JPH08166725A - Image forming device - Google Patents

Abstract

PURPOSE: To form a satisfactory image by providing a means for applying an electrical insulating liquid to one side of a transfer material prior to transfer to the transfer material, thereby suppressing paper powder on the transfer sheet from sticking to a toner image carrier in a transfer process. CONSTITUTION: The photoreceptor drum 1 of a copying machine A is rotated in the direction of the arrow (a) by a driving means, and its surface is uniformly electrified by an electrifier 2. In this electrifying area, image exposure is carried out by an exposure device 10 so as to correspond with the image of an original, so that an electrostatic latent image is formed. This latent image is developed by a developing device 3 to become a visible toner and it is moved to a transfer/separation charger 7. On the other hand, a transfer sheet 4 fed from a sheet feed part reaches timing rollers 50 and 6, and here it is fed into a transfer part in synchronism with the toner image on the drum 1. At this time, the toner image transfer side (surface) of the transfer sheet 4 is coated with the electrical insulating oil by means of a roller 50. Thus, since paper powder on the surface of the sheet is covered with this oil, sticking of the paper powder to the drum 1 is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
The present invention relates to an image forming apparatus such as a printer.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, the surface of an electrostatic latent image bearing member such as a photosensitive drum is charged by a charging device, and the charged area is exposed by an exposure device corresponding to an original image. The electrostatic latent image thus formed is developed by a developing device to form a visible toner image, the toner image is transferred onto a transfer material sent by the transfer device, and then fixed by the fixing device.

In a general monocolor image forming apparatus, the electrostatic latent image is developed on the electrostatic latent image carrier, and the developed visible toner image is transferred from the carrier to the transfer material. An intermediate transfer member may be used in a full-color image forming apparatus or the like. That is, for example, a cyan toner image is formed on the electrostatic latent image carrier, this is transferred to the intermediate transfer member, then a magenta toner image is formed on the electrostatic latent image carrier, and this is formed on the intermediate transfer member. Toner images of respective colors are sequentially formed such that they are transferred over the cyan toner image, and these toner images are sequentially transferred in multiplex onto an intermediate transfer member such as a drum type or a belt type. When a predetermined toner image is transferred onto the intermediate transfer body, the toner image on the intermediate transfer body is transferred onto the transfer material and fixed.

The toner remaining after the toner image on the electrostatic latent image carrier serving as the toner image carrier is transferred to the transfer material or the intermediate transfer medium is removed and cleaned by a cleaning device.
When the toner image on the intermediate transfer body is transferred to the transfer material, the residual toner there is also removed and cleaned by the cleaning device for the intermediate transfer body. As the transfer material, plain paper for copying machines, printers, etc. is usually used.

[0005]

However, when a transfer paper is used as the transfer material in the image forming apparatus described above, there is a problem associated with paper dust. That is, in the step of transferring the toner image to the transfer material, the transfer material is the electrostatic latent image carrier,
Alternatively, it is made to pass through a portion facing the toner image bearing member such as an intermediate transfer member, and at this time, the transfer device presses the transfer material against the toner image bearing member to perform pressure transfer, or electrostatically depending on its type. Transfer processing is performed by, for example, transferring a toner image from a toner image carrier to a transfer material, but in any case, the transfer material is brought into contact with the toner image carrier.

At this time, if the transfer material is a transfer paper, the paper powder adheres to the toner image carrier, and the filler contained in the adhered paper powder absorbs moisture in the air and becomes sticky. As a result, paper dust is filmed on the toner image carrier,
Further, paper dust is caught between the cleaning blade of the cleaning device and the toner image carrier to cause cleaning failure, or in an image forming apparatus having a toner recycling means, the paper dust enters the developing device and causes Agglomeration causes clogging of the developer amount control member in the developing device to generate white streak-shaped image noise, and even when such clogging of the developer does not occur, black spots on the background due to development by the agglomerated developer A problem such as occurrence of image noise occurs.

To solve this problem, the transfer condition is devised so as to suppress the adherence of the paper powder to the toner image carrier, or the paper powder collecting means is provided to the paper feed roller prior to the transfer paper entering the transfer portion. Provision has been made, for example, a flexible foamed synthetic resin member is brought into contact with the device, but at present, the effect is not satisfactory. Therefore, the present invention is an electrophotographic image forming apparatus, and in the case of using a transfer paper as a transfer material, it is possible to suppress the paper dust of the transfer paper from adhering to the toner image carrier in the transfer process. It is an object to provide a device that can form a high-quality image.

[0008]

In the electrophotographic image forming apparatus of the present invention which solves the above-mentioned problems, a toner image formed by developing an electrostatic latent image is transferred from a carrier of the toner image to a transfer material. Prior to this, a means for applying an electrically insulating liquid to at least one surface of the transfer material is provided.

The image forming apparatus according to the present invention focuses on the following mechanism in which paper dust adheres to the toner image carrier in the transfer process. a. When the toner image carrier and the transfer paper come into contact with each other, the paper dust on the paper surface is attached by a physical force. b. When the charged paper powder is generated as in the case where the transfer paper is charged and transferred, the charged paper powder is attached by an electric force.

In the present invention, it is intended to suppress the attachment of paper dust except for at least one of the causes of a and b. Examples of the application means of the electrically insulating liquid include the following. A roller for exclusive use of coating, which is arranged upstream of the transfer device in the transfer paper conveyance direction and is impregnated with an electrically insulating liquid or a paper feed roller or a paper passage. As such a paper feed roller, a timing roller impregnated with an electrically insulating liquid can be exemplified. At least the surface layer of these rollers is formed of a liquid impregnable material such as foamed synthetic resin (foamed polyurethane). A transfer device including a sheet having a liquid-impregnated material portion made of felt or the like and a tank for supplying an electrically insulating liquid to the sheet by, for example, inserting and immersing a part of the sheet in the transfer paper transport direction. The one that faces the paper passage at a position on the upstream side. In this case, the sheet may be flexible so as to have good contact with the transfer paper. A paper feed roller arranged upstream of the transfer device in the transfer paper transport direction, or a coating-only roller facing the paper passage,
A liquid application member that is in contact with the roller and is made of, for example, a flexible synthetic resin foam material, and a tank that supplies an electrically insulating liquid by, for example, inserting and immersing a part of the liquid application member in the member. It includes a rotary brush or a fixed brush for liquid application and a tank for supplying an electrically insulating liquid to the rotary brush or the fixed brush by, for example, immersing a part thereof, and the brush is transferred in the transfer paper conveyance direction. A device that faces the paper passage at a position upstream from the device.

The electrically insulating liquid may be any liquid that does not damage the transfer paper and does not hinder the transfer of the toner image to the transfer paper and the fixing of the transferred toner image. For example, it is generally used in a fixing device. In addition to the silicone oil for preventing the offset (for preventing the toner image from adhering to the fixing roller), fluorine oil or liquid paraffin can be used.
When using offset prevention oil such as silicone oil used in the fixing device, it may be possible to omit the offset prevention oil supply in the fixing device by appropriate application, depending on the amount of application etc. become. In this case, when the oil applied to the transfer paper passes through the fixing device, a part of the oil is transferred to the fixing roller.

The application of the electrically insulating liquid is performed on the toner image transfer surface of the transfer paper, the back surface thereof, or both surfaces thereof. In either case, the adhesion of paper powder to the toner image carrier can be suppressed as described below.

[0013]

According to the image forming apparatus of the present invention, the transfer paper sent to the toner image transfer portion enters into the transfer area and the toner image on the toner image carrier is transferred onto the transfer paper by the transfer device. Before passing through the electrically insulating liquid applying means, the electrically insulating liquid is applied to the toner image transfer surface or the back surface or both surfaces thereof by the applying means, and then the toner image is transferred and fixed.

When the electrically insulating liquid is applied to the toner image transfer surface, the paper powder is covered with the liquid film, so that the direct contact between the paper powder and the toner image carrier is suppressed, and that much paper powder remains. Transfer and adhesion to the toner image carrier is suppressed. Further, when the transfer device electrostatically transfers the toner image, when the charged paper powder is generated, it is prevented that the charged paper powder is attracted to the toner image carrier by an electric force. The transfer adhesion of the paper powder to the toner image carrier is suppressed.

When the electrically insulating liquid is applied to the back surface of the transfer paper (the surface on the transfer device side), the paper powder adhering to the back surface is covered with the liquid film to transfer the back paper powder to the transfer device member. Adhesion to (for example, a transfer roller) is suppressed, which in turn suppresses the adhesion of paper dust from the transfer device member to the toner image carrier after passing through the paper, thus suppressing the adhesion of paper dust to the toner image carrier as a whole. To be done.

Further, when the charged paper powder is generated on the back surface of the paper, it is suppressed that the charged paper powder adheres to the transfer device member by an electric force, and by extension, the toner from the transfer device member after passing the paper. Adhesion of paper powder to the image carrier is suppressed, and adhesion of paper powder to the toner image carrier is suppressed as a whole. Also,
When the electrically insulating liquid is applied to the back surface (the surface on the transfer device side) of the transfer paper in association with the paper dust adhesion suppressing effect, when the transfer device electrostatically transfers, for example, Where the transfer paper absorbs moisture during image formation in a moist environment, and unless the electrically insulating liquid is applied, the charge given from the transfer device leaks to the low potential side through the water molecules, causing transfer failure. By the application of the electrically insulating liquid, leakage of charges is suppressed, and transfer failure is suppressed accordingly.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a schematic structure of a copying machine A according to an embodiment of the present invention. The copying machine A includes a photosensitive drum 1, and a charging device 2, a developing device 3, and a developing device 3 around the photosensitive drum 1.
A transfer / separation charger 7 and a cleaning device 8 having a cleaning blade 81 are arranged in this order.

The transfer / separation charger 7 is of a corona discharge type, and includes a transfer charger 71 and a separation charger 7.
2, a paper feed roller pair (timing roller pair) 50, 6 is provided on one side, and a fixing roller device 9 is provided on the opposite side. An exposure device 10 is provided above the photosensitive drum 1. Timing roller pair 5
The transfer sheet 4 is fed to the sheets 0 and 6 from a sheet feeding unit (not shown) along a sheet passage.

The upper roller 50 of the timing roller pairs 50 and 6, that is, the roller 50 which comes into contact with the toner image transfer surface of the transfer sheet 4, has a surface layer portion 500 made of foamed polyurethane, to which a fixing device is attached. It is impregnated with the same electrically insulating oil used to prevent offsets. According to the copying machine A described above, the photosensitive drum 1 is rotated in the direction of the arrow a by the driving means (not shown), and the surface thereof is uniformly charged by the charging device 2.

Image exposure is performed on the charged area from the exposure device 10 in accordance with the original image to form an electrostatic latent image. This latent image is developed by the developing device 3 to become a visible toner image, and moves to a portion where the transfer / separation charger 7 is located. On the other hand, the transfer paper 4 delivered from a paper supply unit (not shown) arrives at the timing roller pair 50 and 6, and is delivered to the transfer site in synchronization with the toner image on the drum 1. At this time, the roller 5 is placed on the toner image transfer surface (front surface) of the transfer paper 4.
0 applies an electrically insulating oil.

On the transfer paper 4 that has entered the transfer portion, the toner image that has just arrived there is electrostatically transferred by the transfer charger portion 71 of the transfer / separation charger 7, and subsequently the photosensitive member is separated by the separation charger 72. It is separated from the drum 1 and conveyed to the fixing roller device 9, where the toner image is fixed,
The sheet is discharged to a sheet discharge tray by a sheet discharge roller (not shown). In the above-mentioned image formation, since the transfer paper 4 is coated with the electrically insulating oil by the timing roller 50, the paper dust on the paper surface is covered with this oil film, so that the paper dust comes into direct contact with the photosensitive drum 1. Is suppressed, and the adhesion of paper powder to the drum 1 is suppressed accordingly.

Further, even if charged paper powder is generated due to the action of the transfer charger section 71, the electrically insulating oil is applied to the transfer paper 4, so that the charged paper powder is caused by an electric force to the photoconductor. The transfer to the drum 1 is hindered, and also in this respect, the adhesion of paper dust to the photosensitive drum 1 is suppressed.
By suppressing the adhesion of the paper powder to the photoconductor drum 1 in this way, the filming of the paper powder on the photoconductor drum 1 which has been conventionally caused by the paper powder adhesion, the defective cleaning, the toner recycling. Developing device 3 when adopting means
Inconveniences such as clogging of the developer in the developer amount regulating section due to the mixing of paper powder into the developer are eliminated as compared with the conventional case, and a good image is formed accordingly. (Embodiment 2) FIG. 2 shows a schematic construction of a copying machine B according to another embodiment of the present invention.

In this copying machine B, the oil-impregnated roller 50 in the timing roller pair 50, 6 in the apparatus shown in FIG. 1 is replaced with a roller 5 for a normal timing roller,
An oil application device 20 is provided between the timing roller pairs 5 and 6 and the transfer / separation charger 7. The oil application device 20 exposes the flexible oil application sheet 201 made of felt to the paper path, supports the upper end of the sheet 201 in an oil tank 202, and dips it in an electrically insulating oil therein. It was done.
In other respects, the structure is the same as that of the copying machine A shown in FIG. 1, and the same parts are designated by the same reference numerals.

According to the copying machine B, an image is formed in the same manner as in the copying machine A, but in this copying machine B, before the toner image is transferred onto the transfer paper 4, the toner image transfer surface of the transfer paper 4 is transferred. Electrically insulating oil is applied to the oil applying sheet 201. By this oil application, the same effect of suppressing paper dust adhesion as in the case of applying oil to the transfer paper by the roller 50 in the copying machine A of FIG. 1 can be obtained. (Embodiment 3) FIG. 3 shows a schematic construction of a copying machine C which is still another embodiment of the present invention.

In the copying machine C, of the timing roller pairs 50 and 6 in the copying machine A of FIG. 1, the roller 50 is changed to a roller 5 for a normal timing roller, and the roller 5 is made of a flexible synthetic resin foam material ( Here, an oil application member 301 made of (generally called maltoprene)
Abutting against each other, and the end of this member 301 is
2 and was immersed in the electrically insulating oil therein. In this example, the member 301 and the tank 30
2, the roller 5 constitutes the oil applying device 30. In other respects, the structure is the same as that of the copying machine in FIG. 1, and the same parts are designated by the same reference numerals.

According to the copying machine C, an image is formed in the same manner as in the copying machine A, but the electrically insulating oil is applied to the upper roller 5 of the timing roller pair 5 and 6 by the oil applying member 301, and the roller 5 is rotated. The oil is applied to the toner image transfer surface of the transfer paper 4 sent by this roller with the rotation of. By this oil application, the same effect of suppressing paper dust adhesion as in the case of applying oil to the transfer paper by the roller 50 in the copying machine A of FIG. 1 can be obtained. (Embodiment 4) FIG. 4 shows still another embodiment of the present invention.

In the copying machine D of FIG. 4, the upper roller 50 of the timing roller pairs 50 and 6 in the copying machine A of FIG. 1 is changed to a roller 5 for a normal timing roller, and the roller pair 5 and 6 are transferred. The oil applicator 40 is provided between the charger 71 and the charger 71. Oil applicator 40
Is composed of a rotary brush 401 that is driven and rotated to apply oil facing the paper passage, and an oil tank 402 that contains electrically insulating oil. The rotary brush 401 is rotatably supported by the oil tank 402. The department is soaked in the oil in it.

The other points are the same as those of the copying machine A shown in FIG.
The same parts are designated by the same reference numerals. According to this copying machine D, an image is formed similarly to the copying machine A, but in this copying machine D, before the toner image is transferred onto the transfer paper 4,
Electrically insulating oil is applied to the toner image transfer surface of the transfer paper 4 by the brush 401.

By this oil application, the same effect of suppressing paper dust adhesion as in the case of applying oil to the transfer paper 4 by the roller 50 in the copying machine of FIG. 1 can be obtained. (Embodiment 5) FIG. 5 shows still another embodiment of the present invention. In the copying machine E of FIG. 5, the upper roller 50 of the timing roller pairs 50 and 6 in the copying machine A of FIG. 1 is changed to a roller 5 for a normal timing roller, and the roller pairs 5 and 6 and the transfer charger unit 71 are used. An oil applying device 50a is provided between the above and.

The oil applying device 50a is composed of a fixed brush 501 for applying oil facing the paper passage and an oil tank 502 containing electrically insulating oil. The fixed brush 501 is supported by the oil tank 502. The department is soaked in the oil in it. The other points are the same as those of the copying machine A in FIG. 1, and the same reference numerals are given to the same parts.

According to the copying machine E, an image is formed in the same manner as the copying machine A, but in this copying machine E, before the toner image is transferred onto the transfer paper 4, the toner image transfer surface of the transfer paper 4 is transferred. The electrically insulating oil is applied by the brush 501.
By applying this oil, the roller 50 in the copying machine of FIG.
The effect of suppressing the adherence of paper dust can be obtained as in the case of applying the oil to the transfer paper 4 by.

The electrically insulating oil used in the above-described embodiments is silicone oil generally used in fixing devices, but in addition to this, electrically insulating fluorinated oil and liquid paraffin oil are also used. it can.
In each of the copying machines shown in FIGS. 1 to 5, the transfer paper 4
Silicone oil (KF96-100 manufactured by Shin-Etsu Chemical Co., Ltd.), fluorine-based oil (Daiflor manufactured by Daikin Industries, Ltd.), and liquid paraffin (Cristol manufactured by Esso Oil Co., Ltd.) are used as electric insulating oils to be applied to
A copying machine of the same structure except that the amount of paper dust adhered to the photosensitive drum 1 after 1,000 sheets of paper for each oil is measured from the amount of paper dust collected by the cleaning device 8 and no oil application device is employed. Using 1000
Similarly, when the amount of paper dust adhered to the photoconductor drum 1 after passing the sheet was measured from the amount of paper dust collected in the cleaning device 8, the amount of paper dust adhered to the photoconductor drum 1 was determined as shown in FIG. No matter what type of oil is used in this copying machine, it is about 1/1 / th compared to the case where no oil is applied.
Reduced to 10.

Although the electrically insulating oil is applied only to the toner image transfer surface of the transfer paper 4 in the embodiment described above, it may be applied to the back surface of the transfer paper 4. If applied to the back surface, even if the transfer paper is likely to absorb moisture, such as when the humidity is high, leakage of charges applied to the transfer paper by the transfer charger 71 is suppressed, and transfer failure is suppressed accordingly.

Further, when the transfer device includes a member that comes into contact with the toner image carrier (here, the photosensitive drum 1) when the transfer paper does not pass, such as when the transfer charger roller or the pressure transfer roller is used, It has already been described in the section [Operation] that the adhesion of paper powder to the toner image carrier can be suppressed even if the electrically insulating oil is applied only to the back surface of the transfer paper 4.

[0035]

According to the present invention, when an electrophotographic image forming apparatus uses transfer paper as a transfer material,
It is possible to provide the one that can prevent the paper dust of the transfer paper from adhering to the toner image carrier in the transfer step, and can form a high quality image.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of another embodiment of the present invention.

FIG. 3 is a diagram showing a schematic configuration of still another embodiment of the present invention.

FIG. 4 is a diagram showing a schematic configuration of still another embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of still another embodiment of the present invention.

[Explanation of symbols]

A copy machine (image forming apparatus) 1 photoconductor drum 2 charging device 3 developing device 4 transfer paper 50 upper roller (electrically insulating liquid applying means) of timing roller pairs 50 and 6 500 oil impregnated surface layer 7 transfer / separation Charger 71 Transfer charger 72 Separation charger 8 Cleaning device 81 Cleaning blade 9 Fixing roller device B, C, D, E Copier (image forming device) 20 Oil applying device (electrically insulating liquid applying means) 201 Oil applying sheet 202 Electric insulating oil tank 30 Oil applying device 301 Oil applying member 302 Electric insulating oil tank 40, 50a Oil applying device (electric insulating liquid applying means) 401 Rotating brush 501 for oil applying Fixed brush 402, 502 for oil applying Electric insulating oil tank

Claims (1)

[Claims] 1. An electrophotographic image forming apparatus comprising:
A means for applying an electrically insulating liquid to at least one surface of the transfer material is provided prior to transferring the toner image formed by the development of the electrostatic latent image from the toner image carrier to the transfer material. Image forming apparatus.