Inkjet recording apparatus and recording position adjustment method

Abstract

To reduce time consumed for adjustment of a recording position.SOLUTION: When ejection timings are adjusted by first adjustment means with adjustment values unstored in data storage means, first correction value calculation means adjusts the ejection timings at n scanning speeds, or otherwise, when the ejection timings are adjusted by the first adjustment means with the adjustment values stored in the data storage means, the first adjustment means adjusts the ejection timings at n-1 or fewer scanning speeds; and the first correction value calculation means uses a correction value calculated on the basis of the adjustment value from the first adjustment means for an adjustment value at a scanning speed at which an ejection timing is not adjusted.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to an inkjet printing apparatus and a printing position adjustment method. [Background technology]

[0002] Inkjet printing devices sometimes experience misalignment of dot printing positions when printing in both directions during reciprocating scans. Because this misalignment leads to a decrease in print quality, techniques for correcting the misalignment of dot printing positions are known.

[0003] Patent Document 1 discloses that a plurality of sample patterns (hereinafter also referred to as adjustment patterns) are printed while shifting the ejection timing of a return scan, which is the reference side, relative to a forward scan, which is the reference side.Then, a sensor is mounted on the carriage of the inkjet printing device, and the adjustment value is determined by scanning the print medium and optically reading the adjustment pattern.

[0004] Incidentally, some inkjet recording apparatuses can be set to a plurality of modes with different quality and printing speed.

[0005] Patent Document 2 discloses a method of printing a plurality of adjustment patterns at different scanning speeds, calculating the ink ejection speed from a selected predetermined adjustment pattern and the distance from the head surface of the print head to the printing surface of the printing medium, storing this in a non-volatile memory, and correcting dot printing position deviations based on the print head scanning speed during printing and the stored ink ejection speed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-329381 [Patent Document 1] Japanese Patent Application Publication No. 11-179891 Summary of the Invention [Problem to be solved by the invention]

[0007] However, with the method described in Patent Document 2, in order to improve the adjustment accuracy for the distance from the head surface of the print head to the printing surface of the printing medium (hereinafter also referred to as the print head-printing medium distance), variations in the print head-printing medium distance, and dot printing position deviations due to various print head scanning speeds, the number of adjustment patterns to be printed must be increased, which poses problems such as longer time required for the process of adjusting the dot printing position (hereinafter also referred to as the registration adjustment process), increased ink consumption, and increased printing medium consumption.In addition, because the ink ejection speed changes as the print head wears out or is replaced, the registration adjustment process must be performed each time, significantly reducing the user experience.

[0008] The present invention has been made in view of the above-mentioned problems, and has as its object to reduce the time required to adjust the printing position. [Means for solving the problem]

[0009] The present invention is an inkjet recording device comprising a recording head having a plurality of nozzle rows for ejecting ink, a carriage that scans the recording head at at least two or more speeds, a first adjustment means that adjusts the ejection timing of the ink from the recording head for each scanning speed of the carriage, a data storage means that stores the adjusted ejection timing as an adjustment value, and a first correction value calculation means that calculates a correction value for each scanning speed of the carriage using the adjustment value stored in the data storage means, wherein when the adjustment of the ejection timing by the first adjustment means is executed with no adjustment value stored in the data storage means, the first correction value calculation means adjusts the ejection timing at n scanning speeds, and when the adjustment of the ejection timing by the first adjustment means is executed with an adjustment value stored in the data storage means, the first adjustment means adjusts the ejection timing at n-1 or fewer scanning speeds, and for the adjustment value at a scanning speed at which the ejection timing was not adjusted, the first correction value calculation means uses a correction value calculated based on the adjustment value of the first adjustment means. [Effects of the Invention]

[0010] According to the present invention, which has been made in view of the above-mentioned problems, the time required for adjusting the printing position can be reduced. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing an example of the external configuration of a recording apparatus 1 according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a schematic configuration of an optical sensor 500 shown in FIG. [Figure 3] FIG. 2 is a diagram showing an example of an arrangement of ejection nozzles 310 in the print head 301 shown in FIG. [Figure 4] FIG. 2 is a diagram showing an example of the functional configuration of the recording device 1 shown in FIG. [Figure 5] 10A and 10B are enlarged views illustrating the configuration of registration adjustment patterns when density is detected by an optical sensor. [Figure 6] FIG. 10 is an overall view of a configuration for explaining a group of registration adjustment patterns when density is detected by an optical sensor. [Figure 7] 6 is a graph showing the density detected from the registration adjustment pattern and an approximation curve. [Figure 8] 10A and 10B are diagrams illustrating deviations in dot recording positions when the ink ejection speed changes. [Figure 9] 10A and 10B are diagrams illustrating a method for adjusting misalignment of dot recording positions without recording on a recording medium. [Figure 10] 10 is a table showing registration adjustment values ​​determined in the first registration adjustment process in the first embodiment. [Figure 11] 10 is a table showing registration adjustment values ​​determined in the second registration adjustment process in the first embodiment. [Figure 12] 6 is a graph comparing first and second adjustment values ​​in the first embodiment. [Figure 13] 10 is a graph comparing registration adjustment values ​​before and after replacing a print head in the fourth embodiment. [Figure 14] 5 is a flowchart showing an example of the flow of processing performed by the recording device 1 according to the first embodiment. [Figure 15] 4 is a table showing registration adjustment values ​​and registration correction values ​​according to the first embodiment. [Figure 16] 10 is a flowchart showing an example of the flow of processing performed by the recording device 1 according to the second embodiment. [Figure 17] 10 is a table showing registration adjustment values ​​and registration correction values ​​according to the second embodiment. [Figure 18] 10 is a table showing registration adjustment values ​​and registration correction values ​​according to the second embodiment. [Figure 19] 11 is a flowchart showing an example of the flow of processing performed by the recording device 1 according to the third embodiment. [Figure 20] 10 is a table showing registration adjustment values ​​and registration correction values ​​according to the third embodiment. [Figure 21] 10 is a graph showing the relationship between the print head-printing medium distance and the registration adjustment value in the third embodiment. [Figure 22]10 is a flowchart showing an example of the flow of processing performed by the recording device 1 according to the fourth embodiment. [Figure 23] 13 is a flowchart showing an example of the flow of processing performed by the recording device 1 according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (First embodiment) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0013] FIG. 1 is a perspective view showing an example of the external configuration of an inkjet recording apparatus 1 according to a first embodiment. The recording apparatus 1 has an inkjet recording head (hereinafter referred to as a recording head) 301 mounted on a carriage 202, which performs recording by ejecting ink according to an inkjet method, and performs recording by moving the carriage 202 back and forth in the direction of arrow X (main scanning direction). The recording apparatus 1 feeds a recording medium S, such as recording paper, via a paper feed mechanism and transports it in the direction of arrow Y (sub-scanning direction). Then, at a predetermined recording position, ink is ejected from the recording head 301 onto the recording medium S, thereby performing recording.

[0014] The carriage 202 is equipped with, for example, a (reflective) optical sensor 500 and ink cartridges 401. In this case, four ink cartridges 401 (401K, 401C, 401M, 401Y) containing magenta (M), cyan (C), yellow (Y), and black (K) ink, respectively, are equipped. Each of these four ink cartridges 401 can be attached and detached independently. In this embodiment, an on-carriage configuration is adopted in which the ink cartridges 401 of each color are mounted on the carriage 202. Alternatively, an off-carriage configuration may be adopted in which main tanks for each ink color are mounted in a location other than the carriage 202 within the inkjet recording apparatus 1, and supply paths such as tubes are provided in the recording head 301 to supply ink.

[0015] A plurality of nozzle rows (rows of ejection openings) for ejecting ink corresponding to each color are formed on the print head 301. In this case, nozzle rows capable of ejecting black (Bk), cyan (C), magenta (M), and yellow (Y) inks are formed corresponding to the ink cartridges 401 described above.

[0016] The print head 301 is equipped with heat generating resistor elements and ejects ink using thermal energy. A heat generating resistor element is provided corresponding to each ejection port, and a pulse voltage is applied to the corresponding heat generating resistor element in response to a print signal. This causes ink to be ejected from the corresponding ejection port. The print head may also use a method of ejecting ink using a piezoelectric element instead of a heat generating resistor element.

[0017] The print head 301 is detachably (i.e., replaceably) mounted on a carriage 202. The carriage 202 is slidably supported on a guide rail 204, and is reciprocated along the guide rail 204 by a driving means (not shown) such as a motor. The print medium S is transported in the sub-scanning direction (arrow Y) by a transport roller 203 while maintaining a constant opposing distance from the ejection port surface (the surface on which ink ejection ports are formed) of the print head 301.

[0018] A recovery unit 207 that recovers ejection defects from the print head 301 is disposed outside the range of reciprocating movement of the carriage 202 (outside the printing area). The position where the recovery unit 207 is provided is called the home position, and the print head 301 remains stationary at this position while no printing operation is being performed. The recovery unit 207 is equipped with caps 208 (208K, 208C, 208M, 208Y) that can cap the ejection ports of the print head 301. The caps 208K, 208C, 208M, and 208Y are configured to be able to cap the ejection ports that eject black, cyan, magenta, and yellow ink, respectively.

[0019] A suction pump (negative pressure generating means) is connected inside each cap 208. When each cap 208 caps the ejection ports of the print head 301, negative pressure is introduced into the cap 208, thereby sucking and discharging ink from the ejection ports of the print head 301 into the cap 208 (suction recovery operation). This suction recovery operation makes it possible to maintain the ink ejection performance of the print head 301.

[0020] The recovery unit 207 is also provided with a wiper 209 such as a rubber blade for wiping the ejection port surface of the print head 301. The recovery unit 207 also performs a recovery process (also called preliminary ejection) to maintain the ink ejection performance of the print head 301 by ejecting ink from the print head 301 into the cap 208.

[0021] In addition to the print head 301 and ink cartridge 401, the carriage 202 is equipped with a reflective optical sensor (hereinafter referred to as the optical sensor) 500. The optical sensor 500 is a sensor that can acquire optical characteristics, and optically reads a registration adjustment pattern (hereinafter referred to as the adjustment pattern) recorded on the recording medium S and measures the recording density.

[0022] 2, the optical sensor 500 is provided with a light-emitting unit 501 realized by an LED or the like, and a light-receiving unit 502 realized by a photodiode or the like. Irradiation light 510 emitted by the light-emitting unit 501 is reflected on the recording medium S, and the reflected light 520 is incident on the light-receiving unit 502. The light-receiving unit 502 converts the reflected light 520 into an electrical signal.

[0023] When measuring the recording density of the adjustment patterns, the recording medium S is conveyed in the sub-scanning direction alternately with the carriage 202, on which the optical sensor 500 is attached, moving in the main scanning direction, so that the optical sensor 500 detects the density of the adjustment patterns recorded on the recording medium as optical reflectance.

[0024] Next, an example of the arrangement of the ejection nozzles 310 in the print head 301 shown in FIG. 1 will be described with reference to FIG.

[0025] The print head 301 has a plurality of nozzle arrays arranged in a sub-scanning direction (nozzle array direction) that intersects (orthogonal in this embodiment) the main scanning direction, which is the nozzle array direction. Specifically, nozzles (302K, 302C, 302M, 302Y) that eject ink of each color (CMYK) are arranged at predetermined intervals along the sub-scanning direction (Y direction), and each nozzle array is arranged along the main scanning direction (X direction). Two nozzle arrays (302K-A, 302K-B, 302C-A, 302C-B, 302M-A, 302M-B, 302Y-A, 302Y-B) are arranged corresponding to each color of ink. Each nozzle array has, for example, 1,280 nozzles arranged at intervals of 600 dpi (dots per inch). Furthermore, the nozzle arrays (two nozzle arrays) ejecting ink of the same color are offset from each other in the sub-scanning direction by, for example, 1200 dpi (half a pitch). That is, to achieve high printing resolution, the nozzle arrays are offset in the sub-scanning direction. This is because, while making the ink droplets smaller reduces the size of the dots that spread on the printing medium, improving resolution, it is not easy to improve resolution by reducing the dot size, and so this method is adopted. In this embodiment, the resolution of each nozzle array in the sub-scanning direction is 600 dpi, but by offsetting the nozzle array positions, printing at a resolution of 1200 dpi in the sub-scanning direction is possible.

[0026] In this embodiment, first, a plurality of adjustment patterns each consisting of a first pattern and a second pattern are printed on a printing medium, with the relative printing position of the second pattern relative to the first pattern in the sub-scanning direction being varied.

[0027] Next, an example of the functional configuration of the recording device 1 shown in FIG. 1 will be described with reference to FIG.

[0028] The controller 60 comprises an MPU 51, a ROM 52, an application specific integrated circuit (ASIC) 53, a RAM 54, a system bus 55, an A / D converter 56, etc. The ROM 52 stores programs corresponding to the control sequence described below, required tables, and other fixed data.

[0029] The ASIC 53 controls the carriage motor M1 and the transport motor M2. The ASIC 53 also generates control signals for controlling the print head 301. The RAM 54 is used as an area for storing image data and as a working area for executing programs. A system bus 55 interconnects the MPU 51, the ASIC 53, and the RAM 54 to exchange data. The A / D converter 56 A / D converts analog signals input from a group of sensors (described later) and supplies the converted digital signals to the MPU 51.

[0030] The MPU 51 performs overall control of the operation of the recording apparatus 1. For example, during the registration adjustment process, the MPU 51 calculates a registration adjustment value (hereinafter, sometimes referred to as an adjustment value) based on the measurement results of the adjustment pattern described above. This adjustment value is stored, for example, in the RAM 54 or the like. The MPU 51 also changes the ejection timing of ink ejected from each nozzle based on the adjustment value stored, for example, in the RAM 54 or the like, and adjusts the landing positions (adhesion positions) of dots formed on the recording medium.

[0031] Reference numeral 20 denotes a group of switches, including a power switch 21, a print switch 22, and a recovery switch 23. Reference numeral 30 denotes a group of sensors for detecting the device status, including a position sensor 31 and a temperature sensor 32. When the print head 301 scans, the ASIC 53 directly accesses the storage area of ​​the RAM 54 and transfers data to the print head 301 for driving the print elements (discharge heaters).

[0032] The printhead control unit 44 controls the printing operation of the printhead 301 by causing the printhead 301 to scan relatively over the print medium.

[0033] The carriage motor M1 is a drive source for causing the carriage 202 to scan back and forth in a predetermined direction, and a carriage motor driver 40 controls the driving of the carriage motor M1. The transport motor M2 is a drive source for transporting the recording medium, and a transport motor driver 42 controls the driving of the transport motor M2. The recording head 301 is scanned in a direction (main scanning direction) substantially perpendicular to the transport direction of the recording medium. In addition, the optical sensor 500 detects the density of the adjustment patterns recorded on the recording medium as optical reflectance.

[0034] The host device 10 is a computer (or an image reader or digital camera, etc.) that serves as a source of image data. Image data, commands, status signals, etc. are exchanged between the host device 10 and the recording device 1 via an interface (hereinafter referred to as I / F) 11. The above is an explanation of an example of the configuration of the recording device 1.

[0035] Here, an example of the configuration of the adjustment pattern used during the registration adjustment process will be described with reference to FIGS.

[0036] As shown in Figure 5, the adjustment pattern is configured so that a rectangular pattern of i pixels x n pixels is periodically repeated for each blank area of ​​m pixels, with the main scanning direction being the x direction and the sub-scanning direction being the y direction. Furthermore, a shift pattern (second pattern) 602 is printed with its printing position shifted by a predetermined number of pixels a in the sub-scanning direction relative to a reference pattern (first pattern) 601. The resolution and amount of shift of these adjustment patterns can be determined according to the printing resolution of the printing device. In this embodiment, the printing resolution is assumed to be 1200 dpi.

[0037] Fig. 6 shows an overall view of a configuration in which multiple adjustment patterns shown in Fig. 5 are arranged, with the main scanning direction being the x direction and the sub-scanning direction being the y direction. In this case, the adjustment pattern group shown in Fig. 6 is printed while changing the shift amount a of the shift pattern (second pattern) along the sub-scanning direction from -3 pixels to +3 pixels.

[0038] Here, if the amount of deviation in the printing position of the shift pattern relative to the reference pattern changes, the area ratio of ink on the printing medium changes. Figure 7 shows the measurement results of optical reflectance for each of the shift amounts shown in Figure 6. Note that density is inversely proportional to reflectance, and the smaller the deviation between the adjustment patterns actually printed on the printing medium, the lower the density and the higher the optical reflectance.

[0039] Therefore, in order to match the dot printing positions of the nozzle array used to form the reference pattern and the nozzle array used to form the shifted pattern, the ejection timing can be adjusted based on the amount of shift when the density of the adjustment pattern is lowest, i.e., the ejection timing of ink from the nozzle array used to form the shifted pattern can be adjusted.

[0040] The number of adjustment patterns formed on the recording medium and the amount of shift can be determined based on the adjustment range required by the mechanical tolerance of the device and the unit of shift in the recording position. In other words, they can be determined according to the accuracy of the registration adjustment process. Furthermore, the recording area of ​​the adjustment patterns can be determined based on the size of the detection area of ​​the optical sensor 500, the width of the area that can be printed in one printing scan, the size of the printable area on the recording medium relative to the group of adjustment patterns, etc.

[0041] The nozzle rows used to form the reference pattern and the shifted pattern are determined by a combination of the ink color and scanning direction of the nozzle row to be adjusted. When adjusting during forward scanning, a reference nozzle row (e.g., 302K-A) is selected to form the reference pattern, and the other nozzle row (e.g., 302C-A) forms the shifted pattern. The same process can be followed during backward scanning.

[0042] The position where ink ejected from each nozzle lands on the recording medium varies depending on various factors, such as the distance between the recording head and the recording medium, the ejection speed of each ink droplet, the scanning speed of the recording head, etc. In particular, the faster the scanning speed of the recording head, the greater the deviation in dot recording position due to variations in ink ejection speed and variations in the distance between the recording head and the recording medium.

[0043] FIG. 8 illustrates the dot recording position deviation when the recording head-recording medium distance varies, for two different recording head scanning speeds.

[0044] 701 represents the print head, and Vy represents the ink ejection speed. V1 and V2 represent the ink flying speed when the print head is scanned at the scanning speeds of Vx1 and Vx2. (Vx1 <Vx2) If the distance between the print head and the print medium changes by ΔH, the dot printing position deviation when scanning at Vx1 will be L1, and the dot printing position deviation when scanning at Vx2 will be L2. As is clear from Figure 8, if the amount of change in the print head-printing medium distance is the same, the dot printing position deviation will be greater when the print head scanning speed is Vx2, which is faster.

[0045] Figure 8 also illustrates the dot printing position deviation caused by fluctuations in ink ejection speed at two different print head scanning speeds. The main scanning direction is the x direction, and the sub-scanning direction is the y direction. As in Figure 8, 701 denotes the print head, Vy denotes the ink ejection speed, and V1 and V2 denote the ink flight speeds when the print head is scanned at scanning speeds of Vx1 and Vx2. (Vx1 <Vx2) For a change in ink ejection speed ΔV, the ink flight speed when scanning at Vx1 is V1', and the ink flight speed when scanning at Vx2 is V2', resulting in respective dot recording position deviations of L1 and L2. Figure 8 shows that even when the amount of change in ink ejection speed is the same, the dot recording position deviation is greater when the print head scanning speed is Vx2, which is faster.

[0046] As described above, the faster the scanning speed of the print head, the greater the deviation in dot printing position caused by changes in the distance between the print head and the print medium and the ink ejection speed.

[0047] Using the above relationship, there is also a method for predicting the dot recording position and performing registration adjustment processing without recording an adjustment pattern on the recording medium. Details are shown in Figure 9. Reference numeral 702 in Figure 9 denotes a laser irradiation device that irradiates a laser beam 703 horizontally toward a light receiving unit 704. By detecting the signal value at the light receiving unit 704, the timing at which the ink droplet passes through the laser beam irradiation surface can be determined. By measuring the time from when the ink droplet is ejected until it passes through the laser beam irradiation surface, it is possible to predict the ink flight velocity in combination with the known distance H between the recording head and the laser beam irradiation surface. The predicted flight velocity Vy and the known scanning speed Vx of the recording head allow the dot recording position at the recording head-recording medium distance during recording operation to be predicted. This makes it possible to adjust and reflect the deviation in the dot recording position without actually recording an adjustment pattern on the recording medium.

[0048] In conventional inkjet recording devices, the registration adjustment process is performed for each of a plurality of print head scanning speeds. This makes it possible to achieve high adjustment accuracy at each scanning speed. However, when the registration adjustment process is performed periodically or each time the head is replaced, there are problems such as the long time required for each adjustment process, the large amount of ink consumption, and the use of a large amount of recording medium.

[0049] Figure 10 shows the results of the first registration adjustment value in this embodiment. Registration adjustment processing is performed at multiple print head scanning speeds, and the print position shift amount (hereinafter also referred to as registration adjustment value) determined based on the adjustment results is stored in ROM 52. In Figure 10, the print head scanning speed is adjusted at 30 to 70 ips (inches per second).

[0050] The registration adjustment values ​​shown in Figure 11 are the registration adjustment values ​​obtained when a second registration adjustment process is performed using the same print head after repeating printing operations for a sufficient period of time using the print head with the registration adjustment values ​​shown in Figure 10. Furthermore, Figure 12 is a graph comparing the registration adjustment values ​​from Figures 10 and 11, with the print head scanning speed on the horizontal axis and the registration adjustment value on the vertical axis, comparing the first registration adjustment value (solid line) and the second registration adjustment value (dashed line). Figure 12(a) shows the registration adjustment values ​​for ink K, Figure 12(b) shows the registration adjustment values ​​for ink Y, Figure 12(c) shows the registration adjustment values ​​for ink M, and Figure 12(d) shows the registration adjustment values ​​for ink C. Looking at these graphs, although the absolute values ​​differ for each ink color, the progression of the registration adjustment value relative to the print head scanning speed is similar for the first and second runs, and the registration adjustment value at one scanning speed can be inferred from the registration adjustment value at another scanning speed. 13(a)-(d) are graphs of each ink color comparing the first registration adjustment value of the print head (referred to as print head A) that underwent the registration adjustment process in FIG. 12 with the registration adjustment value of another print head (referred to as print head B). As with FIG. 12, the transition of the registration adjustment value relative to the print head scanning speed is similar, so if the absolute value of the registration adjustment value for one print scan is known, it is possible to estimate the registration adjustment value for the remaining print scans. Therefore, by using the registration adjustment value determined in a previous registration adjustment process and stored in ROM 52, high adjustment accuracy can be maintained even in subsequent registration adjustment processes or registration adjustment processes after print head replacement, without having to perform registration adjustment processes at all scanning speeds. Additionally, it is possible to reduce the time, ink, and media consumption associated with performing registration adjustment processes.

[0051] Next, the registration adjustment process will be described in detail. In this embodiment, the registration adjustment process is performed only at the scanning speed selected by the user (hereinafter referred to as the first scanning speed), and at scanning speeds where the registration adjustment process is not performed, correction is made using past registration adjustment values ​​stored in ROM 52. In the registration adjustment process of this embodiment, in order to adjust the dot recording positions during forward scanning and reverse scanning, a reference pattern is recorded during forward scanning and a shifted pattern is recorded during reverse scanning. Figure 14 shows the operational flow when the user executes the registration adjustment process on the inkjet recording apparatus of this embodiment via the host device 10 or interface (I / F) 11.

[0052] FIG. 14 shows the operational flow for determining and storing registration adjustment values ​​in ROM 52 for all scanning speeds (referred to as scanning speeds 1 through n, where n is an integer equal to or greater than 2) used in the printing operation of the inkjet printing apparatus used in this embodiment. This process is executed by the MPU 51. When the user selects and starts the registration adjustment process, the MPU 51, which serves as a determination unit, determines in S101 whether the registration adjustment values ​​(registration adjustment values ​​1' through n') determined in the previous registration adjustment process are stored in ROM 52. Thereafter, the MPU 51 determines whether the registration adjustment values ​​are stored in ROM 52. If the registration adjustment values ​​are not stored, the process proceeds to S102, where the registration adjustment process is performed at all scanning speeds to determine the registration adjustment values ​​(registration adjustment values ​​1 through n) for each scanning speed. If the registration adjustment values ​​are stored in ROM 52 in S101, the process proceeds to S103, where the user selects one scanning speed to adjust. The selected scanning speed is designated as the first scanning speed.

[0053] Next, in S104, the registration adjustment process is performed at the first scanning speed to determine the registration adjustment value at the first scanning speed (first registration adjustment value). Next, for the registration adjustment values ​​2 to n that were not selected, in S105, the registration adjustment values ​​2' to n' already stored in ROM 52 are acquired. If the registration adjustment process has been performed multiple times in the past and multiple registration adjustment values ​​2' to n' are stored in ROM 52, it is preferable to acquire the most recent one among them, i.e., the registration adjustment value determined when the registration adjustment process was previously performed. In S106, the registration correction values ​​2 to n are calculated.

[0054] A specific calculation method will be described with reference to the table in FIG. 15. FIG. 15 is a table illustrating the 1st to nth scanning speeds and the registration adjustment values ​​for each color stored in ROM. FIG. 15(a) shows the 1st to nth registration adjustment values ​​already stored in ROM 52 at the time of performing the registration adjustment process. FIG. 15(b) shows the registration adjustment process performed in S104 at the first scanning speed (30 inches / second in Table 16) set by the user in S103, and the determined first registration adjustment value is input. FIG. 15(c) shows the difference between the registration adjustment values ​​for each color at 40 to 70 inches / second, based on the registration adjustment values ​​for each color at 30 inches / second, the same as the 1st scanning speed, from the registration adjustment values ​​shown in FIG. 15(a). These difference values ​​are used as the 2nd to nth registration correction values ​​in S106.

[0055] In S107, the second to nth registration correction values ​​(corresponding to FIG. 15(c)) calculated in S107 are added to the first registration adjustment value (corresponding to FIG. 15(b)) determined in S104, and the result is determined as the first to nth registration adjustment values, as shown in FIG. 15(d). Finally, the determined registration adjustment value is stored in ROM 52 in S108. In this way, by utilizing the relationship between registration adjustment values ​​between scanning speeds, it is possible to perform high-precision adjustment in a short time without performing registration adjustment processing for all scanning speeds.

[0056] As described above, when the ejection timing adjustment is performed with no adjustment values ​​stored in the ROM 52, the ejection timing is adjusted at n scanning speeds. On the other hand, when the ejection timing adjustment is performed with adjustment values ​​stored in the ROM 52, the ejection timing is adjusted at n-1 or fewer scanning speeds. By using a correction value calculated by the MPU 51 based on the first registration adjustment value as the adjustment value for the scanning speed at which the ejection timing is not adjusted, it is possible to perform the registration adjustment process in a short time when the registration adjustment process is not performed for all scanning speeds.

[0057] In this embodiment, the user arbitrarily sets the first scanning speed, but the method for determining the first scanning speed is not limited to this. For example, many inkjet recording devices have biased uses for printed output depending on the user. Inkjet recording devices used in offices often print documents, CAD drawings, and the like, and the print head scanning speed is often set high to achieve high productivity for outputting such printed output. On the other hand, when used to print advertisements, photographs, and the like, the print head scanning speed is often set low to output printed output with higher image quality. In such cases, when the inkjet recording device is used with a bias toward certain printing conditions, the number of times the printing conditions are used is stored in ROM 52 and this data is referenced when performing the registration adjustment process. By setting the scanning speed of the most frequently used printing condition among the printing conditions stored in ROM 52 as the first scanning speed, the user can perform the registration adjustment process and determine highly accurate registration adjustment values ​​for frequently used printing conditions without having to set the first scanning speed, while quickly determining registration adjustment values ​​for other less frequently used printing conditions.

[0058] In addition, in this embodiment, adjustments were made to the dot recording positions during forward scanning and reverse scanning, but this is not limited to this, and the present invention can also be used to adjust the dot recording positions between ink colors or between nozzle rows.

[0059] (Second embodiment) In the second embodiment, registration adjustment processing is performed at multiple scanning speeds. This allows for more accurate determination of registration adjustment values ​​for each scanning speed compared to the first embodiment. A specific operational flow is shown in FIG. 16 , and the adjusted, acquired, and calculated registration adjustment values ​​are shown in the table in FIG. 17 . First, as in the first embodiment, in S201, the MPU 51 determines whether previous registration adjustment values ​​are stored in the ROM 52. If they are not stored, the process proceeds to S202. As shown in FIG. 17( a), if registration adjustment values ​​are stored in the ROM 52, the process proceeds to S203, where the user selects the scanning speed at which they want to perform registration adjustment. In this embodiment, a first scanning speed (30 inches / second) and a second scanning speed (70 inches / second) are selected. Any number of scanning speeds may be selected here as long as they are equal to or less than n. The more scanning speeds selected, the longer the registration adjustment processing time, but the higher the accuracy of the adjustment. In S204, registration adjustment processing is performed for the first and second scanning speeds selected in S203, and the first and second registration adjustment values ​​are determined. (FIG. 17(b)) Next, in S205, the 3' to n' registration adjustment values ​​are obtained from ROM 52, and the differences between the registration adjustment values ​​for the scanning speeds of 30 inches / second and 70 inches / second selected by the user in S203 and the registration adjustment values ​​for 40 inches / second, 50 inches / second, and 60 inches / second are calculated. In this embodiment, the differences between registration adjustment values ​​for scanning speeds that are close to each other are calculated. The difference between the registration adjustment value for 40 inches / second and 30 inches / second is calculated, and the difference between the registration adjustment value for 60 inches / second and 70 inches / second is calculated. The difference between the registration adjustment value for 50 inches / second, which is an intermediate scanning speed, and 30 inches / second is calculated. This makes it possible to obtain the registration correction values ​​for each scanning speed. (FIG. 17(c)) Next, in S207, the registration adjustment values ​​for 30 inches / second and 70 inches / second that have been subjected to the registration adjustment process are reflected as is, and the registration adjustment values ​​for the remaining scanning speeds are calculated by adding the registration correction values ​​calculated in S206 to the registration adjustment values. The registration correction values ​​for 40 inches / second and 50 inches / second are added to the registration adjustment value for 30 inches / second, and the registration correction value for 60 inches / second is added to the registration adjustment value for 70 inches / second (FIG. 17(d)). The registration adjustment values ​​determined for each scanning speed are stored in ROM 52 in S208.

[0060] In this embodiment, the registration correction value is calculated from the difference between registration adjustment values ​​at similar scanning speeds. However, the method for calculating the registration correction value is not limited to this. For example, even if registration adjustment processing is performed at multiple scanning speeds, the registration correction value may be calculated using the difference between only the first scanning speed or only the second scanning speed. Alternatively, the registration correction value may be calculated by linear interpolation of the scanning speed and the registration adjustment value. Furthermore, as shown in FIG. 18 , the registration correction value may be calculated by calculating the difference between the first scanning speed (30 inches / second) and the first registration adjustment value determined by performing registration adjustment processing (FIG. 18(c-1)). Alternatively, the registration correction value may be calculated by calculating the difference between the second scanning speed (70 inches / second) and the second registration adjustment value determined by performing registration adjustment processing (FIG. 18(c-2)). These calculations may then be averaged to calculate the registration adjustment value (FIG. 18(d-2)). (FIG. 18(e)) As described above, by providing multiple scanning speeds for performing the registration adjustment process, the time required for the registration adjustment process increases compared to the first embodiment, but it is possible to perform registration adjustment with higher accuracy.

[0061] (Third embodiment) In the third embodiment, a method for calculating registration correction values ​​not only at scanning speeds where registration adjustment processing is not performed but also at printhead-to-printing medium distances will be described. The operation flow is shown in FIG. 19. In S301 of FIG. 19, the MPU 51 determines whether previous registration adjustment values ​​(adjustment values ​​1' to N') are stored in ROM 52. In this embodiment, in addition to scanning speeds 1' to n', registration adjustment values ​​1' to N' (N' = n' × m') for printhead-to-printing medium distances 1' to m' are also stored. The registration adjustment values ​​are shown in FIG. 20(a). The registration adjustment values ​​shown in FIG. 20 are registration adjustment values ​​obtained by adjusting the dot recording positions in the forward direction and the reverse direction for cyan (C). If the determination result indicates that registration adjustment values ​​are not stored in ROM 52, registration adjustment processing is performed at scanning speeds 1 to n and printhead-to-printing medium distances 1 to m (m ways) in S302, and registration adjustment values ​​1 to N are determined. If it is determined in S301 that a registration adjustment value is stored in ROM 52, the process proceeds to S303, where the scanning speed and printhead-to-printing medium distance that have been used most frequently in previous printing operations are selected as the first scanning speed and first printhead-to-printing medium distance. In this embodiment, the first scanning speed is 30 inches / second, and the first printhead-to-printing medium distance is 1.2 mm. As described in the first and second embodiments, S303 may be selected by the user. In S304, registration adjustment processing is performed using the first scanning speed and first printhead-to-printing medium distance selected in S303, and the first registration adjustment value is determined (see FIG. 20(b)). In S305, registration adjustment values ​​for scanning speeds and printhead-to-printing medium distances other than the first scanning speed and first printhead-to-printing medium distance are obtained and used as registration adjustment values ​​2' through N'. In S306, registration adjustment values ​​2' through N' are calculated. As shown in Figure 20(c), the registration correction values ​​for scanning speeds of 40 inches / second, 50 inches / second, 60 inches / second, and 70 inches / second for a first print head-to-printing medium distance of 1.2 mm are calculated using the method described in the first embodiment.(Fig. 20(d)) The registration correction values ​​at printhead-to-printing medium distances of 1.4 mm, 1.6 mm, 1.8 mm, and 2.0 mm are calculated using linear interpolation based on the change in the registration adjustment value for the printhead-to-printing medium distance at each printhead scanning speed, with reference to the registration adjustment values ​​1' through N'. Fig. 21 is a graph showing the relationship between the printhead-to-printing medium distance and the registration adjustment value at 30 inches / second for the registration adjustment values ​​1' through N'. From this graph, it can be seen that the printhead-to-printing medium distance and the registration adjustment value can be predicted linearly from the slope. From this relationship, it is possible to calculate the registration correction values ​​(registration correction values ​​2 through N) for printhead-to-printing medium distances 2 through m (m-1 ways) when the first printhead-to-printing medium distance is used as the reference distance at each scanning speed. The registration correction values ​​2 through N are shown in Fig. 20(e). Next, in S307, the registration adjustment value at the first scanning speed determined in S304 is added to the registration correction value calculated in S306 to calculate registration adjustment values ​​1 through N as shown in FIG. 20(f), and these values ​​are saved in ROM 52 in S308. In this embodiment, only one condition is set for the print head-to-printing medium distance for performing the registration adjustment process, but just as multiple scanning speeds are set in the second embodiment, multiple print head-to-printing medium distances can also be set. This makes it possible to determine registration adjustment values ​​with higher accuracy.

[0062] As described above, by calculating correction values ​​using past registration adjustment values ​​stored in ROM 52 not only for the scanning speed but also for the distance between the print head and the print medium, it is possible to predict registration adjustment values ​​with high accuracy, and the time required for registration adjustment processing can be significantly reduced.

[0063] (Fourth embodiment) As explained with reference to FIG. 13 , the effects of this embodiment are also effective for correcting registration adjustment values ​​between different printheads. In the next embodiment, a registration adjustment process after replacing a printhead that has been used for a long time will be described in detail. In conventional inkjet printing devices, registration adjustment is often performed when replacing a printhead. In such cases, registration adjustment is performed for each printhead scanning speed and each printhead-to-printing medium distance to determine the registration adjustment value. In this embodiment, as in the first to third embodiments, registration adjustment is performed for some scanning speeds and printhead-to-printing medium distances, and registration adjustment values ​​are determined using the registration correction value for other printing conditions. A specific operational flow is shown in FIG. 22 . When performing the first registration adjustment process after replacing a printhead, the user first sets a first scanning speed and a first printhead-to-printing medium distance at which the registration adjustment process will be performed in S401. In S401, the settings may be automatically set based on the number of times the printing conditions have been used, stored in ROM 52, as described in the third embodiment, or multiple scanning speeds and printhead-to-printing medium distances may be set. In S402, a registration adjustment process is performed at a first scanning speed and a first printhead-to-recording medium distance to determine a first registration adjustment value. In S403, the registration adjustment values ​​determined when the registration adjustment process was performed on the printhead before replacement (hereinafter also referred to as the previous printhead) are used from ROM 52 to obtain registration adjustment values ​​for printing conditions other than the first scanning speed and the first printhead-to-recording medium distance. (2' to N' Registration Adjustment Values) If registration adjustment was performed multiple times on the previous printhead and multiple registration adjustment values ​​are stored in ROM 52, it is preferable to use the oldest of the stored registration adjustment values, i.e., the registration adjustment value determined when the registration adjustment process was first performed on the previous printhead. This is because it reduces the impact of changes in ink ejection speed over long-term printhead use. Using the oldest registration adjustment value allows the registration adjustment values ​​to be inherited from both the previous printhead and the replaced printhead without any changes due to durability, thereby maintaining high adjustment accuracy. Next, in S404, the 2' to N' registration correction values ​​are calculated from the obtained 2' to N' registration adjustment values. The method for calculating the registration correction value is as described in the third embodiment.The second to Nth registration adjustment values ​​are calculated from the calculated second to Nth registration correction values ​​and the first registration adjustment value determined in S402, and are stored in the ROM 52 in S406.

[0064] As described above, even after replacing the recording head, it is possible to calculate the registration correction value by using the registration adjustment value of the previous recording head stored in ROM 52, thereby significantly reducing the time required for the registration adjustment process after replacing the recording head.

[0065] (Fifth embodiment) In the fifth embodiment, the registration adjustment values ​​at any of a plurality of scanning speeds are compared with the registration adjustment values ​​at the same scanning speeds stored in ROM 52. If the difference between these values ​​is greater than a predetermined value, the registration adjustment values ​​are performed at all scanning speeds. If the difference is less than the predetermined value, the registration correction values ​​are calculated using the method described in the first to fourth embodiments to determine the registration adjustment values. The operation flow is shown in FIG. 23. First, as in the first to third embodiments, the MPU 51 determines whether registration adjustment values ​​determined in a previous registration adjustment process are stored in ROM 52. If not, the process proceeds to S402, where the registration adjustment process is performed at all scanning speeds to determine the registration adjustment values. If it is determined that the registration adjustment values ​​are stored, the process proceeds to S403, where the user selects any scanning speed (a first scanning speed and a second scanning speed). In this embodiment, the first scanning speed is 40 inches / second, and the second scanning speed is 60 inches / second. Next, in S404, the registration adjustment values ​​at the first scanning speed and the second scanning speed are determined by performing the registration adjustment process. In S405, the registration adjustment values ​​for the first and second scanning speeds of 30 inches / second and 40 inches / second, which are the same as the first and second scanning speeds selected by the user in S403, are obtained from the ROM (first registration adjustment value, second registration adjustment value). In S406, the difference between the first and second registration adjustment values ​​determined in S404 (|first registration adjustment value - second registration adjustment value|) is calculated and compared with the difference between the first and second registration adjustment values ​​obtained in S405 (|first registration adjustment value - second registration adjustment value|). As a result of the comparison, the MPU 51 determines whether the difference between the two is equal to or greater than a predetermined value. In this embodiment, the predetermined value is "5." The predetermined value may be a value determined based on the adjustment resolution of the registration adjustment process in the inkjet printing apparatus, or may be set based on the image quality the user desires to print. If ||First registration adjustment value - Second registration adjustment value| - |First' registration adjustment value - Second' registration adjustment value|| is 5 or more, it is determined that there is a large change in dot recording position at other scanning speeds as well, and in S407 registration adjustment processing is performed at scanning speeds 3 to n, and these are determined as registration adjustment values ​​3 to n.On the other hand, if ||first registration adjustment value - second registration adjustment value| - |1' registration adjustment value - 2' registration adjustment value|| is less than the predetermined value 5, it is determined that registration correction values ​​can be calculated with sufficiently high accuracy, and the 3' to n' registration adjustment values ​​are acquired in S408, the 3rd to nth registration correction values ​​are calculated in S409, and the 3rd to nth registration adjustment values ​​are determined in S410. The calculation and determination methods in each step are the same as those described in the first to fourth embodiments. The 1st to nth registration adjustment values ​​thus determined are stored in ROM 52 in S411.

[0066] As described above, in the fifth embodiment, a determination is made as to whether to perform registration adjustment processing at all scanning speeds and print head-to-printing medium distances as needed by comparing the registration adjustment values ​​determined by actually performing registration adjustment processing with the registration adjustment values ​​stored in ROM 52. This makes it possible to maintain high-precision adjustment even when the dot printing position changes significantly over time due to the specifications of the inkjet printing device.

Claims

1. a print head having a plurality of nozzle rows for ejecting ink; a carriage for scanning the recording head at at least two or more speeds; a first adjusting means for adjusting the timing of ejecting the ink from the recording head in accordance with the scanning speed of the carriage; a data storage means for storing the adjusted ejection timing as an adjustment value; a first correction value calculation means for calculating a correction value for each scanning speed of the carriage using the adjustment value stored in the data storage means; An inkjet recording apparatus comprising: an inkjet recording device characterized in that, when adjustment of the ejection timing is executed by the first adjustment means with no adjustment value stored in the data storage means, the first correction value calculation means adjusts the ejection timing at n scanning speeds; when adjustment of the ejection timing is executed by the first adjustment means with adjustment values ​​stored in the data storage means, the first adjustment means adjusts the ejection timing at n-1 or fewer scanning speeds; and for adjustment values ​​at scanning speeds where the ejection timing is not adjusted, the first correction value calculation means uses a correction value calculated based on the adjustment value of the first adjustment means.

2. 2. The inkjet recording apparatus according to claim 1, wherein the scanning speed at which the ejection timing adjustment is performed includes the scanning speed most frequently used in the recording operation of the inkjet recording apparatus.

3. 2. The inkjet recording apparatus according to claim 1, wherein the correction value calculated by the first correction value calculation means is a difference between an adjustment value at a scanning speed at which the ejection timing is adjusted and an adjustment value at a scanning speed at which the ejection timing is not adjusted.

4. a second adjusting means for adjusting the ejection timing in accordance with the distance between the recording head and the recording medium; a second correction value calculation means for calculating a correction value for each distance between the recording head and the recording medium using the adjustment values ​​stored in the data storage means; Furthermore, When the adjustment of the ejection timing by the second adjustment means is executed in a state where the adjustment value is not stored in the data storage means, when the ejection timing is adjusted for m distances between the print head and the print medium, When the adjustment of the ejection timing is executed by the second adjustment means with the adjustment value stored in the data storage means, the ejection timing is adjusted for m-1 or less distances between the print head and the print medium, and the correction value calculated by the second correction value calculation means is used for the adjustment value for the distance between the print head and the print medium that has not been adjusted.

2. The ink jet recording apparatus according to claim 1, wherein:

5. 5. The ink jet recording apparatus according to claim 4, wherein the correction value calculated by the second correction value calculation means is calculated based on a relationship of first-order linear interpolation of an adjustment value with respect to a distance between the recording head and the recording medium.

6. The recording head is replaceable, When the ejection timing adjustment is performed on the replaced recording head while the adjustment value of the ejection timing of the recording head before replacement is stored in the data storage means, a correction value calculated from the adjustment value of the recording head before replacement stored in the data storage means is used for the adjustment value of the scanning speed or the distance between the recording head and the recording medium that has not been adjusted.

2. The ink jet recording apparatus according to claim 1, wherein:

7. As the correction value, of the adjustment values ​​stored in the data storage means, the adjustment value that was first stored in the adjustment of the ejection timing that was performed when the recording head before replacement was installed is used.

7. The ink jet recording apparatus according to claim 6, wherein:

8. When the ejection timing adjustment is performed with the adjustment values ​​stored in the data storage means, the ejection timing adjustment is performed for at least two or more scanning speeds or between the print head and the print medium, and when the difference between the two or more acquired adjustment values ​​is A and the difference between the same scanning speed or the adjustment value between the print head and the print medium stored in the data storage means is B, the apparatus further comprises a determination means for determining whether the absolute value of the difference between A and B is equal to or greater than a predetermined value, If the determining means determines that the difference is equal to or greater than a predetermined value, the ejection timing is adjusted for the unadjusted scanning speed or between the recording head and the recording medium, and if the determining means determines that the difference is less than the predetermined value, the correction value calculated by the first or second correction value calculating means is used for the unadjusted scanning speed or between the recording head and the recording medium.

2. The ink jet recording apparatus according to claim 1, wherein:

9. a print head having a plurality of nozzle rows for ejecting ink; a carriage for scanning the recording head at at least two or more speeds; A method for adjusting a printing position in a printing apparatus comprising: a first adjusting step of adjusting the timing of ejecting the ink from the recording head in accordance with the scanning speed of the carriage; a storing step of storing the adjusted ejection timing as an adjustment value in a data storing means; a first correction value calculation step of calculating a correction value for each scanning speed of the carriage using the stored adjustment values; a correction value calculated in the first correction value calculation step in the first adjustment step, wherein if the adjustment of the ejection timing is executed in the first adjustment step while no adjustment value is stored in the data storage means, the ejection timing is adjusted at n scanning speeds in the first adjustment step, and if the adjustment of the ejection timing is executed in the first adjustment step while the adjustment value is stored in the data storage means, the ejection timing is adjusted at n-1 or fewer scanning speeds in the first adjustment step, and the correction value calculated in the first correction value calculation step in the first adjustment step is used as the adjustment value for the scanning speed at which the ejection timing is not adjusted.

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