JP2004026470A - Full color printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a full color printer having a printer paper feeder with a stable paper feed performance without limiting the types and thicknesses of the sheets usable as recording media. <P>SOLUTION: In this full color printer, the paper feeder thereof comprises, at the separation part thereof, a means for varying separating force generated between cut paper and an abrasive material so that the separating force can be lowered for thick cut paper and increased for thin cut paper. Thus the paper feed performance of the paper ranging from thin paper to thick paper can be stabilized without relating to a sheet thickness. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a full-color laser printer provided with an automatic paper feeder for a recording medium.
[0002]
[Prior art]
In the printer of the related art, the paper feeding means is roughly classified into a continuous recording paper feeding method in which recording paper is continuous and a cut paper feeding method in which cut paper cut to a predetermined size is fed. . A conventional technique of the cut sheet feeding method is described in Japanese Patent Application Laid-Open No. H11-20968.
[0003]
[Problems to be solved by the invention]
There are a wide variety of paper sheets as recording media, from thin paper with low paper rigidity to thick paper with high paper rigidity. It is very difficult to separate all these types of cut paper with one separation mechanism.
[0004]
Since the thin paper has low rigidity, a phenomenon in which a number of cut sheets are overlapped and fed (hereinafter, referred to as double feed) is likely to occur, and therefore, it is necessary to set a high separating force. However, if the above setting is performed, cut paper stops at the separation section for thick rigid paper, and the paper cannot be fed. Therefore, it is very difficult to realize a separation mechanism for making both thin paper and thick paper compatible. For this reason, the paper supply device of the conventional printer has a specification in which the types and thicknesses of paper that can be used are limited.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a printer provided with a paper feeding device of a printer having a stable paper feeding performance without limiting a usable paper type and paper thickness.
[0006]
[Means for Solving the Problems]
In the full-color printer of the present invention, the paper feeding device is provided with means for varying the separating force generated between the cut sheet and the friction material in the separating section, the separating force is reduced for thick paper, and the separating force is increased for thin paper. It was configured as follows. With this configuration, it is possible to realize a paper feeder in which the paper feed performance from thin paper to thick paper is stabilized.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a vertical sectional side view showing a combined state of a full-color printer which is an electrophotographic image forming apparatus according to the present embodiment, and an external sheet feeding device 2 is attached to an electrophotographic image forming apparatus main body 1 in a direction of an arrow. By combining in this manner, a full-color printer shown in FIG. 3 is configured.
[0008]
The operation of the electrophotographic image forming apparatus 1 and the external paper feeder 2 will be described in detail with reference to FIG. The charger 17 uniformly charges the photosensitive belt 22 in response to a print start signal from a host (not shown). The optical unit 7 controls exposure according to print data sent from the host, and draws an electrostatic latent image on the photosensitive belt 22. The drawn electrostatic latent image is developed by any of the developing devices 3 to 6 containing toners of yellow, magenta, cyan, and black, and the toner in the developing devices 3 to 6 is placed on the photosensitive belt 22. To form a toner image. The photosensitive belt 22 is rotated by a driving source (not shown), and transfers the toner image on the photosensitive belt 22 onto the transfer drum 21. Excess toner remaining on the transfer drum 21 is removed by the drum cleaner 20.
[0009]
Excess toner remaining on the photosensitive belt 22 is removed by a belt cleaner 23, and the cleaned photosensitive belt 22 is charged again by the charger 17 to form an electrostatic latent image and a toner image. repeat.
[0010]
When a plurality of color toner images are formed on the transfer drum 21, the sheet 27 is pulled out from the sheet cassette 8 by the sheet feeding roller 10 at the time when the desired transfer is completed or in advance, and the sheet 27 is brought into contact with the registration roller 15 and waits. After a predetermined time, the paper feed roller 10 stops.
[0011]
At this time, since several sheets of paper 27 stacked on the paper cassette 8 are pulled out by the paper feed roller 10, these papers 27 pass through the separator pad 11 placed in pressure contact with the paper feed roller 10. Then, the overlapping sheets 27 are separated one by one.
[0012]
At a timing when the position of the toner image formed on the transfer drum 21 coincides with the transfer position on the sheet 27, the conveyance of the sheet 27 that has been in contact with the registration roller 15 and is on standby is restarted. An electric field is applied to transfer the toner image on the transfer drum 21 to the paper 27 side. The sheet 27 to which the toner image has been transferred is discharged by the charge remover 18 to be separated from the transfer drum 21, and the toner image is fixed on the sheet 27 by passing through the fixing unit 19, and the sheet 27 is discharged as a printed sheet 29. Discharge onto tray 28.
[0013]
The external paper feeder 2 also includes a paper cassette 8, a paper feed roller 10, and a separator pad 11, and feeds the paper 27 one by one into the main body 1 of the electrophotographic image forming apparatus, similarly to the paper cassette 8.
[0014]
FIG. 1 shows details of the separation unit. The separation unit includes a separator pad 11 that is in pressure contact with the paper feed roller 10, a spring 30 that presses the separator pad 11, and the like. The separator pad 11 includes a friction material 12 and a support 13 to which the friction material 12 is attached, and the friction material 12 is pressed against the paper feed roller 10. Since the frictional force (separation force) of the papers 27 that are in contact with the friction material 12 is larger than the frictional force generated between the papers 27, the paper feed rollers 10 The paper 27 that has come into contact with the paper feed roller 10 has a frictional force between the paper supply roller 10 and the paper 27 (hereinafter referred to as a conveyance force) greater than the frictional force between the papers 27 and the separation force. Only the 271 sheets that have come into contact are conveyed into the main body 1 of the electrophotographic image forming apparatus.
[0015]
In the present embodiment, the separation of the sheet separating mechanism of the electrophotographic image forming apparatus main body 1 and the external sheet feeding device 2 and the stabilization of the sheet feeding performance are achieved. Generally, it is very difficult for the electrophotographic image forming apparatus main body 1 and the external paper feeder 2 to feed a thin paper to a thick paper, which vary greatly in thickness, one by one. Thin paper literally has a thin paper thickness and low rigidity, so that the paper is deformed, and double feed that passes several sheets simultaneously between the separator pads 11 pressed against the paper feed roller 10 is likely to occur. This is one of the causes that the sheet 27 is deformed when the sheet 27 comes into contact with the separator pad 11 and the sheet is not shifted by the preliminary separation.
[0016]
Preliminary separation refers to a function of shifting the sheets 27 one by one along the surface of the separator pad 11 when several sheets 27 abut on the separator pad 11 as shown in FIGS. In order to separate the thin paper in this manner, a sufficiently large separating force is required.
[0017]
In addition, since the thick paper has a large thickness, the rigidity of the paper is high, and sufficient separation of the paper can be performed by the preliminary separation. In the present embodiment, the separating force is varied as shown in FIGS. 1 and 6 to 10, so that thin paper to thick paper can be easily separated.
[0018]
As shown in FIGS. 1 and 6, a receiving table 32 rotatable about a fulcrum A31 on which the separator pad 11 is set, and a separator 30 is pressed up by a spring 30 to press the separator pad 11 against the paper feed roller 10. The rotating plate 33 to which the spring 30 is attached is configured to rotate about a fulcrum B34. When the switching plate 35 is pressed by a switching lever 35 provided in the cassette 8, the rotating plate 33 rotates about the fulcrum B34 and the spring 30 is rotated. The rotating plate 33 has a step A33a, a step B33b, and a step C33c as shown in the figure, so that the convex portion 35a provided on the switching lever 35 presses the spring 30 depending on which step 33a to 33c is pressed. Is changed, and when the separator pad 11 is pressed against the paper feed roller 10, the amount of deflection of the spring 30 changes and the spring load changes. In general, by changing the pressing force, the separation force generated between the frictional material 12 and the several sheets 27 passing therethrough can be varied.
[0019]
The step A33a, the step B33b, and the step C33c have a difference in angle with respect to the fulcrum B34 of the rotating plate 33. The angle of the step C33c from the fulcrum B34 is the smallest, and the position of the spring 30 is the highest. , Separating power is maximized. FIG. 5 shows the state of the separation unit in this case. When the thin paper is passed, the convex portion 35a of the switching lever 35 on the cassette 8 side is set so as to abut the step C33c, and the cassette 8 is mounted on the main body, so that the separating force is increased, and the double feed is stable. Enables paper feeding.
[0020]
Further, when passing the thick paper, the separation force is reduced by bringing the convex portion 35a of the switching lever 35 into contact with the step A33a, and the paper 27 is caught by the friction material 12 and the paper 27 cannot be sent out from the cassette 8. By avoiding this, stable separation and paper feeding can be performed. FIG. 6 shows the state of the separating section at this time.
[0021]
FIG. 7 is a front view of the steps 33a to 33c provided on the rotating plate 33 of the separation unit. FIG. 8 illustrates a switching lever 35 provided on the cassette 8, and the switching lever 35 moves and switches as indicated by a broken line 35b. The steps 33a to 33c have a three-stage configuration in the present embodiment, but needless to say, the number may be increased or decreased as needed.
[0022]
FIGS. 9 and 10 are views for explaining another embodiment, in which the steps 33a to 33c provided on the rotating plate 33 of the separating portion of the above embodiment are provided on the switching lever 35 on the cassette 8 side. It is.
[0023]
The switching lever 35 includes a step 35d, a step 35e, and a step 35f having different heights, and the steps 35d to 33f that come into contact with the rotating plate 33 of the separation unit are different depending on the set position of the switching lever 35. There is an effect similar to that of the embodiment. A dashed line 35b in FIG. 9 shows the state of movement (switching) of the switching lever 35. FIG. 9 also has a three-stage configuration of the steps 35d to 33f, but it goes without saying that the number of steps may be increased or decreased as necessary similarly to the above-described embodiment.
[0024]
【The invention's effect】
In the full-color printer of the present invention, since the paper feeding device is provided with a variable separating force mechanism, it is possible to stably separate and feed from thin paper to thick paper.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating details of a separation unit according to an embodiment.
FIG. 2 is an explanatory diagram illustrating a combined state of an electrophotographic image forming apparatus main body and an external sheet feeding device of the full-color printer according to the embodiment.
FIG. 3 is a longitudinal sectional side view of an electrophotographic image forming apparatus main body of the full-color printer of the embodiment.
FIG. 4 is an explanatory diagram of a state of preliminary separation.
FIG. 5 is a cross-sectional perspective view showing a state of separation and sheet feeding.
FIG. 6 shows a state where the separating force is the lowest in the separating unit of the embodiment.
FIG. 7 is an explanatory diagram of FIG. 1 viewed from a direction A.
FIG. 8 is an explanatory diagram of FIG. 1 viewed from a direction B.
FIG. 9 is a front view of another embodiment in which a step is provided on a switching lever provided on a cassette.
FIG. 10 is a bottom view of FIG. 9 and is an explanatory view of a step of a switching lever.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electrophotographic image forming apparatus main body, 2 ... External paper feeder, 3-6 ... Developer, 7 ... Optical unit, 8 ... Paper cassette, 9 ... Cassette bottom plate, 9a ... Support point, 10 ... Paper feed roller, 11 ... Separator pad, 12 friction material, 13 support, 15 resist roller, 16 transfer roller, 17 charger, 18 static eliminator, 19 fixing device, 20 drum cleaner, 21 transfer drum, 22 Photosensitive belt, 23: Belt cleaner, 27: Paper (cut paper), 28: Discharge tray, 29: Printed paper, 30: Spring, 31: Support point A, 32: Cradle, 33: Rotating plate, 33a ... Step A, 33b Step B, 33c Step C, 34 Step B, 35 Switch lever, 35a Projection, 35d Step D, 35e Step E, 35f Step F, 36 Separation base, 37 Shaft A, 38 ... Yafuto B, 39 ... torsion spring.

Claims (5)

After each of the yellow, magenta, cyan, and black toners is made visible on an endless belt-shaped photoconductor having a photoconductive surface capable of forming an electrostatic latent image, the developed color toner image is made on an intermediate transfer member. In a full-color printer that sequentially superimposes and transfers the toner image superimposed on the intermediate transfer body to a recording medium,
The full-color printer includes a unit that presses cut paper as a recording medium, a paper cassette having a cassette bottom plate that rotates about a fulcrum, and a separation unit of a paper feed mechanism that separates the cut paper. A full-color printer comprising a sheet feeding device provided with a means for varying a frictional force, which is a separating force generated between a cut sheet and a friction material, by a separation unit of a paper mechanism unit. 2. The sheet feeding device according to claim 1, wherein the means for varying the separation force of the sheet feeding device includes a plate for fixing a spring for pressing a separator pad to a sheet feeding roller at a separation portion of the sheet feeding mechanism, and the plate is provided around a fulcrum. A full-color printer characterized in that it is means for rotating and changing the amount of rotation to vary the amount of deflection of the spring to vary the separating force. 3. The full-color printer according to claim 2, wherein the means for changing the amount of rotation of the plate includes a switching lever for adjusting the amount of rotation of the plate in the cassette. 3. The full-color printer according to claim 2, wherein the amount of rotation changes according to the position of a switching lever provided on the cassette of the plate, and a step corresponding to the switching lever position is provided. 3. The full-color printer according to claim 2, wherein the switching lever of the cassette is provided with a step, and means for changing the amount of rotation of the plate to vary the separating force is provided.

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