JPH04358640A - Paper feed mechanism of electrophotographic equipment - Google Patents

Abstract

PURPOSE:To prevent abnormal paper feeding noise generated when highly smooth paper sheets are passed in the paper feeding mechanism of the electrophotographic device of a copier, a printer or the like which are composed of a paper feeding roller and a separation pad brought in pressure contact therewith. CONSTITUTION:There is provided, on the back side of the fitting position, of a separating base 23 which supports a separation pad 20, to a paper feeding base 24, a member 26 for forming an approximate box structure in combination with a paper feeding base 24. The member 26 for forming the box structure and the separation base 23 are fixed to the paper feeding base 24 by means of common fixing screws 25. As vibrations of the paper feeding part can be suppressed by means of a very simple constitution, the paper feeding abnormal noises, generated by the self-excited vibration of the separation pad when highly smooth paper sheets used overseas are passed through the separation pad can be prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic copying machines, electronic printers, etc., and more particularly to a paper feeding mechanism for feeding cut sheets.

0002

2. Description of the Related Art The structure of a paper feed section of a conventional electrophotographic apparatus is as described in Japanese Patent Laid-Open No. 2-38228, in which a separation pad is pressed against a paper feed roller, and this separation pad support member is attached to a main body frame. It has become.

0003

[Problems to be Solved by the Invention] The above-mentioned prior art is particularly applicable to highly smooth paper (Bekk smoothness of about 200 to 40) used overseas.
When paper is fed (0 seconds), stick-slip occurs between the separation rubber of the separation pad and the paper, and this becomes a source of vibration, causing the separation pad to self-excite vibration, causing the frame to which it is attached to vibrate, causing a very large amount of paper to be fed. No consideration was given to the problem of generating abnormal noise. That is, when highly smooth paper is passed through, the separation pad vibrates by self-excitation, and the vibration is transmitted to the separation base that supports the separation pad. Since this separation base is generally installed in the center of a flat paper feed base, it is vulnerable to vibration and has a large area, so that once vibration starts, it generates extremely loud paper feed noise, making it unsuitable for use by customers. SUMMARY OF THE INVENTION An object of the present invention is to provide a paper feeding mechanism for an electrophotographic apparatus that is effective in preventing abnormal paper feeding noise that occurs when highly smooth paper is fed.

0004

[Means for solving the problem] In order to achieve the above object, a member that forms a box structure in combination with the paper feed base is installed on the back side of the attachment position of the separation base that supports the separation pad to the paper feed base. has been established. Further, the members constituting the box structure and the separation base supporting the separation pad are fixed to the paper feed base using a common fixing screw.

[0005]

[Function] Providing a member that forms a box structure in combination with the paper feed base on the back side of the separation base supporting the separation pad at the attachment position to the paper feed base works as follows. The self-excited vibration of the separation pad is transmitted to the separation base that supports it, and vibrates the paper feed base, which has a large radiation area, to generate paper feed noise. However, since the paper feed base is mounted in a box structure, it is much more rigid than a flat plate and is less likely to vibrate. Therefore, it is possible to prevent the occurrence of paper feeding noise without increasing the size of the apparatus. Furthermore, fixing the members constituting the box structure and the separation base supporting the separation pad to the paper feed base using a common fixing screw works as follows. The vibration of the separation base is transmitted to the paper feed base via the fixing screw, but since this screw also tightens the members that make up the box structure, its spring effect reduces vibration and prevents abnormal paper feed noise. It works like that.

[0006]

[Embodiment] An embodiment of the present invention is shown below in Figs. 1, 2, 3,
This will be explained using FIGS. 4 and 5. First, the schematic structure of a laser printer embodying the present invention will be described using FIG. 2. A charger 7, an optical unit 8, a developer 9, and a transfer/static eliminator 1 are installed around the drum 6 whose outer periphery is coated with a photosensitive material.
0, a cleaning unit 11, and an erase lamp 12 are provided to carry out an electrophotographic process. 1
3 is a paper cassette, 14 is a fixing unit, and 15 is a paper discharge tray. 16 is a paper feed roller, 23 is a separation base, and 24 is a paper feed base. Figure 3 shows the structure of the paper feed separation section. A paper feed roller 16 having a rubber material on its outer periphery is supported by a shaft 19, and a rotational driving force is applied to this shaft to frictionally feed paper. The separation pad 20 is supported so as to be in pressure contact with the outer periphery of the paper feed roller 16 and separates the paper. Reference numeral 21 denotes a separation spring for pressing the separation pad 20 into contact. 22
is a release lever that rotates to press against the separation pad 20 only when a paper cassette is inserted. The separation pad 20, separation spring 21, release lever 22, etc. are supported by a separation base 23 made of die-cast aluminum or the like. Note that 23a is a protrusion provided on the separation base, and the separation pad 20 is supported here so as to be swingable in the left-right direction. FIG. 4 is a perspective view showing the structure of the separation pad, in which a separation rubber portion 20b is attached to a support portion 20a formed of aluminum, zinc, or the like.

Next, the structure of the paper feed base mounting section, which is the subject of the present invention, will be explained with reference to FIG. The paper feed base 24 attached to the main body frame (not shown) is generally a flat plate. The separation base 23 is attached to the paper feed base 24 with the fixing screw 2.
Fixed by 5. A through hole for a fixing screw 25 is provided in the center of the rear surface of the separation base attachment part of the paper feed base 24, and a member 26 bent into a U shape is pressed against the paper feed base 24 using the fixing screw 25. Install. By doing this, a box structure is formed by the combination of the paper feed base 24 and the U-shaped bent member 26. FIG. 5 shows a diagram of FIG. 1 viewed from direction A. In this figure, 2
4a is a paper passage hole.

Next, the operation will be explained. When highly smooth paper is passed through, the separation pad 20 itself causes self-excited vibration due to the stick-slip of the paper and the separation rubber 20b on the separation pad 20. This vibration is transmitted to the separation base 23 and attempts to vibrate the paper feed base 24. However, since the rear surface of the paper feed base 24 has a box structure, its rigidity is very high and vibrations can be suppressed. In addition, the vibration of the separation base 23 is transmitted to the paper feed base 24 via the fixing screw 25, but the vibration of the fixing screw 25 is absorbed by the spring effect of the member 26 bent in a U shape, causing paper feeding noise. can be prevented.

[0009]

[Effects of the Invention] According to the present invention, it is possible to prevent abnormal paper feeding noise that occurs when paper is passed through the highly smooth paper used overseas (Beck smoothness of about 200 to 400 seconds) with a very simple structure. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of a paper feeding mechanism section of an electrophotographic apparatus embodying the present invention.

FIG. 2 is a cross-sectional structural diagram showing the entire laser printer embodying the present invention.

FIG. 3 is a perspective view showing the structure of a paper feed separation section.

FIG. 4 is a perspective view showing the structure of a separation pad.

5 is a side view seen from direction A in FIG. 1. FIG.

[Explanation of symbols]

16... Paper feed roller, 20... Separation pad, 23... Separation base, 24... Paper feed base, 25... Fixing screw, 26... Member bent into a U-shape.

Claims (2)

[Claims] [Claim 1] Paper is pressed against a paper feed roller provided with a friction material on the surface to generate paper feeding force, and at the same time, a friction material is provided on the surface for the purpose of preventing multiple sheets of paper from being fed. In a paper feeding mechanism of an electrophotographic apparatus such as an electronic copying machine or a printer, in which a separation pad is in pressure contact with a paper feeding roller, the paper is fed to a rear portion of a separation base supporting the separation pad at a position where the separation base is attached to the paper feeding base. A paper feed mechanism for an electrophotographic device, characterized by having a member that forms a generally box structure when combined with a base. 2. A paper feeding mechanism for an electrophotographic apparatus according to claim 1, wherein the members constituting the box structure and the separation base are fixed to the paper feeding base using a common fixing screw.