JPH045387B2 - - Google Patents

Description

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

Conventional configurations and their problems Conventional developing devices, such as copying machines, that develop by flying toner, use a jumping development method that uses one component of magnetic insulating toner, and a jumping development method that uses one component of non-magnetic insulating toner and a magnetic carrier. There is a two-component magnetic brush method. The problem with the jumping development method is that the toner is a magnetic material, and since the magnetic material is generally colored, it is difficult to obtain a clear color image, and therefore it is difficult to create a color image. The magnetic brush method supports a developer layer made of non-magnetic insulating toner and a magnetic carrier on its surface, has a non-magnetic sleeve with a magnet inside, and a non-magnetic sleeve that faces the non-magnetic sleeve with a certain gap. It is composed of a magnetic roller and a photosensitive drum that faces the non-magnetic roller with a constant gap at a position away from the opposing portion. The development principle is to frictionally charge the developer layer on the non-magnetic sleeve by rotating a magnet to triboelectrically charge the toner and carrier, and then apply a voltage between the non-magnetic sleeve and the non-magnetic roller to de-charge the charged toner. Toner is deposited on a magnetic roller and then on a non-magnetic roller, which is then flown by the electrostatic attraction of the electrostatic latent image on the photosensitive drum and adheres to the electrostatic latent image. This magnetic brush method has the advantage that the toner is non-magnetic and can be colored. In addition, in this method, in order to uniformly adhere the toner on the non-magnetic roller, the developer layer on the non-magnetic sleeve is brought into contact with the surface of the non-magnetic roller, and the developer layer is brought into contact with It is necessary to increase the pressure. However, in order to bring the developer layer into contact with the surface of the non-magnetic roller in a spiky state, it is necessary to make the gap between the tip of the spiers of the developer layer and the surface of the non-magnetic roller zero. 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 non-magnetic roller to zero or less. Therefore, there was a drawback that a part of the tip of the spike did not stand. Therefore, this method requires the gap between the non-magnetic sleeve and the non-magnetic roller to be installed with high precision, which has the drawback of increasing assembly cost.

OBJECTS OF THE INVENTION The present invention solves the problems of the conventional art, and provides a developing device that enables development of toner that does not contain a magnetic substance, enables colorization, and does not require highly accurate adjustment. With the goal.

Structure of the Invention The developing device of the present invention supports a developer layer made of non-magnetic toner and a magnetic carrier on its surface, has a rotating magnet inside, and has a fixed first non-magnetic sleeve; The magnetic roller includes a first non-magnetic sleeve and a magnetic roller facing each other at a constant interval, and the developer layer on the first non-magnetic sleeve is brought into contact with the magnetic roller.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows 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, reference numeral 1 denotes a photosensitive drum which is a latent image holder, and includes, for example, an electrode 2 whose surface is coated with a photosensitive material such as zinc oxide, selenium, OPC, or the like. Reference numeral 3 denotes a charger which applies corona, which is negative in the case of zinc oxide and positive in the case of selenium, depending on the photosensitive material of the photosensitive drum 1, by the first high-voltage DC power supply 4, and charges the surface of the photosensitive material of the photosensitive drum 1. It is something that charges up. 5 is the optical department,
A pattern light image is projected onto the photosensitive drum 1 to form a latent image. A magnetic roller 6 is made of a magnetic material such as Fe or SUM. Further, the magnetic roller 6 is provided at a position facing the photosensitive drum 1 with a certain gap therebetween, and is rotated, for example, in a clockwise direction. Reference numeral 7 denotes a first non-magnetic sleeve, which has a first magnet 8 inside. The first non-magnetic sleeve 7 is provided at a position away from the position where the photosensitive drum 1 and the magnetic roller 6 face each other, and is opposed to the magnetic roller 6 with a certain gap therebetween. The magnetic sleeve 7 is fixed and the first magnet 8 is rotated clockwise. Furthermore, a magnetic carrier 9 is placed on the first non-magnetic sleeve 7.
They are attached and made to stand up by the magnetic force of the magnet 8. Further, the magnetic carrier 9 facing the magnetic roller 6 is kept in pressure contact with the magnetic roller 6 in a state where it always stands up due to the magnetic force between the first magnet 8 and the magnetic roller 6. 10 is a hopper containing non-magnetic insulating toner, 11 is a hopper containing the insulating toner 10, and an outlet portion 1 is provided at one end.
1a. 12 is a toner supply roller;
For example, it is made of foamed plastic and is provided at the outlet 11a of the hopper 11. The insulating toner 10 is supplied to the magnetic carrier 9 on the first non-magnetic sleeve 7 by the toner supply roller 12, and is frictionally charged with the magnetic carrier 9 by the rotation of the first magnet 8. 13 is a second high-voltage DC power supply that applies voltage between the magnetic roller 8 and the non-magnetic sleeve 7 and generates an electric field therebetween.
The insulating toner 10 on the non-magnetic sleeve 7 is easily electrostatically deposited on the magnetic roller 8, and the magnetic carrier 9 is made difficult to electrostatically adhere. 14 is a prevention plate that prevents the insulating toner 10 and the magnetic carrier 9 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 current power source 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 10 in the hopper 11 is supplied to the magnetic carrier 9 on the non-magnetic sleeve 7 by the toner supply roller 12, is positively charged by friction due to the rotation of the first magnet 8, and is charged by the magnetic roller 6. Transport it to the opposite position. In addition, a positive voltage is applied between the magnetic roller 6 and the non-magnetic sleeve 7 by the second high-voltage DC power supply 13 to the first non-magnetic sleeve 7 side, so that the magnetic roller 6 is insulated with a positive charge. toner 10
electrostatically adhere. Also, as an experimental fact, the height of the spikes of the magnetic carrier 9 is kept constant at 1 mm, and the gap between the magnetic roller 6 and the non-magnetic sleeve 7 is set at 0.5 to 1 mm.
The insulating toner 10 is uniformly electrostatically deposited on the magnetic roller 6 even if the magnetic roller 6 changes. Next, photosensitive drum 1
rotates, and when the negatively charged latent image on the photosensitive drum 1 faces the positively charged insulating toner 10 on the magnetic roller 6, the insulating toner 1
0 can fly onto the photosensitive drum 1 to perform development.

FIGS. 2 and 3 show developing devices showing second and third embodiments of the present invention. In the figure, 1 is a photoreceptor, 2 is an electrode, 3 is a charger, 4 is a first high-voltage DC power supply, 5 is an optical section, 6 is a magnetic roller, and 7 is a first
1 is a non-magnetic sleeve, 8 is a first magnet, 9 is a magnetic carrier, 10 is a non-magnetic insulating toner, 11 is a hopper, 11a is an outlet section, 12 is a toner supply roller, 13 is a second high-voltage power supply, 14 is a prevention plate, and the above structure is the same as the structure shown in FIG.

The difference from the configuration of the embodiment shown in FIG. 1 is that 15 collecting means for collecting the magnetic carrier 9 attached to the magnetic roller 6 and the photosensitive drum 1 are provided. The collecting means 15 of the second embodiment shown in FIG.
6 second non-magnetic sleeves, 17 second magnets provided therein, and second non-magnetic sleeves 16.
It consists of 18 first doctor blades that come into contact with the surface of the blade. Also, for example, the second non-magnetic sleeve 16
is provided at a position away from the facing position of the magnetic roller 6 and the first non-magnetic sleeve 7 and at a position with a certain gap from the magnetic roller 6 and the photosensitive drum 1, and the second non-magnetic sleeve 16 is fixed, the second magnet 17 is rotated counterclockwise, and one end of the first doctor 18 is fixed to the hopper 11.
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 15 will be explained next. Collection means 15
The magnetic carrier 9 partially attached to the magnetic roller 6 and the photosensitive drum 1 during the developing process is transferred to the second magnet 1.
7 is attracted onto the second non-magnetic sleeve 16, and then the rotation of the second magnet 17 causes the second non-magnetic sleeve to be attracted onto the second non-magnetic sleeve 16.
The magnetic carrier 9 on the non-magnetic sleeve 16 of
Then, the magnetic carrier 9 is scraped off by the first doctor 18 and collected inside the hopper 11. Next, the recovered magnetic carrier 9 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 9. In addition, since the recovery means 15 can fix the second non-magnetic sleeve 16 and the doctor 18 and recover the magnetic carrier 9 into the hopper,
The second non-magnetic sleeve 16 and doctor 18 have a long life. Furthermore, since the recovered magnetic carrier 9 is returned onto the first non-magnetic sleeve 7, the used magnetic carrier 9 is not consumed.

The collecting means 15 of the third embodiment shown in FIG. 3 is composed of 19 magnetic rollers and 20 second doctors that come into contact with the surface of the magnetic rollers. For example, the magnet roller 19 is provided at a position away from the position where the magnetic roller 6 and the first non-magnetic sleeve 7 face each other, and at a position with a certain gap from the magnetic roller 6 and the photosensitive drum 1. The roller 9 is rotated clockwise, and one end of the second doctor 20 is fixed to the hopper 11. The developing process of the third embodiment shown in FIG. 3 is basically the same as that of the first embodiment shown in FIG. Therefore, the operation of the recovery means 15 will be explained next. The collecting means 15 partially collects the magnetic roller 9 during the developing process.
The magnetic carrier 9 attached to the photosensitive drum 1 is attracted onto the magnetic roller 19 by the magnetic force of the magnetic roller 19, and then the magnetic carrier 9 on the magnetic roller 19 is conveyed to the second doctor 20 by rotation of the magnetic roller 19. Then, the second doctor 20 scrapes off the magnetic carrier 9 and collects it inside the hopper 11. Next, the collected magnetic carrier 9 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 9. Furthermore, since the recovered magnetic carrier 9 is returned onto the first non-magnetic sleeve 7, the used magnetic carrier 9 is not consumed.

Effects of the Invention The developing device of the present invention includes a fixed first non-magnetic sleeve that carries a developer layer made of toner and a magnetic carrier on its surface, and has a rotating magnet inside.
The magnetic roller includes a first non-magnetic sleeve and a magnetic roller facing each other at a constant interval, and the developer layer on the first non-magnetic sleeve is brought into contact with the magnetic roller. With this configuration, by fixing the first non-magnetic sleeve, the accuracy of the gap variation between the magnetic roller and the first non-magnetic sleeve is improved, and the contact between the developer on the surface of the non-magnetic sleeve and the magnetic roller is improved. The amount becomes uniform. In addition, since the developer is brought into contact with the magnetic force generated between the rotating magnet and the magnetic roller,
The developer on the surface of the first non-magnetic sleeve can be stably contacted with a predetermined pressure. Therefore, the gap accuracy between the magnetic roller and non-magnetic sleeve can be easily achieved, and the development characteristics are stable. Furthermore, by providing a recovery means, the magnetic roller and the carrier on the latent image carrier can be sequentially removed, so that development suitable for colorization can be performed. Therefore, the problem of highly accurate adjustment of the gap between the magnetic roller and the non-magnetic sleeve is eliminated.

[Brief explanation of drawings]

FIG. 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. 7 is a partially sectional side view of a developing device in a third embodiment of the present invention. 6... Magnetic roller, 7... First non-magnetic sleeve, 8... Magnet, 9... Magnetic carrier, 10...
…toner.

Claims (1)

[Claims] 1. A non-magnetic sleeve 7 which carries a developer layer made of non-magnetic toner and a magnetic carrier on its surface and has a magnet 8 inside, and a non-magnetic sleeve 7 which is located between the photosensitive drum 1 and the non-magnetic sleeve 7 at a constant interval. It has a magnetic roller 6 facing each of the photosensitive drum 1 and the non-magnetic sleeve 7, and the photosensitive drum 1 and the magnetic roller 6 are arranged at a constant interval.
magnetic carrier collection means 15 facing each of the
A developing device having: