JP2016108105A - Pretreatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize conveying performance of a recording medium when starting image formation by correcting curvature habits of the recording medium without increasing the cost and delaying a first print time.SOLUTION: A pretreatment device includes: application means 20 for applying pretreatment liquid to a long recording medium 7; a plurality of heating means 23a; conveyance means 24; buffer means 16; and control means 38. The control means 38 controls the operations of the conveyance means 24 and vertical movement means 31 so that the buffer means 16 is raised higher than a specified position A occupied by the buffer means during the conveyance accompanying the recording of the recording medium 7 while decelerating conveyance speed when the conveyance accompanying the recording of the recording medium 7 is stopped. The control means controls the operations of the conveyance means 24 and the vertical movement means 31 so that the buffer means 16 is lowered for a prescribed period until there is no influence on the recording medium 7 by heating of the heating means 23a after the conveyance of the recording medium 7 is stopped, conveys the recording medium 7 in a prescribed length range, and shifts a contact position between the heating means 23a and the recording medium 7.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pretreatment device.

  In an image forming apparatus such as a rotary press or an ink-jet printer, in order to prevent the occurrence of phenomena such as feathering, bleeding, and show-through, a pre-coating liquid having an effect of aggregating ink is applied to a recording medium before image formation. A pretreatment device equipped with a heat roller is used.

  In this pre-processing apparatus, the recording medium stopped on the heat roller when image formation is stopped causes moisture to evaporate, causing fiber shrinkage, and deforms following the shape of the heat roller. When this deformation occurs, the color superimposition accuracy deteriorates and color misregistration occurs, or the ink on the deformation part comes into contact with the apparatus or the like, causing ink rubbing, and the image quality deteriorates. Further, when the deformable portion comes into contact with the apparatus, the contacted part of the apparatus may be damaged, or the recording medium may be clogged.

  In order to suppress such an adverse effect resulting from the deformation of the recording medium, a method is adopted in which image formation is not performed on the deformed portion, or a portion that may be damaged is retracted. As a method for suppressing deformation of the recording medium, a method is known in which the recording medium is reciprocated to disperse the pressed portions in order to prevent the recording medium from being deformed by the pressing roller, although it is not a heat roller portion. This is because the recording medium is intermittently moved in the image forming standby direction and in the opposite direction during image formation standby in order to provide a device that suppresses deterioration of quality such as whiteout due to deformation of the recording medium by pressing of the pressing roller. To be moved. The recording medium is buffered when it moves intermittently, and the transport direction is reversed when the buffer amount of the recording medium reaches a predetermined amount (see, for example, “Patent Document 1”).

  However, the above-described method for retracting the contact portion without forming an image on the deformed portion is merely a countermeasure that does not suppress the deformation of the recording medium itself but does not use the deformed portion, and uses the image forming apparatus. One has to discard the recording medium, and there is a problem that the recording medium is wasted. In addition, the deformation suppression method using the pressing roller is intended to disperse the deformation amount of the recording medium due to the pressurization, and it follows the shape of the roller by stopping on the heat roller and evaporating moisture to cause fiber contraction. There is a problem that the curved wrinkles of the recording medium cannot be corrected and the deformed recording medium is wasted.

  Therefore, as a countermeasure against the curling wrinkles of the recording medium, the recording medium is transported in the direction opposite to that at the time of image formation before receiving the image forming signal and heating of the heat roller is started. By passing the recording medium through the recording medium, a portion having a curved wrinkle is wound around the heat roller at least once in a direction opposite to the curving direction, whereby a method of correcting the curved wrinkle of the recording medium can be considered.

  However, in this method, a buffer mechanism capable of absorbing the conveyance amount for reciprocating the recording medium before and after the heat roller and two or more paper conveyance mechanisms are essential. Ordinary pre-processing apparatuses do not have such a buffer mechanism and often have only one paper transport mechanism.

  If the above-described configuration is adopted, the cost increases because the buffer mechanism and the paper transport mechanism are provided, and the reciprocating movement of the recording medium needs to be performed after the heat roller rises to the control temperature during image formation. It is conceivable that the preparation operation time at the start of image formation is extended by the time required for the reciprocating operation of the recording medium, and the first print time is delayed.

  The present invention provides a pre-processing apparatus capable of correcting the curl of a recording medium and stabilizing the transportability of the recording medium at the start of image formation without increasing the cost and delaying the first print time. For the purpose of provision.

  The present invention includes an application unit that applies a pretreatment liquid to a long recording medium, a plurality of heating units that heat the recording medium at a predetermined temperature, a conveying unit that conveys the recording medium, and a vertical movement unit. A buffer means for storing the recording medium for a predetermined length while applying tension to the recording medium conveyed by the conveying means; and a control means for controlling the operations of the conveying means and the vertical movement means. The control means is less than a prescribed position occupied by the buffer means during conveyance accompanying recording of the recording medium during deceleration of the conveyance speed of the recording medium when stopping conveyance associated with recording of the recording medium. The operation of the conveying means and the vertical movement means is controlled so as to rise, and after the conveyance of the recording medium is stopped, there is no influence on the recording medium due to the heating of the heating means. In order to lower the buffer means during the period, the recording medium is conveyed within the predetermined length by controlling the operation of the conveying means and the vertical movement means, and the contact position between the heating means and the recording medium is determined. It is characterized by shifting.

  According to the present invention, the thermal contraction of the recording medium can be suppressed by shifting the contact position between the high-temperature heating means and the recording medium without increasing the cost due to the existing configuration, and the recording medium can be stabilized. It can be transported in the state.

1 is a schematic diagram of an image forming line to which an embodiment of the present invention can be applied. It is the schematic of the pre-processing apparatus used for one Embodiment of this invention. It is the schematic which shows the relationship between the image formation process in one Embodiment of this invention, and the position of a buffer means. 6 is a flowchart illustrating a control operation from when image formation is stopped to when an image formation operation is completed according to an embodiment of the present invention. 6 is a flowchart illustrating a control operation in an image formation preparation period according to an embodiment of the present invention.

  FIG. 1 shows a double-sided image forming line to which an embodiment of the present invention can be applied. In this order from the upstream side in the paper conveyance direction, the paper feeding device 1, the pre-coating device 2 as the pre-processing device, the ink jet printer 3 for forming the front surface image, the reversing device 4, the ink jet printer 5 for forming the back surface image, the paper storage The apparatus 6 is comprised. A sheet 7 as a recording medium used in the present embodiment has a long shape, and is stored in a roll shape on a sheet storing member 8 provided in the sheet feeding apparatus 1. The paper 7 sent out from the paper feeding device 1 is sent to a pre-coating device 2 to be described later, which pre-processes the paper 7.

  The sheet 7 sent out from the pre-coating device 2 forms a surface image on one surface thereof by the ink jet printer 3 and is then discharged to the reversing device 4. The sheet 7 sent to the reversing device 4 is sent to the ink jet printer 5 with the front and back reversed, and a back image is formed on the other side. The paper 7 on which images are formed on both sides is sent to the paper storage device 6, and is wound around a paper storage member 9 provided in the paper storage device 6 in a roll shape.

  FIG. 2 shows the pre-coating device 2. The paper 7 fed from the paper feeding device 1 is stretched around each of the rollers 10, 11, 12, 13, 14, 15 and the ink jet printer 3 via the buffer means 16 disposed at the most downstream position in the paper transport direction of the device. Sent to. Between the roller 11 and the roller 12, a first application unit 17 that applies a treatment liquid (an application liquid) having an effect of aggregating ink on the paper 7 is disposed. The first application unit 17 includes an application roller 18 and a pressure roller 19, and the pressure roller 19 presses the paper 7 against the application roller 18 that is rotationally driven with the stored processing liquid on the surface. As a result, the treatment liquid is applied to the surface of the sheet 7. Between the roller 13 and the roller 14, there is disposed a second coating unit 20 having a coating roller 21 and a pressure roller 22 and configured similarly to the first coating unit 17. The processing liquid is applied to the back surface of the sheet 7 by 20.

  A drying device 23 having a heat roller 23a as a plurality of heating means is disposed on the most downstream side of the second coating means 20 in the sheet conveying direction. The paper 7 on which both sides of the processing liquid are applied by the application means 17 and 20 is dried when the paper 7 passes through the heat rollers 23a of the drying device 23, and enters an image formation standby state. Stored in the means 16. On the downstream side of the drying device 23 in the sheet conveyance direction, a conveyance roller 24 is disposed as a conveyance unit that conveys the sheet 7. The transport roller 24 is rotationally driven by the transport motor 25 in the direction of transporting the paper 7 in the direction of the arrow in FIG. 2, and the transport roller 24 has a pressure roller 26 that presses the paper 7 against the transport roller 24 with a predetermined pressure. Abutment is arranged.

  A roller 15 is disposed downstream of the transport roller 24 in the paper transport direction, and a buffer unit 16 is disposed further downstream of the transport roller 24 in the paper transport direction. The buffer means 16 includes three fixed rollers 27, 28, 29, a dancer roller 30 that can move up and down, a vertical movement means 31 that moves the dancer roller 30 up and down, and the like. Each fixed roller 27, 28, 29 is rotatably supported by the main body of the pre-coating device 2 and rotates at a fixed position. The fixed roller 29 is configured to be rotatable only in the counterclockwise direction in FIG. Yes. The dancer roller 30 has two rotatable rollers, and each roller is configured to be fitted between the fixed rollers 27 and 28 and between the fixed rollers 28 and 29. The dancer roller 30 is supported by a rail member (not shown) so as to be movable up and down.

  Up and down moving means 31 is disposed on the right side of each of the fixed rollers 27, 28, 29 and the dancer roller 30. The vertical movement means 31 has a pair of timing pulleys 32, 33, a timing belt 34 spanned between the timing pulleys 32, 33, and a lift motor 35 that can rotate forward and reverse to rotate the timing pulley 32. . A dancer roller 30 is connected to the timing belt 34. Further, a one-way clutch 36 is interposed between the lifting motor 35 and the timing pulley 32, and the encoder 37 for detecting the height position of the dancer roller 30 is provided on the timing pulley 32.

  With the above-described configuration, the traveling direction of the timing belt 34 is changed by changing the rotation direction of the lifting motor 35, and the dancer roller 30 can be lifted and lowered. Further, due to the action of the one-way clutch 36, all the driving force of the lifting motor 35 is transmitted to the timing belt 34 in the upward direction of the dancer roller 30, but almost no driving force is transmitted in the downward direction. Therefore, when the dancer roller 30 is lowered while the paper 7 is passing, the dancer roller 30 hits at a position corresponding to the length of the paper 7 stored between the fixed roller 27 and the fixed roller 29. And stop. At this time, the dancer roller 30 is hung from the paper 7, and a tension corresponding to the weight of the dancer roller 30 is applied to the paper 7. Based on the information from the encoder 37, the conveyance speed of the conveyance roller 24 is determined based on the height position of the dancer roller 30.

  Below the apparatus main body of the pre-coating apparatus 2, a control means 38 comprising a well-known microcomputer having a CPU, ROM, RAM and the like is disposed. The control unit 38 controls the operations of the transport motor 25 and the lifting motor 35 based on the position information of the dancer roller 30 obtained from the encoder 37. The control means 38 is connected to the ink jet printer 3 through an interface cable, and receives signals such as processing liquid application conditions (amount, front and back, etc.), drying temperature, paper speed information, various start and stop signals from the ink jet printer 3. Then, the pre-coating device 2 is controlled. During the conveyance of the sheet 7, the dancer roller 30 continues to apply tension to the sheet 7 by moving in the downward direction, and moves up and down according to the speed difference between the inkjet printer 3 and the conveyance roller 24. The transport roller 24 is speed-controlled by the control means 38 so as to maintain a control line at a specified position, which is indicated by a symbol A in FIG. 2 where the dancer roller 30 has a constant height. Specifically, the dancer roller 30 is controlled to accelerate when it moves upward from the control line A, and to decelerate when it moves downward.

  In the above-described configuration, in the pre-coating device 2 after image formation, the paper 7 stopped in the drying device 23 is thermally contracted by contact with the heat roller 23a, and is in a zigzag pattern in which the heat roller 23a is disposed. There is a problem of bending. The present invention solves this problem and suppresses the curling wrinkles of the paper 7 so that the paper 7 can be stably conveyed during the next image formation.

Control of the pre-coating device 2 in one embodiment of the present invention will be described below.
Before the image formation is completed and the sheet conveyance is stopped, the control unit 38 controls the operation of the conveyance motor 25 so that the dancer roller 30 occupies the position B shown in FIG. Specifically, the speed information received from the ink jet printer 3 is confirmed, and the dancer roller 30 is raised by decelerating the transport roller 24 at a speed faster than the speed information received from the ink jet printer 3 when the transport speed is reduced. . Further, before the image formation is decelerated upon completion of image formation, control is performed so that the height of the dancer roller 30 is set to the position B when receiving a coating stop signal. In this way, by changing the height of the dancer roller 30 in advance before the end of image formation, it is possible to perform deceleration control while maintaining a stable state without sudden deceleration.

  When the conveyance is stopped and the image forming operation is completed, the dancer roller 30 is stopped in the state where the position B is occupied. Each of the heat rollers 23a shifts from heating control during image formation to control during stoppage, and the control temperature is lowered to be in an OFF state. However, immediately after the completion of image formation, residual heat still remains, and the high temperature state continues for a while. . During this period, the dancer roller 30 is lowered little by little while rotating the conveyance roller 24 in the conveyance direction, and the dancer roll 30 is lowered to the position C shown in FIG. At this time, the dancer roller 30 can be slowly lowered little by little by rotating the conveyance roller 24 at a low speed and repeating intermittent conveyance. Further, by driving the transport roller 24 while lowering the dancer roller 30, the control can be performed without transporting the sheet 7 to the downstream side of the pre-coating device 2. In this way, the conveyance control of the sheet 7 is performed until the heat roller 23a reaches room temperature while the contact position between the heat roller 23a and the sheet 7 is gradually shifted.

  With the above-described configuration, it is possible to suppress the occurrence of thermal contraction on the sheet 7 after the end of image formation by shifting the contact position between the high-temperature heat roller 23a and the sheet 7 without increasing the cost due to the existing configuration. The paper 7 can be conveyed in a stable state. When the temperature of the heat roller 23a is lowered to room temperature, the dancer roller 30 is lowered to the position C. Thus, the control at the end of image formation is completed, and the pre-coating device 2 is in a normal stoppage control.

  The next image formation is started from the normal stop state. When the image formation preparation start signal is received from the ink jet printer 3, the heat roller 23a heats up to the control temperature during image formation. During this period, the dancer roller 30 is lowered while rotating the transport roller 24 little by little in the transport direction, and the dancer roller 30 is controlled to occupy the control line A. When the heat roller 23a is heated to the control temperature during image formation, the dancer roller 30 is lowered to the control line A, and the pre-coating device 2 is ready for image formation. Then, the inkjet printer 3 is notified that preparation is complete, and image formation is started.

  Next, a change in the position of the dancer roller 30 from the time when image formation is completed to the time when re-image formation is started in the control described above will be described with reference to FIG. The period a is a period during image formation, and the transport roller 24 transports the paper 7 based on the speed data received from the ink jet printer 3. At this time, the dancer roller 30 occupies the control line A, and the heat roller 23a is controlled by the drying temperature at the time of image formation, and heat-drys the paper 7 being conveyed.

  Next, in order to complete image formation, the inkjet printer 3 sends a signal requesting completion of application of the treatment liquid to the pre-coating device 2 at time point b, and starts deceleration. The pre-coating device 2 receives the signal from the ink jet printer 3 and completes the application of the treatment liquid and starts deceleration. At this time, the conveyance roller 24 is controlled so as to have a speed slower than the speed data sent from the ink jet printer 3, and the dancer roller 30 is moved from the control line A to the position B in the period c until the speed is reduced and stopped. Control to raise.

  When the conveyance of the sheet 7 is stopped and the image formation is completed at the time point d, the heat roller 23a is changed from the control temperature at the time of image formation to the temperature at which the heat roller 23a is stopped, and is turned off. However, the temperature of the heat roller 23a does not drop immediately, but remains high for a while due to residual heat. For this reason, the paper 7 that is in contact with the heat roller 23a undergoes thermal shrinkage, resulting in curving wrinkles. Therefore, during the period e from when the surface temperature of the heat roller 23a drops to return to room temperature, the dancer roller 30 is lowered while the transport roller 24 is rotated little by little to shift the contact position between the paper 7 and the heat roller 23a. To control. Thereby, generation | occurrence | production of the curved wrinkle to the paper 7 can be suppressed. Further, by combining the transport amount of the sheet 7 generated as the dancer roller 30 is lowered with the transport amount of the sheet 7 by the transport roller 24, the sheet 7 is not loosened and is transported to the downstream side of the pre-coating device 2. Therefore, the inkjet printer 3 is not affected.

  In the period e, the control unit 38 controls the operations of the transport roller 24 and the dancer roller 30 so that the dancer roller 30 descends from the position B to the position C. At this time, the lowering and stopping of the dancer roller 30 are repeated four times in FIG. 3, but the number of repetitions is not limited to this as long as the heat shrinkage to the paper 7 does not occur and the conveyance amount. If it is sufficient to rotate the transport roller 24 at a low speed and lower the dancer roller 30 from the position B to the position C in the period e, it is not necessary to repeat the intermittent transport, and the dancer roller 30 is controlled by one lowering control in the period e. It may be lowered from position B to position C. When the surface temperature of the heat roller 23a drops to room temperature at the time point f, there is no risk of thermal contraction of the paper 7 that is in contact with it, so the period after the operation of the transport roller 24 and the dancer roller 30 is stopped. g is a conventional stop state.

  Next, in order to start image formation again at time h, the inkjet printer 3 sends a signal to start image formation preparation to the pre-coating device 2. Upon receiving this signal, the pre-coating device 2 starts preparation for application and drying control during image formation. At this time, the heat roller 23a heats up to the control temperature at the time of image formation. Since the conveyance of the sheet 7 is stopped during the period i from when the heating of the heat roller 23a is completed until the sheet 7 is conveyed, the part in contact with the heating heat roller 23a is the same as the period e. Heat shrinkage occurs. Therefore, in the period i as well as in the period e, the control unit 38 controls the operations of the transport roller 24 and the dancer roller 30 so that the dancer roller 30 descends from the position C to the control line A. The control method is the same as in the period e. The dancer roller 30 is set on the control line A in the period i, and after the tension is applied to the sheet 7, the sheet conveyance is started at the time j.

  FIG. 4 is a flowchart for explaining a control method when the image forming operation is stopped according to the embodiment of the present invention. This flowchart is an operation control of the conveying roller 24 and the dancer roller 30 by the control means 38 in the period from the time point b to the time point f in FIG.

  First, in order to stop the image forming operation, the ink jet printer 3 sends a signal indicating completion of the application of the processing liquid to the pre-coating device 2, and starts decelerating the paper conveyance speed. At this time, the control means 38 controls the operation of the transport roller 24 and the dancer roller 30 so that the dancer roller 30 moves up so that the control position of the dancer roller 30 changes from the control line A to the position B (ST01, FIG. 3). Time point b to period c).

  When the image forming operation is completed and the operations of the transport roller 24 and the dancer roller 30 are stopped (ST02), the pre-coating device 2 waits for a specified time (ST03). This waiting time is set to a time that does not cause thermal contraction of the paper 7 due to the residual heat of the heat roller 23a, and this time varies depending on the type of paper 7 to be used, the paper thickness, and the paper width. An optimal standby time data table corresponding to such information is prepared in advance, and optimal control can be realized for each paper by selecting and controlling the standby time for the paper 7 to be used. .

  After waiting for a specified time, the dancer roller 30 is lowered while rotating the transport roller 24 (ST04). At this time, the control means 38 operates the transport roller 24 and the dancer roller 30 so that the transport amount of the paper 7 transported by the transport roller 24 is smaller than the transport amount of the paper 7 transported as the dancer roller 30 is lowered. To control. As a result, the dancer roller 30 can be lowered while maintaining a stable state in which tension is applied to the sheet 7. Then, after the dancer roller 30 is lowered by a predetermined amount, the operations of the transport roller 24 and the dancer roller 30 are stopped.

Next, the surface temperature of the heat roller 23a is confirmed. If the surface temperature of the heat roller 23a has not decreased to room temperature, the process returns to step ST03, and the dancer roller 30 is lowered by a predetermined amount after waiting for a specified time. The amount of lowering of the dancer roller 30 in step ST04 is such that the dancer roller 30 is lowered from the position B to the position C during a period (period e in FIG. 3) from when the surface temperature of the heat roller 23a is lowered to the normal temperature from the end of image formation. The amount of descending when controlled in this way. Specifically, it can be obtained by the following equation.
Descent amount of dancer roller 30 at step ST04 = Descent amount of dancer roller 30 from position B to position C / number of descents α
The number of times of descending α = the time required for the surface temperature of the heat roller 23a to cool to room temperature / the standby time in step ST03.

  Since the speed at which the surface temperature of the heat roller 23a is lowered is substantially constant according to the configuration of the pre-coating device 2, the time required for cooling to room temperature is determined by the control temperature during image formation. A number obtained by dividing the time from the position B to the position C of the dancer roller 30 by the number of descending times α obtained by dividing this time by the standby time in step ST03 is the one time descending amount in step ST04. When the surface temperature of the heat roller 23a decreases to room temperature, the pre-coating device 2 enters a normal standby state. At this time, the dancer roller 30 occupies the position C (time point f in FIG. 3).

  With the above-described configuration, it is possible to suppress the occurrence of thermal contraction on the sheet 7 after the end of image formation by shifting the contact position between the high-temperature heat roller 23a and the sheet 7 without increasing the cost due to the existing configuration. The paper 7 can be conveyed in a stable state.

  FIG. 5 is a flowchart illustrating a control method at the start of image formation according to an embodiment of the present invention. This flowchart is the operation control of the transport roller 24 and the dancer roller 30 by the control means 38 during the period from the time point h to the time point j in FIG.

  In order to start image formation, the ink jet printer 3 sends a signal informing the start coating device 2 of the start of image formation preparation. Upon receiving the signal, the pre-coating device 2 starts heating the heat roller 23a until it reaches the control temperature during image formation (ST11).

  When heating of the heat roller 23a is started, the pre-coating device 2 stands by for a specified time (ST12). This waiting time is set to a time that does not cause thermal contraction of the paper 7 due to the residual heat of the heat roller 23a, and this time varies depending on the type of paper 7 to be used, the paper thickness, and the paper width. An optimal standby time data table corresponding to such information is prepared in advance, and optimal control can be realized for each paper by selecting and controlling the standby time for the paper 7 to be used. .

  After waiting for a specified time, the dancer roller 30 is lowered while rotating the transport roller 24 (ST13). At this time, the control means 38 operates the transport roller 24 and the dancer roller 30 so that the transport amount of the paper 7 transported by the transport roller 24 is smaller than the transport amount of the paper 7 transported as the dancer roller 30 is lowered. To control. As a result, the dancer roller 30 can be lowered while maintaining a stable state in which tension is applied to the sheet 7. Then, after the dancer roller 30 is lowered by a predetermined amount, the operations of the transport roller 24 and the dancer roller 30 are stopped.

Next, the surface temperature of the heat roller 23a is confirmed. If the surface temperature of the heat roller 23a has not decreased to room temperature, the process returns to step ST12, and the dancer roller 30 is lowered by a predetermined amount after waiting for a specified time. In step ST13, the amount of lowering of the dancer roller 30 is such that the dancer roller 30 is lowered from the position C to the control line A during the period from the end of image formation to the normal temperature (period i in FIG. 3). The amount of descending to be. Specifically, it can be obtained by the following equation.
Descent amount of dancer roller 30 at step ST13 = Descent amount from position C of dancer roller 30 to control line A / Descent number β
Number of descending times β = time required for the surface temperature of the heat roller 23a to be heated to the control temperature at the time of image formation / standby time in step ST12.

  The time required for the surface temperature of the heat roller 23a to rise from the normal temperature to the control temperature during image formation is determined by the control temperature during image formation. A number obtained by dividing the time from the position C of the dancer roller 30 to the control line A by the number of descending times β obtained by dividing this time by the waiting time in step ST12 is the amount of one descending in step ST13. When the surface temperature of the heat roller 23a rises to the control temperature at the time of image formation and becomes ready for image formation, the pre-coating device 2 notifies the inkjet printer 3 that image formation preparation is complete. At this time, the dancer roller 30 occupies the control line A. The inkjet printer 3 waits for the completion of image formation preparation of the pre-coating device 2, sends a paper conveyance start signal and paper conveyance speed data, and starts image formation (time point j in FIG. 3).

  With the above-described configuration, it is possible to suppress the occurrence of thermal contraction on the sheet 7 during the image formation preparation period by shifting the contact position between the high-temperature heat roller 23a and the sheet 7 without increasing the cost due to the existing configuration. The paper 7 can be conveyed in a stable state. Further, when the dancer roller 30 is lowered, the dancer roller 30 occupies the control line A and is in a state where tension is applied to the paper 7. Therefore, the paper can be stably conveyed during the next image formation.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments described above, and is described in the claims unless specifically limited by the above description. Various modifications and changes can be made within the scope of the present invention.
The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention. .

2 Pretreatment device 7 Recording medium (paper)
16 Buffer means 17 First application means 20 Second application means 23a Heating means (heat roller)
24 Conveying means (conveying roller)
31 Vertical movement means 38 Control means A Specified position (control line)

JP 2012-136313 A

Claims (4)

Application means for applying a pretreatment liquid to a long recording medium;
A plurality of heating means for heating the recording medium at a predetermined temperature;
Conveying means for conveying the recording medium;
Buffer means that can be moved up and down by vertical movement means, and stores the recording medium for a predetermined length while applying tension to the recording medium conveyed by the conveying means;
Control means for controlling the operation of the conveying means and the vertical movement means,
The control means is configured such that the buffer means rises above a predetermined position occupied during conveyance of the recording medium during the recording medium conveyance speed reduction when the conveyance of the recording medium is stopped when the conveyance of the recording medium is stopped. And controlling the operation of the conveying means and the vertical movement means to lower the buffer means for a predetermined period until the recording medium is no longer affected by heating of the heating means after the conveyance of the recording medium is stopped. Therefore, a pre-processing apparatus for controlling the operation of the conveying means and the vertical movement means to convey the recording medium in the range of the predetermined length and shifting the contact position between the heating means and the recording medium. The pretreatment device according to claim 1,
Before the heating unit is heated to the predetermined temperature prior to starting conveyance along with recording of the recording medium, the control unit operates the conveyance unit and the vertical movement unit to lower the buffer unit. A pre-processing apparatus that controls and conveys the recording medium in a range of the predetermined length and shifts a contact position between the heating unit and the recording medium. The pretreatment device according to claim 1 or 2,
When lowering the buffer means, the control means causes the transport amount of the recording medium transported by the transport means to be smaller than the transport amount of the recording medium transported as the buffer means descends. A preprocessing apparatus for controlling operations of a conveying means and the vertical movement means. The pretreatment device according to any one of claims 1 to 3,
The preprocessing apparatus according to claim 1, wherein when the buffer means is lowered, the control means controls the operation of the transport means and the vertical movement means so that the buffer means occupies the specified position at a lower limit position.

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