JP5287819B2 - 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 apparatuses described in Patent Documents 1 and 2, intermittent conveyance operation along the conveyance direction of the recording medium and reciprocation of the recording head along the scanning direction orthogonal to the conveyance direction are repeated alternately. Ink is ejected at the time of scanning in both directions, i.e., when the recording head is moved forward and backward, and a recording operation (bidirectional printing) is performed.

  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, until the ink is ejected from the nozzle and landed, the ink also flies in the scanning direction due to the inertia of the movement of the recording head. Therefore, the actual ink ejection takes the scanning speed of the recording head and the ink flying time (ink speed and recording time). The landing positions can theoretically be made uniform by performing timing at a predetermined distance before the dot formation position, which is obtained from the gap between the head and the recording medium.

  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 position (timing) determined as described above during forward scanning and backward scanning, a slight landing position deviation occurs. For this reason, it is necessary to adjust the ejection timing during forward scanning and backward scanning.

  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 a minimum amount of landing position deviation is detected and adjusted to the ink ejection timing during the forward scanning of the recording head and the ink ejection timing during the backward scanning at the time of pattern formation, and the scanning direction is adjusted. The relative displacement of the landing position is eliminated. Further, in the ink jet recording apparatus described in Patent Document 2, such a pattern is formed on both sides of the recording medium in the scanning direction in order to perform landing correction for the gaps at the left and right ends of the platen.

JP 2009-196367 A Japanese Patent Laying-Open No. 2006-167995 (FIG. 1)

  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. The undulation of this recording medium increases as the ambient humidity increases. Even if the ambient humidity is the same, the undulation of multiple recording media is not uniform, and varies depending on the recording medium. It is.

  When attempting to form a pattern on a recording medium having such a variation in the undulation, the area of the recording medium on which the pattern is formed may or may not be lifted. Even so, the floating height varies, and the gap between the inkjet head and the recording medium 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. Even if a pattern is formed and adjusted on a recording medium having such a variation in undulation, the adjustment is not correct.

  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 conveyance unit that conveys the recording medium in a conveyance direction orthogonal to the scanning direction, and controls the inkjet head, the scanning unit, and the conveyance unit. An ink jet recording apparatus comprising: a control unit configured to perform recording on the recording medium, wherein the control unit performs the recording when the ink jet head is scanned forward and backward. Each ink is ejected onto the medium, and the relative position of the landing position in the forward scanning and the landing position in the backward scanning with respect to the scanning direction is determined. Pattern forming means for forming one or more patterns including at least one mark for detecting misalignment, wherein the pattern forming means includes the recording medium of the recording medium conveyed by the conveying means. At least a part of the mark is formed for each of the marks belonging to at least one of the one or more patterns in a region further outside the clamping portion that clamps the medium on the outermost side in the scanning direction.

  The recording medium may be deformed into a wavy shape due to the influence of ambient humidity. However, the recording medium transported by the transporting unit is sandwiched between the recording media on the outermost side in the scanning direction. The region outside the portion has a free end at the end, can extend along the scanning direction, does not float up, and has a stable gap with the inkjet head. According to the ink jet recording apparatus of the present invention, a pattern is formed in a region where the waviness of the recording medium having a stable gap with the ink jet head is small, so that the adjustment can be performed with high accuracy regardless of the influence of ambient humidity and the like. Can do.

  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 transporting at least the pattern corresponding to the fastest scanning speed by the transport unit. It is preferable that the recording medium is formed in the outer region in the scanning direction.

  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. In other words, the higher the scanning speed, the greater the displacement of the landing position for the same gap variation. Therefore, by forming a pattern corresponding to the fastest scanning speed among a plurality of patterns in the outer area in the scanning direction of the recording medium, all the patterns are temporarily arranged in the outer area in the scanning direction of the recording medium. Even when there is no region in which the position can be formed, it is possible to preferentially perform high-precision adjustment at the fastest scanning speed at which landing position deviation tends to be large.

  At this time, the pattern forming unit applies the pattern corresponding to the fastest scanning speed among the plurality of patterns to one outer region in the scanning direction of the recording medium transported by the transport unit. Forming the pattern corresponding to the second fastest scanning speed, and having the same position in the transport direction as the pattern corresponding to the fastest scan speed and transported by the transport means Preferably, the medium is formed in the other outer region in the scanning direction of the medium.

  According to this, among the plurality of patterns, two patterns corresponding to the upper two scanning speeds with the higher scanning speed are the same in the position in the transport direction of the recording medium, and the most both in the scanning direction. By forming each on the outer side, it is possible to preferentially adjust with high accuracy at the upper two scanning speeds at which landing position deviations tend to be large.

  Further, 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.

At this time, the pattern forming unit forms the plurality of patterns by shifting in the transport direction, and among the plurality of patterns, the pattern corresponding to a slow scanning speed is upstream of the recording medium in the transport direction. It is preferable to form.

  According to this, it is possible to form a pattern corresponding to a high scanning speed on the recording medium first while conveying the recording medium in a fixed direction.

  The pattern includes a plurality of marks arranged in a line in the transport direction by relatively shifting the ink ejection timing during the backward scanning relative to the ink ejection timing during the forward scanning of the inkjet head by a predetermined timing. Preferably it consists of.

  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.

  Further, it is preferable that the transport unit has a contact portion that is disposed in the outer region, faces a surface of the recording medium facing the inkjet head, and can contact the recording medium.

  If the recording medium is prevented from floating by bringing the recording medium into contact with the contact portion in an area outside the clamping portion that clamps the recording medium on the outermost side in the scanning direction, it is opposite to the clamping portion of the recording medium. Since the end on the side is a free end, the recording medium can be pushed down and flattened, and the gap with the inkjet head can be further stabilized.

  Further, it is preferable that the pattern forming unit forms the pattern in a region overlapping with the outermost holding portion in the transport direction in addition to the outer region.

  The gap between the recording medium and the inkjet head is also relatively stable in the area facing the inkjet head and overlapping the sandwiching portion in the transport direction. Therefore, by forming a pattern in a region that overlaps the sandwiching unit and the transport direction in addition to a region further outside the sandwiching unit that sandwiches the recording medium on the outermost side in the scanning direction, a region where the pattern is formed becomes large. Therefore, it becomes easy to form a large pattern. Then, for example, it becomes easy for the user to visually recognize the pattern.

  By forming a pattern in a region where the waviness of the recording medium having a stable gap with the inkjet head is small, high-precision adjustment can be performed regardless of the influence of ambient humidity and the like.

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. FIG. 6 is a schematic front view for explaining the undulation in a region facing the inkjet head of the recording paper. FIG. 9 is a plan view of a recording sheet on which a ruled line adjustment pattern is formed, in which (a) is Modification 1 and (b) is Modification 2. FIG. FIG. 10 is a plan view of a recording sheet on which a ruled line adjustment pattern according to Modification 3 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 ink jet printer 1 (ink jet recording apparatus) includes a carriage 2 configured to reciprocate along a predetermined scanning direction (a direction perpendicular to the paper surface of FIG. 1), and is mounted on the carriage 2. The inkjet head 3, the conveyance mechanism 4 that conveys the recording paper P along the paper conveyance path 5 (shown by a one-dot chain line in FIG. 1) positioned below the inkjet head 3, and the operation of each part. A control device 50 for controlling the overall operation is included.

  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) and ejects ink in the ink flow path of the stored flow path unit from a plurality of nozzles 15 by a piezoelectric actuator. A plurality of nozzles 15 are arranged side by side in the transport direction (left 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 among 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 and 87. 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 spurs 86 and 87 are arranged at intervals in the scanning direction. Among the plurality of spurs 86, 87, the plurality of spurs 86 disposed to face the plurality of rubber members 84 of the paper discharge roller 14 sandwich the recording paper P with the rubber member 84, and each record independently. It is configured to be elastically displaceable in a direction away from the paper P. Further, the remaining spurs 87 are respectively arranged at positions slightly higher than the spurs 86 between the plurality of spurs 86, facing the surface on which images, characters, and the like of the recording paper P are recorded. It is configured to be prevented from being displaced in a direction away from the recording paper P by restricting contact and floating upward. 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 (downward in FIG. 1) between the main roller pair 10 and the paper discharge roller pair 13 in the transport direction, and the ink ejection surface A plurality of ribs (not shown) are formed on the upper surface facing 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 print quality decreases as the scanning speed of the inkjet head 3 increases 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, the ink-jet head 3, the paper feed motor 61, the main motor 62, the paper discharge motor 63, and the carriage drive motor 64 are controlled so that the ruled line adjustment pattern 70 is applied to the recording paper P conveyed by the conveyance mechanism 4 (see FIG. 5). Form. 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 at the same position on the recording paper P during reciprocating scanning and backward scanning, ink ejection timing (scanning) from the inkjet head 3 during forward scanning and backward scanning is used. It is necessary to change the injection position).

  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 to be adjusted, for example, in a low humidity or high humidity environment. However, it 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 the raised area of the recording paper P every time the adjustment is made, or is lifted. For example, the gap between the inkjet head 3 and the recording paper P varies, and the landing position in the scanning direction varies. Thus, even if the ruled line adjustment pattern 70 is formed and adjusted on the recording paper P having a variation in the undulation, the landing position in the scanning direction varies and does not adjust correctly.

  Therefore, in the present embodiment, as shown in FIG. 7, the pattern forming unit 55 overlaps the spur 86 that holds the recording paper P on the outermost side in the scanning direction of the recording paper P transported by the transport mechanism 4. A ruled line adjustment pattern 70 is formed in a region X2 further outside X1 and the spur 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.

  Here, a description will be given with reference to FIG. 8 of the undulation of the area of the recording paper P facing the inkjet head 3 when the undulating recording paper P is conveyed by the conveyance mechanism 4. FIG. 8 is a front view for explaining the undulation in the region of the recording paper facing the inkjet head. In FIG. 8, a portion that overlaps the sandwiched portion of the spur 86 and the rubber member 84 in the transport direction is indicated by a black point, and a portion that overlaps a contact portion that the spur 87 contacts and the transport direction is indicated by a white point. In order to simplify the explanation, the number of black spots and white spots is reduced.

  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.

  As shown in FIG. 8, the black spot portion of the area of the recording paper P facing the ink jet head 3 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. Then, the raised portion of the area of the recording paper P facing the ink jet head 3 is restricted by a white point to suppress the floating. However, since there is no escape for the stretched part, the part sandwiched between the black and white spots will float.

  On the other hand, in the area of the recording paper P facing the inkjet head 3, the black dot portion corresponding to the spur 86 that sandwiches the recording paper P on the outermost side in the scanning direction cannot be sandwiched and extended. One of the extending portions is a free end and can be freely extended along the scanning direction, and is difficult to lift. That is, in the region X2 outside the spur 86 that holds the recording paper P on the outermost side in the scanning direction of the recording paper P transported by the transport mechanism 4, the gap with the inkjet head is stable.

  In the black and white spots shown in FIG. 8, the floating of the recording paper P is suppressed to some extent. However, since the floating of the white dot portion is originally restricted only slightly above the surface of the recording paper P, the floating of the recording paper P cannot be completely suppressed. Further, the black dot portion does not lift if the force that the recording paper P is about to rise is smaller than the pressing elastic force of the spur 86, but it rises if the force that the recording paper P is about to rise is large. There is a case. In particular, in the spurs 86 other than the outermost spur 86, the recording paper P tends to float on both sides, so that it is more likely to float than the outermost spur 86. Further, the effect of suppressing the lifting of the recording paper P to some extent at the spurs 86 and 87 indicated by the black and white dots becomes smaller as the distance from the spurs 86 and 87 in the transport direction decreases, so that the recording paper P faces the inkjet head 3. Even in the region, the recording paper P is lifted even at a position on an extension line of the spurs 86 and 87 in the conveying direction.

  When the recording paper P is not wavy, the gap with the ink jet head is naturally stable in any region, and the recording paper P of the recording paper P conveyed by the conveyance mechanism 4 is the most in the scanning direction. It can be said that the region X1 of the spur 86 sandwiched on the outside and the region X2 further outside the spur 86 are regions where the gap with the inkjet head is always stable regardless of the undulation of the recording paper P.

  Therefore, in the present embodiment, the pattern forming unit 55 is located above the region X1 of the recording paper P conveyed by the conveyance mechanism 4 and the spur 86 that overlaps the spur 86 holding the recording paper P on the outermost side in the scanning direction. Further, a ruled line adjustment pattern 70 is formed in the outer area X2.

  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.

  Therefore, among the four ruled line adjustment patterns 70 corresponding to the four modes, the ruled line adjustment pattern 70a corresponding to the fastest scanning speed is set to one outer region X2 in the scanning direction of the recording paper P conveyed by the conveyance mechanism 4. Further, the ruled line adjustment pattern 70b corresponding to the second fastest scanning speed has the same position in the conveyance direction as the ruled line adjustment pattern 70a and the scanning direction of the recording paper P conveyed by the conveyance mechanism 4 Is formed in the other outer region X2.

  Then, the remaining two ruled line adjustment patterns 70c and 70d are in the area X1 and the area X2 and have the same position in the conveyance direction as the ruled line adjustment pattern 70a and are inside the ruled line adjustment patterns 70a and 70b. To form.

  According to the ink jet printer 1 of the present embodiment, the region X2 outside the spur 86 of the recording paper P transported by the transport mechanism 4 from the spur 86 that sandwiches the recording paper P on the outermost side in the scanning direction, as described above. The gap with the head 3 is stable. By forming the ruled line adjustment pattern 70 in the region of the recording paper P where the distance from the inkjet head 3 is stable, it is possible to perform highly accurate adjustment regardless of the influence of ambient humidity or the like. 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, by forming the ruled line adjustment pattern 70a corresponding to the fastest scanning speed among the plurality of ruled line adjustment patterns 70a to 70d in the outermost region in the scanning direction of the recording paper P, as in the present embodiment, Even when there is no area in which all the ruled line adjustment patterns 70a to 70d can be formed in the outer area X2 in the scanning direction of the recording paper P, the accuracy is preferentially given at the fastest scanning speed at which landing position deviation tends to be large. High adjustment can be made. Further, among the plurality of ruled line adjustment patterns 70a to 70d, the ruled line adjustment pattern 70b corresponding to the next highest scanning speed is the same as the ruled line adjustment pattern 70a on the recording paper P in the transport direction, and By forming it in the outermost region opposite to the scanning direction, it is possible to preferentially adjust with high precision at the top two scanning velocities in which landing position deviations tend to be large.

  Further, when the spur 87 is brought into contact with the recording paper P in the region X2 outside the spur 86 that sandwiches the recording paper P on the outermost side in the scanning direction, the spur 86 of the recording paper P is prevented from rising. Since the end on the opposite side is a free end, the recording paper P can be pushed down and flattened. Therefore, the gap with the inkjet head is further stabilized.

  Further, the area X1 of the recording paper P facing the ink jet head 3 and overlapping the spur 86 in the transport direction has a small width in the scanning direction, but the gap with the ink jet head 3 is stable like the area X2. Therefore, by forming the ruled line adjustment pattern 70 in the area X1 and the area X2 of the recording paper P, the area in which the ruled line adjustment pattern 70 is formed becomes large, and it becomes easy to form a large ruled line adjustment pattern 70. Then, for example, it becomes easy for the user to visually recognize the ruled line adjustment pattern 70.

  Further, since the ink has landed on the recording paper P on the downstream side in the transport direction from the ink jet head 3, the surface of the recording paper P on which the ink is landed is in contact with the spur 86 so that the ink does not adhere. It is preferable to carry. Since the spurs 86 are not densely arranged over the entire scanning direction of the recording paper P but are arranged at intervals, the spurs 86 are located outside the spur 86 that restrains the recording paper P on the outermost side in the scanning direction. The width of the region that can extend along the scanning direction and has a stable gap with the inkjet head can be secured to some extent.

  Further, even if the ruled line adjustment pattern 70 is formed by conveying the longitudinal direction of the recording paper P, which is a horizontal sheet, in parallel with the conveying direction, the gap between the area X1 and the area X2 with the inkjet head is stable. Therefore, it is possible to detect the positional deviation stably regardless of what type of recording paper P is used.

  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.

  In the present embodiment, the pattern forming unit 55 is further outside the region X1 and the spur 86 that overlap the spur 86 that sandwiches the recording paper P on the outermost side in the scanning direction of the recording paper P transported by the transport mechanism 4. Although the ruled line adjustment pattern 70 is formed in the region X2, it may be formed only in the region X2. An arrangement example of the ruled line adjustment pattern 70 in the case of forming in this way will be described below. FIG. 9 is a plan view of a recording sheet on which a ruled line adjustment pattern according to a modification is formed. (A) is Modification 1 and (b) is Modification 2. FIG.

  For example, as shown in FIG. 9A, first, among the four ruled line adjustment patterns 70 corresponding to the four modes, the ruled line adjustment pattern 70a corresponding to the fastest scanning speed is conveyed by the conveyance mechanism 4. The ruled line adjustment pattern 70b corresponding to the second fastest scanning speed is formed in one outer region X2 in the scanning direction of the paper P, and the position in the conveyance direction is the same as the ruled line adjustment pattern 70a. It is formed in the other outer region X2 in the scanning direction of the recording paper P conveyed by the mechanism 4.

  Thereafter, the position in the transport direction is shifted to correspond to the third fastest scanning speed among the four ruled line adjustment patterns 70 corresponding to the four modes on the upstream side of the ruled line adjustment patterns 70a and 70 in the transport direction. A ruled line adjustment pattern 70c is formed in one outer region X2 in the scanning direction of the recording paper P conveyed by the conveyance mechanism 4, and a ruled line adjustment pattern 70d corresponding to the slowest scanning speed is defined as a ruled line adjustment pattern 70c. The positions in the transport direction are the same and are formed in the other outer region X2 in the scanning direction of the recording paper P transported by the transport mechanism 4 (Modification 1).

  Further, as shown in FIG. 9B, a plurality of ruled line adjustment patterns 70 are formed shifted in the transport direction, and the ruled line adjustment pattern 70 corresponding to the slower scanning speed among the plurality of ruled line adjustment patterns 70 is recorded on the recording paper P. Is formed on the upstream side in the conveying direction (Modification 2). At this time, as shown in FIG. 9B, the plurality of ruled line adjustment patterns 70 may be formed in one row along the transport direction, or may be formed 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.

  In the present embodiment, the pattern forming unit 55 further includes the region X1 and the spur 86 that overlap the spur 86 that sandwiches the recording paper P on the outermost side in the scanning direction of the recording paper P transported by the transport mechanism 4. Although all the ruled line adjustment patterns 70 are formed in the outer region X2, when there is no space where all the ruled line adjustment patterns 70 can be formed, the landing position shift is likely to be large and the scanning speed is high. The corresponding ruled line adjustment pattern 70 may be formed preferentially in the region X1 and the region X2, and the remaining ruled line adjustment pattern 70 may be formed inside the region X1 (Modification 3). For example, as shown in FIG. 10, among the four ruled line adjustment patterns 70 corresponding to the four modes, a ruled line adjustment pattern 70a corresponding to the fastest scanning speed and a ruled line adjustment pattern 70b corresponding to the second fastest scanning speed are provided. The ruled line adjustment pattern 70c corresponding to the third fastest scanning speed and the ruled line adjustment pattern 70d corresponding to the slowest scanning speed are formed inside the area X1. According to this, each ruled line adjustment pattern 70 can be easily formed large and easily visible.

  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 unit 52 Conveyance control unit 53 Carriage control unit 55 Pattern formation unit 70 Ruled line adjustment pattern

Claims (8)

An inkjet head having a nozzle for ejecting ink;
Scanning means for reciprocatingly scanning the inkjet head in a predetermined scanning direction;
A transport unit that is arranged at intervals in the scanning direction and has a plurality of sandwiching units that can transport the recording medium so as to be transported, and transports the recording medium in a transporting direction perpendicular to the scanning direction;
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 with respect to the scanning direction;
The pattern forming unit includes the one or more patterns on the recording medium conveyed by the conveying unit in a region further outside the clamping unit that clamps the recording medium on the outermost side in the scanning direction. An ink jet recording apparatus, wherein at least a part of the mark is formed for each of the marks belonging to at least one pattern. 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;
2. The ink jet recording apparatus according to claim 1, wherein at least the pattern corresponding to the fastest scanning speed is formed in the outer region in the scanning direction of the recording medium transported by the transporting unit. .   The pattern forming unit forms the pattern corresponding to the fastest scanning speed among the plurality of patterns in one outer region in the scanning direction of the recording medium transported by the transport unit, Further, the pattern corresponding to the second fastest scanning speed is the same as the pattern corresponding to the fastest scanning speed in the position in the transport direction, and the recording medium transported by the transport unit is the same. The inkjet recording apparatus according to claim 2, wherein the inkjet recording apparatus is formed in the other outer region in the scanning direction.   The pattern forming unit forms the plurality of patterns on the recording medium in an order of decreasing scanning speed from the pattern corresponding to the fastest scanning speed. The ink jet recording apparatus described. 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 is composed of a plurality of marks arranged in a line in the transport direction, with the ink jet timing of the ink jet head relative to the ink ejection timing during forward scanning being shifted relative to the ink ejection timing by a predetermined timing. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is an ink jet recording apparatus.   2. The conveying unit according to claim 1, further comprising a contact portion that is disposed in the outer region, faces a surface of the recording medium facing the ink jet head, and can contact the recording medium. The ink jet recording apparatus according to any one of 1 to 6. 8. The pattern forming unit according to claim 1, wherein the pattern forming unit forms the pattern in a region overlapping with the outermost clamping unit in the transport direction in addition to the outer region. The ink jet recording apparatus described.

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