JP3695512B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus such as a copying machine or a printer, and in particular, a primary transfer unit that transfers a toner image from a photosensitive member to an intermediate transfer member, and a toner image that is transferred from the intermediate transfer member to a sheet. The present invention relates to an image forming apparatus including a secondary transfer unit.
[0002]
[Prior art]
In the image forming apparatus of the above-mentioned type, an image carrier such as a rotationally driven photoconductor, latent image forming means for sequentially forming electrostatic latent images for a plurality of colors on the photoconductor, and the electrostatic latent image A developing means for developing the toner image into a plurality of color toner images, an intermediate transfer member comprising an intermediate transfer belt rotating in contact with the photosensitive member, and a plurality of color toner images on the photosensitive member overlapping the intermediate transfer member. Primary transfer means for transferring and forming a color image; secondary transfer means for transferring a color image on the intermediate transfer body onto a transfer material; and for removing toner remaining on the photoreceptor and the intermediate transfer body. A cleaning device is provided.
[0003]
In the cleaning device, a cleaning blade or the like is disposed in a direction orthogonal to the running direction of the photosensitive member and the intermediate transfer member to remove residual toner. In this case, toner adheres to both ends of the blade and remains as a toner streak. If this is left unattended, it accumulates on the intermediate transfer member, and toner that cannot be held on the intermediate transfer member may spill out, or both sides of the cleaning device By being scraped off by a side seal that seals the surface, there is a problem that in-machine contamination is caused in a paper conveyance path or the like. For this reason, in Japanese Patent Publication No. 7-43561, auxiliary blades (auxiliary cleaners) are provided at both ends of the cleaning blade.
[0004]
[Problems to be solved by the invention]
However, when this method is employed in an image forming apparatus composed of a photoreceptor and an intermediate transfer member, a cleaning device that collects toner streaks (hereinafter referred to as “photosensitive toner streaks”) generated at the end of the cleaning blade on the photoreceptor side; In addition, two pairs of auxiliary cleaners and a collection box (collection space) for collecting toner streaks (hereinafter referred to as “intermediate transfer body toner streaks”) generated at the edge of the cleaning blade on the intermediate transfer member side are required. Has the problem of inviting up.
[0005]
Therefore, as shown in FIG. 7A, it is considered that the cleaning toner width on the intermediate transfer member side is made larger than the cleaning blade width on the photosensitive member side so that the photosensitive toner stripes are collected by the cleaning device on the intermediate transfer member side. However, since the cleaning blade on the intermediate transfer member side makes contact with the intermediate transfer member, cleaning properties deteriorate due to the presence of foreign matter (photosensitive toner streaks) in the cleaning blade at the time of contact with the blade. In such a state, by continuously cleaning the photosensitive toner streaks, the load on the cleaning blade increases, resulting in poor cleaning, and as a result, the blade wears out rapidly, resulting in poor cleaning. The amount increases. At this time, normally, a part of the cleaned toner travels along the blade tip and moves to the end side, but leaks from the previous defective cleaning portion, so that the toner gradually disappears at the end of the cleaning blade and the frictional force. Increases and blade curling occurs. Therefore, an auxiliary cleaner cannot be provided on the downstream side of the cleaning blade on the intermediate transfer member side.
[0006]
Therefore, as shown in FIG. 7B, it is conceivable to provide an auxiliary cleaner on the upstream side of the cleaning blade on the intermediate transfer member side, and in this case, accumulation of toner stripes on the intermediate transfer member can be prevented, In addition, since the cleaning blade can be brought into contact with the surface cleaned by the auxiliary cleaner, the previous cleaning failure due to the presence of foreign matter can be prevented. However, under normal conditions where the transfer bias is applied, only a very small amount of toner on the intermediate transfer member moves to the photosensitive member side, but insulation breakdown occurs immediately after the start of rotation of the photosensitive member or intermediate transfer member or immediately before the stop. In order to avoid this, a bias is not applied, and a part of the intermediate transfer member toner streak moves to the photosensitive member side. When such a cycle is repeated, toner streaks (intermediate transfer body toner streaks) located outside the end of the cleaning blade on the photoconductor side may fall after being deposited on the end of the side seal that seals both sides of the cleaning device, There arises a problem that the machine is slid by the side seal and dropped to cause in-flight contamination.
[0007]
The present invention solves the above problems, and includes a primary transfer unit that transfers a toner image from a photosensitive member to an intermediate transfer member, a secondary transfer unit that transfers a toner image from the intermediate transfer member to a sheet, and a photosensitive member. In the image forming apparatus having a cleaning unit for removing residual toner on the intermediate transfer member, the auxiliary cleaner on the photoconductor side can be omitted to reduce the cost and space, and the image can reliably remove the toner streak. An object is to provide a forming apparatus.
[0008]
[Means for Solving the Problems]
Therefore, an image forming apparatus according to the present invention includes a primary transfer unit that transfers a toner image from a photosensitive member to an intermediate transfer member, a secondary transfer unit that transfers a toner image from the intermediate transfer member to a sheet, a photosensitive member, and an intermediate transfer member. In the image forming apparatus including a cleaning unit for removing residual toner on the intermediate transfer member, the width of the photosensitive member cleaning unit is made larger than the width of the intermediate transfer member cleaning unit, and the intermediate transfer member cleaning unit from the downstream side of the primary transfer portion of the intermediate transfer member Auxiliary cleaning means is disposed between the upstream side of the intermediate transfer belt, the intermediate transfer member is an intermediate transfer belt, and is opposed to the both ends of the intermediate transfer belt at a position facing the secondary transfer backup roller of the secondary transfer unit. A pair of auxiliary cleaning means are arranged so as to be in contact with each other .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram showing an embodiment of an image forming apparatus of the present invention. This image forming apparatus is a color electrophotographic printer capable of forming a full color image with four color toners. However, the present invention is not limited to this, and an image transfer body such as a photoconductor to an intermediate transfer body. The present invention can be applied to all image forming apparatuses that transfer toner images.
[0010]
The photosensitive member 1 has a thin cylindrical conductive substrate and a photosensitive layer formed on the surface thereof, and is driven to rotate in the direction of the arrow shown by a driving unit (not shown). Around the photosensitive member 1, along the rotation direction, a charging roller 2 as charging means, an exposure unit 3 for forming an electrostatic latent image on the photosensitive member 1, and an electrostatic latent image are developed. The developing unit 4, the intermediate transfer device 5 for transferring the toner image formed on the photoconductor 1 onto the intermediate transfer belt 7, and the photoconductor cleaning device 6 for removing the toner remaining on the photoconductor 1. Is arranged. In this example, the charging roller 2 and the photoconductor cleaning device 6 are accommodated in the unit 8.
[0011]
The developing unit 4 includes a yellow developing unit 4Y, a cyan developing unit 4C, a magenta developing unit 4M, and a black developing unit 4K. These developing units 4Y, 4C, 4M, and 4K are respectively connected to the photoreceptor 1. The developing roller 4a of only one developing device can be selectively brought into contact with the photosensitive member 1 every rotation of the photosensitive member 1. The electrostatic latent images on the photosensitive member 1 are sequentially developed by the developing devices 4Y, 4C, 4M, and 4K, and the developed toner images are sequentially transferred to the intermediate transfer belt (intermediate transfer member) 7 of the intermediate transfer device 5. Is transcribed. The photoconductor cleaning device 6 has a cleaning blade 6a (which is always in contact with the photoconductor 1) for scraping off the toner remaining on and adhering to the outer peripheral surface of the photoconductor 1 after the transfer of each toner image. And a collecting unit 6b for storing toner scraped off by the cleaning blade 6a.
[0012]
The intermediate transfer device 5 includes a driving roller 9 for running the intermediate transfer belt 7, a primary transfer backup roller 10, a pre-primary transfer roller 11 for preventing wrinkles of the belt, a cleaning backup roller 12, and a secondary transfer roller. A backup roller 13 and a tension roller 14 for applying tension to the belt are configured, and an endless intermediate transfer belt 7 is stretched around each of these rollers. The drive roller 9 is configured to be driven in synchronization with the photosensitive member 1, whereby the intermediate transfer belt 7 is rotated in the direction of the arrow shown in the drawing at substantially the same peripheral speed as the photosensitive member 1. . The intermediate transfer belt 7 is urged toward the photoreceptor 1 by a primary transfer backup roller 10, and a primary transfer portion T1 is formed here.
[0013]
Further, an intermediate transfer member cleaning device 15 is disposed opposite to the cleaning backup roller 12 so as to be able to contact and separate from the intermediate transfer belt 7. The cleaning device 15 includes a cleaning blade 15a that contacts the intermediate transfer belt 7 and scrapes off toner adhering to the outer peripheral surface thereof, and a recovery unit 15b that stores toner scraped off by the cleaning blade 15a. It has.
[0014]
A secondary transfer roller 16 is disposed opposite to the secondary transfer backup roller 13 with the intermediate transfer belt 7 interposed therebetween, and a secondary transfer portion T2 is formed there. An auxiliary cleaning device 17 is disposed on the downstream side of the secondary transfer portion T2 so as to face the secondary transfer backup roller 13. The auxiliary cleaning device 17 is in contact with both end portions (outside of the toner image area) of the intermediate transfer belt 7 and scrapes off the toner remaining on and adhering to the outer peripheral surface thereof, and the cleaning blade 17a. And a collecting unit 17b that stores the toner scraped off by the toner.
[0015]
The operation of the image forming apparatus having the above configuration will be described. When an image forming signal is input from a computer (not shown), the photosensitive member 1, the developing rollers 4a of the developing unit 4 and the intermediate transfer belt 7 are driven to rotate. First, the outer peripheral surface of the photosensitive member 1 is uniformly charged by the charging roller 2, and the outer peripheral surface of the uniformly charged photosensitive member 1 is subjected to the first color (for example, yellow) image information by the exposure unit 3. A selective exposure L is performed to form a yellow electrostatic latent image.
[0016]
Only the developing roller 4a of the yellow developing device 4Y comes into contact with the photosensitive member 1, whereby a yellow electrostatic latent image toner image is formed on the photosensitive member 1. The intermediate transfer belt 7 is applied with a primary transfer voltage opposite in polarity to the toner charging polarity, and the toner image formed on the photoreceptor 1 is transferred onto the intermediate transfer belt 7 at the primary transfer portion T1. At this time, the secondary transfer roller 16 and the cleaning blade 15 a of the intermediate transfer body cleaning device 15 are separated from the intermediate transfer belt 7. After the toner remaining on the photosensitive member 1 is removed by the photosensitive member cleaning device 6, the outer peripheral surface of the photosensitive member 1 is discharged by a discharging means (not shown).
[0017]
The above operation corresponds to the second, third, and fourth colors of the image forming signal, and latent image formation and development by one rotation of the photoreceptor 1 and the intermediate transfer belt 7 are repeated. Four color toner images corresponding to the contents are superimposed and transferred on the intermediate transfer belt 7. Then, at the timing when this full-color image reaches the secondary transfer portion T2, the sheet S is supplied from the arrow direction to the secondary transfer portion T2, and at this time, the transfer roller 16 is pressed against the intermediate transfer belt 7 and the secondary transfer is performed. A voltage is applied, and the full color toner image on the intermediate transfer belt 7 is transferred onto the sheet S. At the same time, the cleaning blade 15a of the intermediate transfer body cleaning device 15 contacts the intermediate transfer belt 7, and the toner remaining on the intermediate transfer belt 7 after the secondary transfer is removed and collected.
[0018]
2 shows the intermediate transfer member cleaning device 15 of FIG. 1, FIG. 2 (A) is a front view, and FIG. 2 (B) is a sectional view taken along line BB of FIG. 2 (A). The intermediate transfer member cleaning device 15 is fixed to a cleaner case 15c having a toner recovery portion 15b therein, a toner transport auger 15d disposed in the toner recovery portion 15b, and an upper portion of the cleaner case 15c via a holding metal 15e. The cleaning blade 15a, the lower end is fixed to the lower portion of the cleaner case 15c, the upper end is a scooping sheet 15f disposed in the vicinity of the cleaning blade 15a, and the side seal 15g that seals both side surfaces of the cleaner case 15c. ing.
[0019]
3 to 5 show the configuration of the secondary transfer portion T2 of FIG. 1, FIG. 3 is a side view of the secondary transfer portion, and is a view seen in the direction of the arrow along the line XX of FIG. 3 is a plan view with the intermediate transfer belt 7 and the secondary transfer backup roller 13 removed in FIG. 3, FIG. 5A is a view seen from the Y direction in FIG. 4, and FIG. 5B is the view in FIG. It is a top view of a static elimination needle holding member.
[0020]
Between the pair of left and right frames 19, 19, a secondary transfer backup roller 13 is rotatably mounted, a support shaft 20 is fixed, and a roller support member 21 is swingably mounted on the support shaft 20. The secondary transfer roller 16 is rotatably disposed on the roller support member 21. A static elimination needle holding member 22 is fixed between the pair of left and right frames 19, 19 in proximity to the roller support member 21. The static elimination needle holding member 22 has a first attachment portion 22a formed at a position facing the secondary transfer roller 16, and second attachment portions 22b and 22b are formed integrally on both sides of the first attachment portion 22a. As a result, the number of parts can be reduced and the cost can be reduced. And the static elimination needle 23 is attached to the 1st attachment part 22a, and the auxiliary | assistant cleaning member 17a is attached to the 2nd attachment part 22b. Further, a dish-shaped toner collecting portion 24 for collecting toner scraped off by the auxiliary cleaning member 17a is connected to the lower portions of the pair of left and right frames 19 and 19.
[0021]
In the present embodiment, the frictional force per unit width of the auxiliary cleaning member 17a is set smaller than that of the intermediate transfer member cleaning blade 15a, and the static elimination needle holding member 22 that holds the auxiliary cleaning member 17a is made of resin. By doing so, the load of the auxiliary cleaning member 17a is reduced in an abnormally high load state, and as a result, it is possible to prevent the belt from being given a larger frictional force than necessary. Can be prevented.
[0022]
Next, features of the present invention will be described with reference to FIG. FIG. 6 is a schematic plan view for explaining the features of the present invention. In FIG. 6, the cleaning blade 6 a for the photosensitive member 1 is a photosensitive member cleaning unit, and the cleaning blade 15 a for the intermediate transfer belt 7 is an intermediate transfer member cleaning unit, and is disposed to face both end portions of the intermediate transfer member 7. A pair of cleaning blades 17a, 17a are auxiliary cleaning means. In the figure, the arrow indicates the traveling direction of the intermediate transfer member 7.
[0023]
In the present invention, the width of the photoconductor cleaning means 6a is made larger than the width of the intermediate transfer body cleaning means 15a, so that even if the intermediate transfer body toner streaks move to the photoconductor 1 side, the photoconductor cleaning means 6a On the other hand, the photoconductor toner streaks and the intermediate transfer body toner streaks are collectively collected on the intermediate transfer body 7. At this time, as shown in FIG. 6A, when auxiliary cleaning means 17a and 17a are provided on the downstream side of the intermediate transfer member cleaning means 15a, the photosensitive toner stripes are side seals of the intermediate transfer member cleaning device 15 (FIG. No. 15 f) is scraped off, causing in-flight contamination. Therefore, as shown in FIG. 6B, the auxiliary cleaning units 17a and 17a are arranged upstream of the intermediate transfer member cleaning unit 15a. Since the intermediate transfer body toner streaks adhere on the downstream side of the primary transfer portion T1, it is a matter of course that the auxiliary cleaning means 17a and 17a are arranged on the downstream side of the primary transfer portion T1.
[0024]
In the case where the intermediate transfer member is a belt as in the embodiment of FIG. 1, it is preferable to provide auxiliary cleaning means 17a, 17a opposite to the secondary transfer backup roller 13, and in this case, a dedicated backup is provided. No roller is required. In this case, as shown in FIG. 4, the width between the auxiliary cleaning means 17a and 17a is made larger than the width of the secondary transfer roller 16 so that the toner does not hit the secondary transfer roller 16 when the toner is removed. Further, it is desirable that the auxiliary cleaning means 17a, 17a is a fixed type that always contacts the transfer belt 7. This is because when the auxiliary cleaning means is separated, it is not necessary to simply place and seal the blade, and it requires the same function and configuration as a normal cleaning device capable of removing and collecting toner streaks. This is because the number of parts is increased and the cost is increased.
[0025]
Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications are possible. For example, in the above-described embodiment, an example in which an intermediate transfer belt is used as the intermediate transfer member is described. However, an intermediate transfer drum may be used. In the above embodiment, the cleaning means of the cleaning devices 6, 15 and 17 is a cleaning blade, but a cleaning brush may be used.
[0026]
【The invention's effect】
As is apparent from the above description, according to the present invention, a primary transfer portion that transfers a toner image from a photosensitive member to an intermediate transfer member, a secondary transfer portion that transfers a toner image from the intermediate transfer member to a sheet, a photosensitive member, and In an image forming apparatus including a cleaning unit that removes residual toner on an intermediate transfer member, an auxiliary cleaner on the photosensitive member side can be omitted to reduce cost and space, and toner streaks can be reliably removed.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an embodiment of an image forming apparatus of the present invention.
2 shows the intermediate transfer body cleaning device of FIG. 1, FIG. 2 (A) is a front view, and FIG. 2 (B) is a cross-sectional view taken along line BB of FIG. 2 (A).
3 is a side view showing the configuration of the secondary transfer portion of FIG. 1, and is a view seen in the direction of the arrow along the line XX of FIG.
4 is a plan view in which an intermediate transfer belt and a secondary transfer backup roller are removed in FIG. 3;
5A is a view as seen from the Y direction in FIG. 4, and FIG. 5B is a plan view of the static elimination needle holding member of FIG. 5A.
FIG. 6 is a schematic plan view for explaining the feature of the present invention.
FIG. 7 is a diagram for explaining a problem of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Photoconductor 6a ... Photoconductor cleaning means 7 ... Intermediate transfer body 13 ... Secondary transfer backup roller 15a ... Intermediate transfer body cleaning means 16 ... Secondary transfer roller 17a ... Auxiliary cleaning means 22 ... Static elimination needle holding member 24 ... Toner Collection unit S ... sheet T1 ... primary transfer unit T2 ... secondary transfer unit

Claims (5)

A primary transfer portion for transferring a toner image from the photosensitive member to the intermediate transfer member, a secondary transfer portion for transferring the toner image from the intermediate transfer member to the sheet, and a cleaning means for removing residual toner on the photosensitive member and the intermediate transfer member. In the image forming apparatus, the width of the photosensitive member cleaning unit is larger than the width of the intermediate transfer member cleaning unit, and an auxiliary cleaning unit is provided between the downstream side of the primary transfer portion of the intermediate transfer member and the upstream side of the intermediate transfer member cleaning unit. And the intermediate transfer member is an intermediate transfer belt, and a pair of auxiliary cleaning means are disposed so as to contact both side ends of the intermediate transfer belt at a position facing the secondary transfer backup roller of the secondary transfer unit. An image forming apparatus. 2. The image forming apparatus according to claim 1, wherein a frictional force per unit width of the auxiliary cleaning unit is set smaller than that of the intermediate transfer member cleaning unit. 3. The image forming apparatus according to claim 1, wherein a width between the pair of auxiliary cleaning units is set larger than a width of the secondary transfer roller. The image forming apparatus according to any one of claims 1 to 3, wherein said that the attached supplementary cleaning means removing needle holding member which is disposed in proximity to the secondary transfer portion. The image forming according to any one of claims 1 to 4, characterized in that connecting the toner recovery portion for recovering the toner scraped off by the auxiliary cleaning means between a pair of frames for holding the secondary transfer portion apparatus.

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