JPH0225879A - developing device - 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 [Field of Industrial Application] The present invention relates to a developing device for developing an electrostatic latent image formed by electrophotography, electrostatic recording, or the like.

[Traditional technique! R] Conventionally, various devices have been proposed and put into practical use as dry-component developing devices. However, in any of the development methods, it is extremely difficult to form a thin layer of dry component developer, and for this reason, the development device has been constructed by forming a relatively thick layer. Nowadays, the sharpness, resolution, etc. of developed images are in high demand, and the R3JA publication regarding a method for forming a thin layer of a dry-component developer and an apparatus therefor is indispensable.

One of the conventional methods for forming a thin layer of dry component magnetic I-ner has been proposed and put into practical use in Japanese Patent Application Laid-Open No. 42141/1983. The developing device using the proposed method has a layer thickness adjusting means using an elastic rubber blade, and the elastic rubber blade applies a predetermined pressure S to the surface of the sleeve, which is a toner support, in the longitudinal direction. The toner layer is applied to the surface of the 1-toner support with a uniform thickness.

[Problem to be solved by the invention] However, in the practical machine using the above example,
Because it uses a heat roller heated to approximately 180°C, the so-called heat fixing method uses a heat roller heated to approximately 180°C, so there are drawbacks to miniaturizing image forming devices and reducing power consumption. there were.

Therefore, the use of l-ner, which has high frictional charging and can fix with low power consumption, is recommended, but this type of! If - toner is used, there is a problem in that the toner is less likely to be fused to the developing device, that is, the + - toner is less likely to be fused to the sleeve.

The present invention solves the above-mentioned problems of the conventional apparatus, allows the use of pressure fixing or a 1-toner that can perform fixing with low power consumption, and also prevents toner from fusing to the sleeve. The purpose of the present invention is to provide a developing device that does not require

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a one-component magnetic developer, a developer carrier that supports and transports the developer, and a developer fixed in the developer carrier. A developing device comprising a magnetic field generating means, a developer supplying means for supplying the developer to the developer carrier, and a developer regulating member disposed on the developer supplying means and made of an elastic body. .

The developer regulating member is configured such that the potential energy of the gravitational field at the end of the contact portion with the developer carrier on the downstream side with respect to the rotational direction of the carrier is such that the potential energy of the gravitational field at the end on the upstream side of the contact portion A minute gap formed by the developer carrier and the developer regulating member on the upstream side of the contact portion is arranged such that the energy is higher than the energy of the gravitational field of the magnetic field generating means. The magnetic field generating means is arranged within the range of the magnetic field of the magnetic field generating means fixed on the downstream side of the contact portion.

[Operation] When the developing device configured as described above is started and the developer m carrier rotates, the toner present in the minute gap formed by the carrier and the developer regulating member is transferred to the carrier in the gap. The spikes stand up and unravel under the influence of the magnetic field of one pole of the magnetic field generating means fixed in the support body on the upstream side with respect to the direction of rotation of the body. The toner is further arranged so that the potential energy of the gravitational field is lower at the contact portion between the carrier and the developer regulating member on the downstream side with respect to the rotational direction of the carrier while being loosened. transported to the designated area.

[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, reference numeral 1 denotes a carrier carrying an electrostatic latent image, and has an insulating layer or a photosensitive layer on its surface. The carrier l is, for example, a photosensitive drum in which an OPC photosensitive member is coated on the surface of an aluminum drum having a diameter of 10 mm and a thickness of 0.8 am. The electrostatic latent image 2 is formed by applying a known method such as corona charging to the surface of a carrier l (hereinafter referred to as a drum).
It is formed by applying a similar charge and then exposing the image to halogen light, fluorescent light, etc. through a lens in an analog manner.

Note that the electrostatic latent image 2 is not formed by this method, but by, for example, LE
It can be formed by other methods, such as a method of performing digital image exposure using a D 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.

1. The drum 1 has a circumferential speed of 52 mm/cm in the direction of arrow a in the figure.
sec, and the potential of the electrostatic latent image 2 on the surface is
, = -700V, bright part Vc, = -200V
There is. Although not shown, the drum l is grounded.

3 is a developing sleeve as a developer carrier. The developing sleeve 3 has a diameter of 16 mai and a thickness of 0.8 mm, for example.
It is a non-magnetic sleeve made of aluminum or the like. Its surface has been processed using, for example, #600 blast particles, and has a JI 310 point average roughness of Rz = 2.0 gya.
It is. It is desirable that the unevenness formed by this processing is uniform, and R2 is smaller than the average particle diameter of the toner particles 4.
I'm sorry for how small it is. The developing sleeve 3 is rotatably supported by a bearing (not shown), and has a circumferential speed of 6, for example.
It rotates in the direction of the arrow in the figure at 0 ya/5 ec (1.18 times the circumferential speed ratio of the drum). Also, the developing sleeve 3 is D
It is connected to a power supply 5 that can superimpose AC bias on C bias, and according to experiments, the Vpp depth is 500 to 3,000 OO.
V.

f=500 to 3,000 H, is suitable. In this example, Voc=-:150 V, VPP=1,30
0V,! , 600 Hz bias is applied.

Further, the developing sleeve 3 has a developing gap g with respect to the drum l.
They are supported facing each other with a gap of 150 mm.
A layer of about 500w is suitable, and in this example,
A gap g of approximately 25 (1 μm) was set.

On the other hand, an elastic blade 6 as a developer regulating member is fixed at one end to the developing sleeve 3 by a support 7, and is brought into contact with the sleeve 3 in the opposite direction, that is, in a shape that causes the blade 6 to warp. .

The elastic plate 6 is, for example, a rubber blade with a hardness of 50=80", and in this embodiment has a thickness of about lam and a hardness of 65".
No. 11 urethane rubber was used.

Reference numeral 9 denotes a permanent magnet (magnet roller) as a fixed magnetic field generating means inserted into the sleeve 3 and held at the illustrated position δ. The magnetic roller 9 is fixedly held in the illustrated position even when the sleeve 3 is rotationally driven. The magnet roller 9 may be provided with an electromagnet instead of a permanent magnet.

In this embodiment, the magnetic roller 9 has magnetic poles 91j5 and 92
A permanent magnet roller is used which exerts about 800 Gausr on the surface of the developing sleeve 3. The magnetic pole 92 is arranged on the upstream side of the contact portion 10, which is the contact portion between the magnetic sleeve 3 and the elastic blade 6, in the rotational direction of the sleeve 3. Note that the magnetic roller 9 has two poles, three poles, or five poles.
A magnetic roller with more than one pole may be used.

The one-component magnetic toner 4, which is a developer, is held on the surface of the sleeve 3 by the magnetic force of the magnetic poles 91 and 92.
As the blade rotates in the direction of the arrow, it is transported to the abutting portion IO between the elastic blade 6 and the sleeve 3. The toner 4 is further affected by the pressing force of the elastic plate 6 against the sleeve 3 and gravity;
Furthermore, the amount of transport is regulated by the magnetic force of the magnetic pole 92, and the layer is coated on the surface of the sleeve 3 to a predetermined thickness.

The toner 4 formed to a predetermined layer thickness is conveyed to the developing section, that is, the closest portion between the sleeve 3 and the drum 1, and the electrostatic latent image 2 described above is developed by known means.

Note that in this embodiment, a jumping development method is used using the bias conditions described above. Further, the above-mentioned pressure contact force is about 5 to 50 PJ/cm, preferably about 25 g.
Kabutsu/C1 is appropriate.

The toner 4 that has contributed to the development is collected again into the container 8 by the rotation of the sleeve 3.

In this embodiment, a capsule toner capable of pressure fixing or low-temperature heat fixing is used in conjunction with the -component magnetic toner 4. This capsule toner consists of a core material whose main component is wax to improve fixing properties, and a positive control resin that contains a monomer monomer as an essential component on the outside of the core material to improve development characteristics. , a functionally separated type magnetic capsule toner with a core and a shell,
The average particle size is approximately lip■. In addition, it is also possible to mix a coloring material or a magnetic material into the core material if necessary, and it can be disintegrated at a pressure of about 50 kg/cm or more, and its melting point is about 70°C. Heat fixing is also possible if the temperature of the roller is about 90° C. or higher.

As is clear from FIG. 2 (A) and FIG. 2(B), which are partially enlarged views showing the features of the developing device of the present invention in more detail, the elastic blade 6 is The contact portion 10 is arranged such that the potential energy at the downstream end thereof is higher than the potential energy at the upstream end thereof with respect to the direction. In addition, at least one pole of the magnetic roller 9 (
A magnetic pole 95) is formed in the wedge multi-chamber space ll formed on the upstream side of the contact portion 3 by the elastic play drum and the developing sleeve 3.
In a developing device having this structure, when the developing sleeve 3 rotates in the direction of the arrow A, the toner 4 present in the wedge multi-chamber space 11 is exposed to the magnetic force of the magnetic pole 95. It stands up and unravels. Toner 4 is even more.

Since the particles are conveyed to the contact portion 1O without being loosened, agglomeration is less likely to occur. Also, as mentioned above, since gravity is acting in the direction opposite to the direction of rotation of the sleeve 3, arrow A
The movement of the toner 4 in the direction becomes active. Further, in addition to the mechanical pressure of the elastic blade 6 and gravity, the amount of toner 4 conveyed passing through the contact portion 10 is regulated by the magnetic force of the magnetic pole g5, so that the pressure can be reduced.

As explained above, the developing device having the structure shown in FIGS. 2(A) and 2(B) prevents the toner 4 from fusing onto the developing sleeve 3 and produces stable and uniform toner 4. Can be formed into a thin layer.

Note that, as shown in FIG. 5, for example, when the elastic blade 6 is brought into contact with the sleeve 3 while being inclined to the upstream side in the direction of rotation of the sleeve 3, the above-mentioned Since the wedge multi-chamber space 11 becomes larger, the amount of toner conveyed to the contact portion 10 increases. Therefore, the pressure welding force should be increased to 35
gw/cm or more, preferably about 100 gw/cm, it is not possible to obtain a uniform thin layer on the surface of the developing sleeve 3, as shown in FIGS. 2(A) and 2(B). This is significantly higher than in the case where the sleeve 3 is opposed to the sleeve 3 and brought into contact with the sleeve 3 in a tilted manner so as to be spaced apart toward the downstream side in the rotational direction of the sleeve 3. Therefore, mechanical load increases on the toner, toner fusion tends to occur, and the rotational torque of the sleeve 3 also increases.

Therefore, as shown in FIGS. 2(A) and 2(B), it is preferable that the developing sleeve 3 be opposed to the developing sleeve 3 and abutted at an angle so as to be spaced apart toward the downstream side in the direction of rotation of the sleeve 3.

The inventors found that the environmental characteristics were low temperature and low humidity (15℃, 1
A durability test was conducted on 10,000 sheets under environmental changes ranging from 0% toner to high temperature and high humidity (32.5°C, 90%). 4 did not fuse to the developing sleeve 3, a good uniform thin layer was formed, and high-quality images were continuously provided stably.

In addition, in the present invention, the elastic blade 6 is made of, for example, phosphor bronze or S.
Similar effects can be obtained by using a thin metal plate such as US. In this case, the metal thin plate preferably has a thickness of about 10 to 100 ru. Furthermore, the effects of the present invention can be effectively applied even if conductive rubber is used as the material of the elastic blade 6 and a bias is applied to it. At this time, it is preferable to apply a bias such that the elastic blade 6 has an equal potential with the developing sleeve 3 or pushes the toner toward the sleeve 3, and this can be applied even when the above-mentioned thin metal plate is used.

FIG. 3 is a partially enlarged view showing essential parts of another embodiment of the present invention. In this embodiment, the outer diameter of the developing sleeve 3 is made smaller than the outer diameter of the sleeve 3 shown in FIGS. 2(A) and 2(B). Reference numeral 31 in the figure indicates the case where the outer diameter of the developing sleeve 3 is 40φ, and reference numeral 32 in the figure indicates the case where the outer diameter of the sleeve 3 is 25 mm.

As is clear from the figure, the aforementioned wedge multichamber rlRt
i increases rapidly as the outer diameter of the sleeve 3 becomes smaller.

Therefore, the smaller the outer diameter of the sleeve 3, the more likely the toner 4 will behave in the direction of the arrows in FIGS. 2A and 2B. Therefore, since the toner 4 is replaced and loosened frequently, the effects of the present invention can be more easily exerted.

For reference, an experiment using the above-mentioned capsule toner in a developing device conventionally proposed by the present inventors will be described. FIG. 4(A) is a partially enlarged view of a developing device having the structure proposed in JP-A No. 54-42141, and FIG. 4(B) is an example of a conventional developing device having another structure. FIG.

When the abutting structure shown in FIGS. 4(A) and 4(B) is adopted, the toner existing in the wedge multispace 11 is pushed by the 1-toner conveyed later. However, they cannot escape, so they aggregate, and due to the pressing force of the elastic blade and the frictional heat generated at the contact area,
This caused a problem in that it fused to the surface layer of the sleeve 3.

In addition, this fusion development is carried out in a high temperature and humidity environment (32.5℃,
90%).

That is, as in the structure shown in FIGS. 4(A) and 4(B), the downstream end of the contact portion 10 with respect to the rotational direction of the developing sleeve 3 has a lower potential energy of the gravitational field than the upstream end. It has become clear from various experiments that the elastic blade 6 should not be brought into contact with the sleeve 3 in such a way that the

Therefore, the inventors, as shown in FIG.
When the elastic blade 6 is brought into contact with the sleeve 3 so that the potential energy of the gravitational field is higher at the downstream end of the contact portion 10 in the direction of rotation of the sleeve 3 than at the upstream end, Since gravity acts on the toner in the wedge multi-space ll in the direction opposite to the direction of rotation of the sleeve 3, the movement of the toner in the direction of arrow B becomes active, and the toner is constantly replaced, so that the wedge multiplicity occurs. Toner is less likely to accumulate in the space 11, and the pressing force of the elastic blade 6 can be made smaller than when the configurations shown in FIGS. It became difficult to get there.

However, - unlike the conventional high-temperature heat fixing toe, the chi 4 itself is prone to fusion, so if the structure shown in Fig. 6 is adopted, fusion will still not occur completely on the sleeve 3. It was not possible to obtain a thin layer coating.

However, according to the developing device having the structure of the present invention, the sixth
It has the structure shown in the figure, and as described above, the minute gap formed by the developing sleeve 3 and the elastic blade 6 on the upstream side in the rotational direction of the sleeve 3, or the magnet row fixed inside the sleeve 3. At least sleeve 3 of 9
Because it is located within the range of the magnetic field formed by one pole on the upstream side in the rotational direction of It is possible to form a uniform thin layer without having to do anything.

``Effects of the Invention'' As shown in L below, the present invention reduces the potential energy of the gravitational field at the downstream end of the contact portion of the developer regulating member with the developer carrier with respect to the rotating direction of the carrier. The magnetic field generating means may be arranged such that the potential energy is higher than the potential energy on the upstream side, and the magnetic field generating means may be fixed at the minute gap formed between the developer regulating member and the carrier or on the upstream side of the carrier. The magnetic field IiI
Even when using a one-component magnetic developer that requires pressure fixing or low-temperature heat fixing, it is possible to maintain a uniform thin layer without fusion of the developer on the surface of the developer carrier. can be formed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a schematic configuration of one embodiment of the developing device of the present invention, FIGS. 2(A) and (B), FIG. 3, and
JSs is an enlarged sectional view showing another embodiment of the developing device of the present invention, FIGS. 4(A) and (B) are enlarged sectional views showing a conventional developing device, and FIG. Diagram (B)
FIG. 3 is an enlarged cross-sectional view showing the configuration of an experimental example for improving the device of FIG. 3----------...Developer carrier (sleeve)
4---------Developer (toner) 6...
......Developer regulating member (elastic blade)
9--------- Magnetic field generating means (magnetic roller) 10---------Contact part

Claims (4)

[Claims] (1) A one-component magnetic developer, a developer carrier that supports and transports the developer, a magnetic field generating means fixed within the developer carrier, and supplies the developer to the developer carrier. In the developing device, the developer supply means has a developer supply means, and a developer regulation member made of an elastic body is disposed on the developer supply means, and the developer regulation member has a contact portion with the developer carrier. The carrier is arranged such that the potential energy of the gravitational field at the downstream end with respect to the rotation direction of the carrier is higher than the gravitational field energy at the upstream end of the contact portion, and the developer A minute gap formed by the carrier and the developer regulating member on the upstream side of the abutting portion is configured to suppress the magnetic field of the magnetic field generating means fixed on the upstream side of the abutting portion of the magnetic field generating means. A particular developing device located within the range. (2) The developing device according to claim 1, wherein the developer regulating member is provided so as to face the developer carrier and be inclined so as to be spaced apart from the developer carrier on the downstream side. (3) The developing device according to claim (1) or (2), wherein the one-component magnetic developer is capable of pressure fixing at a surface pressure of 50 kilograms per square centimeter or more. (4) The developing device according to any one of claims (1) to (3), wherein the one-component magnetic developer can be thermally fixed by a fixing roller heated to 90 degrees Celsius.