Printing position correction method, printing method, printing 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 method for correcting a print position, a printing method, a printing apparatus, and a program. [Background technology]

[0002] Some long inkjet print heads, such as those used in line-type printing devices, are made by connecting multiple ejection modules. In such long print heads, misalignment between the ejection modules occurs in the short direction, which intersects with the long direction, and this can cause image degradation.

[0003] Patent Document 1 discloses a method for reducing misalignment of print positions in the width direction by adjusting the ejection timing of print elements arranged in the length 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, while 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 print heads that circulate ink between the print head and the printing device to maintain normal ejection operation, the heat distribution of the print head and the resulting 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 its purpose is to reduce the 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. [Means for solving the problem]

[0007] To this end, the present invention provides a method for correcting a print position in a second direction of a printing apparatus that includes a plurality of printing element substrates, each having a plurality of printing elements arranged continuously in a first direction, a temperature control unit for controlling the temperature of the printing element substrates, a circulation unit for circulating a liquid through the printing element substrates, a common supply flow path for commonly supplying liquid to the plurality of printing element substrates, and a common recovery flow path for commonly recovering liquid from the plurality of printing element substrates, and that uses a print head that thermally expands in response to the temperature control unit and the circulation of the liquid, and that prints an image on a printing medium that moves in a second direction intersecting the first direction, the method comprising: an acquisition step of acquiring a print position deviation amount of the print head in the second direction from a test pattern recorded on a print medium transported in the second direction by driving the print elements while controlling the temperature of the plurality of print element substrates of the print head by the temperature adjustment means and the circulation means; For each of the plurality of recording element substrates or for a plurality of adjacent recording element substrates as a unit, and a setting process for setting a correction value, wherein 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. [Effects 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 explanation of the drawings]

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

[0010] (First embodiment) <Overall configuration of the recording device> 1(a) and (b) are diagrams showing an example of a printing apparatus that can be used in this embodiment. The printing apparatus of this embodiment is an inkjet printing apparatus (hereinafter simply referred to as the printing apparatus) 1000 that prints a color image on a printing medium S by ejecting cyan (C), magenta (M), yellow (Y), and black (Bk) inks. In the figure, the X direction is the conveyance direction of the printing medium S, the Y direction is the width direction of the printing 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 directly applies ink to a recording medium S transported in the X direction. The recording medium S is mounted on a transport unit 1 and 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 ports 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 onto a recording medium S via an intermediate transfer drum 2. The four recording heads 3, which eject different inks, are arranged so that their ejection port surfaces 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 the nip portion between the intermediate transfer drum 2 and a transfer roller 5, the ink applied to the intermediate transfer drum 2 is transferred onto 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 illustrating the control configuration of the recording apparatus 1000. The control unit 500 is composed of a CPU and other components, and controls the entire recording apparatus 1000 while using a RAM 502 as a work area in accordance with programs and various parameters stored in a 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. The control unit 500 then drives the recording head 3 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. Information about the use areas of the ejection ports used for ejection in the print head 3 is stored in the ROM 501 in a rewritable manner for each print head 3. The method for setting the use areas will be explained in detail later.

[0016] Although not shown in FIG. 2, the print head 3 has an array of multiple printing element substrates 10 (see FIGS. 3 and 4). Each printing element substrate 10 is provided with a temperature sensor 301 for detecting the temperature of the printing element substrate 10 and multiple sub-heaters 302 for heating the printing element substrate 10 to a predetermined set temperature. For ease of explanation, FIG. 2 shows the multiple temperature sensors 301 and sub-heaters 302 collectively. When performing a printing operation, the control unit 500 drives the sub-heaters 302 based on the temperature detected by the temperature sensor 301, thereby maintaining each printing element substrate 10 at an appropriate temperature. In this embodiment, the printing element substrate 10 is maintained at 65°C during a typical printing 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 the system for circulating the ink under the management of the control unit 500. 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 due to buoyancy and are released into the atmosphere.

[0020] The print head 3 of this embodiment has a discharge unit 300 that discharges ink in accordance with discharge data, and two liquid supply units 220 that adjust the pressure of the ink supplied to the discharge unit 300. The two liquid supply units 220 are each provided with a first negative pressure control unit 230 and a second negative pressure control unit 231 that control the pressure of the ink flowing to the discharge unit 300.

[0021] 3(a) shows an example in which the first negative pressure control unit 230 and the second negative pressure control unit 231 are arranged upstream of the ejection unit 300 in the flow of ink. After being discharged by the first circulation pump P1, the ink stored in the buffer tank 1001 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 via their respective filters 221.

[0022] The first negative pressure control unit 230 has a control pressure set to a weak negative pressure (a 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 (a 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 shown as H and the second negative pressure control unit 231 is shown 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 unit 300 ejects ink, i.e., the image duty. By providing the first negative pressure control unit 230 and the second negative pressure control unit 231 upstream of the ejection unit 300 as in this embodiment, the ink pressure in the ejection unit 300 can be maintained within a constant range regardless of the image duty.

[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. Because 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, an ink flow is formed from the individual supply flow path 213a toward the individual recovery flow path 213b.

[0026] In the ink circulation configuration described above, the first circulation pump P1 is preferably one that can obtain a certain level of head pressure or higher within the range of ink circulation flow rate achieved 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 that is arranged with a certain water head difference relative 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 can be positive displacement pumps capable of delivering a constant amount of liquid. Specific examples include tube pumps, gear pumps, diaphragm pumps, and syringe pumps. Alternatively, a general constant flow valve or 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 can employ 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 influence of the hydraulic head pressure of the buffer tank 1001 on the discharge unit 300 can be suppressed, thereby improving the degree of freedom in the layout of the buffer tank 1003 in the recording apparatus 1000.

[0029] In the discharge unit 300 shown in FIG. 3(a), when the recording apparatus 1000 is performing a recording operation, a constant amount of ink flows through each recording element substrate 10, regardless of whether or not there is 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 arranging the ink flow direction in the common supply flow channel 211 and the ink flow direction in the common recovery flow channel 212 in opposite directions, heat exchange between these opposing flow channels can be promoted. As a result, the temperature gradient in the longitudinal direction (Y direction) within the recording head 3 can be reduced, and variations in the discharge amount of the multiple recording element substrates 10 can be suppressed.

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

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

[0032] In Figure 3(b), ink flows in the opposite direction to that in Figure 3(a). That is, 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 into the buffer tank 1001 via the first negative pressure control unit 230 by the first circulation pump P1, which acts as a negative pressure source. The ink that has passed through the common recovery flow path 212 is recovered into the buffer tank 1001 via the second negative pressure control unit 231 by the first circulation pump P1, which acts as a negative pressure source.

[0033] The first negative pressure control unit 230 and the second negative pressure control unit 231 in FIG. 3(b) can employ a mechanism similar to a so-called "back pressure regulator." By providing the first negative pressure control unit 230 and the second negative pressure control unit 231, which function as back pressure regulators, downstream of the discharge unit 300, the ink pressure in the discharge unit 300 can be maintained within a constant range regardless of the image duty. As with the configuration in FIG. 3(a), the configuration in FIG. 3(b) can also suppress the effect of the head pressure of the buffer tank 1001 on the discharge unit 300, thereby increasing the degree of freedom in the layout of the buffer tank 1003 in the recording apparatus 1000.

[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, let Qa be the flow rate required to circulate ink in the discharge unit 300 when no discharge operation is performed. The flow rate Qa is defined as the minimum flow rate required to maintain the discharge unit 300 at an appropriate temperature when the recording apparatus 1000 is in standby mode. Also, let Qb be the flow rate of ink consumed by the discharge unit 300 when all discharge ports are performing discharge operations at maximum frequency.

[0037] In the configuration of FIG. 3(a), the sum of the set flow rates of the high-pressure side second circulation pump P2 and the low-pressure side third circulation pump P3 is Qa. Therefore, when all nozzles are ejected at the maximum frequency, the maximum amount of ink supplied to the ejection unit 300 is Qa + Qb. In contrast, in the configuration of FIG. 3(b), the sum of the set flow rates of the high-pressure side second circulation pump P2 and the low-pressure side third circulation pump P3 can be the larger of Qa and Qb. In other words, the configuration of FIG. 3(b) can reduce the total amount of circulated ink and, therefore, the pump power, compared to the configuration of FIG. 3(a), thereby increasing the flexibility of the applicable circulation pump. This effect becomes more pronounced as Qa and Qb increase, i.e., the line head size increases.

[0038] On the other hand, in the configuration of FIG. 3(b), the negative pressure acting on each nozzle is greater than 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 flow rate through the ejection unit 300 is the same as the flow rate when no ejection operation is performed, and the lower the image duty, the greater the negative pressure acting on each ejection port. As a result, satellites occur at each ejection port even in images with low duty, and these satellites are more noticeable in images with low duty. This tendency becomes particularly pronounced when the widths of the common supply channel 211 and the common recovery channel 212 are reduced to reduce the size of the liquid ejection head. In contrast, in the configuration of FIG. 3(a), the negative pressure acting on each nozzle is greater when the duty is high. In this case, even if satellites occur, they are less noticeable in images with high duty.

[0039] The ink circulation configuration of this embodiment can be either one of those shown in Figures 3(a) and 3(b), taking into consideration the respective characteristics described above. While Figures 3(a) and 3(b) show ink circulation configurations for one color of ink, in practice, such configurations are provided for each ink color. Furthermore, in the above description, the liquid flows in opposite directions in the common supply flow channel 211 and the common recovery flow channel 212 to reduce the temperature gradient in the longitudinal direction (Y direction) within the print head 3, but these directions may also be the same.

[0040] <Recording head configuration> 4(a) and 4(b) are external perspective views of a print head 3 that can be used in this embodiment. FIG. 4(a) is a view of the print head 3 viewed obliquely from below, and FIG. 4(b) is a view of the print head 3 viewed obliquely from above. The print head 3 is provided with print head support sections 80 on both sides in the Y direction, which is the longitudinal direction, to ensure rigidity. Each of these two print head support sections 80 houses the liquid supply unit 220 described in FIG. 3(a) and 3(b). In the figures, the first negative pressure control unit 230 and the second negative pressure control unit 231 protrude above the print head support section 80 (in the +Z direction). The print head support section 80 is provided on its underside with a liquid connection section 111 for connection to a buffer tank 1001.

[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. Each recording element substrate 10 has 20 ejection port arrays arranged in parallel in the X direction, each array having a plurality of ejection ports arranged in the Y direction (see FIG. 10).

[0042] Electrical 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 shorter side direction. Each of the recording element substrates 10 is connected to the electrical wiring boards 90 on both sides via a flexible wiring board 40. Each electrical wiring board 90 is provided with two power supply terminals 92 for receiving power from the main body of the recording apparatus 1000 and four signal input terminals 91 for receiving ejection signals. By consolidating the wiring using the electrical circuit within the electrical wiring board 90, the number of signal input terminals 91 and power supply terminals 92 can be kept smaller than the number of recording element substrates 10, simplifying the connection work when attaching or detaching the recording head 3 to or from the recording apparatus 1000.

[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 a 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 3(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 3(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, provides the rigidity of the recording head 3. The material of the second flow path member 60 is preferably one that has sufficient corrosion resistance to liquids 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 plurality of recording element substrates 10 and a sealant 110 (see FIG. 9) for sealing the connection portions between each recording element substrate 10 and the flexible wiring substrate 40 are exposed. The frame portion around the cover opening 131 functions as an abutment surface when a cap provided on the recording apparatus 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, sealant, filler, or the like around the cover opening 131 so as to fill in 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 underside 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. Note that a joint rubber 100 is arranged at the connection part between the liquid supply unit 220 and the discharge unit 300 to prevent ink leakage.

[0047] 6 is a diagram showing the state in which the recording head 3 is mounted on the carriage 70 provided in the recording device 1000. The carriage 70 has a box-like shape that can mount the recording head 3, and is provided with a movable part 71 that can slide in the Y direction on one side of the carriage 70 in the longitudinal direction, i.e., the Y direction.

[0048] In this embodiment, by providing the movable part 71 on one side of the carriage 70 in this way, 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 surface of the first flow path member 50 that abuts against the recording element substrate 10 is 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 is formed with an individual communication port 53 that is fluidly connected to the second flow path member 60.

[0052] 7(c), the second flow path member 60 has a surface that abuts against the first flow path member 50 formed with communication ports 61 that communicate with the individual communication ports 53 of 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. This common flow path groove 62 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 in fluid communication with the liquid supply unit 220 are formed at both ends of the common flow path groove 62.

[0054] 8(a) and 8(b) are a perspective view and a cross-sectional view for explaining the 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, which extend 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. Furthermore, the recording element substrate 10 of the discharge 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 explained, the common supply flow path 211 is connected to the first negative pressure control unit 230, which has a relatively high pressure, and the common recovery flow path 212 is connected to the second negative pressure control unit 231, which has 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 path 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 path 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 manner, a discharge operation is performed in the recording element substrate 10 in accordance with the discharge data, and the ink supplied through the ink supply path that is not consumed by the discharge operation is recovered through the ink recovery path.

[0057] 9A and 9B are a perspective view and an exploded view of the ejection module 200. The ejection 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 to the terminals 41 of the flexible wiring substrate 40 by wire bonding, and sealing the wire-bonded portion with a sealing material 110. The terminals 42 of the flexible wiring substrate 40, which are 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 has 20 ejection port arrays, i.e., 20 recording element arrays, with 10 arrays on one side and 10 arrays on the other side corresponding to different flexible wiring substrates 40. By connecting the flexible wiring substrates 40 to both sides of the recording element substrate 10 in this manner, the distance between each recording element array on the recording element substrate 10 and the terminals 16 can be minimized, thereby reducing voltage drops and signal transmission delays that occur in the wiring section. However, when the number of recording element arrays is small or when voltage drop is not a significant problem, the flexible wiring board 40 may be disposed on only one side of the recording element board 10 .

[0058] The support member 30 has liquid supply ports 31 serving as openings formed at positions corresponding to the communication paths 51 described in Figures 8(a) and (b) so as to straddle all of the ejection port arrays of the recording element substrate 10. The support member 30 serves as a support for the recording element substrate 10 and also as 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 high flatness and can be bonded to the recording element substrate 10 with sufficiently high reliability. Suitable materials that can be used include alumina and resin materials, for example.

[0059] <Configuration of the recording element substrate> Figures 10(a) to 10(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 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 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, the recording element substrate 10 has terminals 16 formed on both ends in the short direction (±X direction) of the recording head 3 for electrical connection with the flexible wiring substrate 40.

[0061] The ejection orifice forming member 12 has 20 ejection orifice arrays arranged in parallel in the X direction, each array consisting of ejection orifices 13 that eject ink of the same color, arranged in the Y direction. Therefore, ejection data for one pixel only needs to be ejected by any of the 20 ejection orifices located at the same position in the Y direction, making it possible to increase the drive frequency of the recording head 3 while ensuring the drive cycle of each ejection orifice. Furthermore, even if a non-ejecting ejection orifice occurs, the ejection data from that ejection orifice can be distributed to other ejection orifices located at the same position in the Y direction, making it possible to record an image without any missing data.

[0062] FIG. 10(b) is an enlarged view of region Xb shown in FIG. 10(a). In the ejection port forming member 12, partition walls 22 are arranged in the Y direction at a predetermined pitch to form a plurality of pressure chambers 23. 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 terminals 16 by wiring (not shown) provided on the recording element substrate 10. The control unit 500 (see FIG. 2) of the recording apparatus 1000 transmits a pulse voltage in accordance with ejection data, and this pulse voltage is applied to the recording elements 15 via the electrical wiring substrate 90 and the flexible wiring substrate 40. The recording elements 15 then generate heat, causing film boiling in the liquid contained in the pressure chambers 23. The growth energy of the generated bubbles causes some of the ink contained in the pressure chambers 23 to be ejected from the ejection ports 13 to the outside.

[0063] Meanwhile, on both sides of each ejection port array in the X direction, liquid supply paths 18 that are connected to individual supply paths 213a of the flow path member 210 and connected to the plurality of pressure chambers 23, and liquid recovery paths 19 that are connected to individual recovery paths 213b of the flow path member 210 and connected to the plurality of pressure chambers 23 extend in the Y direction. Also, as shown in the cross-sectional view of FIG. 11 , supply ports 17a that communicate with the pressure chambers 23 are formed in the liquid supply paths 18, and recovery ports 17b that communicate with the pressure chambers 23 are formed in the liquid recovery paths 19, corresponding to each pressure chamber 23. Liquid inside the pressure chambers 23 flows between the outside of the pressure chambers 23 via the supply ports 17a and the recovery ports 17b. In other words, fresh ink is supplied to the pressure chambers 23 regardless of whether ink has been ejected from the ejection ports 13 for the ejection operation.

[0064] Furthermore, as shown in FIG. 10(c), the cover plate 20 disposed on the side in contact with the first flow path member 50 has a plurality of openings 21 formed at positions corresponding to the communicating paths 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 in the cover plate 20 for each liquid supply path 18, and two openings 21 are provided in each liquid recovery path 19. As shown in FIG. 10(b), each opening 21 in the cover plate 20 communicates with the plurality of communicating paths 51 shown in FIG. 7(a). Such a cover plate 20 is required to have sufficient corrosion resistance against the liquid (ink) and high layout accuracy for the plurality of openings 21. Therefore, the plurality of cover plates 20 are preferably 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 arranged continuously in the Y direction with their sides abutting each other. At the connection point between the two recording element substrates 10, at least one ejection port 13 located at the extreme end of one recording element substrate 10 and one 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 to achieve this layout. 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 a slight misalignment during the manufacture of the liquid ejection head, the image at the position corresponding to the connection can be recorded by the multiple ejection ports included in the overlapping area. Therefore, black streaks and white areas caused by the misalignment can be made less noticeable in the image recorded on the paper. While the main plane of the recording element substrate 10 has been described as a parallelogram in the above, 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 multiple areas, each of which is provided with a temperature sensor 301 and a sub-heater 302. The control unit 500 (see FIG. 2) uses the temperature sensor 301 and the sub-heater 302 to adjust the temperature based on the temperature set for each area. 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. Setting the target temperature of the recording element substrate 10 to a relatively high temperature reduces the viscosity of the ink, enabling optimal ink ejection and circulation. Furthermore, by performing such temperature control and keeping the temperature variation among the multiple recording element substrates 10 within a predetermined range, variations in the ejection amount caused by temperature variation among the recording element substrates 10 can be reduced, thereby suppressing density unevenness in the printed image.

[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 of the recording elements 15 are driven at the highest possible driving frequency. A diode sensor can be used as the temperature sensor 301.

[0069] 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 is not strong enough to cause bubbles. 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 together.

[0070] <Another example of a recording head> Figures 13(a) and (b) are diagrams illustrating 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 described in Figures 4 and 5 will be described.

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

[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 directions. Four electric wiring boards 90 are disposed on both sides of the electric wiring board support part 82 in the ±X directions so as to be continuous in the Y direction and are supported by the electric wiring board support part 82. Each electric wiring board 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 directions to protect the wiring circuit of the electric wiring board 90, the flexible wiring board 40, and their connection points. Note that the shield plate 132 is omitted from 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 part 80.

[0074] 14(a) to 14(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, compared to the configuration described in FIG. 4, the number of flow path connections is reduced, the number of parts and the number of assembly steps are reduced, and ink leakage can be suppressed.

[0075] Furthermore, 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 configuration is particularly suitable for use in the recording apparatus 1000 having the configuration shown in Fig. 1(b), i.e., 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 due to changes in flow rate becomes smaller, making it possible to perform stable negative pressure control.

[0076] Figure 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 Figure 3(b). That is, the pressure of the ink flowing to 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] Figure 14(c) is a cross-sectional view taken along line XIVc-XIVc of Figure 14(a). Similar to the discharge unit 300 described in Figure 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 Figure 8(b), in the discharge unit 300 of this example, the cover plate 20 (see Figure 11) of the recording element substrate 10 is mounted directly on the surface of the first flow path member 50.

[0078] The individual supply flow paths 213a and the individual recovery flow paths 213b formed in each of the plurality of 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. Therefore, alignment when mounting the first flow path member 50 on the second flow path member 60 is easier than with the configurations described with reference to FIGS. 4(a) to 8(b), and as a result, the yield during production 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 and 14 can be suitably used.

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

[0081] When the temperature adjustment process is performed, ink before being heated by the recording element substrate 10 flows through the common supply flow path 211, and ink after being heated by the recording element substrate flows through the common recovery flow path 212. As a result, the temperature on the side of the second flow path member 60 facing the common recovery flow path 212 becomes higher than the side of the common supply flow path 211, causing greater thermal expansion, and the side facing the common recovery flow path 212 bends so as to protrude in the X direction, resulting in thermal deformation as shown in Figure 15(b). Such thermal deformation becomes larger 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 printing element substrate 10 depends on the pressure difference created by the first and second negative pressure control units 230 and 231, the flow resistance of the printing 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 printing heads 3 mounted on the printing apparatus 1000, there is inevitably a certain degree of variation in thermal deformation during temperature control processing and printing operation.

[0083] 16(a) and 16(b) are diagrams illustrating print position deviations caused by thermal deformation of the print head 3. FIG. 16(a) shows print position deviations when both ends of the print head are fixed to the printing apparatus, and FIG. 16(b) shows print position deviations when the center of the print head is fixed to the printing apparatus. In both figures, the left side shows ruled lines printed on the print medium by head A, which has relatively large thermal deformation, and the right side shows ruled lines printed on the print medium by head B, which has relatively small thermal deformation. Head A is a print head in which the temperature detected by the temperature sensor 301 is detected as lower than the actual temperature, causing the sub-heater 302 to be driven more strongly. Alternatively, this print head is one 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, resulting in a relatively large amount of ink circulating in the print element substrate 10.

[0084] Head B is a print head in which the temperature detected by the temperature sensor 301 is higher than the actual temperature, causing the sub-heater 302 to be weakly driven. Alternatively, this print head is one in which 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, causing the amount of ink circulating in the print element substrate 10 to be relatively small.

[0085] In this way, in each print head 3, print position deviation in the X direction occurs due to thermal deformation, and even when attempting to print straight ruled lines, a curved ruled line is printed. Furthermore, when these print heads print images in the same area of ​​the print medium, the difference in the amount of deflection manifests as print position deviation in the X direction. In the case of FIG. 16(a), where both ends of the print head are fixed, the print position deviation in the X direction is greatest at the center of the print head 3. In the case of FIG. 16(b), where the center of the print head is fixed, the print position deviation in the X direction is greatest at both ends of the print head 3. This print position deviation can be on the order of several hundred microns, raising concerns about a decrease in image quality.

[0086] (First embodiment) 17 is a flowchart illustrating the process for correcting 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 print position deviation becomes noticeable, and other times as needed.

[0087] When this process starts, the control unit 500 first performs temperature control under the same conditions as during normal recording operation for all the recording heads 3 in step S1, 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 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 amount of shift from the standard value for the timing at which a pulse voltage is applied to the recording elements 15. That is, if the correction value is +Δt, the drive timing of that recording element substrate 10 after correction will be delayed by Δt from the standard. On the other hand, if the correction value is -Δt, the drive timing of that recording element substrate 10 after correction will be advanced by Δt from the standard. Such correction values ​​can be calculated based on the amount of recording position deviation obtained in step S3, the recording medium transport speed, 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 the correction values ​​for each recording element substrate 10 set in step S4 in memory. The memory may be the ROM 501 or may be a storage means provided separately from the ROM 501. This completes 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 print command is input to the printing device 1000, the control unit 500 reads 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. This makes it possible to print an image on the printing medium S with reduced print position deviation.

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

[0095] In the case of head A, as shown in Figure 18(a), the printing position in the center is shifted in the +X direction relative to the printing positions at the edges. Therefore, in the correction process, the drive timing of the printing element substrate 10 located in the center is corrected so as to be delayed relative to the drive timing of the printing element substrate 10 located at the edges. In this case, the amount of correction is greater toward the center and smaller toward the edges. By performing this correction process, the printing positions in the X direction of all the printing element substrates 10 arranged in head A are aligned, and ideal ruled lines extending in the Y direction are obtained, as shown in Figure 18(b).

[0096] The same applies to 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 can suppress misregistration of the recording position within each recording head 3 and misregistration of the recording position between recording heads, thereby making it possible to record high-quality images without color misregistration.

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

[0099] <Expansion difference due to difference in discharge frequency> Figure 19 is a diagram illustrating the difference in print head deformation due to differences in ejection frequency. Here, the figure compares the ruled lines printed at maximum drive frequency and minimum drive frequency for head A and head B. Hereinafter, for ease of explanation, the state in which all print elements 15 used for printing are driven at the maximum drive frequency to eject a large amount of ink will be referred to as the maximum drive frequency. Furthermore, the state in which the minimum ejection operation is performed to enable confirmation of the print position on the print medium will be referred to as the minimum drive frequency.

[0100] Even for the same print head, the amount of print position misalignment varies depending on the ejection frequency. The higher the ejection frequency, the more heated ink is expelled to the outside, reducing the amount of ink circulation. This suppresses thermal deformation and reduces the amount of misalignment in the X direction. Here, the X direction misalignment at the center of head A at the minimum drive state is shown as Xa1, and the X direction misalignment at the maximum drive state is shown as Xb2. Similarly, the X direction misalignment at the center of head B at the minimum drive state is shown as Xb1, and the X direction misalignment at the maximum drive state is shown as Xb2. In other words, without correction processing, the center of head A during printing shifts between Xa1 and Xa2, while the center of head B shifts between Xb1 and Xb2. In this case, a maximum color misalignment of ΔDmax = |Xa1 - Xb2| occurs between head A, which has large thermal deformation, and head B, which has small thermal deformation. ΔDmax is even larger than the maximum print position misalignment shown in Figure 16, which compares the print positions under a single drive state.

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

[0102] 20 is a flowchart illustrating the process for correcting 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 print position deviation becomes noticeable, and other times as needed.

[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 controlled 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 from the ROM 501 onto the recording medium.

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

[0106] In steps S14 to S16, the control unit 500 sets correction values ​​for 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 the temperature control temperature for normal recording operation, and then a predetermined circulation control is performed without driving the recording elements or at the 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 obtained in step S13 and the amount of recording position deviation in the minimum driving state obtained in step S16.

[0108] 21(a) and 21(b) are diagrams illustrating the method of setting the correction values ​​performed by the control unit 500 in step S17 of this embodiment and the effect of the correction. In this embodiment, as shown in FIG. 21(a), the average value of the print position deviation in the maximum drive state and the print position deviation in the minimum drive state is calculated for each print element substrate 10. Then, a correction value for making this average deviation amount zero is set as the correction value for that print 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 zero is set. At the center of head B, the average deviation amount is (Xb1+Xb2) / 2. Therefore, a correction value for making this deviation zero is set.

[0109] Returning to the description of the flowchart in Fig. 20, in step S18, the control unit 500 stores the correction values ​​for each recording element substrate 10 set in step S17 in memory. The memory may be the ROM 501, or may be a storage means provided separately from the ROM 501. This completes 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 in accordance with the correction values, an image is printed on the printing medium in accordance with the image data.

[0112] FIG. 21(b) shows the state in which ruled lines are printed according to the set correction values. The correction performed on each printing element substrate 10 is a correction to make the average deviation amount between 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 printed are slightly curved toward the +X side. In the maximum drive state, the correction is slightly excessive, and ruled lines that are printed are slightly curved toward the -X side. Furthermore, in a drive state between the maximum drive state and the minimum drive state, approximately straight ruled lines are printed.

[0113] More specifically, with 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. Furthermore, the maximum print position deviation ΔDmax' between head A and head B can also be reduced compared to ΔDmax.

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

[0115] In the above, the deviation amount to be corrected (hereinafter referred to as the deviation amount to be corrected) is the average value of the print position deviation in the maximum drive state and the print position deviation in the minimum drive state, but the deviation amount to be corrected does not have to be the average value. The deviation amount to be corrected may also be calculated 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 inconspicuous in the minimum drive state, the deviation amount to be corrected may be calculated by making the weighting coefficient for the print position deviation in the maximum drive state larger than the weighting coefficient for the minimum drive state. Furthermore, for ink that rarely experiences the maximum drive state in the ejection data after image processing, the deviation amount to be corrected may be calculated by making the weighting coefficient for the print position deviation in the minimum drive state larger than the weighting coefficient for the maximum drive state.

[0116] Furthermore, in the above, the amount of deviation to be corrected was calculated based on the print position deviation at two points, the maximum drive state and the minimum drive state, but the amount of deviation to be corrected may also be calculated from a different drive state. That is, the amount of deviation to be corrected may also 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 amount of deviation to be corrected may be adjusted appropriately 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 both the maximum drive state and the minimum drive state for each print head 3. However, such measurements require that the temperature control process and 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 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) for 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 referred to as the intermediate state.

[0119] <How to recreate the intermediate state> FIG. 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 represents the circulation amount Vs, and the vertical axis represents 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. Furthermore, the target temperature set in common to the multiple recording element substrates 10 arranged in the Y direction and adjusted by the temperature sensor 301 and 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] Fig. 22 plots the relationship between the circulation rate Vs and the controlled temperature Ts that can reproduce the intermediate state obtained by thermal-fluid-structure coupled simulation. This relationship between the circulation rate Vs and the controlled temperature Ts can be approximated by a cubic function with 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 determined from the ink temperatures Ti of 28° C. and 32° C. Therefore, in this embodiment, the following (Equation 2) is used as the cubic function Ts(Vs) of the controlled temperature Ts, using a minimum value α and a maximum value β.

[0124]

number

[0125] 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 ink temperatures T of 28° C. and 32° C. The coefficients a, α, and β for the ink temperatures T of 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-mentioned cubic function for any print head 3 can be derived by measuring the temperature Ti of ink circulating through the printing apparatus 1000 via that print head 3. Then, by using the derived cubic function, the temperature control 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 23(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. As a result, a flow from the common supply flow path 211 toward the common recovery flow path 212 occurs in the recording element substrate 10, and the total flow rate that passes through multiple recording element substrates 10 is the circulation volume Vs. The circulation volume Vs is controlled based on tolerances such as the differential pressure created by the first and second negative pressure control units 230 and 231, the liquid viscosity, and flow path resistance, and in this embodiment is adjusted to 25 to 255 ml / min.

[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 that takes 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 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 channel 211 and the relationship between the circulation amount Vs and the upstream flow rate Q2 of the common recovery channel 212, respectively.

[0134] The relationship between the upstream flow rates Q1, Q2 and the circulation rate Vs can be measured by installing flow meters at four locations, upstream and downstream of the common supply flow path 211 and the common recovery flow path 212. Specifically, the circulation rate Vs is the difference between the measurements of the 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 rate Vs can also be the difference between the measurements of the two flow meters installed upstream and downstream of the common recovery flow path 212. The average of these two differences may also be used as the circulation rate Vs.

[0135] 23(b) and 23(c) show, as legends, 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 normal operation of the negative pressure control unit, and the set flow rate of this embodiment. All of these have a linear relationship with the circulation rate Vs. That is, in the recording head 3 of this embodiment, the circulation rate 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 values ​​of the flow meter. Furthermore, the circulation rate Vs of the target recording head 3 can be calculated based on the graphs of FIGS. 23(b) and 23(c) from the actual measurements 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.

[0136] That is, in this embodiment, the intermediate state of any print head 3 can be reproduced by the following procedure. First, the ink temperature Ti and circulation volume Vs of the target print 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 volume Vs is obtained based on the graphs of FIGS. 23(b) and 23(c). Next, using the measured ink temperature Ti, a cubic function of the target print head 3 is derived according to (Equation 2) and (Equation 3). Then, according to the derived cubic function, the controlled temperature Ts corresponding to the circulation volume Vs is calculated (see FIG. 22). Finally, the temperature of each printing element substrate 10 of the target print head 3 is adjusted to the controlled temperature Ts, and a steady state is waited for. This allows the target print head 3 to reproduce an intermediate state of thermal expansion intermediate between the maximum drive state and the minimum drive state.

[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 intermediate state will be described.

[0138] Fig. 24 is a flowchart for explaining the process of correcting print position deviation in this embodiment. The only difference from the flowchart of Fig. 17 described 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-described method, and then a predetermined circulation control is performed without driving the recording elements 15.

[0140] The following steps S22 to S25 are the same as 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 print 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] Furthermore, in the case of the second embodiment, in a print head that is inherently less susceptible 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 it may be impossible to set an appropriate amount of deviation to be corrected. In a configuration in which print position deviation is measured in a single drive state, as in this embodiment, it is possible to obtain the amount of deviation to be corrected with higher accuracy.

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

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

[0145] 23(b) and 23(c) have been described with reference to a case where 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 volume 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 or the upstream flow rate Q2 of the common recovery flow path 212 change discontinuously with respect to the circulation volume Vs, they may be expressed by a plurality of discontinuous functions. In any case, it is sufficient that the circulation volume Vs be uniquely determined with respect to the actually measured Q1 and Q2.

[0146] In the above description, a function of the controlled temperature Ts and the circulation volume Vs, as shown in FIG. 22, was derived in accordance with Equation 3 in association with the ink temperature Ti, and then the controlled temperature Ts was obtained from the circulation volume Vs using this function. However, this procedure 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 volume Vs, and then the controlled temperature Ts may be obtained from the ink temperature Ti using this function.

[0147] Furthermore, in the above, the controlled temperature Ts corresponding to the ink temperature Ti and the circulation rate Vs was calculated using functions such as (Equation 2) and (Equation 3), but the controlled temperature Ts may also be obtained by referencing a lookup table. In this case, a three-dimensional lookup table in which the ink temperature Ti, the circulation rate 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 coupled simulation.

[0148] In the above, an intermediate state in which 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 in which intermediate thermal expansion is obtained can be reproduced and then the print position deviation can be measured, it becomes possible to set an appropriate correction value for each print head 3, and the effects of this embodiment can be achieved.

[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 the degree to which print position deviation is noticeable, the driving frequency at which it is most frequent, etc. The effect of this embodiment can be obtained by performing the temperature adjustment process in step S21 under driving conditions that result in the deviation amount to be corrected.

[0150] (Other embodiments) In the above embodiment, a 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 group 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 area.

[0151] In the above, an example has been described in which the temperature Ti of the ink flowing through the printing apparatus 1000 is maintained at 28°C to 32°C by a heat exchanger, and the controlled temperature Ts of the printing element substrate 10 during normal printing operations is set to 65°C, but these 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 due to the temperature control process and circulation control may not be very noticeable. To fully utilize the effects of the above embodiment, it is preferable that the controlled temperature Ts during printing operations be 10°C or more higher than the ink temperature Ti.

[0152] In the above embodiment, a method for correcting print position deviation in the X direction that occurs due to the temperature difference between the ink flowing in the common supply flow path 211 and the common recovery flow path 212 has been described using Figure 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 correction processing is performed after the thermal expansion of the print head 3 reaches a steady state, it is possible to obtain the effect of reducing dynamically changing print position deviation.

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

[0154] While the above examples use Figures 4 and 5 to illustrate print heads compatible with A3 and B2 sizes, the length of the print head is not particularly limited. Furthermore, the print head does not necessarily have to be a line print head mounted on a full-line printing device. Even in a serial printing device that alternates print head print scans and transport operations that transport the print medium in a direction intersecting the print scans, if the print head mounted is long, print position deviations due to thermal deformation may occur. Even in such cases, print position deviations can be reduced by setting the correction values ​​for each print head according to the above-described embodiment. However, to effectively correct print position deviations due to thermal deformation, it is preferable that the print head have a print width of A3 size or greater.

[0155] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the 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 realizes one or more functions. [Explanation of symbols]

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

Claims

1. a temperature adjusting means for adjusting 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 the liquid to the plurality of recording element substrates, and a common recovery flow path for commonly recovering the liquid from the plurality of recording element substrates, the method comprising: correcting a recording position in a second direction intersecting the first direction; an acquisition step of performing temperature control on 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 for each of the plurality of recording element substrates or for a plurality of adjacent recording element substrates as a unit based on the amount of recording position deviation; 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 in the first direction.

2. A method for correcting a recording position in a second direction of a recording device comprising: a plurality of recording element substrates on which a plurality of recording elements are arranged successively in a first direction; temperature control means for adjusting the temperature of the recording element substrates; circulation means for circulating a liquid to 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 accordance with the temperature control means and the circulation of the liquid, and records an image on a recording medium moving in the second direction intersecting the first direction, the method comprising: an acquisition step of performing temperature control on 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 indicating a shift amount from a standard value of the timing at which the recording elements are driven based on the amount of recording position deviation; 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 in the first direction.

3. 3. 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 the growth energy of the generated bubbles.

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

5. 5. 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.

6. 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; recording an image on a recording medium according to image data using the correction value; A recording method comprising:

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

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