JPH04360168A - Image forming device - Google Patents

Abstract

PURPOSE:To impart electrifying and cleaning functions to an electrifying roll by forming a spiral shaped projecting groove on a surface of the electrifying roll for primary electrification and carrying out cleaning with this projecting groove, while maintaining the electrifying function. CONSTITUTION:The spiral shaped projecting groove 12c is formed on the surface of the electrifying roll 12. Because of this, the image bearing body is electrified by the electrifying roll 12, as in a normal case, and with the effect of this projecting groove 12c, incoming residue toner and other foreign matters are slid and eliminated and the effect as a cleaning means is actuated, as well. That is, the residue toner (t) reaching a position of the electrifying roll 12 is scraped off on a surface B side upstream of the projecting groove 12c, and the electrification is affected on the surface abutting the image bearing body and a surface A. In this case, since the projecting groove 12c is in the spiral shape, the scraped off toner (t), etc., are successively carried in the direction (d) along with the rotation of the electrifying roll 12, dropped and accumulated in a toner storing part 14b.

Description

[Detailed description of the invention]

0001

[Purpose of the invention]

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

After uniformly charging the surface of the image carrier and applying an image signal to the charged surface to form an electrostatic latent image, toner is supplied to the surface to form a toner image, and this toner image is transferred to paper. After the toner image is transferred to a transfer material such as, the toner image is fixed and fixed on the transfer material, and the remaining toner that is not transferred to the transfer material and remains on the surface of the image carrier is removed by a cleaning means such as a cleaning blade. Forming devices have been widely used in the past.

FIG. 5 is a schematic side view showing a typical example of such an image forming apparatus, in which the surface of the image carrier 1 extending perpendicular to the plane of the paper and rotating in the direction of arrow A is shown. However, it is uniformly charged by the charging bias applied to the charging roller 5 that comes into contact with the charging roller 5.

[0004] An image signal 7 such as an image-modulated laser beam is applied to this charged surface, and the potential at the relevant portion is attenuated to form an electrostatic latent image.

As the image carrier 1 rotates, the latent image arrives at a developing area where the developing device 8 is located, and toner is supplied from the developing device and adheres to the latent image portion to form a toner image. .

When this toner image reaches the transfer site formed by the image carrier 1 and the transfer roller 11 that comes into contact with it,
At the same time, the transfer material P is supplied to the transfer site and a transfer bias is applied to the transfer roller 11, and the toner image on the image carrier 1 is transferred to the transfer material P by the action of the electric field formed. do.

Thereafter, the transfer material carrying the toner image is conveyed to a fixing site (not shown), where the toner image is fixed and fixed to the transfer material, and some of the toner that was not transferred to the transfer material during the transfer is transferred to the cleaning device 2. When the image carrier 1 reaches the position , it is removed by the cleaning blade 3, and the image carrier 1 is ready for the next image forming process.

In the image forming apparatus configured as described above, the charging roller 5 as the primary charging means does not require a high-voltage power source and does not generate ozone, compared to a device using a conventionally known corona discharger. It is becoming more and more commonly used because of its advantages such as small size.

Further, the cleaning blade used in the illustrated apparatus is a blade made of an elastic material such as urethane rubber, which is brought into contact with the image carrier in a counter direction with respect to the running direction of the image carrier. However, because of this, the friction with the image carrier is large, and this is especially noticeable when there is no toner on the surface of the image carrier when the device is first used, and there is a risk of the blade turning over. In order to prevent this, polyvinylidene fluoride, which is a solid lubricant, is applied to the edge portion of the blade that comes into contact with the image carrier.

By the way, as mentioned above, when a contact type charging means such as a charging roller is used, the charging means rubs the surface of the image carrier, so that toner and dust on the surface are removed. In addition, polyvinylidene fluoride coated as a lubricant on the edge of the cleaning blade, which has peeled off due to vibrations or impact of the blade or image carrier, inevitably adheres thereto.

Since this polyvinylidene fluoride is an insulating material, if it exists in the area where the charging roller 5 and the image carrier 1 come into contact, this area will cause a local charging failure and the circumference of the charging roller will change. Image defects such as black spots and white spots occur on the image at the same intervals as the image carrier, and the pressure of the charging roller on the image carrier promotes the adhesion of foreign substances such as toner to the image carrier. There is a risk.

[0012] Also, regarding the cleaning device,
The straightness of the blade edge of the cleaning blade 3 that presses against the surface of the image carrier 1, the angle of contact of the blade with the image carrier, and the uniformity of the pressure force over the entire length are important factors in order to obtain a good cleaning action of the blade. High installation accuracy is required. Furthermore, the scooping sheet 4 disposed upstream of the cleaning blade 3 of the cleaning device allows toner entering the cleaning area to freely pass therethrough, and allows the toner removed by the blade 3 to leak to the outside. Since it is necessary to hold the scoop sheet in the cleaning device without any interference, high precision is also required in the relative arrangement of the scoop sheet with respect to the surface of the image carrier.

As mentioned above, in order to make the cleaning device work well, there is a problem in that it increases the number of parts and the number of assembly steps, which leads to an increase in cost.For this reason, a contact type device such as a charging roller is used. In this case, it has been proposed to eliminate the cleaning device and use the charging means also as the cleaning means. If this is possible, it would be extremely suitable, particularly for cartridge-type image forming apparatuses in which members around the image carrier are required to be housed in as small a space as possible.

However, with such a configuration, as described above, a large amount of toner and other foreign matter must accumulate in the nip between the charging roller and the image bearing member, which impairs the charging function of the charging roller. As a result, there was a situation where the toner was significantly reduced and the fusion of the toner onto the image bearing member was promoted by the pressing action of the charging roller, making it completely unusable.

The present invention has been made in view of the current situation, and is an image forming apparatus that uses a contact type charging means such as a charging roller, in which the surface of the charging roller is formed in a spiral shape. The surface is substantially divided into a portion that mainly contributes to charging the image carrier and a portion that removes incoming residual toner and other foreign matter, thereby forming a uniform charging surface and removing residual toner and other foreign matter. It is an object of the present invention to provide an image forming apparatus that can perform stable charging and cleaning at all times while simultaneously achieving both removal and removal.

[0016]

[Structure of the invention]

[Technical Means for Solving the Problems and Their Effects] In order to achieve the above object, the present invention provides an image forming apparatus with a charging member that rotates in contact with an image carrier, and a charge member that remains on the surface of the image carrier even after transfer. The charging member is characterized in that a linear protrusion is formed on the charging member to remove the toner.

With this configuration, there is no need to separately install a cleaning device to remove residual toner.
The configuration is simple and can be downsized, which is also effective in reducing costs.

[0018]

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a schematic side view showing the configuration of an image forming apparatus to which the present invention is applied. It is integrally built into the frame 14 and is detachably attached to the main body of the device.

The image carrier 10, which has been uniformly charged by the primary charging roller 12, is then charged via the lens array 13.
An image signal such as reflected light from the original or an image-modulated laser beam is projected onto the charged surface to form an electrostatic latent image, and the latent image is formed when the developing device 11 and the image carrier 10 face each other. When the latent image is reached, toner is supplied from the developing device 11 to the latent image to form a toner image.

Furthermore, when this toner image arrives at the transfer site where the transfer roller 15 is in contact with the image carrier 10, it is transferred from the paper feed tray 16 side via the paper feed roller 17 and the registration roller 18 at the same timing. A material (not shown) is conveyed to the transfer site, and the toner image on the image carrier 10 side is transferred to the transfer material side by a transfer bias applied to the transfer roller.

Thereafter, the transfer material carrying the toner image is separated from the image carrier 10, passes through the conveyance path 19, reaches the fixing section 20, and after the toner image is fixed and fixed on the transfer material, it is removed from the paper output tray 21 to the outside of the machine. be discharged.

During transfer, the image carrier 1 does not transfer to the transfer material.
The residual toner remaining on the surface of the image carrier 10 reaches the position of the charging roller 12 as the image carrier rotates, and is rubbed off by the roller, and the image carrier 10 is ready for the next image forming process. . That is, in the case of the illustrated apparatus, the charging roller 12 is configured to also perform a cleaning function of removing residual toner.

Next, the above-mentioned charging roller 12, which has a charging function and also has a cleaning function, will be explained.

"FIG. 2" shows the image carrier 1 of the apparatus of "FIG. 1".
0 and a charging roller 12 in contact with the charging roller 12, the image carrier 10 has its shaft ends 10a, 10b
is pivotally supported on the cartridge frame 14, and the charging roller 12
is pivotally supported by a conductive bearing 12b, and a spring 13
The image bearing member 12 is pressed against the image carrier 12 with an appropriate pressure.

In the illustrated apparatus, a gear 10g formed at the left end of the image carrier meshes with a gear 12g formed at the end of the charging roller 12 so that both run at an appropriate relative speed. It is structured as follows.

In the illustrated device, a spiral protrusion 12c is formed on the surface of the charging roller 12. It is preferable that the height of the protrusion is approximately 50 μm. With this configuration, the charging roller 12 not only charges the image bearing member in the same way as in a normal case, but also acts as a cleaning means by removing residual toner and other foreign matter that arrive due to the action of the protrusions. It can also be played.

"FIG. 3" is a schematic diagram illustrating the cleaning action of the charging roller 12. The residual toner t that has reached the position of the charging roller is scraped off by the upstream surface of the protruding strip 12c, the side indicated by the symbol B. , a charging action is performed on the surface in contact with the image carrier and the surface A in the drawing.

Since the protruding stripes have a rectangular shape, the scraped toner is sequentially conveyed in the direction of symbol d in the figure as the charging roller rotates, and is transferred to the waste toner storage section 14b.
It falls and accumulates.

In this case, in order to remove the toner and avoid contamination of the charging roller, a scoop sheet 27 is placed in contact with the roller as shown in FIG. In order to prevent the scattering of the
A sealing member is provided as shown at 6.

Regarding the charging function of the charging roller, in order to perform good charging, it is necessary to make the circumferential speed of the charging roller 12 faster than that of the image carrier 10. When the charging roller 12 advances by b, the charging roller 12
Good results are obtained especially when the speeds of both are set so as to rotate.

"FIG. 4" shows another embodiment of the present invention, and as in the case of "FIG. 3", only the vicinity of the part where the image bearing member and the charging roller are in contact is shown, and " Figure 3
The same reference numerals are given to the parts corresponding to those in the apparatus shown in FIG.

In the illustrated device, the linear protrusions formed on the surface of the charging roller 12 are divided into two protrusions 12c1 and 12c2 whose directions are opposite, so that the scraped toner is The toner is conveyed to the left and right in the figure and collected in the toner storage portions 14b on both sides.

[0033] With this configuration, the average transport distance for the scraped toner to reach the storage section is reduced, and recovery efficiency is improved.

Although not shown in the drawings, by forming a plurality of protrusions on the charging roller, a plurality of protrusions are applied to the toner at one place on the surface of the image carrier during one rotation of the image carrier. Since the circular scraping action works, the ability to remove toner, etc. is improved.

[0035]

As explained above, according to the present invention, after the surface of the image carrier is charged by a charging roller or the like and the toner image formed thereon is transferred to a transfer material, the remaining toner is removed by a cleaning means. In an image forming apparatus configured to remove electricity, the charging roller is used as a cleaning means, and there is no need to separately install a special cleaning device, which greatly contributes to miniaturization and cost reduction of the image forming apparatus. be.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of an image forming apparatus showing an embodiment of the present invention.

[Figure 2] Front view of the main parts of the same as above

[Figure 3] Schematic diagram explaining the cleaning action of the charging roller

[Fig. 4] Front view of main parts showing another embodiment

FIG. 5 is a schematic side view showing the configuration of a known image forming apparatus.

[Explanation of symbols]

Claims (1)

[Claims] 1. An image forming apparatus comprising a charging member that rotates in contact with an image carrier, and a linear protrusion is formed on the charging member to remove residual toner remaining on the surface of the image carrier after transfer.