JPH01161366A - Carrier selecting device - Google Patents

Abstract

PURPOSE:To select a normal carrier uniformized in magnetic characteristics through a simple device by applying, between a magnetic brush roller and an abnormal carrier attracting drum, potential difference higher than that to be applied between a photosensitive drum and a magnetic drum in an ordinary developing process. CONSTITUTION:A nonselected carrier 1 fed from a carrier feeder 2 to the magnetic brush roller 3 magnetically attracted to the surface of the roller 3 is transferred and an abnormal carrier 6 is attracted by an abnormal carrier attracting drum 4 at the position nearest to the drum 4 by setting a relative potential difference between the roller 3 and the drum 4 to a value higher than the potential difference between the photosensitive drum and the magnetic brush roller at the time of ordinary development. On the other hand, the normal carrier 7 normal in magnetic characteristics remains on the roller 3 and is moved in the direction of arrow B and scraped off with a recovering blade 9 down to a normal carrier recovering box 11, and the abnormal carrier 6 is scraped down with a recovery blade 8 into an abnormal carrier recovering box 10, thus permitting the abnormal carrier 6 inferior in magnetic characteristics to be separated from the normal carrier 7.

Description

Detailed Description of the Invention [Summary] The present invention relates to a carrier sorting device for determining and sorting the magnetic properties of carriers in two-component developers used in electrostatic printing devices. The purpose of the present invention is to provide a carrier sorting device with a simple configuration that judges the quality of the characteristics and sorts them out.A device that sorts the carrier that is mixed with the toner to form a two-component developer by judging the quality of the magnetic properties. containing an unsorted carrier before being mixed with the toner;
and a carrier supplying device for discharging the carrier, a magnetic brush roller for magnetically adsorbing the unsorted carriers discharged from the carrier, and a rotatable rotatable device proximate to the magnetic brush roller, and a defective magnetic property on the brush roller. an abnormal carrier suction drum that sucks and attaches abnormal carriers;
A power source is provided between the magnetic brush roller and the abnormal carrier suction drum, and the power source provides a potential difference larger than the potential difference applied between the photosensitive drum and the magnetic brush roller in a normal development process. Due to the given large potential difference, abnormal carriers with poor magnetic properties on the magnetic brush roller are attracted by the electrostatic attraction force of the abnormal carrier suction drum and separated from normal carriers.

[Industrial application field]

The present invention relates to a carrier sorting device that determines the quality of the magnetic properties of carriers in two-component developers used in electrostatic printing devices and sorts them out.

[Conventional technology]

The two-component developer used in laser printers, etc. consists of about 95 parts by weight of a carrier made of magnetic powder, specifically iron particles, with a diameter of about 1501 m, and about 5 parts by weight of toner, which is particles with a diameter of about 5 to 30 mm. It is composed of a mixture of.

This two-component developer is made by stirring the toner in a developing machine to charge the toner, and then using a magnetic roller consisting of a plurality of magnetic poles arranged in a cylindrical shape that are fixed so as not to rotate, and an outer side of the magnetic roller. The charged toner is supplied onto a magnetic brush roller composed of a rotating non-magnetic cylinder, for example, an aluminum sleeve, and is uniformly deposited on the surface of the magnetic brush roller.

On the other hand, a latent image made of static electricity that is selectively charged in accordance with the printing pattern is formed on the surface of the photosensitive drum.The toner is attached to this latent image, and the attached toner is transferred onto plain paper to form a transferred image. The printing pattern is configured to be heat-fixed to obtain a duplicate printed pattern.

By the way, toner is a particle made of a heated mixture of about 90 parts by weight of resin as a base, about 5 parts by weight of each colorant (dye, pigment), and charge control agent, and it produces a clear printed pattern. In order to obtain this, it is necessary that the charge density on the surface of the toner particles is uniform, and that the carrier transports the toner so that toner of the same ffl can adhere to areas of the same charging state on the latent image.

[Problem that the invention seeks to solve]

2. Description of the Related Art Electrostatic printing devices such as laser printers are attracting attention for their high-speed processing capabilities, and increasingly high-speed printing and high print quality are required. As a result, when printing is performed with variations in the magnetic properties of carriers contained in a two-component developer, the static force of the photosensitive drum is stronger than the magnetic attraction force of the magnetic brush roller for the carrier whose magnetic attraction force has weakened. The electric attraction force acts more strongly and is attracted to the photosensitive drum along with the toner, which causes stains such as black dots on the paper surface, resulting in a problem of deterioration of printing quality.

The present invention was created in view of the above-mentioned conventional drawbacks, and an object of the present invention is to provide a carrier sorting device that determines the quality of carrier magnetic properties and sorts them.

[Means for solving problems]

FIG. 1 is a schematic diagram of a carrier sorting device of the present invention. A carrier that is mixed with toner to form a two-component developer,
A device for determining the quality of magnetic properties and sorting, containing unsorted carrier 1 before being mixed with the toner,
and a carrier supply device 2 for discharging the unsorted carriers 1, a magnetic brush roller 3 for magnetically adsorbing the unsorted carriers 1 discharged from the carrier supply device 2, and a magnetic brush roller 3 that is rotatably provided in the vicinity of the magnetic brush roller 3, Between the abnormal carrier suction drum 4, which attracts and adheres the abnormal carrier 6 with poor magnetic properties, and the magnetic brush roller 3 and the abnormal carrier suction drum 4, there is a gap between the photosensitive drum and the magnetic brush roller in a normal development process. and a power source 5 which provides a larger potential difference than the potential difference applied to the magnetic brush roller, and the abnormal carrier 6 having poor magnetic properties on the magnetic brush roller is removed by the abnormal carrier 6 having poor magnetic properties on the magnetic brush roller. The carrier is configured to be attracted by the electrostatic attraction force of the carrier attraction drum 4 and separated from the normal carrier 7.

[For production]

The unsorted carrier (2) supplied from the carrier supply device 2 to the magnetic brush roller 3 is magnetically attracted to the surface of the magnetic brush roller 3 rotating in the direction of arrow B in the form of a magnetic brush and moves. At the position closest to the abnormal carrier suction drum 4, the abnormal carrier 6 whose magnetic properties have deteriorated and is included in the unsorted carrier 1 causes the relative potential difference between the magnetic brush roller 3 and the abnormal carrier suction drum 4 to become normal. By setting the potential difference to be larger than the potential difference between the photosensitive drum and the magnetic brush roller during development, the abnormal carrier adsorption drum 4 is set to be larger than the magnetic attraction force.
The electrostatic attraction force acts more strongly, and the abnormal carrier is attracted and attached to the suction drum 4, and moves in the direction of arrow A.

On the other hand, the normal carrier 7 having good magnetic properties moves in the direction of arrow B while remaining there due to the magnetic attraction force of the magnetic brush roller 3.

The thus sorted carriers are scraped off by the collection blades 8.9 and collected into the abnormal carrier collection box 10 and the normal carrier collection box 11.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a schematic diagram of a carrier sorting device. In the figure, a carrier sorting device 2 is equipped with a screw 2 a for feeding unsorted carriers 1 to a magnetic brush roller 3 .

The magnetic brush roller 3 is similar to the magnetic brush roller of a laser printer, and includes a magnetic roller including a plurality of fixed magnetic poles (not shown) arranged in a cylindrical shape, and a non-magnetic material rotating on the outside of the magnetic roller. It consists of a cylinder, for example a sleeve made of aluminum. In the normal development process, the surface of the sleeve of this magnetic brush roller 3 has a voltage of -300V.
The carrier selection configuration of the present invention, although the pressure R(Dt) is applied.

Therefore, a smaller voltage of about -IOθ to -50V is applied from the power supply 5a. The unsorted carriers l supplied from the carrier supply device 2 are attracted to the sleeve surface of the magnetic brush roller 3 to which this voltage is applied by the magnetic attraction force, and move in the direction of the arrow B.

The abnormal carrier suction drum 4 has an electrostatic suction function similar to a photosensitive drum, and has a structure in which the surface of an aluminum cylinder is coated with resin, and the drum surface is connected to a power source 5b. A voltage comparable to the charged potential of the photosensitive drum, for example, -650 .ANG., is applied. Therefore, a larger potential difference is created between the abnormal carrier suction drum 4 and the magnetic brush roller 3 than in the case of a normal development process.

When such a large potential difference is formed, the abnormal carrier 6 with deteriorated magnetic properties, which is magnetically attracted to the surface of the magnetic brush roller 3, becomes different from the normal developing process when it comes closest to the abnormal carrier adsorption drum 4. The abnormal carrier is strongly attracted by the electrostatic attraction force of the abnormal carrier attraction drum 4, which is set to be larger than the electrostatic attraction force of the photosensitive drum, and is attached to the surface of the abnormal carrier attraction drum 4 and moves in the direction of arrow A. However, the normal carrier 7 with good magnetic properties moves in the direction of arrow B while being attracted by the magnetic attraction force of the magnetic brush roller 3.

The abnormal carrier 6 is collected into an abnormal carrier collection box 10 by a collection blade 8 that scrapes off the surface of the abnormal carrier suction drum 4. In addition, the normal carrier 7 has a collection blade 9 that sweeps the surface of the magnetic brush roller 3.
, the carrier is collected into the normal carrier collection box 11.

In addition, this sorting device performs repeated sorting multiple times.
Furthermore, the magnetic properties of the normal carrier 7 can be made uniform.

An embodiment of the present invention has been described above, and the voltage applied to the magnetic brush roller and the abnormal carrier suction drum is the same as the voltage applied to the magnetic brush roller during development, and the voltage applied to the abnormal carrier suction drum is the same as the voltage applied to the photoreceptor during development. A voltage higher than the voltage may be applied.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, normal carriers with uniform magnetic properties can be selected with a simple device configuration, so that it is effective in improving printing quality when applied to laser printers, etc. be.

[Brief explanation of the drawing]

FIG. 1 shows a schematic diagram of a carrier sorting device of the present invention. In the figure, 1 is an unsorted carrier, 2 is a carrier supply device, 3 is a magnetic brush roller, 4 is an abnormal carrier suction drum, 5 is a power supply, 6 is an abnormal carrier, 7 is a normal carrier, 8 and 9 are collection blades, respectively. show.

Claims (1)

[Scope of Claims] An apparatus for sorting carriers that are mixed with toner to form a two-component developer by determining the quality of their magnetic properties, comprising: unsorted carrier (1) before being mixed with the toner; a carrier supply device (2) that accommodates and discharges unsorted carriers; a magnetic brush roller (3) that magnetically attracts the unsorted carriers (1) discharged from the carrier; and a magnetic brush roller (3) adjacent to the magnetic brush roller (3). an abnormal carrier suction drum (4) which is rotatably provided and which attracts and adheres the abnormal carrier (6) with poor magnetic properties on the brush roller; the magnetic brush roller (3) and the abnormal carrier suction drum; (4) and a power source (5) that provides a potential difference larger than the potential difference applied between the photosensitive drum and the magnetic brush roller in a normal development process, and Due to the large potential difference, the abnormal carrier (6) with poor magnetic properties on the magnetic brush roller is transferred to the abnormal carrier suction drum (4).
A carrier sorting device characterized in that it is configured to attract and separate normal carriers (7) by electrostatic attraction force.