JPS6051851A - Developing device - Google Patents

Abstract

PURPOSE:To form a thin layer of a developer without any leakage by forming plural cuts in an elastic body at intervals from an end side of press contacting with a developer carrier, forming the developer layer at the part between the cuts, and attaining elastic deformation without any influence from both end parts. CONSTITUTION:Plural cuts 36A are formed at intervals from the press-contacting side of the elastic body 36 for developer layer formation which is pressed against the developer carrier 35 to the carrier 35, and the developer layer is formed at the part between the cuts 36A. In this case, two cuts are formed. This part between the cuts 36A is displaced elastically without any influence of a leak preventing means for a developer from the side of the developer carrier 35 and elastic body 36 even when the preventing means is provided. Consequently, the developer flowing between the developer carrier 35 and elastic body 36 leaks neither from the side them nor from the elastic body 36 in a floating state, and the developer thin film becomes uniform, thereby obtaining a developed image of good quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention 1] This relates to a developing device that attaches a developer to a body and develops a latent image.

[Technical background of the invention and its problems] Development is a process in which, for example, colored fine powder called toner, which is charged to have a potential difference with the charge forming the static N latent image, is electrostatically applied to the electrostatic latent image. This is done by being attracted to the As a developer, in addition to a one-component developer consisting of powdered toner only or external additives such as St 02 attached to the outer surface of this toner, powdered toner and magnetic powder called a carrier can be used. Alternatively, there is a two-component developer made by mixing fine powder of resin, glass, etc. In a two-component developer, the toner is charged by friction with the carrier, and the toner is reliably charged. On the other hand, in order to maintain a constant development density, the mixing ratio of toner and carrier, that is, the toner concentration must always be maintained constant. -Component developers do not require such management of toner concentration, and are classified into two-component developers due to their ease of handling.-Component developers are classified into non-magnetic and magnetic.

Non-magnetic developers are generally made by mixing resin powder with a coloring agent such as carbon, and magnetic developers are made by mixing magnetic powder into this.

- Conventional general developing devices using component developers are an application of the so-called non-contact developing method described in Japanese Patent Publication No. 41-9475. The developer layer is maintained at a distance and faces each other, and an appropriate bias is applied so that the developer is ejected only to the image area. This development method allows the use of electrically insulating or high-resistance developers;
The transfer method has advantages such as (1) no problems such as poor transfer in the culm, (2) no fogging in non-image areas, and has superior features compared to other methods. When developing an electrostatic latent image using this method, the distance between the image carrier and the developer carrier must be made as narrow as possible in order to obtain a high-quality developed image. The upper developer layer is desirably a very thin and uniformly thin layer.

As a means for forming such a thin layer of developer, for example,
A method of forming a magnetic developer IIIW on the developer carrier using a developer carrier having a magnetic field generating means inside is disclosed in Japanese Patent Application Laid-Open No. 54-43047. According to this method, it is possible to stably form a uniform WIN of the magnetic developer, and therefore good ms can be obtained even with the above-mentioned non-contact development method.

However, as mentioned above, when forming the R[ of the developer using a developer carrier having a magnetic field generating means, the magnetic field generating means 1, that is, a magnet, and the magnetic powder dispersed in the developer are used to form C. Since it uses a magnetic developer as an essential component, it has the following drawbacks. (2) Since a magnet must be provided inside the developer carrier, the device becomes complicated and expensive, and it is difficult to reduce the weight and size of the device. ■
Magnetic 11 developer is more expensive than non-magnetic developer.

(2) Magnetic developers contain magnetic powder in their resin, so they have poor coloring properties and are unsuitable for color development.

Although the non-contact development method using a magnetic developer has many advantages, as mentioned above, because it uses a magnetic developer, it also includes essential defects.

On the other hand, the non-contact development method using a non-magnetic developer can be said to be an ideal development method that eliminates all the problems associated with the conventional technology. The only major problem is that it is difficult to stably form a thin layer of developer.
The amount of developer ejected onto the electrostatic latent image becomes partially nonuniform, making it impossible to obtain a high-quality m-image (an image formed by adhering developer to the latent image).

Here, to explain a conventional general developing device that uses a -component developer, an elastic blade made of urethane rubber, stainless steel, etc. is used to apply the developer to a developer carrier made of an aluminum drum or the like. is in pressure contact with the surface of the developer carrier. For example, when using a non-magnetic developer, the developer that flows and dislocates between the elastic blade and the developer carrier is triboelectrically charged, causing the development to occur. The agent is applied to the surface of the agent carrier. By the way, when applying the developer in this manner, it is necessary to prevent the developer flowing and dislocating between the elastic body and the developer carrier from leaking from the sides thereof. This is to prevent waste of developer and to prevent contamination of other devices and malfunction of contaminated devices caused by leaked developer scattering. For this reason, in conventional devices, wedge-shaped seal members made of urethane, felt, etc. are inserted on both sides where the elastic body and the developer carrier face each other, or both sides of the developer carrier are supported pivotably. A sheet-shaped seal member made of urethane, felt, or the like is attached to the side frame, and an elastic body is placed in contact with the seal member to prevent developer from leaking from the sides.

However, depending on the dimensional accuracy of the seal member, both sides of the elastic body may be lifted off the surface of the developer carrier, or the elastic displacement of both sides may be restricted due to friction with the elastic body. Therefore, there is a slight difference in the pressing pressure of the elastic body against the developer carrier between the middle part and both sides. Such non-uniformity in the pressing pressure of the elastic body impedes the formation of a uniform thin layer of the developer on the developer-carrying member, causing uneven development.

In particular, in developing devices that use non-magnetic component developers, this affects the probability of contact between the developer and the elastic body, causing uneven triboelectric charging of the developer, which has a great negative effect on the formation of a thin layer of developer. It was affecting me.

[Object of the Invention] The present invention has been made in view of the above circumstances, and the object of the present invention is to prevent leakage of developer from the sides of the developer carrier and the elastic body. Another object of the present invention is to provide a developing device that does not cause problems with the formation of a thin layer of developer on a developer carrier.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention provides a plurality of cuts in the elastic body from the side of the end in contact with the developer carrying member, spaced apart from each other, and connects both cuts with this cut as a boundary: This part is designed to be able to be elastically displaced with as little influence as possible on both sides.

[Embodiments of the Invention] A developing device of the present invention will be described below with reference to the drawings.

First, an image forming apparatus, such as a copying machine, to which the developing device of the present invention is applied will be described. FIG. 1 is a schematic sectional view of the copying machine. What is indicated by 1 in the figure is the copy m housing,
A drum-shaped photoreceptor 2 made of an image carrier such as selenium, on which an electrostatic latent image is formed on its surface, is rotatably disposed approximately in the center, and a document platen that moves horizontally in a reciprocating manner is mounted on the peripheral side of the drum-shaped photoreceptor 2. A lamp 4 and a convergent light transmitter 5 are used to optically scan the original placed on the photoreceptor 3 and form an image of the original on the surface of the photoreceptor. A charger 7 that uniformly charges the surface of the photoconductor 2 after static elimination, and a charger 7 that selectively flies a developer onto the electrostatic latent image formed on the surface of the photoconductor 2. A developing device 8 according to the present invention is provided to develop the electrostatic latent image, so that a developed image is formed on the surface of the photoreceptor. A paper feed section 10Ifi is provided on one side of the copying housing 1 (the right side in the figure), and includes a paper feed cassette 11 that can be freely moved from the wound, for example, and paper stored in the paper feed cassette 11. A paper feed roller 12 that rolls into contact with the top layer of the MP to send it forward, a manual paper feed guide 13 for manual paper feeding, and a paper inserted from this manual paper feed guide 13. It is constituted by a conveyance roller 14 that conveys it to the destination. The paper fed from the paper feeding section 10 is conveyed at a timing determined by registration rollers 15 so as to come into sliding contact with the photoreceptor 2. A pre-transfer charger 9 and a transfer charger 16 for transferring the developer constituting the developed image onto the paper are located near the paper being conveyed and around the circumference of the photoreceptor 20.
and a peeling charger 17 that peels off the paper from the photoreceptor 2 after transfer. Furthermore, the paper that has been transferred with the developer is conveyed by a conveyor belt 19 and
The developer is fixed by the pressure and heat of the heat roller pair 21 constituting the fixing device 20, and the sheet is ejected onto the tray 23 by the ejecting roller pair 22.

Next, details of the developing device 8 will be explained.

FIG. 2 is a schematic perspective view of the developing device, and FIG. 3 is a schematic sectional view of the developing device. This developing device 8 uses a non-magnetic developer, and the back frame 3 is oriented in a spaced manner.
Side frames 32 and 33 are attached to both sides of the front frame 31 and the developing device housing 34, and the upper end opening 34A has a lid 41 that can be opened and closed for replenishing the developer. A developing roller 35 made of, for example, aluminum or stainless steel is provided near the lower end opening 34B and is rotatably supported by the side frames 32 and 33. There is. Furthermore, between the front frame 31 and the developing roller 35, an elastic material such as silicone butadiene rubber ( The elastic blade 36 formed from the urethane rubber, stainless steel, phosphor bronze (hardness 40 degrees to 45 degrees), urethane rubber, stainless steel, phosphor bronze (thickness 0.07 mm - 0.2 mm) or urethane 1/heel is platen 1, ruda 37 The fluorocarbon 1 is connected to the frame 31 via the fluorocarbon 1 to the frame 31. Elastic blade 3
For example, two cuts 36Δ are provided spaced apart from the end of the roller 35 in pressure contact with the developing roller 35 numbered No. 6 (the upstream side of the elastic blade bent in the developer conveying direction). This cut 36A is used to elastically displace the part sandwiched between the two cuts 36Δ using this as a boundary, without being affected by the two sides of the cut 36A as much as possible.
For example, as shown in FIG. 2, the specific positions include a developing area which is a curved area with a maximum developing width a that is approximately equal to the maximum image forming width of the photoreceptor 2, and a non-developing width formed on both sides of this developing area. An example of this is the boundary between the peripheral surface area and the non-developing area. The elastic blade 36 can be moved to the developing roller 35 by adjusting the position of the blade holder 37.
This allows for fine adjustment of the pressure contact force. In particular, the elastic blade 36 performs development so that a part of the surface facing the developing roller 35 is in surface contact with the developing roller 35.
C, the contact area between the elastic blade 36 and the current 3o-ra 35 can be increased compared to a structure in which the self-mounted part of the elastic blade 36 is in contact with L.

Therefore, it is easy to finely adjust the pressure applied to the developing roller 35, and the pressure can be made uniform. Moreover, the developer can be kept under pressure for a longer period of time. Since it will be rubbed, the developer will be uniform and sufficient I9! tp charge can be acquired. In addition, in order to prevent the developer that flows between the elastic blade 36 and the developing roller 35 and enters under the pressure contact of the elastic blade 36 from leaking from the sides thereof, the elastic blade 36 is Developing roller 35
A sheet-shaped sealing member 42 made of urethane, felt, or the like is interposed on both opposing sides and is attached to the side frames 32 and 33. Note that this seal member 42 has a relatively small coefficient of friction and is
The structure is such that it does not hinder the rotation of the elastic blade 36, and is tightly attached to the side part of the elastic blade 36 (a part other than the area sandwiched by the cut 36A) through an adhesive or the like. This developing device 8 is arranged at a position where the developer applied to the developing roller 35 does not come into contact with the photoreceptor 2 . This non-contact arrangement relationship is based on the particle size W of the developer applied to the developing roller 35! Although it is determined by JW etc., in order to ensure the flying of the developer and obtain a high-quality developed image, the distance between the developing roller 35 and the photoreceptor 2 must be as narrow as possible. It is desirable for the developer layer to be thin, and the range of the developer particle size used is also determined by the relationship with the resolution, so the practical gap size between the two is approximately 10
It is about 11 to 300 μm. In order to maintain this gear method, for example, a gap regulation roller 39 is rotatably attached to the shaft of the developing roller 35. The center-to-center distance between the photoreceptor 2 and the developing roller 35 is kept constant by contacting a receiving roller (not shown) attached to the shaft of the photoreceptor 2 . Further, a power source 40 is provided that applies a voltage to the developing roller 35 to form an electric field between the photoreceptor 2 and the developing roller 35 .

This power source 40 uses an electric field formed between the photoreceptor 2 and the developing roller 35 to transfer the developer on the developing roller 35 to the photoreceptor 35.
This makes it easier to fly to the surface and is not necessarily necessary. This is because the developer triboelectrically charged on the developing roller 35 is sufficiently flown to the surface of the photoreceptor simply by the electrostatic attraction force generated by the latent image charge on the surface of the photoreceptor.

Here, the uneven rough surfaces formed on the developing roller 35 and the elastic blade 36 will be explained.

First, to explain both generally, as shown in FIG. 4, a first uneven surface 45 is formed on the circumferential surface of the developing roller 35, and an elastic blade 36 facing the developing roller 35 is formed on the circumferential surface of the developing roller 35. A second uneven surface 46 is formed on a part of the opposing surface. First, the first uneven surface 45 is formed to have a surface roughness of 0.07D to 1.5D, where D is the developer particle size, and is roughened by sandblasting or puff finishing. Processing is being done. Note that the first
As shown in FIG. 2, the uneven rough surface 45 is formed in the developing region which is the peripheral surface region of the maximum developing width a which is approximately equal to the maximum image forming width of the photoreceptor 2, and on both sides of this, there is a peripheral surface of the non-developing width. A non-developed area is formed and no special surface roughening treatment is performed. Further, as shown in FIG. 4, the second uneven rough surface 46 is a region that is not in contact with the developer single particles 11A interposed between the developing roller 35 and the elastic blade 36, for example, the developing roller. 35 and the specific developer T1, the distance between the distance 111tdt (approximately 2 to 3 times the developer particle diameter) from the tangent 11 and the distance F1d2. formed in the area. When viewed in the longitudinal direction of the elastic blade 46, this formation area extends from one end in the longitudinal direction (direction along the axis of the developing roller) to the other end, as shown in FIG. Further, this second uneven rough surface 46 has a diameter of 0 when the developer particle size is D.
．． It is formed to have a surface roughness of 10 to 2.0D, and is roughened by sandblasting or puff finishing.

Next, the operation and effect of the developing device 8 will be explained.

When the developing device 8 is filled with the developer T and the developing roller 35 is rotated in the direction of the fourth arrow W1, the developer T is conveyed in the direction of the arrow W1 by the conveying force of the developing roller 35 and the like. Frictional electrification occurs between the blade 36 and the blade 36 . At this time, since the first uneven surface 45 is formed on the surface of the developing roller 35, the conveying force F of the developer in contact with the developing roller 35 and the developer T in the vicinity thereof
i is increased, and the developer T near the developing roller is reliably conveyed in the direction of the force of arrow Ws and is fluidly disposed.

Furthermore, since the elastic blade 36 is formed with a second uneven surface 46, the developer that comes into contact with the second uneven surface 46 is subjected to a relatively large conveyance resistance force F2.
6, the flow dislocation of the developer T becomes slower.
Since the surface (ds range) is not subjected to surface roughening treatment, only a relatively small transport resistance force F3 is applied to the developer T in contact with this portion, resulting in smooth flow dislocation. The developer T entering under the pressure contact of the elastic blade 36 which exerts a pressing force "4" on the side is actively and smoothly fluidized and dislocated along the arrows W2 and W3 near the developing roller 35. The layer thickness of the flowing and dislocated developer gradually decreases as it approaches the downstream side of the elastic blade 36, and in the downstream part of the elastic blade 36, it is applied to the developer roller 35 as a uniform single particle layer. In this way, the developer that enters under the pressure of the elastic plate 36 flows clearly in the area sandwiched by the cuts 36A, that is, the development area that is the peripheral surface area of the maximum development width a shown in FIG. Since the layer thickness of the developer that is dislocated and fluidly dislocated is gradually reduced by a relatively small angle θ, the elastic blade 36 may be damaged due to deterioration in fluidity of the developer T, unevenness, or inclusion of foreign matter.
The unrestricted state of the developer layer caused by the pushing up of
Also, uneven charging of the developer can be reliably prevented.

In addition, a portion other than the area sandwiched by the cut 36A (second
In the side part of the elastic blade 36 corresponding to the undeveloped width (b) shown in the figure, the back surface of the elastic blade 36 is tightly attached to the sealing member 42 via an adhesive or the like. The elastic blade 36 in the developing width is reliably prevented from lifting off the surface of the developing roller 35. In this way, the elastic blade 36
Even if lifting of both sides is restricted, the elastic blade 36 has cuts 36A, so the part of the elastic blade 36 sandwiched between both cuts 36A
can be elastically displaced almost unaffected by its both sides. Therefore, as explained based on FIG. 4, even if the elastic blade 36 is deflected by the amount of the developer single particle layer A within the maximum development width a during development, this deflection is 36. Therefore, the pressure of the elastic blade 36 is always uniform within the range of the maximum development width a, and there is no possibility that the developer will form a uniform thin layer on the development roller. Moreover, since the elastic displacement of the elastic blade 36 in the non-developing width is regulated via the seal member 42,
The developer that undergoes flow transfer between the elastic blade 36 and the developing roller 35 may leak from the sides thereof, or the elastic blade 36 may rise from the surface of the developing roller 35 in the non-developing width. The leakage of developer from that part is reliably prevented. In addition, the deflection (lifting) of the elastic blade 36 in the development width a is about 100 μm or less, which is the amount equivalent to a single particle layer of the developer as described above. By making it more than a particle layer, the developer will not leak from the cut 36A. When a uniform thin layer of the developer T is formed on the surface of the developing roller 35, the triboelectrically charged developer constituting the thin layer is is selectively ejected onto the surface of the photoreceptor 2, and the electrostatic latent image on the surface is visualized. As mentioned above, the contact pressure of the elastic material grade 36 at the maximum development width a and d3 is uniform, and the thin layer of developer applied to the developing roller is uniform, so the selectively blown developer is static. The electrolatent image is uniform in each part, and a high-quality developed image can be obtained.

Further, as mentioned above, since the thin layer of developer applied to the developing roller 35 is uniform, it is sufficient that the distance between the developing roller 35 and the photoreceptor 2 is at least slightly larger than the thickness of the developer single particle layer. This can fully meet the need to reduce the distance between the developing roller 35 and the photoreceptor 2 as much as possible in order to ensure the flying of the developer and obtain a good developed image. For the same reason, even if a one-component non-magnetic developer is used, non-contact development (the image carrier and the coated developer layer on the developer layer are separated and opposed to each other), and the developer layer formed on the image carrier is developing by spraying developer only on the image area of the latent image)
Because it can reliably perform this process, it can be applied reliably to the overlay development required for color phenomena, and it also ensures that the image carrier will not be damaged due to contact with the image carrier or deteriorate over time. can be prevented.

It should be noted that the above embodiment is merely an example, and it goes without saying that various modifications can be made within the scope of the gist of the present invention. For example, although the cut is used as it is, it is also possible to fill the cut with a silicone filler that remains elastic even after hardening. Especially if you do it this way,
Even when an elastic body whose thickness is smaller than the particle size of the developer is used, it is possible to prevent the developer from leaking through the cuts. Further, in the above embodiment, the structure in which the back surface of the elastic blade in the non-developing width is bonded to the sealing member 42 has been described, but a structure for suppressing the elastic displacement of the elastic blade in this area is shown in FIG. 6, for example. It is also possible to attach a holding member 52 made of a plate spring or the like to the right side of the blade holder 37 so that the free end thereof is pressed against the elastic blade 36.

Note that the holding member may be replaced with urethane rubber, a coil spring, or the like. In addition, grooves (not shown) into which both end surfaces of the elastic blade 36 in the longitudinal direction are fitted are provided in the side frame 33.32, and the fitting with the grooves prevents elastic displacement of the elastic blade in the non-developing width. It can also be configured as follows. Furthermore, not only a non-magnetic developer but also a one-component magnetic developer can be used as the developer. In addition, the developer carrier can be replaced not only with a metal drum made of aluminum or stainless steel, but also with a metal drum or a belt, and it is also possible to anodize or chrome plate the surface thereof.

In particular, by performing such surface treatment, it is possible to prevent wear of the surface of the developer carrier, for example, the first uneven surface, etc., and it is possible to improve the stability of development over time and extend the life of the developer carrier. .

Furthermore, the electrostatic latent images that can be developed by this developing device are not limited to those formed by the copying machine shown in FIG. Any pattern will do.

Effects of filling E] As is clear from the above description, in the developing device of the present invention, a plurality of cuts are provided at a distance from the end of the elastic body that is in pressure contact with the developer carrier, and these cuts are used as boundaries. The part sandwiched between the two cuts is designed to be able to elastically displace with as little influence as possible from both sides. Even if preventive measures are taken, the PyF of the current PyF agent on the current Ii agent carrier
It has excellent effects such as having no adverse effect on i formation.

[Brief explanation of the drawing]

FIG. 1 shows the current f! ! FIG. 2 is a schematic perspective view showing an embodiment of the developing device of the invention, FIG. 3 is a schematic sectional view of the same device, and FIG. 4 is a schematic cross-sectional view of the same device. FIG. 5 is a schematic perspective view of the elastic blade, and FIG. M6 is a schematic cross-sectional view showing a modified example. 35... Developer carrier, 36... Elastic body, 36Δ... Cut, T... Developer.

Claims (1)

[Claims] (1) Equipped with a developer carrier that supports and transports developer on its surface, and an elastic body for forming a developer layer that is elastically pressed against the surface of the developer carrier, and this elastic body performs development. In a developing device for forming a developer layer by attaching a developer to a developer carrier and subjecting the layer to development, a plurality of cuts are provided at a distance from an end of the elastic body in pressure contact with the developer carrier, A developing device characterized in that a developer layer is formed in a portion sandwiched between these cuts. ('2J) The claim is that the cut is provided between two chains from the end of the elastic body in contact with the developer carrier, and a developer layer is formed in the portion sandwiched between the two cuts. Developing device according to item 1.