JP2001034033A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain stable electrifying processing over a long term and to always obtain an excellent image by supplying electrification accelerating particles to an electrifying member from a developing means side. SOLUTION: An electrifying sponge roller 2A is rotatably born and supported on an edge side of a supporting member 9 freely turned centering around a center axial line O of an image carrier 1. A control circuit part controls a driving mechanism of the member 9 in specified sequence so as to perform such position switching control that the member 9 is rocked and moved counterclockwise to set the roller 2A to a 1st position R1 where the roller 2A is separated from a developing sleeve 4a of a developing device 4 by a specified distance and the member 9 is rocked and moved clockwise to set the roller 2A to a 2nd position R2 where the roller 2A is brought into contact with the sleeve 4a through a developer thin layer Ta. Developer T and the electrification accelerating particles Z are moved between the roller 2A and the sleeve 4a by the relation of potential between the roller 2A and the sleeve 4a in a state where the roller 2a is at the 2nd position R2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using a contact charging device as a charging device for an image carrier.

More specifically, the present invention relates to an image forming apparatus using contact charging means in which charging is dominant by interposing charge promoting particles at least in a nip portion between an image carrier and a contact charging member.

[0003]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus, in order to form an electrostatic latent image on an image carrier, an electrophotographic photosensitive member, an electrostatic recording dielectric and the like are used. A charging process for charging the image carrier to a uniform potential is required, and as such a charging means, a corona charging device or the like which is not in contact with the image carrier has been used. However, the corona charging device has problems such as generation of a large amount of ozone and application of a high voltage of about 10 KV between the charging device and the image carrier.

As a charging means for solving these problems,
In recent years, a so-called contact charging device that uniformly charges an image carrier by applying a voltage to a charging member (contact charging member) that directly contacts the image carrier has been proposed and put into practical use.

A) Roller charging device [0005] A typical example of the above-mentioned contact charging device is a roller charging device 2X as shown in FIG. The roller charging device 2X uses a conductive roller (hereinafter, referred to as a charging roller) as the contact charging member 2Xa.
a is a composite layer roller composed of a core metal 2Xd, a conductive base roller portion 2Xc integrally formed in a roller shape around the core metal, and a medium resistance surface layer 2Xb further formed on the outer peripheral surface thereof. is there.

Reference numeral 1 denotes an image bearing member as a member to be charged, for example, a rotary drum type electrophotographic photosensitive member. The image carrier 1 is driven to rotate at a predetermined peripheral speed in the clockwise direction of arrow a.

The charging roller 2Xa holds both ends of the cored bar 2Xd by a bearing member so as to be rotatable, and presses the image carrier 1 in parallel with the image carrier 1 with a predetermined pressing force. The image carrier 1 rotates in the counterclockwise direction of arrow b following the rotation of the image carrier 1.

[0008] A predetermined voltage is applied between the charging roller 2Xa and the image carrier 1 by a power supply S1, whereby the image carrier 1 is charged to a uniform potential.

Here, regarding the application of the voltage,
. A method of applying only a DC voltage (DC method),. There are two methods of applying a voltage obtained by superimposing an AC voltage on a DC voltage (AC method).

In the case of the DC system, for example, in order to set the potential on the image carrier 1 to -600 V, it is necessary to use -1300.
It is necessary to apply a voltage of about V. In the case of the AC method, an AC voltage in which a DC voltage is
By applying the voltage of 00 Vpp or more, the potential on the image carrier 1 can be similarly set to -600 V.

The charging mechanism in this case is as follows.
In any of the DC system and the AC system, the Pasche
In accordance with the n (Paschen) law, the discharge phenomenon occurs at a certain distance between the charging roller 2Xa and the image carrier 1 as shown by a region A in FIG. 21, that is, in a region satisfying the Paschen's law. Occurs to charge the image carrier 1.

However, as can be understood from the charging mechanism described above, such a contact charging device performs the same operation as the corona charging device described above in a minute space, and the generation of ozone is caused by the corona charging. Although it is much smaller than the device, it still occurs. When this ozone generates nitrogen oxide and adheres to the image carrier 1, the resistance thereof is low, so that an image failure due to poor charging occurs.

B) Magnetic brush charging device On the other hand, a charging process which is contact charging but does not have the above-mentioned problem of generation of ozone and can further reduce the voltage applied to the charging device. Kaihei 6
It has been proposed in, for example, US Pat.

The feature of this charging process is that the surface potential of the image carrier 1 can be made substantially the same as the voltage applied to the charging device. This is because the contact charging member and the image carrier can be used without using a discharge phenomenon. This is made possible by injecting charges into the image carrier by directly transferring charges to and from the surface (injection charging process).

Several types of charging devices have been proposed as contact charging devices (injection charging devices) for realizing the above-described injection charging process.

FIG. 22 shows a schematic configuration model diagram of an example of a magnetic brush type injection charging device (magnetic brush charging device) 2Y as a typical example. The magnetic brush charging device 2Y of this example is of a sleeve rotation type.

Reference numeral 2Ya denotes an apparatus housing, and 2Yb denotes a non-magnetic sleeve (hereinafter, referred to as a charging sleeve) as a magnetic brush holding member, a part of which is exposed to the outside and rotatably disposed in the apparatus housing 2Ya. is there.

Reference numeral 2Yc denotes a magnet roller as a magnetic field generating means, which is inserted into the charging sleeve 2Yb and is fixed so as not to rotate. The charging sleeve 2Yb moves around the fixed magnet roller 2Yc around an arrow b. Is rotated clockwise.

Reference numeral 2Yd denotes conductive magnetic particles (magnet carrier, hereinafter referred to as charged carrier) housed in the apparatus housing 2Ya.

Reference numeral 2Ye denotes a conductive magnetic brush layer thickness regulating member (hereinafter referred to as a regulating blade) provided at an opening of the apparatus housing 2Ya, which is attached to the charging sleeve 2Yb with a predetermined small gap. Have been. The regulating blade 2Ye is magnetically constrained and carried as a magnetic brush by the magnetic field of the magnet roller 2Yc in the charging sleeve 2Yb, and is conveyed in rotation with the rotation of the charging sleeve 2Yb to be taken out of the apparatus housing 2Ya. The amount of the carrier 2Yd, that is, the layer thickness of the magnetic brush is regulated to a predetermined value, and serves to form a magnetic brush coat layer of an appropriate amount of the charged carrier.

The magnetic brush charging device 2Y is provided such that the charging sleeve 2Yb is close to the image carrier 1 in parallel. The charging sleeve 2Yb and the image carrier 1 are opposed to each other with a predetermined small gap. In this gap, the magnetic brush of the charge carrier on the charging sleeve 2Yb, which is conveyed with the layer thickness regulated by the regulating blade 2Ye as described above, comes into contact with the image carrier 1 as a contact charging member and the image carrier One surface is rubbed with the magnetic brush. N is the magnetic brush contact nip portion (charging portion, charging area). The magnetic brush of the charge carrier that has passed through the charging section N is returned to the charge carrier pool in the apparatus housing 2Ya by the subsequent rotation of the charging sleeve 2Yb and transported.

In the magnetic brush charging device 2Y of this embodiment, the regulating blade 2Ye is supplied with -600 V from the power supply S1.
DC voltage is applied. For this reason, the portion of the image carrier 1 that is in contact with the charged carrier of the magnetic brush tends to have the same potential. At this time, if charges are injected into the image carrier 1 from the charged carrier over the energy barrier on the surface of the image carrier 1, the image carrier 1 is charged. When the energy barrier cannot be exceeded, or when the charged carrier of the magnetic brush and the image carrier 1 are separated,
Again, when the charge moves from the image carrier 1 to the charged carrier, no charging occurs. This phenomenon largely depends on the energy barrier on the surface of the image carrier 1 and the ability to retain electric charges, but when considered as a competitive reaction, the frequency of the opportunity for the charged carrier to come into contact with the image carrier 1 becomes important. .

In order to increase the frequency, the density of the charged carrier 2Yd is increased by reducing the particle size of the charged carrier 2Yd and increasing the magnetic force of the charged carrier 2Yd. In the charging portion N, which is a portion facing the body 1, the rotation direction of the charging sleeve 2Yb is reversed with respect to the traveling direction of the image carrier 1 to increase the relative speed, so that the charge carrier contacts the image carrier 1 per time. Increasing the number of times is effective.

As described above, the surface potential of the image carrier 1 is applied to the charging sleeve by bringing the charge carrier 2Yd serving as a site for injecting charges into the image carrier 1 into contact with the image carrier 1 with a high probability. The potential is almost the same as -600 V, and uniform charging without uneven charging is possible even for a micro part.

However, when the present system is implemented, a mechanism for holding the charged carrier is indispensable, and there are many difficult problems in consideration of the sealing property and the like.

C) Fur-brush charging device Further, as a charging device of a type different from the above-described magnetic brush type, a fur-brush-type injection charging device 2Z (fur-brush charging device) as shown in FIG. 23 has been devised.

The fur brush charging device 2Z uses a fur brush 2Za as a contact charging member. The fur brush 2Za of this embodiment is composed of a core bar 2Zb and a conductive bristle brush portion 2Zc provided around the core bar. Is a rotating brush.

The above-mentioned fur brush 2Za has a core metal 2Z.
b are rotatably held by a bearing member, and are disposed so that their axes are parallel to the image carrier 1 and are pressed against the image carrier 1 with a predetermined pressing force. In the section (charging section) N, the image carrier 1 is rotationally driven in a clockwise direction indicated by an arrow b which is opposite to the rotational direction of the image carrier 1.

In the fur brush type, the role of the magnetic brush by the charged carrier in the magnetic brush type is imparted to the conductive bristles (fur) 2Zc, and the same voltage as in the magnetic brush type is supplied from the power supply S1. The surface of the image carrier 1 is charged by applying the voltage to the brush 2Za, rotating the fur brush as described above, and rubbing the image carrier 1 with the tips of the fur brush.

The fur brush type is advantageous in terms of the method of holding the charge carrier, which is a problem in the magnetic brush type. On the other hand, in order to increase the charging efficiency, the fur brush density may be increased or the fur may be softened while maintaining uniformity. There is a problem in terms of the manufacturing method, such as the need to maintain the properties.

In both the magnetic brush type and the fur brush type, the developer remaining on the image carrier 1 is gradually accumulated on a magnetic brush or a fur brush as a contact charging member. This leads to poor charging. To remove this accumulated developer,
There is a problem that a considerably large device must be attached.

D) Sponge roller charging device A sponge roller type injection charging device 2 (sponge roller charging device) as shown in FIG. 24 has been devised as a charging device that has solved these problems. In this type, a sponge roller 2A (hereinafter, referred to as a charging sponge roller) is used as a conductive / flexible (plastic) contact charging member as a contact charging member, and the upper half of the roller 2A is omitted in the drawing. ), A relatively low-resistance particle Z referred to as a charge-promoting particle is adhered to a vacant portion on the surface of the charge sponge roller 2A, and the charge-promoting particles are attached to the magnetic brush-type charge carrier. Z is equivalent.

The charging sponge roller 2A is disposed with its axis parallel to the image carrier 1 and pressed against the image carrier 1 with a predetermined pressing force, and a contact nip portion (charging portion) At N, the image carrier 1 is driven to rotate in a clockwise direction indicated by an arrow b opposite to the rotational direction of the image carrier 1. A voltage is applied from the power supply S1 to the charging sponge roller 2A, and the surface of the image carrier 1 is charged by rubbing the image carrier 1 with the charge promoting particles on the surface of the charging sponge roller in the charging section N.

FIG. 25 is a schematic configuration diagram of an example of an image forming apparatus using the sponge roller charging device 2. The image forming apparatus of this embodiment is a transfer type electrophotographic process, a cleaner-less system, and a reversal developing type laser beam printer.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member as an image bearing member, which is rotationally driven at a predetermined peripheral speed in a clockwise direction indicated by an arrow a. The image carrier 1 is uniformly charged to a predetermined polarity and potential at a charging portion N by a sponge roller charging device 2 during the rotation process, and the charged surface is subjected to image exposure L by a laser scanner 3. An electrostatic latent image of image information is formed. The electrostatic latent image is reversely developed as a toner image in the developing unit D by the non-contact jumping developing device 4. S1 is a charging bias application power source,
S2 is a developing bias application power supply.

On the other hand, a transfer material P is fed from a paper feed unit (not shown) at a predetermined control timing to a transfer unit M, which is a contact nip between the image carrier 1 and a transfer roller 5 as transfer means. The toner image on the image carrier 1 surface side is sequentially transferred to the surface of the transfer material P while the transfer material P is introduced and is nipped and conveyed by the transfer portion M. S3 is a charging bias application power supply. The transfer material P that has passed through the transfer section M is the image carrier 1
The toner image is introduced into a fixing device 6 of a heat roller type or the like, undergoes a fixing process on the toner image, and is discharged in the rotation direction e of the fixing roller.

After transfer of the toner image onto the transfer material P, a small amount of transfer residual toner remains on the surface of the image carrier 1. The printer of this embodiment is a cleaner-less system device which does not have a dedicated cleaner (cleaning device) for removing the transfer residual toner. The transfer residual toner on the surface of the image carrier 1 continuously rotates the image carrier 1. Accordingly, the developer is carried to the charging section N, further carried to the developing section D, and is subjected to so-called simultaneous cleaning (development simultaneous recovery) by the developing device 4 in the developing section D.

The simultaneous cleaning with development is a method in which the transfer residual toner slightly remaining on the image carrier after the transfer is recovered by a fogging bias at the time of development after the next step. According to this method, the transfer residual toner is collected in the developing device and used in the subsequent steps, so that waste toner can be eliminated, and troublesome maintenance can be reduced. Further, the advantage in terms of space is great, and the size of the image forming apparatus can be reduced.

A major feature of the sponge roller type is that the charge accelerating element Z serving as an injection site contains a developer T (magnetic toner) in a developing container of the jumping developing device 4.
And the developer T containing the charge-promoting particles.
Is a developing sleeve (developing roller) as a developer carrying member
Image bearing member 1 which is applied as a thin layer to
When the development of the electrostatic latent image is being performed, the mixed charge-promoting particles Z also adhere to the image carrier 1 and are carried to the charging unit N via the transfer unit M, thereby promoting the charge. The particles Z reach the charging sponge roller 2A from the developing device 4 along the route indicated by the bold line in the drawing, and the charging promoting particles Z are supplied to the charging sponge roller 2A.

The supply of the charge accelerating particles Z to the image carrier 1 is performed by the non-contact jumping developing device 4 together with the development of the image carrier 1 by the developer T. The charge accelerating particles Z supplied to the image carrier 1 have a charge polarity opposite to that of the developer T, so that the transfer material P is transferred by the transfer device 5 in the transfer section M.
Is left on the image carrier 1 without being substantially transferred to the charging unit N, is carried to the charging unit N, and is collected on the charging sponge roller 2A, so that a new injection site is always obtained.

For this reason, there are relatively few problems such as the difficulty in the method of retaining particles and the method of manufacturing a charging member, which are problems with the magnetic brush type and the fur brush type, and the developer T is supplied by the sponge roller 2-A. Even if it accumulates on the upper side, if the charge accelerating particles Z are supplied more than that, it is possible to suppress the occurrence of poor charging.

In this type, after the transfer of the toner image on the image carrier 1 to the transfer material P, the cleaning of the image carrier 1 must be eliminated. The carrier is charged and charged in the same manner as the image carrier 1 while passing between the charge accelerating particles Z and the image carrier 1 where the charging process is being performed, so that it is possible to have an appropriate charge. Therefore, when passing through the developing section D in which the developing process is performed,
Will be collected. Therefore, it is possible to realize an electrophotographic process without a cleaner.

[0043]

However, in the case of the injection charging device 2 of the sponge roller type described above, the charging promoting particles Z serving as the injection site are contained in the developer T of the developing device 4. In addition, the supply amount of the charge promoting particles Z to the charging sponge roller 2A depends on the supply amount of the developer T from the developing device 4 to the image carrier 1.

Accordingly, when an image with a low printing rate continues for a long time, the amount of the charge accelerating particles Z supplied from the developing device 4 onto the image carrier 1 and carried to the charging section N also decreases.
There is a problem that charging failure occurs.

Since the charge accelerating particles Z have a charge polarity opposite to that of the developer T, they are not always supplied onto the image carrier 1 at the same ratio with respect to the amount of the developer. Developing device 4
The supply amount of the charge-promoting particles Z to the image carrier 1 varies depending on the form of the developing system, the charge amount of the developer itself, the print pattern, and the like.
In a system in which the charge accelerating particles Z are likely to be excessively supplied to the image carrier 1 with respect to the developer T, as the use of the developer T proceeds, the charge accelerating particles T with respect to the developer T in the developing container are increased.
, The charging ratio tends to be low, and consequently the supply of the charge accelerating particles Z to the image carrier 1 tends to be insufficient at the initial stage. However, there is a problem that it is difficult to obtain a system for supplying the charge accelerating particles Z to the image carrier 1 at a similar ratio.

In order to solve this problem, the ratio of the total charge accelerating particles to the developer T in the developing device 4 is adjusted so that sufficient charging can be performed even when the amount of the charge accelerating particles Z with respect to the developer T is reduced. When the height is increased, there is a problem that a problem occurs in the developability of the developer T.

In the present system, the image carrier 1
Image carrier 1 after transfer of upper toner image to transfer material P
There is no cleaning step provided with the dedicated cleaner of the above. This is because the untransferred toner at this time is usually charged with the charge accelerating particles Z of the charging section N and the image carrier 1 during the charging step.
Since the charge injection is carried out in the same manner as in the image carrier 1 during the passage between the developing unit D and the developing unit D, it is possible to have an appropriate charge. The toner is collected by the developing device 4 without performing the above operation. Therefore, it is possible to realize an electrophotographic process without a cleaner.

However, when a toner image having a high printing rate, which is not transferred to the transfer material P, remains on the image carrier 1 during a jam or the like, a large amount of toner is carried to the charging section N and the charging sponge roller is charged. Attached to 2A,
Inhibits charging. In the normal process, the toner adhering to the charging sponge roller 2A is also charged during the charging process and returns to the image carrier 1. However, when the amount is large, However, there is a problem that it takes time to restore the charging ability.

Further, in order to realize the above cleaner-less system, a transfer system having a certain high level (a transfer system having a high transfer efficiency) must be used. , For example, a spherical developer is desirable, and the developer is limited in many points.

In order to solve these problems, FIG.
As shown in FIG. 6, it is conceivable to provide a means 2B for directly supplying the charge promoting particles Z to the charging sponge roller 2A separately from the charge promoting particles Z in the developer T of the developing device 4. As with the charging device 2Y (FIG. 22), there are problems such as how to hold the charge promoting particles Z and how to supply a stable amount of the charge promoting particles to the sponge roller 2A. In order to solve the problem, there has been a problem that the device becomes considerably large.

The charging sponge roller 2A is an elastic body having a low hardness, and is generally easily deformed when pressure is applied to a specific portion for a long time. For this reason, when the image carrier 1 is left for a long time in a pressurized state, the contact portion with the image carrier is deformed, and there is a problem that poor charging easily occurs in this portion. In order to solve this problem, when the contact pressure of the charging sponge roller 2A with respect to the image carrier 1 is reduced, the contact area with the image carrier 1 is reduced, and the charging capability is reduced.

It is also conceivable to release the contact with the image carrier 1 after the charging step. However, if the pressure release mechanism is provided, the cost increases.

Accordingly, the present invention has been made to cope with such a current situation, and a voltage is applied to form an image carrier and a nip portion as in a sponge roller type injection charging device. It has a flexible charging member for charging the carrier, and in the nip portion, the image carrier is charged by injection of electric charge with charge-promoting particles for promoting charging of the image carrier by the charging member interposed therebetween. In the image forming apparatus using the charging unit, the supply of the charge-promoting particles to the charging member can be efficiently performed by providing a manual supply from the developing unit side or through an intervening member without passing through the image carrier. An object of the present invention is to stably perform the charging process, maintain a stable charging process for a long period of time, suppress occurrence of charging failure, and always obtain a good image.

[0054]

SUMMARY OF THE INVENTION The present invention is an image forming apparatus having the following configuration.

(1) Image carrier, charging means for charging the image carrier, image information writing means for forming an electrostatic latent image on the charged surface of the image carrier, and developing the electrostatic latent image Developing means for visualizing with an agent, wherein the charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier and charges the image carrier, and at least the nip portion In the developing means, the charge accelerating particles for accelerating the charging of the image carrier by the charging member are interposed, and the developing means has the charge accelerating particles mixed in the developer. A developing member for developing an electrostatic latent image on the image carrier, at least one of the charging member and the developing member is movable, and in a process other than image formation, the charging member and the developing member At least one of the moves Ri charging member and brought into contact with the developing member, an image forming apparatus in which the developer and a charging accelerating particles, characterized in that as a moveable between them.

(2) Image carrier, charging means for charging the image carrier, image information writing means for forming an electrostatic latent image on the charged surface of the image carrier, and developing the electrostatic latent image Developing means for visualizing with an agent, wherein the charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier and charges the image carrier, and at least the nip portion In the developing means, the charge accelerating particles for accelerating the charging of the image carrier by the charging member are interposed, and the developing means has the charge accelerating particles mixed in the developer. A developing member for developing an electrostatic latent image on the image carrier, at least one of the charging member and the developing member is movable, and in a process other than image formation, the charging member and the developing member At least one of the moves An image forming apparatus, wherein the charging member and the developing member are brought close to each other, and the developer and the charge accelerating particles are movable between them by an electric field formed therebetween. .

(3) In the image forming apparatus described in (1) or (2), the charging member can be detached from the image carrier when the charging member moves to the developing member. Image forming apparatus.

(4) Image carrier, charging means for charging the image carrier, image information writing means for forming an electrostatic latent image on the charged surface of the image carrier, and developing the electrostatic latent image Developing means for visualizing with an agent, wherein the charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier and charges the image carrier, and at least the nip portion In the developing means, the charge accelerating particles for accelerating the charging of the image carrier by the charging member are interposed, and the developing means has the charge accelerating particles mixed in the developer. Having a developing member for developing an electrostatic latent image on the image carrier, wherein the charging member and the developing member are in contact with each other, and the developer and the charge-promoting particles are movable between them. An image forming apparatus comprising:

(5) Image carrier, charging means for charging the image carrier, image information writing means for forming an electrostatic latent image on the charged surface of the image carrier, and developing the electrostatic latent image Developing means for visualizing with an agent, wherein the charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier and charges the image carrier, and at least the nip portion In the developing means, the charge accelerating particles for accelerating the charging of the image carrier by the charging member are interposed, and the developing means has the charge accelerating particles mixed in the developer. A developing member for developing an electrostatic latent image on the image carrier, wherein the charging member and the developing member are close to each other, and the developer and the charge promotion particles form an electric field formed between them. Characterized by being movable between these by Forming apparatus.

(6) Image carrier, charging means for charging the image carrier, image information writing means for forming an electrostatic latent image on the charged surface of the image carrier, and developing the electrostatic latent image Developing means for visualizing with an agent, wherein the charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier and charges the image carrier, and at least the nip portion In the developing means, the charge accelerating particles for accelerating the charging of the image carrier by the charging member are interposed, and the developing means has the charge accelerating particles mixed in the developer. A developing member for developing an electrostatic latent image on the image carrier, and a rotatable member that is in contact with or in proximity to both of the charging member and the developing member is provided between the charging member and the developing member. The member is an electric potential of the charging member and the developing member. On the other hand, it is possible to take an intermediate potential, and between the charging member and the rotatable member and between the developing member and the rotatable member, by an electric field formed by a potential difference between the potentials, An image forming apparatus, wherein the developer and the charge accelerating particles are movable between them.

<Operation> Either a contact charging member for charging by contacting the image bearing member or a developing member for developing can be moved so that they can be in contact with or close to each other. By contacting or approaching the contact charging member and the developing member, or by providing an intermediate member that is in contact with or approaching both the contact charging member and the developing member, charging promotion to adhere to the contact charging member and assist charging. By supplying the particles directly to the contact charging member from above the developing member, and simultaneously collecting the developer adhered to the contact charging member to the developing member, the supply of the charge promoting particles to the contact charging member can be reduced. Since the toner can be supplied directly from the developing member without relying only on the route via the image bearing member, there is a problem with the amount of use of the image forming apparatus, such as a shortage of the charge accelerating particles and This makes it possible to suppress the occurrence of charging failure due to the adhesion of the developer.

Further, since the above-described steps are performed at times other than the time of image formation, good images can be obtained without adversely affecting the developing step when the charge accelerating particles Z and the developer T are transferred. Is now possible.

In the case where the same pattern is repeatedly developed, the charge accelerating particles and the developer may be unevenly adhered to each other at a specific position on the contact charging member, resulting in poor charging. Since the supply of the charge accelerating particles of the contact charging member is not affected by the development pattern, such a problem does not occur.

Even when a large amount of developer adheres to the contact charging member via the image carrier due to a paper discharge failure or the like generated during the image forming process, the exchange of the developer and the charge promoting particles is performed. Can be directly performed with the developing member, the recovery to the original state is quick, the occurrence of poor charging hardly occurs, and the recovery is quick.

In addition, since the supply of the charge accelerating particles Z does not need to rely on the route from the image carrier, it is possible to provide a cleaning process of the image carrier after the transfer process. Since the system need not be required, the degree of freedom in system design has increased.

In the case where the contact charging member is not brought into contact with the developing member but is brought close to the developing member by an electric field so as to allow the charge promoting particles to fly, the developer and the charge promoting member are applied only to the AC electric field. Since the particles are exchanged, in addition to the effects described above, these exchanges can be performed very selectively.

Further, the step of moving the contact charging member is also used as a mechanism for releasing contact from the image carrier for preventing pressure deformation of the contact charging member. The problem and the problem of the occurrence of the charging failure due to the deformation of the contact charging member can be simultaneously solved by one apparatus, and the cost can be reduced.

When the contact-propelling member is not brought into contact with the developing member but is brought close to the developing member by a distance such that the charge-promoting particles can fly by the electric field, the developer thin layer on the developing member is disturbed. Since the number of factors was reduced, adverse effects on the developing process were less likely to occur. Alternatively, by displacing the contact position between the contact charging member and the developing member downstream of the developing position with the image carrier in the rotation direction of the developing member, the factor of disturbing the developer thin layer on the developing member is reduced. Adverse effects on the development process were less likely to occur.

Also, an intermediate member is provided between the contact charging member and the developing member, and the intermediate member is brought into contact with or close to the respective contact charging member and the developing member, and the potential of the intermediate member is controlled, whereby Contact charging member
The transfer of the developer and the charge-promoting particles between the intermediate member and the developing member can be efficiently controlled at a timing that does not affect the developing process.

Further, by providing the intermediate member, a space is created between the charging device and the developing device, so that the exposing device can be installed outside the image carrier.

[0071]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment (FIGS. 1 to 7) FIG. 1 is a schematic structural model diagram of an image forming apparatus of the present embodiment. This image forming apparatus is a laser beam printer of a transfer electrophotographic process, a sponge roller type injection charging system, a cleanerless system, and a reversal developing system.

The description of the components and parts common to those of the laser beam printer shown in FIG.

(1) Sponge roller charging device 2 Charging sponge roller 2A as a contact charging member of sponge roller charging device 2 has a hardness of 30 degrees and an average foam diameter of 50 μm.
m, and the outer peripheral surface of the conductive roller has a charge accelerating particle Z.
, And the roller contacts the image carrier 1 to form a charging portion N.

Then, in the charging section N, the image carrier 1 is driven to rotate in a clockwise direction indicated by an arrow b, which is a direction opposite to the rotation direction of the image carrier 1, and moves with a speed difference with respect to the image carrier. The surface speed is the same as that of the image carrier 1, that is, at a relative speed with respect to the image carrier 1, the moving speed is 200% of the surface speed of the image carrier.

A predetermined charging bias is applied from the power supply S1 to the charging sponge roller 2A, and the surface of the image carrier is injected and charged.

As the charge accelerating particles Z, conductive zinc oxide particles having an average particle diameter including the secondary aggregate of 3 μm and a specific resistance of 10 ⁶ Ω · cm are used. The charge accelerating particles Z have a polarity opposite to that of the negative polarity of the developer (magnetic toner) T.

The charge accelerating particles Z mainly adhere to the sponge vacant portion on the surface of the charging sponge roller and cover the surface of the charging sponge roller 2A.

A voltage of -620 V is applied to the image carrier 1 from the power supply S1 to the charging sponge roller 2A. For this reason, in the charging portion N where the image carrier 1 and the charging sponge roller 2A are in contact with each other, the charge accelerating particles Z, which are a low-resistance substance, are likely to have the same potential in a portion where they are in direct contact with them. An electric charge is induced on the surface of the carrier 1 and tends to reach −620 V, which is the same potential as the charging sponge roller 2A side.

Thereafter, when the charging sponge roller 2A and the surface of the image carrier 1 are separated from each other, the movement of the electric charge again occurs, and the electric charge on the image carrier 1 tends to decrease. It is determined by the resistance value of the charge accelerating particles Z, the resistance value of the image carrier 1 and the layer structure thereof. In the present embodiment, a system that minimizes the reduction amount is reduced by 20 V, −600
V surface potential is obtained.

After this charging step, a laser beam scanning exposure L corresponding to image information is performed by a laser scanner 3 as an exposure device, and a portion of the charged surface of the image carrier 1 irradiated with laser light is the same as a general electrophotographic process. Then, the potential is lowered, and a potential difference is created between the exposed portion and the unexposed portion, thereby forming a latent image.

In the present embodiment, the so-called bright portion potential V1 of the exposed portion is V1 = -150V, while the so-called dark portion potential Vd = -600V which is not exposed.

(2) Developing Apparatus 4 The electrostatic latent image formed on the image carrier 1 as described above is converted into a toner image by the developing apparatus 4 using a so-called jumping developing method that does not contact the image carrier 1. Developed.

The developing device 4 includes a developing sleeve 4a (developing member, developing roller) that includes a fixed developing magnet 4b and is rotatable in a counterclockwise direction indicated by an arrow c, and a developing contact with the developing sleeve 4a. It is formed by a blade 4c and a developing container 4d that stores a developer (magnetic toner) T.

The developer container 4d contains a developer T in which the charge accelerating particles Z are mixed in a weight ratio of 3 parts. When strong electric power does not work, the charge accelerating particles Z mixed with the developer T move in a state where most of them adhere to the developer T.

The surface of the developing sleeve 4a is roughened. The developer T, which is a magnetic toner, is held on the surface of the developing sleeve 4a in accordance with the magnetic force of the developing magnet 4b contained therein, and is conveyed by rotating the arrow c in the counterclockwise direction. The transported developer T is restricted in height on the developing sleeve 4a when passing through the contact surface with the developing blade 4c, and is charged by friction to receive charge. In this embodiment, most of the chargeability of the developer T at this time is negative due to the charge polarity of the material. At the same time, the charge promotion particles Z passing through this region are positively charged.

The thin layer T of the developer T containing the charge accelerating particles Z formed on the surface of the developing sleeve 4a as described above.
a is the rotation of the developing sleeve 4a, and the image carrier 1
Is transported to a developing section D, which is an approaching and opposing portion between the developing sleeve 4a and the developing sleeve 4a, and is subjected to development of the electrostatic latent image on the image carrier 1 side in the presence of a developing bias. Is reversely developed as a toner image. The image carrier 1 and the developing sleeve 4a are closely opposed to each other in a non-contact manner with a gap of 300 μm. Developing sleeve 4a that has passed developing section D
The remaining thin developer layer Tb on the upper side is the developing sleeve 4a
Is returned to the developer reservoir in the developing container 4d and conveyed again.

Here, in the developing section D, the behavior of the charged developer T and the charge accelerating particles Z of the developer thin layer Ta on the developing sleeve 4a behaves between the developing sleeve 4a and the image carrier 1. This is shown in FIG.

That is, when the negatively charged developer T reaches the area approaching the image carrier 1, the developer T is charged by the electric field formed between the image carrier 1 and the developing sleeve 4a. Develop the latent image. In this embodiment,
The image carrier 1 is provided on the surface of the developing sleeve 4a by the power source S2.
To a DC voltage of -400V and a frequency of 1500H
A voltage obtained by superimposing a rectangular wave AC voltage of z · 1600 Vpp is applied, and in the gap of 300 μm formed between the image carrier 1 and the developing sleeve 4a, the negatively charged developer T is Vd = − Although it does not fly to the dark potential portion of 600V, it does fly to the bright potential portion of V1 = -150V.

At this time, the positively-charged charge-promoting particles Z tend to electrically fly to the dark potential portion, contrary to the developer T. T
When the developer T is much attached to itself and the electrostatic force with the developer T is stronger, the developer T moves in the same manner as the developer T without exhibiting the opposite behavior to the developer T.

Therefore, the charge accelerating particles Z are
It is possible to fly from the a side to the bright portion potential portion and the dark portion potential portion on the image carrier 1 side.

(3) Transfer The toner image formed on the image carrier 1 in the above-described developing step is transferred to a transfer material (transfer sheet) P in a transfer section M. A DC voltage of 2 KV is applied to the image carrier 1 by a power source S3 to the rotary transfer roller 5 serving as a transfer unit, and an electric field formed between the image carrier 1 and the transfer roller 5 is reduced. Since the negatively charged toner image is attracted to the transfer roller 5 side, most of the toner of the toner image is transferred to the transfer material P.

(4) Simultaneous Development Cleaning (Cleanerless System) On the other hand, the positively charged charge accelerating particles Z supplied to the surface of the image carrier 1 from the developing sleeve 4a side in the developing section D are removed from the surface of the image carrier 1 In the light potential portion, most of the toner adhering to the toner is transferred to the transfer material P together with the toner. However, since the toner is electrically stable on the image carrier 1, a larger amount of toner is used than the toner. The amount remains on the image carrier 1. In addition, most of the charge-promoting particles Z attached to the dark potential portion on the surface of the image carrier 1 remain on the image carrier 1 as it is.

Therefore, on the image carrier 1 after the transfer step, the transfer residual toner slightly remaining in the transfer step at the light potential portion and the charge accelerating particles Z remaining on the entire surface of the image carrier 1 in a relatively large amount.
Will exist.

The transfer residual toner and the charge accelerating particles Z on the image carrier 1 are transferred to the charging portion N by the subsequent rotation of the image carrier.
And is passed over the charging sponge roller 2A. Since a voltage of −620 V is applied to the image carrier 1 to the charging sponge roller 2A, the positively charged charging promoting particles are Z tends to move to the charging sponge roller 2A from the surface of the image carrier 1 that is charged to the positive side from the charging sponge roller 2A in the transfer process. And, by being held on the fine surface of the sponge of the charging sponge roller, it performs the function of the charging step as described above.

That is, the charging promoting particles Z are supplied from the developing device 4 to the charging sponge roller 2A, which is a contact charging member of the sponge roller charging device 2, via the image carrier 1.

On the other hand, the transfer residual toner carried to the charging section N is a so-called inversion component which is originally positively charged and is difficult to be transferred, or is positively charged since it has been subjected to the transfer voltage. Things are dominant. Therefore, these toners also adhere to the charging sponge roller 2A, and while the toner adheres to the area where the image carrier 1 and the charging sponge roller 2A perform the charging step, that is, the charging section N several times, the negative charge is applied. Since the grant is made,
Originally, the toner which is easily charged negatively becomes negatively charged relatively quickly, and returns to the image carrier 1 again.
Since the toner is assimilated with toner newly developed when passing through the area adjacent to the developing sleeve 4a in which the developing process is performed, that is, the developing unit D (simultaneous development cleaning), the present electrophotographic process is established.

(5) Direct supply of charge-promoting particles from the developing sleeve 4a to the charging sponge roller 2A The problem with this system is that the charging-promoting particles Z to the charging sponge roller 2A are problematic, as described above. Regarding the supply method, in the present embodiment, in the initial stage, the charge accelerating particles Z are attached to the charge sponge roller 2A from the beginning to have the charging ability.

On the other hand, when the use of the image forming apparatus is advanced, as described above, in the simultaneous supply of the developer T to the image carrier 1 in the developing step, the method of use and the image pattern to be used are Charge accelerating particles Z
Supply tends to be unstable. Further, when the image forming apparatus is stopped due to a trouble such as paper feeding, a large amount of the developer T remains on the image carrier 1 and reaches the charging sponge roller 2A, so that the charging ability is reduced.

In the present embodiment, as a measure against these problems, the supply of the charge accelerating particles Z to the charging sponge roller 2 is not limited to the indirect supply via the image carrier 1, but also the charging from the developing sleeve 4 a side. Sponge roller 2A
It is made possible to directly.

That is, in the present embodiment, the charging sponge roller 2A, which is a contact charging member, is rotatably supported by a support member 9 rotatable about the central axis O of the image carrier 1. It is. The support member 9 is controlled to swing clockwise or counterclockwise by a drive mechanism (not shown) controlled by a control circuit (not shown). The charging sponge roller 2A is rotationally controlled at a predetermined peripheral speed in a clockwise direction indicated by an arrow b by a drive mechanism (not shown) controlled by a control circuit (not shown). A predetermined voltage is applied to the intermediate roller 9 from a power supply S1.

The control circuit controls the driving mechanism of the support member 9 in a predetermined sequence, and swings the support member 9 in the counterclockwise direction to cause the charging sponge roller 2A to be developed by the developing device 4. The first, which is separated from the sleeve 4a by a predetermined distance,
Position R1 (the position indicated by the solid line in FIG. 1, the position indicated by the two-dot chain line in FIG. 3)
And the supporting member 9 is swung clockwise to move the charging sponge roller 2A through the developer thin layer Ta.
a in contact with the second position R2 (the position indicated by the two-dot chain line in FIG. 1;
(The position indicated by the solid line in FIG. 3). When the charging sponge roller 2A is in the second position R2 in which the charging sponge roller 2A is in contact with the developing sleeve 4a via the developer thin layer Ta, the developer T and the charging promoting particles Z are charged by the charging sponge roller due to the potential relationship between the charging sponge roller 2A and the developing sleeve 4a. It can move between 2A and the developing sleeve 4a.

At the first position R1 of the charging sponge roller 2A, there is a space between the developing roller 4a and the developing sleeve 4a where the exposure L from the laser scanner 3 to the image carrier 1 is possible. No position. At the second position R2 of the charging sponge roller 2A, the exposure L is blocked by the charging sponge roller 2A.

FIG. 4 shows a sequence relating to the switching movement of the intermediate roller 9 between the first position R1 and the second position R2. In FIG. 4, “pre-rotation” means that the main motor is turned on to start rotation of the image carrier 1 in response to input of an image formation (print) start signal in the standby state of the image forming apparatus, and the image forming apparatus This is a process period in which a predetermined pre-image forming operation is performed. In the “post-rotation”, the main motor is driven to rotate the image carrier 1 for a while after the image forming process of the last n-th sheet (including the case of forming only one sheet) is completed. During which the image forming apparatus executes a predetermined post-image forming operation. Further, the “sheet interval” means that after the rear end of one transfer material P passes through the transfer portion M in the continuous image forming mode for two or more sheets,
Until the leading end of the next transfer material P reaches the transfer portion M,
This is a non-sheet passing state period of the transfer material P in the transfer unit M.

The charging sponge roller 2A is at the first position R1 during the process of forming a latent image in which the presence of the charging sponge roller 2A hinders the exposure L on the image carrier 1, and the exposure L is emitted. If not, it is at the second position R2.

Here, the formation of the latent image by the exposure L and the development process of developing the latent image with the development sleeve 4a are almost the same, and the time when the development process is completed is the same as the time when the exposure L is not emitted. Think at the same time.

The behavior of the developer T and the charge accelerating particles Z during the development process moves between the developing sleeve 4a and the charging sponge roller 2A via the image carrier 1 as described above. However, when the charging sponge roller 2A moves to the second position R2, the charging sponge roller 2A can directly move between the developing sleeve 4a and the charging sponge roller 2A.

In the ordinary image forming process, the charging step is required for most of the time while the image carrier 1 is rotating unless a special step is provided. Therefore, in this embodiment, the charging sponge roller is used. A voltage of -620 V is always applied to 2A. On the other hand, the voltage applied to the developing sleeve 4a is basically OV since no voltage is applied except when the latent image on the image carrier 1 is developed.

Therefore, when the charging sponge roller 2A is at the second position R2 in contact with the developing sleeve 4a, the charging sponge roller 2A is in contact with the developing sleeve 4a.
The potential of A is -620 V, and among the positively charged charge accelerating particles Z, those excluding those electrostatically strongly adhered to the developer T, those released from the developer T are charged sponge rollers 2A. To fly.

On the other hand, the behavior of the developer T is such that the developing sleeve 4a
Not only does not move onto the charging sponge roller 2A from above, but also what has adhered to the charging sponge roller 2A is directly collected on the developing sleeve 4a without passing through the image carrier 1.

Therefore, in this embodiment, the charging sponge roller 2A is effectively supplied with the charge accelerating particles Z necessary for charging only by applying a voltage necessary for a normal image forming process, Charging sponge roller 2
Since the developer T on A is effectively removed, good charging performance can always be maintained.

By carrying out the present embodiment, the charge accelerating particles Z can be directly supplied to the charging sponge roller 2A to remove the developer T, and the developed image pattern, Since the transfer of the developer T on the image carrier 1 is less susceptible to the influence of the developer T, stable charging can be obtained over a long period of time, and the occurrence of image defects can be suppressed.

Although the electrophotographic process in this embodiment does not have a cleaning mechanism on the image carrier 1 after transfer, this is inevitable in the conventional example, and a high transfer efficiency is required to realize this. System was needed.

However, according to the present invention, even when the above-described cleaning mechanism is provided, the supply of the charging promoting particles Z to the charging sponge roller 2A is possible.

Accordingly, a blade cleaning device 7a as shown in FIG. 5 or a roller cleaning device 7b as shown in FIG. 6 for spreading the residual developer by rotation of a brush roller may be provided. Since the condition of the transfer efficiency is relaxed as compared with the above, the degree of freedom as a system is increased.

Although the present embodiment is a non-contact developing system using a magnetic toner as the developer T, the developer T is not limited to the magnetic toner, and the developing system is also widely used. It can also be applied to existing contact development systems.

Further, the sequence of movement of the charging sponge roller 2A in the present embodiment is a simple one separated only during the latent image process (= developing process) and other times. When contacting the sleeve 4a, avoid the problem that the image carrier 1 cannot be exposed, or the charging sponge roller 2A in contact with the sleeve 4a disturbs the developer coating layer Ta on the developing sleeve 4a and causes deterioration of an image in development. Therefore, for example, when the image carrier 1 is neutralized by the exposure L, such as during post-rotation, the charging sponge roller 2A is moved to the first position away from the developing sleeve 4a even when the developing process is not performed. R1
It may be.

In the above case, as shown in FIG. 7, the movable range of the charging sponge roller 2A is made sufficiently large so that the charging sponge roller 2A and the developing sleeve 4a are kept in contact during post-rotation. After the charging step, the image carrier 1 can be neutralized by the exposure L.

Further, in this embodiment, the charging sponge roller 2A as the charging member moves and comes into contact with the developing sleeve 4a as the developing member. However, the charging sponge roller 2A does not move and the developing device does not move. An apparatus configuration may be used in which the developing sleeve 4a moves and the developing sleeve 4a contacts the charging sponge roller 2A.

<Second Embodiment> (FIG. 8) FIG. 8 is a schematic diagram of a main part of an image forming apparatus according to a second embodiment.

In this embodiment, the second position R2 of the charging sponge roller 2A in the image forming apparatus of the first embodiment is used.
Are positioned so as not to be in contact with the developing sleeve 4a but to be in close contact with the developing sleeve 4a in a non-contact manner with a small gap α. In this embodiment, when the charging sponge roller 4a is at the second position R2 in which the charging sponge roller 4a is in non-contact and close proximity to the developing sleeve 4a, the proximity facing distance α is 200 μm.

In this embodiment, even when the charging sponge roller 2A moves to the second position R2, the developing sleeve 4
The charging sponge roller 2A and the developing sleeve 4a are rotating in the directions of arrows b and c, respectively, while always opposing each other without contacting the same. The conditions such as the voltage applied to each member and the rotation speed of each member are the same as in the first embodiment.

Except for the vicinity of the charging sponge roller 2A and the developing sleeve 4a, the design is the same as that of the image forming apparatus of the first embodiment.
It is possible to move on the image carrier 1 between the first position R1 and the second position R2 by the same sequence as that of the embodiment (FIG. 4).

In the present embodiment, during the non-development step in which the charging sponge roller 2A is at the second position R2, the DC voltage of 0 V, 1500 Hz, 16 Hz is applied to the developing sleeve 4a.
An AC voltage of 00 Vpp is applied.

The charging sponge roller 2A and the developing sleeve 4
Since a potential difference of 620 V is provided in a space of 200 μm between the developer T and the developer T and the charge accelerating particles Z in the area near the charging sponge roller 2A and the developing sleeve 4a. Similarly, when the toner is developed on the body 1, the toner moves between the charging sponge roller 2A and the developing sleeve 4a. In the process, the developer T and the charge accelerating particles Z move to a more stable potential, and consequently, the charge accelerating particles Z similarly to the first embodiment.
Moves to the charging sponge roller 2A side, and the developer T moves to the developing sleeve 4a side.

In this embodiment, the charging sponge roller 2
A and the developing sleeve 4a must always be kept at a precise distance to some extent. Therefore, a mechanism for this must be provided as compared with the first embodiment, but the developing sleeve 4a and the charging sponge roller 2A Since the developer T and the charge accelerating particles Z are exchanged only in an AC electric field in a non-contact manner, the exchange can be performed very selectively.

In the present invention, since the charging sponge roller 2A and the developing sleeve 4a are not in contact with each other, even if the resistance of the charging sponge roller 2A and the developing sleeve 4a is low, a large electric field can be obtained by forming an appropriate gap. Is not formed, so that there is no need to worry about generation of a leak current here.

In this embodiment, an AC electric field is applied between the charging sponge roller 2A and the developing sleeve 4a. However, the transfer of the developer T and the charge accelerating particles Z is smoothly performed only by the DC electric field. If so, the AC electric field may be eliminated.

In the image forming apparatus of this embodiment, the first
As in the embodiment of FIG. 5, the cleaning devices 7a and 7b (FIG. 5)
・ Fig. 6) may be provided.

Further, as in the first embodiment, the developer T is not limited to the magnetic toner, and the developing system can be adapted to a contact developing system which is generally widely used.

Also in this embodiment, as compared with the conventional example, the charge accelerating particles Z can be directly supplied to the charging sponge roller 2A, the developer T can be removed, and the developed image pattern and image carrier 1 can be removed. Since it is less susceptible to the transfer residual developer T, stable charging can be obtained over a long period of time. Further, since there is little influence on the developing device 4, a good image can always be obtained. Was.

Also in this embodiment, the charging sponge roller 2A as a charging member moves and comes close to the developing sleeve 4a as a developing member. However, the charging sponge roller 2A does not move and the developing device 4, the developing sleeve 4a may move closer to the charging sponge roller 2A.

Third Embodiment (FIG. 9) FIG. 9 is a schematic diagram of a main part of an image forming apparatus according to a third embodiment.

In this embodiment, the charging sponge roller 2A in the image forming apparatus of the first embodiment is supported by a guide member 10 disposed in the left-right direction.
The position can be moved in the left-right direction along 0.

The charging sponge roller 2A is
9, the charging sponge roller 2A is brought into contact with the image carrier 1 by being pressed against the image carrier 1 in a predetermined manner as shown by a two-dot chain line in FIG. Will be retained. The position of the charging sponge roller 2A is the first position R1. In the first position, the charging sponge roller 2A is separated from the developing sleeve 4a of the developing device 4 in a non-contact manner, and the exposure L to the surface of the image carrier 1 passes through the space between the charging sponge roller 2A and the developing sleeve 4a. It is possible.

The charging sponge roller 2A is moved rightward along the guide member 10 and is held at a predetermined right end point position, so that the charging sponge roller 2A is moved to the developing device 4 as shown by the solid line in FIG. Is kept in contact with the developing sleeve 4a. The position of the charging sponge roller 2A is the second position R2. At this second position, the charging sponge roller 2A is separated from the image carrier 1 in a non-contact manner. That is, the contact of the sponge roller 2A with the image carrier 1 is released.

The second position R of the charging sponge roller 2A
The position 2 may be a position where the charging sponge roller 2A does not come into contact with the developing roller 4a and is closely opposed to the developing roller 4a with a small gap α as shown in FIG.

The image forming apparatus of this embodiment has the same design as that of the first embodiment except for the movement of the charging sponge roller 2A. The charging sponge roller 2A is of the first embodiment. In the same sequence as described above, switching to the first position R1 and the second position R2 is controlled by a control unit and a driving unit (not shown).

Since the charging sponge roller 2A is a very low elastic body, it is likely to be deformed when pressure is applied to the same place for a long time. Image carrier 1
A pressure release mechanism is required to make the contact nip wide with the pressure release mechanism.

In this embodiment, the above-mentioned pressure release mechanism and the first
This also serves as the mechanism described in the first embodiment, thereby making it possible to reduce costs.

In this embodiment, when the charging sponge roller 2A is moved to the second position R2, the charging sponge roller 2A is brought into contact with the developing sleeve 4a.
If the transfer of the developer T and the charge accelerating particles Z is smoothly performed between the charging sponge roller 2A and the developing sleeve 4a, the second position R2 of the charging sponge roller 2A is set to the charging sponge roller as in the second embodiment. There is no problem if the 2A is brought into close proximity with a small gap α (FIG. 8) without making contact with the developing roller 4a.

Also in this embodiment, as compared with the conventional example, the charge accelerating particles Z can be directly supplied to the charging sponge roller 2A to remove the developer T, and the developed image pattern and image carrier can be removed. 1 is less susceptible to the transfer residual developer T, so that a stable charge can be obtained for a long period of time, and the effect on the developing device 4 is small, so that a good image can always be obtained. Was.

Further, even if the above process is performed during post-rotation and the image forming apparatus is left as it is, the pressure on the charging sleeve 4a of the charging sponge roller 2A is sufficiently low.
It is possible to suppress the occurrence of poor charging due to the trace of the charging sponge roller 2A being left.

Further, similarly to the first embodiment, the developer T is not limited to the magnetic toner, and the developing system can be applied to a contact developing system which is generally widely used.

In the first to third embodiments described above, the charge-promoting particles Z mixed with the developer T are applied to the conductive charging sponge roller 2A which comes into contact with the image carrier 1 while rotating.
Is applied to the charging sponge roller 2A, the charging sponge roller 2A is charged to substantially the same potential.
A is brought into contact with a developing sleeve (or developing roller) 4a that transports the developer T to the developing position D of the image carrier 1, that is, a conductive sleeve that contacts and charges the image carrier 1. Either the charging sponge roller 2A or the developing sleeve 4a for performing development can be moved so that they can come into contact with or approach to each other. At this time, the charging sponge roller adheres to the charging sponge roller to assist charging. By supplying the accelerating particles directly from the developing sleeve to the charging sponge roller 2A, and simultaneously collecting the toner adhering on the charging sponge roller to the developing sleeve, the supply of the charging accelerating particles Z to the charging sponge roller 2A is achieved. Since the toner can be supplied directly from the developing sleeve 4a without relying only on the conventional route via the image carrier 1, the amount of use of the image forming apparatus is reduced. Becomes a problem, shortage or the charging performance enhancement particle amount, due to the adhesion of developer onto the charging sponge roller 2A, it has become possible to suppress the occurrence of charging failure.

Further, since the above-described steps are performed at times other than the time of image formation, good images can be obtained without adversely affecting the developing step when the charge accelerating particles Z and the developer T are transferred. Is now possible.

Further, when the same pattern is repeatedly developed, the charge accelerating particles Z and the developer T may be unevenly adhered at a specific position on the charging sponge roller 2A, resulting in poor charging. Since the supply of the charge accelerating particles Z of the charge sponge roller 2A from the developing sleeve 4a is not affected by the development pattern, such a problem does not occur.

Further, even when a large amount of the developer T adheres to the charging sponge roller 2A via the image carrier 1 due to a paper discharge failure or the like generated during the image forming process, the developer T and the charging Since the exchange of the accelerating particles Z can be performed directly with the developing sleeve 4a, the recovery to the original state is quick, the occurrence of charging failure is unlikely to occur, and the recovery is quick.

Further, since the supply of the charge accelerating particles Z does not need to rely on the route from the image carrier 1, a cleaning step of the image carrier 1 can be provided after the transfer step. Since a system that does not require transfer efficiency is no longer required, the degree of freedom in system design is increased.

In the case where the charging sponge roller 2A is not brought into contact with the developing sleeve 4a, but is brought close to the charging accelerating particles Z by an electric field so that the particles can fly, the developer is applied only to the AC electric field. Since the transfer of the T and the charge accelerating particles Z is performed, in addition to the above-described effects, the transfer can be performed very selectively.

The step of moving the charging sponge roller 2A is also used as a mechanism for releasing the contact from the image carrier 1 to prevent pressure deformation of the charging sponge roller 2A. The problem of the occurrence of the defect and the problem of the occurrence of the charging defect due to the deformation of the charging sponge roller 2A can be simultaneously solved by one apparatus, and the cost can be reduced.

<Fourth Embodiment> (FIGS. 10 to 13) FIG. 10 is a schematic structural diagram of an image forming apparatus according to this embodiment. Constituent members and portions common to those of the image forming apparatus of the first embodiment described above are denoted by common reference numerals, and description thereof will not be repeated.

In the image forming apparatus of this embodiment, the image carrier 1 is an electrophotographic photosensitive member of the inner side exposure type, and a photosensitive drum layer is formed on the outer peripheral surface of a transparent drum base. An exposure device 3, such as an LED array, is disposed inside 1.

The charging sponge roller 2A of the charging device 2 is brought into contact with the image carrier 1 to form a charging portion N,
The developing device 4 is always in contact with the developing sleeve 4a.

The conditions such as the rotation direction, rotation speed, and applied voltage of the image carrier 1, the charging sponge roller 2A, the developing sleeve 4a, etc. are the same as those of the image forming apparatus of the first embodiment.

Image exposure by the exposure device 3 is performed from the inner side of the image carrier 1 at a position between the charging section N and the developing section D.

That is, after the charging step of the rotating image carrier 1 by the charging sponge roller 2A, the image carrier 1
The light L emitted by the exposure device 7 provided inside the image carrier 1 passes through the transparent drum substrate inside the image carrier 1, and reaches the photosensitive layer on the outer peripheral surface of the drum substrate. Then, as in a general electrophotographic process, the potential of the photoreceptor portion exposed to light becomes low, and a potential difference is created between the exposed portion and the non-exposed portion to form a latent image. In this embodiment, the so-called bright portion potential V1 of the exposed portion is V1 = -150 with respect to the unexposed so-called dark portion potential Vd = -600V.
V.

The developing device 4 is the same as that of the first embodiment.
This is an apparatus using a so-called jumping development method that does not come into contact with the image carrier 1, and a charge-promoting particle Z is mixed in a developer (magnetic toner) T.

The behavior of the charged developer T and the charge accelerating particles Z in the developing section D is the same as that of FIG. 2, and the simultaneous cleaning of the transfer residual developer and the transfer from the developing sleeve 4a to the charged sponge roller 2A are performed. Image carrier 1 of charge accelerating particles Z
Is supplied in the same manner as in the first embodiment.

In this embodiment, the charging sponge roller 2A
Is in constant contact with the developing sleeve 4a via the thin developer layer Ta. Therefore, the charging sponge roller 2A
The developer T and the charge accelerating particles Z can move through these 2A and 4a depending on the relationship between the potential and the potential of the developing sleeve 4a. That is, the supply of the charge promoting particles Z from the developing sleeve 4a to the charging sponge roller 2A can be performed not only indirectly through the image carrier 1 but also directly from the developing sleeve 4a to the charging sponge roller 2A. it can.

Here, in the image forming (electrophotographic) process, the charging sponge roller 2A and the developing sleeve 4a are used.
FIG. 11 shows the sequence of the applied voltages.

That is, in the normal electrophotographic forming process, the charging step is almost required during the rotation of the image carrier 1 unless a special step is provided. A voltage of -620 V is always applied to the charging sponge roller 2A. On the other hand, the voltage applied to the developing sleeve 4a is obtained by applying an AC voltage to a DC voltage of -400 V as described above. However, this voltage is applied only when a latent image on the image carrier 1 is developed. Things. At other times, basically no voltage is applied and the voltage is 0V.

Accordingly, at the time of image formation, the potential of the charging sponge roller 2A is-with respect to the developing sleeve 4a.
220 V, positively charged charge accelerating particles Z
Of those, those that electrostatically strongly adhered to the developer T were removed,
Those released from the developer T fly to the charging sponge roller 2A. During non-image formation, the potential of the charging sponge roller 2A is -6 with respect to the developing sleeve 4a.
At 20 V, the charge accelerating particles Z easily fly to the charge sponge roller 2A more than during image formation.

On the other hand, the behavior of the developer T is such that the developing sleeve 4a
Not only does it not move onto the charging sponge roller 2A from above, but on the contrary, even the one that has adhered to the charging sponge roller 2A is directly collected on the developing sleeve 4a without passing through the image carrier 1.

Therefore, in the present embodiment, the charging sponge roller 2A is effectively supplied with the charge accelerating particles Z necessary for charging only by applying a voltage necessary for a normal image forming process, Since the developer T on the charging sponge roller 2A, which is an obstacle, is effectively removed, good charging performance can always be maintained.

By carrying out this embodiment, the charging sponge roller 2A can be removed from the developing sleeve 4a as compared with the conventional example.
The developer T can be removed by directly supplying the charge accelerating particles Z to the toner, and the developer T is less susceptible to the developed image pattern and the developer T remaining after transfer on the image carrier 1. As a result, stable charging was obtained, and the occurrence of image defects could be suppressed.

Although the electrophotographic process in this embodiment does not have a cleaning mechanism on the image carrier 1 after transfer, this is inevitable in the conventional example, and in order to realize this, high transfer is required. An efficient system was needed.

However, in the present invention, even when the above-described cleaning mechanism is provided, the supply of the charge accelerating particles Z to the charge sponge roller 2A is possible.

Therefore, a blade cleaning device 7a as shown in FIG. 12 or a roller cleaning device 7b as shown in FIG. 13 for spreading the transfer residual developer by rotation of a brush roller may be provided. Since the condition of the transfer efficiency is relaxed as compared with the above, the degree of freedom as a system is increased.

In this embodiment, a non-contact developing system using a magnetic toner as the developer T is used. However, the developer T is not limited to the magnetic toner.
The present invention can also be applied to a contact developing system generally widely used.

<Fifth Embodiment> (FIG. 14) FIG. 15 is a schematic diagram of a main part of an image forming apparatus according to a fifth embodiment.

In this embodiment, in the image forming apparatus of the fourth embodiment, the charging sponge roller 2A does not come into contact with the developing sleeve 4a, but comes close to the developing sleeve 4a in a non-contact manner with a small gap α. They are arranged facing each other. In this embodiment, the charging sponge roller 4a
The distance α between the head and the developing sleeve 4a is 200 μm. The charging sponge roller 2A and the developing sleeve 4a rotate in the directions of arrows b and c, respectively. The conditions such as the voltage applied to each member and the rotation speed of each member are the same as in the fourth embodiment. Except for the vicinity of the charging sponge roller 2A and the developing sleeve 4a, the fourth
The same design as that of the image forming apparatus of the embodiment is performed.

In this embodiment, a potential difference of 220 V is provided between the charging sponge roller 2 A and the developing sleeve 4 a in a space of 200 μm during development and 620 V except during development. And during this time, 1500H
z, since an AC voltage of 1600 Vpp is also applied,
In the vicinity of the charging sponge roller 2A and the developing sleeve 4a, the developer T and the charge promoting particles Z
Is developed between the charging sponge roller 2A and the developing sleeve 4a. In the process, the developer T and the charge accelerating particles Z move to a more stable potential, and consequently, as in the fourth embodiment, the charge accelerating particles Z are transferred to the charging sponge roller 2A. Side, and the developer T moves to the developing sleeve 4a side.

In this embodiment, since the distance between the charging sponge roller 2A and the developing sleeve 4a must always be maintained at a precise distance to some extent, compared to the fourth embodiment,
A mechanism for this must be provided, but since the developing sleeve 4a and the charging sponge roller 2A are not in contact,
The charging sponge roller 2A hardly disturbs the thin developer layer Ta on the developing sleeve 4a, and the influence on the developing process is very small.

Since the charging sponge roller 2A is not in contact with the developing sleeve 4a, the charging sponge roller 2A
Even if A or the resistance of the developing sleeve 4a is low, since a large electric field is not formed by providing an appropriate gap, there is no fear of occurrence of a leak current or the like here.

In this embodiment, as in the fourth embodiment, the cleaning devices 7a and 7b (see FIGS.
3) may be present.

Further, similarly to the fourth embodiment, the developer T is not limited to the magnetic toner, and the developing system can be applied to a contact developing system which is generally widely used.

Also in this embodiment, as compared with the conventional example, the charge accelerating element Z can be directly supplied to the charging sponge roller 2A, the developer T can be removed, and the developed image pattern and image carrier can be removed. 1 is less susceptible to the transfer residual developer T, so that a stable charge can be obtained for a long period of time, and the effect on the developing device 4 is small, so that a good image can always be obtained. Was.

<Sixth Embodiment> (FIG. 15) FIG. 15 is a schematic diagram showing the construction of an image forming apparatus according to a sixth embodiment. A charging device 2, an exposure device 3 disposed inside the image carrier 1, a developing device 4 using a developer T mixed with the charge promoting particles Z,
It comprises a transfer device 5, a fixing device 6, and the like.

Also in the present embodiment, the charging device 2 is a device in which the surface of a charging sponge roller 2A made of a conductive sponge contains charging promoting particles Z. The carrier 1 is charged.

The supply of the charge accelerating particles Z to the charging sponge roller 2A is performed together with the developer T during image formation via the image carrier 1 in the same manner as in the fourth embodiment. 2A is also brought into direct contact with the developing sleeve 4a.

Here, in the present embodiment, the rotation direction c of the developing sleeve 4a is rotated in the direction opposite to the traveling direction a of the image carrier 1 at the position facing the image carrier 1, Accordingly, the contact surface between the developing sleeve 4a and the charging sponge roller 2A is located on the downstream side of the proximity surface (developing section D) between the developing sleeve 4a and the image carrier 1 with respect to the rotation direction c of the developing sleeve 4a. . As a result, the transfer of the developer T and the charge accelerating particles Z between the charging sponge roller 2A and the developing sleeve 4a is performed when the developer thin layer Ta on the developing sleeve 4a regulated by the developing blade blade 4c is transferred to the image carrier 1. It is not performed before the development, and does not disturb the developer layer and adversely affect the development.

In this embodiment, there is no need to worry about disturbance of the developer thin layer Ta in the transfer of the developer T and the charge accelerating particles Z between the charging sponge roller 2A and the developing sleeve 4a. The contact condition between the sponge roller 2A and the developing sleeve 4a is not strict, and the degree of freedom of the setting condition increases.

Further, since the component ratio of the developer layer containing the charge accelerating particles Z does not change before and after the transfer of the developer T and the charge accelerating particles Z, stable development can be performed.

In this embodiment, the charging sponge roller 2
A and the developing sleeve 4a are in contact with each other. However, as in the fifth embodiment, the charging sponge roller 2A and the developing sleeve 4a are closely opposed to each other in a non-contact manner with a small gap α. The transfer of the agent T and the charge accelerating particles Z may be performed.

In this embodiment, since the relative speed at the opposing position (developing section) D between the developing sleeve 4a and the image carrier 1 is high, the voltage of the developing sleeve 4a applied to the image carrier 1 is reduced. AC component 3500Hz, 2Kvpp
By doing, in a short time, between the image carrier 1
The developer T is so designed that it can be selectively developed.

In this embodiment, as in the fourth embodiment, the cleaning devices 7a and 7b (FIGS. 12 and 1) are used.
3) may be present.

Further, similarly to the first embodiment, the developer T is not limited to the magnetic toner, and the developing system can be applied to a contact developing system which is generally widely used.

Also in this embodiment, compared with the conventional example, the charge accelerating particles Z can be directly supplied from the developing sleeve 4a to the charging sponge roller 2A to remove the developer T, and the developed image pattern and image can be removed. Since it is less susceptible to the developer T remaining on the carrier 1 on the transfer, stable charging can be obtained for a long period of time, and the effect on the developing device 4 is small, so that a good image can always be obtained. Became.

<Seventh Embodiment> (FIGS. 16 to 20) FIG. 16 is a schematic diagram showing the configuration of an image forming apparatus according to a seventh embodiment. 1, an injection charging device 2, an exposure device 3 disposed inside the image carrier 1, a developing device 4 using a developer T mixed with charging promoting particles Z,
It comprises a transfer device 5, a fixing device 6, and the like.

Also in the present embodiment, the charging device 2 is a device in which the surface of a charging sponge roller 2A made of a conductive sponge contains charging promoting particles Z. The carrier 1 is charged.

In this embodiment, the charging sponge roller 2A and the developing sleeve 4a are separated from each other, and an intermediate roller 8 is provided between the charging sponge roller 2A and the developing roller 4A. 4a are closely opposed to each other with a gap α of 200 μm, and rotate in the arrow direction f. The intermediate roller 8 is a metal roller, and a voltage is applied by a power source S4 so as to have a predetermined potential.

The voltage applied to the intermediate roller 8 is always equal to the voltage applied to the charging sponge roller 2A.
The value is set to a value between the DC component of the voltage applied to the developing sleeve 4a. Therefore, as shown in FIG. 17, due to the potential relationship between the charging sponge roller 2A and the intermediate roller 8, the developer T tends to move to the intermediate roller 8, and the charge promoting particles Z tend to move to the charging sponge roller 2A. .

Similarly, the intermediate roller 8 and the developing sleeve 4a
The developer T tends to move to the developing sleeve 4a, and the charge accelerating particles Z tend to move to the intermediate roller 8 because of the potential relationship.

As a result, the developer T moves from the charging sponge roller 2A to the developing sleeve 4a, and the charge promoting particles Z move to the charging sponge roller 2A.

Here, the use of the intermediate roller 8 enables more efficient movement of the developer T and the charge accelerating element Z by changing the potential of the intermediate roller 8, and the development accompanying the movement thereof. Developer coat Ta on sleeve 4a
To reduce vandalism.

In this embodiment, the potential of the voltage applied to the charging sponge roller 2A, the developing sleeve 4a, and the intermediate roller 8 during the image forming sequence is shown in FIG.
FIG.

The potential of the intermediate roller at the time of image formation is the same as that of the developing sleeve 4a, and the developer T and the charge accelerating particles Z move between the charging sponge roller 2A and the intermediate roller. The movement of the developer T and the charge accelerating particles Z between the and the intermediate roller 8 is hardly performed. Accordingly, during the developing process on the image carrier 1, the disturbance of the developer thin layer Ta does not occur.

Next, the potential of the intermediate roller 8 other than during image formation is set to the same potential as the charging sponge roller 2A. At this time, since the rollers 8.2A are in contact, the developer T and the charge accelerating particles Z
・ It is going to be almost the same amount as 2A. On the other hand, since a large electric field is formed between the intermediate roller 8 and the developing sleeve 4a, the charge accelerating particles Z
The developer T moves to the developing sleeve 4a. For this reason, between these rollers 2A, 8 and 4a, the charge promoting particles Z eventually increase on the charging sponge roller 2A and the intermediate roller 8 side, and the developer T moves on the developing sleeve 4a side. Become.

When the developing process is performed again, the electric field formed between the charging sponge roller 2A and the intermediate roller 8 causes the charge accelerating particles Z to move toward the charging sponge roller 2A between them. While these steps are repeated, the charging promoting particles Z are supplied to the charging sponge roller 2A, and the developer T remaining on the image carrier 1 after the transfer is recovered to the developing sleeve 4a. Then, the step of disturbing the image does not occur.

By carrying out the potential sequence of the intermediate roller 8 as described above, the ideal movement of the developer T and the charge accelerating particles Z between the charging sponge roller 2A and the developing sleeve 4a can be realized.

However, the original meaning of the intermediate roller 8 is that the movement of the charge accelerating particles Z and the developer T can be smoothly performed by increasing the degree of freedom such as potential setting. The optimal potential setting and the like to be performed for each system differ depending on the system. For example, as shown in FIG. 19, the potential of the intermediate roller 8 is repeatedly switched back to the potential of the charging sponge roller 2A and the potential of the developing sleeve 4a every one rotation of the charging sponge roller 2A except during image formation. In some cases, the charge accelerating particles Z and the developer T can be moved efficiently.

Further, in the case of the present embodiment, the image carrier 1
Since a space is created between the charging sponge roller 2A and the developing sleeve 4a, an LED array as the exposure device 3 can be provided in this space as shown in FIG.

In this embodiment, the intermediate roller 8 is in contact with the charging sponge roller 2A and is not in contact with the developing sleeve 4a. However, the charging promoting particles Z and the developer are interposed between these rollers 2A, 8 and 4a. As long as the transfer of T is performed and the developer thin layer Ta on the developing sleeve 4a is not disturbed, the relationship between the respective rollers 2A, 8 and 4a is not limited to contact or non-contact.

Further, the material of the intermediate roller 8 is not limited to metal, but a rubber roller may be used to stabilize the contact state between the rollers 2A, 8 and 4a. It is also possible to use a roller having a medium resistance or a roller having a multilayer structure in order to prevent the occurrence of occurrence.

In this embodiment, as in the fourth embodiment, the cleaning devices 7a and 7b (see FIGS.
3) may be present.

Further, as in the first embodiment, the developer T is not limited to a magnetic toner, and the developing system can be adapted to a contact developing system which is generally widely used.

Also in this embodiment, compared to the conventional example, the charge accelerating particles Z can be directly supplied from the developing sleeve 4a to the charging sponge roller 2A to remove the developer T, and the developed image pattern and image can be removed. Since it is less susceptible to the developer T remaining on the carrier 1 on the transfer, stable charging can be obtained for a long period of time, and the effect on the developing device 4 is small, so that a good image can always be obtained. Became.

In the fourth to seventh embodiments described above, the charge-promoting particles Z mixed with the developer T are applied to the conductive charging sponge roller 2A which comes into contact with the image carrier 1 while rotating.
Is applied to the charging sponge roller 2A, the charging sponge roller 2A is charged to substantially the same potential.
A, by contacting a developing sleeve (developing roller) 4a that transports the developer T to the developing position D with the image carrier 1, that is, a charging sponge roller 2A that contacts and charges the image carrier. By bringing the developing sleeve 4a that performs development into contact with or close to the developing sleeve 4a, the charge-promoting particles that adhere to the charging sponge roller and assist charging are supplied to the charging sponge roller 2A directly from above the developing sleeve 4a.
Alternatively, the same effect can be obtained by providing an intermediate roller in contact with or close to both the charging sponge roller 2A and the developing sleeve 4a. At the same time, the developer T adhered to the charging sponge roller is collected in the developing sleeve 4a. Thus, the supply of the charge accelerating element Z to the charging sponge roller 2A can be directly supplied from the developing sleeve 4a without relying only on the conventional route via the image carrier 1, so that the amount of use of the image forming apparatus can be increased. It is possible to suppress the problem of insufficient charging promoting particles and the occurrence of poor charging due to the adhesion of the developer onto the charging sponge roller 2A.

In addition, when the same pattern is repeatedly developed, the charge accelerating particles Z and the developer T may be unevenly adhered to each other at a specific position on the charging sponge roller 2A to cause poor charging. Since the supply of the charge accelerating particles Z from the developing roller 4a is not affected by the developing pattern, such a problem does not occur.

Further, even when a large amount of the developer T adheres to the charging sponge roller 2A via the image carrier 1 due to a paper discharge failure or the like generated during the image forming process, the developer T and the charging Since the exchange of the accelerating particles Z can be performed directly with the developing roller 4a, the recovery to the original state is quick, the occurrence of charging failure is unlikely to occur, and the recovery is quick.

The supply of the charge accelerating particles Z is controlled by the image carrier 1
Since it is no longer necessary to rely on the route from the printer, it is possible to provide a cleaning step of the image carrier 1 after the transfer step, and the system need not be required to have high transfer efficiency. The degree of freedom above has increased.

In addition, when the sponge roller 2A is not brought into contact with the developing roller 4a, but is brought close to the charge accelerating particles Z by an electric field at such a distance that they can fly, the effect of the present invention is obtained. And the developing roller 4
Factors that disturb the thin developer layer Ta on the substrate a were reduced, so that adverse effects on the developing process were less likely to occur. Alternatively, the contact point between the charging sponge roller 2A and the developing roller 4a may be located downstream of the developing position D with the image carrier 1 in the rotation direction of the developing sleeve 4a. As a result, the adverse effect on the developing process is less likely to occur.

Further, an intermediate roller 8 is provided between the charging sponge roller 2A and the developing roller 4a, and the roller 8 is brought into contact with or close to the respective rollers 2A and 4a to control the potential of the intermediate roller 8. The transfer of the developer T and the charge accelerating particles Z between the respective rollers 2A, 8.4 and 4a can be efficiently controlled at a timing that does not affect the developing process.

Further, by providing the intermediate roller 8, a space is created between the charging device 2 and the developing device 4, so that the exposing device 3 can be installed outside the image carrier.

<Others> 1) The surface resistance of the image carrier is 10 in the case of the injection charging system.
It is desirable to have a layer of ⁹ to 10 ¹⁴ Ω · cm. For example, an OCL photoconductor coated with a surface layer (charge injection layer) in which conductive particles such as SnO ₂ are dispersed on an OPC photoconductor, a photoconductor having a surface layer of α-Si (amorphous silicon, amorphous silicon), etc. Having the charge injection charging property of

2) AC applied to charging device and developing device
As a bias waveform, a sine wave, a rectangular wave, a triangular wave, or the like can be used as appropriate. Alternatively, a rectangular wave formed by periodically turning on / off a DC power supply may be used.
As described above, a bias whose voltage value periodically changes can be used as the waveform of the AC bias.

3) As the image exposure means as information writing means on the charged surface of the image carrier in the image forming apparatus, a digital laser scanning exposure means, an analog image exposure means, or a light emitting element such as an LED was used. Any device that can form an electrostatic latent image corresponding to image information, such as a device using a combination of a light emitting element such as a fluorescent lamp and a liquid crystal shutter or the like, may be used.

4) The image carrier may be an electrostatic recording dielectric or the like. In this case, the dielectric surface has a predetermined polarity.
After uniformly primary charging to a potential, the charge is selectively removed by a charge removing means such as a charge removing needle head or an electron gun to write and form a target electrostatic latent image.

5) The developing method and means of the electrostatic latent image are not limited to the one-component non-contact developing method of the embodiment. A two-component contact developing system or a non-contact developing system may be used. Instead of reversal development, a regular development system may be used.

As the toner particles, pulverized toner or polymerized toner can be used. When the polymerized toner is used, the amount of the transfer residual toner can be further reduced, and a sufficient collecting effect by the developing means can be obtained.

6) The transfer means is not limited to the roller transfer of the embodiment, but may be blade transfer or other contact transfer charging method.
A non-contact transfer charging system using a corona charger may be used.

7) An arbitrary image forming process device such as an image carrier, a charging device, and a developing device may be detachably attached to and detachable from a main body of the image forming apparatus. it can.

In the drawing, PC is a process cartridge, which includes an image carrier 1, a charging device 2, a developing device 3, and a cleaning device 7a or 7b. The process cartridge PC is detachably attached to a predetermined position in the image forming apparatus main body by a guide support unit (not shown).
By being attached to the image forming apparatus main body in a predetermined manner, it is mechanically and electrically coupled to the image forming apparatus main body.

8) Using an intermediate transfer member such as a transfer drum or a transfer belt as a second image carrier, an image forming apparatus for forming not only a single color image but also a multi-color or full-color image by multiple transfer or the like. Applicable.

9) An electrophotographic photosensitive member or an electrostatic recording dielectric as an image carrier is formed into a rotating belt type, and a toner image corresponding to required image information is formed thereon by a charging, latent image forming and developing process means. An image display device (display device) that is used for forming a display image and displaying the image by positioning the toner image forming portion on the reading and displaying portion, and using the image carrier repeatedly to form a display image
There is also. The image forming apparatus of the present invention includes such an image display device.

[0226]

As described above, according to the present invention, as in a sponge roller type injection charging device, a voltage is applied to form a nip portion with an image carrier and the flexible member charges the image carrier. Image forming using a charging means having a charging member having a chargeability, and charging the image carrier by injecting a charge through charging nip particles for promoting charging of the image carrier by the charging member in the nip portion. In the apparatus, the supply of the charge-promoting particles to the charging member is performed directly and directly from the developing means side without passing through the image carrier, so that the charging is efficiently and stably performed, and the stable charging is performed for a long time. By maintaining the processing, it is possible to suppress the occurrence of charging failure and always obtain a good image.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the configuration of an image forming apparatus according to a first embodiment.

FIG. 2 is a diagram illustrating the behavior of a developer and a charge-promoting particle in a developing section.

FIG. 3 is an enlarged model diagram of a main part.

FIG. 4 is a sequence diagram of switching of a charged sponge roller position.

FIG. 5 is a schematic configuration diagram of an image forming apparatus in which a blade cleaning device is provided in the image forming apparatus of FIG. 1;

FIG. 6 is a schematic configuration diagram of an image forming apparatus in which a roller cleaning device is provided in the image forming apparatus of FIG. 1;

FIG. 7 is a schematic diagram of a main part of an image forming apparatus according to a modified example.

FIG. 8 is a schematic diagram of a main part of an image forming apparatus according to a second embodiment.

FIG. 9 is a schematic diagram of a main part of an image forming apparatus according to a third embodiment.

FIG. 10 is a schematic diagram of a main part of an image forming apparatus according to a fourth embodiment.

FIG. 11 is a potential sequence diagram of the charging sponge roller and the developing sleeve.

FIG. 12 is a schematic configuration diagram of an image forming apparatus in which a blade cleaning device is provided in the image forming apparatus of FIG. 10;

13 is a schematic configuration diagram of an image forming apparatus in which a roller cleaning device is provided in the image forming apparatus of FIG.

FIG. 14 is a schematic diagram of a main part of an image forming apparatus according to a fifth embodiment.

FIG. 15 is a schematic diagram of a main part of an image forming apparatus according to a sixth embodiment.

FIG. 16 is a schematic diagram of a main part of an image forming apparatus according to a seventh embodiment.

FIG. 17 is a diagram illustrating the behavior of the developer and the charge accelerating particles between the charging sponge roller and the intermediate roller and between the intermediate roller and the developing sleeve.

FIG. 18 is a potential sequence diagram of the charging sponge roller and the developing sleeve (part 1)

FIG. 19 is a potential sequence diagram of the charging sponge roller and the developing sleeve (part 2)

FIG. 20 is a schematic model diagram of an image forming apparatus according to a modification.

FIG. 21 is an explanatory diagram of a roller charging device.

FIG. 22 is an explanatory diagram of a magnetic brush charging device.

FIG. 23 is an explanatory view of a fur brush charging device.

FIG. 24: Description of a sponge roller charging device

FIG. 25 is a schematic configuration diagram of an example of an image forming apparatus using a sponge roller charging device.

26 is a diagram in which a means for directly supplying a charge accelerating particle to a charge sponge roller is added to the image forming apparatus of FIG.

[Explanation of symbols]

1 is an image carrier, 2 is a sponge roller charging device, 2A is a charging sponge roller, 2B is a charging promoting particle supply device, 2X
Is a roller charging device, 2Y is a magnetic brush charging device, 2Z is a fur brush charging device, 3 is an exposure device (LED array), 4 is a developing device, 4a is a developing sleeve, 4b is a developing magnet, 4c is a developing blade, and 4d is a developing blade. Container, 5
Is a transfer device, 6 is a fixing device, 7a is a blade cleaning device, 7b is a roller cleaning device, 8 is an intermediate roller, 9 is a charging sponge roller support member, 10 is a charging sponge roller moving guide member, L is an exposure signal, and P is Transfer paper, T is a developer, Z is a charge accelerating particle, S1 is a power supply of a charging device, S2 is a power supply of a developing device, S3 is a power supply of a transfer device,
S4 is the power supply of the intermediate roller, R1 is the position of the charging sponge roller at the time of image formation, and R2 is the position of the charging sponge roller at the time of supplying the charging promoting particles.

Claims (6)

[Claims] An image carrier, charging means for charging the image carrier, image information writing means for forming an electrostatic latent image on a charged surface of the image carrier, and a developer And a developing means for visualizing the image bearing member.The charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier, and charges the image carrier, and at least the nip portion In the developing means, the charge promotion particles for promoting the charging of the image carrier by the charging member are interposed, and the developing means has the charge promotion particles mixed in the developer, and carries and transports the developer to the developing portion. A developing member for developing the electrostatic latent image on the image carrier, at least one of the charging member and the developing member is movable, and during a process other than image formation, the charging member and the developing member By moving at least one of them Collecting member and is brought into contact with the developing member, an image forming apparatus in which the developer and a charging accelerating particles, characterized in that as a moveable between them. 2. An image carrier, charging means for charging the image carrier, image information writing means for forming an electrostatic latent image on a charged surface of the image carrier, and a developer And a developing means for visualizing the image bearing member.The charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier, and charges the image carrier, and at least the nip portion In the developing means, the charge promotion particles for promoting the charging of the image carrier by the charging member are interposed, and the developing means has the charge promotion particles mixed in the developer, and carries and transports the developer to the developing portion. A developing member for developing the electrostatic latent image on the image carrier, at least one of the charging member and the developing member is movable, and during a process other than image formation, the charging member and the developing member By moving at least one of them Collecting member and is close to a developing member, the developer and a charging accelerating particles by the electric field formed between these, the image forming apparatus is characterized in that as a moveable between them. 3. An image forming apparatus according to claim 1, wherein said charging member is detachable from said image carrier when said charging member moves to said developing member. apparatus. 4. An image carrier, charging means for charging the image carrier, image information writing means for forming an electrostatic latent image on a charged surface of the image carrier, and a developer And a developing means for visualizing the image bearing member.The charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier, and charges the image carrier, and at least the nip portion In the developing means, the charge promotion particles for promoting the charging of the image carrier by the charging member are interposed, and the developing means has the charge promotion particles mixed in the developer, and carries and transports the developer to the developing portion. A developing member for developing the electrostatic latent image on the image carrier, wherein the charging member and the developing member are in contact with each other, and the developer and the charge promoting particles are movable between them; Characteristic image forming apparatus. 5. An image bearing member, charging means for charging the image bearing member, image information writing means for forming an electrostatic latent image on a charged surface of the image bearing member, and developing agent for the electrostatic latent image And a developing means for visualizing the image bearing member.The charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier, and charges the image carrier, and at least the nip portion In the developing means, the charge promotion particles for promoting the charging of the image carrier by the charging member are interposed, and the developing means has the charge promotion particles mixed in the developer, and carries and transports the developer to the developing portion. A developing member that develops an electrostatic latent image on the image carrier; the charging member and the developing member are close to each other; and the developer and the charge promotion particles are caused by an electric field formed therebetween. Image forming, movable between these Location. 6. An image carrier, charging means for charging the image carrier, image information writing means for forming an electrostatic latent image on a charged surface of the image carrier, and a developer And a developing means for visualizing the image bearing member.The charging means has a flexible charging member to which a voltage is applied, forms a nip portion with the image carrier, and charges the image carrier, and at least the nip portion In the developing means, the charge promotion particles for promoting the charging of the image carrier by the charging member are interposed, and the developing means has the charge promotion particles mixed in the developer, and carries and transports the developer to the developing portion. A developing member that develops an electrostatic latent image on the image carrier; a rotatable member that is in contact with or close to both of the charging member and the developing member;
The rotatable member can take an intermediate potential with respect to the potentials of the charging member and the developing member,
Between the charging member and the rotatable member, and between the developing member and the rotatable member, the developer and the charge-promoting particles move between them due to an electric field formed by the potential difference between the potentials. An image forming apparatus characterized in that it is possible.