JPH01156235A - Sheet feeding cassette - Google Patents

Abstract

PURPOSE:To prevent an upper cover from easily generating friction electrostatic charge so as to inhibit attraction due to the electrostatic charge by forming many irregular parts in the upper cover on at least its reverse surface. CONSTITUTION:An upper cover 2 provides in its reverse 2a an innumerable quantity of irregularity by a crimp 9, decreasing a contact area with paper P, and the upper cover 2 reduces a generation quantity of friction electrostatic charge, while the paper P is prevented from easily sticking to the cover even when the friction electrostatic charge is generated. By this constitution, fully loading the paper P in a cassette C1 under an environment of low humidity, even when the paper is continuously fed, the paper P is prevented from sticking to the upper cover 2 because it generates a less quantity of friction electrostatic charge further with difficulty of adherence by the irregularity.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a sheet feeding section of an image forming apparatus such as a copying machine, a printer, or a printing machine, and more particularly to a sheet feeding cassette having a top lid.

(B) Prior Art Conventionally, paper feed cassettes have been widely used in copying machines, printers, printing machines, etc. that use sheets.

As shown in FIGS. 4 and 5, the paper feed cassette C' includes a main body 1 including an intermediate plate 3 made of sheet metal or the like, a separating claw member 8, a spring 4 for applying paper feed pressure, and an upper lid. Consisting of 2'.

The upper lid 2' prevents foreign matter such as dust from entering the cassette l-C', and also prevents the paper P from absorbing moisture. Recently, there are also devices that use the surface of the top lid as a manual feed tray.

In the conventional paper feed cassette 1-C', the paper P is placed on the middle plate 3.
By rotating the half-moon-shaped paper feed roller 5 stacked on top of the paper feed roller 5 by a drive source (not shown), only the topmost sheet P of the paper sheets P is exposed to the frictional force of the paper feed roller 5 and the separation claw. Part 8
The sheet is separated by the action of the paper feed guide plate 7, 7' and sent to the pair of registration rollers 6.degree. 6'. Here, the upper lid 2' is generally made of ABS resin or the like, and the back surface 2'a1 of the upper lid 2', that is, the paper P
The contacting surface was smooth.

(C) Problems to be Solved by the Invention By the way, when the paper P is fed, the paper is conveyed while being in contact with the back surface 2'a of the top cover. Normally, paper is fed continuously, so the top lid becomes electrically charged due to friction with the paper P. Eventually, the paper P receives a force in the direction of the arrow in FIG. 2'a
If the paper P2 sticks to the paper and receives an unstable force, the paper P2 may become skewed as shown by the broken line in Figure 5, or it may not be held correctly by the pair of registration rollers 6.6', or the amount of loop may be incorrect. In some cases, there was a misalignment jam or poor printing position accuracy. This phenomenon tends to occur in low humidity environments where charging is likely to occur, or when the cassette is full of paper. When the cassette is full of paper (this is likely to occur because the distance between the topmost paper in the cassette and the top lid 2' is small, so they easily come into contact and are easily charged due to friction).

Furthermore, in cassette I, in which the top lid 2' of cassette C' doubles as a tray for manual paper feeding, the friction between the paper and the top lid (tray) causes the top lid to become electrically charged during manual feeding, resulting in continuous manual feeding. While loading the paper in the cassette, the top sheet of paper in the cassette may stick to the back side of the top cover 2'a and float up. If you try to feed the paper automatically in this condition, it may result in poor paper feeding or skewed paper feeding. was likely to occur.

Further, even if the upper lid 2' was made of conductive resin, this drawback could not be completely eliminated.

(C) Means for Solving the Problem The present invention aims to solve the above-mentioned problems, and provides a sheet feeding cassette J. having a top lid, in which a large number of It is characterized by forming an uneven portion.

Due to the above-mentioned means, the back of the top cover of the cassette for feeding cassettes has many irregularities, so even if cassette 1 is fully loaded with cassettes 1 and continuously fed at low humidity, Frictional charging of the top lid occurs, and since the contact area between the back surface of the top lid and the sheet is small, adhesion due to charging is significantly prevented.

(F) Example 1 3= Hereinafter, examples of the present invention will be described along with the drawings. Incidentally, the same parts as those of the conventional paper feed cassette 1-C' described above are given the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows a first embodiment of the present invention, in which a grain 9 (surface unevenness processing) is applied to the back surface 2a of the upper lid 2 of the paper feed cassette C1.

That is, by providing countless unevenness with grains 9 on the back surface 2a of the lid 1, the contact area with the paper P is reduced, the amount of frictional electrification generated on the upper lid 2 is reduced, and even if frictional electrification occurs, it will not stick. It's on.

According to this embodiment, in a low humidity environment, the cassette C
Even if the inside of the lid 1 is fully loaded with paper P and continuous paper feeding is performed, the amount of frictional electrification of the upper lid 2 is small and the unevenness makes it difficult for the paper P to stick, so the paper P will never stick.

Furthermore, when continuous paper feeding is performed using the top lid 2 as a manual feed tray, the amount of frictional electrification is the same as in the prior art, but due to the uneven surface of the back surface 2a of the top lid, the paper in the cassette C1 is
The top paper P does not stick.

FIG. 2 shows a second embodiment of the invention, cassette C2
A large number of ribs 10 are provided on the back surface 2a of the top lid 2. This also reduces the contact area between the paper P and the upper lid 2, similar to the first embodiment described above, and achieves the same effect. As is clear from the above first and second embodiments, the upper lid back surface 2a
The shape of the unevenness provided on the surface is not particularly limited, and in short, any shape may be used as long as it reduces the area of contact with the paper P. For example, a shape with many spherical surfaces arranged side by side may be used.

According to the experiment, the back side is textured (Tanazawa Hekosha, FN
G-82), or those with many ribs perpendicular to or parallel to the paper traveling direction as shown in Figure 3.
For example, clear effects were observed when a=1 mm, b=05 mm, and c=2 mm.

Further, in the above embodiments, a separation type paper feed cassette has been described, but it goes without saying that the present invention can be similarly applied to paper feed cassettes used for friction separation type and other paper feeding systems.

Furthermore, if the material of the upper lid 2 is not just a resin but also a conductive resin, the amount of triboelectric charging is further reduced and the effect is even more significant.

(G) As described in detail, according to the present invention, a simple method of providing unevenness on the back surface of the top cover of the sheet feeding cassette, and
By simply implementing measures that have almost no impact on cost, we can significantly reduce the occurrence of feeding defects, skewed feeding, poor printing accuracy, etc. caused by sheets adhering to the top cover of the sheet feeding cassette, especially in low humidity environments. can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of a sheet feeding cassette showing a first embodiment of the invention, and FIG. 2 is a schematic side view of a sheet feeding cassette showing a second embodiment of the invention. , 3rd
The figure is an enlarged sectional view showing the uneven surface in the second embodiment of the present invention, FIG. 4 is a schematic side view of a conventional sheet feeding cassette 1-, and FIG. 5 is a conventional sheet feeding cassette FIG. 1.Sheet feeding cassette body, 2.Top lid,
2a...Back side of top lid, 5...Paper feed roller, 9
210...Irregularities (grain, ribs), P...Sheet (paper), C8, C2...Sheet 1-Feeding cassette
to .

Claims (2)

[Claims] (1) A sheet feeding cassette having a top lid, characterized in that a large number of concave and convex portions are formed on at least the back surface of the top lid. (2) The sheet feeding cassette according to claim 1, wherein the upper lid also serves as a sheet feeding tray for manual feeding.