JPH11288161A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a developer supply member capable of preventing toner from being deteriorated, and stably obtaining an image which does not have fogging, whose density is sufficient, and whose image quality is uniform for a long time, and to obtain a developing device provided with the same. SOLUTION: The toner supply roller 6 of the developing device is constituted to be an elastic roller obtained by providing a foam roller 16 using consecutively foamable polyurethane foam as a foamed elastic body on the periphery of a metallic rotary shaft 17. As to the roller 16; the cell number of the foamed elastic body is 55 pieces whose size is >=25 mm, 100 pieces whose size is >=25 mm, and quantity of air flow is 10 to 40 cc/cm<2> /sec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image formed by an electrophotographic method or an electrostatic recording method, and more particularly to a developing device for supplying a one-component developer to a developer carrier to carry the developer. The present invention relates to an improvement in a developer supply member made of a foamed elastic material.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, an image recording apparatus, a printer, and a facsimile, an electrostatic latent image formed on a latent image carrier made of an electrophotographic photosensitive member or an electrostatic recording dielectric is used. Are developed by a developing device and visualized as a toner image. As one of such developing devices, various one-component developing devices using a one-component developer of a non-magnetic toner as a developer have been proposed and put into practical use.

For example, as shown in Japanese Patent Application Laid-Open No. 54-43038, a rubber or metal elastic blade as a developer regulating member is brought into contact with the surface of a developing sleeve as a developer carrying member. By passing non-magnetic toner between the contact portions of the elastic blade and the developing sleeve to regulate it, a thin layer of toner is formed on the developing sleeve,
In addition, there is a developing device that imparts a sufficient triboelectric charge (triboelectric charge) to the toner by friction at a contact portion.

The one-component developing device using the above-mentioned non-magnetic toner requires a separate toner supply member for supplying the toner onto the developing sleeve. This is for magnetic toners.
This is because toner can be supplied onto the developing sleeve by the magnetic force of the magnet in the developing sleeve, but in the case of non-magnetic toner, toner cannot be supplied by the magnetic force.

[0005] That is, as shown in FIG. 1, a one-component developing device 4 contains a non-magnetic toner 8 in a developing container 14.
A toner supply roller 6 that contacts the developing sleeve 5 at a position upstream of the elastic blade 7 in the rotation direction of the developing sleeve 5.
The non-magnetic toner conveyed by the stirring member 18 in the container 14 is rotated by rotating this in the direction D (the direction in which the facing portion moves in the opposite direction) with respect to the developing sleeve 5 rotating in the direction B. 8 is supplied to and carried on the developing sleeve 5.

The toner 8 carried on the developing sleeve 5
Then, as the developing sleeve 5 rotates, it is sent to a contact portion with the elastic blade 7, where the layer is thinned, and then conveyed to the developing unit facing the photosensitive drum 1, It is used for developing the latent image. The toner 8 remaining on the developing sleeve 5 without being used for development is
The toner is returned into the developing container 14 by the toner supply roller 6, peeled off from the surface of the developing sleeve 5 by the toner supply roller 6, mixed with the other toner 8 by the stirring member 18, and thereafter, by the toner supply roller 6 as described above. The supply to the developing sleeve 5 is repeated.

[0007] In recent years, the demand for images in computers and the like that handle images in digitized form has increased, and accordingly, higher-definition and higher-quality images have been demanded. Further, improvements in color images and electrophotographic images have been demanded. I have.

As a developing device meeting such a demand,
Many proposals using a foamed elastic body for the toner supply roller 6 have been proposed and commercialized. This toner supply roller 6
Is an elastic roller provided with a foamed elastic body (sponge) such as polyurethane foam around the rotation axis.
It is excellent in durability and productivity, and there is no fatal trouble as a developing device such that the fur on which the fur brush is implanted comes off and is caught in the contact portion between the developing sleeve 5 and the elastic blade 7. is there.

[0009]

However, in order to study the performance of the toner supply roller 6 using the foamed elastic body, the present inventors used several kinds of foamed elastic materials for the toner supply roller, 4 for development
When image formation was repeated, when the number of times of image formation increased, so-called fog, in which toner adhered to non-image portions, occurred.

[0010] The fog phenomenon caused by the image formation many times is mainly caused by the deterioration of the toner due to the rubbing of the toner supply roller 6 and the developing sleeve 5. If the deterioration of the toner is further promoted, in addition to fog, the toner cannot have a sufficient triboelectric charge, resulting in problems such as a low density and further scattering of the toner.

Conventionally, in order to suppress the deterioration of the toner, the toner supply roller 6 has to be reduced in the amount of intrusion into the developing sleeve 5 or the hardness of the foamed elastic body of the toner supply roller 6 has been reduced. It has been proposed to contact the developing sleeve 6 with the developing sleeve 5 with a light load.

As described above, the toner supply roller 6
It has both a function of supplying toner to the developing sleeve 5 and a function of peeling off residual toner from the developing sleeve 5. Comparing the two functions from the viewpoint of applying stress to the toner, the peeling function gives more stress than the toner supplying function. Looking at the toner before and after the development, the toner after the development has a higher percentage of particles such as toner fine powder that is less likely to contribute to the development, and the toner is more susceptible to stress during the stripping process. In state.

In the stripping process, the undeveloped toner peeled off from the developing sleeve 5 is captured by the foam cells formed on the surface of the foamed elastic body constituting the toner supply roller 6, and in this state, the toner supply roller It is transported with the rotation of 6. When the surface of the foamed elastic body deformed at the contact portion with the developing sleeve 5 passes through the contact portion and the deformation is restored to its original state, a part of the toner captured by the restoring force causes a part of the foamed elastic body. Depart from the surface of. Further, a part of the captured toner separates from the surface of the foamed elastic body due to its own weight, and receives an external force due to the flow of the toner formed in the developing device 4 as the toner supply roller 6 rotates. Also, a part of the toner is separated from the surface of the foamed elastic body.

However, while the majority of the toner trapped in the foam cells is retained, the toner supply roller 6 is rotated once to make one revolution and then subjected to the peeling process again. It gradually penetrates into the inside of the roller 6 and is absorbed. If the type of foam elastic is
If the toner supplied to the toner supply roller 6 has a property of giving a slow movement, the toner inside the toner supply roller 6 is gradually compressed by the toner absorbed from the developing sleeve 5 one after another. The toner cannot be moved inside the toner supply roller 6 and stays there.

When the inside of the toner supply roller 6 is filled with the staying toner as described above, the toner supply roller 6 starts to be hardened, and at the same time, the toner inside the toner supply roller 6 is aggregated or solidified to develop an image. Toner that cannot participate in the process. Also, the toner which cannot be separated from the surface of the toner supply roller 6 and is compressed and agglomerated starts to exist.
When the surface of the toner supply roller 6 is covered with the condensed toner, not only the remaining toner on the developing sleeve 5 cannot be peeled off, but also the toner rubs against the developing sleeve 5 with a large force at a contact portion with the developing sleeve 5. The toner supply roller 6
Deterioration of the toner is also increased on the surface of the developing sleeve 5, which eventually causes a fatal problem of fusion of the toner to the developing sleeve 5.

[0016] Because of this, the toner that has penetrated inside can move satisfactorily without stagnation, and the toner inside can be promptly extruded by the toner that penetrates inside through repeated stripping. It is desired to develop a toner supply roller made of a foamed elastic material and a developing device provided with the toner supply roller so that the toner supply roller can flow out to the outside.

An object of the present invention is to provide a toner having the above-mentioned characteristics, preventing deterioration of the toner, free from fog, having a sufficient density and uniform image quality for a long period of time. An object of the present invention is to provide a developer supply member and a developing device including the same.

[0018]

The above object is achieved by a developer supply member and a developing device according to the present invention. In summary, the present invention is a developer supply member for supporting a one-component developer on the developer carrier by rotating while being in contact with the developer carrier of the developing device. In a developer supply member provided with a foamed elastic body, the foamed elastic body has a foam cell number of 55 cells / 25 mm or more and 100 cells / 25 mm or less, and a ventilation volume of 10 to 40 cc / c.
m ² / sec. According to the present invention, preferably, the variation range of the ventilation amount of the developer supply member is within a range of ± 25% of a predetermined value.

According to another aspect of the present invention, the contact pressure per unit length in the longitudinal direction of the developer supply member with respect to the developer carrier, and the contact pressure of the developer supply member with respect to the developer supply member The variation width in the direction is defined to be within a range of ± 15% of a predetermined value. Alternatively, the variation width of the average value of the contact pressure in the circumferential direction of the developer supply member in the longitudinal direction of the developer supply member is defined to be within a range of ± 15% of a predetermined value.

According to still another aspect of the present invention, there is provided a rotating developer carrier that carries a one-component developer and conveys the developer to a developing section opposed to the image carrier, and rotates the developer carrier in contact with the developer carrier. A developer supply member for supplying and supporting the one-component developer on the developer carrier, wherein the developer supply member is provided with a foamed elastic body around a rotation shaft. The developer supply member is the developer supply member described above.

[0021]

Embodiments of the present invention will be described below in 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.

The developing device 4 has a developing container 14 containing a non-magnetic toner 8 of a one-component developer.
A developing sleeve 5 as a developer carrying member is arranged opposite to the photosensitive drum 1 at an opening extending in the longitudinal direction of 4 (perpendicular to the plane of the drawing). The developing sleeve 5
A substantially right half circumferential surface shown in the figure protrudes into the developing container 14, and a left substantially half circumferential surface is exposed outside the developing container 14 so as to be laterally provided at the above-mentioned opening. It is opposed to the drum 1 with a small interval. Developing sleeve 5
Is driven to rotate in the direction of arrow B.

The surface of the developing sleeve 5 has a rough surface with moderate irregularities in order to increase the probability of rubbing with the toner 8 and to improve the transportability of the toner 8. This rough surface
It can be suitably formed by forming by blast treatment with Alundum abrasive glass beads, or by coating conductive particles such as metal oxide particles, graphite, and carbon with a phenol resin or the like as a binder.

At a position above the developing sleeve 5, an elastic blade 7 attached to the developing container 14 by a holding metal plate 15 is installed. The vicinity of the free end of the elastic blade 7 is located on the outer peripheral surface of the developing sleeve 5. It is in contact by surface contact. The contact direction of the elastic blade 7 is a so-called counter direction in which the tip is located upstream of the contact portion in the rotation direction of the developing sleeve 5.

The elastic blade 7 is made of SU having spring elasticity.
Urethane rubber on a metal thin plate 7a of S or phosphor bronze;
The elastic body 7b is provided by injection molding of a rubber material such as silicone rubber or various elastomers. In the present embodiment, the elasticity of the non-magnetic toner 8 is increased by applying a negative triboelectric charge. The elastic body 7b was formed of a polyamide elastomer having excellent and appropriate elasticity.

The toner supply roller 6 is in contact with the contact portion of the elastic blade 7 with the developing sleeve 5 on the upstream side in the rotation direction of the developing sleeve 5 and is rotatably supported. The toner supply roller 6 will be described later in detail.

In the developing device 4 as described above, the non-magnetic toner 8 in the developing container 14 is supplied to the stirring member 1 during the developing operation.
8 is fed in the direction of the toner supply roller 6 with the rotation in the direction of arrow C. The toner 8 sent to the toner supply roller 6 is carried to the vicinity of the developing sleeve 5 by the rotation of the toner supply roller 6 in the direction of arrow D, and rubs at the contact portion between the developing sleeve 5 and the toner supply roller 6. As a result, a negatively charged triboelectric charge is applied to the developing sleeve 5.
Adheres to the surface of

The toner 8 thus carried on the developing sleeve 5 is carried to the elastic blade 7 with the rotation of the developing sleeve 5 in the direction of the arrow B. , And is formed on the developing sleeve 5 as a thin layer of toner. Thereafter, the photosensitive drum 1 is conveyed to a developing section facing the photosensitive drum 1 and is used for developing an electrostatic latent image on the photosensitive drum 1.

At the time of development, a developing bias in which an AC voltage is superimposed on a DC voltage is applied between the developing sleeve 5 and the photosensitive drum 1 by the developing power supply 20 so that the toner on the developing sleeve 5 The latent image is developed by attaching to the electrostatic latent image and is visualized as a toner image.

Undeveloped toner not consumed in the development on the developing sleeve 5 is collected into the developing container 14 from below the developing sleeve 5 as the developing sleeve 5 rotates. A seal member 19 is provided at the collecting portion. The seal member 19 allows the remaining toner to be developed to pass into the developing container 14, and the toner 8 in the developing container 14 leaks from a lower portion of the developing sleeve 5. To prevent

The collected toner 8 is peeled off from the surface of the developing sleeve 5 at the contact portion between the toner supply roller 6 and the developing sleeve 5. Most of the stripped toner is conveyed toward the stirring member 18 with the rotation of the toner supply roller 6, mixed with the toner 8 in the developing container 14, and charged by the stripped toner. The charge is dispersed in the mixed toner. At the same time, the toner 8 is newly supplied onto the developing sleeve 5 by the rotation of the toner supply roller 6, and the above operation is repeated.

A specific example of each component of the developing device 4 in this embodiment will be described.
A 6 mm aluminum sleeve surface was coated with a carbon-dispersed phenol resin to a thickness of about 10 μm, and the surface roughness Ra was about 0.9 μm. The gap between the developing sleeve 5 and the photosensitive drum 1 is about 300 μm, and the gap between the developing sleeve 5 and the peripheral speed of the photosensitive drum 1 is slightly faster than 117 mm / sec.
The developing sleeve 5 was rotated at a peripheral speed of 9 mm / sec.

The elastic blade 7 was composed of a thin plate 7a of a phosphor bronze plate having a thickness of 0.1 mm and an elastic member 7b made of a polyamide elastomer having a thickness of 1 mm formed thereon by bonding or molding.

During development, the developing sleeve 5
As a developing bias, a voltage obtained by superimposing an AC voltage having a frequency of 2000 Hz and a peak-to-peak voltage of 2000 V and a DC voltage of -400 V was applied. The latent image on the photosensitive drum 1 was formed such that the surface potential of the non-exposed portion was -600 V and the surface potential of the exposed portion was -150 V, and the latent image was developed by reversal development of the exposed portion. The non-magnetic toner 8 has an average particle size of 6 μm.
Was used.

The toner supply roller 6 according to the present invention will be described.

As shown in FIG. 2, the toner supply roller 6 is an elastic roller provided with a foamed elastic roller (form roller) 16 around a metal rotating shaft 17. In this embodiment, the diameter of the rotating shaft 17 is 5 mm,
A foam roller 16 having an outer diameter of 16 mm was formed from a continuous foaming polyurethane foam around the rotating shaft 17. As the polyurethane foam, a polyester-based polyurethane foam is preferred from the viewpoints of uniform cell size and good deformation resistance.

In this embodiment, the toner supply roller 6
Is 1.5 m from the developing sleeve 5 which is the member to be contacted.
m, and was rotated and driven in the same direction as the developing sleeve 5 at a peripheral speed of 158 mm / sec.

The toner supply roller 16 will be described in more detail.

One of the physical properties of the foamed elastic body is the air permeability. This ventilation rate indicates the degree of flow of the air flowing inside the foamed elastic body, and is defined as JIS as a standard of the measurement method.
L1096 is defined. The foamed elastic body is a material that allows air to flow more easily as the numerical value of the air permeability increases.According to the study of the present inventors, the foamed elastic body shows similar properties with respect to the mobility of the toner. Do you get it. In other words, the larger the numerical value of the gas flow rate of the foamed elastic body, the more quickly the toner can move inside the foamed elastic substance, and conversely, the smaller the numerical value of the gas flow rate, the slower the toner moves inside the foamed elastic body.

That is, several toner supply rollers 6 having different air flow rates and cell numbers of the foam roller 16 are prepared, and these are mounted on the developing device 4 and subjected to development to form 5,000 images. That is, printing was performed. Then, the fog, density, uniformity of image quality, and the like of the image at that time were observed and evaluated. Table 1 shows the results.

The air flow rate of the foam roller 16 was measured by a method in accordance with JISL1096 at the stage of foaming the slab foam before the polyurethane foam was formed into a roller. The number of cells is the number of foam cells per 25 mm in length.

[0043]

[Table 1]

From Table 1, it can be seen that image fogging can be prevented by setting the air flow rate of the foam roller 16 to 10 cc / cm ² / sec or more. This is because the air flow rate of the foam roller 16 increases, and
6 shows that the toner permeated and absorbed inside the roller 6 flows well inside the roller 16.

Regarding the image density and the uniformity of the image quality, first, in the case of the cell number of 20 cells / 25 mm, both the density and the image quality uniformity were deteriorated. This is because the open cell diameter is 1
mm or more, which is much larger than the average toner particle diameter of 6 μm. Therefore, when the toner supply roller 6 comes into contact with the developing sleeve 5, most of the toner conveyed by the toner supply roller 6 permeates into the foam roller 16. This is because the amount of toner supplied to the sleeve 5 is greatly reduced, and density cannot be obtained. Further, since the cell diameter is large, when the toner is supplied to the developing sleeve 5, the state substantially follows the cell diameter. Is supplied in the form of spots,
This is because it appears on the image.

When the number of cells was 55 to 100 cells / 25 mm, the density and the image quality uniformity were good in the range of the air flow rate of 10 to 40 cc / cm ² / sec. However, the ventilation volume is 5cc
In the case of / cm ² / sec, all the toner supply rollers are hardened, and the deterioration of the toner is accelerated, so that a sufficient triboelectric charge cannot be obtained. Was. When the air flow rate is 50 cc / cm ² / sec, the uniformity of the image quality is good due to the small cell diameter, but the toner supply amount is reduced, and the density is reduced.

The number of cells in urethane foam is 1
Those exceeding 00 pieces / 25 mm are difficult to manufacture,
Even if it could be manufactured, the air flow rate was less than 5 cc / sec, and the toner supply roller was similarly cured. Similarly, silicone rubber, NBR, and the like, which are advantageous for production of a high cell density, cannot similarly obtain a sufficient air permeability.

As described above, in this embodiment, the foam roller 16 which is the foamed elastic body of the toner supply roller 6 is
The number of cells was set to 55 cells / 25 mm or more and 100 cells / 25 mm or less, and the ventilation rate was set to 10 to 40 cc / cm ² / sec.
As a result, the fluidity of the toner inside the toner supply roller 6, that is, inside the foam roller 16, can be ensured, and the deterioration of the toner can be prevented. With good development, the density without fog and the uniformity of the image quality can be improved. Image can be obtained.

Embodiment 2 As described above, the phenomenon of fogging and the like caused by toner deterioration is related to the air flow rate of the foam roller 16 of the toner supply roller 6, and the measurement of the air flow rate is based on JISL.
In the method according to 109, it must be performed before the polyurethane foam is formed into the foam roller 16.

In this embodiment, in order to solve this inconvenience, the measuring device shown in FIG.
The air flow rate was measured as it was, that is, in the state of the toner supply roller 6. In this embodiment, the toner supply roller 6
Is a foam roller formed around the rotating shaft 17 by foaming and molding polyurethane inside the casting in which the rotating shaft 17 is inserted.

As shown in FIG. 3, the present measuring apparatus includes a cylindrical measuring chamber 18 having a jig 19 for holding the toner supply roller 6 in close contact therewith.
Is inserted into the chamber 18 by press-fitting from an insertion portion having an opening diameter d at the center of the jig 19. Measurement chamber 18
Is connected to a vacuum pump 22 via a flow meter 20 and a pressure gauge 21, and the inside of the chamber 18 is depressurized by suction of the vacuum pump 22. The pressure in the chamber 18 is monitored by a pressure gauge 21, and the suction of the vacuum pump 22 is adjusted so that the pressure becomes constant. The flow rate of the toner supply roller 6 is measured by the flow meter 20.

In the measuring apparatus shown in FIG. 3, since the measured value of the air flow rate varies depending on the opening diameter d and the thickness L of the jig 19, these factors are unified during the measurement. In this embodiment, since the outer diameter of the toner supply roller 6 is 16 mm,
The opening diameter d was fixed at 15 mm, and the thickness L was fixed at 25 mm. During the measurement, the suction of the vacuum pump 22 was adjusted so that the pressure gauge 21 indicated 1 kPa.

FIG. 4 shows the result of measuring the air flow of the toner supply roller of which the air flow amount of the foam roller 16 is known by the apparatus shown in FIG. Five toner supply rollers are prepared with only the foaming degree of the foam roller 16 being different, and the air flow rate of the foam roller is measured by a method conforming to JISL109 at a stage before the roller is molded.

As shown in FIG. 4, the measured value of the air flow rate by the apparatus shown in FIG. 3 has a substantially linear correspondence with the known air flow rate. It can be seen that the quantity is measurable.

Therefore, when measuring a toner supply roller whose air flow rate is unknown, a toner supply roller whose air flow rate is known is prepared by changing the air flow rate, and the toner supply roller whose air flow rate is known is measured in FIG. If the air flow rate is measured by the device and the measured air flow rate is used as a reference value, the measured air flow rate of the toner supply roller whose measurement target air flow rate is unknown is compared with the reference value, so that the air flow rate of the toner supply roller to be measured is approximately correct. You can know.

The measurement by the apparatus shown in FIG. 3 has an advantage that the distribution of air flow in the longitudinal direction of the toner supply roller 6 can be measured.
FIG. 5 shows the distribution of the air flow in the longitudinal direction when the toner supply roller of this embodiment is measured by the apparatus shown in FIG. As described above, the toner supply roller 6 is formed by foam-forming the foam roller 16 inside the casting. The ventilation volume is
As described above, it is obtained by conversion from the measured value. The ventilation amounts described later are all described using converted numerical values.

As shown in FIG. 5, the amount of air flow of the toner supply roller slightly changes in the longitudinal direction, and the air flows from the roller end surface near the roller end, so that a relatively large amount of air is measured. You. Incidentally, continuous printing operation was repeatedly performed using this toner supply roller, but there was no problem.

However, the toner supply roller 6 formed by casting foam molding has a problem in that air permeability and the like of a part of the foam roller 16 may be deteriorated due to mixing of air bubbles at the time of material input, adhesion of foreign matter to the inner surface of the casting, and inappropriate management of molding conditions. There is a possibility that it will change significantly. If a large bubble exists in the portion of the foam roller 16, the air flow in that portion is high and the contact pressure is low. When the toner supply roller 6 is incorporated into the developing device 4 in such a state, and the toner is supplied to the developing sleeve 5 and stripped off, and then used for development,
An image obtained by image formation has a low density corresponding to a portion of the foam roller 16 where large bubbles are present, or has poor uniformity such as a so-called ghost image due to a decrease in stripping performance. Or image quality.
If there is a part having a high density, the air permeability is reduced, and the deterioration of the toner is promoted.

In this embodiment, the apparatus shown in FIG. 3 is used to measure the unevenness of the air flow rate of each of the toner supply rollers 6 to prevent the use of a single article having a partially defective portion such as uneven foaming. .

In this embodiment, the average air flow rate of the cast-foamed toner supply roller 6 is 15, 20, 3
Two samples each having 0 cc / cm ² / sec were prepared (samples A to F), mounted on the developing device 4 and subjected to development, and 5,000 prints were made. Fog, density, and image quality uniformity And the like were observed and evaluated. Table 2 shows the results.
The number of cells of the foam roller 16 is all 80 cells / 25 mm.

[0061]

[Table 2]

As shown in Table 2, Samples A, C and E of the toner supply roller were able to form a good image without any problem. Sample B, Sample D and Sample F had poor image quality uniformity, and in particular, had image unevenness in the portion where the air flow rate changed significantly. In the case of sample B, fogging and low concentration occurred corresponding to the portion having the lowest ventilation rate.

The sample A from which the above-mentioned good image was obtained,
For the toner supply rollers C and E, the variation range of the ventilation amount is generally within a range of ± 25% of the average value of each, and the toner supply rollers of the other samples B, D, and F that have produced a defective image are: The variation range of the ventilation rate was approximately ± 50% of each average value.

As described above, in the present embodiment, the fluctuation range of the ventilation amount within one product of the toner supply roller 6 is -2 of the average value.
It was defined to be in the range of 5% to + 25%. As a result, even when the air flow rate varies within one toner supply roller 6, it is possible to prevent deterioration of the toner, to obtain an image having no fog, and excellent in both density and image quality uniformity.

In the second embodiment, the toner supply roller 6
Has been described in which the foam roller 16 is foam-molded inside the casting, but the present invention can be similarly applied to the case where the foam roller 16 is cut from a slab foamed foam body, and the same effect is exerted.

Example 3 The toner supply roller 6 of Example 2 is a non-defective product having no unevenness in the air flow rate due to the unevenness in the molding by measuring the unevenness in the air flow rate of the toner supply roller using the apparatus shown in FIG. The toner supply roller 6 of the present embodiment is obtained by measuring the molding unevenness of the toner supply roller with a simple device and selecting a non-defective product having no molding irregularity.

By measuring the contact pressure when the toner supply roller 6 is in contact with the developing sleeve 5 at a portion of the toner supply roller 6, a partial defect such as uneven foaming can be known. In other words, a defect is a phenomenon in which large air bubbles are present or the cells are not completely formed due to insufficient foaming, and the air permeability of such a defective part changes extremely, and the contact pressure also changes. It is a thing using.

FIG. 6 is an explanatory view showing a contact pressure measuring device used in this embodiment. The measuring device has a probe 23 rotatably supported by a support 24, and the probe 2
Reference numeral 3 denotes a short cylindrical body made of a metal such as SUS, which simulates the developing sleeve 5. A load sensor 25 is disposed on the back side of the support 24. The load when the probe 23 is brought into contact with the toner supply roller 6 is measured by the load sensor 25, and the measured load is displayed on the display unit 26.

In this embodiment, since the diameter of the developing sleeve 5 is approximately 16 mm, the diameter of the probe 23 is set to 16 mm so as to be substantially equal to this. The width of the probe 23 (the length of the cylindrical body in the axial direction) is 10 mm. Probe 2
The amount of toner 3 entering the toner supply roller 6 is
Of toner supply roller 6 into developing sleeve 5
A contact state approximately the same as that of 5 mm is obtained between the probe, 23 and the toner supply roller 6 by 1.5 mm.
And

When the toner supply roller 6 is rotated in the direction of arrow E in this contact state, the probe 23 is driven to rotate in the direction of arrow F, and the load on the toner supply roller 6 by the probe 23 is changed in the circumferential direction of the toner supply roller 6. Measured along.
That is, the load on the probe 23, in other words, the load of the toner supply roller 6 on the developing sleeve 5, that is, the contact pressure is measured in the circumferential direction of the toner supply roller 6. In this embodiment,
The rotation speed of the elastic roller 5 was set to 30 rpm. After measuring the toner supply roller 6 for one rotation in this way, the position of the probe 23 is moved by a predetermined width in the longitudinal direction of the toner supply roller 6 and the same measurement is performed. This is repeated until the entire area in the longitudinal direction is measured. Was.

FIG. 7 shows the circumferential distribution of the contact pressure of the toner supply roller 6 whose contact pressure was measured by the measuring device of FIG. The contact pressure is a load value per unit length in the longitudinal direction of the toner supply roller 6, that is, a linear pressure (gf / cm). In the figure, curve a
In the case where there is no defect in the circumferential direction of the foam roller 16 of the toner supply roller 6, there is no change in the contact pressure in the circumferential direction of the toner supply roller 6, and a substantially uniform contact pressure is obtained. Curve b is the form roller 1 of the toner supply roller 6
In the case where a large bubble is partially present in the circumferential direction in FIG. 6, the contact pressure is extremely reduced in the portion where the bubble is present. Curve c represents the form roller 16 of the toner supply roller 6.
In the case where there is a defect such as defective foaming in which the amount of ventilation is significantly reduced in the circumferential direction, the contact pressure is extremely increased in a portion where the defect such as defective foaming exists.

When three kinds of toner supply rollers 6 having the contact pressure characteristics of the curves a, b and c were mounted on the developing device 4 and subjected to development, and 5000 prints were performed.
The toner supply roller having the contact pressure characteristic curve a showed no problem, and a good image was formed up to the end. The toner supply roller of curve b has uneven density in the image almost corresponding to the contact pressure decreasing portion, and the toner supply roller of curve c has uneven density in the image almost corresponding to the increasing contact pressure portion. .

As shown in Table 3, six kinds of toner supply rollers (samples G to L) were prepared to check the appropriate value of the circumferential fluctuation width of the contact pressure of the toner supply roller 6. Was mounted on the developing device 4 and subjected to development, and 5,000 prints were performed. Then, the image evaluation was performed by paying particular attention to the fog, the density, and the uniformity of the image quality of the image. The results are also shown in Table 3.

In Table 3, Samples G to I of the toner supply roller have 80 cells / 25 mm and a ventilation rate of 20.
cc / cm ² / sec, and samples J to L have 5 cells.
5 pieces / 25 mm, and the ventilation rate was 30 cc / cm ² / sec.

[0075]

[Table 3]

As shown in Table 3, Samples G and J of the toner supply roller did not cause any problem, and a good image could be formed to the end. In sample H, density unevenness and light density were generated at the rotation position of the toner supply roller at the longitudinal position where the contact pressure showed the minimum value. Sample K was similar. In sample I, band-like fogging occurred near the position in the longitudinal direction where the contact pressure had the maximum value, and the density was also reduced. This was the same for sample L. After the evaluation,
When the toner supply roller was removed from the developing device 4 and observed, only the portions of the samples H, I, K, and L that caused the image defect were cured. The above-mentioned band-like fog and low density are probably caused by the toner being rubbed and deteriorated in the cured portion and scattered in the circumferential direction of the roller with the rotation of the toner supply roller.

The fluctuation range in the circumferential direction of the contact pressure of the samples G and J is within a range of about ± 15% of the average value, and the samples H, I, K, and The fluctuation width of the contact pressure of L in the circumferential direction was widened to about ± 30% of the average value.

As described above, in this embodiment, the developing sleeve 5
The variation width in the circumferential direction of the contact pressure of the toner supply roller 6 to the toner supply roller 6 is defined to be within a range of -15% to + 15% of the average value. Accordingly, even when the contact pressure of the toner supply roller 6 fluctuates in the circumferential direction, it is possible to prevent deterioration of the toner, to obtain an image having no fog, and excellent in both density and image quality uniformity.

Example 4 In Example 3 described above, the unevenness in the circumferential direction of the contact pressure of the toner supply roller 6 with the developing sleeve 5 was measured using the measuring device shown in FIG. In the fourth embodiment, non-defective products having no contact unevenness were measured, and non-defective products having no molding non-uniformity in the longitudinal direction were selected.

FIG. 8 shows the longitudinal distribution of the contact pressure of the toner supply roller 6 whose contact pressure was measured by the measuring device of FIG. The measured value is obtained by measuring the contact pressure in the circumferential direction at each measurement position in the longitudinal direction and averaging the measured values in the circumferential direction. In the figure, a curve d represents the form roller 16 of the toner supply roller 6.
In the case where there is no defect in the longitudinal direction, the contact pressure hardly changes in the longitudinal direction of the toner supply roller 6, and a substantially uniform contact pressure is obtained. A curve e indicates a case where a defect due to defective foaming or the like is present on the foam roller 16 of the toner supply roller 6 at one end in the longitudinal direction, and the contact pressure is greatly increased at the end where the defect exists. This is because when the foam roller 16 is formed by foaming, the polyurethane injected into the vertical casting is foamed from below, but at this time, the weight of the upper portion is added to the bottom portion of the polyurethane. When the foaming at the bottom does not proceed sufficiently, the foam cells become smaller, or the skeleton of the formed foam cells is crushed, so that the air flow rate at the bottom of the obtained foam roller 16, that is, at one end, decreases, and The contact pressure also increases.

In order to check the appropriate value of the variation width in the longitudinal direction of the contact pressure of the toner supply roller 6, a slab-foamed urethane foam material was used. Four kinds of toner supply rollers of a sample M including a bottom portion, a sample N including a portion near a bottom portion, a sample O including a portion near the top portion, and a sample P including a top portion are prepared and mounted on the developing device 4 for development. Offer, 500
Zero prints were made. Then, image evaluation was performed with particular attention to fog, density, and image quality uniformity of the image. The results are also shown in Table 4. FIG. 9 shows the longitudinal distribution of the contact pressure measured for the samples M to P by the apparatus shown in FIG.

The raw urethane foam used in this embodiment has a cell number of 80 cells / 25 m at the center in the height direction.
m, the air flow rate is 20 cc / cm ² / sec, and the average value of the contact pressure at the position corresponding to the center in the height direction of the raw material when processed into the toner supply roller is 40 fg / cm. It is called the median for convenience. The median is a value that serves as a guide for judging a portion where the raw material can be used, and an appropriate range and the like will be described later.

[0083]

[Table 4]

As shown in Table 4, samples N and O of the toner supply roller did not cause any problem, and a good image was formed to the end. In the sample M, band-like fogging occurred in the center in the longitudinal direction from the vicinity of the position where the contact pressure showed the minimum value, and the density was also reduced. After the evaluation, the developing device 4
When the toner supply roller was removed from the sample M and observed, it was found that only the portion of the sample M where an image defect occurred was cured. In the sample P, density unevenness and density thinness occurred from near the position where the contact pressure showed the minimum value to near the center in the longitudinal direction. This is because the upper part of the raw urethane foam is in a rough foamed state, and the size of the foamed cell is also increased.

The variation width in the longitudinal direction of the contact pressure of the samples N and O is within a range of about ± 15% of the median value. The longitudinal fluctuation width of the contact pressure is approximately ± 15% of the same median value as above
No defect image was generated in the portion within the range of.

As described above, in this embodiment, the developing sleeve 5
The variation width in the longitudinal direction of the contact pressure of the toner supply roller 6 to the toner supply roller 6 is defined to be within a range of -15% to + 15% of the average value. Thereby, even when the contact pressure of the toner supply roller 6 fluctuates in the longitudinal direction, deterioration of the toner is prevented, and
It is possible to obtain an image free from fog and excellent in both density and image quality uniformity.

[0087]

As described above, according to the present invention,
In the toner supply roller made of a foamed elastic material, the number of cells of the foam is set to 55 cells / 25 cm to 100 cells / 25 cm, and the air flow rate is set to 10 to 4 cc / cm ² / sec. It is possible to stably obtain a high-quality image with sufficient density and high uniformity of image quality for a long time without fog due to good development.
Further, the variation width of the ventilation amount of the toner supply roller is set within a range of ± 25% with respect to a predetermined value, or the contact pressure per unit length in the longitudinal direction of the toner supply roller with respect to the developing sleeve is determined in the circumferential direction of the toner supply roller. Change range ± 15 of the specified value
%, Or the fluctuation width in the longitudinal direction of the toner supply roller is within a range of ± 15% of a predetermined value, whereby image quality can be further stabilized.

[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 a toner supply roller installed in the developing device of FIG.

FIG. 3 is a schematic view showing a measuring device used for measuring the air flow rate of the toner supply roller in the present invention.

FIG. 4 is a diagram showing a correlation between a ventilation amount of a toner supply roller and a measured value of a ventilation amount by the apparatus of FIG. 3;

5 is a view showing a longitudinal distribution of the amount of air flow of the toner supply roller measured by the apparatus of FIG. 3 in another embodiment of the present invention.

FIG. 6 is a schematic diagram showing a measuring device used to measure the contact pressure of the toner supply roller with the developing sleeve in the present invention.

7 is a diagram showing a circumferential distribution of a contact pressure of a toner supply roller measured by the apparatus of FIG. 6 in still another embodiment of the present invention.

8 is a view showing a difference in a longitudinal distribution of a contact pressure of a toner supply roller measured by the apparatus of FIG. 6 in still another embodiment of the present embodiment.

9 is a diagram showing a longitudinal distribution of a contact pressure of a toner supply roller measured by the apparatus of FIG. 6 in the embodiment of FIG. 8;

[Explanation of symbols]

 Reference Signs List 4 developing device 5 developing sleeve 7 elastic blade 6 toner supply roller 8 non-magnetic toner 16 foam roller 17 rotating shaft

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunori Hashimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masuro Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Non Corporation

Claims (5)

[Claims] 1. A developer supply member for supporting a one-component developer on the developer carrier by rotating in contact with the developer carrier of a developing device, wherein a foamed elastic material is provided around a rotation shaft. In the developer supply member provided with, the foamed elastic body has a foam cell number of 55 cells / 25 mm or more and 100
Pieces / 25mm or less, ventilation rate is 10 to 40 cc / cm ² /
A developer supply member, wherein the developer supply time is seconds. 2. The developer supply member according to claim 1, wherein the variation width of the ventilation amount of the foamed elastic body is within a range of ± 25% of a predetermined value. 3. A developer supply member for supporting a one-component developer on the developer carrier by rotating while being in contact with the developer carrier of a developing device, wherein a foamed elastic material is provided around a rotation shaft. A contact pressure per unit length in the longitudinal direction of the developer supply member with respect to the developer carrying member, and a variation width of the contact pressure in the circumferential direction of the developer supply member. Is within a range of ± 15% of a predetermined value. 4. A developer supply member for causing a one-component developer to be carried on the developer carrier by rotating in contact with the developer carrier of a developing device, wherein a foamed elastic material is provided around a rotation shaft. In the developer supply member provided with, the contact pressure per unit length in the longitudinal direction of the developer supply member to the developer carrier, the average value of the contact pressure in the circumferential direction of the developer supply member Wherein the variation width in the longitudinal direction of the developer supply member is within a range of ± 15% of a predetermined value. 5. A one-component developer which carries a one-component developer and conveys the developer to a developing unit opposed to the image carrier, and which rotates while being in contact with the developer carrier. And a developer supply member for supplying and supporting the developer carrier, wherein the developer supply member is provided with a foamed elastic body around a rotation shaft, the developer supply member, A developing device, comprising the developer supply member according to claim 1.