JP2020049772A - Printer - Google Patents

Abstract

To provide a printer which prevents a printing medium from contacting with an inkjet head by deformation of the printing medium caused by a temperature difference between the outside of a device housing and the inside of the device housing.SOLUTION: A printer includes: print parts 22A, 22B which perform print processing to a printing medium W in a non-contact manner; a clearance change mechanism which changes a clearance between the printing medium W and the print parts 22A, 22B; a first temperature 25 which detects a temperature in the device housing; and a print control part 24 which controls the clearance change mechanism to change a clearance between the printing medium W and the print parts 22A, 22B based on a difference between temperature information detected by the first temperature sensor 25 and temperature information of the outside of the device housing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a printing apparatus that performs a printing process on a print medium in a non-contact manner.

  2. Description of the Related Art Conventionally, there has been proposed a printing apparatus that performs a printing process on a print medium formed of a long paper or a film while transporting the print medium by a roller.

  As such a printing apparatus, for example, an ink jet printing apparatus having an ink jet head for discharging ink onto a print medium has been proposed. In this inkjet printing apparatus, a roll in which a print medium of several meters to several kilometers is wound in a roll shape is installed in a sending unit, and the print medium sent from the roll is conveyed by a roller or the like and is transported under an inkjet head. Is passed through to perform printing. Then, after printing, it is configured to be wound in a roll shape at a winding section on the downstream side.

JP 2012-218349 A JP 2017-30167 A

  Here, when the printing process is performed by the above-described inkjet printing apparatus, the print medium may be deformed due to a temperature difference between the inside of the apparatus housing and the outside of the apparatus housing. The environment where the roll is placed is a room temperature environment outside the apparatus housing, and the temperature of the print medium of the roll is equal to room temperature.

  On the other hand, the inside of the device housing is heated by heat radiation from the inkjet head and the control unit by performing, for example, continuous printing, and a certain amount of heat is discharged by an exhaust fan provided in the housing. And the temperature is maintained in an elevated state, which causes a temperature difference inside and outside the apparatus.

  In a situation where the temperature difference is present, dew condensation occurs on the low-temperature print medium by transferring the print medium from the outside of the low-temperature apparatus housing into the high-temperature, long transport path length apparatus housing. In particular, the fibers absorb moisture from the cut end face (the end face along the length direction of the print medium sent out from the roll), and undulation occurs on the end face. The print medium may come into contact with the inkjet head due to the undulation (deformation) of the print medium. When the print medium comes into contact with the ink jet head, there is a possibility that the ink adheres to the print medium and becomes dirty, or the ink jet head is damaged.

  Patent Document 1 proposes providing a plurality of paper pressing guide rollers formed in a size corresponding to the paper suction force of a transport belt in order to avoid contact of a print medium with an inkjet head.

  However, in the method of Patent Document 1, since the printing medium immediately after printing is pressed by the guide roller, the ink that has not been completely dried adheres to the guide roller, or the guide roller is located near the ink jet head, and the guide roller is moved by an ink mist or the like. The ink adheres to. Then, the ink is re-transferred from the guide roller to the print medium, which causes stain.

  Further, in Patent Document 2, it is proposed to increase the interval between the print medium and the inkjet head in order to prevent the print medium from fluttering during the period in which the print medium is accelerated and conveyed. I have.

  However, in Patent Literature 2, no consideration is given to the deformation of the print medium due to the temperature difference between the outside of the apparatus casing and the inside of the apparatus casing as described above.

  The present invention has been made in view of the above circumstances, and provides a printing apparatus that can prevent a print medium from contacting an inkjet head due to deformation of the print medium caused by a temperature difference between the outside of the apparatus housing and the inside of the apparatus housing. It is the purpose.

  The printing apparatus of the present invention includes a printing unit that performs a printing process on a print medium in a non-contact manner, an interval changing mechanism that changes an interval between the print medium and the printing unit, and a temperature detection unit that detects a temperature in the apparatus housing. And a control unit that controls an interval changing mechanism to change the interval between the print medium and the printing unit based on a difference between the temperature information detected by the temperature detection unit and the temperature information outside the apparatus housing.

  According to the printing apparatus of the present invention, the printing apparatus includes an interval changing mechanism that changes an interval between the print medium and the printing unit, and a temperature detection unit that detects a temperature in the apparatus housing, and includes temperature information detected by the temperature detection unit. Since the interval changing mechanism is controlled to change the interval between the print medium and the printing unit based on the difference between the temperature information outside the device housing and the temperature information, printing caused by the temperature difference between the outside of the device housing and the inside of the device housing is performed. The deformation of the medium can prevent the print medium from contacting the inkjet head.

FIG. 1 is a diagram illustrating a schematic configuration of an inkjet printing apparatus using one embodiment of a printing apparatus of the present invention. View from above of head unit FIG. 2 is a view of the head unit shown in FIG. FIG. 2 is a block diagram showing a configuration of a control system of the inkjet printing apparatus shown in FIG. The figure which shows an example of a control table Flow chart for explaining the printing operation of the inkjet printing apparatus shown in FIG. FIG. 4 is a diagram illustrating an example of a relationship between a print medium conveyance speed and a head gap change timing based on temperature difference information.

  Hereinafter, an inkjet printing apparatus using an embodiment of the printing apparatus of the present invention will be described in detail with reference to the drawings. The ink jet printing apparatus according to the present embodiment is configured to be capable of performing printing on a long print medium, and is characterized by adjusting the interval between the head unit and the print medium according to the temperature inside the apparatus housing. First, a schematic configuration of the entire inkjet printing apparatus will be described. FIG. 1 is a schematic configuration diagram of an inkjet printing apparatus 1 of the present embodiment. Note that the vertical and horizontal directions indicated by arrows in FIG. 1 are the vertical and horizontal directions in the inkjet printing apparatus 1 of the present embodiment, the direction orthogonal to the paper surface of FIG. 1 is the front-rear direction, and the front surface direction of the paper surface is the front direction.

  As shown in FIG. 1, the inkjet printing apparatus 1 of the present embodiment includes a sending unit 2, a printing apparatus main body 3, and a winding unit 4. In the following description, “upstream” and “downstream” mean upstream and downstream in the transport direction of the print medium W transported from the sending unit 2 to the winding unit 4.

  The sending unit 2 sends out the print medium W from a roll 10 in which a long print medium W made of a film, paper, or the like is wound in a roll shape. The delivery unit 2 includes a roll support shaft 11 that rotatably supports the roll 10, a brake 12 (see FIG. 4) that applies a brake to the roll support shaft 11, and a delivery control unit 13 that controls the delivery unit 2. Have.

  The brake 12 applies a brake to the roll support shaft 11. By the brake by the brake 12, tension is applied to the print medium W between the roll 10 and a transport roller 43 of the printing apparatus main body 3 described later.

  The delivery control unit 13 controls the brake 12 based on a preset tension set value. By this brake control, a tension corresponding to the tension set value is generated on the print medium W. The transmission control unit 13 includes a CPU (Central Processing Unit), a semiconductor memory, a hard disk, and the like.

  The printing apparatus main unit 3 performs a printing process on the print medium W while transporting the print medium W sent from the sending unit 2. The printing apparatus main unit 3 includes a transport unit 21, printing units 22A and 22B, an operation panel 23, a print control unit 24, a first temperature sensor 25, and a second temperature sensor 26.

  The transport unit 21 transports the print medium W sent from the sending unit 2. The transport section 21 includes guide rollers 31 to 40, 20 head lower support members 41, a meandering control section 42, a pair of transport rollers 43, an encoder 44, and a transport motor 47 (see FIG. 4). ing.

  The guide rollers 31 to 40 guide the print medium W conveyed in the printing apparatus main body 3. The guide roller 31 is arranged below the left end of the printing apparatus main body 3. The guide roller 32 is disposed between the guide roller 31 and a meandering control roller 42a of a meandering control unit 42 described later.

  The guide rollers 33 to 39 guide the print medium W between the meandering control unit 42 and the transport roller 43. The guide roller 33 is disposed slightly to the left of a meandering control roller 42b of a meandering control unit 42 described later.

  The guide roller 34 is arranged above the guide roller 33. The guide roller 34 is provided with an encoder 44. The encoder 44 outputs a pulse signal corresponding to the rotation angle of the guide roller 34. The pulse signal output from the encoder 44 is output to a print control unit 24, which will be described later, and the print control unit 24 outputs the ink signals from the head units 51K, 51C, 51M, 51Y, and 51P based on the input pulse signal. Control the ejection timing.

  The guide roller 35 is arranged at the same height as the guide roller 34 and to the right of the guide roller 34. The guide roller 36 is disposed below the guide roller 35 and higher than the guide roller 33. The guide roller 37 is located to the left of the guide roller 36, near the right side of the print medium W between the guide rollers 33 and 34, and at substantially the same height as the guide roller 36. The guide roller 38 is disposed below and to the right of the guide roller 37. The guide roller 39 is disposed slightly below and to the right of the guide roller 38.

  The guide roller 40 guides the print medium W between the transport roller 43 and the winding unit 4. The guide roller 40 is arranged below the right end of the printing apparatus main body 3.

  The lower head support member 41 supports the print medium W below the head unit 51 described below between the guide rollers 34 and 35 and between the guide rollers 36 and 37. The lower head support member 41 is formed in a long shape extending in the front-rear direction. Ten head lower support members 41 are arranged between the guide rollers 34 and 35 and between the guide rollers 36 and 37, respectively.

  The meandering control unit 42 corrects the meandering of the print medium W. The meandering control unit 42 includes meandering control rollers 42a and 42b, a meandering control motor 42c (see FIG. 4) described later, and an edge sensor 42d.

  The meandering control rollers 42a and 42b are formed in a long shape extending in the front-rear direction. The meandering control rollers 42a and 42b are configured so that the angle in the axial direction with respect to the front-rear direction can be adjusted.

  The meandering control motor 42c rotates the meandering control rollers 42a, 42b about an axis parallel to the left-right direction in order to adjust the angle of the meandering control rollers 42a, 42b in the axial direction.

  The edge sensor 42d detects an edge in the width direction (front-back direction) of the print medium W. The edge sensor 42d is arranged near the downstream side of the meandering control roller 42b.

  The pair of transport rollers 43 transports the print medium W toward the winding unit 4 while nipping the print medium W. The transport roller 43 is formed in a long shape extending in the front-rear direction. The transport roller 43 is disposed between the guide rollers 39 and 40. The transport motor 47 (see FIG. 4) drives the transport roller 43 to rotate.

  The printing unit 22A prints an image of each page on the front surface of the print medium W. The printing unit 22A is disposed near the upper portion of the print medium W between the guide rollers 34 and 35. The printing unit 22A includes head units 51K, 51C, 51M, 51Y, and 51P arranged in parallel in the transport direction of the print medium W. Hereinafter, the head units 51K, 51C, 51M, 51Y, 51P, etc. may be represented by omitting the suffixes of the alphabets.

  The head units 51K, 51C, 51M, 51Y, and 51P are arranged side by side in this order from the upstream side. FIG. 2 is a view of one head unit 51 as viewed from above. Each head unit 51 includes, as shown in FIG. 2, inkjet heads 57A to 57J.

  The inkjet heads 57A to 57J have a plurality of nozzles arranged along a direction (front-back direction) orthogonal to the transport direction of the print medium W, and perform a printing process by discharging ink from the nozzles to the print medium W. . Each of the ink jet heads 57A to 57J included in each of the head units 51K, 51C, 51M, 51Y, and 51P discharges ink of black (K), cyan (C), magenta (M), yellow (Y), and a preliminary ink color, respectively. I do. Red or light cyan is used as the preliminary ink color.

  In each head unit 51, the inkjet heads 57A to 57J are arranged in a staggered manner. Specifically, as shown in FIG. 2, a first head row in which five inkjet heads 57A, 57C, 57E, 57G, and 57I are arranged in a direction (front-back direction) orthogonal to the transport direction of the print medium W. Similarly, the second head row in which the five inkjet heads 57B, 57D, 57F, 57H, and 57J are arranged in a direction (front-back direction) orthogonal to the transport direction of the print medium W is in the transport direction of the print medium W. Are provided side by side. Then, the first head row and the second head row are arranged so that there is a portion that partially overlaps between the inkjet heads 57 adjacent to each other in a direction (front-back direction) orthogonal to the transport direction of the print medium W. I have.

  In each head unit 51, a mist collection unit 52 is provided. The mist collecting unit 52 collects the ink mist IM generated in the air due to the ejection of the ink from the inkjet head 57 to the print medium W. The mist collecting unit 52 includes a fan, a motor for rotating the fan, and the like.

  FIG. 3 is a view of the head unit 51 shown in FIG. As shown in FIG. 3, the mist collecting unit 52 sucks the surrounding air by rotating the fan, and thereby absorbs the ink mist IM generated due to the ink ejection from the inkjet head 57.

  The mist collection unit 52 extends in a direction orthogonal to the transport direction of the print medium W, and is disposed near the downstream side of the inkjet head 57. Thereby, the mist collecting unit 52 can efficiently collect the ink mist IM.

  Although not shown in FIG. 1, as shown in FIG. 2, each head unit 51 is provided with an interval changing mechanism 27. The interval changing mechanism 27 includes a known actuator, and changes the interval between the head unit 51 and the print medium W by moving the head unit 51 in the vertical direction. Hereinafter, the interval between the head unit 51 and the print medium W is referred to as a head gap.

  The printing unit 22B prints the image of each page on the back surface on the back surface of the print medium W. The printing unit 22B is arranged near the upper portion of the printing medium W between the guide rollers 36 and 37. The printing unit 22B has a configuration in which the printing unit 22A is reversed left and right. This is because the transport direction of the print medium W is opposite between the guide rollers 36 and 37 printed by the printing unit 22B and between the guide rollers 34 and 35 printed by the printing unit 22A. The printing unit 22B has the same configuration as the printing unit 22A except that the printing unit 22B is reversed left and right.

  The operation panel 23 displays various screens and accepts an input operation by a user. The operation panel 23 includes a display unit having a liquid crystal display panel and the like, and an input unit having various operation keys and a touch panel.

  The first temperature sensor 25 detects the temperature inside the housing of the printing apparatus main body 3. In the present embodiment, the first temperature sensor 25 corresponds to a temperature detecting section of the present invention.

  The first temperature sensor 25 is arranged near and above the printing unit 22A. In the housing of the printing apparatus main body 3, heat sources are particularly the printing unit 22A and the printing unit 22B provided with the head unit 51, and the upper part of the printing unit 22A provided in the upper stage has the highest temperature. It is expected to be. The position of the first temperature sensor 25 is not limited to this, and may be arranged at another position in the housing of the printing apparatus main body 3. The first temperature information detected by the first temperature sensor 25 is output to the print control unit 24.

  The second temperature sensor 26 detects a temperature outside the housing of the printing apparatus main body 3. In the present embodiment, the second temperature sensor 26 is provided on the outer surface of the housing of the printing apparatus main body 3. The second temperature information detected by the second temperature sensor 26 is output to the print control unit 24. In the present embodiment, the temperature information outside the housing of the printing apparatus main body 3 is detected by the second temperature sensor 26. However, the present invention is not limited to this. For example, the user can use the operation panel 23 to Temperature information outside the housing of the printing apparatus main body 3 may be set and input.

  The print control unit 24 controls the operation of the entire inkjet printing apparatus 1. FIG. 4 is a block diagram illustrating a control system of the inkjet printing apparatus 1 according to the present embodiment. The print control unit 24 includes a CPU (Central Processing Unit), a semiconductor memory, a hard disk, and the like. The print control unit 24 controls each unit shown in FIG. 4 by executing a program stored in a storage medium such as a semiconductor memory or a hard disk in advance and operating an electric circuit. Note that, in the present embodiment, the print control unit 24 corresponds to the control unit of the present invention.

  When performing the printing process, the printing control unit 24 controls the printing units 22A and 22B to perform the printing process on the print medium W while rotating the transport roller 43 by the transport motor 47 to transport the print medium W. The printing control unit 24 counts the pulse signals output from the encoder 44 during the printing process, and controls the timing of ink ejection from the head units 51K, 51C, 51M, 51Y, and 51P based on the counted number. That is, the print control unit 24 prints an image at a desired position on the print medium W by controlling the ink ejection timing according to the transport amount of the print medium W.

  Further, the print control unit 24 of the present embodiment changes the head gap by controlling the interval changing mechanism 27 based on the difference between the input first temperature information and the second temperature information.

  Further, the print control unit 24 controls the mist collection strength of the mist collection unit 52 based on the head gap changed by the interval change mechanism 27. The print control unit 24 of the present embodiment controls the suction force by controlling the number of rotations of the fan in the mist collection unit 52, and thereby controls the mist collection strength. Specifically, the print control unit 24 performs control such that the larger the head gap, the higher the number of rotations of the fan, because the larger the head gap, the more likely the ink mist IM is generated. Accordingly, the ink mist IM can be efficiently collected, and the accumulation of the ink in the apparatus and the contamination of the print medium W by the ink mist IM can be reduced.

  Further, the print control unit 24 controls each inkjet head 57 of each head unit 51 based on the head gap changed by the interval changing mechanism 27, and changes the ink ejection timing of each inkjet head 57.

  Specifically, a control table as shown in FIG. 5 is preset in the print control unit 24 of the present embodiment. The print control unit 24 calculates the temperature difference information by calculating the difference between the input first temperature information and the input second temperature information. Then, the print control unit 24 refers to the control table shown in FIG. 5 and determines the head gap based on the calculated temperature difference information. In the control table shown in FIG. 5, when the first temperature information is T1, the second temperature information is T2, and the temperature difference information is T, only the head gap, the adjustment count, and the fan rotation speed are set. Although not shown, it is assumed that a head gap, an adjustment count number, and a fan rotation number corresponding to various types of temperature difference information are actually set.

  The relationship between the temperature difference information and the head gap may be stored in advance as a table as in the present embodiment, or a function representing the relationship between the temperature difference information and the head gap is stored in advance. You may do so.

  The head gap according to the temperature difference information is obtained, for example, by measuring the difference between the temperature inside the housing of the printing apparatus main body 3 and the temperature outside the housing, and acquiring the maximum deformation amount of the print medium W in the case of the temperature difference. Is determined by The maximum deformation amount of the print medium W may be actually measured, or may be estimated from the physical properties of the print medium W or the like.

  Further, the head gap determined after acquiring the maximum deformation amount of the print medium may be set to, for example, the maximum deformation amount + α in consideration of tension instability during acceleration / deceleration of the conveyance of the print medium W. α is an amount previously determined by experiment.

  Further, the print control unit 24 determines change information of the mist collection intensity of the mist collection unit 52 and the ink ejection timing of each inkjet head 57 based on the head gap determined based on the temperature difference information. Specifically, the print control unit 24 determines the rotation speed of the fan of the mist collection unit 52 as the mist collection intensity, and determines the adjustment count of the pulse signal of the encoder 44 as the change information of the ink ejection timing.

  The relationship between the head gap and the number of rotations of the fan and the relationship between the head gap and the adjustment count may be stored in advance as a table as in the present embodiment, or a function representing the relationship may be stored in advance. You may make it memorize.

  When the head gap is changed (expanded), the print control unit 24 subtracts the above-described adjustment count from the preset count of the pulse signal of the encoder 44 based on the print position of the image. Then, the print control unit 24 controls the ink ejection timing from each of the inkjet heads 57 based on the subtraction value, so that the ink is ejected at a timing earlier than the preset ink ejection timing. . Thus, even when the head gap is changed (expanded), an image to be printed can be printed at a desired position.

  Further, as shown in FIG. 5, the control table is set for each type of the print medium W. In the example of the control table shown in FIG. 5, the setting is made for each of thin paper, thick paper, and plain paper. When the thickness of the thin paper is th1, the thickness of the thick paper is th2, the thickness of the plain paper is th3, and the relationship between these thicknesses is th1 <th3 <th2, the head gaps D1, D2 shown in FIG. The relationship between D3 and D3 is D2 <D3 <D1. This is because the smaller the thickness of the print medium W is, the easier it is to deform. The relationship among the adjustment count numbers C1, C2, and C3 shown in FIG. 5 is C2 <C3 <C1. This is because the larger the head gap, the larger the adjustment count number, and the faster the ink ejection timing. The relationship among the fan rotation speeds F1, F2, and F3 shown in FIG. 5 is F2 <F3 <F1. This is because the larger the head gap, the more the amount of the ink mist IM tends to increase, and it is necessary to increase the rotation of the fan to increase the mist collection strength.

  In the present embodiment, the head gap according to the temperature difference information is set in advance. However, the present invention is not limited to this. For example, the print control unit 24 may determine the maximum deformation amount of the print medium W according to the temperature difference information. May be acquired, and the head gap according to the maximum deformation amount may be determined. The maximum deformation amount according to the temperature difference information may be stored in advance as a table, or a function indicating the relationship between the temperature difference information and the maximum deformation amount may be stored in advance.

  Further, the type of the print medium W is not limited to the above-described three types, and a control table corresponding to another type of print medium W such as, for example, matte paper may be set.

  Next, the winding unit 4 winds the printed print medium W. The winding unit 4 includes a winding shaft 61, a winding motor 62 (see FIG. 4) described later, and a winding control unit 63.

  The winding shaft 61 is rotated clockwise in FIG. 1 by a winding motor 62. With the rotation of the take-up shaft 61, the printed print medium W is taken up by the take-up shaft 61. The winding shaft 61 holds the printed print medium W that has been wound up as a printed roll 60.

  The winding control unit 63 controls the driving of the winding motor 62, and includes a CPU (Central Processing Unit), a semiconductor memory, a hard disk, and the like.

  Next, a printing operation of the inkjet printing apparatus 1 of the present embodiment will be described with reference to a flowchart shown in FIG. FIG. 7 is a diagram illustrating an example of the relationship between the transport speed of the print medium W and the timing of changing the head gap based on the temperature difference information.

  First, the print control unit 24 acquires the temperature difference information at the time t0 when the acceleration of the print medium W starts (S10). Specifically, the print control unit 24 of the present embodiment firstly conveys the print medium W at a predetermined acceleration and conveys the print medium W, and thus acquires the temperature difference information at the acceleration start time t0.

  Then, the print control unit 24 determines the head gap according to the input temperature difference information with reference to the control table shown in FIG. 5 (S12). Further, based on the head gap according to the temperature difference information, the print control unit 24 refers to the control table shown in FIG. 5 to determine the fan rotation speed and the adjustment count according to the head gap (S14). ).

  Then, the print control unit 24 controls the interval changing mechanism 27 to change the head gap to a head gap according to the temperature difference information, and to change the rotation speed of the fan of the mist collection unit 52 to the rotation speed according to the temperature difference information. It is set (S16).

  Next, after changing the head gap, the print control unit 24 starts driving the conveyance motor 47, and the winding control unit 63 starts driving the winding motor 62 and starts conveying the print medium W ( S18). Specifically, the print control unit 24 conveys the print medium W while accelerating at a predetermined acceleration as described above. When the print medium W is conveyed at the predetermined acceleration, the print medium W is conveyed while the tension and the like of the print medium W are not stable, so that the influence of the deformation of the print medium W due to the temperature difference between the inside and outside of the housing of the printing apparatus main body 3. However, in the present embodiment, the head gap is changed according to the temperature difference information as described above, so that a sufficient head gap can be secured against deformation of the print medium W, and the head unit The contact of the print medium W with the print medium 51 can be prevented.

  Then, when the transport speed of the print medium W reaches the transport speed V shown in FIG. 7 (time point t1), the delivery control unit 13 starts driving the brake 12. When the brake is applied to the roll support shaft 11 by the brake 12, the print medium W is transported while tension is applied to the print medium W between the roll 10 and the transport roller 43. Further, after the transport speed of the print medium W reaches the print transport speed, the print control unit 24 controls the transport motor 47 so as to maintain the print transport speed.

  Further, in the printing apparatus main body section 3, while the print medium W is being conveyed, the meandering control section 42 corrects the meandering of the print medium W. Specifically, the print control unit 24 controls the meandering control motor 42c to maintain the position of the edge in the width direction of the print medium W detected by the edge sensor 42d at a predetermined position, thereby controlling the meandering control rollers 42a, Adjust the angle of 42b.

  After the transport of the print medium W at the transport speed V is started, the print control unit 24 counts the pulse signals output from the encoder 44, and sets a count number preset according to the count number and the image printing position. The image of each page is printed at a desired position on the surface of the print medium W by controlling the timing of ink ejection from the inkjet head of each head unit 51 of the print unit 22A based on the adjustment count and the adjustment count. (S20). The print control unit 24 of the present embodiment controls the ink ejection timing in consideration of the adjustment count number as described above, so that it is possible to prevent the print position of the image from being shifted due to the change of the head gap. .

  After printing by the printing unit 22A, the print medium W is further conveyed, and the print control unit 24 determines the count number of the pulse signal of the encoder 44 and the count number and the adjustment count number set in advance in accordance with the print position of the image. Then, the image of each page is printed at a desired position on the back surface of the print medium W by controlling the timing of ink ejection from the inkjet head of each head unit 51 of the print unit 22B (S22).

  Then, the print control unit 24 continues the printing process until the printing of the images of all the pages is completed (S24, NO).

  Then, when the printing process of the images of all pages is completed (S24, YES), the print control unit 24 starts to reduce the transport speed of the print medium W as shown in FIG. Temperature difference information is obtained (S26).

  Then, the print control unit 24 refers to the control table shown in FIG. 5 again and determines a head gap according to the input temperature difference information (S28). Further, based on the head gap according to the temperature difference information, the print control unit 24 refers to the control table shown in FIG. 5 to determine the fan rotation speed and the adjustment count according to the head gap (S30). ).

  Then, the print control unit 24 controls the interval changing mechanism 27 to change the head gap to a head gap according to the temperature difference information, and to change the rotation speed of the fan of the mist collection unit 52 to the rotation speed according to the temperature difference information. It is set (S32).

  After changing the head gap, the print control unit 24 conveys the print medium W at a reduced speed at a predetermined acceleration as described above (S34). When the print medium W is conveyed while being decelerated at a predetermined acceleration, the print medium W is conveyed while the tension and the like of the print medium W are not stable. Although the influence of the deformation is large, in the present embodiment, since the head gap is changed to the temperature gap according to the temperature difference information as described above, it is possible to secure a sufficient head gap for the deformation of the print medium W. Thus, contact of the print medium W with the head unit 51 can be prevented.

  Then, the sending control unit 13 gradually weakens the brake 12 in accordance with the decrease in the speed of the transport motor 47, and when the transport motor 47 stops, the brake 12 is maintained with a force that does not bend the print medium W, The winding control unit 63 stops the winding motor 62. Thus, the conveyance of the print medium W ends, and a series of printing operations ends (S36).

  In the ink jet printing apparatus 1 according to the above embodiment, the head gap, the ink ejection timing, and the mist collection strength are changed according to the temperature difference information. In some cases, the amount of deformation is small, and even if the head gap is initially set, it can be transferred without any problem. Therefore, the print control unit 24 determines whether or not the temperature difference information is equal to or greater than a preset threshold, and if the temperature difference information is equal to or greater than the threshold, the head gap corresponding to the above-described temperature difference information; The ink ejection timing and the mist collection strength may be changed, and if the temperature difference information is less than the threshold, these changes may not be made.

  Further, in the inkjet printing apparatus 1 of the above embodiment, the temperature difference information is obtained at the time when the acceleration and the deceleration of the print medium W are started, and the head gap and the like are changed according to the temperature difference information. The change timing of the head gap according to the temperature difference information is not limited to this, and when an abnormal state requiring the change of the head gap due to the deformation of the print medium W occurs, the change of the head gap or the like according to the temperature difference information occurs. May be performed. The abnormal state includes, for example, a case where the tension of the print medium W becomes unstable (abnormal) for some reason during the conveyance of the print medium W, and a change in the temperature detected by the first temperature sensor 25 is set in advance. There is a case where the temperature is equal to or higher than the threshold value (when the temperature inside the housing of the printing apparatus main body 3 rises sharply) or a case where the printing operation is restarted after the printing apparatus main body 3 is urgently stopped for some reason.

  Alternatively, the print control unit 24 may calculate the temperature difference information for each preset elapsed period, and change the head gap, the ink ejection timing, and the mist collection intensity according to the temperature difference information.

  Further, in the ink jet printing apparatus 1 of the above embodiment, the ink ejection timing is controlled based on the adjustment count number corresponding to the change of the head gap. However, the present invention is not limited to this. The ink ejection speed may be changed according to the change. Specifically, the print control unit 24 may increase the ink ejection speed as the head gap increases, so that the image is printed at a desired position.

  In addition, the inkjet printing apparatus 1 of the above-described embodiment performs printing processing on the print medium W wound in a roll shape, but the present invention is applied to an inkjet printing apparatus that performs printing processing on so-called cut paper. You may make it.

  Further, in the above embodiment, the printing apparatus of the present invention is applied to an ink jet printing apparatus. However, the present invention is not limited to this. For example, the present invention can be applied to a printing apparatus other than the inkjet method.

Regarding the printing apparatus of the present invention, the following supplementary notes are further disclosed.
(Note)

  In the printing apparatus of the present invention, a transport mechanism for transporting the print medium can be provided, and the control unit controls the transport mechanism to accelerate and transport the print medium at a predetermined acceleration and then transport the print medium at a constant speed. When the acceleration is started, the interval between the print medium and the printing unit may be changed by controlling the interval changing mechanism based on the difference between the temperature information detected by the temperature detection unit at the time of starting the acceleration and the temperature information outside the device housing. it can.

  Further, in the printing apparatus of the present invention, a transport mechanism for transporting the print medium can be provided, and the control unit controls the transport mechanism to transport the print medium at a constant speed and then decelerate at a predetermined acceleration. When the sheet is conveyed, the interval changing mechanism is controlled to change the interval between the print medium and the printing unit based on the difference between the temperature information detected by the temperature detection unit and the temperature information outside the apparatus casing at the time of the start of deceleration. be able to.

  In the printing apparatus of the present invention, the control unit can control the printing unit based on the interval changed by the interval changing mechanism.

  Further, in the printing apparatus of the present invention, the printing unit can include a mist collection unit that collects ink mist generated in the air due to ejection of ink from the inkjet head of the printing unit to the print medium, and the control unit includes The mist collection strength of the mist collection unit can be changed based on the interval changed by the interval changing mechanism.

REFERENCE SIGNS LIST 1 Inkjet printing device 2 Sending unit 3 Printing device main unit 4 Winding unit 10 Roll 11 Roll support shaft 12 Brake 13 Sending control unit 21 Transporting units 22A, 22B Printing unit 23 Operation panel 24 Printing control unit 25 First temperature sensor 26 Second temperature sensor 27 Interval changing mechanisms 31 to 40 Guide roller 41 Lower head support member 42 meandering control units 42a, 42b meandering control roller 42c meandering control motor 42d edge sensor 43 transport roller 44 encoder 47 transport motors 51K, 51C, 51M, 51Y, 51P Head unit 52 Mist collecting units 57A to 57J Ink jet head 60 Printed roll 61 Take-up shaft 62 Take-up motor 63 Take-up control unit IM ink mist W Print medium

Claims (5)

A printing unit that performs printing processing on the print medium in a non-contact manner,
An interval changing mechanism for changing an interval between the print medium and the printing unit,
A temperature detection unit that detects a temperature inside the device housing;
A control unit configured to control the interval change mechanism to change an interval between the print medium and the print unit based on a difference between the temperature information detected by the temperature detection unit and the temperature information outside the apparatus housing. Printing equipment. A transport mechanism for transporting the print medium,
The control unit controls the transport mechanism, when transporting the print medium at a constant speed after being accelerated and transported at a predetermined acceleration,
Based on a difference between the temperature information detected by the temperature detection unit and the temperature information outside the device housing at the time of the acceleration start, the interval changing mechanism is controlled to change the interval between the print medium and the printing unit. The printing device according to claim 1. A transport mechanism for transporting the print medium,
The control unit controls the transport mechanism, when transporting the print medium at a predetermined acceleration after transporting the print medium at a constant speed,
Based on a difference between the temperature information detected by the temperature detection unit and the temperature information outside the apparatus housing at the time of the start of the deceleration, the interval changing mechanism is controlled to change the interval between the print medium and the printing unit. The printing device according to claim 1.   The printing apparatus according to claim 1, wherein the control unit controls the printing unit based on the interval changed by the interval changing mechanism. A mist collection unit that collects ink mist generated in air due to ejection of ink from the inkjet head of the printing unit to the print medium,
The printing apparatus according to claim 1, wherein the control unit changes the mist collection strength of the mist collection unit based on the interval changed by the interval change mechanism.