JPH0641258Y2 - Development device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of Invention] (Industrial field of application) The present invention relates to a developing device for developing a charge image by adhering a developer to an image carrier having a charge image formed on its surface. It is about.

(Prior Art) In development, colored fine powder called toner, which is charged so as to have a potential difference from the charge forming an electrostatic latent image, is electrostatically attracted to the electrostatic latent image. Done by. As the developer, in addition to a one-component developer consisting of a powder toner alone or an external additive such as SiO ₂ attached to the outer surface of the toner, a powder toner and a magnetic powder called carrier. Alternatively, there is a two-component developer prepared by mixing fine powder such as resin or glass. In the 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 keep the developing density constant, the mixing ratio of the toner and the carrier, that is, the toner density must always be kept constant. The one-component developer does not require such toner concentration management, and is superior to the two-component developer in the ease of handling.

One-component developers are classified into non-magnetic and magnetic. The non-magnetic developer is generally a resin powder mixed with a coloring agent such as carbon, and the magnetic developer is a mixture of magnetic powder with this.

A conventional general developing device using a one-component developer is an application of a so-called non-contact developing method described in Japanese Patent Publication No. 41-9475, for example, an image carrier and a developer carrier. The developer layer and the developer layer are held apart from each other so as to face each other, and an appropriate bias is applied to cause the developer to fly only to the image portion. Since this developing method can use an electrically insulating or high-resistance developer, it has advantages that problems such as transfer defects do not occur in the transfer step, and that no fog occurs in the non-image area. It has excellent characteristics compared to other methods. When developing an electrostatic latent image by this method, the space between the image carrier and the developer carrier should be as narrow as possible in order to obtain a good quality image (image in which the developer is attached to the charge image). Inevitably, it is desirable that the developer layer on the developer carrying member be a very thin and uniform thin layer.

As a means for forming such a thin layer of the developer, for example, a method of using a developer carrier having a magnetic field generating means inside and forming a thin layer of the magnetic developer on the developer carrier is specified. It is disclosed in Kaisho 54-43047 and the like. According to this method, it is possible to stably form a uniform thin layer of the magnetic developer, and thus a good visible image can be obtained even by the above-mentioned non-contact developing method.

However, as described above, when a thin developer layer is formed by using a developer carrier having a magnetic field generating means, a magnetic developing means in which magnetic powder is dispersed in the magnetic field generating means, that is, a magnet and the developer. Since the agent is an indispensable constituent element, it has the following drawbacks. Since the magnet has to be provided inside the developer carrying member, the device becomes complicated and expensive, and it is difficult to reduce the weight and size.
Magnetic developers are more expensive than non-magnetic developers. Since the magnetic developer contains magnetic powder in the resin, it has poor coloring properties and is not suitable for colorization.

The non-contact developing method using a magnetic developer has many advantages, but on the other hand, it contains an essential defect due to the use of the magnetic developer as described above.

On the other hand, the non-contact developing method using a non-magnetic developer can be said to be an ideal developing method that solves all the problems related to the conventional technology, but since the non-magnetic developer is used, it is uniform. There is only one big problem that it is difficult to stably form a thin layer of the developer, and if the thin layer of the developer cannot be uniformly formed in this way,
The amount of the developer flying on the electrostatic latent image is partially nonuniform, and it becomes impossible to obtain a high-quality visible image.

Further, from the viewpoint of preventing unnecessary consumption of the developer and preventing the occurrence of a functional failure due to the contamination of other devices around the developing device, the leakage of the developer entering toward the developer carrier is prevented. There is a need to.

Therefore, in the conventional apparatus, a wedge-shaped seal member made of urethane or felt is inserted into both sides of the developer carrying member, or urethane or felt is attached to the side frames pivotally supported on both sides of the developer carrying member. A sheet-like seal member is attached and an elastic member is brought into contact with the seal member to prevent the developer from leaking from the side.

However, even if the seal member is provided in this manner, there are mechanical dimensional errors (errors in processing and assembly of parts) in each part of the device, and the developer particle size is extremely small, such as about 20 μm. It was not possible to completely prevent the developer from leaking from both sides, so that the scattering of the developer from the apparatus had to be silently accepted.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and an object of the present invention is to form a uniform developer layer and prevent the developer from leaking. It is an object of the present invention to provide a developing device capable of improving reliability and reliability of operation.

[Structure of the Invention] (Means for Solving the Problems) In the developing device of the present invention, a one-component non-magnetic developer contained in a housing having an opening is frictionally charged by an elastic member to form a layer on the developing roller. And a developing unit that supplies the electrostatic latent image to an image carrier on which an electrostatic latent image is formed from the opening of the chassis while carrying it and develops it, and a region of a developing roller in the chassis that faces non-developing regions on both ends of the image carrier. And a width extending from both ends of the developing roller to a position where the developing roller is inserted and held in a groove formed in a side wall of the housing located at both ends of the developing roller and covers both end regions of the opening of the housing. As described above, from a flexible member having a low coefficient of friction wound around such a degree that the developer intervening along the peripheral surface of the developing roller and the peripheral surface of the developing roller can be moved by receiving the rotational force of the developing roller. And a film member The one in which the features.

(Operation) The operation of the apparatus having the above configuration will be described below.

The one-component non-magnetic developer supplied from the housing for the developing device to the developing roller is uniformly pressure-contacted with the peripheral surface of the developing roller while being triboelectrically charged by the elastic member to form a uniform layer. At this time, the non-developing area on both ends of the developing roller and the both end areas of the opening portion of the housing are continuously covered with the film member, and the film member is arranged at a position in contact with the side wall of the housing. Since the film member is arranged so that the developer interposed between the film member and the developing roller can be moved by receiving the rotational force of the developing roller, the leakage of the one-component non-magnetic developer to the image carrier side and the outside. Outflow is completely prevented.

Further, since the film member is made of a flexible material having a low coefficient of friction, the developing roller is not scratched and the layer formation is not hindered.

(Embodiment) The 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 8 of the present invention is applied will be described. FIG. 1 is a schematic sectional view of the copying machine. In FIG. 1, reference numeral 1 denotes a copier housing, in which a drum-shaped photosensitive member 2 made of an image carrier, such as selenium, on the surface of which a charge image, for example, an electrostatic latent image is formed, can rotate. , A lamp 4 and a converging light for forming an image of the original on the surface of the photoconductor by optically scanning the original placed on the original table 3 which horizontally reciprocates. A surface of the photoconductor 2; a transmitter 5; a discharge lamp 6 for discharging the surface of the photoconductor 2 before forming an image of a document; a charger 7 for uniformly charging the surface of the photoconductor 2 after the charge is removed. The developing device 8 of the present embodiment for selectively flying a developer on the electrostatic latent image formed on the surface of the photosensitive drum to develop the electrostatic latent image is provided. It has become so. A paper feeding unit 10 is provided on one side (the right side in the drawing) of the copying machine housing 1,
For example, a paper feed cassette 11 that is detachable from the side, a paper feed roller 12 that rolls onto the uppermost sheet of the paper P stored in the paper feed cassette 11 and sends it out to the front, and manual paper feed. It is composed of a manual paper feed guide 13 for paper and a carrying roller 14 for carrying the paper inserted from the manual paper feed guide 13 forward. The sheet fed from the sheet feeding section 10 is conveyed by the registration rollers 15 so that the sheet is slidably contacted with the photosensitive member 2 at a conveying timing. In the vicinity of the conveyed paper and on the peripheral side of the photoconductor 2, a pre-transfer charger 9, a transfer charger 16 for transferring the developer forming the visible image onto the paper, and a paper after the transfer from the photoconductor are transferred. A peeling charger 17 for peeling is provided. Furthermore, the paper that has received the transfer of the developer is
The fixing device 20 is conveyed by 19 and guided to the fixing device 20.
The developer is fixed by the pressure and heat of the heat roller pair 21 that makes up the
It is ejected to 23.

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

2 is a schematic perspective view of the developing device, FIG. 3 is a side sectional view of the developing device, and FIG. 4 is a partial detailed perspective view of the developing device.

The developing device 8 uses a non-magnetic developer, and side frames 32 and 33 are attached to both sides of a back frame 30 and a front frame 31 which are spaced apart from each other, so that a housing 34 for the developing device is formed. The upper end opening 34A is provided with an openable / closable lid 41 for replenishing the developer, and in the vicinity of the lower end opening 34B, a developer carrying member for carrying the developer on the surface and transporting it, for example, aluminum. Alternatively, a developing roller 35 made of stainless steel or the like is rotatably supported by the both side frames 32 and 33 to constitute a developing means.

Further, between the front frame 31 and the developing roller 35,
An elastic member for forming a developer layer, such as a silicone butadiene rubber (hardness: 40 degrees to 45 degrees), which forms a developer layer by adhering the developer T, which is pressed against the developing roller 35 and has entered under pressure, to the surface of the developing roller 35. Degree), urethane rubber, stainless steel, phosphor bronze (thickness of about 0.07 mm to 0.2 mm), or an urethane blade formed of an elastic blade 36 is attached to the front frame 31 via a blade holder 37 in a cantilevered manner. There is.

The elastic blade 36 can be finely adjusted in pressure contact with the developing roller 35 by adjusting the position of the blade holder 37 and the like.

In particular, since the elastic blade 36 is pressed against the developing roller 35 so that a part of the surface facing the developing roller 35 is in surface contact, it is compared with a structure in which the free end of the elastic blade 36 is pressed. The contact area between the elastic blade 36 and the developing roller 35 can be increased. Therefore, fine adjustment of the pressure contact pressure to the developing roller 35 is easy and the pressure contact pressure can be made uniform, and further, the developer is subjected to friction under the pressure contact pressure for a longer period of time, and the developer is evenly distributed. Sufficient triboelectric charge can be obtained.

Then, on both sides of the developing roller 35, for example, a non-development area which is a peripheral surface area of a non-development width b formed outside a development area which is a peripheral surface area of a maximum development width a substantially equal to the maximum image formation width of the photoconductor 2. The cover body 50 as a member for covering the area is the casing 34.
It is provided inside.

The cover body 50 is made of a flexible member having a relatively small coefficient of friction (hereinafter referred to as a film member) such as a polyester film, a nylon film, or a urethane foam film, and one end of the front frame 31 via the blade holder 37. The other end is attached to the back frame 30 via the film holder 30A and is wound around the peripheral surface of the non-developing area.

The film member 50 is a developing roller 35 in the direction of the arrow.
It is not firmly adhered to the surface of the developing roller 35 so as to brake the rotation of the developing roller 35. It is attached.

Further, the peripheral end portion 50A of the film member 50 along the peripheral surface of the developing roller 35 has an end surface 35A of the developing roller 35 as shown in FIG.
As shown in FIG. 5, the peripheral end portion 50A projects further than the groove portion 33A (32A) formed in the side frames 32, 33.
A) Inserted and held. It should be noted that it is possible to fill the gap between the groove 33A (32A) and the peripheral end 50A with a filler such as a silicon compound.

Further, as shown in FIG. 2, in the housing 34, a guide is arranged in a slanted shape as a guide member for guiding the developer to the surface of the developer carrying member located between the film members 50, for example, the developing area. Plates 52, 52 are provided.

The developing device 8 is arranged at a position where the developer applied to the developing roller 35 is not in contact with the photoconductor 2. This non-contact arrangement relationship is determined by the particle size of the developer, the layer thickness of the developer applied to the developing roller 35, etc.
The distance between the developing roller 35 and the photoconductor 2 must be as small as possible in order to reliably fly the developer and obtain a high-quality image, and for that purpose, the applied developer layer is a thin layer. Since it is desirable to be present and the range of the particle size of the developer to be used is also determined in relation to the resolution, the gap size between the two is practically about 10 μm to 300 μm.

In order to hold this gap size, for example, a gap regulating roller 39 is integrally rotatably attached to the shaft of the developing roller 35, and the gap regulating roller 39 is provided on both sides of the photosensitive member 2 or the photosensitive member 2. The photoconductor 2 and the developing roller 35 are brought into contact with a receiving roller (not shown) attached to the shaft of the body 2.
The distance between the heart and is kept constant.

Further, a power source (not shown) for applying a voltage to the developing roller 35 to form an electric field between the photoconductor 2 and the developing roller 35 can be provided. This power source facilitates the developer on the developing roller 35 to fly to the surface of the photosensitive member 2 by the electric field formed between the photosensitive member 2 and the developing roller 35, and is not always necessary. This is because the developer triboelectrically charged on the developing roller 35 is sufficiently fly to the surface of the photoconductor by only the electrostatic attraction force generated by the latent image charge on the surface of the photoconductor.

Reference numeral 54 in FIG. 3 denotes a developing roller which prevents the developer contained in the housing 34 from falling and which is used after the development.
A collecting blade that collects the developer remaining on the surface of the casing 35 to the inside of the casing 34, and is elastically pressed against the surface of the developing roller 35 at an appropriate pressure.

Next, the operation and effect of the developing device 8 will be described.
When the housing 34 is filled with a non-magnetic developer and the developing roller 35 rotates in the direction of the arrow shown in FIGS. 2 to 4, the developer is conveyed by the elastic blade 36 and the developing roller 35.
It enters under pressure contact with and is frictionally charged by contact with the elastic blade 36 and the like.

The frictionally charged developer is gradually and uniformly thinned by the pressure contact pressure between the elastic blade 36 and the development roller 35, and is attached to the surface of the development roller 35 and conveyed.

The developer conveyed in this way is transferred to the developing roller 35.
The electrostatic attraction force generated by the electric field formed between the photoconductor 2 and the photoconductor 2 or the latent image charge on the photoconductor 2 surface causes the electrostatic latent image to fly to the photoconductor 2 surface, and the electrostatic latent image on the surface is developed. It will be. When development is done in this way,
If the developer leaks from both sides of the developing roller 35,
The developer is received by the film member 50, and it is possible to prevent the developer from being scattered to the outside of the developing device casing by the centrifugal force generated by the rotation of the developing roller 35.

Further, the conveyance force due to the rotation of the developing roller 35 is received between the film member 50 and the developing roller 35, and is collected inside the housing 34. Therefore, the leaked developer is prevented from being filled between the developing roller 35 and the film member 50 and flowing out of the housing 34. Further, the peripheral edge portion 50 of the film member 50
A is a groove portion 33A (32
Since it is inserted and held in (A), the developer collected and conveyed between the developing roller 35 and the film member 50 is prevented from flowing out from the gap between the side frames 32, 33 and the film member 50. .

Further, the developer accommodated in the housing 34 is the guide plate.
Since it is supplied to the developing area on the developing roller 35 while being guided by the 52, 52, the developing roller passes through the non-developing area.
35 It is possible to reduce the rate of developer leakage from both ends.

Needless to say, the above embodiment is an example and various modifications can be made within the scope of the present invention.

For example, the developer applicable to the present invention is not limited to the non-magnetic developer and may be a magnetic developer. Further, the developer carrying member can be replaced with not only a metal drum such as aluminum or stainless steel but also a metal plate or belt, and the surface thereof can be subjected to alumite treatment or chrome plating. In particular, such a surface treatment can prevent abrasion of the surface of the developer carrier, and can improve the temporal stability of development and prolong the life of the developer carrier.

The charge image that can be developed by the present developing device is not limited to that formed by the copying machine shown in FIG. 1, and the pattern of charged particles formed by a cathode ray tube, laser light, needle electrode, light emitting diode, etc. Anything will do.

[Advantages of the Invention] According to the invention described in detail above, with the above configuration, the one-component non-magnetic developer supplied from the inside of the developing device housing to the developing roller is developed while being frictionally charged by the elastic member. A uniform layer is formed by uniformly pressing the roller peripheral surface. At this time, the non-developing area on both ends of the developing roller and the both end areas of the opening portion of the housing are continuously covered with the film member, and the film member is arranged at a position in contact with the side wall of the housing. Since the film member is arranged so that the developer interposed between the film member and the developing roller can be moved by receiving the rotational force of the developing roller,
Leakage of the one-component non-magnetic developer to the image carrier side and the outside is completely prevented.

Further, since the film member is made of a flexible material having a low coefficient of friction, the developing roller is not scratched and the layer formation is not hindered.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a copying machine to which the developing device of the present invention is applied, FIG. 2 is a schematic perspective view showing an embodiment of the developing device of the present invention, and FIG. 3 is a side sectional view of the same. FIG. 4 is a partial detailed perspective view of the developing device, and FIG. 5 is a partial front sectional view of the developing device. 2 ... Image carrier, 8 ... Developing device, 34 ... Housing, 35 ... Developing roller, 50 ... Film member, 52 ... Guide member.

Claims (1)

[Scope of utility model registration request] 1. A latent electrostatic image is formed from the opening of the housing while a one-component non-magnetic developer contained in the housing having the opening is triboelectrically charged by an elastic member to form a layer on a developing roller and is conveyed. Developing means for supplying the developed image carrier to the developed image carrier,
A region of the developing roller in the casing facing the non-developing regions on both ends of the image carrier, and a position projecting from both ends of the developing roller and being inserted and held in a groove formed in a casing side wall located at both ends thereof. And a developer interposed between the developing roller and the peripheral surface of the developing roller along the peripheral surface of the developing roller so as to cover both end regions of the opening of the housing. A developing device, comprising: a film member made of a flexible member having a low coefficient of friction wound so as to be movable by receiving a rotational force.