JPH0225880A - Developing device - Google Patents

Abstract

PURPOSE:To form a satisfactory thin layer by arranging a second magnetic pole having specific magnetic forces at a prescribed angle to a first magnetic pole and simultaneously, arranging a developer regulating member and the second magnetic pole at a prescribed angle. CONSTITUTION:A first magnetic pole 92 is arranged in a position faced to an electrostatic latent image carrier 1, a second magnetic pole 91 has the magnetic force at 400-900 gauss on a surface at a developer carrier 3, it is arranged in the position at 120 deg. or above and 180 deg. or below in the rotating direction of the developer carrier 3 form the center of the first magnetic pole 92, a developer regulating member 6 is made to abut on the developer carrier 3 in a prescribed position, and the arrangement is executed so that the angle made between the abutting part and the center of the second magnetic pole 91 can be made into 30-90 deg.. When a developer carrier 1 is rotated, a toner 4 is held on the surface of the carrier 3 by the magnetic force of the second magnetic pole 91, carried along with the rotation of the carrier 3 and regulated by the press-contact force of the developer regulating member 6 to the carrier 3. Thus, a satisfactory layer thickness can be formed.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an electrophotographic copying apparatus, particularly to a display device for forming an image record, and a developing device applicable to various apparatuses such as printers and facsimile electrophotographic apparatuses. [Prior Art] Various types of dry-component developing devices have been proposed and put into practical use. However, in any of the development methods, it is extremely difficult to form a thin layer of dry component developer, and for this reason, a developing device has been configured with a relatively thick layer. However, as improvements in the sharpness, resolution, etc. of developed images are now being sought after, it is essential to develop a method for forming a thin layer of a dry component developer and an apparatus therefor. As a conventionally known method for forming a thin layer of dry component magnetic toner, Japanese Patent Application Laid-open No. 42141/1984 has been proposed and has been put to practical use. A developing device using this proposed method has a layer thickness adjusting means using an elastic rubber blade as a developer regulating member, and the elastic rubber blade is used as a developer sleeve as a toner support. The toner support is pressed with a predetermined pressure in the longitudinal direction of the surface to supply a toner layer with a uniform thickness onto the surface of the toner support. [Problem to be solved by the invention] However, in a practical machine using the above conventional example,
Since all of them employ a so-called thermal fixing method in which fixing is performed using a heat roller heated to about 180° C., there are drawbacks in reducing the size and power consumption of image forming apparatuses. Therefore, it is desirable to use toner that has high triboelectric charging ability and can be fixed with low power consumption. However, when this type of toner is used, the toner may fuse to the developing device, that is, the toner may fuse to the sleeve. The problem was that it was easier. The present invention solves the above-mentioned problems of the conventional device, allows the use of toner that can be fixed using pressure or low power consumption, and does not cause the toner to fuse to the sleeve. The purpose is to provide a developing device. [Means for Solving the Problems] The present invention is aimed at achieving the above objects. an electrostatic latent image carrier that carries an electrostatic latent image, a one-component magnetic developer that visualizes the electrostatic latent image, and a developer carrier that carries and conveys the developer; a magnetic field generation means fixed within the developer carrier; a developer supply means for supplying the developer to the developer carrier; and a developer supply means disposed in the developer supply means to supply the developer to the developer carrier. In the developing device having a developer regulating member that regulates the layer thickness of the developer, the magnetic field generating means includes two magnetic poles, and the first magnetic pole is disposed at a position facing the electrostatic latent image carrier. and the second magnetic pole is 400 Gauss or more on the surface of the developer carrier,
It has a magnetic force of 900 Gauss or less and is disposed inside the developer supplying means at a position of 120 degrees or more and 180 degrees or less from the center of the first magnetic pole in the rotational direction of the developer carrier, and The developer regulating member contacts the developer carrier at a predetermined position, and is arranged such that the angle between the contact portion and the center of the second magnetic pole is 30 degrees or more and 90 degrees or less. , consists of: [Function] When the developing device configured as described above is started and the developer carrier rotates, the one-component magnetic toner introduced into the developer supply means generates a magnetic field fixed in the developer carrier. It is held on the surface of the carrier by the magnetic force of the second magnetic pole of the means. It is conveyed as the carrier rotates. The toner is further
The developer is regulated by the pressing force of a developer regulating member disposed in the developer supplying means against the developer carrier, and is formed to have a predetermined layer thickness. [Example] Hereinafter, the present invention will be described in detail based on the accompanying drawings. FIG. 1 shows an embodiment of a developing device according to the present invention. In the figure, 1 is a drum 1 serving as an electrostatic latent image carrier carrying an electrostatic latent image, and has an insulating layer or a photosensitive layer on its surface. In this embodiment, the tram 1 is a photosensitive drum in which an oPc photosensitive member is coated on the surface of an aluminum drum having a diameter of 30 I and a thickness of 0.8 am. The electrostatic latent image 2 is formed by uniformly charging the surface of the drum l by a known method such as corona charging, and then exposing the drum to imagewise light such as halogen light or fluorescent light through a lens in an analog manner. Ru. Note that the electrostatic latent image is formed not by this method but by one method, for example, an LED.
It can also be formed by any other method, such as a method of performing digital image exposure using an array, a liquid crystal shutter array, or a laser beam, or a method of forming an electrostatic charge dot pattern using a needle electrode or the like. The drum l has a circumferential speed of 52 mm/s in the direction of arrow a in the figure.
The electric potential of the electrostatic latent image on one surface is the dark area Te VI, =
-700V, bright area TE V+, = -200V ``t'' exists.Although not shown, the drum 1 is grounded. 3 is a developing sleeve as a developer carrier.The developing sleeve 3 is For example, it is a non-magnetic sleeve made of aluminum or the like with a diameter of 16mm and a thickness of 0.8mm.The surface is processed with, for example, #600 blast particles, and the JIS 10 point average roughness is R2 = 2. .OJA Maro.It is desirable that the unevenness formed by this process be uniform, and it is desirable that R2 be smaller than the average particle diameter of the toner particles 4.The developing sleeve 3 is rotatably supported by a bearing (not shown). ,-as an example, peripheral speed 60■/s
It rotates at ec (circumferential speed ratio of drum 1.18 times) in the direction of the arrow in the figure. Further, the developing sleeve 3 is connected to a power source 5 capable of superimposing an AC bias on a DC bias, and an oscillating electric field is formed between the developing sleeve 3 and the drum 1. According to experiments, Vpp=50D~3.000V,
It is appropriate that f = 500 to 3.0 OH. In this example, Voc=-350V, VFP=1.
:100V. A bias of 1.600 Hz is applied. Further, the developing sleeve 3 has a developing gap g with respect to the tram l.
They are supported facing each other with a gap g of 150
Approximately gm ~ 500μ■ is appropriate, and in this example,
A gap g of approximately 250 l was set. On the other hand, an elastic blade 6 as a developer regulating member has one end fixed to the developing sleeve 3 by a support 7, and is brought into contact with the developing sleeve 3 in the opposite direction, that is, in a shape that causes the elastic blade 6 to warp. ing. The elastic blade 6 is, for example, a rubber blade with a hardness of 50 to 800, and in this embodiment, the elastic blade 6 has a thickness of approximately
urethane rubber was used. Reference numeral 9 denotes a permanent magnet (magnet roller) serving as a magnetic field generating means, which is inserted into the developing sleeve 3 and has two magnetic poles 91 and 92 held at the positions shown in the figure. Even when driven, it remains fixedly held at the position shown in the figure. The magnet roller 9 may be provided with an electromagnet instead of a permanent magnet. Unlike multi-polar magnet rollers, which are made by pasting multiple magnets together, such two-pole magnet rollers can be made from a single magnet, so they are easy to manufacture, and the magnetism exerted by the magnetic poles is easy. The force setting conditions are also relaxed. In this embodiment, a magnetic roller was used in which the 91st pole had a peak of 900 Gauss and the 92nd pole had a peak of 650 Gauss on the surface of the developing sleeve 3. The magnetic pole 92 is disposed on the upstream side of the contact portion 10 with respect to the rotational direction of the developing sleeve 3 . The one-component magnetic toner 4, which is a developer, is held on the surface of the developing sleeve 3 by the magnetic force of the magnetic pole 92, and as the developing sleeve 3 rotates in the direction indicated by the arrow, the contact portion between the elastic plate 6 and the developing sleeve 3 is 1o. The amount of toner 4 to be conveyed is further regulated by the pressing force of the first elastic blade 6 against the developing sleeve 3, and furthermore, the toner 4 is subjected to a tribo effect, so that the toner 4 becomes a predetermined layer thickness thinner than the gap between the developing sleeve 3 and the drum 1, and is developed. It is applied onto the surface of the sleeve 3. The toner 4 formed to a predetermined layer thickness is conveyed to the developing section, that is, the closest portion between the developing sleeve 3 and the drum 1 where the first magnetic pole 91 is disposed, and the electrostatic latent image 2 described above is transferred to the developing section by known means. Develop. In this embodiment, using the bias conditions described above, the toner 4 is repeatedly attached to and detached from the drum 1 using a so-called jumping development method to finally obtain an image corresponding to the potential of the latent image. is used. Further, the above-mentioned pressing force is suitably about 5 to 50 g/cm, preferably 25 g/cm per unit thickness. The toner 4 that has contributed to the development is collected again into the container 8 by the rotation of the developing sleeve 3. FIG. 2 is a partially enlarged view showing the developing device of the present invention in more detail. In FIG. 2, a straight line m connects the center O of the developing sleeve 3 and the center of the developing pole 91 of the first magnetic pole. The straight line or straight line n is a straight line connecting the center 0 of the developing sleeve 3 and the center of the transport pole 92 as the second magnetic pole, or a straight line or a straight line connecting the center 0 of the developing sleeve 3 and the center of the developing sleeve 3 at the contact portion 10. It is a straight line connecting the upstream part in the rotation direction.Also,
The angle formed by n when viewed from a straight line is 0 The angle formed by straight lines m and n is ψ. The toner 4 held on the surface of the developing sleeve 3 by the magnetic force of the 6WI pole feed 92 rotates in the direction of the arrow mark of the developing sleeve 3. The toner is conveyed to the contact part 10 by the elastic blade 6, and the toner is organized by the pressing force of the elastic blade 6 against the developing sleeve 3.
Although regulation and further tribodding are performed to obtain a predetermined layer thickness, the l-ner 4 that could not pass through the contact portion 10 is returned in the direction of arrow C in the figure. 5 In this embodiment, -component magnetic toner 4 and 1) are capsule toners capable of pressure fixing or low humidity heat fixing.
is used. This Capsule 1 Henna consists of a core material whose main component is wax to improve fixing properties, and a fluorine-based 1,000 chloride-based mercury contained on the outside of the core material to improve development properties. Functional separation N with positive control resin Bukoa as a shell! This toner is a one-component magnetic capsule toner with a '+' average particle size or approximately 11 particles.6 In addition, this toner can also have a coloring material or magnetic material mixed into the core material if necessary. Heat fixing is also possible as long as the linear pressure is about 5 kg/cm or more and the temperature of the L-1 roller is about 80° C. or higher. Further, the toner 4 is applied to the core material 100 in this embodiment.

[80% (weight ratio) of magnetic materials are mixed. This is because, as described above, since the toner 4 is of a functionally separated type, the toner is tribo-imposed excessively, so that a larger amount of magnetic material is mixed than in a single-component magnetic toner produced by a normal pulverization method. However, if the mixing ratio of the magnetic materials is too large, the fixing performance deteriorates, so a mixing ratio of 4L was used as a preferable range for both. Through experiments, the inventors found that when these toners are used, the toner fusion is caused by the behavior of the toner becoming inactive in the microspace on the L flow side of the contact portion IO and the cohesiveness increasing. It was found that this occurs. Furthermore, even when the magnetic force of the transport pole g2 is too strong, the adhesion force of the toner itself to the developing sleeve 3 becomes too strong, causing fusion. In other words, in order to prevent fusion, the transport pole 92 must be at a f or more than 900 Gauss on the surface of the developing sleeve 3.
It was confirmed that it must be done. Molno, 900
If a magnetic force exceeding Gauss is generated at the transport pole 92, no matter how the contact conditions of the elastic plate F6 with the developing sleeve 3 are changed, the toner 4 will stand up too much at the transport pole 92, and the toner 4 will cause Strongly press the L-ner 4 adhering to the surface ζ of the developing sleeve 3.
Press to the side. Since the developing sleeve 3 is rotating in the direction of the arrow, the toner 4 is fused to the surface of the developing sleeve 3 due to friction, pressure and heat generated at that time, and is completely stuck to the surface of the developing sleeve 3. . Furthermore, if the transport pole 92 is weakened too much to prevent fusion, the amount of toner 4 supplied will not follow suit no matter how the contact conditions of the elastic blade roller against the developing sleeve 3 are changed, resulting in solid black etc. When copying an image that consumes a lot of toner, only a low-density image can be obtained. In other words,
It has been confirmed that the transport pole 92 must have a pressure of 400 Gauss or more on the surface of the developing sleeve 3, and in combination with the above experimental facts, it has been found that the transport pole 92 must have a pressure of 400 Gauss or more and 900 Gauss or less. Furthermore, even if the transport pole 92 is above 400 Gauss and below 900 Gauss, if the angle θ is not within an appropriate range, the behavior of the toner in the direction of arrow C in the figure will deteriorate, causing the contact portion 10 to deteriorate.
: Microspace on the flow side] It was also found that 1-toner was successful in 1, and toner fusion still occurred. In other words, θ is 30
If the magnetic pole is less than 100%, even if the transport pole 92 is within the above-mentioned preferable range, the toner will stand up on the developing sleeve 3 of the magnetic pole and will prevent the toner 4 from returning in the direction of the arrow C. Backing of the toner 4 occurs in the micro space 11 on the upstream side of the contact filO, and the same toner rubs against the developing sleeve 3 many times, so that the surface 1 of the developing sleeve 3
- It was confirmed that the fusion occurred. However, when 0 is 38 degrees or more, the behavior of the toner in the direction of arrow C becomes active, and no agglomeration or fusion occurs.
Since the magnetic force of 2 must be less than 900 Gauss,
The amount of toner conveyed to the contact portion 10 decreases, and when an image that consumes a large amount of toner, such as a solid black image, is copied, there is an adverse effect that only an image with low density is obtained. As described above, it is clear that θ must be 306 or more and 90" or less. Furthermore, the carrier pole 92 must be 400 Gauss or more and 900 Gauss or less, and θ must be 30" or more and 90" or less. too,
It has also been found that if the angle ψ in FIG. 2 is not within an appropriate range, the conveyance of the toner 4 will deteriorate, resulting in toner scattering. That is, if ψ is less than 120', the magnetic poles 91 and 92
If the magnetic field is too concentrated during this period, toner will stagnate in that area, and the toner will eventually become sluggish and scatter on the image. On the other hand, if ψ exceeds 180°, the transport pole 92 must be 900 gauss or less, so that the toner cannot be held on the surface of the developing sleeve 3 by magnetic force, causing the negative effect of scattering. confirmed. Therefore, the angle ψ must be between 120" and J-180.'
Gauss or less, the angle θ is 30" or more and 90° or less, and the angle ψ is 18" or more and 180° or less, so that no fusion occurs, and a good film without scattering or fogging can be obtained. It is possible to continue providing images. The inventors found that the environmental characteristics were low temperature and low humidity (15°C91
A durability test was conducted on 10,000 sheets under environmental changes ranging from 0%) to high temperature and high humidity (32°5°C, 90%), and the developing device with the structure of the present invention was found to be The toner did not fuse to the developing sleeve 3, a good uniform thin layer was formed, and images of high quality were continuously provided stably. Note that the present invention is also applicable to toner manufactured by a commonly used pulverization method. This toner is manufactured by mixing 100 parts of styrene acrylic resin with 60 parts of magnetic material (by weight) and pulverizing the mixture. Unlike capsule toner, it contains only a small amount of magnetic material since it is not covered with a shell. It's done. In addition, since the magnetic pole structure is composed of two poles, the outer diameter of the developing sleeve 3 is 5Il to 25m, preferably 81m.
By setting it to 111-2()■, the effects of the present invention can be more effectively exhibited. In other words, the conventionally used magnet roller 9 has a multipolar magnet roller having four or more poles. Therefore, there are three or more poles for m feeding. Since the toner is held on the developing sleeve 3 by these magnetic forces, the toner can be held sufficiently even if the diameter of the developing sleeve 3 becomes large. However, in this embodiment, since the number of magnetic poles is two, if the diameter of the developing sleeve 3 becomes too large, no matter how strong the magnetic force is, it will not be possible to hold the toner 4 on the surface of the developing sleeve 3. This is because toner scattering is likely to occur. The elastic blade 6 may be made of a thin metal plate made of phosphor bronze, Sus, or the like, in addition to this embodiment. At this time, the metal thin plate preferably has a thickness of about 10 to 100 tons. [Effects of the Invention] As described above, in the present invention, the second magnetic pole fixed in the developer carrier and arranged inside the developer supply means has a predetermined magnetic force, and the second magnetic pole Since the developer regulating member is arranged at a predetermined angle with the second magnetic pole, a one-component magnetic toner capable of pressure fixing or low-temperature heat fixing is used as the developer. Even in such cases, it is possible to form a good thin layer without toner fusing, and a high-quality copy image can be stably obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a schematic configuration of an embodiment of the developing device of the present invention, and FIG. 2 is an enlarged cross-sectional view partially showing the device of FIG. l...... Electrostatic latent image carrier (tram)
3...Developer carrier (developing sleeve) 4...Developer (toner) 6.
.........Developer regulating member (elastic plate) 9... Magnetic field generating means (magnetic roller) 10...・・Contact portion 11 ・・・・・・・・Minute gap Patent applicant
Canon Co., Ltd. Figure 2

Claims (6)

[Claims] (1) An electrostatic latent image carrier that carries an electrostatic latent image, a one-component magnetic developer for visualizing the electrostatic latent image, and a developer carrier that supports and transports the developer. a magnetic field generating means fixed within the developer carrier; a developer supply means for supplying the developer to the developer carrier; and a developer supply means disposed in the developer supply means, the developer carrier and a developer regulating member that regulates the layer thickness of the developer supplied to the developing device, wherein the magnetic field generating means includes two magnetic poles, and the first magnetic pole is located at a position opposite to the electrostatic latent image carrier. The second magnetic pole has a magnetic field of 400 Gauss or more, 90 Gauss or more on the surface of the developer carrier.
has a magnetic force of 0 Gauss or less, and is disposed inside the developer supplying means at a position of 120 degrees or more and 180 degrees or less from the center of the first magnetic pole in the rotational direction of the developer carrier,
The developer regulating member contacts the developer carrier at a predetermined position, and is arranged such that the angle between the contact portion and the center of the second magnetic pole is 30 degrees or more and 90 degrees or less. There is a developing device. (2) The developing device according to claim 1, wherein the one-component magnetic developer is capable of pressure fixing at a linear pressure of 5 kilograms per centimeter or more. (3) The developing device according to claim 1 or 2, wherein the one-component magnetic developer can be thermally fixed by a fixing roller heated to 90 degrees Celsius. (4) Claims (1) to (3) wherein the developer regulating member is provided facing the developer carrier and inclined so as to be spaced downstream with respect to the rotating direction of the developer carrier. ). (5) The outer diameter of the developer carrier is approximately 5 mm or more and 25 mm or less (claim 1).
) to (4). (6) Claims (1) to (5), wherein the developer regulating member is formed of a non-magnetic thin plate having elastic force.
The developing device according to any one of the above.