JPS61185754A - Developing method - Google Patents

Abstract

PURPOSE:To perform the development without staining and controlling the toner density by replenishing a developer consisting of a magnetic toner and a magnetic carrier having a smaller particle size to a developing roll after magnetic particles having a large particle size are stuck to the peripheral surface of the developing roll by a magnetic force in case of the electrophotographic development. CONSTITUTION:Such quantity of magnetic particles having a large particle size are stuck preliminarily to the surface of the sleeve 2 of the developing roll by a magnet 3 fixed in the sleeve 2 that all of the surface of the sleeve 2 is covered with these magnetic particles. A developer 5 where the magnetic toner (8-20mum volume average particle size) and the magnetic carrier (1-20mum volume average particle size) having a relatively small particle size are mixed and the triboelectrification change is given sufficiently to the magnetic toner preliminarily by mixing and agitating is supplied to a hopper to perform the development. The mixture where 2-10pts.wt. magnetic carrier is mixed in 100pts.wt. magnetic toner is used to perform the developer where it is unnecessary to control the toner density of the developer 5 and since the carrier is consumed while sticking to an electrostatic latent image together with the toner the flocculation and the staining are hardly generated in the development.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developing method in an image forming apparatus such as an electrophotographic copying apparatus or a blink using electrophotographic technology.

[Prior art and its problems]

2. Description of the Related Art Conventionally, dry developing methods are known as a one-component developing method that uses only magnetic toner as a developer, and a two-component developing method that uses a mixture of a non-magnetic toner and a magnetic carrier as a developer. Although the -component development method does not require a magnetic carrier and does not require toner concentration control, it has the disadvantage that L-toner tends to aggregate. In addition, the thickness of the developer layer conveyed from the developing roll to the developing section and the distance between the photoreceptor and the developing roll must be set to extremely small values of around 0.2 mm, which requires extremely high processing speed. Accuracy is required. -What is the two-component development method?

It is necessary to control the toner concentration in the developer.

For this reason, an expensive toner density control device must be used.

As a solution to these problems, a method is known in which a developer is used in which a small amount of magnetic carrier is mixed into magnetic toner. However, this method has the drawback that as the toner is consumed, the toner density on the developing roll decreases and the image density changes.

For this reason, a method has been proposed in which a certain amount of magnetic carrier is deposited on the developing roll and then magnetic toner is replenished. According to this method, there are problems such as toner aggregation that occurs in the -component development method and the need for high processing accuracy. do not have.

In this method, as described above, a certain amount of large particle size magnetic carrier is deposited on the developing roll.

This method replenishes only magnetic toner. After replenishment.

Frictional charges are added to the magnetic toner by the regulating force of the regulating plate and the agitation force generated by the rotation of the developing roll, but the friction of the magnetic toner on the developing sleeve immediately after the developer is added The electric charge is small. Therefore, the adsorption force of the magnetic toner to the large particle size magnetic carrier depends mostly on the magnetic force acting on the magnetic toner from the magnet in the developing roll. For this reason, magnetic toner particles that contain a small amount of magnetic material have weak adsorption to large-particle carriers, and therefore, toner easily adheres to low-potential areas of the photoreceptor, especially immediately after developer is added. However, it has the disadvantage that scumming tends to occur.

[Object of the Invention] In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide a developing method that imparts a sufficient lV triboelectric charge to a magnetic toner and is free from scumming.

[Summary of the Invention] According to the present invention, the above object is achieved by attaching a magnetic trochanter around a developing roll by magnetic force, and thereafter.

The present invention provides a developing method characterized in that development is performed by replenishing a developing roll with a developer consisting of magnetic toner and magnetic carrier.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

The figure is a schematic configuration diagram of a developing device used in the present invention.

A developing device is installed close to the photoreceptor 1 which rotates in the direction of the arrow in the figure. The developing device includes a non-magnetic developing sleeve 2 that is rotatably installed in the direction of the arrow and a developing roll 4 that has four permanent magnets 3 inside. It is composed of a pumper 6 that stores the developer 5, and a regulating plate 7 that regulates the layer thickness of the developer conveyed on the sleeve 2.

First, an amount that can cover almost the entire surface of the developing sleeve 2, that is, for example, about 10 to 30 g if the developing sleeve 2 has a diameter of 20 mm and a length of about 300 mm, and A magnetic carrier having a larger particle size than the magnetic carrier in the developer to be added later is attached. However, if the distance between the developing sleeve 2 and the regulating plate 7 is set wide, a larger amount of large-grained magnetic carrier is required, and some large-grained magnetic carriers accumulate near the regulating plate 7. You may add as much as you can. However, if the input amount is too large, replenishment of the developer 5 to the developing sleeve 2 will be inhibited.

In this way, after attaching a small amount of large particle size magnetic carrier to the developing sleeve 2 in advance, a magnetic l-ner (volume average particle size 8 to 20 μm) and a comparatively small particle size magnetic carrier are placed in the hopper 6. A developer 5 consisting of a mixture of carriers (volume average particle diameter of 1 to 20 μm), which has already been mixed and stirred and has been given a sufficient triboelectric charge to the magnetic toner, is introduced.

The amount of small particle size magnetic carrier in the developer 5 may be extremely small compared to the amount of magnetic toner. for example.

When the volume average particle size of the magnetic carrier is small, about 5 μm, compared to the magnetic toner (with a volume average particle size of 10 μm), the mixing ratio of the magnetic toner and the magnetic carrier is as follows: It is 2 to 10 parts by weight long, and when the volume average particle size of the magnetic carrier is small, 5 μm or less, the total surface area is larger than that of a magnetic carrier with a particle size of 5 μm.

The mixing ratio of both is magnetic toner (particle size 10 μITI) 10
0 parts by weight, magnetic carrier (particle size 5 μm or less) is 2 parts by weight.
It may be less than ~10 parts by weight. However, if the particle size is too small, it becomes difficult to mix uniformly with the magnetic toner, so it is necessary to limit the particle size to about several tenths of a micrometer.

In this way, when the developer 5 in which magnetic toner and small particle size magnetic carrier are mixed and stirred is put into the hopper 6, the developer 5 is pre-injected by the magnetic force of the magnet 3 fixedly installed in the developing sleeve 2. It is adsorbed by the large particle size magnetic carrier. As the developing sleeve 2 rotates, the adsorbed developer 5 is sent along with large particle diameter magnetic carriers to a position facing the regulating plate 7 +1), is regulated to a certain amount of brush height, and is further transported to the developing area. IIQ is sent. In this development area, the magnetic toner in the developer adheres to the electrostatic latent image on the photoreceptor 1 and is consumed, and at the same time, a portion of the small-sized magnetic carrier is consumed while adhering to the magnetic toner. Ru. Note that the consumption rate of the small particle size magnetic carrier here is the same as the initial rate when magnetic toner and small particle size magnetic carrier are mixed to form a developer due to the selection of the magnetic properties of the magnetic carrier. It is set so that Therefore,
It is not necessary to keep the mixing ratio of magnetic toner and small particle size magnetic carrier constant.

In addition, in order to increase the triboelectric charging efficiency of small particle-sized magnetic carriers, organic substances (e.g., acrylic or polyester resins) or inorganic substances (e.g., titanium-based or silane-based compounds) are added to the surface of the small-particle carriers. It may be coated.

〔Effect of the invention〕

As explained in detail above, according to the developing method of the present invention, a developer containing magnetic toner that has been sufficiently triboelectrically charged is charged into the developing roll to which magnetic particles have already adhered. Can prevent dirt. Furthermore, the assembly accuracy of the distance between the photoconductor and the developing roll can be relaxed, and
No toner concentration control is required and toner aggregation is less likely to occur.

[Brief explanation of drawings]

The figure is a schematic configuration diagram of a developing device used in the present invention. 1... Photoreceptor. 2...Developing sleeve. 3...Permanent magnet. 4.・・Presence (Elephant roll. 5...Developer. 6...Hopper. 7...Regulation board.

Claims (1)

[Claims] A developing method characterized by attaching magnetic particles around a developing roll by magnetic force, and then replenishing the developing roll with a developer consisting of magnetic toner and magnetic carrier to perform development.