JP3110930B2 - Developer carrier and developing device - Google Patents

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 electrophotographic photosensitive member or an electrostatic recording dielectric image carrier.

[0002]

2. Description of the Related Art Conventionally, a one-component developer is used, and a developer carrier carrying the one-component developer is opposed to the image carrier at a predetermined minute gap from the surface of the image carrier. Is known (for example, Japanese Patent Publication No. 41-9476). A high frequency pulse bias (frequency 10 kHz to 3000 k) is applied to the gap.
(E.g., Hz) to apply the developer to the image portion of the image carrier, but not to the non-image portion (for example, US Pat. No. 3,890,929).
No. 3,866,574 and No. 3,938,318).

Further, a two-component developer containing a toner and a carrier is used, and the two-component developer is indiscriminately brought into contact with the image portion and the non-image portion of the image carrier, and at the same time, the developer carrier and the image carrier are contacted. There is also known a developing technique in which a low-frequency alternating electric field is applied during the process to substantially apply the developer only to the image portion and to prevent the developer from adhering to the non-image portion, thereby performing development (for example, JP-A-55-32060).

FIG. 10 is a schematic configuration diagram showing an image forming apparatus provided with a conventional developing device. The present developing device is an example of a conventional developing device, and applies an alternating electric field to a developing region, which is a gap between a developer carrier and an image carrier.

As shown in FIG. 10, a developing device 10 is installed opposite to a drum-shaped electrophotographic photosensitive member which is an image carrier of an image forming apparatus, that is, a photosensitive drum 1 which rotates in the direction of an arrow. An electrostatic latent image is formed on 1 by a known electrostatic latent image forming unit 20 including a charger, an exposure unit, and the like. As the exposure unit, a projection unit for an optical image of a document, an optical system for scanning a laser beam modulated by a recorded image signal, or the like is employed. The latent image formed on the photosensitive drum 1 is
The toner 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 and the like.
The transfer material onto which the toner image has been transferred is separated from the photosensitive drum 1 and sent to a known fixing unit, where the toner image is fixed on the transfer material.

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

[0008] 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 contains a small amount of silica fine powder. The silica fine 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 fumed silica (dry silica) and / or wet-process silica (wet silica) to a toner.

[0009] such as styrene - to the negative polarity toner containing 60 parts by weight of magnetite acrylic respect strong negative charging property of the dry silica indicated (e.g. 100 m ² fumed silica, HMDS the 100 m ² per 10 parts by weight of The developer which is added in a ratio and heat-treated) is suitable for reversal development of a negative electrostatic latent image.

The one-component developer, that is, the magnetic toner 11 is supplied to the container 1 by a non-magnetic developing sleeve 14 such as aluminum or stainless steel, which rotates in the direction of the arrow as a developer carrier.
2 and taken out of the developing area 1 facing the photosensitive drum 1
3 is carried. 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, a developer is applied to the electrostatic latent image on the photosensitive drum 1 in the developing area 13 to develop the electrostatic latent image.

The developing sleeve 1 conveyed to the developing area 13
The thickness of the toner layer 11 ′ on 4 is regulated by the blade 16. The blade 16 is made of a magnetic material such as iron.
5 and the developing sleeve 14 is interposed therebetween. Therefore, the lines of magnetic force from the magnetic pole N1 concentrate 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 the two 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 through the air gap and reaches the photosensitive drum 1. I do. A developing bias voltage including an alternating component is applied to the developing sleeve 14 from a bias power source 18 of constant voltage control in order to improve the developing efficiency at that time and to form a developed image having a high density, a clear image and a reduced fog. Is done.

As described above, the developing bias is preferably obtained by superimposing an alternating voltage on a DC voltage. The frequency of the alternating voltage is preferably 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 a rectangular wave, a sine wave, a triangular wave, or the like. Is done.

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

By the developing bias, an electric field in the direction of transferring the toner 11 from the developing sleeve 14 to the photosensitive drum 1 and an electric field in the direction of transferring the toner 11 from the photosensitive drum 1 to the developing sleeve 14 alternately act. Thereby, a good developed image is obtained.

Incidentally, the reversal development is a development method in which a toner charged to the same polarity as the latent image is attached to the bright portion potential region of the latent image to visualize the latent image. On the other hand, a developing method in which a toner charged to a polarity opposite to that of the latent image is made to adhere to the dark portion potential region of the latent image to visualize the latent image is called normal development.

The toner 11 mainly consists of the developing sleeve 14
Is charged to the polarity to develop the electrostatic latent image.
The toner 11 includes, for example, a binder resin containing a styrene-acryl copolymer as a main component, 60% by weight of magnetite, and 1% by weight of a metal complex salt of a monoazo dye as a negative charge control agent. It is based on an insulating magnetic toner of 10 ¹³ Ωcm, and is obtained by externally adding 0.4% by weight, based on the weight of the toner, of silica fine particles which have been subjected to hydrophobic treatment in order to enhance fluidity. Such toner is negatively charged due to friction with the developing sleeve 14.

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 conveyance of the toner.

[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 appears on a printed image. A sleeve ghost generated in the case of a developer in which negative silica is externally added to negative toner becomes a positive ghost as shown in FIG. That is, since the non-printed portion (white background) continues, only a thin development is performed even when printing is performed (a).
Density unevenness occurs in a portion and in a portion (b) where dark development is performed because printing is continued.

According to the experiments and considerations of the present inventors, the mechanism of the ghost formation is deeply related to the layer of the differential toner (particle size of 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 consuming portion and the toner non-consuming portion, and the fine powder layer is formed in the toner lowermost layer of the non-consuming portion. . Since the fine powder toner has a large surface area per volume, the amount of triboelectric charge per mass becomes larger than that of the toner having a large particle diameter, and the toner is strongly restrained electrostatically to the developing sleeve by the self-reflective force. For this reason, the toner on the portion where the fine powder layer is formed is not sufficiently frictionally charged with the surface of the developing sleeve, so that the developing ability is reduced and appears as a sleeve ghost on the image.

The above-mentioned sleeve ghost is a phenomenon that occurs because the charging of the toner greatly 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 mirror force acting between the charged sleeve of the 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 mirror force of a charged-up fine powder developer near the surface of a developer carrying member, and to obtain a good image without a sleeve ghost. To provide a body and a developing device.

[0024]

The above object is achieved by a developer carrier and a developing device according to the present invention. In summary, according to the first aspect of the present invention, in a developer carrier for carrying a developer and transporting the developer to a development area opposed to an image carrier, the developer carrier is electrically conductive on a surface of a conductive substrate. A conductive resin layer containing a conductive potassium titanate whisker, wherein the whisker has an average fiber diameter of 0.3 to 0.7 μm and an average fiber length of 10 to 20 μm; is, 10 ^-6 ~10 ² Ω · cm in volume resistivity, and 0.
A whisker having a thickness of 5 to 30 μm, partially projecting the whisker from the surface of the conductive resin layer, and removing the resin at the tip of the projecting whisker to expose the surface of the whisker. Is provided. According to one embodiment of the present invention, the conductive resin layer may further contain carbon black and / or graphite.

According to the second aspect of the present invention, the developer is carried on the developer carrier and regulated by the regulating member, and the developer is transported by the developer carrier to the developing area facing the image carrier. In the developing device, the developer carrier has a conductive resin layer containing a conductive potassium titanate whisker coated on a surface of a conductive substrate, and the whisker has a thickness of 0.3 to 0.7 μm. Average fiber diameter and 10-20
μm, and the resin layer has an average fiber length of 10 ⁻⁶ to 10
^{It has} a volume resistivity of ² Ω · cm and a film thickness of 0.5 to 30 μm, partially protrudes the whisker from the surface of the conductive resin layer, and removes the resin at the tip of the protruding whisker. A developing device is provided, wherein the surface of the whisker is exposed. According to one embodiment of the present invention, the conductive resin layer may further contain carbon black and / or graphite.

According to a second embodiment of the present invention, the developer is a magnetic toner or a non-magnetic toner, and the surface roughness of the developer carrier is about 2.0 at a center line average roughness Ra.
μm. According to another embodiment of the second invention, the developer is a spherical magnetic toner, and the surface roughness of the developer carrier is about 0.6 μm in center line average roughness Ra. According to another embodiment of the second invention, the developer is a two-component developer having a non-magnetic toner and a magnetic carrier, and the surface roughness of the developer carrier has a 10-point average roughness R
It is about 10 μm in z. According to another embodiment of the second invention, the toner has an average particle size of 9 μm or less. Second
According to another embodiment of the present invention, the regulating member comprises an elastic member abutting on the developer carrier.

[0027]

【Example】

Embodiment 1 FIG. 1 is a configuration diagram showing one embodiment of a developing device of the present invention, FIG. 2 is a perspective view showing a developing sleeve disposed 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,
The use of a developing sleeve 114 having a conductive resin layer containing conductive potassium titanate whiskers formed on the surface is a major feature. Other configurations of the developing device of the present embodiment are basically the same as the conventional developing device shown in FIG.
In FIG. 1, the same reference numerals as those shown in FIG. 10 indicate the same members.

In this embodiment, the developing sleeve 114
Is a conductive resin layer 10 containing a conductive potassium titanate whisker (a general formula of potassium titanate: K ₂ O.nTiO ₂ ) on the surface of a nonmagnetic aluminum base 101.
2 is provided. The base 101 has an outer diameter of 16 mm,
It has dimensions of a wall 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 μm.
Conductive potassium titanate whisker (trade name: Dentol, manufactured by Otsuka Chemical Co., Ltd.) obtained by subjecting the surface 105 of a potassium titanate whisker (trade name: Tismo, manufactured by Otsuka Chemical Co., Ltd.) 104 of ~ 20 μm to conductivity. 103, this was dispersed in a thermosetting phenol resin, and applied to the substrate 101 by spray coating to a coating 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 about 30 ° C. for about 30 minutes.

The conductive potassium titanate whisker content of 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 a coating condition or the like. In this embodiment, the surface roughness of the developing sleeve 114 is set to J
The center line average roughness Ra described in ISB0601 is about 2.0.
μm.

The most characteristic feature of the resin layer 102 is that at least a part of the conductive potassium titanate whiskers 103 partially protrude from the surface thereof as shown in FIG. In other words, although the surface of the developing sleeve 114 after the application of the conductive resin layer 102 is roughened to Ra ≒ 2.0 μm, the conductive potassium titanate whisker 103 further protrudes microscopically. Surface condition.

According to this, since the conductive potassium titanate whisker 103 is a needle-shaped crystal as shown in FIG. 4, the whisker has an effect of acting as a leak site, and the charged fine powder on the surface of the developing sleeve is reduced. It is considered that an effect of weakening the reflection power of the toner can be expected, thereby suppressing the sleeve ghost which has conventionally occurred.

An example of an image forming experiment performed in this embodiment will be described. The above-described 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 in a low-temperature and low-humidity environment of 15 ° C. and 10% RH where a sleeve ghost easily occurs. . Developing sleeve 11
The conductive resin layer 102 of No. 4 had a conductive potassium titanate whisker content of 25 wt%.

The developing sleeve 114 has a bias power supply 18
A developing bias of VDC = -500 V, VAC (peak-to-peak voltage Vpp) = 1600 V, and 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 as a one-component developer used had a volume average particle diameter of 11 μm.

For comparison, the same procedure as above was carried out using an aluminum developing sleeve which had been subjected to conventional sandblasting (using Morundum # 400 manufactured by Showa Denko). Table 1 shows these results as Example 1 and Conventional Example 1.

[0037]

[Table 1]

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

In the above description, a potassium titanate whisker (Dentol manufactured by Otsuka Chemical Co., Ltd.) that has been subjected to a conductive treatment was used as the conductive potassium titanate whisker. However, the present invention is not limited to this, and the conductive potassium titanate whisker may be any of Whiskers obtained by coating potassium titanate whiskers with various metal materials, specifically, whiskers coated with silver (Super Dentol manufactured by Otsuka Chemical Co., Ltd.), and whiskers coated with copper or nickel (Rioval manufactured by Otsuka Chemical Co., Ltd.) can also be used.

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

Although a 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, which 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 of the first embodiment is different from that of the first embodiment.
The feature is that carbon black is contained in the conductive resin layer 102 on the surface in addition to the conductive potassium titanate whisker (Dentol manufactured by Otsuka Chemical Co., Ltd.). Other configurations of the present embodiment are the same as those of the first embodiment.

As described above, the conductive potassium titanate whisker of the conductive resin layer 102 can be used at a content in the range of 10 to 40% by weight. Volume resistivity is 10 ²
It can be used at a content within the range of Ω · cm or less.

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

Carbon black 17% by weight Conductive potassium titanate whisker 17% by weight Phenol resin 66% by weight

Using the developing sleeve described above, an image forming experiment similar to that in Example 1 was performed. The results of this embodiment are shown in Table 2 as Examples 2 and Conventional Example 2 together with the results obtained 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 sleeve ghost is remarkable, and the density is stable even when a large number of images are formed, as compared with the conventional example.

Embodiment 3 This embodiment is different from Embodiment 1 in that the developing sleeve 114
It is characterized in that graphite is contained in the conductive resin layer 102 on the surface in addition to the conductive potassium titanate whisker (Dentol manufactured by Otsuka Chemical Co., Ltd.).

The above-mentioned graphite content is determined by adding the conductive potassium titanate whiskers 10 to 4 to the conductive resin layer 102.
The graphite can be blended under 0 wt% blending, and the volume resistivity can be selected in a range where 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 as follows. The method of forming the developing sleeve 114 was the same as in the first embodiment.

Graphite 17% by weight Conductive potassium titanate whisker 17% by weight Phenol resin 66% by weight

Using the developing sleeve described above, an image forming experiment similar to that in Example 1 was performed. The results of the present embodiment are shown in Table 3 as Examples 3 and Conventional Example 3 together with the results obtained when the developing sleeve of Conventional Example 1 was used.

[0054]

[Table 3]

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

Embodiment 4 In the present embodiment, the developing sleeve 114 of the first embodiment is different from that of the first embodiment.
The feature is that both graphite and carbon black are contained in the conductive resin layer 102 on the surface in addition to the conductive potassium titanate whisker (Dentol manufactured by Otsuka Chemical Co., Ltd.).

The total content of graphite and carbon black is determined by mixing graphite and carbon black with 10-40 wt% of conductive potassium titanate whisker in conductive resin layer 102, and having a volume resistivity of 10%. It can be selected within the range of ² Ω · cm or less.

In this case, in order to ensure the mechanical strength of the resin layer 102, the total amount of graphite and carbon black is preferably not more than 2 parts by weight with respect to 1 part by weight of the resin. In order to enhance the mechanical lubricity of the surface of the developing sleeve 114, it is desirable to make the ratio of graphite 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 as follows. The method for forming the developing sleeve 114 is described in Example 1.
Same as.

Conductive potassium titanate whisker 10 wt% graphite 20 wt% carbon black 5 wt% phenolic resin 65 wt%

Using the developing sleeve described above, an image forming experiment similar to that in Example 1 was conducted. The results in this embodiment are shown in Table 4 as Examples 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 example, the effect of reducing 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 on the surface of the developing sleeve and the effect of reducing the charge-up are particularly high, the effect of preventing the toner component from adhering to the surface of the developing sleeve is improved by 5 times.
It can be seen that a characteristic result that can be sufficiently maintained even with about 0000 sheets is obtained.

Embodiment 5 This embodiment shows an example in which a non-magnetic toner which is a non-magnetic one-component developer is used as a developer. FIG. 5 is a configuration diagram illustrating the developing device of the present embodiment.

The developing device 10 of this embodiment includes a developing container 12
1 in that an application roller 50 for the non-magnetic toner 311 is provided therein, and an elastic blade 36 that comes into contact with the developing sleeve 114 is used as a regulating member. Other configurations of the developing device of this embodiment are basically the same as those of the developing device of FIG. 1. In FIG. 5, the same reference numerals as in FIG. 1 denote the same members.

The application roller 50 is formed of an elastic roller made of a foaming elastic material. The application roller 50 abuts against 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 transported and carried on the sleeve 114. The elastic blade 36 is made of an elastic material such as urethane and is in contact with the developing sleeve 114 in a direction opposite to the rotation 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 thin toner layer 311 ′ by the elastic blade 36 during the conveying.
And is subjected to development in the development area.

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

Using the developing sleeve described above, an image forming experiment similar to that in Example 1 was performed. Table 5 shows the results of the present embodiment together with the results obtained when the developing sleeve of Conventional Example 1 was used, as Example 5 and Conventional Example 5.

[0069]

[Table 5]

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

In addition to the above, in addition to the conductive potassium titanate whisker, one of carbon black and graphite was formed on the conductive resin layer 102 on the surface of the developing sleeve 114 in the same manner as in Examples 2 to 4. Trials containing two or more species were also effective for non-magnetic toners.

Example 6 In this example, the magnetic toner 11 of Example 1 having a volume average particle diameter of 9 μm was used as the one-component magnetic developer. Other configurations of the present embodiment are the same as those of the first embodiment.

The above magnetic toner 1 having a volume average particle diameter of 9 μm
An image forming experiment similar to that of the first embodiment was performed using the developing sleeve of the first embodiment. Table 6 shows the results of this embodiment together with the results obtained when the developing sleeve of Conventional Example 1 was used, as Example 6 and Conventional Example 6.

[0074]

[Table 6]

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

Further, using a 6.5 μm magnetic toner, the same results as those shown in Table 6 were obtained. This shows that the present invention is also effective for magnetic toners having a volume average particle diameter of 6.5 μm or less.

Embodiment 7 This embodiment is characterized in that a spherical toner is used as the magnetic toner 11 in the embodiment 1, and the other configuration is the same as that of the embodiment 1.

The spherical magnetic toner is produced by a polymerization method. In this embodiment, a toner having a volume average particle diameter of 8 μm is used. Since the spherical toner has a shape in which the specific charge amount of the toner particularly increases as the particle diameter decreases, it is characterized in that it is difficult to mechanically convey the toner.

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 Co., Ltd.) having an average fiber length of 10 to 20 μm is blended. As described above, since a part of the whisker protrudes from the surface of the resin layer 102 and forms a so-called infinite number of leaks on the surface, the charge-up of the toner can be prevented.

However, in addition to this, the fine projections on the surface of the resin layer 102 due to the projections of the whiskers have an effect of effectively working the mechanical transport of the toner. Therefore, even the spherical toner used in this embodiment can be sufficiently mechanically conveyed by the developing sleeve 114. This toner transportability is particularly effective when the toner layer on the developing sleeve 114 is a thin layer (for example, one or two layers). This is because each of the toners in the thin toner layer is reliably transported because the protrusions on the surface of the resin layer 102 due to the whisker protrusions are present innumerably and uniformly.

In the present embodiment, a developing sleeve 114 which is basically the same as that shown in Embodiment 1 is used for the above-mentioned spherical magnetic toner 11. However, the surface roughness of the developing sleeve 114 was Ra ≒ 0.6 μm.

Using the developing sleeve described above, an image forming experiment similar to that in Example 1 was performed. For comparison, an image forming experiment was similarly performed using a conventional sand-blasted aluminum developing sleeve. The surface roughness was the same Ra ≒ 0.6 μm. The image had a halftone portion, and the halftone portion was formed with a resolution of 600 dpi, a horizontal line of 2 dot lines, and a blank of 3 dot lines. The test environment is the same as before at 15 ° C. and 10% RH. Table 7 shows the obtained results as Example 7 and Conventional Example 7, respectively.

[0083]

[Table 7]

As shown in Table 7, according to the present embodiment, a spherical magnetic toner is used for an image having a halftone to prevent image unevenness, prevent sleeve ghost, and reduce the total solid black density. It turns out that everything was good.

Embodiment 8 FIG. 6 is a structural view showing still another embodiment of the developing device of the present embodiment. The developing device according to the first embodiment shown in FIG. 1 uses the urethane elastic blade 46 that abuts the developing sleeve 114 in the direction opposite to the rotation direction as the developer regulating member. Different from device. Other configurations of this embodiment are the same as those of the first embodiment. In FIG. 6, the same reference numerals as those shown in FIG. 1 denote the same members.

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

Using the developing sleeve 114, an image forming experiment similar to that of the first embodiment was performed. Table 8 shows the results of this embodiment together with the results obtained when the developing sleeve of Conventional Example 1 was used, as Example 8 and Conventional Example 8.

[0088]

[Table 8]

As shown in Table 8, according to the present embodiment,
The sleeve ghost and the density stability of image formation on a large number of sheets were improved even when the elastic blade in reverse contact was used.

Embodiment 9 FIG. 7 is a structural view showing still another embodiment of the developing device of the present embodiment. In the developing device of the present 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, as shown in FIG. Different from developing device. Developing sleeve 11
As for No. 4, the same one as shown in Example 1 was used.

Using the developing sleeve described above, the same image forming experiment as in Example 1 was performed. The results in this embodiment are shown in Table 9 as Examples 9 and Conventional Example 9 together with the results obtained when the developing sleeve of Conventional Example 1 was used.

[0092]

[Table 9]

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

Example 10 In this example, the surface of the developing sleeve 114 of Example 1 was polished and used with an abrasive-free felt. Others were the same as in Example 1.

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

Therefore, according to the present embodiment, even if the resin covers the whisker protrusion 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. Thus, the effect of a whisker leak site can be improved.

Using the developing sleeve described above, the same image forming experiment as in Example 1 was performed. Table 10 shows the results of the present embodiment together with the results obtained when the developing sleeve of Conventional Example 1 was used, as Example 10 and Conventional Example 10.

[0098]

[Table 10]

As shown in Table 10, according to the present embodiment, the sleeve ghost and the density stability of forming many images were further improved.

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

The features of this embodiment are similar to those of the tenth embodiment.
Polishing the surface of the developing sleeve 114 has the same effect as in the tenth embodiment.

Using the developing sleeve described above, an image forming experiment similar to that in Example 1 was performed. The results in this embodiment are shown in Table 11 as Examples 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 the present example, the sleeve ghost and the density stability of forming many images were improved.

Example 12 In this example, the surface of the developing sleeve 114 of Example 3 was polished with an abrasive-free felt. Others were the same as in Example 3. Using the developing sleeve described above, an image forming experiment similar to that in Example 1 was performed.
Table 12 shows the results of this embodiment together with the results obtained when the developing sleeve of Conventional Example 1 was used, as Example 12 and Conventional Example 12.

[0106]

[Table 12]

As shown in Table 12, according to the present embodiment, the sleeve ghost and the density stability of forming many images were improved.

In Examples 10 to 12 described above, the surface of the developing sleeve 114 was polished with felt containing no abrasive. However, if an abrasive having a small particle size is selected, the surface of the developing sleeve 114 can be polished using an abrasive. Effects can be obtained.

Embodiment 13 FIG. 9 is a structural diagram showing still another embodiment of the developing device of the present invention. This developing device is characterized in that a two-component developer 31 composed of a magnetic carrier and a toner is used as a developer. Other configurations of the present embodiment are basically the same as those of the developing device of the first embodiment shown in FIG. 1. In FIG. 9, the same reference numerals as those shown in FIG. 1 denote the same members.

In this developing device, the two-component developer 31 accommodated in the developing container 12 is stirred and transported by a pair of transport screws 32, and the developer 31 is transferred to the developing sleeve 114.
It is carried on the developing sleeve 114 by the magnetic force of the magnet roller 34 disposed inside. After regulating the developer 31 carried on the developing sleeve 114 by the blade 33, the developer 31 is conveyed to the developing area 13 by rotating the developing sleeve 114 in the direction facing the photosensitive drum 1, and 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 a latent image formed on the photosensitive drum 1.

In this embodiment, as the two-component developer 31,
A carrier composed of 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 non-magnetic toner having a particle size of 8.5 μm was 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 Example 02, 25% by weight of conductive potassium titanate whisker was blended in the same manner as in Example 1. However, by adjusting the method of forming the resin layer 102, the surface roughness of the developing sleeve 114 was adjusted to 10 stipulated in JIS. 10 μm in point average roughness Rz
And the surface roughness was different from that of Example 1 (Example 1).
Surface roughness RaＲ2.0 μm) of the developing sleeve.

The aluminum substrate 101 is made of irregular-shaped abrasive grains (for example, Morandum # 400 manufactured by Showa Denko).
The surface of the conductive resin layer 10 can also be sand-blasted in advance to roughen the surface to near Rz = 10 μm.
2 after forming, the surface roughness Rz of the developing sleeve 114 is set to 10 μm.
m.

Using the developing sleeve described above, an image forming experiment similar to that in Example 1 was performed. As a result, even when the two-component developer was used, the image density after the formation of about 5,000 sheets of image satisfied 1.4, and the prevention of sleeve ghost was good.

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

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

In the present invention, since the developing sleeve 114 has a high leak site effect due to the conductive potassium titanate whiskers blended 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, in which the specific charge is large, particularly 9 μm
Has significant effects on:

[0118]

As described above, according to the present invention,
The developer carrier is formed by coating a conductive resin layer containing a conductive potassium titanate whisker on the surface of a conductive substrate, and the whisker has an average fiber diameter of 0.3 to 0.7 μm and The resin layer has an average fiber length of 10 to ²⁰ μm and a volume resistivity of 10 ⁻⁶ to 102 Ω · cm and 0.5 to
It has a thickness of 30 μm, and furthermore, the whisker is partially protruded from the surface of the conductive resin layer, and the resin at the tip of the protruded whisker is removed to expose the surface of the whisker. By removing or reducing the mirror force of the charged fine powder developer near the surface of the developer carrier, a good image without sleeve ghost can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing a developing sleeve provided in the developing device of FIG. 1;

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

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

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

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

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

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

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 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 developing sleeve

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tohru Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Takushi Shibuya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (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. (56) References JP-A-5-19606 (JP, A) JP-A-2-34665 (JP, A) JP-A-2-33167 (JP, A) JP-A-1-276174 (JP, A) JP-A-4-194867 (JP, A) JP-A-2-176682 (JP, A) JP-A-1-250963 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15 / 08 501 G03G 15/09-15/09 101

Claims (9)

(57) [Claims] 1. A developer carrier for carrying a developer and transporting the developer to a development area facing the image carrier, wherein the developer carrier 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 has a thickness of 10 ⁻⁶ to 10 μm. ^The whisker has a volume resistivity of ² Ω · cm and a film thickness of 0.5 to 30 μm, and partially protrudes the whisker from the surface of the conductive resin layer. A developer carrier having a surface of a whisker exposed. 2. The developer carrier according to claim 1, wherein the conductive resin layer further contains carbon black and / or graphite. 3. A developing device which carries a developer on a developer carrier and regulates the developer by a regulating member, and transports the developer by a developer carrier to a development area facing the image carrier. The carrier has a conductive resin layer containing conductive potassium titanate whiskers coated on the surface of a conductive substrate, and the whiskers have an average fiber diameter of 0.3 to 0.7 μm and a diameter of 10 to 10 μm. have an average fiber length of 20 [mu] m, the resin layer has a thickness of 10 ^-6 ~10 ² Ω · cm in volume resistivity and 0.5 to 30 m, the whiskers from the conductive resin layer surface A developing device characterized in that the whisker is partially protruded, and the resin at the tip of the protruding whisker is removed to expose the surface of the whisker. 4. The developing device according to claim 3, wherein the conductive resin layer further contains carbon black and / or graphite. 5. The developer according to claim 3, wherein the developer is a magnetic toner or a non-magnetic toner, and a surface roughness of the developer carrier is about 2.0 μm in center line average roughness Ra. 4 developing device. 6. The developer is a spherical magnetic toner, and the surface roughness of the developer carrier is a center line average roughness Ra.
5. The method according to claim 3, wherein the thickness is approximately 0.6 μm.
Developing device. 7. The developer according to claim 1, wherein the developer is a two-component developer having a non-magnetic toner and a magnetic carrier, and a surface roughness of the developer carrier is about 10 μm as a 10-point average roughness Rz. The developing device according to claim 3, wherein 8. The developing device according to claim 5, wherein the toner has an average particle diameter of 9 μm or less. 9. The developing device according to claim 3, wherein said regulating member comprises an elastic member abutting on a developer carrying member.