JP4223635B2 - 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 the surface of 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]
Therefore, the present invention provides a charging means for charging the surface of the image carrier, an electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image carrier, and a developing means for developing the formed electrostatic latent image with toner. And 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 that extends to a position higher than the leading edge of the cleaning blade. An image forming apparatus provided with a cleaning unit made of a deposition member for depositing the image carrier so as to be rubbed against the surface of the image carrier,
A selection means for selecting a predetermined print pattern from a plurality of print patterns in which the ratio of the area of the black portion and the white portion is changed, and a transfer bias control means for controlling the transfer bias of the transfer means,
An electrostatic latent image is formed with the print pattern selected by the selection means and toner is developed, and the transfer bias control means controls the transfer bias to adjust the amount of toner transferred to the transfer medium and reaches the cleaning blade portion. The toner amount is adjusted, the toner remaining on the surface of the image carrier after the transfer is scraped off by the cleaning blade and deposited on the deposition member, and the accumulated toner is collected at the contact portion between the surface of the image carrier and the cleaning blade. The tip of the cleaning blade is buried in the accumulated toner.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be 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. It should be noted that a static eliminating means for resetting the photosensitive member potential may be operated before charging. 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. In addition, although a cloud is usually generated from the tip of the cleaning blade, since that portion is buried in the toner, the generation of the cloud can be prevented and contamination outside the apparatus can be prevented.
[0014]
Next, a method for collecting toner with the toner accumulation member will be described.
In order to efficiently supply the toner to the cleaning blade, for example, an electrostatic latent image is formed with a black pattern and the photoreceptor is solidly developed, and most of the developed toner is removed without applying a transfer bias. To get to. However, if an excessively large amount of toner is supplied to the cleaner by such a method, cleaning failure occurs, and most of the toner passes through the cleaning blade, so that there is a possibility that the toner cannot be accumulated in the toner accumulation member.
[0015]
Therefore, in the present invention, for example, an appropriate amount of toner is supplied to the cleaner using a composite pattern including a solid portion 30 and a white portion 31 as shown in FIG. According to such a pattern, the toner supply amount to the cleaning blade can be freely adjusted by changing the ratio of the area of the solid portion 30 and the white portion 31.
[0016]
Further, as shown in FIG. 4, an appropriate amount of toner may be supplied to the cleaner by using a half pattern 40 having a halftone dot pattern. Also in this case, the toner supply amount to the cleaning blade can be freely adjusted by changing the area ratio of the black dots of the halftone dots.
[0017]
FIG. 5 is a diagram illustrating a flow in the case where toner accumulation is performed by adjusting the amount of toner using a composite pattern.
A plurality of print patterns 1, 2,... N with different ratios of the black and white portions are prepared, and a specific print pattern is selected from these print patterns (S1). Next, an electrostatic latent image is formed based on the selected printing pattern (S2), developed with toner (S3), supplied to the cleaning blade unit, scraped off the toner, and accumulated in the toner by the toner accumulation member. Perform (S4). By selecting the print pattern in this way, the amount of toner reaching the cleaning blade can be adjusted, so that the toner can be stored without causing cleaning failure. By not applying the transfer bias, most of the developed toner reaches the cleaning blade portion, and the toner can be supplied efficiently.
[0018]
FIG. 6 is a diagram showing a flow when toner is stored by adjusting toner by transfer bias control.
First, a predetermined printing pattern is selected to form an electrostatic latent image (S11-12). The printing pattern at this time is arbitrary, and may be a pattern as shown in FIGS. 3 and 4 or a solid pattern. Next, toner development is performed (S13), transfer is performed thereafter (S14), and toner accumulation processing is performed thereafter (S15). In the embodiment of the present invention, an intermediate transfer belt is used, but of course, transfer to a sheet may be used. In this transfer, the transfer bias is controlled to adjust the amount of toner to be transferred. By this transfer bias control, the amount of toner reaching the cleaning blade portion is adjusted, and toner can be stored without causing cleaning failure.
[0019]
【The invention's effect】
As described above, according to the present invention, an electrostatic latent image is formed by selecting a predetermined print pattern from among a plurality of print patterns, for example, a print pattern such as a solid and white composite pattern or a half pattern. Toner development can be performed, and the amount of toner reaching the cleaning blade portion can be adjusted, so that toner accumulation can be performed without causing cleaning failure.
[0020]
In addition, toner transfer can be performed by controlling the transfer bias to adjust the amount of toner reaching the cleaning blade portion, so as not to cause cleaning failure.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an 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 showing a solid and white composite pattern;
FIG. 4 is a diagram showing a half pattern.
FIG. 5 is a diagram illustrating a flow when toner accumulation is performed by adjusting the amount of toner using a composite pattern.
FIG. 6 is a diagram illustrating a flow when toner is stored by adjusting toner by transfer bias control.
[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 ... solid portion, 31 ... white portion.

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 portion of the toner scraped off by the cleaning blade on the surface of the image carrier. An image forming apparatus comprising: a cleaning unit including a deposition member that is deposited so as to be rubbed;
A selection means for selecting a predetermined print pattern from a plurality of print patterns in which the ratio of the area of the black portion and the white portion is changed, and a transfer bias control means for controlling the transfer bias of the transfer means,
An electrostatic latent image is formed with the print pattern selected by the selection means and toner is developed, and the transfer bias control means controls the transfer bias to adjust the amount of toner transferred to the transfer medium and reaches the cleaning blade portion. The toner amount is adjusted, the toner remaining on the surface of the image carrier after the transfer is scraped off by the cleaning blade and deposited on the deposition member, and the accumulated toner is collected at the contact portion between the surface of the image carrier and the cleaning blade. An image forming apparatus, wherein a tip of a cleaning blade is buried in accumulated toner.

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