JPH0416774A - Method for measuring charge quantity distribution of developer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for measuring the charge amount distribution of a developer.

[Prior Art] In recent years, with the widespread use of image forming apparatuses such as electrophotography, electrostatic recording, and electrostatic printing, their uses have become widespread, and quality requirements for images have become stricter. The characteristics of the toner particles used here, particularly the amount of charge and particle size, are important factors in electrophotographic characteristics because they greatly affect the image density, sharpness, fog, etc. of the final copied image.

Traditionally, the blow-off method has been used to measure the amount of charge (this is known, but this alone is insufficient to provide information on the electrophotographic characteristics. In other words, it is difficult to measure the amount of charge on each toner particle. It is important as an electrophotographic property.2.3 is a method for measuring the charge amount distribution of such toner.
Proposed.

For example, Japanese Patent Application Laid-Open No. 57-7995111 proposes a method in which toner particles in a constant velocity airflow are deflected by an electric field and the toner charge distribution is measured from the amount of deflection after a certain period of time. However, toner particles have a wide particle size distribution depending on the case, and if the correspondence with the particle size is not known, it cannot be said that the charge amount distribution is effective.

As a method to solve such problems, Japanese Patent Application Laid-Open No. 61-2
No. 77071 has been proposed. This method determines the charge amount distribution corresponding to the particle size of toner particles from the degree of deflection and vibration phase of toner particles in a constant velocity airflow, electric field, and vibration waves. This is a very effective method. However, the most important point in measuring the amount of charge is to measure the amount of charge of the toner contained in the developer used for development.

Therefore, an important point is how to separate the charged toner from the developer in a form close to the development system and convey it to the measuring section. The method of JP-A No. 61-277071 mentioned above includes:
Since it is based on the measurement of charged particles after they have been separated,
It may not be possible to correlate the measured data with the toner used for development.

As a method for separating toner particles from carrier particles of a two-component developer, JP-A-57-79958 and JP-A-6
No. 3-263475 and the like propose a method of separating toner particles from carrier particles using compressed air. However, it is difficult to separate all the toner particles from the carrier particles because there are toner particles that are shaded by the carrier particles and cannot be effectively affected by compressed air, making it difficult to measure the charge distribution of all toner particles. It is. Furthermore, Japanese Patent Application Laid-open No. 1987-87'58 proposes a method of separating toner particles from carrier particles by using a mesh below the developer container. The mesh is fine, and when the toner particles pass through the mesh, they are recharged due to friction with the mesh, which may make it difficult to accurately measure the charge amount distribution.

As a method to solve such problems, JP-A-64-80
969 has been proposed. This method uses an electric field to weaken the Coulomb force between toner particles and carrier particles, and in this state, blows an air stream to separate the toner particles from the carrier particles. However, since this method relies on air flow for final separation of toner particles, it is difficult to separate all toner particles, and therefore it may be difficult to accurately measure the charge amount distribution of toner particles.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems, and its purpose is to peel off all the charged developer that has been charged in a form close to the developing system, and to remove the charged developer from the developing system. It is to measure the quantity distribution. Another purpose is to prevent the charged developer from being re-charged and to measure the charge amount distribution of the charged developer.

[Means and effects for solving the problems] The present invention provides a method for measuring charge distribution, in which a voltage is applied between a developer carrier and an electrode facing the developer carrier, and the voltage is used to measure the charge distribution. A method is provided in which the charged developer on the developer carrier is peeled off by the generated electric field, and further, an air flow is generated. This is a developer charge amount distribution measuring method that allows the charged developer to be transported to a measuring section.

[Examples] Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 FIG. 1 is a schematic diagram of a method for measuring charge amount distribution according to the present invention. A in the figure shows the charged developer 8 being transferred to the developer carrier 2.
This is a charged developer conveying part for peeling off the charged developer by applying an electric field and conveying the charged developer 8 to the measurement section B. B in the figure measures the particle size and charge amount of the charged developer 8. This is the part that measures the charge amount distribution.

A voltage is applied between the developer carrier 2 and the counter electrode 3 by a power source 4 to generate an electric field. Therefore, a force in the same direction as the electric field acts on the charged developer 8 in the developer 1 supported on the developer carrier 2 (that is, a predetermined voltage is applied according to the charging polarity of the charged developer 8). By applying this, it becomes possible to separate the charged developer 8 from the developer carrier 2.

The separated charged developer 8 flies from the device inlet toward the counter electrode 3 due to the force caused by the electric field.

Furthermore, the charged developer 8 that has flown to the vicinity of the counter electrode 3 is carried by the compressor 7 to the introduction part of the measuring part B by the air flow in the direction of the arrow.

In the present invention, from the developer l on the developer carrier 2,
The charged developer 8 is caused to fly by the force of the electric field, and can be further transported to the measuring section B by the air flow generated by the compressor 7 that passes through the measuring device 5.

The charged developer 8 conveyed to the measuring section B is transferred to the measuring device 5.
A predetermined physical quantity is measured, and the arithmetic unit 6 converts the physical quantity into a charge amount and a particle size.

Therefore, by measuring a plurality of charged developers 8 through the above process, it is possible to obtain the charge amount distribution with respect to particle size.

FIG. 2 and FIG. 3 show an example of the above-mentioned measuring device.

FIG. 2 shows a method of measuring the amount of charge and particle size using the laser Doppler method. 21a21b in the figure is a vibrating electrode, and 22 is a vibration generator. As is well known, microparticles existing in a constantly vibrating air field vibrate to follow the air vibrations. At this time, due to the inertia of the grains, the large grains vibrate with a delay from the standard vibration. Further, when a voltage is applied to the electrode, the particles are shifted in the direction of the electric field due to the particle size, the amount of charge, and the electric field caused by the applied voltage. Therefore, by measuring the phase delay of the vibration of the particles relative to the air vibration and the degree of deviation due to the electric field, the particle size and the amount of charge of the particles can be determined.

In the present invention, a laser generator 23 and a laser receiver 24 are arranged, and by using the laser Doppler method, the phase delay of the charged developer 8 with respect to air vibration and the shift speed due to the electric field are measured. The particle size and charge amount of the charged developer 8 are obtained by calculating the measured amount using the calculation device 6 shown in FIG.

In addition, the measurement method is not limited to (but is not limited to) the one shown in Figure 2, for example,
It may be as shown in the figure.

That is, a laser is generated from the laser generating section 23, the generated laser is introduced into the laser receiving section 24 through the window 25, and the velocity of the charged developer 8 in the air flow direction is measured by the laser Doppler method. As is well known,
The diameter of a particle can be determined by measuring the relative falling speed of the microparticle falling through the airflow with respect to the airflow.

Therefore, the particle size of the charged developer 8 can be obtained by determining the relative falling speed of the charged developer 8 using the laser Doppler method and calculating it using the calculation device 6.

Further, as is well known, the amount of charge on the charged developer 8 can be measured by measuring the charge induced on the detection electrode 31 by the charged developer 8 using the charge measuring device 32.

Embodiment 2 The present invention is not limited to the above method. For example, as shown in FIG.
It is also possible to transport the material up to

Embodiment 3 Also, for example, as shown in FIG.
．． 7" upstream and downstream of the measuring device 5,
2 in order to strengthen the air flow conveyed to the measuring section B, reduce the amount of charged developer 8 adhering to the counter electrode 3, and keep the strength of the air flow necessary for measurement within the measuring device 5 constant. A method using two compressors may also be used.

[Effects of the Invention] As explained above, according to the present invention, an electric field is generated between a developer carrier and an electrode facing the developer carrier, and all the charged developer on the developer carrier is peeled off. By transporting the charged developer to the measurement section using the electric field and air flow, it becomes possible to measure the charge amount distribution of the charged developer in a manner similar to that in the developing system.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the present invention, FIGS. 2 and 3 are schematic diagrams of a measuring section using an embodiment of the present invention, and FIGS.
The figure is a schematic diagram of another embodiment of the invention. 1: Developer 2: Developer carrier 3: Counter electrode 4: Power source 5: Measuring device 6: Computing device 7.7°: Compressor 8: Charged developer 21a, 2
1b + Vibrating electrode plate 23: Laser generator 22: Vibration generator 24: Laser receiver 25: Zu! person who prays

Claims (1)

[Claims] (1) A voltage is applied between a developer carrier and an electrode facing the developer carrier, the electric field generated by the voltage causes the charged developer to be peeled off from the developer carrier, and A developer charge amount distribution measuring method characterized by transporting a charged developer to a measuring section using an electric field and an air flow.