JP3142037B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus, and more particularly to an electrophotographic apparatus using an a-Si drum, such as a printer, a copying machine, and a facsimile.

[0002]

2. Description of the Related Art Conventionally, respective process means of exposure, development, transfer, cleaning (removal of residual toner), charge elimination and charging are arranged on the outer peripheral surface of a photosensitive drum, and an image is formed by a predetermined electrophotographic process. Electrophotographic apparatuses based on the so-called Carlson process are well known.

In this type of electrophotographic apparatus, charging is generally performed using corona discharge in order to uniformly charge the surface of a photoreceptor. Corona discharge generally requires application of a high voltage of 4 to 8 KV or more to a wire. Therefore, the corona discharge generates ozone and nitrogen oxides and ammonium salts, which are discharge products thereof, and these are adsorbed on the surface of the photoreceptor to easily cause image deletion. The image deletion is remarkable in a high humidity environment. On the other hand, in recent years, there has been a photosensitive drum used in an electrophotographic apparatus which uses an a-Si drum in order to improve durability and realize free maintenance. However, a-Si is compared with OPC and other organic semiconductors. As a result, the water absorption is high, so that the image flow is likely to occur in the a-Si drum. Therefore, in the prior art, a sheet heater or other heating element is disposed on the back side of the photosensitive drum, and the photosensitive drum is heated to prevent the occurrence of the image deletion. In the formation of the nitrogen oxides, a soft drum such as an OPC drum has its surface slightly scraped off by the rubbing of a cleaning blade for removing residual toner after transfer.
Since the system drum is hard, the above-mentioned disadvantages are likely to become apparent. For this reason, in the a-Si drum, the surface of the photosensitive drum has been polished using a polishing blade or a polishing roller to remove the products, thereby preventing the occurrence of image flow.

[0004]

As described above, a-S
Although the i-drum is harder and more durable than the organic semiconductor drum, in order to achieve the durability and free maintenance, the above-mentioned heater or the polishing means must be provided. The configuration becomes extremely complicated. In order to solve such a drawback, a roller charging method has been proposed in which a conductive roller is brought into contact with the photosensitive drum, and a DC voltage is applied to the conductive roller to perform contact charging of the photosensitive drum in a dark place. Exists. However, in such a charging method, since a minute wedge-shaped gap 102 exists between the photosensitive drum 100 and the charging roller 101 as shown in FIG. 2, a slight discharge phenomenon occurs in that portion, and generation of ozone is recognized. However, the above-mentioned disadvantages cannot always be solved.

[0005] In view of the drawbacks of the prior art, the present invention provides a
An object of the present invention is to provide an electrophotographic apparatus that can easily achieve durability and free maintenance without complicating the structure of an electrophotographic apparatus using a Si drum.

[0006]

SUMMARY OF THE INVENTION The present invention providesSupported by the substrate
An image carrier formed of an a-Si layer, and an image carrier near the image carrier.
Place the fixed magnet inside the non-magnetic sleeve
Supplying magnetic particles to the image carrier by rotation of the sleeve
A particle charging means for performing uniform contact charging;
A magnetic member positioned on the body, charged by the particle charging means.
While the conductive particles relatively move on the image carrier, the image
An electrophotographic apparatus configured to be able to rub against a carrierAtA support for the image carrier is formed of a non-magnetic material.
Position corresponding to the rubbing area of the magnetic particles on the back side of the support
A pair of magnetic poles of opposite polarity The magnetic field is formed by a horizontal magnetic field formed by the pair of magnetic poles.
The particles are brought into close contact with the image carrier, and the image carrier is slid.
The image carrier is charged by rubbing Also configured as possible
It is. AndIn the present invention, the charged particles are magnetic particles.
AndThe support of the image carrier is formed of a non-magnetic material
Together with the support back sideMagneticCorresponding to the rubbing area of particles
Position, a pair of magnetic poles of opposite polarity is arranged, and the magnetic poles
Due to the horizontal magnetic field formed, the particles are densely placed on the image carrier.
Dressing arrangementLet me.In this case,particleThe charging means is
Current bias or DC bias may be used
However, in the case of DC bias, the bias voltage is set to 600 V
It is better to set below.Further, the image bearing member is a photosensitive member.
A surface layer is formed on the layer and its surface, and a
Using an -SiC layer is also an effective means of the present invention.

[0007]

[Function] In the particle charging, charging is performed by injecting electric charge in a state in which fine particles are brought into close contact with the photosensitive drum, so that even when the charging bias voltage is set to a DC bias of 600 V or less, smooth charging is achieved. It is possible, and as a result, there is no room for generation of ozone and discharge products even if a DC bias is set. In the present invention, the charged magnetic particles are configured to be slidable while relatively moving on the image carrier, and preferably, the relative speed is maintained between the magnetic particles and the image carrier. With the configuration in which the rubbing is possible, even if the photosensitive drum absorbs water, the rubbing can remove water, and the image deletion is further prevented. In particular, according to the present invention, the above-described effect is further enhanced because the particle group is configured to be brought into close contact with the image carrier and slidable by the horizontal magnetic field. Further, by forming a surface layer on the photosensitive member layer and the surface of the image bearing member and using an a-SiC layer having a high resistance of an inorganic high resistance or an insulating material as the surface layer, the moisture resistance is enhanced, which is more preferable. The effect can be obtained.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Not just. FIG.
FIG. 1 shows an electrophotographic apparatus to which the present invention is applied, and an optical system including an exposure LED head 2 and a selfoc lens 3 around an a-Si photosensitive drum 1 rotating clockwise in FIG. , A two-component developing unit 4, a transfer roller 5, a cleaning blade 6, a neutralizing lamp 7, and a particle charging unit 8.

Next, each component will be described.
The photoconductor drum 1 includes a photoconductor layer 1b on a conductive support 1a,
The support 1a is generally formed of an aluminum cylindrical body, but is made of an inorganic material such as glass having a conductive film adhered to the surface, or a transparent material such as epoxy. It is formed of resin or the like, and in this embodiment, the thickness is 2
mm and the outer diameter is set to 30 mm, and 3 mm in the axial direction.
An aluminum cylinder having a length of 00 mm is used.

The a-Si photosensitive layer 1b and the surface layer 1c are formed by a glow discharge decomposition method, a sputtering method,
A film is formed by an R method, a vapor deposition method, and the like.
An element for terminating dangling bonds, for example, (H) or halogen is 5 to 40 wt. /%. That is,
The photoconductor layer 1b uses a photoconductor made of a-Si: H,
When the developing bias is positive, non-doped or Va group elements are included in order to increase the mobility of electrons, and when the developing bias is negative, the mobility of holes is increased.
It is preferable to include a group a element. If necessary, elements such as C, O, and N may be contained in order to obtain desired characteristics such as electric characteristics such as dark conductivity and photoconductivity, and optical band gap. The film thickness of the entire photoreceptor layer 1b is 2 to 25 in order to ensure necessary charging and dielectric strength, absorb exposed light, and suppress the above-described residual potential.
It is good to be about μm.

The surface layer 1c is made of a-SiC, a-Si
A such as O, a-SiN, a-SiON, a-SiCON, etc.
-It is preferable to use an Si-based inorganic high-resistance or insulating material, an organic insulating material such as polyethylene terephthalate, parylene, polytetrafluoroethylene, polyimide, and polyfluoroethylene propylene. Particularly, when a high-resistance a-SiC layer is used. In addition, characteristics such as dielectric strength, abrasion resistance, and environmental resistance are improved. The x value of a-Si _1-x C _x is set to 0.3 ≦ x <1.0, preferably 0.5 ≦ x ≦ 0.95, so that 10 ¹² to 10
High humidity resistance can be obtained with a resistance value in the range of ¹³ Ω · cm, and in this case, the C amount may have a gradient in the layer. Further, by containing N, O, and Ge simultaneously with C, the moisture resistance can be further improved.

The thickness of the surface layer 1c is preferably in the range of 0.05 to 5 μm, preferably 0.1 to 3 μm, and the thickness of the surface layer 1c is set to 10 ¹² to 10 ¹³ Ω · cm.
The exposure LED head 2 has an exposure wavelength of 740 nm.
A head array having a wavelength energy of 0.8 μJ / cm ² was used, and this was dynamically driven for 6 lines per scanning line.
It is configured to be able to perform 4 bits x 40 divided exposures.

The developing unit 4 comprises a developing container 41 in which a multi-component developer composed of a carrier and a toner is stored, and a developing roller 42 in which a fixed magnet assembly 43 is stored. The developing bias power supply 44 is connected to perform development.

The carrier has an average particle size of 70 μm.
Although the ferrite carrier described above was used, the carrier is not limited to this, and iron powder, a carrier such as magnetite, or a magnetic resin carrier may be used. The developing method may be a one-component developing method other than the two-component developing method.

As the toner, an ordinary high-resistance or insulating toner is used. For example, a magnetic substance is added to a binder resin, a coloring agent, a charge controlling agent, an anti-offset agent and the like, and the average central particle size is 5 to 15 μm. The carrier and the toner are configured as the front and rear magnetic toners, and an appropriate mixing ratio of the carrier and the toner is set to, for example, 85 to 90:15 to 10% by weight. The transfer roller 5 uses a conductive roller to increase the transfer efficiency, applies a transfer bias having a polarity opposite to the charging potential of the toner, and uniformly presses the transfer roller 5 against the peripheral surface of the photosensitive drum 1 to synchronize with the drum 1. To be rotatable.

The particle charging unit 8 has a charging gap (0.5 mm) with respect to the photosensitive drum 1 rotating rightward in FIG.
The non-magnetic sleeve 8 is rotatable in the rotational direction of the photosensitive drum 1 and the opposite direction (left direction in the figure) through the
1 and a fixed magnet body 82A fixedly disposed on the downstream side of the charging area on the back side of the non-magnetic sleeve 81, and on the upstream side of the charging area of the fixed magnet body 82A, in other words, on the downstream side in the sleeve rotation direction, A repulsion magnet body 82B having the same polarity as the fixed magnet body 82A, and a magnet body 82C having a polarity opposite to that of the fixed magnet body 82A are arranged on the upstream side in the sleeve rotation direction. Reference numeral 86 denotes a bias power supply for applying a charging bias to the conductive magnetic particle group 84 via the non-magnetic sleeve 81.

The conductive magnetic particles interposed on the charged area are not particularly limited as long as they are conductive. However, the conductive magnetic particles having a magnetic core such as ferrite, iron powder or magnetite coated on the surface with a conductive resin are used. Or a mixed particle group 84 of conductive particles and magnetic particles. For example, a magnetic particle base material having an average particle size of about 30 μm,
What mix | blends the conductive particle material with an average particle diameter of about 15 micrometers at an appropriate ratio may be used. In this example, ferrite core particles having an average particle diameter of 20 to 35 μm and a resistivity of 10 ⁵ to 10 ⁶ Ω · cm were used, and the magnetic characteristics were 60 to 70 emu.
/ G (1 k Oe).

On the other hand, on the back side of the photosensitive drum 1, a first magnet body 85A substantially facing the fixed magnet body 82A positioned downstream of the charging area, and a first magnet body 85A
A second magnet body 85B is arranged adjacent to the charging area upstream side adjacent to the first magnet body 85A, and the first magnet body 85A is set to an S pole having a polarity opposite to that of the fixed magnet body 82A, and is set between the fixed magnet body 82A and the fixed magnet body 82A. And a second magnetic body 85B.
Is set to an N pole having a polarity opposite to that of the first magnet body 85A, and forms a horizontal magnetic field on the photosensitive drum 1 between the two magnet bodies 85A and 5B.

In this embodiment, the magnetic particles 84 attached to the charged area of the photosensitive drum 1 are placed on the photosensitive drum on a horizontal magnetic field between the N-pole and S-pole magnets 85A and 85B. On the vertical magnetic field on the downstream side of the charged area deviating from the horizontal magnetic field, it adheres so as to stand in a rough state in the normal direction of the photosensitive drum 1. When the photoconductor drum 1 rotates in this state, the photoconductor drum moves from the horizontal magnetic field to the vertical magnetic field while charging the photoconductor drum on the horizontal magnetic field. The vertical magnetic field 6E escapes in the vertical direction without being conveyed to the downstream side by the non-magnetic force zone 6C formed on the photosensitive drum 1 by the repulsive magnetic field.

The magnetic particles 84 oriented in the vertical direction
Adheres to the sleeve 81 side due to the attractive force with the fixed magnet body 82A, and then is pulled back to the horizontal magnetic field 6A side on the upstream side of the charging area as the sleeve 81 rotates.
A non-magnetic force zone 6D is formed between the two magnetic poles 82A and 82B. As a result, the magnetic field moves from the horizontal magnetic field 6A to the vertical magnetic field 6B, and the magnetic particle group 84 is further conveyed to the downstream side by the non-magnetic force zone formed by the repulsion between the N-pole magnet body 82B and the fixed magnet body 82A. Without falling to the charging area side
Thereafter, the circulation is repeated. After the surface of the photosensitive drum 1 is smoothly charged while the magnetic particles 84 are brought into close contact with each other on the horizontal magnetic field, a predetermined latent image is exposed by the exposure head 2 and then the latent image is developed by the developing unit 4. After the toner image is attached, it can be transferred to the transfer roller 5.

Next, the photosensitive layer is coated with 30
μm and the surface layer is set to 1 μm, and the applied voltage of the charging bias power supply 86 is set to 250, 35
0 and 700V, respectively, and after printing 10,000 sheets first, 3
After leaving for 8 hours in an environment of 5 ° C. and 85% RH, the state of image flow after printing 100 sheets again was confirmed.
No image deletion occurred in any case. Next,
When a minute image flow was observed on each of the sheets with a 10 × magnifying glass, it was confirmed that although the applied voltage of the charging bias power supply 86 was 700 V, the first two sheets had a slight image flow. When the surface potential of the photosensitive drum was checked, it was 200 V when the applied voltage of the charging bias power supply 86 was 250 V, 300 V when the applied voltage was 350 V, and 650 V when the applied voltage was 700 V.

[0022]

As described above, according to the present invention, a
Even in an electrophotographic apparatus using a -Si drum, since image flow can be prevented without complicating the structure, durability and free maintenance can be easily achieved. In particular, the effect is further enhanced by lowering the charging bias voltage to 600 V or less of the DC bias. And so on.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a charging device according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor drum 2 Exposure head 3 Optical system, 4 Two-component developing unit 8 Charging device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-234063 (JP, A) JP-A-63-187267 (JP, A) JP-A-5-181347 (JP, A) JP-A 60-187 176069 (JP, A) JP-A-5-72782 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/02 G03G 15/09

Claims (3)

(57) [Claims] (1)Image formed by a-Si layer supported on substrate
A carrier, and a non-magnetic roller that rotates in close proximity to the image carrier;
A fixed magnet is placed in the sleeve and the magnetic particles are
Particle band for supplying uniform charge to the image carrier by supplying
The particles, wherein the particles are located on the image carrier.
The magnetic particles charged by the charging means move on the image carrier.
It is configured to be able to rub against the image carrier while relatively moving.
Electrophotographic equipmentAtA support for the image carrier is formed of a non-magnetic material.
Position corresponding to the rubbing area of the magnetic particles on the back side of the support
A pair of magnetic poles of opposite polarity The magnetic field is formed by a horizontal magnetic field formed by the pair of magnetic poles.
The particles are brought into close contact with the image carrier, and the image carrier is slid.
The image carrier is charged by rubbing What was configured
An electrophotographic apparatus characterized by the above-mentioned. 2. A charging bias applied to the particle charging means is set to a DC bias, and the charging bias is set to 6
2. The electrophotographic apparatus according to claim 1, wherein the voltage is set to 00 V or less. 3. An electrophotographic apparatus according to claim 1, wherein said image bearing member has a photosensitive layer and a surface layer formed on a surface thereof, and an a-SiC layer is used for said surface layer.