JPS61204657A - Preventing device for toner scatter of developing device - Google Patents

Abstract

PURPOSE:To prevent toner from scattering from a developing device by providing a sheet member which covers the opening part of the developing device and then contacts the surface of a magnetic brush after the magnetic brush passes through a developing part. CONSTITUTION:The magnetic brush 4 rotates according to the rotation of a sleeve 5 and a film 18 and an electrode 19 are rubbed against the surface of the magnetic brush, thereby energizing the front end part of the film 18 gently that it abuts on a photosensitive layer 36 gently. The electrode 19 puts toner in various operations. A potential of the same polarity with the necessary potential of, for example, the dead toner and toner decreased in the quantity of electrostatic charging is applied to the electrode 19 from a power source 22 through a resistor 21 and an electric wire 20 to give a charge to said toner by the toner rubbing, and the toner is used for development together with normal toner while the charge is held. Consequently, the dead toner and toner decreased in the quantity of electrostatic charging are reused for the development, so toner scatter preventing effect is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] □ The present invention relates to a developing device used in electrophotography, and particularly to prevention of toner scattering in the developing device.

[Background of the invention]

In order to prevent toner from scattering in the developing device, a method has been proposed in which the gap between the developing device and the photosensitive drum is sealed with an insulating film. However, conventional devices have the disadvantage that the sealing effect is not sufficient. This device was published in Japanese Patent Application Laid-Open No. 49-1989.
It is disclosed in Japanese Patent No. 78556.

[Purpose of the invention]

An object of the present invention is to improve the effect of preventing toner from scattering from a developing device.

[Summary of the invention]

Conventionally, in the case of a mixture of magnetic powder and toner, which is a two-component developer, which forms a developer, the density of the toner, the amount of charge of the toner, the generation of dead toner during use, or the electrical resistance of the magnetic powder Depending on the relationship with the magnetic brush, the rotational speed of the magnetic brush, the structure of the developing device, etc., toner scattering is likely to occur.

In particular, the present invention takes into account that dead toner is a cause of background smear when forming toner particles, and that toner scattering increases as dead toner floats in the developing device.
In order to add charge to the dead toner and to the dangerous toner, which can contribute to development, the toner is directly connected to the magnetic brush in or near the developing area where it rubs against the photosensitive member and the magnetic brush. Depending on the sliding friction with the film, which is a sliding member, an electric charge is applied directly to the dead toner and the toner with a reduced charge amount, and before the electric charge disappears, the toner is rubbed against the electrostatic latent image on the photosensitive member. It is used for the formation of toner power. The rubbing member further blocks ventilation between the inside of the developing device and the outside world, and reliably prevents toner from scattering.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The drawing is a side sectional view of a developing device 1 according to the present invention. The developing device 1 has a case 3 sandwiched between side plates 2 and 2 (the front side is not shown) which are arranged opposite to each other, and a non-magnetic brush 4 is formed at a predetermined position in the case 3. A sleeve 5 made of a magnetic metal is rotatable in the direction of the arrow, has a magnetic pole attached to a predetermined position, and has a built-in magnetic roller 6.
A Zenigata roller 8 for agitating and transporting the developer 7 is arranged at the lower right side of the roller. The Zenigata roller 8 has a plurality of threads 1 on the shaft 9.
0 are connected and the rods 12 groups are communicated with the holes of the collar 11. The Zenigata roller 8 is given rotation in the direction of the arrow, and the group of rods 12 stirs the developer 7 and also transports it to and from the sleeve 5 side. Above the sleeve 5 and Zenigata roller 8, there are many fins 14 on the sliding plate 13.
form a bridge over a diagonal. Above the sleeve 5 and inside the case 3, a pointed ridgeline portion 15 for regulating developer is provided. One end of a film 18 made of urethane is adhered to the flat surface of the bent portion 16 of the case 3 in order to close the opening 17. The other end of the film 18 is connected to the magnetic brush 4
The width reaches within or near the developing area of
0 and a power supply 22 via a resistor 21. Case 3
A sealing member 23 made by folding back a urethane film is attached to the lower tip of the sleeve 5. The sealing member 23 is brought into light contact with the magnetic brush 4 as shown, so as not to obstruct the movement of the developer 7, and to cut off ventilation between the inside of the developing device 1 and the outside world.

The developer 7 inflow side of the sliding plate 13 is bent downward to provide a downwardly downward portion 13' to form a guide portion 24 facing the case 3. On the side of the case 3, a sensor portion 25 of a concentration detection device for the developer 7 is provided by being inserted into a through hole. The toner hopper part 26 is located in case 3. It is formed by a side plate 2 and an inclined side plate 3', and the bottom is closed with a sponge roller 27. Regarding toner replenishment, the sponge roller 27 is rotated in the direction of the arrow, and the toner 28 is replenished into the developing device in a timely manner. Toner is supplied into the hopper 26 by moving the lid 29 in the direction of the double chain line. Note that the lid 29 is attached to the hopper 26.
The ear portion 33 is engaged with the pin 31 and serves as a support point, and the hopper 26 and the lid 29 are kept sealed with a gasket 30. A photosensitive layer 36 is disposed on the outer peripheral surface of the conductive drum 35, and the photosensitive drum 34 is rotated in the direction of the arrow as shown in the figure, and development is performed by rubbing against the magnetic brush 4.

Next, we will discuss the effects. The aforementioned Nyozen-type roller 8
is rotated in the direction of the arrow, and at the same time the sleeve 5
It also rotates. The developer 7 is attracted and collected on the sleeve 5 by the magnetic attraction force of the magnetic roller 6, and is conveyed as the sleeve 5 rotates. The developer 7 on the sleeve 5 is shaped by the pointed ridgeline portion 15 to form the magnetic brush 4. When forming the magnetic brush 4, the excess developer 7 is regulated by the pointed ridge line 15 and is pushed up into the opposed guide section 24, slides down on the sliding plate 13, and returns to the Zenigata roller 8 side. The developer 7 is pushed up the opposed guide part 24 and the sensor part 25 measures the concentration while the developer 7 is being conveyed. When the concentration decreases below the set value, the drive transmission mechanism is operated via an electric circuit (not shown), and the main body is The replenishment of the sponge rollers 27 and 28 by transmitting the drive from the power source is carried out as appropriate, taking into account the replenishment position and the delay in detection, until the density reaches the set value.

The magnetic brush 4 rotates with the rotation of the sleeve 5, and its surface rubs against the film 18 and the electrode 19.
The tip portion of the photosensitive layer 36 is biased so as to lightly contact the photosensitive layer 36. The leading end of the magnetic film 18 may be located in or near the development area caused by sliding contact with the photosensitive drum 34 and the magnetic brush 4. The electrode 19 has the effect of imparting various effects to the toner, but here, in particular, with regard to toner, it is a friend that electrically revives dead toner and even toner whose charge amount has decreased. Regarding toner scattering, as described above, the magnetic brush 4 forming the magnetic brush 4
For example, a potential of the same polarity as the required potential of dead toner or toner with a reduced charge amount is applied to the electrode 19 from the power supply 22 via the resistor 21 and the electric wire 20, and the toner is rubbed by the toner. A charge is applied to the toner, and while the charge is retained, the toner is subjected to development together with normal toner. After development, the magnetic brush 4 is once separated from the sleeve 5 and moved to the jaw-shaped roller 8.
The fluid is conveyed and agitated at the trough, and then transported to the third sleeve 5 side where the magnetic brush is formed, and then divided into the magnetic brush 4 side and the sliding plate 13 side. Since the film 18 for preventing scattering of the toner and imparting charge to the toner rubs against the surface of the photosensitive layer 36, it is preferable to use an elastic material that does not cause scratches on the surface of the photosensitive layer. If the toner that rubs against the film 18 generates a required polar charge due to friction, the electrode 19 may be omitted. Film 18 is based on a material that generates a frictional charge when rubbed with toner.
It is preferable to use a material that is difficult to adhere to when rubbed with toner. For the sealing member 23 as well, a material that does not easily attract toner during rubbing may be selected, and a urethane film is suitable.

Since the film 18 is sandwiched between the photosensitive layer 36 and the magnetic brush 4 and has a good shape, the rubbing portion thereof is constantly cleaned. Note that if the toner is not sufficiently removed in a cleaning step (not shown), the toner may accumulate near the contact area between the film 18 and the photosensitive layer 36, and the toner may pass through the contact area. Also, since the magnetic plan 4 also has a cleaning effect, it is possible to prevent the non-image area from becoming dirty. Note that it is preferable to apply a seal between the side plate 2 and the vicinity of the edge of the photosensitive drum 34 with a flocked material 37 to prevent toner from scattering.

The electrophotographic apparatus using the developing device with the above-described toner scattering prevention mechanism can reduce the scattered toner cleaning maintenance period to 500 sheets compared to the conventional apparatus's 500 sheets.

〔Effect of the invention〕

As described above, according to the present invention, since the photosensitive drum and the magnetic brush are inserted from the rotating entry side into the developing area where the dielectric film is rubbed, the dead toner and the amount of charge decrease, and the toner is revived. Since it contributes to development, the effect of preventing toner scattering is improved.

[Brief explanation of the drawing]

The drawing is a side sectional view of a developing device according to the present invention. DESCRIPTION OF SYMBOLS 18... Film, 19... Electrode, 20... Electric wire, 21... Resistor, 22... Power supply, 23... Seal member.

Claims (1)

[Claims] 1. In a developing device equipped with a magnetic brush that is rotated in the same direction as the outer peripheral rotation direction of the photosensitive drum, the photosensitive drum and the magnetic brush are placed in a developing area where the photosensitive drum and the magnetic brush rub together. A film made of a dielectric material is shallowly inserted from the rotational entry side of the brush, and the opening of the developing device is closed with the film, and a seal is further provided in contact with the surface of the magnetic brush after the magnetic brush passes through the developing section. A toner scattering prevention device for a developing device, which is made up of several members.