JP3483360B2 - Transfer device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device which can be used in an image forming apparatus such as a copying machine, a facsimile machine, a printer, and the like, and more specifically, it passes a transfer position facing an image carrier on which an image to be transferred is formed. The present invention relates to a transfer device including a transfer conveyance belt for supporting and conveying a transfer material, and an electrode that is in contact with the transfer conveyance belt and is electrically connected to another member.

[0002]

2. Description of the Related Art Conventionally, as a device for applying a bias to a transfer / transport belt used in a transfer device, a non-contact type corona transfer system has been used for the transfer / transport belt. According to this, there is a problem that ozone is generated by corona discharge.

As another charge applying method to the transfer / transport belt, a transfer method has been proposed in which an electrode is brought into contact with the transfer / transport belt to directly apply a bias. According to this contact application method, compared with the corona transfer method, there are advantages that the amount of ozone generated is small, the power source capacity is small, and the separation / conveyance performance of the transfer paper is good.

[0004]

Conventionally, as a transfer system in which an electrode as a charge supplying member is brought into contact with a transfer / conveying belt and a bias is directly applied to the transfer / conveying belt, for example, a roller-shaped electrode of the transfer / conveying belt is used. Those which are brought into contact with the surface opposite to the side facing the latent image carrier (for example, JP-A-5-113725 and JP-A-6-317).
990).

However, it has been found that when the electrodes are composed of a rotating body such as a roller as described above, various troubles are caused in connection between the rotating body and the high voltage power source. Further, according to the transfer belt device proposed in Japanese Patent Laid-Open No. 5-113725, in addition to the electrodes, the roller-shaped contact member is opposite to the side of the transfer / transport belt facing the latent image carrier. It is provided so as to come into contact with the surface, and the charge of the transfer conveyance belt is removed by this contact member, and the transfer current is controlled by detecting the current flowing into the transfer conveyance belt.
The charge injection of the transfer paper is suppressed on the upstream side of the nip between the transfer conveyance belt and the latent image carrier. Since this roller-shaped contact member was electrically connected to other members, it was found that various problems related to the connection occur as in the above.

FIG. 1 is an exploded view showing an example of a connecting portion between a bias roller 11 as a conventionally proposed charge supplying means and a high voltage power source (not shown). In this example, a slide bearing 22 is fixedly provided by a screw 21 on a leaf spring 20 that is provided so as to be connectable to a high-voltage power supply that is fixedly provided on the main body side, and the bias roller 1 is provided via the slide bearing 22.
1 is supplied with a voltage. In such a configuration, the bias roller shaft 11a and the slide bearing 2
Since it is difficult to maintain electrical continuity for a long period of time only by electrical continuity with 2, the convex portion 20a of the leaf spring 20 makes contact with another portion of the bias roller shaft 11a as a measure for maintaining electrical continuity. By doing so, electrical continuity is established at a plurality of points, or instead of using the sliding bearing 22, a ball bearing is provided and conductive grease is used in the ball bearing. However, even if the above measures are taken, it is not possible to completely prevent the abrasion of the sliding portion between the bias roller shaft and the bearing and the toner, the foreign matter, etc. adhering to the sliding portion. The connection part between 11 and the high-voltage power supply becomes a conduction failure part and electrostatic noise is generated, which causes malfunctions of the main body machine and noises to electronic devices installed in the vicinity.

In addition, the tension roller which stretches the transfer / conveyance belt is grounded (for example, Japanese Patent Laid-Open No. 2-11).
No. 0586) or a tension roller connected to a power supply controller (for example, Japanese Patent Laid-Open No. 3-23127).
No. 4) has been proposed, but in both cases, it was difficult to completely connect the sliding portion between the rotating body and the grounding member, the power supply controller or the like. Then, the incomplete sliding portion becomes a conduction failure portion, and a potential difference is generated between the rotation failure portion where the electric charge is transmitted through the conveyance transfer belt and the grounding member, the power supply controller, or the like. As a result, discharge is caused and becomes a source of electrostatic noise.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a transfer device having an electrode which is in contact with a transfer conveyance belt and electrically connected to other members. The purpose is to eliminate defects and prevent the generation of electrostatic noise, and at the same time reduce costs.

[0009]

In order to achieve the above object, a transfer device according to a first aspect of the present invention supports a transfer material so as to pass a transfer position facing an image carrier on which an image to be transferred is formed. In a transfer device including a transfer / transport belt for transporting the transfer transport belt and a plurality of electrodes in contact with the transfer / transport belt and electrically connected to other members, all of the electrodes are in contact with the transfer / transport belt. The belt is a fixing member fixedly provided at a position and extends in the width direction of the belt at different portions in the surface movement direction of the belt in the portion of the fixing member facing the transfer / conveying belt. It is characterized in that two ridges that come into contact with the surface of are formed. Here, being electrically connected to another member also includes the case of being grounded. In this transfer device, since the connecting portion between the electrode which is the fixing member and the other member electrically connected to each other does not move relative to each other, abrasion of the connecting portion with time or toner or foreign matter does not adhere to the inside of the connecting portion. . For this reason,
No contact failure occurs in the connection portion over time, and no electrical continuity failure occurs.

According to a second aspect of the present invention, the transfer device is provided with a tension roller for stretching the transfer conveyor belt, and the tension roller is electrically insulated from a member other than the transfer conveyor belt. It is characterized by. In this transfer device, the tension roller that is electrically insulated from members other than the transfer / transport belt is, for example, a metal roller or a rubber roller covered with conductive rubber.
Even when the electric charges supplied from the electrodes to the transfer / conveying belt are transmitted to the stretching roller, the electric charges are not discharged.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An example in which the present invention is applied to a transfer device of an image forming apparatus will be described below. FIG. 2 is a plan view of the transfer device. First, the configuration and operation of the entire transfer device will be described. The transfer device shown in FIG. 2 detachably supports the belt unit 2 with respect to the image forming apparatus main body. The belt unit 2 transfers the image to be transferred (developed image) from the drum-shaped photoconductor 3 as an image carrier onto a transfer sheet S as a transfer material, so that the belt unit 2 is wound around a pair of rollers 4 and 5. The transfer belt 6, the DC solenoid 8 for contacting and separating the belt 6 with respect to the photoconductor 3, the contact / separation lever 9, and the transfer bias applied to the surface of the transfer / transport belt 6 opposite to the photoconductor 3 side to transfer charges. A bias applying plate 18 as an electrode for supplying the electric charge and a contact plate 13 for removing electric charges of the transfer / conveying belt 6 are provided. Further, the high voltage power supply 12 for applying a voltage to the cleaning device 16 having the cleaning blade 16A for scraping off the residual toner and the paper waste of the transfer paper S adhering to the surface of the transfer / conveying belt 6 and the bias applying plate 18 is provided in the main body of the image forming apparatus. It is provided.

The roller 5 around which the transfer / conveyance belt 6 is wound has a gear connected to a drive motor (not shown) so as to be rotationally driven. The transfer / conveyance belt 6 is configured to be able to move in the transfer direction of the transfer sheet S at a transfer position facing the photoconductor 3 by following the rotation of the roller 5.

The rollers 4 and 5 are rotatably supported by a support 7. The support 7 is a member of the rollers 4 and 5 in the transfer paper conveyance direction indicated by the arrow A.
The support shaft 5a of the roller 5 located on the downstream side of the transfer position with respect to is movable as a fulcrum. This support 7
Is operated by a DC solenoid 8 driven on the transfer position side of the transfer / transport belt 6 by a signal from the control plate 8A. That is, the DC solenoid 8 has a contact / separation lever 9
Are connected to each other, and the contact / separation lever 9 moves the supporting member 7 to bring the transfer / conveying belt 6 into contact with / separate from the photosensitive member 3.

In the control plate 8A, the front end of the transfer sheet S conveyed while being aligned with the front end position of the image formed on the photoconductor 3 by the registration roller 10 which is the paper conveying means is the photoconductor. When approaching 3, the drive signal is issued to drive the DC solenoid 8. When the solenoid 8 is driven, the support 7 comes close to the photoconductor drum 3 and the transfer / conveying belt 6 comes into contact with the photoconductor 3, so that the transfer sheet S is placed at a position facing the photoconductor 3. A nip portion that can be conveyed while being in contact with the photoconductor 3 is formed.

Of the rollers 4 and 5, the roller 4 located on the side of the photoconductor 3 is configured as a driven roller for the roller 5 on the driving side. The surface shape of the roller 4 is such that both ends 4a, 4a are tapered in the axial direction to prevent the transfer / conveying belt 6 from being biased. is there.
On the other hand, the driving-side roller 5 is the transfer / conveying belt 6 during driving.
A material such as EPDM rubber, chloroprene rubber, or silicone rubber is selected from the function of enhancing the gripping force against.

The bias applying plate 18 is provided on the downstream side of the roller 4 in the moving direction of the transfer / conveying belt 6 so as to contact the inside of the transfer / conveying belt 6. The bias applying plate 18 constitutes a contact electrode for applying a charge having a polarity opposite to the charge polarity of the toner on the photoconductor 3 to the transfer / conveying belt 6, and is connected to the high voltage power source 12.

The contact plate 13 is disposed on the inner surface of the belt near the driven roller 4 on the lower side of the transfer / transport belt 6 which is not the transfer sheet transport surface, and injects charges into the transfer sheet S at the upstream side of the transfer nip. Is suppressed. The contact plate 13 is for detecting the current flowing on the transfer / conveying belt 6 as a feedback current, and the supply current from the bias applying plate 18 is controlled by the detection of this current.
For this reason, the transfer control plate 1 for setting the supply current to the bias applying plate 18 in the contact plate 13 according to the detected current.
4 is connected, and the transfer control plate 14 is connected to the high voltage power supply 12. Here, the bias applying plate 1
8 and the contact plate 13 will be described in detail later.

In the transfer device 1 having the above-described structure, as the transfer paper S is fed from the registration roller 10,
The support 7 is set at a position where the transfer / conveying belt 6 approaches the photoconductor 3 and forms a nip portion with the photoconductor 3.

On the other hand, the surface of the photosensitive member 3 is, for example, -8.
The toner is charged to 00V and moves to the nip portion with the toner positively charged on the surface being electrostatically adsorbed.
The photoconductor 3 is arranged in the vicinity of the photoconductor 3 before reaching the nip portion, and the surface potential of the photoconductor 3 is lowered by a pre-transfer charge eliminating lamp (PTL) 15 that weakens the charge on the surface of the photoconductor 3.

In the nip portion, the toner on the photoconductor 3 is transferred to the bias applying plate 1 located on the transfer conveying belt 6 side.
It is transferred onto the transfer paper S by the transfer bias applied from 8. This transfer bias is -1.5 kV to -6.5 kV.
The voltage is applied from the high-voltage power supply 12 in the range of V. This is when the current value output from the high-voltage power supply 12 is I1 and the feedback current value flowing from the contact plate 13 to the ground side via the transfer / conveying belt 6 is detected. When the value of is set to I2, the transfer bias is variably set as a result of constant current control between them.

When the image transfer from the photoconductor 3 is performed, the transfer paper S is also charged at the same time. Therefore, due to the relationship between the true charge of the transfer / transport belt 6 and the polarization charge generated on the transfer paper S side, the transfer paper S is electrostatically adsorbed on the transfer / transport belt 6 and separated from the photoconductor 3. Can be done.
Then, the transfer paper S, which utilizes the curvature separation of the photoconductor 3, is promoted by the peeling operation due to the strength of the waist of the transfer paper S itself.

On the other hand, the transfer paper S that has passed through the nip portion
Is electrostatically adsorbed according to the movement of the transfer / conveyance belt 6,
The drive-side roller 5 separates the curvatures.

The transfer sheet S separated from the transfer / conveying belt 6 by the driving-side roller 5 is guided by a guide plate and conveyed between the heating roller 17a and the pad roller 17b forming the fixing section 17. It In the fixing unit 17, the toner on the transfer sheet S is heated and melted and pressure-bonded to the transfer sheet S to fix the toner on the transfer sheet S.

In the transfer / conveying belt 6 on which the image transfer onto the transfer sheet S and the separation are completed, the contact / separation lever 9 is released in response to the excitation of the DC solenoid 8 being released, and the support 7 is removed from the photoreceptor 3. Be separated. Then, the cleaning device 16
Cleans the surface.

The cleaning device 16 is provided with a cleaning blade 16A, and by rubbing the transfer / conveyance belt 6, the toner transferred from the surface of the photoconductor 3 or scattered around the transfer / conveyance belt 6 without being transferred. The toner and the paper dust of the transfer paper S when the foreign matter adheres are scraped off. The toner or paper dust scraped off from the surface of the transfer / transport belt 6 is collected by the recovery screw 16
The toner is collected from the main body by B in a toner collecting container (not shown).

Next, the bias applying plate 18 and the contact plate 13 will be described. In the embodiment of the present invention, the bias applying plate 18 and the contact plate 13 are both made of a material such as a nickel-plated steel plate or a stainless steel plate, which is resistant to mechanical wear and has good electrical conductivity. ,
It is fixed inside the belt unit. With the above materials and installation, the structure can be made simpler and the cost can be reduced as compared with the case where a bias is applied to the transfer / conveyance belt 6 using a roller-shaped member.

Further, in the embodiment of the present invention, the only electrodes that are in contact with the transfer / transport belt and are electrically connected to other members are the bias applying plate 18 and the contact plate 13, and no ground is provided. Since the bias applying plate 18 and the contact plate 13 are fixed to the belt unit, as shown in FIG.
Connector 12 of cable connected to (not shown)
It can be directly connected to a. If the electrical connection of the contact plate 13 is performed in the same manner, the bias applying plate 18 and the electrical connection portions of the contact plate 13 and other members do not move relative to each other. With this configuration, the electrode rotating in contact with the transfer / conveying belt 6 as in the conventional proposal does not rotate the high-voltage power supply 1
In comparison with the case of connecting with 2, the abrasion of the connecting portion between the high-voltage power supply 12 and the bias applying plate 18 with time, and the adhesion of toner or foreign matter to the inside of the connecting portion are less likely to occur, resulting in poor electrical continuity due to poor contact. Since it is difficult to do so, it is possible to prevent the generation of electrostatic noise.

Further, the bias applying plate 18 or the contact plate 13
In the contact portion between the transfer belt and the transfer / conveyance belt, abrasion of the belt is liable to occur due to the sliding of the both, and the contact property is likely to decrease. Therefore, it is desirable to prevent this problem. If the contact pressure between the bias applying plate 18 or the contact plate 13 and the transfer / transport belt is increased or the contact area with the transfer / transport belt is increased in order to maintain the sliding pressure, the sliding load on the transfer / transport belt increases. . Therefore,
In the present embodiment, the portions where both the bias applying plate 18 and the contact plate 13 contact the transfer / conveying belt 6,
It is formed by two ridges extending in the width direction of the transfer / transport belt 6 so that the transfer / transport belt 6 contacts the bias applying plate 18 or the contact plate 13 at two places. With the above configuration, even if foreign matter such as belt scraps adheres to the protrusion portion that contacts the transfer conveyor belt on the upstream side in the conveying direction of the belt, the protrusion portion that contacts on the downstream side does not Since it is difficult for foreign matter to adhere, the contact property can be more reliably maintained as compared with the case where the bias applying plate 18 or the contact plate 13 comes into contact with the transfer / conveying belt at one place. Further, since the tips of the ridges formed on the bias applying plate 18 and the contact plate 13 are rounded so that the rounded tips come into contact with the transfer / transport belt, the transfer / transport belt 6 and the bias The sliding load with the application plate 18 or the contact plate 13 can be reduced. From the above, the transfer conveyance belt 6
With this, the contact property can be maintained without increasing the sliding load with the bias applying plate 18 or the contact plate 13 as much as possible.

As shown in FIG. 4, the shaft portions of the two rollers 4 and 5 around which the transfer / conveyance belt 6 is stretched only support the transfer / conveyance belt 6, and the casing on the apparatus main body side. It is placed so that it is not close to metal parts. In addition to this, if the gear 5b connected to the shaft portion of the roller 5 as a driving roller, the bearings of the rollers 4 and 5 provided on the support 7 and the like are made of a material such as a resin having a high insulating property, the roller 4 , 5 is a metal roller or a rubber roller covered with conductive rubber, the electric charge supplied from the bias applying plate 18 to the transfer / conveying belt is transmitted through the rollers 4 and 5 to the enclosure or metal member on the main body side. It is possible to prevent the discharge from becoming electrostatic noise. Further, even when the number of rollers around which the transfer / conveyance belt 6 is stretched is increased, all the rollers stretched around the transfer / conveyance belt 6 are transferred in the same manner as above.
The same effect as described above can be obtained by electrically insulating the other members.

[0030]

According to the transfer device of the first aspect of the invention, since the electrical connection portions of the electrodes and the other members do not move relative to each other,
It is possible to prevent generation of electrostatic noise due to poor electrical continuity without causing contact failure that causes poor electrical continuity in the connection portion over time. In addition, compared to the case where a member of a rotating body is used for the electrode, the structure can be simplified,
The cost can be reduced.

According to the transfer device of the second aspect, the tension roller that is electrically insulated from the members other than the transfer / conveying belt is made of metal, or is covered with a conductive rubber or the like. Therefore, even if the electric charge supplied from the electrodes to the transfer / transport belt is transmitted to the stretching roller, the electric charge supplied to the transfer / transport belt is not discharged. Can be prevented. Further, since it is not necessary to use conductive grease for the roller bearing to prevent the generation of noise or to provide an earth path for safety, it is possible to reduce the cost as compared with such a case.

[Brief description of drawings]

FIG. 1 is an exploded view of a power supply connection portion of a bias roller applicable to a conventionally proposed transfer device.

FIG. 2 is a schematic configuration diagram of a transfer device according to an embodiment of the invention.

FIG. 3 is a cutaway view of a belt unit applicable to the transfer device according to the embodiment of the invention.

FIG. 4 is a perspective view of the belt unit.

[Explanation of symbols]

2 Belt unit 3 photoconductor drum 4,5 roller 6 Transfer conveyor belt 12 High-voltage power supply 13 Contact plate 14 Transfer control plate 18 Bias application plate

─────────────────────────────────────────────────── ─── Continuation of front page (72) Koichi Ishii 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-5-333717 (JP, A) JP-A 7-140755 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/16

Claims (2)

(57) [Claims] 1. A transfer transport belt for supporting and transporting a transfer material so as to pass through a transfer position facing an image carrier on which an image to be transferred is formed, and another member in contact with the transfer transport belt. In a transfer device including a plurality of electrodes electrically connected to a transfer member, all of the electrodes are fixed members that are fixedly provided at positions that come into contact with the transfer transfer belt, and the transfer transfer of the fixed member is performed. 2. A transfer device, wherein two protrusions extending in the width direction of the belt and contacting the surface of the belt are formed at different portions in a surface movement direction of the belt in a portion facing the belt. 2. The transfer device is provided with a tension roller for stretching the transfer conveyance belt, and the tension roller is electrically insulated from a member other than the transfer conveyance belt. Transfer device 1.