JPH10239946A - Electrifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the variation of resistance due to the change of distance from the power feed section to an electric discharge area in the case of supporting a cylindrical electrifying electrode in contact with the electric charge acceptor, to obtain uniform and stable potential by electrification, and to prevent the variation of the potential by the electrification due to the environmental change. SOLUTION: This electrifying device is provided with an insulating electrode supporting member 3 being held with the range away from the electric charge acceptor 1 for supporting the electrification electrode 2 so as to be held in contact with the electric charge acceptor 1. The power feed electrode 5 whose tip edge is formed so as to become a curved surface is supported while held in contact with the electrification electrode 2, on the outside of the electrification electrode 2. When a voltage is applied from the power feed electrode 5 to the electrification electrode 2, the electrification electrode 2 is attracted to the electric charge acceptor 1 by the electrostatic force, driven in accompany with the electric charge acceptor 1. In this time, the range from the contact part between the power feed electrode 5 and the electrification electrode 2 to the discharge area is maintained as specified, therefore the change of resistance is restrained. Moreover, it may be proper to provide the power feed electrode 5 so as to enable shifting in the peripheral direction of the electrification electrode 2 corresponding to the change of the temp. and the humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device which is used in an image forming apparatus such as a copying machine or a printer to which an electrophotographic method is applied and uniformly charges the surface of a photoreceptor which is a charge acceptor. In particular, the present invention relates to a charging device in which a charging electrode is provided so as to be in contact with a charge receptor.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer, the surface of a photoreceptor serving as a charge receptor is charged by a charging device, an electrostatic latent image is formed on the surface by irradiating image light, and a developer adheres. Makes this electrostatic latent image visible. Conventionally, as a charging device used in such an image forming apparatus, there are a non-contact charging system using corona discharge or the like and a contact charging system using a charging roller or the like using discharge in a minute gap.

In a charging device using corona discharge, a wire is stretched in a shield case so as to be close to or apart from the surface of a charge acceptor, and a high voltage is applied to the wire to cause corona discharge, thereby causing a charge acceptor. A predetermined charge is applied to the surface. Although such charging device is superior in uniform charging, disadvantages ozone, the process for discharging products such as NO _X is produced in large quantities is required, size of the apparatus, that tends to cause high cost There is. In addition, the electrode wire may be contaminated by dust in the air, toner, discharge products, fuser oil, or the like, resulting in non-uniform charging, which may cause a defect in an obtained image.

For this reason, recently, a contact charging type charging device has been used in which a charging electrode is brought into direct contact with a charge acceptor to perform charging. This charging device arranges a conductive elastic roller or brush in contact with the surface of the charge receptor, and applies a charging voltage to the conductive member to cause a discharge in a minute gap near the contact portion, It performs charging. In addition, as disclosed in JP-A-1-93760 and JP-A-2-282279, a blade-shaped charging electrode pressed against a charge receptor is used to remove residual toner and the like on the surface of the charge receptor. An apparatus that is also used as a cleaning blade to be removed is also known. Further, as disclosed in Japanese Patent Application Laid-Open No. Hei 4-249270, a charging device using a flexible film-shaped member as a charging electrode and disposing the leading end thereof in contact with the surface of a charge receptor is also known. I have. The charging device of this type has an advantage that the amount of ozone generated is extremely small because corona discharge is not used, and the device is suitable for miniaturization and weight reduction of the device because it is in contact with the charge receptor. ing.

[0005] However, among the above-mentioned contact type charging devices, those using a conductive elastic roller require a roller supporting device and the like, and have a drawback that the structure tends to be complicated. In addition, in order to perform uniform charging, it is necessary to improve the adhesion between the elastic roller and the charge acceptor to form a stable minute gap, and to take measures such as lowering the hardness of rubber. Therefore, a large amount of process oil must be contained in the rubber, and this process oil has a disadvantage that it tends to transfer to the charge acceptor and adversely affect the image quality. On the other hand, in order to solve such a defect, there is a method of increasing the outer shape accuracy of the roller. However, it is very difficult to increase the outer shape accuracy of rubber or the like, which leads to an increase in cost due to a decrease in yield and the like.

[0006] In the charging device using a conductive brush among the charging devices, it is easy to make the contact uniform as compared with the elastic roller, but it takes much time and effort to manufacture the brush, and the brush sweep is difficult. There is a drawback that images tend to appear on the image as uneven charging. Further, the method in which the blade-shaped charging electrode is also used as a cleaning blade has a drawback that it is difficult to achieve both the accuracy of cleaning and the setting of minute gaps required for discharge, and it is difficult to perform uniform and good charging. .

On the other hand, the use of a film-shaped charging electrode has the advantage that stable contact can be easily obtained with a simple structure as compared with other conductive members, and the manufacturing cost of the member is low. However, since the leading end of the film-shaped member comes into contact with the charge acceptor, a gap in which the discharge is performed is fluctuated due to frictional charging or vibration of the charging electrode, and the charging potential is likely to become unstable. Further, there is a disadvantage that foreign matters such as toner and external additives adhere to a contact portion between the film-shaped member and the charge receptor, and so-called creeping discharge causes streak-like charging failure. In order to improve such a defect, there is a method of applying a DC voltage in which an AC voltage is superimposed on a film-like member. And the problem that the wear of the charge receptor becomes remarkable. In addition, there is a drawback in that the film-shaped member vibrates according to the frequency of the alternating current, and a charging noise is generated. Further, when a DC voltage on which an AC voltage is superimposed is applied, there is a problem that charging efficiency is extremely low. For example, when calculating the energy consumption efficiency, the ratio of the electrostatic energy for charging the charge receptor to the power consumption energy of the charger is 0.5% for scorotron, and the charging is performed by applying a voltage obtained by superimposing an AC voltage on a DC voltage. The roll is 2.6%, and both have low efficiency.

In order to improve such low charging efficiency,
A charging device that charges a charge acceptor by applying a DC voltage by bringing a semiconductive charging electrode into contact with the charge acceptor has been studied again. However, in such a method, although the energy consumption efficiency is as large as 27.3%, the charging potential is uniquely determined by the discharge starting voltage and the resistance of the charging electrode. There is a drawback that the charging potential becomes non-uniform due to environmental changes in resistance and the like. In particular, the polymer material used as the surface material of the charging electrode has a property that the resistance varies by about 0.5 to 1 digit and varies by about 2 digits depending on the temperature and humidity of the atmosphere. Furthermore, since the charged electrode is pressed against the charge receptor and brought into contact therewith, dirt such as toner, discharge products, dust in the air, and paper dust easily adheres to the surface of the charged electrode. And unstable discharge occur, and image defects such as fogging are likely to occur. This instability against dirt is particularly noticeable when a DC voltage is applied,
There is also a fatal defect that non-uniform charging due to a large amount of dirt is unsuitable especially for an image forming apparatus aiming at high image quality.

Therefore, in order to avoid the above-mentioned disadvantages, there have been proposed charging devices disclosed in Japanese Patent Application Laid-Open Nos. Hei 4-232977 and Hei 5-72869. This charging device uses a charging electrode in which a flexible film-shaped member is formed in a cylindrical shape, and supports the charging electrode so as to be in contact with the peripheral surface of a supporting roller. To make contact. The peripheral surface of the charging electrode is moved endlessly by the rotation of the support roller, and the moving direction is set to be the same direction at the contact portion with the charge receptor. Further, in order to stably contact the charging electrode with the supporting roller, a pressing member for pressing the charging electrode against the peripheral surface of the supporting roller may be provided. Such a charging device has an advantage that frictional charging between the charging electrode and the charge receptor is minimized, and occurrence of charging failure due to vibration can be eliminated. Further, foreign substances such as toner are unlikely to adhere, and the occurrence of uneven charging can be reduced. Also,
Even if foreign matter adheres, the charged electrode rotates, so that it does not stay at the same position, so that it is possible to avoid the occurrence of a vertical stripe-like image quality defect.

[0010]

However, the charging devices described in Japanese Patent Application Laid-Open Nos. Hei 4-232977 and Hei 5-72869 have the following problems. In the above charging device, in order to make the contact between the charging electrode and the charge receptor uniform, it is necessary to reduce the thickness of the film as compared with the charging electrode described in JP-A-4-249270. However, there is a drawback that it is easily deformed. Therefore, there is a problem that the distance from the power supply electrode to the discharge region and the shape of the discharge region are likely to fluctuate, causing uneven charging potential.

That is, in the above-described charging device, the charging electrode is rotated by the electrostatic attraction with the charge acceptor, so that the power supply portion near the discharge region has large or small stiffness, eccentricity, film thickness, and straightness of the film. For example, due to the non-uniformity of FIG. For this reason, the resistance value viewed from the discharge region fluctuates, and the potential unevenness increases. Further, each time the charging electrode in the vicinity of the discharge region and the conductive supporting member are attached to or separated from each other, a transient change in capacitance occurs, so that high-frequency noise is further increased.

Further, when the charging electrode is pressed by the pressing member so as to be in close contact with the peripheral surface of the support roller, and the charging electrode is brought into contact with the charge receptor, a frictional force is generated between the pressing member and the charging electrode. Distortion occurs in the charged electrode that is driven to move endlessly, and the distribution of the contact pressure with the charge acceptor tends to be non-uniform. For this reason, there is also a problem that a uniform charging potential cannot be stably maintained. Also,
When a thin charging electrode is used as described above, the smaller the thickness of the electrode is, the more easily the electrode is damaged by dielectric breakdown. Therefore, a charging voltage supply method such as pressing against a charge receptor is not suitable. There is a major drawback.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to make it possible to prevent fluctuations in resistance with a simple configuration and to perform uniform and stable charging. In addition, it is another object of the present invention to prevent a change in the charged potential due to a change in the surrounding environment and to obtain a stable image quality for a long time.

[0014]

According to a first aspect of the present invention, there is provided a charging device according to the present invention, wherein a flexible semiconductive film-like member is formed in a substantially cylindrical shape. The charged electrode and the inside of the cylindrical charging electrode are held at a distance from the charged object, and the peripheral surface of the charged electrode is brought into contact with the charged object to move and the charged object and the charged object are moved. An insulating electrode support member that supports the charged electrode to move around by electrostatic force acting between the electrode and
A power supply electrode which is pressed almost uniformly in the width direction from the outside of the charging electrode, and which is supported so as to sandwich the charging electrode between the charging electrode and the electrode support member; And a power source for applying an electric potential. The power supply electrode is, for example, a plate-like member formed so that a leading edge is curved as in the invention described in claim 2, such that the leading edge contacts the charging electrode. It can be supported.

In such a charging device, an insulating electrode supporting member inserted into a charging electrode formed of a cylindrical film-shaped member and held with a gap from a member to be charged; And a power supply electrode that is supported so as to be sandwiched between the power supply electrode and the power supply electrode. The charging electrode is attracted to the side of the member to be charged, and the charging electrode rotates while being driven by the orbital movement of the member to be charged while being supported by the electrode support member. At this time, the power supply electrode is arranged so that the leading edge having a curved surface is pressed against the outside of the charging electrode in the width direction thereof, and the voltage is applied from a position distant from the member to be charged. Even if vibration occurs due to the magnitude of rigidity, eccentricity, unevenness in straightness, or the like, the position of the power supply unit in contact with the charging electrode does not change, and the distance from the power supply unit to the discharge region is kept constant. Therefore, the fluctuation of the resistance value viewed from the discharge region is suppressed, and the occurrence of potential unevenness is prevented. In addition, since the electrode support member is insulative, a change in the capacity between the charging electrode and the member to be charged in the vicinity of the discharge region is suppressed, and generation of high-frequency noise is prevented. For this reason, the charging potential can be stabilized, and the uniformity of the charging potential can be greatly improved.

Further, as the power supply electrode, in addition to the plate-shaped member, a roll-shaped member which is rotated or independently driven to rotate in accordance with the orbital movement of the charging electrode as described in claim 3 or claim 4. A brush-like member having conductive fiber hairs planted almost uniformly in the width direction of the charging electrode as described in (1) may be used. That is, even with the roll-shaped member or the brush-shaped member, the position of the power supply unit can be appropriately prevented from being changed, so that the same effect as described above can be obtained. Even when a conductive film-shaped member as described in claim 5 is used, the position of the power supply unit can be similarly prevented from being changed by appropriately adjusting the thickness of the film. Further, even in the case of using a rotatable roll-shaped brush having conductive fiber hairs planted therein, the position of the power supply unit can be similarly prevented from changing. The roll brush makes soft contact with the charging electrode,
In addition, since the rotation force is not hindered, stable charging can be performed for a long time.

Further, as in the invention described in claim 7, the position where the power supply electrode contacts the charging electrode is determined by the distance in the circumferential direction from the discharge start position between the charging electrode and the member to be charged.
It is desirable that the distance is set to be substantially equal to the circumferential distance from the discharge end position. That is, the member to be charged is charged while passing from the discharge start position to the discharge end position, but by making the circumferential distances equal,
It is possible to make the charged potential of the charged body substantially constant when passing through the discharge end position, and it is possible to further improve the uniformity of the charged potential.

Further, as in the invention described in claim 8, the power supply electrode is supported such that the contact position with the charging electrode is movable in the circumferential direction of the charging electrode, and the temperature and the temperature are controlled.
It is possible to adopt a configuration in which the position of the power supply electrode is controlled based on a detected value such as humidity. Generally, the charging property of a charging electrode is affected by the temperature or humidity near the charging device, so that the charging characteristics of the charged object with respect to the applied voltage also change. That is, in a low-temperature and low-humidity environment, there is a tendency that ionization of air is less likely to occur and charging is difficult than in a high-temperature and high-humidity environment. When the same voltage is applied, the charging potential of the member to be charged varies. For this reason, this environmental change often has an adverse effect on image quality. Therefore, the position of the power supply electrode is controlled as described above, and in a low-temperature and low-humidity environment, the distance from the contact portion with the charged electrode to the discharge region is short, and the power supply electrode is disposed at a position where the resistance of the charged electrode is small. In a wet environment, the distance from the contact portion with the charging electrode to the discharge region is long, and the charging electrode is arranged at a position where the resistance of the charging electrode increases. This makes it possible to prevent a decrease in the charging potential in a low-temperature and low-humidity environment and an increase in the charging potential in a high-temperature and high-humidity environment.
A uniform and stable charging potential can be obtained without being affected by environmental fluctuations.

Further, as in the ninth aspect of the present invention, a plurality of power supply electrodes are provided in the circumferential direction of the charging electrode, and the power supply selects one of the plurality of power supply electrodes and sets a potential. Can be provided. As a result, at low temperature and low humidity, the applied voltage is increased, and the distance between the contact area with the charged electrode and the discharge region is short, and the power supply electrode arranged so as to reduce the resistance of the charged electrode is used. In wet conditions, the applied voltage is reduced,
The power supply position and the applied voltage can be selected such that the power supply electrode arranged so that the distance from the contact portion with the charging electrode to the discharge region is long and the resistance of the charging electrode is large is used. For this reason, it is possible to prevent a change in the charging potential due to a change in the environment and to obtain a uniform and stable charging potential. Further, since there are a plurality of power supply electrodes, the rotation of the charging electrode is stabilized, and a more uniform charging potential can be obtained.

According to another aspect of the present invention, there is provided a charging device according to a tenth aspect of the present invention, comprising a flexible semiconductive film-shaped member supported to be in contact with a member to be charged. A charging electrode formed in a substantially cylindrical shape; and electrode supporting means including a plurality of brush-like members abutting substantially uniformly in a width direction of an outer peripheral surface of the charging electrode, wherein at least one of the brush-like members is provided. One has conductive fiber hairs, and a charging potential is applied to the charging electrode via the brush-like member. In such a charging device, by arranging the conductive brush-shaped member away from the member to be charged, it is possible to prevent a change in resistance value as viewed from the discharge region, and reduce the occurrence of potential unevenness.
Further, since the conductive brush-like member is in soft contact with the charging electrode, it is possible to prevent the charging electrode from being damaged. Further, foreign matter and dirt attached to the surface of the charged electrode can be scraped off by the brush, and the life of the charged electrode can be extended.

The eleventh aspect of the present invention provides the tenth aspect.
The charging device according to any one of the preceding claims, further comprising a roll-shaped member that abuts on a surface other than a contact portion between the charging electrode and the member to be charged, substantially uniformly in a width direction of an outer peripheral surface of the charging electrode. It is assumed that the shaped members are driven to rotate independently. In such a charging device, since the roll-shaped member is rotating while pressing the surface of the charging electrode, a foreign substance or the like is interposed between the charging electrode and the member to be charged, and even when the electrostatic attraction force is weakened,
The charged electrode can be rotated stably.

According to a twelfth aspect of the present invention,
Wherein the roll-shaped member is a roll-shaped brush on which conductive fiber hairs are planted, and is driven to rotate at a constant speed or a different peripheral speed from the charging electrode. In such a charging device, since the roll-shaped brush rotates while pressing the charging electrode,
Foreign matter and dirt attached to the surface of the charging electrode can be scraped off. Furthermore, even when foreign matter or the like is caught between the charging electrode and the charged object and the electrostatic attraction force is weakened, the charging electrode can be stably rotated. In addition, since the roll-shaped brush is in soft contact with the charging electrode, damage to the charging electrode can be prevented, and long-term use is possible.

According to a thirteenth aspect of the present invention, there is provided a charging device, comprising: a substantially semi-cylindrical charging electrode formed of a flexible semiconductive film-like member; The charged electrode is held at an interval from the member to be charged, the peripheral surface of the charging electrode is brought into contact with the member to be charged, and the charged electrode is moved by the electrostatic force acting between the member to be charged and the electrode. An insulative, substantially cylindrical electrode support member that is supported so as to move around; and a conductive member attached to the electrode support member, the width of which is substantially equal to the axial direction of the peripheral surface of the electrode support member. An exposed power supply electrode;
It has a pressing member arranged outside the charging electrode to press the charging electrode against the power supply electrode, and a power supply for applying a charging potential to the charging electrode via the power supply electrode. As a result, power can be stably supplied to the charging electrode from a fixed position, and the occurrence of potential unevenness can be more reliably prevented.

According to a fourteenth aspect of the present invention, there is provided a charging device comprising: a charging electrode in which a flexible film-shaped member is formed in a substantially cylindrical shape; and a charged object inside the cylindrical charging electrode. Is held at an interval, the peripheral surface of the charging electrode is brought into contact with the object to be charged, and the charged electrode is moved around by the electrostatic force acting between the moving object to be charged and the charged electrode. A power supply electrode that supports the charging electrode, and a power supply that applies a charging potential to the charging electrode via the power supply electrode, wherein the charging electrode has a low-resistance inner layer and a high-resistance outer layer. Shall be provided. In such a charging device, when a voltage is applied to the charging electrode from the power supply via the power supply electrode, a current flows through the low-resistance inner layer, and a high-resistance current flows near the contact between the charging electrode and the member to be charged. Discharge occurs via the outer layer. For this reason, even if the charging electrode vibrates and the distance from the power supply electrode to the discharge region changes, stable discharge can be generated, and a change in potential can be prevented. That is, by forming the high-resistance outer layer on the low-resistance inner layer, a state similar to that in which a capacitor is inserted is obtained, and an effect of equalizing high-frequency current fluctuations can be obtained.

According to a fifteenth aspect of the present invention, there is provided a charging device, comprising: a charging electrode in which a flexible semiconductive film-like member is formed in a substantially cylindrical shape; The charged electrode is held at a distance from the charged body, and the peripheral surface of the charged electrode is brought into contact with the charged body, and the charged electrode is moved by the electrostatic force acting between the moving charged body and the charged electrode. An insulative electrode supporting member that supports the charging electrode, and is disposed outside the charging electrode, contacts the charging electrode almost uniformly in the width direction thereof, and at the contact portion, the charging electrode and the electrode supporting member. And a power supply for applying a charging potential to the charging electrode via the power supply electrode, wherein the power supply electrode moves around the charging electrode. Rotation or independent rotation according to It is assumed that the roller members to be. In such a charging device, the power supply electrode is almost in non-contact or light contact with the charging electrode, but when the charged body starts rotating, the charged electrode comes into contact with the power supply electrode due to frictional force with the charged body. In addition, it becomes possible to charge an object to be charged by applying a charging voltage. At the same time, the charged electrode starts to rotate stably due to the electrostatic attraction acting between the charged object and the charged electrode. Therefore, sufficiently stable power supply can be achieved without sandwiching the charging electrode between the electrode support member and the power supply electrode.

A charging device according to a sixteenth aspect of the present invention is the charging device according to any one of the first to fifteenth aspects, wherein the charging electrode is a film having two or more layers. It is assumed that at least the outermost layer in contact with the member to be charged is formed of an ion conductive material. In such a charging device, since the outermost layer is formed of an ion conductive material, the capacitance component is larger than that of an electron conductive material that imparts conductivity by dispersing a conductive powder such as carbon, Is not in direct contact with the member to be charged, and there is no contact state in which no conductivity exists in the micro. Therefore, the charging current is stabilized, and occurrence of abnormal discharge can be prevented. It is also possible to supply power from the outer peripheral surface of the charging electrode.

The material of the charging electrode in the charging device may be any material having semiconductivity, such as polyester, polyamide, polyethylene, polycarbonate, polyolefin, polyurethane, polyvinylidene fluoride, and polyimide. , PEN, PE
K, PES, PPS, PFA, PVdF, ETFE, C
Resin such as TFE, or silicone rubber, EPDM,
Ethylene propylene rubber, butyl rubber, acrylic rubber,
Synthetic rubber such as urethane rubber or nitrile rubber mixed with conductive powder such as carbon black, metal powder, or metal oxide can be used. Alternatively, a polar rubber such as epichlorohydrin rubber, chloroprene rubber, EPDM rubber, or a semiconductive inorganic material such as titanium oxide or amorphous silicon may be formed by thin-film or thick-film deposition on an insulating substrate. However, since polar rubber and the like have a high adhesive force to foreign substances and the like, it is necessary to devise a method of coating the surface with a low-adhesion material or the like. Further, when a thin film or a thick film is deposited, the hardness is high.

[0028] At this time, it is necessary to adjust the mixing amount of the conductive particles such that the preferred volume resistivity, 10 ² Omega
· Spark discharge easily occurs in cm or less, 10 ¹¹ Ω · c
m or more tends to cause dot-like charging failure,
It is desirable to use in the range of 0 ³ Ω · cm to ^{10 10} Ω · cm. In particular, at 10 ³ Ω · cm to 10 ⁶ Ω · cm,
The charging voltage applied to the charging device can be set relatively low, and the process speed can be set to 150 mm / s.
When used in a high-speed machine with a speed of ec or more, it is most preferable because potential fluctuation can be reduced.

The charging voltage applied to the charging electrode may be either a DC voltage or a voltage obtained by superimposing an AC voltage that is twice or more the charging start voltage on the DC voltage. However, a voltage in which an AC voltage is superimposed on a DC voltage increases the surface energy of the surface of the member to be charged and the surface of the charging device, and further adversely affects the member to be charged.

The material of the power supply electrode for supplying a charging voltage to the charging electrode may be any material having conductivity, such as polyester, polyamide, polyethylene, polycarbonate, polyolefin, polyurethane, and polyfluoride. Vinylidene, polyimide, PE
N, PEK, PES, PPS, PFA, PVdF, ET
It is possible to use resin such as FE or CTFE or synthetic rubber such as silicone rubber, ethylene propylene rubber, butyl rubber, acrylic rubber, urethane rubber, nitrile rubber mixed with conductive powder such as carbon black or metal powder. it can. Further, a polar rubber such as epichlorohydrin rubber, chloroprene rubber, EPDM rubber, or a semiconductive inorganic material such as amorphous silicon may be formed by vapor-depositing a thin film or a thick film on an insulating substrate. However, since a polar rubber or the like has a high adhesive force, it is necessary to devise a method of coating the surface with a low-adhesion material or the like.
Further, the material is not limited to the above-described polymer materials, and may be, for example, a metal such as SUS, aluminum, and brass, water,
Conductive liquids such as alcohols and liquid metals can also be used. However, when a conductive liquid is used, a mechanism for preventing the liquid from adhering to and scattering on the charged electrode and the like and evaporating is required.

The shape of the power supply electrode may be any shape as long as it can come into contact with the front surface or the back surface of the charging electrode. paddle,
A rotating body such as a block or a roll made of gel, resin, metal, or the like, or a brush-like member that reciprocates is preferably used. However, depending on the shape of the charging device,
In some cases, it is desirable that the pressure at the contact portion be small, and a brush, felt, nonwoven fabric, sponge, roll, or the like is suitably used.

As the image forming apparatus in which the charging device according to the present invention is incorporated, a black-and-white, color copying machine, printer, or the like provided with a conventional photoconductor (charging target) cleaning device is suitable. Further, the present invention can be suitably used even when a cleanerless image forming apparatus having no cleaning device or a pseudo cleaning device is provided.

[0033]

Next, an embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a charging device according to an embodiment of the invention described in claim 1 or 2, wherein FIG. 1 (a) is a sectional view and FIG. 1 (b) is a side view. . The charging device 10 is supported at a position facing the charge receptor 1 that can move in a certain direction, and is formed by forming a semiconductive film member into a cylindrical shape so as to have a peripheral surface that can move endlessly. It has an electrode 2 and a cylindrical electrode support member 3 inserted into the charging electrode 2 and supporting the charging electrode 2 so as to be in contact with the charge receptor 1.
Further, a power supply electrode 5 connected to a DC power supply 4 is provided, and is supported such that the charging electrode 2 is sandwiched between the power supply electrode 5 and the electrode support member 3.

The charge acceptor 1 has, for example, a structure in which a photoconductive layer 1a is laminated on a cylindrical conductive substrate 1b, and the conductive substrate 1b is electrically grounded. Then, a discharge is generated in a minute gap near the contact portion with the charging electrode 2, so that the surface of the charge receptor 1 is charged.

The charging electrode 2 is formed such that the peripheral length of the film-shaped member is larger than the peripheral length of the electrode supporting member 3.
When no voltage is applied, as shown in FIG. 1, it is in contact with the charge receptor 1 by its own weight. When a voltage is applied to the charging electrode 2, the charging electrode 2 is pressed against the charge receptor 1 by an electrostatic force generated between the charging electrode 2 and the charge receptor 1, and rotates following the rotation of the charge receptor 1. It has become. The operation of the charging electrode 2 will be described later.

As the film-like member constituting the charging electrode 2, a flexible semiconductive member having a thickness of about 30 to 200 μm is used. This film-shaped member, for example, polyester, polyamide, polyimide,
It is formed by mixing conductive particles such as carbon black in a film made of a polymer material such as polyethylene, polycarbonate, polyolefin, polyurethane, polyvinylidene fluoride, and acrylic. The amount of particles mixed has been adjusted. In this case, the spark discharge is likely to occur in the volume resistivity is less 10 ² Omega · cm, and is easy to cause dot-like charge failure in 10 ¹¹ Omega · cm or more, 10 ³ to 1
It is desirable to use in the range of 0 ¹⁰ Ω · cm. Especially 10
A charging voltage of ³ to 10 ⁶ Ω · cm is preferable in that the charging voltage to be used can be set relatively low, and power consumption can be saved. Further, in consideration of direct contact with the charge receptor 1, the impression elastic modulus is set to about 10 to 280 kg / mm ² . In the above example, a flexible film tube having a thickness of 50 μm and a volume resistivity of 10 ⁵ Ω · cm obtained by mixing carbon black with polycarbonate is used.

The electrode support member 3 is formed in a roll shape from an insulating material, and is made of, for example, polyester, polyamide, polyimide, polyethylene, polycarbonate, or the like.
Polymer materials such as polyolefin, polyurethane, polyvinylidene fluoride, acrylic, POM, phenol, and fluorine, and a metal shaft inside to increase the strength, and the surface is made of the above insulating material are suitable. Used for In the above example, a roll-shaped member having a polyurethane resin layer formed around a metal shaft is used. The electrode support member 3 is provided slightly longer than the entire length in the longitudinal direction of the charging electrode 2 as shown in FIG. 1B, and is fixed and supported in the charging device so as not to rotate.

The power supply 4 can apply a DC voltage to the charging electrode 2 in the charging step of the charge receptor 1. Also,
This power supply may be set to apply a voltage obtained by superimposing an alternating current on a direct current. The applied voltage of the power supply 4 will be described later.

The power supply electrode 5 is formed of a plate-like member formed so that the front end edge is curved, and is supported such that the front end edge is pressed almost uniformly from the outside of the charging electrode 2 in the width direction thereof. ing. The power supply electrode 5 is formed of a conductive material so as to supply a charging voltage to the charging electrode 2. For example, a metal such as aluminum or SUS, or a volume resistivity equal to or less than the volume resistivity of the charging electrode 2. A conductive polymer material or the like formed so as to be used is used. Also,
The force applied to the power supply electrode 5 is preferably in a direction toward the vicinity of the center of the electrode support member 3, and its magnitude is larger than the electrostatic attraction force acting between the charging electrode 2 and the charge receptor 1. Smaller is better. In the above example, the power supply electrode 5 is made of aluminum.

In such a charging device, when a predetermined voltage is applied to the charging electrode 2 from the power supply 4 via the power supply electrode 5, the charging electrode 2 is placed between the charging electrode 2 and the charge receptor 1 as shown in FIG. Due to the generated electrostatic force, the charge receptor 1 is pressed against the side of the charge receptor 1 and moves in a certain direction, so that the charge receptor 1 rotates following the charge receptor 1. At this time,
The charging electrode 2 comes into contact with the charge receptor 1 at a constant contact pressure while being supported by the electrode support member 3, and has a shape that swells in the movement direction near the contact portion with the charge receptor 1. At this time, the voltage applied to the charging electrode 2 causes a discharge in a minute gap near the contact portion between the charging electrode 2 and the charge receptor 1, and ionization of air occurs. When the negative electrode of the power supply 4 is connected to the power supply electrode 5, negative ions or electrons flow toward the charge acceptor 1 and charge it, and positive ions reach the charge electrode 2 and are neutralized. You.

Since the charging electrode 2 has a sufficiently large resistance, the discharge is stable and does not lead to fireworks discharge. In addition, since a semiconductive resistor is used for the charging electrode 2, any portion of the gap is excessively large. A large amount of current can be prevented from flowing, and the charge receptor 1 can be uniformly charged.

Next, the results of a charging test conducted by using the charging device shown in FIG. 1 and a charging test device as shown in FIG. 2 will be described. This charging test apparatus includes a surface potential sensor 11 for detecting a surface potential of the charge receptor 1 around a drum-shaped charge receptor 1 rotating in the direction of an arrow, and a charge removing lamp for removing the surface charge of the charge receptor 1. And a surface potential meter 12 is connected to the surface potential sensor 11. A charging device 10 having the configuration shown in FIG. 1 is arranged on the upstream side of the surface potential sensor 11 in the rotation direction of the charge receptor 1, and the conductive charging electrode 2 is supported so as to contact the surface of the charge receptor 1. ing. DC power supply 1
4 is connected, and a DC charging voltage is applied. The DC power supply 14 is capable of arbitrarily changing the output voltage, and measures the surface potential of the charge receptor 1 that changes with the increase or decrease of the applied voltage by the surface voltmeter 12.

The film-shaped charging electrode 2 used in the charging device 10 has a volume resistivity of 1 by mixing carbon black into each of PVdF, nylon, and polycarbonate.
It is a flexible film tube adjusted in three stages of 0 ³ , 10 ⁵ , and 10 ⁷ Ω · cm, and the thickness is 30 μm, 50 μm
Set to. Also, a thin cylindrical charging electrode having a thickness of 500 μm was used. The inner diameter of the charging electrode 2 is 12.5 m
m, and the electrode support member 3 was φ11 mm. The power supply electrode 5 was made of brass.

FIG. 3 shows the relationship between the applied voltage and the surface potential of the charge receptor 1 when a DC voltage is applied to the charging electrode 2 in a charging test using the charging test apparatus shown in FIG. It is. In FIG.
Charge receptor 1 when a DC voltage of -2000 V is applied
When the surface potential of the charge acceptor 1 was measured, the surface potential of the charge receptor 1 started to increase from an applied voltage of about -550 V, and was -2000.
It was confirmed that the applied voltage of V reached about -1450V. During this time, no abnormal discharge was generated by the charging device 10. As for the material of the charging electrode 2, the volume resistivity, and the thickness of the film, good results were obtained in all the above cases.

When the shape of the charging electrode 2 was observed when the charge receptor 1 was rotating, the shape was almost the same as that in FIG. 1 when no voltage was applied, but the applied voltage was increased. At about -200 V, it started to rotate following the charge acceptor 1 and stably rotated to -2 kV. At this time, the charging electrode 2 is in contact with the charge receptor 1 due to the electrostatic force, but is pulled in the rotational direction by the movement of the charge receptor 1. As shown, the shape is such that it swells in the rotational direction. This phenomenon was more conspicuous in thin and soft film tubes of 30 μm and 50 μm in thickness compared to a thin cylindrical electrode of 500 μm in thickness.

Next, the results of measurement of the potential fluctuation on the surface of the charge receptor using the charging test apparatus shown in FIG. 2 are shown. In this experiment, for comparison, as shown in FIG. 4, the same measurement was performed for a conventional charging device in which power was supplied from an electrode support member that was close to and opposed to the charge acceptor. The charging device shown in FIG. 4, which is a comparative example, is a seamless device having a thickness of about 30 to 200 μm and a volume resistance of 10 ³ to 10 ¹⁰ Ω · cm, similarly to the charging device of the present embodiment shown in FIG. The charge electrode 202 using a semiconductive film tube is connected to the charge receptor 2.
No. 01 is arranged. The charging electrode 202 is supported by a conductive electrode supporting member / feeding electrode 203 that is arranged at a distance from the charge acceptor 201. The cylindrical charging electrode 202 is lightly in contact with the charge receptor 201 by its own weight, and when a voltage is applied, rotates in the direction of the arrow by the electrostatic attraction force with the charge receptor 201 to hold the charge receptor 201 in a predetermined direction. To the potential of.

FIG. 5 is a diagram showing the charging potential of the charge receptor in the above two charging devices with time. This figure 5
In contrast, in the conventional charging device shown in FIG. 4, the potential unevenness of about 23 V is generated, whereas in the charging device of the present embodiment, the potential unevenness is hardly changed to about 5 V, and the potential unevenness is greatly improved. You can see that it is done. Further, in the charging device shown in FIG. 4, in addition to the large potential unevenness generated in each cycle of the film-shaped charging electrode, high-frequency unevenness occurs. Has not occurred. The mechanism of such an effect by the charging device of the present embodiment will be described with reference to FIG.

That is, in the conventional charging device shown in FIG. 4, since the charging electrode is rotated by the electrostatic attraction with the charge receiving member, unevenness in film rigidity, eccentricity, film thickness, and straightness is caused. 6A, the position of the film-shaped electrode fluctuates as shown by the solid line and the broken line in FIG. 6A, and the power supply portion near the discharge region (the end of the contact region between the film-shaped charging electrode 202 and the power supply electrode 203). Part) changes from C to D. For this reason, the resistance value viewed from the discharge region fluctuates, and the potential unevenness increases. Further, since the charging electrode 202 and the conductive electrode support member 203 near the discharge region are attached to or separated from each other, both gaps change within the range of the hatched area shown in FIG. Will fluctuate. Therefore, high-frequency noise is further increased. However, in the present embodiment, since a voltage is applied from the outside of the charging electrode 2 by the power supply electrode 5 formed so that the leading edge has a curved surface, the voltage from the contact portion between the power supply electrode 5 and the charging electrode 2 to the discharge region is increased. The distance can be kept almost constant, and the fluctuation of the resistance can be suppressed. Also, by making the electrode support member 3 insulating,
It is possible to reduce the fluctuation of the capacity near the discharge region. For the above two reasons, a more stable charging potential can be obtained. From the above, it can be seen that in the charging device of the present embodiment, the uniformity of the charging potential is greatly improved.

Next, the results of confirming the image quality of each of the above film-shaped charging electrodes using the image forming apparatus shown in FIG. 7 will be described. This image forming apparatus includes a photoconductor (charge acceptor) 20 on which a latent image is formed by irradiating image light after uniform charging, and the surface of the photoconductor 20 is charged around the photoconductor 20. In addition to the charging device 10 of the embodiment shown in FIG. 1, an exposure device 21, a developing device 22, a transfer roller 25, a cleaning device 27, and a discharging lamp 28 are provided. Further, the apparatus is provided with a paper cassette 23 for storing paper 24 and a fixing device 26 for fixing a toner image.

In such an image forming apparatus, the charging device 1
After the photosensitive member 20 is charged to a predetermined potential by 0, the exposure device 21 irradiates laser light corresponding to the image information to form an electrostatic latent image on the surface of the photosensitive member 20. This electrostatic latent image is developed by the developing device 22 to form a visible image due to toner adhesion. At the same time, the paper 24 is transported from the paper cassette 23 along the paper guide 29 between the photoconductor 20 and the transfer roller 25, and the toner image on the photoconductor 20 is transferred by the transfer roller 25. Is transferred onto the sheet 24. The transferred toner image is fixed by the fixing device 26, and a print image is formed on the paper 24. On the other hand, the untransferred toner remaining on the photoconductor 20 with the rotation of the photoconductor 20 is cleaned by the cleaning device 27,
After the surface of the photoconductor 20 is neutralized by the neutralization lamp 28, the charging process by the charging device 10 is started again. Note that the voltage applied to the charging device 10 in the above-described process includes-
A DC voltage of 900 V is set, whereby the surface potential of the charge receptor 1 becomes approximately -350 V.

A print image is formed using such an image forming apparatus, and the results of charging tests of the charging device 10 of the present embodiment and the conventional charging device shown in FIG. 4 are shown in FIG.
Shown in Here, FIGS. 8A and 8B are print images when both charging devices are driven in a normal temperature to high temperature and high humidity environment. FIGS. 8C and 8D are print images. 3 shows a print image when both charging devices are driven in a low-temperature and low-humidity environment. As shown in FIG. 5, the conventional charging device shown in FIG. 4 has a large potential fluctuation as shown in FIG.
While image quality defects such as fogging and density unevenness occur in the cycle of the outer diameter of the film-shaped charging electrode, it was confirmed that the charging device of the present embodiment can provide a good image without image quality defects. Further, in the charging device shown in FIG. 4, the power supply portion, which is an electrode support member, is arranged close to the photoreceptor. As shown in (1), the discharge became non-uniform, and abnormal dot-like discharge occurred. However, according to the charging device of the present embodiment, since the distance from the power supply unit to the discharge region can be sufficiently long, stable charging can be performed even when the resistance value of the charging electrode is relatively low. This has the advantage that a good image can be obtained as shown in FIG.

FIG. 9A is a schematic configuration diagram showing a charging device according to one embodiment of the present invention. The charging device is substantially the same configuration as the charging apparatus shown in FIG. 1, different from the position of the feeding electrode 35a, the distance in the circumferential direction from the discharge start position A ₁ between the charging electrode 32 and the charge receptor 31 When, at a position substantially equal and the circumferential direction of the distance from the discharge end position a _2, the feeding electrode 35a
Are supported so as to be in contact with the charging electrode 32. The power supply 34 is a DC power supply of -900 V, which is the same as that of the charging device shown in FIG. The other configuration of the charging device is the same as that of the charging device shown in FIG.

In such a charging device, the charge acceptor 31
In the position facing the charging electrode 32, but charged is during passage through the discharge end position A ₂ from the discharge start position A _1, the circumferential direction from the discharge start position A ₁ and the discharge end position A ₂ to the feeding electrode 35a by substantially equal distances, the surface potential of the charge receptor 31 as it passes through the discharge end position a ₂ can be made substantially uniform. For this reason, it is possible to more reliably prevent the fluctuation of the charging potential.

As shown in FIG. 9B, a DC power supply 36 and an AC power supply 37
Connect the circumferential distance from the discharge start position B _1, with approximately equal position in the circumferential direction of the distance from the discharge end position B _2, the feeding electrode 35b is configured so as to contact the charging electrodes 32 You can also. The voltage applied from the power supplies 36 and 37 is, for example, a DC component of -350 V and an AC component as a peak-to-peak voltage of 1.5 kV and a frequency of 170 Hz.
The voltage on which the in-wave is superimposed is set. Thus, when a voltage obtained by superimposing an alternating current to direct current is also the charging potential of the charge receptor 31 as it passes through the discharge end position B ₂ it can be made substantially uniform, to prevent variation of the charging potential be able to.

FIG. 10 is a schematic structural view showing a charging device according to an embodiment of the third aspect of the present invention.
10A is a sectional view, and FIG. 10B is a side view. This charging device is provided with a power supply electrode 45 made of a rotatable roll-shaped member instead of the power supply electrode 5 used in the charging device shown in FIG. The power supply electrode 45 is an EPD
By dispersing carbon in M, the volume resistivity becomes 1
This is a conductive rubber roll formed to have a resistance of about 0 ³ Ω · cm, and a metal shaft is inserted at the center. The power supply electrode 45 is pressed against the charging electrode 42 with a force F in the direction of the arrow shown in the figure, and is supported so as to be driven while contacting the charging electrode. In order to stabilize the rotation of the charging electrode 42, the magnitude of the force F is preferably smaller than the electrostatic attractive force acting between the charging electrode 42 and the charge receptor 41. As the charging electrode 42 and the electrode support member 43, the same charging device as that shown in FIG. 1 is used.
While rotating in the direction of the arrow in the figure while touching the surface. The other structure of the charging device is the same as that of the charging device shown in FIG.

In such a charging device, when a voltage is applied to the charging electrode 42 via the power supply electrode 45, the charging electrode 42 is charged by the electrostatic force with the charge receptor 41.
1 and pulled in the direction of its movement,
The charge receptor 31 rotates following the orbital movement. At the same time, the power supply electrode 45 also rotates following the rotation of the charging electrode 42.

Using such a charging electrode, a charging test was performed by a charging test apparatus shown in FIG.
It was confirmed that good results were obtained as in the case of the charging device shown in FIG. In addition, a print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image free from image quality defects such as fog was obtained. Also,
Since the power supply electrode 46 is formed using a conductive rubber material, the power supply electrode 46 can be softly contacted with the charging electrode 42, and thus has the effect of not easily damaging the electrode surface.

In the above-described embodiment, the power supply electrode 46 is configured to rotate following the charging electrode 42. However, when a driving device is connected to the power supply electrode and the power supply electrode 46 rotates at the same speed as the charge receptor 41, the power supply electrode 46 rotates. It was confirmed that power could be supplied stably without hindering the rotation of the electrode, and that better charging uniformity could be obtained. In addition, when the power supply electrode was formed of EPDM rubber with high friction and the same test was performed, the charging electrode was able to rotate stably even under the condition that the charging voltage was low and the rotating force due to the electrostatic attraction was weak. It was confirmed that good charge uniformity was obtained.

FIG. 11 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention. This charging device is different from the power supply electrode 5 used in the charging device shown in FIG. 1 in that a power supply electrode 55 made of a brush-like member having conductive fiber hairs planted almost uniformly in the width direction of the charging electrode 52 Is provided. The power supply electrode 55 is made of a conductive material adjusted to be smaller than the volume resistance of the charging electrode 52. In this example, the volume resistance value is adjusted by mixing carbon black into the rayon. Is 10 ³ Ω
A conductive brush formed to have a size of about cm is used. The material of this brush-like power supply electrode is
The material is not limited to rayon, and any material such as polyester and nylon can be used as long as it can be formed into a fibrous form. The charging electrode 5
Reference numeral 2 is the same as the charging device shown in FIG. 1, and rotates in the direction of the arrow in the figure while contacting the charge receptor 51 by electrostatic attraction. The other configuration of the charging device is the same as that of the charging device shown in FIG.

Using such a charging device, a charging test was performed by the charging test device shown in FIG.
As a result, good results were obtained as in the charging device shown in FIG. Also,
A print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image without image quality defects such as fog was obtained. Further, since the power supply electrode 55 is in soft contact with the surface of the charging electrode 52, there is also an effect that stable charging can be performed for a long time without damaging the surface of the charging electrode.

FIG. 12 is a schematic structural view showing a charging device according to an embodiment of the present invention. In this charging device, instead of the power supply electrode 5 used in the above-described charging device shown in FIG. The film-shaped member is supported so as to be in contact with the charging electrode 62 on the curved surface. The power supply electrode 65 is made of a conductive material adjusted to be smaller than the volume resistivity of the charging electrode 62. In this example, carbon black is mixed into polycarbonate to reduce the volume efficiency to 10 ³ Ω.
A film-like member having a thickness of about 50 μm adjusted to cm is used. The same charging device as the charging device shown in FIG. 1 is used as the charging electrode 62, and the charging electrode 62 rotates while being in contact with the charge receptor 61 by an electrostatic attraction force. The other configuration of the charging device is the same as that of the charging device shown in FIG.

Using such a charging device, a charging test was performed by the charging test device shown in FIG.
As a result, good results were obtained as in the charging device shown in FIG. Also,
A print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image without image quality defects such as fog was obtained. Further, since the power supply electrode 65 is in soft contact with the surface of the charging electrode 62, FIG.
As in the charging device shown in FIG. 1, stable charging can be performed for a long period without damaging the surface of the charging electrode 62.

FIG. 13 is a schematic structural view showing a charging device according to an embodiment of the present invention. This charging device is a roll-shaped supporting device in which the contact position with the charging electrode 72 is movable in the circumferential direction of the charging electrode instead of the fixed power supply electrode 5 used in the charging device shown in FIG. Are provided. This power supply electrode 75
Is connected to a movable member 77 via a support rod 78 above the charging electrode 72, and the movable member 77 slides on a rail 76 fixedly supported in the apparatus, thereby forming a periphery of the charging electrode 72. It moves on the surface. And
The surrounding temperature and humidity are detected by a sensor (not shown), and the driving of the movable member 77 is controlled based on the detected temperature and humidity, and the movement of the power supply electrode 75 is adjusted so that the contact portion between the power supply electrode 75 and the charging electrode 72 is at an appropriate position. It is controlled. The position of the power supply electrode 75 is controlled as follows.

Since the charging property of the charging electrode is affected by the temperature or humidity near the charging device, the charging characteristics shown in FIG. 3 also change. In a low-temperature and low-humidity environment, air is less likely to be ionized than in a high-temperature and high-humidity environment. For this reason, this environmental change often has an adverse effect on image quality. In the present embodiment, in order to suppress such potential fluctuation, at low temperature and low humidity, FIG.
As shown by the solid line in the figure, the position of the power supply electrode 75 is controlled so that the distance from the contact portion with the charging electrode 72 to the discharge region A is shortened, and the resistance of the charging electrode is set to be small. Further, at high temperature and high humidity, as indicated by a dotted line in FIG.
The position of the power supply electrode 75 is controlled so that the distance from the contact portion with the charging electrode 72 to the discharge region A is long, and the resistance of the charging electrode is set to be large. The other configuration of the charging device is the same as that of the charging device shown in FIG.

In such a charging device, the power supply position can be controlled according to the surrounding environment, and the fluctuation of the charging potential due to changes in temperature and humidity can be suppressed. When a charging test using the charging device shown in FIG. 2 was performed using such a charging device, stable charging characteristics were exhibited from a high-temperature and high-humidity environment to a low-temperature and low-humidity environment. Improved. In addition, a print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image free from image quality defects such as fog was obtained.

FIG. 14 is a schematic structural view showing a charging device according to an embodiment of the present invention. This charging device includes, in place of the power supply electrode 5 and the power supply 4 used in the charging device shown in FIG.
An applied voltage switching device 86 for selecting one of the power supply electrodes and applying a potential thereto and three power sources 84 are provided.
The power supply electrodes 85a, 85b, and 85c are made of a conductive rubber roll having the same configuration as the power supply electrode 45 shown in FIG.
It is supported so as to be driven to rotate while being in contact with the charging electrode 82 with a force F in the direction of the arrow shown in the figure.

The power supply 84 includes an applied voltage switching device 86
Are connected to the power supply electrodes 85 via the power supply electrodes 85, and different charging electrodes are independently applied to the three power supply electrodes 85, respectively. The applied voltage switching device 86 is configured to always be able to select one type of applied voltage and the power supply electrode 85 by a detection signal (not shown) based on detected values such as temperature and humidity. In the present embodiment, at low temperature and low humidity, the applied voltage is increased, the distance from the contact portion with the charging electrode 82 to the discharge region is short, and the power supply electrode 85a arranged so as to reduce the resistance of the charging electrode is used. At high temperature and high humidity, the applied voltage is reduced, the distance from the contact portion with the charging electrode 82 to the discharge region is long, and the power supply electrode 85c arranged so as to increase the resistance of the charging electrode is used. . The power supply electrode 85b is set to be used in a normal environment. The other configuration of the charging device is the same as that of the charging device shown in FIG.

Using such a charging device, a charging test was performed by the charging test device shown in FIG. 2. As a result, stable charging characteristics were exhibited from a high-temperature, high-humidity environment to a low-temperature, low-humidity environment, and the difference in charging potential was 5 V. Improved to the following. In addition, a print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image free from image quality defects such as fog was obtained. Furthermore, since there are a plurality of power supply electrodes 85, when one power supply electrode is supplying power to the charging electrode 82, the other two contact the charging electrode 82 with the charge receptor 81 to stabilize rotation. Since it plays a role as a conversion member, it also has the effect of achieving a more uniform charging potential.

FIG. 15 is a schematic diagram showing a charging device according to an embodiment of the present invention. This charging device has a cylindrical charging electrode 92 having a peripheral surface on which a semiconductive film-shaped member can move endlessly, and the charging electrode 92 is inserted and fixed so as to cover the outside of the charging electrode. And a supported frame 97. Further, the brush-like power supply electrode 95 connected to the power supply 94
7, and a brush-shaped electrode support member 93 for preventing the charging electrode 92 from moving in the frame 97 is mounted inside the frame 97.
Then, the charging electrode 92 is brought into contact with the brush-like power supply electrode 95 and the brush-like electrode support member 93, whereby
It is supported so as to be in contact with the charge acceptor 91.

As the charging electrode 92, the same charging device as that shown in FIG. 1 is used. The charging electrode 92 is driven to rotate in the direction of the arrow in FIG. It has become. The power supply electrode 95 is a conductive brush formed by mixing carbon black into rayon so that the volume resistance becomes about 10 ³ Ω · cm. Is adhered to the frame body 97 in a slightly laid shape. The material of the brush-like power supply electrode 95 is not limited to rayon, but may be any material such as polyester or nylon as long as it can be formed into a fibrous shape. The electrode support member 93 is a brush-like member formed of rayon, nylon, or the like in a fibrous shape, and, like the power supply electrode 95, is adhered to the frame in a shape slightly laid in the rotation direction. The frame body 97 may be formed of any material as long as it is an insulating material. For example, polyester, polyamide, polyimide, polyethylene, polycarbonate, polyolefin, polyurethane, polyvinylidene fluoride, acrylic, POM,
Polymer materials such as phenol and fluorine are preferably used. Further, in the case where the charge acceptor 91 is installed at a sufficient distance so as not to be discharged, a conductive material such as polyester, polyamide, polyethylene, polycarbonate, polyolefin, polyurethane, in addition to the above-mentioned insulating material. , Polyvinylidene fluoride, polyimide, PEN, P
EK, PES, PPS, PFA, PVdF, ETFE,
Resin such as CTFE or synthetic rubber such as silicone rubber, ethylene propylene rubber, butyl rubber, acrylic rubber, urethane rubber and nitrile rubber mixed with conductive powder such as carbon black or metal powder can be used. Further, a polar rubber such as epichlorohydrin rubber, chloroprene rubber, EPDM rubber, or a semiconductive inorganic material such as amorphous silicon may be formed by vapor-depositing a thin film or a thick film on an insulating substrate. The other configuration of the charging device is the same as that of the charging device shown in FIG.

Using such a charging device, a charging test was performed by the charging test device shown in FIG.
As a result, good results were obtained as in the charging device shown in FIG. Also,
A print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image without image quality defects such as fog was obtained. In addition, since the power supply electrode 95 is formed of a conductive brush, the power supply electrode 95 can be softly contacted with the charging electrode 92, and thus has the effect of not easily damaging the electrode surface. Furthermore, a brush-like electrode support member 93
Has the effect of scraping off foreign matter and dirt attached to the charging electrode 92, and thus has the characteristic that the life of the charging device is prolonged. Further, since the function of regulating the position of the charging electrode 92 is high, and the power supply electrode 95 and the electrode support member 93 also have the effect of stabilizing the rotation of the charging electrode 92, more stable rotation is performed, and It was confirmed that excellent charging uniformity was obtained.

In this embodiment, a brush-like member is used inside the frame 97. However, the present invention is not limited to this shape. For example, sponge, felt, non-woven fabric,
The same effect can be obtained by using a blade, a plate member having high smoothness, or the like.

FIG. 16 is a schematic structural view showing a charging device according to an embodiment of the present invention. This charging device has a cylindrically formed charging electrode 102 having a peripheral surface on which a semiconductive film-shaped member can move endlessly,
It has an insulating cylindrical electrode support member 103 that is inserted into the charging electrode 102 and supports the charging electrode 102 so as to be in contact with the charge receptor 101. Also, the power supply electrode 105 made of a conductive member is
The power supply electrode 1 is installed so as to be embedded in a part of the
05 is exposed. Further, on the outside of the charging electrode 102, a rotation stabilizing member 106 for controlling the deflection of the cylindrical film so that the charging electrode 102 rotates stably is arranged. Is pressed against the power supply electrode 105. In order to stabilize the rotation of the charging electrode 102, the magnitude of the force F
It is better that the force is smaller than the electrostatic attraction force acting between the charge receptor 02 and the charge receptor 101. As shown in FIG. 17, the location where the rotation stabilizing member 106 is disposed is one rotation direction relative to a line connecting the charge acceptor 101 and the center of the electrode support member 103.
A position of 20 ° is most desirable, but it may be installed in a range of 90 ° to 180 °. In this case, the rotation stabilizing member 10
When 6 is driven, the rotation of the charging electrode 102 becomes even smoother.

As the charging electrode 102, the same charging device as that shown in FIG. 1 is used. The charging electrode 102 rotates in the direction of the arrow in FIG. It has become. Feeding electrode 1
Numeral 05 is made of a conductive material adjusted to be smaller than the volume resistivity of the charging electrode 102. For example, polyester, polyamide, polyethylene, polycarbonate, polyolefin, polyurethane, polyvinylidene fluoride, polyimide, PEN , PEK, PES, PP
Resins such as S, PFA, PVdF, ETFE, CTFE,
Alternatively, synthetic rubber such as silicone rubber, ethylene propylene rubber, butyl rubber, acrylic rubber, urethane rubber, nitrile rubber or the like mixed with conductive powder such as carbon black or metal powder can be used. Also,
Epichlorohydrin rubber, chloroprene rubber, EPDM
It is also possible to use a polar rubber such as rubber. Further, the rotation stabilizing member 106 can use an insulating or conductive material, and can use the material used for the charging electrode or the electrode supporting member in the above-described embodiment. In the above example, the power supply electrode 1
As 05, a resin obtained by mixing carbon black into polycarbonate is used. As the rotation stabilizing member 106, urethane rubber is used. The other configuration of the charging device is the same as that of the charging device shown in FIG.

Using such a charging device, a charging test was performed by the charging test device shown in FIG.
As a result, good results were obtained as in the charging device shown in FIG. Also,
A print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image without image quality defects such as fog was obtained. In addition, the rotation stabilizing member 1
In addition, since the charging electrode 102 is rotated stably by the setting of 06, there is also an effect that a uniform charging potential is obtained.

In this charging device, the roll-shaped rotation stabilizing member 106 is used. However, the present invention is not limited to this shape. You may. However,
If the load of the rotation stabilizing member is too large, the rotation of the charging electrode becomes unstable, causing slippage with the charge acceptor.
Must be adjusted appropriately.

FIG. 18 is a schematic structural view showing a charging device according to an embodiment of the present invention. The charging device includes a charging electrode 112 formed in a cylindrical shape so as to have a peripheral surface on which a semiconductive film-shaped member can move endlessly,
It has a cylindrical power supply electrode 113 that is inserted into the charging electrode 112 and supports the charging electrode 112 so as to be in contact with the charge receptor 111. The charging electrode 112
Are the lower resistance inner layer 112a and the higher resistance outer layer 112b
And is supported so as to be in contact with the power supply electrode 113 by the low resistance inner layer 112a and to be in contact with the charge receptor 111 by the high resistance outer layer 112b. The material for forming the film-shaped electrode shown in the above embodiment can be used for the low-resistance inner layer 112a constituting the charged electrode, but the material for forming the high-resistance outer layer 112b is epichlorohydrin rubber chloroprene rubber Polar rubbers such as EPDM rubber are preferred. In this example, epichlorohydrin rubber is used as the charging electrode, and the inner layer 11
The low volume efficiency of 2a is 10 ³ Ω · cm, the low volume efficiency of the outer layer 112b is 10 ¹⁰ Ω · cm, and the thickness is 50 μm each.
Is set to Since the polar rubber has a high adhesive force, the surface of the outer layer 112b is coated with a low adhesive material.

The power supply electrode 113 is formed of a cylindrical conductive roll, and is connected to a power supply 114 for applying a DC voltage. The material of the power supply electrode 113 may be any material as long as it has conductivity, for example, polyester, polyamide, polyethylene, polycarbonate, polyolefin, polyurethane, polyvinylidene fluoride, polyimide, PEN, PEK, PES. , PP
Resins such as S, PFA, PVdF, ETFE, CTFE,
Alternatively, synthetic rubber such as silicone rubber, EPDM, urethane rubber, ethylene propylene rubber, butyl rubber, acrylic rubber, and nitrile rubber mixed with conductive powder such as carbon black, metal powder, and metal oxide can be used. . Further, the surface of the electrode molded with the above material, coated with a paint made conductive by adding a conductive filler such as carbon black or metal powder, metal oxide to a polymer binder such as acrylic or epoxy, metal or An elastic rod of a thin hollow pipe made of resin or the like, on which a film whose resistance is adjusted such as titanium oxide or a-Si to which impurities are added is formed, and furthermore, the thin hollow pipe itself has conductivity. Those possessed can also be used effectively. The other configuration of the charging device is the same as that of the charging device shown in FIG.

In such a charging device, when a voltage is applied from the power supply 114 to the charging electrode 112 via the power supply electrode 113, a current flows through the low resistance inner layer 114a,
Discharge occurs near the contact portion between the high-resistance outer layer 112b and the charge acceptor 111 via the outer layer 112b. At the same time, the charging electrode 112 is charged by the electrostatic force generated between the charge receptor 111 and the charging electrode 112.
11 and rotates following the circular movement of the charge acceptor 111. In such a charging device, even if the charging electrode 112 vibrates and the distance from the contact portion with the power supply electrode 113 to the discharge region changes, stable discharge can be performed, and fluctuation of the charging potential can be prevented. . This is because the lower resistance inner layer 112a is shifted from the higher resistance outer layer 112
This is because, by performing the discharge through b, a state similar to the state where the capacitor is inserted is obtained, and there is an effect of equalizing the high-frequency current fluctuation.

When a charging test was carried out using such a charging device using the charging test device shown in FIG. 2, a substantially uniform potential was obtained with little change in the charging potential.
In addition, a print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image free from image quality defects such as fog was obtained. Further, since a voltage is applied by the power supply electrode 113 disposed inside the charging electrode 112, the charging layer 112b has an effect that stable charging can be performed for a long time without damaging the outer layer 112b of the charging electrode. .

The outer layer 112b shown in FIG. 18 can be made of a material having ionic conductivity, as described in claim 16. In this case, the inner layer 1b is formed.
It is possible to make the resistivity almost the same as 12a. Examples of the material having ionic conductivity include a modified polymer such as denatured nylon, a material obtained by mixing an ionic conductive material such as lithium perchlorate in urethane or the like, or a polymer having an ether bond to increase conductivity. What has been provided can be used. The outer layer 112 is made of such a material.
By constituting b, the capacitance component is larger than that of an electron conductive material that imparts conductivity by dispersing conductive powder such as carbon, and the conductive powder comes into direct contact with the charge acceptor, and the micro conductivity is reduced. Since there is no contact state that does not exist, there is an effect that the charging current is stabilized and abnormal discharge hardly occurs. Also, as shown in FIG. 1, even if power is supplied from the outer peripheral surface of the charging electrode, a sufficient effect can be exhibited.

FIG. 19 is a schematic structural view showing a charging device according to an embodiment of the present invention. The charging device includes a charging electrode 122 formed in a cylindrical shape so as to have a peripheral surface on which a semiconductive film member can move endlessly;
It has an insulating cylindrical electrode support member 123 that is inserted into the charging electrode 122 and supports the charging electrode 122 so as to be in contact with the charge receptor 121. Further, at a position facing the outer peripheral surface of the charging electrode 122, the power supply electrode 1 made of a conductive member is spaced from the electrode support member 123.
A DC power supply 124 is connected to the power supply electrode 125. The power supply electrode 125 also has a role of controlling the bending of the cylindrical film so that the charging electrode 122 rotates stably.

As the charging electrode 122, the same charging device as that shown in FIG. 1 is used. The charging electrode 122 contacts the charge receptor 121 by the electrostatic attraction force and moves in the direction of the arrow in FIG. It is designed to rotate. The power supply electrode 125 is made of a conductive material adjusted to be smaller than the volume resistivity of the charging electrode 122, and can be made of the same material as the power supply electrode 105 shown in FIG. The electrode support member 123 is made of an insulating material, and can be made of the same material as the electrode support member 3 shown in FIG. In the above example, the power supply electrode 125 is formed of brass in a roll shape, and the electrode support member 123 is formed of polycarbonate. The other configuration is the same as the charging device shown in FIG.

When such a charging device is used, FIG.
As shown in (a), when the charging voltage is not applied and the charge receptor 121 is stationary, the charging electrode 122
And the power supply electrode 125 make almost non-contact or light contact, but when the charge receptor 121 starts to rotate in the direction of the arrow in FIG. 19B, the charging electrode 122 contacts the charge receptor 121. It is pushed rightward in the figure by the frictional force and comes into contact with the power supply electrode 125, a charging voltage is applied, and the charge receptor 121 can be charged. Thereafter, the charging electrode 122 starts to rotate stably due to electrostatic attraction acting between the charge receptor 121 and the charging electrode 122. Therefore, sufficiently stable power supply is possible without sandwiching the charging electrode 122 between the electrode support member 123 and the power supply electrode 125.

At this time, an upward force F is applied to the charging electrode 122 in FIG.
5, so that a uniform charging potential can be obtained. If the power supply electrode 125 is installed in another place, the charging electrode 122 has a shape as shown by a broken line in the figure, and the rotation becomes slightly unstable. The effect due to the balance of the forces is greatest when the power supply electrode 125 is installed at a position as shown in FIG.
Further, by independently rotating the power supply electrode 125, the rotation of the charging electrode 122 becomes more stable, so that a more uniform charging potential can be obtained.

Using such a charging device, a charging test was performed by the charging test device shown in FIG.
As a result, good results were obtained as in the charging device shown in FIG. In addition, a print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image free from image quality defects such as fog was obtained. This charging device can be particularly suitably used in a cleanerless image forming apparatus described later.

FIG. 20 is a schematic structural view showing a charging device according to an embodiment of the present invention. This charging device comprises a roll-shaped brush member in which conductive fiber hairs are planted substantially uniformly in the width direction of the charging electrode 132, instead of the feeding electrode 5 used in the charging device shown in FIG. 135 is provided.

The power supply electrode 135 is made of a conductive material adjusted to be smaller than the volume resistivity of the charging electrode 132. In this example, the power supply electrode 135 is made of the same fiber as the power supply electrode 55 shown in FIG. The formed conductive brush roll is used. The power supply electrode 135 is configured to rotate in the same direction as the moving direction of the charging electrode 132 at a portion facing the charging electrode 132. The same charging device as the charging device shown in FIG. 1 is used as the charging electrode 132. The charging electrode 132 rotates in the direction of the arrow in FIG. The other configuration of this charging device is the same as that of the charging device shown in FIG.

Using such a charging device, a charging test was performed by the charging test device shown in FIG.
As a result, good results were obtained as in the charging device shown in FIG. In addition, a print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image free from image quality defects such as fog was obtained. Further, the power supply electrode 1
Since the roller 35 is softly in contact with the surface of the charging electrode 132 and is independently driven so as not to hinder its rotational force, it also has the effect that stable charging can be performed for a long time. This charging device can be particularly suitably used in a cleanerless image forming apparatus described later.

FIG. 21 is a schematic structural view showing a charging device according to an embodiment of the present invention. The charging device has a charging electrode 142 formed in a cylindrical shape so as to have a peripheral surface on which a semiconductive film member can move endlessly,
A frame 147 fixedly supported so as to cover the outside of the charging electrode 142 with the charging electrode 142 interposed therein;
And a roll 148 that is in contact with the outer peripheral surface of the charging electrode 142 at a position on the opposite side and that is independently driven to rotate.
The roll 148 is inserted into an opening provided at a position of the frame 147 opposite to the charge receptor 141 and is rotatably supported. Further, a brush-like power supply electrode 145 connected to the power supply 144 is mounted inside the frame 147, and is formed in a brush shape to prevent the charging electrode 142 from moving inside the frame 147. The electrode support member 143 is mounted inside the frame 147. The charging electrode 142 is supported so as to be in contact with the charge receptor 141 by being in contact with the brush-shaped power supply electrode 145, the brush-shaped electrode support member 143, and the roll 148.

As the charging electrode 142, the same charging device as that shown in FIG. 1 is used. The charging electrode 142 is driven by an electrostatic attraction to rotate in the direction of the arrow in the figure while contacting the charge receptor 141. It is supposed to. The power supply electrode 145 is a conductive brush formed by mixing carbon black into rayon to have a volume resistance of about 103 Ω · cm, similarly to the power supply electrode 95 of FIG. As the electrode support member 143 and the frame body 147, the same members as those in FIG. 15 are used. The roll 148 is made of a conductive or insulating material, for example, polyester, polyamide, polyethylene, polycarbonate, polyolefin, polyurethane, polyvinylidene fluoride, polyimide, PEN, PE
K, PES, PPS, PFA, PVdF, ETFE, C
Resins such as TFE or synthetic rubbers such as silicone rubber, ethylene propylene rubber, acrylic rubber, urethane rubber and nitrile rubber mixed with conductive powder such as carbon black and metal powder can be used. Also, epichlorohydrin rubber, chloroprene rubber, EP
A polar rubber such as DM rubber or a semiconductive indefinite material such as amorphous silicon may be formed by depositing a thin film or a thick film on an insulating substrate. In the case of insulation, polyester, polyamide, polyimide, polyethylene, polycarbonate, polyolefin, polyurethane, polyvinylidene fluoride, acrylic, POM, phenol, fluorine and other high polymer materials, and metal shaft inside to increase strength However, a material whose surface is made of the above insulating material is preferably used. The other configuration of this charging device is the same as that of the charging device shown in FIG.

Using such a charging device, a charging test was performed by the charging test device shown in FIG.
As a result, good results were obtained as in the charging device shown in FIG. In addition, a print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image free from image quality defects such as fog was obtained. Further, the brush-like electrode support member 143 and the power supply electrode 145 are
Since there is also an effect of writing off foreign substances and dirt attached to the surface of No. 2, there is also a feature that the life of the charging device is prolonged. Further, since the roll 148 is constantly rotating while pressing the charging electrode 142, even when foreign matter or the like is caught between the charging electrode 142 and the charge receptor 141, the electrostatic attraction force is weakened. Has the effect that it can rotate stably.

In this embodiment, a brush-like member is used inside the frame 147. However, the present invention is not particularly limited to this shape. May be used. Further, when the roll 148 is conductive, the power supply 1
44 may be connected to a roll 148, and the power supply electrode 145 may be made of the same material as the electrode support member 143 which is a rotation stabilizing member.

FIG. 22 is a schematic structural view showing a charging device according to an embodiment of the present invention. The charging device includes a charging electrode 152 formed in a cylindrical shape so as to have a peripheral surface on which a semiconductive film-shaped member can move endlessly;
A frame 157 fixedly supported so as to cover the outside of the charging electrode by inserting the charging electrode 152 therein;
And a brush-shaped roll 158 which is in contact with the outer peripheral surface of the charging electrode 152 at a position opposite to the above and which is independently driven to rotate. Further, a brush-like power supply electrode 155 connected to the power supply 154 is mounted inside the frame 157,
An electrode support member 153 formed in a brush shape for preventing the charging electrode 152 from moving inside the frame 157 is mounted inside the frame 157. And the charging electrode 1
The brush 52 is supported so as to be in contact with the charge receptor 151 by being brought into contact with the brush-like power supply electrode 155, the brush-like electrode support member 153, and the brush-like roll 158 at three points.

As the charging electrode 152, the same charging device as that shown in FIG. 1 is used. The charging electrode 152 is driven by an electrostatic attraction to rotate in a direction indicated by an arrow in FIG. It is supposed to. The power supply electrode 155 is a conductive brush formed by mixing carbon black into rayon to have a volume resistance of about 103 Ω · cm, similarly to the power supply electrode 95 of FIG. The same electrode supporting member 153 and frame 157 as those in FIG. 15 are used. The brush-like roll 158 is made of a conductive or insulating material, and can use the same fiber hair as either the power supply electrode 155 or the electrode support member 153. The other configuration of this charging device is the same as that of the charging device shown in FIG.

Using such a charging device, a charging test was performed by the charging test device shown in FIG.
As a result, good results were obtained as in the charging device shown in FIG. In addition, a print test was performed using the image forming apparatus shown in FIG. 7, and it was confirmed that a good image free from image quality defects such as fog was obtained. In addition, the brush-like electrode support member 153, the power supply electrode 155, and the brush-like roll 158 have an effect of writing off foreign matters and dirt attached to the surface of the charging electrode 152, and thus have a feature that the life of the charging device is extended. . Furthermore, a brush-like roll 1
Since the rotating member 58 is constantly rotating while pressing the charging electrode 152, even when foreign matter or the like is caught between the charging electrode 152 and the charge receptor 151, the charging electrode 152 is stable even when the electrostatic attraction force is weakened. It also has the effect of being able to rotate. In addition, since all the elements that come into contact with the surface of the charging electrode 152 are brushes, the surface is hardly damaged, and the surface can be used for a long time.

[0097] The brush-like roll 158 is
Although the above-described effect can be obtained even when it is rotated at the same peripheral speed as that of the charging electrode 1, in particular, by providing the peripheral speed,
The rotation of 52 is stabilized, and the effect of cleaning the surface is also improved. Also, if you rotate while reciprocating in the axial direction,
The effect is further enhanced.

In this embodiment, a brush-like member is used inside the frame 157. However, the present invention is not limited to this shape. May be used. Further, when the brush-like roll 158 is conductive, the power supply 154 is connected to the brush-like roll 158, and the power supply electrode 155 is connected to the electrode support member 15 which is a rotation stabilizing member.
It is also possible to use the same material as 3.

Next, an example of the use of the charging device according to the above-described embodiment, and an image forming apparatus using the charging device will be described. FIG. 23 is a schematic configuration diagram showing an image forming apparatus in which the charging device 10 shown in FIG. 1 is incorporated, according to an embodiment of the invention described in claim 17. This image forming apparatus is substantially the same as the image forming apparatus shown in FIG.
As shown in FIG. 3, the charging device 10 charges the untransferred toner, which has not been completely transferred by the transfer device 25, on the charge receptor 20. Such an image forming apparatus has various advantages such as a long life, such as a reduction in the size of the apparatus due to the absence of waste toner, and the prevention of wear of the charge receptor 20 by the cleaning blade. However, since there is a high possibility that the charging device 10 is contaminated with the untransferred toner, the surface resistance increases, charging failure or the like easily occurs, and the life of the charging device is shortened.

The charging device according to the present invention can be suitably used for such an image forming apparatus. In particular, FIG.
The charging device shown in FIG. 0, FIG. 14, FIG. 16, FIG. 19, FIG. 20, FIG. 21, or FIG. In addition, since the independent driving roller is in contact with the outer peripheral surface, even if the electrostatic attraction force is weakened by untransferred toner or the like, the charged electrode can rotate stably without slipping. Therefore, even if the frictional force between the charge receptor 20 and the charging electrode changes due to the environment or aging, stable charging can be performed.

When a print test was performed on the charging device shown in FIGS. 10, 14, 16, 19, 20, 21, and 22 using the image forming apparatus shown in FIG. No good images were obtained. In addition, it was confirmed that even when an experiment was performed by increasing the amount of untransferred toner, the toner stably rotated and a uniform charging potential was obtained.

Accordingly, it was confirmed that the charging device according to the present invention can obtain a good charging potential even in a cleanerless image forming apparatus. The configuration of the cleaner-less image forming apparatus is not limited to that shown in FIG. 23, and may include a simulated cleaning device such as a cleaning roll, or may transfer finer particles than toner onto the charge receptor to transfer efficiency. It can also be used for a device that raises the pressure.

[0103]

As described above, according to the present invention,
Since it is possible to minimize the change in resistance due to the change in the distance from the charging voltage application unit to the charging electrode to the discharge region, it is possible to obtain a uniform charging potential. Further, since a complicated additional device or the like is not incorporated, the device can be configured as a small and lightweight device, and cost reduction can be realized. Furthermore, even if the ambient temperature and humidity change, a stable potential can be obtained by controlling the distance from the charging voltage application unit and the applied voltage, realizing a charging device with excellent environmental resistance. it can.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a charging device according to an embodiment of the invention described in claim 1 or 2;

FIG. 2 is a schematic configuration diagram showing a charging test device for performing a charging test of the charging device.

FIG. 3 is a view showing test results of the charging device shown in FIG. 1 and showing a relationship between a DC voltage applied to the charging device and a surface potential of a charged charge receptor.

FIG. 4 is a schematic configuration diagram showing a conventional charging device as a comparative example of the charging device.

FIG. 5 is a diagram showing test results of the charging device shown in FIG. 1 and showing the surface potential of the charge receptor over time.

6 is a diagram showing a behavior of a charging electrode near a discharge region in the charging device shown in FIG.

FIG. 7 is a schematic configuration diagram showing an image forming apparatus in which the charging device shown in FIG. 1 is used.

FIG. 8 is a diagram showing an example of an image obtained by using the image forming apparatus shown in FIG. 7;

FIG. 9 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention described in claim 1, 2 or 7;

FIG. 10 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 11 is a schematic configuration diagram showing a charging device according to an embodiment of the invention described in claim 4;

FIG. 12 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 13 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 14 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 15 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 16 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 17 is a view showing a position where a rotation stabilizing member used in the charging device shown in FIG. 16 is provided.

FIG. 18 is a schematic configuration diagram showing a charging device according to an embodiment of the invention described in claim 14;

FIG. 19 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 20 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 21 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 22 is a schematic configuration diagram showing a charging device according to an embodiment of the present invention.

FIG. 23 is a schematic configuration diagram showing a cleanerless image forming apparatus using the charging device shown in FIG. 1;

[Explanation of symbols]

1, 31, 41, 51, 61, 71, 81, 91 Charge acceptor 2, 32, 42, 52, 62, 72, 82, 92 Charging electrode 3, 33, 43, 53, 63, 73, 83, 93 Electrode support member 4, 34, 44, 54, 64, 74, 84, 94 DC power supply 5, 35a, 35b, 45, 55, 65, 75 Power supply electrode 10 Charging device 11 Surface potential sensor 12 Surface potential meter 13 Static elimination lamp 14 DC power supply 20 Photoconductor 21 Exposure device 22 Developing device 23 Paper cassette 24 Paper 25 Transfer roll 26 Fixing device 27 Cleaning device 28 Static elimination lamp 29 Paper path 36 DC power supply 37 AC power supply 76 Rail 77 Movable member 78 Support rods 85a, 85b, 85c Power supply electrode 86 Applied voltage switching device 95 Power supply electrode 97 Frame 101, 111, 121, 131, 1 41, 151
Charge acceptors 102, 112, 122, 132, 142, 152
Charging electrode 103, 123, 133, 143, 153 Electrode support member 104, 114, 124, 134, 144, 154
Power 105,125,135,145,155 feeding electrode 106 rotation stabilizing member 113 feeding electrodes 147, 157 frame 148 roll 158 rolled brush A _1, B ₁ discharge start position A _2, B ₂ discharge end position A discharge area

Claims (16)

[Claims] 1. A charging electrode in which a flexible semiconductive film-like member having a flexibility is formed in a substantially cylindrical shape, and a charging member which is held inside the cylindrical charging electrode at a distance from an object to be charged, An insulating electrode support member for supporting the charged electrode in such a manner that the peripheral surface of the charged electrode is brought into contact with the object to be charged and the charged electrode is moved around by the electrostatic force acting between the object to be charged and the charged electrode A power supply electrode that is pressed almost uniformly in the width direction from the outside of the charging electrode and is supported so as to sandwich the charging electrode between the electrode supporting member and the power supply electrode. And a power supply for applying a charging potential to the charging device. 2. The charging device according to claim 1, wherein the power supply electrode is a plate-shaped member formed such that a leading edge is curved, and the leading edge is in contact with the charging electrode. A charging device, which is a charging device. 3. The charging device according to claim 1, wherein the power supply electrode is a roll-shaped member that is rotated or independently driven to rotate according to the circumferential movement of the charging electrode. 4. The charging device according to claim 1, wherein the power supply electrode is substantially evenly arranged in a width direction of the charging electrode.
A charging device comprising: a brush-like member having conductive fiber hairs planted thereon. 5. The charging device according to claim 1, wherein the power supply electrode is a conductive film-shaped member. 6. The charging device according to claim 1, wherein the power supply electrode is a roll-shaped brush on which conductive fiber hairs are planted, and is driven to rotate or independently rotated according to the orbital movement of the charging electrode. A charging device, comprising: 7. The charging device according to claim 1, wherein the position at which the power supply electrode contacts the charging electrode is a discharge start position between the charging electrode and the member to be charged. And a circumferential distance from the discharge end position is substantially equal to a circumferential distance from the discharge end position. 8. The charging device according to claim 1, wherein the power supply electrode is supported such that a contact position with the charging electrode is movable in a circumferential direction of the charging electrode. A charging device, comprising: 9. The charging device according to claim 1, wherein a plurality of the power supply electrodes are provided in a circumferential direction of the charging electrode, and the power supply is the plurality of power supply electrodes. A charging device for applying a potential by selecting one of the charging devices. 10. A charging electrode which is formed so as to be in contact with an object to be charged and which has a flexible semi-conductive film-like member formed in a substantially cylindrical shape, and substantially in the width direction of an outer peripheral surface of the charging electrode. Electrode supporting means having a plurality of brush-like members abutted evenly, and at least one of the brush-like members has conductive fiber bristle, and through this brush-like member A charging device, wherein a charging potential is applied to the charging electrode. 11. The charging device according to claim 10, wherein the roll is brought into substantially uniform contact with a surface other than a contact portion between the charging electrode and the member to be charged in a width direction of an outer peripheral surface of the charging electrode. A charging device having a shape member, wherein the roll member is independently driven to rotate. 12. The charging device according to claim 11, wherein the roll-shaped member is a roll-shaped brush on which conductive fiber hairs are planted, and is driven to rotate at a constant speed or a different peripheral speed from the charging electrode. A charging device, comprising: 13. A charging electrode in which a semiconductive film member having flexibility is formed in a substantially cylindrical shape, and the charging electrode is held inside the cylindrical charging electrode at a distance from an object to be charged, and An insulative, substantially cylindrical shape that contacts the peripheral surface of the charging electrode with the member to be charged and supports the charging electrode to move around by the electrostatic force acting between the moving member to be charged and the charging electrode. An electrode supporting member, a conductive member attached to the electrode supporting member, a power supply electrode exposed at a width substantially equal to an axial direction of a peripheral surface of the electrode supporting member, and a power supply electrode disposed outside the charging electrode. A charging device, comprising: a pressing member for pressing the charging electrode against the power supply electrode; and a power supply for applying a charging potential to the charging electrode via the power supply electrode. 14. A charging electrode in which a flexible film-shaped member is formed in a substantially cylindrical shape, and a charging member which is held inside the cylindrical charging electrode at a distance from a charged body, and is provided around the charging electrode. A power supply electrode that supports the charged electrode so that the charged electrode orbits by an electrostatic force acting between the moving charged object and the charged electrode by bringing a surface into contact with the charged object; And a power supply for applying a charging potential to the charging electrode via an electrode, wherein the charging electrode has a low-resistance inner layer and a high-resistance outer layer. 15. A charging electrode in which a flexible semiconductive film-like member having a substantially cylindrical shape is formed, and the charging electrode is held inside the cylindrical charging electrode at a distance from an object to be charged, and An insulating electrode support member that supports the charged electrode in such a manner that the peripheral surface of the charged electrode is brought into contact with the object to be charged and the charged electrode is moved around by the electrostatic force acting between the object to be charged and the charged electrode. Is disposed outside the charging electrode, almost uniformly contacts the charging electrode in the width direction thereof, and at the contact portion, the charging electrode and the electrode supporting portion are arranged so as to be in non-contact. A power supply electrode, and a power supply for applying a charging potential to the charging electrode via the power supply electrode, wherein the power supply electrode is rotated or independently driven to rotate according to the orbital movement of the charging electrode. Characterized by being a member A charging device. 16. The charging device according to claim 1, wherein the charging electrode is a film having two or more layers, and at least an outermost layer that contacts the member to be charged is provided. And a charging device formed of an ion conductive material.