printer

Abstract

It provides a more visible bidirectional adjustment pattern. [Solution] The printer prints a bidirectional adjustment pattern 200 on the recording medium 5 to correct the deviation in the ink landing position with respect to the scanning direction Y between forward printing, in which ink is ejected from the ink head while the ink head is moved in the Y1 direction, and return printing, in which ink is ejected from the ink head while the ink head is moved in the Y2 direction. The bidirectional adjustment pattern 200 includes a plurality of adjustment patterns 201, each with a different correction value set and arranged in the scanning direction Y. Each adjustment pattern 201 includes a baseline 203 extending in the nozzle alignment direction X and a diagonal line 204 that is oblique to the alignment direction X, and the baseline 203 and the diagonal line 204 are arranged in the alignment direction X.

Description

Technical Field

[0001] The present invention relates to a printer.

Background Art

[0002] There has been conventionally known a printer that forms an image on a recording medium by a bidirectional printing method including forward printing in which ink is ejected from an ink head while moving the ink head in one of the scanning directions, and backward printing in which ink is ejected from the ink head while moving the ink head in the other of the scanning directions. For example, Patent Document 1 discloses an inkjet printer including a carriage slidable along a guide rail extending in the main scanning direction and a recording head mounted on the carriage, and in the process of reciprocating movement along the main scanning direction, ink is ejected toward the recording medium at a predetermined timing according to image data.

[0003] The inkjet printer described in Patent Document 1 is configured to print a landing position adjustment chart for adjusting the landing position of ink between the forward path and the backward path. Adjustment of the landing position of ink between the forward path and the backward path is performed by the user checking the landing position adjustment chart. The landing position adjustment chart is formed by ejecting ink during the movement of the recording head in the forward path and the backward path, respectively, and includes a predetermined image pattern with variously different landing positions.

[0004] Furthermore, Patent Document 1 discloses that in inkjet printers, the initial ink ejection velocity tends to decrease when there are more nozzles ejecting ink at the same time than when there are fewer nozzles ejecting ink at the same time, due to the characteristics of the ink head, cable, or drive circuit. According to Patent Document 1, since a change in the initial ink ejection velocity manifests as a change in the ink's landing position, the number of nozzles ejecting ink at the same time affects the image quality. Therefore, the inkjet printer described in Patent Document 1 is configured to perform different landing position adjustments in Mode 1, where the number of nozzles ejecting ink at the same time is relatively large, and Mode 2, where the number of nozzles ejecting ink at the same time is relatively small.

[0005] The inkjet printer described in Patent Document 1 prints a bullet impact position adjustment chart that combines an image pattern for "Mode 1" consisting of thin, straight lines parallel to the sub-scanning direction and an image pattern for "Mode 2" consisting of thin, straight lines inclined diagonally with respect to the sub-scanning direction. In this bullet impact position adjustment chart, the straight lines parallel to the sub-scanning direction and the diagonal lines inclined with respect to the sub-scanning direction are arranged to align with the main scanning direction.

[0006] According to Patent Document 1, in adjusting the impact position in Mode 1, the user selects a chart in which the positions of a straight line parallel to the sub-scanning direction in the forward path coincide with the positions of a straight line parallel to the sub-scanning direction in the return path. In adjusting the impact position in Mode 2, the user selects a chart in which the positions of a diagonal line in the forward path coincide with the positions of a diagonal line in the return path.

[0007] According to Patent Document 1, this allows for adjustment of the impact position deviation for each recording mode, and optimizes the impact position in various images using different recording modes. Furthermore, according to Patent Document 1, this impact position adjustment chart allows for simultaneous viewing of charts for multiple recording modes, thus eliminating the waste of time and recording media required to output multiple impact position adjustment charts for each recording mode. Additionally, it is stated that this improves usability for the user, as they no longer need to be aware of multiple impact position adjustment charts for each recording mode. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2007-203490 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] In the impact position adjustment chart (bidirectional adjustment pattern) disclosed in Patent Document 1, a straight line parallel to the sub-scanning direction intersects with a diagonal line inclined with respect to the sub-scanning direction, making it difficult to determine at a glance which chart to select.

[0010] This invention has been made in view of the above, and aims to provide a printer that can provide a more visible bidirectional adjustment pattern. [Means for solving the problem]

[0011] The printer disclosed herein comprises a support base for supporting a recording medium, an ink head having a nozzle row in which a plurality of nozzles, each ejecting ink toward the recording medium supported by the support base, are arranged in a predetermined direction, a moving device for moving the ink head in a scanning direction perpendicular to the direction of arrangement, and a control device for controlling the ink head and the moving device. The control device includes a pattern printing unit. The pattern printing unit controls the ink head and the moving device to print a bidirectional adjustment pattern on the recording medium for correcting the deviation of the ink landing position in the scanning direction between forward printing, in which ink is ejected from the ink head while the ink head is moved to one side of the scanning direction, and return printing, in which ink is ejected from the ink head while the ink head is moved to the other side of the scanning direction. The bidirectional adjustment pattern includes a plurality of adjustment patterns, each with a different correction value set and arranged in the scanning direction. Each adjustment pattern includes a baseline extending in the direction of arrangement and a diagonal line intersecting the direction of arrangement, and the baseline and the diagonal line are arranged in the direction of arrangement.

[0012] With the above-described printer, since the baseline and diagonal lines do not overlap, the degree of positional misalignment related to the baseline between the forward and return prints, and the degree of positional misalignment related to the diagonal lines between the forward and return prints, can be grasped at a glance from each adjustment pattern. Therefore, the printer disclosed herein can provide a more visually apparent bidirectional adjustment pattern. [Brief explanation of the drawing]

[0013] [Figure 1] This is a front view of a printer according to one embodiment. [Figure 2] This is a bottom view of the carriage. [Figure 3] This is a cross-sectional view of the vicinity of one nozzle of the ink head. [Figure 4] This is a cross-sectional view of the ink head, cut along a plane extending in the sub-scanning direction. [Figure 5] This is a block diagram of a printer. [Figure 6] This is a schematic plan view of the bidirectional adjustment pattern. [Figure 7] This is a flowchart for determining the correction value for bidirectional printing. [Figure 8] These are schematic plan views of the outbound and return routes. [Figure 9] This is a plan view showing three adjacent adjustment patterns. [Figure 10] This is a schematic plan view of an adjustment pattern relating to another embodiment. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the inkjet printer (hereinafter referred to as "printer") according to the present invention will be described with reference to the drawings. Naturally, the embodiments described herein are not intended to particularly limit the present invention. Furthermore, the same reference numerals are used for components and parts that perform the same function, and redundant explanations are omitted or simplified.

[0015] Figure 1 is a front view of a printer 10 according to one embodiment. In the following description, when viewing the printer 10 from the front, the direction away from the printer 10 is referred to as the front, and the direction towards the printer 10 is referred to as the rear. The symbols F, Rr, L, R, U, and D in the drawing represent front, rear, left, right, up, and down, respectively. The symbol X in the drawing (see Figure 2) indicates the sub-scanning direction. The sub-scanning direction X is the extension direction of the nozzle row 42, which will be described later. The sub-scanning direction X is also the transport direction of the recording medium 5. Here, the sub-scanning direction X is the front-back direction. The symbol Y indicates the main scanning direction Y which is perpendicular to the sub-scanning direction X. Here, the main scanning direction Y is the left-right direction. However, these directions are merely for the convenience of explanation and do not limit the installation configuration of the printer 10, etc.

[0016] As shown in FIG. 1, the printer 10 sequentially moves the recording medium 5 wound in a roll forward, and prints an image on the recording medium 5 by discharging ink from ink heads 40A to 40D (see FIG. 2) mounted on a carriage 30 that moves in the main scanning direction Y.

[0017] The recording medium 5 is an object on which an image is printed. The recording medium 5 is not particularly limited. The recording medium 5 may be, for example, paper such as plain paper or inkjet printing paper. The recording medium 5 may be, for example, a transparent sheet made of resin, glass, or the like. The recording medium 5 may be, for example, a sheet made of metal, rubber, or the like.

[0018] As shown in FIG. 1, the printer 10 includes a platen 15, a conveyance device 20, a carriage 30, a carriage moving device 35, a plurality of ink heads 40A to 40D (see FIG. 2), a control device 100, and an operation panel 110.

[0019] The platen 15 is an example of a support base that supports the recording medium 5. As shown in FIG. 1, the platen 15 extends in the main scanning direction Y. The recording medium 5 is placed on the platen 15. The conveyance device 20 conveys the recording medium 5 on the platen 15 in the sub-scanning direction X. The conveyance device 20 includes a grit roller 21, a pinch roller 22, and a feed motor 23 (see FIG. 5). The grit roller 21 is embedded in the platen 15. The grit roller 21 rotates in the front-rear direction under the driving force of the feed motor 23. The pinch roller 22 is provided above the grit roller 21. The pinch roller 22 is disposed at a position facing the grit roller 21. The pinch roller 22 presses the recording medium 5 from above. When the grit roller 21 rotates with the recording medium 5 sandwiched between the grit roller 21 and the pinch roller 22, the recording medium 5 is conveyed in the sub-scanning direction X.

[0020] The carriage 30 is positioned above the platen 15. The carriage 30 is equipped with multiple ink heads 40A to 40D. The carriage moving device 35 moves the multiple ink heads 40A to 40D in the main scanning direction Y by moving the carriage 30 in the main scanning direction Y. The carriage moving device 35 comprises a guide rail 36, left and right pulleys 37a and 37b, an endless belt 38, and a carriage motor 39.

[0021] The guide rail 36 extends in the main scanning direction Y. The carriage 30 is slidably engaged with the guide rail 36 in the main scanning direction Y. The pulleys 37a and 37b are provided on the left and right sides of the guide rail 36. The belt 38 is wrapped around the left and right pulleys 37a and 37b. When the carriage motor 39 is driven, one of the pulleys 37b rotates, and the belt 38 moves. As a result, the carriage 30 and the multiple ink heads 40A to 40D move along the guide rail 36 in the main scanning direction Y. In the following, the left side of the main scanning direction Y may be referred to as the forward direction Y1, and the right side as the return direction Y2.

[0022] Figure 2 is a bottom view of the carriage 30. As shown in Figure 2, the multiple ink heads 40A to 40D are provided on the lower surface of the carriage 30. Each of the multiple ink heads 40A to 40D is equipped with multiple nozzles 41 arranged in the sub-scanning direction X. Each of the multiple nozzles 41 ejects ink toward the recording medium 5 on the platen 15 (in this case, downward). In each of the ink heads 40A to 40D, the multiple nozzles 41 are arranged in the sub-scanning direction X to form a nozzle row 42. The multiple nozzles 41 are arranged in the sub-scanning direction X at a density of, for example, 300 dpi. However, the density of the nozzles 41 in each of the ink heads 40A to 40D is not particularly limited. In this embodiment, different colored inks are ejected from each of the multiple ink heads 40A to 40D. However, the inks ejected from the multiple ink heads 40A to 40D may be of the same type. In the following, unless otherwise necessary, the code 40 will be used as a general term for multiple ink heads 40A to 40D. The number of multiple ink heads 40 is not particularly limited.

[0023] Figure 3 is a cross-sectional view of the ink head 40 near one nozzle 41. Figure 4 is a cross-sectional view of the ink head 40 cut in a plane extending in the sub-scanning direction X. As shown in Figure 3, the ink head 40 comprises a hollow case 51 having a plurality of pressure chambers 53 inside which ink is stored. As shown in Figure 4, the plurality of pressure chambers 53 are aligned in the sub-scanning direction X. As shown in Figure 3, the ink head 40 comprises a plurality of diaphragms 52 mounted on the case 51 so as to partition a portion of the pressure chamber 53, and a plurality of piezoelectric elements 56 connected to each diaphragm 52. The diaphragms 52 are elastically deformable inward and outward of the pressure chamber 53. The diaphragms 52 are configured to be deformable to increase and decrease the volume of the pressure chamber 53. The diaphragms 52 are typically resin films or metal foils.

[0024] As shown in Figure 3, a common channel 58 is formed in the case 51 through which ink supplied from an ink cartridge (not shown) flows. An ink inlet 54 is formed in the case 51 through which ink flows in. The ink inlet 54 only needs to be in communication with the pressure chamber 53, and its position is not limited in any way. The ink inlet 54 is formed between the common channel 58 and the pressure chamber 53. Ink is supplied to the pressure chamber 53 from the common channel 58 through the ink inlet 54, and a predetermined amount of ink is temporarily stored there. The ink that flows into the pressure chamber 53 through the ink inlet 54 is guided to the nozzle 41. As shown in Figure 4, the nozzles 41 are each formed on the lower surface 51B of the case 51. Each nozzle 41 is in communication with the pressure chamber 53. The nozzles 41 eject ink toward the recording medium 5.

[0025] As shown in Figure 3, the piezoelectric element 56 is connected to the side of the diaphragm 52 opposite to the pressure chamber 53 side (in this case, the top surface). The piezoelectric element 56 is connected to the control device 100 via a flexible cable (not shown). An electrical signal is supplied to the piezoelectric element 56 via the flexible cable. When the piezoelectric element 56 receives an electrical signal from the control device 100, it expands or contracts, causing the diaphragm 52 to elastically deform outwards or inwards of the pressure chamber 53. The piezoelectric element 56 is, for example, a longitudinal vibration mode piezoelectric element (PZT). A longitudinal vibration mode PZT is expandable and contractible in the stacking direction, for example, it contracts when discharged and expands when charged. However, the type of piezoelectric element 56 is not particularly limited.

[0026] In the ink head 40, for example, by lowering the potential of the piezoelectric element 56 from the reference potential, the piezoelectric element 56 contracts. In response, the diaphragm 52 elastically deforms outward from its initial position, causing the pressure chamber 53 to expand. The expansion of the pressure chamber 53 means that the volume of the pressure chamber 53 increases due to the deformation of the diaphragm 52. Next, by raising the potential of the piezoelectric element 56, the piezoelectric element 56 stretches in the stacking direction. As a result, the diaphragm 52 elastically deforms inward, causing the pressure chamber 53 to contract. The contraction of the pressure chamber 53 means that the volume of the pressure chamber 53 decreases due to the deformation of the diaphragm 52. Due to this expansion and contraction of the pressure chamber 53, the pressure inside the pressure chamber 53 fluctuates. This pressure fluctuation inside the pressure chamber 53 pressurizes the ink inside the pressure chamber 53, causing it to be ejected as ink droplets from the nozzle 41. Subsequently, by returning the potential of the piezoelectric element 56 to the reference potential, the diaphragm 52 returns to its initial position and the pressure chamber 53 expands. At this time, ink flows into the pressure chamber 53 from the ink inlet 54.

[0027] As shown in Figure 1, the control panel 110 is located on the front of the printer 10. The control panel 110 includes a display unit for showing the device status and input keys operated by the user. The control device 100 is housed inside the control panel 110.

[0028] Figure 5 is a block diagram of the printer 10. As shown in Figure 5, the control device 100 is connected to the feed motor 23 of the transport device 20, the carriage motor 39 of the carriage moving device 35, and the piezoelectric element 56 of the ink head 40. The control device 100 controls the operation of these devices. The control device 100 is typically a computer. The control device 100 includes, for example, an interface (I / F) for receiving print data from external devices such as a host computer, a central processing unit (CPU) for executing instructions of the control program, a ROM for storing programs executed by the CPU, RAM used as a working area for expanding the program, and a storage device such as memory for storing the program and various data.

[0029] As shown in Figure 5, the control device 100 includes a drive signal generation unit 101, a drive signal supply unit 102, an image printing unit 103, an adjustment pattern printing unit 104, a correction value input unit 105, and a correction unit 106. The functions of each part of the control device 100 are realized by a program. This program may be read from a recording medium such as a CD or DVD. This program may also be downloaded via the Internet. The functions of each part of the control device 100 may also be realized by a processor and / or circuits.

[0030] The drive signal generation unit 101 generates a drive signal for driving the ink head 40 at each drive cycle. The drive signal includes one or more drive pulses.

[0031] The drive signal supply unit 102 supplies part or all of the drive signals generated by the drive signal generation unit 101 to each piezoelectric element 56, causing ink to be ejected from the nozzles 41 of the ink head 40. The drive signal supply unit 102 can change the amount of ink ejected from the nozzles 41 of the ink head 40 during one drive cycle by appropriately selecting the drive pulses of the drive signals supplied to the piezoelectric elements 56.

[0032] The image printing unit 103 controls the feed motor 23, carriage motor 39, and ink head 40 to print an image on the recording medium 5. The image printing unit 103 is configured to print images based on input image data in bidirectional printing. In bidirectional printing, both forward printing is performed, in which ink is ejected from the ink head 40 while moving the ink head 40 in the forward direction Y1, which is one of the main scanning directions Y, and return printing is performed, in which ink is ejected from the ink head 40 while moving the ink head 40 in the return direction Y2, which is the other of the main scanning directions Y. Bidirectional printing allows for high-resolution printing in the main scanning direction Y in a shorter time. For example, each time either forward printing or return printing is completed, the image printing unit 103 controls the feed motor 23 to move the recording medium 5 forward (downstream in the sub-scanning direction X) and repeats this process to form an image on the recording medium 5. However, the image printing unit 103 may, for example, control the feed motor 23 to move the recording medium 5 forward (downstream in the sub-scanning direction X) each time the forward printing and return printing are completed a predetermined number of times (for example, once each).

[0033] The adjustment pattern printing unit 104 controls the ink head 40 and the carriage moving device 35 to print a bidirectional adjustment pattern 200 (see Figure 6) on the recording medium 5 to correct the misalignment of the ink landing position with respect to the main scanning direction Y between forward and return printing. During printing, the ink head 40 moves with the carriage 30 in the main scanning direction Y. Therefore, the ink landing position with respect to the main scanning direction Y differs depending on the direction of movement of the ink head 40 (forward or return printing). The amount of misalignment of the ink landing position varies depending on the thickness of the recording medium 5. The bidirectional adjustment pattern 200 is an image that allows confirmation of the amount of misalignment of the ink landing position with respect to the main scanning direction Y between forward and return printing by printing it on the recording medium 5.

[0034] Figure 6 is a schematic plan view of the bidirectional adjustment pattern 200 according to this embodiment. As shown in Figure 6, the bidirectional adjustment pattern 200 includes a plurality of adjustment patterns 201, each with a different correction value, arranged in the main scanning direction Y. In this embodiment, the bidirectional adjustment pattern 200 includes a plurality of sets of adjustment patterns 201 arranged in the main scanning direction Y. Each set corresponds to one nozzle row 42. The plurality of sets are arranged in the sub-scanning direction X. For example, in Figure 6, a plurality of adjustment patterns 201 on the rear side (four are shown in Figure 6, but generally there are many more; however, the number of adjustment patterns 201 in one set is not limited) constitute one set, and a plurality of adjustment patterns 201 on the front side (four are shown in Figure 6) constitute another set. The set of adjustment patterns 201 on the rear side consists, for example, of ink ejected from the ink head 40A. The set of adjustment patterns 201 on the front side consists, for example, of ink ejected from the ink head 40B. Other sets, not shown in the illustration, each correspond to one inkhead 40. One set is printed without transporting the recording medium 5 in the sub-scanning direction X. That is, one set is printed in one forward print and one return print, after which the recording medium 5 is transported in the sub-scanning direction X, and the next set is printed in one forward print and one return print.

[0035] As shown in Figure 6, each adjustment pattern 201 includes a forward pattern 202A printed in the forward printing and a return pattern 202B printed in the return printing. In this embodiment, a correction value is set for each of the multiple return patterns 202B. Here, the correction value is the time (offset time) that advances the ink ejection timing in the return printing. The correction value may also include the time (negative offset time) that delays the ink ejection timing in the return printing. The ink landing position may shift to the rear side in the direction of travel of the carriage 30 due to the effects of air resistance caused by the movement of the carriage 30. Therefore, a correction value that delays the ink ejection timing may also be set. The correction value may also be set for each of the multiple forward patterns 202A. In that case, the correction value is the time that advances (or delays) the ink ejection timing in the forward printing. The correction value set for the adjustment pattern 201 with the smallest positional misalignment between the forward pattern 202A and the return pattern 202B is an appropriate correction value. However, as will be explained in more detail later, in this embodiment, the amount of deviation differs depending on the location of the adjustment pattern 201. In this embodiment, the correction value differs depending on which location of the adjustment pattern 201 is minimized.

[0036] In this embodiment, the adjustment pattern printing unit 104 prints multiple adjustment patterns 201 in a set by a pair of forward and return printing passes. To achieve this, the length of the sub-scanning direction X of each adjustment pattern 201 is set to be less than or equal to the length of the sub-scanning direction X of the nozzle row 42.

[0037] As shown in Figure 6, each adjustment pattern 201 includes a baseline 203 extending in the sub-scanning direction X, which is the direction in which the nozzles 41 are aligned, and a diagonal line 204 that is oblique to the sub-scanning direction X. The baseline 203 and the diagonal line 204 are aligned in the sub-scanning direction X. Here, the baseline 203 includes a forward baseline 203F and a rearward baseline 203Rr. The diagonal line 204 includes a forward diagonal line 204F that is further rearward towards the forward direction Y1, and a rearward diagonal line 204Rr that is further rearward towards the return direction Y2. The forward diagonal line 204F is connected to the rear end of the forward baseline 203F. The rearward diagonal line 204Rr is connected to the rear end of the forward diagonal line 204F. The rearward baseline 203Rr is connected to the rear end of the rearward diagonal line 204Rr. It should be noted that "connected" means that they are ideally connected, but in reality, there is a small gap between two adjacent lines. This will be discussed later.

[0038] As shown in Figure 6, in this embodiment, the length of the front baseline 203F and the length of the rear baseline 203Rr are different. More specifically, in the forward path pattern 202A, the length of the front baseline 203F is longer than the length of the rear baseline 203Rr. In the return path pattern 202B, the length of the rear baseline 203Rr is longer than the length of the front baseline 203F. Furthermore, with respect to the front baseline 203F, the length is longer in the forward path pattern 202A than in the return path pattern 202B. With respect to the rear baseline 203Rr, the length is longer in the return path pattern 202B than in the forward path pattern 202A.

[0039] In this embodiment, the diagonal lines 204 intersect the baseline at a 45° angle (angle θ in Figure 6, see also Figure 8). Here, the diagonal lines 204 are formed by numerous ink dots aligned in the main scanning direction Y at the same pitch as the nozzle 41 in the sub-scanning direction X, and shifted in the sub-scanning direction X by the same pitch. The adjustment pattern printing unit 104 ejects ink at the same density as the nozzle 41 in the sub-scanning direction X with respect to the main scanning direction Y. In the forward printing of the diagonal lines 204F on the front side, the adjustment pattern printing unit 104 shifts the nozzle 41 ejecting ink one position backward each time the nozzle row 42 moves in the forward direction Y1 by a distance equal to the pitch of the nozzles 41. At the same position in the main scanning direction Y, there is one ink dot included in the diagonal lines 204F on the front side. During the forward printing of the rear diagonal line 204Rr, the adjustment pattern printing unit 104 shifts the nozzle 41 that ejects ink forward by one position each time the nozzle row 42 moves in the forward direction Y1 by a distance equal to the pitch of the nozzles 41. At the same position in the main scanning direction Y, there is one ink dot included in the rear diagonal line 204Rr.

[0040] Similarly, during the return printing of the front diagonal line 204F, the adjustment pattern printing unit 104 shifts the ink-emitting nozzle 41 forward by one position each time the nozzle row 42 moves in the return direction Y2 by a distance equal to the pitch of the nozzles 41. During the return printing of the rear diagonal line 204Rr, the adjustment pattern printing unit 104 shifts the ink-emitting nozzle 41 backward by one position each time the nozzle row 42 moves in the return direction Y2 by a distance equal to the pitch of the nozzles 41.

[0041] Thus, the angle of the diagonal line 204 with respect to the baseline 203 is determined by the density of ink dots in the sub-scanning direction X and the density of ink dots in the main scanning direction Y. The density of ink dots in the sub-scanning direction X and the density of ink dots in the main scanning direction Y are not particularly limited. Note that the density of ink dots in the sub-scanning direction X can be made higher than the density of the nozzles 41 by transporting the recording medium 5. Therefore, the angle of the diagonal line 204 with respect to the baseline 203 is also not limited.

[0042] However, preferably, the density of ink dots in the main scanning direction Y is greater than or equal to the density of ink dots in the sub-scanning direction X. That is, the angle θ of the diagonal line 204 with respect to the baseline 203 is preferably 45° or less. The angle θ of the diagonal line 204 with respect to the baseline 203 refers to the acute angle of the angle of the diagonal line 204 with respect to the baseline 203. By setting the angle θ of the diagonal line 204 with respect to the baseline 203 to 45° or less, the density of ink dots constituting the diagonal line 204 in the main scanning direction Y increases, and the density of the diagonal line 204 becomes darker. As a result, the visibility of the diagonal line 204 is improved. In order to increase the density of ink dots in the sub-scanning direction X, it is necessary to increase the number of passes in bidirectional printing. Therefore, increasing the density of ink dots in the sub-scanning direction X is not advantageous in terms of printing efficiency compared to increasing the density of ink dots in the main scanning direction Y.

[0043] When printing the baseline 203, the adjustment pattern printing unit 104 ejects ink from the first nozzle group 41A shown in Figure 3, among the multiple nozzles 41 of the nozzle row 42. When printing the diagonal lines 204, the adjustment pattern printing unit 104 ejects ink from the second nozzle group 41B, which is located closer to the center of the sub-scanning direction X than the first nozzle group 41A in the nozzle row 42. "Located closer to the center of the sub-scanning direction X in the nozzle row 42" means that, with respect to the sub-scanning direction X, it is located closer to the midpoint between the front end and the rear end of the nozzle row 42.

[0044] The adjustment pattern printing unit 104 prints symbols 205 representing the correction value of each adjustment pattern 201 on the extension line L1 of the baseline 203 of each adjustment pattern 201. Each symbol 205 is positioned in alignment with the corresponding adjustment pattern 201 with respect to the main scanning direction Y. Here, the symbols 205 are integers representing the order of magnitude of the correction values ​​(Figure 6 shows "14" to "17"). The larger the number in symbol 205, the larger the correction value (in this case, the larger the offset time).

[0045] However, the position of the symbol 205 representing the correction value is not particularly limited. The symbol 205 is not limited to an integer. The symbol 205 may be, for example, a real value of the offset time or offset distance. The symbol 205 may be a letter such as A, B, ...

[0046] The correction value input unit 105 receives a correction value selected based on the bidirectional adjustment pattern 200. In this embodiment, the correction value is entered by the user into the operation panel 110. The input correction value is, here, an integer shown by symbol 205. The correction value is entered for each nozzle row 42. The correction unit 106 corrects the ink landing position (timing of ink ejection) in the return print by the correction value entered into the correction value input unit 105 for each nozzle row 42.

[0047] [Procedure for determining correction values] The following describes the procedure for determining the correction value for bidirectional printing. Figure 7 is a flowchart for determining the correction value for bidirectional printing. As shown in Figure 7, in step S01 of determining the correction value for bidirectional printing, the recording medium 5 used for printing images is set in the printer 10. In step S02, the bidirectional adjustment pattern 200 is printed on the recording medium 5.

[0048] Figure 8 is a schematic plan view of the forward path pattern 202A and the return path pattern 202B. Figure 8 is an enlarged view of one of the adjustment patterns 201 in Figure 6. As shown in Figure 8, in the forward path pattern 202A, the baseline 203 is shifted in the forward direction Y1 relative to the diagonal line 204. This shift is due to the fact that the ejection speed of the ink dots forming the baseline 203 is slower than the ejection speed of the ink dots forming the diagonal line 204. As disclosed in Patent Document 1, in inkjet printers, due to the characteristics of the ink head, cable, or drive circuit, the initial ejection velocity of ink tends to decrease when there are many nozzles ejecting ink at the same timing compared to when there are few nozzles ejecting ink at the same timing. The baseline 203 extends parallel to the direction of the arrangement of nozzles 41 in the nozzle row 42. Therefore, when printing the baseline 203, there are many nozzles 41 ejecting ink at the same timing. On the other hand, when printing diagonal lines 204, the number of nozzles 41 that eject ink at the same time is small (in this case, there are two nozzles that eject ink at the same time for the front diagonal line 204F and the rear diagonal line 204Rr). As a result, the position of the ink dots that form the baseline 203 is shifted forward in the direction of movement of the carriage 30 compared to the ink dots that form the diagonal lines 204.

[0049] For the same reason, as shown in Figure 8, in the return path pattern 202B, the baseline 203 is shifted in the return path direction Y2 relative to the diagonal line 204.

[0050] In this embodiment, the adjustment pattern 201 includes a baseline 203 and a diagonal line 204. Therefore, if a correction value for the adjustment pattern 201 is selected that minimizes the misalignment of the baseline 203 between the forward path pattern 202A and the return path pattern 202B, the misalignment of the diagonal line 204 between the forward path pattern 202A and the return path pattern 202B will not be minimized. On the other hand, if a correction value for the adjustment pattern 201 is selected that minimizes the misalignment of the diagonal line 204 between the forward path pattern 202A and the return path pattern 202B, the misalignment of the baseline 203 between the forward path pattern 202A and the return path pattern 202B will not be minimized.

[0051] Figure 9 is a plan view showing three adjacent adjustment patterns 201 (labeled 201L, 201C, and 201R from left to right). In the example in Figure 9, the leftmost adjustment pattern 201L (forward direction Y1) of the three adjustment patterns 201 has the smallest positional displacement of the diagonal line 204 between the forward pattern 202A and the return pattern 202B. In the bidirectional adjustment patterns 200 shown in Figures 6 and 9, the correction value is smaller for adjustment patterns 201 to the left (forward direction Y1) and larger for adjustment patterns 201 to the right (return direction Y2). Therefore, the positional displacement of the baseline 203 between the forward pattern 202A and the return pattern 202B is smallest in any of the adjustment patterns 201 to the right (return direction Y2) of the leftmost adjustment pattern 201L in Figure 9. Here, we assume that in the rightmost of the three adjustment patterns 201 shown in Figure 9, adjustment pattern 201R (return direction Y2) has the smallest positional displacement of the baseline 203 between the forward pattern 202A and the return pattern 202B.

[0052] Returning to Figure 7, in steps S03 and S04, the user selects the elements to prioritize in bidirectional printing. Steps S03 and S04 may be performed before step S01. In step S03, the user selects whether to prioritize the sharpness of lines extending in the sub-scanning direction X. Prioritizing the sharpness of lines extending in the sub-scanning direction X is appropriate, for example, when printing images that contain frames or geometric figures with many straight lines extending in the sub-scanning direction X. If the sharpness of lines extending in the sub-scanning direction X is prioritized (if the result of step S03 is YES), in step S05A, the user selects the adjustment pattern 201 that minimizes the positional misalignment of the baseline 203 between the forward pattern 202A and the return pattern 202B. In the example shown in Figure 9, the user selects the rightmost adjustment pattern 201R.

[0053] If the sharpness of lines extending in the sub-scanning direction X is not considered important (the result of step S03 is NO), in step S04, the user selects whether to consider the sharpness of diagonal lines extending in a direction oblique to the sub-scanning direction X. Considerations for considering the sharpness of diagonal lines include, for example, printing images containing many small characters or diagonal lines, printing photographs, or improving the granularity of an image. If the sharpness of diagonal lines is considered important (the result of step S04 is YES), in step S05B, the user selects the adjustment pattern 201 with the smallest misalignment of the diagonal lines 204 between the forward pattern 202A and the return pattern 202B. In the example shown in Figure 9, the user selects the leftmost adjustment pattern 201L.

[0054] If the sharpness of the diagonal lines is not important (the result of step S04 is NO), in step S05C, the user selects one of the adjustment patterns 201 that lies between the adjustment pattern 201 with the smallest deviation of the baseline 203 and the adjustment pattern 201 with the smallest deviation of the diagonal lines 204. In the example shown in Figure 9, the user selects the central adjustment pattern 201C. This selection is made, for example, when the overall balance of the image is important. As an image, this selection is suitable when printing an image that includes a frame and small text. If there are multiple adjustment patterns 201 between the adjustment pattern 201 with the smallest deviation of the baseline 203 and the adjustment pattern 201 with the smallest deviation of the diagonal lines 204, the user may choose to slightly prioritize the baseline 203, slightly prioritize the diagonal lines 204, or give equal importance to the baseline 203 and the diagonal lines 204.

[0055] [Effects of the Embodiment] The following describes the effects and benefits that can be achieved by the printer 10 according to this embodiment.

[0056] The printer 10 according to this embodiment includes a platen 15 that supports a recording medium 5, an ink head 40 having a nozzle row 42 in which a plurality of nozzles 41 that eject ink toward the recording medium 5 supported by the platen 15 are arranged in the sub-scanning direction X, a carriage moving device 35 that moves the ink head 40 in the main scanning direction Y which is perpendicular to the sub-scanning direction X, and a control device 100 that controls the ink head 40 and the carriage moving device 35. The control device 100 includes an adjustment pattern printing unit 104. The adjustment pattern printing unit 104 controls the ink head 40 and the carriage moving device 35 to print a bidirectional adjustment pattern 200 on the recording medium 5 to correct the deviation in the ink landing position with respect to the main scanning direction Y between forward printing, in which ink is ejected from the ink head 40 while moving the ink head 40 in the forward direction Y1 which is one of the main scanning directions Y, and return printing, in which ink is ejected from the ink head 40 while moving the ink head 40 in the return direction Y2 which is the other of the main scanning directions Y. The bidirectional adjustment pattern 200 includes multiple adjustment patterns 201, each with a different correction value, arranged in the main scanning direction Y. Each adjustment pattern 201 includes a baseline 203 extending in the sub-scanning direction X and a diagonal line 204 that intersects the sub-scanning direction X, with the baseline 203 and diagonal line 204 arranged in the sub-scanning direction X.

[0057] In the printer 10 according to this embodiment, in each adjustment pattern 201, the baseline 203 and the diagonal line 204 are aligned in the sub-scanning direction X. Therefore, in each adjustment pattern 201, the degree of misalignment of the baseline 203 (here, the misalignment with respect to the main scanning direction Y between the forward pattern 202A and the return pattern 202B) and the degree of misalignment of the diagonal line 204 can be checked at a glance. For example, compared to an adjustment pattern in which the baseline and diagonal line are aligned in the main scanning direction, as described in Patent Document 1, the adjustment pattern 201 according to this embodiment has even higher visibility because the baseline 203 and the diagonal line 204 do not overlap. In the adjustment pattern described in Patent Document 1, the baseline and diagonal line intersect, making it difficult to grasp the degree of misalignment of the baseline and diagonal line at a glance. In the adjustment pattern described in Patent Document 1, it is also difficult to intuitively judge whether the correction value should be increased or decreased when looking at one adjustment pattern.

[0058] In this embodiment, the adjustment pattern printing unit 104 prints multiple adjustment patterns 201 by a pair of forward and return printing passes. With this configuration, since multiple adjustment patterns 201 can be printed by a pair of forward and return printing passes (one pass), the time required to print the bidirectional adjustment patterns 200 can be reduced.

[0059] In this embodiment, the length of the sub-scanning direction X of each adjustment pattern 201 is set to be less than or equal to the length of the sub-scanning direction X of the nozzle row 42. By using such adjustment patterns 201, it becomes possible to print multiple adjustment patterns 201 in a single pass. Therefore, it is possible to reduce the time required to print the bidirectional adjustment patterns 200.

[0060] In this embodiment, when printing the baseline 203, the adjustment pattern printing unit 104 ejects ink from the first nozzle group 41A among the multiple nozzles 41 of the nozzle row 42. When printing the diagonal lines 204, the adjustment pattern printing unit 104 ejects ink from the second nozzle group 41B, which is located closer to the center in the sub-scanning direction X than the first nozzle group 41B in the nozzle row 42. With this configuration, the diagonal lines 204 can be printed using the second nozzle group 41B on the central side, which has higher ink placement accuracy. If the ink placement accuracy is low, the diagonal lines 204 will be curved, making it difficult to accurately determine the misalignment of the diagonal lines 204. In this embodiment, by forming the diagonal lines 204 using the second nozzle group 41B on the central side, which has higher ink placement accuracy, it is made easier to determine the misalignment of the diagonal lines 204.

[0061] In this embodiment, the diagonal lines 204 intersect the baseline 203 at an angle of 45°. Preferably, the diagonal lines 204 may intersect the baseline 203 at an angle of 45° or less. By setting the angle of the diagonal lines 204 with respect to the baseline 203 to 45° or less, the density of the ink dots constituting the diagonal lines 204 in the main scanning direction Y can be increased without reducing printing efficiency (without increasing the number of passes). As a result, the density of the diagonal lines 204 becomes darker, and the visibility of the adjustment pattern 201 is improved.

[0062] In this embodiment, the baseline 203 of the forward path pattern 202A and the baseline 203 of the return path pattern 202B have different lengths in the sub-scanning direction X. Here, the front baseline 203F of the forward path pattern 202A and the corresponding front baseline 203F of the return path pattern 202B have different lengths in the sub-scanning direction X. Also, the rear baseline 203Rr of the forward path pattern 202A and the corresponding rear baseline 203Rr of the return path pattern 202B have different lengths in the sub-scanning direction X. With this adjustment pattern 201, the baseline 203 of the forward path pattern 202A and the baseline 203 of the return path pattern 202B can be easily distinguished. Therefore, it is easy to determine which of the baseline 203 of the forward path pattern 202A and the baseline 203 of the return path pattern 202B is in the forward path direction Y1 and which is in the return path direction Y2. Therefore, it is easier to determine whether the correction value for baseline 203 should be increased or decreased.

[0063] In this embodiment, the adjustment pattern printing unit 104 prints symbols 205 representing the correction value of each adjustment pattern 201 on the extension line L1 of the baseline 203 of each adjustment pattern 201. This arrangement makes the correspondence between the adjustment patterns 201 and the symbols 205 easier to understand.

[0064] [Other embodiments] Preferred embodiments of the present invention have been described above. However, the embodiments described above are merely illustrative, and the present invention can be implemented in various other forms.

[0065] For example, in the embodiment described above, the adjustment pattern 201 consisted of a front baseline 203F, a front diagonal line 204F, a rear diagonal line 204Rr, and a rear baseline 203Rr. However, the adjustment pattern 201 is not particularly limited as long as it includes one or more baselines 203 and diagonal lines 204. The adjustment pattern 201 may include three or more baselines 203 and three or more diagonal lines 204. Figure 10 is a schematic plan view of an adjustment pattern 201 according to another embodiment. As shown in Figure 10, the adjustment pattern 201 may consist of one baseline 203 and one diagonal line 204 positioned in front of or behind it. The baseline 203 and the diagonal line 204 may be positioned far apart as long as they are aligned in the sub-scanning direction X. The adjustment pattern printing unit 104 may print symbols 205 representing the correction value of each adjustment pattern 201 on the extension line L2 of the diagonal line 204 of each adjustment pattern 201. For example, if the adjustment pattern 201 is composed of one baseline 203 and one diagonal line 204, this arrangement of symbols 205 makes the correspondence between the adjustment pattern 201 and the symbols 205 easier to understand.

[0066] In the embodiment described above, multiple adjustment patterns 201 corresponding to one nozzle row 42 were printed by a pair of forward and return prints. However, multiple adjustment patterns 201 corresponding to one nozzle row 42 may each be printed by multiple forward and return prints. By printing multiple adjustment patterns 201 by multiple forward and return prints, the number of nozzles 41 ejecting ink simultaneously can be reduced. This suppresses a decrease in the ejection speed of the ink dots constituting the baseline 203. As a result, the misalignment between the baseline 203 and the diagonal lines 204 is reduced.

[0067] In the embodiment described above, the user determined which adjustment pattern 201 had the smallest misalignment of the baseline 203 between the forward pattern 202A and the return pattern 202B, and which adjustment pattern 201 had the smallest misalignment of the diagonal lines 204 between the forward pattern 202A and the return pattern 202B. However, such adjustment patterns 201 may be automatically determined by the printer 10. Automatic determination may be performed, for example, based on an image of the bidirectional adjustment pattern 200 captured by a camera provided on the carriage 30 or the like. Various known methods can be used without particular limitation as the method for calculating the amount of misalignment based on the image. The printer 10 may have an interface that accepts selections corresponding to steps S03 and S04 in Figure 7, and may automatically select a correction value according to the user's selection.

[0068] Unless otherwise specified, the embodiments do not limit the present invention. [Explanation of symbols]

[0069] 5. Recording media 10. Inkjet printer (printer) 15. Platen (support stand) 35. Carriage moving device (moving device) 40 Inkheads 41 nozzles 41A Nozzle Group 1 41B Nozzle Group 2 42 nozzle rows 100 Control device 104 Adjustment Pattern Printing Section (Pattern Printing Section) 200 bidirectional adjustment patterns 201 Adjustment Pattern 202A Outbound Pattern 202B Return Trip Pattern 203 Baseline 204 diagonal line 205 Symbol L1 Baseline extension L2 extension of the diagonal line X Sub-scanning direction (alignment direction) Y Main scanning direction (scanning direction) Y1 Outbound direction Y2 Return Route

Claims

1. A support stand for supporting the recording medium, An ink head having a nozzle row in which a plurality of nozzles are arranged in a predetermined direction, each ejecting ink toward the recording medium supported on the support base, A moving device for moving the ink head in a scanning direction perpendicular to the aforementioned alignment direction, The system comprises a control device for controlling the ink head and the moving device, The control device is The system includes a pattern printing unit that controls the ink head and the moving device to print a bidirectional adjustment pattern on the recording medium for correcting the deviation in the ink landing position with respect to the scanning direction between forward printing, in which ink is ejected from the ink head while the ink head is moved to one side of the scanning direction, and return printing, in which ink is ejected from the ink head while the ink head is moved to the other side of the scanning direction. The aforementioned bidirectional adjustment pattern includes a plurality of adjustment patterns, each with a different correction value set, arranged in the scanning direction. Each adjustment pattern includes a baseline extending in the direction of alignment and a diagonal line intersecting the direction of alignment, wherein the baseline and the diagonal line are arranged in the direction of alignment. Printer.

2. The pattern printing unit prints the plurality of adjustment patterns by a pair of forward and return printing passes. The printer according to claim 1.

3. The length of each adjustment pattern in the direction of alignment is set to be less than or equal to the length of the nozzle row in the direction of alignment. The printer according to claim 1.

4. The pattern printing unit is When printing the baseline, ink is ejected from the first group of nozzles among the plurality of nozzles in the nozzle row. When printing the aforementioned diagonal lines, ink is ejected from a second group of nozzles located closer to the center in the nozzle row than the first group of nozzles in the same direction. The printer according to claim 1.

5. The pattern printing unit prints symbols representing the correction values ​​of each adjustment pattern on the extension of the baseline or the extension of the diagonal line of each adjustment pattern. The printer according to claim 1.

6. The aforementioned diagonal lines intersect the baseline at an angle of 45° or less. The printer according to claim 1.

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