JPH06161234A - One-component toner developing method - Google Patents

Abstract

PURPOSE:To obtain an excellent print without a fringe even if printing speed is increased and the design precision of a machine is made rough by electrostatically separating toner stuck to a nonimage part on an electrostatic latent image carrier after development. CONSTITUTION:The layer of one-component toner 4 on a toner carrier 1 is brought into contact with the electrostatic latent image carrier 5, to actualize an electrostatic latent image 6. As a mechanism removing the toner stuck to a fringe part generated on the circumference of the image part of the electrostatic latent image 6, a conductive roller is provided on the downstream side of a developing unit and the upstream side of an electrostatic transfer mechanism. A voltage having the polarity reverse to that of the toner stuck to the fringe part is impressed to this roller and it comes into contact with the electrostatic latent image carrier 5 after being developed or approaches it. The toner stuck to the image part and the toner stuck to the fringe part have opposite polarities each other. Therefore, electrostatic attracting force acts on the toner on the fringe part and repulsive force acts on the toner on the image part. Thus, the toner on the fringe part is selectively removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method for developing an electrostatic latent image by an electrophotographic method, an electrostatic recording method or the like with a one-component toner.

[0002]

2. Description of the Related Art In recent years, in the electrophotographic developer widely used not only in copying machines but also in printers, facsimiles and the like, the dry type is the mainstream because of its ease of handling. Further, the dry type developer includes a two-component developer which is used by mixing carrier particles and toner particles and a one-component developer which does not require a carrier. Development method using two-component developer (2
The component development method) has the most proven results and is most widely used at present, and the image quality is relatively good, but it has the following drawbacks.

(1) Since the developer consumes only toner during development, a toner replenishing means and an adjusting mechanism for keeping the toner density constant are required, which makes the machine large and complicated. (2) In order to triboelectrically charge the toner and the carrier, the developer must be sufficiently and quickly stirred, large power is required, and the developing device becomes large. (3) The life of the developer is short due to contamination of the carrier surface by the toner. (4) Due to the problem of (3) above, it is necessary to replace the developer from time to time, and it is easy for stains inside the machine to occur due to toner scattering due to a decrease in the toner charge amount, and sometimes extensive cleaning inside the machine is necessary. Therefore, maintenance by a person with specialized knowledge is essential. (5) The triboelectrification property of the toner is easily affected by environmental humidity, and problems such as fog generation and image density reduction are likely to occur.

However, in recent years, electrophotographic copying machines,
Due to the rapid progress of miniaturization and personalization of printers, facsimiles, etc., they are small, simple, and do not require the above-mentioned maintenance, and are stable in any usage environment, especially in high temperature and high humidity. It is becoming more and more important to establish a reliable one-component developing method capable of obtaining an image. In addition, when the two-component developing method is used for a large-sized machine or a high-speed machine, the developing device needs to be 2
If more than one piece is needed, the development mechanism becomes more complicated and large, the developer replacement work during maintenance becomes very difficult, and the downtime accompanying this becomes a major obstacle to use. The demand for these improvements is increasing.

Further, in recent years, environmental protection on a global scale has become more and more important, and carrier particles discarded from a two-component developer having a short life cannot be reused, which will become a problem in the future. It is expected that.

Unlike the two-component developing method having the above problems, the one-component developing method containing no carrier particles is easy to downsize and simplify the machine, and the life of the developer like the two-component developing method. There is no problem with the shortness of. Toners used in the one-component developing method include magnetic one-component toner containing magnetic powder inside and non-magnetic one-component toner containing no magnetic powder inside. The non-magnetic one-component toner has a feature that it can be a vivid color toner, and various developing methods have already been proposed.
They are mainly members for imparting triboelectric charge and forming a thin toner layer, which form a thin toner layer on a toner carrier and fly in space with a bias voltage in a non-contact state with an electrostatic latent image carrier for development. To do. However, even though this developing method is a one-component developing method, it is difficult to always maintain a stable toner charge amount and image quality, and there is a drawback that the life of the toner and the developing device is short.

At first, as the magnetic one-component toner, a conductive magnetic toner as disclosed in, for example, US Pat. Nos. 3,639,245 and 3,909,258 was used. Unlike the insulating toner, the developing with the conductive toner uses the electric charge induced by the electric field due to the electrostatic induction action, and therefore, compared to the insulating toner, (1) the influence of image deterioration due to humidity can be eliminated. , (2) A uniform charge can be applied to the toner, so that an image with less background stain and excellent resolution can be obtained. (3) A one-component development that is easy to do is possible. Since it is unnecessary, the structure of the developing device can be simplified and downsized, and (5) both the normal development and the reverse development can be performed with the same toner.

However, in spite of the many advantages as described above, the conductive toner is a plain paper transfer system using electrostatic force, which is widely used in the process using an insulating toner, that is, corona discharge or corona discharge. Plain paper copiers (PPCs) and facsimiles are extremely difficult due to the greatest drawback of a biased conductive or dielectric roller, which is difficult to transfer well to plain paper. The fact is that it is rarely used except for those using the low-efficiency adhesive transfer method. The most successful one-component developing method currently in practical use is the insulating magnetic one-component toner development capable of copying plain paper by electrostatic transfer.

The insulating magnetic one-component toner is classified into contact development in which the toner layer is brought into contact with the electrostatic latent image and non-contact non-contact development. In non-contact development, for example, JP-A-55-18
As disclosed in Japanese Patent No. 656, etc., a thin layer of toner is formed and charged mainly by friction with a toner carrier, which is placed in a non-contact state with a photoconductor and the toner is caused to fly by an electric field to develop. There is a developing method called "jumping development". This method is an excellent method because it makes it easy to downsize and simplify the developing device, but it has a high reliability because it depends on the environment of the image and the dimensional accuracy of the toner layer thickness regulating member is required. There is room for improvement, and there is a problem that the waste toner remaining after transfer onto paper cannot be reused.

On the other hand, as the contact development, for example, a development method called "BMT development method" utilizing triboelectric charging between toner particles, which is disclosed in Japanese Patent Publication No. 59-44627, US Pat. No. 121,931, a developing method utilizing charge injection from a toner carrier, a method disclosed in Japanese Patent Laid-Open No. 54-134640, and a Japanese Patent Application No. 4-105887. There are ways. The developing method disclosed in Japanese Patent Laid-Open No. 54-134640 uses a toner having a surface in which charge transferable regions such as carbon black are mainly scattered in an insulating main region and a developing unit is used. The constituent toner carrier is an insulating one, and the toner is in a chargeable state in which it can be developed by the latent image charge in the image area. The developing mechanism will be described in more detail below. Using magnetic toner particles in which a conductor such as carbon is dispersed, exposed carbon parts are in contact with each other in the electric field of the developing field.
Considering individual toner particles, positive and negative charges are induced in the carbon portion of each toner by electrostatic induction through the contact points. Thus, the toner particles in the charged state capable of contributing to the development develop the latent image when they come into contact with the latent image.

When these developing methods by contact developing are actually tested, it is easy to always obtain a stable image regardless of the use environment, and the mechanical dimensional accuracy of the developing device is also easily roughened. There is a merit in terms of sexualization. Further, in the toner used for non-contact development, a "charging aid" having a role as a carrier in the two-component developing method is added to promote triboelectric charging, but one component using the charging aid is added. In the toner, there is a problem that the collected toner cannot be reused and must be discarded because the mixing ratio of the charging aid in the toner varies depending on the recovered toner after the initial cleaning and after cleaning. In the contact development, the reasons are different depending on the charging mechanism or such a phenomenon does not occur. Therefore, the waste toner can be reused and is a development method suitable for toner recycling.

However, these contact developing methods still have the following problems. (1) There is no problem if the developing speed is slow and the distance between the toner carrier and the electrostatic latent image carrier is small, but in contact development, a phenomenon called fringe, in which toner adheres to the periphery of the latent image, tends to appear. . (2) Since the toner in the fringe portion remains on the electrostatic latent image carrier during electrostatic transfer onto paper, the transfer rate of the toner decreases, which is inefficient.

[0013]

SUMMARY OF THE INVENTION The present invention has a high reliability that it is small and simple, does not require maintenance in particular, and is excellent in environmental stability of an image, and it can make the design accuracy of a machine rough, so that In the contact one-component development method that does not generate waste such as waste toner, it is possible to obtain good printed matter without fringes, mainly when speeding up printing speed or making machine design accuracy rougher. A method of developing a one-component toner that can be used.

[0014]

SUMMARY OF THE INVENTION The present invention provides a method for developing a one-component toner in which a toner on a toner carrier is brought into contact with the electrostatic latent image carrier to visualize the electrostatic latent image. The present invention relates to a method for developing a one-component toner, which has a mechanism for electrostatically separating toner adhered to a non-image portion on an electrostatic latent image carrier after development.

The present invention will be described more specifically. The method for producing a one-component toner used in the present invention includes a biaxial extrusion kneader, a two-roll mill, a binder component containing a thermoplastic resin as a main component, a colorant, and other components optionally added. It is common to perform hot melt kneading using a kneader such as a pressure kneader, then cool and solidify, finely pulverize using a pulverizer such as a jet mill, and adjust to a desired particle size distribution by an air stream classifier or the like. . In recent years, various methods for directly producing toner particles have been proposed by a suspension polymerization method, an emulsion polymerization method, etc., and a toner manufactured by these methods can also be used. The toner has a volume-based average particle size of 5 to 15
It is desirable that it is μ. If the upper limit is exceeded, the image will become rough, and if it is less than the lower limit, the fluidity of the toner will be significantly deteriorated.

The thermoplastic resin may be any of those usually used for toners, and examples thereof include polystyrene-based resins, styrene-acrylic acid ester or methacrylic acid ester copolymers, and acrylonitrile- or maleic acid ester-containing styrene copolymer systems. Examples thereof include polyacrylic acid ester-based, polymethacrylic acid ester-based, polyester-based, polyamide-based, epoxy-based, phenol-based, hydrocarbon-based, and petroleum-based resins.

As the colorant, commonly used pigments and dyes can be used, for example, carbon black, iron black,
Various non-ferrous metal oxides, zinc white, yellow iron oxide, Hansa yellow, disazo yellow, quinoline yellow, permanent yellow, red iron oxide, resole red, watchyan red calcium salt, watchyan red manganese salt, pyrazolone red, lake red C, lake Examples thereof include pigments such as red D, brilliant carmine 3B, dark blue, phthalocyanine blue, and titanium oxide, or nigrosine-based oil-soluble dyes, crystal violet, azo-based metal complex salts, balatin dyes, orazole dyes, and other metal complex salt dyes. Regarding the amount of the colorant added, a necessary amount for imparting the desired colorability to the toner is added, but if the amount added is too large, the free colorant particles become toner carrier,
It is desirable that the content of the toner is 10% by weight or less with respect to the toner in view of problems such as contamination of the electrostatic latent image carrier.

If necessary, various charge stabilizers, magnetic powders, lubricants such as various waxes, and hydrophobic silica can be added to improve the fluidity of the toner. As the charge stabilizer, various charge control agents that have been used in various developing methods using ordinary triboelectrification can be used, and various charge control agents can be used. It has a particle size that does not separate from the toner particles when classified, and imparts a predetermined charge to the toner particles. Examples of such substances include nigrosine-based oil-soluble dyes, crystal violet, triphenylamine, quaternary ammonium salts, azo-based metal complex salts, balatin dyes, and olazole dyes. Further, various pigments conventionally used as colorants, for example, various non-ferrous metal oxides, zinc white, yellow iron oxide, Hansa yellow, disazo yellow, quinoline yellow, permanent yellow, red iron oxide, resole red, watchyan red calcium salt. , Watchzan red manganese salt, pyrazolone red, lake red C, lake red D, brilliant carmine 3B, dark blue, phthalocyanine blue, titanium oxide and the like can also be the charge stabilizer in some cases.

In the case of a magnetic one-component toner, magnetic powder is added to impart magnetic force to the toner particles. The required amount is added depending on the strength of the magnetic field on the toner carrier,
From the relationship between the binding force to the toner carrier and the attractive force to the electrostatic latent image, 20 to 60% by weight of the toner is desirable. As the magnetic powder, various known ones such as various ferrites, magnetites and hematites can be used, and various shapes such as cubic crystal, regular octahedron shape, spherical shape and needle shape can be used, but the toner when dispersed in the toner The particle size is preferably 1 μm or less in view of problems such as uneven distribution of the amount of magnetic powder among particles and generation of free magnetic powder. In terms of magnetic characteristics, saturation magnetization is 50em
The coercive force is not particularly limited as long as it is about u / g or more, but the coercive force is 200 due mainly to the problem of the mobility of toner particles on the toner carrier.
It is preferably Oe or less, more preferably 120 Oe or less and 40 Oe or more. The magnetic powder may be used as it is without any problem, but may be surface-treated with a fatty acid, a silane coupling agent or the like, if necessary.

As a method for forming an electrostatic latent image on an electrostatic latent image carrier, an inorganic photosensitive material such as Se type or a-silicon type,
In addition, the electrostatic latent image is exposed by exposing the image information after evenly distributing the charge by charging the surface of the electrostatic latent image carrier such as an organic photoconductor by using corona discharge etc. Most commonly it is formed. In addition, a method of directly recording an electrostatic latent image on electrostatic recording paper or the like by a needle electrode, an ion flow recording, or the like may be used. Then, the electrostatic latent image can be visualized by bringing the toner carrier holding the toner into contact with the electrostatic latent image.

When a so-called magnetic one-component toner containing magnetic powder inside the toner is used, the toner carrier is
A general mechanism has a plurality of magnetic poles inside and conveys a toner layer regulated by a doctor blade by rotating a conductive cylindrical sleeve. Normal contact magnetism 1
In the component toner development, the developing sleeve used as the toner carrier has roughly two effects: a "developing effect" and a "cleaning (scavenging) effect". The development effect conveys toner particles to the vicinity of the electrostatic latent image,
It is the effect of attaching toner particles to the latent image. At this time, it is necessary to selectively adhere to only the image portion, but in the contact one-component developing method, the toner also adheres to a portion called a fringe that is formed around the image portion of the electrostatic latent image in the form of a fringe. Often. The reason for this is that if the gap between the electrostatic latent image carrier and the developing sleeve, that is, the so-called developing gap is large, the lines of electric force are curved toward the ground side of the electrostatic latent image carrier at the latent image edge portion (fringe portion). That is, an electric field having a polarity opposite to that of the electrostatic latent image is generated. In the case of non-contact one-component toner development, etc., the toner does not adhere to the fringe portion because the charge polarity of the toner is relatively clear, but the charge polarity of the toner is not clear in contact one-component toner development. The toner adheres to the fringe portion because of the large amount of toner. Also in the image area, the toner is excessively attached to the electrostatic latent image due to the electrostatic attraction between the toner particles,
The resolution and gradation are significantly deteriorated. Therefore, it is necessary to have a cleaning (scavenging) effect for removing the toner particles that have excessively adhered. Normally, the cleaning (scavenging) effect is enhanced by increasing the rotation speed of the cylindrical sleeve or rotating the inner magnetic pole at high speed. Therefore, when the developing speed is slow and the cleaning effect is sufficiently working, the toner in the fringe portion disappears and a good image is obtained, but as the developing speed becomes faster, the cleaning effect becomes insufficient and the fringe effect becomes poor. Part of the toner is not completely removed, resulting in deterioration of an image and a decrease in transfer rate.

However, in the developing method according to the present invention, the cleaning effect is unsatisfactory because it has a mechanism for separating the toner adhering to the non-image area on the electrostatic latent image carrier at the latter stage of the developing mechanism. Even if it is sufficient, a good image can be obtained. In the extreme, in the present developing method, the developing sleeve only needs to have the “developing effect” and does not need the “cleaning (scavenging) effect”. That is, it causes clogging due to soft agglomeration of toner, a toner layer thickness regulating member (doctor blade) that requires high dimensional accuracy, and internal magnetic poles that cause toner scattering and complicate the developing device. The rotating mechanism is not particularly necessary. Further, the developing sleeve need only have a "developing electrode effect" for neatly aligning the lines of electric force from the electrostatic latent image, so it may be plate-shaped instead of cylindrical, and if the substrate is conductive. An insulating coating may be provided on the surface that comes into contact with the toner.

When a so-called non-magnetic one-component toner containing no magnetic powder inside the toner is used, the toner cannot be held by using the magnetic force as described above, and therefore gravity or electrostatic force is used. In this case, since the above-mentioned “cleaning (scavenging) effect” is small, it is necessary to make the toner layer extremely thin to suppress the toner adhesion amount. However, since the "cleaning (scavenging) effect" is not required in the present developing method as described above, it is possible to provide a developing device that does not require a toner layer thickness regulating member even for non-magnetic one-component toner. To hold the toner by using gravity, there is a method of placing the toner carrier directly under the electrostatic latent image carrier, and when using static electricity, apply a voltage opposite to the charging polarity of the toner. It is also possible to use an electret or the like which is applied to the developing sleeve or which is charged opposite to the charging polarity of the toner. Also in these cases, the developing sleeve as the "developing electrode effect" is
If the substrate is conductive, the surface may be insulative, and the shape may be cylindrical or plate-like. To realize vivid color toner, it is necessary to make the toner non-magnetic. However, the non-magnetic one-component toner development method proposed so far has the stable image quality and the life of the developing device. It wasn't enough. One of the major features of the present development method is that it enables reasonable non-magnetic one-component development.

The volume resistivity (electrical resistance) of the toner
In general, an insulating toner is used because it is advantageous for electrostatic transfer, but it is also possible to use a so-called conductive toner having a relatively low resistance. When the volume resistivity of the conductive toner is low at about 10 ³ Ωcm or less, the toner layer itself has a developing electrode effect, so the separation mechanism according to the present invention is not necessary, but when it exceeds about 10 ³ Ωcm, fringes still occur. It easily occurs, and the separation mechanism according to the present invention is very effective. Since the conductive toner does not utilize triboelectric charging and therefore has particularly high environmental stability, it is a highly reliable developing method.

In any case, it is preferable that the conductive portion of the developing sleeve as the toner carrier is electrically grounded. For organic and inorganic photoconductors, if there is residual potential on the background due to insufficient exposure, etc., a DC bias of the same polarity as the electrostatic latent image is applied by an electric means for the purpose of preventing scumming. Must be applied.

As a fringe toner removing mechanism, when a voltage having a polarity opposite to that of the toner adhered to the fringe portion is applied to a conductive roller or plate, and the electrostatic latent image carrier after development is brought into contact with or very close to the electrostatic latent image carrier, As described above, since the toner attached to the image area and the toner attached to the fringe area have opposite polarities, the fringe area toner acts as an electrostatic attractive force and the image area toner acts as a repulsive force. The toner can be selectively removed.

Further, although the toner on which the fringe portion is developed has the opposite polarity, unlike the frictional charge auxiliary agent used in the non-contact one-component toner development, the image portion is developed as a component. The exact same toner is only charged to the opposite polarity due to any reason such as mutual friction between toners, electrostatic induction, and charge injection.Therefore, the toner removed from the fringe part is returned to the toner carrier part. , Can be used again. Therefore, it is desirable that the electrostatic toner separation mechanism collects the separated toner and reuses it. As a fringe portion toner removing mechanism provided with such a collecting mechanism, for example, there is a method in which a scraper or a brush is brought into contact with a cylindrical conductive roller to collect and reuse it.

[0028]

The present invention relates to a method for developing a one-component toner in which an electrostatic latent image is visualized by bringing a toner layer on the toner carrier into contact with the electrostatic latent image carrier. It is characterized by having a mechanism for electrostatically separating the toner adhering to the non-image portion on the electrostatic latent image carrier. The contact one-component development method has high reliability that it is small and simple, does not require special maintenance, and is excellent in environmental stability of the image, and also allows the machine design accuracy to be rough, and waste such as carriers and waste toner. It has many advantages of not causing. However, if the printing speed is increased or the design accuracy of the machine (especially the development gap) is made rougher, a fringed image called a fringe is generated in the obtained image, greatly impairing the resolution and gradation. According to the present invention, since the toner in the fringe portion is selectively removed, it is possible to obtain a good image.

Further, by providing such a separating mechanism, the conventional developing sleeve had to have both the developing effect and the cleaning (scavenging) effect. As a result, it is possible to obtain a good image even in a plate shape, for example, without using a developing sleeve having a complicated mechanism.

[0030]

【Example】

Production Example of Magnetic One-Component Toner Toner raw materials having the following formulations were premixed. Parts represent parts by weight. Toner A (insulating magnetic toner) Styrene-acrylic resin (trade name: ALMATEX PA-201, manufactured by Mitsui Toatsu Chemicals, Inc.) 63.0 parts Magnetite (trade name: MG-WMK, Mitsui Metal Industry Co., Ltd.) ) 35.0 parts Charge stabilizer (trade name: Nigrosine Base EX, manufactured by Orient Chemical Industry Co., Ltd.) 2.0 parts

Toner B (conductive magnetic toner) Styrene-acrylic resin (trade name: ALMATEX PA-201, manufactured by Mitsui Toatsu Kagaku KK) 50.0 parts Magnetite (trade name: MG-WMK, Mitsui Metals) Industrial Co., Ltd.) 40.0 parts Carbon Black (trade name: Conductex SC, Colombian Carbon Co., Ltd.) 10.0 parts

3 kg of the above raw materials were mixed with a 20 liter mixer (trade name: Henschel mixer, manufactured by Mitsui Miike Seisakusho Co., Ltd.) at 1500 rpm for 5 minutes. After melt-kneading this with a twin-screw extrusion kneader (trade name: PCM-30, manufactured by Ikegai Tekko Co., Ltd.), it was pulverized with a jet mill and classified with an air stream classifier, with a volume-based average particle size of about 11 μm. 5
A toner sample containing substantially no μ or less and 20 μ or more was used. Toner A is mainly used to improve fluidity,
0.3 part of hydrophobic silica was added to 100 parts of the toner and dry-mixed. When the volume resistivity of these toners was measured, it was 5 × 10 ¹⁵ Ωcm for toner A and 8 × 10 5 for toner B.
It was ⁶ Ωcm.

The volume resistivity of the toner is measured as follows. In a commercially available tablet molding machine for measuring infrared absorption spectrum (circle having a molding internal cross section of 20 mm), 23 ° C.
The toner left in a thermo-hygrostat of 0% RH for 24 hours was about 0.
8 g was put and pressurized with a hydraulic press machine at 400 kg / cm ² , to prepare a circular cylindrical pellet having a thickness of about 2 mm and both end faces having a diameter of 20 mm. A silver paste is applied to the center of both circular end faces of this pellet with a silver paste having a diameter of 10 mm, and one end is grounded. Next, a guard electrode whose one end is grounded is provided along the outer periphery of the pellet, a DC voltage is applied to the main electrode, the current flowing between the main electrodes is directly read by an ammeter, and the volume is determined from the stable current value. The specific resistance value was calculated.

Prototype Example 1 of Copy Tester A print test was actually conducted using an experimental machine which was a remodeled commercial copy machine. As the copying machine, a copying machine using a negatively charged OPC (surface potential −600 V) photoconductor as an electrostatic latent image carrier (hereinafter referred to as photoconductor) was used. Next, a toner carrier (hereinafter referred to as a developing device) having the following structure and setting conditions was experimentally manufactured. Conductive sleeve: Diameter 24mmφ, Variable peripheral speed Internal magnetic pole: Rotatable, 8 poles, 1000 gauss, Rotation speed variable Toner layer thickness regulation blade-conductive sleeve gap: 0.3
mm DC bias -100V is applied to the sleeve. Photosensitive member-conductive sleeve gap: 0.2 mm. Photosensitive member-conductive sleeve peripheral speed ratio = 1: 2.

Example 1 A printing test was conducted using Toner A in the above copying tester. After changing various setting conditions of the developing device,
The toner image on the photoreceptor was as shown in Table 1.

Table 1 Copy test machine test results Conductive sleeve peripheral speed (cm / sec) Internal magnetic pole rotation speed (rpm) (fringe) 6 600 Δ 6 1200 ○ 13 600 Δ 26 600 × 26 1200 1200 Δ The symbols of the copy tester test results mean the following. ◯: No fringe is observed, and there is no problem in transferring as it is. Δ: A fringe is seen, but there is no problem because the fringe portion is not transferred. X: The fringe is remarkably generated, and the fringe part is partially transferred, so that it cannot be used.

Prototype of electrostatic separation mechanism A diameter of 20 mm is provided on the downstream side of the developing device and on the upstream side of the electrostatic transfer mechanism.
The conductive roller of No. 1 was arranged so as to face the photoconductor in a non-contact state. A DC voltage of 2 kV was applied to this conductive roller. Further, the conductive roller is provided with a collecting mechanism for collecting the adhered toner.

When an ordinary electrostatic transfer test was carried out using a copying tester equipped with the electrostatic separation mechanism described above, the conductive sleeve was fixed at a developing speed of 26 cm / sec and the inner magnetic pole rotation speed was 600 rpm. The obtained image was good without fringe.

Example 2 The same test as in Example 1 was conducted using Toner B. Table 2 Copy tester test results Conductive sleeve peripheral speed (cm / sec) Internal magnetic pole rotation speed (rpm) (fringe) 6 600 ○ 6 1200 ○ 13 600 △ 26 600 × 26 1200 ×

The tendency was the same as in Example 1 as described above. Therefore, the test was conducted with a copying tester equipped with an electrostatic separation mechanism similar to that of Example 1 under the developing conditions of a conductive sleeve peripheral speed of 26 cm / sec and an internal magnetic pole rotation speed of 600 rpm. Since the toner B is a conductive toner and is not transferred to plain paper under normal conditions, a transfer paper that has been sufficiently heated and dried immediately before use was used. The image obtained was good, with no fringes, as in Example 1.

Example 3 The same test as in Example 1 was carried out except that the electrostatic separation mechanism was arranged so as to be in contact with the photosensitive member. As a result, the removal of toner in the fringe portion was as good as in Example 1. Met. Further, as an additional effect, it has been found that the transfer rate is increased by about 10% as compared with the case where the electrostatic separation mechanism is arranged in non-contact with the photoconductor.

Example 4 The removal of the fringe toner from the photoconductor is not limited to the above-mentioned roller, and the same effect can be obtained by using, for example, a conductive flat plate arranged so as to face the photoconductor. It was

Example 5 Prototype Example 2 of Copy Test Machine The copy test machine used in Prototype Example 1 of the copy test machine was prototyped by removing the toner layer thickness regulating blade of the developing device. The toner layer thickness regulating blade has an effect of storing necessary toner in addition to the function of forming a toner layer. However, by removing the blade, the function of this storage is provided above the gap between the photoconductor and the sleeve. It will be given to the space. This is referred to as Prototype Example 2 of the copy tester. Using this, the same test as in Example 1 was performed.

Table 3 Copy tester test results Conductive sleeve peripheral speed (cm / sec) Internal magnetic pole rotation speed (rpm) (fringe) 6 600 × 6 1200 × 13 600 × 26 600 × 26 1200 × Toner layer thickness regulating blade When was removed, the amount of toner adhered to the photosensitive member became excessive and the fringe became noticeable. However, by providing the electrostatic separation mechanism as in Example 1, the image after transfer was good.

Example 6 In the development of the prototypes 1 and 2 of the copying tester, considering the developing mechanism, first, in the prototype 2 of the copying tester, the photoconductor and the developing sleeve were opposed to each other. Although the photoconductor is in contact with the toner within a few cm above the portion, the toner actually develops the electrostatic latent image in a very narrow area between the developing sleeve and the photoconductor. I understand. Therefore, it is understood that in the contact development, not only the toner contacts the electrostatic latent image on the photoconductor but also the conductors facing each other with a relatively narrow gap are required. Therefore, it has been found that a conductive flat plate is used instead of the conductive sleeve, and the latent image is developed even if toner is supplied to this gap. However, the toner image thus obtained was not a good image because the toner adhesion was excessive and there were many fringes. However, by providing the same electrostatic separation mechanism as in Example 1 with this, the image after transfer was very good.

Example 7 Production Example of Nonmagnetic One-Component Toner Toner raw materials having the following formulations were premixed. Toner C (insulating non-magnetic toner) Styrene-acrylic resin (trade name: ALMATEX PA-201, manufactured by Mitsui Toatsu Chemicals, Inc.) 93.5 parts Charge stabilizer (trade name: Bontron P-51, Orient) Chemical Industry Co., Ltd. 3.0 parts Phthalocyanine Blue (trade name: Rionol Blue FG7305, Toyo Ink Mfg. Co., Ltd.) 3.5 parts

This was melt-kneaded, pulverized, and melted in the same manner as in Example 1.
Air-flow classification is performed to obtain a toner sample having a volume-based average particle size of about 11 μm and substantially not containing 5 μ or less and 20 μ or more,
Toner 1 mainly uses hydrophobic silica to improve fluidity.
0.3 part was added to 00 parts and mixed by dry mixing. Toner C
The volume resistivity of was measured to be 8 × 10 ¹⁵ Ωcm.

Prototype Example 3 of Copy Test Machine Since toner C is a non-magnetic toner, Prototype Example 1 of copy test machine
In No. 2 and No. 2, the developing device was not suitable because it could not hold the toner.
Then, a developing device as shown in FIG. 1 was prototyped, and a printing test was conducted in the same manner as in the prototype 1 of the copying tester. As a result, the toner image obtained in the same manner as in Example 6 had excessive toner adhesion. There were many fringes and the image was not good. However, by providing the same electrostatic separation mechanism as in Example 1 with this, the image after transfer was very good.

[0049]

[Brief description of drawings]

 FIG. 1 shows a developing device.

[0050]

[Explanation of symbols]

 1: Toner carrier 2: Conductive support 3: Electric film 4: Toner 5: Electrostatic latent image carrier 6: Electrostatic latent image

Claims (3)

[Claims] 1. A method for developing a one-component toner for developing an electrostatic latent image by bringing a toner layer on the toner carrier into contact with the electrostatic latent image carrier, and carrying the electrostatic latent image after development. A one-component toner developing method having a mechanism for electrostatically separating toner attached to a non-image portion on the body. 2. The one-component toner developing method according to claim 1, wherein the toner carrier does not have a toner layer thickness regulating member for forming a toner layer on the toner carrier. 3. The mechanism for electrostatically separating the toner adhering to the non-image portion on the electrostatic latent image bearing member after development has a mechanism for collecting the separated toner. The one-component toner developing method described.