JPH11174858A - Recording material peeling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely peel recording material from an image carrier, to prevent defective carrying of the peeled recording material and also to prevent irregularities in a transferred toner image by constructing a device so that it may be provided with a conductive grounded sheet-like member and the leading end of a guiding member may extend toward a transfer position with reference to the sheet-like member. SOLUTION: The device is provided with the insulating or semiconductive guiding member 1 with which the recording material discharged from the transfer position comes into contact, and the conductive grounded sheet-like member 2 installed in contact with the rear side of the guiding member 1, and the leading end of the guiding member 1 is arranged so as to extend toward the transfer position with reference to the sheet-like member 2. By having such a constitution, the recording material discharged from the transfer position surely comes into contact with the guiding member 1 before the recording material reaches the sheet-like member 2, and the recording member is carried along the guiding member 1, so that defective carrying such the recording material is caught by the sheet-like member 2 or the like is suppressed. Besides, the recording material does not directly come into contact with the conductive sheet-like member 2, so that the irregularities in the unfixed toner image held by the recording material are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material peeling device for an image forming apparatus using an electrophotographic process, and more particularly, to a recording material peeling device for guiding a recording material to an appropriate conveyance path after transfer.

[0002]

2. Description of the Related Art Conventionally, a toner image is formed on an image carrier by an electrophotographic process, the toner image is transferred onto a recording material conveyed at a predetermined timing, and the toner image is subjected to heat or pressure. 2. Description of the Related Art There is known an image forming apparatus which obtains a permanent image by being fused and fixed on a recording material by an action. In such an image forming apparatus, in order to transfer a toner image onto a recording material, a method using corona discharge by a transfer charger or a nip between a transfer roll to which a charge is applied and an image carrier holding a toner image is used. Is passed through a recording material.

A problem in performing such transfer is that the recording material may stick to the image carrier after the transfer. That is, at the time of transfer, the toner image is transferred to the recording material by the action of an electric field. At that time, the recording material itself is also charged, and is attracted to the image carrier by the electrostatic force, and is moved to a predetermined position. The recording material to be separated from the image carrier and conveyed to the fixing position may stick to the image carrier as it is. In particular, in a so-called full-color image forming apparatus, since a large amount of toner images superimposed on one another in multiple layers must be transferred to a recording material at the moment of a slight transfer, a strong electric field is generated at the time of transfer, and the recording material also It tends to be strongly charged, and tends to stick to the image carrier.

When the recording material adheres to the image carrier and the recording material follows the rotation of the image carrier, various problems are caused. That is, if the recording material directly enters the image carrier cleaning device, the cleaning device and the image carrier may be damaged. For this reason, it has been conventionally detected that the recording material is stuck to the image carrier,
There are image forming apparatuses that immediately stop the image forming operation, but even in such a case, it is difficult for the user to remove the recording material stuck to the image carrier, and the work by a specialized technician is required. This imposes a burden on time and economy, which is not preferable. Therefore, means for preventing the recording material from sticking to the image carrier after the transfer is required.

In view of this, Japanese Patent Publication No. 8-23719 has already proposed a technique in which a peeling plate is formed of a grounded conductive member and an insulating shielding plate protruding toward the transfer portion. FIG. 11A shows an example of a conventional recording material peeling apparatus. Here, when the recording material charged from the transfer position approaches the conductive portion, an electric charge having a polarity opposite to that of the recording material is induced by the conductive portion, and the recording material is attracted by the charge and easily peeled off from the image carrier. It is. Further, since the recording material is conveyed in contact with the insulating shielding plate, the charged recording material is not discharged at a stroke, and the disturbance of the transferred toner image can be prevented. .

[0006]

However, in such a recording material peeling device, a recording material conveyance failure such as the recording material being caught on the conductive portion or entering between the transfer device and the recording material peeling device. May occur. That is, in FIG. 11B, the arrow indicates the appropriate recording material conveyance direction, but the electric charge induced by the conductive portion concentrates on the P portion closest to the recording material.
Attracted towards the part by electrostatic forces. Then
The recording material may advance as shown by the arrow and be caught by the conductive portion. In some cases, the recording medium may take a path of a lower arrow due to the influence of gravity acting on the recording medium. In this case, the recording medium enters between the transfer device and the recording material peeling device.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to reliably peel off a recording material from an image carrier and to remove a recording material after peeling. It also prevents transport failures such as getting caught in the device and entering between the transfer device and the recording material peeling device,
Another object of the present invention is to provide a recording material peeling device of an image forming apparatus that does not disturb the transferred toner image.

[0008]

According to the present invention, a toner image formed on an image carrier by an electrophotographic process is transferred to a recording material conveyed at a predetermined timing at a transfer position. In a recording material peeling device provided adjacent to a transfer position and at a downstream side in a recording material conveyance direction to promote peeling from a body, the recording material peeling device is provided with an insulating member for contacting a recording material discharged from the transfer position. A conductive or semiconductive guide member, and a conductive grounded plate member provided in contact with the back surface of the guide member, and the tip of the guide member is transferred to the plate member. It extends to the position side.

Further, in the present invention, a portion of the tip of the plate-like member which does not contact the guide member is covered with an insulating or semiconductive cover member.

Further, according to the present invention, after a toner image formed on an image carrier by an electrophotographic process is transferred to a recording material conveyed at a predetermined timing at a transfer position, the recording material is peeled from the image carrier. A recording material peeling device provided adjacent to the transfer position on the downstream side in the recording material transport direction to promote the recording material to be insulated or semiconductive in contact with the recording material discharged from the transfer position. And a conductive grounded plate-shaped member provided in contact with the back surface of the guide member, and another portion of the plate-shaped member is provided on a surface where the plate-shaped member comes into contact with the guide member. It has a low-resistance portion having a lower electric resistance value than the above.

The present invention also provides a power supply unit for supplying a bias voltage for attracting a recording material to the plate member, and a determining unit for determining a timing at which an image area of the recording material discharged from a transfer position contacts the guide member. And a control unit that controls the power supply unit to turn off a bias voltage supplied to the plate-shaped member while the image area of the recording material is in contact with the guide member based on the determination of the determination unit. Things.

[0012]

Next, preferred embodiments of the present invention will be described based on examples. Embodiment 1 FIG. 1 shows a configuration of a recording material peeling apparatus according to an embodiment together with a configuration around the recording material peeling apparatus. The recording material peeling device separates the recording material from the image carrier after the recording material, which has been conveyed at a predetermined timing, is transferred to the toner image formed on the image carrier by an electrophotographic process at a predetermined transfer position. In a recording material peeling device provided adjacent to the transfer position on the downstream side in the recording material conveyance direction to promote
The recording material peeling device includes an insulating or semiconductive guide member 1 with which the recording material discharged from the transfer position contacts, and a conductive grounded plate provided in contact with the back surface of the guide member 1. And the tip end of the guide member extends toward the transfer position with respect to the plate member 2.

The guide member 1 has an insulating member on the surface in contact with the recording material conveyed to the fixing device after the secondary transfer, and guides the recording material to an appropriate conveyance path. The guide member 1 may be made of a single material such as ABS resin, polycarbonate, conductive resin or the like, or may have a multi-layered structure. It is necessary to be constituted by a member or a semiconductive member. In this embodiment, the guide member 1 is made of a single material, and has a volume resistivity of 10 ³ to 10 ³ .
A material of about 10 ¹³ Ω · cm is used.

The plate member 2 is provided on the surface of the guide member 1 on which the recording material does not contact, and is made of a conductive material. For example, a sheet metal, an electrogalvanized steel sheet, or the like can be used.

FIG. 2A shows a guide member 1 and a plate-like member 2.
Are shown from different viewpoints. In this embodiment, the guide member 1 has a rib shape. FIG.
(B) shows a front end portion on the transfer position side between the guide member 1 and the plate member 2.

Here, the angle α formed between the intermediate transfer belt downstream of the transfer position shown in FIG. 1 and the recording material discharge direction is:
This is determined in consideration of the other configuration of the image forming apparatus, the ease of sticking the recording material to the intermediate transfer belt, and the like. That is, it is desirable to configure the angle α to be large in order to make the recording material difficult to stick to the intermediate transfer belt. However, it is difficult to make the angle α too large due to a space problem of other components of the image forming apparatus. There is. Further, an angle β formed between the guide member 1, the plate-shaped member 2 and the recording material discharging direction.
Is determined in consideration of the releasability of the recording material, prevention of image disorder, transferability, and the like. In consideration of these, the angles α and β are determined. In this embodiment, the angle α is 35 ° and the angle β is 10 °.
And

In FIG. 2B, the distance l ₁ from the transfer position to the tip of the guide member 1 can be appropriately designed from the viewpoint of peeling of the recording material and prevention of jam. That is, the shorter the distance l ₁ is, the easier it is to guide the transferred recording material to an appropriate transport path. However, if the distance l ₁ is designed to be too short, the recording material is caught by the guide member 1, the recording material is clogged, and the recording material is There is a possibility that conveyance failure such as winding may occur. Therefore, the distance l ₁ is determined taking these factors into consideration comprehensively. In the present embodiment, the distance l ₁ is set to 7 mm.

Further, the plate member 2 at the tip of the guide member 1 is
Extension length l_TwoIs the magnitude of the action that attracts the recording material
Design from the viewpoint of preventing
Can be That is, the extension length l_TwoSet shorter
The recording material discharged from the transfer position
Since the distance to the tip of the material 2 is short, many charges are in the form of a plate.
Dielectric at the transfer position side tip of the member, further layered by electrostatic force
Prevents the recording material from sticking to the intermediate transfer belt
Can be However, too much extension length l _TwoShorten
When set, the discharged recording material contacts the guide member 1.
Instead of directly contacting the tip of the plate member 2,
Since the accumulated electric charge is discharged at once, it is recorded by the influence
Of course, the toner image held on the
The tip of the recording material is caught on the tip of the plate member 2 and
Material conveyance failure occurs. In addition, the influence of gravity, etc.
The recording material discharged from
The transfer roll is sandwiched between the transfer roll and the plate
There is a possibility that problems such as entanglement may occur.

Therefore, the extension length l ₂ is set in consideration of the distance l ₁ , the angle β, the electrical characteristics of the recording material, and the like. In consideration of the progress toward the leading end of the plate-like member 2, the straight line connecting the transfer position and the leading end of the plate-like member 2 is entirely formed by the guide member 1 as shown by the arrow in FIG. It is preferable to design so as to be shielded.
In the present embodiment has set this extension設長of l ₂ to 3 mm.

FIG. 3 shows the overall configuration of an image forming apparatus to which the recording material peeling apparatus according to the present embodiment is applied. The configuration of the image forming apparatus includes a photosensitive drum 100 that holds a toner image, an image forming unit 110 that forms a toner image on the photosensitive drum 100 by an electrophotographic method, and a toner that is formed on the photosensitive drum 100. A primary transfer device 120 that transfers an image onto the intermediate transfer belt 130, an intermediate transfer belt 130 that holds a primary-transferred toner image,
A secondary transfer device 140 for secondary-transferring the toner image held on the intermediate transfer belt 130 to a recording material conveyed at a predetermined timing, and fusing and fixing the secondary-transferred toner image by the action of pressure and heat Fixing device 15 to make permanent image
0, a recording material transport device that discharges the recording material from the recording material tray through a secondary transfer device 140 and a fixing device 150 at a predetermined timing.

In this embodiment, the image bearing member includes a photosensitive drum 100 and an intermediate transfer belt 130.
These are made of known materials. For example,
The intermediate transfer belt 130 is formed such that a volume resistivity is 10 ⁶ to 10 ¹⁵ Ω · cm by adding an appropriate amount of carbon black or the like to a resin such as polyimide, polycarbonate, polyester, polypropylene, or polyethylene terephthalate or various rubbers. , And its thickness is set to 0.1 mm.

The image forming section 110 includes a charger 111 for uniformly charging the surface of the photosensitive drum, an exposing device 112 for exposing the charged surface of the photosensitive drum to form an electrostatic latent image,
A developing device 113 for attaching a toner to the formed electrostatic latent image to form a visible image; a photoconductor cleaning device 114 for cleaning toner remaining on the photoconductor drum surface without being transferred by the primary transfer device 120; Things.

The secondary transfer device 140 is used for the intermediate transfer belt 1
The transfer roller 141 transfers the toner image transferred to the recording material 30 onto a recording material conveyed at a predetermined timing. The transfer roller 141 includes a transfer roll 141 and a backup roll 142 that face each other with the intermediate transfer belt 130 interposed therebetween. A power supply roll 1 is provided on the roll to promote the transfer of the toner image.
A charge is applied by 43.

In this embodiment, the transfer roll 141 is
It has a triple structure comprising a core layer, a skin layer, and a coating layer from the center to the outer periphery. Each of the core layers is made of metal, and the skin layer around the core layer is a carbon black dispersed and foamed EPDM (ethylene propylene diene rubber). ) Material, and the surrounding coating layer is made of a fluorocarbon resin material in which carbon black is dispersed.
At this time, the volume resistivity between the core layer and the coating layer is 10
^The roll hardness is ⁴ Ω · cm to 10 ⁶ Ω · cm, and the roll hardness is 20 ° to 45 ° in Asuka C hardness. Further, a cleaning blade made of urethane rubber is pressed against the transfer roll 141 at a predetermined pressure in order to clean a small amount of toner offset on the surface thereof.

The backup roll comprises a metal core layer and an EPDM layer from the center toward the outer periphery, and the EPDM layer further comprises an inner foamed elastic layer and an outer conductive layer. Here, the conductive layer is a semiconductive EPDM in which carbon black is dispersed at 15 to 35 wet%.
It is composed of foamed rubber and has a thickness of 0.5 to 1.5
mm, and the surface resistivity is specified to be 10 ⁷ to 10 ¹⁰ Ω / □.

The fixing device 150 comprises a pair of rolls each having a heat source therein and being pressed against each other at a predetermined pressure. Further, the recording material transport device includes a pickup roll 16 for taking out recording materials one by one from a recording material tray.
1. a transport roll 162 for transporting the removed recording material;
A registration roll (not shown) for transporting the recording material to the secondary transfer position in accordance with the transfer timing;
And a recording material transport belt 163 for transporting the recording material to the fixing device 150.

Next, the operation of forming a full-color image by the image forming apparatus according to the present embodiment will be described.
First, the photoconductor 1 uniformly charged by the charger 111
An electrostatic latent image corresponding to each color of black, yellow, magenta, and Sian is exposed to a laser by the exposure unit 112 on the surface of the surface 00, and a toner image is formed by the development unit 113 corresponding to each. For example, when an electrostatic latent image corresponding to black is formed, toner is adhered to the electrostatic latent image by the developing unit 113 (Bk) for black to form a toner image (visible image). This toner image follows the rotation of the photoconductor 100 and reaches the primary transfer position. Here, by applying a voltage having a polarity opposite to that of the belt-shaped member 2 of the toner by the primary transfer device 120 with the intermediate transfer belt 130 interposed therebetween, the toner image on the photoreceptor 100 is electrostatically electrostatically applied to the intermediate transfer belt. Transferred to 130. By repeating this process while measuring the primary transfer timing for each color of yellow, magenta, and cyan, a full-color toner image is formed on the intermediate transfer belt 130 by four color toner images. The transfer roll 141 and the cleaning device 170 are separated from the intermediate transfer belt 130 until the toner images of all colors are primarily transferred onto the intermediate transfer belt 130.

The full-color toner image is transferred to the intermediate transfer belt 1
Following the rotation of 30 rotations, it reaches the secondary transfer position. In synchronization with this timing, the recording material held by the registration roll (not shown) is also conveyed to the secondary transfer position. At this secondary transfer position, the transfer roll 141 and the backup roll 142 sandwich the intermediate transfer belt 130, the toner image, and the recording material, and a voltage having the same polarity as that of the toner strip member 2 is applied from the power supply roll 143. Because
A voltage having a polarity opposite to that of the toner band-shaped member 2 is generated on the transfer roll 141 forming the opposed plate-shaped member 2, and the toner image on the intermediate transfer belt 130 is secondarily transferred to a recording material by electrostatic force. .

At this time, it is assumed that the recording material to which the toner image has been secondarily transferred is, for example, positively charged as a whole. Plate member 2
Because it is grounded, the negative charge is dielectric when the recording material is positively charged approaches, this negative charge portion near the recording material, that is to focus on P ₁ parts shown in FIG. 2 (b) Becomes An attractive force is applied between the charged recording material and the induced electric charge by electrostatic force, and the recording material discharged from the transfer position is attracted to the plate member 2 side, causing a conveyance failure such as sticking to the intermediate transfer belt 130. Can be prevented. In addition,
The same applies when the polarity of the recording material is reversed.

Further, since the guide member 1 tip is long l ₂ extends to the plate-like member 2, a recording material discharged from the transfer position the plate-like member 2, particularly in its Figure 2 (b) P
Attracted towards _one part. That is, the recording material is attracted to the range in the direction of the two arrows shown in FIG. Therefore, the recording material is always conveyed while being blocked by the guide member 1, and the recording material is caught by the plate member 2, between the guide member 1, the tip of the plate member 2, and the transfer roll 141. Transport failures such as pinching can also be prevented.

Further, since the surface of the recording material contacting, including the extended portion, is constituted by the insulating or semiconductive guide member 1, the charged recording material discharged from the transfer position is guided by the guide. Since no rapid discharge occurs even when the recording material comes into contact with the member 1, the unfixed toner image held by the recording material is not disturbed.

Thereafter, the toner image secondarily transferred to the recording material is conveyed to the fixing device 4 by the recording material conveying belt 54 while being held on the surface of the recording material, and passes through the nip portion of a pair of fixing rolls. The toner is melted by the action of the pressure and heat to form a permanent image, and the recording material holding the permanent image is discharged to complete image formation.

In this embodiment, the full-color image forming apparatus using the drum-shaped photosensitive member 100 and the belt-shaped intermediate transfer belt 130 has been described. However, the present invention is not limited to this. The present invention can also be applied to a device using a belt-shaped photosensitive member or a drum-shaped intermediate transfer member, a device using no intermediate transfer member, and a monochrome device.

Embodiment 2 The recording material peeling apparatus according to the present embodiment relates to an improvement of the recording material peeling apparatus according to the first embodiment. A portion of the tip of the member 2 that does not contact the guide member 1 is covered with an insulating or semiconductive cover member 3. FIG.
FIG. 5A shows the overall configuration of the recording material peeling apparatus according to the present embodiment, and FIG. 5A shows the guide member 1, the plate member 2, and the cover member 3 from different viewpoints. . FIG. 5B shows the details of the periphery of the guide member 1 and the tip of the plate member 2 from the transfer position. In addition,
The same components as those of the recording material peeling apparatus according to the first embodiment are denoted by the same reference numerals.

The cover member 3 may be made of the same material as that of the guide member 1, or may be made of a different material. The resistance value is from 10 ¹² to ∞
(Completely insulated) It is preferable that the resistance is about Ω.

The operation of the recording material peeling apparatus according to this embodiment will be described. Since the plate-like member 2 is grounded, when a charged recording material approaches, electric charges of opposite polarity are induced. Here, in this embodiment, since the portion of the plate member 2 that does not contact the cover member 3 is covered by the insulating or semi-insulating cover member 3, the covered portion of the plate member 2 Is less affected by the charged recording material,
The uncovered part will have relatively more effect. Further, as in the case of the first embodiment, a portion near the recording material is affected by the charged recording material. as a result,
So that the charges dielectric to P ₂ parts of Figure 5 of the plate-like member 2 (b) is concentrated. An attractive force by electrostatic force acts between the charged recording material and the dielectric charge, and the recording material discharged from the transfer position is attracted to the plate-like member 2 side, causing a conveyance failure such as sticking to the intermediate transfer belt 130. Can be prevented.

Further, since P ₂ parts of FIG contact with the guide member 1 in the present embodiment 5 (b), i.e. the upper electric charge dielectric on the plate-like member 2 is concentrated, an arrow shown in FIG. 5 (b) The guide member 1, the tip of the plate member 2, and the transfer roll 1 attract the recording material in the direction of
This makes it possible to more effectively prevent a conveyance failure such as being sandwiched between the first and second members 41.

Further, since the surface of the recording material contacting, including the extended portion, is constituted by the insulating or semiconductive guide member 1, the charged recording material discharged from the transfer position is not guided by the guide. Since no rapid discharge occurs even when the recording material comes into contact with the member 1, the unfixed toner image held by the recording material is not disturbed.

Embodiment 3 A recording material peeling apparatus according to this embodiment transfers a toner image formed on an image carrier by an electrophotographic process to a recording material conveyed at a predetermined timing at a transfer position.
In a recording material peeling device provided adjacent to a transfer position and on a downstream side in a recording material conveyance direction to promote the peeling of the recording material from the image carrier, the recording material peeling device is used for recording discharged from the transfer position. An insulating or semi-conductive guide member 1 with which a material comes into contact, and a conductive grounded plate member 2 provided in contact with the back surface of the guide member 1, wherein the plate member 2 is It has a low-resistance portion 21 having a lower electric resistance value than other portions of the plate-shaped member 2 on a surface that contacts the guide member 1.

FIG. 6 shows the entire configuration of the recording material peeling apparatus according to the present embodiment. The same reference numerals are given to the same components as those of the recording material peeling apparatus according to the first embodiment.

As shown in FIG. 7A, the low-resistance portion 21 may be provided over the entire surface of the plate member 2 in contact with the guide member 1, or as shown in FIG. 7B. The plate member 2 may be provided on a part of the surface in contact with the guide member 1 on the transfer position side. Further, the resistance value of the low-resistance portion 21 is set to be lower than that of other portions of the plate-shaped member 2 and is desirably a resistance value of about 0 to 10 ³ Ω. In this embodiment, the resistance is set to 10 ² Ω. Further, the low resistance portion 21 can be formed by plating one surface of the plate-shaped member 2, and the thickness of the low resistance portion 21 formed by the plating process is approximately 0.1 mm.

The operation of the recording material peeling apparatus according to this embodiment will be described. Since the plate-like member 2 is grounded, when a charged recording material approaches, electric charges of opposite polarity are induced. Here, in the present embodiment, since the low resistance portion 21 is provided on the surface of the plate-shaped member 2 which is in contact with the guide member 1, the dielectric charge concentrates on the resistance portion having a small resistance value.
Further, similarly to the first and second embodiments, the portion nearer to the recording material concentrates the electric charge which is dielectric. As a result, the dielectric charges concentrate on the portion P3 of the plate-like member 2 in FIGS. 7A and 7B. An attractive force is applied between the charged recording material and the induced electric charge by electrostatic force, and the recording material discharged from the transfer position is attracted to the plate member 2 side, causing a conveyance failure such as sticking to the intermediate transfer belt 130. Can be prevented. Since the electric charge is concentrated on the P3 portion which is a very small area, the electrostatic force is increased, and such a transport failure can be more effectively prevented.

In this embodiment, since the electric charge concentrated on the portion P3 in FIGS. 7A and 7B which comes into contact with the guide member 1, that is, on the upper side of the plate member 2, the plate member 2 The guide member 1, the tip of the plate member 2, and the transfer roll 1, where the recording material is attracted upward and the recording material is caught by the plate member
It is possible to prevent a conveyance failure such as being sandwiched between the sheet 41 and the recording medium 41. In addition, since the recording material is attracted to the upper side of the plate-like member 2, such a conveyance failure can be prevented without extending the guide member 1 as in the first embodiment. Further, since it is not necessary to extend the guide member 1, the plate member 2 can be configured to be closer to the transfer position, so that a large amount of electric charge is concentrated on the portion P3, and the recording material is transferred to the intermediate transfer belt. It is possible to more effectively prevent poor conveyance such as sticking to the surface 130.

Further, since the surface in contact with the recording material is constituted by the insulating or semiconductive guide member 1,
Even if the charged recording material discharged from the transfer position contacts the guide member 1, no abrupt discharge occurs, so that the unfixed toner image held by the recording material is not disturbed.

Embodiment 4 In addition to the configuration of the recording material peeling device according to the first embodiment, the recording material peeling device according to the present embodiment includes a power supply unit 4 for supplying a bias voltage for attracting the recording material to the plate member 2. The image area of the recording material discharged from the transfer position is
Determining unit 5 for determining the timing of contact with
The image area of the recording material is
The control unit 6 controls the power supply unit 4 so as to turn off the bias voltage supplied to the plate-shaped member 2 during the contact with the control unit 6.
And FIG. 8 shows the entire recording material peeling apparatus according to the present embodiment. The same components as those of the recording material peeling device according to the first embodiment are denoted by the same reference numerals.

The power supply section 4 applies a voltage to the plate-like member 2 for attracting a recording material to the plate-like member 2. In the figure, the power supply unit 4 may apply a DC voltage or may apply an AC voltage to a DC voltage. When a DC voltage is applied, if the voltage is too low, the problem of peeling failure occurs, which is not preferable. If the voltage is too high, the problem of image disturbance or leakage due to discharge is unpreferable.
It is desirable to apply a voltage of about V. In addition, when a biased AC voltage is applied, a problem of insufficient static elimination occurs at an extremely low frequency, which is not preferable, and a problem of image disorder occurs at an excessively high frequency. Thus, a frequency of about 500 to 1000 Hz is more preferable. It is desirable to apply a voltage having a frequency of about 600 Hz.

The judging section 5 judges the timing at which the image area of the recording material discharged from the transfer position comes into contact with the guide member 1. In an ordinary image forming apparatus, since various timings related to image formation are monitored by the main controller, the timing may be determined by the main controller. The image area refers to an area where an image can be actually formed by a toner image, which is slightly smaller than the size of the recording material.

The control section 6 controls the bias voltage supplied to the plate member 2 to be turned off while the image area of the recording material is in contact with the guide member 1 based on the judgment of the judgment section 5. Yes, it can be configured by a well-known analog circuit or the like.

FIG. 9 shows the operation of the power supply unit 4, the judgment unit 5, and the control unit 6 using a timing chart. First, in a state where the recording material discharged from the transfer position has not reached the guide member 1, that is, in a state from time 0 to T1, the power supply unit 4 applies a reverse voltage to the charged recording material to the plate member 2. Is applied. FIG. 10A shows the periphery of the recording material peeling device in this state. Next, at time T1, at the timing when the leading end of the recording material in the transport direction reaches the guide member 1, the determination unit 5 sends the signal to the control unit 6, and the control unit 6 supplies the voltage applied from the power supply unit 4. Abort. From time T2 to T3, the image area of the recording material has reached the guide member 1. FIG. 10B shows the periphery of the recording material peeling device in this state. Further, at time T4
, The rear end in the conveying direction of the recording material leaves the guide member 1.

Thereafter, at a predetermined timing until the leading end of the next recording material in the conveying direction reaches the guide member 1, the controller 6
Starts the application of the voltage from the power supply unit 4. Stopping the voltage application at the timing when the leading end of the recording material in the transport direction before the leading end in the transport direction of the image area reaches the guide member 1 is performed after transmitting the command to stop the voltage application.
This is because it takes a certain time until the voltage actually reaches the initial value. For example, in this embodiment, the time required for the voltage to return to the initial value is set to 10 msec, and the leading end of the recording material in the conveying direction from the leading end of the image area to the guide member 1
Designed to be shorter than 15msec to reach
The image area reaches the guide member 1 after the voltage is reliably returned to the initial value.

In this embodiment, the recording material is the guide member 1.
However, the present invention is not limited to this, and the voltage application may be stopped at an arbitrary timing until the image area of the recording material reaches the guide member 1. It may be to cancel.

By peeling the recording material in this manner, a voltage having a polarity opposite to that of the recording material is applied to the plate member 2, so that the recording material discharged from the transfer position is positively attracted to the plate member 2. Thus, sticking to the intermediate transfer belt 130 can be more effectively prevented. In addition, since the control of stopping the application of the voltage is performed while the image area of the recording material reaches the guide member 1, the unfixed toner image held on the recording material by the applied voltage is disturbed by electrostatic force. And no image defects are caused.

[0053] Further, since the guide member 1 tip is long l ₂ extends to the plate-like member 2, a recording material discharged from the transfer position as in the case of the recording material separating apparatus of Example 1 The recording material is always conveyed so as to be blocked by the guide member 1, so that the recording material is caught on the plate member 2, or the guide member 1, the tip of the plate member 2, and the transfer roll 141.
Transport failure, such as being caught between them, can also be prevented.

Further, since the surface of the recording material contacting, including the extended portion, is constituted by the insulating or semiconductive guide member 1, the charged recording material discharged from the transfer position is guided by the guide. Since no rapid discharge occurs even when the recording material comes into contact with the member 1, the unfixed toner image held by the recording material is not disturbed.

It should be noted that in Examples 2 to 4, Example 1
The present invention can be applied to an image forming apparatus to which the recording material peeling device according to the above is applicable.

[0056]

As described above in detail, according to the first aspect of the present invention, since the leading end of the guide member extends toward the transfer position with respect to the plate member, the guide member is discharged from the transfer position. Even if the recording material is attracted toward the tip of the plate-shaped member, especially where the charges are concentrated, the recording material always contacts the guide member before reaching the plate-shaped member, and is conveyed along the guide member. It is unlikely to cause conveyance failure such as the material being caught on the plate member or being caught in the transfer roll. Also,
Since the recording material does not directly contact the conductive plate member 2, no rapid discharge occurs between the recording material and the plate member, and as a result, the unfixed toner image held on the recording material is removed. An image defect is less likely to occur without being disturbed by the sudden discharge.

According to the invention described in claim 2, according to claim 1
In addition to the effect of the invention described in (1), since the portion of the tip of the plate-shaped member that does not contact the guide member is covered with the insulating or semiconductive cover member, the tip of the plate-shaped member is concentrated at the transfer-position-side tip. The effect of the resulting dielectric charge is relatively remarkable in a portion not covered by the cover member, that is, in a portion in contact with the guide member, and the charged recording material is attracted to the portion in contact with the guide member by electrostatic force, and The transfer failure such as that the sheet advances to the lower portion of the plate member and is caught on the plate member, or is entangled in the transfer roll, is less likely to occur.

According to the third aspect of the present invention, by providing the low-resistance portion on the surface of the plate-shaped member that comes into contact with the guide member, it is possible to concentrate electric charges on that portion,
The charged recording material is more attracted to the guide member side, and it is possible to prevent a conveyance failure such as the recording material being caught on the plate-shaped member or entering between the plate-shaped member and the transfer roll. In addition, since such a conveyance failure can be prevented, the plate-shaped member can be brought closer to the transfer position side, and furthermore, the plate-shaped member is insulated by a small area called a low resistance portion at the transfer position side end. Since the charges can be concentrated, the charged recording material can be more effectively attracted to the plate-like member and the guide member side, and the conveyance failure such as the recording material sticking to the intermediate transfer member can be more effectively performed. Can be prevented.

According to the invention described in claim 4, claim 1 is provided.
In addition to the effects of the inventions described in the above, the recording material can be more positively attracted because it has a power supply unit for applying a voltage having a polarity opposite to that of the charged recording material to the plate-shaped member. Transporting defects such as being caught on the plate member 2 and being caught in the transfer roll are more unlikely to occur.
Further, when the image area of the recording material comes into contact with the guide member 1, the application of the voltage is controlled to be stopped, so that the unfixed toner held by the recording material is not disturbed by the influence of the applied voltage.

[Brief description of the drawings]

FIG. 1 illustrates an overall configuration of a recording material peeling apparatus according to a first embodiment.

FIG. 2 shows the configuration of the recording material peeling apparatus according to the first embodiment in more detail.

FIG. 3 illustrates an overall configuration of an image forming apparatus to which the recording material peeling apparatus according to the first embodiment can be applied.

FIG. 4 illustrates an overall configuration of a recording material peeling apparatus according to a second embodiment.

FIG. 5 shows the configuration of a recording material peeling apparatus according to a second embodiment in more detail.

FIG. 6 illustrates an overall configuration of a recording material peeling apparatus according to a third embodiment.

FIG. 7 shows the configuration of a recording material peeling apparatus according to a third embodiment in more detail.

FIG. 8 is a diagram illustrating an entire configuration of a recording material peeling apparatus according to a fourth embodiment.

FIG. 9 is a diagram for explaining the operation of the recording material peeling apparatus according to the fourth embodiment using a timing chart.

FIG. 10 is a diagram for explaining a voltage application on / off state of the recording material peeling apparatus according to the fourth embodiment.

FIG. 11 shows a configuration of an example of a conventional recording material peeling apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Guide member, 2 ... Plate member, 21 ... Low resistance part, 3 ...
Cover member, 4 ... Power supply section 4, 5 ... Determining section, 6 ... Control section

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kawahata Hata 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd. (72) Inventor Masaaki Takahashi 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd. 72) Inventor Takashi Kawabata 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd. (72) Inventor Makoto Ochiai 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd.

Claims (4)

[Claims] 1. After transferring a toner image formed on an image carrier by an electrophotographic process to a recording material conveyed at a predetermined timing at a transfer position, the recording material is urged to be separated from the image carrier. A recording material peeling device provided downstream of the recording material conveyance direction adjacent to the transfer position, the recording material peeling device comprising: an insulating or semiconductive guide member with which the recording material discharged from the transfer position contacts. And a conductive grounded plate member provided in contact with the back surface of the guide member, and the tip of the guide member extends toward the transfer position with respect to the plate member. A recording material peeling device characterized by the above-mentioned. 2. The recording material peeling device according to claim 1, wherein a portion of the tip of the plate-shaped member that does not contact the guide member is covered with an insulating or semiconductive cover member. 3. After the toner image formed on the image carrier by the electrophotographic process is transferred to the recording material conveyed at a predetermined timing at a transfer position, the recording material is urged to be separated from the image carrier. A recording material peeling device provided downstream of the recording material conveyance direction adjacent to the transfer position, the recording material peeling device comprising: an insulating or semiconductive guide member with which the recording material discharged from the transfer position contacts. And a conductive grounded plate-shaped member provided in contact with the back surface of the guide member, the surface of which the plate-shaped member is in contact with the guide member, compared to other portions of the plate-shaped member. A recording material peeling device having a low resistance portion having a low electric resistance value. A power supply unit for supplying a bias voltage for attracting the recording material to the plate member; a determining unit for determining a timing at which an image area of the recording material discharged from the transfer position contacts the guide member; A control unit that controls the power supply unit to turn off a bias voltage supplied to the plate member while the image area of the recording material is in contact with the guide member based on the determination of the unit. The recording material peeling device according to claim 1.