JPH0429257A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a recording paper from being soiled by toner by disposing a toner soil preventing cover for covering the upper surface of a guiding board for controlling the leading edge of the recording paper. CONSTITUTION:The guiding board 5 for controlling the leading edge of the recording paper is arranged nearly horizontally on the position close to a photosensitive drum 1 on a carrying path 4 so that the upper surface of the recording paper 8 may be bought into contact with the board, and the toner soil preventing cover 6 for covering the upper surface of the guiding board 5 for controlling the leading edge of the recording paper is arranged on the upper position of the guiding board 5 for controlling the leading edge of the recording paper while leaving a distance (d) with reference to the guiding board 5 for controlling the leading edge of the recording paper. Then, even in the case that the toner adhering on an image carrier 1 drops, the guiding board 5 for controlling the leading edge of the recording paper is prevented from being soiled by the toner. Thus, the recording paper 8 is prevented from being soiled by the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to image forming apparatuses such as electrophotographic printers such as laser printers, electrophotographic copying machines, and transfer type electrostatic recording printers.

[Prior Art] In a conventional laser printer, generally, as shown in FIG. attached to. Further, a transfer charger 13 is arranged at a transfer position around the photoreceptor drum 11, and the transfer charger 13 transports toner attached to the photoreceptor drum 11 to the transfer position. Copied on recording paper.

A conveying path 14 for guiding the recording paper to the transfer position is formed between the development position and the transfer position. The recording paper is fed from a paper feed section (not shown) onto the conveyance path 14 via the registration rollers 15, advances along the conveyance path 14 toward the photosensitive drum 11, and passes through the recording paper leading edge regulating guide plate] 6 and before transfer. The photoreceptor tram 11 is guided by rollers 17 onto the outer circumferential surface of the photoreceptor tram 11 and sent to the transfer position.

The recording paper leading edge regulating guide plate 16 is made of polyester film and is arranged on the conveying path 14 at a position closer to the photosensitive drum 11, and regulates the leading edge of the recording paper fed to the pre-transfer roller 17 and also controls the recording paper before transfer. To prevent transfer deviation due to bouncing of the trailing edge of the recording paper that occurs when the trailing edge of the recording paper passes through the roller 17.

[Problems to be Solved by the Invention] In the conventional laser printer described above, some of the toner adhering to the photosensitive drum 11 at the developing position falls onto the recording paper leading edge regulating guide plate 16, and the recording paper leading edge regulating guide plate 16 falls onto the recording paper leading edge regulating guide. Board 16
toner stains. Also, by charging the transfer charger 13, the recording paper leading edge adjustment guide plate 16 is positively charged.
The negatively charged toner adhering to the photosensitive drum 11 is attracted to the recording paper leading edge regulating guide plate 16 by electrostatic force, resulting in toner stains on the recording paper leading edge regulating guide plate 16.

In this way, if toner stains occur on the recording paper leading edge regulation guide plate 16, when the recording paper is guided to the recording paper leading edge regulation guide plate 16, the toner stains will appear on the recording paper, especially on the front edge of the recording paper. It comes alive.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can prevent old toner from forming on a guide plate for regulating the leading edge of recording paper, thereby preventing toner stains from forming on the recording paper.

[Means for Solving the Problems] A first image forming apparatus according to the present invention adjusts the leading edge of the recording paper so that the top surface of the recording paper comes into contact with the image carrier on the conveyance path that guides the recording paper to the transfer position. A guide plate is arranged, and a toner stain prevention cover that covers the upper surface of the recording paper leading edge regulating guide plate is arranged above the recording paper leading edge regulating guide plate at a distance from the recording paper leading edge regulating guide plate. It is characterized by

Image carriers include photoreceptors such as photoreceptor drums and photoreceptor belts used in electrophotographic printers and electrophotographic copying machines, and dielectric drums used in transfer electrostatic recording printers. For example, a polyester film is used as the guide plate for regulating the leading edge of the recording paper.

In the second image forming apparatus according to the present invention, a guide plate for regulating the leading edge of the recording paper is disposed near the image carrier on the conveyance path that guides the recording paper to the transfer position so that the top surface of the recording paper comes into contact with the leading edge of the recording paper. A toner stain prevention cover that covers the top surface of the recording paper leading edge regulating guide plate is arranged above the recording paper leading edge regulating guide plate at a distance from the recording paper leading edge regulating guide plate. The front end in the recording paper transport direction is located on the rear side in the recording paper transport direction from the front end of the toner stain prevention cover in the recording paper transport direction. For example, a polyester film is used as the guide plate for regulating the leading edge of the recording paper.

The distance in the longitudinal direction between the front end of the recording paper leading edge regulation guide plate in the recording paper transport direction and the front end of the toner stain prevention cover in the recording paper transport direction is the distance between the recording paper guided by the recording paper leading edge regulation guide plate and the toner stain prevention cover. It is preferable to set the value to a large value within a range where no contact occurs.

In the third image forming apparatus according to the present invention, a guide plate for regulating the leading edge of the recording paper is disposed near the image carrier on the conveyance path that guides the recording paper to the transfer position so that the top surface of the recording paper comes into contact with the leading edge of the recording paper. A toner stain prevention cover that covers the top surface of the recording paper leading edge regulating guide plate is placed above the recording paper leading edge regulating guide plate at a distance from the recording paper leading edge regulating guide plate. It is characterized by being made of a conductive material and being grounded. For example, a polyester film containing carbon is used as the guide plate for regulating the leading edge of the recording paper.

In the fourth image forming apparatus according to the present invention, a guide plate for regulating the leading edge of the recording paper is disposed near the image carrier on the conveyance path that guides the recording paper to the transfer position so that the top surface of the recording paper comes into contact with the leading edge of the recording paper. A toner stain prevention cover that covers the top surface of the recording paper leading edge regulating guide plate is arranged above the recording paper leading edge regulating guide plate at a distance from the recording paper leading edge regulating guide plate. The front end in the recording paper conveyance direction is located on the rear side in the recording paper conveyance direction from the front end in the recording paper conveyance direction of the toner stain prevention cover, and the guide plate for regulating the recording paper leading edge is made of a conductive material and is grounded. shall be. As the guide plate for regulating the leading edge of the recording paper, for example, a polyester film containing carbon is used.

The distance in the longitudinal direction between the front end of the recording paper leading edge regulation guide plate in the recording paper transport direction and the front end of the toner stain prevention cover in the recording paper transport direction is the distance between the recording paper guided by the recording paper leading edge regulation guide plate and the toner stain prevention cover. It is preferable to set the value to a large value within a range where no contact occurs.

[Operation of the Invention] In the first image forming apparatus according to the present invention, the toner that has fallen from the image carrier falls onto the toner stain prevention cover and is prevented from falling onto the recording paper leading edge regulating guide plate. Therefore, even if the toner adhering to the image carrier falls, only toner stains will not form on the guide plate for regulating the leading edge of the recording paper.

In the second image forming apparatus according to the present invention, the front end of the recording paper leading edge regulation guide plate in the recording paper transport direction is located at the rear end of the recording paper transport direction than the front end of the toner stain prevention cover in the recording paper transport direction. Toner falling from the carrier can be effectively prevented from adhering to the guide plate for regulating the leading edge of the recording paper.

In addition, since the distance between the image carrier and the recording paper leading edge regulating guide plate can be increased, the recording paper leading edge regulating guide plate is charged with a polarity opposite to that of the toner by the charge of the transfer charger. Even so, the toner attraction force due to electrostatic force is reduced, and the amount of toner adhering to the recording paper leading edge regulating guide plate based on electrostatic force is also reduced.

In the third image forming apparatus according to the present invention, toner that has fallen from the image carrier falls onto the toner stain prevention cover and is prevented from falling onto the recording paper leading edge regulating guide plate. In addition, since the guide plate for regulating the leading edge of the recording paper is made of a conductive material and is grounded, it is possible to prevent the guide plate for regulating the leading edge of the recording paper from being charged by the charging of the transfer charger. It is possible to effectively prevent toner from adhering to the guide plate for regulating the paper leading edge.

In the fourth image forming apparatus according to the present invention, the front end of the recording paper leading edge regulating guide plate in the recording paper conveyance direction is located rearward from the front end of the toner stain prevention cover, so that the toner falling from the image carrier is removed from the leading edge of the recording paper. Adhesion to the regulation guide plate can be effectively prevented.

In addition, since the guide plate for regulating the leading edge of the recording paper is made of a conductive material and is grounded, it is possible to prevent the guide plate for regulating the leading edge of the recording paper from being charged by the charging of the transfer charger. It is possible to effectively prevent toner from adhering to the guide plate for regulating the paper leading edge.

[Example] Hereinafter, an example in which the present invention is applied to a laser printer will be described with reference to FIGS. 1 to 5. In the following description, the front refers to the left side of FIG. 1, and the rear refers to the right side of FIG. 1, respectively.

1 and 2 show a first embodiment of the invention. A developing sleeve 2 is disposed at a developing position around the photosensitive drum 1, and the developing sleeve 2 causes toner to adhere to the photosensitive drum.

Further, a transfer charger 3 is arranged at a transfer position around the photoreceptor drum 1, and the transfer charger 3 transports toner adhering to the photoreceptor drum 1 to the transfer position. Copied on recording paper. The photosensitive drum 1 rotates at a constant speed in the direction of the arrow in FIG.

A conveyance path 4 is formed between the development position and the transfer position for conveying recording paper from a paper feed section (not shown) to the transfer position. At a position on the conveyance path 4 closer to the photoreceptor drum 1,
Guide plate 5 for adjusting the leading edge of the recording paper so that the top surface of the recording paper is in contact with the top surface of the recording paper.
are arranged almost horizontally. Recording paper leading edge regulation guide plate 5
is for adjusting the leading edge of the recording paper and feeding the recording paper to the transfer position. The width of the recording paper leading edge regulation guide plate 5 is formed to be larger than the width of the recording paper sent to the conveyance path 4.

At a position above the recording paper leading edge regulation guide plate 5, a toner stain prevention cover 6 that covers the upper surface of the recording paper leading edge regulation guide plate 5 is arranged at a distance d from the recording paper leading edge regulation guide plate 5. has been done. The interval d is set to, for example, 0.5 to 1.5■.

The guide plate 5 for regulating the leading edge of the recording paper and the toner stain prevention cover 6 are attached to a mounting member 7 supported by the frame of the printer (not shown). Recording paper leading edge regulation guide plate 5
The toner stain prevention cover 6 is made of, for example, a polyester film.

In this embodiment, the front end of the recording paper leading edge regulating guide plate 5,
It is flush with the front end of the toner stain prevention cover 6.

In the above-described configuration, when recording paper (indicated by a chain line 8 in FIG. 2) is fed from the paper feed section onto the conveyance path 4, the recording paper 8 is delivered to the photosensitive drum 1 along the conveyance path 4. The direction you are heading (
It advances in the direction shown by arrow B in FIG. 2) and enters between the conveyance path 4 and the recording paper leading edge regulating guide plate 5. Then, the upper surface of the recording paper 8 is guided by the lower surface of the front end of the recording paper leading edge regulating guide plate 5, and is brought along the outer peripheral surface of the photosensitive drum 1 to reach the transfer position. Therefore, the recording paper 8 is fed onto the surface of the photoreceptor drum 1 with its front end regulated. When the recording paper 8 is sent to the transfer position, the toner adhering to the photoreceptor tram 1 at the development position is transferred onto the recording paper 8 by the transfer charger 3.

In this embodiment, the toner stain prevention cover 6 is disposed above the recording paper leading edge regulating guide plate 5 at intervals, so that the toner that has fallen from the photoreceptor drum 1 is removed from the toner stain prevention cover 6. The guide plate for adjusting the leading edge of the recording paper 6
It will no longer fall upwards.

Therefore, even if toner adhering to the photosensitive drum 1 falls, toner stains on the recording paper leading edge regulating guide plate 5 can be prevented. Therefore, when the recording paper is guided to the recording paper leading edge regulating guide plate 5, it is possible to prevent toner stains from occurring on the recording paper.

FIG. 3 shows a second embodiment of the invention.

In FIG. 3, the same parts as in FIG. 2 are given the same reference numerals, and their explanations will be omitted.

In this embodiment, the front end of the recording paper leading edge regulating guide plate 5 is
This embodiment differs from the first embodiment in that it is located a distance meter distance behind the front end of the toner stain prevention cover 6.

The distance is set within a range in which the recording paper guided by the recording paper leading edge regulating guide plate 5 does not come into contact with the toner stain prevention cover 6. Preferably, the trailing edge of the recording paper is kept within a range where it does not come into contact with the toner stain prevention cover 6 due to the bounce of the trailing edge of the recording paper that occurs when the trailing edge of the recording paper passes the front end of the guide plate 5 for regulating the leading edge of the recording paper. For example, 0.5 to 2.
Set to 00. More preferably, the distance meter prevents the trailing edge of the recording paper from coming into contact with the toner stain prevention cover 6 due to bounce of the trailing edge of the recording paper that occurs when the trailing edge of the recording paper passes the front end of the recording paper leading edge regulating guide plate 5. Set to the largest possible value within the range.

In this embodiment, since the front end of the recording paper leading edge regulating guide plate 5 is located rearward from the front end of the toner stain prevention cover 6, toner falling from the photosensitive drum 1 is transferred to the recording paper leading edge regulating guide plate 5. It is possible to more effectively prevent the product from adhering to the surface.

Furthermore, since the distance between the photoreceptor drum 1 and the recording paper leading edge regulating guide plate 5 can be increased, the recording paper leading edge regulating guide plate 5 becomes polarized to the opposite polarity to the charged polarity of the toner by charging the transfer charger. Even if it is charged, the toner attraction force due to the charging decreases, and the amount of toner adhering to the recording paper leading edge regulating guide plate 5 based on the electrostatic force also decreases.

Therefore, when the recording paper is guided to the recording paper leading edge regulating guide plate 5, toner stains on the recording paper can be effectively prevented.

FIG. 4 shows a third embodiment of the invention.

In FIG. 4, the same parts as in FIG. 2 are given the same reference numerals, and their explanation will be omitted.

This embodiment differs from the first embodiment in that the guide plate 51 for regulating the leading edge of the recording paper is made of a conductive material such as carbon-containing polyester and is grounded.

In this embodiment, since the toner stain prevention cover 6 is disposed at a distance above the recording paper leading edge regulation guide plate 51, the toner falling from the photoconductor tram 1 is removed from the recording paper leading edge regulating guide plate 51. Adhesion to the plate 51 can be prevented.

Furthermore, since the recording paper leading edge regulating guide plate 51 is made of a conductive material and is grounded, it is possible to prevent the recording paper leading edge regulating guide plate 51 from being charged by the charging of the transfer charger, and to avoid electrostatic force. Accordingly, it is possible to effectively prevent toner from adhering to the guide plate 51 for regulating the leading edge of the recording paper.

Therefore, when the recording paper is guided to the pre-transfer recording paper guide plate 51, toner stains on the recording paper can be more effectively prevented.

FIG. 5 shows a fourth embodiment of the invention.

In FIG. 5, the same parts as in FIG. 2 are given the same reference numerals, and their explanations will be omitted.

In this embodiment, the front end of the recording paper leading edge regulating guide plate 51 is located behind the front end of the toner stain prevention cover 6, and the recording paper leading edge regulating guide plate 51 is made of a conductive material such as polyester containing carbon. This differs from the first embodiment in that it is made of metal and is grounded.

In this embodiment, since the front end of the recording paper leading edge regulating guide plate 51 is located behind the front end of the toner stain prevention cover 6, toner falling from the photosensitive drum 1 is transferred to the recording paper leading edge regulating guide plate 51. can effectively prevent adhesion to

Furthermore, since the recording paper leading edge regulating guide plate 51 is made of a conductive material and is grounded, it is possible to prevent the recording paper leading edge regulating guide plate 51 from being charged by the charging of the transfer charger, and to avoid electrostatic force. Accordingly, it is possible to prevent toner from adhering to the guide plate 51 for regulating the leading edge of the recording paper.

Therefore, 1. It is possible to very effectively prevent toner stains from forming on the recording paper when the recording paper is guided to the recording paper leading edge regulating guide plate 51.

In each of the above embodiments, the recording paper leading edge regulating guide plate 5.5
1 and the transfer position, a pre-transfer roller is provided close to the photoreceptor drum 1, and the recording paper guided by the recording paper leading edge regulating guide plate 5.51 is placed between the photoreceptor drum 1 and the pre-transfer roller. It may also be sent in between.

Further, in each of the above embodiments, the toner stain prevention cover 6
Aluminum may be deposited on the top surface of the device, and the aluminum deposited surface may be grounded. In this way, the toner stain prevention cover 6 is less likely to be charged, and it is possible to prevent toner from being absorbed from the surface of the photoreceptor drum 1 to the toner stain prevention cover 6 side due to electrostatic force. It is possible to more effectively prevent toner from adhering to the plates 5.51.

The present invention can also be applied to a laser printer that uses a photosensitive belt instead of the photosensitive drum 1.

Further, the present invention can be applied to image forming apparatuses other than laser printers, such as electrophotographic printers, electrophotographic copying machines, and transfer electrostatic recording printers.

[Effects of the Invention] In the first image forming apparatus according to the present invention, even if toner adhering to the image carrier falls, toner stains can be prevented from occurring on the recording paper leading edge regulating guide plate. Therefore, it is possible to prevent toner stains from occurring on the recording paper when the recording paper is guided to the recording paper leading edge regulating guide plate.

The second image forming apparatus according to the present invention can more effectively prevent toner falling from the image carrier from adhering to the guide plate for regulating the leading edge of the recording paper. Furthermore, even if the guide plate for regulating the leading edge of the recording paper is charged with the polarity opposite to that of the toner due to the charging of the transfer charger, the attraction force of the toner due to the electrostatic force is reduced, and the leading edge of the recording paper is adjusted based on the electrostatic force. The amount of toner adhering to the guide plate is also reduced. Therefore, it is possible to effectively prevent toner stains from occurring on the recording paper when the recording paper is guided to the recording paper leading edge regulating guide plate.

In the third image forming apparatus according to the present invention, it is possible to prevent toner falling from the image carrier from adhering to the recording paper leading edge regulating guide plate. Further, it is possible to prevent the recording paper leading edge regulating guide plate from being charged by the charging of the transfer charger, and it is possible to effectively prevent toner from adhering to the recording paper leading edge regulating guide plate due to electrostatic force. Therefore, it is possible to more effectively prevent toner stains from occurring on the recording paper when the recording paper is guided to the pre-transfer recording paper guide plate.

In the fourth image forming apparatus according to the present invention, it is possible to effectively prevent toner falling from the image carrier from adhering to the recording paper leading edge regulating guide plate. Further, it is possible to prevent the recording paper leading edge regulating guide plate from being charged by the charging of the transfer charger, and it is possible to prevent toner from adhering to the recording paper leading edge regulating guide plate due to electrostatic force. Therefore, it is possible to very effectively prevent toner stains from being generated on the recording paper when the recording paper is guided to the guide plate for regulating the leading edge of the recording paper.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, and FIG. 1 is a schematic diagram of the vicinity of a transfer position in a laser printer. FIG. 2 is an enlarged view of the main part of FIG. 1. FIG. 3 is a diagram corresponding to FIG. 2 showing a second embodiment of the invention. FIG. 4 is a diagram corresponding to FIG. 2 showing a third embodiment of the present invention. FIG. 5 is a diagram corresponding to FIG. 2 showing a fourth embodiment of the present invention. FIG. 6 shows a conventional example, and is a schematic diagram of the vicinity of a transfer position in a laser printer. 1... Photosensitive drum, 4... Conveyance path, 5.51...
-Guide plate for regulating the leading edge of recording paper, 6...Toner stain prevention cover or above

Claims (10)

[Claims] (1) A guide plate for regulating the leading edge of the recording paper is disposed near the image carrier on the conveyance path that guides the recording paper to the transfer position so that the top surface of the recording paper comes into contact with it, and above the guide plate for regulating the leading edge of the recording paper, An image forming apparatus in which a toner stain prevention cover is disposed at a distance from the recording paper leading edge regulating guide plate and covers the upper surface of the recording paper leading edge regulating guide plate. (2) The image forming apparatus according to claim 1, wherein the guide plate for regulating the leading edge of the recording paper is made of polyester film. (3) A guide plate for regulating the leading edge of the recording paper is arranged near the image carrier on the conveyance path that guides the recording paper to the transfer position so that the top surface of the recording paper comes into contact with the guide plate, and above the guide plate for regulating the leading edge of the recording paper, A toner stain prevention cover is placed at a distance from the recording paper leading edge regulating guide plate and covers the top surface of the recording paper leading edge regulating guide plate, and the front end of the recording paper leading edge regulating guide plate in the recording paper transport direction is contaminated with toner. The image forming apparatus is located on the rear side in the recording paper conveyance direction from the front end of the prevention cover in the recording paper conveyance direction. (4) The image forming apparatus according to claim 3, wherein the guide plate for regulating the leading edge of the recording paper is made of polyester film. (5) The distance in the longitudinal direction between the front end of the recording paper leading edge regulation guide plate in the recording paper transporting direction and the front end of the toner stain prevention cover in the recording paper transporting direction is such that the recording paper guided by the recording paper leading edge regulating guide plate is contaminated with toner. 4. The image forming apparatus according to claim 3, wherein the value is set to a large value within a range that does not contact the prevention cover. (6) A guide plate for regulating the leading edge of the recording paper is arranged near the image carrier on the conveyance path that guides the recording paper to the transfer position so that the top surface of the recording paper comes into contact with the guide plate, and above the guide plate for regulating the leading edge of the recording paper, A toner stain prevention cover that covers the top surface of the recording paper leading edge regulating guide plate is arranged at a distance from the recording paper leading edge regulating guide plate, and the recording paper leading edge regulating guide plate is made of a conductive material and is grounded. image forming device. (7) The image forming apparatus according to claim 6, wherein the guide plate for regulating the leading edge of the recording paper is made of a polyester film containing carbon. (8) A guide plate for regulating the leading edge of the recording paper is disposed near the image carrier on the conveyance path that guides the recording paper to the transfer position so that the top surface of the recording paper comes into contact with the guide plate. A toner stain prevention cover is placed at a distance from the recording paper leading edge regulating guide plate and covers the top surface of the recording paper leading edge regulating guide plate, and the front end of the recording paper leading edge regulating guide plate in the recording paper transport direction is contaminated with toner. An image forming apparatus, which is located on the rear side in the recording paper conveyance direction from the front end of the prevention cover in the recording paper conveyance direction, and has a recording paper leading edge regulation guide plate made of a conductive material and grounded. (9) The image forming apparatus according to claim 8, wherein the guide plate for regulating the leading edge of the recording paper is made of a polyester film containing carbon. (10) The distance in the longitudinal direction between the front end of the recording paper leading edge regulating guide plate in the recording paper conveying direction and the front end of the toner stain prevention cover in the recording paper conveying direction is such that the recording paper guided by the recording paper leading edge regulating guide plate is contaminated with toner. 9. The image forming apparatus according to claim 8, wherein the value is set to a large value within a range that does not contact the prevention cover.