JPH058898A - Image forming device - Google Patents

Abstract

PURPOSE:To facilitate a work to remove a sheet conveyance unit and mount the unit in an original position again after a half-moon roller is changed by a method wherein the sheet conveying roller pair of the upper part of the sheet feed half-moon roller, an auxiliary member, a sheet guide plate, and a sheet detecting switch are supported as the sheet conveying unit, which is integrally removable. CONSTITUTION:A sheet conveying roller pair 18 of the upper part of a sheet feed half-moon roller 16, an auxiliary member 22, sheet guide plates 23a and 23b, and a sheet detecting switch 24 are supported as a sheet conveying unit 30 which can be integrally removed. As a result, a roller change work, wherein during work to change the roller 16, the sheet conveying roller pair 18, the auxiliary member 22, the sheet guide plates 23a and 23b, and the sheet detecting switch 24 are removed and after change of the roller 16, the members are mounted on respective original positions, is facilitated.

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 more particularly to a sheet conveying mechanism for reversing and feeding a fed sheet in a direction opposite to its feeding direction. The present invention relates to an image forming apparatus having.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a paper feed roller is usually provided for feeding paper one by one. This paper feed roller uses the friction between its peripheral surface and the surface of the paper placed in the automatic paper feed cassette to feed the paper one by one, and the friction causes the surface to be worn little by little. It is necessary to replace the rollers regularly.

On the other hand, in recent years, many copying machines have a front loading type in which a paper feeding cassette is arranged under the image forming device and the cassette is pulled out to replenish the paper with the paper feeding cassette. There is an increasing number of paper sheets fed from a cassette that are turned upside down in a paper feed cassette and conveyed in a direction opposite to the original feeding direction.

[0004]

By the way, in the image forming apparatus having the above-described paper feeding mechanism, the paper feeding roller is provided on the paper feeding cassette, and the paper detecting mechanism and the paper feeding roller are provided above the paper feeding roller. And the like are provided in close proximity to each other. Therefore, when the paper feed roller is replaced, the above-mentioned members provided on the upper part of the paper feed roller hinder the replacement work, so disassemble these members once and remove them to expose the paper feed roller. It must be in a removable state, and when these members are replaced in their original positions after being replaced, the position adjustment must be performed accurately, which makes it difficult to replace the paper feed rollers. The waste of time and labor involved was enormous.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus in which the paper feed roller can be easily replaced.

[0006]

In order to achieve the above object, an image forming apparatus of the present invention includes a sheet holding section for placing a sheet, and a sheet for sending out the sheet placed on the sheet holding section. A removable paper feed roller, and a unit that integrally and removably supports a plurality of members provided in proximity to the paper feed roller on the opposite side of the paper holding unit. And

[0007]

According to the above-mentioned structure of the present invention, the paper detection mechanism, the paper carrying roller, etc. provided in the vicinity of the paper feeding roller are integrally removed as a paper carrying unit, and then the paper feeding roller is removed to newly install the new one. It is possible to replace it with a new one and then attach the paper transport unit to the original position again.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing the external appearance of the laser beam printer of this embodiment, while FIG. 2 is a view showing its cross section. As shown in the figure, the laser beam printer body 1
Is composed of a lower frame 2 and an upper frame 3 pivotally supported by the lower frame 2 about a shaft 4 and capable of opening upward. The upper frame 3 is provided with a laser optical system 11, a pair of paper discharge rollers 12, a paper discharge tray 13, and the like.
The lower frame 2 includes an image forming unit 14, a paper feed cassette 15 on which paper is placed, a paper feed half-moon roller 16 for automatically feeding paper, a manual paper feed tray 17, a paper feed roller pair 18, and a timing roller pair. 19, a transfer charger 20, a fixing device 21 and the like are provided. Imaging unit 14
Includes a device such as a photoconductor drum, a charger, a developing device and a cleaning device necessary for forming a toner image, and is supported so as to be vertically swingable when the upper frame 3 is opened. When rocked, it becomes possible to remove the paper transport unit 14 described later. FIG. 1 shows the state at this time. In addition, the manual paper feed tray 17
Is for manually feeding paper one by one,
It is pivotably supported between the sheet supply position shown in FIG. 1 and the storage position shown in FIG.

The copy paper is fed from the automatic paper feed cassette 15 provided with the paper feed half-moon roller 16 or the manual paper feed tray 17.
Sheets are fed one by one and sent to the timing roller pair 19 via the sheet conveying roller pair 18. The image information output from the laser optical system 11 is converted into a toner image by the image forming unit 14 described above, and is transferred by the transfer charger 20 to the copy paper fed at a timing by the timing roller pair 19. Further, this sheet is conveyed to the left, the toner image is thermally fixed by the fixing device 21, and then the sheet is discharged onto the sheet discharge tray 13.

The sheet conveying section according to the present invention will be described in more detail. As shown in the drawing, the sheet conveying roller pair 1 is used.
No. 8 automatic paper feed cassette 1 is provided on the side of the manual paper feed tray 17 side.
An auxiliary member 22 is provided for guiding the paper fed from No. 5 on the lower surface and the copy paper fed from the manual paper feeding tray 17 on the upper surface, respectively, to the paper conveying roller pair 18, and A guide plate 2 that forms a paper transport path between the paper transport roller pair 18 and the timing roller pair 19.
A sheet detection switch 24 is provided to detect that the sheet has been conveyed to the pair of rollers 3a and 23b and the timing roller 19. Then, each member of the paper transport roller pair 18, the auxiliary member 22, the guide plates 23a and 23b, and the paper detection switch 24 is integrally detachably supported as a paper transport unit 30 as indicated by a chain line in FIG. Has been done.

The structure and mounting mechanism of the sheet conveying unit 30 and the sheet feeding half-moon roller 16 will be described with reference to FIG. As shown in the drawing, the paper transport unit 30 includes roller shafts 18a and 18b that support the paper transport roller pair 18, auxiliary members 22, guide plates 23a and 23b, and a paper detection switch 24 (not shown in FIG. 3). Left and right side plates 3
It is integrally supported by 1L and 31R. Each of the side plates 31L and 31R is formed with two screw holes 32L and 32R for fixing the lower frame 2 by screwing. On the other hand, at the end on the side plate 31R side, a plurality of gear trains (not shown) for engaging with a gear 45 described later and driving the roller pair 18 are provided.

The two feeding half-moon rollers 16L and 16R are
As shown in the drawing, the flat surface is fixed to the roller shaft 42 in the same direction. The roller shaft 42 is a bearing 43L, 43R provided outside the two rollers 16L, 16R.
Is rotatably fitted in the circular hole of the side plate 31R.
A gear 45 for engaging with a gear 44a of a motor 44 fixed to the printer body 1 and a protrusion 47a for turning on and off the rotation of the roller 16 using a flapper solenoid 46 are formed at the side end. The clutch 47 is provided. Further, as shown in FIG. 4, the lower frame 2 is formed with a groove 41 for positioning the sheet feeding half-moon roller 16, while the bearing 43 is provided with a sheet conveying unit 30.
Is formed with a protrusion 43a that fits into the groove 31a provided on the side of the.

When the sheet feeding half-moon roller 16 and the sheet conveying unit 30 are attached to the main body 1, first, the lower frame 2
The rollers 16 are attached to the side portions 41L and 41R of the groove 41 formed on the roller 16.
By inserting the bearings 43L and 43R of the roller 16 into
Is attached to a fixed position, the gear 45 meshes with the gear 44a of the motor 44 accordingly. Then, the paper transport unit 30 is fixed from above with screws, and at this time, the grooves 31 provided in the side frames 31L and 31R are fixed.
The paper feeding half-moon roller 16 is positioned at a fixed position by fitting the a and 31a to the protrusions 43a and 43a. Thereby, the positional accuracy between the roller 16 and the paper transport unit 30 can be ensured. At the same time, a gear train (not shown) provided on the roller shaft 18a
It meshes with the gear 45.

The sheet feeding half-moon roller 16 and the sheet conveying roller pair 18 are driven by a common motor 44. When the motor 44 is turned on, the sheet conveying roller pair 18 is rotated, and in this state, the flapper 46a of the solenoid 46 is vertically swung to turn the clutch 47 on and off, which causes the sheet feeding half-moon roller 16 to move to 1 The paper feed operation is performed by rotating.

When replacing the sheet-feeding half-moon roller 16, first, the upper frame 3 is opened, the image forming unit 14 is swung upward, and the sheet conveying unit 30 is unscrewed to remove the roller 16 in one piece. It is exposed and can be easily removed and operated. After replacing the roller 16, the paper transport unit 30 is screwed in place again. This completes the replacement work of the sheet feeding half-moon roller 16.

As described above, in the laser beam printer 1 to which the present invention is applied, the sheet conveying roller pair 18, the auxiliary member 22, the guide plate 23, and the sheet detecting sensor 24, which are arranged in proximity to the upper portion of the roller 16, are provided. The paper transport unit 30
Since it is integrally supported as, it is possible to remove all of these members at once.

The paper transport unit 3 in this embodiment is used.
Reference numeral 0 designates a paper transport roller pair 18, an auxiliary member 22, and a guide plate 23.
Although the paper detection switch 24 and the paper detection switch 24 are integrally supported, the unit of the present invention is not necessarily limited to these. For example, the paper detection switch 24 may be detached from the unit and provided in the lower frame 2. However, the timing roller 19 may be included in the unit.

Further, in the present embodiment, the above-mentioned members arranged above the paper feed roller 16 are collectively supported by one unit, but the unit of the present invention is not limited to one.
For example, the sheet conveying roller pair 18 and the auxiliary member 22 may be integrated into one unit, and the guide plate 23 and the sheet detection switch 24 may be supported as another unit, so that a total of two units may be detachably provided.

On the other hand, in this embodiment, the sheet is fed by using the half-moon roller 16, but a sheet feeding method using a circular roller and a separation roller may be used, for example. Further, although the paper transport unit 30 is supposed to be screwed, without using screws,
The post-imaging unit 30 and the upper unit 13 that have been fitted may be fixed together with the positioning.

Further, in this embodiment, the automatic paper feeding cassette 1 is used.
5, a sheet-feeding half-moon roller 16 is provided, and members provided on the upper part thereof are integrally supported as a unit. According to the present invention, the sheet placed on the sheet-holding section is placed under the sheet-holding section. The present invention can also be applied to a paper feed system in which paper is sequentially fed from the bottom by a paper feed roller provided in. In this case, the sheet conveying roller, the sheet guide plate, and the like, which should be provided closer to the lower side of the sheet feeding roller, are supported as an integrally removable unit.

In addition, although the present invention has been described as being applied to a laser beam printer in this embodiment, it goes without saying that it can also be applied to a copying machine and other image forming apparatuses.

[0023]

According to the image forming apparatus of the present invention, when a paper feed roller worn due to friction with a paper is replaced, the image forming apparatus is provided in the vicinity of the paper feed roller. Since the above member is integrally and detachably supported as a paper transport unit, the paper feed roller can be exposed only by removing this unit. Therefore, it is possible to easily perform the replacement work of the roller and to replace the roller. It is not necessary to adjust the position of each member in the unit for each. Therefore, the time and labor required for the paper feed roller replacement work can be significantly reduced.

[Brief description of drawings]

FIG. 1 is an external view of a laser beam printer according to the present invention.

FIG. 2 is a front sectional view of a laser beam printer according to the present invention.

FIG. 3 is a diagram showing a structure and a mounting mechanism of a paper transport unit according to the present invention.

FIG. 4 is a diagram showing a positioning mechanism for a sheet transport unit and a sheet feeding half-moon roller according to the present invention.

[Explanation of symbols]

 1 Laser Beam Printer 15 Automatic Paper Feed Cassette 16 Paper Feed Half Moon Roller 18 Paper Transport Roller 22 Auxiliary Member 23 Guide Plate 24 Paper Detecting Switch

Claims (1)

Claim: What is claimed is: 1. An image forming apparatus having a paper transport mechanism for transporting a fed paper by reversing the fed paper in a direction opposite to the feeding direction, and a paper holding unit for placing the paper. A removable paper feed roller for feeding the paper placed on the paper holder, and a plurality of paper feed rollers to be provided in proximity to the paper feed roller on the opposite side of the paper holder. An image forming apparatus comprising: a unit in which members are integrally and detachably supported.