the fourth embodiment of the present invention, and FIG. 5 is a partially sectional side view of the developing device in the fifth embodiment of the present invention. It is a partially sectional side view. 1...Photosensitive drum, 6...Nonmagnetic sleeve, 7
...Magnet, 8...Magnetic carrier, 9...Toner,
17...Magnetic roller, 17a...Nonmagnetic material,
19... Collection means, 22... First doctor, 2
4...Second Doctor.

Claims (1)

[Claims] 1 A non-magnetic sleeve 6 which carries a developer layer made of non-magnetic toner and a magnetic carrier on its surface and has a magnet 7 inside, and a non-magnetic sleeve 6 which is located between the photosensitive drum 1 and the non-magnetic sleeve 6 at a constant interval. It has a magnetic roller 17 having a non-magnetic material 17a on its surface, which faces each of the photosensitive drum 1 and the non-magnetic sleeve 6, and further includes a magnetic roller 17 having a non-magnetic material 17a on its surface, and further has a magnetic roller 17 arranged at a constant interval between the photosensitive drum 1 and the magnetic material. A developing device having magnetic carrier collection means 19 facing each of the rollers 17.