JP2015101029A - Treatment agent liquid-applying device for ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment agent liquid-applying device that prevents slack in a recorded medium in deceleration printing, while preventing both slack in the recorded medium and wear of an application roller during constant-speed printing.SOLUTION: A treatment agent liquid-applying device comprises: a switching circuit 76 that sets a first command speed for giving a command such that a command speed for an application roller is (99%) of a transport detection speed and a second command speed for giving a command such that it is at a speed ratio (80%), which is slower than the first command speed, the circuit 76 being switchable between the first and second command speeds; and a counter 71 and comparison circuit 74 for detecting a change in paper sheet transport speed in a printer. For constant-speed printing, the application roller is rotated and driven at the first command speed. When deceleration of paper sheet transport speed in the printer is detected, the command speed for the application speed is switched from the first command speed to the second command speed, and deceleration printing is carried out.

Description

  The present invention relates to an ink jet printer that applies a treatment agent solution such as a blur suppressor for suppressing image bleeding of an ink jet printer that discharges ink droplets to form an image on a recording medium before the image formation. The present invention relates to a processing agent solution coating apparatus (hereinafter sometimes abbreviated as a processing agent solution application device).

  Inkjet image formation has rapidly gained popularity in recent years because it has the advantage of being easy to color in addition to low noise and low running costs. However, when an image is formed on a recording medium other than dedicated paper (hereinafter sometimes abbreviated as paper), in addition to initial quality problems such as bleeding, density, color tone and show-through, water resistance, weather resistance, etc. Since there are problems related to image robustness, proposals have been made to solve these problems.

  For example, a printing system using web-like paper such as roll paper is mainly composed of a main body printing device, a processing agent liquid application device for applying a processing agent liquid to the surface of the paper in the preceding process, and an unwinder and rewinder. It is configured. The processing agent solution coating apparatus has a role of applying the processing agent solution to the web-like paper drawn from the unwinder, drying it, and feeding it to the printing device downstream in the paper transport direction.

  An application roller for applying the processing agent liquid is disposed on the upstream side in the sheet conveying direction inside the processing agent solution applying apparatus, and the sheet coated with the processing agent liquid on the downstream side in the sheet conveying direction is sent to the printing apparatus. A conveyance roller is disposed, and a driving means by a motor is provided for each of the application roller and the conveyance roller.

  In such an apparatus that transports a sheet by interlocking a plurality of rollers, a technique for detecting the transport amount by the upstream roller and correcting the upstream roller speed is already known.

  However, in the conventional conveyance means, there is no buffer mechanism that absorbs the difference in conveyance amount between the upstream roller (application roller) and the downstream roller (conveyance roller), and between the application roller such as plain paper and the sheet. When handling paper that does not slip, if the application roller speed> conveyance roller speed, the paper loosens and a conveyance failure occurs. As a result, problems such as paper breakage due to paper wrinkling and meandering, and uneven application of the treatment liquid are caused.

  Therefore, by detecting the conveyance roller speed and controlling the application roller speed so that the application roller speed is slower than the conveyance roller speed by a certain ratio, the paper is prevented from loosening during constant speed printing. Is possible.

  However, the slower the application roller speed, the larger the speed difference between the application roller and the paper, and the more the wear of the application roller increases, so the paper will not loosen during constant speed printing and the application roller will wear out. In order to achieve both of this, it is desirable to control the application roller speed to operate at 98% to 100% of the conveyance roller speed.

In addition to the mode for printing at a constant speed, the print mode includes a mode for performing accelerated printing or reduced printing.
Since the application roller command speed is created based on the detected value of the transport roller speed, the transport roller speed is delayed from the command speed, that is, the transport roller speed by the response time of the motor. Therefore, at the time of decelerating printing, the conveyance roller speed becomes smaller than the application roller speed, and the paper becomes slack.

  In other words, with the conventional control, there is a problem that the application roller cannot be controlled so that the paper does not loosen during slow printing, while the paper does not loosen during constant speed printing and the application roller does not wear. there were.

  Japanese Patent Laid-Open No. 2013-91262 (Patent Document 1) discloses that a processing agent solution coating apparatus for an ink jet printer uses a printing roller for the conveyance roller and the coating roller at each of acceleration, constant speed, and deceleration. The command speed is determined. Further, the command speed of the application roller is set to 90% to 95% of the command speed of the transport roller.

  However, there is a problem that wear of the application roller occurs due to the difference in speed between the application roller and the paper, and therefore the life of the application roller is short.

  The object of the present invention is to solve such problems of the prior art and to ensure that the recording medium does not sag during constant speed printing and that the coating roller does not wear, and that the recording medium can be used during slow printing. An object of the present invention is to provide a treatment liquid coating apparatus for an inkjet printer that does not sag.

In order to achieve the above object, the present invention provides a conveying means such as a conveying roller for conveying a long recording medium before image formation in a predetermined direction;
An application roller for applying a treatment liquid to the recording medium conveyed by the conveying means;
The present invention is intended for a processing agent liquid coating apparatus for an ink jet printer that includes a driving source for a coating roller such as a coating motor that rotationally drives the coating roller.

And, for example, a coating roller speed detecting means such as a coating encoder for detecting the speed of the coating roller;
A transport speed detecting means such as a transport encoder for detecting a recording medium transport speed by the transport means;
A first command speed commanding the command speed of the coating roller with respect to the transport speed detected by the transport speed detecting means (for example, 99% of the transport speed) and a speed ratio (slower than the first command speed) For example, the second command speed commanded at 80% of the transport speed) is set to be switchable, for example, a coating roller command speed output means such as a switching circuit described later,
A conveyance speed change detecting means comprising, for example, a counter and a comparison circuit, which will be described later, for detecting a change in the conveyance speed of the recording medium in an ink jet printer connected to the downstream side in the recording medium conveyance direction of the processing agent liquid coating apparatus. With
During constant speed printing or accelerated printing, the application roller is rotationally driven at a first command speed from the application roller command speed output means,
When the deceleration of the recording medium conveyance speed in the ink jet printer is detected by the conveyance speed change detection means, the command speed from the coating roller command speed output means is switched from the first command speed to the second command speed. Thus, it is characterized in that it is configured to perform decelerated printing.

  The present invention is configured as described above, and is compatible with an ink jet printer in which the recording medium does not loosen during constant speed printing and the application roller does not wear, and the recording medium does not loosen during slow printing. A treatment liquid coating apparatus can be provided.

It is a schematic block diagram of the processing agent liquid coating device which concerns on embodiment of this invention. It is a figure explaining the relationship between the speed of the application motor of various paper, the speed of an application roller, the slack of paper, and the wear of an application roller. It is a block diagram which shows the structure and flow of control of the speed control circuit of a coating roller and a conveyance roller. It is a timing chart explaining speed control operation of an application roller and a conveyance roller. FIG. 6 is a diagram illustrating an example in which slack occurs on a sheet during slow printing and an example in which slack does not occur on a sheet. It is a figure explaining the timing which detects a deceleration state. It is a figure explaining the control circuit which detects the deceleration operation | movement of an inkjet printer, and switches an application speed setting value, and its operation | movement.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a treatment liquid coating apparatus according to an embodiment of the present invention.

  The treatment liquid coating apparatus 1 is used in a series of printing systems that handle web-like paper 6 such as an ink jet printer (not shown). An infeed unit 2, a coating unit 3, an outfeed unit 4, and a dancer roller unit 5 are provided in the processing agent solution coating apparatus 1 along the conveyance direction of the paper 6.

  The sheet 6 fed from an upstream unwinder (not shown) or the like is conveyed in the direction of the arrow by an infeed roller 2R driven by an infeed motor 2M in the infeed unit 2.

  In the infeed motor 2M, the height of the sheet 6 is detected by the sensor 2S so that the height of the sheet 6 falls within the target position A, and the number of rotations of the infeed motor 2M is increased or decreased according to the detection result. The transport speed is controlled.

  Next, the treatment liquid 3 </ b> A is applied to the paper 6 by the application roller 3 </ b> R in the application unit 3, and then sent to the outfeed unit 4.

  The sheet 6 fed to the outfeed unit 4 is conveyed by a conveyance roller 4R driven by a conveyance motor 4M, and is downstream of an inkjet printer (not shown) through a dancer roller 5R having a loop-shaped path in the dancer roller unit 5. )).

  The dancer roller 5R absorbs a difference in the transport amount of the paper 6 generated between the processing agent liquid coating apparatus 1 and the inkjet printer on the downstream side thereof by changing the height by an elevating unit 5B configured by a belt mechanism. ing. The height of the dancer roller 5R is detected by the dancer roller encoder 5E, and the conveyance speed of the paper 6 is controlled by increasing / decreasing the number of rotations of the conveyance motor 4M so that the dancer roller 5R is within the target position.

  FIG. 2 is a diagram for explaining the relationship among the speed of the application motor 3M for various papers, the speed of the application roller 3R, the slackness of the paper 6, and the wear of the application roller 3R. FIG. 4A is a schematic diagram showing a drive system for the application roller 3R. FIG. 4B shows the application motor speed (speed of the conveyance roller), the application roller speed (speed of the conveyance roller), and the conditions under which the paper 6 does not loosen when plain paper is used as the paper 6. FIG. FIG. 6C shows the coating motor speed (vs. conveying roller speed), the applying roller speed (vs. conveying roller speed), the condition that the applying roller 3R is not worn, and the applying roller when coated paper is used as the paper 6. It is the figure which showed the amount of wear of 3R collectively.

  As shown in FIG. 4A, the drive system of the application roller 3R is composed of an application motor 3M, an application roller 3R, and a one-way clutch 3C that connects the application motor 3M and the application roller 3R. A transport roller 4R is disposed on the downstream side of the coating roller 3R in the paper transport direction.

  When the application roller 3R is driven by the paper 6 like plain paper, the one-way clutch 3C works even if the application motor 3M is driven at a speed slower than the speed of the transport roller 4R. It operates at the same speed as the (conveying roller 4R). However, when the speed of the coating motor 3M is faster than the speed of the transport roller 4R, the paper 6 is driven by the coating roller 3R, and the coating roller 3R feeds the paper 6 more than the transport roller 4R. The slack of the paper 6 occurs between the rollers 4R.

  That is, in order to prevent slack from occurring in the paper 6 which is a problem when using plain paper, the speed of the coating motor 3M needs to be 100% or less with respect to the speed of the transport roller 4R (same as above). (Refer figure (b)).

  When the application roller 3R does not follow the paper 6 as in coated paper, that is, when slipping occurs, the speed of the application roller 3R is equal to the speed of the application motor 3M, and the speed of the application roller 3R is greater than the speed of the transport roller 4R. However, the slack of the paper 6 does not occur.

  On the other hand, since a speed difference occurs between the application roller 3R and the paper 6, the wear amount of the application roller 3R increases as the speed difference increases. In order for the application roller 3R not to be worn, the speed of the application motor 3M needs to be 98% or more (˜100%) with respect to the speed of the transport roller 4R (see FIG. 10C).

  In other words, the speed of the coating motor 3M is set to satisfy both the condition that the paper does not sag when using plain paper during constant speed printing and the condition that the transport roller does not wear when using coated paper. It is necessary to control to be 98% to 100% with respect to the speed of the transport roller 4R.

  As described above, the command speed of the coating motor 3M during constant speed printing or accelerated printing may be set to approximately 99% (99% in this embodiment) with respect to the speed of the transport roller 4R.

  FIG. 3 is a block diagram showing the configuration and control flow of the speed control circuit for the application roller 3R and the transport roller 4R.

  As shown in the figure, paper feed pulses 70 are sequentially output according to the paper transport amount of the ink jet printer 7, input to the arithmetic circuit 40, and converted into a transport speed command value 41. The transport speed command value 41 is a numerical value converted according to the cycle of the paper feed pulse 70, converted into a transport command voltage 43 by the D / A converter 42, and input to the transport motor 4M.

  The conveyance motor 4M is a DC brushless motor composed of a driver and a motor, and can increase or decrease the motor rotation speed according to the input voltage. When the driving force of the transport motor 4M is transmitted to the transport roller 4R, a transport encoder pulse 44 is output from the transport encoder ENC4E attached to the transport motor 4M according to the number of rotations of the transport roller 4R and is input to the arithmetic circuit 30. Is done.

  The arithmetic circuit 30 can output a coating speed command value 31 converted according to the cycle of the transport encoder pulse 44 by multiplying the transport encoder pulse 44 by the coating speed set value (%) 36. The coating speed command value 31 is converted into a coating command voltage 33 by the D / A converter 32 and input to the coating motor 3M.

  The coating motor 3M is also a DC brushless motor composed of a driver and a motor, similar to the transport motor 4M, and can increase or decrease the motor rotation speed according to the input voltage. When the driving force of the application motor 3M is transmitted to the application roller 3R via the one-way clutch 3C, an application encoder pulse 34 is output from the application encoder ENC3E according to the rotation speed of the application roller 3R. The coating encoder pulse 34 calculates a coating speed detection value 37 and a coating transport amount detection value 38 by the detection circuit 35, and both detection values 37 and 38 are input to the arithmetic circuit 30 and are feedback-controlled with respect to the coating speed command value 31. It is the composition which performs.

  In this embodiment, the printing (printer) speed is 120 mpm, the diameter of the application roller 3R and the conveying roller 4R is 95.49 mm, the reduction ratio is 5, and the motor voltage / rotation speed characteristic is rotation speed = voltage × 1000, D / A. Conversion characteristics: voltage = input value / 1000, paper feed pulse cycle is 1/6 inch, encoder resolution is 1000 pulses / rotation, transport speed command value = 424000 / paper feed pulse cycle (count value), coating speed command value = 3000000 / conveyance encoder pulse cycle (count value) × application speed setting value (%), application speed detection value = 3000000 / application encoder pulse period (count value).

FIG. 4 is a timing chart for explaining the speed control operation of the application roller 3R and the transport roller 4R.
The paper transport of the inkjet printer 7 is 120 m / min, and when the paper feed pulse 70 is output in units of 1/6 inch, the cycle of the paper feed pulse 70 is 2.12 msec.

  As shown in FIG. 3, the arithmetic circuit 40 converts the measurement result of the pulse period of the paper feed pulse 70 into a conveyance speed command value 41. The conversion constants are the diameter of the conveyance roller 4R, the reduction ratio, the motor of the conveyance motor 4M. It is determined from the characteristics and D / A converter characteristics.

  When the diameter of the transport roller 4R is 95.49 mm (circumferential length 300 mm) and the peripheral speed of the transport roller 4R is 120 m / min, the rotation speed of the transport roller 4R is 120,000 / 300 = 400 rpm, and the reduction ratio = 5. In some cases, the rotation speed of the transport motor 4M is 400 × 5 = 2000 rpm.

  When the voltage-rotational speed characteristic of the transport motor 4M is 1000 rpm / 1V, the transport command voltage 43 is 2V. When the conversion characteristic of the D / A converter 42 is 1 V / 1000 (digit), the conveyance speed command value 41 is 2000 (digit).

When counting the pulse period of the paper feed pulse 70 with a clock of 100 kHz, the period 2.12 ms is converted to a count value = 212. Since the pulse period of the paper feed pulse 70 and the conveyance speed command value 41 are in an inversely proportional relationship, the conversion constant when converting the cycle count value = 212 to the conveyance speed command value 41 = 2000 is 212 × 2000 = 424000. In this way, the transport roller 4R can be rotationally driven at the same speed as the ink jet printer 7.
When the diameter of the coating roller 3R, the reduction ratio, the characteristics of the coating motor 3M, and the D / A converter 32 are the same as those in the transport unit, if the coating speed command value 31 is 2000, the peripheral speed of the coating roller 3R is transported. Similar to the roller 4R, the speed is 120 m / min.

  The coating speed command value 31 is converted from the cycle of the transport encoder 4E. When the resolution of the transport encoder 4E is 1000 pulses / 1 rotation, the cycle of the transport encoder pulse 44 is 1 / (1000 × 400 rpm / 60) = 0.15 ms, and the cycle of the transport encoder pulse 44 is counted by a 10 MHz clock. In this case, the period of 0.15 ms is converted to count value = 1500.

  Similarly, since the cycle of the transport encoder pulse 44 and the application speed command value 31 are also inversely proportional, the conversion constant when converting the cycle count value = 1500 to the application speed command value 31 = 2000 is 1500 × 2000 = 3000000.

  The value converted to the application speed command value 31 = 2000 is a value when the application speed setting value 36 is 100%, and the application speed command value 31 when the application speed setting value 36 is set to 99% is: 2000 × 0.99 = 1980.

  When the coating encoder 3E has the same resolution as the transport encoder 4E = 1000 pulses / 1 rotation, the cycle of the transport encoder pulse 44 is 1 / (1000 × 400 rpm × 0.99 / 60) = 0.1515 ms, and a 10 MHz clock In the case of counting at, the period of 0.1515 ms is converted to count value = 1515. The conversion constant when the detection circuit 35 converts the cycle into the coating speed detection value 37 is 3000000/1515 = 1980, which matches the command speed.

  When the peripheral speed of the application roller 3R is faster than the command speed, the application speed detection value 37 is larger than the application speed command value 31. Therefore, if the difference is fed back and subtracted from the application speed command value 31, the command speed Can be approached.

  On the other hand, when the peripheral speed of the application roller 3R is slower than the command speed, the difference between the application speed detection value 37 and the application speed command value 31 can be fed back to the application speed command value 31 and added to approximate the command speed. .

  The application speed detection value 37 is a value obtained by detecting the difference between the number of pulses of the transport encoder pulse 44 and the number of pulses of the application encoder pulse 34. If the number of pulses of the coating encoder pulse 34 is larger, it is fed back to the coating speed command value 31 and subtracted. If the number of pulses of the coating encoder pulse 34 is smaller, it is fed back to the coating speed command value 31 and added. By doing so, it is possible to cancel the steady deviation generated between the command speed and the detected speed.

  FIG. 5 is a diagram for explaining an example in which a slack occurs in the paper during deceleration and an example in which no slack occurs in the paper. The figure (a) shows the operation when the application motor speed is reduced to 99%, which is the same as the constant speed printing, and the figure (b) shows the operation when the application motor speed is reduced to 80%. Is shown.

  In both figures, the thin solid line represents the speed of the transport roller 4R, the thick dotted line represents the speed of the coating roller 3R, the thick solid line represents the coating roller command speed, and the thin dotted line represents the speed of the coating motor 3M.

  As shown in FIG. 6A, when performing decelerating printing with the application speed setting value 36 set to 99% of the speed of the transport roller 4R, the speed of the transport roller 4R is increased from 100% to 20 during 1.6 sec. %, The time (= t) until the speed of the conveying roller 4R decreases from 100% to 99% is 1 × 1.6 / 80 = 0.02 sec.

  On the other hand, when the response time (= Δt) of the coating motor 3M is 0.1 sec, that is, when t <Δt, the speed of the coating motor 3M during deceleration becomes faster than the speed of the transport roller 4R ( The speed of the coating motor 3M> the speed of the transport roller 4R), and the paper is slack.

  On the other hand, as shown in FIG. 7B, when the application speed set value 36 is switched to 80% of the speed of the transport roller 4R and the decelerated printing is performed, the speed of the transport roller 4R is set to 100 during 1.6 sec. When the speed is reduced from% to 20%, the time (= t) until the speed of the conveying roller 4R decreases from 100% to 80% is 20 × 1.6 / 80 = 0.4 sec.

  On the other hand, when the response time (= Δt) of the coating motor 3M is 0.1 sec, that is, when t> Δt, the speed of the coating motor 3M during deceleration does not become higher than the speed of the transport roller 4R ( 3M ≦ 4R), there is no slack in the paper.

That is, during constant speed printing, the speed of the application roller 3R needs to be 99% of the speed of the transport roller 4R.
Since sheet slack occurs, it is necessary to switch the application speed setting value 36 to a slower speed during deceleration.

  FIG. 6 is a diagram illustrating timing for detecting a deceleration state. The thin solid line in the figure indicates the speed of the printer 7 (= command speed of the transport roller 4R), and the thick solid line indicates the speed of the transport roller 4R.

In order to switch the application speed setting value 36 during the deceleration printing, first, it is necessary to detect the deceleration state.
Point a in the figure is the timing at which the speed of the printer 7 is decelerated to an arbitrary detection value. Since the command speed of the transport roller 4R is generated from the speed of the printer 7, it operates almost simultaneously with the speed of the printer 7. Since the speed of the transport roller 4R is delayed by the response time (Δt) of the transport motor 4M, the timing at which the speed of the transport roller 4R decelerates to the same detection value is point b in the figure, and the response time of the transport motor 4M (Δt ) Only delayed.

  Similarly, since the application roller 3R decelerates behind the command speed by the response time of the application motor 3M, when the printer 7 decelerates, it is necessary to detect this as soon as possible and switch the application speed setting value 36 to a lower speed. There is. That is, it is only necessary to detect that the speed of the printer 7 has decreased and switch the application speed setting value 36.

  FIG. 7 is a diagram illustrating a control circuit that detects the deceleration operation of the printer 7 and switches the application speed setting value 36, and the operation thereof. FIG. 7A is a block diagram of the control circuit, and FIG. ) Is a timing chart illustrating a control operation.

  As described with reference to FIG. 4, when the conveyance speed of the inkjet printer 7 is 120 m / min and the paper feed pulse 70 is output in units of 1/6 inch, the cycle of the paper feed pulse 70 is 2.12 msec.

  A paper feed pulse 70 from the printer 7 is input to the counter 71. The counter 71 counts the cycle of the paper feed pulse 70 with a clock of 100 kHz. When the cycle = 2.12 msec, the pulse width data 72 is 212.

  The pulse width data 72 generated by the counter 71 is input to the comparison circuit 74. As shown in FIG. 5B, the pulse width data 72 increases as the paper transport speed of the printer 7 decreases. Therefore, the comparison circuit 74 detects that the pulse width data 72 is larger than the reference data 73. , Recognize the deceleration state.

  For example, when the detection level is 95% (= 114 m / min) of 120 m / min, the cycle of the paper feed pulse 70 at 114 m / min is 2.23 msec, so the reference data 73 set by the comparison circuit 74 is set. Is 223. When the pulse width data 72 becomes larger than the reference data 73 (223), the deceleration detection signal 75 is switched to the H level.

  The switching circuit 76 selects 99% as the application speed setting value 36 when the deceleration detection signal 75 is at the L level, and selects 80% as the application speed setting value 36 when the deceleration detection signal 75 is at the H level.

  Thus, by detecting that the paper feed speed of the printer 7 is in a decelerating state and switching the application speed setting value 36 to 80%, as shown in FIG. Since the speed can be reduced so as not to become faster, the occurrence of slack in the paper can be prevented.

  Further, when it is detected that the paper feed speed of the printer 7 has changed from deceleration to constant speed or from deceleration to acceleration, the application speed setting value 36 is switched from 80% to 99% again.

  In the embodiment, the conveyance roller is used as the recording medium conveyance unit. However, the present invention is not limited to this, and other conveyance unit such as a conveyance tractor may be used.

1: Treatment liquid application device,
3: Application unit,
3A: treatment solution,
3M: coating motor,
3R: coating roller,
3E: coating encoder,
4: Outfeed unit,
4M: Conveyance motor,
4R: conveying roller,
4E: Transfer encoder,
6: Paper,
7: Inkjet printer,
31: Application speed detection value,
33: Application command voltage
34: Application encoder pulse,
35: detection circuit,
36: Application speed setting value,
37: Application speed detection value,
38: Application conveyance amount detection value,
40: arithmetic circuit,
41: Transport speed command value,
43: Transport command voltage,
44: transport encoder pulse,
70: Paper feed pulse,
71: counter,
72: Pulse width data,
73: Reference data,
74: Comparison circuit,
75: Deceleration detection signal,
76: A switching circuit.

JP 2013-91262 A

Claims (3)

Conveying means for conveying the long recording medium before image formation in a predetermined direction;
An application roller for applying a treatment liquid to the recording medium conveyed by the conveying means;
In a processing agent liquid coating apparatus for an ink jet printer provided with a driving source for a coating roller that rotationally drives the coating roller,
Application roller speed detection means for detecting the speed of the application roller;
A transport speed detecting means for detecting a recording medium transport speed by the transport means;
A first command speed for commanding the command speed of the coating roller with respect to the transport speed detected by the transport speed detecting means, and a second command speed for commanding at a speed ratio slower than the first command speed, Application roller command speed output means set to be switchable,
A conveyance speed change detecting means for detecting a change in the conveyance speed of the recording medium in the inkjet printer connected to the downstream side in the recording medium conveyance direction of the treatment liquid coating apparatus;
During constant speed printing or accelerated printing, the application roller is rotationally driven at a first command speed from the application roller command speed output means,
When the deceleration of the recording medium conveyance speed in the ink jet printer is detected by the conveyance speed change detection means, the command speed from the coating roller command speed output means is switched from the first command speed to the second command speed. A processing agent solution coating apparatus for an ink jet printer, characterized in that it is configured to perform reduced speed printing. The processing agent solution coating apparatus for an ink jet printer according to claim 1,
When the conveyance speed change detecting means detects that the printing mode of the ink jet printer has changed from decelerated printing to constant speed printing or accelerated printing, the command speed from the application roller command speed output means is determined from the second command speed. A processing liquid coating apparatus for an ink jet printer, which is configured to perform constant speed printing or accelerated printing by switching to the first command speed. In the processing agent liquid coating device for an inkjet printer according to claim 1 or 2,
A processing agent solution coating apparatus for an ink jet printer, wherein the speed of the coating roller is restricted within a range of 98% to 100% of the speed of the conveying means during the constant speed printing.