JP3485362B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an upper conveyance type electronic recording type image forming apparatus having a transfer means and a paper conveyance path on the upper side.

[0002]

2. Description of the Related Art In a conventional upper conveyance type image forming apparatus having a transfer means and a sheet conveyance path on the upper side of a photoconductor, a transfer roller and a sheet conveyance roller are provided on the upper structure side which is a part of the apparatus main body. The lower structure is provided with a photoconductor, a developing unit, a fixing unit, an optical writing unit, and a waste toner collecting unit. The upper structure is pivotally supported so as to be openable and closable, so that the sheet conveyance path located on the upper surface side inside the apparatus main body can be exposed.

[0003]

By the way, in this upper conveyance type image forming apparatus, since the toner image is transferred and conveyed on the lower surface side of the paper, the paper after the toner transfer comes into contact with the paper guide surface and the toner is transferred. There was a problem that the image was rubbed. Further, in the paper conveyance path from the transfer means to the fixing means, paper jams and paper jams are likely to occur, and it is necessary to open the upper structure and remove the paper each time, and the photoconductor is There is a problem that it is deteriorated by being exposed to external light, or is damaged by an external stimulus such as being touched by a hand or coming into contact with a tool.

For this reason, it has been proposed to provide a protective cover for the photoconductor interlocking with the upper structure.
The protective cover must be retracted from the position covering the photoconductor during image formation, and by providing the retracted position, the main body of the apparatus becomes large, and the protective cover scrapes the jammed paper while the photoconductor is rubbed. Since the protective cover becomes dirty, the user's hands may get dirty when the photoconductor, the waste toner container, the toner supply tank, etc. are attached or detached, or the inside of the main body of the device may be uncomfortable due to toner stains. There was a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which protects a photoconductor from external light and external stimuli and guides a toner image transferred onto a sheet during image formation so as to be protected.

[0006]

In order to achieve the above object, in the invention according to claim 1, an optical writing means is provided on the lower side of the photoconductor, and a transfer means and a sheet conveying path are provided on the upper side. In a transport-type image forming apparatus, one end of a link is attached to the front and rear positions of both end portions, and the other end of the link is attached to a stationary member such as an apparatus casing to open and close the upper structure formed in the apparatus main body. When the upper structure opens, it extends to cover the exposed portion of the photoconductor, and when the upper structure closes, it retracts from the exposed portion of the photoconductor to expose the exposed portion. A protective cover for guiding the paper is also provided, and
On the upper surface of the protective cover, a pair of ribs for supporting both end portions in the paper width direction are provided for each paper size to be used, and the ribs are sequentially raised as the paper size increases. .

Further, in the invention according to claim 2, the retreat of the protective cover is located on the rear side of the transfer means and on the front side of the fixing means, and the upper surface of the protective cover serves as a sheet fixing entrance guide. Is characterized by.

The invention according to claim 3 is characterized in that the retreat of the protective cover is positioned on the front side of the transfer means, and the upper surface of the protective cover serves as a transfer entrance guide for the sheet.

According to a fourth aspect of the present invention, in an upper conveyance type image forming apparatus in which an optical writing unit is provided on a lower side of a photoconductor and a transfer unit and a sheet conveyance path are provided on an upper side, front and rear sides of both side end portions are provided. One end of the link is attached to the position, the other end of the link is attached to an immovable member such as a device casing, and the bending operation is interlocked with the opening / closing operation of the upper structure formed in the device main body.
A protective cover that extends when the upper structure opens to cover the exposed portion of the photoconductor and retracts from the exposed portion of the photoconductor when the upper structure closes to expose the exposed portion and guide the paper. Ribs are provided on the upper surface of the protective cover, the ribs gradually increasing from the center in the paper width direction to the outside along the paper conveyance direction.

Further, in the invention according to claim 5, the retreat of the protective cover is located on the rear side of the transfer means and on the front side of the fixing means, and the upper surface of the protective cover serves as a fixing entrance guide for the sheet. Is characterized by.

Further, the invention according to claim 6 is characterized in that the retreat is located on the front side of the transfer means, and the upper surface of the protective cover serves as a transfer entrance guide for the sheet.

[0012]

According to the structure of the first aspect, a pair of ribs corresponding to a sheet size and supporting both ends in the width direction of the sheet are provided on the upper surface of the protective cover as the sheet width increases. By doing so, it is possible to prevent the portion of the lower surface of the sheet, which is the image forming area, from rubbing against the flat portion of the protective cover and the ribs of other sheet sizes, and reduce the sheet conveyance resistance. Therefore, it is possible to prevent the toner image in the image forming area from being rubbed and disturbed, and the transfer timing deviation, the image blurring, and the jitter, which are caused by the sheet being caught.

Further, according to the second aspect of the invention, the retreat of the protective cover is positioned in front of the fixing means and also serves as the fixing entrance guide, so that the sheet after transfer is smoothly guided to the fixing means. You can At the same time, by providing a rib corresponding to the paper size on the upper surface of the protective cover, it is possible to guide the conveyance without rubbing or disturbing the toner image transferred on the lower surface of the paper. Further, when the paper is jammed in front of the fixing means, the main body of the apparatus is opened to remove the paper, but at that time, since the protective cover operates in conjunction with the upper structure, the lower surface of the jammed paper is The top surface of the protective cover may be rubbed. At this time, the ribs can prevent the toner image in the image forming area on the lower surface of the paper from being rubbed or touched, so that toner scattering and contamination of the protective cover by the toner can be prevented.

According to the third aspect of the invention, the sheet can be properly guided to the transfer means by arranging the withdrawal of the protective cover in front of the transfer means and also serving as the transfer entrance guide. Further, since the ribs corresponding to the paper size are provided on the upper surface of the protective cover, the contact surface with the paper can be reduced, and the corresponding transfer resistance is eliminated, so that the paper can be transferred smoothly. Therefore, it is possible to prevent the leading edge of the sheet from being caught before the transfer, which leads to the deviation of the timing at the time of transfer, and further the prevention of image blur and jitter.

Further, according to the structure of the fourth aspect, since the ribs are provided on the upper surface of the protective cover so as to be gradually increased from the center to the outside in the paper width direction along the paper conveyance direction, Even at the paper size, both widthwise end portions can be supported, and the widthwise direction can be restricted so that the paper does not skew. Therefore, the image forming area on the lower surface of the paper is the flat portion of the protective cover and other paper sizes. The ribs are not rubbed, and the paper transport resistance can be reduced. Therefore, it is possible to prevent the toner image in the image forming area from being rubbed and disturbed, and the transfer timing deviation, the image blurring, and the jitter, which are caused by the sheet being caught.

According to the structure of claim 5, the retreat of the protective cover is positioned in front of the fixing means and also serves as the fixing entrance guide, so that the sheet after transfer is smoothly guided to the fixing means. You can At the same time, on the upper surface of the protective cover, along the paper transport direction,
Since the ribs which are sequentially raised from the center in the paper width direction to the outside are provided, the toner image transferred to the image forming area on the lower surface of the paper can be rubbed or disturbed on the flat portion of the protective cover and other ribs. Disappear. Further, when the paper is jammed in front of the fixing means, the main body of the apparatus is opened to remove the paper, but at that time, since the protective cover operates in conjunction with the upper structure, the lower surface of the jammed paper is The top surface of the protective cover may be rubbed. At this time, the ribs can prevent the toner image on the lower surface of the paper from rubbing or touching, so that toner scattering and contamination of the protective cover by the toner can be prevented.

Further, according to the structure of the sixth aspect, by arranging the retreat of the protective cover in front of the transfer means and also serving as the transfer entrance guide, the paper can be properly guided to the transfer means, and By providing ribs on the upper surface of the protective cover, which are sequentially increased from the center to the outside in the paper width direction along the paper conveyance direction, the conveyance resistance with the paper can be reduced and the paper does not skew. Since the width direction can be regulated, the paper can be smoothly and properly conveyed. Therefore, it is possible to prevent the leading edge of the paper sheet from being caught before the transfer, which leads to the deviation of the timing at the time of transfer, and further the prevention of the image blur and the jitter.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an image forming apparatus according to an embodiment of the present invention. Reference numeral 1 denotes an apparatus main body, which includes an upper structure 1a and a lower structure 1b. The upper structure 1a is pivotally supported on the lower structure 1b by an axis X so as to be openable and closable. 2 is a photoconductor, around the charging means 3,
A developing unit 4, a transfer unit 5, a cleaning unit 6, and an optical writing unit 8 for forming a latent image on the photoconductor 2 are provided. Reference numeral 9 denotes a paper feed cassette containing a paper P therein. The paper P is fed out by a paper feed roller 10 and conveyed to the upper side of the photoconductor 2 in synchronization with the registration roller 11. The photoconductor 2 rotates in the direction of the arrow, is uniformly charged by the charging means 3, and then is irradiated with the laser beam from the optical writing means 8 to form an electrostatic latent image. This electrostatic latent image is visualized by the toner of the developing means 4. The visible image of the toner is transferred to the lower surface of the paper P conveyed to the upper side of the photoconductor 2 by the transfer means 5, and further fixed by the fixing means 7. The paper P sent out from the fixing means 7 is stacked on the paper discharge tray 13 by the paper discharge rollers 12.

Reference numeral 20 is a protective cover for covering a part of the photosensitive member 2, and ribs 21 are formed on the upper surface thereof. In FIG. 1, the protective cover 20 is at a position that covers the photoconductor 2 and the upper structure 1a is open. The protective cover 20 is supported by a pair of links 20a and 20b at both ends thereof, and the links 20a, 2b
The other end of 0b is engaged with a side plate of a photoconductor unit (not shown) or a shaft provided on the side plate of the apparatus main body 1. The protective cover 20 is always biased by a spring member (not shown) in a direction to cover the photoconductor 2. Reference numeral 16 denotes an abutting portion formed on the upper structure 1a, which abuts the opening / closing receiving portion 20c of the protective cover 20 when the upper structure 1a is closed, so that the protective cover 20 is covered from the position where the photoconductor 2 is covered. It is designed to be moved in the evacuation direction.

FIG. 2 shows a sectional view of the protective cover of the first embodiment of the present invention. This cross section is taken along the paper width direction of the protective cover 20, and each paper size A4, B4, A3.
Is provided with a pair of ribs 21a, 21b, 21c, which sequentially increase in height from the inside to the outside. Therefore, when the paper of the paper size A3 is guided, it is carried without touching the heads of the ribs 21a and 21b.

FIG. 3 is a configuration diagram of the retracted position of the protective cover according to the second embodiment of the present invention. When the upper structure 1a is closed, the protective cover 20 is retracted from the position covering the photoconductor 2 to the position in front of the fixing unit 7. At the retracted position, the upper surface of the protective cover 20 functions as a fixing entrance guide that guides the sheet to the fixing unit 7. Since a pair of ribs 21a, 21b, 21c corresponding to the respective paper sizes A4, B4, A3 are provided on the upper surface while increasing the height from the inner side to the outer side, the toner image formed on the lower surface of the paper is rubbed. Or you can guide to the fixing entrance without breaking. When the paper jams before the fixing unit 7 or in the upper transport path, the upper structure 1 is used to remove the paper.
a is opened, but at that time, since the protective cover 20 operates in conjunction with the upper structure 1a, the protective cover 20 slides on the lower surface of the sheet after the toner transfer, and the protective cover 20 moves to the photosensitive member 2a.
Move to the position covered by. At this time, the ribs 21 prevent the toner image in the image forming area on the lower surface of the paper from rubbing or touching, so that toner scattering and contamination of the protective cover by the toner can be prevented.

FIG. 4 is a configuration diagram of the retracted position of the protective cover according to the third embodiment of the present invention. When the upper structure 1a is closed, the protective cover 20 is retracted from the position covering the photoconductor 2 to the position in front of the transfer means. At the retracted position, the upper surface of the protective cover 20 functions as a transfer entrance guide that guides the sheet to the transfer unit. A pair of ribs 21 corresponding to each paper size A4, B4, A3 is provided on the upper surface.
Since the heights a, 21b, and 21c are sequentially increased from the inner side to the outer side, the contact surface with the paper can be reduced, and the conveyance resistance corresponding to that can be eliminated, so that the paper can be smoothly conveyed. Therefore, it is possible to prevent the leading edge of the sheet from being caught before the transfer, and prevent the timing deviation during the transfer. Therefore, problems such as image blurring and jitter can be prevented.

Reference numeral 17 denotes a pressing portion 17 provided on the upper structure 1a, which, when the upper structure 1a is closed from the open state, hits the head of the opening / closing receiving portion 20c of the protective cover 20, The protective cover 20 is moved along the contour of the pressing portion 17 in the direction of retracting from the position covering the photoconductor 2.

FIG. 5 shows a sectional view of a protective cover according to a fourth embodiment of the present invention. This cross section is taken along the paper width direction of the protective cover 30.
The ribs 31 are provided so as to become higher from the center in the paper width direction toward the outside. By forming the ribs 31, it is possible to prevent the image forming area, which is the lower surface portion of the sheet, from being touched, and also it is possible to reduce the conveyance resistance of the sheet. Furthermore, when guiding the paper at the position where the protective cover is retracted, any paper size, such as a postcard, can support both widthwise ends thereof, and the widthwise regulation is performed so that the paper does not skew. You can also

The retracted position of the protective cover according to the fifth embodiment of the present invention is the same as that shown in FIG. However, the formation of the upper surface of the protective cover is different. This protective cover 30
When the upper structure 1a is closed, the upper structure 1a is retracted from the position covering the photoconductor 2 to the position before the fixing unit. At this retracted position, the upper surface of the protective cover 30 functions as a fixing entrance guide for guiding the sheet to the fixing means. Ribs 31 are provided on the upper surface in order of increasing height from the center in the paper width direction to the outside along the paper conveyance direction. By forming the ribs 31, when guiding the paper at the position where the protective cover is retracted, both widthwise end portions of any paper size can be supported, and the widthwise regulation is performed so that the paper does not skew. You can also When the sheet jams before the fixing unit 7 or in the upper conveyance path, the upper structure 1a is opened to remove the sheet, and at that time, the protective cover 30 operates in conjunction with the upper structure 1a. Therefore, the protective cover 30 moves to the position covered by the photoconductor 2 while sliding on the lower surface of the sheet after the toner transfer.
At this time, the ribs 31 can regulate the toner image in the image forming area on the lower surface of the paper so as not to rub or touch it and skew in the width direction. The cover can be reliably prevented from becoming dirty.

The retracted position of the protective cover according to the sixth embodiment of the present invention is the same as that shown in FIG. However, the formation of the upper surface of the protective cover is different. This protective cover 30
When the upper structure 1a is closed, the upper structure 1a is retracted from the position covering the photoconductor 2 to the position before the transfer means 5. At the retracted position, the upper surface of the protective cover 30 functions as a transfer entrance guide that guides the sheet to the transfer unit 5. Ribs 31 are provided on the upper surface in order of increasing height from the center in the paper width direction to the outside along the paper conveyance direction.
By forming the ribs 31, when guiding the paper at the position where the protective cover is retracted, both widthwise end portions of any paper size can be supported, and the widthwise regulation is performed so that the paper does not skew. Since it is also possible to reduce the contact surface with the paper, the conveyance resistance is eliminated, and the paper can be smoothly conveyed. Therefore, it is possible to prevent the leading edge of the sheet from being caught before the transfer, prevent the timing deviation at the time of transfer, and prevent image blurring and jitter.

The heads of the ribs formed on the upper surface of the protective cover may be stepped to regulate the paper width direction to prevent skew of the paper.

The upper surface of the protective cover may be formed in a step shape from the center in the paper width direction to the outside.

[0030]

According to the inventions of claims 1 and 4,
Since the pair of ribs are provided according to the paper size, the toner image transferred to the lower surface of the paper does not rub against the flat portion of the protective cover and the ribs of other paper sizes.
Therefore, a high-quality recorded image can be obtained without disturbing the toner image formed on the lower surface of the paper, and toner scattering and adhesion can be prevented. Further, it is possible to reduce the conveyance resistance of the paper and reduce the occurrence of jam. Further, the strength of the protective cover can be improved.

Further, according to the second and fifth aspects of the invention, since the retraction of the protective cover is positioned before the fixing, it is possible to prevent rubbing or disturbing the unfixed toner image formed on the lower surface of the paper. Further, it is possible to prevent the occurrence of defects such as image blur and jitter, and obtain a high quality recorded image. Further, when the jam is processed, it is possible to prevent the protective cover from being soiled or the toner from scattering. Further, the transport path can be simplified and the cost can be reduced.

Further, according to the third and sixth aspects of the invention, since the retreat of the protective cover is positioned before the transfer, the sheet can be smoothly guided to the transfer position, the jam can be reduced, and the transfer timing can be further improved. Since it is possible to prevent misalignment of the image, image misalignment, image distortion, blurring,
High quality recorded images can be obtained by eliminating jitter.
In addition, the transport path can be simplified and the cost can be reduced.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a protective cover according to a first embodiment of the present invention.

FIG. 3 is a configuration diagram of a retracted position of a protective cover according to second and fifth embodiments of the present invention.

FIG. 4 is a configuration diagram of a retracted position of a protective cover according to third and sixth embodiments of the present invention.

FIG. 5 is a sectional view of a protective cover according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 ... Device body 2 ... Photoconductor 3 ... Charging means 4 ... Developing means 5 ... Transferring means 6 ... Cleaning means 7: fixing means 8 ... Optical writing means 9 ... Paper feed cassette 10 ... Paper feed roller 11 ... Registration roller 12 ... Ejection roller 13 ... Paper ejection tray 15 ... Transport guide plate 16… Pointing part 20, 30 ... Protective cover 17 ... Pushing part 20a, 20b, 30a, 30b ... Link part 20c, 30c ... Open / close receiving part 21, 31 ... Ribs

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Claims (6)

(57) [Claims] 1. An upper conveyance type image forming apparatus in which an optical writing unit is provided on the lower side of a photoconductor and a transfer unit and a sheet conveyance path are arranged on the upper side, and one end of a link is attached to the front and rear positions of both side end portions. The other end of the link is attached to an immovable member such as an apparatus housing, and bends in conjunction with the opening / closing operation of the upper structure formed in the apparatus body. When the upper structure opens, the link extends and extends. A protective cover is provided which covers the exposed portion of the body, retracts from the exposed portion of the photoconductor when the upper structure is closed, exposes the exposed portion, and guides the paper, and the upper surface of the protective cover. To
An image forming apparatus characterized in that a pair of ribs for supporting both end portions in the paper width direction are provided for each paper size to be used, and the ribs are sequentially raised as the paper size increases. 2. The image forming apparatus according to claim 1, wherein the retreat is located on the rear side of the transfer means and on the front side of the fixing means, and the upper surface of the protective cover serves as a fixing entrance guide for the sheet. apparatus. 3. The image forming apparatus according to claim 1, wherein the retreat is located on the front side of the transfer unit, and the upper surface of the protective cover serves as a transfer entrance guide for paper. 4. An upper conveyance type image forming apparatus having an optical writing unit on the lower side of a photosensitive member and a transfer unit and a sheet conveying path on the upper side, wherein one end of a link is attached to the front and rear positions of both side end portions. The other end of the link is attached to an immovable member such as an apparatus housing, and bends in conjunction with the opening / closing operation of the upper structure formed in the apparatus body. When the upper structure opens, the link extends and extends. A protective cover is provided which covers the exposed portion of the body, retracts from the exposed portion of the photoconductor when the upper structure is closed, exposes the exposed portion, and guides the paper, and the upper surface of the protective cover. An image forming apparatus characterized in that a rib that is gradually increased from the center in the paper width direction to the outside is provided along the paper conveyance direction. 5. The image forming apparatus according to claim 4, wherein the retreat is located on the rear side of the transfer means and on the front side of the fixing means, and the upper surface of the protective cover serves as a fixing entrance guide for the sheet. apparatus. 6. The image forming apparatus according to claim 4, wherein the retreat is located on the front side of the transfer unit, and the upper surface of the protective cover serves as a transfer entrance guide for the sheet.