JPH11143216A - Developing device, developing cartridge and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent toner from being leaked or scattered by electrically imparting charge to non-magnetic toner which is incompletely electrified. SOLUTION: This developing device is made a developing cartridge which can be freely attached to/detached from an image forming device main body. A charge imparting roller 102 following and rotating while press-contacting with both ends of the developing sleeve 5 of the developing device is installed on the downstream side of an elastic blade 7 in the rotating direction of the sleeve 5, and voltage having the same polarity as the electrification polarity of the toner is impressed on the roller 102 from a power source 106 so as to electrically impart the charge to the incompletely electrified toner on both ends of the sleeve 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, a developing cartridge, and an image forming apparatus used in an image forming apparatus of an electrophotographic system or the like.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a latent image formed on an image bearing member is developed by a developing device using a developer and visualized as a toner image.

In such a developing apparatus using a non-magnetic toner (non-magnetic one-component developer) as a developer, an elastic blade is brought into contact with a developing sleeve, and the toner carried on the developing sleeve is brought into contact with the elastic blade. By forming a toner layer on the developing sleeve by passing between the
Sufficient triboelectric charge (tribo) is imparted to the toner by friction at the contact portion.

[0004] Unlike a magnetic toner which can magnetically hold the toner by the action of a magnetic field on the surface of the developing sleeve, the non-magnetic toner cannot use such a magnetic attraction force, so Except for the charged one, the toner is not held on the developing sleeve, so that the toner easily leaks or scatters from the developing container, and there is a problem that the inside of the image forming apparatus is liable to be contaminated with the toner.

Therefore, in order to prevent leakage of the non-magnetic toner, a flexible seal member which is lightly contacted with the developing sleeve is provided in a toner collecting portion below the opening where the developing sleeve of the developing container is disposed, for example. The leakage of toner from the lower part is prevented. Further, seal members are separately provided near both ends in the longitudinal direction of the developing sleeve to prevent leakage of toner from both ends in the longitudinal direction of the elastic blade and between the developing container and the developing sleeve. Furthermore, in order to eliminate the gap between these members, the contact portions of the elastic blade at both ends in the longitudinal direction, which are in contact with the developing sleeve, are pressed from the back surface by the end seal member.

[0006]

However, when the pressure of the elastic blade end against the developing sleeve is increased, the elastic blade is deformed. On the other hand, when the pressure is reduced to prevent the elastic blade, the elastic blade end and the end seal are reduced. A gap is easily formed between the member and the member.

As described above, depending on the pressure contact state of the end seal member, the elastic blade is deformed and the contact with the surface of the developing sleeve becomes insufficient, or a gap is formed in the end seal portion. If the toner is not sufficiently triboelectrically charged, there is a problem that the toner is not retained on the developing sleeve and the toner leaks or scatters.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a developing device capable of preventing the leakage and scattering of toner by electrically applying a charge to a non-magnetic toner having an insufficient charge. To provide a developing cartridge and an image forming apparatus.

[0009]

The above object is achieved by a developing device, a developing cartridge and an image forming apparatus according to the present invention. In summary, the present invention is a developer carrier that carries a developer and transports the developer to a development area facing the image carrier,
A developing device having a developer regulating member for regulating the amount of developer carried on the developer carrying member, the developer regulating member being in contact with the developer carrying member; On the downstream side of the contact portion, a conductive member that is driven to rotate by being pressed against both ends of the developer carrier is installed, and a bias having the same polarity as the charged polarity of the developer is applied to each of the conductive members. A developing device is characterized in that a charge is applied to a developer passing through a pressure contact portion of each conductive member.

According to the present invention, each of the conductive members is in pressure contact with the developer carrying member over both the developer carrying region of the developer carrying member and the non-developer carrying region outside the developer carrying region. Each of the conductive members is formed of a conductive metal roller. The developer is a non-magnetic one-component developer.

According to the present invention, there is provided a developing cartridge comprising a developing device detachable from the image forming apparatus main body, wherein the developing device comprises the above-mentioned developing device. Further, the present invention is an image forming apparatus provided with a developing device, wherein the developing device comprises the above-mentioned developing device.

[0012]

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

FIG. 1 is a sectional view showing an embodiment of the image forming apparatus of the present invention. In FIG. 1, the image forming apparatus has a photosensitive drum 1 as an image carrier.
Rotates in the direction of arrow A, and its surface is uniformly charged by the charging roller 2 of the charging device, and remains. Next, the surface of the photosensitive drum 1 is irradiated with the laser beam 3a from the exposure means 3, and an electrostatic latent image is formed on the surface.

The electrostatic latent image is developed by a developing device 4 disposed close to the photosensitive drum 1, and is visualized as a toner image. In this embodiment, the developing device 4
Is a developing cartridge which is detachably mounted to the image forming apparatus main body.

The toner image formed on the photosensitive drum 1 is
The paper 13 on which the toner image has been transferred onto the paper 13 serving as the recording medium supplied to the photosensitive drum 1 by the action of the transfer roller 9 is transferred to the fixing device 12 and subjected to a fixing process.
The sheet is discharged outside the image forming apparatus main body.

The photosensitive drum 1 removes untransferred toner remaining on the surface thereof without being transferred onto the cleaning blade 10.
Is used again for image formation. The scraped toner is stored in a toner collection container 11 to which a cleaning blade 10 is attached.

As shown in FIG. 2, the developing device 4 includes a developing container 14 containing a non-magnetic toner 8 as a non-magnetic one-component developer.
And a developing sleeve 5 as a developer carrier is disposed in an opening of the developing container 14 facing the photosensitive drum 1. The opening of the developing container 14 extends along the longitudinal direction of the photosensitive drum 1, and the developing sleeve 5 protrudes into the container 14 at approximately a right half of the drawing and into a substantially half of the left at the opening. It is laterally exposed and exposed outside the container 8. The surface of the developing sleeve 5 exposed outside the developing container 8 is opposed to the photosensitive drum 1 located on the left side of the developing device 4 with a small gap.

The developing sleeve 5 is driven to rotate in the direction of arrow B. The surface of the developing sleeve 5 increases friction with the toner 8,
In addition, in order to enhance the transportability of the toner 8, the toner 8 has appropriate irregularities. In this embodiment, the developing sleeve 5 has a diameter of 16 m.
m, an aluminum cylinder having a surface roughness Rz of about 3 μm was used by subjecting the surface of the aluminum cylinder to a regular blast treatment with glass beads (# 600). Also, the developing sleeve 5
Is 300 μm between the photosensitive drum 1 and the developing sleeve 5.
Is 80 mm / sec, which is slightly faster than the peripheral speed of the photosensitive drum 1 of 50 mm / sec.

At the opening of the developing container 14, end sealing members 19 are provided at both ends in the longitudinal direction of the developing sleeve 5.
Has stopped leaking.

An elastic blade 7 supported by a sheet metal 15 is provided at a portion of the container 14 above the developing sleeve 5 and is in contact with the developing sleeve 5. The elastic blade 7 is formed of a rubber material such as urethane rubber or silicone rubber, or is made of a thin metal plate having spring elasticity such as SUS or phosphor bronze, and adheres a rubber material to a contact side with the developing sleeve 5. And the like. The contact direction of the elastic blade 7 is preferably a so-called counter direction in which the leading end is located upstream of the contact portion in the rotation direction of the developing sleeve 5.

In this embodiment, the elastic blade 7 has a thickness of 1.
It was made of a 0 mm plate-like urethane rubber, which was adhered and supported on a supporting metal plate. The contact pressure of the elastic blade 7 with the developing sleeve 5 was set to 30 g / cm in linear pressure. The linear pressure is measured by inserting three metal thin plates having a known coefficient of friction into the abutting portion between the developing sleeve 5 and the elastic blade 7 and pulling out one central metal thin plate with a spring meter. Was determined from the load indicated.

An elastic roller 6 is provided upstream of the contact portion of the elastic blade 7 in the rotation direction of the developing sleeve 5.
The elastic roller 6 is in contact with the developing sleeve 5 and is rotatably supported. The elastic roller 6 has a foamed skeleton-like sponge structure or a fur brush structure in which fibers such as rayon and nylon are planted on a cored bar. This is preferable from the viewpoint of supplying new toner 8.

In this embodiment, the elastic roller 7 has a structure in which a polyurethane foam is provided on a metal core, and the elastic roller 7 has a diameter of 12 mm.
mm. It is preferable that the elastic roller 6 has a relative speed with the developing sleeve 5 at a contact portion with the developing sleeve 5, and a contact width of 1 to 8 mm is effective. In this embodiment, the contact width is set to 3 mm, and the peripheral speed of the elastic roller 6 is set to 50 mm / sec in the D direction during the developing operation (the relative speed to the developing sleeve 130 is 130 mm / sec). It was driven to rotate by means.

FIG. 3 shows the developing device 4 as viewed from the direction of the photosensitive drum 1. In FIG. 3, the developing sleeve 5 is omitted for convenience of explanation.

As shown in FIG. 3, the elastic blade 7 is moved from the contact portion of the elastic blade 7 with the developing sleeve 5 shown by hatching.
Is formed so that the distance from the normal developing region to the both ends of the elastic blade 7 is continuously reduced from the normal developing region.
It is configured to be in a position corresponding to the contact portion.

As is conventionally known, the thickness of the toner layer formed on the developing sleeve 5 is affected by the distance from the point of the contact portion on the upstream side in the rotation direction of the developing sleeve 5 to the tip thereof, The longer the distance, the thicker the toner layer on the developing sleeve 5, and the shorter the distance, the thinner the toner layer. In the present embodiment, as described above, the distance to the front end in the area abutting on the peripheral surface of the developing sleeve corresponding to the non-contact portion of the elastic roller 6 is smaller than the distance to the front end in the normal developing area. By reducing the length, the regulating force on the toner in the contact area is increased.

In this embodiment, as the non-magnetic toner 8 of the non-magnetic one-component developer, a toner having excellent transferability and high lubricity, that is, a toner having a spherical shape and a smooth surface is used. Specifically, the shape factor SF-1 is 1
The toner is 100 to 180, and the SF-2 is 100 to 140. The high lubricity of the toner is that when the toner remaining on the photosensitive drum 1 without being transferred is cleaned by a cleaning means such as a blade or a fur brush, the residual toner is transferred to the photosensitive drum 1 due to the high lubricity. It has the advantage that the abrasion of the drum 1 is small.

The shape factors SF-1 and SF-2 are sampled at random from 100 toner particle images using a Fe-SEM (S-800) manufactured by Hitachi, Ltd., and the image information is collected via an interface. Image analyzer (L
uxex3), analyzed and defined as a value calculated by the following equation.

SF-1 = ｛(MXLNG) ² / ARE
A｝ × (π / 4) × 100 SF-2 = {(PERI) ² / AREA} × (π / 4)
× 100 where AREA: toner projection area, MXLNG: absolute maximum length, PERI: circumference

The shape factor SF-1 of the toner indicates the degree of spherical shape of the toner. As the shape factor SF-1 increases from 100, the shape gradually becomes irregular from a spherical shape. The shape factor SF-2 of the toner indicates the degree of unevenness of the toner. As the value increases from 100, the unevenness on the surface of the toner becomes remarkable.

The method for producing the toner may be any method as long as it falls within the range of the shape factor described above. In addition to the so-called pulverization method, JP-A-36-10231 and JP-A-59-5
No. 3856, a method of directly producing a toner using a suspension polymerization method, and a method of directly producing a toner using an aqueous organic solvent which is soluble in a monomer and insoluble in a polymer obtained. It can be produced by a polymerization method or an emulsion polymerization method typified by soap-free, which directly polymerizes in the presence of a water-soluble polar polymerization initiator to form a toner.

In this embodiment, the shape factor SF-1 of the toner
The suspension polymerization method under normal pressure or pressure can easily control the SF to 100 to 180 and the SF-2 to 100 to 140, and can relatively easily obtain a fine particle toner having a sharp particle size distribution and a particle size of 4 to 8 µm. Styrene and n-butyl acrylate as monomers, a metal salicylate compound as a charge control agent, a saturated polyester as a polar resin, and a colorant, to produce colored suspension particles having a weight average particle diameter of 7 μm. Then, hydrophobic silica was added to this.
By transferring 5 wt%, a negative toner 8 having excellent transferability as described above and having little abrasion when cleaning the photosensitive drum 1 was manufactured.

In the developing device 4 described above, during the developing operation, the non-magnetic toner 8 in the developing container 14 is sent toward the elastic roller 6 with the rotation of the stirring member 16 in the direction of arrow C. Next, the toner 8 is carried to the vicinity of the developing sleeve 5 by the rotation of the elastic roller 6 in the direction of the arrow D, and the toner 8 on the elastic roller 6 is developed at the contact portion between the developing sleeve 5 and the elastic roller 6. By being rubbed with the sleeve 5, the toner is frictionally charged and adheres to the developing sleeve 5.

Thereafter, as the developing sleeve 5 rotates in the direction of arrow B, it is sent under pressure of the elastic blade 7 and is regulated by the elastic blade 7 to receive an appropriate amount of triboelectric charge (triboelectric charge) and A thin toner layer is formed on the sleeve 5. In the present invention, the contact pressure of the elastic blade 7 and the like are set so that 0.6 mg / cm ² can be obtained as a good toner coating amount.

However, as described above, the elastic blade 7 is deformed due to the pressure contact state of the end seal member 19, and the contact with the surface of the developing sleeve 5 becomes insufficient, or a gap is formed in the end seal portion. If the toner is not sufficiently triboelectrically charged, the toner will not be held on the developing sleeve 5 and will leak or scatter.

Therefore, in the present invention, as shown in FIG.
At a position downstream of the contact portion with the elastic blade 7 with respect to the rotation direction of the developing sleeve 5, a toner charge applying roller 102 contacting the surfaces of both end portions of the developing sleeve 5 is provided.

According to the present embodiment, the toner charge applying rollers 102 are provided integrally near both ends of the central shaft 101 parallel to the developing sleeve 5, and slide end bearings 101 a of both ends of the central shaft 101. By being fitted into the groove 103, it is installed rotatably and movably in the direction of the developing sleeve 5 along the groove. Each slide bearing 103 is attached to the developing container 14 via a supporting metal plate 15 that supports the elastic blade 7.

At each end of the developing sleeve 5, the charge applying roller 102 extends over both the hatched toner-coated area 105 on the surface of the developing sleeve 5 and the non-toner-coated area outside the area. It is pressed against the surface of the sleeve 5. The pressure contact of the charge applying roller 102
This is realized by the urging in the direction of the developing sleeve 5 by the pressing spring 104 attached to the supporting metal plate 15 and the weight of the end roller 102 itself and the center shaft 101. The charge applying roller 102 pressed against the developing sleeve 5 is driven to rotate in the direction of arrow E in accordance with the rotation of the developing sleeve 5.

The charge applying roller 102 and the central shaft 101 are made of a conductive metal, and the pressure spring 104 is also made of a conductive material. A bias power source 106 is connected to the pressure spring 104, and the power source 106 supplies the bias spring 1 during development.
04 and the charge applying roller 102 via the central shaft 101
, A bias having the same polarity as the charging polarity of the toner 8 is applied. As a result, the toner 8 carried on the developing sleeve 5 and conveyed to the charge applying roller 102 is charged with the same polarity as the charging polarity to the toner 8 pressed against the applying roller 102.

In this embodiment, the charge applying roller 102
Under the condition that the volume resistance of the central shaft 101 is 10 ⁶ Ωcm or less, and the negative toner is used as the non-magnetic toner 8, the charge applying roller 102 is applied with −300 V to −600 V.
Is applied, the toner having the same polarity as the charging polarity is applied to the toner pressed by the charge applying roller 102 at the end of the developing sleeve 5, and the toner increases the attraction force to the surface of the developing sleeve 5. In the held state, the developing container 14
Passing through the seal member 17 below the opening of the developing container 1
4 was confirmed to be reliably recovered. Further, the volume resistance of the charge applying roller 102 and the central shaft 101 is set to 10
^{Although it was set to 6} Ωcm or less, no electric leak occurred because toner was interposed between the developing sleeve 5 and the developing sleeve 5.

However, if the applied voltage is further increased to increase the charge amount of the toner, the leakage limit between the developing sleeve 5 and the charge applying roller 102 will be exceeded. The resistance is
It is better to be higher than the above.

FIG. 5 shows another embodiment of the present invention. In this embodiment, the charge applying roller 112 is disposed at each end of the developing sleeve 5. Each of the charge applying rollers 112 press-fits a metal center shaft 111 into a ring-shaped hollow elastic body 112 and freely rotates and moves both ends of the center shaft 111 into concave grooves of a slide bearing 113 similar to FIG. It fits freely. At both ends of the central shaft 111, a conductive pressure spring 104 for urging the application roller 112 in the direction of the developing sleeve 5 and bringing it into an electrically conductive state is pressed. Slide bearing 113 and pressure spring 10
4 is attached to a support plate (not shown) similar to the support plate 15 in FIG. 5, the same reference numerals as those shown in FIG. 4 denote the same members.

In this embodiment, an elastic roller having a volume resistance of 10 ⁸ to 10 ¹⁰ Ωcm is used as each of the charge applying rollers 112. In this embodiment, each of the charge applying rollers 112
When a voltage was applied under the conditions of 500 V to -800 V and 1 mA, it was confirmed that a charge was applied to the toner on the end of the developing sleeve 5 and sufficient adhesion to the developing sleeve 5 could be given.

FIG. 6 shows still another embodiment of the present invention.
In this embodiment, a leaf spring 124 having a pair of mounting frames 124a is provided at each end of the developing sleeve 5, and the center axis 121 of the charge applying roller 122 is supported between the frames 124a. The developing sleeve 5 was brought into contact with the surface of each end.

According to the present embodiment, the leaf spring 124 has the role of supporting the charge applying roller 122 and serving as a pressure spring, so that the space can be saved and simplified as compared with the embodiment of FIG.

While the embodiment of the present invention has been described above, the charge applying rollers 102, 112,
In a simulation test assuming a state in which the charging roller 122 is set in the developing device 4, an outer diameter of the charge applying roller is set to 6 to 12 mm, and an appropriate pressing state to the developing sleeve 5, for example, a pressing force of 50
２００200 grf, the contact width was 6 to 12 mm, the applied voltage was −500 V, and the set current value was 0.1 mA. By applying an electric charge to the toner at both ends of the developing sleeve, an adhesive force can be given to the developing sleeve, and the seal member 17 can be removed from the lower part of the opening of the developing container 14 without leaving the toner from the developing sleeve 5. It could be visually confirmed that it passed through and was collected in the developing container 14. When the voltage applied to the charge applying roller is turned off in this state,
The toner on both ends of the developing sleeve 5 is
, And could not pass through the lower seal member 17, and toner leakage and scattering were confirmed.

Further, it was confirmed what would happen if the rotation of the charge applying member with respect to the developing sleeve 5 could not be obtained. That is, when a resistance is applied so that the charge applying roller does not rotate and a peripheral speed difference is provided between the charge applying roller and the developing sleeve 5, the toner coating area 10 on the surface of the developing sleeve 5 in FIG.
The toner 5 is blocked by the charge applying roller and is peeled off from the developing sleeve 5, causing toner leakage and scattering. Therefore, it is necessary that the charge applying roller is driven to rotate with respect to the developing sleeve 5.

As described above, according to the present invention, the bias is applied to the charge applying roller which is driven to rotate by being pressed against both ends of the developing sleeve, thereby applying charges to the toner at both ends of the developing sleeve, and Increase adhesion to
The toner can be collected in the developing container 14 without causing leakage or scattering.

[0049]

As described above, according to the present invention,
Since electric charge is electrically applied to the insufficiently charged non-magnetic toner on both ends of the developer carrying member, leakage and scattering of the toner from the developing device can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of an image forming apparatus of the present invention.

FIG. 2 is a schematic sectional view showing a developing device installed in the image forming apparatus of FIG.

FIG. 3 is a view of the developing device of FIG. 2 as viewed from a photosensitive drum direction.

FIG. 4 is a perspective view showing toner charge applying members provided at both ends of a developing sleeve of the developing device of FIG. 2;

FIG. 5 is a perspective view showing a toner charge applying member according to another embodiment of the present invention.

FIG. 6 is a perspective view showing a toner charge applying member according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum 4 Developing device 7 Elastic blade 8 Non-magnetic toner 14 Developing container 15 Support metal plate 17 Seal member 19 End seal member 101 Central shaft 102 Toner charge application roller 103 Slide bearing 104 Pressure spring 104 106 Power supply

Claims (6)

[Claims] An image bearing member that carries the developer and conveys the developer to a development area facing the image bearing member; and a developer abutting member that regulates an amount of the developer carried on the developer bearing member. A developing device having a developer regulating member having the above-mentioned configuration, and is driven to rotate by being pressed against both ends of the developer carrying member with respect to the rotation direction of the developer carrying member at a position downstream of the contact portion of the developer regulating member. Developing characterized by providing a conductive member, applying a bias having the same polarity as the charged polarity of the developer to each of the conductive members, thereby applying a charge to the developer passing through the pressure contact portion of each of the conductive members. apparatus. 2. The developing device according to claim 1, wherein each of the conductive members is in pressure contact with the developer carrying member over both the developer carrying region of the developer carrying member and a non-developer carrying region outside the developer carrying region. 3. The developing device according to claim 1, wherein each of the conductive members is formed of a conductive metal roller. 4. The developing device according to claim 1, wherein said developer is a non-magnetic one-component developer. 5. A developing cartridge comprising a developing device detachably mounted on an image forming apparatus main body, wherein the developing device comprises the developing device according to claim 1. 6. An image forming apparatus provided with a developing device, wherein the developing device comprises the developing device according to claim 1. Description: