JPH01217377A - Method for measuring toner concentration of developing agent - Google Patents

Abstract

PURPOSE:To accurately calculate the toner concentration of a developing agent by calculating the toner concentration in such a way that a linear measuring electrode is provided on the peripheral surface of an electrically insulating cylindrical body along the axial direction of the cylindrical body which is provided in the vicinity of a sleeve for carrying developing agent and the toner concentration is calculated form a developing current measured in such state. CONSTITUTION:An electrically insulating cylindrical body 1 is provided in the vicinity of a sleeve 2 for carrying developing agent and, at the same time, a narrow measuring electrode 3 is provided on the peripheral surface of the cylindrical body 1 along its axial direction. Then a developing agent is supplied while a bias voltage is applied across the sleeve 2 and electrode 3 and the value of the current flowing between them is measured. The measured current value is converted into toner concentration. Since all of the electric current from the sleeve surface in the developing area substantially flows to the linear electrode 3 when such linear electrode 3 is used, the electric current which flows into the unit area of the electrode 3 becomes extremely large. Accordingly, the measured current value sensitively changes in corresponding to a change in toner concentration and, when a calibration curve is prepared in advance, the concentration can be calculated accurately form the current value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for measuring toner concentration in a developing area in an electrostatographic apparatus that performs development using a two-component 6R developer.

(Prior Art and Problems) In an electrostatic photographic device such as a copying machine, an electrostatic latent image is formed on a photoreceptor drum by image exposure, and the latent image is visualized using a developer to make a copy. Get the image.

As this developer, a so-called two-component developer consisting of a magnetic carrier and electrostatic toner is known.
The ears of a magnetic brush are formed by a magnetic carrier, the magnetic brush is rubbed against the surface of a photoreceptor drum, and development is performed by the toner in the magnetic brush adhering to the electrostatic latent image due to electrostatic attraction. be.

Therefore, when performing development using a two-component developer, understanding the toner concentration of the developer in the development area has extremely important significance in setting good development conditions.

As a method of measuring this toner concentration, an appropriate measuring electrode is installed near the developer conveying sleeve in the developing device of an actual copying machine, and the toner concentration is determined by measuring the electrical resistance between the electrode and the sleeve. There are known methods for calculating . , .

However, in this method, it is difficult to install the measuring electrode in the actual developing area (there is a photoreceptor drum in the developing area), so it is not possible to measure the toner concentration in the developing area. It is unsuitable for analyzing the development state.

In addition, as a method for measuring the developing current, an aluminum tube is installed near the developer conveying sleeve, and while developer is supplied between the aluminum tube and the sleeve, the developing current flowing through the aluminum tube is measured. The means are known.

It is possible to use this method to calculate the toner concentration in the development area from the development voltage, but with this method, the current value does not change in response to changes in toner concentration, and the toner concentration can be accurately calculated. It is difficult to calculate accurately.

(Means for Solving the Problems) The present invention provides a linear measuring electrode in the axial direction of the circumferential surface of an electrically insulating cylinder, and disposes the cylinder in the vicinity of a developer conveying sleeve. The above-mentioned problem is solved by calculating the toner concentration from the developing current measured in the state.

That is, according to the present invention, in a method for measuring toner concentration in a two-component magnetic developer comprising a magnetic carrier and electrostatic toner, an electrically insulating cylinder is disposed near a developer conveying sleeve, and A narrow measurement electrode is provided at a position in the axial direction of the circumferential surface of the cylinder, a bias voltage is applied between the sleeve and the electrode to supply developer, and a value of the current flowing between the two is measured, This measured current value is the toner concentration.

Provided is a method for measuring the toner concentration of a developer, which is characterized in that the toner concentration is converted into .

(Function) A notable feature of the present invention is that the toner concentration is calculated from the developing current measured by a linear measuring electrode provided on the electrically insulating cylinder.

In other words, when the developing current is measured using a cylindrical body such as an aluminum tube as a measurement electrode, the current from the sleeve surface in the developing area flows into the aluminum tube surface in the developing area, so the current is measured per unit area of the aluminum tube. The developing current flowing through is extremely small.

Therefore, as shown in the comparative example described below, the change in the developing current value in response to the change in toner density is minute, and it is inappropriate to calculate the toner density from the current value.

On the other hand, when a linear electrode is used according to the present invention, substantially all of the current from the sleeve surface in the developing area flows into the linear electrode, so the current flowing per unit area of the linear electrode is , becomes extremely large.
- For this reason, the measured current value changes sensitively in response to changes in toner concentration, so by creating a calibration curve in advance, it is possible to accurately calculate toner from the current value. .

Incidentally, the rate of change of the developing current value per toner density light measured according to the present invention is approximately twice that when an aluminum tube is used.

(Preferred Aspects of the Invention) The present invention will be described in detail below based on specific examples shown in the accompanying drawings.

Measuring Development Current In the method of the present invention, crosstalk current is measured, and toner density is calculated from this development current.

In FIG. 1, a device for measuring this development current is shown, which roughly consists of a developer conveying sleeve 2 and a measuring drum 1. As shown in FIG.

The sleeve 2 has a built-in magnet (not shown), similar to the one provided in an actual copying machine, and the magnetic brush of the developer is caused by the rotation of the sleeve or the rotation of the magnet. is formed and transported.

The measurement tram 1 corresponds to the photoreceptor tram,
The gap I between the sleeve 2 and the sleeve 2 is approximately 1
It is set to about 2 mm to 2 mm.

The measuring drum 1 is made of an insulating cylindrical body, and a linear measuring electrode 3 is provided on the circumferential surface of the drum 1 in the axial direction.

It is desirable that the measuring electrode 3 be fixed at a position in the developing area where the current flow is lowest, and generally within ±2° with respect to a line connecting the center of the tram 1 and the center of the sleeve 2.

The measuring electrode 3 is connected to the sleeve 2 via an ammeter 5 and a power source 6.
The bias voltage necessary for development is applied and the current is read.

In the present invention, the width P of the measurement electrode 3 is 01 to 5
mm, especially in the range 01 to 1.0 mm.

If the width exceeds 5 mm, the change in the measured current value for each toner concentration groove will become small, making it difficult to calculate the toner concentration accurately, and if the width is smaller than 0.1 mm, the absolute value of the measured current value will become smaller. As a result, it becomes difficult to calculate the toner concentration with high accuracy.

In the present invention, the apparatus shown in FIG. 1 is used,
A bias voltage similar to that of an actual copying machine is applied, a two-component developer is supplied from the sleeve 2, and the developing current flowing to the measuring electrode 3 is measured.

Calculation of toner concentration In the present invention, a calibration curve is created in advance by measuring the developing current for a constant toner concentration using the above method, and based on this calibration curve, the development of the developer to be measured is calculated. The toner concentration is calculated from the current value.

According to the present invention, toner concentration can be calculated with a detection limit of 0.1%, which is extremely useful in analyzing actual development conditions.

Example As shown in FIG. 1, an insulating cylinder (drum) 1 with a 0.5 mm wide electrode 3 is fixed so that the tram-sleeve center line and the electrode are at +2° θ= 2°), rotate the sleeve. Next, apply a DC bias of +500■ from the power supply 6, and measure the current flowing at that time using the ammeter 6.
I read it at.

FIG. 2 shows the relationship between the toner concentration of the developer and the current value.

As a comparative example, FIG. 2 also shows the results of current measurements using aluminum tubes instead of electrodes. Table 1 also shows the current amount and rate of change that change with a 1% change in toner concentration.

From Table 1, it can be seen that compared to using an aluminum tube, the present invention has a
It can be seen that the sensitivity is twice as high.

FIG. 3 shows the relationship between electrode width and rate of change. From this, it is relevant that the electrode width is preferably 0.1 to 5 mm, particularly 01 to 1 mm.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a developing current measuring device used in the method of the present invention, Fig. 2 is a diagram showing the relationship between the toner concentration in the developer and the measured current value, and Fig. 3 is a diagram showing the measurement electrode width. FIG. 3 is a diagram showing the relationship between the change rate of the measured current and the rate of change of the measured current. 1... Measuring tram 2... Sleeve 3... Measuring electrode 5... Ammeter 6... Power source Patent applicant Sanda Kogyo Co., Ltd. company

Claims (2)

[Claims] (1) In a method for measuring toner concentration in a two-component magnetic developer consisting of a magnetic carrier and electrostatic toner, an electrically insulating cylinder is disposed near a developer conveying sleeve, and the cylinder is A narrow measurement electrode is provided at a position in the axial direction of the circumferential surface, a bias voltage is applied between the sleeve and the electrode to supply developer, and the value of the current flowing between the two is measured. A method for measuring toner concentration of a developer, the method comprising: converting the toner concentration into toner concentration. (2) The measuring method according to claim 1, wherein the width of the measuring electrode is 0.1 to 5 mm.