JP2004035181A - Paper sheet feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a paper sheet feeder from lowering a continuous printing processing speed even if an image is formed after detecting paper sheet absence. <P>SOLUTION: In a paper sheet feeder, a paper sheet rear end stopper 6, which is mounted as another piece on the guide groove 1a of the paper sheet placing tray 1 of a paper sheet feeding cassette so as to be movable in a paper sheet feeding direction, is made into a U-like shape, and a light-emitting device 6a is arranged at a position where the stopper 6 and the tray 1 become nearly flush at the section of the guide groove 1a (that is, a position where the lowest paper sheet on the tray 1 abuts on), and a light receiving element 6b is arranged at a position directly above the light-emitting device 6a. An image formation device controls the paper sheet feeder so that the paper sheet on the top position to be printed in the next place out of the paper sheets on the paper sheet feeding cassette is preparatorily fed to a position passing the light receiving element 6b before printing and stands by there. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a paper feeder used in an image forming apparatus using electrophotography of a printer, a copier, a facsimile, and the like, and more particularly, to a paper feeder capable of moving in a paper feed direction of a paper cassette and storing paper. The present invention relates to a sheet feeding device provided with a stopper for abutting the most upstream end in the sheet feeding direction.
[0002]
[Prior art]
As shown in FIG. 3, the conventional paper feeder has a paper feed cassette 10, and the paper feed cassette 10 has a paper loading plate 13 on which paper is loaded, and a downstream end of the paper loading plate 13 in the paper feeding direction. A spring 14 provided on the bottom of the unit, a pair of left and right separation claws 12 abutting on the uppermost sheet placed on the sheet placement plate 13, a cassette plate rubber 15 provided on the sheet placement plate 13, A paper trailing end stopper 16 is provided to abut the trailing edge of the paper placed on the loading plate 13, and presses the paper loading plate 13 against the elastic force of the spring 14 when storing a large number of sheets. In this state, the uppermost sheet is pressed by the separation claw 12, so that the upward movement of the sheet placing plate 13 is restricted, and the sheet feeder located above the sheet cassette 10 is placed. Keep the contact pressure between the paper roller (not shown) and the topmost paper Can be one by one and fed by the difference in the coefficient of friction 置用 paper loading a cassette plate rubber 15 and the paper feed roller during the feeding, it is possible to prevent skew feeding by the separation claw 12.
[0003]
[Problems to be solved by the invention]
However, in the case of the conventional paper feeding device, in the case of a paper feeding device that starts forming an image before paper feeding due to a problem of continuous printing speed, when the previous paper is fed and it is determined that there is no next paper. In this case, the formation of an image to be printed on the next sheet has been started, and it is necessary to collect all the toner images on the photoreceptor by the cleaning unit, and a useless developer is used. was there. Conversely, if the image formation is started after the presence or absence of the sheet is determined, the image forming apparatus has a low printing speed during continuous printing.
[0004]
In order to solve such a problem, it is conceivable to carry out standby by a preliminary sheet feeding until the rear end of the sheet passes through the remaining amount sensor. There is a problem that a large space for waiting for the paper sheet is required, resulting in a large image forming apparatus.
[0005]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a paper cassette capable of storing a large number of papers, which is movable in a paper feeding direction of the paper cassette, and abuts the most upstream end of the stored paper in the paper feeding direction. A light-emitting element (or light-receiving element) is disposed at a position where the lowermost sheet of the stopper comes into contact with the stopper, and the stopper is provided at a position where the stopper stands from the paper cassette. A light-receiving element (or light-emitting element) corresponding to the light-emitting element (or light-receiving element) is provided, and before the printing, the storage paper is preliminarily fed to a position past the light-emitting element (or light-receiving element) and put on standby. It is a paper device.
[0006]
Note that, in the paper feeding apparatus of the present invention, when a paper cassette mounted in the image forming apparatus is a target, the image forming apparatus itself is a paper feeding apparatus, and a paper unit mounted in the image forming apparatus is a target. If so, it is assumed that the sheet feed unit is used.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the configuration is the same as that of the conventional one shown in FIG. 3 except for the paper feeder of the present invention, particularly the paper stopper of the paper cassette.
FIG. 1 is a view showing the vicinity of a sheet rear end stopper of a sheet feeding cassette in a sheet feeding device of the present invention. According to the present invention, as shown in FIG. 1, a paper trailing end stopper 6 which is mounted as a separate piece on a guide groove 1a of a paper loading tray 1 of a paper feed cassette and is movable in the paper feeding direction is substantially U-shaped. The light emitting element 6a is disposed at a position on the guide groove 1a which is substantially flush with the sheet loading tray 1 (that is, a position where the lowermost sheet stacked on the sheet loading tray 1 abuts). A light receiving element 6b is disposed immediately above the light emitting element 6a, and the remaining amount of paper is detected by detecting the presence or absence between the light emitting element 6a and the light receiving element 6b.
[0008]
Prior to printing, the image forming apparatus performs control so that the uppermost sheet to be printed next among the sheets stacked in the sheet feed cassette is preliminarily fed to a position past the light receiving element 6b and is put on standby. ing. As a result, the presence or absence of the next sheet can be accurately detected between the light emitting element 6a and the light receiving element 6b. If it is detected that there is no sheet corresponding to printing, the corresponding image forming process is not performed. Stop printing.
[0009]
As a result, even if the image forming process is performed after detecting the absence of a sheet, the printing process can be performed without reducing the continuous printing speed. In addition, it is possible to avoid starting the image forming process before determining the presence or absence of a sheet in order to increase the printing speed.
[0010]
In the present embodiment, 6a is a light emitting element and 6b is a light receiving element. In this embodiment, the light emitting element and the light receiving element are arranged at positions substantially vertically above. However, only when the last sheet of paper is preliminarily fed, light from the light emitting element is emitted. May be any position as long as the light receiving element can receive light, and any structure may be used as long as the position is provided on the paper trailing end stopper.
[0011]
Next, the image forming possibility determination will be described with reference to the flowchart of FIG.
First, it is determined whether or not light is received by the light receiving element 6b (step 1). If light is received, it is determined that an image cannot be formed (step 6) because there is no paper on the paper tray 1 (step 6). If not, one or more sheets are placed on the sheet tray 1 so that the above-mentioned preliminary sheet feeding is performed (step 2). Thereafter, it is again determined whether or not light is received by the light receiving element 6b (step 3). If light is received, there is no paper other than the paper that has been pre-fed in the paper tray 1 so that one page Only the image can be formed (step 5), and if no light is received, the image is formed on two or more pages (step 4) because the sheet is still placed on the sheet tray.
[0012]
【The invention's effect】
As described above, according to the paper feeding apparatus of the present invention, the light emitting element (or the light receiving element) is disposed at the position where the lowermost sheet of the stopper comes into contact, and the stopper stands from the paper cassette. A light-receiving element (or light-emitting element) is provided in the printer, and the paper is preliminarily fed to the position where the storage paper passes the light-emitting element (or light-receiving element) prior to printing. It is possible to provide a paper feeder that can perform printing without lowering the continuous printing processing speed even when the processing is performed, and that does not detect the absence of paper after forming a toner image on a photoconductor.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the vicinity of a sheet rear end stopper of a sheet feeding device of the present invention.
FIG. 2 is a flowchart illustrating a sheet feeding operation according to the present invention.
FIG. 3 is a diagram showing a paper feed cassette in a conventional paper feed device.
[Explanation of symbols]
1: paper loading tray 1a: guide grooves 6, 16: paper trailing end stopper 6a: light emitting element 6b: light receiving element 10: paper feed cassette 12: separation claw 13: paper loading plate 14: spring 15: cassette plate rubber

Claims (1)

A paper feeding device comprising: a paper cassette capable of storing a large number of papers; and a stopper movable in a paper feeding direction of the paper cassette and abutting an uppermost end of the storage paper in a paper feeding direction.
A light-emitting element (or light-receiving element) is disposed at a position where the lowermost sheet of the stopper comes into contact, and a light-receiving element corresponding to the light-emitting element (or light-receiving element) is provided at a position of the stopper standing from a paper cassette. A paper feeder provided with a light-emitting element (or a light-emitting element), and preliminarily feeding the stored paper to a position past the light-emitting element (or the light-receiving element) prior to printing and waiting.

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