JPS58117553A - Developing device - Google Patents

Abstract

PURPOSE:To suppress unevenness of inclination, picture drift, and texture staining and to increase picture density by using a developer which contains <=2wt% toner particles of 5-10mum in volumetric mean particle size and >=15mum in particle size. CONSTITUTION:The developer 4 charged by friction is conveyed on a sleeve 2 in a layer 4a to reach a developing area D. At this time, the developer on the sleeve, i.e. toner particles stick to an electrostatic latent image formed on a photoreceptor 9 to make the latent image visible. As the volumetric mean particle size of the toner particles increases more and more, the amount of friction charging of the toner particles decreases more and more. When the developer has <=10mum volumetric mean particle size, the visible image is sharp and has such picture density that (unevenness of inclination) and (picture drift) are eliminated or less. Further, the visible image has high quality when the developer contains <=2wt% toner particles having 5-10mum volumetric mean particle size and >=15mum particle size based upon the whole of the developer.

Description

[Detailed description of the invention]

The present invention relates to a developing device that visualizes an electrostatic latent image using a developer. Electronic copying machine, electrostatic recording device or other various recording devices?
A trowel is used. Developing devices of the above-mentioned type have been well known in the past, and in this type of developing device, various types of developing devices can be used, such as developers made of toner particles containing magnetic material or toner particles substantially free of magnetic material. agent is used. In this case, it has been known that the image quality of the visible image changes depending on the particle size of the toner particles when any type of developer is used. By using a developer that does not contain the following toner particles or has a reduced content, it is possible to remove so-called background stains in which toner particles adhere to the background part of the flexible image (the part where no image will be formed) by kneading. Configurations have been proposed to try to prevent this. As described above, the idea of using a developer that does not contain small-sized toner particles or contains only a small amount of small-sized toner particles has been known for a long time, but on the other hand, little consideration has been given to large-sized toner particles. It wasn't worth it. However, according to studies conducted by the present inventors, when a developer consisting of toner particles with a large particle size is used, not only the texture of the visible image developed by kneading becomes rough, but also the following disadvantages occur. It became clear that That is, when using a one-component developer consisting of a toner with a relatively high specific volume resistivity, before using it for development,
Although it is necessary to forcibly charge the developer to a predetermined polarity, large-sized toner particles inevitably have a small amount of charge, and the quality of the neppy image deteriorates based on this phenomenon. This disadvantage is caused by the magnet that generates the rotating magnetic field.
, in the J'lj image device of the type in which the developer is embedded, this phenomenon appears conspicuously. In a developing device that performs fl'7((,4+) by conveying it by magnetic force,
Toner particles with a large particle size are attracted to the magnet by a relatively large force (p7).
? - If a developer containing a large amount of large-diameter toner particles is used, the density of the visible image will inevitably be lowered because the probability of the toner adhering to the image decreases. The decoy is φ) based on the above h1 knowledge, and contrary to the conventional idea, it is necessary to use a developer that suppresses the content of large toner particles to a certain amount or less. Because of this,
It is an attempt to eliminate the above-mentioned drawbacks. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A developing device to which the present invention can be applied will be further clarified with reference to the drawings, and advantageous embodiments of the present invention will also be explained. FIG. 1 shows an example of a configuration in which a viewing device W1 to which the present invention is applicable is used in an electronic copying machine. The developing device 1 shown here accommodates a developer carrier configured as a developing sleeve 2, a roller-shaped magnet 3 disposed inside the developing sleeve 2, and a one-component developer 4 made of toner particles. do. It has a raccoon tank 5. In this example, high-resistance toner particles, at least a portion of which are made of a magnetic material, are used as the toner particles constituting the printing press material 4. magnet 3
The magnetic poles S and N have opposite polarity alternately along the circumferential direction of the sleeve 2. In the illustrated developing device, the magnet 3 is rotated clockwise and the developing sleeve 2 is rotated counterclockwise. 6 is a magnetic leveling plate pressed against the developing sleeve 2; 7 is a doctor disposed at a predetermined gap from the sleeve 2; and 8 is a scraping plate for scraping off the developer on the sleeve 2. On the other hand, at a position facing the developing sleeve 2, a latent image carrier configured as a drum-shaped photoreceptor 9 is located, and this photoreceptor 9 is rotated clockwise. When the copying operation starts, the photoreceptor 9''1 is rotated clockwise as described above, and at this time, an electrostatic latent image is formed on the surface of the photoreceptor by bamboo image forming means (not shown). In the Of+l image device 1 in which the latent image moves to the developing area between the developing sleeve 2 and the photoreceptor 9, !0:, the developing sleeve 2 and the 41-degree stone 3 are rotated in the aforementioned directions. As a result, a part of the developer 4 in the tank 5 is carried by the developing sleeve 2 and transported in the counterclockwise direction. When passing, the developer is subjected to a +4 scraping action by the doctor 7, and the amount of the developer carried and dripping is regulated to approximately 1.Then, the developer passes between the magnetic leveling plate 6 and the sleeve 2. When passing through a minute gap, the developer in the sleeve 2-1 is pressed by the leveling plate 6 to regulate its thickness, and also to maintain a predetermined polarity (for example, the electric charge forming the electrostatic latent image mentioned above). In this case, in this example, the leveling plate 6 is made of the magnetic material A, and since the magnet 3 rotates and a rotating magnetic field is generated, the magnetic The leveling plate 6 vibrates while being attracted by the magnet 3, and the sleeve 2
The minute gap between the flattening plate 6 and the leveling plate 6 changes periodically, so that the developer passing through this plate is subjected to frictional force while keeping its thickness extremely thin. Charged. Since the developer is triboelectrically charged in a thin layer in this way, the developer layer can be charged relatively uniformly over the entire thickness σ direction. As mentioned above, the charged and large developer is conveyed through the two sleeves in the layer 4a and reaches the development area mentioned above, and at this time,
The developer, or toner particles, on the sleeve adheres to the electrostatic latent image formed on the photoreceptor 9, and the latent image becomes visible. In this case, since the toner particles are forcibly charged by friction in advance as described above, the toner particles can electrostatically adhere to the electrostatic latent image. Ji image removal that needs to be done usually has a specific volume resistivity of lol
. Ω-m or more, especially 1013 to 014 Ω-m or more). Before the toner particles adhere to the plate 9, the toner particles continue to be transported on the sleeve 2 and returned to the tank 5, where they are scraped off from the sleeve 2 by the scraping plate 8vC. Furthermore, the first
In the developing device shown in the figure, the gap between the sleeve 2 and the photoreceptor 9 can be, for example, about 100 μm, and the thickness of the developer layer on the sleeve after controlling the layer thickness can be about 20 to 30 μm. . The structure shown in FIG. 1 and its operation are roughly as described above. In this case, if the magnetic developer is conveyed by generating a rotating magnetic field using the magnet 3 as in the device shown in FIG. 11.1 image average of lc or visual image
It is possible to relatively increase the sex level (11 and 5). However, when pre-charging the developer, i.e., toner particles, if the amount of charge given to each toner particle is insufficient, toner particles electrostatically adhere to the latent image, causing Coulomb force to act on the latent image. However, as the magnet 3 rotates, the toner particles adhere to the latent image and move over it. The density decreases significantly, and there is a possibility that so-called "tilt unevenness" may occur, causing density unevenness in the visible image. This phenomenon becomes more noticeable when a large amount of toner particles adhere to the edge portion of the latent image, that is, the latent image portion close to the background area, and in some cases, toner particles protrude from this edge area and reach the background area. This can also cause so-called "image bleeding" in which toner particles run off. It is clear from the above description that in the developing device shown in FIG. 1, if the amount of charge on the toner particles is insufficient, the quality of the visible image may deteriorate. In this case, the amount of charge of the toner particles is greatly influenced by the particle size of the toner particles, and the larger the particle size of the toner particles, the smaller the amount of charge l becomes. This will be made clear by explaining the progress of an experiment conducted using the developing device shown in FIG. 48 parts by weight of styrene/acrylic resin, 50 parts by weight of magnetite as a magnetic powder, and 2 parts by weight of a charge polarity control agent were kneaded and then ground to obtain toner particles, which were used as a developer. By preparing four kinds of developers having toner particles of 71 and a total average particle diameter of 0, the volume specific resistivity of one toner particle was approximately 10'4 Ω-(7)/ζ. Next (1st
The rotation speed f of the magnet 3 of the developing device shown in the figure is 150flrp
m, developing sleeve 20 revolutions wo 1000 r p nI
SK'(81/1') with a thickness -gt of 0.2 mm. We investigated the relationship between the volume average particle diameter of particles and their triboelectric charge, and found that the second
The results shown in Figure R were obtained.The amount of charge was measured using the blow-off method, and as is clear from Figure 2, the larger the volume average particle diameter of the toner particles, the more the frictional electrification of the toner particles increases. Next, we examined the particle size of the toner particles and the image quality of the visible image, and found that if a developer with a volume average particle size of 10 μm or less was used, the image on the left as explained earlier A sharp visible image with no or little density unevenness and image blurring can be obtained; conversely, if a developer with a larger volume average particle diameter is used, tilting unevenness and image blurring will occur. It has been revealed that high-quality visible images can be obtained when toner particles that do not deteriorate significantly are added in an amount of 2% by weight or less based on the entire developer. The structure of the developer is characterized by the above-mentioned structure.By the way, in the apparatus shown in FIG.
The phenomenon of "image deletion" occurs because the developer is strongly attracted to the magnet 3, so whether or not these phenomena occur depends on the amount of charge on the toner particles as well as the amount of charge on the toner particles. It also depends on the amount of magnetic material contained in the toner particles, and the higher the content of magnetic material in the toner particles, the more the toner particles become
Therefore, uneven tilting and image deletion are likely to occur. In this case, the content of magnetic material in the toner particles is
In addition to the allocation of the magnetic material in each toner particle, it also depends on the total volume of each toner particle, in other words, the particle diameter. This is because if the diameter of the toner particle is small and the volume is large, the total magnetic material contained in the toner particle (11-) also increases. , the quality of the visible image is affected, but the ampholytic content (weight %) in each toner particle is within the range of normal allocations, and magnetic material is added to toner particles at particularly high allocations than necessary. A developer consisting of toner particles with a small particle size, i.e., a volume average particle size of 5 μ to 10 μ, and a particle size of 151 tons or more, with a weight coefficient of 2 or less. By using a developer having a diameter of 1, it is possible to effectively suppress tilt unevenness and image deletion.If the particle size of the toner particles is made relatively small in this way, generally each toner particle is It can be said that phenomena such as image blurring can be suppressed by reducing the absolute fineness of the magnetic material contained in the toner.
The following advantages can also be obtained by using (2) A developer having a volume average particle size of 5 μ to 10 μ and 2% or more of toner particles with a particle size of 15 μ or more is smaller in diameter than the toner particle size of conventionally used normal developers; By using such small-diameter toner particles, it is possible to improve the printability by making the visible image finer. In addition, since the toner particles have a small diameter, even if they adhere to the skin a little, they do not make any noticeable stains, and it is possible to substantially reduce skin stains. ■ As explained earlier, if the toner particles are small, the total amount of magnetic material contained in each toner particle will be relatively small, and therefore the force that attracts the toner particles to the magnet will be relatively small. Therefore, the probability that toner particles will adhere to the layer image is high.
The density of the visible image increases. ■ When using a high-resistance developer, as in the device shown in Figure 1, the developer must be made thin in order to charge it uniformly. This can be relatively easily made into a thin layer, thereby achieving uniform charging of the developer and, by extension, reduction of background stains. If the particle size is small, the developer can be made into a thin layer relatively easily, and the burden on the leveling plate 6 can be reduced. This also applies to the case where the developer is made into a thin layer and charged by means other than the means shown in the I''IfXIfX effect diagram.The above is the structure according to the invention according to the structure shown in FIG.
Although examples and their effects have been described, the invention can also be applied to various types of developing devices other than those shown in FIG. For example, as shown in FIG. 3, there is also a developing device 1 for a copying machine in which the photoreceptor 109 is formed of an endless belt-like VC cedar wrapped around two rollers 10 and 11.
In that case, at least the surface of the roller 10 facing the developing sleeve 2 may be made of an elastic material such as rubber, and the gap between the developing sleeve 2 and the photoreceptor 10q may be set to approximately zero. The other configuration in FIG. 3 is substantially the same as that in FIG. 1, and by using toner particles having the above-mentioned particle size as the developer 4 in the developing device, the effect described above can be achieved. A similar effect can be obtained. In FIG. 4, a belt-shaped photoreceptor 109 is wound around the rollers 10, 11, 12 of 3-), and the developing sleeve 2 is placed in the photoreceptor portion between the two rollers 10, 11.
The doctor 7 (FIG. 1) is omitted, but the other constructions are substantially the same as in FIG. 1. Therefore, the present invention can also be applied to the developing device IK shown in FIG. 4 in the same way as the embodiment described above. In FIG. 5, the photoreceptor 109 is wrapped around the four rollers 10 to 13, and the developing sleeve 2 or the photoreceptor 109
[[! Contact is made through the image agent. 1, sleeve 2, inner thigh, 1, multiple magnets 1
03 is fixed immovably. The other configurations are the same as in FIG. 4. When the magnet is fixed and tilted in this way, the above-mentioned tilt unevenness and image deletion are less likely to occur than when it rotates, but by applying the invention to this developing device, A similar charge amount relationship to the toner particles as shown in Fig. 1 is obtained, and a visible image with fine grain and rich sharpness and less background staining is obtained. Mani 1 Developing device shown in Figure 5

[For C, magnet] 03
is fixed, so each magnet 1031/(: The spikes of the developer located opposite to each other become large, and therefore, in order to give a sufficient amount of charge to the developer, the rake plate 6 and the magnet]0 :
It is necessary to strengthen E11's energy between 3 and V.
Rubbing generally increases the force acting on the leveling plate, making it more likely to be damaged, but if a developer with small-diameter toner particles is used, as described above, the leveling plate can be easily damaged. It is possible to reduce the burden and reduce the possibility of damaging the break-in and developing sleeve. Further, as shown in FIGS. 4, 5, and 6, the developing sleeve 2 is supported by the upper body supporter 4 and the dielectric layer J5 provided therebetween. number of microelectrodes J
6, and these microelectrodes 16 are connected to the conductive support 1.
In addition to electrically insulating the microelectrodes from each other, if the microelectrodes are also substantially insulated from each other, the line image of the p-electrode latent image (the latent image) becomes -density V. Although it is possible to obtain a high-density visible image even from a relatively low-density thin line image on an original, the invention can be applied to a developing device having such an h-developing sleeve without difficulty. , by applying the invention to a device that uses a mother developer as the developer and in which the surface of the developing sleeve is made of a rigid body,
1? Although a specific example has been explained, as shown in FIG. The present invention can also be applied to a developing device which carries out development by holding a triboelectric charging member IOi (Thus, this developer is charged while being made into a thin layer, and is rubbed against the photoreceptor 9. In this case, among the effects described above, the effects that can only be obtained by using magnetic development cannot be obtained with the apparatus shown in FIG. 7, but the other effects can be obtained as they are. Ma1ζ,
The surface of the sleeve 2 shown in FIG. 7 is normally formed with minute irregularities, but if these irregularities are thick, it becomes difficult to thin the developer, and conversely, the irregularities If the size is too small, toner particles with a large particle size will not be able to pass between the triboelectric charging member 106 and the sleeve 2.If the size is too small, the toner particle size will be small, so the layer thickness of the developer will be reduced. Even if the unevenness is made smaller in order to reduce the thickness of the sleeve, it is possible to reduce the inconvenience that toner particles cannot pass between the frictional charging member and the sleeve. Thank you, for the equipment shown in Figures 4, 5, and 7.
/Here, the developer on the sleeve 2 was brought into contact with the photoreceptor. Since the so-called scavenging effect of removing toner particles can be sufficiently obtained, it is possible to particularly effectively suppress skin stains.Therefore, it has a 41-effective effect on the occurrence of skin stains caused by scraping using small-diameter toner particles. Can be suppressed. Next, although it is directly related to non-invention, I will briefly explain the relationship between the content of magnetic material in each toner particle and the image quality of the visible image in Reference 1. Even if it is. First of all, a developer consisting of toner particles having an average particle size of 12μ was prepared by changing the blending ratio of the toner particles with the resin (!: magnetic powder), which was explained earlier in connection with FIG. 1 and used in Example 1C. The developing device shown in Fig. 1 is used to perform a developing operation using these developers. On the other hand, it has been found that in toner particles with a large amount of magnetic material, these phenomena appear conspicuously. As a result of increasing the ratio of resin, the amount of frictional electrification of the toner particles increases and the force with which the toner particles are attracted to the magnet 3 decreases (Figure 8f shows the magnetic powder in each toner particle). (This is a graph showing the relationship between the content ratio (weight %) and the amount of frictional electrification).For this reason, in a developing device that uses a rotating magnet, the amount of water required to transport the developer on the sleeve 2 is It can be seen that a high quality visible image can be obtained by applying a minimum magnetic force to the toner particles and by increasing the electrostatic charge on the toner particles. In addition to considering the amount of magnetic material in the toner particles, it is also necessary to consider the magnetic force of the magnet. Using the same developer, we performed development with a magnet of 700 gauss and 120 gauss, and the result was 700 gauss. However, phenomena such as tilt unevenness are small, and the problem of the amount of magnetic material content in a single particle of 7i'oF is not directly related to non-invention, but This condition can be achieved even by non-invention. 1. To apply the present invention to various types of developing devices
Although the simple example has been explained, the non-inventive one is also a pond-type developing device l.
/ can also be applied, for example, when F
3J4 charges are injected into the band*c/*, or friction between the developing sleeve and toner particles is used to frictionally charge the developer, or a corona discharger is used to charge the developer. The present invention can also be applied to a developing device using nine electromagnets instead of a magnet, or a developing device in which a magnetic IC historical image sleeve is immovably identified. Furthermore, there are also devices in which the developer carrier is formed in the form of a belt rather than a sleeve, the developing device 1 in an electrostatic recording device, or the developing device VC in a direct copy type VT recording device in which the layered image carrier is used as the final copy. Applicable. -f* 3M Using something made of low-resistance toner particles as a wound (also by applying the invention, we can obtain the effect of the invention that a fine-grained hardenable image can be formed) As can be seen from the above explanation, according to non-invention, the intended purpose can be achieved with a simple configuration.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a developing device to which the invention can be applied, Fig. 2 is a graph showing the relationship between the volume average particle diameter of toner particles and the frictional electrification setting, and Figs. 3 to 5 are the same as Fig. 1. is a sectional view showing a different developing device, FIG. 6 is an enlarged schematic sectional view of the developing sleeve shown in FIGS. 4 and 5, and FIG. 7 is a sectional view showing another developing device. FIG. 8 is a graph showing the relationship between the content of magnetic material in toner particles and the amount of triboelectric charge. 1... Developing device 4... Purifying the developer 1111 (no change in content) Fig. 1 Fig. 2 [nu 1 Fig. 4 Fig. 5 Fig. 8 →F Procedure Amendment (Method) % Formula % 2 Name of the invention Developing device: (Relationship to the person making the amendment Patent applicant address 1-3-6 Nakamagome, Ota-ku, Tokyo Name (67)
4) Ricoh Co., Ltd., Managing Director 1st Address: 3, Chugin 5th Hill, 1-9-9 Nishi-Shinbashi, Minato-ku, Tokyo 105
Floor Ta (501) No. 4887 April 9, 1980 Shipment date April 27, 1982 Subject to amendment 6 Contents of amendment 7

Claims (1)

[Scope of Claims] In a developing device that converts an electrostatic latent image into a PR image using a one-component developer containing toner particles, toner particles having a particle size of 15 μm or more are added to the entire developer. 2% by weight
The following and toner particles. The above-described developing device is characterized in that the particles have a volume average particle diameter of 5 μ to 10 μ.