JP3852610B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a configuration of an image forming apparatus including a recording paper skew prevention device that includes a registration roller, a press roller that presses against the registration roller, and a pressing member that presses the press roller toward the registration roller.

  2. Description of the Related Art Conventionally, an image forming apparatus picks up a recording sheet from a sheet feeding cassette by a sheet feeding roller, conveys the recording sheet to the position of a developing machine, and transfers the toner image formed on the photosensitive member to the recording sheet. Forming. The paper picked up from the paper feed cassette collides the leading edge with the registration roller and press roller joint and presses it from the back, so that the leading edge of the paper matches the joint of the two types of rollers and skews the recording paper. It is preventing. (For example, see Patent Document 1)

As shown in FIG. 3, conventionally, the registration roller 121 is pivotally supported on the main body side of the image forming apparatus 101 via a bearing 128, and the press roller 122 is pivotally supported on an exterior cover (jam access cover) 107. . Further, an elastic member 123 is attached to the exterior cover 107, and the elastic member 123 is disposed so as to press the press roller 122 toward the registration roller 121 in a state where the exterior cover 107 is closed.
The bearing 128 that supports the registration roller 121 is formed with a recess 128b at a substantially central portion in the vertical direction on the exterior cover 107 side. When the exterior cover 107 is closed, the shaft portion 125 of the press roller 122 is The press roller 122 was positioned by fitting into the recess 128b.

A slope 128c is formed above the recess 128b, and the slope 128c is used as a guide for the press roller 122 when the exterior cover 107 is opened and closed. The inclination 128 c is formed so as to be substantially along the movement locus A of the shaft portion 125 around the rotation shaft 175 so that the opening of the exterior cover 107 is not restricted by the shaft portion 125.
With this configuration, when the exterior cover 107 is opened and closed, the press roller 122 and the elastic member 123 rotate about the rotation axis of the exterior cover 107. Therefore, when performing the jam processing, when the exterior cover 107 is opened, the nip between the registration roller 121 and the press roller 122 can be released. For example, the recording paper sandwiched between the registration roller 121 and the press roller 122 is removed. We were able to.

Japanese Patent Laid-Open No. 5-289564

However, in the conventional image forming apparatus, a press roller is pivotally supported on the exterior cover side, and when the exterior cover is opened and closed, the shaft portion of the press roller moves along the recess and the inclination of the bearing. Therefore, when the exterior cover is opened and closed, the shaft portion of the press roller interferes with the concave portion and the inclination of the bearing, and it is difficult to open and close the exterior cover.
Further, if the bearing has a shape that facilitates the opening and closing operation of the exterior cover, the positioning of the press roller is incomplete, the nip between the registration roller and the press roller is incomplete, and the skew of the recording paper is prevented. I can't. As a result, there is a problem that the image transfer timing is shifted, and characters transferred to the recording paper are shifted.
Accordingly, the present invention provides an image forming apparatus in which the positioning of the press roller with respect to the registration roller is ensured while facilitating jamming as a configuration that facilitates opening and closing the exterior cover.

  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

That is, in claim 1,
A recording paper skew prevention device having a registration roller, a press roller in pressure contact with the registration roller, and a pressing member that presses the press roller toward the registration roller, and an exterior cover mounted on the main body so as to be opened and closed ,
In the image forming apparatus in which the registration roller is disposed on the recording paper conveyance path exposed to the outside when the exterior cover is opened,
A guide portion for positioning the press roller with the exterior cover closed is provided in the main body, the registration roller and the press roller are supported on the main body, and the pressing member is supported on the outer cover ,
The pressing member is a leaf spring that presses the left and right central portions of the shaft portion of the press roller .

  According to a second aspect of the present invention, the guide direction of the guide portion is set to a direction perpendicular to the recording paper conveyance path of the image forming apparatus.

  According to a third aspect of the present invention, the guide portion is provided on a support member of the registration roller and serves as a bearing for the press roller.

  By configuring as in claim 1, the press roller does not rotate in conjunction with the exterior cover when the exterior cover is opened and closed, so that the press roller and the support member of the press roller do not interfere with each other, and the exterior The cover can be easily opened and closed, and jamming can be easily performed. Moreover, the positioning of the press roller when the exterior cover is closed by the exterior cover opening / closing operation does not become incomplete. That is, the press roller and the registration roller are completely nipped, and the skew of the recording paper can be surely prevented.

  By configuring as described in claim 2, the shape of the guide portion can be made simple and the cost can be reduced. Further, since the shape of the guide portion is a straight path, when the press roller 22 is pushed by the elastic member by closing the exterior cover, it moves smoothly without shaking between the guide portion.

  By configuring as described in claim 3, the number of parts can be reduced and the cost can be reduced.

Next, the best mode for carrying out the invention will be described with reference to the accompanying drawings.
FIG. 1 is a sectional side view showing an embodiment of an image forming apparatus to which the present invention is applied, FIG. 2 is a schematic plan view showing a skew feeding preventing apparatus for recording paper, and FIG. 3 is a sectional view of a conventional image forming apparatus. It is a side view. In this embodiment, the direction of arrow A in FIG.
The image forming apparatus of this embodiment is configured in an electrophotographic system, and is applied to, for example, a printer, a copier, and a facsimile.

  As shown in FIG. 1, the image forming apparatus 1 is disposed above the paper feed cassette 5. The image forming apparatus 1 transfers image information onto a recording sheet carried from the paper feed cassette 5, fixes the image information, and performs image fixing. The recording paper is discharged to a paper discharge tray (not shown) provided at the top of the forming apparatus 1. An exterior cover (jam access cover) 7 is provided at the rear portion of the image forming apparatus 1 so as to be openable and closable with respect to the apparatus main body 1a. When the outer cover 7 rotates about a rotation shaft 75 provided at the lower rear of the image forming apparatus 1, one side of the image forming apparatus 1 is opened. Normally, the exterior cover 7 is locked and closed by a stopper or the like (solid line in FIG. 1). However, when the jam treatment is performed, the exterior cover 7 is opened (dashed line in FIG. 1). ).

The configuration of the image forming apparatus 1 will be described.
Inside the image forming apparatus 1, there is formed a recording paper transport path for transporting the recording paper fed from the paper feed cassette 5 to a paper discharge tray disposed at the top of the image forming apparatus 1. When the outer cover 7 is closed, there is a gap between the apparatus main body 1a and the outer cover 7, and the recording paper transport path 9 is formed in this gap.

The recording paper transport path 9 is formed from the upstream paper feed cassette 5 through the image forming unit toward the downstream paper discharge tray.
In this recording paper conveyance path 9, in order from the upstream side to the downstream side, a paper feed roller 52, a registration roller 21, a press roller 22, a photosensitive drum 31, and a transfer drum provided near the paper feed port of the paper feed cassette 5. A roller 32, a heat roller 41, a press roller 42, and a paper discharge roller (not shown) provided near the paper discharge port to the paper discharge tray are arranged.

The registration roller 21 is disposed above the paper feed cassette 5, and a press roller 22 is disposed so as to contact the outer peripheral surface of the registration roller 21. The registration roller 21, the press roller 22, and will be described later. The elastic member 23 and the like constitute a recording paper skew feeding prevention device.
The skew feeding prevention device is for preventing the skew feeding of the recording paper picked up from the paper feeding cassette 5, and the recording paper picked up from the paper feeding cassette 5 at the joint of the registration roller 21 and the press roller 22. And press from below to align the leading edge of the paper with the joint between the two types of rollers, straighten the recording paper transport direction, and transport the recording paper with corrected skew to the downstream side. I am doing so.
Further, the registration roller 21 and the press roller 22 are rotatably supported by the apparatus main body 1a via a support member 28 described later.

The photosensitive drum 31 is disposed above the registration roller 21, and a transfer roller 32 is disposed so as to contact the outer peripheral surface of the photosensitive drum 31.
The photosensitive drum 31 forms an electrostatic latent image by an exposure device (not shown) that performs exposure based on image information, and the photosensitive drum 31 on which the electrostatic latent image is formed and a thin toner layer are carried. A toner image is formed on the photosensitive drum 31 by sliding contact with the developed developing roller (not shown), and this toner image is transferred onto the recording paper by the transfer roller 32.
The photosensitive drum 31 is rotatably supported by the apparatus main body 1a. On the other hand, the transfer roller 32 is rotatably supported by the exterior cover 7, and the transfer roller 32 rotates about the rotation shaft 75 by opening and closing the exterior cover 7.

The heat roller 41 is disposed above the photosensitive drum 31, and a press roller 42 is disposed so as to contact the outer peripheral surface of the heat roller 41.
A halogen lamp 43 or the like as a heat source is provided at the axial center position in the heat roller 41, and heat generated by the halogen lamp 43 is transmitted to the outer peripheral portion of the heat roller 41. The heat roller 41 and the press roller 42 sandwich and convey the recording paper holding the toner image along the conveyance path while heating and pressurizing, and fix the toner image on the recording paper as a permanent image.
The heat roller 41 is rotatably supported by the apparatus main body 1a. On the other hand, the press roller 42 is rotatably supported by the exterior cover 7, and the press roller 42 revolves around the rotation shaft 75 when the exterior cover 7 is opened and closed.

When the outer cover 7 is closed, a recording paper conveyance path 9 is formed in the image forming apparatus 1, and each roller pair is disposed opposite to the recording paper conveyance path 9. The recording paper is nipped and conveyed along the recording paper conveyance path 9 by each roller pair.
That is, a nip portion is formed on each roller pair so that a predetermined nip pressure is applied. Specifically, a nip portion between the registration roller 21 and the press roller 22 pair, a nip portion between the photosensitive drum 31 and the transfer roller 32 pair, and a nip portion between the heat roller 41 and the press roller 42 pair are formed.
Further, the recording paper conveyance path 9 is exposed to the outside when the outer cover 7 is opened. When the recording paper is jammed in the recording paper conveyance path 9, the outer cover 7 is opened to remove the jam. Like to do.

Next, the support structure of the registration roller 21 and the press roller 22 of the present invention will be described.
As shown in FIGS. 1 and 2, the registration roller 21 and the press roller 22 are rotatably supported by the apparatus main body 1 a via support members 28 and 28.
The support members 28 and 28 are provided in the vicinity of both end portions of the shaft portions 24 and 25 of the registration roller 21 and the press roller 22, and are disposed at two positions on the left and right of the apparatus main body 1a and attached to the apparatus main body 1a. .

The support member 28 has a bearing hole 28 a of the registration roller 21 and a guide hole 28 b of the press roller 22, and the guide hole 28 b guides the positioning of the press roller 22 with the exterior cover 7 being closed. Has become a department.
The shaft portion 24 of the registration roller 21 disposed in the left-right direction of the apparatus main body 1a is inserted into the bearing hole 28a of the support member 28. The shaft portion 24 is rotatably supported in the bearing hole 28a, and movement in the axial direction is restricted by E-rings 27 attached to both ends. A bearing may be provided between the bearing hole 28a and the shaft portion 24 so that the shaft portion 24 can be easily rotated.
.. Are provided between the left and right support members 28, 28 of the shaft portion 24, and the registration rollers 21, 21. Rotate integrally with 24.

The guide hole 28b of the support member 28 is formed in the support member 28 in a direction substantially perpendicular to the recording paper conveyance path 9 (in the front-rear direction in this embodiment), and in the guide hole 28b, the press roller 22 is formed. The shaft portion 25 is inserted. The shaft portion 25 is rotatably supported by the support member 28, and movement in the axial direction is restricted by an E ring 27 attached to the shaft portion 25. A bearing may be provided between the guide hole 28b and the shaft portion 25 so that the shaft portion 25 can be easily rotated.
The guide hole 28b functions as a bearing that supports the shaft of the press roller 22 so as not to drop off. Therefore, the support member 28 is configured not only to position the press roller 22 in a state in which the exterior cover 7 is closed, but also to use both the bearing of the registration roller 21 and the bearing of the press roller 22.

The guide hole 28b can be inserted into the shaft portion 25 of the press roller 22 and the shaft portion 25 can move to a position where the nip between the registration roller 21 and the press roller 22 can be released when the outer cover 7 is opened. Is formed. In the present embodiment, the guide hole 28b is formed in a rectangular shape in a side view that is long in the front-rear direction (a direction substantially perpendicular to the recording paper conveyance path).
That is, the guide direction of the guide hole 28 b is set to be substantially perpendicular to the recording paper conveyance path 9 of the image forming apparatus 1.
.. Are provided between the left and right support members 28, 28 of the shaft portion 25, and the press rollers 22, 22. And rotate together.

Further, the shaft portion 25 of the press roller 22 is pressed by the elastic member 23 in a state in which the exterior cover 7 is closed. In the present embodiment, a plate spring is used as the elastic member 23, and the elastic member 23 is disposed at the left and right center portion of the shaft portion 25.
The elastic member 23 serving as a pressing member of the press roller 22 is attached to the exterior cover 7 side. When the exterior cover 7 is opened, the elastic member 23 rotates about the rotation shaft 75 and the shaft portion. 25 is released. That is, the nip between the registration roller 21 and the press roller 22 can be released when the exterior cover 7 is opened.

With such a configuration, when the exterior cover 7 is opened for jam processing, the pressing of the elastic member 23 is released, and the shaft portion 25 of the press roller 22 becomes movable in the guide hole 28b. Therefore, the nip between the registration roller 21 and the press roller 22 can be released, and for example, the recording paper sandwiched between the registration roller 21 and the press roller 22 can be removed.
On the other hand, when closing the exterior cover 7, the shaft portion 25 of the press roller 22 is pressed by the elastic member 23 provided in the exterior cover 7, and moves toward the registration roller 21 along the guide hole 28 b of the support member 28. Moving. The registration roller 22 is disposed at an appropriate position, that is, a position where a nip portion is formed between the registration roller 21 and the press roller 22 and a predetermined nip pressure is applied.

With the above configuration, when the exterior cover 7 is opened and closed, the press roller 22 and the shaft portion 25 do not rotate around the rotation shaft 75 in conjunction with the exterior cover 7. The support member 28 of the press roller 22 does not interfere with each other, and the exterior cover 7 can be easily opened and closed, so that jamming can be easily performed.
A guide hole 28b which is a guide portion is provided on the main body side of the image forming apparatus 1, and the outer cover 7 is closed by positioning the press roller 22 with the outer cover 7 closed by the guide hole 28b. In this case, the shaft portion 25 of the press roller 22 can be disposed at a predetermined position by the guide hole 28b so that the press roller and the registration roller are completely nipped, and the skew of the recording paper can be ensured. Can be prevented.
Further, by setting the guide direction of the guide hole 28b to be substantially perpendicular to the recording paper conveyance path 9 of the image forming apparatus 1, the shape of the guide hole 28b can be made simple and low cost. Can be achieved. Further, since the shape of the guide hole 28b is a straight path, when the press roller 22 is pushed by the elastic member 23 by closing the exterior cover 7, it does not rattle with the guide hole 28b and moves smoothly. To do.
Further, by providing the guide hole 28b in the support member 28 of the registration roller 21 and also serving as a bearing for the press roller 22, the support member 28 is a press for arranging the press roller 22 at an appropriate position. It can be used not only as a positioning member for the roller 22 but also as a bearing for the shaft portions 24 and 25 of the registration roller 21 and the press roller 22, thereby reducing the number of parts and reducing the cost.

1 is a cross-sectional side view showing an embodiment of an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic plan view showing a recording paper skew prevention device. FIG. 6 is a cross-sectional side view of a conventional image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1a Apparatus main body 7 Exterior cover 9 Recording paper conveyance path 21 Registration roller 22 Press roller 23 Elastic member (pressing member)
28 Support member 28b Guide hole (guide part)

Claims (3)

A recording paper skew prevention device having a registration roller, a press roller in pressure contact with the registration roller, and a pressing member that presses the press roller toward the registration roller, and an exterior cover mounted on the main body so as to be opened and closed ,
In the image forming apparatus in which the registration roller is disposed on the recording paper conveyance path exposed to the outside when the exterior cover is opened,
A guide portion for positioning the press roller with the exterior cover closed is provided in the main body, the registration roller and the press roller are supported on the main body, and the pressing member is supported on the outer cover ,
The pressing member is a leaf spring that presses the left and right center portion of the shaft portion of the press roller.
An image forming apparatus.   The image forming apparatus according to claim 1, wherein a guide direction of the guide portion is set to a direction substantially perpendicular to a recording paper conveyance path of the image forming apparatus.   The image forming apparatus according to claim 1, wherein the guide portion is provided on a support member of the registration roller and serves also as a bearing of a press roller.

Images