JP2008292795A - Paper meandering correction control system in electrophotographic system printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper meandering correction control system which performs operation for opening and closing and the correction of paper-meandering by one motor without separating a motor, prevents thickening of a printed character due to excessive fixation easy to occur when paper conveyance is started, and also performs the paper conveyance without meandering a printed paper. <P>SOLUTION: The paper conveyance is started from a position overrunning by a predetermined angle amount from a cam shaft position where the loads of A and B sides are uniform in the close position of a heat roll and a pressure roll, so as to correct the printed paper meandered at the beginning of the start of the paper conveyance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a paper meandering correction control in a paper transport mechanism of an electrophotographic printing apparatus such as a laser beam printer or a copying machine.

  An example of an electrophotographic apparatus such as a copying machine or a laser beam printer as a printing apparatus having a sheet conveying apparatus that conveys a sheet and a meandering correction apparatus that corrects the meandering amount of the sheet will be described.

  A conventional printing apparatus is provided with a paper meandering correction device and its control device in order to cope with various printing papers such as paper quality, paper thickness, and dimensions in addition to improvement in printing speed and printing quality.

  Even in the paper transport device, the fixing device adopting the pressure roll method has a great influence on the paper running performance. Especially in the laser beam printer for continuous paper, there is an example in which the fixing device has a paper meandering correction device. Many are known.

  As shown in FIG. 5, an electrophotographic apparatus such as a laser beam printer for continuous paper moves the printing paper 201 at the same speed as the cycle of the photosensitive drum 202 by the tractor 203, and transfers the toner image onto the printing paper 201 by the transfer device 208. Let After that, after passing through the buffer 204 for applying a constant tension to the printing paper 201, passing through the paper transport guide 205, the toner image is pressurized and heated by the heat roll 206 and the pressure roll 207, and melted and fixed on the printing paper 201. Let Then, the printing paper 201 is pulled with a constant tension by the puller 211 and the pulling roll 210, the printing paper 201 is folded by the swing fin 212 for folding the printing paper 201, and then the printing paper 201 is conveyed to the stacker 213 on which the printing paper 201 is stacked. .

  In the electrophotographic apparatus having the above-described configuration, the printing paper 201 is driven by two driving operations, that is, pin driving by the tractor 203 and frictional driving of the thermal roll 206-printing paper 201-pressure roll 207. In the portion where the printing paper 201 is conveyed by the frictional force between the pressure rolls 207, the printing paper 201 meanders from side to side, whereby stress is applied to the printing paper 201, and feed holes are pierced or wrinkled. Therefore, the meandering of the printing paper 201 is corrected by detecting the meandering of the printing paper 201 by the sensor 209 and changing the load of the heat roll 206 and the pressure roll 207 left and right with respect to the support shaft of the heat roll 206. A straightening device is added.

  FIG. 6 shows an example of a conventional meandering correction device. The heat roll 206 is rotatably supported at a fixed position by a support unit (not shown) and a drive unit. The pressure roll 207 faces the heat roll 206 with the printing paper 201 interposed therebetween.

  The pressure roll 207 has a structure movable in the radial direction along a guide groove (not shown). The means for pressing the pressure roll 207 against the heat roll 206 includes an arm 304, a pair of left and right cams 302, and a spring 307, and one set is provided at each end of the pressure roll 207. The arm 304 has a bearing 305 at one end and is rotatably supported by a frame (not shown). One end of a spring 307 is connected to the other end of the arm 304 and is pulled toward the heat roll 206. The cam 302 is installed at a position in contact with a cam follower 303 provided on the arm 304. The cam 302 is set on the same axis as the cam shaft 306, and the cam shaft 306 is rotatably supported by a frame (not shown) and can be rotated by the motor 301. A rotatable shaft protrudes from both ends of the pressure roll 207, and the shaft is always in contact with a part of the arm.

  At the time of non-printing, the pressure roll 207 and the heat roll 206 are stopped at a position (open position) where they are not in contact with each other. At the time of printing, the cam 302 is separated from the cam follower 303 due to the rotation of the cam shaft 306. It stops at a position (closed position) where 207 completely contacts the heat roll 206. At this time, the spring 307 presses the pressure roll 207 so that the printing paper 201 is sandwiched between the heat roll 206 and the pressure roll 207, and the pressure roll 207 is driven by the rotation of the heat roll 206 and the printing paper 201 is fixed. Be transported.

  The print paper feed position is detected by the sensor 209. When it is detected that the printing paper 201 is shifted to the left in the paper feeding position in the paper feeding position, the motor 301 rotates the camshaft 306 counterclockwise when viewed from the left side.

  This movement causes the left cam 302a to come into contact with the cam follower 303, and slightly pushes back the arm 304a against the left spring force. As a result, the load on the left side of the pressure roll 207 is smaller than that on the right side, and the conveyance force on the left side of the sheet is smaller than that on the right side, so that the sheet feeding position is shifted to the right side. In this way, the paper feeding position shift (meandering) can be corrected. When meandering to the right, the opposite operation is performed.

  That is, as shown in FIG. 3, when it is desired to bend the printing paper 201 to the A side, the load of the heat roll 206 and the pressure roll 207 is increased on the A side and lower on the B side, thereby causing the heat roll 206 and the pressure roll to press. In the roll 207, the A-side diameter ra is compressed and becomes smaller than the B-side diameter rb, and the peripheral speed of the heat roll 206 and the pressure roll 207 is higher on the B side (Vra <Vrb). Therefore, the amount of movement of the conveyed printing paper 201 is greater on the B side than on the A side, and the printing paper 201 approaches the A side. Conversely, when it is desired to bend the printing paper 201 to the B side, similarly, the printing paper 201 approaches the B side by increasing the load of the heat roll 206 and the pressure roll 207 on the B side and lowering the A side. .

  FIG. 2 is a timing chart from the reception of a print start signal to the start of the paper meander correction control in the conventional printing apparatus, and shows that each signal is valid when the state is “1”. At the time of non-printing, the heat roll 206 and the pressure roll 207 are in the open position, but after receiving a print start signal from a host controller (not shown) (state in FIG. 2A), the motor is TA (ms) later. 301 rotates and starts the closing operation of the heat roll 206 and the pressure roll 207 (the state of FIG. 2B), and the camshaft 306 has an angle of 180 degrees at which the left and right load balance becomes uniform after TC (ms). The closing is stopped (state shown in FIG. 2D). On the other hand, the printing paper 201 starts to be conveyed in advance from the timing when the heat roll 206 and the pressure roll 207 after TB (ms) are stopped after receiving the print start signal (state in FIG. 2C). The paper meandering correction control is started from the timing when the heat roll 206 and the pressure roll 207 are closed (the state shown in FIG. 2D).

  FIG. 4 shows the angle of the camshaft 306 and the left and right load changes of the heat roll 206 and the pressure roll 207. In the conventional meandering correction device, the thermal roll 206 and the pressure roll 207 are set to the open position when printing is not performed, and the left and right load balance between the thermal roll 206 and the pressure roll 207 is adjusted by adjusting the operation to the closed position during printing. In order to use a single motor for correcting the meandering of the paper, the left and right sides of the cam 302 set on the same axis of the camshaft 306 are reversed so that the camshaft 306 has an angle of 0 degrees. (State of FIG. 4-a) and 180 degree closed position (state of FIG. 4-c), the right and left load balance of the heat roll 206 and the pressure roll 207 is equal, but the camshaft angle is In the range of 40 degrees to 180 degrees, the load on the A side is high, and in the range of 180 degrees to 320 degrees, the load on the B side is high. The point of the camshaft 306 at an angle of 140 degrees (state shown in FIG. 4-b) corresponds to the timing (state shown in FIG. 2-c) at which the printing paper 201 starts to be conveyed.

  For example, the following patent documents can be cited regarding this type of technology.

JP 2003-160262 A

In the conventional printing apparatus, if the paper conveyance is started from the position where the heat roll 206 and the pressure roll 207 stop closing at the start of printing (the angle of the camshaft 306 is 180 degrees), the printed characters become thick due to overfixing. Therefore, it is necessary to start the paper conveyance start timing before the heat roll 206 and the pressure roll 207 stop closing. For this reason, in the initial stage of paper conveyance, the heat roll 206 and the pressure roll 207 come in contact from the A side, the load on the A side becomes transiently high, paper meandering occurs, and paper meandering jam is detected. There was a drawback.

  An object of the present invention is to solve such drawbacks of the prior art, and perform an open / close operation and a motor for correcting the meandering of the paper with a single motor without being separated, and overfixing that is likely to occur at the start of paper conveyance. It is an object of the present invention to provide a paper meandering correction control system that can prevent the printing character from becoming thicker and can transport the paper without meandering the printing paper.

  In order to achieve the above object, the present invention comprises a heat roll and a pressure roll for fixing the toner image transferred on the paper by heating and pressing, and a drive unit for driving the pressure roll; A paper position detecting means for detecting the meandering amount of the paper, and a means for calculating and storing a meandering correction amount from the meandering amount of the paper detected by the paper position detecting means; In an electrophotographic printing apparatus having a meandering correction device that corrects the meandering of a sheet by varying the pressure difference between the right and left of a thermal roll and the pressure roll, the meandering of the sheet is corrected in a fixed direction in advance when the conveyance of the sheet is started. It is characterized by doing.

  In the present invention, the opening / closing operation and the motor for correcting the paper meander are separated by setting the first closed position of the heat roll and the pressure roll at the start of paper conveyance to a position overrun by a predetermined angle. Therefore, it is possible to prevent the printing character from being thickened by overfixing, which is likely to occur at the start of paper conveyance, and to convey the paper without meandering.

  As will be described later, the present invention has been realized by devising control by a microprogram without adding mechanical parts and motors related to a meandering correction mechanism for printing paper.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a timing chart from the reception of a print start signal to the start of paper meander correction control according to the present invention, and shows that each signal is valid when in the state “1”.

  After receiving a print start signal from a host controller (not shown) (state shown in FIG. 1A), after TA (ms), the closing operation of the pressure roll 207 is started (state shown in FIG. 1B). ms) After that, the conveyance of the printing paper 201 is started (FIG. 1-c). The operation so far is the same as the timing chart of the conventional printing apparatus shown in FIG.

  In the present embodiment, the first closing stop position of the pressure roll 207 is set at an angle 180 degrees of the camshaft 306 at which the loads on the A side and B side of the heat roll 206 and the pressure roll 207 are equal (in FIG. 1-d). ), But 20 degrees overrun (state shown in FIG. 1-e) and stopped at a position where the load on the B side is high. Further, the paper meandering correction control is started after TX (ms) has elapsed, which corresponds to a time during which the printing paper 201 is conveyed by 1/2 inch or more (state shown in FIG. 1-f).

  That is, as shown in FIG. 4, in the closing operation of the heat roll 206 and the pressure roll 207, the printing paper 201 always starts from the state where the load on the A side is high (b) to (c) in the initial stage of paper conveyance. Since it is conveyed, it is conveyed while meandering to the A side. Therefore, since it is necessary to cancel the amount of meandering to the A side at the beginning of paper conveyance start, the load on the A side and B side of the heat roll 206 and the pressure roll 207 is more than the position where the load is equal. Further, by rotating the camshaft 306 until the load on the B side is high (between c and d in FIG. 4), the printing paper 201 meandering on the A side is corrected at the beginning of paper conveyance. As a result, stable paper transport can be realized from the start of paper transport, and jamming due to paper meandering can be reduced.

  Note that the angle at which the camshaft 306 is overrun differs in the meandering correction effect depending on the thickness and width of the printing paper 201. Therefore, the data for causing the memory element in the control board (not shown) to overrun and the paper meandering control are started. A plurality of times are prepared and stored, and can be selected as necessary. This means for selection is possible from an operator panel (not shown).

  The present invention can be used in a printing apparatus having a mechanism for correcting the opening and closing of a pressure roll and a heat roll and the meandering of a sheet with a single motor.

6 is a timing chart from the start of printing to the start of paper conveyance according to an embodiment of the present invention. 6 is a timing chart from the start of printing to the start of paper conveyance in a conventional printing apparatus. It is a schematic diagram which shows the state of the heat roll and pressure roll at the time of meandering correction | amendment in a paper meandering correction apparatus. It is a figure which shows the load change of a cam shaft angle, a heat roll, and a pressure roll. It is the schematic diagram which showed the laser beam printer for continuous paper as an example of a printing apparatus. It is a schematic diagram of the conventional paper meandering correction apparatus.

Explanation of symbols

  201, printing paper, 202, photosensitive drum, 203, tractor, 204, buffer, 205, paper conveyance guide, 206, heat roll, 207, pressure roll, 208, transfer device, 209, sensor, 210, puller roll, 211 Is a puller, 212 is a stacker, 213 is a stacker, 301 is a motor, 302 is a cam, 303 is a cam follower, 304 is an arm, 305 is a bearing, 306 is a camshaft, and 307 is a spring.

Claims (3)

  A heat roll and a pressure roll for fixing the toner image transferred on the paper by heating and pressing, a driving unit for driving the pressure roll, and a paper position for detecting the meandering amount of the paper Detecting means, and means for calculating and storing the meandering correction amount from the meandering amount of the paper detected by the paper position detecting means, and by means of the pressure roll drive unit, the right and left sides of the heat roll and the pressure roll In an electrophotographic printing apparatus having a meandering correction device that corrects meandering of a paper by varying a pressure difference, the meandering correction control for paper meandering in advance in a certain direction at the start of conveyance of the paper method.   2. The paper meandering correction control system according to claim 1, wherein the timing of starting the paper meandering correction in a certain direction at the start of transport of the paper is from the time when the paper is transported by 1/2 inch or more. Paper meandering correction control system.   3. The paper meandering correction control system according to claim 1 or 2, wherein the timing of starting the paper meandering correction and the amount of paper meandering correction in a fixed direction at the start of transporting the paper can be changed. method.

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