JP2005309190A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably transfer a transfer paper to an image carrier in a toner image transfer of an image forming apparatus, prevent the transfer paper from being separated from the image carrier by its own weight at the leading and trailing edges of the transfer paper, and prevent transfer failure. An image forming apparatus is provided.
A transfer unit that transfers a toner image to a transfer paper that receives a transfer of a toner image formed on an image carrier, and a transfer that transfers the transfer paper that has received a transfer of a toner image by the transfer unit to a fixing device. In the image forming apparatus provided with the means, a guide member for controlling the transfer path of the transfer paper with respect to the image carrier by airflow is installed in the transfer paper carry-in portion to the transfer means.
[Selection] Figure 2

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly, to an image forming apparatus that improves the adhesion of transfer paper to a photoconductor to enable good transfer.

Conventionally, in the case of an electrophotographic image forming apparatus, when an image formed on a photoconductor is transferred onto a transfer paper, the transfer process is performed by separating the leading or trailing edge of the transfer paper that has passed the transfer position from the transfer area. Does not work well, and the quality of the transferred image deteriorates (transfer failure, transfer omission, etc.).
On the other hand, in order to improve the adhesion between the photoconductor and the transfer paper and increase the conveying force of the transfer paper, the lifting mechanism unit engages with the transfer paper carried out from the photoconductor side and lifts the transfer paper to the photoconductor side. There has been proposed a method of providing a drive mechanism portion in which a member that contacts the transfer paper operates manually or automatically (see, for example, Patent Document 1).
In the conventional image forming apparatus, in order to avoid and solve this problem,
(1) By improving the positional accuracy of the guide member in the vicinity of the transfer position, the adhesion of the transfer paper to the intermediate transfer member or the image carrier is improved.
(2) An auxiliary guide function is provided so that the transfer paper does not abruptly separate (self-weight drop) from the guide member.
(3) The transfer voltage at the time of image formation is controlled by detecting the transfer area entry timing at the trailing edge of the transfer paper.
Such a method was used.
JP-A-10-221963

However, the technique described in Patent Document 1 does not consider stabilization of electrostatic attraction in order to ensure that the transfer paper is in close contact with the intermediate transfer member or the image carrier. Therefore, there is also a problem that there is a possibility that transfer sheet adsorption failure or the like may occur due to a change in the state of the transfer sheet due to environmental changes such as temperature and humidity.
On the other hand, in the case of the prior art as described above, the following problems occur with respect to transfer failure (transfer omission, etc.) that occurs when the leading edge or trailing edge of the transfer paper that has passed the transfer position is separated from the transfer area. It was. That is, in the method (1), in order to improve the position accuracy of the guide member in the vicinity of the transfer position, the part dimensional tolerance is reduced, the means for measuring the position accuracy with high accuracy, and the measuring means for arranging the measurement means in the vicinity of the measuring unit. Layout constraints, etc. are necessary and cannot be adequately addressed. In the method (2), it is difficult to drop the leading edge and trailing edge of the transfer paper uniformly in the ridge line direction. For example, when there is a minute curl or the like on the transfer paper, an appropriate auxiliary guide function that keeps the state when the leading or trailing edge of the transfer paper is separated from the transfer area cannot be secured. In the method (3), since the behavior of the leading edge and trailing edge of the transfer paper cannot be controlled, there is a limit to the corresponding range. In connection with the method (1) above, in order to improve the position accuracy of the guide member in the vicinity of the transfer position, means for reducing the component dimensional tolerance, measuring the position accuracy with high accuracy, and arranging the measurement means in the vicinity of the measurement unit Layout restrictions are required to make it happen.
Incidentally, the moisture content of the transfer paper changes due to changes in the environment such as temperature and humidity when the image forming apparatus is used, and the resistance value of the transfer paper decreases as the moisture content increases. When the resistance value is lowered, the charge applied to the transfer paper surface moves inside, and the transfer paper surface is not charged. For this reason, the stability of the adsorption of the transfer paper to the transfer drum is poor, and the transfer paper may not be adsorbed, resulting in poor image quality formed on the transfer paper.
Further, if the amount of charge is increased for attracting the transfer paper, it causes image deterioration when the toner image on the surface of the photosensitive drum is transferred to the transfer paper. Therefore, in order to obtain a high-quality image, it is not preferable to increase the charge amount of the transfer paper.
The present invention has been made in consideration of the above-described circumstances, and reliably attaches the transfer paper to the image carrier, preventing the transfer paper from being separated from the image carrier by the weight of the front and rear ends of the transfer paper, An object of the present invention is to provide an image forming apparatus capable of preventing transfer failure.
The image forming apparatus directly transfers the toner image on the photosensitive member as an image carrier onto the transfer paper, and once transfers the toner image on the photosensitive member to the intermediate transfer member, and then transfers the toner from the intermediate transfer member to the transfer paper. There is a method for transferring an image. The image carrier of the present invention includes both the photoreceptor and the intermediate transfer member.

In order to solve the above problems, the invention according to claim 1 is a transfer unit that transfers a toner image formed on an image carrier onto a transfer sheet, and a transfer that receives the transfer of the toner image by the transfer unit. An image forming apparatus including a conveyance unit configured to convey the paper to the fixing device, wherein a conveyance control unit that controls a conveyance path of the transfer paper with respect to the image carrier by an air current is installed in the transfer paper carrying unit to the transfer unit. Features.
According to a second aspect of the present invention, in the first aspect of the present invention, the conveyance control unit is configured to be directed toward a transfer inlet guide member disposed at an upper part and a lower part of the conveyance path and a transfer sheet passing through the conveyance path. An exhaust fan and a duct member for supplying a pressure or negative pressure airflow are provided.
According to a third aspect of the present invention, in the second aspect, the transfer inlet guide member has a hole for allowing the air flow to pass therethrough.
According to a fourth aspect of the present invention, in the first, second, or third aspect, a small amount of airflow is always generated by the exhaust fan during a time period in which power is supplied to the image forming apparatus.

  According to the present invention, airflow (suction or blowing) is applied from above the transfer paper to the vicinity of the transfer paper guide member provided at the upstream end of the transfer means for transferring the toner image formed on the image carrier to the transfer paper. Since the exhaust duct to be generated is provided and the exhaust fan communicating with the exhaust duct is provided outside, the transfer paper is securely attached to the transfer paper guide member, thereby improving the adhesion to the image carrier and the transfer paper tip It is possible to prevent transfer paper from being separated from the image carrier due to its own weight at the rear end, and to prevent transfer failure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. 2 and 3 are enlarged views of the main part.
There is a registration roller 13 on the upstream side of the image carrier 11 (upstream side in the transfer paper conveyance path), and there is a transfer function part (in this example, a transfer charger, which can be a transfer roller) 15 in the transfer part. There is a transfer paper transport belt 16 downstream of the transfer section. As shown in FIG. 2, an inlet piece 15-1 is formed at the upstream end of the transfer function unit 15, and a transfer sheet is transferred above the transfer piece (between the image carrier 11 and the transfer function unit 15). The transfer paper guide members 14 and 20 are provided to guide the light.
In the present invention, a transfer paper guide member 20 that guides the transfer paper to the transfer portion (between the image carrier 11 and the transfer function portion 15) is disposed above the transfer function portion 15. The transfer paper guide member 20 has a plurality of holes. An exhaust duct (duct member) 19 is provided above the transfer paper guide member 20. The exhaust duct 19 communicates with an exhaust fan 18 installed outside. When the exhaust fan 18 is driven to rotate, the exhaust duct 19 passes through a plurality of holes of the transfer paper guide member 20 from the opening of the exhaust duct 19 and passes through the upper surface of the transfer paper. Generate air flow that sucks or blows.
As a result, the transfer paper 12 is brought into close contact with the upper transfer paper guide member 20 (in the case of suction) or the lower transfer paper guide member 14 (in the case of spraying). When the transfer paper 12 is in close contact with the transfer paper guide member 20 or 14, the position of the front or rear end of the transfer paper is stabilized, and it is possible to ensure a transport behavior that can be in close contact with the photoreceptor.
That is, the present invention is characterized in that the conveyance control means A for controlling the conveyance path of the transfer paper to the image carrier 11 by the airflow is installed in the transfer paper carry-in portion to the transfer means 15.
Further, the conveyance control means A is an exhaust for supplying a positive or negative pressure airflow toward the transfer inlet guide members 20 and 14 respectively disposed at the upper and lower portions of the conveyance path and the transfer paper passing through the conveyance path. A fan 18 and a duct member 19.
The transfer paper 12 (see FIG. 1) is timed by the registration roller 13 and sent to the transfer section while being guided by the transfer paper guide members 14 and 20, and the toner on the image carrier 11 is operated by the transfer function section 15. The image is transferred. The transfer sheet after transfer is conveyed toward a fixing unit (not shown) by a transfer sheet conveyance belt 16.

In the present invention, in order to improve the adhesion between the transfer paper 12 and the image carrier 11 in the transfer portion and to increase the transfer efficiency, the exhaust fan 18 is rotationally driven to the transfer paper 12 in the transfer portion through the exhaust duct 19 from above. An air flow is generated, and the transfer paper 12 is sucked (in the case of a negative pressure air flow) or sprayed (in the case of a positive pressure air flow). The exhaust duct 19 determines the optimum shape by experimentally obtaining an opening width such that an air flow intensively strikes the transfer paper 12. Similarly, the shape, size, number, and the like of the plurality of holes arranged in the transfer paper guide member 20 are also experimentally determined to determine the optimum shape. The specification of the exhaust fan 18 is determined by experimentally obtaining an air volume for ensuring the adhesion of the transfer paper 12.
By providing a through-hole in the transfer paper guide member 20, it becomes possible to pass an appropriate air flow through the transfer paper, the position of the front or rear end of the transfer paper is stable, and a transport behavior that can be in close contact with the photosensitive member is achieved. Can be secured.
When the exhaust fan 18 is rotationally driven, specifically, for example, the timing at which the leading edge of the transfer paper 12 passes the registration roller 13 is detected by the sensor 17, and the exhaust fan 18 is rotationally driven at this timing. The timing at which the trailing edge of the transfer paper 12 passes through the transfer portion is detected by another sensor, and the driving of the exhaust fan 18 is stopped at this timing. Various known techniques can be adopted as the timing of driving and stopping of the exhaust fan 18.
As for the rotational drive of the exhaust fan 18, the passage timing of the transfer paper 12 is set so that a very small amount of airflow (suction or blowing) is always generated during the time period when the power is supplied to the image forming apparatus. It is possible to delete the sensor for detecting the error.
In this case, since a small amount of airflow is constantly generated, the suction amount from the exhaust duct 19 and the effect of making the exhaust amount constant can also be expected. Can keep.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows the relationship between the transfer paper guide of this invention, and an exhaust duct. FIG. 3 is a schematic perspective view of a transfer paper guide member of the image forming apparatus of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Image carrier (photosensitive body), 12 Transfer paper, 13 Registration roller, 14 Transfer entrance guide member 1, 15 Transfer function part (in this case, transfer charger), 15-1 Transfer function part entrance piece, 16 Transfer paper transport belt , 17 Paper transport detection sensor, 18 Exhaust fan, 19 Exhaust duct, 20 Transfer entrance guide member 2

Claims (4)

  An image forming apparatus comprising: a transfer unit that transfers a toner image formed on an image carrier onto a transfer sheet; and a transfer unit that transfers the transfer sheet on which the toner image has been transferred by the transfer unit to a fixing device. An image forming apparatus comprising: a transfer control unit configured to control a transfer path of the transfer paper with respect to the image carrier by an airflow in a transfer paper carrying unit to the transfer unit.   The transport control means includes a transfer inlet guide member disposed at each of an upper part and a lower part of the transport path, an exhaust fan and a duct member for supplying a positive or negative pressure airflow toward the transfer paper passing through the transport path, The image forming apparatus according to claim 1, further comprising:   The image forming apparatus according to claim 2, wherein the transfer inlet guide member has a hole for allowing the air flow to pass therethrough.   4. The image forming apparatus according to claim 1, wherein a small amount of airflow is always generated by an exhaust fan during a time period in which power is supplied to the image forming apparatus.

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