JP3634352B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that reduces friction at a contact portion between a cleaning member that scrapes residual toner on an image carrier and an image carrier.
[0002]
[Prior art]
A film-shaped rake sheet that is gently pressed against the surface of the image carrier and a staying wall are arranged below the cleaning blade that removes toner by contacting the edge with the surface of the image carrier and a cleaning blade. It has been proposed that the removed toner is deposited in the space between the scooping sheet and the staying wall, and the deposited toner is softly brought into contact with the surface of the image carrier to trap paper dust passing through the scooping sheet ( JP-A-1-161288).
[0003]
Also, the toner scraped off by the cleaning blade is deposited with the scooping sheet and the rotatable deposition plate, and the deposited toner is brought into soft contact with the surface of the image carrier to trap the paper dust that passes through the scooping sheet. Also, there has been proposed one in which the accumulated toner is dropped to the lower part of the casing by rotating the accumulation plate (Japanese Patent Laid-Open No. 5-1257577).
[0004]
[Problems to be solved by the invention]
However, in the above-mentioned conventional one, it is not disclosed how and when the toner is accumulated in the vicinity of the rake sheet, and depending on how the image forming apparatus is used, toner accumulation is insufficient, so that paper dust is effectively removed. There is a possibility that the paper cannot be trapped, and the paper dust directly hits it and damages the cleaning blade, resulting in streak-like stains on the image.
[0005]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, effectively securing deposited toner that contacts the surface of the image carrier, trapping paper dust, and reducing friction at the contact portion between the image carrier and the cleaning means. The purpose is to be able to plan.
[0006]
[Means for Solving the Problems]
The image forming apparatus according to the present invention includes a charging unit that charges the surface of the image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the surface of the image carrier, and toner development of the formed electrostatic latent image. A developing means, a transfer means for transferring the developed toner image, a cleaning blade for scraping off the toner remaining on the surface of the image carrier, and a part of the toner scraped off by the cleaning blade are rubbed against the surface of the image carrier. And a cleaning unit made of a deposition member to be deposited, and the developing unit is operated without operating the charging unit, and the toner on the surface of the image carrier is scraped off by the cleaning blade and deposited on the deposition member. A forming device,
The developing means comprises a plurality of developing means having different end positions, and operates at least two developing means, that is, a developing means located at the rightmost end and a developing means located at the leftmost end .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention are described below.
[0008]
In the field of image forming apparatuses such as copiers and printers using an electrophotographic process, there is a trend toward higher image quality (toner particle size reduction), higher speed, and longer service life. In order to prevent a decrease in the fluidity of the toner, a fluidity improver (inorganic substance) such as silica and titanium oxide is excessively added, and therefore the cleaning properties of the toner tend to deteriorate. In order to improve (ensure) the cleaning performance, it is necessary to increase the contact pressure and contact angle of the cleaning blade. However, if the cleaning performance is improved in this way, the frictional force between the blade and the image carrier surface is improved. Increases and the cleaning blade turns over. In particular, turning-up tends to occur in an image pattern with little residual toner or in a high temperature and high humidity environment.
[0009]
In response to this turning over problem, the present applicant has proposed to stabilize the frictional force between the blade and the image carrier surface at a low level by collecting toner at the contact portion between the cleaning blade and the image carrier. As a result, the contact pressure and contact angle of the cleaning blade can be tightened, the problem of turning over can be solved while ensuring the cleaning property, and the performance of the cleaner can be greatly improved. Therefore, in the present invention, the toner storage method is devised regardless of measures against foreign matters such as paper dust and measures for turning over the cleaning blade.
[0010]
FIG. 1 is a schematic view showing the overall configuration of the image forming apparatus of the present invention, and FIG. 2 is a diagram for explaining the cleaning apparatus of the present invention.
The drum-shaped photoreceptor 1 is rotationally driven in the direction of arrow D by a drive source (not shown). A charging roller 2 is disposed on the outer periphery of the photoconductor 1 and uniformly charges the surface of the photoconductor 1 while rotating in contact with the photoconductor 1. The uniformly charged photoreceptor 1 is selectively scanned and exposed as a first color according to, for example, yellow image information by a latent image forming unit (not shown) to form a yellow electrostatic latent image. On the downstream side in the rotation direction of the photoreceptor 1 on which the electrostatic latent image is recorded, developing means 4, 5, 6, and 7 are arranged to store yellow, magenta, cyan, and black toners as developers, respectively. The yellow electrostatic latent image is developed with only the yellow developing means 4 in contact with the photosensitive member 1 to form a yellow toner image.
[0011]
An intermediate transfer belt 8 is disposed adjacent to the photoreceptor 1 on the downstream side in the rotation direction of the photoreceptor 1 on which the toner image is formed. The intermediate transfer belt 8 is wound around a drive roller 9, a backup roller 10, a tension roller 11, and a scissor roller 12, and is driven at the same speed as the peripheral speed of the photoreceptor 1. Further, the driving force of the photosensitive member 1 is transmitted to the driving roller 9 so that the photosensitive member 1 and the intermediate transfer belt 8 are driven synchronously. The primary transfer roller 13 is urged toward the photoreceptor 1 via the intermediate transfer belt 8, and a primary transfer position where the intermediate transfer belt 8 is sandwiched between the photoreceptor 1 and the primary transfer roller 13 from a high voltage power source (not shown). By supplying a voltage to the primary transfer roller 13, the yellow toner image is transferred to the surface of the intermediate transfer belt 8. The photosensitive member 1 having the yellow toner image transferred to the intermediate transfer belt 8 is further rotated in the direction of arrow D, and the toner remaining on the surface is scraped off by the cleaning blade 16 so that the image can be formed again. There may be a case where a static elimination means for resetting the photoreceptor potential before charging is provided. By repeating the same procedure for the second to fourth color images in this way, four color toner images are sequentially superimposed and recorded on the intermediate transfer belt 8.
[0012]
The cleaning blade 16 is attached to the inside of the case 14 with a cleaning blade support sheet metal 15, and its tip abuts against the surface of the photoreceptor 1. Further, a scooping sheet 17 is attached to the lower side of the case 14 so as to face the cleaning blade 16 so that the residual toner scraped off by the cleaning blade 16 does not leak out of the case. In addition to the scoop sheet, a toner accumulating member 18 is provided so as to extend to a position higher than the tip edge of the cleaning blade 15, and scraped toner is accumulated, and the accumulated toner adheres to the surface of the photoreceptor 1 and the cleaning blade. It also collects at the contact area.
[0013]
That is, as shown in FIG. 2, the toner 20 is deposited in the space formed on the surface of the rake sheet 17, the toner accumulation member 18, and the photoreceptor 1, and the tip of the cleaning blade 16 is buried in the toner. Since toner is present at the contact portion between the surface of the photoreceptor 1 and the cleaning blade, the frictional force between them can be stabilized at a low level.
[0014]
Next, the width of toner development for storing toner by the toner accumulation member will be described.
In general, the width of the region charged in the axial direction of the photosensitive member by the charging roller (charge width), the width of the toner developed by the developing roller (development width), and the latent image forming means forms an electrostatic latent image by laser light irradiation. As shown in FIG. 3, the relationship of the laser irradiation width (effective image width) in this case is the relationship of charge width> development width ≧ effective image width, and naturally, the cleaning blade width> development width. In general, the width of the cleaning blade is the same as the width of the charging roller. By the way, when accumulating the toner with the toner accumulating member, if the toner is not accumulated more than the width of the cleaning blade, it prevents the foreign matters such as paper dust from reaching the end of the cleaning blade and the blade from the end of the cleaning blade. It cannot prevent turning over.
[0015]
Therefore, in order to efficiently collect the toner up to the end of the cleaning blade, it is preferable to supply the toner with the full width of the developing device. Since the effective image width obtained by laser light irradiation is narrower than the width of the developing device, development is not performed by irradiating the laser light, but without applying a charging bias, that is, by operating the developing device without charging. If the toner is developed to the full width of the container and is scraped off by the cleaning blade, the toner at the end of the developing width spreads to the end of the cleaning blade and can be collected up to the end of the cleaning blade. At this time, the transfer bias is not applied. By not applying the transfer bias, most of the developed toner reaches the cleaning blade portion, so that the toner can be collected more efficiently.
[0016]
FIG. 4 is a view showing an example of the toner reservoir of the present invention.
In an image forming apparatus having Y, M, C, and Bk developing units, the width of the Bk developing unit is larger than the widths of the other developing units, for example, only the black image is A3 and the color image is up to B4. In such a case, if the toner is developed by operating the Bk developing device and supplied to the cleaning blade, the toner can be supplied in the widest width, and the toner can be stored at the end of the cleaning blade. Of course, in this case, not only the Bk developing unit but also other developing units may be operated simultaneously.
[0017]
FIG. 5 is a view showing another example of the toner reservoir of the present invention.
In the contact development in which the developing roller is brought into contact with the photosensitive member for development, a rubber roller is usually used. However, if a relatively hard developing roller is used, the photosensitive member may be damaged at the roller edge portion. As shown in FIG. 4, the Y, M, C, and Bk developing devices are arranged slightly shifted in one direction. In such an image forming apparatus, the widest width is obtained by operating the two developing units, the developing unit located at the right end and the developing unit located at the left end, to develop toner and supply it to the cleaning blade unit. Can supply toner. Also in this case, of course, the other two developing units may be operated simultaneously.
[0018]
In the case of an apparatus having charge removal light that resets the photoreceptor potential before charging, when the charge removal light is applied with the charge bias OFF and laser OFF, the photoreceptor potential before development is set to the bright part potential (image formation potential). Therefore, it is possible to supply (develop) the toner in a state that is almost solid over the entire area of the charge removal light irradiation. In this case, it is desirable that the static elimination light width ≧ the development width.
[0019]
FIG. 6 is a functional block diagram for performing toner storage processing according to the present invention.
The control device 30 including a CPU or the like provided in the image forming apparatus of the present invention is configured to store the bias of the charging roller 31, the power of the laser 32 on / off, the bias of the transfer device 33, and the power of the charge removal device 34 when storing toner. The Y, M, C, and Bk developing rollers 35, 36, 37, and 38, or the largest developing roller, Recognize the leftmost and rightmost developing rollers, and select and control the developing roller so that a wide range of toner development can be performed.
[0020]
【The invention's effect】
As described above, according to the present invention, the toner is developed to the full width of the developing device by developing the developing device without applying the charging bias, and the toner can be accumulated up to the end of the cleaning blade. At this time, by not applying a transfer bias, most of the developed toner reaches the cleaning blade portion, and the toner can be collected more efficiently.
[0021]
In addition, when there are a plurality of developing devices, at least the developing device having the widest developing width is operated, and when there are a plurality of developing devices having different end positions, the developing device located at the rightmost end is By operating at least two developing units of the developing unit located at the left end, the toner can be stored in the widest width.
[0022]
Also, by setting the discharge light irradiation area width of the discharge light device that resets the photoreceptor potential before charging by the charging roller to be equal to or greater than the development width, toner is supplied in a state that is almost solid over the entire discharge light irradiation area. Toner can be stored in the toner.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus of the present invention.
FIG. 2 is a diagram illustrating a cleaning device of the present invention.
FIG. 3 is a diagram illustrating a relationship between a charging width, a developing width, and an effective image width.
FIG. 4 is a diagram illustrating an example of a toner reservoir according to the present invention.
FIG. 5 is a diagram illustrating another example of a toner reservoir according to the present invention.
FIG. 6 is a functional block diagram for performing toner reservoir processing according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Photoconductor, 2 ... Charging roller, 4,5,6,7 ... Developing means, 8 ... Intermediate transfer belt, 9 ... Drive roller, 10 ... Backup roller, 11 ... Tension roller, 12 ... Removal roller, 13 ... Primary transfer roller, 14 ... case, 15 ... cleaning blade support sheet metal, 16 ... cleaning blade, 17 ... rake sheet, 18 ... toner depositing member, 19 ... holding member, 20 ... deposited toner, 30 ... control device, 31 ... charging Roller, 32 ... laser, 33 ... transfer device, 34 ... static elimination device, 35, 36, 37, 38 ... developing roller.

Claims (1)

A charging unit for charging the surface of the image carrier, an electrostatic latent image forming unit for forming an electrostatic latent image on the surface of the image carrier, a developing unit for developing the formed electrostatic latent image with toner, and a developed toner Transfer means for transferring an image, a cleaning blade for scraping off toner remaining on the surface of the image carrier, and a stacking member for depositing a part of the toner scraped off by the cleaning blade so as to rub against the surface of the image carrier. An image forming apparatus comprising: a cleaning unit; wherein the developing unit is operated without operating the charging unit, and the toner on the surface of the image carrier is scraped off by the cleaning blade and deposited on the deposition member;
The developing means comprises a plurality of developing means having different end positions, and operates at least two developing means, that is, a developing means located at the rightmost end and a developing means located at the leftmost end. Forming equipment.

Images