JPH02228545A - Evaluation of carrier - Google Patents

Abstract

PURPOSE:To achieve an evaluation of an adhering characteristic of a carrier with respect to a photosensitive body more accurately by arranging a dielectric body stuck together with a dielectric body, a false developing roller and a carrier removing means. CONSTITUTION:An electric charge is injected into a carrier 5 by a potential difference Vb between a false developing roller 20 and a conductor 1 so that a specified amount of the carrier 5 adheres to the surface of a dielectric body 2. When the carrier adhering to the surface of the dielectric body 2 is removed, the carrier tending to escape the electric charge easily is removed by a carrier removing means 9 with the electric charge left on the surface of the dielectric body 2 while those tending to hold the electric charge easily is removed 9 with the electric charge held. Then when a potential difference Vb between the roller 20 and the conductor 1 is constant, an adhering characteristic of the carrier with respect to a photosensitive body is evaluated to be better all for the larger potential difference between the surface of the dielectric body 2 and the conductor 1 due to a residual electric charge on the surface of the dielectric body 2.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a method for evaluating two-component developers used in electrophotographic recording devices, and in particular to a method for evaluating the likelihood of carrier adhesion failure in which carrier adheres to a photoreceptor. The purpose of the present invention is to provide a method for accurately evaluating the likelihood of adhesion failure in a way similar to the actual usage conditions of an electrophotographic recording device. a process of rotating the pseudo developing roller to convey the carrier;
A process of applying a voltage between the pseudo-developing roller and the conductive material to make the carrier adhere to the dielectric surface, a process of removing the carrier adhering to the dielectric surface, and a process of removing the carrier from the dielectric surface due to the residual charge on the dielectric surface. The process includes the process of measuring the potential difference V between the conductor, and the relationship between the potential difference Vb between the pseudo developing roller and the conductor and the potential difference between the dielectric surface and the conductor due to residual charge on the dielectric surface. It is characterized by evaluating the adhesion characteristics of the photoreceptor to the photoreceptor.

[Industrial application field]

The present invention relates to a method for evaluating a two-component developer used in an electrophotographic recording device, and more particularly to a method for evaluating the occurrence of carrier adhesion failure in which carrier adheres to a photoreceptor.

In recent years, printers used as output devices for electronic computers are desired to have high resolution and high speed, and electrophotographic printers are attracting attention. The main type of developer used in electrophotographic printers is a two-component developer consisting of toner and carrier. The toner forms a visible image, and the carrier charges and transports the toner, holding it on the developing roller. It is something that will be done. When this carrier adheres to the photoreceptor due to electrostatic force, the toner around the carrier is not transferred to the recording paper, resulting in white spots in the output image.

In evaluating developers, the difficulty of causing this carrier adhesion disorder is an important item.

[Conventional technology]

Causes of carrier adhesion failure include those resulting from the configuration of the printer device and those resulting from the electromagnetic characteristics of the developer. Examples of factors that are caused by the configuration of the printer device include the moving speed ratio of the photoreceptor 22 and the sleeve 3, the depth of contact between the magnetic brush 23 and the photoreceptor 22, and the position of the magnetic pole of the mag roll 4. and strength.

The object of the present invention is carrier adhesion problems caused by the electromagnetic properties of developers, especially carriers. To explain using FIG. 4, the carrier contacts the toner, gives it an electric charge, and also acquires an opposite electric charge and attracts the toner. When the charged toner adheres to the latent image area of the photoreceptor 22 due to development, the reverse charge remaining in the carrier flows into the sleeve 3 through the connected carriers. However, if this reverse charge remains on the carrier, the boundary portion of the latent image on the photoreceptor 22 (
Due to the strong electrostatic field acting on the edges, carriers with residual charges may adhere to the vicinity of the edges.

Carriers that tend to retain charge tend to cause carrier adhesion problems. Conventionally, the conductivity of the carrier has been used to evaluate the adhesion characteristics of the carrier to the photoreceptor. The higher the conductivity, the less likely carrier adhesion problems will occur due to charge movement. However, if the conductivity is too high, when the magnetic brush comes into contact with the surface of the photoreceptor, the charge in the latent image portion will be removed and the output image will deteriorate. Therefore, the electrical conductivity needs to be an appropriate value, but as far as the adhesion characteristics of the carrier to the photoreceptor are concerned, the higher the electrical conductivity of the carrier, the better.

FIG. 5 shows a method for measuring the conductivity of carriers. The main electrode 13 and the shield electrode work 2 insulated from the main electrode form a container, into which the carrier 5 is placed under certain filling conditions, and the upper electrode 11 is placed on top of this with a certain load to apply a constant voltage to the picture electrode. (2) is applied, and the electric current (2) flowing between the electrodes is measured to determine the conductivity of the carrier 5.

[Problem to be solved by the invention]

However, the evaluation of the adhesion characteristics to the photoreceptor based on the conductivity of the carrier does not necessarily match the actual adhesion characteristics to the photoreceptor.
The ease with which carrier charges remain depends not only on conductivity but also on
It varies depending on the shape of the carrier and the conditions of the development process. Conventionally, in order to evaluate the adhesion characteristics of carriers to photoreceptors,
In fact, an evaluation method is used in which a predetermined test pattern is output from a printer and the amount of carrier adhesion is determined by counting the white spots in the test pattern. In addition to being time-consuming, it is not clear whether the carrier adhesion failure is actually due to the electromagnetic characteristics of the carrier or the configuration of the printer device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for accurately evaluating the likelihood of carrier adhesion failure by approaching the actual usage conditions of electronic and photographic recording devices.

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention. In figure A,
The mag roll 4 and the sleeve 3 are used as a developing roller of an electrophotographic printer, and are a pseudo developing roller 20.
A magnetic brush consisting only of carriers is formed on top. The blade 6 regulates the height of the magnetic brush.

Further, a dielectric material 2 is pasted on the conductor 1, and a pseudo developing roller 20 is arranged to perform development on the dielectric material 2. It is something.

The carrier removing means 9 shown in FIG.
0 is for measuring the potential difference (2) between the surface of the dielectric 2 and the conductor 1 due to residual charges on the surface of the dielectric 2.

[Effect]

Charge is injected into the carrier 5 due to the potential difference V between the pseudo developing roller 20 and the conductor 1, and a predetermined amount of the carrier 5 adheres to the surface of the dielectric 2. When removing carriers attached to the surface of the dielectric 2, carriers that easily release charges are removed while leaving their charges on the surface of the dielectric 2, and carriers that easily retain charges are removed while retaining their charges. Therefore, when the potential difference V between the pseudo developing roller 20 and the conductor 1 is constant, the larger the potential difference V between the surface of the dielectric 2 and the conductor 1 due to the residual charge on the surface of the dielectric 2, the more the carrier will adhere to the photoreceptor. The characteristics are evaluated to be good.

〔Example〕

FIG. 2 is a configuration diagram of an embodiment of the present invention. In the figure, the conductor 1 is an aluminum drum, and the drum diameter and rotation speed are preferably the same as those of a photoreceptor in a printer.A dielectric film 2 is pasted on the surface of the aluminum drum 1. Furthermore, the developing roller 20 is one that is used in an actual printer, and the size, rotational speed, number of magnetic poles, magnitude of magnetic force, developing gap, etc. are made in the same environment as in the actual printer.

For example, the diameter of the aluminum drum 1 is 141 txa and the circumferential speed is 120 mm/s, and the diameter of the sleeve 3 is 32 mm and the circumferential speed is 240 nm/s. It is assumed that the mag roll 4 has six magnetic poles and does not rotate. Further, the constant voltage power supply 7 has its positive electrode connected to the aluminum drum l and its negative electrode connected to the sleeve 3, and applies a bias voltage Vs between the developing roller 20 and the aluminum drum 1. Further, the aluminum drum L side is grounded.

First, the aluminum drum 1 and the sleeve 3 are rotated in the direction of the arrow, and a bias voltage Vb of, for example, 600 V is applied between the aluminum drum 1 and the sleeve 3 by the constant voltage power supply 7.

Charges are injected into the carriers by applying a voltage, and the carriers adhere to the dielectric film 2. The bias voltage is turned off before the aluminum drum 1 makes one revolution.

Subsequently, nitrogen gas is sprayed with an air gun to blow away the carriers attached to the dielectric film 2. and,
A surface potential measurement probe (not shown) is installed at a position about two cabinets away from the dielectric film 2, and the aluminum drum l is slowly rotated at a circumferential speed of 12 mm/s.The zero surface potential is output to an X-Y plotter (not shown). The average surface potential v8 is determined from the results.

Using the bias voltage (■) applied between the developing roller 20 and the aluminum drum 1 as a parameter, carry out the measurement in (8). Graph the electric charge potential Vf.

FIG. 3 is a graph showing the measurement results of four types of sample carriers. In the figure, as long as the bias voltage ■ is small, there is no difference in the residual charge potential v3 for all four types.However, as the bias voltage increases, samples A and B have larger ■, compared to samples C and D. There is. Therefore, it can be evaluated that Samples A and B allow the charge in the carrier to escape more easily to the surface of the dielectric film 2, and have better adhesion characteristics of the carrier to the photoreceptor.

〔Effect of the invention〕

As described above, according to the present invention, the measurement is performed under almost the same developing conditions as in an actual electrophotographic printer, making it possible to more accurately evaluate the adhesion characteristics of the carrier to the photoreceptor.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanation of the present invention. FIG. 2 is a configuration diagram of an embodiment of the present invention. FIG. 3 is a graph showing measurement results according to this embodiment. FIG. 4 is an explanatory diagram of a magnetic brush. FIG. 3 is a diagram showing a method for measuring conductivity. In the figure, 1... Conductor (aluminum drum) 2... Dielectric material (dielectric film) 3... Sleeve 4... Magroll 5... Carrier 9... Carrier removal means 10... Surface potential measuring device 20... Pseudo developing roller (developing roller) Book reading - Sanskrit stamp groove drawing 2 posts Vb (V) This implementation Italian 1135 row 1 fixed fruit %3 Σ production air bran. Illustration of Hinaro's illustration of conductive conduction and foot birthmarks.

Claims (1)

[Claims] A conductor (1) having a dielectric (2) pasted thereon, and a pseudo developing roller (20) disposed at a predetermined interval on the surface of the dielectric (2), the pseudo developing roller (20) ) to transport the carrier, and the voltage V_b between the pseudo developing roller (20) and the conductor (1).
A process of applying carriers to the surface of the dielectric (2), a process of removing the carriers attached to the surface of the dielectric (2), and a process of removing carriers attached to the surface of the dielectric (2) due to residual charges on the surface of the dielectric (2). and a step of measuring the potential difference V_s between the pseudo developing roller (20) and the conductor (1),
_b and the residual charge on the surface of dielectric (2)
) A method for evaluating a carrier, which comprises evaluating the adhesion characteristics of the carrier to a photoreceptor based on the relationship between the potential difference V_s between the surface and the conductor (1).