JPH02228544A - Evaluation of carrier - Google Patents

Abstract

PURPOSE:To achieve more accurate evaluation of an adhering characteristic of a carrier to a photosensitive body by arranging a conductor stuck together with a dielectric body and a false developing roller. CONSTITUTION:When an electric charge is injected into a carrier 5 by a potential difference Vb between a false developing roller 20 and a conductor 1, the carrier 5 adheres to the surface of the dielectric body 2. An adhesion value of the carrier 5 to the surface of the dielectric body 2 is M1-M2. A potential difference between the surface of the dielectric body 2 and the roller 20 is Vb-Vs as given when the carrier 5 adheres to the dielectric body 2. Then, with the potential difference Vb as parameter, adhesion values M1 and M2 and the potential difference Vs are measured to determine a relationship between the potential difference Vb-Vs between the surface of the dielectric body 2 and the roller 20 and a carrier adhesion value per unit area. Then, carrier adhesion values per unit area are compared as obtained when the potential difference between the surface of the dielectric body 2 and the roller 20 is constant and thus, the carrier with the less adhesion value is evaluated to be a better adhering characteristic thereof to the photosensitive body.

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 and applying a voltage V between the pseudo developing roller and the conductor.

a process in which carriers are attached to the dielectric surface by applying
The method includes a process of measuring the amount of carriers attached to the dielectric surface, and a process of measuring the potential difference (5) between the dielectric surface and the conductor due to the residual charge on the dielectric surface after removing the attached carriers. The potential difference between the pseudo developing rollers ■, -■,
It is characterized by evaluating the adhesion characteristics of the carrier to the photoreceptor based on the relationship with the amount of adhering carrier per unit area.

[Industrial Field of Application] The present invention relates to a method of evaluating a two-component developer used in an electrophotographic recording device, and more particularly to a method of evaluating the likelihood 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 easier the charge is to move, which makes carrier adhesion less likely to occur. 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 area 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 12 insulated from the main electrode 13 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. is applied, and the electric current ■ flowing between the electrodes is measured to determine the conductivity of the carrier 5.

(Problems 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, development process conditions, etc. Conventionally, in order to evaluate the adhesion characteristics of the carrier to the photoconductor, an evaluation method has been used in which a predetermined test pattern is output from an actual printer and the amount of carrier adhesion is determined by counting the white spots in the test pattern. Evaluating the adhesion characteristics of the carrier to the photoreceptor from the above is time-consuming, and 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 operating conditions of an electrophotographic recording apparatus.

[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 2 is attached to the conductor 1, and a pseudo developing roller 20 is arranged so as to perform development on the surface of the dielectric 2. A constant voltage power supply 7 applies a voltage Vb between the pseudo developing roller 20 and the conductor 1.
is applied.

The figure B shows the process in which the carrier amount measuring means 8 measures the mass M of the dielectric 2 to which carriers have adhered, and the figure C shows the process in which the carrier removing means 9 removes carriers from the surface of the dielectric 2. The quantity measuring means 8 is the mass M2 of only the dielectric material 2.
FIG. 5E explains the process in which the surface potential measuring means 10 measures the potential difference 5 between the surface of the dielectric 2 and the conductor 1.

[Effect]

When a charge is injected into the carrier 5 due to the potential difference 5 between the pseudo developing roller 20 and the conductor 1, the carrier 5 becomes the dielectric 2.
Adheres to surfaces. The amount of carriers attached to the surface of the dielectric 2 is M,
-M2. Further, when the carrier 5 adheres to the dielectric 2, the potential difference between the surface of the dielectric 2 and the pseudo developing roller 20 is V and -V.

Using 5 as a parameter, measure M+, M2 and 1, and measure the potential difference V between the surface of the dielectric 2 and the pseudo developing roller 20,
-V and the amount of carrier attached per unit area is determined. The amount of carrier adhesion per unit area when the potential difference between the surface of the dielectric 2 and the pseudo developing roller 20 is constant is compared, and the carrier with a smaller amount of adhesion is evaluated as having good adhesion characteristics to the photoreceptor.

〔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 the photoreceptor of the printer. A dielectric film 2 is attached to a part of the circumference of an aluminum drum 1.

Further, the mag roll 4 and the sleeve 3 are those used in an actual printer, and the size, rotational speed, number of magnetic poles, magnitude of magnetic force, development gap, etc. are made in the same environment as in the actual printer. For example, if the diameter of aluminum drum 1 is 14
7 cylinders, the circumferential speed is 120 M/S, the diameter of the sleeve 3 is 32 mm, and the circumferential speed is 240+++ m/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 a positive electrode connected to the aluminum drum 1, a negative electrode connected to the sleeve 3, and the aluminum drum I side grounded.

First, the developing roller 20 and the aluminum drum 1 are rotated in the direction of the arrow, and before the leading edge of the dielectric film 2 reaches the developing position of the developing roller 20, the constant voltage power supply 7 is applied to connect the developing roller 20 and the aluminum drum 1. Voltage ■5 For example 600■
Apply. Charges are injected into the carriers by applying a voltage, and the carriers adhere to the surface of the dielectric film 2. After the aluminum drum 1 rotates and the development position reaches the end of the dielectric film 2, the applied voltage is turned off.

Next, the dielectric film 2 with the carrier attached thereto is peeled off from the aluminum drum 1, and the mass M of the dielectric film 2 with the carrier attached is measured. Thereafter, the adhered carriers are blown off by blowing nitrogen gas with an air gun, and the mass M2 of the dielectric film 2 is measured again. The carrier adhesion amount M is determined from M 1M z, and the carrier adhesion amount M/S per unit area is determined from the area S of the dielectric film 2.

The dielectric film 2 from which the carrier has been removed is attached to the aluminum drum 1 again, a surface potential measurement probe (not shown) is installed at a position about 2ffII11 away from the dielectric, and the aluminum drum 1 is slowly rotated at a circumferential speed of 12 mm/s. The surface potential is output to an X-Y plotter (not shown), and the average VS of the surface potential is determined.

Subsequently, the voltage (2)5 applied between the developing roller 20 and the aluminum drum 1 is changed, and M+, Mz, and (4) are measured. Then, the potential difference V, -V between the developing roller 20 and the surface of the dielectric film 2, and the carrier adhesion amount per unit area M/
Graph S. FIG. 3 is a graph of the measurement results for two samples. In the figure, sample B has a larger amount of adhesion at the same potential difference, and it can be evaluated that sample B is more likely to cause carrier adhesion failure.

〔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 an explanatory diagram of the principle 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 the magnetic brush, and Fig. 5 The figure shows 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 means according to the present invention Part 1 Fig. 20 - Pseudo developing roller (developing roller) t Aluminum drum (41 teeth) 7θθ −200−, 3m −4/η zu
-6〃Regular roller and straddle electric bar I) Potential difference Vb-V3<
V) Shi4 Kuji (2 Iso〆J rc, R 5 Wozeri〉N1) [Ki] 晟t 3 Σ Ishisoki Fu Ran-) Ceremony date prisoner post

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 a 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) to make them adhere to the surface of the dielectric (2), a process of measuring the amount of carriers attached to the surface of the dielectric (2), and a process of removing the adhering carriers and measuring the amount of carriers remaining on the surface of the dielectric (2). Potential difference V between the surface of dielectric (2) and conductor (1) due to charge
Evaluating the adhesion characteristics of the carrier to the photoreceptor based on the relationship between the potential difference V_b-V_s between the surface of the dielectric (2) and the pseudo developing roller (20) and the amount of adhering carrier per unit area. A career evaluation method characterized by: