JPS60203971A - Magnetic one-component developing method - Google Patents

Abstract

PURPOSE:To improve image quality and developing efficiency by controlling the amt. of the toner to be stuck onto a developing sleeve under rotation and forming the main developing pole of a magnet of repulsive magnetic poles of the same pole. CONSTITUTION:A thin layer of a one-component type magnetic toner controlled to 3-6mg/cm with a control blade 7 is formed on a sleelve 10 rotating around a fixed magnet 5. The main developing poles of the magnet 5 are both formed of repulsive poles of the same pole such as N pole and therefore the thin layer toner on the sleele 10 scatters magnetically in a developing region and contacts slightly a photosensitive drum 1. Generation of defective reproduction of low density lines, thickening of lines, fringing around the lines, etc. is obviated by the same pole repulsion of the main developing poles and the required scattering of the thin layer toner, by which image quality as well as developing efficiency are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic-component development method for developing electrostatic latent images using a-component magnetic toner.

BACKGROUND ART Conventionally, in electronic copying machines and the like, a device as shown in FIG. 1 has generally been used as a one-component developing device for developing an electrostatic latent image on an image carrier using a -component magnetic toner. It is used. In FIG. 1, ] is a photoconductive drum capable of holding an electrostatic latent image 2, and a developing device is disposed close to and facing the photoconductive drum 1. In FIG.

The developing device includes a pumper 3 for containing -component magnetic toner 4, an agitator 8 for agitating and transporting the toner 4, and a plurality of magnetic poles of different polarities that are fixed so as not to rotate inside and are arranged alternately. It has a magnet roll 5, a non-magnetic cylindrical developing sleeve 6 rotatably fixed around the magnet roll 5, and a developer sleeve 7 for regulating the amount of toner on the sleeve 6. - The agitator 8 and the developing sleeve 6% regulating grade 7 are arranged in the flopper 3, and the developing sleeve 6 is arranged at regular intervals on the upper part of the developing sleeve 6. A bias voltage is applied by an insulator source 9 placed close to the conductive drum 1.The one-component magnetic toner 4 stored in the hopper 3 is agitated by an agitator g. It is held on the surface of the developing sleeve 6 by the magnetic force of the magnet roll 5, and as the developing sleeve 60 rotates, it is sent to the developing area where the photoconductive drum 1 and the developing sleeve 6 face each other. The electrostatic latent image 2 is developed.

Above Q:) High resistance) Su-(10”~10
In the induction type magnetic component development method using ``l; I-cm'' or the charge exchange type high resistance magnetic component development method.

Normally, the amount of toner adhesion on the developing three 1 is about 10 m9 to 2
0 */c-J, and for this reason, as a problem in image quality, (α) the density of the copied image is 7.
1, the density of the copy image does not decrease linearly, and the density of the copied image decreases rapidly in the low density area of the original density. So-called low density line reproducibility is poor.

Thickness of tbl line.

(There was a fringe phenomenon in which spots were attached around the C1 line.

In order to solve the above-mentioned problems, attempts have been made to make the toner layer on the developing sleeve even thinner, but this also causes a decrease in development efficiency, so it has not been possible to simultaneously solve the above-mentioned image quality problems. Ta.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems in image quality and development efficiency. It is an object of the present invention to provide a magnetic component developing method that is free from image quality problems such as peripheral fringe phenomena and has sufficient development efficiency.

Structure of the Invention The magnetic component and component development method according to the present invention is a one-component magnetic toner composed of insulating particles having a nitrogen-containing polar functional group, etc., and an external additive having an electron-attracting polarity. In a developing method that utilizes the electric charge generated by charge exchange between the polar groups of the -component magnetic toner, the amount of toner adhesion on the developing sleeve is regulated to 3 to 6 Da/d, and the amount of toner adhering to the developing area is In order to ensure sufficient charge exchange, the developing main pole of the magnet roll (near the image carrier) is

(Magnetic poles placed in opposing positions, that is, in the development area)
By using the same-polarity repelling magnetic pole (i?%), the amount of toner adhering to the developing sleeve can be reduced, and by using a repelling magnetic pole as the main developing pole, toner flying in the developing nip can be reduced. By making it easy to generate and exchange charges, problems with image quality can be solved and development efficiency can be fully satisfied.

Operation and aspects of the invention The operation and various aspects of the invention will be explained below with reference to the drawings. For convenience of explanation, parts having the same functions as those of the conventional device shown in FIG.

First, as shown in FIG. 2, the single layer of developer (-component magnetic toner) used in the method of the present invention is applied to at least the surface layer of insulating particles 11 made of magnetic powder 12 bound with binder resin 13. .

External additive particles 14 having an electron-withdrawing polar group are attached or embedded therein, and the binder resin 13 has a functional group that can cause charge exchange in an electric field with the electron-attracting polar group of the external additive particle 14. ,.

For example, it is necessary to have a nitrogen-containing functional group.

FIG. 2 shows an example of a developer comprising insulating particles 11 having amino groups -N (Hj)2 and externally added carbon black 14 having carboxyl groups -COOH'i.

As monomer components for introducing, for example, a confining polar functional group into the insulating particles 11 (strictly speaking, the binder resin),
N-methylaminoethyl acrylate, N-ethylaminoethyl acrylate), N,N-dimethylaminoethyl acrylate), N,N-diethylaminoethyl acrylate), N,N-dibutylaminoethyl acrylate ), N
, N-diethylaminopropyl acrylate and other substituted amino group-containing acrylates.

aminoethyl methacrylate), N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, N-methylaminoethyl methacrylate, N-ethylaminoethyl acrylate), 2-N,N
-dicyclohexylaminoethyl methacrylate, N.

Substituted amino group-containing methacrylates such as N-dibutylaminoethyl methacrylate, 2-phenylaminoethyl methacrylate), 2-dibenzylaminoethyl methacrylate, aminostyrene, dimethylaminoethylstyrene, N-methylaminoethylstyrene, dimethylamino Aminostyrenes such as ethoxystyrene, allylamines such as acrylamine and allylmethylamine, vinylpyridines such as SN-vinylpyridine%2-vinyl-5-methylpyridine, vinylamines, vinylquinolines and allylquinolines, acrylamides , N-vinylamides, etc. can be used.

Examples of external additives include inorganic oxides such as metal oxides, inorganic halides, and inorganic salts that exhibit a pH≦6 when dispersed in ion-exchanged water.

Carbon or the like can be used. These include silane coupling agents, titanate coupling agents,
Higher fatty acids and their derivatives.

It may be used after the surface is organically treated with higher alcohol or the like. Further, it may be combined with other inorganic substances. Furthermore, fine resin particles prepared by emulsion polymerization or suspension polymerization or obtained by a pulverization method, higher fatty acids and their derivatives, organic oxides, organic halides, organic salts, etc. can also be used. Among them, pH≦4 and -COOH group, -O
H group.

It is preferable to use inorganic fine particles having at least one type of polar functional group among halogens, since the binding performance and development characteristics as a developer can be easily controlled. Preferred are acidic carbon black, fine silica powder, fine titanium oxide powder, etc., and those having a particle size of 1 μm or less, particularly 0.1 μm or less are conveniently used.

FIG. 3 shows a schematic configuration of an example of a developing device using the magnetic component developing method according to the present invention, which is similar to the conventional device shown in FIG. 1 except for the arrangement of the magnetic poles of the magnet roll 5. In this apparatus, as shown in FIG. 3, two magnetic poles (N+, Nz) of the same polarity are arranged as the main developing pole 10 of the magnet roll 5 so that they repel the same polarity. By making the main developing pole of the magnet roll 5 homopolar repulsive in this way, the one-component magnetic toner stands up on the surface of the sleeve 6 in the developing nip, thereby increasing the flying force of the toner and improving the developing efficiency. will improve.

Regarding the above image quality problem, the amount of toner adhering on the developing sleeve is regulated to 3 to 64 kg, and the toner is in a non-contact state or in slight contact with the image carrier when the developing sleeve is not rotating, preferably about 0. By setting the interval to .3 to 0.5 u, the electric field strength becomes stronger and the toner rises higher at the entrance of the development area depending on the direction of rotation of the development sleeve for low density line reproducibility. Therefore, the scavenging force after development on the exit side of the development area is weakened, which improves the performance.

In addition, regarding line thickening and fringing phenomena around the line, it is necessary to weaken the edge effect of the latent image of the line and to prevent development on the opposite polarity side by making the toner on the developing sleeve an even thinner gold layer. Improved by on the other hand.

Because the toner is magnetically ejected for development, there is a large interaction between the toners in the developing nip. Charge exchange is sufficient and sufficient development is achieved.

By the way, as mentioned above, if the magnetic force of the same-polarity repelling pole of the main developing pole is equal on the development area entrance side and the development area exit side, the toner rise at the development area entrance side will depend on the rotational direction of the development sleeve. 9 becomes high, and as a result, toner jamming is likely to occur and uneven copying is likely to occur. Therefore, as shown in FIG. 4, it is preferable to set the magnetic force distribution of the same-pole repelling poles so that the developing area exit side (N,) is higher than the developing area entrance side (N1). 300-600 Gauss (Gawzs) on side (N1) - exit side (N2)
It is preferable to set it to 600 to 1200 cows.

Although we have described an example in which a homopolar repelling pole is placed on the developing main pole of a magnet roll as a means for magnetically flying toner, it is also possible to use two magnetic rolls to form a repelling pole and magnetically flying toner. A similar effect can also be obtained by

Example An embodiment of the present invention will be described below.

Example 1 Using a charge exchange type high-resistance induction-component developing toner, a homopolar repulsion magnet was used to increase the magnetic force (Nl) on the entrance side of the development area.
'k 500 gauss, exit side magnetic force <N,) is 1000 gauss, and using a magnet roll with angle #(θ) between two magnetic poles of 25°, the amount of toner adhering to the developing sleeve should be 4 da. When developed under the following conditions, the resulting copies had no image quality problems such as poor reproduction of low-density lines, thick lines, or fringing around the lines, and sufficient development efficiency was obtained. Ta.

Example 2 A charge exchange type high-resistance rust conduction-component developing toner was used, the amount of toner adhering to the developing sleeve was regulated to 4 to 400 yen, the main developing pole was made a homopolar repellent pole, and as shown in the fifth example. , development entrance side (
The same results as in Example 1 were obtained even when using a magnet roll with N1) 800 Gauss, CNv) Boo Gauss on the developing outlet side, and an interpolar angle (θ) of 25°.

Effects of the Invention As described above, in the magnetic component developing method according to the present invention,
- It utilizes the charge generated by charge exchange between the polar groups of the component-based magnetic toner, and regulates the amount of toner adhesion on the developing sleeve to 3 to 6 74 points, and the main developing pole is made of homopolar repulsion. This solves image quality problems such as poor reproduction of low-density lines, thick lines, and fringing around the lines, and also prevents toner from flying in the developing nip and facilitates charge exchange. , the development efficiency is also sufficiently satisfactory.

Furthermore, the amount of toner adhering to the developing sleeve should be reduced by 3 to 6 my
/crA, and the toner is magnetically ejected, so capri is not generated in the background area of the copy, and there is no need to scavenge the background area in an alternating electric field, so there is no fogging caused by DC bias and high Provides high quality image quality.

In addition, by increasing the magnetic force gradient of the main developing pole on the exit side of the developing area, scavenging on the exit side of the developing nip is strong, eliminating the toner scattering seen on the trail side of the line1. A measure has been taken to provide a magnet at the very bottom side of the developing main body, but this method has the advantage that this is not necessary.

[Brief explanation of the drawing]

The first factor is a schematic explanatory diagram of a conventional one-component developing device. FIG. 2 is a schematic diagram showing an example of a charge exchange type high-resistance induction-component magnetic toner used in the present invention, FIG. 3 is a schematic diagram showing an example of a developing device for carrying out the method of the present invention, FIG. 5 is a graph showing an example of the magnetic force distribution of homopolar repelling poles in the present invention. 1... Photoconductive drum, 2... Electrostatic latent image, 4...
-component magnetic toner, 5... magnet roll, 6...
Developing sleeve, 7 Regulating blade, 8 Agitator 110 Main developing pole, 11 Insulating particles. 14...External additive particles. Figure 1. > 2 Eyj. Figure 49Figure 5

Claims (1)

[Scope of Claims] 1. A developing sleeve that uses a one-component magnetic toner consisting of insulating particles having a polar functional group and an external additive having a polar group and is rotatably pivoted around a fixed magnet. The above-mentioned -component magnetic toner is supported and conveyed on the surface of the
In a magnetic component development method for developing an electrostatic latent image on an image carrier disposed in close proximity to the developing sleeve 1, the amount of toner adhering on the developing sleeve is regulated to 3 to 6 cm/c111, and . A magnetic component development method, characterized in that the main development pole of the magnet is a homopolar repelling magnetic pole, and the one-component magnetic toner is magnetically ejected in the development area. 2. The magnetic component developing method according to claim 1, wherein the magnetic force of the same-pole repelling poles is set to be higher on the exit side of the development area than on the entrance side of the development area. & The magnetic force of the same-polarity repelling pole is 300 on the entrance side of the development area.
~60ρ Gauss, 600~+200 on the exit side of the developing area
2. The magnetic component developing method according to claim 2, wherein the t-% characteristic is Gaussian.