JP3044104B2 - Developer supply peeling member, developing device having this member, and image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine , an image recording apparatus , a printer , a facsimile, etc., which is formed on a latent image carrier made of an electrophotographic photosensitive member or an electrostatic recording dielectric. an electrostatic latent image, developing the developer supply peeling unit for developing with a developing apparatus to be used to visualize, in particular a one-component developer containing no carrier, this
To a developing device and an image forming apparatus having the same .

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying apparatus, an image recording apparatus , a printer and a facsimile, a latent image carrier formed of an electrophotographic photosensitive member or an electrostatic recording dielectric is formed. The developed electrostatic latent image is developed by a developing device and visualized as a toner image.

As one of such developing devices, various dry single-component developing devices have been proposed and put into practical use. However, it is difficult for any developing device to form a thin layer of toner, which is a one-component developer, on a developer carrier.

However, at present, there is a demand for improvements in image resolution, sharpness, etc., and development of a method and an apparatus for forming a thin layer of toner is indispensable. Proposed.

For example, as disclosed in Japanese Patent Application Laid-Open No. 54-43038, an elastic blade made of rubber or metal is brought into contact with a developing sleeve of a developer carrier, and the elastic blade is brought into contact with the developing sleeve. In some cases, the toner is allowed to pass between the portions to regulate the toner so that a thin layer of toner is formed on the developing sleeve, and sufficient tribo is given to the toner by friction at the contact portion.

In this case, when the non-magnetic toner is regulated by the elastic blade, a toner supply member for supplying the toner onto the developing sleeve is separately required. this is,
In the case of a magnetic toner, the toner can be supplied onto the developing sleeve by the magnetic force of a magnet in the developing sleeve,
This is because in the case of non-magnetic toner, supply of toner by magnetic force cannot be performed.

Accordingly, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 58-116.
No. 559 proposed a developing device shown in FIG. In this developing device, a fur brush structure is provided in a developer container 2 containing a non-magnetic toner 6 as a one-component developer at a position upstream of the elastic blade 4 in the rotation direction of the developing sleeve 3 and in contact with the developing sleeve 3. An elastic roller 15 is provided so that the toner 6 remaining without being consumed in the development on the developing sleeve 3 is peeled off by the elastic roller 15 and new toner 6 is supplied onto the developing sleeve 3.

As a result, a thin layer of the non-magnetic toner 6 can be satisfactorily formed on the developing sleeve 3, so that the electrostatic latent image on the photoreceptor 1 can be satisfactorily developed. Thus, it has become possible to faithfully reproduce a wide area solid black image to obtain a good image.

However, the above-described elastic roller having a fur brush structure is formed by implanting fibers such as nylon and rayon on a metal core, and the elastic roller due to the detachment of the fibers when the developing device is repeatedly used for a long period of time. The fiber is clogged between the blade and the developing sleeve, causing white streaks at that part, or the falling of the fiber, causing poor contact of the elastic roller with the developing sleeve, resulting in insufficient reproduction of a solid black image due to insufficient toner supply and stripping. Sometimes it was enough.

In view of this, the elastic roller is made of an open-cell foam such as a polyurethane foam having a foam skeleton structure and a relatively low hardness, so that the elastic roller is brought into contact with the developing sleeve with a light pressure and an excessive pressure is applied to the toner. It is possible to supply the toner onto the developing sleeve and remove the remaining toner that is not consumed in the development with appropriate unevenness on the foam surface without adding the toner.

[0011]

However, in such a developing device, since the elastic roller is formed of a relatively low-density open-cell foam, the toner having a small particle size can be used especially in a high humidity environment. When used, the toner gradually enters inside the bubbles of the elastic roller as the developing operation is repeated many times. When such toner clogging reaches the entire foam of the elastic roller, the elastic roller is hardened, and the contact pressure of the elastic roller against the developing sleeve becomes excessive, resulting in an increase in the driving torque of the developing sleeve and the elastic roller, or the elastic roller against the developing sleeve. Unevenness was observed in the application and peeling of the toner, and the coating was uneven on the developing sleeve, which was not preferable.

In order to prevent such inconvenience caused by toner clogging in the elastic roller, the following configuration is conceivable. A skin layer for preventing toner clogging is provided on the surface of the elastic roller. The elastic roller is made of a single-cell foam. The cells (bubbles) of the open-cell foam are made as fine as possible and a cell having a high density is used.

However, the use of the elastic roller having the above-mentioned structure has the following disadvantages.

First, when the skin layer is brought into contact with the surface of the developing sleeve and rubbed, the function of rubbing the toner onto the developing sleeve on the surface of the skin layer is too strong. The above toner is unfavorably fused, or the toner undergoes a change in physical properties (toner deterioration), resulting in an increase in fog. Further, even in a configuration in which the skin layer surface is appropriately roughened, the same problem could not be prevented because the hardness is locally higher (the local pressure on the toner and the developing sleeve is higher) than the foam surface.

In the structure (1), the application and peeling of the toner onto the developing sleeve can be performed satisfactorily in the same manner as in the case of the open-cell foam due to the unevenness of the surface of the single-cell foam. Compared to open-cell foam, single-cell foam has higher hardness and rebound resilience, and the hardness of the elastic roller is too high, so that the elastic roller is stably and securely abutted against the developing sleeve. If this is the case, the contact pressure on the developing sleeve and the toner becomes excessively large, causing an increase in driving torque of the developing sleeve and the elastic roller, and an increase in fog due to a change in physical properties of the toner due to durability (toner deterioration). Occurs. In order to prevent such inconvenience, the hardness of the single-cell foam may be reduced as much as possible. However, in this case, a large amount of the oil component is contained, and the elastic roller is kept in contact with the developing sleeve and the toner in a high-temperature environment. When left for a long period of time, the oil component seeps out, the oil adheres to the developing sleeve and the toner, and toner fusion to the developing sleeve occurs. When the toner is fused on the developing sleeve in this way,
The toner newly supplied to the developing sleeve is rubbed with the toner fused on the developing sleeve, so that an appropriate tribo cannot be provided and fogging due to shortage of the tribo occurs, which is not preferable.

In addition, when the structure is adopted, the cells are made as small as possible with respect to a general open cell foam having a cell number, for example, a foam such as a polyurethane foam having 30 to 50 cells / inch (cell number). The use of an open-cell foam can prevent the toner inside the elastic roller from invading to some extent, but the overall hardness becomes too high as in the case of the above, and the same problem occurs. That is, it is not preferable because the driving torque of the elastic roller and the developing sleeve is increased and the fog is increased due to the deterioration of the toner.

The present invention solves the above problems, and supplies and removes the toner onto the developing sleeve without applying excessive pressure to the developing sleeve and the toner on the developing sleeve even during long-term use. It is an object of the present invention to provide a developer supply / peeling member, a developing device , and an image forming apparatus that can satisfactorily remove toner.

[0018]

According to the present invention, the above object is achieved by providing a developer supply / peeling member with a developer carrier.
Developer supply and release member for supplying and removing the developer
In the outermost layer of a single-cell foam, and the inside of the outermost layer
This is achieved by having an open-cell foam provided . The above object is to supply the developer to the developer carrier.
The developer supply / peeling member that feeds and peels
An outermost layer of a foam, and the above unit provided inside the outermost layer.
To have a single-cell foam with a lower density than the foam
This is also achieved. And for the developing device,
This is achieved by having a developer supply peeling member having a configuration.
You. Further, with respect to the image forming apparatus,
A developer supply peeling member, a developer carrier, and an image carrier.
And an alternating voltage between the developer carrier and the image carrier.
Is applied.

[0019]

According to the present invention , the outermost layer of the developer supply / peeling means is a single-cell foam, and the inner side thereof is open-cell or
As a low-density, single-cell foam, the foam is made of foam whose compression elasticity is gradually increased from the support axis side to the surface in the radial direction. On the side, the compression elasticity is low, so that an appropriate hardness is maintained and an excessive contact pressure is not applied to the developer carrier and the developer. Thus, the supply and peeling of the developer can be performed satisfactorily for a long time without applying an excessive pressure to the developer carrier.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment and a second embodiment of the present invention will be described with reference to the drawings.

<First Embodiment> First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram showing a first embodiment of the developing device of the present invention. In FIG. 1, reference numeral 2 denotes a developer container that contains a non-magnetic toner 6 as a one-component developer, and has an opening extending in the longitudinal direction of the developing device (perpendicular to the paper surface). In the opening,
A developing sleeve 3 that rotates in the direction of arrow b in the figure is provided as a developer carrier, and the developing sleeve 3 protrudes into the developer container 2 through the opening at the substantially right half peripheral surface shown in the figure. The left half of the outer peripheral surface is exposed to the outside of the developer container 2 and is laterally provided. The surface exposed to the outside of the developer container 2 is disposed so as to face the photosensitive member 1 serving as a latent image carrier rotating in the direction of arrow a with a slight minute interval. Is developed to be visualized as a toner image.

The developer container 2 of the developing sleeve 3
An elastic blade 4 as an elastic regulating member
The developing sleeve 3 is provided so as to be inclined downward toward the upstream side in the rotation direction of the developing sleeve 3, and is in contact with the outer peripheral surface of the upper portion of the developing sleeve 3 in the rotating direction. As a result, the toner 6 carried on the developing sleeve 3 is rubbed at the contact portion between the elastic blade 4 and the developing sleeve 3 to apply triboelectric charge, and the toner 6 entering between the contact portions is developed. It is applied on the sleeve 3 to form a thin layer of the toner 6.

Further, an elastic roller 5 is provided at a position upstream of the elastic blade 4 in the rotation direction of the developing sleeve 3 as a developer supply / peeling means. The elastic roller 5
Is in contact with a portion of the developing sleeve 3 opposite to the photoreceptor 1 and is rotatably supported. The elastic roller 5
By the rotation, the toner 6 is carried and supplied to the vicinity of the developing sleeve 3, and the toner 6 is rubbed on the developing sleeve 3 at a contact portion between the developing sleeve 3 and the elastic roller 5, so that the toner 6 is placed on the developing sleeve 3. The toner 6 is attached.

Next, the configuration of each means of the apparatus of the present embodiment as described above will be described in detail. First, as the photoconductor 1, a so-called xerographic photoconductor which forms an electrostatic latent image by, for example, the Carlson process,
No. 910, a photosensitive member having an insulating layer on the surface on which an electrostatic latent image is formed by an NP process, an insulator forming an electrostatic latent image by an electrostatic recording method, and forming an electrostatic latent image by a transfer method An insulator or a member that forms an electrostatic latent image (including a potential latent image) by an appropriate method is used.

The developing sleeve 3 is made of a material such as aluminum , stainless steel or the like, but a conductive rubber roller may be used. The form is not limited to a cylindrical body (sleeve) but may be an endless belt that is driven to rotate. The developing sleeve 3 in this embodiment has a moderately roughened surface on its surface, which increases the probability of rubbing between the surface of the developing sleeve 3 and the toner 6 and improves the transportability of the toner 6. Have improved.

The rough surface of this unevenness has a surface roughness Rz of 1 to 10
It is obtained by performing sandblasting on the surface of the developing sleeve 3 with irregular shaped random grains or sandblasting with fixed glass beads so as to have a thickness of μm. Alternatively, a convex rough surface is formed on the surface of the developing sleeve 3 by using conductive particles such as metal oxide particles , graphite , and carbon , which can form a convex surface alone, and forming the convex rough surface. Phenolic resin ,
The surface of the binder resin may be formed with a concave portion by binding with a binder resin such as a fluororesin, thereby obtaining a roughened surface on the surface of the developing sleeve 3. In this embodiment, as the developing sleeve 3, an aluminum sleeve having a diameter of 16 mm is used as a base, and the surface of the developing sleeve 3 is subjected to a blasting process using fixed glass beads (# 600) to obtain a surface roughness R.
Those having z of about 3 μm were used.

Next, the elastic roller 4 is formed of a rubber member such as silicone or urethane (having a hardness prescribed by JISA of 40 ° to 90 °), and the elastic blade 4 is opposed to the developing sleeve 3. A part of the surface comes into contact with the surface, and presses against the developing sleeve 3. The contact pressure of the elastic blade 4 with the developing sleeve 3 in the present invention is preferably 5 to 200 g / cm as a linear pressure in the generatrix direction of the developing sleeve 3.
A urethane rubber blade having a thickness of 1.2 mm and a thickness of 1.2 mm was used, and was brought into contact with the developing sleeve 3 at a linear pressure of 50 g / cm. The linear pressure was measured by stacking three thin plates with known friction coefficients and inserting them into the abutting part of the elastic blade 3. The center thin plate was pulled out with a spring scale, and converted from the pulling force at that time and the friction coefficient. And the linear pressure.

The non-magnetic toner 6 is used as a non-magnetic one-component developer, and is obtained by dispersing a pigment such as carbon in various thermoplastic resins such as styrene resin, acrylic resin and polyethylene resin. I have. In the present embodiment, the toner 6 has an average particle diameter of 8 μm comprising a copolymer of styrene-acryl resin and styrene-butadiene resin and a pigment.
Was used in which 1.0% of colloidal silica was externally added to the above toner powder.

In the apparatus having the above-described structure, when the elastic roller 5 rotates (in the direction c in FIG. 1) as described above, the toner 6 is supplied and carried by the developing sleeve 3, and the elastic blade 4 and the developing sleeve 3 Is frictionally charged at the abutting portion. The charged toner 6 escapes from the contact portion between the elastic blade 4 and the developing sleeve 3, forms a thin layer of the toner 6 on the developing sleeve 3, and faces the photoreceptor 1 at a small interval. Transported to the department. In the developing section, an alternating voltage in which DC and AC are superimposed is applied as a developing bias between the developing sleeve 3 and the photoconductor 1, so that the toner 6 on the developing sleeve 3 becomes an electrostatic latent image on the photoconductor 1. Correspondingly transfers, adheres to the electrostatic latent image, develops and visualizes as a toner image.

On the other hand, the toner 6 remaining on the developing sleeve 3 without being consumed
Is collected into the developer container 2 from the lower part of the developing sleeve 3 with the rotation of. A seal member 7 is provided at a toner collecting portion of the developer container 2, and the seal member 7 allows the toner 6 remaining on the developing sleeve 3 to pass into the developer container 2, and The toner 6 collected in the developer container 2 for preventing the toner 6 in the container 2 from leaking from the lower portion of the container 2 is separated from the developing sleeve 3 by the elastic roller 5 at a contact portion with the developing sleeve 3. Stripped. At the same time, new toner 6 is supplied onto the developing sleeve 3 by the rotation of the elastic roller 5, and the new toner 6 is conveyed again to the contact portion between the developing sleeve 3 and the elastic blade 4 with the rotation of the developing sleeve 3. . Most of the peeled toner 6 is conveyed and mixed into the toner 6 in the developer container 2 with the rotation of the elastic roller 5, and the charged charge of the peeled toner 6 is dispersed. You.

As described above, in the developing device such as the present embodiment, the role played by the elastic roller 5 in supplying and peeling off the toner is important. It is necessary to exhibit its performance over a wide range. For this reason, in this embodiment, the elastic roller 5 has the following configuration.

As shown in FIG. 2, the elastic roller 5 has a metal cored bar 51 as a support shaft, and a low-hardness open-cell foam made of polyurethane foam or the like having a low compression elasticity sequentially from the support shaft side to the outside. 52, and a single-cell foam 53, such as silicone or CR rubber sponge, whose wall surface is not in communication with an adjacent cell portion.

As described above, by adopting a configuration in which a single-cell foam is provided on the outermost layer of the elastic roller and a low-hardness open-cell foam having low compression elasticity is provided inside the elastic roller,
The elasticity of the elastic roller 5 can be reliably brought into contact with the developing sleeve 3 without reducing the overall hardness and making the contact pressure with the developing sleeve 3 excessive. The peeling of the undeveloped toner 6 on the developing sleeve 3 and the supply of new toner 6 are favorably performed by the wall surface of the bubble portion of the single-cell foam 53 of the outermost layer. It is possible to prevent the toner 6 from being clogged inside.

In this embodiment, the elastic roller 5 has an outer diameter.
A 4 mm metal core body 51 is made of poly as an open-cell foam 52.
Urethane foam (brand name malt filter, density 0.0
30g / cm^Three ) Is coated in a roller shape with a thickness of 3 mm.
In addition, silicone foam is formed on the outside as a single-cell foam 53.
Body (rubber hardness Asker C 14 °, density 0.31g /
cm^Three) With a roller thickness of 2 mm and an outer diameter of 14 m
m. This elastic roller 5 is a developing sleeve
Approximately 1-10mm is required for the contact width (nip) with 3
In the embodiment, the contact width is set to about 5 mm.

It is preferable that the relative speed between the elastic roller 5 and the developing sleeve 3 is 20 to 200 mm / s . In this embodiment, the peripheral speed of the developing sleeve 3 is increased by 50 mm / s in the direction of arrow c. s and the relative speed was 120 mm / s.

The developing device of the present invention is incorporated in a copier FC-5 manufactured by Canon Inc., and the surface potential of the electrostatic latent image on the photoreceptor 1 is set to -600 V in the dark area and -150 V in the bright area. The developing bias applied to the sleeve 3 was obtained by superimposing a DC voltage of -250 V on an AC voltage having a frequency of 1800 Hz and a peak-to-peak voltage of 1200 V. Further, the peripheral speed (process speed) of the photoconductor 1 is about 50 mm.
/ S, the peripheral speed of the developing sleeve 3 was set to about 70 mm / s, and the copying operation of about 2,000 sheets was performed. Even when a toner having a small particle diameter was used, image unevenness due to toner clogging in the elastic roller 5 was observed. There is no increase in the driving torque of the developing sleeve 3 and the elastic roller 5, and the developing sleeve 3 and the toner 6
An increase in fogging due to a change in physical properties (toner deterioration) of the toner 6 caused when the contact pressure against the toner is too high did not occur, and a good image faithful to the original and free of fogging was provided from the initial stage to the latter half of the durability.

In this embodiment, the single-cell foam 52 is provided on the outer surface side of the elastic roller 5. However, among the open-cell foams, the cells are as fine as possible (for example, ordinary open-cell polyurethane). (The number of cells of the foam is 30 to 50 cells / inch, whereas 100 cells / inch or more) By using a foam, the effect of preventing toner 6 particles from entering the elastic roller 5 is significantly improved. It is effective when used in a developing device of about 2,000 sheets.

<Second Embodiment> Next, a second embodiment of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted. FIG. 3 is a sectional view of an elastic roller according to a second embodiment of the present invention. In the present embodiment, the configuration of the elastic roller 8 is a metal core 81.
, And a low-density single-cell foam 82 having a low rebound resilience is provided in a cylindrical shape on the outside thereof, and a high-density single-cell foam 83 having a relatively high resilience is provided in a cylindrical shape on the outermost layer. ing.

In this embodiment, the low-density single-cell foam 72 has an Asker C hardness of 8 ° and a density of 0.25 g / c.
a silicone foam m ^3, of the first embodiment and the same slightly high density outside Asker C hardness 14, density 0.3
1 g / cm ³ silicone foam was used. By adopting this configuration, the same effect as that of the first embodiment can be obtained, and the intrusion of the toner 6 from both ends in the longitudinal direction of the elastic roller 5 can be prevented.

In this embodiment, when the elastic roller 8 is made of only the metal core 81 and the low-density silicone foam 82 having low rebound resilience, the contact pressure of the elastic roller 8 with the developing sleeve 3 is reduced. Although it can be further suppressed, since a large amount of an oil component is contained in order to obtain a foam having a low density and a low rebound resilience, undesirably, the developing sleeve is fused by oil seepage during long-term storage as described above. . In the present embodiment, since the foam 83 having almost no oil seepage is provided on the outer periphery of the foam 82 having a low rebound resilience containing a large amount of the oil component, even if the oil seeps, the foam 83 on the outer side is provided. Thereby, it is possible to prevent the oil from reaching the surface side of the elastic roller 8, that is, the developing sleeve 3 side.

[0041]

As described above, according to the present invention,
The surface layer of the developer supply peeling means , the outermost layer is a single-cell foam.
And the inside is made of open-cell or low-density single-cell foam.
The foam is formed such that the compressive elasticity increases from the support axis side toward the outer surface in the radial direction, so that the compressive elasticity of the entire developer supply / peeling means can be kept low, and the developer Prevents the contact pressure against the carrier from becoming excessive and prevents uneven coating on the developer carrier and an increase in drive torque due to clogging of the developer into the developer supply / separation unit that occurs when the developing operation is repeated. However, it is possible to stably peel off the undeveloped developer on the developer carrier and supply the developer to the developer carrier for a long period of time, thereby providing a good image.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a developing device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a developer supply / peeling unit of the apparatus in FIG. 1;

FIG. 3 is a sectional view of a developer supply / peeling unit according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a schematic configuration of a conventional developing device.

[Explanation of symbols]

 2 developer container 3 developing sleeve (developer carrier) 5 elastic roller (developer supply / peeling member)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-296267 (JP, A) JP-A-63-103276 (JP, A) JP-A-62-179757 (JP, U) JP-A-63-179757 198062 (JP, U) Japanese Utility Model 63-187159 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08-15/08 507 F16C 13/00

Claims (4)

(57) [Claims] 1. A method for supplying a developer to a developer carrier,
In the developer supply peeling member for peeling, a single-cell foam
Outermost layer, and open-cell foam provided inside the outermost layer
Developer supply peeling member characterized by having a. 2. A method for supplying a developer to a developer carrier,
In the developer supply peeling member for peeling, a single-cell foam
An outermost layer, and the above-mentioned closed cell foam provided inside the outermost layer.
It is characterized by having a single-cell foam having a lower density than a foam
Developer supply peeling member . 3. The developer supply according to claim 1 or claim 2.
A developing device comprising a supply / separation member . 4. The developer supply according to claim 1 or claim 2.
A supply / separation member, a developer carrier, and an image carrier;
Alternating voltage is applied between the developer carrier and the image carrier
An image forming apparatus, comprising: