JP2003316152A - Single-component developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a developing device that prevents agglomeration and caking of single-component toner while extending its life and allows long-time use. <P>SOLUTION: The single-component developing device has: a developing roller 1 which is situated in contact with or close to a photoreceptor body having an electrostatic latent image formed thereon and is rotated during image formation for rendering the electrostatic latent image visible by attaching the single- component toner to the photoreceptor body; a toner supply roller 2 which supplies the single-component toner to the developing roller 1; and a toner restricting roller 4 which forms a toner thin layer on the developing roller 1 by restricting the amount of the single-component toner sticking to the developing roller 1. When development is not carried out, the roller 1 is rotated in a direction opposite to the direction of the rotation used for development. At least the toner-thin-layer-forming part of the toner restricting roller 4 has a crown shape in which the outer diameter at the center of the shaft is greater than the outer diameters at both ends of the shaft. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-component developing device used in an electrophotographic apparatus such as a copying machine, a facsimile machine, a printer, and a complex machine thereof, and an image forming apparatus equipped with the one-component developing device.

[0002]

2. Description of the Related Art Conventionally, as a one-component developing device used in an electrophotographic apparatus, for example, in order to make an electrostatic latent image visible by contacting an image carrier on which an electrostatic latent image is formed and adhering one-component toner. The developing roller that rotates during image formation, the toner supply roller that is placed in contact with the developing roller to supply the one-component toner to the developing roller, and the amount of the one-component toner that adheres to the developing roller are regulated to develop the image. A roller having a toner regulating member for forming a thin toner layer on a roller is known.

[0003]

In this type of one-component developing device, it is essential to uniformly charge the one-component toner at a high voltage in order to prevent fog and ghost from occurring and maintain image quality. Therefore, it is important to select the surface material of each component that is frictionally charged by contacting with the one-component toner.

In recent years, due to environmental problems, it has been required to extend the life of the one-component developing device. However, regarding the surface of each component, the one-component toner aggregates and adheres to the surface of the toner regulating member and the surface of the developing roller. It is necessary to deal with the deterioration of the surface of the developing roller and the surface of the toner regulating member due to scratches, cracks, peeling and the like. Further, there is also a need to be able to deal with internal contamination of the image forming apparatus due to toner leakage and scattering for long-term use as a one-component developing device.

The reason why the one-component toner agglomerates and adheres to the toner regulating member and the developing roller is considered to be that the one-component toner is clogged in the wedge-shaped area having the wedge-shaped cross section that exists at the contact portion between these two parts. To be

As a means for preventing the aggregation of the one-component toner, Japanese Patent Application Laid-Open No. 5-142938 discloses a structure in which a mechanism for vibrating a flat plate (blade) toner regulating member is provided. Since a large number of components are required to vibrate the blade, there is the inconvenience that the developing unit is extremely complicated and has a large scale. Further, in this blade method, since the contact portion with the developing roller is limited, the contact portion is mechanically worn, and there is a disadvantage that it is difficult to extend the life of the developing device due to deterioration due to wear.

As means for preventing the toner aggregation and sticking, in JP-A-11-84867, a toner regulating member is constituted by a toner regulating roller, and the toner regulating roller is rotated at a predetermined timing during non-developing. A configuration is proposed.

In the developing device disclosed in Japanese Unexamined Patent Publication No. 11-84867, the contact portion between the developing roller and the toner regulating roller is increased as compared with the developing device in which the toner regulating member is of the blade type. It is effective to prevent mechanical abrasion of the surface and developing roller.

However, the developing roller always rotates in a fixed direction during development and non-development, and the toner regulating roller rotates in a direction opposite to the rotation direction of the developing roller. As a measure to prevent accumulated toner agglomerated powder from moving toward the downstream side, pressure is applied to the toner agglomerated powder to easily cause scratches on the surface of the developing roller and the surface of the toner regulation roller, and to prevent toner aggregation and sticking. Not preferable. Therefore, in an image forming apparatus using this type of developing device, the number of times of image formation is limited to about 6,000 sheets, and it is insufficient to expect a long life.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to prevent agglomeration and sticking of one-component toner from occurring while extending the life thereof, and to enable long-term use. Another object of the present invention is to provide a developing device and an image forming apparatus using the developing device.

[0011]

In order to achieve the above object, the invention of claim 1 is characterized in that the one-component toner is adhered to or brought into contact with or close to an image carrier on which an electrostatic latent image is formed. A developing roller that is rotated at the time of image formation to visualize the electrostatic latent image, a toner supply roller that supplies the one-component toner to the developing roller, and an amount of the one-component toner that adheres to the developing roller are regulated. And a toner regulating roller for forming a thin toner layer on the developing roller, wherein the developing roller is rotated in a direction opposite to the rotation direction during image formation during non-developing. In the one-component developing device, at least the portion forming the toner thin layer has a crown shape in which the outer diameter at the axial center is larger than the outer diameter at both ends in the axial direction.

According to a second aspect of the present invention, the contour shape of at least the portion of the toner regulating roller where the thin toner layer is formed is a part of a quadratic curve when the section is taken along the longitudinal direction. The one-component developing device according to claim 1.

According to a third aspect of the invention, there is provided the one-component developing device according to the first or second aspect, wherein polar rubber is used for the elastic layer provided in the toner regulating roller.

The invention according to claim 4 is characterized in that a metal base material provided on the toner regulating roller and an elastic layer covering the circumferential direction of the metal base material are bonded by an adhesive.
3 is a one-component developing device.

A fifth aspect of the present invention is the one-component developing apparatus according to the fourth aspect, wherein nitrile-butadiene rubber or epichlorohydrin rubber is used as the elastic layer material of the toner regulating roller.

The invention according to claim 6 is the one-component developing apparatus according to claim 4, wherein the adhesive is a conductive adhesive.

The invention of claim 7 is characterized in that a resin layer is formed on the outer periphery of the elastic layer.
1 is a one-component developing device.

The invention according to claim 8 is an image forming apparatus including the one-component developing device according to any one of claims 1 to 7.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a one-component developing device according to one embodiment of the present invention. As shown in FIG. 1, this one-component developing device is arranged in contact with the developing roller 1 which is arranged in contact with or close to an image carrier (not shown) on which an electrostatic latent image is formed, and in contact with the developing roller 1. , A toner supply roller 2 for supplying one-component toner to the developing roller 1
A toner conveying member 3 that conveys toner toward the toner supply roller 2; a toner regulating roller 4 that regulates the amount of one-component toner adhering to the developing roller 1 to form a thin toner layer on the developing roller 1; A metal spring 6 for pressing and biasing the toner regulating roller 4 against the developing roller 1 and a case 5 having these inside are provided. The spring 6 is not limited to a metal, and any spring having elasticity can be used.

The developing roller 1, the toner supply roller 2 having a sponge layer formed around the metal core shaft, and the toner conveying member 3 are axially supported by a side plate (not shown) of the case 5. Further, the toner regulating roller 4 has a core shaft 4a (see FIG. 2), which is a rotary shaft portion at both ends thereof, rotatably supported by an inner cylinder of a one-way clutch (not shown), and directs the one-way clutch toward the developing roller 1. Urging spring 6
It is placed in contact with the developing roller 1 by the spring pressure.

In this one-component developing device, the one-component toner 7
Is supplied to the surface of the developing roller 1 via the toner conveying member 3 and the toner supply roller 2. The one-component toner 7 supplied onto the developing roller 1 is further transferred to the toner regulating roller 4
The contact pressure is applied to reduce the thickness to a predetermined amount, and the developing roller 1 is rotated so that the developing roller 1 is conveyed to a photoreceptor, which is an image carrier, not shown. The developing roller 1 is in parallel contact with the photoconductor and is applied with a bias voltage substantially intermediate between the charging potential of the photoconductor and the residual potential after optical writing (after exposure). The one-component toner 7 on the developing roller 1 is conveyed to the contact portion with the photoconductor, and the charged one-component toner 7 adheres to the photoconductor according to the developing electric field due to the photoconductor potential and the developing bias to form an electrostatic latent image. Visualized. The toner regulating roller 4 is in contact with the developing roller 1 in a stationary state during the above-described developing operation, but when not developing, the developing operation for one print is performed once at a predetermined timing, for example, at an angle of 10 degrees. It is designed to rotate.

The developing roller 1 in this embodiment has a diameter of 26 m.
m roller made of aluminum, polyester resin, guanamine curing agent and ITO (indium tin oxi
de) and a coating composition dispersed therein were spray-coated and then cured to form a surface layer having a thickness of 10 μm. The surface roughness of the developing roller 1 is 2 according to JIS Rz standard.
The smooth surface was not more than μm. Guanamine is a substance containing an amino group and has a polarity opposite to that of the negatively charged toner. ITO is based on alumina powder and is coated with indium-doped tin oxide on its surface.

The toner supply roller 2 is formed by forming a conductive foam around the metal core shaft and has a resistance value of 10 ^6.
Ω, the same potential as the developing bias is applied to the metal core shaft. The toner regulating roller 4 is an elastic roller because the developing roller 1 is a rigid body. That is, the core shaft 4 which is a core metal made of stainless steel (JIS standard S45C) having a diameter of 10 mm.
The elastic layer 4c, which is a rubber roller coated with a polar rubber such as nitrile rubber or epichlorohydrin rubber on a, is formed by spray coating a fluororesin with a thickness of 20 μm.

FIG. 3 is an explanatory view of the contour line shape of the elastic layer of the toner regulating roller provided in the one-component developing device of FIG. As shown in FIG. 3, the crown amount is the difference between the outer diameter A of the central portion of the toner regulating roller 4 and the average of the outer diameters B and C of both end portions. That is, the crown amount = A- (B + C) / 2.

In the toner regulating roller 4 of this embodiment, the outer diameter A of the central portion is 14 mm, and the outer diameters B and C of both end portions are 1.
It was set to 3.75 mm. That is, a crown having a difference in outer diameter of 250 μm is provided. When the toner regulating roller is made straight as in the conventional case, the both ends of the toner regulating roller are bent by the springs to be bent, and the both ends of the toner regulating roller are worn at about 40,000 sheets and the rubber is exposed. It was confirmed to do. However, in the toner regulation roller 4 of the present embodiment, the uneven wear in the axial direction can be prevented by providing the crown. By providing the crown, not only the life of the toner regulating roller alone can be improved, but also the pressure distribution between the toner regulating roller 4 and the developing roller 1 can be made uniform, and the toner regulating roller relative to the developing roller 1 can be achieved. It is possible to improve the reliability of the roundabout property of No. 4. Specifically, when the above crown is added,
The amount of movement of the toner regulating roller 4 with respect to the amount of rotation of the developing roller 1 was 100%, which was stable, whereas in the case of the straight shape, only 75-80% could be obtained.

FIG. 4 is a diagram showing an example of a crown shape. In FIG. 4, a parabolic shape is shown as an example of the crown shape. The crown shape of the toner regulating roller 4 can be given by an NC grinder. However, when the toner regulating roller 4 has a trapezoidal shape or a polygonal shape, the developing roller 1 is formed at the inflection point.
It was found that a band-shaped toner layer unevenness was generated on the upper side and the dot image was slightly uneven. Therefore, a continuous waveform shape such as an arc shape, a parabolic shape shown as an example in FIG. 4, an elliptical shape, a quadratic curve shape such as a hyperbolic shape,
It became possible to prevent this problem.

As described above, the polar rubber is used as the material of the rubber of the toner regulating roller 4 in order to secure the adhesiveness with the fluororesin of the surface layer having excellent releasability. When a fluororesin is formed on a non-polar rubber such as silicone rubber or ethylene propylene rubber, the rubber and fluororesin cause interfacial peeling, but the above polar rubber shows the destruction of the rubber layer. No problems such as peeling occurred.

FIG. 2 is a sectional view of the toner regulating roller provided in the one-component developing device of FIG. 1, and FIG. 2A shows a toner regulating roller having no adhesive layer between the core shaft and the elastic layer, and FIG. )
Shows the case of a toner regulating roller having an adhesive layer between the core shaft and the elastic layer. Regarding the adhesiveness, FIG. 2 (B)
A rubber roller as an elastic layer 4c and a core metal as a core shaft 4a as a metal base material are bonded together via an adhesive layer 4b as shown in FIG. 2 and an elastic layer 4c as shown in FIG. The durability quality is greatly different from the case where the rubber roller is simply press-fitted into the core metal which is the core shaft 4a. First, the nitrile rubber used as the polar rubber was left to stand in an ozone atmosphere of 5 ppm at 40 ° C. for 1 week. There was no problem with the adhesive product, but cracks occurred from the rubber end face in the press-fit product. This is a result of the oxidation reaction of ozone with respect to the double bond in the nitrile rubber polymer, but this reaction is induced by the tension due to the press-fitting. This is because the adhesive does not apply large tension to the rubber.

Further, it was confirmed that even a rubber having a relatively strong ozone resistance such as hydrin rubber has different durability performances between the adhesive product and the press-fit product. A heat cycle accelerated test was conducted as a condition for transporting and storing parts. The condition is 23 ° C for 2 hours
When 10 cycles were confirmed by setting / 60 ° C. 2 hr / 23 ° C. 2 hr / −30 ° C. 2 hr as 1 cycle, unevenness was generated on the surface of only the press-fitted product. When an image of this was confirmed, unevenness in the toner thin layer and unevenness in image density were observed. It is considered that this was due to swelling on the surface as the rubber repeatedly expanded and contracted.

The structure of the toner regulation roller examined including the above matters is shown below. The core shaft 4a having a diameter of 10 mm
After vulcanizing the rubber of the elastic layer, the roller diameter was 14 mm (center portion in the roller axial direction) by grinding, the outer diameter of both ends was 13.75 mm, and a crown of 250 μm in difference in outer diameter was given. . The surface layer used was formed with a fluorine resin of 20 μm. The thickness of the adhesive layer when the adhesive layer was used was 5 μm.

[Example 1] Elastic layer: NBR (nitrile-butadiene rubber) (JIS
-A hardness 45) Use crown amount: 250 μm (trapezoidal shape) Adhesive layer: None

[Example 2] Elastic layer: NBR (nitrile-butadiene rubber) (JIS
-A hardness 45) Crown amount used: 250 μm (quadratic curve shape) Adhesive layer: None

[Example 3] Elastic layer: EPDM (ethylene propylene rubber) (JIS
-A hardness 45) Crown amount used: 250 μm (quadratic curve shape) Adhesive layer: None

[Example 4] Elastic layer: NBR (nitrile-butadiene rubber) (JIS
-A hardness 45) Use amount of crown: 250 μm (quadratic curve shape) Adhesive layer: use Chemlok 238 (manufactured by Road Far East Co.)

[Example 5] Elastic layer: epichlorohydrin rubber (JIS-A hardness 4
5) Crown amount used: 250 μm (arc shape) Adhesive layer: Chemlock 238 (manufactured by Road Far East Co.) used

[Comparative Example 1] Elastic layer: NBR (nitrile-butadiene rubber) (JIS
-A hardness 45) Crown used: None (straight shape) Adhesive layer: None

Using the toner regulating rollers of Examples 1 to 5 and Comparative Example 1 described above, the toner regulating roller 4 is brought into contact with the core 4 of the toner regulating roller 4 by spring pressure (one side 20).
N). Rotatability of the toner regulation roller 4,
The durability of the toner thin layer uniformity and the image density uniformity in the output image was evaluated. The results are shown in Table 1 below.

[0038]

[Table 1]

However, the follow-around property in Table 1 shows the result of evaluation of the follow-around process of the toner regulating roller 4 during non-developing. Toner of the evaluation standard is 60 when the toner regulation roller 4 is 60.
Those rotated together by more than °, △ indicates that the toner regulation roller 4 is 1
The rotation angle of 0 ° or more and less than 60 degrees indicates that the toner regulation roller 4 has a rotation angle of less than 10 °.

In addition, the evaluation criteria of thin layer uniformity in Table 1 are ○.
Indicates that the one-component toner on the surface of the developing roller after toner regulation is visually uniform, Δ indicates that the one-component toner on the surface of the developing roller after toner regulation is partially uneven, and x indicates the developing roller after toner regulation. The one-component toner on the surface is visually nonuniform on the front surface.

The image density uniformity in Table 1 shows the result of evaluation of the density unevenness of the output image with a solid image and a 600 × 600 dpi 2 × 2 dot pattern. The evaluation criteria x indicates that both the solid image and the dot image were uneven, and Δ indicates that only the dot image was uneven.
Shows the case where uniform concentration was obtained in both cases. In Table 1, 150K is after printing 150,000 sheets and 40K is after printing 40,000 sheets.

From Table 1, in the case where the toner regulating roller 4 has the crown shape, as compared with the straight shape,
It can be seen that entrainment, thin layer uniformity, and image density uniformity are all improved.

As described above, the one-component toner layer is formed on the surface, and the one-component toner is attached to the photoreceptor, which is an image bearing member on which the electrostatic latent image is formed, to make the electrostatic latent image visible. A one-component developing device comprising a developing roller, a toner supply roller arranged in contact with the developing roller to supply one-component toner, and a toner regulating roller that regulates the one-component toner on the developing roller to form a thin layer. One feature of the present invention is that the developing roller is reversely rotated at the time of image development and the developing roller is reversely rotated at the time of development, so that the toner regulation roller stopped at the time of development is rotated in the same direction as the developing roller. In the component developing device, the toner regulating roller has a crown shape whose outer diameter at the central portion is larger than the outer diameters at both ends, so that the contact pressure with the developing roller is made uniform. Uneven wear in the axial direction can be prevented, the life of parts can be extended, and the stability of the toner regulation roller along with the reverse rotation of the developing roller can be improved, and the developing device can be used for an extremely long time. Becomes

Further, by making the contour shape of the toner regulating roller a continuous waveform such as a quadratic curve or an arc curve, it is possible to provide a highly durable developing device without image density unevenness. Further, by using polar rubber for the elastic layer of the toner regulating roller, the adhesive strength of the surface layer can be improved and peeling of the surface layer can be prevented, so that the developing device can be used for an extremely long time.

The developing roller is a rigid body having a metal layer on which a resin layer having a charging polarity opposite to that of the one-component toner is provided, and the toner regulating roller is an elastic body having a releasing layer on the surface. It is possible to prevent abrasion due to the seal at the end of the roller, and it is possible to electrostatically convey the toner by forming the developing roller with a material having a charging property of a polarity opposite to that of the toner. It can be used for an extremely long time.

Further, since the surface shape of the toner regulating roller is kept stable by adhering the metal base material and the rubber roller, it is possible to provide a highly durable developing device without uneven image density.

Next, a one-component developing device of another embodiment will be described. For the developing roller 1, a pipe material made of aluminum was used, and a conductive phenol resin having carbon black dispersed therein was applied to a thickness of 20 μm on a base body obtained by press-fitting and integrating a stainless steel core shaft portion. The resistance value is 10 ³ Ω, and a developing bias is applied to the core shaft 1 a of the developing roller 1 from a constant voltage power source. The toner supply roller 2 has a conductive foam formed around a metal core shaft and has a resistance value of 1
0 ⁶ Ω, and the same potential as the developing bias is applied to the metal core shaft.

The toner regulating roller 4 is a metal core shaft 4a.
Adhesive layer 4b for bonding the core shaft 4a and the elastic layer 4c to the periphery of the
Was formed, and the surface layer 4d made of a resin layer was coated around the elastic layer 4c if necessary. Surface layer 4
As the coating method of d, various known coating methods such as dipping method, spray coating, roll coating, or coating of a molded product formed into a tubular shape can be used.

Next, the structure of the toner regulating roller 4 will be described. In this toner regulation roller 4, the diameter of the core shaft 4a is 10 mm.
After vulcanizing the elastic layer rubber, the roller diameter was adjusted to 14 mm by grinding. Furthermore, in Examples 6 to 11 of the toner regulating roller 4, the crown shape was the same as in Examples 2 to 4 described above. The coating thickness of the adhesive was 5 μm. Further, a bias lower than the developing roller 1 and the toner supply roller 2 by 50 V was applied to the toner regulation roller 4. In Comparative Example 2, a straight elastic layer similar to Comparative Example 1 was used.

[Example 6] Elastic layer: EPDM (ethylene propylene rubber) (JIS
-A hardness 45) Adhesive layer used: Chemlock 238 (manufactured by Road Far East Co.)

[Example 7] Elastic layer: NBR (nitrile-butadiene rubber) (JIS
-A hardness 45) Adhesive layer used: Chemlock 238 (manufactured by Road Far East Co.)

[Example 8] Elastic layer: epichlorohydrin rubber (JIS-A hardness 4
5) Adhesive layer used: Metalloc UB (manufactured by Toyo Kagaku Kenkyusho) is used

[Example 9] Elastic layer: NBR (nitrile-butadiene rubber) (JIS
-A hardness 45) Adhesive layer used: Adhesive made by adding carbon black to Chemlok 238 (manufactured by Road Far East) to make it conductive

[Example 10] Elastic layer: epichlorohydrin rubber (JIS-A hardness 4
5) Adhesive layer used: An adhesive made by adding carbon black to Metalloc UB (manufactured by Toyo Kagaku Kenkyusho) to make it conductive

[Embodiment 11] A fluororesin (fluoroolefin-vinyl ether copolymer) was used as a surface layer on the surface of the elastic layer for the toner regulating roller of Embodiment 10.
Roller coated with a film thickness of 0 μm

[Comparative Example 2] Elastic layer: EPDM (ethylene propylene rubber) (JIS
-A hardness 45) Adhesive layer used: None

Using the toner regulating rollers of Examples 6 to 11 and Comparative Example 2 described above, the toner regulating roller is brought into contact with the developing roller by pressing the core of the toner regulating roller with spring (one side 20).
N). The uniformity of the toner thin layer, the density uniformity of the output image, and the image background stain were evaluated. The results are shown in Table 2 below.

[0058]

[Table 2]

However, in Table 2, the evaluation standard of the thin layer uniformity is that the toner on the surface of the developing roller after toner regulation is visually uniform, and the symbol on the table is the toner on the surface of the developing roller after toner regulation. Part of the toner is uneven, and x indicates that the toner on the surface of the developing roller after the toner is regulated is visually uneven.

The image density uniformity in Table 2 shows the result of evaluation of the density unevenness of the output image with a solid image and a 600 × 600 dpi 2 × 2 dot pattern. The evaluation criteria x indicates that both the solid image and the dot image were uneven, and Δ indicates that only the dot image was uneven.
Shows the case where uniform concentration was obtained in both cases.

Further, in the evaluation criteria of image background stain shown in Table 2, ⊚ indicates that the entire surface of the image is visually free of background stain.
Indicates that there is almost no background stain on the entire image visually, △
Indicates that a part of the image is visually stained, and x indicates that the entire image is visually stained. In Table 2, “after 50K” means after printing 50,000 sheets.

From Table 2, it can be seen that the provision of the adhesive layer as in the toner regulating roller of this embodiment is effective for the uniformity of the thin layer and the uniformity of the image density at the time of durability. The load on the elastic layer of the toner regulating roller is high with respect to the uniformity of the nip between the developing roller and the toner regulating roller, but by providing the adhesive layer, the deviation of the core axis / elastic layer deformation of the toner regulating roller at the time of development. It is considered that the durability is improved because there is no elastic layer deformation deviation when rotating at a predetermined timing during non-development.

By providing the surface layer, the one-component toner does not adhere to the roller surface, and the durability is improved. To improve the releasability of the one-component toner, aiming to improve the water repellency and oil repellency of the surface, by coating the elastic layer with a resin containing fluorine, it is possible to fix the one-component toner during durability. It was confirmed that it is advantageous to obtain an image of high quality.

It is considered that the roller resistance value of the toner regulating roller contributes to the image background stain. The roller resistance value (100 V applied) of the toner regulating roller of each example is as follows: Example 6: 2 × 10 ¹¹ Ω, Example 7: 7 × 10 ⁸ Ω, Example 8: 4 × 10 ⁶ Ω, Example 9 : 4 × 10 ⁸ Ω, Example 10: 2 × 10 ⁶ Ω, Example 11: 4 × 10 ⁶ Ω, Comparative Example 2: 1 × 10 ¹¹ Ω. First, it is considered that the use of NBR or a medium resistance material of epichlorohydrin rubber as the material of the elastic layer has an effect on image background stain when a bias is applied to the toner regulating roller.

Further, although it cannot be said that the roller resistance value alone is an obvious difference with respect to the adhesive layer, the use of a conductive adhesive is more effective than the use of an insulating adhesive against image background stains. I know there is. The reason for this may be that, when an insulating adhesive is used, uneven application of the adhesive layer affects the roller resistance of the toner regulating roller in a minute portion. It is considered that the use of a conductive adhesive is better against the background stain of the image because it is reduced to the effect of only the resistance.

In the one-component developing device, how to make the toner thin layer uniform is important both in the initial stage and during the durability. Providing an adhesive layer between the core shaft of the toner regulating roller and the elastic layer is effective for the thin layer uniformity and the image density uniformity at the time of durability. Although the load on the elastic layer of the toner regulating roller is high with respect to the uniformity of the nip between the developing roller and the toner regulating roller, the core axis / elastic layer deformation deviation of the toner regulating roller at the time of development due to the adhesive layer, non-development Sometimes, there is no displacement of the elastic layer when it rotates at a predetermined timing, which improves durability.

Further, by providing the surface layer on the elastic layer of the toner regulating roller, the releasability for the one-component toner is improved, the toner is not fixed to the roller surface, the durability is improved, and a high quality image is obtained. .

The roller resistance value of the toner regulating roller may contribute to the image background stain. The use of a medium resistance material such as NBR or epichlorohydrin rubber as the material of the elastic layer is effective against image background stain when a bias is applied to the toner regulating roller. Further, as the adhesive provided between the core shaft and the elastic layer, it is more effective to use the conductive adhesive than the insulating adhesive against the image background stain. The reason for this is that when an insulating adhesive is used, uneven application of the adhesive layer may affect the roller resistance of the toner regulating roller in a small portion, but the conductive adhesive layer only affects the resistance of the elastic layer. It is considered that it is better to use the conductive adhesive for the image background stain because the influence of the above is reduced.

As described above, the one-component toner layer is formed on the surface, and the electrostatic latent image is visualized by contacting or adhering to the image bearing member on which the electrostatic latent image is formed and adhering the toner to the surface of the image bearing member. A developing roller, a toner supplying roller which is arranged in contact with the developing roller and supplies toner, and a toner regulating roller which regulates the toner on the developing roller to form a thin layer. In a one-component developing device having a mechanism for rotating at a predetermined timing during non-development, the toner regulating roller is composed of an elastic layer made of rubber or elastomer around the support, and the support and the elastic layer are bonded to each other. The one-component developing device, which is characterized in that it is adhered via an agent, allows the thin toner layer at the contact portion between the developing roller and the toner regulating roller to be fast and highly resistant. Adaptable, it can be more uniformly formed.

A one-component developing device using nitrile-butadiene rubber or epichlorohydrin rubber as the elastic layer material of the toner regulating roller uniformly forms a thin toner layer when a bias is applied to the toner regulating roller for the purpose of improving image quality. Therefore, it is advantageous for image background stain.

Further, by using the one-component developing device in which the adhesive of the toner regulating roller is made conductive, a thin toner layer can be formed more uniformly when a bias is applied to the toner regulating roller for the purpose of improving the image quality, which causes image background stains. It will be more advantageous than that.

Further, the one-component developing device in which the resin layer is formed on the outer circumference of the elastic layer of the toner regulating roller has a function of preventing the toner from sticking to the toner regulating roller and obtaining a high quality image for a long period of time.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the case of a quadratic curve has been described as an example of the crown shape, but if the curve is a smooth curve that is convex outward with the maximum outer diameter at the center in the axial direction,
Similar effects can be obtained with curves other than the next curve.
That is, various modifications can be made without departing from the gist of the present invention.

[0074]

As described above, according to the first aspect of the present invention, since the contact pressure with the developing roller is made uniform, uneven wear in the axial direction of the toner regulating roller is prevented, and the life of parts is extended. In addition, it is possible to improve the rotation stability of the toner regulating roller against the reverse rotation of the developing roller.
The developing device can be used for an extremely long time. Further, according to the invention of claim 2, it is possible to provide a highly durable developing device without image density unevenness. Further, according to the invention of claim 3, since the adhesive strength of the surface layer can be improved and the surface layer can be prevented from peeling off, the developing device can be used for an extremely long time.

According to the invention of claim 4, the thin toner layer in the contact portion between the developing roller and the toner regulating roller can be formed at high speed and with high durability and can be formed more uniformly.

Further, according to the invention of claim 5, a thin toner layer can be uniformly formed when a bias is applied to the toner regulating roller for improving the image quality, which is advantageous for image background stain.

Further, according to the invention of claim 6, the toner thin layer can be formed more uniformly when the bias is applied to the toner regulating roller for improving the image quality, which is more advantageous for the image background stain. .

According to the seventh aspect of the invention, it is possible to prevent the toner from sticking to the toner regulating roller and obtain a high quality image for a long period of time.

According to the invention of claim 8, claim 1
It is possible to obtain the image forming apparatus including the developing device having the effect described in any one of 1 to 7.

[Brief description of drawings]

FIG. 1 is a schematic view showing a one-component developing device according to one embodiment and another embodiment of the present invention.

FIG. 2 is a cross-sectional view of a toner regulating roller provided in the one-component developing device in FIG. 1, where (A) is a toner regulating roller having no adhesive layer between a core shaft and an elastic layer, and (B) is a core. This is the case of a toner regulating roller having an adhesive layer between the shaft and the elastic layer.

FIG. 3 is an explanatory diagram of a contour line shape of an elastic layer of a toner regulating roller provided in the one-component developing device in FIG.

FIG. 4 is a diagram showing an example of a crown shape.

[Explanation of symbols]

1 developing roller 2 Toner supply roller 3 Toner transport member 4 Toner regulation roller 4a core shaft 4b adhesive layer 4c elastic layer 4d surface layer 6 spring 7 One-component toner

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takayuki Yoshii             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Taisuke Tokuwaki             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F term (reference) 2H077 AC04 AD02 AD06 AD14 AD17                       BA03 DB21 EA15 EA16 FA12                       FA21 FA25 GA03                 3J103 AA02 AA13 AA32 AA51 BA32                       BA41 EA07 FA10 FA12 FA18                       GA02 GA57 GA58 GA60 HA03                       HA12 HA20 HA53

Claims (8)

[Claims] 1. A developing roller which is in contact with or close to an image bearing member on which an electrostatic latent image is formed, and which is rotated at the time of image formation to visualize the electrostatic latent image by adhering one-component toner. A toner supply roller for supplying the one-component toner to the developing roller, and a toner regulating roller for regulating the amount of the one-component toner adhering to the developing roller to form a thin toner layer on the developing roller, In a one-component developing device in which the developing roller is rotated in the direction opposite to the rotation direction during image formation during non-developing, at least a portion of the toner regulating roller that forms the thin toner layer has both axial end portions. The one-component developing device is characterized in that the outer diameter at the axial center is larger than the outer diameter of the crown shape. 2. The contour shape of at least a portion of the toner regulating roller where the thin toner layer is formed is a part of a quadratic curve in a cross section along the longitudinal direction. The one-component developing device described. 3. The polar rubber is used for the elastic layer provided on the toner regulating roller.
The one-component developing device described in 1. 4. The metal base material provided on the toner regulating roller and an elastic layer covering the circumferential direction of the metal base material are adhered by an adhesive agent. Component developing device. 5. The one-component developing device according to claim 4, wherein nitrile-butadiene rubber or epichlorohydrin rubber is used as an elastic layer material of the toner regulating roller. 6. The one-component developing device according to claim 4, wherein the adhesive is a conductive adhesive. 7. The one-component developing device according to claim 3, wherein a resin layer is formed on the outer periphery of the elastic layer. 8. An image forming apparatus comprising the one-component developing device according to claim 1.