JP3026390B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus used in an electrophotographic system in which corona charging is unnecessary and exposure and development can be performed almost simultaneously, and more particularly to an image forming apparatus capable of color recording. It is.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic image forming apparatus, a Carlson method for charging a photosensitive member by corona discharge has been widely used. In this method, a corona charger, an exposing unit, a developing unit, a transferring unit, a cleaning unit, a discharging unit, and the like are arranged around a drum-shaped or belt-shaped photoconductor, and a charging, exposing, developing, transferring, and fixing process is performed. After that, an image is formed on the recording paper, which complicates the configuration of the device and the image forming process.A high-voltage power supply is required for corona discharge, and ozone is generated due to corona discharge, causing There were problems such as adverse effects.

In recent years, an electrophotographic system which does not require corona discharge has been proposed to solve these problems (Japanese Patent Publication No. 2-49).
No. 00, JP-B-60-59592, JP-A-58-44445, JP-A-58
-153957, JP-A-61-46961, JP-A-62-280772, etc.).

According to the electrophotography system proposed above, a drum-shaped or belt-shaped photoconductor in which a light-transmitting conductive layer and a photoconductive layer are sequentially laminated on a light-transmitting support is placed on the light-transmitting support side. The surface of the photoreceptor is rubbed with a magnetic brush made of a conductive magnetic toner on the developing device to which a bias voltage is applied by a power source for supplying a developing bias while the exposure is performed by the exposing device. Performed almost simultaneously, forming a toner image on the photoreceptor. The toner image is transferred to recording paper using a transfer roller and fixed by a fixing unit to form a recorded image. On the other hand, the toner remaining on the photoreceptor is collected by a developing device and reused.

There is a problem that it is difficult to record on plain paper because a conductive toner is used as a developer used in the electrophotographic system. In order to solve such a problem, a two-component developer in which a conductive magnetic carrier and an insulating magnetic toner are combined has been proposed, thereby enabling satisfactory recording on plain paper.

[0006]

However, in the electrophotographic system using the two-component developer proposed above, a strong magnetic material is used by using a ferromagnetic material such as iron, ferrite, or magnetite as the magnetic powder in the developer. To obtain a black recorded image, but on the other hand, there was a problem that a clear color image could not be obtained because the magnetic powder itself had a dark color close to black. .

[0007]

The image forming apparatus according to the present invention comprises a light-transmitting conductive layer, an amorphous silicon-based carrier injection blocking layer, and an amorphous silicon-based photoconductive layer (hereinafter referred to as amorphous silicon) on a light-transmitting support. Is abbreviated as a-Si) and a surface layer, a developing unit disposed on the photoconductive layer side of the photoconductor, a sleeve of the developing unit and a light-transmitting conductive layer. A means for applying a developing bias voltage therebetween, and an exposing means for irradiating light from the translucent support side to form an image on the photoconductor with a developer are provided. An image forming apparatus in which a developer reservoir is provided by moving the developer reservoir in the opposite direction at a closest position, and the developer reservoir is irradiated with exposure means, wherein the developer is a conductive magnetic carrier and an insulating magnetic material. toner 2 is a component developer and a magnetic powder to be contained in the insulating magnetic toner consisting of is characterized by a clear or colorless.

[0008]

The present invention will be described below with reference to examples.

FIG. 1 is a schematic view showing an image forming apparatus 1 according to the electrophotographic method of the present invention. In FIG. 1, reference numeral 2 denotes a light-transmitting conductive layer 4, a photoconductive layer 5 and a surface on a light-transmitting support 3. A drum-shaped photoreceptor having the layer 6 laminated thereon, 7 is an LED head as exposure means, 8 is a developing device, and 9 is a transfer roller. The LED head 7 and the developing device 8 are arranged substantially symmetrically via a part of the photoconductor 2. 10 is L as a light source for erasing
It is an ED array and may be arranged outside the photoconductor 2.
However, this does not mean that the LED array 10 must be provided. The developing device 8 includes, for example, a columnar magnetic pole roller 11 having eight poles and a conductive sleeve 12 disposed around the outer periphery thereof. The developing device 8 further includes a conductive magnetic carrier and an insulating magnetic toner. A two-component developer in which the magnetic powder contained in the non-magnetic toner is transparent or colorless is stored in the toner receiver 13, and the two-component developer is delivered to the outer periphery of the sleeve 12 to form the magnetic brush 14. A bias power source 15 is provided between the sleeve 12 and the light-transmitting conductive layer 4.
A voltage of V is applied. Reference numeral 16 denotes a toner image formed on the surface of the photoconductor 2, reference numeral 17 denotes recording paper, and reference numeral 18 denotes residual toner.
In addition, a rotating means for the developer and a rotating means for the photoconductor 2 are provided. Although an LED head is used here as the exposure means, a laser, a liquid crystal shutter, an EL head, or the like may be used. As the erasing light source 10, a light source such as a halogen lamp, a fluorescent lamp, and an EL array can be used in addition to the LED array.

Thus, according to the image forming apparatus having the above-described configuration, light for image exposure is emitted from the LED head 7 from the translucent support 3 side of the rotating photoreceptor 2, and holes are formed in the photoconductive layer 5. When the electrons are generated, if a + bias voltage is applied to the developing device side, the electrons move to the surface side of the photoconductive layer 5 by the bias voltage and cancel out the positive charges at the end of the magnetic brush 14, The toner adheres to the surface of the photoconductor 2. Then, the toner is transferred onto the recording paper 17 by the transfer roller 9 and then fixed.

Next, the specific contents of the image forming apparatus having the above configuration will be described in more detail.

FIG. 2 is an explanatory view showing a part of the photosensitive member 2 and a developer reservoir 19 formed by the developing means 8.

The developing device 8 for holding the developer includes a conductive sleeve 12 and a magnetic pole roller 11 disposed therein.
The developer may be conveyed by fixing the magnetic pole roller 11 and rotating the sleeve 12, or
May be fixed and the internal magnetic pole roller 11 may be rotated.

Here, when the developer is rotated in the opposite direction to the photosensitive member 2, the friction between the two causes the developing unit 8 to develop downstream from the closest part between the developing unit 8 and the photosensitive member 2 (the side where the photosensitive member is separated from the developer). A reservoir 19 is formed. The developer reservoir 19 is a portion separated by a broken line in the figure. That is, the portion of the developer protruding beyond the original height is the developer reservoir 19, and the transport speed of the developer, the height of the developer, the gap between the sleeve 12 and the surface of the photoconductor 2, etc. Rotation speed and required developer pool 1
It is set appropriately according to the size of 9.

Reference numeral 20 denotes a control electrode.
Is provided on the sleeve 12 at a position closest to the photosensitive member 2, and is insulated from the sleeve 12 by the insulator 21. The control electrode 20
The sleeve 12 has a belt-like shape along the length direction so that a uniform electric field is applied to the photoconductor 2 and the developer. This control electrode 2
0 is not indispensable to the present invention, and is appropriately adopted.

The position where image exposure is performed is not the closest position A between the surface of the photosensitive member 2 and the developing sleeve 12, but the position B of the developer reservoir 19 formed downstream by the rotation of the photosensitive member 2 in the reverse direction. Preferably, it is the latter half of the developer reservoir 19 on the downstream side. By performing the exposure at the position of the developer reservoir 19, the photoconductor 2 is sufficiently charged before the exposure, and the influence of the potential history of the photoconductor 2 before charging is suppressed. The toner remaining on the surface and the toner in the image background are sufficiently collected. Furthermore, since the photosensitive member 2 is sufficiently charged and exposed to light to eliminate the charge, the electric attraction between the developer and the photosensitive member 2 is strong, and a good toner image 16 is formed. After the toner image 16 is formed, the photoconductor 2 is quickly separated from the developer reservoir 19, so that the toner image 16 on the surface of the photoconductor 2 is disturbed by mechanical force such as collision or friction of the developer. Thus, the toner image 16 having a good resolution can be obtained.

At the position of the developer reservoir 19, a position A where the surface of the photosensitive member 2 and the developing sleeve 12 are closest to each other is larger than that of the position A.
The distance between the surface of the photoconductor 2 and the magnetic pole roller 11 increases.
Therefore, the magnetic force that attracts the developer toward the magnetic pole roller 11 is weakened, and the toner image 16 formed on the surface of the photoconductor 2 is weakened.
Can be prevented from being collected by the developing unit due to the magnetic force to lower the image density, or from being disturbed by the magnetic force and lowering the resolution. Further, a belt-shaped control electrode 20 is provided, and its potential is adjusted to a predetermined potential by a power supply 22. For example, the control electrode 20 is grounded and set to the same potential as the translucent conductive layer 4. Alternatively, the potential is set lower or higher than the potential of the sleeve 12.

By providing the control electrode 20 to which a potential can be applied independently of the sleeve 12 as described above, the surface potential of the photosensitive member 2 is neutralized via a developer, or the potential of the surface of the photosensitive member 2 is made uniform. The influence of the history of the photoconductor 2 due to the presence or absence of charging, exposure, and the like in the previous process can be canceled. As a result, when repeatedly used, for example, when the photoconductor 2 is rotated several times to obtain one image, a stable developed state and a recorded image can be obtained. Here, when the potential of the control electrode 20 is adjusted, it is possible to adjust and obtain optimum image forming conditions for image density, background fog, and the like. In addition, control electrode 2
By raising the potential of 0 and lowering the potential of the sleeve 12, the toner adheres to the non-exposed area and the toner does not adhere to the exposed area, so-called reversal development has become possible.

The toner image 16 formed on the surface of the photosensitive member 2
Is transferred to a recording paper 17 and fixed to form a recorded image. The residual toner 18 remaining on the surface of the photoreceptor 2 without being transferred is collected by a developing unit in the next image forming process and reused.

Further, the photoreceptor 2 after transfer is irradiated with a charge removing light by the erasing light source 10 so as to more effectively cancel the influence of the history of the photoreceptor 2 due to the charging or exposure in the previous process. It is possible to suppress an image problem such as an afterimage phenomenon at the time of repeated use. Further, the carrier trapped at the interface between the photoconductive layer 5 and the surface layer 6 of the photoreceptor 2 is erased, and the residual toner on the photoreceptor 2 is developed by eliminating the electric attraction between the photoreceptor 2 and the residual toner on the surface. It can be easily collected in the container 8.

In these figures, the photoconductor 2 has a light-transmitting conductive layer 4 formed on the outer peripheral surface of a drum-shaped light-transmitting support 3, and a photoconductive layer 5 and a photoconductive layer 5 are formed on the light-transmitting conductive layer 4. Surface layer 6
Are laminated.

The material constituting the translucent support 3 includes:
Examples include pyrex glass, soda glass, borosilicate glass, and the like; inorganic materials such as quartz and sapphire; and organic resin materials such as fluorine resin, polyester, polycarbonate, polyethylene terephthalate, vinylon, epoxy, and mylar.

The material constituting the transparent conductive layer 4 includes:
There are indium-tin-oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, and the like, and a metal layer made of Al, Ni, Au, or the like thinned to be translucent may be used. . The layer forming method includes a vacuum deposition method, an active reactive deposition method, an ion plating method, an RF sputtering method, a DC sputtering method, an RF magnetron sputtering method, a DC magnetron sputtering method,
Thermal CVD method, plasma CVD method, spray method, coating method,
There is an immersion method and the like. As the photoconductive layer 5, it is particularly preferable to use an a-Si based photoconductive layer. The a-Si based layer is formed by, for example, a glow discharge decomposition method, a sputtering method, an ECR method, a vapor deposition method, and the like. In this case, hydrogen (H) or a halogen element is contained in an amount of 1 to 40 atomic% for dangling bond termination. In order to obtain desired electrical characteristics such as dark conductivity and photoconductivity, and optical band gap of this layer, a Group IIIa element in the periodic table (hereinafter, a Group IIIa element in the periodic table) is used. Is abbreviated as group IIIa element), a group Va element (hereinafter abbreviated as group Va element), or an element such as carbon (C), nitrogen (N), and oxygen (O). In particular, when amorphous silicon carbide (hereinafter, amorphous silicon carbide is abbreviated as a-SiC) is used for the photoconductive layer 5, the x value of Si _1-X C _x is 0 <
x ≦ 0.5, preferably set in the range of 0.05 ≦ x ≦ 0.45. In this range, the resistance becomes higher than that of the a-Si layer,
This is desirable in that good carrier traveling can be ensured. III As Group a elements and Va group elements,
The element and the P element are preferable in that they have excellent covalent bonding properties and can sensitively change semiconductor characteristics, and furthermore, that excellent light sensitivity can be obtained.

The thickness of the a-Si based photoconductive layer 5 is 0.5 to 20.
μm, preferably 1 to 15 μm.

The surface layer 6 includes a high-resistance surface layer, particularly a-SiC
A-Si-based high-resistance surfaces such as amorphous silicon nitride (a-SiN), amorphous silicon oxide (a-SiO), amorphous silicon oxycarbide (a-SiCO), and amorphous silicon oxynitride (a-SiNO) It is preferable to use layers, which are formed by the same thin film forming means as the photoconductive layer 5. When a-SiC is used for the surface layer 6 and the photoconductive layer 5, carbon in the surface layer 6 is contained more than the amount of carbon contained in the photoconductive layer 5. Amount of carbon in the surface layer 6 is the x value of the _{Si 1-X C x 0.3 <} x <1.0, preferably good range of 0.5 ≦ x ≦ 0.95. The high-resistance surface layer 6 may also contain a group IIIa element or a group Va element for adjusting electric characteristics.

The thickness of the surface layer 6 is 0.05 to 5 μm, preferably
0.1 to 3 μm, and if less than 0.05 μm,
The layer 6 cannot sufficiently improve the withstand voltage, effectively trap optical carriers and contribute to the formation of a toner image, and when used repeatedly, has a poor life due to abrasion. When the thickness exceeds 5 μm, an electric field (lines of electric force) spreads in the film surface direction in this layer 6 to form a fine charge pattern, thereby lowering the resolution and obtaining a sufficient resolution. I can't. Further, since the amount of charge remaining on the surface increases and the residual potential increases, problems such as a reduction in image density, fogging of a back, and a change in image density during repeated use occur.

The photosensitive member 2 of the image forming apparatus according to the present invention
A carrier injection blocking layer may be further formed between the translucent conductive layer 4 and the a-Si based photoconductive layer 5 described above.

The carrier injection blocking layer may be an a-Si layer or an a-Si layer.
Any of SiC layers may be used. Generally, it is necessary to make the optical band gap larger than that of the photoconductive layer 5 so as not to absorb light effective for photocarrier generation in the photoconductive layer 5. It is preferable to include an element such as nitrogen. When the carrier injection blocking layer is formed of an a-SiC layer, the amount of carbon is preferably larger than that of the photoconductive layer 5.

The carrier injection blocking layer contains an impurity element for preventing carrier injection from the translucent conductive layer 4 into the photoconductive layer 5. That is, in order to prevent the injection of the negative charge carriers, the group IIIa element should be contained at 1 to 10,000 ppm, preferably 100 to 5,000 ppm. 5,000ppm
In the following, the content is preferably 300 to 3,000 ppm. These elements may be provided with a gradient in the layer thickness direction, in which case the average content of the entire layer may be within the above range.

When the carrier injection blocking layer contains a Group IIIa element as described above, a positive developing bias is used. On the other hand, when the carrier injection blocking layer contains a Va group element, a negative developing bias is used.

As the IIIa group element and the Va group element, the B element and the P element have excellent covalent bonding properties and can change semiconductor characteristics sensitively, and furthermore, excellent injection stopping power and light sensitivity can be obtained. This is desirable. The thickness of the carrier injection blocking layer is 0.01 to 3 μm, preferably 0.1 to 2 μm.
m, it is easy to secure a necessary dielectric strength voltage, and it is possible to effectively generate photocarriers in the photoconductive layer by suppressing unnecessary absorption of light exposure in this layer. Can be suppressed.

When the total content of each element of oxygen and / or nitrogen is in the range of 0.01 to 30 atomic% in the carrier injection blocking layer, the injection of carriers from the translucent conductive layer 4 is further improved. As well as being able to prevent this, the adhesion to the layer 4 can be further increased.

According to the present invention, there is provided an image forming apparatus having the above-mentioned configuration, wherein a two-component developer comprising a conductive magnetic carrier and an insulating magnetic toner and having a transparent or colorless magnetic powder contained in the insulating magnetic toner is used. Is the feature.

With this two-component developer, the electrostatic transfer of the toner image formed on the photoreceptor 2 to plain paper is facilitated by the insulating magnetic toner, and it is excellent for various recording papers. In addition to forming a recorded image, a multicolor recorded image can be obtained by using a color toner.

In particular, when a two-component developer comprising a combination of a conductive magnetic carrier having a conductive layer formed on the surface of particles in which a magnetic material is dispersed in a binder resin and an insulating magnetic toner is used, the photosensitive member 2 Excellent characteristics such as improvement of bias application characteristics and image density, effective collection of residual toner, and the like, and excellent recorded images can be obtained.

The insulating magnetic toner forms a magnetic brush. At this time, the toner is held on the carrier by the magnetic force of the developing device 8, and the residual toner on the photoreceptor 2 is not only removed by the magnetic brush but also by the magnetic force. Will be collected,
Fogging of the bag and scattering of the toner in the machine are suppressed, and good development characteristics excellent in recovering the residual toner can be obtained.

The magnetic powder of the insulating magnetic toner includes rare earth garnet and yttrium iron garnet (Y ₃ Fe ₅ O
₁₂ ) rare earth gallium such as single crystal or polycrystal of rare earth iron garnet, yttrium gallium garnet
At least one kind of garnet is used. These are transparent and can be arbitrarily colored with coloring agents,
As a color toner, a clear recorded image with little color turbidity can be obtained.

The particle size of these magnetic powders is 0.01 to 20 μm.
m is preferable, and is appropriately selected as needed according to the characteristics of the toner. In particular, when a magnetic powder having a particle diameter of 0.5 μm or less is used, a color image having good transparency can be obtained.

As the colorant of the toner, various well-known dyes and pigments for color toners can be used. For example, cadmium yellow, Hansa yellow G, permanent yellow HR, graphite, mineral first yellow, C.I.
I. Direct yellow, C.I. I. Acid yellow,
Disazo Yellow, Permanent Orange GTR, Cadmium Orange, Benzidine Orange G, Pyrazolone Orange, Permanent Red GG, Permanent Red F5R, Cadmium Red, Brilliant Carmine 6
B, pyrazolone red, lake red C, quinacridone red, C.I. I. Acid red, anthraquinone, fast violet B, dioxane violet,
Methyl violet lake, cobalt blue, ultramarine, navy blue, phthalocyanine blue, copper phthalocyanine, Victoria blue lake, indanthrene blue BC, C.I.
I. Direct blue, pigment green B, phthalocyanine green, carbon black, C.I. I. Direct black and the like.

As the binder resin for the toner, there are various well-known ones as long as they do not adversely affect the colorant. For example, waxes such as carnauba wax, montan wax, paraffin wax, polyethylene wax, polypropylene wax, etc. Styrene resins such as polystyrene, chloropolystyrene, poly-α-methylstyrene, epoxy resins, polyester resins, polyamide resins, glycol ester resins, phenolic resins, copolymers of styrene with alkyl acrylate or alkyl methacrylate, acrylic acid Alternatively, there is a copolymer of methacrylic acid and an alkyl acrylate or an alkyl methacrylate, and these are used alone or in combination.

The mixing ratio of the magnetic powder, the colorant and the binder resin is preferably 10 to 80 parts by weight of the magnetic powder and 5 to 40 parts by weight of the colorant with respect to 100 parts by weight of the binder resin.

If necessary, a surfactant, a lubricant, a metal-containing complex, a charge control agent such as chlorinated paraffin, a fixing aid such as polyethylene, a fluidity imparting agent such as zinc stearate, and a blocking agent such as colloidal silica. Additives such as inhibitors and cleaning agents are blended.

In order to obtain a magnetic color toner from the above components, there are a method of melt-kneading, pulverizing and then classifying with a classifier, a granulation method such as a spray drier method, a microencapsulation method and the like.

Further, fine particles such as a charge controlling agent may be fixed on the surface of the toner particles to adjust the characteristics of the toner.

In such a two-component developer, toner adheres to a magnetic brush formed by a carrier, and mainly adheres to the carrier by magnetic force.

[0046] The conductive magnetic carrier is suitable that the volume resistivity is not more than 10 ⁵ Ω · cm, preferably 10 ⁴ Ω · cm or less, and optimally 10 ² ~10 ⁴ Ω ·
cm. If the volume resistivity is too large, the characteristics as a conductive carrier are impaired, and charge is not quickly injected into the photoconductor in backside exposure recording, resulting in insufficient charging of the photoconductor. The volume resistivity of the carrier was measured by placing 1.5 g of the carrier in a 20 mm inner diameter Teflon cylinder having an electrode at the bottom, inserting an electrode having an outer diameter of 20 mm, and applying a load of 1 kg from the top. Is the value of

Further, the magnetic force of the carrier needs to be higher than a certain level, and the maximum magnetization (magnetic flux density) in a magnetic field of 5 kOe is preferably 55 emu / g or more, and more preferably 55 to 90 emu / g. 60 to 85 em
u / g. Also, the maximum magnetization in a magnetic field of 1 kOe is
It is preferably at least 40 emu / g, more preferably from 40 to 40 emu / g.
60 emu / g, optimally 45-60 emu / g
It is. If the magnetic force of the carrier is too small, the transportability of the developer is deteriorated, and the carrier is developed together with the toner, so-called carrier pulling occurs.

The average particle size of the carrier is suitably from 5 to 100 μm, preferably from 5 to 50 μm, more preferably from 10 to 40 μm. If the carrier is too large, it becomes difficult to uniformly charge the photoconductor. On the other hand, if it is too small, the transportability of the developer on the developing sleeve deteriorates, and it becomes difficult to apply a constant potential to the photoconductor.

As the conductive magnetic carrier, for example, the following can be used.

(1) A magnetic powder carrier which is used as it is or after being subjected to a stabilization treatment such as surface oxidation treatment or surface resin coating.

(2) A surface conductive resin carrier in which a conductive layer is formed on the surface of mother particles containing a magnetic substance in a binder resin.

(3) A surface conductive powder carrier having a conductive layer formed on the surface of a magnetic powder.

The magnetic material in the above magnetic powder carrier includes spinel ferrite such as magnetite and gamma iron oxide, spinel ferrite containing one or more metals other than iron (Mn, Ni, Mg, Cu, etc.), barium Magneto plumbite type ferrite such as ferrite,
Iron or alloy particles whose surface is oxidized or resin-coated can be used. Its shape is granular, spherical,
Any of a needle shape may be used. In particular, when high magnetization is required, ferromagnetic fine particles such as iron can be used. In consideration of chemical stability, it is preferable to use ferromagnetic fine particles of magnetite, spinel ferrite containing gamma iron oxide, and magnetoplumbite ferrite such as barium ferrite. By appropriately selecting the type and content of the ferromagnetic fine particles, a carrier having a desired magnetization can be obtained.

FIG. 3 is a schematic view showing an embodiment of the surface conductive resin carrier 23. The conductive fine particles 26 are provided on the surface of carrier base particles 25 in which magnetic particles 24 are uniformly dispersed in a binder resin. The carrier 23 is formed by being fixed to form a conductive layer. As the binder resin used for the carrier base particles 25, a vinyl resin represented by a polystyrene resin, a polyester resin, a nylon resin, a polyolefin resin, or the like is used.

As the magnetic particles 24, the same as the magnetic powder carrier can be used. It is appropriate to add the magnetic particles 24 in an amount occupying 70 to 90% by weight of the carrier base particles 25. As the conductive fine particles 26, carbon black, tin oxide, conductive titanium oxide (a coating of titanium oxide with a conductive material), silicon carbide, or the like is used, which does not lose conductivity due to oxidation by oxygen in the air. Is desirable.

For fixing the conductive fine particles 26 to the surface of the carrier base particles 25, for example, the carrier base particles 25 and the conductive fine particles 26 are uniformly mixed, and the conductive fine particles 26 are adhered to the surface of the carrier base particles 25. Thereafter, a mechanical / thermal impact force is applied to drive and fix the conductive fine particles 26 into the carrier base particles 25. The conductive fine particles 26 are not completely embedded in the carrier base particles 25, but are fixed so that a part thereof protrudes from the carrier base particles 25.

By fixing the conductive fine particles on the surface of the carrier 23 to form the conductive layer, the carrier 23 can be efficiently provided with high conductivity. In addition, since it is not necessary to mix the conductive fine particles 26 in the carrier matrix particles 25, the magnetic particles 24 can be blended in the carrier matrix particles 25 as much as possible, and the magnetic force of the carrier 23 can be increased.

FIG. 4 is a schematic view showing another embodiment of the conductive resin carrier, in which the magnetic particles 24 are uniformly dispersed in a binder resin, and the surface of the carrier base particles 25 is the same as in FIG. The conductive thin film 27 is formed to form a conductive layer, and the carrier 23 is formed.

In the surface conductive powder carrier, a surface conductive layer can be formed, for example, by the following method.

(1) A conductive thin film is formed in the same manner as the conductive resin carrier.

(2) After the surface of the magnetic powder is coated with a resin, conductive fine particles are fixed to the resin coating layer in the same manner as the conductive resin carrier.

The true density of the carrier is determined by the magnetic substance used in the case of a magnetic powder carrier, and is substantially the same in the case of a surface conductive powder carrier. The true density of the conductive resin carrier is 3.0 to 4.5 g / cm ^3.
Is suitable. The bulk density is suitably 2.5 g / cm ³ or less, preferably 2.0 g / cm ³ or less, more preferably 1.5 g / cm ³ or less. The carrier and the toner are mixed to form a developer. As the toner, a normal insulating toner is used, and preferably has a volume resistivity of 10 ¹⁴ Ω · cm or more, and preferably 10 ¹⁵ Ω · cm.
Ω · cm or more. This value is measured as in the case of the carrier.

As in the case of the carrier 23 shown in FIG.
The charging characteristics of the toner can also be controlled by fixing the charging fine particles to the surface of the toner base particles to form a toner.

Further, according to the present invention, the volume resistivity of the developer is preferably 10 ⁶ Ω · cm or less, preferably 10 ⁵ Ω · cm or less, more preferably 10 ³ to 10 ^5.
Ω · cm. This value is measured in the same manner as the carrier. If the resistance is too high, the charging of the photoconductor becomes insufficient.

The electrical resistance as a two-component developer also changes depending on the electrical resistance between the toner and the carrier, the toner concentration, the particle size ratio between the toner and the carrier, and the true density.

When the surface conductive resin carrier is used, the toner concentration of the developer (toner / carrier, ie, T /
C) is suitably at least 10% by weight, preferably at least 20% by weight.
%, More preferably 20 to 50% by weight.
If the toner density is too low, sufficient image density cannot be obtained when applied to the image recording method of the present invention. On the other hand, if the toner concentration is too high, the charging of the photoconductor becomes insufficient.
In the image forming method of the present invention, since substantially the same image density can be obtained in a wide range of the toner density T / C, the control of the toner density can be substantially unnecessary or greatly simplified.

In a developer using a conductive resin carrier,
The ratio (carrier) / (toner) of the average particle diameter of the carrier and the toner is preferably 1 to 5, and more preferably 1 to 5.
~ 3. When the toner is significantly smaller than the carrier, the surface area of the carrier covered by the toner increases at a constant toner concentration, and the photosensitive drum cannot be sufficiently charged. As a result, when applied to the image forming method of the present invention, the image density may be reduced depending on conditions. The average particle size of the toner is generally 20
μm or less, more preferably 15 μm or less.

Further, the present inventors have obtained the above-mentioned features of the second embodiment.
In the case where the component-based developer was used, an experiment was repeatedly performed. As a result, it was found that the developing bias voltage was preferably set to a low bias of 250 V or less. If the developing bias voltage is too high, not only the toner but also the carrier is developed, so-called carrier pull development occurs, and the image quality deteriorates. This is particularly remarkable when the particle size of the carrier is small. For development at such a low bias voltage, an a-Si-based photoreceptor having excellent photosensitivity characteristics such as good photocarrier excitation characteristics and high carrier mobility is preferable.

In particular, when a two-component developer in which a conductive magnetic carrier having a conductive layer formed on the surface of particles in which a magnetic material is dispersed in a binder resin and an insulating toner is used is used, It has excellent characteristics such as improvement of charging characteristics and image density by applying bias to
An extremely good recorded image can be obtained.

Next, each embodiment will be described in detail.

Example 1 First, a two-component developer was prepared as follows.

100 parts by weight of styrene acrylic resin, 65 parts by weight of yttrium iron garnet powder, 10 parts by weight of quinacridone red (red pigment), and 3 parts by weight of a charge control agent were mixed, and the mixture was heated in a hot roll mill. And kneaded by heating. Thereafter, the mixture is cooled, pulverized by a pulverizer and a jet mill, classified by an air classifier, and further externally added with silica powder having a particle diameter of 20 nm at 0.5% by weight using a Henschel mixer to obtain a red toner of 5 to 15 μm. Was. Next, this red toner and a conductive magnetic carrier having a particle size of 25 μm were mixed in a toner / carrier ratio of 15% to prepare a two-component developer.

Next, an ITO layer having a thickness of 1000 A was formed as a light-transmitting conductive layer 4 on the peripheral surface of a transparent cylindrical glass substrate having an outer diameter of 30 mm by an active reaction vapor deposition method. Using a discharge decomposition apparatus, an a-Si injection blocking layer, an a-Si photoconductive layer, and an a-SiC surface layer were sequentially laminated under the film forming conditions shown in Table 1 to produce a photoreceptor.

[0074]

[Table 1]

This photoreceptor is mounted on the image forming apparatus as shown in FIG. 1, using the two-component developer, and emitting light of a dynamic drive method at a wavelength of 685 nm and a resolution of 3
00DPI (dot / inch) LED head
Then, Vs = between the sleeve 12 and the translucent conductive layer 4.
A voltage of +50 V is applied, an image is exposed under the condition of an exposure amount of 0.7 μJ / cm ² , and a toner image is formed on the photosensitive member.
The toner image was transferred onto a commercially available plain paper by a transfer roller to which a transfer bias voltage of -200 V was applied, and was thermally fixed to obtain an image. The developer was rotated in the direction opposite to that of the photosensitive member 2 to form a developer reservoir 19, and the portion was exposed. When this image was evaluated, the optical density (hereinafter, referred to as
O. D. The image was a good image with a fogging of the background and a resolution of 300 DPI.

(Example 2) An image was formed in the same manner as in (Example 1) except that a two-component developer was prepared as described below.

100 parts by weight of polystyrene resin, 70 parts by weight of yttrium iron garnet powder, 15 parts by weight of copper phthalocyanine blue (blue pigment), and 3 parts by weight of a charge control agent were mixed, and the mixture was heated in a hot roll mill. And kneaded by heating. Thereafter, the mixture is cooled, pulverized by a pulverizer and a jet mill, classified by an air classifier, and further externally added with silica powder having a particle size of 20 nm at 0.5% by weight using a Henschel mixer to obtain a blue toner of 5 to 15 μm. Was. Next, this blue toner and a conductive magnetic carrier having a particle diameter of 25 μm were mixed at a toner / carrier ratio of 15% to prepare a two-component developer.

According to the image evaluation test of this example, the O.D. D.
A blue image having an image density of 1.3 was obtained, there was no fogging of the background, and the image had a good resolution of 300 DPI.

(Example 3) An image was formed in the same manner as in (Example 1) except that a two-component developer was prepared as described below.

100 parts by weight of a polyester resin, 75 parts by weight of yttrium / gallium / garnet powder, 10 parts by weight of disazo yellow (yellow pigment), and 3 parts by weight of a charge control agent were mixed, and the mixture was heated with a hot roll mill. And kneaded by heating. Thereafter, the mixture was cooled, pulverized by a pulverizer and a jet mill, classified by an air classifier, and further treated with a Henschel mixer to form silica powder having a particle size of 20 nm.
By external addition at 5% by weight, a yellow toner of 5 to 15 μm was obtained.
Next, this yellow toner and a conductive magnetic carrier having a particle size of 25 μm were mixed at a toner / carrier ratio of 15% to prepare a two-component developer.

According to the image evaluation test of the present example, the O.D. D.
A yellow image having an image density of 1.2 was obtained, there was no fogging of the background, and the image had a good resolution of 300 DPI.

(Example 4) Next, in (Example 3), magnetite was used as the magnetic powder, a yellow toner was similarly obtained, and a two-component developer was prepared.

When a similar image forming test was performed, a yellow image having a brownish color tone was obtained, and the image was a color tone in which turbidity due to magnetic powder was observed.

(Example 5) Next, in (Example 1), a magnetite was used as a magnetic powder, a red toner was similarly obtained, and a two-component developer was prepared.

When a similar image forming test was performed, a blackish red image was obtained, and the color tone was turbid due to magnetic powder.

(Example 6) Next, in (Example 2), spinel ferrite was used as the magnetic powder, a blue toner was similarly obtained, and a two-component developer was prepared.

Then, when a similar image forming test was performed, a blackish blue image was obtained, and a color tone image in which turbidity due to magnetic powder was observed.

[0088]

As described above, according to the image forming apparatus of the present invention, the developer is a two-component developer comprising a conductive magnetic carrier and an insulating magnetic toner, and is contained in the insulating magnetic toner. By using a two-component developer in which the magnetic powder is transparent or colorless, the electrostatic transfer of the toner image to plain paper is facilitated, and a good recorded image can be formed on various recording papers. As a result, a color toner can be obtained by using various colorants, whereby a clear, multi-colored recorded image having a clear color tone can be obtained. Further, since the magnetic powder is contained in the toner, there is an advantage that formation of a magnetic brush by a magnetic force, suppression of scattering of the toner in the apparatus, and recovery of the residual toner can be efficiently performed.

[0089]

[Brief description of the drawings]

FIG. 1 is a schematic view showing an electrophotographic method according to the present invention.

FIG. 2 is a configuration diagram of a main part of the electrophotographic method of the present invention.

FIG. 3 is a schematic view showing a surface conductive resin carrier according to the present invention.

FIG. 4 is a schematic view showing a surface conductive resin carrier according to the present invention.

[Explanation of symbols]

 2 Photoreceptor 7 LED head 8 Developing device 9 Transfer roller 10 Erase light source 12 Sleeve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/05 G03G 5/08 105-360 G03G 9/083 G03G 9/107

Claims (1)

(57) [Claims] 1. A light-transmitting support on the transparent conductive layer and Amorufu
Amorphous silicon-based carrier injection blocking layer and amorphous silicon
And Con type photoconductive layer and the surface layer and the sequentially stacked comprising photoreceptor, a developing unit which is disposed in the photoconductive layer side of the photoreceptor,
Means for applying a developing bias voltage between the sleeve of the developing means and the translucent conductive layer; and exposing means for irradiating light from the translucent support side to form an image on the photoconductor with a developer. developing Rutotomoni, and the photosensitive member is provided at the door
Developing by moving the means and the opposite direction at both nearest parts
Providing a developer reservoir and irradiating the developer reservoir with exposure means
An image forming apparatus according to claim 1 , wherein said developer is a two-component developer comprising a conductive magnetic carrier and an insulating magnetic toner, and said magnetic powder contained in said insulating magnetic toner is transparent or An image forming apparatus characterized by being colorless.