JPH0422882A - Toner charge amount distribution measurement method - 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 one-component toner particles.

[Prior Art] In recent years, with the spread 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 individual toner particles used, particularly the amount of charge and particle size, are important factors for electrophotographic characteristics because they greatly affect the image density, sharpness, fog, etc. of the final copied image.

Conventionally, the blow-off method is well known for measuring the amount of charge, but this method alone is not sufficient to provide information on electrophotographic characteristics. In other words, the amount of charge of each toner particle is important for electrophotographic characteristics.

Several proposals have been made as methods for measuring the charge amount distribution of toner.

For example, Japanese Patent Application Laid-open No. 57-79958 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. Although this is a very effective method, the most important point of these measurement methods is that the amount of charge on the toner is measured in a manner close to the developing system. Therefore, it is important to separate the charged toner from the developer in a form close to the development system and convey it to the measuring section. Since the above method is based on the measurement of charged particles after separation, there are cases where a correlation with development cannot be established.

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. 60-8758 proposes a method of separating toner particles from carrier particles by using a mesh below the developer container. The toner particles are so fine that when they 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.

As described above, the method for measuring the charge amount distribution is still not sufficient.

Furthermore, in recent years, one-component developing method has been increasingly used instead of two-component developing method. The one-component developing method is particularly suitable for small-sized machines because the developing machine can be made very small, but improvements in the developing machine have led to its use in high-speed machines that can process about 80 sheets per minute. However, the amount of charge, especially the distribution of the amount of charge, of one-component toner has not yet been fully analyzed, and it is thought that by analyzing these, it will be possible to further improve the level of the developing machine. In particular, in the insulating one-component developing method, the toner is thinly coated on the surface of the toner carrier, making it more difficult to separate the toner particles. In other words, when an air stream is used as the separation means 7, a thin layer of coated toner is blown onto the toner carrier, causing recharging with the surface of the toner carrier, or causing non-uniform charging. This causes problems such as a change in the charge amount distribution due to the formation of a toner coat layer. Furthermore, the toner particles may slip on the toner carrier and may not be conveyed to the measurement unit.

In contrast to this method of separating toner particles using air flow, a method of separating toner particles using only an electric field was proposed in Japanese Patent Application Laid-Open No. 1986-62.
This is proposed in Japanese Patent No. 58175. In this method, an alternating electric field is applied between two electrodes embedded inside an insulating sleeve, and the toner particles are separated from the two-component developer supported on the surface of the insulating sleeve by this alternating electric field.
This is to measure the charge amount distribution of toner particles by allowing them to fall freely to a measuring section.

However, the sleeve used in this method is special, and it cannot be said that it measures the charge amount distribution of toner particles that actually contribute to development.

As described above, a method for measuring the charge amount distribution of toner particles in the insulating l-component development method has not yet been established.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems. That is, the purpose is to measure the charge amount distribution of charged one-component toner particles in a form similar to the developing system in an actual image forming apparatus such as an electrophotographic system. Another purpose is to measure the charge amount distribution of all toner particles on the toner particle carrier while maintaining a thin and uniform toner coating layer on the toner particle carrier. Furthermore, it is necessary to accurately measure the charge amount distribution of magnetic toner particles in a form close to that of the developing system.

[Means and effects for solving the problem] According to the present invention, (1) In measuring the charge amount distribution of component toner particles, a thin film of monocomponent toner particles is coated on a toner particle carrier, and the toner particle carrier is and an electrode facing the toner particle carrier, an electric field generated by the voltage causes the toner particles to be peeled off from the toner particle carrier, and the electric field and air flow cause the toner particles to be separated from the measuring section. By transporting the toner particles to a toner particle carrier, almost all of the toner particles can be separated from the toner particle carrier and measured.

[Examples] Hereinafter, the present invention will be specifically explained by examples based on the drawings.

FIG. 1 is a schematic diagram of a method for measuring charge amount distribution according to the present invention. In the figure, A is a peeling/transporting part for peeling charged toner particles 10 from the toner carrying member 2 by an electric field and conveying them to measurement part B, and B in the figure is a part for measuring the particle size and charge amount of the charged toner particles 10. This is the part for measuring the charge amount distribution. The charged toner particles 10 are one-component toner, and numerals 2 and 4.5 indicate components of the developing system. That is, 2 is the sleeve,
4 is a regulating member, and 5 is a magnetic pole. As the sleeve 2 rotates, a thin layer of toner is coated. An electric field is generated between the henna carrier 2 and the counter electrode 3 by a voltage applied by a power source 9.

Therefore, a force in the same direction as the electric field acts on the charged toner particles 10 in the toner l carried on the toner carrier 2. Therefore, by applying a predetermined voltage according to the charging polarity of the charged toner particles 10, it becomes possible to separate the charged toner particles 10 from the toner carrying member 2.

The separated charged toner particles 10 fly from the device inlet toward the counter electrode 3 due to the force caused by the electric field. In the case of one-component magnetic toner, toner 1 in FIG.
When enlarged, it forms a panicle like 61 in Figure 6,
It exists on the toner carrier 2 in an aggregated state.

Furthermore, the charged toner particles 1O that have flown to the vicinity of the counter electrode 3 are carried by the compressor 8 to the introduction section of the measurement section B by an air flow in the direction of the arrow.

In the present invention, the charged toner particles 1O are caused to fly from the toner 1 on the toner carrying member 2 by the force of the electric field, and can be further transported to the measurement section B by the airflow from the compressor 8 that passes through the measurement device 6.

A predetermined physical quantity of the charged toner particles 10 conveyed to the measurement section B is measured by a measuring device 6, and the physical quantity is converted into a charge amount and a particle size by a calculation device 7.

Therefore, by measuring a plurality of charged toner particles 10 through the above process, it is possible to obtain the charge amount distribution with respect to particle size.

FIG. 2 shows an example of the above measuring device, which uses a laser Doppler method to measure the amount of charge and particle size. 21a and 21b in the figure are vibrating electrodes,
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 depending on 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 charge amount 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 toner particles 10 with respect to air vibration and the deviation speed due to the electric field are measured, and this measured quantity is The charged toner particles 10 are calculated by the calculation device 7 in FIG.
The particle size and charge amount are obtained.

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 generator 23, and the generated laser is passed through the window 25 to the laser receiver 24.
The velocity of the charged toner particles 10 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 velocity of a minute particle falling in an air stream with respect to the air stream.

Therefore, the particle size of the charged toner particles 10 can be obtained by determining the relative falling speed of the charged toner particles 10 using the laser Doppler method and performing calculations using the calculation device 7.

In addition, as is well known, the electric charge induced by the charged toner particles 10 on the detection electrode 32 is measured by the electric charge measuring device 31.
The amount of charge on the charged toner particles 10 can be measured by measuring the amount of charge on the charged toner particles 10. In this method, when a one-component magnetic toner that is restrained by magnetic force on a toner carrier is used, the magnetic cohesive force of the toner particles is weakened by separating and transporting the toner particles that have a strong magnetic force. It was also confirmed that the toner was separated into individual toner particles before entering the measuring section.

Embodiment 2 The present invention is not limited to the above-described method (for example, as shown in FIG. 4, a compressor 8' is provided, which generates an air flow from the upper part of the apparatus and carries the charged toner particles 10 to the measuring section B). A method of transportation may also be used.

Embodiment 3 In addition, for example, as shown in FIG.
. It is also possible to use two compressors so that the strength of the required airflow can be kept constant. Furthermore, in this method, the conveying air flow can increase the flow of the air flow from the inlet for toner uptake, so that the toner powder cohesive force is weakened by this air flow, and the toner particles are separated into individual toner particles. It was also possible to reduce the amount of unmeasured toner.

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

Therefore, the one-component magnetic toner can be transported to the measuring section in a state in which the magnetic aggregation is loosened, and a more accurate charge amount distribution can be obtained.

Furthermore, since the air flow can be strengthened locally, it is possible to weaken the powder cohesive force and loosen the toner particles, resulting in a more accurate charge amount distribution.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the present invention, FIG. 2 is a schematic diagram of a measuring section used in the present invention, and FIGS. 3 to 5 are schematic diagrams of other embodiments of the present invention. FIG. 6 is an enlarged view of the toner in FIG. 1. 1: Toner 2; Toner carrier regulating member measuring device 8': Compressor Charged toner particles 3: Opposing electrode 4: 5: Magnetic pole 6: 7: Arithmetic unit 8 9: Power supply 10: 21a, 21b: Vibrating electrode plate 22: Vibration Generator 23: 24: Laser receiver 25: Window 31: Charge measuring device 32: Detection electrode 61: Ear-shaped toner mass A: Peeling/conveying section
B: Measurement part laser generator

Claims (1)

[Claims] (1) In measuring the charge amount distribution of one-component toner particles,
A thin film of one-component toner particles is coated on a toner particle carrier having a conductive member, a voltage is applied between the toner particle carrier and an electrode facing the toner particle carrier, and the electric field generated by the voltage causes the particles to be peeled off. A toner charge amount distribution measuring method characterized in that the toner is conveyed to a charge amount distribution measuring section by the electric field and air flow.