JPS5986530A - Residual paper detector - Google Patents

Abstract

PURPOSE:In a residual paper detector for paper feeder in a copier, to improve detection accuracy by providing two paper detectors with predetermined positional relation on a paper mounting table in container and detecting the residual paper from the outputs of both detectors. CONSTITUTION:Assuming the distance between a stopper face 3 and a separating section 8 is L1, while the length of paper in carrying direction A is L2, detectors 11, 12 are arranged at the positions departed by the distances LX, LY from said face 3 (L2-L1<Lx<L2, 0<LY<L2-L1). With such structure, when paper is abundant, high vertical force is applied onto the frictional face between the lowermost paper Pn and the mounting face 6 to never move the paper Pn, but as the paper volume reduces such condition is produced where said vertical force is reduced and the frictional force in the direction A will overcome the frictional force between the lowermost paper Pn and the mounting face 6 or the inter paper frictional force will overcome said frictional force to move the paper. Since two detectors 11, 12 are in predetermined relation, this condition can be detected accurately to output scarce residue. Consequently reliability of detection can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a paper feeding device for a copying machine, a printing machine, etc., and more particularly to a remaining paper amount detection device in this paper feeding device.

BACKGROUND OF THE INVENTION Many methods and devices have been known for detecting the remaining amount of paper by detecting the thickness of stacked papers or a similar amount thereof.

A method for detecting the remaining amount of paper by detecting the position of a paper mounting table is known, for example, from Japanese Patent Publication No. 52-7162.

However, with this device, the amount of paper remaining is extremely low ('t
In order to detect the presence of paper (for example, about 5 to 10 sheets), the thickness of a single sheet of paper is very thin (about 100 μm), so
It is necessary to accurately adjust the fixing position of the microswitch, and the detection accuracy of the microswitch itself also needs to be high. Furthermore, when raising and lowering the paper stacking table using a motor, it is necessary to precisely detect the position of the top of the stacked paper, and also minutely control the rotation of the motor to move the paper stacking table up and down. It was difficult to reduce the error.

As described above, conventional remaining amount detection devices that detect the thickness of stacked sheets or a similar amount thereof are not suitable for detecting that the remaining amount of paper has become extremely low.

Purpose The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and it is possible to detect not only the state where no paper is set in the container but also the state where the remaining paper amount is extremely small (it is impossible to detect that the paper has become too small). Moreover, it is an object of the present invention to provide a highly reliable remaining paper amount detection device that has a small error in the number of remaining sheets when detecting the remaining amount of paper.

composition The configuration of the present invention will be explained based on an example shown below.

FIG. 1 is a simplified vertical cross-sectional view of a paper feeding device according to an embodiment of the present invention.

In the figure, 1 is a storage container (cassette,
The stacked sheets 2 are set in such a way that the tip thereof is pushed against the protruding face 3 of the tip of the container 1. The mounting plate 4 for the paper 2 is urged upward by a spring 5, and has a mounting surface 6 whose coefficient of static friction with the paper is smaller than the coefficient of static friction between the paper sheets. 7 is a feeding roller that constitutes a feeding section; 8 is a paper feeding roller 9 and a separating roller 10
This is a separation unit consisting of a separating section, which separates the fed sheets one by one and sends them out. Further, in the figure, Ll is the distance between the abutting surface 3 and the separating section 8, and L2 is the length of the sheet 2 in the conveyance direction (direction A). The aforementioned mounting plate 4 is provided with two notches.
A first paper detecting section 11 and a second paper detecting section 12 made of photoyellow are provided toward the inside from this notch. This first
The paper detection unit 11 is located at a distance LX-b''- from the abutting surface 3.
L2 is provided at a position where Ll<LX<L2, -
The force cylinder 2 paper detection unit 12 has a distance Ly from the abutment surface 3 of O.
(Ly (L 2 1) 13 is the output a of the first paper detection section 11, the output C of the second paper detection section 12
This is a paper remaining amount determination device that outputs a paper remaining amount signal according to the amount of paper remaining.

Next, its operation will be explained.

FIGS. 2 and 3 are explanatory diagrams showing the state of paper feeding. FIG. 2 shows a case where there is a large amount of paper remaining, and FIG. 3 shows a case where there is a small amount of paper remaining.

First, in FIG. 2, when the sheet feeding operation starts, the uppermost sheet P1 of the stacked sheets 2 is sent to the separating section 8 by the feeding roller 7. At this time, the following sheets P2, P3, and P4 are driven slightly forward by the frictional force in the sheet conveyance direction that is also transmitted to the topmost sheet P1. However, the separating section 8 sends out only the uppermost paper P1, and does not send out P2+P3+P4 to the separating section 8 and subsequent parts.

The bottom paper Pn of the stacked papers 2 receives the frictional force transmitted from Pl, but since there is a large amount of remaining paper, the normal force applied to the friction surface between Pn and the placement surface 6 is large, and the Since the static frictional force is constant, this paper P,1 is not driven in the paper conveyance direction. Therefore, the first paper detection section 11 and the second paper detection section 12 each output "paper present", and the paper remaining amount determination device 1
3 outputs "amount of paper remaining".

Next, as shown in FIG. 3, the paper feeding operation is repeated and as the remaining amount of paper decreases, the vertical force applied to the friction surface between the lowest paper Pn and the placement surface 6 becomes smaller.

Bottom paper Pn and paper P near the bottom paper Pn
The static friction force between the sheets H1+P'H2, for example, the static friction force between the bottom sheet Pn and the sheet Pn-1 is larger than the static friction force between the bottom sheet Pn and the placement surface 6. In other words, the vertical force between the bottom paper Pn and the placement surface 6 is slightly larger than that between the bottom paper Pn and the paper Pn-1, but the static friction coefficient is between the bottom paper Pn and the placement surface 6. This is because the distance between the sheets Pn and Pn-1 is smaller than that between the sheets Pn at the bottom and the sheet Pn-1, so the static friction force between the sheets Pn at the bottom and the placement surface 6 is smaller. The same thing can be said about the static friction force between the recent sheets of paper Pn at the bottom.

Therefore, when there is a large amount of remaining paper as shown in Figure 2, only the paper near the paper P1 at the top of one magazine is driven; however, as the remaining amount of paper decreases, the maximum amount of paper moves as shown in Figure 3. Upper paper P
1 becomes larger than the static friction force between the bottom paper Pn and the placement surface 6, and the bottom paper Pn and the paper Pn- in the vicinity of the bottom paper Pn
1. Since the static friction force between the sheets Pn-2 is smaller than that of the sheets Pn-2, the lowest sheet Pn begins to slide on the placement surface 6. Therefore, all of the stacked sheets on the mounting plate 4 are driven in the sheet conveying direction A and abut against the separating section 8.

When there are a plurality of sheets remaining, the separation section 8 does not send out any sheets other than the topmost sheet to the separation section 8 and beyond. Therefore,
The distance L between the abutting surface 3 and the separating section 8 for the lowest paper Pn
It is not possible to follow one or more paper conveyance directions A. Therefore, the distance from the surface 3 is O<Ly<Lz Lt
Since the length of the paper is Lz, the second paper detection unit 12 installed at a certain position outputs "paper present". On the other hand, the distance LX between the abutment surfaces 3 is Lz −Ll <LX<Lz
The first paper detection unit 11 installed at a certain position outputs "no paper" because the lowest paper Pn is driven in the paper conveyance direction A. In this case, the paper remaining amount determining device 13 outputs a,
The rL and HJ high outputs of e output "less paper amount".

In FIG. 3, the paper feeding operation is further repeated, and the last paper, that is, the paper Pn, is sent out. When the trailing edge of the paper Pn passes over the second paper detection section 12, the second paper detection section 12 detects the second paper. The unit 12 outputs "out of paper", and the remaining paper amount determining device 13 outputs "out of paper" by outputting "rr, . . . L" of the output arc.

FIG. 4 is an example of a circuit diagram of the first and second paper detection units 11.12 and the remaining paper amount determination device 13. First paper detection unit 11
, the second paper detection section 12 is a light emitting diode DI, respectively.
r D2 r phototransistor. On the other hand, the paper remaining amount determining device 13 is composed of an anchor case G1. Next, the operation will be explained. When there is a large amount of paper remaining, there is paper above the first and second paper and the detection section 11.12, so the light emitted from the photodiode 1+D2 is reflected by the paper and the phototransistors Ql and Q
2, Ql + Q2 turns on and the output a
and C both become H. Therefore, andgate G
1 outputs H.

Therefore, the paper remaining amount signals bl and b2 both become H, indicating that the amount of paper loaded is large.

When the amount of paper remaining decreases, there is no paper on the first paper detection section 11, so the light emitted from the photodiode D is not irradiated to the phototransistor Ql, and Ql is turned off. On the other hand, since Q2 is on, the output a becomes L1 and the output C becomes H. Therefore, the paper remaining amount signal b1 becomes L1b2 and becomes H.
"Paper quantity is low."

Furthermore, when the remaining amount of paper decreases and the last sheet is sent out, there will be no more paper on the second paper detection unit 12, so Ql
, Q2 are turned off, and both outputs a and e become L. Therefore, the paper remaining amount signals t)1 +t)2 both become L, and "
"No paper remaining" is displayed.

The number of remaining sheets of paper when a low amount of paper is detected is affected by the static friction coefficient of the paper area, the static friction coefficient between the paper and the paper setting surface, the basis weight of the paper, etc., but it is detected when the number of remaining sheets is very small. can do. - To give an example, we conducted an experiment with a configuration in which B4 high-quality paper was used, the mounting surface 6 was made of stainless steel, and a part of the mounting surface had a friction member (cork).
It was possible to detect a low paper load with a very small number of sheets (0 sheets), and the difference in paper residual sound and number of sheets when a paper load of 1 was detected was extremely small and stable.

Effects As described above, in the present invention, the remaining amount of paper is detected not by detecting the thickness of stacked sheets or a similar amount thereof, but by using two paper detection units 1 arranged in the paper conveyance direction. By detecting the amount of paper remaining, it is possible to reliably detect when the amount of paper remaining is extremely low.
Moreover, the error can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a simplified longitudinal sectional view of the paper feeding device according to the present invention, FIGS. 2 and 3 are diagrams for explaining the state of paper at the time of paper feeding, and FIG. FIG. 3 is a diagram when the remaining amount of paper is small, and FIG. 4 is a detection circuit diagram according to an embodiment. 1... Container, 2... Paper, 3... Thrusting surface,
7... Paper feeding section, 8... Separating section, 11... First
Paper detection section, 12... second paper detection section. 7th @ ■ Figure 2 Figure 3 Figure 4 Figure 1',

Claims (1)

[Claims] A feeding section for setting the stacked sheets of paper against the abutting surface at the tip of the container, abutting against the top of the set paper, and feeding out the paper from the abutting surface; In a paper feeding device equipped with a separation section that separates and feeds out sheets of paper sheet by sheet, the distance between the separation section and the abutment surface is L11100, and the length in the transport direction is Lz.
When, the distance LX between the abutting surfaces A and R is Lz
The first paper detection section is provided at a position where Ll<L) (<Lz, and the distance Ly from the punching surface is O<Ly<L.
A second paper detection section is provided at a position z-Ll, and this first paper detection section is
A paper remaining amount detection device characterized in that a very small remaining amount of paper or no paper is detected based on the output conditions of a paper detection section and a second paper detection section.