JPS5929869B2 - magnetic brush developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device for developing an electrostatic latent image.
In particular, a type that includes a fixed sleeve and a magnet rotatably installed inside the sleeve, and uses the magnetic attraction force of the rotating magnet to convey a magnetically attractable developer to develop an electrostatic latent image. The present invention relates to a developing device.

A conventional electrostatic latent image developing device consists of a fixed non-magnetic cylindrical sleeve 3 and this sleeve 3, as shown in FIG.
A magnet 2 rotatably provided in the hopper 8, a hopper 8 that can accommodate a magnetic developer 4 that can be transported by the magnetic attraction of the magnet, and a mixer 6 that stirs the magnetic developer. It consists of a blade 5 for controlling the amount of magnetic developer.

Now, assuming that the photosensitive drum 1 with an electrostatic latent image is rotating in the direction of the arrow, the magnet 2 in the sleeve 3 is rotated in the direction of the arrow by the drive system T, and due to this rotation, the toner is transferred to the magnet 2. The electrostatic latent image can be moved in the opposite direction and directed toward the development area to develop the electrostatic latent image. However, in this developing device, the moving speed of the magnetic developer is slow compared to the rotational speed of the drive system, and when the speed of the photoreceptor drum is fast, this developing device has drawbacks such as not increasing the density sufficiently. Ta. The present invention proposes a new developing device and its drive system that improve the drawbacks of conventional developing devices.

In other words, by increasing the number of developing rolls, the developing time and number of times can be increased, and the shortcomings of conventional equipment, such as high speeds, can be addressed. At the same time, a new and simple drive system has been developed. The aim is to prevent the complexity of the device and make it more compact. The present invention is based on the second
As shown in FIGS. 3 and 3, it has a fixed non-magnetic enclosure and a rotatable magnetic roll, and a magnetic roller that holds and conveys the developer that can be magnetically attracted onto the enclosure for development. In the brush developing device, the magnetic roll includes a first magnetic roll rotated by a drive system and at least one second magnetic roll arranged parallel to the first magnetic roll and rotated by the magnetic attraction force of the first magnetic roll. It is characterized by consisting of a magnetic roll.

In the present invention, there is no need to connect the second developing magnet member with a sprocket or a chain, and since it is driven entirely by magnetic force, it is possible to prevent the apparatus from becoming cluttered.

An embodiment of the present invention will be explained with reference to FIG.

Reference numeral 1 denotes a photoreceptor drum having an electrostatic latent image, and a developing device of the present invention comprising two magnetic rolls is disposed at a position facing the drum.

This developing device has one end of the shaft connected by a drive system T, and three
The first (lower) magnetic roll is composed of a polar symmetrically magnetized cylindrical magnet 2 and a non-magnetic sleeve 3 that completely covers this magnet, and the magnetic attraction force of this rotating cylindrical magnet 2 Therefore, the second (upper) magnetic roll consists of an eight-pole symmetrically magnetized cylindrical magnet 12 that rotates in opposite directions and a non-magnetic sleeve 13 that covers it, and a magnetic developer (
A hopper 18 that stores a two-component developer consisting of a magnetic carrier and toner, or a one-component developer consisting of magnetic toner, and two regulating blades for controlling the amount of developer adhering to both magnetic rolls. It consists of 5. Further, 6 is a mixer for stirring the developer, and 15 is a splitter block for dividing the developer on the two magnetic rolls into upper and lower parts. The two rotating cylindrical magnets have exactly the same diameter, number of poles, magnetized width, and magnetic flux density, and the distance d between both rolls is 10 mm so that they can rotate due to the action of magnetic attraction. It is set to . Now, put a two-component developer 4 consisting of a magnetic carrier and toner as a magnetic developer into the hopper 8, and rotate the drive system 7 in the direction of the arrow to remove the developer on the first magnetic roll (lower stage). It passes through the regulating blade 5 and moves in the direction opposite to the rotational direction of the cylindrical magnetic roll (in the direction of the arrow).
Further, the developer on the second magnetic roll (upper stage) also moves in the opposite direction to the rotation direction of the second cylindrical magnet 12, which rotates due to the magnetic attraction force of the first circular magnet 2. . These two developing rolls are a photosensitive drum 1 holding an electrostatic latent image.
This means that the conveyance forms are different in direction, in the same direction and in the opposite direction to the rotational direction of. As a result of experiments, it has been found that a developed image of good quality can be obtained by using such a mode of conveyance in different directions. The developer that came into contact with the electrostatic latent image and did not contribute to development is collected between the two rolls and is divided into upper and lower parts by a splitter block 15 and transported. New toner is then mixed and agitated, and the process is repeated to develop a new latent image. FIG. 3 shows another embodiment of the invention. Three cylindrical magnets are arranged inside the shell 9 made of non-magnetic material. These three cylindrical magnets each have the same pitch,
The number of rotating poles is magnetized. Further, the respective magnets are arranged in such a positional relationship that the other two upper and lower cylindrical magnets 2 and 22 can be rotated by the magnetic attraction force of the middle magnet 12. now,
When the middle magnet 12 rotates counterclockwise, the upper and lower two magnets 2 and 22 rotate clockwise, respectively. As the earth magnet 2 rotates, the magnetically attractive developer (in this case, magnetic toner) 24 in the hopper 18 begins to be conveyed and moves along the shell 9 toward the development area. Also, since the lower magnet 22 is also rotating clockwise, the magnetic toner is
From top to bottom it can pass together with the photoreceptor drum through a development area, where development takes place. After this, the magnetic toner that has not been developed is scraped off by a scraper 10 and collected in a receiving tray 11. According to this embodiment, since the developing area can be made sufficiently large, excellent effects such as speeding up can be obtained. In the embodiments shown in Figures 2 and 3, the diameters of the cylindrical magnets in the magnetic attraction relationship are all the same, and the number of poles is the same, but it is sufficient if they are magnetized at approximately the same pitch, and even if the diameters are different. , it goes without saying that it can be used satisfactorily even if the number of poles is different.

Further, the magnet is not limited to an isotropic cylindrical magnet, but a segment magnet may also be used. As described above, by increasing the number of magnetic rolls, a sufficient developed image can be obtained even if the speed of the photosensitive drum is increased. This is due to the lengthening of the developing nip width and the increase in the number of times of development. Furthermore, by simplifying the drive system to one, the device can be prevented from becoming complicated and can be made smaller.

[Brief explanation of drawings]

FIG. 1 shows a conventional fixed sleeve rotating magnet type developing device.

Claims (1)

[Claims] 1. A magnetic brush developing device that has a fixed non-magnetic envelope and a rotatable magnetic roll, and that holds and conveys a developer that can be magnetically attracted onto the envelope for development. comprises a first magnetic roll rotated by a drive system and at least one second magnetic roll arranged parallel to the first magnetic roll and rotated by the magnetic attraction force of the first magnetic roll. Magnetic brush developing device.