JPH04338037A - Automatic sheet feed mechanism - Google Patents

Abstract

PURPOSE:To surely prevent the stack-feed of sheets by providing separating grippers at both the ends of sheet cassettes for respectively storing sheets of different size, and providing pressing rollers concentrically with pick up rollers so that the pressing rollers are located between the respective separating grippers when the cassette is changed. CONSTITUTION:Separating grippers 5 and 8 are respectively provided at both the ends of a small size cassette 1 and a large size cassette 7 and sheets are bent and fed one by one by pickup rollers 2. Since 2 distance L2 between the pick up roller 2 and the separating gripper 8 is larger than a distance L1 between the pick up roller 2 and the separating gripper 5, resiliency due to the bending of a sheet is decreased, and thereby the stack-feed of sheets is liable to be generated. To solve the problem, together with the pick up rollers 2, pressing rollers 10 with the same diameter as that of the pick up roller 2 are provided concentrically therewith and between the respective separating grippers 5 and 8. With such a constitution, even a sheet of large size can be bent with strong resiliency by the separating grippers 8, so that the stack-feed of the sheets can be prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic paper feeding mechanism for feeding a plurality of types of cut sheets in a printing apparatus or the like.

0002

[Prior Art] FIG. 4 shows, for example, Japanese Patent Application Laid-Open No. 01-301274
FIG. 2 is a perspective view of a conventional automatic paper feeding mechanism shown in the publication. In the figure, 1 is a first paper cassette that stores cut paper (paper), and 2 is a semi-disc-shaped pickup roller made of a material with a high coefficient of friction with the paper. The circumferential portion of the disk is in contact with the topmost sheet of paper in the paper cassette 1, and the chipped portion of the disc is provided at a position that does not contact with the topmost sheet of paper. 4 is a motor that rotates the pickup roller 2 via the shaft 3; 5 is a paper separation claw provided at both ends of the paper sending side of the first paper cassette 1; and 6 is a paper sent out from the paper cassette 1. This is a conveyance roller that conveys the image to the printing mechanism.

The arrangement of paper cassettes when such an automatic paper feeding mechanism feeds paper of a larger size than the paper fed by the first paper cassette 1 is shown by a two-dot chain line.
In this case, 7 is a second paper cassette that stores and stores large-sized paper, and 8 is a paper separation claw provided at both ends of the paper feed pattern of the second paper cassette 7.

FIG. 5 is a side view of the automatic paper feeding mechanism. In the figure, 2, 3, 5, 6 are the same as explained above. 9 is a paper guide that guides the paper to the printing mechanism above.

Next, the operation will be explained. The sheets stored in the paper cassette 1 are urged upward by a spring or the like above the bottom surface, and both ends of the topmost sheet abut against the sheet separating claws 5 to keep the height constant. In the paper feeding operation, the shaft 3 rotates in the direction of arrow A, and the circumference of the pickup roller 2 pushes out the paper in the direction of arrow B. At this time, both ends of the paper in the top tier and the papers in the next tier are fixed by the paper separation claw 5, but the stiffness of the paper in the next tier is greater than the friction between papers, and the paper in the top tier is It can slide on the next layer of paper. For this reason, both ends of the paper in the top row are in contact with the paper separation claw 5, so it bends as shown by the broken line in Figure 5 due to the elasticity of the paper, and since the center leading edge of the paper goes first, both ends of the paper is removed from the paper separation claw 5, and the paper is separated into one sheet and sent to the conveyance roller 6. In general, the positional relationship between the pickup roller 2 and the paper separation claw 5 is L1=1, which is the relationship dimension that minimizes the occurrence of overlapping feeding in the first paper cassette 1.
0~25m/m, L3=15~25m/m.

[0006]

[Problems to be Solved by the Invention] In the conventional automatic paper feeding mechanism as described above, when the first paper cassette 1 is replaced with the second paper cassette 7 in order to supply large size paper, the pickup The relative dimensions between the roller 2 and the paper separation claw 8 are L1 > 35 m/m, L3 = 15 to 25 m/m.
It becomes m. When the distance between the pickup roller 2 and the paper separation claw 8 increases, the repulsive force when both ends of the paper contact the paper separation claw 8 and bend becomes weaker, especially when the humidity is high or when the paper is weak. Since the elasticity of the paper in the next and subsequent stages is reduced, the paper in the next stage is also bent together with the paper in the uppermost stage, and double feeding is likely to occur.

Furthermore, since the distance between the pickup roller 2 and the paper separating claw 8 is large, the curvature of the paper as shown by the broken line in FIG. As the contact dimension becomes longer, the paper may come out of the meshing position of the transport roller 6 or the leading edge of the paper may be bent. To prevent this, a wide gap is required between the paper separation claw 8 and the transport roller 6, making the entire device large. There were issues such as:

[0008] This invention has been made to solve the above-mentioned problems, and even when paper is fed from a paper cassette for feeding large-sized paper, double feeding of paper does not occur, and the entire apparatus is An object of the present invention is to provide an automatic paper feeding mechanism that does not become large in size.

[0009]

[Means for Solving the Problems] The automatic paper feeding mechanism according to the present invention includes a paper cassette that stores papers of different paper sizes, and paper separation claws corresponding to each paper size provided at both ends of the paper cassette. and a paper pressing roller provided concentrically with the pickup roller so as to be located between the paper separation claws of each paper cassette when the paper cassette is installed.

0010

[Operation] In the automatic paper feeding mechanism according to the present invention, when a large-sized paper cassette is installed, the paper pressing roller suppresses the large curvature that is formed between the pickup roller and the paper separation claw, and prevents the curvature near the paper separation claw. Make the paper smaller and make the paper more elastic.

[0011]

[Example] Example 1. FIG. 1 is a perspective view of an automatic paper feeding mechanism showing an embodiment of the present invention, FIG. 2 is a front view, and FIG. 3 is a perspective view of essential parts. In the figure, numerals 1 to 8 are the same as those explained in the above conventional example. Reference numeral 10 denotes a paper pressing roller provided coaxially with the pickup roller 2 and between the paper separating claws 5 and 8. The appropriate relationship between the paper pressing roller 10 and the paper separating claw 8 is L0 of 10 to 20 m/m. The diameter of the paper pressing roller 10 is equal to or slightly smaller than the diameter of the semicircular portion of the pickup roller 2, and is made of a material having a small coefficient of friction with the paper.

Next, the operation will be explained. When feeding small size paper, the same paper feeding operation as in the conventional example described above is performed regardless of the paper pressing roller 10. However, when a large size paper, that is, the second paper cassette 7 is installed, the paper pressing roller prevents the curvature created between the pickup roller 2 and the paper separation claw 8 of the paper being pushed out during the paper feeding operation as shown in FIG. 10 is pressed, and the curvature is transferred between the paper pressing roller 10 and the paper separating claw 8. Paper press roller 1
Since the distance between 0 and the paper separating claw 8 is configured to be short, the elasticity of the paper in the next stage is strong, and the paper in the top stage and the paper in the next stage will slip, and the paper in the top stage will always be curved. . Therefore, duplicate feeding of paper is eliminated. Furthermore, the size of the paper that pops out when both leading edges of the paper come off the paper separating claws 8 can be reduced.

[0013] In the above embodiment, two types of paper cassettes were described, the first paper cassette 1 and the second paper cassette 7. However, when using the third and fourth paper cassettes, there are two types of paper cassettes. A paper pressing roller may be provided between the paper separating claws. In addition, in the case of a paper cassette that stores multiple types of paper in one paper cassette and moves the paper separation claw, insert a paper presser roller between the position of the paper separation claw when the paper is one size smaller. Just set it up.

[0014]

As described above, in this invention, by providing the paper press roller between the pickup roller and the paper separation claw, even if paper is fed from a large paper cassette, it can be fed from a normal paper cassette. Automatic paper feeding that maintains the same force relationship as that of paper, minimizes paper curvature, eliminates paper duplication, and reduces the amount of paper that pops out when it comes off the paper separation claw, so that the entire printing device does not become bulky. mechanism can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an automatic paper feeding mechanism showing an embodiment of the present invention.

FIG. 2 is a front view of an automatic paper feeding mechanism showing an embodiment of the present invention.

FIG. 3 is a perspective view of essential parts of an automatic paper feeding mechanism showing an embodiment of the present invention.

FIG. 4 is a perspective view of a conventional automatic paper feeding mechanism.

FIG. 5 is a side view of a conventional automatic paper feeding mechanism.

[Explanation of symbols]

1 First paper cassette 2 Pick up roller 5 Paper separation claw 6 Conveyance roller 7 Second paper cassette 8 Paper separation claw 10 Pick up roller

Claims (1)

[Claims] Claim 1: In an automatic paper feeding mechanism in which a paper cassette loaded with cut sheets is attached to a printing device and the paper is sent out by the rotation of a pickup roller, the paper is separated into single sheets by a paper separation claw and then fed. Paper cassettes that store different types of paper, paper separation claws that match each paper size provided at both ends of the paper feed side of this paper cassette, and paper of each paper size above when the above paper cassettes are installed in the printing device. An automatic paper feeding mechanism characterized by comprising a paper pressing roller provided concentrically with the pickup roller so as to be located between the separating claws.