JPH07199629A - Toner supply device - Google Patents

Abstract

PURPOSE:To hold magnetic toner on the periphery of a roller by a magnet layer and to form stable electric field between the rollers by a covering layer. CONSTITUTION:The toner supply device supplying the magnetic toner to a developing roller 10 is constituted of a toner supply roller 7 and power sources 9 and 13 impressing bias between the two rollers 7 and 10. The toner supply roller 7 is formed of a rotatable conductive base substance 72, the non- conductive magnet layer 73 with which the outer periphery of the base substance is covered, and the conductive covering layer 74 with which the outer periphery of the magnet layer is covered and which is conducted to the base substance 72, and the bias is impressed between the roller 10 and the base substance 72 by the power sources 9 and 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner supply device for supplying magnetic toner from one roller to another roller in a developing device of an image forming apparatus using an electrophotographic copying method or a device for replenishing toner to this developing device. Regarding

[0002]

2. Description of the Related Art As the toner supply device, a first roller, a second roller facing the first roller at a predetermined minute interval, and a space between the first roller and the second roller. Power source means for applying a bias to the toner. For example, the toner held on the outer circumference of the second roller is held on the outer circumference of the first roller by an electric field formed between the rollers based on the bias. It is known to supply a developing agent.

[0003]

By the way, when a magnetic toner is used as the toner, it is necessary to stably hold the magnetic toner on the outer peripheral portion of the roller. Therefore, if a magnet is provided on the outer peripheral portion of the roller and the magnetic toner is held by this magnet, a necessary electric field cannot be obtained between the two rollers, and there is a problem that the toner supply property is deteriorated.

[0004]

Therefore, according to the invention of claim 1, a toner supply device for supplying a magnetic toner to a rotatable supply target roller having a developer on its outer peripheral portion is provided with a rotatable conductive toner supply device. A base, a non-conductive magnet layer that covers the outer periphery of the base, and a conductive coating layer that covers the outer periphery of the magnet layer and is electrically connected to the base, and holds magnetic toner on the outer periphery of the coating layer. It is composed of a magnetic roller and a power supply means for supplying a magnetic toner from the magnetic roller to the supply roller by applying a bias between the supply roller and the base body.

According to a second aspect of the invention, the toner supply device comprises a rotatable conductive base and a conductive magnet layer covering the outer circumference of the base, and the magnetic toner is provided on the outer circumference of the magnet layer. And a power supply means for supplying a magnetic toner from the magnetic roller to the supply target roller by applying a bias between the supply target roller and the base body.

[0006]

In the toner supply device of the first aspect, the distance between the base body of the magnetic roller having the conductive coating layer on the outer peripheral portion and the supply target roller is made by the non-conductive magnet body layer existing therebetween. Although separated, the base body and the coating layer are electrically connected to each other, so that a stable electric field is formed between the base body and the supply roller. Further, in the toner supply device of the second aspect, since the magnet layer is conductive, when a bias is applied between the base of the magnetic roller and the supply roller from the power supply means, the magnet body and the supply roller are separated from each other. A stable electric field is formed between them. Therefore, the magnetic toner is properly supplied by the stable electric field formed between the two rollers.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a cross section of a developing device accommodated in a copying machine, a printer or the like by electrophotography. This developing device 1
In, a storage chamber 4 for storing magnetic toner is formed between the lower housing 2 and the upper housing 3,
A blade 5 for agitating and supplying the toner is arranged in the storage chamber 4.

The toner supply roller 7 is disposed so as to face a passage 6 provided at a side portion of the storage chamber 4, and a regulation plate 8 made of a magnetic thin plate (stainless steel, nickel, or iron thin plate) is in pressure contact with the outer peripheral portion. . As shown in FIGS. 2 and 3, the toner supply roller 7 includes a support shaft 71 and a base 72 made of a conductive metal (for example, aluminum or brass) and mounted on the support shaft 71.
And a magnetic layer 73 made of a non-conductive material (for example, a ferrite magnet body or a rubber magnet body) that covers the periphery of the base body 72,
The base body 72 is connected to the first bias power source 9 having an AC power source and a DC power source, and the AC layer and the DC layer are superposed on each other. The first bias V1 is applied.

The magnet layer 73 is magnetized with a plurality of magnetic poles extending in the axial direction, with N poles and S poles arranged alternately and at equal intervals. The number of magnetized magnetic poles is preferably such that the magnetic toner supplied to the toner supply roller 7 is held substantially uniformly on the outer peripheral portion. For example, in the case of a toner supply roller having an outer diameter of 16 mm, 40 magnetic poles are used. Is suitable for each 9 ° center angle. The magnet layer 73 preferably has a thickness such that each magnetic pole can be magnetized to about 50 to 300 Gauss, and for example, about 1 mm is suitable.

The magnet layer 73 is formed into pellets by mixing, heating, kneading, extruding, crushing, for example, nylon: 10% by weight, ferrite powder: 80% by weight, carbon powder: 10% by weight. After that, this pellet-shaped processed product is put into a magnetic field-molded mold and magnetized at the same time as molding.

The thickness of the conductive layer 74 is preferably about 500 μm or less. The conductive layer 74 may be formed by coating or plating a conductive material such as chromium or zinc on the magnetic layer 73, or made of a conductive material such as carbon, nickel, chromium or zinc, or a resin containing carbon. A heat-shrinkable tube covered with the magnetic layer 73 may be used, and the one having high surface hardness, excellent smoothness, and capable of charging the surface of the magnetic toner is preferable.

The developing roller 10 is arranged parallel to the side of the toner supply roller 7 with a minute gap (for example, 1.5 mm or less) therebetween. The developing roller 10 is composed of a cylindrical fixed magnet body 11 having a plurality of magnetic poles on the outer peripheral portion thereof, and a rotary sleeve 11 which is externally mounted on the magnet body 11.
The sleeve 11 is connected to a second bias power source 13 having an output variable type DC power source, and a second bias V2 is applied.

The toner stirring member 16 is a toner supply roller 7.
Is disposed in the developer reservoir 15 formed below. A regulating plate 17 made of a magnetic material is provided above the toner stirring member 16, and the tip portion thereof is the developing roller 1.
It is made to face 0 at a predetermined minute interval.

In the developing device 1 having the above structure, the magnetic toner contained in the containing chamber 4 is mixed and stirred by the rotation of the blade 5. Further, a part of the magnetic toner is sent out from the passage 6 and supplied to the toner supply roller 7. The magnetic toner supplied to the toner supply roller 7 is held by the magnetic force of the magnet layer 73. Further, the magnetic toner moves in the direction of arrow b with the rotation of the toner supply roller 7, and is regulated by the regulation plate 8 at the position (contact portion) 18 in contact with the toner supply roller 7. Further, the toner contacting the regulation plate 8 is charged to a predetermined polarity, and a thin charged toner layer having a constant thickness is formed on the outer peripheral surface of the toner supply roller 7 passing through the contact portion 18.

At the contact portion 18 between the regulating plate 8 and the toner supply roller 7, the contact portion 1 is moved by the movement of the magnet layer 73.
The magnetic fields of N pole and S pole pass through 8 at a constant cycle. Therefore, if the regulating plate 8 is made of a magnetic material, the regulating plate 8 will have a frequency in accordance with the magnetic pole passage cycle in the normal direction of the toner supply roller 7 and the tangential direction of the toner supply roller 7 due to the moving magnetic field. Repeated force acts and vibrates minutely. Moreover, the vibration is further promoted by the alternating current applied to the toner supply roller 7. Therefore, even if a foreign matter enters between the regulation plate 8 and the toner supply roller 7, this foreign matter is immediately removed. Therefore, the toner supply failure does not continue. Further, even if there is some deviation in the mounting state of the regulation plate 8 to the toner supply roller 7, the thickness of the toner thin layer passing through the contact portion becomes constant. Further, the contact portion 18
The frequency of contact between the magnetic toner passing through and the regulation plate 8 increases, and the amount of charge of the magnetic toner increases.

Toner supply roller 7 which has passed the contact portion 18
The upper magnetic toner is conveyed in the direction of arrow b, and the replenishment / recovery area 19 where the toner supply roller 7 and the developing roller 10 face each other.
Then, the bias voltage difference between the first bias V1 and the second bias V2, the magnetic force difference between the magnet body 11 and the magnet body layer 73, and the development including the toner and the carrier formed on the outer peripheral portion of the developing roller 10. It is supplied to the developing roller 10 based on the scraping action of the agent. On the contrary, if excess toner is held on the outer peripheral portion of the developing roller 10, this is collected by the toner supply roller 7.

Further, a non-conductive magnet body layer 73 is interposed between the base 72 of the toner supply roller 7 connected to the power source 9 and the developing roller 10 to widen the distance between them. Since the conductive layer 74 is provided on the outer periphery of the layer 73, when the biases V1 and V2 are applied, a voltage is also applied to the conductive layer 74 through the base 72, and the conductive layer 74 and the developing roller 10 have a predetermined strength. The electric field of is stably formed,
Appropriate toner supply and recovery properties can be obtained.

The resistance value of the conductive layer 74 is the AC bias voltage (V) applied from the first bias power source 9.
_{As is} clear from FIG. 5 showing the relationship between _PP ) and the amount of replenishment toner, it is preferably 10 ¹² Ω · cm or less.

The magnetic toner held on the developing roller 10 in the replenishment / recovery area 19 is conveyed while being mixed with the developer held on the outer circumference of the developing roller 10, and the developing area 2
It is formed on the outer peripheral surface of the photoconductor 14 based on the potential difference between the second bias V2 and the surface potential of the photoconductor 14 in contact with the outer peripheral surface of the photoconductor 14 moving from the direction of arrow d at 0. Develop the electrostatic latent image. The magnetic toner and the developer that have passed through the developing area 20 are separated from the outer peripheral surface of the developing roller 10 at a portion facing the developer reservoir 15 and agitated in the developer reservoir 15, and then retained on the developing roller 10 again. Then, the developer which has been regulated to a fixed amount by the regulation unit 17 and which has passed through the tip of the regulation unit 17 is replenished with new toner in the replenishment / recovery region 19. Further, if the developing roller 10 holds excess toner, it is collected by the toner supply roller 7.

In the above description, the magnet layer 73 is made of a non-conductive magnetic material and the outer peripheral surface thereof is covered with the conductive layer 74. However, as shown in FIG. A conductive material may be included to make it conductive.

[0021]

As is apparent from the above description, in the magnetic roller of the toner supply device according to the present invention, the periphery of the substrate to which the bias is applied is the non-conductive magnet layer and the coating layer that is electrically connected to the substrate. , Or covered with a conductive magnet layer. Therefore, between the supplied roller to which the magnetic toner is supplied and the magnetic roller to supply the magnetic toner,
When a bias is applied between them, an electric field is appropriately formed, and the toner is smoothly supplied from the magnetic roller to the supply roller.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a developing device.

FIG. 2 is a perspective view of a toner supply roller.

FIG. 3 is a partial cross-sectional view of a toner supply roller.

FIG. 4 is a partial cross-sectional view of a toner supply roller according to another embodiment.

FIG. 5 is a diagram showing a relationship between an AC bias and a replenishment toner amount.

[Explanation of symbols]

1 ... Developing device, 7 ... Toner supply roller, 8 ... Regulating member,
Reference numeral 9 ... First bias power source, 10 ... Developing roller, 13 ... Second bias power source, 71 ... Spindle, 72 ... Base, 73 ... Magnet layer, 74 ... Covering layer.

Claims (2)

[Claims] 1. A toner supply device for supplying magnetic toner to a supply roller having a developer on its outer periphery, a rotatable conductive base, a non-conductive magnet layer covering the outer periphery of the base. And a magnetic coating layer which covers the outer periphery of the magnet layer and is electrically connected to the base, and holds a magnetic toner on the outer periphery of the coating layer and a bias between the supply roller and the base. A toner supply device comprising: a power supply unit that applies a magnetic toner from a magnetic roller to a supply roller. 2. A toner supply device for supplying a magnetic toner to a supply roller having a developer on its outer periphery, comprising a rotatable conductive base and a conductive magnet layer covering the outer periphery of the base. And a magnetic roller for holding magnetic toner on the outer circumference of the magnet layer, and a power supply means for supplying a magnetic toner from the magnetic roller to the supplied roller by applying a bias between the supplied roller and the base body. A toner supply roller characterized in that