JP2007018000A - Printing device and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing device and printing method, by which printing is made without forming wrinkles in paper even on thin paper whose stiffness is weak. <P>SOLUTION: The printing device for carrying out the printing method according to the invention includes: a photoreceptor drum 2; a developing unit 4 for developing an electrostatic latent image on the photoreceptor drum 2; a transfer charger 5 by which a developed toner image is transferred to paper P; a fixing lamp 9 for fixing the transferred toner image; and a conveying means 10 for conveying paper sheet. This conveying means 10 has: a tractor 11 for conveying paper sheet P to the photoreceptor drum 2; a plurality of conveying belts 13 for conveying paper with an electrostatic latent image transferred thereto from the photoreceptor drum 2; and a paper sheet guide 15 disposed on the conveyance-in side of the conveying belts 13. The paper sheet guide 15 extends in the direction where the conveying belts 13 are arranged, and has a curved shape projecting toward the photoreceptor drum 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printing apparatus and a printing method.

  In general, an electrophotographic printing apparatus using a light emitting element such as an LED or a laser beam as an exposure unit conveys a sheet from a sheet feeding unit at a constant speed by a sheet feeding unit and is developed on the sheet by a photosensitive drum. The toner image is transferred, and the toner image is fixed on a sheet by a non-contact type fixing unit such as a xenon lamp and an infrared radiation heater or a contact type fixing unit such as a hot pressure roller, and then discharged.

By the way, in the above-described printing apparatus, paper is conveyed in synchronization with the rotational speed of the photosensitive drum, and if the synchronization is not achieved, the printed image may be distorted or the image may be blurred. Will occur.
In particular, when a non-contact type fixing unit is used in a printing apparatus for printing continuous paper, a scatch having a transport speed slightly higher than that of the tractor in the vicinity of the fixing unit, in addition to the tractor constituting the paper feeding mechanism of the paper. The flora is placed opposite to cause slipping on the paper. Thus, in the continuous paper printing apparatus, the continuous paper transported by the tractor is transported at a constant speed with an appropriate tension to achieve stable transfer and fixing.

Incidentally, in recent years, printing apparatuses capable of printing cut paper together with continuous paper have been required to print on thin paper. However, the conventional printing apparatus, for example, targets about 64 g / m ² (55 Kg / ream) or more, and is thinner than this, for example, about 64 g / m ^{2 to} 46 g / m ² (40 Kg / ream). There are various problems in printing on thin paper.

Here, a ream is a unit that represents 1000 sheets of 788 mm × 1091 mm, and a 40 kg / ream sheet is a sheet having a weight of 1000 kg and is used as an index of thickness.
When the paper used in the conventional printing apparatus is thin paper, if the paper is weak, the paper may be wrinkled depending on the direction of the applied tension depending on the configuration of the paper conveying means. If this wrinkle spreads to the photosensitive drum side, the toner image may not be transferred from the photosensitive drum to the paper well due to the wrinkle, and a transfer omission in which a part of the print is missing may occur. In addition, when such transfer omission occurs, a part of the toner image remaining on the photosensitive drum is transferred to the succeeding paper during subsequent printing, resulting in smearing called ghost, which causes a problem in print quality. there were.

  The present invention has been made in view of the above points. It is a second object of the present invention to provide a printer apparatus and a printing method capable of handling thin paper printing without generating wrinkles even when the paper is weak. And

  To achieve the above object, the present invention relates to a latent image carrying medium, a developing means for developing an electrostatic latent image on the latent image carrying medium, a transfer means for transferring the developed toner image onto a sheet, and a transferred image. In the printing apparatus including a fixing unit that fixes the toner image on the paper and a transport unit that transports the paper, the transport unit is disposed upstream of the transfer unit in the transport direction of the paper. A first conveyance unit that conveys the sheet toward the latent image carrying medium in a state in which relative slip with respect to the sheet is eliminated; and a downstream side of the transfer unit as viewed in the conveyance direction of the sheet, Second conveying means for conveying the paper in a state in which sliding with the paper on which the toner image has been transferred from the latent image carrying medium is allowed, and the second conveying means is on the paper carry-in side Includes a paper guide, and the paper guide Has a curved surface that extends in the width direction of the second conveying means and is convex toward the upstream side in the conveying direction of the sheet when viewed in a cross section intersecting the conveying surface of the second conveying means. It comprises a curved plate that guides the paper along the surface to the transport surface of the second transport means.

Specifically, the second conveying means has a plurality of conveying belts in the width direction, and the paper guide extends in the width direction over all of the plurality of conveying belts. Preferably, the paper is thin paper thinner than at least 64 g / m ² .
In order to achieve the above object, the present invention provides a printing method in which a toner image developed on a latent image carrying medium is transferred and fixed on a sheet conveyed by a conveying unit. In view of this, on the upstream side of the transfer position to which the toner image is transferred, the paper is transported in a state in which relative slip between the transport means and the paper is eliminated, and on the downstream side of the transfer position, the paper is transported. The paper is transported in a state in which relative slip between the transport means and the paper is allowed, and when the paper is carried into the transport surface of the downstream transport means, the cross section intersects with the transport surface. The paper is guided along a curved surface that is convex toward the upstream side in the paper transport direction.

According to the first, second, and fourth aspects of the invention, even if the paper is weak, no wrinkle is generated, and it is possible to cope with printing of thin paper.
That is, since the sheet guide is a curved plate extending in the width direction of the second conveying unit and curved in the sheet carrying-in direction, the sheet is guided by the sheet guide and fed into the second conveying unit, and wrinkles are generated. It does not occur. For this reason, the transfer of the toner image does not occur on the paper, and the so-called ghost that occurs on the subsequent paper during subsequent printing does not occur, thereby improving the print quality.

According to a third aspect of the present invention, even if the paper is a thin paper thinner than at least 64 g / m ² and the paper is weak, the paper is guided by the paper guide to the second conveying means. Since it is sent in, wrinkles are prevented from occurring.

Hereinafter, an embodiment according to a printing apparatus and a printing method of the present invention will be described in detail with reference to FIGS. 1 to 4.
As shown in FIG. 1, the printing apparatus 1 includes a pre-charger 3, a developing unit 4, a transfer charger 5, a separation charger 6, a cleaner unit 7, and a preheating lamp 8 described later. And a fixing lamp 9, and conveying means 10 for conveying paper, for example, continuous paper P, is horizontally disposed below these.

The photosensitive drum 2 as a latent image carrying medium is a drum on which an electrostatic latent image is formed on the surface using an organic photoconductor and the like, and is uniformly charged by the precharger 3 prior to the formation of the electrostatic latent image. . The photosensitive drum 2 is exposed as indicated by an arrow A in the drawing by exposure means (not shown) such as an LED or a laser, and an electrostatic latent image corresponding to print data is formed.
The developing unit 4 as developing means develops the electrostatic latent image formed on the photosensitive drum 2 with dry toner or wet toner, and is unitized and stored in the printing apparatus 1.

The transfer charger 5 serving as a transfer unit is a charger that transfers the toner image developed on the photosensitive drum 2 onto the continuous paper P. The transfer charger 5 is disposed adjacent to the separation charger 6 and applies an alternating voltage to the charged continuous paper P onto which the toner image is transferred to remove the charge.
The cleaner unit 7 is a unit that scrapes off a part of the toner image remaining on the photosensitive drum 2 without being transferred to the continuous paper P, and is housed in the printing apparatus 1.

The preheating lamp 8 is a lamp that preliminarily heats the toner image that is arranged in the width direction of the continuous paper P and transferred to the paper. For example, a halogen lamp is used.
The fixing lamp 9 is a lamp that melts the toner image transferred on the continuous paper P and fixes it on the continuous paper P. For example, a xenon lamp is used. Accordingly, the preheating lamp 8 is not necessarily required if the fixing lamp 9 has a heat generation amount sufficient to dissolve the toner image.

Here, both the lamps 8 and 9 are housed in a reflection case whose inner surface is a reflection surface, and are lit on the basis of the timing of feeding the continuous paper P.
The conveying means 10 conveys the continuous paper P as indicated by an arrow in FIG. 1, and includes a tractor 11, a conveying belt 13, a guide 15 serving as a paper guide, scuff rollers 16 and 17, a switching claw 18 and the like. .

  The tractor 11 is a first transport unit that transports the continuous paper P stored in a paper feeding unit (not shown) to the photosensitive drum 2. In the tractor 11, a guide plate 12 that guides the continuous paper P to the photosensitive drum 2 is disposed between the tractor 11 and the photosensitive drum 2. Here, the printing apparatus 1 according to the present embodiment prints on the continuous paper P, and when printing on cut paper, a supply unit for cut paper is separately arranged.

  The conveyance belt 13 is a second conveyance unit that conveys the continuous paper P on which the toner image is transferred from the photosensitive drum 2 by the transfer charger 5. The conveyor belt 13 is composed of a plurality of belt-like belts, and each belt-like belt is provided with a number of suction holes 13a (see FIG. 2). A suction device 14 provided with a large number of small holes (not shown) corresponding to the suction holes 13a is disposed on the back side of each belt. Therefore, the continuous paper P is transported in a state of being sucked onto the plurality of transport belts 13 by the suction device 14.

  The guide 15 prevents the continuous paper P from wrinkling on the transport belt 13, and is provided on the upstream side of the transport belt 13 in the transport direction of the continuous paper P as shown in FIG. It is a curved plate that extends in the width direction of the conveyor belt 13 and is curved in the carrying-in direction of the continuous paper P. The guide 15 carries the continuous paper P into the conveyance belt 13 while being guided along the curved surface on the carry-in side.

  The scuff rollers 16 and 17 are continuously continuous while applying tension to the continuous paper P in the transport direction by rotating in a half-clutch state while one scuff flora 16 is driven at a transport speed slightly higher than the tractor 11. The paper P is conveyed at the same speed as the tractor 11. The other scuff roller 17 is a driven roller that is supported by a support arm 24 described later and rotates with the rotation of the scuff roller 16. Here, the scuff flora 17 is provided with changing means 20 for changing the tension according to the thickness of the continuous paper P.

The switching claw 18 switches the carrying-out direction of the continuous paper P fed from the conveying belt 13 according to the thickness, and the position is switched in conjunction with the switching operation of the cam 23 of the changing means 20 described later. That is, the switching claw 18 is a position when the thin continuous paper P is discharged to the discharge roller 19 side, and the dotted line is a position when the continuous paper P having a normal thickness is discharged.
Here, as shown in FIG. 4, the changing means 20 includes a rotating arm 21, a receiving metal member 22, and a cam 23.

  The upper side of the pivot arm 21 is pivotable counterclockwise about the fulcrum 21a, and the support arm 24 and the bracket 25 are screwed. The support arm 24 supports the rotating shaft 17a of the scuff roller 17 with a recess 24a provided on the tip side. A push spring 26 is disposed between the bracket 25 and the rotating shaft 17a to prevent the rotating shaft 17a from coming off from the recess 24a.

The receiving bracket 22 is an L-shaped member having an abutting piece 22 a with which a cam surface 23 b described later of the cam 23 abuts, and is screwed to the upper portion of the rotating arm 21.
The cam 23 has a switching knob 23a and a cam surface 23b, and changes the tension pulled in the transport direction in two stages according to the thickness of the continuous paper P. However, if the tension of the cam 23 can be changed according to the thickness of the continuous paper P, the shape of the cam surface 23b can be changed into multiple stages by forming it into a polygonal shape, or the cam surface 23b can be formed into a curved surface. May be changed continuously.

The printing apparatus 1 is configured as described above, and a toner image is printed on plain paper or thin paper by the printing method described below.
First, the photosensitive drum 2 is uniformly charged by the pre-charger 3 and then exposed by an exposure unit (not shown) as indicated by an arrow A in the figure, thereby forming an electrostatic latent image corresponding to the print data.
Next, the electrostatic latent image formed on the photosensitive drum 2 is developed by the developing unit 4 to become a toner image.

Next, the toner image developed on the photosensitive drum 2 is a plain paper conveyed by a tractor 11 through a guide plate 12 from a paper supply unit (not shown), for example, about 64 g / m ² (55 Kg / ream) or more. The toner is transferred onto the continuous paper P by the charge from the transfer charger 5. At this time, in the changing means 20, the switching knob 23a of the cam 23 is operated in advance to switch to the plain paper printing state, and the switching claw 18 is switched to the position indicated by the dotted line in FIG. Further, the continuous paper P onto which the toner image has been transferred has its charge charged by the separation charger 6 removed, and the adsorption force of the continuous paper P electrostatically adsorbed to the photosensitive drum 2 is reduced to reduce the continuous paper P. Separation from the photosensitive drum 2 is facilitated.

  The continuous paper P onto which the toner image has been transferred in this way is guided to the transport belt 13 by the guide 15 and is transported by the tension from the transport belt 13 and the scuff rollers 16 and 17. At this time, the guide 15 extends in the width direction of the transport belt 13 and is curved in the direction in which the continuous paper P is carried. Therefore, the continuous paper P is guided to the conveying belt 13 along the curved surface of the guide 15 and wrinkles are not generated. For this reason, the continuous paper P is a split type belt in which the conveyance belt 13 is constituted by a plurality of belt-like belts, but is fed into the conveyance belt 13 by the guide 15 without wrinkles. In this way, the continuous paper P is sucked and transported on the transport belt 13 by the suction device 14 without wrinkles, and no wrinkles are generated on the photosensitive drum 2 side. Therefore, the toner image developed on the photosensitive drum 2 is transferred from the photosensitive drum 2 to the continuous paper P in a satisfactory manner, and no transfer omission occurs, so that the ghost is formed on the subsequent continuous paper P in the subsequent printing. Dirt called is not generated.

Then, the continuous paper P transported on the transport belt 13 is preheated by the preheating lamp 8, and the transferred toner image is melted and fixed by the heat from the fixing lamp 9.
Thereafter, the continuous paper P on which the toner image has been fixed is guided by the switching claw 18 switched to the position indicated by the dotted line in FIG. 1 and is indicated by the dotted line to a paper discharge hopper (not shown) disposed below. Sent out.

On the other hand, for ^example, when printing to ^{64g / m 2 ~46g / m 2} (40Kg / continuous) order of thin paper, the changing means 20 is switched to the print state of the thin paper by operating the switch knob 23a of the cam 23, interlocked The switching claw 18 is also switched to the position indicated by the solid line in FIG.
That is, when printing on thin paper, the switching knob 23a is rotated counterclockwise in FIG. 4, and the abutting piece 22a of the receiving bracket 22 is pressed by the cam surface 23b. Then, in the changing means 20, as shown in FIG. 3, the turning arm 21 turns the upper side counterclockwise around the fulcrum 21 a together with the receiving bracket 22. As a result, the scuff roller 17 supported by the support arm 24 slightly moves to the upper left in FIG. 4, and the nip pressure between the scuff roller 17 and the scuff roller 16, and hence the tension for pulling the continuous paper P in the transport direction is reduced. Will be changed as follows.

  Thereby, in the printing apparatus 1, the continuous paper P on which the toner image is fixed is discharged to the discharge roller 19 side by the switching claw 18. In the printing apparatus 1, the tension when the continuous paper P is transported is changed from a plain paper to a small value corresponding to the thin paper, and the continuous paper P is detached from the tractor 11 during transport, It is prevented that the sprocket hole is broken or the continuous paper P itself is torn.

In the above embodiment, the case of printing on continuous paper has been described, but it goes without saying that the present invention can be applied to cut paper.
Further, if the thin continuous paper P is weak, the meshing state between the pin of the tractor 11 and the sprocket hole of the continuous paper P is not stable and is easily detached. For this reason, the tractor 11 is good to set the length of a pin long compared with the case of plain paper, and to stabilize the meshing state.

  Further, a detection lever (not shown) for detecting the presence or absence of paper is usually provided at the position of the conveyor belt 13, but in the case of thin paper, the perforation of the continuous paper P may be broken by interference with the detection lever. For this reason, the detection lever avoids breakage due to interference by smoothly processing the tip portion in contact with the paper.

1 is a schematic configuration diagram of a printing apparatus to which a printing method of the present invention is applied. FIG. 2 is a perspective view showing a paper guide provided in the printing apparatus of FIG. 1. It is a side view explaining the action | operation of the change means provided in the printing apparatus of FIG. It is a side view which shows the change means provided in the printing apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printing apparatus 2 Photosensitive drum 3 Precharger 4 Developing unit 5 Transfer charger 6 Separation charger 7 Cleaner unit 8 Preheating lamp 9 Fixing lamp (fixing means)
10 transport means 11 tractor (first transport means)
12 Guide Plate 13 Conveyor Belt (Second Conveyor)
14 Suction device 15 Guide (paper guide)
16, 17 Scuff flora 18 Switching claw 19 Discharge roller 20 Changing means 21 Rotating arm 22 Receiving bracket 23 Cam 24 Support arm 25 Bracket 26 Spring P Continuous paper

Claims (4)

A latent image carrying medium, a developing means for developing the electrostatic latent image on the latent image carrying medium, a transfer means for transferring the developed toner image to a sheet, a fixing means for fixing the transferred toner image on the sheet, A printing apparatus comprising a conveying means for conveying the paper,
The conveying means is
A first transport unit disposed upstream of the transfer unit in the transport direction of the paper and transporting the paper toward the latent image carrying medium in a state in which relative slip with the paper is eliminated; ,
Second transport for transporting the paper in a state of being allowed to slide with the paper on which the toner image has been transferred from the latent image carrier medium, provided downstream of the transfer means in the paper transport direction. Means,
The second conveying means includes a paper guide on the paper carry-in side,
The sheet guide has a curved surface that extends in the width direction of the second conveyance unit and is convex toward the upstream side in the conveyance direction of the sheet when viewed in a cross section intersecting with the conveyance surface of the second conveyance unit. A printing apparatus comprising a curved plate for guiding the sheet to the transport surface of the second transport means along the curved surface. The second conveying means has a plurality of conveying belts when viewed in the width direction,
The printing apparatus according to claim 1, wherein the sheet guide extends in the width direction over all of the plurality of conveying belts. The printing apparatus according to claim 1, wherein the paper is thin paper thinner than at least 64 g / m ² . A printing method for transferring and fixing a toner image developed on a latent image carrying medium onto a sheet conveyed by a conveying unit,
On the upstream side of the transfer position to which the toner image is transferred as viewed in the paper transport direction, the paper is transported in a state where relative slip between the transport means and the paper is eliminated, and from the transfer position. Also on the downstream side, the paper is transported in a state in which relative slip between the transport means and the paper is allowed,
When the paper is carried into the conveyance surface of the conveyance means on the downstream side, the paper is guided along a curved surface that is convex toward the upstream side in the conveyance direction of the paper as seen from a cross section intersecting the conveyance surface. A printing method characterized by the above.

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