JPH0415567A - One-component 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 Field of Application] 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 toner particles used here, particularly the amount of charge and the 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 method alone is not sufficient to provide information on the electrophotographic characteristics. In other words, it is difficult to measure the amount of charge on each individual toner particle. is important as an electrophotographic property.

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 one to five 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 sometimes have a wide particle size distribution, and unless the correspondence with the particle size is 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 developing system and convey it to the measuring section. Since the above method is based on the measurement of charged toner after being separated, it may not correlate with actual development.

Therefore, as a method for separating toner particles from carrier particles of a two-component developer, Japanese Patent Laid-Open No. 57-79958 discloses a method for separating toner particles from carrier particles of a two-component developer.
Japanese Unexamined Patent Publication No. 63-263475 proposes a method of separating toner particles from carrier particles using compressed air. However, since some toner particles are hidden by carrier particles and compressed air is not effective, it is difficult to separate all toner particles from carrier particles, and it is difficult to measure the charge distribution of all toner particles. Have difficulty. Further, 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. In this method, the mesh is quite fine in order to collect carrier particles, 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. be.

As a method to solve such problems, JP-A-64-80
No. 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 airflow 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.

The method for measuring the toner charge distribution described so far has been proposed for two-component developers consisting of carrier particles and toner particles, and it is thought that there is a problem with measuring the charge distribution of single-component toner particles. It will be done. That is, with these methods that mainly use air flow, it is difficult to accurately measure the charge amount distribution of one-component toner particles. Measuring the charge amount distribution of one-component toner particles is free from the problem of separation of toner particles and carrier particles as in the case of two-component developers, but the measurement of toner particle distribution during development in an actual electrophotographic system It is more difficult than in the case of two-component developers to measure the charge amount distribution that corresponds to the triboelectric charge of the two-component developer.

That is, when an air flow or the like is used as a means for separating the one-component l-toner coated in a thin layer onto the toner particle carrier, the toner layer coated in a thin layer is separated from the toner particle carrier. In addition to causing problems such as recharging with the surface of the toner particle carrier when the toner particles are blown or becoming an uneven toner layer and changing the charge amount distribution, the toner particles may separate from the toner particle carrier. Otherwise, the toner particles may slip on the toner particle carrier and the toner particles may not be properly conveyed to the measuring section.

In contrast to this method of separating toner particles using air flow,
A method for separating toner particles using only an electric field was published in Japanese Patent Application Laid-open No. 62-5.
This is proposed in Publication No. 8175. In this method, an alternating electric field is applied between two electrodes embedded inside an insulating sleeve, and the alternating electric field separates 1-ner particles from the two-component developer supported on the surface of the insulating sleeve.
This is to measure the charge amount distribution of toner particles by allowing them to fall freely to a measuring section. However, in this method, the sleeve used is special, and not only is it difficult to correspond to the actual developing system, but the applied alternating electric field is essentially generated inside the sleeve. The separated toner particles are subjected to a force due to the leaked electric field, and there is a possibility that the toner particles have a biased charge distribution even before measurement. Furthermore, since a stronger electric field is required to separate all the toner particles, creeping discharge may occur on the sleeve surface.

As described above, no method has yet been proposed for accurately measuring the charge amount distribution of component-based toners, especially magnetic toners.

Therefore, in measuring the charge amount distribution of a one-component toner, the present inventors conducted a research in which one-component toner particles coated in a thin layer on a toner particle carrier having a conductive member were mixed with an L-toner particle carrier and the toner particles. We proposed a method for measuring the charge distribution by peeling off the support by an electric field generated between the support and an electrode facing it, and transporting it to a charge distribution measurement unit by the electric field and air flow.

[Problems to be Solved by the Invention] However, in the above conventional method, (1) depending on the amount of charge or charge polarity of the toner, it takes time to peel off the charged toner particles from the toner particle carrier; There may be cases where the applied electric field has to be readjusted. Also, in actual systems, frictional charging occurs with the toner particle carrier, so it is necessary to correspond between the measured value of the amount of charge and the actual value. There are issues such as the need for

That is, an object of the present invention is to provide a method for measuring the charge amount distribution of a one-component toner, which eliminates the problems such as "double charge".

[Means and effects for solving the problems] The present invention is characterized by: A one-component toner is supported on a toner particle carrier, and a voltage is applied between the toner particle carrier and an electrode facing the toner particle carrier. By applying an electric field, the one-component toner particles supported on the toner particle carrier are peeled off, and the charged one-component toner particles peeled off by the electric field and air flow are sent to the charge amount distribution measuring section. A one-component toner charge amount distribution measuring method in which the charge amount of a one-component toner is measured by transporting the toner, the one-component toner particle carrier being coated with a thin layer of one-component toner particles, and an alternating electric field being applied as the electric field. This method uses a toner charge amount distribution measurement method.

Another feature is that a rectangular wave is particularly used as the alternating electric field.

According to this means, it is possible to peel off all the toner particles on the toner particle carrier regardless of the charge amount and polarity of the toner, and the charge amount of the charged toner to be used for actual development can be controlled. It becomes possible to measure.

Hereinafter, the structure and operation of the present invention will be explained in detail using examples.

[Example] FIG. 1 shows an example of an apparatus to which the charge amount distribution measuring method according to the present invention is applied. This apparatus is roughly divided into a toner particle 1 separation/transport section A and a measurement section B. First, regarding the separation/transport section A, reference numeral 1 denotes charged one-component toner particles, and 2 denotes a toner particle carrier capable of supporting the one-component toner particles 1, which are made of aluminum or stainless steel. It is a plate-like cylindrical member having a rubber, resin layer, etc. on the metal surface, and the toner particle supporting surface may be roughened as necessary. Furthermore, the opposite side (back side) of the toner particle supporting surface
A magnet 7 may be provided to provide a supporting force when the above-described toner particles 1 include a magnetic material. 3 is a toner particle carrier 2
An electrode plate for generating an electric field between aluminum and aluminum.

It is made of conductive metal such as iron, or the surface of these metals is plated with gold or the like for rust prevention purposes. Further, the electrode plate 3 is provided with a slit 6 for taking the toner particles 1 separated from the toner particle carrier 2 by the electric field into the conveying section and the measuring section. Reference numeral 10 denotes a power source for generating an electric field between the toner particle carrier 2 and the electrode plate 3, and in this embodiment, it is an AC power source for generating an alternating electric field. Further, although the power source 10 is installed between the ground and the electrode plate 3, there is no problem if it is installed between the ground and the toner particle carrier 2.

Next, measurement section B will be described. The measurement unit B includes a charge amount detection unit 21. Arithmetic unit 22. Consisting of 31 compressors,
The charge amount detection section 21 detects the charge amount of each toner particle sent in a constant air flow from the toner particle separation/conveyance section A using the Faraday gauge method shown in FIG. 2(b) or the second method. The measurement is performed by the ion spectrometry method (Static Electricity Handbook, published by Ohmsha) using the deflection of charged particles by a constant electric field as shown in Figure (a). Furthermore, the particle size can also be measured by using the laser Doppler method described later. The values measured here are sent to the calculation unit 22 and output as data in a necessary format, for example, Q/m specific gravity charge amount, Q/d ratio diameter charge amount, and particle size distribution.

To explain this measuring method based on FIG. 2, the one shown in FIG. 2(a) is a method for measuring the amount of charge and particle size using the laser Doppler method. 21 in the diagram
1a, 211. b is a vibrating electrode, and 212 is a vibration generator.

As is well known, microparticles existing in an air field vibrating at a constant frequency vibrate following the air vibrations. At this time, due to the inertial force 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 this embodiment, a laser generator 213 and a laser receiver 214 are arranged, and the laser Doppler method is used to measure the phase delay of the charged toner particles 1 with respect to air vibration and the shift speed due to the electric field. The particle size and charge amount of the toner particles 1 are obtained by calculating the measured amounts in the calculating section 22 in FIG.

Further, the measurement method is not limited to the one shown in FIG. 2(a), but may be, for example, the one shown in FIG. 2(b).

That is, a laser is generated from the laser generator 213, and the generated laser is passed through the window 217 to the laser receiver 2.
14, and the velocity of the toner particles 1 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 a microparticle falling in an airflow with respect to the airflow. Therefore, the particle size of the toner particles 1 can be obtained by determining the relative falling speed of the toner particles 1 using the laser Doppler method and performing calculations in the calculation section 22 (a).

Furthermore, the amount of charge on the toner particles 1 can be measured by measuring the charge induced on the detection electrode 218 by the toner particles 1 using the charge measuring device 22 (b).

Next, the compressor 31 has the role of generating an air flow to move the charged toner particles 1 at a constant flow rate through the separation/transport section A and the measurement section B, and the compressor 31 has the role of generating an air flow to move the charged toner particles 1 at a constant flow rate. It is preferable to adjust the bow-sucking force appropriately depending on the central particle size, density, and surface shape.

Next, the electric field applied between the toner particle carrier 2 and the electrode plate 3 will be described in detail. Normally, the toner particles 1 on the particle carrier 2 are coated in a thin layer by a regulating member 4 in a form similar to that of a developing system, and at the same time are triboelectrically charged. At this time, the regulating member may be made of a magnetic blade made of stainless steel, iron, etc., an elastic roller or elastic blade made of urethane, or any other material that can coat the toner particles in a thin layer. The toner particles 1 coated in a thin layer in this manner usually have a diameter of 10-odd pm to several μm, and it is very difficult to make the charging polarity of each toner particle uniform. That is, it is easily considered that the l·ner particles 1 have both positive and negative polarities.

For this reason, if only a DC electric field is used as a separating electric field, not only can only toner particles biased toward one polarity be collected;
Even if aggregates of positive and negative toner particles are separated, it is possible that accurate charge amount distribution cannot be determined.

Therefore, by setting the electric field involved in this separation to an alternating electric field as shown in FIG. 3, toner of both positive and negative polarities can be extracted.

FIG. 3(a) shows a waveform generally called a sine wave, in which the applied voltage gradually increases and decreases as time passes, and the electric field also gradually increases and decreases repeatedly. When this alternating electric field is applied to the electrode plate 3 shown in FIG. When the negatively charged toner particles 1 are applied with an electric field stronger than the restraining force described later, they separate from the toner particle carrier 2, and are accelerated by the gradually increasing electric field and move toward the electrode plate 3. Further, when the applied alternating voltage is in the opposite (-) direction of the arrow, the toner particles 1 are decelerated, and the toner particles 1 that were able to reach the vicinity of the electrode plate 3 before the speed reaches O are slit. It is sucked in by the air flow (arrow 5) flowing into the separating/conveying section A from 6, and then flows into the measuring section B along with this air flow.

On the other hand, if the applied sinusoidal alternating electric field is biased toward the (-) side,
The positively charged toner particles 1 are separated from the toner particle carrier 2 and subjected to measurement.

Next, the conditions of the applied alternating electric field will be described. The applied alternating electric field needs to be strong enough to separate the charged toner particles 1 from the particle carrier 2, but the upper limit of the electric field that can be applied is between the toner particle carrier 2 and the electrode plate. 3 (as shown in FIG. 1). In other words, if the charged toner particles are non-magnetic, the lower limit of the electric field to be applied is determined by the electric field, which is greater than the sum of the reflection force determined by the amount of charge and the particle size, and the dispersion force such as van der Waals force. It is necessary to set the force so that the force applied to the toner particles is large.

In addition, in the case of a magnetic toner in which the toner particles have a magnetic substance inside, a magnet is generally provided inside the toner particle carrier 2, and the addition of this magnetic force to the reflection force 5 dispersion force determines the separation electric field. This is a guideline.

The upper limit of the electric field is uniquely determined by the distance described above.

That is, when this method is used in air, in order to obtain a stable applied electric field, it is necessary to suppress the electric field to less than the electric field defined by Paschen's law. If an electric field stronger than the electric field determined by this law is applied, a spark discharge will occur between the electrodes, so this value is about 10% lower than the discharge starting electric field indicated by Paschen's law. It is sufficient to apply the maximum electric field within a range not exceeding .

Next, the frequency of the applied alternating electric field will be described. If the toner particles 1 separated by this alternating electric field are not pulled back by the alternating electric field with the opposite component and the reflected force from the toner particle carrier 2, the reflected force from the electrode plate 3 and the air suction force is taken into the measurement system by Therefore,
The frequency of the alternating electric field to be applied needs to be determined with sufficient consideration given to the reflection force from the toner particle carrier 2.
When a pullback force due to a magnetic field is present in addition to this reflection force, it is preferable that an electric field of the same polarity is applied for a sufficient period of time. If the electric field alternates in a short time compared to these pulling forces, the toner particles will vibrate near the surface of the toner particle carrier.

Furthermore, the electric field that separates the toner particles measured here differs depending on the amount of charge.

Generally, charged toner particles are charged to various sizes. In the alternating electric field expressed by the sine wave in FIG. 3(a), when the electric field increases in the direction of the arrow, a restraining force other than the electric field force is exerted on the toner particle carrier 2 and the charged toner particles inside it. If not, charged toner particles l
Among them, those with a large particle size or a small amount of charge are separated initially, and as the electric field becomes stronger (as the electric field becomes stronger, particles with a smaller size and a larger amount of charge are separated).

In other words, it is more efficient (to collect toner particles,
As shown in Figure 3(b), applying a rectangular wave electric field with the same effective value as a sine wave electric field allows more time for a strong electric field to be applied, as shown in Figure 3(b), than a gradually changing electric field. The number of toner particles that can be collected will increase.

However, in this case, the PP value of the applied rectangular wave increases the velocity of the toner particles in a short time, reaches the electrode plate 3, and is collected more quickly than the sine wave.

Furthermore, if the effective value of the alternating electric field due to this rectangular wave is made equal to that of a sine wave, there will be a margin in the P-P value, and in order to make it close to the P-P value of the sine wave, as shown in Figure 3 (c). The P-P value can be increased by up to 4 times.

In this case, an electric field force equal to the maximum value of the sine wave is applied to the toner particles for half a period, and the speed of the toner particles reaching the electrode plate 3 increases, and the positive and negative polarities are combined. The maximum collecting power for toner particles can be obtained. It goes without saying that the P-P value should be set within a range that does not exceed the discharge starting electric field mentioned above.

Next, the conditions of each part will be explained in detail. When the toner particles are magnetic and have a particle size of 3 to 15 pm, if a stainless steel blade is used as the regulating member 4, the distance between the toner particle carrier 2 and the tip of the regulating member 4 will be 50 to 30 μm.
0 ILm is preferable, and the toner particles 1 are transferred to the toner layer 3 by rotating the toner particle carrier 2 by the regulating member 4.
It is coated in a thin layer of ~20 layers.

The distance between the toner carrier 2 and the electrode 3 is 50 pm or more and 3 m.
m or less, preferably 100 ILm or more and 2 mm
It is recommended to set the following. If it is set to less than 50 pm, leaks are likely to occur due to the accuracy of the toner particle carrier 2, and the toner particles will also be separated due to the wind flowing in from the slit 6, making accurate measurement difficult. Moreover, if it is set to exceed 3 mm, it is necessary to increase the applied alternating voltage, and there is a possibility that discharge will occur at the end face of the slit 6, etc. Or, the electric field leaking to the outside is strong (
Therefore, there is a possibility that toner particles may be scattered outside the measuring section.

Next, the alternating electric field to be applied has a particle size of 3 to 15 pm,
In order to sufficiently separate toner particles with a maximum absolute value of charge of about 100 pc/g, the toner particle carrier 2 and the electrode plate 3 are required.
If the distance between them is 400 to 600 ILm, P-P is 8
It is sufficient to generate an electric field by applying an alternating voltage of 00 to 2000V, preferably 1500 to 2000V.

Note that under the same conditions as above, the frequency should not exceed 20 KHz (preferably, it should not exceed 10 KHz).

Next, specific numerical values and the like in this example will be described.

First, a magnetic toner is used as the toner particles 1, and a toner particle carrier 2, which is an aluminum sleeve, is rotated by a regulating member 4 made of a stainless steel blade, and a thin layer of toner of about 150 μm is coated on the toner particle carrier 2. provided. As the electrode 3, an aluminum plate coated with gold is used, and the surface facing the sleeve has a width of 1 mm, a length of 1 mm, and a length of 0 mm.
The slit 6 was cut in the shape of a cross. Furthermore, air was made to flow in at a rate of 50 cc per second by the compressor 31, the peak-to-peak voltage was 1600 V, and the distance between the sleeve and the electrode was 500 μm.
A sinusoidal alternating electric field was applied with one frequency of 2 KHz. The charge amount distribution of the separated transported toner was measured using a laser Doppler method. The measurement results are shown in Figure 4. In this figure, the vertical axis is the ratio of numbers, and the horizontal axis is q/d.
(charge/diameter) distribution. A distribution of toner particles is also seen on the positive electrode side beyond the central charge amount of 0, and it is seen that the toner charge amount distribution spans both positive and negative sides. On the other hand, when the applied voltage was DC and +300V was applied to the electrode plate 3 side, it was confirmed that the toner particles charged on the positive electrode side were extremely reduced and were not measured and were not separated.

Furthermore, the regulating member for thin layer coating is not limited to the method described above (for example, as shown in FIG. A method may also be used in which a thin layer is coated for measurement.

Alternatively, as shown in FIG. 6, a method may be used in which a urethane sponge roller is used as the regulating member 4 to form a thin layer of non-magnetic one-component toner.

[Effects of the Invention] As explained above, according to the method for measuring the charge amount distribution of a one-component toner of the present invention, a thin layer of toner is coated on a toner particle carrier, and an I. By applying an alternating electric field between the toner particles and the electrode, 2) collecting the toner particles, and measuring the charge amount distribution, (2) measurement becomes possible regardless of the charge characteristics of the toner particles.

(2) It is possible to measure the charge amount distribution of charged [component toner particles] in a form similar to that in a developing system, and it is also possible to measure efficiently and with high precision.

There are effects like this.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic configuration diagram of an apparatus used for measuring charge amount distribution that best represents the features of the present invention. 3 is a schematic diagram showing a means for measuring the amount of charge and particle size using the Puller method. FIGS. 3(a), 3(b), and 3(c) show alternating electric fields according to the present invention. Fig. 4 shows the measurement results of the charge amount distribution obtained in the example. Figs. 5 and 6 show the case where other means were used as the regulating member. 1... Toner particles 3... Electrode plate 5... Air flow 10... Power source 22.22 (a), 22 (b) - calculation unit 221a,
211b... Vibrating electrode plate 213... Laser generator 217... Window 2... Toner particle carrying member 4... Regulating member 6... Slits 1 to 21... Charge amount detection device 31. ... Compressor 212 ... Vibration generator 214 ... Laser receiver 218 ... Detection electrode

Claims (2)

[Claims] (1) A one-component toner is supported on a toner particle carrier,
By applying a voltage between the toner particle carrier and the opposing electrode, an electric field is generated to peel off the one-component toner particles supported on the toner particle carrier, and the electric field and air In a method for measuring charge amount distribution of a one-component toner in which charged one-component toner particles peeled off by a flow are conveyed to a charge amount distribution measuring section and the amount of charge is measured, a thin layer of one-component toner particles is formed on the toner particle carrier. A method for measuring the charge amount distribution of a one-component toner, characterized in that the toner is coated with a toner, and an alternating electric field is applied as the electric field. (2) The one-component toner charge amount distribution measuring method according to claim 1, wherein a rectangular wave is used as the alternating electric field.