JPH1063064A - Electrifier for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifier capable of suppressing the occurrence of defective electrification by suppressing the occurrence of damage such as the crack and disconnection of the electrode of an electrifying member even if the flexible electrifying member is placed in repeated pressurized contact/ noncontact states with a body to be electrified to be repeatedly bent in accordance with the repetition of the electrifying/nonelectrifying of the surface of the body to be electrified. SOLUTION: The flexible electrifying member 1 has an electrifying attitude away from the surface of the body to be electrified 10, when it is electrified, in such a manner that a first part on the downstream side in the moving direction of the surface of the body to be electrified 10 is brought into pressurized contact therewith and a second part being adjacent to the first part and on the upstream side is bent toward the first part. The flexible electrifying member 1 has a nonelectrifying attitude, when the body to be electrified 10 is not electrified. Then, the difference between angles in the electrifying and nonelectrifying attitudes, formed by the second part and the surface of the body to be electrified 10 is <=30 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an electrostatic latent image directly on a recording material such as recording paper by a charging device and developing and fixing it to a visible toner image. Copiers and printers that form an electrostatic latent image on a belt, photoreceptor drum, or other electrostatic latent image carrier using a charging device, develop this into a visible toner image, and transfer and fix it on a recording material The present invention relates to a charging device used in an electrophotographic image forming apparatus such as a facsimile machine, and an image forming apparatus that develops an electrostatic latent image formed on a member to be charged into a toner image and directly displays the toner image.

[0002]

2. Description of the Related Art In the field of charging devices for image forming apparatuses, various types have been proposed and put into practical use. For example, a flexible film is brought into contact with a member to be charged. There is known a device that charges this.
As such a charging device, for example, US Pat.
No. 8,614 is known.

This charging device has a configuration in which a film is cantilevered by a holding plate, and a free end side of the film is brought into contact with a member to be charged. The film is provided such that its free end is located downstream with respect to the moving direction of the surface of the member to be charged. The surface of the film that contacts the member to be charged is coated with an electric insulating layer, and the film functions as an electrode.

[0004]

However, in the above-mentioned conventional charging device, there are many cases where the state of the film being bent due to contact with the member to be charged is different between when the surface of the member to be charged is charged and when it is not charged. . For example, at the time of charging, the film is pressed into contact with the member to be charged, and when the film is not charged, the pressing force is released.
The bending state of the film is different when not charged. Also,
When the surface of the member to be charged is moving for charging and when the surface is stopped during non-charging, the film is attracted to the member by the presence or absence of frictional charging between the charging member and the member to be charged. -A non-adsorption state occurs, and the bending state of the film changes accordingly.

As described above, the bending state of the film is different between the charged position and the non-charged position. If the difference (particularly, the difference in the bending angle) is large, the repetitive stress applied to the bent portion and the change in the bending position are changed. There is a problem that cracks or disconnections occur in the electrode at the bent portion, which causes charging failure.
Accordingly, the present invention provides a charging device for an image forming apparatus that charges a member to be charged by bringing a flexible charging member having at least a flexible electrode into contact with the member to be charged, Even when the charging member is repeatedly pressed and non-pressed against the member to be charged with the repetition of charging and non-charging, even if the charging member is repeatedly bent, damage such as cracking of the electrode of the charging member and disconnection may occur. It is an object of the present invention to provide a charging device in which the occurrence of poor charging is suppressed.

[0006]

According to the present invention, there is provided a charging device for charging a charged object by bringing a flexible charged member having at least a flexible electrode into contact with the charged object. A charging unit for the image forming apparatus, wherein the charging member is configured such that, when charging the charged body, a first portion on the downstream side in the moving direction of the surface of the charged body is pressed against the charged body. A second upstream part adjacent to the first part;
Is placed in a charging position separated from the surface of the member to be charged by being bent with respect to the first portion, and is placed in a non-charging position released from the charging position when the member to be charged is not charged. Forming the second portion and the surface of the member to be charged;
The difference between the angle in the charging position and the angle in the non-charging position is 30 ° or less.

According to the charging device of the present invention, the charging member comprises:
Ordinarily, the charging member is arranged such that a part thereof is supported and a part of the charging member surface is in contact with the member to be charged. When charging the member to be charged, the first portion on the downstream side of the charging member is pressed against the member to be charged, and the second portion on the upstream side adjacent to the first portion is connected to the first portion. On the other hand, the surface of the member to be charged is charged by applying a charging voltage to the electrode while being bent and separated from the surface of the member to be charged and taking a charging posture. When the member to be charged is not charged, a non-charging position is released from the charging position.

The difference between the angle between the charging position and the non-charging position between the second portion and the surface of the member to be charged is 3
The angle is set to 0 ° or less, so that even if charging and non-charging are repeated and stress is repeatedly applied to the bent portion between the first portion and the second portion of the charging member, the stress is suppressed to a small value. In this case, damage such as cracks and disconnection of the electrode is significantly reduced, and the occurrence of charging failure such as uneven charging can be suppressed, so that good charging can be performed, and a good quality image can be formed. .

When the difference between the angle between the charging position and the non-charging position between the second portion and the surface of the member to be charged becomes larger than 30 °, such cracks and disconnections are likely to occur. The angle difference may be 30 ° or less, but is more preferably 20 ° or less in order to more reliably prevent the charging member from being damaged. The following are typical examples of the charging device of the present invention.

That is, the charging member includes a flexible electric insulating member (hereinafter, sometimes referred to as a “flexible insulating member”) and a flexible member provided with the flexible electrode on one surface. The surface of the flexible member opposite to the side on which the electrode is provided is directed to the charged object, is brought into contact with the charged object, and charges the charged object by discharging from the electrode. The discharge is a charging device generated from the first portion or its vicinity.

In the case of this charging device, for example, the case where the first portion includes the tip of the charging member and the portion where the discharge occurs is the tip of the charging member can be exemplified. Also,
In this case, the resistance value of the electrode tip is 10 ¹ as described later.
Desirably, it is in the range of 10 to 10 ⁸ Ωcm. When the charging member is provided with the flexible electrode on one surface of a flexible member including a flexible insulating member, the flexible insulating member is typically in the form of a sheet or a film. Can be mentioned.

The flexible electrode may be an electrode in the form of a needle, a line, a band, or a combination thereof (hereinafter, referred to as an electrode).
These may be collectively referred to as “linear electrodes”. ) Or a continuous electrode in the form of a film can be considered, but as a typical example, a plurality of electrodes are provided (for example, a plurality of linear electrodes are provided).
In addition, there may be a case where the electrodes are arranged at intervals in a direction substantially perpendicular to the moving direction of the surface of the member to be charged.

The electrode may be covered with a flexible, electrically insulating sheet, film, film or other member or material. The electrodes are formed by coating a flexible insulating member, forming a film by vacuum deposition, sputtering deposition, or the like, or etching the film under a photoresist pattern, a contact mask method using an excimer laser, and a mask image method. , Using a beam scanning method, bonding a preformed electrode to a flexible insulating member, and clamping the preformed electrode between the flexible insulating member and the covering member or material of the electrode by any method. Can be provided.

Examples of the material of the above-mentioned flexible insulating member provided with an electrode on one side and the above-mentioned member and material for covering the electrode include fluororesin (ethylene tetrafluoride resin) and the like.
Examples thereof include synthetic resins such as polyimide and polyester, synthetic rubbers such as urethane rubber, and appropriate combinations thereof. In addition, at least a portion of the flexible member that is brought into frictional contact with the member to be charged is desirably formed of a material having good wear resistance, and has a small coefficient of friction with the member to be charged. It is desirable to be formed of a material.

The thickness of the portion of the flexible insulating member (generally, the tip of the electrode) overlapping the discharge portion of the electrode (generally, the tip of the electrode) is determined by the thickness of the flexible insulating member. Although it depends on the material, Young's modulus, etc., the thickness is preferably about 5 to 1000 μm, and in order to sufficiently respond to the unevenness and undulation of the charged body,
Further, the thickness is preferably about 5 to 200 μm. In any case, the electrode is typically made of a conductive material, for example, a conductive metal such as nickel, chromium, copper, gold, platinum, tungsten, aluminum, indium, or titanium; It can be composed of one or a combination of two or more conductive materials such as ITO and carbon.

However, the electrodes may be eroded and contaminated by products such as ozone and nitrogen oxides generated by the discharge. In order to prevent this and to stably perform the discharge for a long period of time, the electrodes must be used. It is desirable that at least the surface of a portion (generally, an electrode tip portion) responsible for electric discharge be covered with a metal oxide-based inorganic thin film, a diamond-like carbon film, or the like. However, since the insulating member on which the electrode is provided has flexibility, it is preferable to cover the insulating member in a range where cracks and the like do not enter.

In addition, at least a portion of the electrode that is in charge of discharging (generally, the tip of the electrode) can be used even in a high humidity environment.
In order to prevent the leakage between the charged objects and to stably discharge, and in the case of the linear electrode, in order to prevent the discharge between the adjacent electrodes, the resistance value is set to 10 ^1.
It may be in the range of about 10 to 10 ⁸ Ω · cm. This is because at least the discharge portion is covered with a high-resistance substance (carbon-containing organic substance or the like) or is formed of a semi-conductive substance, so that the external impedance is increased so that no overcurrent flows between the electrode and the member to be charged. As described above, it is also possible to increase the impedance between the electrodes so that no discharge occurs between the electrodes. However, in this case, the driving voltage is not excessively increased due to the increase in the resistance value, and the inconvenience such that the length or the thickness of the portion differs between the electrodes and a discharge difference occurs is prevented. .

In any case, when the above-mentioned linear electrode is adopted as the electrode, the electrode width is preferably in the range of several μm to 100 μm. Although it is necessary to consider the resolution and the occurrence of inter-electrode leakage, the distance between adjacent electrodes is preferably in the range of about 30 μm to 100 μm. The following case can be exemplified as a mode in which the charging member is in the above-mentioned charging posture or non-charging posture. A semiconductive member directed to the surface of the member to be charged is provided on at least a portion of the charging member that generates a discharge, and the charging position of the charging member is changed by switching a voltage applied to the semiconductive member. Place in non-charging position. Means for pressing the charging member against the member to be charged, the charging member being charged by the magnitude of the pressing force applied to the charging member by the pressing means ("small" includes the case without pressing force). Place in a posture or a non-charged posture. The charging member is placed in the charging position or the non-charging position depending on the presence or absence of frictional charging according to the presence or absence of relative movement between the charging member and the surface of the member to be charged. Combinations of two or more of the above.

In the above-described charging device in which a semiconductive member is provided at a portion where discharge of the charging member occurs, the semiconductive member is sowed by the wind generated by the movement of the surface of the member to be charged or the member to be charged. This is for stably electrostatically adsorbing the charging member to the member to be charged so as to suppress vibration of the charging member in the direction of movement of the surface of the charging member. The wind generated by the movement of the surface of the member to be charged tends to soar up the charging member. In this charging device, a semiconductive member is provided at a portion where the charging member is discharged. By applying a charge to the member, an electrostatic attraction force acts between the member and the member to be charged, whereby the charging member is stably brought into contact with the member to be charged, and thus even when the wind is generated,
In addition, even if the object to be charged has irregularities or undulations, the charging member has flexibility, so that each portion of the charging member uniformly contacts the object to be charged, and discharge of the electrode between the object to be charged and the electrode on the charging member. The discharge interval from the charge portion is made uniform, the vibration of the charging member in the moving direction of the surface of the member to be charged is also suppressed, and the synchronous deviation of the discharge from each portion of the charging member is also suppressed. As a result, good charging is performed in a state where charging unevenness and other charging defects are suppressed, and a good image can be obtained.

Such a semiconductive member is made of a material
Fluororesin (ethylene tetrafluoride resin, etc.), polyimide,
A material in which a conductive material is mixed in a material such as a synthetic resin such as polyester or a synthetic rubber such as urethane rubber is conceivable, but is not limited thereto. As a method of forming, it can be formed by means such as application of a semiconductive material solution, sputtering, etc., but is not limited thereto. Further, since the semiconductive member is a portion that rubs and contacts the member to be charged, it is preferable to use a material having good wear resistance, and a member having a small friction coefficient with the member to be charged is more preferable in terms of torque to the member to be charged. . Further, even if there is a cleaning device for the member to be charged, residues such as toner for forming a visible image may reach the charging device, and they are prevented from fusing to the semiconductive member or the like. For this reason, a material having good releasability with respect to toner for forming a visible image or the like is preferable. A suitable resistance value of the semiconductive member is about 10 ¹ to 10 ⁸ Ω · cm.

In the charging device according to the present invention, at least a part of the surface of the charging member on the side in contact with the member to be charged is formed of a semiconductive member, and means for applying a voltage to the semiconductive member is provided. In this case, the voltage applied to the semiconductive member by the voltage applying means may not charge the member to be charged to a predetermined potential. More specifically, although it depends on the resistance value of the semiconductive member, the difference between the voltage and the potential of the member to be charged may be, for example, 550 [V] or less in absolute value. When such a voltage is employed, no charge is deposited on the member to be charged, and the residual potential on the member to be charged can be maintained before reaching the charging device. However, if it exceeds 550 (V), the member to be charged is charged. Further, as such a voltage applying unit, it is also conceivable that the polarity of the applied voltage is made to be opposite to the polarity of the voltage at the time of non-image formation, or that the semiconductive member is cleaned by applying an alternating current.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view of an example of a charging device to which the present invention can be applied, and FIG. 1B is a side view thereof. The charging device A shown in FIG.
It is provided for a charged body 10 which is a drum-type electrostatic latent image carrier that is driven to rotate in the direction.

The charging device A is provided with a flexible, substantially sheet-shaped charging member 1, which is arranged in a direction along the surface moving direction of the member 10 to be charged, and which moves in the surface moving direction of the member. , The upstream end 1a is sandwiched between a holding member 2 parallel to the rotation axis direction of the member to be charged 10 and a pressing member 3 thereon, and is supported as a cantilever as a whole. When the charging member 1 charges the member 10 to be charged, the pressing device P
By R, as shown in FIG. 1, at least the downstream end 1b takes a charging posture in which it is pressed against the surface of the charged body 10 as a discharge end. That is, the holding member 12 is rotatable about the shaft 21, and at the time of charging, the rear end of the holding member 2 is pulled up by the spring SP, so that the charging member end 1b is urged in the counterclockwise direction in FIG. As a result, the end 1b is pressed against the member 10 to be charged. On the other hand, during non-charging (non-printing), the solenoid SOL connected to the holding member 2 is turned on by an instruction from the control unit CONT, whereby the rear end of the holding member 2 moves downward against the spring SP. When the charging member 1 is pulled down, the charging member 1 assumes a non-charging posture released from the charging posture pressed against the member 10 to be charged.

The spring SP and the solenoid SOL
Is turned upside down, the solenoid SOL is turned on at the time of charging, and the charging member 1 is pressed against the member to be charged against the spring SP. At the time of non-charging, the solenoid SOL is turned off and the charging member 1 is pressed by the spring SP. May be canceled. A flexible electrode, which will be described later, of the charging member 1 is connected to a discharge driving power supply or the like by a signal cable 4 as described later.

The member to be charged 10 is formed by coating a dielectric layer on the surface of a conductive support drum. Due to the discharge from the charging member 1, a sufficient surface charge is applied to the dielectric layer without causing dielectric breakdown, and the latent image after the formation of the electrostatic latent image by the charging device is visualized (developed) by a developing unit (not shown). ) The surface charge can be retained until the step, and the surface charge can be removed and used repeatedly. The developing device contains a powder toner, and the electrostatic latent image is developed by the powder toner. The developed image advances to a transfer unit (not shown) with the rotation of the member to be charged 10 and is transferred to a sheet such as paper. After the transfer, the charged object 10 is removed from the charge removing brush 16.
(Refer to FIG. 18) The static latent image is erased by static elimination means such as (see FIG. 18), and the portion arrives at the charging member 1 again.
Although the charging target 10 has a drum shape here, it may have a belt shape or other shapes. In addition, a photoconductor layer may be used instead of the dielectric layer. When the photoconductor layer is employed, the charge can be removed by irradiating the entire surface, and the photoconductor layer can be easily used repeatedly.

FIGS. 2 to 9 show examples of the charging member 1 to which the present invention can be applied. Each of the charging members 1 is a flexible sheet-like electrically insulating member 11 (hereinafter, referred to as a member).
This is referred to as “flexible insulating member 11”. 2) is provided with a plurality of flexible linear electrodes 12 on one side. More specifically, of the surface of the flexible insulating member 11 opposite to the side on which the electrode 12 is provided, the surface of the free tip portion 111 corresponding to the downstream end portion 1b of the charging member 1 on the side of the member to be charged is described. Charged object 1
0 to form a discharge gap between the charged body 10 and the tip of the electrode 12, and the charged body 10 is charged by the discharge from the tip of the electrode.

In the charging member 1 shown in FIG. 2, each electrode 12 is a narrow band-shaped electrode having a uniform width in the length direction, and a plurality of the electrodes 12 are arranged in parallel. Here, the charging member 1 shown in FIG.
In addition, items that are substantially common to a charging member to be described later will be described. The thickness of the flexible insulating member 11, particularly at least the thickness of the free front end portion 111 or the front end portion and the vicinity thereof, is 5 to 100 in order to obtain a good discharge.
The thickness is preferably about 0 μm, and although it depends on the material and Young's modulus of the flexible insulating member 11, the thickness is more preferably about 5 to 200 μm in order to sufficiently respond to irregularities and undulations on the surface of the charged body 10. Due to the thickness of this portion, the distance between the tip end portion 121 of the flexible electrode 12 to which the discharge voltage is applied and discharged and the member to be charged 10 are kept constant. Therefore, the thickness of this portion is made uniform so as not to seriously affect the discharge. In addition, as a material of the flexible insulating member 11, a material such as a fluororesin (eg, tetrafluoroethylene resin), urethane rubber, polyimide, and polyester can be used, but is not limited thereto.

The object to be charged 10 of the flexible insulating member 11
It is preferable to use a material having good abrasion resistance for the portion in contact with the material, and it is more preferable to use a material having a small coefficient of friction with the member to be charged 10. Further, the flexible electrode 12 is made of a material such as nickel, chromium, copper, gold, platinum, tungsten, aluminum, indium, titanium, or the like;
Using a conductive material such as carbon and patterning by photoetching, using a method such as sputtering, or using a contact mask method, mask image method, beam scanning method, or the like using an excimer laser, or using another method. It can be formed on the flexible insulating member 11.

The flexible electrode 12 formed on the flexible insulating member 11 may be eroded or contaminated by products such as ozone and nitrogen oxide generated by electric discharge. In order to discharge stably over a long period of time, at least the surface of the flexible electrode tip 121 may be covered with a metal oxide-based inorganic thin film or a diamond-like carbon film. However, since both the insulating member 11 and the electrode 12 are flexible, it is preferable to cover the insulating member 11 and the electrode 12 within a range where cracks and the like do not enter.

In order to prevent a leak between the electrode 12 and the member to be charged 10 and to stably discharge even in a high humidity environment,
In addition, at least the resistance value of the flexible electrode tip 121 is set to 1 so as to prevent leakage between the adjacent electrodes 2 and prevent abnormal dot discharge, thereby performing stable discharge.
It may be in the range of about 0 ¹ to 10 ⁸ Ω · cm.
To this end, at least the flexible electrode tip 121 may be covered with a material having a higher resistance than the flexible electrode 12 main body (for example, a carbon-containing organic material) or may be formed of a semiconductive material. However, the driving voltage is not excessively increased due to the increase in the resistance value, and there is no inconvenience such that the length or thickness of the portion differs between the electrodes and a discharge difference occurs.

The width of the electrode 12 is approximately several μm.
Those having a range of from 100 to 100 μm are preferred. Although it is necessary to consider the resolution and the occurrence of inter-electrode leakage, the distance between adjacent electrodes is preferably in the range of about 30 μm to 100 μm. Next, further description will be given of other charging members to which the present invention can be applied. The charging member 1 shown in FIG. 3 is obtained by fixing a flexible electrode 12 made of a tungsten wire having a diameter of about 10 μm to 100 μm to a flexible insulating member 11 with an insulating adhesive or the like.

The charging member 1 shown in FIG. 4 is a modification of the charging member shown in FIG.
The end surface 111a of the flexible insulating member end portion 111 having the cross section 21 is cut obliquely and protrudes like an eave in the moving direction of the surface of the member to be charged.
In this case, the area facing the surface is large, so that the discharge is easy.

The charging member 1 shown in FIG. 5 is another modified example of the charging member shown in FIG. 2, in which the distal end portion 121 of the flexible electrode 12 is thinner than other portions, and the discharge at the end portion 121 is performed. Is easy, the driving voltage can be kept low, and
The printing diameter can be reduced. Charging member 1 of FIG.
Is another modification of the charging member of FIG.
2 is the free end surface 11 of the flexible insulating member 11
1b, whereby the discharge area becomes large and the discharge becomes easy.

In the charging member 1 of FIG. 7, the flexible electrode 12 is provided in the flexible insulating member 11, and the end face of the discharge end 121 is exposed to the insulating member end face 111b. This may be created by a method of forming the flexible insulating member 11 around the flexible electrode 12, or may be created by sandwiching the flexible electrode 12 between two flexible insulating members. Is also good. With such a configuration, it is possible to prevent the electrodes from leaking from each other except at the discharge end, particularly at the time of high humidity. Such a configuration can be employed in other charging members. For example, in the charging member of FIG. 2, the same effect can be obtained by applying, depositing, attaching, or the like an electrically insulating member on the surface of the flexible insulating member 11 on which the flexible electrode 12 is provided. .

The charging member 1 of FIG. 8 is the same as FIG. 7 in that the flexible electrode 12 is provided in the flexible insulating member 11, but the discharge end 121 of the flexible electrode 12 is It protrudes from the insulating member end face 111b. With such a configuration, the space of the discharge end portion 121 with respect to the member to be charged 10 is widened, so that the discharge becomes easy. In the charging member 1 of FIG. 9, the thickness of the free distal end portion 111 of the flexible insulating member 11 is about 5 to 1000 μm. Thick,
It has a thickness of several hundred μm to several mm. FIG. 9 (B)
As shown in (1), the vicinity of the boundary between the thick portion and the thin portion of the flexible insulating member 11 is a contact start portion between the flexible insulating member 11 and the member 10 to be charged. Although it depends on the friction coefficient of the contact surface between the member to be charged 10 and the flexible insulating member 11, the thickness of the flexible insulating member 11 is generally 5 to 5 as in the charging member of FIG. If it is uniform at about 1000 μm, a force that causes the flexible insulating member 11 to move in the moving direction of the member to be charged 10 by the frictional force accompanying the movement of the surface of the member to be charged 10 and the flexible insulating member 11 is fixed. Due to the balance with the applied stress, the flexible insulating member 11 vibrates in the moving direction of the surface of the member to be charged, so that printing unevenness is likely to occur. But,
In the charging member 1 of FIG. 9, since the flexible insulating member 11 is held by the thick portion, the rigidity of the vicinity of the holding portion of the member 11 is increased, and the contact between the flexible insulating member 11 and the member to be charged 10 is increased. When the start portion is determined, the vibration of the flexible insulating member 11 in the moving direction of the surface of the member to be charged is reduced, and the printing unevenness can be suppressed.

Next, FIGS. 10 to 12 show examples of a charging device to which the present invention can be applied, which have a slightly different structure from the charging device of FIG. Although not shown, the charging member 1 shown in these figures is also rotated in the direction of the arrow by a pressing device PR including a spring SP and a solenoid SOL as shown in FIG. 10 and a non-charging posture released from the pressing. However, in these charging devices, a pressing member described below is also employed as a component of the pressing means. 10 to FIG.
Reference numeral 2 denotes a charging member 1 which is in a charging posture.

The charging device B shown in FIGS. 10A and 10B
The elastic member 5 is applied to a portion of the charging member 1 held by the holding member 2 and the pressing member 3 and a portion in the vicinity thereof. The elastic member 5 includes the holding member 2 and the holding member 3.
And the charging member 1. The other points are the same as those of the charging device shown in FIG. Charging member 1
During charging, the pressing device PR presses against the member to be charged 10 and is also pressed by the elastic member 5, thus charging the flexible insulating member 11 of the charging member 1 with the member to be charged, as shown in FIG. The contact start portion with the body 10 is determined. That is, the vicinity of the downstream end of the elastic member 5 that presses the charging member 1 is a contact start portion between the flexible insulating member 11 and the member 10 to be charged. In the charging device B, the vibration of the flexible insulating member 11 in the moving direction of the surface of the member to be charged due to the frictional force accompanying the surface movement of the member to be charged 10 is reduced.

The charging device C shown in FIGS. 11A and 11B
Is obtained by adding a pressing member 6 to the charging device A shown in FIG. In the device C, at the time of charging, the charging member 1 is pressed against the member to be charged 10 by the pressing device PR, and the pressing member 6 presses the vicinity of the end 1b of the charging member 1 so that the flexible electrode 12 is charged. The distance from the body 10 is kept constant. In the charging device C, the responsiveness of the charging member 1 to the eccentricity and large undulation of the charged body 10 is good. The pressing member 6 is a driving device (not shown) (for example, a solenoid)
As a result, when charging is performed, the pressing position shown is taken, and when charging is not performed, the pressure rises to take the non-pressing position.

The charging device D shown in FIG. 12 is obtained by adding the pressing member 7 to the charging device A shown in FIG. The pressing member 7 includes a pressing member 71 and a pressing member holding member 72. In this device D, at the time of charging, the charging member 1 is connected to the pressing device PR.
As a result, the pressing member 7 presses the vicinity of the end 1b of the charging member 1 so that the distance between the flexible electrode 12 and the charging target 10 is kept constant. As in the case of the device C, the charging member 1 has good follow-up performance with respect to the eccentricity and large undulation of the charged body. It is preferable that the pressing member 71 be capable of sufficiently transmitting the pressing force and have sufficient followability to the pressing, such as urethane foam or foamed silicone rubber. Note that the pressing member 7 takes a pressing position shown in the drawing when charging, and rises to a non-pressing position in the non-charging state by a driving device (for example, a solenoid) not shown.

FIG. 13 is a diagram showing an example of an electric circuit that can be employed in the charging device according to the present invention, including the charging device described above. According to this electric circuit, a print signal corresponding to an image to be printed is formed by the image signal forming unit 102 and output to the drive power supply unit 101. The drive power supply unit 101 boosts the print signal to a high voltage, and the high-voltage print signal is applied to each flexible electrode 12 of the charging member 1.

Conversely, while a high voltage is applied to the conductive support on the side of the member to be charged, each of the flexible electrodes 1 according to the print signal is applied.
2 may be grounded. Or, combining these,
While a high voltage is applied to each flexible electrode 12 in response to a print signal, a slight bias voltage having a polarity opposite to that of the print signal may be applied to the conductive support.
Can be reduced.

FIG. 14 is a diagram showing another example of an electric circuit that can be employed in the charging device according to the present invention. In this example, the charging member 1 is provided with a flexible control electrode 12c outside the flexible electrodes 12 at both ends and between the adjacent flexible electrodes 12. According to this electric circuit, a print signal corresponding to an image to be printed is formed by the image signal forming unit 104 and output to the drive power supply unit 103. The drive power supply unit 103 boosts the print signal to a high voltage, and a high voltage application signal is applied to each flexible electrode 12 of the charging member 1. A voltage is also applied to each flexible control electrode 12c. By setting the voltage applied to the control electrode 12c to a voltage approximately intermediate between the voltage (discharge voltage) applied to each flexible electrode 12 and the ground voltage, for example, the potential difference between the flexible electrode 12 and the control electrode 12c is reduced. The size can be reduced, thereby preventing leakage between the electrodes. Further, the mutual influence of the potentials of the adjacent flexible electrodes 12 is reduced, and the printing diameter is stabilized. The control electrode 12
Depending on the voltage applied to c, the print diameter can be reduced. That is, regarding one discharge electrode 12, by applying a voltage to the control electrodes 12c on both sides of the discharge electrode 12, the spread angle of the discharge from the discharge electrode 12 is controlled (it is narrowed according to the voltage applied to the electrode 12c). Thus, the printing diameter can be reduced.

FIG. 15 is a diagram showing still another example of an electric circuit that can be employed in the charging device according to the present invention. In this example, the charging member 1 includes a flexible electrode (discharge electrode) 12, and the flexible electrode 12 receives a print signal from an IC circuit drive power supply 101 a directly attached to the flexible insulating member 11. High voltage is applied. With such a configuration, the size can be reduced, and the number of signal cables between the charging member and the main body including the image forming apparatus can be reduced.

In the charging device according to the present invention, the voltage applied to the flexible electrode (discharge electrode) 12 of the charging member 1 corresponds to the electrode tip of the flexible insulating member 11 in the charging member 1. An example of the relationship with the thickness of the end portion 111 or the end portion and the vicinity thereof is as follows. Note that this is an example in which the discharge voltage polarity is positive. Basically, a discharge occurs when a voltage higher than the following voltage is applied, but when a too high voltage is applied too much, the printing diameter becomes large.

Thickness [μm] of flexible insulating member 11 Voltage [V] applied to electrode 12 5 400 50 700 100 1000 300 1200 1000 (1 mm) 1700 Next, still another example of a charging device to which the present invention can be applied. Figure 1
This will be described with reference to FIG. FIG. 16 is a perspective view showing a main part of the charging device. Although not shown in its entirety, the charging device E has the same basic configuration as the charging device A shown in FIG. 1, and uses the charging member 1 shown in FIG. 16 as the charging member 1 in the basic configuration. The electric circuit shown in FIG. 13 is employed. The charging member 1 shown in FIG. 16 is provided with a plurality of flexible electrodes 12 on one side of a flexible insulating member 11, and the holding portion of the charging member 1 by the holding member 2 and the holding member 3 ( In a portion downstream of the end 1a) on the upstream side in the moving direction of the member to be charged and in a portion where the electrode 12 is not provided, the ventilation hole 1 is formed in the flexible insulating member 11.
3 is formed. The position of the ventilation hole 13 is
Is a position where the portion having the ventilation hole 13 does not come into contact with the member to be charged 10 during the rotation of.

According to the charging device E, the substantially sheet-shaped flexible charging member 1 comes into contact with the member 10 at the downstream end 111 of the flexible insulating member 11. Then, in the contact state, discharge is performed from the flexible electrode 12 to the surface of the charged body 10, whereby the surface of the charged body 10 is charged as predetermined. The wind generated by the rotation of the charged member 10 escapes through the ventilation holes 13 provided in the charging member 1, so that the rising of the charging member 1 is suppressed accordingly. Since the charging member 1 is substantially sheet-shaped and has flexibility, the object to be charged 10
Furthermore, even if there are irregularities or undulations, the contact is familiar and the discharge interval between the charged object 10 and each electrode 12 is made uniform. Further, in the related art, the frictional force generated at the contact portion generated by the rotation of the member to be charged 10 receives a force in a direction in which the flexible electrode 12 on the flexible insulating member 11 is extended and a force in a direction in which the flexible electrode 12 flies, and When the amount of bending of the electrode 12 on the flexible insulating member 11 changes due to the balance, the tip 121 of the electrode 12 vibrates in the direction of movement of the surface of the charged object, thereby moving the surface of the charged object at the tip of each electrode. Where the discharge time lag occurs in the direction and the discharge lag occurs, causing printing unevenness.
When the wind escapes, the influence of the wind on the charging member 1 is small, so that the vibration of the charging member 1 in the moving direction of the surface of the member to be charged is also suppressed, thereby suppressing the synchronization deviation of the discharge by the electrodes 12. As a result, good charging is performed in a state where charging unevenness and other charging defects are suppressed, and a good image can be obtained. Further, disconnection of the electrode is less likely to occur.

The ventilation holes 13 can also be provided in the charging members shown in FIGS. FIG. 17 shows a main part of still another example of the charging device to which the present invention can be applied.
The charging device F shown in FIG. 17A is not shown in its entirety, and mainly shows the charging member 1 as a main part.
The charging device A has the same basic configuration as the charging device A shown in FIG. 1, and the entirety of the flexible insulating member 11 of the charging member shown in FIG. A stack of semiconductive members 14,
The member 14 comes into contact with the member 10 to be charged.

In the charging member 1 shown in FIG. 17A, the semiconductive member 14 is provided on the entire surface of the flexible insulating member 11 on the side to be charged. The electrode 12 may be provided only in the vicinity of the vicinity of the distal end 121 in charge of discharge. FIG. 17B shows such a charging device F '. In this charging device, the semiconductive member 14 is provided at the leading end portion of the charging member in charge of discharging by a width d (width d in the direction of movement of the surface of the charged member 10).

The semiconductive member 14 is formed from a material such as a synthetic resin such as fluororesin, polyimide, polyester or the like or a synthetic rubber such as urethane rubber mixed with a conductive material, but is not limited thereto. As a method of making, it is made by a method such as application of a semiconductive material solution, sputtering, etc., but the method is not limited thereto. In addition, since the semiconductive member 14 is a portion that rubs and contacts the member 10 to be charged,
It is preferable to use a material having good abrasion resistance.
This is preferable from the viewpoint of torque against zero. Further, even if the charged object 10 has a cleaning device, residues such as toner for forming a visible image may reach the charging device, and thus, they are prevented from fusing to the semiconductive member 14 or the like. Therefore, a material having good releasability with respect to toner for forming a visible image is preferable. The resistance value of the semiconductive member is 10 ¹ to 10 ⁸ Ω
About cm is appropriate.

A voltage is applied to the semiconductive member 14 by a driving power supply. The value of the applied voltage depends on the semiconductive member 1.
It is preferable that the voltage value is such that the charged object 10 is not charged according to the value of 4, but is not limited thereto. Semiconductive member 1
If the difference between the surface potential of the member to be charged 10 and the voltage value applied to the member 14 is about 550 [V] or less, the semiconductive member 14 Is not charged. Therefore, if the potential of the member to be charged is 0 [V], the voltage applied to the semiconductive member 14 is -550.
[V] to about 550 [V] is appropriate. When a voltage is applied to the semiconductive member 14, the semiconductive member 14 is attracted to the member to be charged 10 by electrostatic force.

The electrostatic attraction will be further described with reference to FIG. For example, the surface of the dielectric layer of the member to be charged 10 has been neutralized by a neutralization brush 16 to which an AC voltage has been applied in a process before reaching the charging member 1, and a negative voltage is applied to the semiconductive member 14, and Consider a case in which a negative voltage is also applied to 12. A negative charge is excited on the conductive drum 10 </ b> D of the member to be charged 10 in a portion charged to a positive charge in the transfer step or the like. When the portion reaches the charge removing brush 16, the brush removes the positive charge on the surface of the charged member 10, and sets the surface potential to 0 [V]. Next, the semiconductive member 14
A positive charge is excited on the conductive drum 10D facing through the dielectric layer by the negative charge of
The charging member 1 is attracted to the member to be charged 10 by an electrostatic attraction force acting between the charged member 1 and the negative charge. When the surface of the member to be charged passes through the member 14, a negative charge is applied from the electrode 12 to the surface, and the surface is charged. In FIG. 18, the charged body 10 is grounded, but may be kept at a predetermined positive potential.

Here, in FIG. 18, the symbol T indicates the toner remaining on the surface of the member to be charged 10 after the transfer step. The residual toner T arrives at the charging member 1 with the rotation of the member 10 to be charged, but is stopped at a portion P where the member 1 contacts. Particularly, in this example, the semiconductive member 14 and the member to be charged 10
And the residual toner T hardly flows out of the portion P. In addition, since the charging member 1 has flexibility, the charging member 1 can well follow undulations, irregularities, and the like on the surface of the member to be charged 10, and can reliably dampen the residual toner T. Even if it flows out, in this example, the charging by the electrode 12 is performed at the most downstream position of the charging member 1 (that is, the charging is performed at the position farthest from the portion P), and thus reaches the charging position by the electrode 12. There is very little to do. Therefore, the residual toner T that has flowed out
Has almost no adverse effect on the charging by the electrode 12, for example, poor charging. From this viewpoint, the length of the contact portion of the charging member 1, that is, the portion downstream of the portion P of the charging member 1 in the moving direction of the charged body 10 is about 3 m.
m or more. That is, the charging member 1
It is preferable that about 3 mm or more from the most downstream position to the upstream side is in surface contact with the member 10 to be charged.

By such an electrostatic attraction effect, the discharge distance between the discharge end portion 121 of the flexible electrode 12 and the charged member 10 is kept uniform. Then, even if wind is generated by the rotation of the member to be charged 10, the charging member 1 is stably brought into contact with the member to be charged 10 by the action of the electrostatic attraction force,
Even if the charged body 10 has irregularities or undulations, each part of the flexible insulating member 11 uniformly contacts the charged body 10 in combination with the fact that the charging member 1 has flexibility, and The discharge interval with the electrode 12 is made uniform. Also, the charging member 1
Is also suppressed in the direction of movement of the surface of the member to be charged, and the synchronous deviation of the discharge by each electrode 12 is also suppressed. As a result, good charging is performed in a state where charging unevenness and other charging defects are suppressed, and a good image can be obtained. Further, disconnection of the electrode 12 is less likely to occur.

Further, as described above, foreign substances such as residual toner and paper dust of recording paper on the member to be charged 10 are blocked by the electrostatic attraction upstream of the electrostatic attraction area, so that the discharge area and its vicinity But there is also an effect that it is not stained. 19, 20, and 2 in place of the semiconductive member 14 shown in FIG.
A semiconductive member 14 as shown in FIG.

The semiconductive member 14 shown in FIG. 19 is provided on a portion of the flexible electrode 12 except for the vicinity of the tip 121. This is effective in preventing a printing failure due to a leak from the discharge end portion 121 of the flexible electrode 12 to the semiconductive member 14, and a region where the semiconductive member 14 is not provided is a flexible insulating member. Several tens μm to several hundred μm from the end of 11
A degree is desirable.

The semiconductive member 14 shown in FIG. 20 has a comb-like shape near the distal end 121 of the flexible electrode 12.
The flexible electrodes 12 and the semiconductive members 14 are alternately arranged. This corresponds to the discharge tip 12 of the flexible electrode 12.
Increasing the distance from 1 to the semiconductive member 14 is effective in preventing printing defects due to leaks between the two, and at the same time, it is necessary to ensure the uniformity of the distance between the electrode 12 and the member 10 to be charged. This is for electrostatically adsorbing the vicinity of the tip of the non-conductive electrode 12. In this example, the distance between the electrode tip 121 and the member to be charged 10 can be kept uniform as compared with the member 14 in FIG. 19, so that more stable discharge is possible.

The semiconductive member 14 in FIG. 21 has a comb-like shape near the distal end 121 of the flexible electrode 12, and
The flexible electrodes 12 and the semiconductive members 14 are alternately arranged. The semiconductive member 14 is partially buried in the flexible insulating member 11, and the member 14 and the member 11 are located at the same plane position. FIG. 21 also shows an electric circuit of a charging device employing the member 14. According to this electric circuit, a print signal corresponding to an image to be printed is formed by the image signal forming section 102 and output to the drive power supply 101b. The drive power supply 101b boosts the print signal to a high voltage,
A high voltage print signal is applied to each flexible electrode 12. A voltage is applied to the semiconductive member 14 by the power supply PW. This electric circuit can also be applied to a charging device employing the charging members of FIGS. 17, 19, and 20.

It should be noted that the semiconductive member 14 may have a charge eliminating function. FIG. 22 and FIG. 23 are diagrams showing the state of charging and discharging at this time. FIG. 22A shows a case where printing is performed by applying a negative voltage to the flexible electrode 12. A negative charge is applied to the charged body 10. Next, FIG. 22B shows a state immediately before the charged body 10 that has undergone the steps of development, transfer, cleaning and the like returns to the charging member 1 again. The polarity of the charged body 10 differs depending on the polarity of the developing step and the transfer step. For example, when the charged body 10 is negatively charged, if a positive potential is applied to the semiconductive member 14, Charged body 10
Is discharged to the positive side. Although it depends on the resistance value of the semiconductive member 14, for example, if a voltage of about +550 V to +600 V is applied, the charge is eliminated to about zero potential, and FIG. 22C shows this state. As shown in FIG. 22 (D), the charged object 10 has no charge due to the charge elimination. FIG.
Indicates a case where the member to be charged 10 is positively charged in the developing step, the transferring step, and the like.

Note that the charging members shown in FIGS. 17 and 19 to 23 can also be provided with the ventilation holes 13 as in the charging member shown in FIG. In combination with the above-mentioned electrostatic attraction by the member 14, good charging is performed in a state where charging unevenness and other charging defects are suppressed more reliably, and a good image can be obtained. Conversely, the semiconductive member 14 can be provided on at least a part of the surface of the charging member 1 shown in FIG.

Next, still another example of the charging device to which the present invention can be applied will be described with reference to FIG. The charging device G shown in FIG. 24 is the same as the charging device E described with reference to FIG.
The semiconductive member 14 as described above is provided on the entire surface on the 0 side, and the pressing fins 15 are provided upright on the downstream side of the ventilation holes 13 in the moving direction of the surface of the charged object. Fin 1
5 is provided so as to receive the pressure of the wind passing through the ventilation hole 13.

According to the charging device G, the wind generated by the rotation of the member to be charged 10 escapes through the air holes 13 provided in the charging member 1, so that the rising of the charging member 1 is suppressed accordingly. Further, the fin 15 receives the pressure of the wind passing through the ventilation hole 13 and presses the charging member 1 toward the member 10 to be charged. Therefore, the rising of the charging member 1 is further suppressed. Further, the charging member 1 is attracted to the charged member 10 by the electrostatic attraction action of the semiconductive member 14. Thus, even if the charged object 10 has irregularities or undulations, or even if wind is generated by the rotation of the charged object 10, each of the electrodes 1 of the charged object 10 and the charging member 1 is not affected.
The discharge interval between the two is made more uniform, and the synchronization deviation of the discharge is further suppressed. Further, disconnection of the electrode is less likely to occur. The electric circuit of FIG. 21 can be applied to the charging device of FIG.

The fin 15 needs to have a certain hardness in its function. It is possible to make the fins 15 and the ventilation holes 13 by bending the flexible insulating member 11, but since the fins 15 become flexible, they are bent by wind pressure, and the flexible insulating member 11 is covered. Charged body 10
May not be able to perform the function of pressing sufficiently. Therefore, the thickness of the flexible insulating member 11 may be increased only in the vicinity of the ventilation hole, or another member may be bonded only in the vicinity of the ventilation hole. Of course, it is also possible to form the fin 15 with another member and attach it to the flexible insulating member 11.

The combination of the ventilation holes 13 and the fins 15 can be applied to the charging members shown in FIGS. 2 to 17 and FIGS. FIG. 25 shows the charging member 1 shown in FIG.
1, that is, a charging device provided with a charging member 1 provided with a semiconductive member 14 on the side that contacts the member 10 to be charged.

In FIG. 25A, the charging member 1 is electrostatically attracted to the member 10 to be charged. At this time, the charging member 1
Is bent at a bending angle θ ₂ [degrees]. FIG.
(B) shows a state when the charging member 1 is not electrostatically attracted to the member to be charged 10. At this time, the charging member 1 is bent at the bending angle θ ₃ [degree]. The angles θ ₂ and θ ₃ are, in other words, the angles formed between the portion of the charging member that is separated from the member to be charged 10 and the member to be charged 10.

Normally, at the time of printing, the charging member 1 is
However, during non-printing or when the power is turned off, no voltage is applied for adsorption, and the charging member 1 is not adsorbed on the member 10 to be charged. This adsorption state (charging posture)
And the non-sucking state (non-charging posture) are repeated, the bent portion of the charging member 1 may cause a fatigue phenomenon, and the flexible electrode 12 on the charging member 1 may be disconnected. The time until the disconnection varies depending on the material, thickness, shape, etc. of the flexible electrode, and | θ ₂ −θ ₃ |
When the temperature exceeds 30 °, the service life becomes about half or less as compared with the case of 30 ° or less. If it is 20 ° or less, the life is further extended. In the present invention, | θ ₂ −θ ₃ |
The degree is 30 ° or less, more preferably 20 ° or less.

FIG. 26 shows the charging device of FIG.
The state of adsorption (charging posture) of the charging member 1 to the member to be charged 10 is
FIG. A charging member for the rotating member to be charged 10
1 is electrostatically attracted, and the charging member 1 has a bending angle θ₁
It is bent at [degree]. Angle θ₁Is, in other words,
The part of the charging member that is separated from the member to be charged 10 is
This is the angle formed by the charged body 10. The surface of the member to be charged 10
When moving, friction between the charging member 1 and the charged body 10
By the balance between the force and the force for holding and attracting the charging member 1
The charging member 1 vibrates slightly in the moving direction of the surface of the member to be charged.
Due to this vibration, the bent portion of the charging member 1 becomes fatigued.
A phenomenon occurs, and the flexible electrode 12 on the charging member 1 is disconnected.
May cause. The time required to cause this disconnection is flexible
Although it depends on the material, thickness, shape, etc. of the conductive electrode 12,
Bend angle θ₁When [degree] exceeds 45 °, 45 °
The life is about half or less compared to the following cases.
You. If it is 30 ° or less, the life is further extended. Follow
In the charging posture described above with reference to FIG.
Difference in bending angle of charging member from posture | θ_Two−θ _Three
| [Degree] is 30 ° or less, more preferably 20 ° or less
In addition to the above, the bending angle θ of the charging member in the charging posture₁
[Degree] is 45 ° or less, more preferably 30 ° or less
Is adopted, the life of the charging member is further extended.

FIG. 27 shows still another example of the charging device to which the present invention can be applied. The charging member 1 in this charging device is a charging member shown in FIG. 2, that is, a flexible insulating member 11 on which flexible linear electrodes 12 are arranged.
FIG. 27A shows a state in which the charging member 1 is pressed against the member to be charged 10 by the pressing member 20, and the charging member 1 is bent at a bending angle θ ₄ [degrees]. FIG. 27 (B)
Indicates a state in which the charging member 1 is released from being pressed by the pressing member 20. At this time, the charging member 1 has a bending angle θ.
It is bent at ₅ [degrees]. The angles θ ₄ and θ ₅ are, in other words, the angles formed by the portion of the charging member that is separated from the member to be charged 10 and the member to be charged 10. Usually, during printing, the charging member 1 is pressed against the member to be charged 10 by the pressing member 20, but during non-printing or when the power is turned off, the pressing member 20 is released, and the charging member 1 is pressed against the member to be charged 10. Absent. Since the pressed state and the non-pressed state are repeated, the bent portion of the charging member 1 may cause a fatigue phenomenon, and the flexible electrode 12 on the charging member 1 may be disconnected. The time required for the disconnection varies depending on the material, thickness, shape, etc. of the flexible electrode, and | θ ₄ −θ ₅ |
When the angle exceeds 0 °, the life is reduced to about half or less as compared with the case of 30 ° or less. If it is 20 ° or less, the life is further extended. In the present invention, | θ ₄ −θ ₅ |
The degree is 30 ° or less, more preferably 20 ° or less. The same can be said when the pressing member 6 shown in FIG. 11 or the pressing member 7 shown in FIG. 12 or another pressing member is employed instead of the pressing member 20.

When the charging device is used in such a contact relationship that the service life is prolonged, the contact relationship position of the charging member 1 to the member to be charged 10 at the time of charging is stabilized, and printing unevenness is further eliminated. In addition, disconnection of the electrode is reduced. FIG.
In order to extend the life of the charging member described with reference to FIG. 5 and FIG. 27, the condition that the difference in the bending angle between the charging position and the non-charging position of the charging member is 30 ° or less, more preferably 20 ° or less is as follows. Whether the charging member is mechanically forward / reversely rotated and pressed / non-pressed against the member to be charged, or is pressed / non-pressed by electrostatic adsorption / non-adsorption by a semiconductive member, Whether a member is pressed or non-pressed by using a pressing member, or is pressed or non-pressed depending on the presence or absence of frictional charging with the moving surface of the member to be charged, and furthermore, it is pressed or non-pressed by an appropriate combination of these. Whatever is pressed,
The present invention can be applied to a flexible charging member that is widely used by bending, including the flexible charging member disclosed in this specification.

In order to extend the life of the charging member described with reference to FIG. 26, the bending angle of the charging member in the charging posture is 45 ° or less, more preferably 30 °.
Also in the following conditions, the charging member is pressed and non-pressed by electrostatic adsorption and non-adsorption by the semiconductive member, even if the charging member is mechanically rotated forward and reverse to be pressed and non-pressed against the member to be charged. A non-pressed or non-pressed member employing a pressing member, a non-pressed or non-pressed member with or without frictional electrification with the surface of the moving object, and a suitable combination of these. Therefore, the present invention can be applied to a flexible charging member that is widely bent and used, including the flexible charging member disclosed in this specification, regardless of whether it is pressed or non-pressed.

FIG. 28 shows a charging member in still another example of the charging device to which the present invention can be applied. This charging member 1 has a flexible linear electrode 12 on a flexible insulating member 11.
However, the downstream end 1b in the direction of movement of the surface of the member to be charged has a comb-tooth shape. In comparison with the case where the surface is not charged, the surface is shifted at a distance in the moving direction of the surface of the member to be charged, and is distant. Therefore, even when the humidity is high, and even if the electrode density in the direction crossing the surface direction of the member to be charged is increased in order to obtain a highly accurate image, the leak between the adjacent electrodes 12 is suppressed, and the printing is performed accordingly. No mistakes occur.

In the case of this charging member, the comb-like shape on the upstream side is determined by the surface moving speed of the charged body 10 and the shift distance between the adjacent flexible electrode tips 121 in the moving direction of the charged body surface. Assuming that the printing delay time between the flexible electrode tip 121 and the downstream electrode is t ₁ [sec], the printing signal from the downstream electrode needs to be generated with a delay of t ₁ [sec]. In that case, by making the pulse cycle time of printing out of an integral multiple and 1 / integer multiple of t ₁ ,
The print signals applied to the upstream and downstream electrodes 12 do not overlap, and therefore the peak voltage applied to the charging member 1 can be reduced. Further, it is desirable that each print signal is shifted by half of the print pulse cycle time because the peak voltage can be further reduced.

FIG. 29 shows a charging member in still another example of the charging device to which the present invention can be applied. The charging member 1 has a flexible linear electrode 12 provided on a flexible insulating member 11, and the downstream end 1b in the moving direction of the surface of the member to be charged has a three-stage comb tooth shape. ing. Also in this case, the distance between the distal end portions 121 of the adjacent flexible electrodes 12 is longer than that in the case where they are not comb-shaped. Therefore, also in this case, even at high humidity, Even if the electrode density in the direction crossing the surface direction of the member to be charged is increased in order to obtain a high-precision image, leakage between the adjacent electrodes 12 is suppressed, and printing errors and the like do not occur.

Further, as can be seen from this example, the flexible insulating member 11 may be formed in any shape as long as the distance between the discharge end portions 121 of the adjacent flexible electrodes 12 increases.
Alternatively, the end of the electrode 2 may be processed. In short, it suffices to dispose adjacent ones of the flexible linear electrodes of the charging member, which are in charge of discharging, of the flexible linear electrodes in the direction of movement of the surface of the member to be charged. Along with this, the end of the flexible insulating member may be formed in an irregular shape like a comb tooth.

In the case of the charging member 1 shown in FIG.
Similarly to the charging member of No. 8, the comb-shaped upstream-side comb-shaped member is determined by the surface moving speed of the charged body 10 and the shift distance in the moving direction of the charged body surface between the adjacent flexible electrode tips 121. Assuming that the printing delay time between the flexible electrode tip 121 and the downstream electrode is t ₂ and t ₃ [sec] from the upstream, respectively, the printing signal of the downstream electrode is only t ₂ and t ₃ [sec]. It needs to occur late. In that case, by setting the printing pulse cycle time to be outside the integral multiples and 1 / integer multiples of t ₂ and t ₃ , the print signals applied to the respective electrodes do not overlap, and therefore, the applied peak voltage is reduced. Can be reduced. Also,
It is preferable that each print signal is shifted by 1/3 of the print pulse cycle time because the peak voltage can be further reduced.

FIG. 30A shows a charging member of still another example of the charging device to which the present invention can be applied. In this example, a plurality of (two in the illustrated example) charging members 1 are provided.
Each of the plurality of charging members 1 has a flexible insulating member 11 on which a flexible linear electrode 12 is provided.
Are arranged so as to be shifted from each other by a distance in the surface movement direction. The electrode 12 of the charging member 1 (1X) on the upstream side and the electrode 12 of the charging member 1 (1Y) on the downstream side are provided so as not to overlap with each other in the moving direction of the surface of the member to be charged. Here, the electrodes 12 arranged in the direction perpendicular to the direction of movement of the surface of the member to be charged on the upstream charging member 1X.
The electrodes 12 of the downstream charging member 1Y are arranged so as to correspond to the respective intermediate positions. As a result, a printing density that is twice the printing density of each of the flexible electrodes 12 on the upstream side and the downstream side is realized as a whole.

In the illustrated example, the charging member 1 on the upstream side
The displacement distance between the discharge end of X and the discharge end of the downstream charging member 1Y in the moving direction of the surface of the member to be charged is “moving speed of the surface of the member to be charged [mm / sec] × t ₄ [sec]”. is there. FIG.
8, the flexible electrode tip 12 on the upstream side
1 and to print delay time t ₄ and that of the downstream side (second), the print signal of the downstream side of the electrode 12 needs to be delayed by t ₄ (seconds). In that case, by setting the printing pulse cycle time to be outside the integral multiple and 1 / integer multiple of t ₄ , the print signals applied to the upstream and downstream electrodes do not overlap, and therefore, the peak voltage is reduced. Can be reduced. Further, it is preferable that each print signal is shifted by half of the print pulse cycle time because the peak voltage can be further reduced.

In this example, two charging members are used. However, when three or more charging members are used, the printing density is further increased. In addition, these two charging members 1
May be arranged independently as shown in FIG. 30 (B), or may be sandwiched together by a pair of holding members 2 and pressing members 3 as shown in FIG. 30 (C). Is also good. Alternatively, as shown in FIG. 30 (D), one flexible insulating member 1
1 may be used in common, an upstream electrode 12 and a downstream electrode 12 may be provided on this, and the insulating member 11 may be bent into two to form an upstream charging member 1X and a downstream charging member 1Y. .

When the charging members are separately held as shown in FIG. 30B, the positioning accuracy of each charging member in a direction perpendicular to the surface direction of the member to be charged is important. Attention should be paid to this point. FIG.
When holding as shown in FIG. 30C or forming as shown in FIG. 30D, the positional accuracy of each charging member in the direction perpendicular to the direction of movement of the surface of the member to be charged is determined by sandwiching the charging member. It is almost determined at the time, and the positioning operation when attaching the charging device becomes relatively easy.

Each of the charging members 1 shown in FIGS. 28 to 30 may employ one or more of the above-described ventilation holes 13, pressing fins 15, and semiconductive members 14. FIG.
FIG. 3 shows an example in which the semiconductive member 14 is provided at an end 111 of the charging member 1 shown in FIG.
2 shows an example in which the semiconductive member 14 is provided on the entire surface of the charging member 1 shown in FIG. According to these charging members, the end portion 1b of the charging member is formed in a comb-like shape, so that warpage or the like is likely to occur at the end portion. Since the object to be charged 10 is electrostatically attracted, it is effective in making the discharge distance uniform.

Next, as shown in FIG. 25, when the surface of the member to be charged 10 is charged, the member takes a charging posture in which the member is attracted to the member to be charged 10 when the surface of the member is not charged. With reference to FIGS. 33 to 36, a specific example of the charging device in the non-charging posture in which the charging member 1 has the configuration shown in FIG. 17B will be described. FIG.
The charging member 1 (charging member of the type shown in FIG. 17B) in the charging device shown in each of FIGS. 3 to 36 has a length in which the flexible insulating member 11 is along the moving direction of the surface of the member to be charged. Is made of PET (polyethylene terephthalate) having a thickness of about 28 mm and a thickness of about 50 μm. The flexible electrode 12 is formed into an electrode shape by an excimer laser after nickel is entirely deposited on one surface of the flexible insulating member 11. The thickness is about 1 μm. The semiconductive member 14 is made of polyethylene in which conductive carbon is dispersed, has a thickness of about several μm, and has a width d [mm along the surface direction of the member to be charged near the tip of the flexible insulating member 11. (See FIG. 17B).

First, the charging device shown in FIG. 33 will be described. As shown in FIG. 25, the electrode bending angle θ ₂ [degree] at the time of adsorption (at the time of charging) and the time of non-attraction (at the time of non-charging) similar to those shown in FIG.
The state of the charging device when the difference in the electrode bending angle θ ₃ [degree] is small is shown. The support point h of the charging device is
Is about 8 mm away from The width d [mm] of the semiconductive member 14 is about 12 mm, and the voltage applied to the semiconductive member 14 at the time of suction in FIG. 33A is 400V. In the case of non-adsorption shown in FIG.
The voltage applied to 4 is 0V. In the case of the adsorption shown in FIG. 2A, the entire semiconductive member 14 is adsorbed on the member 10 to be charged, and is bent at an angle of θ ₂ = about 17 degrees at a point k where the semiconductive member 14 disappears. In the case of non-adsorption shown in FIG. 8B, the curve is bent at an angle of θ ₃ = about 4 degrees at the α point downstream of the k point, and the k point is bent at an angle of about 0 to 4 degrees.
Therefore, when adsorption and non-adsorption are repeated, the k point is almost 4
The bending and elongation from degrees to 17 degrees is repeated, and the bending and elongation from 0 to 4 degrees is repeated at the α point, and the bending and elongation from the α point to the k point is repeated from the k point to the α point. become. Therefore, the k point is the most stressed,
The bending and elongation from 4 degrees to 17 degrees, that is, θ ₂ −θ
That is, a load of ₃ degrees is applied. Here, the k point is not is under theta ₃ = about 4 degrees of the load from the beginning, but rather the angle is smaller load on the k point is considered smaller, a steady state, the Since the surface of the charged body 10 is not moved, the load is sufficiently small as compared with fatigue in which adsorption and non-adsorption are repeated, and can be almost ignored.

Next, the charging device shown in FIG.
This is a charging device in the case where the difference between the electrode bending angle θ ₂ [degrees] during adsorption and the electrode bending angle θ ₃ [degrees] during non-adsorption is medium. The supporting point h of the charging member 1 of this device is located at a position about 8 mm away from the charged body 10 as in FIG. The width d [mm] of the semiconductive member 14 is about 15 m
m, which is longer than that shown in FIG. The voltage applied to the semiconductive member 14 during suction shown in FIG. 34A is 400 V, and the voltage applied to the semiconductive member 14 during non-suction shown in FIG. is there. In the case of the adsorption shown in FIG. 7A, the entire semiconductive member 14 is adsorbed on the member to be charged 10 and is bent at an angle of θ ₂ = approximately 33 degrees at the point m where the semiconductive member 14 disappears. In the case of non-adsorption shown in FIG. (B), θ is set at n point downstream of point m.
₃ = bend at an angle of about 7 degrees, and point m is bent at an angle near 0 to 7 degrees. Therefore, when adsorption and non-adsorption are repeated, the bending and elongation of point m is repeated from approximately 7 degrees to 33 degrees, and the bending and elongation of point n is repeated from 0 degrees to 7 degrees. Between the points, bending and elongation of n points or more and m points or less are repeated. Therefore, the load is applied most at the m point, and bending and elongation from 7 degrees to 33 degrees, that is, a load of θ ₂ −θ ₃ [degrees] is applied. Here, the point m is not is under theta ₃ = about 7 degrees of load than originally more the angle is small m
It is considered that the load on the point is smaller, but it is a steady state, and the charged object is not moving. Therefore, the load is sufficiently smaller than fatigue caused by repeated adsorption and non-adsorption, and is almost ignored. be able to.

The charging device shown in FIG. 35 has an electrode bending angle θ ₂ [degrees] at the time of suction and an electrode bending angle θ ₃ at the time of non-suction.
This is a charging device when the difference in [degree] is large. The support point h of the charging member 1 of this device is located at a position about 8 mm away from the member to be charged 10 as in FIG. The width d [mm] of the semiconductive member 14 is about 17 mm, and FIG.
Longer than the ones. Further, the voltage applied to the semiconductive member 14 at the time of suction in FIG.
The voltage applied to the semiconductive member 14 at the time of non-adsorption in FIG. 35B is 0V. In the case of the adsorption shown in FIG. 3A, the entire semiconductive member 14 is adsorbed on the member 10 to be charged, and is bent at an angle θ ₂ = about 50 degrees at the point o where the semiconductive member 14 disappears. In the case of the non-adsorption state shown in FIG. 8B, it is bent at an angle of about ₃ degrees at a point p downstream of the point o,
Point o is bent at an angle near 0 to 7 degrees. Therefore, when the adsorption and the non-adsorption are repeated, the bending and elongation of the point o from approximately 7 degrees to 50 degrees is repeated, and the bending and the elongation of the point p from 0 degrees to 7 degrees are repeated. Between the points, bending and elongation at points p and o are repeated. Therefore, the load is applied most at point o, and bending and elongation from 7 degrees to 50 degrees, that is, a load of θ ₂ −θ ₃ [degrees] is applied. Here, the point o is θ
₃ = A load of about 7 degrees is applied, and it is considered that the smaller the angle is, the smaller the load on point o is. The steady state is the state where the surface of the member to be charged does not move. Therefore, the load is sufficiently small as compared with fatigue in which adsorption and non-adsorption are repeated, and can be almost ignored.

The charging device shown in FIG. 36 is at the time of suction (at the time of charging posture).
Is shown. The supporting point h of the charging member 1 of this charging device is located at a position about 8 mm away from the member 1 to be charged, and the width d [mm] of the semiconductive member 14 is about 17 mm, as in FIG. . The difference from FIG. 35 (A) is that
That is, the voltage applied to the semiconductive member 14 is 50V. Since the attraction force is weakened, a part of the semiconductive member 14 is attracted to the member to be charged 10 and the semiconductive member 14 is lost.
It is bent at an angle of θ ₂ = about 30 degrees at a point q downstream of the point. In the case of non-adsorption, as in FIG.
At the point, it bends at an angle of θ ₃ = about 7 degrees, and at point q, it bends at an angle near 0 to 7 degrees. Therefore, when the adsorption and the non-adsorption are repeated, the bending and elongation of the point q from about 7 degrees to 30 degrees are repeated, and the bending and the elongation of the point p from 0 degrees to 7 degrees are repeated. Between the points, bending and elongation at points p and q are repeated. Therefore, the load is applied most at the q point, and bending and elongation from 7 degrees to 30 degrees, that is, a load of θ ₂ −θ ₃ [degrees] is applied. Here, a load of about θ ₃ = approximately 7 degrees is applied to the q point from the beginning.
It is considered that the load on the point is smaller, but it is a steady state and the non-charged body etc. is not moving, so it is a sufficiently small load compared to the fatigue that repeats adsorption and non-adsorption, and is almost ignored. be able to.

In each of the charging devices shown in FIGS. 33 to 36, when the adsorption posture (charging posture) and the non-adsorption posture (charging posture) with respect to the electrode 12 of the charging member 1 are repeated,
The number of repetitions until the electrode is disconnected and (θ ₂ −θ
FIG. 37 shows the relationship with ₃ ). If (θ ₂ −θ ₃ ) is 30 degrees or less, the number of repetitions before disconnection increases, and 2
It can be seen that if the angle is equal to or less than 0 degrees, the temperature rises dramatically.

FIG. 38 shows that the thickness of the flexible insulating member 14 is
It is a result of the same experiment in the case of using PET of 50 μm. Although the absolute value of the number of repetitions before disconnection is different, the relative relationship with (θ ₂ −θ ₃ ) is the same, and the same applies to changes in the Young's modulus of the charging member. I can say. FIG. 39 shows the number of repetitions up to disconnection when the thickness of the flexible electrode was set to about 0.1 μm and (θ ₂ −
θ ₃ ). Again, although the absolute value of the number of repetitions before disconnection is different, (θ ₂ −
θ ₃ ) are equivalent.

Next, as in the charging device shown in FIG.
40 and 41 show a specific example of a charging device employing the charging member 1 shown in FIG.
In the charging device of FIG. 40, the charging posture or the non-charging posture of the charging member 1 is controlled by pressing / non-pressing the pressing member 100. Also, in the charging device of FIG. 41, by changing the pressing position and pressing width of the pressing member 100, the charging member bending angle θ when the pressing member 100 presses the charging member 1 against the member to be charged 10 as compared with FIG. ₄ is bigger. In the charging device of FIG. 40, the difference in the bending angle between the charging position of the charging member 1 and the non-charging position (θ ₄ −θ ₅ )
= 23 ° -6 ° = 17 °. Also in this case, if the angle difference (θ ₄ −θ ₅ ) is 30 degrees or less, the number of repetitions until disconnection increases, and if the angle difference is 20 degrees or less, it increases more dramatically.

33 to 36, 40 and 41
In the charging device described with reference to_Two−θ_Three(Or θ
_Four−θ_Five) As a means to obtain a good value
The width of the conductive member, the voltage applied to the semiconductive member,
It shows that the pressing position and the pressing width of the pressing member are changed
However, in addition to this, the supporting position of the charging member is
If θ_Two(Θ_Four) And θ_Three(Θ_Five) Becomes smaller and charged
Θ also depends on the support angle of the device_Two(Θ_Four) And θ
_Three(Θ_Five) Can be changed. In addition, the charging member and the
By increasing the friction coefficient of the charged body, the surface of the charged body
Θ when moving _Two(Θ_Four)
Can also. Also, by frictional charging between the charging member and the member to be charged
When using adsorption force, the difference between each charging series should be small.
The absorption force weakens by making_Two(Θ_FourChange)
Can also be.

FIG. 42 shows still another electric circuit of the charging device to which the present invention can be applied, and the state of printing. This device has a charging member 1 of the type shown in FIG.
As shown in FIG. 42 (A), unlike the charging device of FIG. 17 (B), a voltage of about +1.3 kV is applied to the semiconductive member 14, and the semiconductive member 14 and the charged object 10 A discharge to the member to be charged 10 is generated at the contact start portion of the member, and the charging member 1 and the member to be charged 10 are attracted and at the same time, the member to be charged 1
0 is uniformly charged to about +750 V over the entire surface. This is a case where the charged body 10 has a negative polarity or zero or a slightly positive polarity before the contact start portion between the charged body 10 and the semiconductive member 14.
Even if a voltage of 1.3 kV is applied, the semiconductive member 14
When there is a portion where a high positive polarity potential is present on the non-charged member 10 such that no discharge occurs at the contact start portion of the non-charged member 10 with the charged member 10, charging cannot be performed uniformly and AC is superimposed. It is necessary to devise ways to equalize such things. Conversely, about +1.
When a high potential of 85 kV or more is on, about +
Since the charge can be uniformly removed up to 1.85 kV, for example, at the contact start portion between the semiconductive member 14 and the member 10
When a high potential of about +750 V or more is applied to the semiconductor device 14, the charged object 10 can be discharged to about +750 V by applying a potential of about +200 V to the semiconductive member 14.

As shown in FIG. 42 (B),
Is charged uniformly at about +750 V by the method described above, but no discharge occurs near the tip of the flexible electrode 12 because the flexible electrode 12 is in an open state. However, as shown in FIG. 42 (C), when the flexible electrode 12 is grounded by a signal, the potential difference between the charged body 10 and the flexible electrode 12 becomes about 750 V, discharge starts, and the print signal The portion of the charged body 10 corresponding to
A latent image is formed.

FIG. 43 shows still another electric circuit of the charging device to which the present invention can be applied. The charging member 1 is the same as that shown in FIG. About +10 for the semiconductive member 14
Since a voltage of 0 V is applied, the semiconductive member 14 and the member to be charged 10 are electrostatically attracted. The flexible electrode 12 is normally biased to a voltage equal to or lower than the discharge start voltage, for example, +350 V. Discharge can be started with a signal voltage of, for example, 200 V, and the withstand voltage of the signal circuit can be reduced. This method is also applicable to, for example, the charging device shown in FIG.

[0092]

As described above, according to the present invention, there is provided an image forming apparatus for charging a member to be charged by bringing a member having at least a flexible electrode into contact with the member to be charged. With the charging device, the charging member is repeatedly brought into pressure contact and non-pressure contact with the member to be charged with repetition of charging and non-charging of the surface of the member to be charged, and even if the member is repeatedly bent, the charging member is not charged. It is possible to provide a charging device in which the occurrence of damage such as cracks and disconnections of the electrodes is suppressed, and the occurrence of charging failure is suppressed accordingly.

[Brief description of the drawings]

FIG. 1A is a perspective view of an example of a charging device to which the present invention can be applied, and FIG. 1B is a side view thereof.

FIG. 2 is a perspective view of a part of an example of a charging member in the apparatus shown in FIG.

3 is a perspective view of a part of another example of the charging member in the device shown in FIG.

4A is a perspective view of a part of still another example of the charging member in the device shown in FIG. 1, and FIG. 4B is a side view thereof.

FIG. 5 is a perspective view of a part of still another example of the charging member in the device shown in FIG.

FIG. 6 is a perspective view of a part of still another example of the charging member in the device shown in FIG.

FIG. 7 is a perspective view of a part of still another example of the charging member in the device shown in FIG.

8 is a perspective view of a part of still another example of the charging member in the device shown in FIG.

9A is a perspective view of a part of still another example of the charging member in the device shown in FIG. 1, and FIG. 9B is a side view of a charging device using the charging member.

10A is a perspective view of a part of an example of a charging device to which the present invention can be applied, which is slightly different in configuration from the charging device of FIG. 1, and FIG. 10B is a side view thereof. .

11A is a perspective view of a part of another example of the charging device to which the present invention can be applied, which has a slightly different configuration from the charging device of FIG. 1, and FIG. FIG.

FIG. 12 is a side view of still another example of a charging device to which the present invention can be applied, which has a slightly different configuration from the charging device of FIG. 1;

FIG. 13 is a diagram showing an example of an electric circuit that can be employed in a charging device to which the present invention can be applied.

FIG. 14 is a diagram illustrating another example of an electric circuit that can be employed in a charging device to which the present invention can be applied.

FIG. 15 is a diagram showing still another example of an electric circuit that can be employed in a charging device to which the present invention can be applied.

FIG. 16 is a perspective view of a part of a charging member in an example of a charging device to which the present invention can be applied.

17A is a perspective view of a part of a charging member in another example of a charging device to which the present invention can be applied, and FIG. 17B is a diagram illustrating a modification of the charging member shown in FIG. It is a partial perspective view.

FIG. 18 is an explanatory diagram of an electrostatic attraction effect of a charging member provided with a semiconductive member.

FIG. 19A is a perspective view of a part of an example of a charging member that can be employed in place of the charging member shown in FIG. 17, and FIG. 19B is a plan view thereof.

20A is a perspective view of a part of another example of the charging member that can be employed in place of the charging member shown in FIG. 17, and FIG. 20B is a plan view thereof.

FIG. 21 is a diagram showing a part of still another example of the charging member which can be employed in place of the charging member shown in FIG. 17, and an electric circuit of a charging device using this member.

FIG. 22 is a diagram illustrating a charge removal function by the semiconductive member in the charging member provided with the semiconductive member.

FIG. 23 is a view showing another example of the charge removing function of the charging member provided with the semiconductive member by the semiconductive member.

FIG. 24A is a perspective view of a part of a charging member in still another example of a charging device to which the present invention can be applied, and FIG. 24B is a side view of the charging device.

25A and 25B show how the charging member having a semiconductive member bends in a state where the charging member is adsorbed and non-adsorbed to the member to be charged, and FIG. 25A shows a state in which the charging member is bent in the adsorption state; () Is a diagram showing a bent state in a non-sucking state.

FIG. 26 is a diagram illustrating a state in which a charging device including a semiconductive member is in contact with a charged object by suction.

FIG. 27 is a side view showing still another example of a charging device to which the present invention can be applied.

FIG. 28 is a perspective view of a part of a charging member in still another example of a charging device to which the present invention can be applied.

FIG. 29 is a perspective view of a part of a charging member in still another example of the charging device to which the present invention can be applied.

FIG. 30A is a perspective view of a part of each of two charging members in still another example of the charging device to which the present invention can be applied;
FIG. (B) is a side view showing an example of an attached state of the charging member, FIG. (C) is a side view showing another example of an attached state of the charging member, and FIG. It is a perspective view showing an example.

FIG. 31 is a perspective view of a part of a modification of the charging member shown in FIG. 28;

FIG. 32 is a perspective view of a part of a modification of the charging member shown in FIG. 29;

FIG. 33 shows a specific example of a change in the bending of the charging member in a state where the charging member including the semiconductive member is attracted to and attracted from the member to be charged, and FIG. (B) is a diagram showing a bent state in a non-sucking state.

34A and 34B show another specific example of a change in bending of the charging member similar to FIG. 33. FIG. 34A shows a bending state in a suction state, and FIG. 34B shows a bending state in a non-suction state. FIG.

35A and 35B show still another specific example of the change in the bending of the charging member similar to that of FIG. 33. FIG. 35A shows the bending state in the suction state, and FIG. 34B shows the bending state in the non-suction state. FIG.

FIG. 36 is a view showing still another specific example of the bending change of the charging member similar to that of FIG. 33, and showing a bending state in a suction state.

FIG. 37 shows an example of a relationship between a bending angle difference between a flexible charging member when it is attracted to a member to be charged and when it is not attracted, and the number of repetitions of adsorption and non-adsorption until the electrode on the charging member is disconnected. FIG.

FIG. 38 shows another relationship between the difference in the bending angle between the time when the flexible charging member is attracted to the member to be charged and the time when it is not attracted, and the number of repetitions of adsorption / non-adsorption until the electrode on the charging member is disconnected. It is a figure showing an example.

FIG. 39 shows the relationship between the difference in the bending angle between when the flexible charging member is attracted to the member to be charged and when it is not attracted, and the number of repetitions of adsorption / non-adsorption until the electrode on the charging member is disconnected. It is a figure showing the example of.

FIG. 40 shows a specific example of a change in bending of the charging member in a state in which the flexible charging member is pressed against the member to be charged by the pressing member, and FIG. 40A shows a bending state in the pressed state. (B) is a diagram showing a bent state in a non-pressure-contact state.

FIG. 41 is a view showing another specific example of the change in the bending of the charging member similar to that of FIG. 40, and is a view showing the bending state in the pressure contact state.

FIG. 42 is a diagram showing still another electric circuit of the charging device to which the present invention can be applied and a state of printing.

FIG. 43 is a diagram showing still another electric circuit of the charging device to which the present invention can be applied.

[Explanation of symbols]

A Charger to which the present invention can be applied 10 Charged object 1 Substantially sheet-shaped flexible charging member 1a Upstream end of charging member 1b Downstream end of charging member 1 11 Flexible insulating member 111 Flexible Downstream end to free tip 111a of insulating member 11a Oblique end face of member end 111b End face (free end) of member end 111 12 Flexible electrode 121 Discharge tip of electrode 12 2 Holding member 21 Holding member 2 rotary shaft 3 pressing member PR pressing device SP spring SOL solenoid 4 signal cable B, C, D Charging device to which the present invention can be applied 5 elastic member 6, 7 pressing member 71 pressing member 72 pressing member holding member 101 drive power supply unit 102 Image signal forming unit 12c Flexible control electrode 103 Driving power supply unit 104 Image signal forming unit 101a Driving power supply E The present invention is applied. Charging device 13 air vent F charging device to which the present invention can be applied 14 semiconductive member PW power supply 101b driving power supply 10D conductive drum of the charged body 10 G charging device to which the present invention can be applied 15 pressing fins 20 pressing member 1X upstream side Charging member 1Y Downstream charging member 100 Pressing member

Claims (9)

[Claims] 1. A charging device for an image forming apparatus, wherein at least a flexible charging member including a flexible electrode as a component is brought into contact with a member to be charged, and the member to be charged is charged. When charging the member to be charged, the first portion on the downstream side in the moving direction of the surface of the member to be charged is pressed against the member to be charged, and the second portion on the upstream side adjacent to the first portion is formed by the second portion. When the first portion is bent and placed in a charging position separated from the surface of the member to be charged, and when the member to be charged is not charged, the member is placed in a non-charging position released from the charging position and the second portion. A charging device, wherein a difference between an angle between a charging posture and a non-charging posture between the portion and the surface of the member to be charged is 30 ° or less. 2. The method according to claim 2, wherein the second portion and the surface of the charged member form
The charging device according to claim 1, wherein a difference between the angle in the charging position and the angle in the non-charging position is 20 ° or less. 3. The charging member includes a flexible member including a flexible electric insulating member and the flexible electrode provided on one surface of the flexible member. The surface on the opposite side is directed to the member to be charged and is brought into contact with the member to be charged, and the member to be charged can be charged by discharging from the electrode, and the discharging is performed from the first portion or the vicinity thereof. The charging device according to claim 1, wherein the charging device is generated. 4. The charging device according to claim 3, wherein the first portion includes a tip of the charging member, and the portion where the discharge occurs is a tip of the charging member. 5. The resistance value of the electrode tip portion is 10 ¹ to 10
The charging device according to claim 4, wherein the charging device has a range of ⁸ Ωcm. 6. The charging device according to claim 3, wherein a plurality of the electrodes are provided, and the electrodes are arranged at intervals in a direction substantially orthogonal to a moving direction of the surface of the member to be charged. . 7. A semiconductive member directed to the surface of the charged member is provided at least on a portion of the charging member which generates discharge, and the charging member is switched by switching a voltage applied to the semiconductive member. 7. The charging device according to claim 1, wherein the charging device is placed in the charging position or the non-charging position. 8. A charging device according to claim 1, further comprising means for pressing the charging member against the member to be charged, wherein the charging member is placed in the charging position or the non-charging position depending on the magnitude of the pressing force applied to the charging member by the pressing means. 7. The charging device according to any one of claims 1 to 6. 9. The charging member according to claim 1, wherein the charging member is placed in the charging position or the non-charging position depending on the presence or absence of frictional charging in accordance with the presence or absence of relative movement between the charging member and the surface of the member to be charged. Charging device.