JPH0651615A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To surely remove magnetic toner sticking to a transfer roller and an electrostatic charging roller. CONSTITUTION:A cleaning roller 16 constituted of a cylindrical rotary cylinder 18 having a smooth surface and a magnet 20 having a nearly C-shaped cross-section and housed inside the cylinder 18 is set so that it can rotate while abutting on the transfer roller 12. A discharged toner box 24 inside which magnetic toner is accumulated is set below the roller 16. The magnetic toner sticking to the roller 12 is attracted by the magnetic force of the magnet 20 and sticks to the surface of the cylinder 18. When the sticking magnetic toner reaches a part where the magnet 20 is not arranged in accordance with the rotation of the cylinder 18, it is separated from the surface of the cylinder 18 and drops to be accumulated in the box 24. The magnetic toner sticking to the roller 12 is surely removed regardless of the polarity of the magnetic toner and the ruggedness of the surface of the roller 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus having a contact type transfer roller and a charging roller, and more particularly to a cleaning mechanism for both rollers.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, an electrophotographic apparatus 130 provided with a contact type transfer roller and a charging roller is
A charging roller 142 that charges the photoconductor 140 to a set potential around the cylindrical photoconductor 140 having photoconductivity, an exposure mechanism 144 that irradiates the photoconductor 140 with light to form an electrostatic latent image, and a photoconductor. A developing mechanism 146 that supplies magnetic toner to 140 to form an electrostatic latent image into a visible image, and a transfer roller 148 that is rotated by contacting the photoconductor 140 by applying a predetermined voltage.
It has a schematic configuration with. This electrophotographic device 13
At 0, the photosensitive member 140 is first driven by a motor (not shown) and is rotated in the direction of the arrow, while the charging roller 142 charges the entire surface to the set potential. Subsequently, an electrostatic latent image is formed on the photoconductor 140 according to the irradiation of light from the exposure mechanism 144. Next, the developing mechanism 146 is formed on the electrostatic latent image.
Magnetic toner supplied from the toner adheres to form a visible toner image of the electrostatic latent image. Following this, from the cassette 158 for storing the recording paper 156 to the paper feed roller 15
The registration roller 160 supplies the recording paper 156 pulled out by 9 onto the transfer roller 148 at a predetermined timing. The recording paper 156 includes the photoconductor 140 and the transfer roller 1.
It is sandwiched by 48 and passes between them in accordance with the rotation of both. At this time, the magnetic toner on the photoconductor 140 is removed by the voltage applied to the transfer roller 148.
Since the Coulomb force acts in the direction of peeling from the toner image, the toner image is transferred to the recording paper 156. The recording paper 156 charged to a high potential with this transfer is discharged by the discharging brush 162, separated from the photoconductor 140, and then transferred to the fixing device 166 via the conveyance guide 164. Fixing device 1
66 heat-melts the unfixed toner on the recording paper 156 to fix it on the recording paper 156, and discharges the recording paper 156 to the paper discharge tray 168. After the toner image is transferred to the recording paper 156, the residual toner is removed by the cleaning mechanism 170 and the entire surface of the photoconductor 140 is neutralized by the optical neutralization mechanism 172. After that, the above steps are repeated again, and an image is recorded on a new recording paper 156.

In the above-mentioned electrophotographic apparatus, recording paper having a size smaller than the image forming area of the photoconductor is supplied,
If the recording paper is not normally supplied to the transfer roller due to paper jam or the like, the magnetic toner to be transferred onto the recording paper may adhere to the transfer roller. In such a case, the magnetic toner adhered to the transfer roller adheres to the next recording paper, and the back surface of the recording paper is contaminated, which has been a problem. Further, toner remaining on the photoconductor or toner floating in the electrophotographic apparatus may adhere to the charging roller, which may cause uneven charging of the photoconductor, which is a problem. Was there. As measures against such contamination of the transfer roller and the charging roller by the toner, means described in, for example, JP-A-51-9840, JP-A-2-272594 and JP-A-2-272589 have been proposed.

[0004]

However, even the countermeasures described in these publications have the following problems. That is, in the means disclosed in Japanese Patent Laid-Open No. 51-9840, a transfer bias having the same polarity as the toner image on the photoconductor is applied to the transfer roller when the recording paper is not interposed between the photoconductor and the transfer roller. , It is effective in preventing the transfer roller from becoming dirty due to the difference in the size of the recording paper, but with the reverse polarity toner that is usually included in the toner, it attracts the toner to the transfer roller, and contaminates the transfer roller. There was a case to do. In addition, JP-A-2-272
In the countermeasures described in Japanese Patent Laid-Open No. 594 and Japanese Patent Laid-Open No. 2-272589, a sponge material or a felt material is brought into contact with a transfer roller or a charging roller to remove toner or the like attached to the transfer roller or the charging roller. However, according to this method, it is difficult to remove the toner adhering to the concave portions when the surface of the transfer roller or the charging roller is even and smooth, and when the surface is irregular such as sponge-like rubber. In some cases, the toner adhering to the concave portions is re-transferred to the recording paper to contaminate the back surface of the recording paper or cause uneven charging.

The present invention has been made in order to solve the above-mentioned problems, and does not depend on the charging polarity of the magnetic toner, and even when the surface of the transfer roller or the charging roller has irregularities, the transfer roller or the charging roller is charged. An object of the present invention is to provide an electrophotographic apparatus capable of reliably removing magnetic toner attached to a roller.

[0006]

In order to solve the above problems, the electrophotographic apparatus of the present invention comprises a cylindrical photosensitive member which forms an electrostatic latent image on the surface thereof in response to light irradiation, and the above-mentioned formed photosensitive member. An electrophotographic apparatus comprising a transfer member for transferring a toner image, which is an electrostatic latent image visualized with magnetic toner, onto a recording sheet, and a charging member for charging the photoconductor to a set potential. At least one of the members is formed of a cylindrical roller, and a cleaning roller having a magnet that contacts the roller is provided.

[0007]

In the electrophotographic apparatus of the present invention having the above construction, the photosensitive member charged to the set potential by the charging member forms an electrostatic latent image on its surface in response to the irradiation of light. The transfer member transfers onto the recording paper a toner image in which the electrostatic latent image formed on the surface of the photoconductor is visualized with magnetic toner. A cleaning roller provided with a magnet comes into contact with a cylindrical roller that forms at least one of a transfer member and a charging member, and magnetic toner attached to the roller is separated by magnetic force and removed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) First, the construction of the main part of the electrophotographic apparatus 1 of this embodiment will be described with reference to FIGS. It should be noted that the other components are not shown because they are conventional examples.

In FIG. 1, at the second stage from the top of the drawing, a cylindrical photoconductor 10 having photoconductivity and driven by a motor (not shown) to rotate in the direction of arrow A is arranged. . When the photoconductor 10 is irradiated with light in a charged state, it can form an electrostatic latent image according to the irradiation. A transfer roller 12 as a transfer member of the present invention is disposed below the photoconductor 10 in contact with the photoconductor 10 and driven by a motor (not shown) to rotate in the direction of arrow B. The transfer roller 12 has a high-voltage power supply (not shown).
The magnetic toner can be attracted by the Coulomb force. Note that the recording paper 14 is the
It is possible for the contact portion between the transfer roller 12 and the transfer roller 12 to pass along the direction of arrow C according to the rotation of both. Further, below the transfer roller 12, a cleaning roller 16 that is in contact with the transfer roller 12 and that is driven by a motor (not shown) and rotates in the direction of arrow D is disposed. These photoconductors 1
0, the transfer roller 12 and the cleaning roller 16 have substantially the same width.

As shown in FIG. 2, the cleaning roller 1
6 is composed of a cylindrical rotary cylinder 18 made of silicone-based synthetic resin and having a smooth surface, and a magnet 20 having a substantially C-shaped cross section and housed and fixed inside the rotary cylinder 18. . The rotary cylinder 18 is in contact with the transfer roller 12 and can rotate. Further, the magnet 20 has a length that extends over substantially the entire width of the rotary cylinder 18, and is arranged along the inner circumference of the rotary cylinder 18. The upper end surface 20a of the magnet 20 is located slightly on the left side in the drawing from the vertical diameter of the rotary cylinder 18, and the lower end surface 20b is located slightly on the right side in the drawing from the vertical diameter. As a result, the magnet 20
Magnetic force can attract magnetic toner to the surface of the rotary cylinder 18 and cause the magnetic toner to adhere to the surface of the rotary cylinder 18, and when the magnetic toner adheres to a portion where the magnet 20 is not arranged according to the rotation of the rotary cylinder 18. In addition, the magnetic toner can be detached from the surface of the rotary cylinder 18.

Further, as shown in FIGS. 1 and 2, a blade 22 which contacts the cleaning roller 16 is provided below the cleaning roller 16 so that the magnetic toner separated from the cleaning roller 16 can be accumulated therein. A toner box 24 is installed. On the other hand, as shown in FIG. 1, above the photoconductor 10 in the figure, a charging roller 26 as a charging member of the present invention is in contact with the photoconductor 10 and is driven by a motor (not shown) to rotate in the direction of arrow E.
Are arranged. A bias from a high voltage power source (not shown) is applied to the charging roller 26, and the photosensitive member 1
The entire surface of the photoconductor 10 can be charged in accordance with the rotation of 0.

In the electrophotographic apparatus 1 having the above structure, when the photoconductor 10 charged to the set potential by the charging roller 26 is irradiated with light, an electrostatic latent image is formed on the surface of the photoconductor 10 in response to the irradiation. It is formed. Photoconductor 1 on which this electrostatic latent image is formed
The magnetic toner is supplied to 0 and the electrostatic latent image becomes a toner image. After that, when the recording paper 14 is supplied and passed between the photoconductor 10 and the transfer roller 12, the toner image on the photoconductor 10 is attracted to the transfer roller 12 side by the Coulomb force of the transfer roller 12 and transferred. Roller 12 and photoconductor 1
It is transferred onto the recording paper 14 which is interposed between the recording paper 14 and 0.

When the toner image is transferred, the recording paper 14
Is not appropriate or the recording paper 14 does not normally pass between the photoconductor 10 and the transfer roller 12 due to jamming or the like, the magnetic toner forming a toner image adheres to the transfer roller 12. . As shown in FIG. 2, the magnetic toner adhered to the transfer roller 12 moves downward in the drawing as the transfer roller 12 rotates and moves to the transfer roller 1.
2 to the contact portion between the cleaning roller 16 and the cleaning roller 16. Then, the magnetic toner is separated from the transfer roller 12 by the magnetic force of the magnet 20 contained in the cleaning roller 16 and adheres to the surface of the rotary cylinder 18. The magnetic toner attached to the rotary cylinder 18 moves downward in the drawing as the rotary cylinder 18 rotates. Since the magnet 20 is installed inside the right half of the rotary cylinder 18 in the drawing, when moving the half,
The magnetic toner acts on the magnetic force toward the substantially center of the rotary cylinder 18. Therefore, the magnetic toner continues to adhere to the surface of the rotary cylinder 18 during the movement of the half portion. However, since the magnet 20 is not installed from the lowermost part of the rotary cylinder 18 to the upper left part of the figure, the magnetic toner reaching this part is released from the magnetic force of the magnet 20 and naturally falls due to gravity, and the toner box is discharged. Collect in 24. Further, the magnetic toner attached to the surface of the rotary cylinder 18 without naturally dropping is
The blade 22 that abuts the rotary cylinder 18 causes the rotary cylinder 18 to move.
The magnetic toner is scraped off from the surface, and is accumulated in the discharged toner box 24 in the same manner as the magnetic toner that has naturally dropped. further,
When foreign matter such as paper dust adheres to the transfer roller 12, they are transferred from the transfer roller 12 to the rotary cylinder 18 together with the magnetic toner.
However, such foreign matter is also scraped off from the rotary cylinder 18 by the blade 22 together with the magnetic toner, and falls and accumulates in the discharged toner box 24.

In this way, the magnetic toner attached to the transfer roller 12 is peeled off by the magnetic force of the magnet 20 provided on the cleaning roller 16 that comes into contact with the transfer roller 12, so that it does not depend on the charging polarity of the magnetic toner, and Even if the surface of the transfer roller is uneven, the magnetic toner attached to the transfer roller can be reliably removed. (Second Embodiment) Next, a second embodiment will be described. As shown in FIG. 3, a cleaning roller 30 is arranged below the drawing roller in contact with the transfer roller 12 rotating in the arrow F direction. The cleaning roller 30 is composed of a magnet and rotates in the direction of arrow G. The surface of the cleaning roller 30 is coated with a silicone-based synthetic resin and is smooth. Further, below the cleaning roller 30 in the drawing, an exhaust toner box 34 having a blade 32 is arranged. The blade 32 is slightly on the left side in the drawing from the lowermost part of the cleaning roller 30 in the drawing, and its tip is in contact with the cleaning roller 30. Since the configuration other than the above is the same as that described in the first embodiment, the description thereof will be omitted.

As in the first embodiment, if the recording paper has a different size or the recording paper jams when the toner image is transferred, the magnetic toner forming the toner image adheres to the transfer roller 12. As shown in FIG. 3, this transfer roller 1
The magnetic toner attached to 2 moves downward in the drawing as the transfer roller 12 rotates and reaches the contact portion between the transfer roller 12 and the cleaning roller 30. Then, the magnetic toner is transferred to the transfer roller 1 by the magnetic force of the cleaning roller 30.
It is separated from 2 and adheres to the surface of the cleaning roller 30. The magnetic toner attached to the cleaning roller 30 moves downward in the drawing as the cleaning roller 30 rotates. The magnetic toner adhering to the surface of the cleaning roller 30 is scraped off from the surface of the cleaning roller 30 by the blade 32 and naturally falls, and is accumulated in the discharged toner box 34. Further, when foreign matter such as paper dust adheres to the transfer roller 12, they move from the transfer roller 12 to the surface of the cleaning roller 30 together with the magnetic toner, but such foreign matter also moves together with the magnetic toner by the blade 32 to the cleaning roller 30. It is scraped off from the surface of 30, and falls and accumulates in the discharged toner box 34.

In this way, the magnetic toner adhering to the transfer roller 12 is peeled off by the magnetic force of the magnet constituting the cleaning roller 30 contacting the transfer roller 12, so that it does not depend on the charging polarity of the magnetic toner, and moreover, the transfer roller. Even if there is unevenness on the surface, the magnetic toner attached to the transfer roller can be reliably removed.

In the above-mentioned first and second embodiments,
Although both the charging member and the transfer member are rollers, one may be a roller and the other may be, for example, a corotron or the like that utilizes discharge of a high-voltage current passing through a wire.
Further, in the above-described Embodiments 1 and 2, an example in which the cleaning roller is brought into contact with the transfer roller of the electrophotographic apparatus to remove the magnetic toner adhering to the transfer roller has been shown. If they are placed in contact with each other, the magnetic toner attached to the charging roller can be reliably removed.

Further, although the rotary cylinder made of silicone-based synthetic resin is used in the first embodiment, the material of the rotary cylinder is not limited to this, and any material which is non-magnetic and which can provide a smooth surface is used. Good. The same applies to the surface coating material of the cleaning roller in the second embodiment. However, in this case, it suffices if the surface of the cleaning roller is smooth, and coating of the surface is not essential.

[0019]

As is apparent from the above description, according to the electrophotographic apparatus of the present invention, the transfer is performed regardless of the charging polarity of the magnetic toner and even when the surface of the transfer roller or the charging roller has irregularities. The magnetic toner attached to the roller or the charging roller can be reliably removed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a main part of an electrophotographic apparatus according to a first exemplary embodiment.

FIG. 2 is a sectional view of the vicinity of a cleaning roller of the electrophotographic apparatus of Example 1.

FIG. 3 is a sectional view of the vicinity of a cleaning roller of the electrophotographic apparatus of Embodiment 2.

FIG. 4 is an explanatory diagram of a configuration of a conventional electrophotographic apparatus.

[Explanation of symbols]

1 ... Electrophotographic device, 10 ... Photoconductor, 12 ...
Transfer roller, 16, 30, cleaning roller, 2
0 ... Magnet, 26 ... Charging roller.

Claims (4)

[Claims] 1. A cylindrical photosensitive member that forms an electrostatic latent image on the surface in response to light irradiation, and a toner image obtained by visualizing the formed electrostatic latent image with magnetic toner on a recording paper. In an electrophotographic apparatus including a transfer member for transferring and a charging member for charging the photosensitive member to a set potential, at least one of the transfer member and the charging member is formed of a cylindrical roller and is in contact with the roller. An electrophotographic apparatus having a cleaning roller provided with a magnet. 2. The electrophotographic apparatus according to claim 1, wherein the transfer member and the charging member are formed of cylindrical rollers, and the cleaning roller is in contact with at least one of the rollers. 3. The electrophotographic apparatus according to claim 1, wherein the cleaning roller is composed of a hollow rotary cylinder, and the magnet is housed in the hollow portion. 4. The electrophotographic apparatus according to claim 1, wherein the cleaning roller comprises a cylindrical magnet.