JP2010210663A - Printing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing system that performs printing on a web W excessively shrunk in a first printer P1, without significantly degrading fixing intensity in a second printer P2, and ensures a stable fixing state between the web W and a toner image from the beginning of printing. <P>SOLUTION: The printing system has the first printer and the second printer. Each of the first and second printers includes a printer, a fixing device by pressure and heat, and a web buffer device for absorbing a difference in web conveying speed between the printer and the fixing device. The second printer includes a means for recognizing the length of one page of the web to be printed, a means for recognizing the number of pages of the web between the first and second printers, and a means for measuring the time during which printing is stopped on the fixing device of the first printer. During a period of time when the web stopped on the fixing device of the first printer passes through the fixing device of the second printer, the printing system decreases the conveying speed in the fixing device of the second printer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a web conveyance system in an electrophotographic image recording apparatus.

  As a printing system for forming images on both sides of a web represented by a long continuous belt-like sheet, for example, two printing apparatuses are arranged in series as described in JP-A-8-50429. After printing on the first surface (front surface) of the web with the front-stage printing apparatus, the web discharged from the front-stage printing apparatus is turned upside down with the reversing apparatus, and then the web is sent to the rear-stage printing apparatus. A printing system in which printing is performed on the second surface (back surface) of a web with the above printing apparatus has been proposed and put into practical use.

  In the fixing device used in such a printing system, the fixing device used for printing on the second surface (back surface) with respect to the fixing temperature of the fixing device used for printing on the first surface (front surface). Generally, the fixing temperature is set higher.

  Further, in a heating roll fixing device such as disclosed in Japanese Patent Application Laid-Open No. 6-274056, it is held and conveyed between a heating roll having a heater inside and a pressure roller pressed against the heating roll, and is fixed to the web by being heated and pressurized. When the pressure roll is pressed against the heating roll, that is, at the time of printing, the web is positioned so as to be wound around the heating roll on the downstream side in the web conveyance direction with respect to the pressure-contact portion of the heating roll and the pressure roll. A fixing device that holds a web guide member, winds the web around a heating roll, and fixes the web while contacting it has been put into practical use.

  As shown in FIG. 2, in a printing apparatus that handles this type of web W, a preheating plate 13a, a heating roller 13b, and a pressure roller are used as a fixing apparatus for fixing an image on the web W in the conveyance path. 13c is provided.

  Conventionally, in a printing system using a printing apparatus having such a fixing device, when the web W is stopped while being passed through the first printing apparatus P1 and the second printing apparatus P2, the first printing apparatus P1 is used. In the web W, as only a part of the web W stopped on the fixing device continues to be preheated as time elapses, the water evaporates and the web W partially shrinks greatly.

  The web W having a largely shrunken portion discharged from the first printing device P1 is fed into the second printing device P2 after being reversed by the reversing device T. The greatly contracted web W passes over the preheating plate 13a of the fixing device.

  When such a greatly contracted web W passes on the preheating plate 13a of the second printing apparatus P2, the web W is deformed like the portion Wt in the web W in FIG. Adhesion with the preheating plate 13a is weakened, and sufficient preheating of the web W and the toner image is not performed.

  As a result, there is a problem that the fixing strength of the greatly contracted portion Wt is greatly deteriorated.

  The object of the present invention is to allow the second printing device P2 to print the web W, which has stopped on the preheating plate 13a of the first printing device P1 and greatly contracted, without greatly deteriorating the fixing strength. An object of the present invention is to provide a printing system having a web conveyance speed control system capable of ensuring a stable web W and toner image fixing state.

  In order to achieve the above object, in the first means of the present invention, a first printing device for forming an image on a first surface of a web, and a second surface of the web provided at a subsequent stage of the first printing device. A first printing device for forming an image on the web, and a preheating plate for fixing the image on the web. A fixing device having a configuration in which heat is applied to the web and the toner image in advance, and a heating roller and a pressure roller are disposed at the subsequent stage, and the printing device and the fixing device. A web buffer device for absorbing a web conveyance speed difference is provided, and the second printing device is configured to detect the length of one page of the web to be printed from now on and the web located between the first printing device and the second printing device. Means for grasping the number of pages and the first printing device In the printing system having means capable of measuring the time during which printing has been stopped on the fixing device of the first printing device, the web that has been stopped on the fixing device of the first printing device passes through the fixing device of the second printing device, The conveyance speed of the fixing device of the second printing apparatus is reduced.

The second means of the present invention is the first means in which the transport speed _Vb when the transport speed of the fixing device of the second printing device is slowed is Y for the length of the fixing device, b for the buffer amount, and the process speed. When V is V, the sheet is conveyed within the range of the speed obtained by Equation 1.

  According to a third means of the present invention, in the first means, a position where the web that has been stopped on the fixing device of the first printing apparatus is normally running immediately before a period during which the web passes the fixing device of the second printing apparatus. The web transport speed on the fixing device side is increased so that the position of the web buffer is moved to the side where the buffer amount is smaller.

According to a fourth means of the present invention, in the first means, the web stopped on the fixing device of the first printing device passes the fixing device of the second printing device, and the web speed V _b When the web is transported and the web buffer position reaches the maximum buffer amount, the web transport speed on the fixing device side is increased so as to move the web buffer position to a position where the web buffer is running normally. It is a feature.

  According to a fifth means of the present invention, the first means includes means for controlling the web conveyance speed so as not to change suddenly when the conveyance speed is changed.

  According to a sixth means of the present invention, in the first means, the second printing device has means for measuring the time during which printing has been stopped on the fixing device of the first printing device, and the web is connected to the first printing device. The web conveyance speed control is not performed when the time during which the fixing device is stopped is short.

  The seventh means of the present invention is the first means, wherein the second printing device has means for measuring the time during which printing has been stopped on the fixing device of the first printing device, and does not carry out web conveyance speed control. The time is changed according to the type of the web.

  The eighth means of the present invention is the first means, wherein the second printing apparatus has means for measuring the time during which printing has been stopped on the fixing device of the first printing apparatus, and the fixing device of the first printing apparatus. When there are a plurality of webs that have been stopped above, only one or two of the webs that have been stopped the longest are slowed down in the conveyance speed of the fixing device of the second printing device. It is.

  According to the present invention, when the portion Wt that is stopped and greatly contracted on the fixing device of the first printing apparatus passes over the preheating plate 13a on the second printing apparatus, the feeding speed of the web W is decreased. Thus, by supplementing the heating roller 13b to compensate for the amount of heat received from the preheating plate 13a by the greatly contracted portion Wt, printing can be performed without greatly reducing the amount of heat received by the greatly contracted portion Wt. It is possible to provide a printing system having a web conveyance speed control method capable of ensuring a stable fixing state between the web W and the toner image and printing.

It is a schematic block diagram of a printing apparatus. 1 is a schematic configuration diagram of a printing system. FIG. 6 is an explanatory diagram illustrating a relationship between web shrinkage and a fixing device. It is explanatory drawing which shows the time of the web which shrunk on the fixing device of a 2nd printing apparatus started to pass. It is explanatory drawing in the case where there are many running positions and buffer amount of a buffer plate, and there are few.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, an embodiment of an electrophotographic printing apparatus applied to the printing system of the present invention will be described with reference to FIG.

  In the figure, W is a web, and usually paper is used. The web W is fed into the printing apparatus P from a feeding device (not shown), guided by the guide roller 1 and conveyed to the web buffer mechanism 2. The web buffer mechanism 2 includes a storage unit 2a that temporarily stores the web W to be transported, a plurality of optical sensors 2d, 2e, 2f, and 2g that detect a slack amount (buffer amount) of the web W, and a web transport direction. And a pair of rollers 2b and 2c provided in the upstream portion. The roller 2c is equipped with an adjusting mechanism for adjusting the pressure contact force to the roller 2b. In this embodiment, the weight 2i is slidably provided on the shaft 2h protruding from one end of the roller 2c, and the pressure contact force of the roller 2c with respect to 2d is adjusted by the lever principle by changing the position of the weight 2i. .

  Since the web buffer mechanism 2 itself is not directly related to the present invention, the description thereof is omitted, but is described in, for example, JP-A-2002-187660. The web W that has passed through the guide member 3 is then fed into the foreign matter removing mechanism 4. The foreign matter removing mechanism 4 is provided with shafts 4a, 4b and 4c, 4d that are fixedly provided. The shafts 4a and 4b are provided with a very narrow interval set in advance, and have a role of preventing foreign matter from entering. The web W is further conveyed to the tension applying mechanism 5.

  The tension applying mechanism 5 includes a drum 5a, a roller 5b provided in pressure contact with the drum 5a, and a drum 5c supported so as to be movable on the web conveyance. The drum 5 is fixed to a free end of an arm 5d that is rotatably supported, and is urged against the surface of the web W by a spring 5e. By providing the tension applying mechanism 5, the tension of the web W is kept constant. Further, the web W is sent to the printing unit 10 by the conveying rollers 8 and 9 through the guide shaft 6 and the guide plate 7.

  In this embodiment, an electrophotographic recording system printing apparatus is used as the printing unit 10, but the present invention is not limited to this type of recording apparatus. When the photosensitive drum 101 exemplified as the image carrier starts to rotate, a high voltage is applied to the corona charger 102, and the surface of the photosensitive drum 101 is uniformly charged with, for example, a positive charge. The light output from the light source 103 composed of a semiconductor laser, a light emitting diode or the like exposes the image on the photosensitive drum 101 and forms an electrostatic latent image on the photosensitive drum 101. When the photosensitive drum area holding the electrostatic latent image reaches a position facing the developing device 104, a developer is supplied to the electrostatic latent image and a toner image is formed on the photosensitive drum 101.

  The toner image formed on the photosensitive drum 101 is sucked onto the web W by the action of the transfer unit 105 that applies a charge having a polarity opposite to that of the toner image to the back side of the web W. The area that has passed the transfer position of the photosensitive drum 101 is cleaned by the cleaning device 106 and prepared for the next printing operation. The web W on which the toner image is transferred from the printing unit 10 as described above is transported to the subsequent stage by the transport belt 11. The conveying roller 8 is provided as a driving roller having a driving source, and is driven by a motor described later. The conveyance roller 9 is provided as a driven roller pressed against the conveyance roller 8 via the web W by the elastic force of the spring 9a. Further, the conveyance belt 11 is supported by being laid over a drive roller 11a and a driven roller 11b, and is provided with a suction device (not shown), and the back surface of the web W is adsorbed onto the conveyance belt 11. It is comprised so that it may convey in the state made to. The web W fed out from the transport belt 11 is transported to the fixing device 13 through the buffer plate 12.

  The web W that has reached the fixing device 13 is preheated by the preheating plate 13a and then heated and pressed by a nip formed by a pair of fixing rollers including a heating roller 13b having a driving source and a pressure roller 13c. The toner image is melted and fixed on the web W by being nipped and conveyed.

  The web W sent out by the heating roller 13b and the pressure roller 13c is transferred by the heating roller 13b and the pressure roller 13c in a printing system in which another second printing device is arranged after the first printing device P. The web W that has been sent out passes through the feed roller 14 and is discharged out of the printing apparatus P as shown by a broken line in FIG. 1, and is conveyed toward the second printing apparatus (not shown).

  The buffer plate 12 is provided with a buffer plate position sensor 12 a that detects the position of the buffer plate 12. The heating roller 13b increases or decreases the speed of the heating roller 13b based on the actual traveling position information from the buffer plate position sensor 12a with respect to the position where the buffer plate 12 is desired to travel. Web conveyance speed correction is performed. By correcting the web conveyance speed, the web W is conveyed while maintaining the position of the buffer plate 12 that normally travels.

  FIG. 2 shows an embodiment of the overall configuration of the duplex printing system according to the present invention.

  This printing system includes two printing apparatuses P1 and P2 having the configuration described with reference to FIG. 1, and a control device 17 connected to both printing apparatuses. Then, the front and back of the web W sent out from the first printing device P1 are reversed by the reversing device T, and then fed into the second printing device P2, and an image is also formed on the second surface of the web W. Is done.

  In the first printing apparatus P1, the web W is kept preheated only for the portion of the web W that is stopped on the preheating plate 13a as time passes, so that the fixing apparatus as shown in FIG. Only a portion of the length Y of 13 is greatly contracted. Here, the second printing apparatus P2 determines that the length of one page of the web W to be printed is L and the number of pages of the web W between the first printing apparatus P1 and the second printing apparatus P2 is X, Assuming that the printing speed is the process speed, the time t until the greatly reduced portion Wt from the start of printing passes over the fixing device of the second printing apparatus P2, and the process speed is V, t is expressed by the following equation (2). .

  The printing system starts printing, and the web W having the greatly contracted portion Wt discharged from the first printing device P1 is sent to the second printing device P2 after being reversed by the reversing device T. Then, after the elapse of t from the start of printing, it passes over the preheating plate 13a.

The second printing apparatus P2 increases the speed of the heating roller 13b in a direction in which the buffer amount decreases with respect to the position Pm where the buffer plate 12 normally travels as shown in FIG. And drive at the position Pd with the smallest buffer amount. Thereafter, after α has elapsed, that is, after the time t has elapsed from the start of printing in the second printing apparatus P2, the partially contracted web W is moved between the preheating plate 13a and the heating roller 13b of the fixing apparatus 13. Let T _b be the time taken to pass.

Within the period of the T _b, to the most common position Pu from the smallest position Pd of the buffer amount, so that a buffer position is varied to convey the heating roller 13b in the conveying speed V _b, the buffer amount smallest when the difference between the buffer amount from the position Pd to the most common position Pd and the buffer variation b, time T _b which passes through the fixing portion of the contracted portion Y is the length Y at a speed V _b is the number It can be expressed as 3.

The speed of the web W fed from the marked copy unit is a process speed V, and when conveyed at speed V _b of the heating roller 13b, the buffer amount of b inches resulting in reduced during the time T _b From the above, it can be expressed as Equation 4.

From Equation 3 and Equation 4, _Vb is obtained as in Equation 5.

The heating roller 13b conveys the web W at a conveyance speed capable of improving the fixing strength at a speed higher than _Vb calculated by Equation 5, and the position of the buffer plate 12 is equal to the buffer amount. This state is continued until the buffer plate position sensor 12a detects that it has moved to Pu, which is the most frequent position.

  Thereafter, the conveyance speed of the heating roller 13b is increased, and the position of the buffer plate 12 is returned to the normal running position.

When the position of the buffer plate 12 is moved from the normal running position Pm to the position Pd with the smallest buffer amount, the speed of the heating roller 13b is increased, or the position from the position Pd with the smallest buffer amount is the largest. When the web W is transported to the position Pd at the transport speed _Vb of the web W, when the transport speed of the web W is changed, the web W is transported when the toner image is transferred from the printing unit 10. By rapidly changing the speed, the conveyance speed of the web W is changed stepwise so as not to swing on the web W.

  In the above description, while the second printing apparatus stops printing, the first printing apparatus also stops printing by the control device 17.

  Here, “the time when the second printing apparatus is stopped” can be considered as “the time when the web W is also stopped on the preheating plate 13a of the first printing apparatus”.

  When the second printing apparatus is stopped for a short time, the second printing apparatus performs the conventional web conveyance speed control because the shrinkage of the web W is small. Here, the time for determining that the time is short is changed depending on the type of the web W being printed at that time. For example, when the web W is a web with little thermal deformation, the time for determining that the web W is short is set long.

  In addition, when the number of pages smaller than the number of pages of the web W between the first printing device P1 and the second printing device P2 is printed and stopped, and this operation is repeated, there are a plurality of contracted portions of the web W. Therefore, the second printing apparatus transports only one or two places that have been stopped for a long time among the places that have been stopped for a long time such that this control is necessary. Implement speed control.

W ... Web, Wt ... Deformed portion of web W, 12a ... Buffer plate position sensor, 12 ... Buffer plate, 13a ... Preheater, 13b ... Heating roller, 13c ... Pressure roller, Pu ... Buffer amount is the largest position, the heating roller speed when moving Pm ... normal running position, the smallest position of Pd ... buffer amount, the most common position from the smallest position of V b _... buffer amount, b ... buffer amount, Y ... Length of web W greatly shrunk, V ... process speed, t ... time from the start of printing until a part greatly shrunk passes through the fixing device of the second printing device, X ... between the first printing device and the second printing device Number of pages of web W in L, length of one page of web W

JP-A-8-50429 JP-A-6-274056

Claims (8)

A first printing device that forms an image on a first surface of a web; and a second printing device that is provided downstream of the first printing device and forms an image on a second surface of the web. The apparatus and the second printing apparatus are provided with a printing apparatus for forming an image on the web, a preheating plate for fixing the image on the web, preheating the web and the toner image, A fixing device configured to press and heat by arranging a heating roller and a pressure roller, and a web buffer device for absorbing a web conveyance speed difference between the printing device and the fixing device. The second printing device has a means for grasping the length of one page of the web to be printed and a means for grasping the number of pages of the web between the first printing device and a fixing device of the first printing device. A means to measure the time during which printing was stopped In a printing system having,
A web conveyance speed control characterized by slowing the conveyance speed of the fixing device of the second printing apparatus during a period when the web stopped on the fixing apparatus of the first printing apparatus passes through the fixing device of the second printing apparatus. A printing system having a method. The transport speed V _b when the transport speed of the fixing device of the second printing apparatus is slow is the speed obtained by the following equation when the length of the fixing device is Y, the buffer amount is b, and the process speed is V. The printing system having a web conveyance speed control system according to claim 1, wherein the printing is performed in a range.

  The position of the web buffer to the side where the buffer amount is smaller than the normal traveling position immediately before the period when the web stopped on the fixing device of the first printing apparatus passes the fixing apparatus of the second printing apparatus The printing system having a web conveyance speed control system according to claim 1, wherein the web conveyance speed on the fixing device side is increased so as to move the web. In a period in which the web stopped on the fixing device of the first printing apparatus passes through the fixing device of the second printing apparatus, the web is conveyed at the conveyance speed _Vb , and the position of the web buffer is the maximum buffer. 2. The web conveyance speed control system according to claim 1, wherein the web conveyance speed on the side of the fixing device is increased so that the web buffer position is moved to a position where the vehicle is normally running when the amount is reached. Having printing system.   2. A printing system having a web conveyance speed control system according to claim 1, further comprising means for controlling the web conveyance speed so as not to change abruptly when the conveyance speed is changed.   The second printing device has means for measuring the time during which printing has been stopped on the fixing device of the first printing device, and when the time when the web has been stopped on the fixing device of the first printing device is short, 2. A printing system having a web conveyance speed control system according to claim 1, wherein the web conveyance speed control system is not implemented.   The second printing device has means for measuring the time during which printing has been stopped on the fixing device of the first printing device, and the time during which the web conveyance speed control method is not performed is changed depending on the type of the web. A printing system having the web conveyance speed control system according to claim 1.   The second printing device has means for measuring the time during which printing has been stopped on the fixing device of the first printing device, and when there are a plurality of webs that have been stopped on the fixing device of the first printing device. 2. The printing system having a web conveyance speed control system according to claim 1, wherein the conveyance speed of the fixing device of the second printing apparatus is reduced only at one or two of the longest stops.

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