JPH11161009A - Developer regulating member and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently regulate a nonmagnetic one-component developer on a developer carrier by preventing the warpage of a developer regulating member in a direction coincident with the longitudinal direction of the developer carrier of a developing device, to uniformly abut the regulating member on the developer carrier. SOLUTION: An elastic blade 19 is provided with a thermoplastic elastomer surface-like elastic layer 16, in the longitudinal direction of a developing sleeve, on the top end part side on one surface of a rectangular sheet metal 17 having spring elasticity. A thermoplastic elastomer bar-like warpage preventing member 18 having a quadrangular section is provided in the longitudinal direction, so that a projection surface is not overlapped with the elastic layer 16, on the other surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device of an image forming apparatus such as an electrophotographic copying machine and an electrophotographic printer, and more particularly to a developer regulating member of a developing device using a one-component developer for development. .

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, an electrostatic latent image formed on an image carrier is developed by a developing device using a developer.

As one of such developing devices, various dry one-component developing devices using a one-component developer toner as a developer have been proposed and put into practical use. However, all the developing devices have a problem that it is difficult to form a thin layer of toner on a developing sleeve which is a developer carrying member.

[0004] However, at present, improvements in image resolution, sharpness, and the like are required, and development of a method of forming a thin layer of toner and a developing device that realizes the method is indispensable. A strategy has been 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, and toner is passed between a contact portion between the elastic blade and the developing sleeve. In some cases, a thin layer of toner is formed on the developing sleeve, and a sufficient frictional charge (tribo) is imparted to the toner by friction at the contact portion.

When a non-magnetic toner is used as the above toner, a supply member for supplying the toner onto the developing sleeve is separately required. This is because 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, but in the case of a non-magnetic toner, the supply of the toner by the magnetic force cannot be used.

In Japanese Patent Application Laid-Open No. 58-116559, a developing sleeve in which a non-magnetic toner of a one-component developer is stored is brought into contact with the developing sleeve at a position upstream of the elastic blade in the rotation direction of the developing sleeve. An elastic roller having a fur brush structure is installed, and by rotating the elastic roller, toner remaining without being consumed in development on the developing sleeve is peeled off, and new toner is supplied onto the developing sleeve. .

[0008] By adopting the above configuration, a thin layer of non-magnetic toner can be favorably formed on the developing sleeve.
The electrostatic latent image on the photosensitive drum serving as the image carrier can be favorably developed.

[0009]

However, in order to further improve image quality and save energy, it has been necessary to use a toner having a small particle diameter and a low melting point in order to respond to the demand. When the developing operation was repeated many times, the following problems occurred.

(1) When a thin metal plate such as SUS or phosphor bronze is used as the elastic blade, the contact of the elastic blade with the developing sleeve tends to be uneven in the longitudinal direction because the hardness of the elastic blade is too high. Tends to cause unevenness in the toner coating. Also, since the hardness is too high, an excessive force is locally applied to the toner, and the releasability of the surface is poor, so that when the developing operation is repeated, the toner melts on the contact surface of the elastic blade with the developing sleeve. To wear. As a result, uneven coating and streaks of the toner on the developing sleeve occur, and an image defect occurs.

(2) A conventional plate made of urethane rubber, silicone rubber, or the like is used alone as an elastic blade, or these rubber plates are bonded and formed on a thin metal plate in order to obtain temporal stability. When an elastic blade is used, (1)
However, the frictional charging ability of the toner is insufficient, and the charge amount of the toner becomes insufficient. As a result, fogging is caused as a problem on the image, and in a severe case, the toner scatters from the developing sleeve, and the inside of the image forming apparatus is stained.

Therefore, it is necessary to use a material having a high triboelectric charging capability for the elastic blade itself. Materials with high donability are selected.

Of these, particularly for negative polarity toners,
Various proposals have been made to use a material containing a charge controlling agent having a high electron-donating property in a base material such as silicone rubber or urethane rubber, but they are still insufficient in terms of imparting triboelectric charge to toner. In particular, it was not possible to prevent the generation of fog images in a high humidity environment.

In order to prevent the occurrence of the fog image, a material having a higher electron-donating property, for example, a polyamide resin such as nylon is preferable. However, since this polyamide resin does not have elasticity, it is used alone in a plate shape. It is impossible to use. Therefore, when a polyamide resin is used for the elastic blade, some measures are taken such as coating the resin on a thin metal plate as a support layer for regulating the pressure or bonding the resin plate.

By doing so, the occurrence of fogging at the early stage of the developing operation could be prevented. However, similar to the case where the thin metal plate alone was used as the elastic blade, the toner on the developing sleeve at the early stage of the developing operation was eventually formed. This caused uneven coating and fusion of the toner to the elastic blade surface when the developing operation was repeated. This is because an excessive force is applied to the toner when passing through the elastic blade because the hardness of the polyamide resin is too high.

For the purpose of reducing the hardness of the elastic blade, for example, a structure in which a thermoplastic elastomer is adhered as an elastic layer on a thin metal plate and a polyamide resin is thinly coated as a charge-imparting layer on the surface of the elastic blade. On the other hand, it has been proposed to form an elastic blade with a polyamide elastomer containing a polyamide component having good triboelectric charging ability and a polyether component having elasticity.

However, as shown in FIG. 6, the elastic blade 19 is made of a thin metal plate 17, for example, phosphor bronze (linear expansion coefficient: 1.8 × 10 ⁻⁶ / ° C.), and an elastic layer 16 of a polyamide-containing elastomer, for example, diamide. PAE E4
0 (manufactured by Daicel Huls Co., Ltd .; linear expansion coefficient: 1.5 × 10
^-4 / ° C), when a polyamide-containing elastomer is injected into a blade mold equipped with a thin metal plate coated with a primer, and an elastic blade is integrally molded, the linear expansion coefficients of the two are greatly different. The shrinkage of the elastomer contained during cooling and solidification is much greater than that of a thin metal plate, and as shown in FIG. 6 and FIG. 7 in the direction of arrow A, the longitudinal direction of the elastic blade 19 (the direction along the longitudinal direction of the developing sleeve). ) Causes large warpage.

Further, it is conceivable that the polyamide elastomer layer is adhered to a thin metal plate by a double-sided tape or the like. In this case, although the warpage does not occur as in the injection molding,
Heat distortion temperature of polyamide-containing elastomer is 100 ° C or less (under a load of 4.6 kg / cm ² , ASTM D648)
Because of its poor heat resistance, if it is left at high temperature and then returned to room temperature, it will shrink and deform, which will appear as warpage of the elastic blade, and the contact with the developing sleeve will be uneven in the longitudinal direction Therefore, a fogging phenomenon occurs near both ends of the elastic blade, and in a severe case, there is a problem that the toner scatters from the developing sleeve and contaminates the inside of the image forming apparatus.

Accordingly, it is an object of the present invention to prevent a warp in a direction along a longitudinal direction of a developer carrying member, to uniformly contact the developer carrying member, and to perform non-magnetic one-component development on the developer carrying member. A developer regulating member capable of satisfactorily regulating the developer, and a developer regulating member provided with the developer regulating member. An object of the present invention is to provide a developing device capable of obtaining a high-quality image free from image defects such as unevenness, unevenness, and streaks.

[0020]

The above object is achieved by a developer regulating member and a developing device according to the present invention. In summary, the present invention provides a non-magnetic one-component developer that abuts the surface of a developer carrier that carries a non-magnetic one-component developer and conveys the developer to a development area facing the image carrier along the longitudinal direction thereof. In a developer regulating member that regulates a layer thickness of the developer, the developer regulating member is provided on one surface of a thin metal plate having spring elasticity along a longitudinal direction of the developer carrier, and a surface of the developer carrier. An elastic layer of a thermoplastic elastomer that is provided in the longitudinal direction, and a warp preventing member is provided in the longitudinal direction at a position where the elastic layer and the projection surface do not overlap on the other surface. is there.

According to one aspect of the present invention, the warpage preventing member is a bar and is made of a resin, and the resin is a thermoplastic elastomer. The elastic layer and the warpage preventing member can be provided on the metal sheet by injection molding. The elastic layer and the warpage prevention member can be provided on the metal sheet by an adhesive means. The cross-sectional shape of the warp member is rectangular or triangular.

Further, the present invention provides a developer carrier which carries a non-magnetic one-component developer and conveys the developer to a development area opposed to the image carrier, and has a surface on the developer carrier along a longitudinal direction thereof. A developing device having a developer regulating member that abuts and regulates a layer thickness of the carried developer, wherein the developer regulating member is any one of the developer regulating members. Developing device.

[0023]

Embodiments of the present invention will be described below in more detail with reference to the drawings.

Embodiment 1 FIG. 1 is a sectional view showing an embodiment of the developing device of the present invention.

As shown in FIG. 1, the developing device 4 is provided with a developing container 14 containing a non-magnetic toner 8 of a non-magnetic one-component developer as a developer, and the developing container 14 faces the photosensitive drum (image carrier) 1. A developing sleeve 5 as a developer carrier is provided at an opening of the developing container 14 with a predetermined gap from the photosensitive drum 1. An elastic roller 6 in contact with the developing sleeve 5 is provided at a position of the developing sleeve 5 opposite to the photosensitive drum 1 in the developing container 14, and a toner stirring and conveying member 23 is further provided behind the elastic roller 6. Agitation transport member 23
Rotates in the direction of arrow C to supply the non-magnetic toner 8 contained in the developing container 14 to the elastic roller 6, and the elastic roller 6 rotates in the direction of arrow D, and the developing sleeve 5 rotates in the direction of arrow B. The toner remaining after development is peeled off from the surface, and new toner 8 supplied by the stirring and conveying member 23 is removed.
Is carried on the surface of the developing sleeve 5.

The developing sleeve 5 rotates in the direction of arrow B,
The carried toner 8 is conveyed to a developing area facing the photosensitive drum 1. At a position above the developing sleeve 5 of the developing container 14, an elastic blade 19 is attached as a developer regulating member by a holding metal plate 15.
Is in contact with the surface of the developing sleeve 5 near the elastic roller 6 in the counter direction. The elastic blade 19 regulates the layer thickness of the toner 8 on the developing sleeve 5 while conveying the toner to the developing area, imparts triboelectric charge to the toner, and forms a thin toner layer.

The toner 8 formed in a thin layer and conveyed to the developing area develops the electrostatic latent image formed on the surface of the photosensitive drum 1 rotating in the direction of arrow A, and is visualized as a toner image. During this development, a developing bias is applied between the developing sleeve 5 and the photosensitive drum 1 by the bias power supply 20 to promote development. The undeveloped toner remaining on the developing sleeve 5 is returned into the developing container 14 with the rotation of the developing sleeve 5, and is peeled off from the surface of the developing sleeve 5 by the elastic roller 6.

At a position below the opening of the developing container 14, a lower seal member 24 which is in contact with the lower surface of the developing sleeve 5 is provided to prevent toner from leaking from below the opening of the developing container 14. At the positions on both ends of the developing sleeve 5 of the developing container 14, end sealing members 22 made of sponge are installed on the opposite side to the opening to prevent leakage of toner from both ends of the developing sleeve 5. I have.

According to the present invention, the elastic blade 19 is, as shown in FIG.
7 is provided in the longitudinal direction (the developing sleeve 5).
Along the same direction as the longitudinal direction of the thermoplastic elastomer) so as to extend over the distal end surface of the thermoplastic elastomer, and to prevent the elastic layer 16 of the thermoplastic elastomer from overlapping the projection surface on the other surface. A bar-shaped warpage preventing member 18 having a rectangular cross section made of a thermoplastic elastomer is provided along the longitudinal direction.

The other end portion 17a of the thin metal plate 17 is a portion for attaching the elastic blade 19 to the developing container 14 by the holding metal plate 15. The elastic blade 19 is used for the container 1.
4, the elastic layer 16 is attached to the elastic layer 16 as shown in FIG.
Is in contact with the surface of the developing sleeve 5. Developing sleeve 5
As shown in FIG. 3, the end seal members 22 at both ends of
The warp preventing member 1 is pressed by both ends of the elastic blade 19.
8 is pressed against the metal sheet 17.

In this embodiment, specifically, a 0.1 mm-thick phosphor bronze plate was used as the thin metal plate 17 of the elastic blade 19, and a polyamide elastomer was used as the thermoplastic elastomer. The thin metal plate 17 was mounted on a metal mold, and a polyamide elastomer was injected into the metal thin plate 17 to form the elastic layer 16 and the warp preventing member 18 on the thin metal plate 17, whereby an elastic blade 19 was integrally formed.

The elastic blade 19 of the present invention is constructed as described above, and has the elastic layer 16 provided in the longitudinal direction.
Since the warpage preventing member 18 is provided in the longitudinal direction on the surface opposite to 7, the elastic blade 19 is prevented from warping in the longitudinal direction.

Since the elastic layer 16 and the warpage preventing member 18 of the same resin material are formed on the opposite surfaces of the thin metal plate 17 by injection molding, the material of the thin metal plate 17 and the resin material of the elastic layer 16 and the like are formed. Even if the coefficient of linear thermal expansion is significantly different,
In the process of solidifying the resin material after the injection, warping in the longitudinal direction between the opposite surfaces of the thin metal plate 17 is canceled out, and the elastic blade 19 is prevented from warping in the longitudinal direction.

Further, since the elastic layer 16 and the warp preventing member 18 are arranged so that the projection surfaces do not overlap, the surface of the thin metal plate 17 on the side opposite to the elastic layer 16 by the mold member is used. The opposite surfaces can be received and supported by the respective mold members, so that even if a molding pressure is applied to the metal sheet 17, the metal sheet 17 is not deformed.

The amount of end warpage of the elastic blade 19, that is, the amount of warp in the longitudinal direction of the thin metal plate 17, is preferably set to 0.3 mm or less in view of the regulation performance of the non-magnetic toner. In the present invention, the amount of end warpage can vary depending on the linear expansion coefficient and the shape of the warpage prevention member 18, but is small because the warpage prevention member 21 is provided, and is easily 0.3 mm.
It can be:

In this embodiment, the mounting portion 17a of the elastic blade 19, which is defined by the thin metal plate 17, is brought into contact with the platen, and the end (corner) of the thin metal plate 17 opposite to the mounting portion 17a is formed. The amount of floating, that is, the amount of end warpage of the elastic blade 19 was measured. Further, the elastic blade 19 was mounted on the developing device 4 of FIG. 1 and used for development to form an image, and the occurrence of unevenness of the image was investigated. Table 1 shows the results.

For comparison, for the elastic blade provided with only the elastic layer 16 without the warp preventing member 18 in the above-mentioned thin metal plate 17, the amount of end warpage was measured in the same manner. An image was formed by using the same, and the occurrence state of image unevenness and the like was investigated. The results are also shown in Table 1.

[0038]

[Table 1]

As shown in Table 1, in the present invention, since the warp preventing member 18 is provided on the elastic blade 19, the end warp amount is 0.1 mm, which is much smaller than that of the comparative example. As a result, the thin layer of the toner was stably formed by properly controlling the toner on No. 5, and no image defects such as fog, unevenness, and streaks occurred.

Another embodiment of the present invention will be described. In the present embodiment, as shown in FIG. 4, the warpage preventing member 18 of the elastic blade 19 has a triangular cross section. Also, the elastic layer 1
6 and the warpage preventing member 18 are individually formed of a polyamide elastomer, and are bonded to the opposite surfaces of the thin metal plate 17 with a double-sided tape 26. Others are the same as the previous embodiment.

Also in this embodiment, since the warpage preventing member 18 is provided in the longitudinal direction on the surface opposite to the metal sheet 17 provided with the elastic layer 16 in the longitudinal direction, the elastic blade 19 warps in the longitudinal direction. Is prevented.

Further, since the elastic layer 16 and the warp preventing member 18 are arranged so that the projection surfaces do not overlap, when the elastic layer 16 and the warp preventing member 17 are adhered to the metal thin plate 17 by the double-sided tape 26, they are pressed. Elastic layer 16 by member
And the pressing of the warpage prevention member 17 can be supported by disposing a support member on the opposite surfaces of the thin metal plate 17, respectively.
Therefore, even if pressure is applied to the metal sheet 17, the metal sheet 1
No deformation occurs in 7.

In the previous embodiment, since the cross-sectional shape of the warp preventing member 18 is square, when the sponge end seal members 22 at both ends of the developing sleeve 5 are pressed against the ends of the elastic blade 19, as shown in FIG. As shown in (2), the seal member 22 pressed against the thin metal plate 17 has a gap 25 between the thin metal plate 17 on both sides of the base of the warp preventing member 18,
Leakage of toner from the end of the elastic blade 19 through the gap 25 is likely to occur. On the other hand, according to the warp prevention member 18 of the present embodiment, since the cross section is triangular, the seal member 22 pressed against the metal thin plate 17 is easily brought into close contact with the metal thin plate 17 on both sides of the base of the warp prevention member 18. No gap is generated between them, and there is no toner leakage from the end of the elastic blade 19.

In this embodiment, the elastic blade 19 provided with the elastic layer 16 and the warpage preventing member 18 by bonding with a double-sided tape is left at a high temperature of 45 ° C. for 24 hours.
The amount of end warpage of the elastic blade 19 was measured at room temperature, and the warpage due to environmental temperature changes was examined. The measuring method was the same as in the previous example. The elastic blade 19 is mounted on the developing device 4 of FIG. 1 and is used for development to form an image.
The occurrence status of image unevenness and the like was investigated. Table 2 shows the results.

For comparison, for an elastic blade provided with only the elastic layer 16 by bonding without having the warp preventing member 18 on the metal thin plate 17, the amount of end warpage was measured in the same manner. 4 was used to form an image, and the occurrence of image unevenness and the like was investigated. The results are also shown in Table 2.

[0046]

[Table 2]

As shown in Table 2, in the present invention, since the warp preventing member 18 is provided on the elastic blade 19, the end warp amount is 0.12 mm, which is much smaller than that of the comparative example. 5, the toner on the top 5 can be well regulated to form a thin layer of toner stably, and no image defects such as fog, unevenness, and streaks have occurred. Also, since the cross-section of the warp preventing member 18 is triangular, it is not shown in Table 2,
There was no toner leakage from the end of the elastic blade 19.

In each of the above embodiments, a polyamide elastomer was used as the thermoplastic elastomer.
Styrene-based, polyurethane-based, and PVC-based thermoplastic elastomers can also be used. In particular, a thermoplastic elastomer having a large linear expansion coefficient, preferably 1.0 × 10 ⁻⁴ / ° C. or more is suitable.

For the warp preventing member 18, a resin such as a thermoplastic polymer can be used instead of a thermoplastic elastomer.

[0050]

As described above, according to the present invention,
The developer regulating member of the developing device is disposed on one surface of a thin metal plate having spring elasticity along the longitudinal direction of the developer carrying member, and an elastic layer of a thermoplastic elastomer contacting the surface of the developer carrying member in the longitudinal direction. The warp preventing member is provided in the longitudinal direction at a position where the elastic layer and the projection surface do not overlap with the other surface, so that warping in the direction along the longitudinal direction of the developer carrier is prevented, and Warpage can also be prevented, and the developer regulating member abuts uniformly on the surface of the developer carrier in the longitudinal direction thereof, thereby favorably regulating the non-magnetic one-component developer carried on the developer carrier. It can be subjected to development. As a result, a high-quality image free from image defects such as fog, unevenness, and streaks can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a developing device of the present invention.

FIG. 2 is a perspective view showing an elastic blade installed in the developing device of FIG.

3 is a cross-sectional view showing a state where an end seal member of a developing sleeve is pressed against a longitudinal end of the elastic blade of FIG. 2;

FIG. 4 is a perspective view showing an elastic blade according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a state where an end seal member of a developing sleeve is pressed against a longitudinal end of the elastic blade of FIG. 4;

FIG. 6 is a perspective view showing a state in which a conventional elastic blade is warped.

7 is a view as viewed in the direction of the arrow A in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum 4 Developing device 5 Developing sleeve 8 Non-magnetic toner 16 Elastic layer 17 Thin metal plate 17a Attachment part 18 Warpage prevention member 19 Elastic blade 22 End seal member

Claims (8)

[Claims] An image forming apparatus according to claim 1, wherein said developing agent carries a non-magnetic one-component developer and is conveyed to a developing area facing said image carrier. In the developer regulating member that regulates the layer thickness, the developer regulating member abuts on one surface of a thin metal plate having spring elasticity along the longitudinal direction of the developer carrier, and contacts the surface of the developer carrier. A developer regulating member, wherein an elastic layer of a thermoplastic elastomer is provided in a longitudinal direction, and a warp preventing member is provided in a longitudinal direction at a position where the elastic layer and the projection surface do not overlap on the other surface. 2. The warp preventing member is a bar.
Developer regulating member. 3. The developer regulating member according to claim 1, wherein the warpage preventing member is made of a resin. 4. The developer regulating member according to claim 3, wherein said resin is a thermoplastic elastomer. 5. The developer regulating member according to claim 3, wherein the elastic layer and the warpage preventing member are provided on the metal sheet by injection molding. 6. The developer regulating member according to claim 3, wherein the elastic layer and the warpage preventing member are provided on the thin metal plate by an adhesive means. 7. The developer regulating member according to claim 2, wherein the cross-sectional shape of the warping member is rectangular or triangular. 8. A developer carrier that carries a non-magnetic one-component developer and conveys the developer to a development area facing the image carrier, and abuts on the surface of the developer carrier along the longitudinal direction thereof, In a developing device having a developer regulating member for regulating a layer thickness of the carried developer, the developer regulating member is the developer regulating member according to any one of claims 1 to 7. A developing device.