JP5287830B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus that ejects ink onto a recording medium.

  In the ink jet recording apparatus described in Patent Document 1, intermittent transport operation along the transport direction of the recording medium and reciprocation of the print head along the scanning direction orthogonal to the transport direction are repeated alternately. The recording operation (bidirectional printing) is performed by ejecting ink at the time of scanning in both directions, ie, when the recording head is moved forward and backward.

  In this bi-directional printing, in order to achieve high print quality, it is desirable that the landing position (dot formation position) during forward scanning and the landing position during backward scanning are aligned in the scanning direction. Here, since ink is ejected in the scanning direction due to the inertia of the movement of the recording head until it is ejected from the nozzle and landed, the actual ink ejection depends on the scanning speed of the recording head and the ink flight time (ink (Determined from the speed and the gap between the recording head and the recording medium), the landing position at the time of forward scanning and backward scanning can be obtained by performing the theoretical timing that is positioned before the dot formation position by a predetermined distance. Can be aligned.

  However, in actuality, the ink speed varies among products, the ink speed is not completely equal during forward scanning and backward scanning, or the gap between the recording head and the recording medium is completely For reasons such as being non-constant, even if jetting is performed at the theoretical timing (position) determined as described above during forward scanning and backward scanning, a slight landing position deviation occurs. Therefore, it is necessary to adjust the injection timing at the forward scanning and the backward scanning from the theoretical timing.

  Therefore, in order to adjust the ink ejection timing at the time of forward scanning of the recording head and the ink ejection timing at the time of backward scanning, the ink jet recording apparatus described in Japanese Patent Application Laid-Open Publication No. 2003-122867 discloses the backward movement with respect to the ink ejection timing during forward scanning. A pattern in which the ink ejection timing during scanning is varied stepwise is formed on the recording medium. Then, a pattern with the smallest amount of landing position deviation is detected, and the ink ejection timing during the forward scanning of the recording head and the ink ejection timing during the backward scanning are adjusted to the ejection timing at the above-mentioned minimum pattern. The relative displacement of the landing position in the scanning direction during forward scanning and backward scanning is eliminated.

JP 2009-196367 A

  By the way, in the ink jet recording apparatus described in Patent Document 1, a recording medium on which a pattern is formed may be deformed into a wavy shape under the influence of ambient humidity. As the ambient humidity increases, the undulation of the recording medium increases. Even when the ambient humidity is the same, the undulation of the plurality of recording media is not uniform and varies from recording medium to recording medium. Occurs.

  When a pattern is formed on a recording medium having such a variation in the undulation, the area of the recording medium on which the pattern is formed may be large or small, and the inkjet head and the recording medium The gap between the media varies. If the gap varies, the flight time of the ink ejected from the inkjet head varies. Then, since the flying ink has an initial speed in the moving direction of the inkjet head that moves in the scanning direction, the flying distance in the scanning direction also varies depending on the variation in the flying time, and the landing positions in the scanning direction vary. End up. For this reason, even if a pattern is formed in an area of a recording medium and the ejection timing is adjusted, the undulation varies from recording medium to recording medium. It was difficult to adjust so as to be small.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus capable of adjusting with high accuracy by forming a pattern in a region where the waviness of a recording medium is small.

  An ink jet recording apparatus according to the present invention includes an ink jet head having a nozzle for ejecting ink, a scanning unit that reciprocates the ink jet head in a predetermined scanning direction, and a recording medium that is spaced from each other in the scanning direction. A transport unit that transports the recording medium in a transport direction perpendicular to the scan direction with respect to the ink jet head, the ink jet head, the scan unit, and An inkjet recording apparatus comprising: a control unit that controls the transport unit to perform recording on the recording medium, wherein the control unit performs forward scanning and backward scanning of the inkjet head. When the ink is ejected, the ink is ejected onto the recording medium, and the landing position in the forward scanning and the landing position in the backward scanning Pattern forming means for forming one or more patterns including at least one mark for detecting a relative positional deviation in the scanning direction on the recording medium conveyed by the conveying means, The pattern forming unit includes a region in which a printing area of all the marks belonging to at least one of the one or more patterns overlaps with one clamping part of the plurality of clamping parts in the transport direction, and the clamping part The pattern is formed so as not to include a line that is equidistant from the sandwiching portion adjacent thereto and extends in the transport direction.

  The recording medium may be deformed into a wavy shape due to the influence of ambient humidity, etc., but the area of the recording medium transported by the transport means that overlaps the sandwiching section in the transport direction is the sandwiching section. Is overlapped in the transport direction with the region sandwiched between the two, and is less likely to float than other regions, and the gap with the inkjet head is stable. In this way, the effect of the holding unit restraining the recording medium is strongest in the region overlapping the holding unit with respect to the transport direction, and the effect becomes weaker as the distance from the region in the scanning direction is greater, and is most intermediate between the holding unit and the holding unit. weak. That is, the position that is equidistant from the sandwiching part and the part that overlaps the line extending in the transport direction is most likely to float, and the gap with the inkjet head is not stable. According to the ink jet recording apparatus of the present invention, by avoiding the region where the gap with the ink jet head is unstable and forming a pattern in a region where the undulation of the stable recording medium is small, the influence of ambient humidity and the like can be reduced. Regardless, it is possible to adjust with high accuracy.

  In addition, among the plurality of sandwiching portions, some of the sandwiching portions constitute a dense portion arranged at an interval smaller than a predetermined interval, and the remaining sandwiching portions are adjacent to the dense portion and the predetermined interval. The sparse part arranged at the above-mentioned interval is configured, and the pattern forming unit includes the sandwiching area in which print areas of all the marks belonging to at least one pattern among the one or more patterns configure the sparse part. It is preferable that the pattern is formed so as not to include a line extending in the transport direction that is equidistant from the sandwiching part and the sandwiching part adjacent to the sandwiching part.

  The plurality of sandwiching portions may be arranged at non-uniform intervals, not all at the same interval, and the plurality of sandwiching portions may be spaced apart from a dense portion arranged at intervals smaller than a predetermined interval and a predetermined interval or more. There are sparse parts arranged side by side. When the recording medium undulates due to the influence of ambient humidity or the like, the recording medium may be deformed in a wavy shape such that peaks and valleys exist at intervals in the scanning direction. Considering a case where the recording medium thus deformed is locally sandwiched by a plurality of sandwiching portions, the recording medium should have a shape that minimizes the total deformation energy of the recording medium and the sandwiching portion. It is. When the interval between the sandwiching portions is small, the waviness interval of the recording medium needs to be equal to or less than the interval between the sandwiching portions in order to achieve zero deformation at the sandwiching portion. As becomes smaller, the deformation energy of the recording medium increases rapidly.

  Then, the energy that causes the recording medium to be tightly deformed and the energy that elastically deforms the sandwiching portion are reversed, and the deformation of the recording medium at the sandwiching portion may not be zero. It is almost impossible to control which of the clamping parts constituting the dense part has zero deformation and which of the clamping parts is not zero. Therefore, the deformation of the recording medium in the sandwiching portion configured in the sparse portion is zero and stable, but the deformation of the recording medium in the sandwiching portion configured in the dense portion may be unstable.

  Therefore, the printing area of all the marks belonging to at least one pattern among the one or more patterns includes a sandwiching part constituting the sparse part and a region overlapping in the transport direction, and the sandwiching part and the sandwiching part adjacent to the sandwiching part. By forming the pattern so as not to include lines that are equidistant and extend in the transport direction, the pattern is formed in a region where the undulation of the recording medium with a stable gap with the inkjet head is small, and the accuracy is higher. You can make adjustments.

  Further, the control means selects one of a plurality of preset scanning speeds, and controls the scanning means to move the inkjet head at the selected scanning speed, and the pattern forming means Forming a plurality of the patterns corresponding to the plurality of types of scanning speeds on one recording medium, and at least printing areas of all the marks belonging to the pattern corresponding to the fastest scanning speed. The pattern is formed so as not to include a line extending in the transport direction that is equidistant from the sandwiching part and the sandwiching part adjacent to the sandwiching part and the sandwiching part adjacent to the sandwiching part that constitutes the sparse part and the transporting direction. Preferably formed.

  When the gap between the inkjet head and the recording medium changes, the higher the scanning speed of the inkjet head, the greater the flight distance in the scanning direction per flight time, and the greater the displacement of the landing position in the scanning direction. Therefore, among the plurality of patterns, the print area of all the marks belonging to the pattern corresponding to the fastest scanning speed includes a sandwiching part constituting the sparse part and an area overlapping in the transport direction, and is adjacent to the sandwiching part. If the pattern is formed so as not to include a line that is equidistant from the holding portion and extends in the transport direction, even if there is no size that can form all the patterns in the above-described region, the landing position Precise adjustment with high accuracy can be preferentially performed at the fastest scanning speed at which the deviation tends to increase.

  In addition, it is preferable that the pattern forming unit forms the plurality of patterns on the recording medium in order of decreasing scanning speed from the pattern corresponding to the fastest scanning speed.

  In addition to the influence of ambient humidity, the recording medium is also deformed into a wavy shape by absorbing ink. That is, the later formed pattern is affected by further undulation of the recording medium due to the absorption of the ink of the previously formed pattern. Therefore, by forming the pattern corresponding to the high scanning speed on the recording medium first, the higher the accuracy of the scanning speed, the easier the landing position shift becomes.

In addition, the pattern forming unit is formed by shifting the plurality of patterns in the transport direction, and among the plurality of patterns, the pattern corresponding to a slow scanning speed is located upstream of the recording medium in the transport direction. It is preferable to form.

  According to this, a pattern corresponding to a high scanning speed can be formed on the recording medium first.

  Further, the pattern includes a plurality of marks having different ink ejection timings during backward scanning with respect to ink ejection timings during forward scanning of the inkjet head, and the pattern forming means includes the plurality of marks. However, it is preferable that the pattern is formed so that the recording mediums transported by the transport unit are arranged in a line in the transport direction.

  According to this, the adjustment can be easily performed in a short time simply by selecting one mark from a plurality of marks belonging to one pattern. Normally, the difference in landing position depending on whether the recording position is an overlapping area or other area with respect to the conveyance direction of a specific clamping unit is different between individual patterns formed by ejecting ink at slightly different timings. Compared to the difference in landing position, it is so large that it cannot be ignored. Therefore, by forming a pattern so that a plurality of marks belonging to one pattern are arranged in a line in the conveyance direction of the recording medium, the pattern is formed so that a plurality of marks are arranged in parallel in the scanning direction. In addition, it is possible to reduce the gap variation between the area where the pattern of the recording medium is to be formed and the inkjet head, and to accurately form a pattern whose position is gradually shifted.

  In addition, the pattern forming unit includes the holding unit that holds the recording medium on the outermost side in the scanning direction, and the printing region of all the marks belonging to at least one of the one or more patterns The pattern is preferably formed so as to include a region overlapping in the transport direction and not including a line that is equidistant from the sandwiching portion and the sandwiching portion adjacent to the sandwiching portion and that extends in the transport direction.

  According to this, since the recording medium is cantilevered further outside the clamping part that clamps the recording medium on the outermost side in the scanning direction, the deformation energy of the recording medium and the elasticity of the clamping part as described above In comparison with the deformation energy, it is only necessary to consider the deformation of the recording medium on one side of the sandwiching part, so as to whether the deformation of the recording medium in the sandwiching part is zero or not than other sandwiching parts. It tends to be zero.

  By avoiding the area where the gap with the inkjet head is unstable and forming a pattern in the area where the undulation of the stable recording medium is small, it is possible to make highly accurate adjustments regardless of the influence of ambient humidity, etc. .

1 is a schematic side view of an ink jet printer according to an embodiment. It is a schematic plan view of an inkjet printer. FIG. 6 is a front view of a paper discharge roller pair. 1 is a block diagram schematically illustrating an electrical configuration of an ink jet printer. It is a top view of a ruled line adjustment pattern. It is a figure explaining the structure of a ruled line adjustment pattern, (a) is a top view of some marks formed at the time of forward scanning, (b) is the plane of some marks formed at the time of backward scanning FIG. 4C is a plan view of the mark when there is no positional shift, and FIG. 4D is a plan view of the mark when the position is shifted. FIG. 6 is a plan view of a recording sheet on which ruled line adjustment patterns are formed. It is a schematic front view explaining the undulation of the recording paper. FIG. 10 is a plan view of a recording sheet on which a ruled line adjustment pattern according to Modification 1 is formed. FIG. 10 is a plan view of a recording sheet on which a ruled line adjustment pattern according to Modification 2 is formed.

  Hereinafter, preferred embodiments of the present invention will be described. This embodiment is an example in which the present invention is applied to an ink jet printer that records desired images, characters, and the like on a recording paper by ejecting ink from the ink jet head onto the recording paper.

  First, a schematic configuration of the ink jet printer according to the present embodiment will be described. FIG. 1 is a schematic side view of an ink jet printer according to the present embodiment. FIG. 2 is a schematic plan view of the ink jet printer. As shown in FIGS. 1 and 2, an inkjet printer 1 (inkjet recording apparatus) includes a carriage 2 configured to reciprocate along a predetermined scanning direction (a direction perpendicular to the plane of FIG. 1), and the carriage 2. The mounted inkjet head 3, the transport mechanism 4 that transports the recording paper P along the paper transport path 5 (shown by a one-dot chain line in FIG. 1) located below the ink jet head 3, and the operation of each part are controlled. And a control device 50 for controlling the overall operation.

  The carriage 2 is supported by two guide shafts 6 and 7 extending in parallel with the scanning direction, and is configured to reciprocate in the scanning direction along the two guide shafts 6 and 7. An endless belt 9 is connected to the carriage 2, and when the endless belt 9 is driven to travel by a carriage drive motor 64 (see FIG. 4), the carriage 2 scans in the scanning direction as the endless belt 9 travels. To move to.

  An ink jet head 3 is mounted on the lower surface of the carriage 2. The ink jet head 3 reciprocates in the scanning direction as the carriage 2 reciprocates in the scanning direction. That is, the carriage 2 in this embodiment and the two guide shafts 6 and 7, the endless belt 9, and the carriage drive motor 64 that are configured to reciprocate the carriage 2 reciprocately scan the inkjet head 3 in the present invention. This corresponds to the scanning means.

  The ink jet head 3 is supplied from an ink cartridge (not shown) by a piezoelectric actuator, and ejects ink in the ink flow path of the stored flow path unit from a plurality of nozzles 15. A plurality of nozzles 15 are arranged side by side in the transport direction (left and right direction in FIG. 1 orthogonal to the scanning direction) to form a nozzle row, and four nozzle rows are arranged in the scanning direction. The lower surface of the ink jet head 3 is parallel to the scanning direction and the transport direction, and is an ink ejecting surface 3a in which a plurality of nozzles 15 are respectively opened. For each nozzle row, magenta, cyan, yellow, black Ink is ejected.

  The transport mechanism 4 includes a paper feed roller 8, a main roller pair 10, and a paper discharge roller pair 13, and transports the recording paper P along the paper transport path 5. The main roller pair 10 and the paper discharge roller pair 13 are disposed with the carriage 2 (inkjet head 3) interposed therebetween in the transport direction, and the paper feed roller 8 is disposed below them.

  The paper feed roller 8 is rotationally driven by a paper feed motor 61 (see FIG. 4), takes out the uppermost recording paper P from the stacked recording papers P, and sends it to the paper transport path 5.

  The main roller pair 10 includes a main roller 11 that is rotationally driven by a main motor 62 (see FIG. 4), and a driven roller 12 that is driven to rotate as the main roller 11 rotates. The driven roller 12 is formed by winding three rubber members 82 at intervals in the axial direction of the rotary shaft 81. The main roller pair 10 is transported to the inkjet head 3 by the cooperation of the main roller 11 and the driven roller 12 with the recording paper P taken out by the paper feed roller 8 and conveyed in a curved manner.

  FIG. 3 is a front view of the paper discharge roller pair. As shown in FIGS. 1 to 3, the pair of paper discharge rollers 13 is driven by a plurality of paper discharge rollers 14 that are rotationally driven by a paper discharge motor 63 (see FIG. 4) and the rotation of the paper discharge rollers 14. And a plurality of star-shaped spurs 86.

  The plurality of spurs 86 are arranged at intervals in the scanning direction. Among the plurality of spurs 86, a part of the spurs 86 arranged at the center in the scanning direction of the area where the recording paper P is conveyed constitute a dense portion 87a arranged at close intervals, and the scanning direction thereof The remaining remaining spurs 86 constitute sparse portions 87b arranged at intervals equal to or greater than the intervals of the spurs 86 constituting the dense portion 87a. In addition, the spur 86 in this embodiment is equivalent to the clamping part in this invention. In addition, when a plurality of spurs 86 have a plurality of sets integrally held by one urging member, the set of one spur 86 is regarded as a clamping portion in the present invention.

  This is because, in the inkjet printer 1 according to the present embodiment, when a plurality of types of recording paper P having different sizes, such as A4 and postcards, are transported by the transport mechanism 4, the width adjustment mechanism (not shown) is used regardless of the size of the recording paper P. The recording sheet P to be conveyed is brought to the center in the scanning direction. At this time, as shown in FIG. 3, for example, there are areas where the recording paper P frequently passes, and areas where only a large size recording paper P passes, for both postcards and A4. In such a case, all the spurs 86 may be set as the interval between the spurs 86 constituting the dense portion 87a. However, this increases the number of spurs 86 and increases the cost. In addition, although all the spurs 86 may be set at intervals of the spurs 86 constituting the sparse portion 87b, in this case, when a small recording sheet P such as a postcard is conveyed, a portion sandwiched by the spurs 86. The frictional force required for conveyance is insufficient. Therefore, the plurality of spurs 86 are not arranged at the same interval, but are arranged so as to constitute the dense portion 87a and the sparse portion 87b.

  The paper discharge roller 14 is formed by winding a plurality of rubber members 84 at intervals in the axial direction of a rotary shaft 83 connected to a paper discharge motor 63. The plurality of rubber members 84 are disposed so as to face the plurality of spurs 86, hold the recording paper P between the plurality of spurs 86, and are elastically displaced in directions that are separated from the recording paper P, respectively. It is configured to be possible. The pair of paper discharge rollers 13 discharges the recording paper P on which an image, characters, and the like have been recorded by the inkjet head 3.

  As shown in FIGS. 1 and 2, a platen 16 is disposed below the carriage 2 (lower in FIG. 1) between the main roller pair 10 and the paper discharge roller pair 13 in the transport direction. A plurality of ribs (not shown) are formed on the upper surface facing the surface 3a. The plurality of ribs reduce the contact area with the recording paper P and reduce the friction with the recording paper P, and are arranged extending in the transport direction. A virtual surface including the tip portions of the plurality of ribs is a conveyance surface parallel to the ink ejection surface 3a on which the recording paper P is conveyed, and supports the recording paper P.

  The inkjet head 3 is supported by the platen 16 while performing reciprocating scanning along the scanning direction integrally with the carriage 2, and is directed toward the recording paper P that is transported downstream in the transport direction by the transport mechanism 4. By ejecting ink from the nozzles 15, desired images and characters are recorded on the recording paper P.

  Next, the control device 50 that controls the entire inkjet printer 1 will be described. FIG. 4 is a block diagram showing an electrical configuration of the ink jet printer. The control device 50 includes, for example, a central processing unit (CPU), a read only memory (ROM) that stores various programs and data for controlling the overall operation of the inkjet printer 1, and a CPU. A random access memory (RAM) that temporarily stores data to be processed is provided, and a program stored in the ROM is executed by the CPU to perform various controls as described below. May be. Alternatively, it may be a hardware type in which various circuits including an arithmetic circuit are combined.

  As shown in FIG. 4, the control device 50 includes a head control unit 51, a conveyance control unit 52, a carriage control unit 53, a mode selection unit 54, and a pattern formation unit 55.

  The head control unit 51 controls the inkjet head 3 based on data input from the PC 60 that is an external device, and ejects ink onto the recording paper P. The transport controller 52 drives the paper feed motor 61, the main motor 62, and the paper discharge motor 63 of the transport mechanism 4, and feeds the recording paper P by the paper feed roller 8, the main roller 11, and the paper discharge roller 14. Transport along. The carriage control unit 53 controls the carriage drive motor 64 to reciprocate the carriage 2 in the scanning direction, thereby causing the inkjet head 3 to reciprocate.

  The ink jet printer 1 receives the ink jet head 3, the paper feed motor 61, and the main motor 62 when the print command is input from the PC 60, which is an external device, to the head controller 51, the transport controller 52, and the carriage controller 53. The paper discharge motor 63 and the carriage drive motor 64 are controlled to perform recording on the recording paper P. At this time, the inkjet printer 1 scans the inkjet head 3 in one scanning direction (leftward in FIG. 1) (forward scanning) and in the other scanning direction (rightward in FIG. 1). In both cases, so-called bidirectional printing is performed in which ink is ejected from the nozzles 15 toward the recording paper P.

  The mode selection unit 54 selects a print mode based on the resolution of the recording data input from the PC 60. The print mode is a plurality of modes determined according to the required degree of print quality. In this embodiment, the mode selection unit 54 can select one mode from four modes. When these four modes are compared, the scanning speed of the carriage 2 (inkjet head 3) by the head control unit 51 is increased with priority given to the printing time over the printing quality as the mode has a lower resolution. The reason why the printing quality decreases as the scanning speed of the inkjet head 3 increases is that the number of ink dots per length in the scanning direction formed when ink is ejected in the same cycle is reduced. This is because the landing position deviation of the ink dots becomes large. The reason why the landing position deviation of each ink dot becomes large will be described later.

  The pattern forming unit 55 sets the ink ejection timing, the conveyance amount, and the like in the head control unit 51, the conveyance control unit 52, and the carriage control unit 53 when a command for adjusting the ruled line is input from the PC 60 which is an external device. Then, a ruled line adjustment pattern 70 (see FIG. 5) is formed on the recording paper P. The ruled line adjustment pattern 70 is a pattern that is referred to in order to optimally adjust the ink ejection timing during forward scanning and backward scanning of the inkjet head 3 in bidirectional printing, as will be described in detail later.

  In bi-directional printing, in order to land ink (form dots) at the same position on the recording paper P during forward scanning and backward scanning, the inkjet head 3 is used during forward scanning and backward scanning. Therefore, it is necessary to change the ink ejection timing (the ejection position in the scanning direction).

  At this time, the optimum values of the ink ejection timings during forward scanning and backward scanning of the inkjet head 3 are the scanning speed of the carriage 2, the ink ejection surface 3a of the inkjet head 3, and the recording paper P conveyed through the conveyance mechanism 4. , And the flying speed of the ink ejected from the inkjet head 3, and it is necessary to adjust each individual.

  The timing for adjustment is the manufacturing stage before shipment or when the user determines that printing is defective during use. For example, the mode in which the user performs ruled line adjustment with an input unit (not shown) such as a button. Select to start. As an adjustment method, ink is ejected from the inkjet head 3 to form a ruled line adjustment pattern 70 (described later) on the recording paper P conveyed by the conveying mechanism 4, and the ruled line adjustment pattern formed on the recording paper P is formed. 70 to adjust. FIG. 5 is a plan view of a ruled line adjustment pattern. 6A and 6B are diagrams for explaining the configuration of the ruled line adjustment pattern. FIG. 6A is a plan view of some marks formed during forward scanning, and FIG. 6B is a portion formed during backward scanning. FIG. 4C is a plan view of the mark when there is no position shift, and FIG. 4D is a plan view of the mark when there is a position shift.

  Specifically, as shown in FIG. 5, the ruled line adjustment pattern 70 includes seven marks 71 a to 71 g formed side by side in the longitudinal direction of the recording paper P. The seven marks 71a to 71g are landed in the scanning direction of the ink ejected during the backward scanning by fixing the ink ejection timing during the forward scanning and shifting the ink ejection timing during the backward scanning by a predetermined timing. The position is shifted by a predetermined distance. As shown in FIG. 6A, each mark 71 forms four rectangular dot groups 72 having a predetermined width at equal intervals with the same width as the dot group 72 during reciprocating scanning. Then, as shown in FIG. 6B, the three rectangular dot groups 73 having the same width as the dot group 73 are arranged at the same interval as the dot group 72 during backward scanning without changing the position in the transport direction. Open and form at regular intervals.

  Then, as shown in FIG. 6C, among the seven marks 71a to 71g, the mark 71d forms a black plane without white streaks without the dot group 72 and the dot group 73 overlapping in the scanning direction. Therefore, the ink ejection timing at the forward scanning and the backward scanning of the inkjet head 3 is optimum, that is, there is a positional deviation in the scanning direction between the ink landing position at the reciprocating scanning and the ink landing position at the backward scanning. Make it not exist.

  As shown in FIG. 6D, among the seven marks 71a to 71g, the mark 71g has the dot group 72 and the left end of the dot group 73 overlapped with each other. A white streak is formed between the right end of the group 73 and, compared with the mark 71d, the ink ejection timing in the backward scanning is earlier than the ink ejection timing in the forward scanning of the inkjet head 3, and the reciprocating scanning is performed. There is a positional deviation in the scanning direction between the ink landing position at the time and the ink landing position during the backward scanning. For the remaining marks 71e and 71f, the ink ejection timing at the backward scanning from the inkjet head 3 is early, and the ink landing position at the reciprocating scanning and the ink landing position at the backward scanning are the same scanning direction as 71g. Misalignment has occurred.

  Concerning the marks 71a to 71c, the right end of the dot group 72 and the left end of the dot group 73 overlap each other, and a white streak is formed between the left end of the dot group 72 on the opposite side and the right end of the dot group 73. Compared with the mark 71d, the ink ejection timing during the backward scanning is slower than the ink ejection timing during the forward scanning of the inkjet head 3, and the ink landing position during the reciprocating scanning and the ink landing during the backward scanning. The position is misaligned in the scanning direction opposite to 71g. In either case, the displacement in the scanning direction can be visually confirmed as white streaks.

  As described above, the ink ejection timing during the forward scanning is fixed, the ink ejection timing during the backward scanning is shifted by a predetermined timing, and the landing position in the scanning direction of the ink ejected during the backward scanning is determined by a predetermined distance. Seven marks 71a to 71g that are shifted one by one are formed on the recording paper P, and the user selects the mark 71 that is the most inconspicuous white stripe from the seven marks 71a to 71g and has a black plane, and so on. The number of the mark 71 is input at the input unit (not shown). Then, the ink ejection timing at the time of forward scanning and backward scanning of the inkjet head 3 when the selected mark 71 is formed is set in the control device 50 as the optimal ejection timing, and ink landing at the time of reciprocating scanning is set. It is possible to eliminate a positional shift in the scanning direction between the position and the ink landing position during backward scanning.

  In order to perform this adjustment for each mode, the pattern forming unit 55 applies four ruled line adjustment patterns 70 on one sheet of recording paper P at the scanning speed of the carriage 2 corresponding to the four modes in the transport direction. They are formed at the same position and shifted in the scanning direction (see FIG. 7). In order to form four ruled line adjustment patterns 70 having different scanning speeds at the same position in the conveyance direction of the recording paper P, the ink-jet head 3 is scanned once and again at each scanning speed for a total of 4 reciprocations. A part of one ruled line adjustment pattern 70 is formed, and this is performed for the length of the ruled line adjustment pattern 70 in the transport direction.

  Here, when the ruled line adjustment pattern 70 is formed, the scanning speed of the carriage 2 and the flying speed of the ink ejected from the inkjet head 3 are affected by the environment of the ruled line adjustment, for example, low humidity or high humidity. Even the environment is not so affected. However, the gap between the ink ejection surface 3a of the inkjet head 3 and the recording paper P conveyed by the conveyance mechanism 4 is greatly affected by the surrounding humidity. This is because the recording paper P absorbs moisture and expands as the ambient humidity increases, and deforms so as to undulate. Even if the ambient humidity is the same, the method of undulating the plurality of recording papers P is not uniform and varies for each recording paper P.

  Then, when the ruled line adjustment pattern 70 is to be formed on the recording paper P having such a variation in the undulation, the ruled line adjustment pattern 70 is formed in a region where the waviness of the recording paper P is large every time adjustment is performed. When the undulation is formed in a small area, the gap between the inkjet head 3 and the recording paper P varies, and the landing position in the scanning direction varies. Therefore, even if the ruled line adjustment pattern 70 is formed in an area of a certain recording paper P and the ejection timing is adjusted, the undulation condition varies for each recording paper P. It was difficult to adjust so that the amount of deviation was small.

  Therefore, in the present embodiment, as shown in FIG. 7, the pattern forming unit 55 includes a region where the ruled line adjustment pattern 70 print region includes an area that overlaps the spur 86 in the conveyance direction, and the spur 86 and the adjacent spur. A ruled line adjustment pattern 70 is formed on the recording paper P conveyed by the conveyance mechanism 4 so as not to include a line that is equidistant from the line 86 and extends in the conveyance direction. The above-described line that is equidistant from the spur 86 and the adjacent spur 86 and that extends in the transport direction is a line that extends in the transport direction through the middle of the inner ends of the two spurs 86. FIG. 7 is a plan view of a recording sheet on which ruled line adjustment patterns are formed. In FIG. 7, a ruled line adjustment pattern corresponding to the fastest scanning speed among the four ruled line adjustment patterns 70 is defined as a ruled line adjustment pattern 70a. Hereinafter, as the scanning speed decreases, ruled line adjustment patterns 70b, 70c, and 70d To do. A region through which the spur 86 passes is indicated by a two-dot chain line.

  Then, the print area of all the marks 71a to 71g belonging to the ruled line adjustment pattern 70a sandwiches the recording paper P on one outermost side in the scanning direction, and an area X1 overlapping the spur 86 constituting the sparse part 87b in the transport direction. Including all the marks 71a to 71g belonging to the ruled line adjustment pattern 70a so as not to include the line X4 that is equidistant from the spur 86 and the adjacent spur 86 and extends in the transport direction. In addition, the printing area of all the marks 71a to 71g belonging to the ruled line adjustment pattern 70b includes an area X2 that is sandwiched on the other outermost side and overlaps the spur 86 constituting the sparse part 87b in the transport direction. All the marks 71a to 71g belonging to the ruled line adjustment pattern 70b are formed so as not to include the line X4 that is equidistant from the spur 86 adjacent to and extending in the transport direction. Further, the printing areas of all the marks 71a to 71g belonging to the ruled line adjustment pattern 70c and all the marks 71a to 71g belonging to the ruled line adjustment pattern 70d sandwich the recording paper P, and the spurs 86 at the extreme ends in the scanning direction. Further, it includes a region X3 that overlaps the spur 86 constituting the sparse portion 87b with respect to the transport direction, and does not include the line X4 that is equidistant from the spur 86 and the spur 86 adjacent thereto and extends in the transport direction. In this way, all the marks 71a to 71g belonging to the ruled line adjustment pattern 70c and all the marks 71a to 71g belonging to the ruled line adjustment pattern 70d are formed.

  Here, the undulation of the recording paper P when the undulating recording paper P is conveyed by the conveyance mechanism 4 will be described with reference to FIG. FIG. 8 is a schematic front view for explaining the undulation of the recording paper. In addition, in FIG. 8, the clamping part of the spur 86 and the rubber member 84 is shown by the black dot.

  In the present embodiment, for example, the recording paper P, which is A4 size vertical eye paper, is transported so that the longitudinal direction and the transport direction are parallel, and the ruled line adjustment pattern 70 is formed on the recording paper P. Assumed. The vertical recording paper P is a paper in which a plurality of fibers extend in the longitudinal direction and is arranged in the width direction. When such vertical recording paper P absorbs moisture in a high-humidity environment or the like, it extends in the width direction and undulates, and deforms in a wavy shape such that peaks and valleys exist at intervals of about several centimeters in the scanning direction. .

  As shown in FIG. 8, the black spot portion sandwiched between the spur 86 and the rubber member 84 constituting the sparse portion 87 b of the recording paper P cannot be sandwiched and extended and is not lifted. The portion of the recording paper P that is sandwiched between the two black spots in the area facing the ink jet head 3 can be freely extended, but both ends of the black spots are fixed, and the platen 16 from below is fixed. Because it is supported, it rises. Thus, the effect that the spur 86 constituting the sparse portion 87b restrains the recording paper P is strongest in the region overlapping with the spur 86 in the transport direction, and the effect decreases as the distance from the region overlapping with the spur 86 in the scanning direction increases. It is weakest between the spur 86 and the spur 86. That is, the region overlapping the intermediate position between the spur 86 and the spur 86 and the conveying direction is most likely to float, and the gap with the inkjet head 3 is not stable.

  By the way, not only the spur 86 constituting the sparse portion 87b and the spur 86 constituting the dense portion 87a, the deformation of the recording paper P should have a shape that minimizes the total deformation energy of the recording paper P and the spur 86. (The principle of minimum potential energy). If there is a sufficient interval between the spur 86 and the spur 86, the spur 86 deforms the recording paper P to be zero, and the recording paper P deforms between the spur 86 and the spur 86.

  In order to achieve zero deformation at the spur 86, the undulation interval of the recording paper P must be equal to or less than the arrangement interval of the spur 86. However, when the undulation interval of the recording paper P is reduced, the deformation energy of the recording paper P increases rapidly. . When the arrangement interval between the spurs 86 is narrow, the energy that causes the recording paper P to be deformed tightly and the energy that elastically deforms the spurs 86 are reversed, and the deformation of the recording paper P at the spurs 86 does not become zero. Occurs. Of the spurs 86 constituting the dense portion 87a, the deformation at which the spur 86 is zero and the deformation at which the spur 86 is not zero belong to a complex event, and it is almost impossible to control.

  Therefore, the deformation of the recording paper P in the spur 86 constituting the sparse portion 87b is zero and stable, but the deformation of the recording paper P in the spur 86 constituting the dense portion 87a may be unstable. However, the gap between the spur 86 and the intermediate position between the spur 86 and the position overlapping in the conveying direction is stable.

  Therefore, in the present embodiment, the pattern forming unit 55 includes an area in which the printing area of the ruled line adjustment pattern 70 overlaps with the spur 86 constituting the sparse part 87b arranged side by side at a predetermined interval or more in the conveyance direction. The ruled line adjustment pattern 70 is formed so as not to include a line connecting the spur 86 and the spur 86 adjacent thereto.

  Further, when the gap between the inkjet head 3 and the recording paper P changes, the faster the scanning speed during the reciprocating scanning of the inkjet head 3, the greater the flight distance in the scanning direction per flight time. The deviation of the landing position with respect to increases.

  At this time, for example, photographic printing is performed in the high resolution mode, but since the scanning speed of the inkjet head 3 is slow and the displacement of the landing position is small, overstrike is performed to increase the resolution. The landing position shift is not noticeable. On the other hand, text printing or the like is performed in the low-resolution mode, but since the scanning speed of the inkjet head 3 is fast and the landing position is largely shifted, the landing position is not shifted, so that the landing position is not shifted. Easy to stand out.

  Since the recording paper P medium is cantilevered outside the spur 86 that clamps the recording paper P on the outermost side in the scanning direction, the deformation energy of the recording paper P and the elastic deformation of the spur 86 as described above. In comparison with the energy, only the deformation of the recording paper P on one side of the spur 86 needs to be considered, so whether or not the deformation of the recording paper P in the spur 86 becomes zero is more zero than the other clamping parts. It is easy to become.

  Therefore, among the four ruled line adjustment patterns 70 corresponding to the four modes, the print areas of all the marks 71a to 71g belonging to the ruled line adjustment pattern 70a corresponding to the fastest scanning speed are the ones on the recording paper P in the scanning direction. Including the region X1 that overlaps the spur 86 constituting the sparse portion 87b with respect to the transport direction, and does not include the line X4 that is equidistant from the spur 86 and the adjacent spur 86 and that extends in the transport direction. In this way, all the marks 71a to 71g belonging to the ruled line adjustment pattern 70a are formed, and further, the print area of all the marks 71a to 71g belonging to the ruled line adjustment pattern 70b corresponding to the second fastest scanning speed is the ruled line adjustment pattern 70a. And a spur 86 having the same position in the transport direction and sandwiching the other outermost side and constituting the sparse portion 87b All the marks 71a to 71g belonging to the ruled line adjustment pattern 70b are formed so as not to include the line X4 that includes the region X2 overlapping in the feeding direction and is equidistant from the spur 86 and the adjacent spur 86 and extends in the transport direction. To do.

  The print areas of all the marks 71a to 71g belonging to the remaining two ruled line adjustment patterns 70c and all the marks 71a to 71g belonging to the ruled line adjustment pattern 70d are in the same position in the transport direction as the ruled line adjustment pattern 70a. And includes a region X3 that is inside the spur 86 at the both ends in the scanning direction and sandwiches the recording paper P and overlaps the spur 86 constituting the sparse portion 87b in the transport direction. All the marks 71a to 71g belonging to the ruled line adjustment pattern 70c and all the marks 71a to 71g belonging to the ruled line adjustment pattern 70d so as not to include the line X4 that is equidistant from the spur 86 adjacent to and extending in the transport direction. Form.

  According to the inkjet printer 1 of the present embodiment, the area of the recording paper P conveyed by the conveyance mechanism 4 that overlaps the spur 86 in the conveyance direction overlaps the area sandwiched by the spur 86 in the conveyance direction. The gap with the inkjet head 3 is more stable than the area. Thus, the effect that the spur 86 restrains the recording paper P is strongest in the region overlapping with the spur 86 in the transport direction, and the effect becomes weaker as the distance from the region in the scanning direction increases, and is most intermediate between the spur 86 and the spur 86. weak. That is, the position where the spur 86 and the center position of the spur 86 overlap with the transport direction is most likely to float, and the gap with the inkjet head 3 is not stable.

  Therefore, by avoiding the region where the gap with the inkjet head 3 is unstable and forming the ruled line adjustment pattern 70 in a region where the undulation of the stable recording paper P is small, regardless of the influence of ambient humidity, Adjustment with high accuracy can be performed. At this time, since the recording paper P on which recording is performed is used, it is not necessary to use a medium having the same thickness as the recording paper P for ruled line adjustment which is difficult to wave, and the running cost can be reduced.

  Further, among the plurality of ruled line adjustment patterns 70a to 70d, the print areas of all the marks 71a to 71g belonging to the ruled line adjustment pattern 70a corresponding to the fastest scanning speed constitute the sparse portion 87b of the recording paper P, and recording is performed. It includes an area overlapping the spur 86 that sandwiches the paper P at one outermost side in the scanning direction and the transport direction, and does not include a line that is equidistant from the spur 86 and the adjacent spur 86 and that extends in the transport direction. By forming all the marks 71a to 71g belonging to the ruled line adjustment pattern 70a, even when there is no region where all the ruled line adjustment patterns 70a to 70d can be formed at positions overlapping in the scanning direction as in this embodiment. Therefore, it is possible to preferentially perform high-precision adjustment at the fastest scanning speed at which landing position deviation tends to be large.

  Further, among the plurality of ruled line adjustment patterns 70a to 70d, the print areas of all the marks 71a to 71g belonging to the ruled line adjustment pattern 70b corresponding to the next highest scanning speed scan the sparse portion 87b of the recording paper P. And includes a spur 86 that has the same position in the transport direction as the ruled line adjustment pattern 70a and that holds the recording paper P on the other outermost side in the scanning direction, and overlaps in the transport direction. By forming all the marks 71a to 71g belonging to the ruled line adjustment pattern 70b so as not to include a line that is equidistant from the adjacent spur 86 and extends in the transport direction, the top two scans that are likely to have a large deviation in landing position. The speed can be adjusted with high accuracy in priority.

  Further, even if the longitudinal direction of the recording paper P of the horizontal paper is transported in parallel with the transport direction and the ruled line adjustment pattern 70 is formed in the above-described region, the gap with the inkjet head is stable. Even when such recording paper P is used, the positional deviation can be detected stably.

  Next, modified examples in which various changes are made to the present embodiment will be described. However, the same reference numerals are given to those having the same configuration as in the above embodiment, and the description thereof is omitted as appropriate.

  The pattern forming unit 55 includes a region where the printing area of the plurality of ruled line adjustment patterns 70 overlaps the spur 86 with respect to the transport direction, and a line extending at an equal distance from the spur 86 and the adjacent spur 86 and extending in the transport direction. The plurality of ruled line adjustment patterns 70 may be formed so as to be shifted in the transport direction after being excluded. For example, as shown in FIG. 9, among the plurality of ruled line adjustment patterns 70, the ruled line adjustment pattern 70 corresponding to the slow scanning speed may be formed on the upstream side in the conveyance direction of the recording paper P (Modification 1). At this time, the plurality of ruled line adjustment patterns 70 may be formed so as to be shifted in the transport direction and further shifted in the scanning direction.

  According to this, since the recording paper P undulates due to moisture absorption, it undulates by absorbing ink in addition to the influence of ambient humidity. That is, the ruled line adjustment pattern 70 formed later is affected by the deformation of the recording paper P due to the ink absorption of the ruled line adjustment pattern 70 formed earlier. Therefore, by forming the ruled line adjustment pattern 70 corresponding to the high scanning speed on the recording paper P before the ruled line adjustment pattern 70 corresponding to the scanning speed slower than the ruled line adjustment pattern 70, the recording paper P is fixed. The higher the scanning speed at which the deviation of the landing position is likely to be larger while transporting in the direction, the more accurate adjustment can be made.

  Further, in the present embodiment, the pattern forming unit 55 forms a plurality of marks 71 belonging to one ruled line adjustment pattern 70 side by side in the transport direction, but may be formed side by side in the scanning direction (Modification 2). ). An example of this will be described with reference to FIG. FIG. 10 is a plan view of a recording sheet on which a ruled line adjustment pattern according to Modification 2 is formed. Here, for simplicity of explanation, the number of marks 71 belonging to one ruled line adjustment pattern 70 is reduced.

  For example, as shown in FIG. 10, first, among the four ruled line adjustment patterns 70 corresponding to the four modes, the print area of the ruled line adjustment pattern 70 a corresponding to the fastest scanning speed is conveyed by the conveyance mechanism 4. The paper P includes a region overlapping with the plurality of spurs 86 constituting the sparse portion 87b in the transport direction, and does not include a line that is equidistant from the spur 86 and the adjacent spur 86 and extends in the transport direction. All the marks 71a to 71g belonging to the ruled line adjustment pattern 70a are formed in one row along the scanning direction. The remaining ruled line adjustment pattern 70 is formed at the fastest scanning speed while shifting the position in the transport direction so that the ruled line adjustment pattern 70 corresponding to the slow scan speed is formed on the upstream side in the transport direction of the recording paper P. Similarly to the corresponding ruled line adjustment pattern 70a, it is formed in one row along the scanning direction.

  According to this, compared with the above-described embodiment, the number of scans of the ink-jet head 3 at a position related to a predetermined conveyance direction of the recording paper P is reduced (specifically, four times in the embodiment and in the second modification example). The time required for ruled line adjustment can be shortened.

  Further, in the present embodiment, the printing area of all the ruled line adjustment patterns 70 includes an area that overlaps the spur 86 constituting the sparse part 87b in the transport direction, and is equidistant from the spur 86 and the adjacent spur 86. Although all the ruled line adjustment patterns 70 are formed so as not to include lines extending in the transport direction, the print areas of all the ruled line adjustment patterns 70 overlap with the spurs 86 constituting the dense portion 87a in the transport direction. All ruled line adjustment patterns 70 may be formed so as not to include a line that includes a region and is equidistant from the spur 86 and the adjacent spur 86 and extending in the transport direction.

  In the present embodiment, the printing area of all the ruled line adjustment patterns 70 includes an area that overlaps the spur 86 with respect to the transport direction, and is equidistant from the spur 86 and the adjacent spur 86 and extends in the transport direction. All the ruled line adjustment patterns 70 are formed so as not to include lines, but only the printing area of some of the ruled line adjustment patterns 70 out of all the ruled line adjustment patterns 70 has an area overlapping with the spur 86 in the transport direction. A part of the ruled line adjustment patterns 70 of all the ruled line adjustment patterns 70 may be formed so as not to include a line that is equidistant from the spur 86 and the adjacent spur 86 and extends in the transport direction. .

  Further, in the present embodiment, four ruled line adjustment patterns 70 having different scanning speeds are scanned at the same position in the transport direction of the recording paper P, and the inkjet head 3 is reciprocated at each scanning speed for a total of four reciprocations. Although formed, the four ruled line adjustment patterns 70 may be formed by varying the scanning speed during one reciprocation.

  Furthermore, in this embodiment, the ink ejection timing during forward scanning is fixed, the ink ejection timing during backward scanning is shifted by a predetermined timing, and the ruled line adjustment pattern 70 composed of seven marks 71a to 71g is formed. However, the ink ejection timing during the backward scanning may be fixed and the ink ejection timing during the forward scanning may be shifted by a predetermined timing, or both ink ejection timings may be shifted.

  The number of ruled line adjustment patterns 70 may be increased or decreased in accordance with the number of modes (scanning speed for scanning). Also, the number of marks 71 belonging to one ruled line adjustment pattern 70 may be increased or decreased as appropriate. In addition, although the user looks at the mark and determines the deviation of the landing position, the mark may be read by an optical sensor and automatically determined. At this time, the number of marks to be formed may be one as long as the sensor is accurate enough to determine the absolute amount of landing position deviation without comparing a plurality of patterns.

  Further, in the present embodiment, all the ruled line adjustment patterns 70 are formed on one sheet of recording paper P. However, when it is desired to form each ruled line adjustment pattern 70 large, a plurality of recording sheets P are formed. It may be formed separately. At this time, if one ruled line adjustment pattern 70 is formed on each recording sheet P, the order in which the plurality of ruled line adjustment patterns 70 are formed without considering the ink absorption at the time of forming the other ruled line adjustment patterns 70. Don't have to worry.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Carriage 3 Inkjet head 4 Conveyance mechanism 6, 7 Guide shaft 9 Endless belt 15 Nozzle 50 Control device 51 Head control part 52 Conveyance control part 53 Carriage control part 55 Pattern formation part 70 Ruled line adjustment pattern 86 Spur

Claims (7)

An inkjet head having a nozzle for ejecting ink;
Scanning means for reciprocatingly scanning the inkjet head in a predetermined scanning direction;
A plurality of holding portions that are arranged at intervals in the scanning direction and hold the recording medium so as to be able to be conveyed, and the recording medium is arranged in a conveying direction perpendicular to the scanning direction with respect to the inkjet head. Conveying means for conveying;
An ink jet recording apparatus comprising: a control means for controlling the ink jet head, the scanning means, and the transport means to perform recording on the recording medium,
The control means ejects ink to the recording medium when the ink jet head is moved backward and when moved backward, so that the landing position in the forward scanning and the landing position in the backward scanning are determined. Pattern forming means for forming one or more patterns including at least one mark for detecting a relative displacement in the scanning direction on the recording medium conveyed by the conveying means;
The pattern forming means includes a region in which a print area of all the marks belonging to at least one pattern among the one or more patterns overlaps with one clamping part of the plurality of clamping parts in the transport direction. An ink jet recording apparatus, wherein the pattern is formed so as not to include a line that is equidistant from a portion and a sandwiching portion adjacent thereto and extends in the transport direction. Among the plurality of sandwiching portions, some of the sandwiching portions constitute a dense portion arranged at an interval smaller than a predetermined interval, and the remaining sandwiching portions are adjacent to the dense portion and are equal to or greater than the predetermined interval. Consists of sparse parts arranged at intervals,
The pattern forming means includes a region in which a printing area of all the marks belonging to at least one pattern among the one or more patterns overlaps with the sandwiching part constituting the sparse part and the transport direction, and the sandwiching part 2. The inkjet recording apparatus according to claim 1, wherein the pattern is formed so as not to include a line that is equidistant from the adjacent sandwiching portion and extends in the transport direction. The control means selects one of a plurality of preset scanning speeds, and controls the scanning means to move the inkjet head at the selected scanning speed,
The pattern forming means includes
Forming a plurality of the patterns corresponding to the plurality of types of scanning speeds on one recording medium;
At least a printing area of all the marks belonging to the pattern corresponding to the fastest scanning speed includes an area that overlaps the sandwiching part constituting the sparse part and the transport direction, and the sandwiching part and the sandwiching part adjacent thereto. The inkjet recording apparatus according to claim 2, wherein the pattern is formed so as not to include a line that is equidistant from the portion and extends in the transport direction.   The pattern forming unit forms the plurality of patterns on the recording medium in order of decreasing scanning speed from the pattern corresponding to the fastest scanning speed. Inkjet recording device. The pattern forming means includes
Forming the plurality of patterns by shifting in the transport direction;
The inkjet recording apparatus according to claim 4, wherein among the plurality of patterns, the pattern corresponding to a slow scanning speed is formed on the upstream side in the transport direction of the recording medium. The pattern includes a plurality of marks having different ink ejection timings during backward scanning with respect to ink ejection timing during forward scanning of the inkjet head,
The pattern forming unit forms the pattern so that the plurality of marks are arranged in a line in the transport direction of the recording medium transported by the transport unit. The inkjet recording apparatus according to any one of 5. The pattern forming unit includes: a printing unit for printing all the marks belonging to at least one of the one or more patterns in the conveyance direction and the clamping unit that clamps the recording medium on the outermost side in the scanning direction. 7. The pattern according to claim 1, wherein the pattern is formed so as to include an overlapping region and not include a line that is equidistant from the sandwiching portion and the sandwiching portion adjacent to the sandwiching portion and extends in the transport direction. 2. An ink jet recording apparatus according to item 1.

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