JP3421288B2 - Image forming apparatus and process unit thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer and a process unit constituting the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-10-149073.
As described in Japanese Patent Application Laid-Open No. 2004-242242, in an image forming apparatus and a process unit thereof including a photosensitive drum that rotates so as to sequentially pass through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, A foreign matter collection brush (foreign matter collection member) that comes into contact with the peripheral surface of the photoconductor drum is disposed between the area and the area, and the foreign matter collection brush collects foreign matter such as paper dust and the residual toner adhering to the photoconductor drum. Is being done.

[0003]

As described above, the paper dust or the residual toner adhered on the photosensitive drum is collected by the foreign matter collecting member including the foreign matter collecting brush arranged between the transfer area and the charging area. In the case of being configured as described above, it is easier than a cleaning device having a cleaning blade for removing the residual toner and the like on the photoconductor drum and a storage unit for the residual toner and the like removed by the cleaning blade. With such a configuration, it is possible to prevent deterioration of image quality due to residual toner or paper dust or the like adhering to the photosensitive drum, and it is possible to effectively prevent toner aggregation or the like due to mixing of the paper dust into the developing device. There are advantages.

On the other hand, as shown in FIG. 6, the amount of foreign matter collected by the foreign matter collecting member gradually increases in accordance with the number of image forming sheets, and when the amount of foreign matter collected exceeds a certain amount, the foreign matter collecting ability is increased. Tends to saturate. For this reason, if a large amount of foreign matter adheres to a part of the foreign matter collecting member and the foreign matter collecting ability of this portion becomes saturated, even if there is a portion where the foreign matter collecting ability can be fully exhibited, There was a problem that the foreign matter collection member had to be replaced with a new one.

The present invention has been made in view of the above points, and an image forming apparatus and a process thereof which can stably collect foreign matters adhering to a photosensitive drum or the like for a long period with a simple structure. The purpose is to provide a unit.

[0006]

The invention according to claim 1 is
A photosensitive drum that rotates so as to sequentially pass through a charging area, an electrostatic latent image forming area, a developing area, and a transfer area, and a foreign matter collecting member that removes and holds foreign matter such as paper dust attached to the photosensitive drum. In the image forming apparatus including the above, a wide portion having a width dimension larger than that of the central portion is provided in a portion including the edge lines of the transfer sheet on both left and right sides of the foreign matter collecting member.

According to the above structure, since the wide portion is provided in the portion including the edge line of the transfer sheet on both the left and right sides of the foreign matter collecting member which generates a large amount of foreign matter, the foreign matter collecting ability of the foreign matter collecting member is improved. Partial saturation is effectively prevented, and foreign matter such as paper dust attached to the photosensitive drum is stably collected by the foreign matter collecting member for a long period of time.

According to a second aspect of the present invention, there is provided an image forming apparatus including a roller provided in a transfer sheet conveying section, and a foreign matter collecting member for removing and holding foreign matter such as paper dust attached to the roller. A wide portion having a width dimension larger than that of the central portion is provided at a portion including the edge line of the transfer sheet on both right and left sides of the foreign matter collecting member.

According to the above construction, since the wide portion is provided in the portion including the edge line of the transfer sheet on both the left and right sides of the foreign matter collecting member which produces a large amount of foreign matter, the foreign matter collecting ability of the foreign matter collecting member is improved. Partial saturation is effectively prevented, and foreign matter such as paper powder attached to the roller is stably collected by the foreign matter collecting member for a long period of time.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the width dimension of the wide portions provided on both the left and right sides of the foreign matter collecting member is set to be 1 of the width dimension of the central portion. It is set to 0.2 to 3.0 times.

According to the above construction, the width of the wide portions provided on both left and right sides of the foreign matter collecting member is set within a certain range, so that the foreign matter collecting member causes excessive rotation of the photosensitive drum or the roller. While the resistance is prevented from being applied, the foreign matter collecting member having the wide portion can stably collect the foreign matter attached to the photosensitive drum or the roller for a long period of time.

The invention according to claim 4 is the above claims 1 to 3.
In the image forming apparatus according to any one of 1 to 3, the distance from the edge line of the transfer sheet to the inner ends of the wide portions provided on both the left and right sides of the foreign matter collecting member is in the range of 20 to 40 mm. The size of the wide portion in the longitudinal direction of the foreign matter collecting member is set.

According to the above construction, since the wide portion of the foreign matter collecting member is provided in the necessary and sufficient range in the longitudinal direction, it is possible to prevent excessive rotation resistance from being imparted to the photosensitive drum or the roller. By the foreign matter collecting member having the wide portion, the foreign matter attached to the photosensitive drum or the like can be stably collected for a long period of time.

According to a fifth aspect of the present invention, a photosensitive drum rotating so as to sequentially pass through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, and a photosensitive drum disposed in the charging area. Between the transfer area and the charging area, and a charger for charging the peripheral surface of the toner sheet to a specific polarity, a developing apparatus disposed in the developing area for developing the electrostatic latent image on the photosensitive drum into a toner image. In a process unit of an image forming apparatus in which a foreign matter collecting member arranged to remove and hold foreign matter such as paper dust adhered to a photoconductor drum is unitized, an edge of a transfer sheet on both left and right sides of the foreign matter collecting member A wide portion having a larger width dimension than the central portion is provided in the portion including the line.

According to the above construction, since the wide portions are provided on both the left and right sides of the foreign matter collecting member where a large amount of foreign matter is generated, that is, the portion including the edge line of the transfer sheet, the foreign matter collecting member collects the foreign matter. A process unit capable of effectively preventing the ability from being partially saturated and capable of stably collecting foreign matter such as paper powder attached to the photosensitive drum for a long period of time by the foreign matter collecting member. Will be obtained.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows a printer which is an embodiment of an image forming apparatus according to the present invention. The printer is provided with a sheet conveying section 3 having a registration roller 2, a process unit 5 having a foreign matter collecting member 1 and a photosensitive drum 4 which will be described later, and a downstream side of the process unit 5 in the sheet conveying direction. Fixing unit 6
It has and.

The process unit 5 includes a charging area in which a charger 7 is installed, an electrostatic latent image forming area in which scanning exposure is performed by an exposing device (not shown), and a developing area in which a developing device 8 is installed.
A charging device 7, a developing device 8, a transfer roller 9 and a foreign matter collecting device, which has a photosensitive drum 4 which rotates so as to sequentially pass through a transfer area in which a transfer roller 9 is installed, are arranged along the peripheral surface thereof. The member 1 etc. are integrally provided and unitized.

The charger 7 includes a charging wire (not shown) to which a high voltage is applied, and the photosensitive drum 4 is subjected to, for example, positive corona discharge from the charging wire.
The surface layer of is charged to a predetermined positive potential.

The developing unit 8 electrostatically attaches toner charged with a positive polarity to the portion of the electrostatic latent image on which the positive charge has been lost on the photosensitive drum 4 by scanning exposure of the image, thereby exposing the photosensitive drum 4. The electrostatic latent image on the body drum 4 is developed with toner to form a toner image as a visible image on the surface of the photoconductor drum 4. Further, most of the unnecessary toner adhering to the photosensitive drum 4 is collected by the developing device 8 and reused.

Further, the transfer roller 9 is arranged so as to face the photosensitive drum 4 in a non-contact state, and is formed on the photosensitive drum 4 by performing negative corona discharge from the back side of the transfer paper. The toner image is electrostatically transferred onto the transfer paper.

The fixing unit 6 has a heating roller 12 for heating the transfer sheet on which the toner image is transferred in the process unit 5, and a pressure roller 13 for pressing the transfer sheet on the heating roller 12, and the transfer sheet The toner image is fused and fixed on the top.

The foreign matter collecting member 1 provided in the process unit 5 is a material suitable for removing and holding foreign matter such as paper powder adhered on the photosensitive drum 4, for example, a plate made of foam resin or a synthetic material. It is made of a resin brush or the like, and is arranged in a state of being in contact with the peripheral surface of the photosensitive drum 4 between the downstream side of the transfer area and the upstream side of the charging area.

The foreign matter collecting member 1 is set so that its entire length is substantially the same as that of the photosensitive drum 4, and
As shown in FIG. 2, wide portions 14 having a larger width dimension W1 than the central portion are provided on both left and right sides including the edge line a of the transfer sheet. Edge line a of the transfer paper
Indicates a line through which the left and right ends of the standard transfer sheet, that is, the transfer sheet most often used in the image forming apparatus, passes.

The width W1 of the wide portion 14 of the foreign matter collecting member 1 is set to 1.2 to 3.0 times the width W2 of the central portion. The wide portion 14 has a distance L from the edge line a of the transfer sheet to the inner end portion of 20 to 40.
The size of the foreign matter collecting member 1 in the longitudinal direction is set to be within the range of mm.

In the above structure, the transfer sheet conveyed from the sheet feeding unit (not shown) is supplied to the transfer area of the photosensitive drum 4 by the registration roller 2 at a predetermined timing, and the toner image on the photosensitive drum 4 is transferred. To be done. The transfer paper on which the toner image is fixed is conveyed to the fixing unit 6 and the toner image is heated and fixed, and then discharged onto a paper discharge tray (not shown).

Foreign matter such as paper powder attached to the peripheral surface of the photosensitive drum 4 when passing through the transfer area is removed by the foreign matter collecting member 1 when it reaches the installation portion of the foreign matter collecting member 1. Is retained. Further, when the peripheral surface of the photoconductor drum 4 passes through the installation portion of the foreign matter collecting member 1, the residual toner adhering to the peripheral surface is also removed and held by the foreign matter collecting member 1.

Since the foreign matter collecting member 1 for removing and holding the foreign matter such as paper dust attached to the photosensitive drum 4 is provided as described above, the foreign matter collecting brush for removing the foreign matter and the removed foreign matter are accommodated. It is possible to effectively collect the foreign matter on the photoconductor drum 4 with a simple structure, without taking any means such as providing a storage section. Therefore, the image formation is not performed in the state where the foreign matter remains on the photosensitive drum 4, and the deterioration of the image quality due to the formation of paper dust traces on the image is effectively prevented. You can Further, it is effective that the peripheral surface of the photoconductor drum 4 is damaged by foreign matter and the life of the photoconductor drum 4 is shortened, or that the foreign matter is mixed into the developing device 8 to cause aggregation of toner. Can be prevented.

Further, since the residual toner adhering to the photosensitive drum 4 can be removed by the foreign matter collecting member 1, a simple and compact structure is provided without providing a cleaning device for removing the residual toner.
It is possible to suppress the transfer of the residual toner onto the transfer paper or the occurrence of a so-called filming phenomenon, and there is an advantage that a high quality image can be formed.

When the amount of collected foreign matter corresponding to the number of formed images is compared between the side end portion and the central portion of the foreign matter collecting member 1, as shown in FIG. 3, the collected amount at the side end portion is the center. It has been confirmed by experiments that the number is significantly higher than that of the section. This is because, as shown in FIG. 4, the amount of the foreign matter generated is the largest in the vicinity of the edge line a of the transfer sheet where the distance from the edge line a to the inside is 0, and the foreign matter is larger than the edge line a. This is because the collection member 1 tends to gradually decrease toward the central portion side.

Therefore, as described above, the wide portion 14 having a larger width dimension than that of the central portion is provided at both left and right sides of the foreign matter collecting member 1 including the edge line of the transfer sheet, so that a part of the foreign matter collecting member 1 is provided. It is possible to prevent a situation in which a large amount of foreign matter is attached to the (side end portion) and the foreign matter collecting ability of this portion is saturated, and thus, the foreign matter collecting member 1 having the wide portion 14 prevents the foreign matter on the photosensitive drum 4. Also, it becomes possible to stably remove the residual toner and the like over a long period of time.

In particular, as shown in the above embodiment, the width W1 of the wide portions 14 provided on both left and right sides of the foreign matter collecting member 1 is 1.2 to 3.0 times the width W2 of the central portion. When set, the foreign matter collecting member 1 prevents foreign matter from being applied to the photosensitive drum 4 by excessive rotation resistance, and at the same time, the foreign matter collecting member 1 having the wide portion 14 removes foreign matter attached to the photosensitive drum. There is an advantage that it can be recovered stably over a long period of time.

That is, the width W1 of the wide portion 14
And a ratio of the width dimension W2 of the central portion to various values, and an experiment was conducted to compare the amount of foreign matter collected in the wide portion 14, the data shown in FIG. 5 were obtained. Until the ratio (W1 / W2) reaches about 1.2, the amount of foreign matter collected sharply increases as this ratio increases, and when the ratio exceeds 3.0, the amount of foreign matter collected is almost the same. It was confirmed that no change was seen.
From this data, by setting the width W1 of the wide portion 14 to 1.2 or more of the width W2 of the central portion, it is possible to sufficiently secure the foreign matter collecting ability by the wide portion 14, and The width W1 of the wide portion 14 is
It can be seen that the rotation resistance imparted by the contact of the foreign matter collecting member 1 with the photoconductor drum 4 can be suppressed to a certain value or less by setting the width W2 of the central portion to 3.0 times or less.

In the above embodiment, the distance L from the edge line a of the transfer sheet to the inner ends of the wide portions 14 provided on the left and right sides of the foreign matter collecting member 1 is 20 to 40.
Since the size of the wide portion 14 in the longitudinal direction of the foreign matter collecting member 1 is set to be within the range of mm, the installation range of the wide portion 14 is set to a necessary and sufficient value,
While preventing excessive rotation resistance from being applied to the photoconductor drum 4, the foreign matter collected on the photoconductor drum 4 can be stably collected by the foreign matter collection member 1 having the wide portion 14 for a long period of time. it can.

That is, as shown in FIG. 4, the amount of foreign matter generated in the longitudinal direction of the foreign matter collecting member 1 is greatest near the edge line a of the transfer sheet, and the foreign matter collecting member 1 is more than the edge line a. When the distance L from the edge line a is 20 mm or less, the amount of foreign matter is large, and when the distance L is over 40 mm, the amount of foreign matter is significantly changed. No, the amount is small. Therefore, the dimension of the wide portion 14 in the longitudinal direction of the foreign matter collecting member 1 is set so that the distance L from the edge line a of the transfer sheet to the inner end of the wide portion 1 is within the range of 20 to 40 mm. It is preferable. Thus, the minimum value L1 of the distance L is
By setting 20 mm to 20 mm, it is possible to sufficiently secure the foreign matter collecting capability of the wide portion 14, and
By setting the maximum value L2 of the distance L to 40 mm,
Rotational resistance generated when the foreign matter collecting member 1 contacts the photosensitive drum 4 can be suppressed to a certain value or less.

It should be noted that, as shown in FIG.
In addition, instead of the above embodiment in which an extension portion extending from the edge line a of the transfer sheet to the outer edge side is provided, the extension portion may be omitted, but the foreign matter flowing out of the edge line a In order to be able to remove effectively, it is preferable to have a structure provided with the above-mentioned extension having a length of about 10 to 20 mm.

Further, as shown in FIG. 1, there is provided a foreign matter collecting member 1a for removing and holding foreign matter such as paper powder adhered to the registration roller 2 provided in the transfer sheet conveying section. A wide portion 14 having a larger width dimension than the central portion may be provided on both left and right sides of 1a. According to this structure, foreign matter such as paper dust attached to the registration rollers 2 can be stably collected for a long period of time with a simple structure, and the foreign matter is conveyed to the image forming unit. It is possible to prevent the image formation from being adversely affected.

Further, the width dimension of the wide portion 14 provided on both left and right sides of the foreign matter collecting member 1a is set to 1.2 to 3.0 times the width dimension of the central portion, and the edge line of the transfer sheet is set. The distance from a to the inner ends of the wide portions 14 provided on the left and right sides of the foreign matter collecting member 1a is 20 to 20.
By setting the size of the wide portion 14 in the longitudinal direction of the foreign matter collecting member 1 so as to be within the range of 40 mm, it is possible to prevent an excessive rotation resistance from being imparted to the registration roller 2 and the like. There is an advantage that the foreign matter collecting member 1a having the wide portion 14 can remove and hold the foreign matter attached to the registration roller 2 and the like.

In the above embodiment, an example in which the wide portions 14 are provided at the terminal portions on both the left and right sides of the foreign matter collecting members 1 and 1a has been described, but as shown in FIG. The wide portion 14 may be provided in the vicinity of the terminal portion on both the left and right sides. Further, as shown in FIGS. 8 and 9, the wide portion 14 of the foreign matter collecting members 1, 1a is
The taper portion may be provided between the center portion and the center portion to gradually change the width dimension of the wide portion 14. further,
As shown in FIG. 10, the bulging portion of the wide portion 14 may be provided, for example, only on the downstream side in the rotation direction of the photosensitive drum 4 and the downstream side in the paper transport direction.

[0039]

As described above, according to the present invention, foreign matter such as paper dust adhered to the photosensitive drum rotating so as to sequentially pass through the charging area, the electrostatic latent image forming area, the developing area and the transfer area is eliminated. In the image forming apparatus and the process unit thereof, the image forming apparatus and the process unit include a foreign matter collecting member that removes and holds the foreign matter, or a foreign matter collecting member that removes and holds the foreign matter such as paper dust adhered to the roller provided in the transfer paper transport unit. A wide part with a larger width than the central part is provided in the part including the edge line of the transfer paper on both the left and right sides of the collecting member, so that foreign matter such as paper dust adhered to the photosensitive drum etc. can be lengthened with a simple structure. There is an advantage that it can be collected stably over a period.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a front view showing a specific configuration of a foreign matter collecting member.

FIG. 3 is a graph showing a correspondence relationship between the amount of foreign matter collected at the side end portion of the foreign matter collection member and the amount of foreign matter collected at the central portion.

FIG. 4 is a graph showing a correspondence relationship between the distance L of the wide portion and the amount of foreign matter generated.

FIG. 5 is a graph showing a correspondence relationship between a width dimension ratio between a side end portion and a central portion of a foreign matter collecting member and a foreign matter collection amount.

FIG. 6 is a graph showing a correspondence relationship between the number of formed images and the amount of foreign matter collected.

FIG. 7 is a front view showing another specific structure of the foreign matter collecting member.

FIG. 8 is a front view showing a more specific structure of the foreign matter collecting member.

FIG. 9 is a front view showing a more specific structure of the foreign matter collecting member.

FIG. 10 is a front view showing a more specific structure of the foreign matter collecting member.

[Explanation of symbols]

1 Foreign material collection member 2 rollers 4 photoconductor drum 5 process units 7 charger 8 developer 14 Wide part

Continuation of the front page (56) References JP 10-149073 (JP, A) JP 5-88591 (JP, A) JP 7-210044 (JP, A) Actual flat 4-67668 (JP , U) Actually open 3-43669 (JP, U) Actually open 63-38169 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 21/00 G03G 21/00 560 -578 G03G 21/10-21/12 G03G 15/16-15/16 103 B65H 5/00-5/38 G03G 15/00 510-534

Claims (5)

(57) [Claims] 1. A photosensitive drum that rotates so as to sequentially pass through a charging area, an electrostatic latent image forming area, a developing area, and a transfer area, and foreign matter such as paper dust attached to the photosensitive drum is removed and held. In the image forming apparatus including the foreign matter collecting member, a wide portion having a width dimension larger than that of the central portion is provided in a portion including the edge line of the transfer sheet on both left and right sides of the foreign matter collecting member. Image forming apparatus. 2. An image forming apparatus comprising: a roller provided in a transfer paper transport section; and a foreign matter collecting member that removes and holds foreign matter such as paper dust attached to the roller. An image forming apparatus characterized in that a wide portion having a width dimension larger than that of a central portion is provided in a portion including an edge line of a transfer sheet on both left and right sides. 3. The image forming apparatus according to claim 1, wherein the width of the wide portion provided on both left and right sides of the foreign matter collecting member is 1.2 to 3.0 times the width of the central portion. An image forming apparatus characterized by being set to. 4. The image forming apparatus according to claim 1, wherein a distance from an edge line of the transfer sheet to an inner end of a wide portion provided on both left and right sides of the foreign matter collecting member is An image forming apparatus characterized in that the size of the wide portion in the longitudinal direction of the foreign matter collecting member is set so as to fall within a range of 20 to 40 mm. 5. A photosensitive drum which rotates so as to sequentially pass through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, and a peripheral surface of the photosensitive drum which is disposed in the charging area and has a specific polarity. A charging device for charging the electrostatic latent image on the photoconductor drum into a toner image, and a developing device provided between the transfer region and the charging region. In a process unit of an image forming apparatus that is a unit of a foreign matter collecting member that removes and holds foreign matter such as paper dust attached to a drum, in a portion including the edge line of the transfer paper on the left and right sides of the foreign matter collecting member, A process unit of an image forming apparatus, wherein a wide portion having a width dimension larger than that of the portion is provided.