JPH07325489A - Sheet electrifying device - Google Patents

Abstract

PURPOSE:To provide a sheet electrifying device applying a non-corona discharging system. CONSTITUTION:The electrifying belt 21 made of an acrylic resin material, is the meshlike belt in a grid shape provided with a number of pores and movably disposed below the photoreceptor drum at a specified space. On the electrifying belt 21, the transported paper sheet is placed on which the toner image is transferred by applying triboelectricity and transported to the fixing device side. The belt driving rollers 22 are the driving rollers for transporting and moving the electrifying belt 21, the rollers 22 are equipped freely rotatably on the upstream side and the downstream side of the photoreceptor drum 4 respectively by one. The friction air flow generating device 23 is disposed at the position approximately right below the photoreceptor drum on the inner surface side of the electrifying belt 21, the air flow is made to flow toward the inner surface side of the electrifying belt 21, and thus, the electric charge having a reversed polarity to that of the toner image is generated by the triboelectricity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet charging device used for charging a sheet when a toner image is transferred onto the sheet.

[0002]

2. Description of the Related Art Conventionally, in an electrostatic image forming apparatus such as a copying machine, in order to prevent generation of ozone when a toner image is transferred onto a sheet, the sheet is charged by using triboelectric charging instead of corona discharge. There is known a transfer device that charges a toner.

As a transfer device utilizing such triboelectric charging, there are JP-A-4-56882 and JP-A-4-9882.
8278. That is, in the configuration of the transfer device, when the toner image is transferred onto the paper, the back surface of the paper is frictionally engaged with the upstream side of the photosensitive drum with respect to the paper transport direction, and the back surface of the paper is frictionally charged. A brush is provided, and a bias having a polarity opposite to that of the toner image is applied to the brush to transfer the toner image to the sheet.

[0004]

However, the above-mentioned structure has a problem that the power consumption is weak.

In view of the above problems of the conventional transfer device, it is an object of the present invention to provide a sheet charging device of a non-corona discharge type which can be charged more reliably as compared with the prior art. .

[0006]

According to the present invention of claim 1, a placing member having a hole or a slit for placing a sheet and a gas flow to the placing member are provided. A sheet charging device comprising: a mounting member; and / or a gas flow generation unit that charges the sheet mounted on the mounting member.

The present invention according to claim 2 is the sheet charging device, wherein the placing member is a conveyor belt that passes through an image transfer portion for transferring an image onto the sheet.

[0008]

In the present invention, the mounting member has a hole or a slit for mounting the sheet, and the gas flow generating means generates a gas flow to the mounting member, whereby The placing member and / or the sheet placed on the placing member is charged.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially schematic sectional view for explaining the structure of a copying machine in which a sheet charging device according to an embodiment of the present invention is used as a transfer / conveyance device, and FIG. FIG. 3 is a perspective view for explaining the configuration of the transfer / conveyance device shown in FIG.

As shown in FIG. 1, in the copying machine main body 1, as in a conventional copying machine, a document image is exposed through an optical system 2, and a developing device 3 forms a toner image on a photosensitive drum 4. Is provided in the substantially central portion of the main body. Paper cassette 7
Is provided on the upstream side of the photoconductor drum 4 in order to store the transfer paper 8 in advance with reference to the paper transport direction. The transfer / conveyance device 5 is a device which is completely different from the conventional structure, and transfers the toner image onto the paper 8 by utilizing the triboelectrification by the air flow as the gas flow of the present invention. It is a means for transporting further downstream. The fixing device 6 is for fixing the toner image on the paper 8 on which the toner image conveyed from the transfer / conveyance device 5 is transferred. Here, the paper 8 corresponds to the sheet of the present invention.

Further, the structure of the transfer / conveyance device 5 will be described with reference to FIG. In the figure, a charging belt 21 as a mounting member of the present invention is a mesh belt formed of an acrylic resin material and having a large number of grid-like holes, and moves below the photosensitive drum 4. It is possible. A predetermined distance is maintained between the surface of the charging belt 21 and the surface of the photoconductor drum 4. The hole diameter of the grid is 1 mm or less, and the height of the grid is 1 mm or less. The charging belt 21 puts the paper 8 conveyed from the paper feeding cassette 7 on it, transfers the toner image using frictional charging, and fixes the fixing device 6 at the same time.
The width of the belt is substantially the same as the width of the photosensitive drum 4 in the axial direction. The belt driving roller 22 is a driving roller for conveying and moving the charging belt 21, and is provided rotatably one each on the upstream side and the downstream side of the photosensitive drum 4.

The friction air flow generating device 23 as the gas flow generating means of the present invention is disposed on the inner surface side of the charging belt 21 at a position substantially directly below the photosensitive drum 4, and the inner surface side of the charging belt 21. This is to generate an air flow toward and to generate an electric charge having a polarity opposite to that of the toner image by frictional charging. In this friction air flow generator 23, a jet guide chamber 23a for jetting air and a suction guide chamber 23b for sucking all or part of the air jetted from the jet guide chamber 23a are adjacent to each other. Is configured. Further, the suction guide chamber 23b can prevent the sheet 8 from floating from the surface of the charging belt 21 by the air jetted from the jet guide chamber 23a. These guide chambers 23a, 2
Since 3b has a shape that is substantially plane-symmetrical with respect to the adjacent surface, a further description will be given centering on the ejection guide chamber 23a.

The blowout guide chamber 23a is an elongated box-shaped member having a substantially pentagonal surface on the front side in the drawing, and a blower pipe 29 described later is connected to the surface. or,
On the side of the ejection guide chamber 23a facing the photoconductor drum 4, there is provided an ejection nozzle forming surface 24 having an inclination of a predetermined angle with respect to the inner surface of the charging belt 21 in the vicinity thereof. The air jet nozzle 24a is a jet nozzle forming surface 24.
Is a small hole formed in a large number on the surface of, and having a width corresponding to the width of the photoconductor drum 4, for blowing the air to the charging belt 21 vigorously.

Suction guide chamber 23 having an air suction function
On the b side, an air suction nozzle 25a is formed on the surface of the suction nozzle formation surface 25, and is used to return the air sucked from the air suction nozzle 25a into the suction guide chamber 23b to the blower device 28 described later. The suction pipe 30
It is provided on the front side surface in the drawing. The ejection nozzle formation surface 24 and the suction nozzle formation surface 25 are not in parallel relationship but face each other while maintaining a predetermined inclination angle.

On the other hand, the paper separating air suction device 26 is
The sheet 8 is disposed on the inner surface side of the charging belt 21 and at a predetermined distance from the inner surface portion of the charging belt 21 and is arranged on the downstream side of the friction air flow generator 23 by using the suction of the air. It is an elongated box-shaped member for separating from the drum 4. The separation air suction nozzle 27 is a large number of holes for suctioning the air, which are arranged in the sheet separation air suction device 26 facing the inner surface of the charging belt 21. The separation suction pipe 31 is a pipe whose end is connected to a middle portion of the suction pipe 30 and whose opposite end is connected to the front surface of the sheet separation air suction device 26 in the drawing.

Separation suction pipe 31 of suction pipe 30
In the portion closer to the blower 28 side than the connecting portion with
A filter (not shown) for removing dust and the like contained in the air is detachably provided.

The blower 28 is a blower fan (not shown).
And a drive motor (not shown) and the like, and an end of the suction pipe 30 is connected to the suction side and a blower pipe 29 is connected to the blowing side.

The operation of this embodiment having the above structure will be described with reference to FIG.

FIG. 3 is a partial schematic side view of the transfer / conveyance apparatus of this embodiment.

As shown in the figure, the paper 8 supplied from the upstream side in synchronization with the rotation of the photoconductor drum 4 on which the toner image is formed has its leading end at the lower part of the photoconductor drum 4. The sheet is placed on the charging belt 21, and while being controlled by the sheet conveying force from the upstream side, the sheet itself moves to the downstream side together with the charging belt 21 which is also conveying and moving. Charging belt 21
The sheet 8 that has been carried on and is conveyed over the friction air flow generator 23 in which the air flow is generated.
The air flow generated on the inner surface side of the charging belt 21 is in heavy contact with the surface of the charging belt 21. The negative polarity toner image formed on the surface of the photoconductor drum 4 is sequentially transferred to the surface of the sheet 8 by the positive polarity charge generated through the friction charging process and the like.

Further, the front end of the paper 8 on which the transfer is completed is
It moves along the surface of the photosensitive drum 4. And
When the leading edge of the sheet 8 reaches the vicinity of the sheet separating air suction device 26, the leading edge of the sheet 8 is peeled off from the surface of the photoconductor drum 4 by the suction force of the separation air suction nozzle 27. It The sheet 8 separated from the surface of the photoconductor drum 4 in this manner is conveyed further downstream while being placed on the charging belt 21, and is conveyed to the fixing device 6.

As described above, according to this embodiment, since corona discharge is not used, ozone is not generated during transfer, so that ozone generation in the entire copying machine can be reduced.
Further, since the corona discharge is not used and the bias voltage is not required, the high voltage power supply is not needed. Furthermore, since a filter is provided in the middle of the suction pipe 30,
The dust inside the copying machine body 1 can be collected and the dust can be prevented from being discharged to the outside of the copying machine body 1.

In the above embodiment, the case where the friction air flow generator 23 is arranged on the inner surface side of the charging belt 21 has been described. However, the present invention is not limited to this. For example, as shown in FIG. The airflow generation device may be arranged outside the charging belt so that the airflow strikes the charging belt from the outer surface side thereof. Figure 4
Then, components having the same functions as those in FIG. 2 are denoted by the same reference numerals.

In the above embodiment, the charging belt 21 is
The case where the sheet also has the function of the transport belt for transporting the sheet to the fixing device has been described, but the present invention is not limited to this and, for example, the sheet does not necessarily have the function of the transport belt.

In the above embodiment, the friction air flow generator 23 has the suction guide chamber 23b in addition to the ejection guide chamber 23a. However, the present invention is not limited to this. Of course you don't have to.

In the above embodiment, the charging belt 21 is
Although the case of using an acrylic resin material has been described, the present invention is not limited to this, and for example, a fluorocarbon resin such as Teflon or polycarbonate may be used.

In the above embodiment, the case where a large number of grid-like holes are formed in the charging belt 21 has been described, but the present invention is not limited to this. For example, slits may be formed in the charging belt, The shape and number of these holes or slits do not matter.

In the above embodiments, the case where paper is used as the sheet of the present invention has been described. However, the present invention is not limited to this. For example, a sheet made of a resin material or the like may be used.
The material is not limited as long as it is a sheet.

Further, in the above embodiment, the case where the sheet charging device of the present invention is applied to the transfer device of the copying machine has been described, but the present invention is not limited to this, and for example, in an electrostatic image forming device such as a facsimile or printer. It can be used for anything.

Further, in the above embodiment, the case where the sheet charging device of the present invention is applied to the transfer device of the copying machine has been described, but the sheet charging device is not limited to such an image forming device, and it is necessary to charge the sheet, for example. If so, it can be used.

[0032]

As is apparent from the above description,
INDUSTRIAL APPLICABILITY The present invention has an advantage of being able to provide a sheet charging device using a non-corona discharge method.

[Brief description of drawings]

FIG. 1 is a partial schematic cross-sectional view for explaining the configuration of a copying machine in which a sheet charging device according to an embodiment of the present invention is used as a transfer / conveyance device.

FIG. 2 is a perspective view for explaining the configuration of a transfer / conveyance device according to the present embodiment.

FIG. 3 is a side view schematically showing a part of the transfer / conveyance apparatus according to the present embodiment.

FIG. 4 is a side view for explaining the configuration of a transfer / conveyance device according to another embodiment.

[Explanation of symbols]

 1 Copier Main Body 2 Optical System 3 Developing Device 4 Photosensitive Drum 5 Transfer / Conveying Device 6 Fixing Device 7 Paper Feed Cassette 8 Paper 21 Charging Belt 22 Belt Driving Roller 23 Friction Air Flow Generator 23a Spouting Guide Chamber 23b Suction Guide Chamber 24 Jet Nozzle Forming Surface 24a Air Jet Nozzle 25 Suction Nozzle Forming Surface 25a Air Suction Nozzle 26 Paper Separation Air Suction Device 27 Separation Air Suction Nozzle 28 Blower 29 Suction Pipe 31 Suction Pipe 31 Separation Pipe

Claims (2)

[Claims] 1. A mounting member having a hole or a slit for mounting a sheet, and a gas flow is generated in the mounting member to cause the mounting member and / or the mounting member to move. A sheet charging device, comprising: a gas flow generation unit that charges the sheet placed on the sheet. 2. The sheet charging device according to claim 1, wherein the placing member is a conveyor belt that passes through an image transfer portion that transfers an image onto the sheet.