JPH07191544A - Developer carrying member and developing device - Google Patents

Abstract

PURPOSE:To obtain good images free from sleeve ghosts by removing and lessening the mirroring power of a fine powder developer charged up near the surface of a developer carrying member. CONSTITUTION:A developing sleeve 114 is formed by coating the front surface of an aluminum base body 101 with a conductive resin layer 102 contg. conductive potassium titanate whiskers 103. These whiskers 103 have an average fiber diameter of 0.3 to 0.77mum and an average fiber length of 10 to 20mum. This resin layer 102 has volume resistivity of 10<-6> to 10<2>OMEGA.cm and a film thickness of 0.5 to 30mum. Then, the whiskers 103 of the resin layer 102 act as leak site and, therefore, the reflection power of the fine powder toner charged up on the sleeve 114 is weakened and the purpose is achieved.

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 on an image carrier of an electrophotographic photoreceptor or an electrostatic recording dielectric.

[0002]

2. Description of the Related Art Conventionally, a one-component developer is used, and a developer-carrying member carrying the one-component developer is made to face a surface of an image bearing member with a required minute gap, and a developer flying in the gap. There is known a jumping developing method for developing by using (for example, Japanese Patent Publication No. 41-9476). A high frequency pulse bias (frequency 10 kHz to 3000 k
There is also known a developing technique in which a developer is attached to the image portion of the image carrier but not to the non-image portion by applying (for example, Hz) (for example, US Pat. No. 3,890,929).
No. 3,386,574, and No. 38934318, etc.).

Further, a two-component developer containing a toner and a carrier is used, and the two-component developer is indiscriminately contacted with the image part and the non-image part of the image carrier, and at the same time, the developer carrier and the image carrier are carried out. A developing technique is also known in which a low-frequency alternating electric field is applied between the two to apply the developer substantially only to the image area and to prevent the developer from adhering to the non-image area (for example, to develop). JP-A-55-3060).

FIG. 10 is a schematic structural view showing an image forming apparatus provided with a conventional developing device. This developing device is an example of a conventional developing device, and is configured to apply an alternating electric field to a developing region which is a gap where a developer carrier and an image carrier face each other.

As shown in FIG. 10, the developing device 10 is installed so as to face a drum-shaped electrophotographic photosensitive member which is an image bearing member of the image forming apparatus and rotates in the direction of the arrow, that is, the photosensitive drum 1. An electrostatic latent image is formed on the surface 1 by a known electrostatic latent image forming unit 20 including a charger and an exposing unit. As the exposing means, a means for projecting an optical image of a document, an optical system for scanning a laser beam modulated by a recorded image signal, or the like is adopted, and the latent image formed on the photosensitive drum 1 is
It is developed by the developing device 10 to form a toner image.

The obtained toner image is transferred onto a transfer material such as paper by a known transfer means 30 including a transfer charger.
The transfer material onto which the toner image has been transferred is separated from the photosensitive drum 1 and sent to a known fixing means, where the toner image is fixed on the transfer material.

The toner remaining on the photosensitive drum 1 after the transfer is removed by a known cleaning means 40 including a cleaning blade and the like.

The developing device 10 contains an insulating one-component developer 11 containing no carrier particles in a developing container 12. The developer 11 is mainly composed of an insulating magnetic toner, and preferably, silica fine powder is slightly added externally. The fine silica powder is externally added for the purpose of controlling the triboelectric charge of the toner so as to increase the image density and obtain an image with less roughness. For example, it is known to externally add vapor phase silica (dry silica) and / or wet process silica (wet silica) to the toner.

For example, with respect to a negative polarity toner containing 60 parts by weight of magnetite in styrene-acryl, dry silica (for example, 100 m ² of vapor-phase process silica and 10 parts by weight of HMDS per 100 m ^{2 of} silica). The developer to which external additives (added in a proportion and subjected to heat treatment) are externally added is suitable for reversal development of a negative electrostatic latent image.

A one-component developer, that is, a magnetic toner 11 is stored in a container 1 by a non-magnetic developing sleeve 14 made of aluminum, stainless steel or the like, which is a developer carrier and rotates in the direction of the arrow.
Development area 1 which is taken out from the photosensitive drum 1 and faces the photosensitive drum 1.
3 is transported. In the developing area 13, the photosensitive drum 1 and the developing sleeve 14 face each other with a minimum gap of 50 to 500 μm. Then, in the developing area 13, a developer is applied to the electrostatic latent image on the photosensitive drum 1 to develop the electrostatic latent image.

The developing sleeve 1 conveyed to the developing area 13.
The thickness of the toner layer 11 ′ on the surface 4 is regulated by the blade 16. The blade 16 is made of a magnetic material such as iron, and is stationary in the developing sleeve 14.
The magnetic pole N1 of No. 5 and the developing sleeve 14 are opposed to each other. Therefore, magnetic force lines from the magnetic pole N1 are concentrated on the blade 16, and a strong magnetic curtain is formed between the blade 16 and the developing sleeve 14. Due to this magnetic curtain, a toner layer 11 ′ thinner than the gap between the blade 16 and the developing sleeve 14 is formed on the developing sleeve 14.

The gap between the blade 16 and the developing sleeve 14 is such that the thickness of the toner layer 11a can be made smaller than the minimum gap between the developing sleeve 14 and the photosensitive drum 1, that is, the gap between them in the developing area 13. Is set to.

As described above, in the developing device shown in FIG. 10, so-called non-contact development is performed. That is, since the thickness of the toner layer 11 ′ conveyed to the developing area 13 is smaller than the minimum gap between the developing sleeve 14 and the photosensitive drum 1, the toner 11 flies from the developing sleeve 14 in the air gap and reaches the photosensitive drum 1. To do. Then, in order to improve the developing efficiency at that time, and to form a developed image having high density, sharpness, and suppressed fog, a developing bias voltage including an alternating component is applied to the developing sleeve 14 from a constant voltage controlled bias power source 18. To be done.

As described above, the developing bias is preferably a DC voltage on which an alternating voltage is superimposed. The frequency of the alternating voltage is 1 to 2 kHz, the peak-to-peak voltage (difference between the maximum value and the minimum value) is preferably about 1.1 to 1.8 kV, and the waveform is rectangular wave, sine wave, triangular wave, etc. To be done.

For example, when a latent image having a dark portion potential of −700 V and a light portion potential of −100 V is reversely developed with toner negatively charged, a developing bias has a DC component of −500 V and an alternating component has a peak-to-peak voltage. Of 1.6 kV and a frequency of 1.8 kHz can be used as a developing bias voltage of a rectangular wave.

Due to the developing bias, the electric field in the direction of transferring the toner 11 from the developing sleeve 14 to the photosensitive drum 1 and the electric field in the direction of reverse transferring from the photosensitive drum 1 to the developing sleeve 14 act alternately on the toner 11. As a result, a good developed image can be obtained.

The reversal development is a developing method in which a latent image of a latent image is visualized by adhering toner charged with the same polarity as that of the latent image to the bright portion potential region. On the other hand, a developing method in which toner charged with a polarity opposite to that of the latent image is made to adhere to a dark potential region of the latent image to make it visible is called normal development.

The toner 11 is mainly the developing sleeve 14.
It is charged to the polarity that develops the electrostatic latent image by friction with.
The toner 11 contains, for example, 60% by weight of magnetite and 1% by weight of a metal complex salt of a monoazo dye as a negative charge control agent in a binder resin containing styrene-acrylic copolymer as a main component, and has a volume resistivity of about An insulating magnetic toner of 10 ¹³ Ωcm is used as a base, and 0.4% by weight of silica fine particles that have been hydrophobized to enhance the fluidity is externally added to the toner weight. Such toner is negatively charged by friction with the developing sleeve 14 described above.

The magnetic pole S1 of the magnet roller 15 forms a magnetic field in the developing area 13 to prevent fog and contribute to clear development of a line image. The magnetic poles N2 and S2 contribute to the toner conveyance.

[0020]

However, in a developer in which silica having a strong negative property is externally added to a negative toner, a sleeve ghost, which is a history of a print pattern, is generated on a developing sleeve, and this also appears on a printed image. As shown in FIG. 11, the sleeve ghost generated in the case of the developer in which negative silica is externally added to the negative toner becomes a positive ghost. That is, since the non-printed portion (white background) continues, only light development is performed even if printing is performed (a).
Density unevenness occurs between the portion and the portion (b) where dark development is performed because printing is continued.

According to experiments and consideration by the present inventors, this ghost formation mechanism is deeply related to the layer of the differential toner (particle size 5 to 6 μm or less) formed on the developing sleeve. That is, there is a clear difference in the particle size distribution of the lowermost layer of the toner layer on the developing sleeve between the toner consumption portion and the toner non-consumption portion, and the fine powder layer is formed in the toner lowermost layer of the non-consumption portion. . Since the fine powder toner has a large surface area per volume, the triboelectric charge amount per mass is large as compared with the toner having a large particle diameter, and the electrostatic force is strongly restrained to the developing sleeve by the self-reflective power. For this reason, the toner on the portion where the fine powder layer is formed is not sufficiently triboelectrically charged with the surface of the developing sleeve, so that the developing ability is deteriorated and appears as a sleeve ghost on the image.

The above-mentioned sleeve ghost is a phenomenon caused by the fact that the charging of the toner largely depends on the frictional charging with the developing sleeve together with the formation of the fine powder layer. Therefore, in order to solve the sleeve ghost, it is necessary to remove or reduce the mirroring force acting between the charged-up fine powder toner and the developing sleeve near the surface of the developing sleeve by some method.

An object of the present invention is to remove or reduce the mirroring force of the charged fine powder developer in the vicinity of the surface of the developer carrying member, so that a good image without sleeve ghost can be obtained. The object is to provide a body and a developing device.

[0024]

The above object can be achieved by a developer carrier and a developing device according to the present invention. In summary, the present invention relates to a developer carrying member carrying a developer and transporting the developer to a developing area facing the image carrying member, wherein the developer carrying member is a conductive potassium titanate whisker on the surface of a conductive substrate. And a whisker having an average fiber diameter of 0.3 to 0.7 μm and 1
It has an average fiber length of 0 to 20 μm, and the resin layer has a thickness of 10
Volume resistivity of ⁻⁶ to 10 ² Ω · cm and 0.5 to 30 μm
The developer carrying member has a film thickness of

Further, the present invention is a developing device in which a developer is carried on a developer carrying body and regulated by a regulating member, and the developer carrying body conveys the developer to a current area facing the image carrying body, The developer carrying member is obtained by coating a conductive resin layer containing a conductive potassium titanate whisker on the surface of a conductive substrate, and the whisker has a thickness of 0.
The resin layer has an average fiber diameter of 3 to 0.7 μm and an average fiber length of 10 to ²⁰ μm, and the resin layer is 10 ⁻⁶ to 10 ² Ω · cm.
And a film thickness of 0.5 to 30 μm.

According to the present invention, in the conductive resin layer,
Furthermore, carbon black and / or graphite can be contained. Further, the surface of the developer carrying member can be lightly polished after being coated with the conductive resin layer. The developer is preferably a one-component developer including a magnetic toner or a non-magnetic toner. A two-component developer composed of a non-magnetic toner and a magnetic carrier can also be used. The toner preferably has an average particle size of 9 μm or less. The toner may have a spherical shape. Further, the regulating member is an elastic member that is in contact with the developer carrying member.

[0027]

【Example】

Embodiment 1 FIG. 1 is a configuration diagram showing an embodiment of a developing device of the present invention, FIG. 2 is a perspective view showing a developing sleeve arranged in the developing device of FIG. 1, and FIG. 3 is a surface of the developing sleeve. It is sectional drawing which expands and shows the vicinity. In this embodiment, as the developer carrying member,
A major feature is the use of the developing sleeve 114 having a conductive resin layer containing conductive potassium titanate whiskers formed on the surface. Other configurations of the developing device of this embodiment are basically the same as those of the conventional developing device shown in FIG.
1, the same reference numerals as those shown in FIG. 10 denote the same members.

In the present embodiment, the developing sleeve 114
Is a conductive resin layer 10 containing conductive potassium titanate whiskers (general formula of potassium titanate: K ₂ O.nTiO ₂ ) on the surface of a non-magnetic aluminum substrate 101.
2 is provided. The base body 101 has an outer diameter of 16 mm,
It has a thickness of 0.8 mm and a length of 220 mm.

According to this embodiment, as shown in FIG. 4, the average fiber diameter D is 0.3 to 0.7 μm and the average fiber length L is 10.
Conductive potassium titanate whiskers (trade name DENTOL, manufactured by Otsuka Chemical Co., Ltd.) obtained by conducting the surface 105 of a potassium titanate whisker (trade name: Tismo, manufactured by Otsuka Chemical Co., Ltd.) 104 having a thickness of 20 μm. 103 was dispersed in a thermosetting phenolic resin, and was spray-coated on the substrate 101 to a coating film thickness of about 7 mm.
The conductive resin layer 102 was formed on the surface of the substrate 101 by heat curing in a drying oven at 30 ° C. for about 30 minutes.

The content of conductive potassium titanate whiskers in the conductive resin layer 102 is preferably 10 to 40 wt%,
More preferably 25Wt～40wt%, by this amount, the volume resistivity of the conductive resin layer 102 10 ² Ω · cm or less, preferably to less than 10 ⁰ Ω · cm.

The surface roughness of the developing sleeve 114 having the conductive resin layer 102 can be controlled by the coating conditions and the like. In this embodiment, the surface roughness of the developing sleeve 114 is J
Center line average roughness Ra described in ISB0601 is about 2.0.
μm.

As shown in FIG. 3, the resin layer 102 is most characterized in that at least a part of the conductive potassium titanate whiskers 103 partially projects from the surface thereof. In other words, the surface of the developing sleeve 114 after the coating of the conductive resin layer 102 is roughened to Ra≈2.0 μm, but microscopically, the conductive potassium titanate whiskers 103 are further projected. It has a surface condition.

According to this, since the conductive potassium titanate whiskers 103 are needle-like crystals as shown in FIG. 4, the whiskers have an effect of acting as leak sites, and the charged up fine powder on the surface of the developing sleeve is obtained. It is expected that the effect of weakening the mirroring power of the toner can be expected, thereby suppressing the sleeve ghost that has conventionally occurred.

An image forming experiment example performed in this embodiment will be described. The above developing sleeve 114 was incorporated into the developing device 10 shown in FIG. 1 and used for development, and a large number of images were formed under a low temperature and low humidity environment of 15 ° C. and 10% RH where sleeve ghosts are likely to occur. . Developing sleeve 11
In the conductive resin layer 102 of No. 4, the content of conductive potassium titanate whiskers was set to 25 wt%.

The developing sleeve 114 has a bias power source 18
Thus, a developing bias of VDC = -500V, VAC (peak-to-peak voltage Vpp) = 1600V, and a frequency of 1800 Hz was applied. The SD gap between the developing sleeve 114 and the photosensitive drum 1 was about 300 μm. The magnetic toner 11 of the one-component developer used had a volume average particle diameter of 11 μm.

For comparison, an aluminum developing sleeve which had been subjected to a conventional sandblasting treatment (using Showa Denko's Morundum # 400) was used, and the same procedure as above was performed. The results are shown in Table 1 as Example 1 and Conventional Example 1.

[0037]

[Table 1]

As shown in Table 1, according to the present embodiment, the effect of reducing the sleeve ghost is remarkable as compared with the conventional example, and the high density is maintained even when a large number of images are formed.

In the above, the conductive potassium titanate whiskers (Dentol manufactured by Otsuka Chemical Co., Ltd.) were used as the conductive potassium titanate whiskers, but the present invention is not limited to this, and the conductive potassium titanate whiskers can be used. It is also possible to use whiskers in which potassium titanate whiskers are coated with various metal materials, specifically, whiskers coated with silver (Superdentol manufactured by Otsuka Chemical), whiskers coated with copper or nickel (Riovale manufactured by Otsuka Chemical).

The volume resistivity of the above-mentioned super dentol is 1 × 10 ⁻⁴ Ω · cm, and the volume resistivity of Riobert is 5 × 10 ⁻⁴ Ω · cm, both of which have very low volume resistivity. When used, a conductive resin layer having a lower volume resistivity can be formed, and a developing sleeve having a further excellent sleeve ghost reduction effect can be manufactured.

Although the phenol resin is used as the resin of the conductive resin layer 102, a resin such as nylon may be used. Also EP
An elastic material such as DM rubber may be used and is similarly effective. Therefore, in the present invention, the resin of the conductive resin layer is EPD.
Includes elastic materials such as M rubber.

Embodiment 2 In this embodiment, the developing sleeve 114 is the same as in Embodiment 1.
The conductive resin layer 102 on the surface is characterized by containing carbon black in addition to the conductive potassium titanate whiskers (Dentol manufactured by Otsuka Chemical). The other configurations of this embodiment are similar to those of the first embodiment.

The conductive potassium titanate whiskers of the conductive resin layer 102 can be used in a content range of 10 to 40 wt% as described above, and the above carbon black can be used in the conductive resin layer 102. Volume resistivity is 10 ²
It can be used with a content in the range of Ω · cm or less.

In this example, as an example, the contents of carbon black and conductive potassium titanate whiskers and the contents of phenol resin were set as follows. The developing sleeve 114 was manufactured in the same manner as in the first embodiment.

Carbon black 17 wt% Conductive potassium titanate whisker 17 wt% Phenolic resin 66 wt%

An image forming experiment similar to that in Example 1 was conducted using the above developing sleeve. The results in this embodiment are shown in Table 2 as Example 2 and Conventional Example 2 together with the results when the developing sleeve of Conventional Example 1 was used.

[0047]

[Table 2]

As shown in Table 2, in this embodiment, the effect of reducing the sleeve ghost is remarkable as compared with the conventional example, and the density is stable even when a large number of images are formed.

Third Embodiment In this embodiment, the developing sleeve 114 is the same as the first embodiment.
It is characterized in that the conductive resin layer 102 on the surface contains graphite in addition to the conductive potassium titanate whisker (Dentol manufactured by Otsuka Chemical).

The above graphite content is such that the conductive resin layer 102 contains conductive potassium titanate whiskers 10-4.
It is possible to add graphite in an amount of 0 wt% and select it in such a range that the volume resistivity is 10 ² Ω · cm or less.

In this example, as an example, the contents of graphite and conductive potassium titanate whiskers and the contents of phenol resin were set as follows. The developing sleeve 114 was manufactured in the same manner as in the first embodiment.

Graphite 17 wt% Conductive potassium titanate whisker 17 wt% Phenolic resin 66 wt%

An image forming experiment similar to that in Example 1 was conducted using the above developing sleeve. The results in this embodiment are shown in Table 3 as Example 3 and Conventional Example 3 together with the results when the developing sleeve of Conventional Example 1 was used.

[0054]

[Table 3]

As shown in Table 3, according to the present embodiment, the effect of reducing the sleeve ghost was great, and the density stability was good when a large number of images were formed. In this embodiment, since the conductive resin layer 102 contains graphite, the stability of the concentration is higher than that in the second embodiment.

Fourth Embodiment In this embodiment, the developing sleeve 114 in the first embodiment is used.
It is a feature that the conductive resin layer 102 on the surface contains both graphite and carbon black in addition to the conductive potassium titanate whisker (Dentol manufactured by Otsuka Chemical).

The total content of graphite and carbon black is 10% by weight to 40% by weight of conductive potassium titanate whiskers in the conductive resin layer 102, and the volume resistivity thereof is 10%. It can be selected within a range of ² Ω · cm or less.

In this case, in order to secure the mechanical strength of the resin layer 102, the total amount of graphite and carbon black is preferably 2 parts by weight or less with respect to 1 part by weight of the resin. Further, in order to enhance the mechanical lubricity of the surface of the developing sleeve 114, it is desirable that the ratio of graphite be higher than that of carbon black.

In this example, as an example, the contents of conductive potassium titanate whiskers, graphite and carbon black, and the contents of phenol resin were set as follows. The method for forming the developing sleeve 114 is the first embodiment.
Same as.

Conductive Potassium Titanate Whisker 10 wt% Graphite 20 wt% Carbon Black 5 wt% Phenolic Resin 65 wt%

An image forming experiment similar to that in Example 1 was conducted using the above developing sleeve. The results of this embodiment are shown in Table 4 as Example 4 and Conventional Example 4 together with the results obtained when the developing sleeve of Conventional Example 1 was used.

[0062]

[Table 4]

As shown in Table 4, according to the present embodiment, the effect of reducing the sleeve ghost was remarkable, and the density stability in forming a large number of images was good. Further, in this embodiment, since the effect of increasing the mechanical lubricity of the developing sleeve surface and the effect of reducing the charge-up are particularly high, the effect of preventing the toner component from adhering to the developing sleeve surface is 5
It can be seen that characteristic results that can be sufficiently maintained even with about 0000 sheets are obtained.

Example 5 In this example, a non-magnetic toner which is a non-magnetic one-component developer is used as the developer. FIG. 5 is a configuration diagram showing the developing device of this embodiment.

The developing device 10 of the present embodiment includes a developing container 12
1 is different from the developing device in FIG. 1 in that the coating roller 50 for the non-magnetic toner 311 is provided therein and the elastic blade 36 that contacts the developing sleeve 114 is used as a regulating member in terms of the mechanical structure of the device. The other configurations of the developing device of this embodiment are basically the same as those of the developing device of FIG. 1, and the same reference numerals as those in FIG. 5 denote the same members in FIG.

The coating roller 50 is an elastic roller made of a foaming elastic material, and elastically contacts the developing sleeve 114 and rotates in the direction of the arrow to develop the non-magnetic toner 311 contained in the developing container 12. It is carried to the sleeve 114 and carried. The elastic blade 36 is made of an elastic material such as urethane, and is in contact with the developing sleeve 114 in the direction opposite to the rotating direction. The toner 311 carried on the developing sleeve 114 is conveyed toward the developing area facing the photosensitive drum 1 by the rotation of the developing sleeve 114, and the toner thin layer 311 ′ is conveyed by the elastic blade 36 during the conveyance.
And is subjected to development in the development area.

In this embodiment, such a non-magnetic toner 3 is used.
For 11 ', the same developing sleeve 114 as that shown in Example 1 was used.

An image forming experiment similar to that in Example 1 was conducted using the above developing sleeve. The results in this embodiment are shown in Table 5 as Example 5 and Conventional Example 5 together with the results when the developing sleeve of Conventional Example 1 was used.

[0069]

[Table 5]

As shown in Table 5, according to the developing sleeve of the present invention, even when the non-magnetic toner of the one-component developer is used, the sleeve ghost can be prevented and the density stability at the time of forming a large number of images can be improved. It turns out that it is effective.

In addition to the above, on the conductive resin layer 102 on the surface of the developing sleeve 114, one of carbon black and graphite other than the conductive potassium titanate whiskers was used as in the case of Examples 2 to 4. One type or two types were tried, but it was similarly effective for the non-magnetic toner.

Example 6 In this example, the magnetic toner 11 of the one-component magnetic developer used in Example 1 had a volume average particle size of 9 μm. The other configurations of this embodiment are similar to those of the first embodiment.

Magnetic toner 1 having the above volume average particle diameter of 9 μm
On the other hand, the same image forming experiment as in Example 1 was conducted using the developing sleeve of Example 1 for No. 1. The results in this embodiment are shown in Table 6 as Example 6 and Conventional Example 6 together with the results when the developing sleeve of Conventional Example 1 was used.

[0074]

[Table 6]

As shown in Table 6, according to the present embodiment, the effect of reducing the sleeve ghost is remarkable with respect to the magnetic toner having the volume average particle diameter of 9 μm, and the density stability in forming a large number of images is improved. An improvement was obtained.

Further, a trial was carried out by using a magnetic toner of 6.5 μm, and the same result as shown in Table 6 was obtained. From this, it is understood that the present invention is also effective for the magnetic toner having a volume average particle diameter of 6.5 μm or less.

Example 7 This example is characterized in that a spherical toner was used as the magnetic toner 11 in Example 1, and the other structures were the same as in Example 1.

The above spherical magnetic toner was produced by a polymerization method, and in this embodiment, a volume average particle diameter of 8 μm was used. The spherical toner is characterized in that the specific charge amount of the toner increases particularly as the particle size decreases, so that the toner is difficult to be conveyed mechanically.

In the present invention, the conductive resin layer 102 on the surface of the developing sleeve 114 has an average particle size of 0.3 to 0.7 μm.
A conductive potassium titanate whisker (Dentol manufactured by Otsuka Chemical) having an average fiber length of 10 to 20 μm is blended. As described above, a part of the whiskers protrudes from the surface of the resin layer 102 to form so-called innumerable leaks on the surface, so that the charge-up of the toner can be prevented.

However, in addition to that, the fine protrusions on the surface of the resin layer 102 due to the protrusion of the whiskers also have an effect of effectively acting on the mechanical transport of the toner. Therefore, even the spherical toner used in this embodiment can be mechanically sufficiently conveyed by the developing sleeve 114. This toner carrying property is particularly effective when the toner layer on the developing sleeve 114 is a thin layer (for example, 1 to 2 layers). This is because the projections on the surface of the resin layer 102 due to the above-mentioned whisker projections are present in an innumerable and uniform manner, so that each toner in the thin toner layer is reliably transported.

In this embodiment, with respect to the above-mentioned spherical magnetic toner 11, the developing sleeve 114 is basically the same as that shown in the first embodiment. However, the surface roughness of the developing sleeve 114 was Ra≈0.6 μm.

Using the developing sleeve described above, the same image forming experiment as in Example 1 was conducted. For comparison, an image forming experiment was similarly performed using a conventional sandblasted aluminum developing sleeve. The surface roughness was Ra≈0.6 μm. The image has a halftone portion, and the halftone portion was formed with a resolution of 600 dpi, a horizontal line: 2 dot lines, and a blank: 3 dot lines. The test environment is the same as before, 15 ° C. and 10% RH. The obtained results are shown in Table 7 as Example 7 and Conventional Example 7, respectively.

[0083]

[Table 7]

As shown in Table 7, according to the present embodiment, the spherical magnetic toner is used for the image having the halftone to prevent the image unevenness, the sleeve ghost and the total solid black density. You can see that everything was done well.

Embodiment 8 FIG. 6 is a constitutional view showing still another embodiment of the developing device of this embodiment. The developing device of this embodiment uses the elastic blade 46 made of urethane, which is in contact with the developing sleeve 114 in the direction opposite to the rotation direction, as the developer regulating member. Different from the device. Other configurations of this embodiment are the same as those of the first embodiment, and the same reference numerals as those in FIG. 1 in FIG. 6 denote the same members.

In this embodiment, the magnetic toner 11 of the one-component developer carried on the developing sleeve 114 was regulated by the elastic blade 46 as described above and provided for development. The developing sleeve 114 used was the same as that shown in the first embodiment.

Using the developing sleeve 114 described above, the same image forming experiment as in Example 1 was conducted. The results in this embodiment are shown in Table 8 as Example 8 and Conventional Example 8 together with the results when the developing sleeve of Conventional Example 1 was used.

[0088]

[Table 8]

As shown in Table 8, according to this embodiment,
Even when the elastic blade in the reverse direction contact was used, the density stability of the sleeve ghost and the formation of a large number of images was improved.

Ninth Embodiment FIG. 7 is a block diagram showing still another embodiment of the developing device of this embodiment. In the developing device of this embodiment, the elastic blade 46 ′ of the developer regulating member is in contact with the developing sleeve 114 in the same direction (forward direction) as the rotation direction thereof. Different from the developing device. Developing sleeve 11
For No. 4, the same one as shown in Example 1 was used.

An image forming experiment similar to that in Example 1 was conducted using the above developing sleeve. The results in this embodiment are shown in Table 9 as Example 9 and Conventional Example 9 together with the results when the developing sleeve of Conventional Example 1 was used.

[0092]

[Table 9]

As shown in Table 9, according to this embodiment,
Even when the forward contact elastic blade was used, the sleeve ghost and the density stability of a large number of images were improved.

Example 10 In this example, the surface of the developing sleeve 114 of Example 1 was used by polishing with a felt containing no abrasive. Others were the same as in Example 1.

The greatest feature of this embodiment is that the surface of the developing sleeve 114 is polished with felt. By this polishing, the conductive titanic acid protruding from the surface of the conductive resin layer 102 on the developing sleeve 114 is used. Rubbing the protruding portion of the potassium whisker, as shown in FIG.
With respect to the conductive potassium titanate whisker 103 in which the resin Bd of No. 02 is thinly adhered to the surface, the resin Bd at the tip portion can be removed.

Therefore, according to this embodiment, even when the resin is coated on the whisker protrusions from the surface of the resin layer 102 when the resin layer 102 is formed, the surface 105 of the whisker 104 can be exposed by polishing. The leak site effect of whiskers can be improved.

An image forming experiment similar to that in Example 1 was conducted using the above developing sleeve. The results in this embodiment are shown in Table 10 as Example 10 and Conventional Example 10 together with the results when the developing sleeve of Conventional Example 1 was used.

[0098]

[Table 10]

As shown in Table 10, according to this embodiment, the density stability of the sleeve ghost and the image formation of a large number of images was further improved.

Example 11 In this example, the surface of the developing sleeve 114 of Example 2 was used after being polished with a felt containing no abrasive. Others were the same as in Example 2.

The feature of this embodiment is that, like the tenth embodiment,
Although the surface of the developing sleeve 114 is polished, the same effect as the tenth embodiment is obtained.

An image forming experiment similar to that in Example 1 was conducted using the above developing sleeve. The results of this embodiment are shown in Table 11 as Example 11 and Conventional Example 11 together with the results obtained when the developing sleeve of Conventional Example 1 was used.

[0103]

[Table 11]

As shown in Table 11, according to this embodiment, the density stability of the sleeve ghost and the image formation of a large number of images was improved.

Example 12 In this example, the surface of the developing sleeve 114 of Example 3 was used after being polished with a felt-free felt. Others were the same as in Example 3. An image forming experiment similar to that in Example 1 was conducted using the above developing sleeve.
The results in this embodiment are shown in Table 12 as Example 12 and Conventional Example 12 together with the results when the developing sleeve of Conventional Example 1 was used.

[0106]

[Table 12]

As shown in Table 12, according to this embodiment, the sleeve ghost and the density stability of image formation on a large number of sheets were improved.

In the above tenth to twelfth embodiments, the surface of the developing sleeve 114 was polished with a felt containing no abrasive. However, if an abrasive having a small particle size is selected, the same can be done by using an abrasive for the felt. Can be obtained.

Embodiment 13 FIG. 9 is a constitutional view showing still another embodiment of the developing device of the invention. The present developing device is characterized in that a two-component developer 31 composed of a magnetic carrier and a toner is used as a developer. The other structure of the present embodiment is basically the same as that of the developing device of the first embodiment shown in FIG. 1, and the same reference numerals as those in FIG. 9 denote the same members in FIG.

In the present developing device, the two-component developer 31 contained in the developing container 12 is agitated and conveyed by a pair of conveying screws 32, and the developer 31 is developed.
It is carried on the developing sleeve 114 by the magnetic force of the magnet roller 34 arranged inside. Then, after the developer 31 carried on the developing sleeve 114 is regulated by the blade 33, the developer 31 is conveyed to the developing area 13 by the rotation of the developing sleeve 114 in the direction opposite to the photosensitive drum 1, and in the developing area 13. A magnetic brush of the developer 31 is formed by the developing pole of the magnet roller 34, and the photosensitive drum 1 is rubbed to develop the latent image formed on the photosensitive drum 1.

In this embodiment, as the two-component developer 31,
An insulating magnetic carrier having a particle size of 60 μm (generally, a particle size of 10 to 200 μm is possible) and an insulating nonmagnetic toner having a particle size of 8.5 μm were used. The distance between the developing sleeve 114 and the photosensitive drum 1 in the developing area is 500 μm.
And

The conductive resin layer 1 on the developing sleeve 114
In the same manner as in Example 1, 25 wt% of conductive potassium titanate whisker was blended in No. 02, but by adjusting the method of forming the resin layer 102, the surface roughness of the developing sleeve 114 was 10 specified in JIS. 10 μm in point average roughness Rz
And the surface roughness was made different from that of Example 1 (Example 1
Surface roughness Ra of the developing sleeve of ≅2.0 μm).

The aluminum substrate 101 is made of an irregular-shaped alundum abrasive grain (for example, Morundum # 400 manufactured by Showa Denko).
Also, the conductive resin layer 10 can be formed by sandblasting with a roughened surface near Rz = 10 μm in advance.
2 After forming the surface roughness Rz of the developing sleeve 114 is 10μ
It can be about m.

An image forming experiment similar to that in Example 1 was conducted using the above developing sleeve. As a result, even when the two-component developer was used, the image density after image formation on about 5,000 sheets = 1.4 was satisfied, and the sleeve ghost prevention was good.

In Examples 1 to 13 above, the phenol resin was used as the resin of the conductive resin layer 102 on the surface of the developing sleeve 114, but the present invention is not limited to this, and various other resins may be used. it can.

Although the developing bias is applied by superimposing the DC voltage on the AC voltage, it is needless to say that the developing bias of only the DC voltage may be applied and the same effect can be obtained.

In the present invention, since the developing sleeve 114 has a high leak site effect due to the conductive potassium titanate whiskers mixed in the conductive resin layer 102 on the surface, the toner of the one-component developer or the two-component developer used is , A toner having a small volume average particle diameter with a large specific charge amount, particularly 9 μm
It has significant effects on:

[0118]

As described above, according to the present invention, the developer carrying member carrying the developer and carrying it to the current region facing the image carrying member is provided with conductive potassium titanate on the surface of the conductive substrate. A conductive resin layer containing whiskers is coated, the whiskers have an average fiber diameter of 0.3 to 0.7 μm and an average fiber length of 10 to 20 μm, and the resin layer is
Volume resistivity of 10 ⁻⁶ to 10 ² Ω · cm and 0.5 to 30
Since it has a film thickness of μm, it is possible to remove or reduce the mirroring force of the charged up fine powder developer in the vicinity of the surface of the developer carrier, and obtain a good image without sleeve ghost.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a developing device of the present invention.

FIG. 2 is a perspective view showing a developing sleeve arranged in the developing device of FIG.

FIG. 3 is an enlarged cross-sectional view showing the vicinity of the surface of the developing sleeve.

FIG. 4 is a plan view schematically showing a conductive potassium titanate whisker blended in a conductive resin layer provided on the surface of the developing sleeve in the present invention.

FIG. 5 is a configuration diagram showing another embodiment of the developing device of the invention.

FIG. 6 is a configuration diagram showing another embodiment of the developing device of the invention.

FIG. 7 is a configuration diagram showing another embodiment of the developing device of the invention.

FIG. 8 is an enlarged sectional view showing the vicinity of the surface of the developing sleeve after polishing.

FIG. 9 is a configuration diagram showing another embodiment of the developing device of the invention.

FIG. 10 is a configuration diagram showing a conventional developing device.

FIG. 11 is an explanatory diagram showing a sleeve ghost that has conventionally occurred.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum 10 Developing device 11 Magnetic toner 15 Magnet roller 31 Two-component developer 41 Non-magnetic toner 101 Base 102 Conductive resin layer 103 Conductive potassium titanate whisker 114 Development sleeve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takushi Shibuya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Yasuo Yoda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masahide Hirai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (13)

[Claims] 1. A developer carrying member carrying a developer and transporting the developer to a developing area facing the image carrying member, wherein the developer carrying member contains a conductive potassium titanate whisker on a surface of a conductive substrate. The whisker has an average fiber diameter of 0.3 to 0.7 μm and an average fiber length of 10 to 20 μm, and the resin layer is 10 ⁻⁶ to 10 ^−6. Volume resistivity of ² Ω · cm and 0.5-
A developer carrier having a film thickness of 30 μm. 2. The developer carrying member according to claim 1, wherein the conductive resin layer further contains carbon black and / or graphite. 3. The developer carrying member according to claim 1 or 2, wherein the surface is lightly polished after coating the conductive resin layer. 4. A developing device in which a developer is carried on a developer carrying body and regulated by a regulating member, and the developer carrying body conveys the developer to a current area facing the image carrying body, The carrier has a conductive resin layer containing conductive potassium titanate whiskers coated on the surface of a conductive substrate, and the whiskers have a thickness of 0.3 to 0.7.
It has an average fiber diameter of 10 μm and an average fiber length of 10 to ²⁰ μm, and the resin layer has a volume resistivity of 10 ⁻⁶ to 10 ² Ω · cm and a film thickness of 0.5 to 30 μm. Developing device. 5. The developing device according to claim 4, wherein the conductive resin layer further contains carbon black and / or graphite. 6. The developing device according to claim 4, wherein the surface of the developer bearing member is lightly polished after being coated with a conductive resin layer. 7. The developing device according to claim 4, wherein the developer is a one-component developer including a magnetic toner or a non-magnetic toner. 8. The developing device according to claim 7, wherein the toner has an average particle diameter of 9 μm or less. 9. The developing device according to claim 7, wherein the toner has a spherical shape. 10. The developing device according to claim 4, 5 or 6, wherein the developer is a two-component developer including a non-magnetic toner and a magnetic carrier. 11. The developing device according to claim 10, wherein the toner has an average particle diameter of 9 μm or less. 12. The toner has a spherical shape 10 or 1.
1 developing device. 13. The regulating member is made of an elastic member that is in contact with a developer carrying member.
0, 11 or 12 developing devices.