Correction method of recording position, recording method, recording device, and program

Abstract

To reduce recording position deviation which dynamically changes with thermal deformation in a recording head which circulates ink with a recording device.SOLUTION: A temperature of a recording element substrate 10 of a recording head 3 is adjusted at a target temperature, and a liquid is circulated in the recording element substrate 10. After thermal expansion of the recording head 3 results in a steady state, recording position deviation of the recording head 3 in a conveyance direction is acquired from a test pattern recorded by using a recording element 15. Furthermore, a correction value for correcting the recording position deviation is set on the basis of the acquired recording position deviation.SELECTED DRAWING: Figure 17

Description

[Technical field]

[0001] The present invention relates to a print position correction method, a print method, a print device, and a program. [Background technology]

[0002] In some long inkjet recording heads to be mounted on line-type recording devices, which are made by connecting a plurality of ejection modules, misalignment between the ejection modules occurs in the short direction intersecting with the long direction of the head, which may cause image degradation.

[0003] Patent Document 1 discloses a method for reducing misalignment of print positions in the lateral direction by adjusting the ejection timing of print elements arranged in the longitudinal direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-44423 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the method of Patent Document 1 can correct print position deviations caused by the static configuration of the print head, it is difficult to correct print position deviations caused by dynamic deformation of the print head. In particular, in a print head that circulates ink between the print head and a printing device to maintain normal ejection operation, the heat distribution of the print head and the associated thermal deformation change dynamically due to the heat of the ink flowing inside the print head, making it difficult to correct print position deviations.

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to reduce printing position deviations that change dynamically due to thermal deformation in a print head that circulates ink between the print head and a printing device. [Means for solving the problem]

[0007] To this end, the present invention provides a method for correcting a printing position in a second direction of a printing device comprising: a plurality of printing element substrates on which a plurality of printing elements are arranged in succession in a first direction; a temperature control means for adjusting the temperature of the printing element substrates; a circulation means for circulating liquid to the printing element substrates; a common supply flow path for supplying liquid commonly to the plurality of printing element substrates; and a common recovery flow path for commonly recovering liquid from the plurality of printing element substrates, the method using a printing head that thermally expands in accordance with the circulation of liquid to print an image on a printing medium moving in a second direction intersecting the first direction, the method including: performing temperature control for the plurality of printing element substrates of the printing head by the temperature control means and the circulation means; acquiring an amount of printing position deviation of the printing head in the second direction from a test pattern recorded on a printing medium transported in the second direction by driving the printing elements; and setting a correction value based on the amount of printing position deviation, the method being characterized in that the common supply flow path and the common recovery flow path are adjacent to each other in the second direction, and the liquid flowing through the common supply flow path and the common recovery flow path flows from one side to the other in the first direction. Effect of the Invention

[0008] According to the present invention, it is possible to reduce printing position deviation that changes dynamically due to thermal deformation in a print head that circulates ink between the print head and a printing device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 shows an example of a recording device. [Diagram 2] Block diagram for explaining the control configuration [Diagram 3] FIG. 1 is a diagram for explaining an ink circulation system. [Figure 4] FIG. 3 is a perspective view of the appearance of a recording head; [Diagram 5] An exploded perspective view of a recording head [Figure 6] FIG. 1 shows a state in which a recording head is attached to a carriage. [Figure 7] FIG. 1 is a diagram for explaining a detailed configuration of a flow path member; [Figure 8] FIG. 1 is a perspective view and a cross-sectional view for explaining a flow path structure formed in a flow path member. [Figure 9] Perspective and exploded views of the dispensing module [Figure 10] FIG. 2 is a diagram for explaining the structure of a recording element substrate in detail. [Figure 11] FIG. 2 is a diagram for explaining the structure of a recording element substrate in detail. [Figure 12] FIG. 13 is a diagram showing a connection state of adjacent recording element substrates. [Figure 13] FIG. 1 is a diagram for explaining another example of a recording head; [Figure 14] FIG. 11 is a detailed view showing the flow path structure of a recording head according to another embodiment; [Figure 15] FIG. 1 is a diagram for explaining thermal deformation of a recording head; [Figure 16] FIG. 1 is a diagram for explaining a recording position deviation caused by thermal deformation of a recording head; [Figure 17] 1 is a flowchart illustrating a correction process according to a first embodiment. [Figure 18] FIG. 1 is a diagram for explaining the effect of correcting a print position deviation in the first embodiment; [Figure 19] FIG. 1 is a diagram for explaining the difference in deformation of a print head caused by a difference in ejection frequency; [Figure 20] 11 is a flowchart illustrating a correction process according to a second embodiment. [Figure 21] FIG. 13 is a diagram for explaining a method for setting a correction value and an effect of correction according to the second embodiment; [Figure 22] A diagram showing the relationship between the circulation amount and the temperature control temperature for reproducing an intermediate state. [Diagram 23] FIG. 13 is a diagram showing the relationship between the circulation amount and the flow rate of ink in the ejection unit; [Figure 24] 13 is a flowchart illustrating a correction process according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (First embodiment) <Overall configuration of the recording device> 1(a) and (b) are diagrams showing an example of a recording device that can be used in this embodiment. The recording device of this embodiment is an inkjet recording device (hereinafter simply called the recording device) 1000 that records a color image on a recording medium S by ejecting cyan (C), magenta (M), yellow (Y) and black (Bk) inks. In the figure, the X direction is the transport direction of the recording medium S, the Y direction is the width direction of the recording medium, and the Z direction is the vertical upward direction.

[0011] Fig. 1(a) shows a recording device 1000 in which a liquid ejection head (hereinafter referred to as a recording head) 3 applies ink directly to a recording medium S transported in the X direction. The recording medium S is mounted on a transport section 1, and is transported in the X direction at a predetermined speed below four recording heads 3 that eject different inks. In Fig. 1(a), the four recording heads 3 are arranged in the X direction in the order of cyan, magenta, yellow, and black, and inks are applied to the recording medium S in that order. Each recording head 3 has multiple ejection openings that eject ink arranged in the Y direction.

[0012] FIG. 1(b) shows a recording device 1000 in which inks ejected from four color recording heads 3 are transferred to a recording medium S via an intermediate transfer drum 2. The four recording heads 3 ejecting different inks are arranged so that their ejection opening faces face the surface of the cylindrical intermediate transfer drum 2. When the recording medium S, which is transported in the X direction by a transport roller 4, passes through a nip portion between the intermediate transfer drum 2 and a transfer roller 5, the ink applied to the intermediate transfer drum 2 is transferred to the recording medium S. The recording head 3 of this embodiment can be used in either of the recording devices 1000 shown in FIG. 1(a) or (b).

[0013] Although cut paper is shown as the recording medium S in FIGS. 1(a) and 1(b), the recording medium S2 may be continuous paper supplied from a roll of paper.

[0014] 2 is a block diagram for explaining the control configuration of the recording device 1000. The control unit 500 is composed of a CPU and the like, and controls the entire recording device 1000 while using the RAM 502 as a work area in accordance with the programs and various parameters stored in the ROM 501. The control unit 500 performs predetermined image processing on image data received from an externally connected host device 600 in accordance with the programs and parameters stored in the ROM 501, and generates ejection data that can be ejected by the recording head 3. Then, the recording head 3 is driven in accordance with this ejection data, causing it to eject ink at a predetermined frequency.

[0015] During the ejection operation by the print head 3, the control unit 500 drives the transport motor 503 to transport the print medium S in the X direction at a speed corresponding to the drive frequency. As a result, an image is recorded on the print medium S according to the image data received from the host device 600. The ROM 501 stores information on the use area of ​​the ejection ports used for ejection in the print head 3 in a rewritable manner for each print head 3. The method of setting the use area will be described in detail later.

[0016] Although not shown in FIG. 2, a plurality of recording element substrates 10 (see FIGS. 3 and 4) are arranged on the recording head 3. Each recording element substrate 10 is provided with a temperature sensor 301 for detecting the temperature of the recording element substrate 10 and a plurality of sub-heaters 302 for heating the recording element substrate 10 to a predetermined set temperature. For ease of explanation, FIG. 2 shows the plurality of temperature sensors 301 and sub-heaters 302 as one. When performing a recording operation, the control unit 500 drives the sub-heater 302 based on the temperature detected by the temperature sensor 301 to keep each recording element substrate 10 at an appropriate temperature. In this embodiment, the recording element substrate 10 is kept at 65° C. in a general recording operation.

[0017] The liquid circulation unit 504 is a unit for circulating and supplying liquid (ink) to the recording head 3. The liquid circulation unit 504 controls a system for circulating the ink under the management of the control unit 500. Note that, for simplicity, the recording head 3 and liquid circulation unit 504 for one color are shown in Fig. 2, but in reality, the recording heads 3 and liquid circulation units 504 for four colors are controlled by the control unit.

[0018] <Ink circulation system> 3(a) and (b) are diagrams for explaining the ink circulation system controlled by the liquid circulation unit 504. FIG.

[0019] 3(a) and 3(b), ink stored in a buffer tank 1001 is supplied to the print head 3, and ink not consumed by ejection is collected back into the buffer tank 1001. That is, ink is circulated between the buffer tank 1001 and the print head 3. When the ink stored in the buffer tank 1001 falls below a predetermined amount, a refill pump P0 is driven, and ink stored in a main tank 1002 is refilled into the buffer tank 1001. The buffer tank 1001 is provided with an air vent (not shown), and air bubbles contained in the ink collected from the print head 3 rise to the water surface by buoyancy and are released into the atmosphere.

[0020] The recording head 3 of this embodiment has a discharge unit 300 that discharges ink in accordance with discharge data, and two liquid supply units 220 for adjusting the pressure of the ink supplied to the discharge unit 300. A first negative pressure control unit 230 and a second negative pressure control unit 231 for controlling the pressure of the ink flowing to the discharge unit 300 are respectively arranged in the two liquid supply units 220.

[0021] 3(a) shows an example in which the first negative pressure control unit 230 and the second negative pressure control unit 231 are disposed upstream of the ejection unit 300 in the flow of ink. After the ink contained in the buffer tank 1001 is discharged by the first circulation pump P1, it is split into two and supplied to the left and right liquid supply units 220. The supplied ink is supplied to the first negative pressure control unit 230 and the second negative pressure control unit 231 through the respective filters 221.

[0022] The first negative pressure control unit 230 has a control pressure set to a weak negative pressure (negative pressure with a small pressure difference from atmospheric pressure). The second negative pressure control unit 231 has a control pressure set to a strong negative pressure (negative pressure with a large pressure difference from atmospheric pressure). The pressure realized by the first negative pressure control unit 230 is higher (negative pressure is lower) than the pressure realized by the second negative pressure control unit 231, so in the figure, the first negative pressure control unit 230 is indicated as H and the second negative pressure control unit 230 is indicated as L.

[0023] The ink whose pressure has been adjusted by the first negative pressure control unit 230 is recovered into the buffer tank 1003 by the suction force of the second circulation pump P2 via the common supply flow path 211 of the discharge unit 300. The ink whose pressure has been adjusted by the second negative pressure control unit 231 is recovered into the buffer tank 1003 by the suction force of the third circulation pump P3 via the common recovery flow path 212 of the discharge unit 300. The adjusted pressures in the first negative pressure control unit 230 and the second negative pressure control unit 231 are maintained within an appropriate range by driving the second circulation pump P2 and the third circulation pump P3.

[0024] The amount of liquid flowing through the common supply flow path 211 and the common recovery flow path 212 varies depending on the frequency at which the ejection units 300 eject ink, i.e., the duty of the image. By providing the first negative pressure control unit 230 and the second negative pressure control unit 231 upstream of the ejection units 300 as in this embodiment, the ink pressure in the ejection units 300 can be kept within a constant range regardless of the duty of the image.

[0025] In the ejection unit 300, a plurality of recording element substrates 10 are arranged in the extension direction (Y direction) of the common supply flow path 211 and the common recovery flow path 212. Each recording element substrate 10 is connected to the common supply flow path 211 via an individual supply flow path 213a, and is connected to the common recovery flow path 212 via an individual recovery flow path 213b. Since there is a pressure difference between the ink flowing through the common supply flow path 211 and the ink flowing through the common recovery flow path 212, in each recording element substrate 10, a flow of ink is formed from the individual supply flow path 213a toward the individual recovery flow path 213b.

[0026] In the above ink circulation configuration, the first circulation pump P1 is preferably one that can obtain a certain head pressure or more within the range of the ink circulation flow rate realized when the ejection unit 300 is driven, and a turbo pump, a positive displacement pump, or the like can be used. Specifically, a diaphragm pump, or the like can be used. Also, instead of the first circulation pump P1, a water head tank arranged with a certain water head difference with respect to the first negative pressure control unit 230 and the second negative pressure control unit 231 can be used.

[0027] The second circulation pump P2 and the third circulation pump P3 may be a positive displacement pump having a quantitative liquid delivery capacity. Specific examples include a tube pump, a gear pump, a diaphragm pump, a syringe pump, etc. Alternatively, a general constant flow valve or a relief valve may be provided at the pump outlet to ensure a constant flow rate.

[0028] The first negative pressure control unit 230 and the second negative pressure control unit 231 may have a mechanism similar to a so-called "pressure reducing regulator." When a pressure reducing regulator is used, it is preferable to arrange the first circulation pump P1 so as to pressurize the upstream side of the first negative pressure control unit 230 and the second negative pressure control unit 231, as shown in FIG. 3(a). In this way, the effect of the head pressure of the buffer tank 1001 on the discharge unit 300 can be suppressed, and therefore the degree of freedom in the layout of the buffer tank 1003 in the recording apparatus 1000 can be improved.

[0029] In the discharge unit 300 shown in FIG. 3(a), when the recording device 1000 is performing a recording operation, a constant amount of ink flows in each recording element substrate 10 regardless of the presence or absence of discharge data. This makes it possible to suppress thickening of ink in discharge ports with low discharge frequency, and to discharge thickened ink and foreign matter from the discharge unit 300. Furthermore, as shown in FIG. 3(a), by making the ink flow direction in the common supply flow path 211 and the ink flow direction in the common recovery flow path 212 opposite to each other, it is possible to promote heat exchange between these opposing flow paths. As a result, it is possible to reduce the temperature gradient in the longitudinal direction (Y direction) in the recording head 3, and to suppress the variation in the discharge amount of the multiple recording element substrates 10.

[0030] However, if the ink flow rate in the discharge unit 300 is set to a too large value, the pressure loss in the flow path may cause a large negative pressure difference between the recording element substrates 10, resulting in uneven density in the output image. Therefore, it is preferable that the ink flow rate in the discharge unit 300 is appropriately adjusted according to the degree of viscosity increase at the discharge ports with low discharge frequency, the temperature variation between the recording element substrates 10, and the pressure loss.

[0031] Fig. 3(b) shows an example in which the first negative pressure control unit 230 and the second negative pressure control unit 231 are disposed downstream of the ejection unit 300 in the flow of ink. The configuration shown in Fig. 3(b) also provides substantially the same effects as those described using Fig. 3(a). Below, differences from the configuration in Fig. 3(a) will be described.

[0032] In Fig. 3(b), the ink flows in the opposite direction to that in Fig. 3(a). That is, the ink stored in the buffer tank 1001 is supplied to the common supply flow path 211 of the liquid supply unit 220 by the second circulation pump P2, and is supplied to the common recovery flow path 212 of the liquid supply unit 220 by the third circulation pump P3. The ink that has passed through the common supply flow path 211 is recovered in the buffer tank 1001 via the first negative pressure control unit 230 by the first circulation pump P1 acting as a negative pressure source. The ink that has passed through the common recovery flow path 212 is recovered in the buffer tank 1001 via the second negative pressure control unit 231 by the first circulation pump P1 acting as a negative pressure source.

[0033] As the first negative pressure control unit 230 and the second negative pressure control unit 231 in Fig. 3(b), a mechanism similar to a so-called "back pressure regulator" can be adopted. By providing the first negative pressure control unit 230 and the second negative pressure control unit 231, which serve as back pressure regulators, downstream of the discharge unit 300, the ink pressure in the discharge unit 300 can be kept within a constant range regardless of the image duty. In the configuration of Fig. 3(b), as in the configuration of Fig. 3(a), the influence of the head pressure of the buffer tank 1001 on the discharge unit 300 can be suppressed, so that the degree of freedom in the layout of the buffer tank 1003 in the recording apparatus 1000 can be increased.

[0034] 3(b), ink supplied from the buffer tank 1001 is supplied directly to the discharge unit 300 via the filter 221. Therefore, even if dust or foreign matter is generated in the first negative pressure control unit 230 or the second negative pressure control unit 231, this will not get mixed into the liquid discharge unit.

[0035] Furthermore, in the case of the configuration of Fig. 3(b), the maximum flow rate of ink sent from the buffer tank 1001 to the ejection unit 300 can be kept lower than in the configuration of Fig. 3(a). The reason for this will be explained below.

[0036] First, the flow rate required to circulate ink in the discharge unit 300 in a state where no discharge operation is performed is defined as Qa. The flow rate Qa is defined as the minimum flow rate required to keep the discharge unit 300 at an appropriate temperature when the recording apparatus 1000 is in a standby state. Also, the flow rate of ink consumed in the discharge unit 300 in a state where all the discharge ports are performing the discharge operation at the maximum frequency is defined as Qb.

[0037] In the case of the configuration of FIG. 3(a), the sum of the set flow rates of the second circulation pump P2 on the high pressure side and the third circulation pump P3 on the low pressure side is Qa. Therefore, when the maximum frequency of the discharge operation is performed at all the discharge ports, the maximum value of the ink supply amount to the discharge unit 300 is Qa+Qb. In contrast, in the case of the configuration of FIG. 3(b), the sum of the set flow rates of the second circulation pump P2 on the high pressure side and the third circulation pump P3 on the low pressure side may be the larger value of Qa and Qb. In other words, in the configuration of FIG. 3(b), the total amount of ink circulated and therefore the power of the pump can be kept lower than in the configuration of FIG. 3(a), and as a result, the degree of freedom of the applicable circulation pump can be increased. And, such an effect is more noticeable as Qa and Qb become larger, that is, as the size of the line head becomes larger.

[0038] On the other hand, in the case of the configuration of FIG. 3(b), the negative pressure acting on each nozzle is larger than that in the configuration of FIG. 3(a), and satellites may be more noticeable in the output image. This is because, in the configuration of FIG. 3(b), the maximum value of the flow rate flowing through the discharge unit 300 is the same as the flow rate flowing in a state where no discharge operation is performed, so the lower the duty of the image, the greater the negative pressure acting on each discharge port. Therefore, satellites occur at each discharge port even in an image with a low duty, and such satellites are more noticeable in an image with a low duty. This tendency becomes more noticeable when the widths of the common supply flow path 211 and the common recovery flow path 212 are reduced in order to reduce the size of the liquid discharge head. In contrast, in the configuration of FIG. 3(a), the negative pressure acting on each nozzle is larger when the duty is high, but in this case, even if satellites occur, they are less noticeable in an image with a high duty.

[0039] The ink circulation configuration of this embodiment can be either one of the configurations shown in Fig. 3(a) and (b) taking into consideration the respective characteristics described above. Although Fig. 3(a) and (b) show the ink circulation configuration for one color of ink, in practice such a configuration is provided for each ink color. Also, in the above, the liquid flows in the common supply flow path 211 and the common recovery flow path 212 in opposite directions in order to reduce the temperature gradient in the longitudinal direction (Y direction) within the recording head 3, but these may flow in the same direction.

[0040] <Recording head configuration> 4(a) and (b) are external perspective views of the recording head 3 that can be used in this embodiment. FIG. 4(a) is a view of the recording head 3 seen from diagonally below, and FIG. 4(b) is a view of the recording head 3 seen from diagonally above. In the recording head 3, recording head support parts 80 for ensuring rigidity are provided on both sides in the Y direction, which is the longitudinal direction, and each of these two recording head support parts 80 accommodates the liquid supply unit 220 described in FIG. 3(a) and (b). In the figure, the first negative pressure control unit 230 and the second negative pressure control unit 231 protrude upward (in the +Z direction) from the recording head support part 80. A liquid connection part 111 for connection to a buffer tank 1001 is provided on the lower surface of the recording head support part 80.

[0041] A plurality of recording element substrates 10 are linearly arranged in the Y direction over a distance corresponding to the width of an A3 size on the underside of the recording head 3. In each recording element substrate 10, 20 ejection port arrays, each of which has a plurality of ejection ports arranged in the Y direction, are arranged in parallel in the X direction (see FIG. 10).

[0042] Electric wiring boards 90 extending in the Y direction are disposed on both side surfaces of the recording head 3 in the X direction, which is the short side direction. Each of the recording element substrates 10 is connected to the electric wiring boards 90 on both sides via a flexible wiring board 40. Each of the electric wiring boards 90 is provided with two power supply terminals 92 for receiving power from the main body of the recording device 1000 and four signal input terminals 91 for receiving ejection signals. By consolidating the wiring using an electric circuit within the electric wiring board 90, the number of signal input terminals 91 and power supply terminals 92 can be reduced to less than the number of recording element substrates 10, and the connection work when attaching and detaching the recording head 3 to and from the recording device 1000 can be simplified.

[0043] 5 is an exploded perspective view of the recording head 3. The recording head 3 mainly includes a liquid supply unit 220, an electric wiring board 90, a recording head support part 80, and a discharge unit 300. The discharge unit 300 has a flow path member 210 that circulates ink to each recording element substrate 10, a plurality of discharge modules 200 each composed of the recording element substrate 10 and a flexible wiring board 40, and a cover member 130 that covers the outer periphery of the discharge module 200.

[0044] The flow path member 210 has a first flow path member 50 that is fluidly connected to the recording element substrate 10, and a second flow path member 60 that is fluidly connected to the liquid supply unit 220. The first flow path member 50 has the individual supply flow paths 213a and the individual recovery flow paths 213b described in Figs. 3(a) and (b) formed therein. The second flow path member 60 has the common supply flow path 211 and the common recovery flow path 212 described in Figs. 3(a) and (b) formed therein. The second flow path member 60 is connected to the recording head support part 80, and together with the recording head support part 80, it is responsible for the rigidity of the recording head 3. The material of the second flow path member 60 is preferably one that has sufficient corrosion resistance against liquid and high mechanical strength. Specifically, SUS, Ti, alumina, etc. can be preferably used.

[0045] The cover member 130 is a member having a frame-shaped surface in which a long cover opening 131 is provided. From the cover opening 131 of the cover member 130, the recording element substrates 10 and a sealant 110 (see FIG. 9) for sealing the connection between each recording element substrate 10 and the flexible wiring substrate 40 are exposed. The frame portion around the cover opening 131 functions as a contact surface when a cap provided on the recording device 1000 caps the discharge port surface of the recording head 3. In order to form a suitable closed space when capping, it is preferable to apply an adhesive, a sealant, a filler, or the like around the cover opening 131 so as to fill unevenness and gaps on the discharge port surface of the discharge unit 300.

[0046] When assembling the recording head 3, the discharge unit 300 is attached to the lower surface of the recording head support part 80, two electric wiring boards 90 are attached to both side surfaces of the recording head support part 80, and the liquid supply unit 220 is installed inside the recording head support part 80. At the connection part between the liquid supply unit 220 and the discharge unit 300, a joint rubber 100 is arranged to prevent ink leakage.

[0047] 6 is a diagram showing a state in which the recording head 3 is attached to a carriage 70 provided in the recording device 1000. The carriage 70 has a box-like shape capable of mounting the recording head 3, and is provided with a movable part 71 that is slidable in the Y direction on one side in the longitudinal direction, that is, the Y direction.

[0048] In this embodiment, by providing the movable part 71 on one side of the carriage 70 in this manner, when the recording head 3 expands in the longitudinal direction, the movable part 71 of the carriage 70 moves in the +Y direction. Therefore, even if the recording head 3 thermally expands in the longitudinal direction, the carriage 70 can support the recording head 3 without distorting it.

[0049] Figures 7(a) to (e) are diagrams for explaining the detailed configuration of the flow path member 210. Figures 7(a) and (b) show the front and back surfaces of the first flow path member 50, and Figures 7(c) to (e) show the front surface, middle layer cross section, and back surface, respectively, of the second flow path member 60. Figure 7(a) is the surface that comes into contact with the recording element substrate 10, and Figure 7(e) is the surface that comes into contact with the liquid supply unit 220. The surface of the first flow path member 50 shown in Figure 7(b) and the surface of the second flow path member 60 shown in Figure 7(c) come into contact with each other.

[0050] The first flow path member 50 includes a plurality of individual members 52 arranged in the Y direction, and each individual member 52 corresponds to one recording element substrate 10. With this configuration, by adjusting the number of discharge modules 200 and the number of individual members 52 arranged, recording heads 3 of various sizes can be assembled.

[0051] 7(a), the first flow path member 50 has a surface in contact with the recording element substrate 10 formed with communication paths 51 that are fluidly connected to the recording element substrate 10 and serve as the individual supply flow paths 213a and the individual recovery flow paths 213b described in FIGS. 3(a) and 3(b). Each communication path 51 has an individual communication port 53 that is fluidly connected to the second flow path member 60.

[0052] 7(c), a communication port 61 communicating with the individual communication port 53 of the first flow path member 50 is formed on the surface of the second flow path member 60 that abuts against the first flow path member 50. A pair of communication ports 61, one for supply and one for recovery, is provided corresponding to each individual member 52.

[0053] 7(d), a common flow path groove 62 extending in the Y direction is formed in the middle layer of the second flow path member 60, and serves as the common supply flow path 211 and the common recovery flow path 212 described in FIGS. 3(a) and 3(b). Common communication ports 63 that are fluidly connected to the liquid supply unit 220 are formed at both ends of the common flow path groove 62.

[0054] 8(a) and (b) are a perspective view and a cross-sectional view for explaining a flow path structure formed inside the flow path member 210. Fig. 8(a) is an enlarged perspective view of the flow path member 210 as viewed from the Z direction, and Fig. 8(b) is a cross-sectional view taken along line VIIIb-VIIIb of Fig. 8(a).

[0055] The common supply flow path 211 and the common recovery flow path 212 extending in the longitudinal direction (Y direction) of the second flow path member 60 are connected to the first flow path member 50 via the communication port 61 of the second flow path member 60 and the individual communication port 53 of the first flow path member 50. That is, the second flow path member 60 and the first flow path member 50 are stacked with the communication port 61 and the individual communication port 53 aligned. In addition, the recording element substrate 10 of the ejection module 200 is placed on the communication path 51 of the first flow path member 50 via the support member 30. Note that although the individual communication port 53 corresponding to the common recovery flow path 212 is not shown in FIG. 8(b), it is clear from FIG. 8(a) that it is shown in another cross section.

[0056] As already described, the common supply flow path 211 is connected to the first negative pressure control unit 230 with a relatively high pressure, and the common recovery flow path 212 is connected to the second negative pressure control unit 231 with a relatively low pressure. Therefore, an ink supply path to the recording element substrate 10 is formed, which is composed of the common communication port 63 (see FIG. 7), the common supply flow path 211, the communication port 61, the individual communication port 53, the communication passage 51 (individual supply flow path 213a), and the recording element substrate 10. Similarly, an ink recovery path is formed, which is composed of the recording element substrate 10, the communication passage 51 (individual recovery flow path 213b), the individual communication port 53, the communication port 61, the common recovery flow path 212, and the common communication port 63 (see FIG. 7). While the ink is circulated in this way, the recording element substrate 10 performs an ejection operation according to the ejection data, and the ink that is supplied through the ink supply path and is not consumed by the ejection operation is recovered through the ink recovery path.

[0057] 9(a) and 9(b) are a perspective view and an exploded view of the discharge module 200. The discharge module 200 is manufactured by adhering the recording element substrate 10 to the support member 30, electrically connecting the terminals 16 of the recording element substrate 10 and the terminals 41 of the flexible wiring substrate 40 by wire bonding, and sealing the wire bonding portion with a sealing material 110. In the flexible wiring substrate 40, the terminals 42 located opposite the recording element substrate 10 are electrically connected to the electrical wiring substrate 90 (see FIG. 4). The recording element substrate 10 of this embodiment is provided with 20 rows of discharge port rows, i.e., 20 rows of recording elements, and the 10 rows on one side and the 10 rows on the other side are associated with different flexible wiring substrates 40. In this way, by connecting the flexible wiring substrates 40 to both sides of the recording element substrate 10, the distance between each recording element substrate 10 and the terminals 16 can be shortened as much as possible, and the voltage drop and signal transmission delay occurring in the wiring portion can be reduced. However, when the number of recording element arrays is small or when voltage drop and the like are not a significant problem, the flexible wiring board 40 may be disposed on only one side of the recording element board 10 .

[0058] In the support member 30, a liquid supply port 31 serving as an opening is formed at a position corresponding to the communication passage 51 described in Figures 8(a) and (b) so as to straddle all the ejection port rows of the recording element substrate 10. The support member 30 is a support for the recording element substrate 10, and at the same time, is also a flow path member located between the recording element substrate 10 and the flow path member 210. For this reason, it is preferable that the support member 30 has a high degree of flatness and can be bonded to the recording element substrate 10 with sufficiently high reliability. Examples of materials that can be suitably used include alumina and resin materials.

[0059] <Configuration of the recording element substrate> Figures 10(a) to (c) and 11 are diagrams for explaining the structure of the recording element substrate 10 in detail. Figure 10(a) is a top view of the recording element substrate 10, Figure 10(b) is an enlarged perspective view of an area Xb shown in Figure 10(a), and Figure 10(c) is a rear view of the recording element substrate 10. Also, Figure 11 is a cross-sectional view taken along line XI-XI of Figure 10(a). As shown in Figure 11, one recording element substrate 10 is formed by laminating an ejection port forming member 12 made of a photosensitive resin, a substrate 11 made of silicon, and a thin film cover plate 20.

[0060] 10(a), the recording element substrate 10 of this embodiment has a parallelogram shape. Furthermore, in the recording element substrate 10, terminals 16 for electrical connection to the flexible wiring substrate 40 are formed on both ends in the short side direction (±X direction) of the recording head 3.

[0061] In the ejection port forming member 12, 20 ejection port arrays, each of which has ejection ports 13 that eject ink of the same color arranged in the Y direction, are arranged in parallel in the X direction. Therefore, the ejection data for one pixel only needs to be ejected by any of the 20 ejection ports located at the same position in the Y direction, and the drive frequency of the recording head 3 can be increased while ensuring the drive cycle of each ejection port. Even if a non-ejecting ejection port occurs, the ejection data from that ejection port can be distributed to other ejection ports located at the same position in the Y direction, so an image without any missing data can be recorded.

[0062] FIG. 10(b) is an enlarged view of the region Xb shown in FIG. 10(a). In the ejection port forming member 12, the partition walls 22 are arranged in the Y direction at a predetermined pitch to partition the ejection port forming member 12, thereby forming a plurality of pressure chambers 23. The recording elements 15, which are electrothermal conversion elements, are arranged on the surface of the substrate 11 at positions corresponding to the individual pressure chambers 23. The recording elements 15 are electrically connected to the terminals 16 by wiring (not shown) provided on the recording element substrate 10. The control unit 500 (see FIG. 2) of the recording device 1000 transmits a pulse voltage according to the ejection data, and the pulse voltage is applied to the recording elements 15 via the electric wiring substrate 90 and the flexible wiring substrate 40. Then, the recording elements 15 generate heat, causing film boiling in the liquid contained in the pressure chambers 23, and the growth energy of the generated bubbles causes a part of the ink contained in the pressure chambers 23 to be ejected from the ejection ports 13 to the outside.

[0063] On the other hand, on both sides of each ejection port row in the X direction, a liquid supply path 18 that is connected to an individual supply path 213a of the flow path member 210 and connected to the multiple pressure chambers 23, and a liquid recovery path 19 that is connected to an individual recovery path 213b of the flow path member 210 and connected to the multiple pressure chambers 23 extend in the Y direction. As shown in the cross-sectional view of FIG. 11, the liquid supply path 18 has a supply port 17a that communicates with the pressure chamber 23, and the liquid recovery path 19 has a recovery port 17b that communicates with the pressure chamber 23, which correspond to each pressure chamber 23. The liquid inside the pressure chamber 23 flows between the outside of the pressure chamber 23 via the supply port 17a and the recovery port 17b. That is, fresh ink is supplied to the pressure chamber 23 regardless of whether ink has been ejected from the ejection port 13 for the ejection operation.

[0064] Furthermore, as shown in FIG. 10(c), the cover plate 20 arranged on the side in contact with the first flow path member 50 has a plurality of openings 21 formed at positions corresponding to the communication passages 51 of the first flow path member 50 and the liquid supply ports 31 of the support member 30. In this embodiment, three openings 21 are provided for each of the liquid supply paths 18, and two openings 21 are provided for each of the liquid recovery paths 19 in the cover plate 20. As shown in FIG. 10(b), each opening 21 of the cover plate 20 communicates with the plurality of communication passages 51 shown in FIG. 7(a). In such a cover plate 20, sufficient corrosion resistance against the liquid (ink) and high layout accuracy of the plurality of openings 21 are required. Therefore, it is preferable that the plurality of cover plates 20 are formed by a photolithography process using, for example, a photosensitive resin material or a silicon plate.

[0065] FIG. 12 is a diagram showing the connection state of adjacent recording element substrates 10. The recording head 3 of this embodiment has a parallelogram shape, and two adjacent recording element substrates 10 are continuously arranged in the Y direction with their sides abutting each other. At this time, at the connection point of the two recording element substrates 10, at least one ejection port 13 located at the extreme end of one recording element substrate 10 and an ejection port 13 located at the extreme end of the other recording element substrate 10 are laid out at the same position in the Y direction. In other words, the inclination angle of the parallelogram is designed so that they are laid out in this way. In the figure, two ejection ports 13 on line P are laid out at the same position in the Y direction.

[0066] With this configuration, even if the two recording element substrates 10 are connected with some misalignment during the manufacture of the liquid ejection head, the image at the position corresponding to the connection part can be recorded by the multiple ejection ports included in the overlapping area. Therefore, in the image recorded on the paper surface, black streaks and white spots caused by the above-mentioned misalignment can be made less noticeable. Note that, although the main plane of the recording element substrate 10 is a parallelogram in the above description, the present invention is not limited to this. For example, a recording element substrate having a rectangular, trapezoidal, or other shape can also be used.

[0067] Although not shown in Figs. 10 to 12, each recording element substrate 10 is divided into a plurality of areas, and a temperature sensor 301 and a sub-heater 302 are provided for each area. The control unit 500 (see Fig. 2) adjusts the temperature based on the temperature set for each area using the temperature sensor 301 and the sub-heater 302. That is, the control unit 500 drives the sub-heater 302 only for areas where the temperature detected by the temperature sensor 301 is equal to or lower than the target temperature. By setting the target temperature of the recording element substrate 10 to a relatively high temperature, the viscosity of the ink can be reduced, and the ink can be ejected and circulated appropriately. In addition, by performing such temperature control and suppressing the temperature variation of the plurality of recording element substrates 10 within a predetermined range, the variation in the ejection amount caused by the temperature variation between the recording element substrates 10 can be reduced, and density unevenness in the printed image can be suppressed.

[0068] The target temperature of the recording element substrate 10 is preferably set to a temperature equal to or higher than the equilibrium temperature of the recording element substrate 10 when all the recording elements 15 are driven at the highest possible driving frequency. A diode sensor can be used as the temperature sensor 301.

[0069] Incidentally, the recording elements 15, which are heat generating elements, can also be used as heating means for the recording element substrate 10. Specifically, the recording element substrate 10 can be heated by applying a voltage to the recording elements 15 that does not cause bubbles to form. In this embodiment, the recording elements 15 may be used as heating means instead of the sub-heater 302, or the sub-heater 302 and the recording elements 15 may be used in combination.

[0070] <Another example of a recording head> Figures 13(a) and (b) are diagrams for explaining another example of the recording head 3 that can be used in this embodiment. Figure 13(a) is an external perspective view of the recording head 3, and Figure 13(b) is an exploded view. Below, differences from the recording head 3 explained in Figures 4 and 5 will be explained.

[0071] In the recording head 3 of this example, 36 ejection modules 200 are arranged in the Y direction, and it is possible to accommodate recording media up to B2 size. That is, the recording head 3 of this example is longer than the recording head 3 described in Figures 4 and 5. Below, the differences from the recording head 3 described in Figures 4 and 5 will be described.

[0072] In the recording head 3 of this example, an electric wiring board support part 82 extending in the Y direction is disposed in the center in the ±X direction. Four electric wiring boards 90 are disposed on both sides of the electric wiring board support part 82 in the ±X direction so as to be continuous in the Y direction and are supported by the electric wiring board support part 82. Each of the electric wiring boards 90 is provided with a signal input terminal 91 and a power supply terminal 92. A shield plate 132 is provided on the outer side of the electric wiring board 90 in the ±X direction to protect the wiring circuit of the electric wiring board 90, the flexible wiring board 40, and the connection points thereof. Note that the shield plate 132 is omitted in the exploded view of FIG. 13(b).

[0073] In the recording head 3 of this example, the first negative pressure control unit 230 and the second negative pressure control unit 231 are provided below the liquid supply unit 220 (-Z direction side), and do not protrude above the recording head support parts 80.

[0074] 14(a) to (c) are diagrams showing in detail the flow path structure of the recording head 3 of this example. Fig. 14(a) is a side cross-sectional view of the recording head 3. Compared to the configuration described in Fig. 4, the distance in the gravity direction (Z direction) between the first negative pressure control unit 230 and the second negative pressure control unit 231 and the recording element substrate 10 is smaller. Therefore, the number of flow path connections is reduced compared to the configuration described in Fig. 4, the number of parts and the number of assembly steps are reduced, and ink leakage can be suppressed.

[0075] In addition, the head difference between the first negative pressure control unit 230 and the second negative pressure control unit 231 and the ejection module 200 is smaller than in the configuration described in Fig. 4. Therefore, this is particularly suitable for use in the recording device 1000 in the configuration shown in Fig. 1(b), that is, in a configuration in which multiple recording heads are arranged at different inclinations. Furthermore, the smaller head difference reduces the flow resistance in the circulation flow path, and the difference in pressure loss associated with flow rate changes becomes smaller, making it possible to perform stable negative pressure control.

[0076] Fig. 14(b) is a schematic diagram showing the state of ink circulation in the recording head 3 of this example. The ink circulation in this example is basically the same as the circulation described in Fig. 3(b). That is, the pressure of the ink flowing in the ejection unit 300 is controlled by the first negative pressure control unit 230 and the second negative pressure control unit 231, which are arranged downstream from the ejection unit 300 and function as back pressure regulators.

[0077] Fig. 14(c) is a cross-sectional view taken along line XIVc-XIVc of Fig. 14(a). As with the discharge unit 300 described in Fig. 8(b), the discharge unit 300 of this example also has a second flow path member 60, a first flow path member 50, and a discharge module 200 stacked in this order. However, while the support member 30 is interposed between the first flow path member 50 and the recording element substrate 10 in the discharge unit 300 of Fig. 8(b), the cover plate 20 (see Fig. 11) of the recording element substrate 10 is mounted directly on the surface of the first flow path member 50 in the discharge unit 300 of this example.

[0078] The individual supply flow paths 213a and the individual recovery flow paths 213b formed in each of the multiple individual members 52 constituting the first flow path member 50 communicate with the openings 21 (see FIG. 10(c)) of the cover plate 20 arranged on the back surface of the recording element substrate 10. In the discharge unit 300 of this example, the individual communication openings 53 of the first flow path member 50 are openings that are sufficiently large relative to the communication openings 61 of the second flow path member 60. For this reason, alignment when mounting the first flow path member 50 on the second flow path member 60 is easier than the configurations described in FIGS. 4(a) to 8(b), and as a result, the yield during the manufacture of the recording head can be improved.

[0079] In the recording apparatus 1000 of this embodiment, either the recording head described with reference to FIGS. 4 to 8 or the recording head 3 described with reference to FIGS. 13 to 14 can be suitably used.

[0080] <Print position deviation due to thermal deformation of print head> 15(a) and (b) are diagrams for explaining thermal deformation of the print head. As already explained, a plurality of temperature sensors 301 and sub-heaters 302 are arranged on each print element substrate 10 of the print head 3 of this embodiment, and the print element substrate 10 is adjusted to an appropriate temperature during printing. Hereinafter, the process of adjusting the temperature of the print head 3 in this manner prior to printing is referred to as a temperature adjustment process.

[0081] When the temperature adjustment process is performed, ink before being heated by the recording element substrate 10 flows in the common supply flow path 211, and ink after being heated by the recording element substrate flows in the common recovery flow path 212. As a result, the common recovery flow path 212 side of the second flow path member 60 becomes hotter than the common supply flow path 211 side, causing greater thermal expansion, and the common recovery flow path 212 side bends so as to protrude in the X direction, causing thermal deformation as shown in Fig. 15(b). Such thermal deformation becomes greater the higher the heating temperature by the sub-heater 302 and the greater the amount of ink circulating through the recording element substrate 10.

[0082] On the other hand, there is inevitably a certain degree of variation in the temperature sensor 301 and the sub-heater 302. Also, the amount of ink circulating through the recording element substrate 10 depends on the pressure difference created by the first and second negative pressure control units 230, 231, the flow resistance of the recording element substrate 10, the viscosity of the ink, and the like, and it is difficult to reduce these tolerances and variations to zero. For this reason, in the multiple recording heads 3 mounted on the recording apparatus 1000, there is inevitably a certain degree of variation in thermal deformation during temperature control processing and recording operation.

[0083] 16(a) and 16(b) are diagrams for explaining the print position deviation caused by the thermal deformation of the print head 3. FIG. 16(a) shows the print position deviation when both ends of the print head are fixed to the printing apparatus, and FIG. 16(b) shows the print position deviation when the center of the print head is fixed to the printing apparatus. In both figures, the left side shows the ruled lines printed on the print medium by the head A with relatively large thermal deformation, and the right side shows the ruled lines printed on the print medium by the head B with relatively small thermal deformation. Head A is a print head in which the temperature detected by the temperature sensor 301 is detected to be lower than the actual temperature, and the sub-heater 302 is driven strongly. Alternatively, it is a print head in which the pressure difference created by the two negative pressure control units 230 and 231 is large or the ink viscosity is lower than the others, and the ink circulation amount of the print element substrate 10 is relatively large.

[0084] Head B is a print head in which the temperature sensor 301 detects a higher temperature than the actual temperature, and the sub-heater 302 is driven weakly. Alternatively, the pressure difference created by the two negative pressure control units 230 and 231 is small, or the ink viscosity is higher than the others, so that the amount of ink circulating in the print element substrate 10 is relatively small.

[0085] In this way, in each recording head 3, a recording position shift in the X direction occurs in response to thermal deformation, and even if an attempt is made to record a straight ruled line, a warped ruled line is recorded. Furthermore, when these recording heads record an image in the same area of ​​the recording medium, the difference in the amount of bending appears as a recording position shift in the X direction. In the case of FIG. 16(a) where both ends of the recording head are fixed, the recording position shift in the X direction is greatest at the center of the recording head 3. In the case of FIG. 16(b) where the center of the recording head is fixed, the recording position shift in the X direction is greatest at both ends of the recording head 3. Such a recording position shift can be on the order of several hundred μm, raising concerns about a decrease in image quality.

[0086] (First embodiment) 17 is a flowchart for explaining the process of correcting the print position deviation in this embodiment. This process is executed by the control unit 500 in accordance with a program stored in the ROM (see FIG. 2). This process is executed when the printing device 1000 is shipped, and also when the print head 3 is replaced, when the print position deviation becomes noticeable, and other times as appropriate.

[0087] When this process is started, first in step S1, the control unit 500 performs temperature control for all the recording heads 3 under the same conditions as during normal recording operation, and then waits until thermal expansion reaches a steady state.

[0088] In step S2, the control unit 500 records a predetermined test pattern on the recording medium. The test pattern is not particularly limited as long as it can confirm the relative amount of misalignment of each recording element substrate 10 in the X direction.

[0089] In step S3, the control unit 500 acquires the amount of recording position deviation in the X direction of each recording element substrate 10. The amount of recording position deviation can be acquired by the control unit 500 reading the test pattern using a reading sensor (not shown) provided in the device and calculating the difference in the X direction from a reference position. Alternatively, a user or a service person may visually determine the difference between the test pattern output in step S2 and the reference pattern and input the determination result to the device.

[0090] In step S4, the control unit 500 sets a correction value for each recording element substrate 10. This correction value corresponds to the shift amount from the standard value of the timing at which a pulse voltage is applied to the recording elements 15. That is, when the correction value is +Δt, the drive timing of the recording element substrate 10 after the correction is delayed by Δt from the standard. Also, when the correction value is -Δt, the drive timing of the recording element substrate 10 after the correction is advanced by Δt from the standard. Such a correction value can be calculated based on the recording position deviation amount obtained in step S3, the conveying speed of the recording medium, the ink ejection speed, and the distance between the recording medium and the ejection port surface.

[0091] In step S5, the control unit 500 stores in a memory the correction values ​​for each recording element substrate 10 set in step S4. The memory may be the ROM 501, or may be a storage means provided separately from the ROM 501. This ends the process.

[0092] The above steps S1 to S5 are performed for each of the multiple recording heads 3 mounted on the recording device 1000. In this case, the steps S1 to S4 may be performed sequentially for the multiple recording heads 3, or may be performed simultaneously in parallel.

[0093] Thereafter, when a recording command is input to the recording device 1000, the control unit 500 reads out the correction values ​​for each recording element substrate 10 stored in the memory. Then, while controlling the drive timing according to the correction values, an image is recorded on the recording medium according to the image data. This makes it possible to record an image on the recording medium S with reduced recording position deviation.

[0094] Figures 18(a) and (b) are diagrams for explaining the effect of correcting the print position deviation in this embodiment. Figure 18(a) shows the print state before the correction process is performed, and Figure 18(b) shows the print state after the correction process is performed. Figure 18(a) is the same as Figure 16(a), and shows the print state of the ruled lines when both ends of the print head are fixed.

[0095] In the case of head A, as shown in FIG. 18(a), the recording position at the center is shifted in the +X direction from the recording positions at the ends. For this reason, in the correction process, the drive timing of the recording element substrate 10 located at the center is corrected so as to be delayed from the drive timing of the recording element substrate 10 located at the ends. In this case, the amount of correction is larger toward the center and smaller toward the ends. By performing such correction process, the recording positions in the X direction are aligned for all of the recording element substrates 10 arranged in head A, and ideal ruled lines extending in the Y direction are obtained as shown in FIG. 18(b).

[0096] The same is true for head B, except that the amount of correction for head B is generally smaller than that for head A. Since head A and head B can each record an ideal straight line in an ideal position, the recording position deviation between head A and head B is also reduced.

[0097] As described above, the correction process of this embodiment makes it possible to suppress misregistration of the recording positions within each recording head 3 and between recording heads, and to record high-quality images without color misregistration.

[0098] Second embodiment In this embodiment, as in the first embodiment, the recording device 1000 and the recording head 3 described with reference to Figures 1 to 14 are used. However, in this embodiment, the correction value of the recording head is set taking into consideration the deformation difference caused by the difference in the ejection frequency.

[0099] <Expansion difference due to difference in discharge frequency> FIG. 19 is a diagram for explaining the difference in deformation of the print head due to differences in ejection frequency. Here, the ruled lines printed in the maximum drive state and the ruled lines printed in the minimum drive state are compared for each of head A and head B. For the sake of convenience, the state in which all the print elements 15 used for printing are driven at the maximum drive frequency to eject a large amount of ink is referred to as the maximum drive state. Also, the state in which the minimum ejection operation is performed to enable confirmation of the print position on the print medium is referred to as the minimum drive state.

[0100] Even for the same print head, the amount of print position deviation varies depending on the ejection frequency. The higher the ejection frequency, the less the amount of ink circulation as the heated ink is discharged to the outside, suppressing thermal deformation and reducing the amount of deviation in the X direction. Here, the amount of deviation in the X direction in the minimum drive state at the center of head A is shown as Xa1, and the amount of deviation in the X direction in the maximum drive state is shown as Xb2. Also, the amount of deviation in the X direction in the minimum drive state at the center of head B is shown as Xb1, and the amount of deviation in the X direction in the maximum drive state is shown as Xb2. That is, if no correction process is performed, the center of head A during printing operation is displaced between Xa1 and Xa2, and the center of head B is displaced between Xb1 and Xb2. In this case, a maximum color deviation of ΔDmax=|Xa1-Xb2| occurs between head A with large thermal deformation and head B with small thermal deformation. ΔDmax is a larger deviation than the maximum print position deviation in FIG. 16, which is compared in one drive state.

[0101] In this embodiment, the deviation in printing position of each print head is reduced while taking into consideration the difference in expansion caused by the difference in ejection frequency described above.

[0102] 20 is a flowchart for explaining the process of correcting the print position deviation in this embodiment. This process is executed by the control unit 500 in accordance with a program stored in the ROM (see FIG. 2). This process is executed when the printing device 1000 is shipped, and also when the print head 3 is replaced, when the print position deviation becomes noticeable, and other times as appropriate.

[0103] When this process starts, the control unit 500 first performs temperature control processing under maximum drive conditions in step S11. Specifically, each recording element substrate 10 of the recording head 3 is heated to a temperature control temperature for normal recording operation, and then all recording elements are driven at the maximum drive frequency while performing a predetermined circulation control.

[0104] After the thermal expansion reaches a steady state, the process proceeds to step S12, where the control unit 500 records the test pattern read out from the ROM 501 onto the recording medium.

[0105] In step S13, the control unit 500 acquires the amount of recording position deviation in the X direction of each recording element substrate 10 in the maximum driving state. The method of acquiring the amount of recording position deviation is the same as that of the first embodiment. That is, the amount of recording position deviation may be acquired using a reading sensor (not shown) provided in the device, or the amount of recording position deviation may be acquired by a user or a service person inputting the judgment result into the device.

[0106] In steps S14 to S16, the control unit 500 sets the correction value of each recording element substrate 10 in the minimum drive state. That is, first, in step S14, each recording element substrate 10 of the recording head 3 is heated to a temperature controlled for normal recording operation, and then a predetermined circulation control is performed without driving the recording elements or at a minimum drive frequency at which the recording position can be confirmed on the recording medium. Then, when a steady state is reached, the control unit 500 records a test pattern on the recording medium in step S15, and further acquires the amount of recording position deviation in the X direction of each recording element substrate 10 in the minimum drive state in step S16.

[0107] In step S17, the control unit 500 sets a correction value for each recording element substrate 10 based on the amount of recording position deviation in the maximum driving state acquired in step S13 and the amount of recording position deviation in the minimum driving state acquired in step S16.

[0108] 21(a) and (b) are diagrams for explaining a method of setting the correction value performed by the control unit 500 and the effect of the correction in step S17 of this embodiment. In this embodiment, as shown in FIG. 21(a), the average value of the recording position deviation in the maximum driving state and the recording position deviation in the minimum driving state is obtained for each recording element substrate 10. Then, a correction value for making the average deviation amount 0 is set as the correction value for that recording element substrate. For example, at the center of head A, the average deviation amount is (Xa1+Xa2) / 2. Therefore, a correction value for making this deviation 0 is set. At the center of head B, the average deviation amount is (Xb1+Xb2) / 2. Therefore, a correction value for making this deviation 0 is set.

[0109] Returning to the description of the flowchart in Fig. 20, in step S18, the control unit 500 stores the correction values ​​of each recording element substrate 10 set in step S17 in a memory. The memory may be the ROM 501, or may be a storage means provided separately from the ROM 501. This ends the process.

[0110] 21 is performed for each of the multiple recording heads 3 mounted on the recording device. In this case, each step may be performed sequentially for the multiple recording heads 3, or may be performed simultaneously in parallel.

[0111] Thereafter, when a print command is input to the printing device 1000, the control unit 500 reads out the correction values ​​for each printing element substrate 10 stored in the memory. Then, while controlling the drive timing according to the correction values, an image is printed on the printing medium according to the image data.

[0112] Fig. 21(b) shows the state where ruled lines are printed according to the set correction value. The correction performed on each printing element substrate 10 is a correction for making the average amount of deviation in the minimum drive state and the maximum drive state zero. Therefore, in the minimum drive state, the correction is slightly insufficient, and ruled lines that are slightly curved on the +X side are printed. In the maximum drive state, the correction is slightly excessive, and ruled lines that are slightly curved on the -X side are printed. Also, in a drive state between the maximum drive state and the minimum drive state, an approximately straight ruled line is printed.

[0113] More specifically, according to the correction process of this embodiment, the print position deviation from the ideal position falls within the range of ±|Xa1-Xa2| / 2 for head A, and within the range of ±|Xb1-Xb2| / 2 for head B. This means that the maximum deviation from the ideal print position is halved compared to the first embodiment, which does not take into account variations in ejection frequency. Also, the maximum print position deviation ΔDmax' between head A and head B can be reduced compared to ΔDmax.

[0114] In this way, according to the correction process of this embodiment, regardless of the ejection frequency of each print head, print position misalignment within each print head and print position misalignment between print heads can be suppressed, making it possible to print high-quality images without color misalignment.

[0115] In the above, the average value of the print position deviation in the maximum drive state and the print position deviation in the minimum drive state is set as the deviation amount to be corrected (hereinafter, the deviation amount to be corrected), but the deviation amount to be corrected does not have to be the average value. The deviation amount to be corrected may be obtained by multiplying the print position deviation in the maximum drive state and the print position deviation in the minimum drive state by an arbitrary weighting coefficient. For example, for an ink color such as yellow whose dots are not noticeable in the minimum drive state, the weighting coefficient of the print position deviation in the maximum drive state may be made larger than the weighting coefficient of the minimum drive state to obtain the deviation amount to be corrected. Also, for ink that rarely has the opportunity to be in the maximum drive state in the ejection data after image processing, the weighting coefficient of the print position deviation in the minimum drive state may be made larger than the weighting coefficient of the maximum drive state to obtain the deviation amount to be corrected.

[0116] Furthermore, in the above, the deviation amount to be corrected is calculated based on the print position deviation at two points, the maximum drive state and the minimum drive state, but the deviation amount to be corrected may be calculated from another drive state. That is, the deviation amount to be corrected may be calculated by taking a weighted average of the print position deviation obtained at a relatively high arbitrary drive frequency and the print position deviation obtained at a relatively low arbitrary drive frequency. The deviation amount to be corrected may be appropriately adjusted based on the conspicuousness of the print position deviation and the frequently used drive frequency so that the print position deviation of each print head and the color deviation between print heads are not noticeable.

[0117] (Third embodiment) In the second embodiment, the print position deviation was measured in each of the maximum drive state and the minimum drive state for each print head 3. However, such a measurement requires that the temperature control process and the ejection operation be continued until the thermal deformation of each print head stabilizes, which consumes a great deal of time and ink.

[0118] Therefore, in this embodiment, for each print head, the print position deviation is actually measured in a steady state where intermediate thermal deformation between the maximum drive state and the minimum drive state, i.e., intermediate print position deviation, is obtained, and a correction value for each head is set based on the print position deviation. Specifically, in the print head 3, the print elements 15 are not driven, and the print element substrate 10 is adjusted to a temperature lower than the set temperature (65°C) in normal printing operation, thereby reproducing intermediate thermal expansion. Hereinafter, the state where intermediate thermal deformation between the maximum drive state and the minimum drive state is obtained is called the intermediate state.

[0119] <How to recreate the intermediate state> 22 is a diagram showing the relationship between the circulation amount Vs and the controlled temperature Ts for reproducing the intermediate state. The horizontal axis indicates the circulation amount Vs, and the vertical axis indicates the controlled temperature Ts of the recording element substrate 10. In the following description, the total amount of ink flowing per unit time to the multiple recording element substrates 10 arranged in the Y direction in the recording head 3 is referred to as the circulation amount Vs. Also, the target temperature that is set in common to the multiple recording element substrates 10 arranged in the Y direction and adjusted by the temperature sensor 301 and the sub-heater 302 (see FIG. 2) is referred to as the controlled temperature Ts. In general recording operations, the controlled temperature is set to 65° C.

[0120] In Fig. 22, the relationship between the circulation amount Vs and the controlled temperature Ts that can reproduce the intermediate state obtained by the thermal-fluid-structure coupling simulation is plotted. Such a relationship between the circulation amount Vs and the controlled temperature Ts can be approximated by a cubic function having a minimum value α and a maximum value β, and Fig. 22 also shows the cubic function obtained as an approximation. In this embodiment, the temperature Ti of the ink flowing through the recording apparatus 1000 is controlled to between 28°C and 32°C by the heat exchanger, and the figure shows the cases where the ink temperature T is 28°C and 32°C as legends.

[0121] Here, the cubic function Ts(Vs) of the controlled temperature Ts can be expressed by the following general formula using coefficients a, b, c, and d.

[0122]

number

[0123] However, in the case of (Equation 1), the coefficients a, b, c, and d also change according to the ink temperature Ti, but the values ​​of the coefficients a, b, c, and d corresponding to an arbitrary ink temperature Ti cannot be linearly calculated from the ink temperature Ti being 28° C. and the ink temperature being 32° C. Therefore, in this embodiment, the following (Equation 2) using a minimum value α and a maximum value β is used as the cubic function Ts(Vs) of the controlled temperature Ts.

[0124]

number

[0125] By using (Equation 2), the values ​​of the coefficients a, α, and β corresponding to an arbitrary ink temperature Ti can be linearly determined from the cases where the ink temperature T is 28° C. and 32° C. The coefficients a, α, and β when the ink temperature T is 28° C. and 32° C. are determined in advance by simulation.

[0126] In this embodiment, for any ink temperature Ti between 28° C. and 32° C., the coefficients a, α, and β can be calculated using the following (Equation 3).

[0127]

number

[0128] That is, in this embodiment, the above cubic function of any print head 3 can be derived by measuring the temperature Ti of ink circulating in the printing apparatus 1000 via that print head 3. Then, by using the derived cubic function, the controlled temperature Ts for reproducing intermediate thermal deformation in that print head 3 can be found based on the circulation amount Vs of the printing element substrate 10.

[0129] Next, a method for measuring the circulation volume Vs will be described.

[0130] 23(a) to (c) are diagrams for explaining the relationship between the circulation amount Vs and the flow rate of ink in the ejection unit 300. In FIG.

[0131] 23(a) is a diagram showing a schematic diagram of ink circulation. A first negative pressure control unit 230 that generates a relatively high pressure is connected to the common supply flow path 211, and a second negative pressure control unit 231 that generates a relatively low pressure is connected to the common recovery flow path 212. Therefore, a flow from the common supply flow path 211 toward the common recovery flow path 212 is generated in the recording element substrate 10, and the total flow rate that passes through the multiple recording element substrates 10 is the circulation amount Vs. The circulation amount Vs is controlled based on the tolerances of the differential pressure created by the first and second negative pressure control units 230 and 231, the liquid viscosity, the flow path resistance, and the like, and is adjusted to 25 to 255 ml / min in this embodiment.

[0132] In this embodiment, when a discharge operation is performed on each recording element substrate 10, ink is supplied to the recording element substrate 10 from the common supply flow path 211 and the common recovery flow path 212 at a ratio of approximately 6:4. The amount of ink consumed during the discharge operation is 0 to 308 ml / min. Note that this maximum value of 308 ml / min is an average value taking into account the instantaneous actual consumption of 375 ml / min when driven at the highest drive frequency and the non-discharge period when switching pages. However, these numerical values ​​can be changed as appropriate depending on the flow path shape, etc.

[0133] 23(b) and (c) show the relationship between the circulation amount Vs and the upstream flow rate Q1 of the common supply passage 211 and the relationship between the circulation amount Vs and the upstream flow rate Q2 of the common recovery passage 212, respectively.

[0134] Such a relationship between the upstream flow rates Q1, Q2 and the circulation amount Vs can be actually measured by installing flow meters at a total of four locations upstream and downstream of the common supply flow path 211 and the common recovery flow path 212. Specifically, the circulation amount Vs is the difference between the measurement values ​​of two flow meters installed upstream and downstream of the common supply flow path 211, i.e., the difference between the upstream flow rate and the downstream flow rate. Similarly, the circulation amount Vs can also be the difference between the measurement values ​​of two flow meters installed upstream and downstream of the common recovery flow path 212. The average value of these two differences may also be used as the circulation amount Vs.

[0135] 23(b) and (c), the minimum required flow rate determined by the amount of ink that may be consumed by the recording element substrate 10, the maximum allowable flow rate determined by the conditions for normally operating the negative pressure control unit, and the set flow rate of this embodiment are shown as legends. All of these have a linear relationship with the circulation amount Vs. That is, in the recording head 3 of this embodiment, the circulation amount Vs of the recording element substrate 10 can be adjusted by controlling the first to third circulation pumps P1 to P3 described in FIG. 3 while checking the measurement value of the flow meter. In addition, the circulation amount Vs of the recording head 3 can be obtained based on the graphs of FIG. 23(b) and (c) from the actual measurement values ​​of the upstream flow rate Q1 of the common supply flow path 211 and the upstream flow rate Q2 of the common recovery flow path 212 of the target recording head 3.

[0136] That is, in this embodiment, the intermediate state of any recording head 3 can be reproduced by the following procedure. First, the ink temperature Ti and the circulation amount Vs of the target recording head 3 are measured. At this time, the upstream flow rate Q1 of the common supply flow path 211 and the upstream flow rate Q2 of the common recovery flow path 212 are actually measured, and the circulation amount Vs is obtained based on the graphs of FIG. 23(b)(c). Next, using the measured ink temperature Ti, a cubic function of the target recording head 3 is derived according to (Equation 2) and (Equation 3). Then, according to the derived cubic function, the temperature control temperature Ts corresponding to the circulation amount Vs is obtained (see FIG. 22). Finally, the temperature of each recording element substrate 10 of the target recording head 3 is adjusted to the above temperature control temperature Ts, and a steady state is waited for. As a result, an intermediate state in which the thermal expansion is intermediate between the maximum drive state and the minimum drive state can be reproduced in the target recording head 3.

[0137] <How to set the correction value> Next, a method for setting a correction value for each recording element substrate 10 based on the recording position deviation obtained in the above-mentioned intermediate state will be described.

[0138] Fig. 24 is a flowchart for explaining the process of correcting the print position deviation in this embodiment. The only difference from the flowchart in Fig. 17 explained in the first embodiment is the temperature adjustment process in step S21.

[0139] In step S21, the control unit 500 performs a temperature control process in an intermediate state. Specifically, each recording element substrate 10 of the recording head 3 is heated to the temperature control temperature Ts obtained by the above-mentioned method, and then a predetermined circulation control is performed without driving the recording elements 15.

[0140] The following steps S22 to S25 are similar to steps S2 to S5 in FIG. 17, and therefore the description thereof will be omitted.

[0141] In this embodiment, in step S24, a correction value for correcting the recording position deviation in the intermediate state is set. Therefore, after the correction process, the same effect as in the second embodiment can be obtained. That is, according to this embodiment, the correction process can be completed in a shorter time than in the second embodiment while obtaining the same effect as in the second embodiment.

[0142] In the second embodiment, in a print head that is inherently less prone to thermal deformation, the difference in print position deviation between the maximum drive state and the minimum drive state is lost in the measurement error, and an appropriate correction target deviation amount may not be set. In a configuration in which the print position deviation is measured in a single drive state as in the present embodiment, it is possible to obtain the correction target deviation amount with higher accuracy.

[0143] As described above, according to this embodiment, by measuring only the printing position deviation in the intermediate state, printing position deviation within each printing head 3 and printing position deviation between printing heads can be suppressed, regardless of the ejection frequency of each printing head, thereby making it possible to print high-quality images.

[0144] In the above, the case where the controlled temperature Ts is approximated by a cubic function of the circulation volume Vs has been described with reference to Fig. 22. However, depending on the circulation control that is the premise, it may be preferable to approximate such a function by a function other than the cubic function. In any case, as long as an approximation function that determines the controlled temperature Ts with respect to the circulation volume Vs can be obtained based on the relationship obtained by simulation or actual measurement, any function may be applied.

[0145] 23(b) and (c) have been described with respect to a case in which the upstream flow rate Q1 of the common supply flow path 211 and the upstream flow rate Q2 of the common recovery flow path 212 each change continuously with respect to the circulation amount Vs. However, in this embodiment, such continuity is not an essential requirement. If the upstream flow rate Q1 of the common supply flow path 211 and the upstream flow rate Q2 of the common recovery flow path 212 change discontinuously with respect to the circulation amount Vs, they may be expressed by a plurality of discontinuous functions. In any case, it is sufficient that the circulation amount Vs is uniquely determined with respect to the actually measured Q1 and Q2.

[0146] In the above, a function of the controlled temperature Ts and the circulation amount Vs as shown in Fig. 22 was derived according to (Equation 3) in association with the ink temperature Ti, and then the controlled temperature Ts was obtained from the circulation amount Vs using the function. However, these procedures can also be reversed. That is, a function of the controlled temperature Ts and the ink temperature Ti may be derived in association with the circulation amount Vs, and the controlled temperature Ts may be obtained from the ink temperature Ti using the function.

[0147] Furthermore, in the above, the controlled temperature Ts corresponding to the ink temperature Ti and the circulation amount Vs is calculated using functions such as (Equation 2) and (Equation 3), but the controlled temperature Ts may be obtained by referring to a lookup table. In this case, a three-dimensional lookup table in which the ink temperature Ti, the circulation amount Vs, and the controlled temperature Ts correspond to each other may be prepared in advance. Such a lookup table can be created by actually measuring the relationship between the controlled temperature Ts and the thermal deformation of the print head 3 or by performing a thermal-fluid-structure coupling simulation.

[0148] In the above, the intermediate state where the intermediate thermal deformation is obtained is reproduced by adjusting the controlled temperature Ts, but such an intermediate state can also be reproduced by adjusting the drive conditions, for example, by setting the drive frequency to approximately half that of the maximum drive state. In any case, if the intermediate state where the intermediate thermal expansion is obtained is reproduced and then the print position deviation can be actually measured, it becomes possible to set an appropriate correction value for each print head 3, and the effect of this embodiment can be obtained.

[0149] Furthermore, in this embodiment, as in the second embodiment, the deviation amount to be corrected may be adjusted appropriately for each print head based on how noticeable the print position deviation is, the driving frequency that is frequent, etc. If the temperature adjustment process in step S21 is performed under driving conditions that obtain the deviation amount to be corrected, the effect of this embodiment can be obtained.

[0150] (Other embodiments) In the above embodiment, the correction value is set for each recording element substrate, but the unit of correction can be changed as appropriate. A correction value may be set for a plurality of adjacent recording element substrates as one unit, or the recording element substrate may be divided into a plurality of areas, and a correction value may be set for each of these areas.

[0151] In the above, the ink temperature Ti flowing through the printing apparatus 1000 is maintained at 28°C to 32°C by the heat exchanger, and the controlled temperature Ts of the printing element substrate 10 in normal printing operation is set to 65°C. However, such temperatures can be changed. However, if the difference between the ink temperature Ti and the controlled temperature Ts is too small, the difference in thermal deformation between the print heads caused by the temperature control process and circulation control may not be very noticeable. In order to fully exert the effects of the above embodiment, it is preferable that the controlled temperature Ts in printing operation is 10°C or more higher than the ink temperature Ti.

[0152] In the above embodiment, a method for correcting the print position deviation in the X direction caused by the temperature difference between the ink flowing in the common supply flow path 211 and the common recovery flow path 212 has been described with reference to Fig. 15. However, in a long print head 3 that circulates ink while heating the print element substrate between the print head 3 and the printing device 1, print position deviation in the X direction may occur due to thermal factors other than those mentioned above. In any case, by adopting the above embodiment in which the correction process is performed after the thermal expansion of the print head 3 reaches a steady state, it is possible to obtain the effect of reducing the dynamically changing print position deviation.

[0153] In addition, although the above description has been given taking as an example a full-line type inkjet recording device equipped with four recording heads 3 that eject ink of different colors, the above-mentioned method of correcting the recording position can also be adopted in recording devices of other types. For example, the recording device may be in a form equipped with five or more recording heads that eject ink of five or more colors, or in a form equipped with one recording head that ejects ink of one color.

[0154] In the above, a print head compatible with A3 size and B2 size has been given as an example with reference to FIG. 4 and FIG. 5, but the length of the print head is not particularly limited. In addition, the print head does not necessarily have to be a line type print head mounted on a full line type printing device. Even in a serial type printing device that alternately repeats print scanning of the print head and a conveying operation that conveys the print medium in a direction intersecting the print scanning, if the print head mounted is long, it is expected that a print position deviation due to thermal deformation will occur. Even in such a case, the effect of suppressing the print position deviation can be obtained by setting the correction value of each print head according to the above-mentioned embodiment. However, in order to obtain the effect of correcting the print position deviation due to thermal deformation, it is preferable that the print head has a print width of A3 size or more.

[0155] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0156] 3 Recording head 13 Recording element 10. Recording element board 1000 Recording Device

Claims

1. a recording device including a plurality of recording element substrates, each having a plurality of recording elements arranged continuously in a first direction, a temperature control means for controlling a temperature of the recording element substrates, a circulation means for circulating a liquid through the recording element substrates, a common supply flow path for commonly supplying liquid to the plurality of recording element substrates, and a common recovery flow path for commonly recovering liquid from the plurality of recording element substrates, the recording device using a recording head that thermally expands in response to the temperature control means and the circulation of liquid, and which records an image on a recording medium moving in a second direction intersecting the first direction, the method comprising: an acquisition step of performing temperature control for the plurality of recording element substrates of the recording head by the temperature control means and the circulation means, and acquiring a recording position deviation amount of the recording head in the second direction from a test pattern recorded on a recording medium transported in the second direction by driving the recording elements; a setting step of setting a correction value based on the recording position deviation amount; Including, A method for correcting a printing position, characterized in that the common supply flow path and the common recovery flow path are adjacent to each other in the second direction, and liquid flowing through the common supply flow path and the common recovery flow path flows from one side to the other side in the first direction.

2. 2. The method for correcting a print position according to claim 1, wherein in the setting step, the correction value is set for each of the plurality of print element substrates or for a group of adjacent print element substrates.

3. 3. The method of correcting a print position according to claim 1, wherein the correction value indicates a shift amount of a timing for driving the print element from a standard value.

4. 4. The method for correcting a print position according to claim 1, wherein the printhead applies a pulse voltage to the print element to cause film boiling in the liquid, and ejects the liquid by using growth energy of bubbles generated.

5. 5. The method for correcting a print position according to claim 1, wherein the temperature of the print element substrate adjusted when performing a printing operation is 10[deg.] C. or more higher than the temperature of the liquid before it is supplied to the print head.

6. 6. The method for correcting a print position according to claim 1, further comprising the step of storing the correction value set in the setting step in a storage means.

7. A step of reading out the correction value set in accordance with the method for correcting a recording position according to any one of claims 1 to 5 from a storage means; using the correction value to record an image on a recording medium according to image data; A recording method comprising the steps of:

8. The method for correcting the recording position according to any one of claims 1 to 5 is executed by a computer. A program to make this possible.

Images