JPH09311561A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of discharging and excellently cleaning the surface of the belt of a peeling and carrying device which peels a transfer material from an image carryer and carrys it, capable of preventing transfer performance and peeling performance from lowering due to the accumulation of charge, and also an image forming device to which the belt device and the cleaning device are easily attached/detached, and which can keep excellent image forming without exerting influence on the cleaning performance, the transfer performance and the peeling performance by exchanging the device. SOLUTION: A cleaning means disposed in the peeling and carrying device 30 consisting of the endless belt 35 is provided with a conductive blade 41 coming in contact with the surface of the dielectric layer 350 of the belt and a regulating member 49 regulating the position of the belt disposed on the side of the conductor layer 355 of the belt, and disposed at a corresponding position through the belt 35. The blade 41 and a position regulating member 49 are integrated through an attaching member 47 to form a blade unit 40. The blade unit 40 is disposed on the downstream side of a 2nd roll 33 and on the upstream side of a 1st roll 31. AC voltage having peak voltage equal to or above discharge start voltage is impressed on the blade 41 so as to surely discharge the surface of the belt 35.

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 an electrostatic transfer process such as an electrostatic copying machine and a printer,
In particular, the present invention relates to an image forming apparatus including a transfer device that separates a transfer material from an image carrier.

[0002]

2. Description of the Related Art An image forming apparatus including a step of transferring a transferable toner image formed electrostatically on the surface of an image bearing member to a transfer material such as paper is required to charge the transfer material at the time of transfer. However, the transfer material tends to be attracted to the image carrier, and the peeling property between the image carrier and the transfer material deteriorates. As in recent years, as the printing speed in the image forming apparatus is increased and the process speed is increased and the diameter of the image carrier is increased, the above-mentioned problems are likely to occur.

Conventionally, as a means for improving the peeling property of the transfer material from the surface of the image carrier, an endless belt to which a bias voltage having a polarity opposite to the polarity applied at the transfer portion is applied is arranged downstream of the transfer device. A method of contacting or approaching the transfer material after transfer to electrostatically attract the transfer material to separate it from the image carrier (separation conveyance belt method), or transfer material by applying transfer charge to the endless belt surface. A method of transferring (transfer belt method) while adsorbing and transferring is used. The transfer belt method electrostatically attracts the transfer material to the belt before transfer,
In addition, since the curvature of the belt is larger than that of the image carrier, the transfer material is not adsorbed to the image carrier in the transfer process.

However, in both the peeling / conveying belt system and the transfer belt system, since the belt is brought into contact with or brought close to the image carrier, the surface of the belt is easily soiled with toner. If the toner adheres to the surface of the belt and is soiled, the back surface of the transfer material is contaminated with the toner when the belt sucks and conveys the transfer material. In order to prevent such a problem, a belt surface cleaning means is provided. Blades and brushes are often used as belt cleaning devices. Further, in both the peeling and conveying belt system and the transfer belt system, if the transfer charge applied to the transfer material leaks through the belt, the transfer property is deteriorated. In order to prevent such a problem, it is desirable that the surface of the belt that contacts the transfer material be a dielectric.

However, when the surface of the belt is made of a dielectric material, the problem that the transfer charge leaks is improved, but on the other hand, the charge attached to the surface of the belt becomes difficult to move, so that the charge on the surface of the belt is increased as the transfer, peeling and conveyance cycles are repeated. As a result, the surface potential of the belt changes due to the accumulation, which causes a problem that transferability and peeling property decrease with time. As a method of cleaning the surface of the belt and improving the transferability and peeling property deterioration due to charge accumulation, a method of removing the electric charge on the surface of the belt by using a conductive cleaning blade is disclosed in JP-A-53-53.
It is disclosed in Japanese Patent No. 104246. This method is economically preferable in that no special static eliminator is required because the cleaning member has a static erasing function. But,
Since the blade has a very small contact width (nip width) with the belt, the charge removal is incomplete, and charge accumulation occurs during the transfer, peeling, and conveying cycles, and the transferability and peelability are not reduced, and the problem cannot be solved. Further, since the toner adhering to the belt surface is charged and electrostatically adsorbed to the belt, there is a problem that cleaning efficiency is not sufficient.

[0006] In addition, JP-A-1-1544074, 154
No. 075,154077, a charging means for precharging is arranged in front of the cleaning position to improve the cleaning property, and a conductive brush in a grounded state and a charging device for charging the belt surface are arranged so that the potential of the belt surface is increased. A method of stabilizing is disclosed. This method was effective in solving the problems that the cleaning property of the toner electrostatically adsorbed on the belt and the transfer property and the peeling property due to the accumulation of electric charges are deteriorated. However, a special charger is required for cleaning and charge removal, which is not economical, and the device cannot be downsized. In addition to this, when the corotron is used as the charger because the number of chargers increases, there is an environmental problem that ozone increases.

[0007]

Therefore, the present invention achieves the following objects. A belt cleaning device that removes and conveys the transfer material from the image carrier does not require a corona charger to eliminate static electricity on the belt surface or a grounded conductive member, and has good belt cleaning performance and transfer due to charge accumulation. Of a belt device or a cleaning device,
(EN) Provided is an apparatus which can be easily removed and which can maintain good image formation without being affected by cleaning property, transfer property and peeling property by replacement.

[0008]

The cleaning means provided in the peeling / conveying device formed of an endless belt of the image forming apparatus of the present invention or the transfer peeling device is composed of a conductive blade and a conductive blade. Has a configuration in which an AC voltage having a peak voltage equal to or higher than the discharge start voltage is applied. Further, the support roll of the endless belt is composed of a first roll adjacent to the image carrier and a second roll arranged on the downstream side in the rotational direction of the belt, and the conductive blade of the cleaning means is the second roll. Downstream and upstream of the first roll, it contacts the dielectric layer of the belt. Further, the cleaning unit of the image forming apparatus includes a conductive blade that comes into contact with the surface of the belt dielectric layer, and a regulation member that regulates the position of the belt disposed on the side of the conductive layer of the belt. The position regulating member is arranged at a corresponding position via a belt, and the conductive blade and the position regulating member are integrated via a mounting member so that a constant discharge gap is always formed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. Although the embodiment shown in the drawings shows an example of an image forming apparatus having a peeling / conveying device, the structure of the discharging / cleaning means is the same in the image forming apparatus having a transfer belt.

FIG. 1 is a schematic sectional view showing the structure of an image forming apparatus embodying the present invention. The image forming apparatus is the image carrier 1.
0, a transfer device 20, and a peeling / conveying device 30. The image carrier 10 has an axis perpendicular to the plane of the drawing and rotates in the direction of arrow X. The outer diameter of the image carrier 10 shown in this figure is 8
4 mm. The photosensitive layer on the surface of the image carrier 10 is uniformly charged to −750 V by a corona charger (not shown) while rotating. This charged surface is irradiated with an image-modulated laser beam (not shown) to form an electrostatic latent image on the surface of the image carrier 10. The process speed of this image forming apparatus is 250 mm / s. Negatively charged toner supplied from a developing device (not shown) adheres to the electrostatic latent image portion of the image carrier 10 to form a toner image. Then
This toner image is transferred to the transfer roll 20 adjacent to the image carrier 10.
Reach the position of arrangement. The transfer material P is supplied from the carrying path at the timing when the toner image reaches the transfer portion. At the same time as the transfer material P is supplied, the control device controls the transfer roll 20.
Then, a transfer bias of 30 μA is applied. The toner image is transferred to the transfer material P.

After that, the transfer material P carrying the toner image is peeled from the image carrier and is conveyed to a fixing section (not shown) through a conveyance path formed by the peeling / conveying device 30 to be fixed to the outside of the apparatus. Is discharged. On the other hand, the toner remaining on the image carrier 10 without being transferred to the transfer material P at the transfer unit 20 is the image carrier 1.
Removed by a cleaner (not shown) disposed adjacent to 0, the image carrier 10 moves to the next imaging cycle.

The peeling / conveying device 30 transfers the transfer material P to the image carrier 1.
0 Peel from the surface and convey. The peeling / conveying device 30 includes a belt 35 that conveys the transfer material P, a first roll 31 and a second roll 33 that support the belt 35. The belt 35 has a dielectric layer 35 on the side (outside) that contacts the transfer material P.
0, the side contacting the roll (inner side) is 2 of the conductor layer 355.
It is composed of layers. In this embodiment, the dielectric layer 350 disposed on the outer side of the belt 35 is made of polyamide elastomer (PAE; manufactured by Daicel Huls) having a thickness of 60 μm, and the conductive layer 355 disposed on the inner side is 40 μm in thickness. It is an endless belt made of PAE in which the carbon is dispersed. The resistance value of the dielectric layer 350 on the side of contact with the transfer material P and outside the belt needs to be sufficiently higher than the resistance value of the transfer material P at a predetermined applied voltage, for example, 10 ¹³ Ωcm.
The above is desirable. Inner conductor layer 35 abutting the roll
5 may be in a range in which applied bias voltage loss does not occur, and is preferably 10 ⁴ Ωcm or less. The resistance value of the conductor layer 355 in this embodiment is adjusted to 10 ¹ to 10 ² Ωcm. However, the material, thickness, etc. of the belt are not limited to those in the above-mentioned embodiment, and any material such as nylon, Teflon, silicone rubber, urethane foam, etc. that can satisfy the mechanical strength required for the belt may be used. Further, the belt structure is not limited to the two-layer molded tube, and may be, for example, a structure in which a sheet obtained by vapor-depositing a metal layer on a dielectric layer is seamed, or a structure in which an insulating layer is coated on the outside of a low resistance tube. Of course, it is good.

The belt 35 is supported by the first roll 31 and the second roll 33, is stretched by means such as a spring (not shown), and is movable in the arrow Y direction. The first roll 31 is arranged in contact with the image carrier 10. The roll 31 is a roll having an outer diameter of 14 mm, in which a metal shaft 311 having a diameter of 8 mm is coated with an EPDM foam layer 313 in which carbon is dispersed as a conductive material and the resistance value is adjusted to 10 ⁴ Ω.
The second roll 33 is disposed on the downstream side in the moving direction of the belt 35 and does not come into contact with the image carrier 10. The second roll 33 is made of aluminum having the same outer diameter as the first roll 31.

A blade unit 40 having a blade 41 in contact with the belt 35 is arranged in the peeling / conveying device 30 (see FIGS. 1 and 2). The blade unit 40 includes a blade 41, a blade support member, and a blade gap regulation member 49, and is arranged on the downstream side of the second roll 33 and on the upstream side of the first roll 31.

The blade 41 is made of urethane rubber and LiClO.
4 is added to form a plate-shaped body. The blade 41 is preferably made of a material having a volume resistance of about 10 ³ Ω · cm to 10 ¹⁰ Ω · cm.
⁴ Ω · cm to 10 ⁷ Ω · cm is preferable. The size of the blade 41 shown in this embodiment is 8 mm in width and 2 mm in thickness, and the volume resistance is adjusted to 10 ⁵ Ω · cm. In addition to the examples, the blade is made of EPDM rubber in which an electronic conductive material such as carbon is dispersed to adjust the resistance value, or urethane rubber is used in the electronic conductive material such as carbon and Li.
There is a hybrid dispersion of an ion conductive agent such as ClO4. The blade 41 is a conductive support member 43.
Attached to. The conductive support member 43 is composed of a phosphor bronze plate. The thickness of the support member 43 can be freely selected in order to obtain a desired elasticity, but in consideration of the contact pressure, the thickness can be 0.
The plate body has a thickness of about 05 mm to 0.2 mm. In this embodiment, the thickness of the support member 43 is 0.1 m.
It is a plate of m.

The conductive support member 43 is fixed to the holder 45. The holder 45 is attached via the holder mounting member 47.
It is attached to the housing 15 to which the belt is attached. A gap regulation member 49 is attached to the holder attachment member 47. The gap regulating member 49 is composed of a SUS plate having a polyimide film attached to the surface that contacts the belt. The SUS plate is grounded, the belt and the SUS plate are insulated, and the holder is attached so as to contact the tip of the blade 41. It is fixed to the member 47 and is integrated with the blade 41. Blade unit 40 configured in this way
The belt 35 is sandwiched between the holder mounting member 47 and the gap regulating member 49 and disposed in the peeling / conveying device 30, and the blade unit 40 is detachable from the peeling / conveying device 30.

The attachment of the blade unit 40 to the peeling / conveying device 30 will be described with reference to FIG. The belt 35 is sandwiched between the gap regulating member 49 of the blade unit 40 and the blade 41, and the blade unit 40
Are arranged in the peeling and conveying device 30. The blade 41 attached to the conductive support member 43 has its tip with respect to the surface of the belt 35 on which the gap regulating member 49 is provided on the back surface.
The setting angle SA is tilted so as to form an angle of 20 degrees. Further, the blade 41 is attached so that the leading end is pressed against the belt 35 in the direction of the belt 35, with the amount of biting into the belt 35 being N. The blade 41 attached in this way bends due to the elasticity of the blade 41 itself, and the tip of the blade 41 forms a constant contact width W and comes into contact with the belt 35. In this embodiment, the setting angle SA is 20 degrees, and the bite amount N is 1.0 m.
When m, the contact width W between the tip of the blade 41 and the belt 35 is W = 0.03 mm. Thus, the blade unit 40 has a contact width (nip width) between the blade 41 and the belt 35 whose position is regulated by the gap regulating member 49.
W can be constant.

Next, the case where a frequency of 1 KHz and a peak-to-peak voltage of 2 kVAC are applied as a bias voltage to the conductive support member 43 of the blade unit 40 will be described. The belt 35 rotating in the direction of the arrow Y is a nip portion having a width W formed between the belt 35 and the blade 41, and the electric charges accumulated on the surface are removed. At this time, since the tip of the blade 41 is positioned by the gap regulating member 49, the nip width between the moving belt 35 and the blade 41 is kept constant, and the static electricity can be reliably removed without being influenced by the movement of the belt or the like. Is executed. The toner T attached to the surface of the belt 35 is wiped off by the tip of the blade 41. Here, the bias power source may be connected via the holder 45. In this way, the blade unit 40 performs the charge removal of the surface of the belt 35 and the cleaning action of the toner.

A method of applying an AC voltage having a peak voltage equal to or higher than the discharge start voltage to the conductive blade is disclosed in Japanese Patent Publication No. 7-27316 and Japanese Patent Laid-Open Publication No. 60-72316 as a blade type contact charger.
It is known from Japanese Patent Publication No. 147756. However, the discharge gap must be accurately formed in order to form a stable discharge state with the blade type contact charger. It is easy to form the discharge gap when the shape of the image bearing member that the conductive blade is in contact with is stable, but as in this image forming apparatus, the contact of the conductive blade is like a belt. In this embodiment, a discharge gap forming member is provided to stabilize the discharge gap when there is flexibility and vibration due to rotation. That is, the gap regulating member 49 is arranged at a position corresponding to the belt 35 with which the conductive blade 41 comes into contact, so as to form a constant discharge gap.

Generally, the belt and the blade are replaced due to scratches, damage to the ends, etc., but the integrated blade and gap regulating member can be replaced because the distance between the belt and the blade can be made constant. In this case, a stable discharge gap is formed. When the charging device of the image forming apparatus is provided with a contact charging device such as a bias charging roll (BCR) for applying a bias in which a sine wave is superimposed as a DC component and an AC component, or a blade charger, an AC power source of the charging device is provided. Can be shared as a bias power source for the blade unit. Further, the image forming apparatus in which the bias voltage applied to the belt is 0 V in the non-sheet passing portion achieves energy saving.

Example 1 The copy state was evaluated using a chart in which a black band of 15 mm was provided at a position 3 mm away from the tip. A belt bias of -600V was applied. Transfer defects such as white spots do not occur in the black band, and transferability in continuous printing,
No reduction in peelability was observed.

[0022]

【The invention's effect】

(1) Separation of a transfer material of an image forming apparatus in which a surface contacting with a transfer material is a dielectric and a back surface of the belt is an endless belt composed of at least two layers of conductors, stretched and rotated in a certain direction. Since the transporting and transferring transporting device uses the blade unit to perform both cleaning action and charge removing action, a special corona charger and charge removing device are not required, and the device can be downsized and the cost can be reduced. (2) Since the AC static elimination method is adopted, it is possible to respond to the change in the process speed by the change in the AC frequency, and the transferability and the peeling property can be well maintained even if the process speed becomes faster, without disposing a special additional device. . (3) Since the blade is unitized with the gap regulating member, it can be easily attached to and detached from the conveying device, and stable static elimination performance can be reliably obtained. (4) Since the corotron is not used as the static elimination means, the ozone generation amount can be reduced. (5) In the case of an image forming apparatus using a contact charger as the charging device, the AC power source of the charging device can be shared, so that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional view taken along the arrow of FIG. 1 at a blade unit mounting portion.

FIG. 3 is an explanatory diagram of blade parameters.

FIG. 4 is an explanatory diagram of blade parameters.

[Explanation of symbols]

10 image carrier, 20 transfer device, 30 peeling / conveying device, 31 first roll, 33 second roll,
44 blade unit, 41 blade, 43
Conductive support member, 45 holder, 47 holder mounting member, 49 gap regulating member.

Claims (5)

[Claims] 1. An endless belt composed of a laminated body of at least two layers of a dielectric layer on the surface in contact with a transfer material and a conductive layer on the back surface, and the endless belt is supported and stretched in a fixed direction. It is equipped with a roll that rotates and moves, and a cleaning unit that contacts the dielectric layer surface of the endless belt and cleans the belt surface.The conductor layer of the endless belt is grounded, or a bias of the opposite polarity to that applied by the transfer device is applied. An image forming apparatus equipped with a peeling / conveying device for applying a voltage to bring a belt into contact with or close to a transfer material on the downstream side of the transfer device to separate and convey the transfer material from an image carrier. Is an electrically conductive blade, and the electrically conductive blade is configured to be applied with an AC voltage having a peak voltage equal to or higher than a discharge start voltage. 2. An endless belt composed of a laminated body of at least two layers of a dielectric layer on the surface in contact with the transfer material and a conductive layer on the back surface, and the endless belt is supported and stretched in a fixed direction. It is equipped with a roll that rotates and moves to the endless belt, and a cleaning unit that contacts the dielectric layer surface of the endless belt and cleans the belt surface, and the conductive layer of the endless belt has a bias voltage of a polarity opposite to that of the transferable toner on the surface of the image carrier. In an image forming apparatus equipped with a transfer device that applies a toner to a transfer material to transfer a toner image from an image carrier, the cleaning means of the transfer device is composed of a conductive blade, and the conductive blade starts discharge. An image forming apparatus configured to be applied with an AC voltage having a peak voltage equal to or higher than the voltage. 3. A supporting roll of the endless belt comprises a first roll adjacent to the image carrier and a second roll arranged on the downstream side in the rotation direction of the belt, and the conductive blade of the cleaning means is the second roll. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to contact the dielectric layer of the belt on the downstream side of the first roll and on the upstream side of the first roll. 4. The cleaning unit includes a conductive blade that contacts the surface of the belt dielectric layer, and a regulating member that regulates the position of the belt disposed on the side of the conductive layer of the belt. The restriction member is arranged at a corresponding position via a belt, or claim 2
The image forming apparatus as described in the above. 5. The image forming apparatus according to claim 4, wherein the conductive blade of the cleaning means and the position regulating member are integrated via a mounting member.