JPH1090998A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of stably obtaining high quality images and preventing contamination inside an image forming device caused by scattering of developer. SOLUTION: In a developing device comprising a developer container for housing non-magnetic one component developer, a developer carrier disposed in the opening part of the developer container so as to be freely rotated, an elastic regulating member brought into contact with the developer carrier via developer, a rotary elastic roller (developer replenishing member) 6 brought into contact with the rotational direction upstream side of the developer carrier with respect to the contact part of the developer carrier of the elastic regulating member, a blowing-out preventing sheet for preventing blowing-out of the developer from the developer container by the elastic roller 6 and an end part sealing member 51 for the leakage of the developer from the developer carrier to the outside of the developer container, the side end face of the end part sealing member 51 inside the developer container opening part is at least brought into contact with the side end face of the elastic roller 6. Thus, melting or scattering of the developer on the developer carrier caused by a developer flocculated lamp generated in a non-contact area between the elastic roller 6 and the developer carrier is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to a developing device of an image forming apparatus such as an electrophotographic printer.

[0002]

2. Description of the Related Art In an image forming apparatus employing an electrophotographic method, an electrostatic latent image formed on an image carrier is visualized as a toner image by a developing device.

Various dry one-component developing devices have been proposed and put into practical use as one of such developing devices. On the other hand, demands for improved resolution and sharpness of images, multicoloring, multicolor images, etc. have been increasing year by year. In order to form such an image, practical use of a non-magnetic developer is particularly essential.
In particular, in the case of an electrophotographic printer that is required to be miniaturized, practical use of a non-magnetic one-component developer is particularly essential.

With respect to a magnetic developer used for forming a conventional monochromatic image (black and white image), a magnetic force generated by a magnetic pole or the like provided in the developer carrier is used to hold the magnetic developer on the developer carrier. Although it was possible to use the holding force that was used, it was not possible to apply magnetic holding to hold the non-magnetic developer on the developer carrier, and the transport force of the developer carrier and the developer itself were The non-magnetic developer is held on the developer carrier by the electrostatic mirror force of the held charge. Therefore, in the case of a non-magnetic developer, a developer supply member is required as a member for supplying the developer to the developer carrier.

A foamable elastic roller is mainly used as the developer replenishing member. The elastic roller rotates in the same direction as the rotation direction of the developer carrier to supply the developer to the developer carrier. At the same time, it is required to have a function of scraping off the developer remaining on the developer carrier after the development process on the image carrier is completed.

The developer supplied to the developer carrier by the developer replenishing member is transferred onto the developer carrier by a rubber or metal developer regulating member abutting on the developer carrier. The coating is uniformly regulated to a predetermined layer thickness, and at the same time, a sufficient tribo necessary for development is provided.

The developer regulating member and the developer replenishing member are in contact with the developer carrying member at the opening of the developing container, and further, at both end portions thereof, the developer is prevented from leaking. The seal member is in close contact with the developer carrying member.

[0008]

However, the structure of the conventional developing device has the following problems.

That is, when the developer replenishing roller, which is a developer replenishing member, is in contact with the developing container wall with little clearance, the developer is supplied between the developer replenishing roller and the developing container wall. The wall is strongly rubbed, the developer gradually aggregates and coarsens, and the coarsened developer is sent to the developer regulating member to regulate the developer,
There is a problem that the coagulated developer is fused to the developer regulating member, and the developer slips through and scatters around the portion where the developer is fused as a center.

In order to fulfill the demand for higher image quality, which has been increasing in recent years, the resolution is increased by reducing the particle size of the developer, and the transferability is improved by making the developer spherical.

However, when the developer is reduced in diameter and spheroidized as described above, the fluidity of the developer is increased and the developer is easily leaked from the developing container, and the bulk density is increased, so that the developer is apt to be agglomerated. Tends to accelerate the occurrence of

In order to overcome the above-mentioned problem, a gap is formed between the developer supply roller and the wall of the developing container so that the aggregate of the developer is not generated, so that the generation of the aggregate is prevented. Measures have been taken to avoid flyaway.

However, the above measures are not perfect, and the developer on the developer carrier cannot be scraped off by the developer replenishment roller in the non-contact area where the developer replenishment roller and the developer carrier are not in contact. Deterioration of the developer on the developer carrier is promoted, and furthermore, the developer is continuously supplied to the region, resulting in an oversupply state, further promoting the deterioration of the developer and simultaneously aggregating the developer. Therefore, there is a problem that the developer is scattered from the developer regulating member, which affects the image quality.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object thereof is to stably obtain a high-quality image and to contaminate the inside of an image forming apparatus main body due to scattering of a developer. It is an object of the present invention to provide a developing device capable of preventing the development.

[0015]

According to a first aspect of the present invention, there is provided a developing container containing a non-magnetic one-component developer, and a rotatably disposed opening of the developing container. A developer carrying member, an elastic regulating member that abuts on the developer carrying member via the developer, and an upstream side in the rotation direction of the developer carrying member with respect to a contact portion of the elastic regulating member with the developer carrying member. A rotatable developer replenishing member that abuts against the developer, a blowing prevention sheet that prevents the developer replenishing member from blowing out the developer from the developing container, and leakage of the developer from the developer carrier to the outside of the developing container. In the developing device having an end seal member for preventing the above problem, a side end surface of the end seal member inside the opening portion of the developing container is at least abutted on a side end surface of the developer supply member.

According to a second aspect of the present invention, in the first aspect of the present invention, the side end surface of the end seal member on the inner side of the opening of the developing container is extended around the developer carrier to the lower end of the free end of the elastic regulating member. It is characterized by being provided so as to extend.

According to a third aspect of the present invention, in the first aspect of the present invention, the blowout prevention sheet and the end seal member overlap each other with respect to the extension width of the end seal member toward the inside of the developing container opening. The width is made constant.

According to a fourth aspect of the present invention, in the first, second, or third aspect, the hardness of the end seal member is greater than the hardness of the developer supply member.

Therefore, according to the present invention, by simply extending the length of the end seal member toward the inside of the opening of the developing container, the end seal member is generated in the non-contact area between the developer supply member and the developer carrier. Since the fusion of the developer and the scattering of the developer due to the aggregated developer are prevented, a high-quality image can be stably obtained, and the image forming apparatus associated with the scattering of the developer. Contamination in the body can be prevented.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> FIG. 1 is a sectional view of an image forming apparatus provided with a developing device according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view of the developing device.

In FIG. 1, reference numeral 1 denotes a photosensitive drum as a latent image carrier. The photosensitive drum 1 rotates in a direction indicated by an arrow A in FIG. 3 forms an electrostatic latent image on its surface.

The electrostatic latent image is developed by the developing device 4 and is visualized as a toner image. The developing device 4 is disposed in close proximity to the photosensitive drum 1 and is detachably attached to the image forming apparatus main body as a process cartridge. It is configured. In the present embodiment, so-called reversal development for forming a toner image on an exposed portion is performed.

The visualized toner image on the photosensitive drum 1 is transferred by a transfer roller 9 to paper 13 as a recording medium, and the transfer residual toner remaining on the photosensitive drum 1 without being transferred is scraped off by a cleaning blade 10. The photosensitive drum 1 stored and cleaned in the waste toner container 11 repeats the above-described operation to form an image.

On the other hand, the paper 13 to which the toner image has been transferred is subjected to a fixing process by the fixing device 12, and is discharged out of the device to complete the printing operation.

Here, the developing device 4 according to the present invention will be described with reference to FIG.

In FIG. 2, reference numeral 14 denotes a developing container for containing the non-magnetic toner 8 as a one-component developer, and an opening extending in the longitudinal direction in the developing container 14 is disposed so as to face the photosensitive drum 1. The developed developing sleeve 5 as a developer carrier is rotatably disposed, and the electrostatic latent image on the photoconductor 1 is developed and visualized by the non-magnetic toner 8 carried on the developing sleeve 5.

The developing sleeve 5 protrudes into the developing container 14 at a substantially right half peripheral surface shown in the drawing at the opening of the developing container 14, and is laterally provided with a substantially left half peripheral surface exposed outside the developing container 14. ing. The surface of the developing sleeve 5 exposed to the outside of the developing container 14 faces 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 indicated by the arrow B in FIG. 2, and has a surface with moderate unevenness. The unevenness increases the probability of sliding of the developing sleeve 5 with the non-magnetic toner 8. At the same time, the conveyance of the non-magnetic toner 8 is favorably performed.

An elastic regulating blade 7 is provided above the developing sleeve 5 so as to be supported by a holding metal plate 15. The vicinity of the free end of the elastic regulating blade 7 is near the outer peripheral surface of the developing sleeve 5. Are in contact with each other.
Note that the contact direction of the elastic regulating blade 7 with the developing sleeve 5 is a so-called counter (reverse) direction in which the tip side with respect to the contact portion is located on the upstream side in the rotation direction of the developing sleeve 5. The elastic blade 7 has a conductive layer via a rubber elastic layer at least at a contact portion with the developing sleeve 5, and in the present embodiment, the rubber elastic layer has a urethane rubber having a rebound resilience of 20% or more. SUS or phosphor bronze metal sheet having spring elasticity is used as the conductive layer.

Further, in FIG. 2, reference numeral 6 denotes an elastic roller as a developer replenishing member. The elastic roller 6 is located upstream of a contact portion of the elastic regulating blade 7 with the surface of the developing sleeve 5 in the direction of rotation of the developing sleeve. And is rotatably supported.

In the developing device 4 having the above configuration,
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 19 in the direction of arrow C.

The non-magnetic toner 8 is applied to the elastic roller 6
Is rotated in the direction of arrow D in the figure, and is conveyed to the vicinity of the developing sleeve 5, and the non-magnetic toner 8 carried on the elastic roller 6 at the contact portion between the developing sleeve 5 and the elastic roller 6 is in contact with the developing sleeve 5. The rubbing causes the toner to receive triboelectric charge and adhere to the developing sleeve 5.

Thereafter, the non-magnetic toner 8 is applied to the developing sleeve 5
Is sent under the pressure of the elastic regulating blade 7 along with the rotation in the direction of arrow B, and receives a proper tribo (amount of frictional charge) to form a thin layer on the developing sleeve 5.
Is conveyed to a developing unit which is a part facing the developing unit and subjected to development.

By the way, the undeveloped toner not consumed in the developing section is recovered from the lower part of the developing sleeve 5 with the rotation of the developing sleeve 5. A blowout prevention sheet 20 is provided in the collection portion. The blowout prevention sheet 20 allows the undeveloped toner to pass into the developing container 14 and the non-magnetic toner 8 in the developing container 14.
From leaking from the lower portion of the developing sleeve 5.

Then, the collected undeveloped toner on the developing sleeve 5 is peeled off from the surface of the developing sleeve 5 at the contact portion between the elastic roller 6 and the developing sleeve 5. Most of the stripped toner is conveyed with the rotation of the elastic roller 6 and mixes with the non-magnetic toner 8 in the developing container 14, whereby the charge of the toner is dispersed. At the same time, the rotation of the elastic roller 6 causes the developing sleeve 5 to rotate.
A new toner 8 is supplied above, and the above operation is repeated.

The latent image on the photosensitive drum 1 is an alternating voltage (developing AC bias) obtained by superimposing a direct current applied by the power supply 21 between the developing sleeve 5 and the photosensitive drum 1.
The toner image is developed by the electric field generated as a result and is visualized as a toner image.

Next, specific examples of each component of the developing device 4 will be described below.

The developing sleeve 5 has a surface roughness Rz by subjecting a surface of an aluminum sleeve having a diameter of 16 mm to a fixed blasting treatment with glass beads (# 600).
Is set to about 3 μm, and is opposed to the photosensitive drum 1 so that the gap is 300 μm.
Peripheral speed of 80 mm /
s.

The toner 8 is a non-magnetic one-component developer. The non-magnetic one-component developer has excellent transfer properties. The non-transferred toner remaining on the photosensitive drum 1 without being transferred is removed by a blade, a fur brush or the like. The cleaning means is required to have high lubricity when cleaning, and therefore, the toner 8 is advantageous in that the wear of the photosensitive drum 1 can be kept small, that is, the toner 8 is spherical and has a surface. Is used. More specifically, the shape factors having SF-1 of 100 to 180 and SF-2 of 100 to 140 are used. The SF-1 and SF-2 are manufactured by Hitachi, Ltd.
Using an E-SEM (S-800), 100 toner images are randomly sampled, and the image information is imaged through an interface using an image analyzer manufactured by Nicole (Lusex3).
And analyzed, and defined as the value obtained by the following equation.

[0040]

SF-1 = (MXLNG) ² / AREA × π / 4 × 100 SF-2 = (PERI) ² / AREA × π / 4 × 100 where AREA: toner projection area MXLNG: absolute maximum length PERI : Perimeter The shape factor SF-1 of the toner indicates a spherical degree, and is 100.
The shape gradually changes from a spherical shape to an irregular shape as the size increases.
The shape factor SF-2 indicates the degree of unevenness. As the shape coefficient SF-2 increases from 100, the unevenness of the toner surface becomes more conspicuous.

As for the method of producing the toner, if it falls within the range of the shape factor described above, in addition to the production method using a so-called pulverization method, JP-A-39-10231 and JP-A-59-78 can be used.
No. 56, a method of directly producing a toner using a suspension polymerization method, or a method of directly producing a toner using an aqueous organic solvent in which the obtained polymer is insoluble and soluble in a monomer. An emulsion polymerization method typified by a polymerization method or a soap-free polymerization method of directly polymerizing in the presence of a water-soluble polar polymerization initiator to form a toner can be used.

In this embodiment, the shape factor SF-1 of the toner is set to 100 to 180, and the shape factor SF-2 is set to 100 to 1
40, and a suspension polymerization method under normal pressure or under pressure that can easily obtain a fine particle toner having a sharp particle size distribution and 4 to 8 μm particle size, using 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 coloring agent were added to produce colored suspension particles having a weight average particle diameter of 7 μm. Then, add 1.5 g of hydrophobic silica.
By transferring the wt%, a toner 8 having a negative polarity, which is excellent in the transferability as described above and can suppress abrasion during cleaning of the photosensitive drum 1 to a small level, was manufactured.

The elastic roller 6 has a foam skeleton sponge structure or a fur brush structure in which fibers such as rayon and nylon are planted on a cored bar. The elastic roller 6 is used to supply the toner 8 to the developing sleeve 5 and to remove the undeveloped toner. In this embodiment, a roller having a diameter of 16 mm in which a polyurethane foam is provided on a metal core is used in this embodiment. The contact width of the elastic roller 6 with the developing sleeve 5 is 1 to 8 mm.
Is effective, and it is preferable that the developing sleeve 5 has a relative speed at a contact portion thereof. In the present embodiment, the contact width is set to 3 mm, and the peripheral speed of the elastic roller 6 is set to 3 mm. During the developing operation, the driving means (not shown) was rotated at a predetermined timing so as to be 50 mm / s (the relative speed with respect to the developing sleeve 5 was 130 mm / s).

Next, a method of applying an alternating electric field formed between the developing sleeve 5 and the elastic regulating blade 7 and the function and effect will be described.

A power supply 21 to which an AC voltage and a DC voltage can be applied is connected to the developing sleeve 5, and a peak-to-peak voltage as a rectangular wave as an AC component is supplied from the power supply 21 to the developing sleeve 5 as a developing bias during a developing operation. 2000
V, a frequency of 2000 Hz, and a DC component of -4
00V is applied. As a result, the latent image potential V1 of the exposed portion of the photosensitive drum 1 is -150V (the potential of the non-exposed portion is -150V).
So-called reversal development for developing the negative toner 8 is performed.

According to the present invention, the toner 8 on the developing sleeve 5 in the developing device 4 is prevented from adhering to the downstream side of the nip of the elastic regulating blade 7 by the following method.

FIG. 3A is a diagram showing a sealing structure at the end of the developing device according to the present invention, and FIG. 3B is a diagram showing a conventional sealing structure at the end of the developing device.

Conventionally, as the end seal 51, an adhesive layer such as a double-sided tape which is generally commercially available for adhesion to a developing container is used as the lowermost layer. In order to alleviate this problem, use a fluorine-based nonwoven fabric (Teflon felt, etc.) which is a highly slidable member. The intermediate layer has a compression between the developing sleeve and the seat surface of the developing container in order to sufficiently prevent leakage of toner. An elastic member, such as a sponge or a nonwoven fabric, which can be sufficiently absorbed is effective. In this embodiment, wool felt is used. FIG.
In (a) and (b), W is a developing container wall.

As shown in FIG. 3A, the developing sleeve 5 and the elastic roller 6 are extended by extending the end sealing member 51 until it comes into contact with the side end of the elastic roller 6.
, The amount of toner supplied to the non-contact area is reduced, and the toner leakage due to the toner aggregate is eliminated. This effect was compared with that of the conventional configuration shown in FIG. 3B by idle rotation for one hour.

In the conventional configuration, the non-contact portion takes 10 to 20 minutes,
In particular, slight toner leakage was observed from the boundary, and 3
At 0 minutes, continuous toner leakage and severe toner scattering were observed.

However, FIG.
When the configuration of the end seal 51 shown in FIG. 1A is adopted, even after 1 hour, no toner leaks from the non-contact area and permanent image formation without toner leakage is realized. Is now possible.

It is preferable that the end seal member 51 has a hardness higher than the hardness of the elastic layer of the elastic roller 6. That is, the end seal member 51 is
It is desirable that the elastic roller 6 is almost in contact with or slightly bites into the elastic roller 6. Therefore, it is required that the elastic roller 6 has a hardness higher than that of the elastic roller 6. It is hoped that there will be no

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a diagram showing a sealing structure at an end of the developing device according to the second embodiment of the present invention, and FIG. 5 is a sectional view taken along line AA of FIG.

In this embodiment, the developer container wall W
The end seal member 51 is brought into contact with the side end of the elastic roller 6 while maintaining a predetermined gap between the elastic roller 6 and the elastic roller 6, and the end seal member 51 is elastically attached to the side end surface inside the opening of the developing container. The regulating blade 7 is provided so as to extend around the developing sleeve 5 to the lower end of the free end.

Thus, according to the present embodiment, the developing sleeve 5 and the elastic roller 6 are provided more than in the first embodiment.
Thus, the prevention of toner leakage in the non-contact area is more complete, and it has become possible to prevent long-term toner leakage and maintain stable high image quality.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a view showing a sealing structure of an end portion of the developing device according to the third embodiment of the present invention, FIG. 7 is a sectional view taken along line BB of FIG. 6, FIGS.
FIG. 3 is a diagram showing a conventional example and a comparative example for the present embodiment.

In this embodiment, the sealing member 20
The overlap width with the elastic seal member 51 is set to the end seal member 5.
1 is constant with respect to the width of extension of the inside of the opening of the developing container.

The end seal member 51 and the developing sleeve 5 are always slid at a predetermined pressure at the end of the developing sleeve 5, thereby preventing the blow-out that is sandwiched therebetween and adhered to the developing container. The sheet 20 is a developing sleeve 5
, And the frictional force gradually becomes greater than the adhesive force with the developing container, so that the function of the blowout prevention sheet 20 is sufficiently ensured.

The conventional blowing prevention sheet 20 shown in FIG.
When the end seal member 51 is extended to the inside of the opening of the developing container while keeping the dimensions of the above, the area where the blowout prevention sheet 20 and the end seal member 51 overlap is large as shown in FIG. As shown in FIG. 7, in the present embodiment, the longitudinal width of the blow-out prevention sheet 20 is reduced by an amount corresponding to the increased amount of the end seal member 51 entering the opening of the developing container. Deformation by the sleeve 5 is prevented.

In this embodiment, too, the same evaluation as in Embodiment 1 was carried out based on idle rotation, and the prevention of toner leakage from the blowout prevention sheet 20 was more complete. That is, also in the present embodiment, toner leakage can be prevented by bringing the end seal member 51 into contact with the side end surface of the elastic roller 6.

In the above-described embodiment, an example in which a spherical polymerized toner is used as the toner has been described. However, the present invention is not limited to this, and any toner may be used as long as the developing device has a toner supply member. Can be.
Further, in the first to third embodiments, the developing device detachably attached to the image forming apparatus main body has been described. However, the present invention is also applicable to a developing device fixed in the image forming apparatus main body and configured to receive only toner supply. Of course.

[0062]

As is apparent from the above description, according to the present invention, a developing container for containing a non-magnetic one-component developer, and a developer carrier rotatably disposed at the opening of the developing container. And an elastic regulating member which comes into contact with the developer carrying member via a developer, and a rotation which comes into contact with a contact portion of the elastic regulating member with the developer carrying member on the upstream side in the rotational direction of the developer carrying member. A possible developer supply member, a blowout prevention sheet for preventing the developer from blowing out of the developer container by the developer supply member, and an end for preventing the leakage of the developer from the developer carrier to the outside of the development container. In the developing device having the external seal member, since the side end surface of the end seal member inside the opening of the developing container is brought into contact at least with the side end surface of the developer supply member, a high quality image can be stably obtained. As the developer scatters There is an advantage that it is possible to prevent the contamination of the image forming apparatus main body.

[Brief description of the drawings]

FIG. 1 is a sectional view of an image forming apparatus including a developing device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the developing device according to the first embodiment of the present invention.

FIG. 3A is a diagram illustrating a sealing structure at an end of the developing device according to the first embodiment of the present invention, and FIG. 3B is a diagram illustrating a conventional sealing structure at an end of the developing device.

FIG. 4 is a diagram showing a seal structure at an end of a developing device according to a second embodiment of the present invention.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is a diagram showing a seal structure at an end of a developing device according to a third embodiment of the present invention.

FIG. 7 is a sectional view taken along the line BB of FIG. 6;

FIG. 8 is a diagram showing a conventional seal structure for a third embodiment of the present invention.

FIG. 9 is a diagram showing a comparative example with respect to the third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 4 developing device 5 developing sleeve (developer carrying member) 6 elastic roller (developer replenishing member) 7 elastic regulating blade (elastic regulating member) 8 nonmagnetic toner 14 developing container 20 blowout prevention sheet 51 end seal member

Claims (4)

[Claims] 1. A developing container for storing a non-magnetic one-component developer, a developer carrier rotatably disposed at an opening of the developing container, and abutting on the developer carrier via a developer. An elastic regulating member, a rotatable developer replenishing member abutting on the upstream side in the rotational direction of the developer carrying member with respect to a contact portion of the elastic regulating member with the developer carrying member, and developing by the developer replenishing member. A blowing prevention sheet for preventing the developer from blowing out of the developing container, and a developing device having an end sealing member for preventing leakage of the developer from the developer carrier to the outside of the developing container; A developing device, wherein a side end face inside the opening portion of the developing container is brought into contact with at least a side end face of the developer supply member. 2. The image forming apparatus according to claim 1, wherein a side end face of the end seal member inside the opening of the developer container is provided so as to extend around the developer carrier to a lower end of the free end of the elastic regulating member. 2. The developing device according to 1. 3. The overlapping width of the blowout prevention sheet and the end seal member is made constant with respect to the width of the end seal member extending inward of the opening of the developer container. Developing device. 4. The developing device according to claim 1, wherein the hardness of the end seal member is greater than the hardness of the developer supply member.