JP3501592B2 - Sheet conveying apparatus and image forming apparatus having the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device for conveying a sheet along a plurality of curved guide ribs, and an image forming apparatus equipped with the sheet conveying device.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 9, an image forming apparatus such as a printer is provided with a paper feed tray 3 at a lower portion of an apparatus main body 2 and an ejected paper stack tray 7 on an upper surface of the apparatus main body 2. Then, there was one configured to make the installation area as small as possible.

Sheet conveyance in this image forming apparatus is
The sheet feeding unit 4 and the sheet discharging unit 6 are provided with curved conveying paths, and the sheet is configured to draw an S-shape during the process from the paper feeding to the paper discharging. Regarding the sheet discharge section 6, the outside and inside of the curved path of the conveyance path are constituted by a sheet guide 34 and an inside guide 29, respectively. Here, since the image surface of the sheet faces the inside of the curve, the sheet conveying speed of the conveying roller 30 is set slightly higher than that of the discharging roller 32 so as not to rub the image surface on the inner guide.
The back surface of the sheet is designed to slide on the sheet guide 34 outside the conveyance path. Further, the sheet guide 34 has its conveying surface formed by a plurality of curved guide ribs 35 made of a resin material or the like. And FIG. 10 and FIG.
As shown in FIG. 5, the sheet guide surface 36 of the guide rib 35 is formed so that the surface thereof is as smooth as possible so that the leading edge of the sheet is not caught and the sheet can be conveyed smoothly.

[0004]

However, in the above conventional example, when a sheet such as an OHP sheet having a very smooth surface is conveyed along the curved sheet guide surface 36, the sheet is near the curved portion of the rib. When the sheet is strongly pressed against the sheet guide surface 36, the sheet guide surface 36 comes into close contact with the sheet guide surface 36, which may cause a sheet jam as shown in FIG. In addition, even when an image is further formed on the front surface of the sheet that has already been imaged on the back surface (during double-sided printing), an abnormal sliding noise occurs because the toner-fixed portion on the back surface easily adheres to the rib surface. There was something to do.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cutout portion on the sheet guide surface of the guide rib to reduce the contact area between the sheet guide surface and the sheet surface, and to prevent the occurrence of sheet jam and sliding noise. An object is to provide an image forming apparatus including the same.

[0006]

In order to achieve the above object, a sheet conveying apparatus according to the first invention of the present application has a curved sheet guide surface integrally, and is arranged in the sheet conveying direction.
A plurality of guide members provided with a plurality of guide members, and a conveyance roller that guides a sheet to the plurality of guide members, and the sheet conveyance direction by the conveyance rollers is reversed by a predetermined angle by the plurality of guide members to convey the sheet. In the sheet conveying device for performing the above, the sheet guide surface of the guide member is provided with a cutout portion that does not contact the sheet being conveyed.

A sheet conveying device according to a second invention of the present application is the sheet conveying device according to the first invention, wherein the plurality of guide members are connected to each other.
The position of the notch of the adjacent guide member in the transport direction.
In, the feature is that they are shifted.

In the sheet conveying apparatus according to the third invention of the present application, each of the guide members in the first or second invention is a plate-shaped member, and a curved sheet of a plurality of juxtaposed guide members. The guide surface is characterized by forming a plane perpendicular to the sheet conveying direction.

In the sheet conveying apparatus according to the fourth invention of the present application, the conveying roller according to the first or second invention is provided below the guide member, and the sheet conveyed by the conveying roller is a guide. It is characterized in that a predetermined angle is reversed while being guided upward from below the sheet guide surface of the member.

An image forming apparatus according to a fifth aspect of the present invention is the sheet conveying apparatus according to any one of the first to fourth aspects,
An image forming unit for forming an image on a sheet is provided.

[0011]

Based on the above means, when a sheet such as an OHP sheet having a very smooth front surface or a sheet having an image formed on the back surface is conveyed along a curved guide rib, the contact area between the sheet and the rib surface is Since the contact is reduced and the contact is intermittent, it is difficult for the sheet to adhere to the rib surface, and sheet jam and abnormal sliding noise are prevented from occurring.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

In the present description, a laser beam type printer as shown in FIG. 3 will be described as an example of an image forming apparatus having a sheet conveying apparatus. The printer 1 includes a paper feed cassette 3, a sheet feeding unit 4, an image forming unit 5, and a sheet discharging unit 6 as a sheet conveying device, which are detachably attached to the lower portion of the apparatus main body 2, and are provided on the upper portion of the apparatus main body 2. Is provided with a sheet stacking unit 7 for stacking sheets on which images are formed and discharged.

The image forming section 5 is provided with a laser scanner 11, a reflection mirror 12, a process cartridge 13, a transfer roller 14, a carrier 15, and a fixing device 16.

Inside the process cartridge 13, a developing device 18, a charging roller 19, a cleaner 20, etc. are provided around the photosensitive drum 17, and the light emitted from the laser scanner 11 is reflected by the reflection mirror 12 to be exposed. A latent image is formed by scanning on the drum 17, and a toner image is further formed by the toner supplied from the developing device 18, and is transferred onto a sheet by the transfer roller 14. The transferred sheet is sent to the fixing device 16 along the conveyance table 15, and the fixing roller 21 and the pressure roller 22 fix the toner.

As shown in FIGS. 1 and 2, the sheet discharging section 6 includes a conveying roller 30, a sheet guide 34, an inner guide 29, and a discharging roller 32.
0, the discharge roller 32 has a transport roller 31 and a discharge roller 33 that face each other and are driven. The sheet guide 34 is integrally molded of a resin material and includes a plurality of guide ribs 35 having a curved sheet guide surface 36. Each guide rib 35 is provided with stepped notches 37 and 38. As shown in FIG. 2, the cutout portion is formed of a steeply inclined surface with respect to the curved sheet guide surface 36 and gently inclined surfaces 39, 40 extending from the innermost end of the steeply inclined surface toward the guide surface. However, the steeply sloping surface can be gently sloping within a range in which front contact between the sheet and the sheet guide surface is avoided.

The operation of the above embodiment will be described below.

The uppermost one of the sheets S in the paper feed cassette 3 is taken out by the paper feed roller 23, and the roller 2
4. The roller 25 conveys the toner image to the image forming section 5 along the guide 26, and transfers and fixes the toner image. The sheet with the image formed on its upper surface is sent to the sheet discharge unit 6, and is guided to the sheet guide 34 by the transport roller 30 and the transport roller 31. The upstream end of the sheet changes its traveling direction upward along the curved sheet guide surface 36 of the guide rib 35 and reaches the notches 37 and 38. The leading edge of the sheet once falls into the inside of the notch at the notches 37 and 38, but since the leading end abuts the slopes 39 and 40 where the angle difference with respect to the traveling direction is small, the notch smoothly moves. Pass 37, 38. In the vicinity of the notches 37 and 38, the contact length between the sheet surface and the sheet guide surface 36 becomes small, so that the sheet is guided to above the sheet guide 34 without coming into close contact with the sheet guide surface 36, and the curved portion is bent. The sheet is discharged and stacked on the sheet stacking section 7 at the upper part of the apparatus by the discharge roller 32 and the discharge roller 33 while changing the traveling direction along the line.

As described above, by providing the notches 37 and 38 in a part of the guide rib 35, the contact between the sheet and the sheet guide surface 36 of the guide rib 35 becomes intermittent, and the sliding resistance is reduced. It is possible to smoothly convey even a sheet having a smooth surface such as a sheet and being easily attached to the sheet guide surface 36.

Further, the notch portion 36 of the guide rib 35,
As shown in FIG. 4, 37 may be adjacent guide ribs that are displaced in the sheet conveying direction. By doing so, the rear end of the seat does not fall into a plurality of adjacent notches at the same time, and an effect of mitigating the splashing sound at the time of depression is produced.

In the above example, the notch portion of each guide rib is described as an example of two pieces, but it may be one piece as shown in FIG. 4 or a large number as will be described later. (Second Embodiment) Next, an embodiment in which a part of the previous embodiment is modified will be described.

As shown in a part of FIG. 5, a plurality of grooves 40 thinner than the thickness of the guide ribs 35 are provided on each sheet guide surface 36 of the guide ribs 35. Similar to the cutouts 37, 38 of the previous embodiment, the upstream side of the groove 40 is gently inclined so that the leading edge of the sheet is hard to be caught, and the groove 40 is continuously arranged at a predetermined interval. To do.

With the above structure, the contact between the sheet and the sheet guide surface 36 is intermittent as in the previous embodiment, so that the sliding resistance is reduced and the sheet does not come into close contact with the sheet guide surface 36 and is smooth. Various transports are possible.

Reference Example 1 for explaining the present invention Next, Reference Example 1 for explaining the present invention will be described .

As shown in a part of FIG. 6, the surface of the sheet guide surface 36 of the guide rib 35 is integrally formed with a fine wrinkle-like uneven pattern 50, and the height of the unevenness is the tip of the sheet. 50-100μ so that it will not get caught
The tip of the convex portion is spherical so that the sheet slides smoothly.

By configuring the sheet guide 35 in this manner, the sheet and the sheet guide surface 36 are in contact with each other at a fine uneven surface, so that the sheet can be smoothly conveyed without being in close contact with each other.

[0027] (Reference Example 2 for describing the present invention) Next, for explaining the present invention along the Figures 7 and 8
The second reference example will be described. In addition, the previous embodiment and
The same parts as those of the reference example are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 7 and 8, the sheet guide 34 is provided with a guide roller 60. The center axis 61 of the guide roller 60 is rotatably supported at both ends by a main body (not shown), and each guide rib 35 is provided with an escape groove 63 so that it is positioned inside the sheet guide surface 36. ing. A plurality of rollers 62 are fitted to or integrally formed with the central shaft 61, and the outer edge of the rollers 62 is configured to project slightly inward from the sheet guide surface 36 of the guide rib 35.

The guide roller 60 is driven to rotate by the sheet on which the image is formed being conveyed along the sheet guide surface 36 and coming into contact with the outer edge of the roller.

By thus providing the sheet guide 35 with the guide roller 60 that is driven and rotated by the sheet, the outer edge portion of the guide roller 60 becomes a part of the sheet guide surface, and the guide roller 60 and the sheet are provided in the vicinity thereof. Since the contact with the sheet guide surface 36 is eliminated and the sliding resistance is reduced, it becomes possible to smoothly convey even a sheet having a smooth surface such as an OHP sheet, which easily adheres to the rib surface.

In the illustrated example, the guide roller 60 is provided below the sheet guide surface 36, but it may be provided above the sheet guide surface 36, or the number of the guide roller 60 may be increased to two or more than one in the illustrated example.

[0032]

As described above, according to the present invention,
When an OHP sheet with a smooth front surface or a sheet with an image formed on the back surface is conveyed along a curved guide rib, the contact area between the sheet and the sheet guide surface is reduced and the contact is intermittent. Is less likely to adhere to the sheet guide surface, and sheet jams and abnormal sliding noise are prevented from occurring.

[0033]

[Brief description of drawings]

FIG. 1 is a perspective view of a sheet conveying device according to a first embodiment of the present invention.

FIG. 2 is a front sectional view of the sheet conveying device according to the first embodiment of the present invention.

FIG. 3 is a front sectional view of an image forming apparatus including a sheet conveying device according to the first embodiment of the present invention.

FIG. 4 is a perspective view of a partially modified sheet conveying device according to the first embodiment.

FIG. 5 is a perspective view of a guide sheet guide according to a second embodiment of the present invention.

FIG. 6 is a perspective view of a guide sheet guide according to Reference Example 1 of the present invention.

FIG. 7 is a perspective view of a sheet conveying device according to a second reference example of the present invention.

FIG. 8 is a front sectional view of a sheet conveying device according to a second reference example of the present invention.

FIG. 9 is a front sectional view of a conventional image forming apparatus.

FIG. 10 is a perspective view of a conventional sheet conveying device.

FIG. 11 is a front sectional view of a conventional sheet conveying device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Device main body 5 ... Image forming part 6 ... Sheet discharging part 30 ... Conveying roller 32 ... Discharging roller 34 ... Sheet guide 35 ... Guide rib 36 ... Sheet guiding surface 37, 38 ... Notch part 40 ... Groove 50 ... Unevenness Pattern 60 ... Guide roller 61 ... Axis S ... Sheet

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Claims (5)

(57) [Claims] 1. A sheet guide surface having a curved shape is integrally formed ,
A plurality of guide members provided along the sheet conveyance direction ,
A sheet conveying device for guiding a sheet to the plurality of guide members, wherein the sheet conveying direction by the conveying rollers is reversed by a predetermined angle by the plurality of guide members to convey a sheet, A sheet conveying device, characterized in that a cutout portion is provided on a sheet guide surface so that a sheet being conveyed does not come into contact with the sheet guide surface. 2. The adjacent ones of the plurality of guide members
Make sure that the position of the notch of the guide member is
The sheet conveying device according to claim 1, wherein
Place Curved sheet guide surface wherein a plurality of juxtaposed guide members, the sheet conveying apparatus according to claim 1 or 2 with respect to the sheet conveying direction and forming a single plane vertical. 4. The transport roller is provided below the guide member, and the sheet transported by the transport roller is
Claim being guided from below the sheet guiding surface of the guide member upward, characterized in that it is a predetermined angle inversion 1 or
Or the sheet conveying device according to item 2 . 5. An image forming apparatus, comprising: the sheet conveying device according to claim 1 ; and an image forming unit that forms an image on a sheet.