JP2013086335A - Method of inkjet recording and inkjet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adequately correct a deposited position of an ink droplet when a recorder performs recording while accelerating a recording head.SOLUTION: This recorder records a test chart in which identical patterns are repeated in a scanning direction, on a recording medium while moving the recording head at a constant speed. Next, the recorder corrects an ink ejection timing, and records the test chart again so as to superpose it on the recorded test chart while accelerating the recording head. The recorder performs the recording in each of cases of a plurality of correction values. After that, the recorder detects a degree of superposition of patterns at a plurality of positions on the recorded test chart in the scanning direction in each of the cases of the plurality of correction values, and thereby the recorder specifies a correction value of which the degree of superposition becomes the largest at each position among the plurality of correction values. The recorder ejects ink at the ink ejection timing obtained by correction in accordance with each of the specified correction values, and thereby the recorder performs the recording on the recording medium while accelerating the recording head.

Description

  The present invention relates to an ink jet recording method and apparatus for printing on a recording medium while scanning a recording head.

  In a serial scan type ink jet recording apparatus that performs printing by scanning a recording head in a direction intersecting the conveyance direction of the recording medium, higher speed is required. In order to meet such demands, it is necessary to increase the speed of the carriage on which the recording head is mounted. However, this requires a wide acceleration / deceleration region, which increases the size of the ink jet recording apparatus. For such a problem, it is considered that printing is performed even while the carriage is accelerating / decelerating so that a part of the acceleration / deceleration area overlaps with the printing area to prevent an increase in apparatus size (Patent Document 1). ).

JP 2008-221672 A

  However, in Patent Document 1, since the landing position is corrected based only on the speed of the accelerating / decelerating carriage, the influence of the change in the posture of the carriage during acceleration is not taken into consideration. Therefore, the landing position of the ink droplet due to the inclination of the carriage posture cannot be corrected.

  An object of the present invention is to solve such conventional problems. In view of the above points, an object of the present invention is to provide an ink jet recording method and apparatus that appropriately corrects the landing positions of ink droplets when printing is performed while accelerating a recording head.

  In order to solve the above problems, an ink jet recording method according to the present invention is an ink jet recording method for performing recording on the recording medium by scanning a recording head in a scanning direction that intersects a conveying direction for conveying the recording medium. A first step of recording on the recording medium a test chart in which the same pattern is repeated in the scanning direction while scanning the recording head at a constant speed, and the ink ejection timing at the time of recording in the first step is corrected by a correction value Then, while accelerating the recording head, the test chart is recorded again so as to overlap the test chart recorded in the first process, and the recording is performed for each of a plurality of correction values. The test chart recorded by the second step in the case of each of the plurality of correction values after recording by the second step At a plurality of locations in the scanning direction, a third step for detecting the degree of overlap between the pattern recorded by the first step and the pattern recorded by the second step, and the degree of overlap for each of the plurality of locations. The print head is accelerated while ejecting ink at the fourth step of specifying the largest correction value from the plurality of correction values and the ink discharge timing corrected by the correction values specified in the fourth step. And a fifth step of recording on the recording medium.

  According to the present invention, when printing is performed while accelerating the recording head, the landing position of the ink droplet can be corrected appropriately.

1 is an external perspective view showing an outline of a configuration of an ink jet recording apparatus. It is a block diagram which shows the control structure of an inkjet recording device. FIG. 3 is a diagram illustrating a structure around a recording head. FIG. 2 is a diagram schematically illustrating a configuration of a nozzle row of a recording head. It is the figure which looked at the carriage from the side. It is a figure for demonstrating the chart which overlaps the adjustment pattern with respect to a reference | standard pattern. It is a figure for demonstrating the attitude | position fluctuation | variation of a carriage. It is a figure which shows the change of the reflection intensity with respect to a detection position about each part of a nozzle row. 6 is a flowchart illustrating a procedure of a correction value acquisition method according to the first embodiment. It is a figure which shows the printing position of the chart in a present Example. It is a figure which shows the correction value applied about each part of the divided nozzle row. It is a figure which shows the value of five reflection intensity corresponding to each detection position. It is a figure which shows the positional relationship of a main droplet and a satellite. 10 is a flowchart illustrating a procedure of a correction value acquisition method according to the second embodiment. It is a figure which shows the printing position of the chart in a present Example. It is a figure which shows the positional relationship of the droplet group from which reflection intensity becomes the maximum.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the present invention according to the claims, and all combinations of features described in the present embodiments are not necessarily essential to the solution means of the present invention. . The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.

[Example 1]
[Description of Inkjet Recording Device]
FIG. 1 is an external perspective view showing an outline of the configuration of an ink jet recording apparatus according to the present embodiment. The recording apparatus 100 transmits the driving force generated by the carriage motor M1 from the transmission mechanism 104 to the carriage 102 on which the recording head 103 that performs recording by discharging ink according to the ink jet method is transmitted, and reciprocates the carriage 102 in the arrow A direction. . A recording medium P such as recording paper is fed through a paper feeding mechanism 105, conveyed to a recording position, and the carriage 102 is reciprocated in a scanning direction intersecting the conveying direction. Recording is performed by ejecting ink onto P.

  Further, in order to maintain the state of the recording head 103 satisfactorily, the carriage 102 is moved to the position of the recovery device 110, and the ejection recovery process of the recording head 103 is performed intermittently. In addition to mounting the recording head 103 on the carriage 102 of the recording apparatus 100, an ink cartridge 106 for storing ink to be supplied to the recording head 103 is mounted. The ink cartridge 106 is detachable from the carriage 102.

  The recording apparatus 100 shown in FIG. 1 can perform color recording. For this reason, the carriage 102 contains four inks containing magenta (M), cyan (C), yellow (Y), and black (K) inks, respectively. An ink cartridge is installed. These four ink cartridges are detachable independently.

  The carriage 102 and the recording head 103 can achieve and maintain a required electrical connection by properly contacting the joint surfaces of both members. The recording head 103 selectively discharges ink from a plurality of discharge ports and records by applying energy according to a recording signal. The recording head 103 employs an ink jet system that ejects ink using thermal energy. The recording head 103 includes an electrothermal transducer to generate thermal energy and ejects ink from an ejection port. The electrothermal transducer is provided corresponding to each of the ejection ports, and ink is ejected from the corresponding ejection port by applying a pulse voltage to the corresponding electrothermal transducer in accordance with the recording signal. Note that the present invention is not limited thereto, and an ink jet recording head using a piezoelectric element, an electrostatic element, or the like may be used.

  As shown in FIG. 1, the carriage 102 is connected to a part of the driving belt 107 of the transmission mechanism 104 that transmits the driving force of the carriage motor M <b> 1, and slides in the direction of arrow A along the guide shaft 113. It is guided and supported freely. Accordingly, the carriage 102 reciprocates along the guide shaft 113 by forward rotation and reverse rotation of the carriage motor M1. In addition, a scale 108 (CR encoder film) is provided for indicating the absolute position of the carriage 102 along the movement direction (arrow A direction) of the carriage 102. In this embodiment, the scale 108 uses a transparent PET film with black bars printed at the required pitch, one of which is fixed to the chassis 109 and the other is supported by a leaf spring (not shown). Yes.

  Further, the recording apparatus 100 is provided with a platen (not shown) facing the discharge port surface where the discharge port (not shown) of the recording head 103 is formed. The carriage 102 on which the recording head 103 is mounted is reciprocated by the driving force of the carriage motor M1, and at the same time, a recording signal is given to the recording head 103 and ink is ejected, whereby the entire width of the recording medium P conveyed on the platen. Recording is done over

  Further, the transport roller 114 in FIG. 1 is driven by a transport motor M2 to transport the recording medium P. The pinch roller 115 abuts the recording medium P against the transport roller 114 by a spring (not shown). Further, the pinch roller holder 116 supports the pinch roller 115 rotatably. Further, the transport roller gear 117 is fixed to one end of the transport roller 114. The transport roller 114 is driven by the rotation of the transport motor M2 transmitted to the transport roller gear 117 via an intermediate gear (not shown).

  The discharge roller 120 discharges the recording medium P on which an image is formed by the recording head 103 to the outside of the ink jet recording apparatus. The discharge roller 120 is driven by the rotation of the transport motor M2. The discharge roller 120 abuts on a spur roller (not shown) that presses the recording medium P by a spring (not shown). The spur holder 122 rotatably supports the spur roller.

  The recording device 100 is provided with a recovery device 110 for recovering the ejection failure of the recording head 103. As shown in FIG. 1, the recovery device 110 is positioned outside the reciprocating motion range (outside the recording area) for the recording operation of the carriage 102 on which the recording head 103 is mounted (for example, a position corresponding to the home position). ).

  The recovery device 110 includes a capping mechanism 111 for capping the ejection port surface of the recording head 103 and a wiping mechanism 112 for cleaning the ejection port surface of the recording head 103. The recovery device 110 forcibly discharges ink from the discharge port by a suction pump or the like in the recovery device in conjunction with the capping of the discharge port surface by the capping mechanism 111, and the viscosity in the ink flow path of the recording head 103 is increased. A discharge recovery process such as removing ink and bubbles is performed.

  Further, at the time of non-recording operation, etc., the ejection port surface of the recording head 103 is capped by the capping mechanism 111, whereby the recording head 103 can be protected and ink evaporation and drying can be prevented. On the other hand, the wiping mechanism 112 is disposed in the vicinity of the capping mechanism 111 and wipes ink droplets adhering to the discharge port surface of the recording head 103. The capping mechanism 111 and the wiping mechanism 112 can keep the ink ejection state of the recording head 103 normal.

[Control configuration of inkjet recording apparatus]
FIG. 2 is a block diagram showing a control configuration of the recording apparatus 100 shown in FIG. The control unit 210 includes an MPU 211 and a ROM 212 that stores a program corresponding to a control sequence described later, a required table, and other fixed data. The control unit 210 includes a special application integrated circuit (ASIC) 213 that generates control signals for controlling the carriage motor M1 and the transport motor M2 and controlling the recording head 103. Further, the control unit 210 includes a RAM 214 provided with an image data development area, a work area for program execution, and the like, and a system bus 215 that connects the blocks to each other to exchange data. In addition, the control unit 210 includes an A / D converter 216 that inputs analog signals from the sensor group described below, performs A / D conversion, and supplies digital signals to the MPU 211.

  In FIG. 2, a host apparatus 300 is a computer (or an image reading reader, digital camera, or the like) serving as a supply source of image data. Image data, commands, status signals, and the like are transmitted and received between the host apparatus 300 and the recording apparatus 100 via an interface (I / F) 201.

The switch group 220 includes switches for receiving command inputs from the operator. The switches are a power switch 221, a print switch 222 for instructing start of printing, and a recovery switch 223 for instructing start of processing (recovery processing) for maintaining the ink ejection performance of the recording head 103 in a good state. including. The sensor group 230 is a sensor group for detecting the state of the recording apparatus 100. The sensor group 230 includes a position sensor 231 such as a photocoupler for detecting the home position, a temperature sensor 232 provided at an appropriate location of the recording apparatus 100 for detecting the environmental temperature, and the like. Carriage motor driver 240 Drives a carriage motor M1 for reciprocally scanning the carriage 102 in the direction of arrow A shown in FIG. Further, the transport motor driver 250 drives a transport motor M2 for transporting the recording medium P. The ASIC 213 transfers drive data of the printing element (discharge heater) to the print head while directly accessing the storage area of the ROM 212 during print scanning by the print head 103.

[Structure around the recording head]
FIG. 3 is a diagram showing the structure around the recording head 103. The recording head 103 is supported by a carriage 102, and the carriage 102 is connected to a motor (not shown) with a belt so as to be able to reciprocate. In FIG. 3, the standby position 301 of the recording head 103 is also referred to as a home position (HP). A position corresponding to the opposite side across the sheet P as a recording medium is also referred to as a back position (BP). The position of the carriage 102 is managed by a linear scale arranged along the carriage scanning direction. The position of the carriage 102 is managed by optically reading the linear scale with an encoder sensor (not shown) provided in the carriage 102. Ink ejection timing from the recording head 103 (hereinafter also simply referred to as ejection timing) is also determined based on a read pulse output from the encoder sensor. The landing position of the ink droplet on the paper P is adjusted by delaying or speeding up the discharge timing during carriage scanning according to a parameter for controlling the discharge timing. The parameter for controlling the ejection timing of the ink droplet is, for example, the amount of deviation (number of dots) of the landing position in the scanning direction.

  FIG. 4 is a diagram schematically showing the configuration of the nozzle array of the recording head 103. In the recording head 103, four nozzle rows are arranged with a predetermined interval. Each nozzle row 401 has a plurality of nozzles arranged in a row. Hereinafter, each nozzle row is also referred to as a chip. Each chip 401 corresponds to a different ink color. For example, chip 0 corresponds to black (K) ink, chip 1 corresponds to yellow (Y) ink, chip 2 corresponds to magenta (M) ink, and chip 3 corresponds to cyan (C) ink. Corresponding to

  FIG. 5 is a view of the carriage 102 as viewed from the side. In this embodiment, the carriage 102 includes a reflective sensor 501. The sensor 501 has a function like a densitometer that reads RGB reflection intensities. The sensor 501 includes a light emitting unit 502 that is an LED that emits light corresponding to RGB, and a light receiving unit 503 that is a phototransistor. As shown in FIG. 5, the light emitted from the light emitting unit 502 is reflected by the paper P, and the light receiving unit 503 receives the reflected light. The electric signal output from the light receiving unit 503 is sent to an AD converter (not shown) via an amplifier circuit and the like, and the intensity of the reflected light is detected. The sensor 501 has an aperture so that a square of about 5 × 5 mm on the paper P becomes a detection spot. The light quantity distribution in the detection spot is almost uniform.

  In this embodiment, the adjustment pattern 602 is overprinted with respect to the reference pattern 601 to print one test chart (hereinafter also simply referred to as a chart). The reference pattern 601 and the adjustment pattern 602 are the same pattern, and as shown in FIG. 6A, ejection of ink droplets and non-ejection are repeated for every four dots. However, in this embodiment, the adjustment pattern 602 is shifted and overlapped with the reference pattern 601 by controlling the ejection timing of the ink droplets.

  Here, the relationship between the shift amount and the reflection intensity (density) will be described. As shown in FIG. 6B, when the reference pattern 601 and the adjustment pattern 602 overlap with each other by various shift amounts, the reflection intensity also varies depending on the state of each shift. That is, when the reference pattern 601 and the adjustment pattern 602 coincide and overlap and the area factor is the smallest, the reflection intensity is the largest (that is, the density is the smallest).

  Next, posture variation during acceleration of the carriage 102 will be described. FIG. 7 is a diagram for explaining the posture variation of the carriage 102. FIG. 7A shows a case where the carriage 102 is at a constant speed (constant speed), and FIG. 7B shows a case where the carriage 102 is accelerating. During the constant speed, the ink droplets ejected from the recording head 103 are subjected to an inertial force due to the speed of the carriage 102 before landing on the paper P, and land with a shift in the scanning direction. Since the deviation amount is constant during the constant speed, it can be corrected by adjusting the normal ejection timing (registration adjustment).

  However, as shown in FIG. 7B, when the carriage 102 is accelerated (including the case where the acceleration is not constant), the carriage 102 is pulled by the belt in the scanning direction in order to accelerate the carriage 102. That is, as shown on the left side of FIG. 7B, the posture of the carriage 102 changes (tilts) in such a direction as to rotate around the guide member. As a result, the landing position of the ink droplet also changes. In addition, since the carriage speed changes during acceleration, the landing position of the ink droplet also changes during acceleration, and correction cannot be made by adjusting the normal ejection timing (registration adjustment).

  In this embodiment, first, the reference pattern 601 is printed by operating the carriage 102 at a constant speed. In that case, since the deviation of the landing position can be corrected by the normal registration adjustment as described above, the printed chart is as shown in FIG. That is, the reference pattern 601 can be said to be an ideal landing position of an ink droplet. Next, printing is performed so as to overlap the reference pattern 601 while accelerating the carriage 102. At that time, the ejection timing of the ink droplets is controlled in accordance with a predetermined correction value.

  If the carriage 102 when overprinting the reference pattern 601 has a constant speed, the reflection intensity is constant in the chart regardless of whether the reference pattern 601 and the adjustment pattern 602 overlap each other. Become. This is because the degree of deviation between the reference pattern 601 and the adjustment pattern 602 is constant over the entire chart.

  However, if the carriage 102 during acceleration with respect to the reference pattern 601 is accelerating, the speed changes even if the ejection timing is controlled with a predetermined correction value. Therefore, the deviation between the reference pattern 601 and the adjustment pattern 602 changes over the entire chart. Referring to FIG. 8, for example, in the case of “II”, there is a medium shift near the detection position 0 to 20 mm, and the shift becomes closer to the constant speed state of the carriage 102 near the detection position 50 mm. Indicates that it is growing. In the case of “IV”, there is a medium shift near the detection position of 0 to 20 mm, and the shift disappears as the carriage 102 near the detection position near 50 mm approaches the constant speed state. . The difference between “II” and “IV” depends on how the correction amount of the landing position of the ink droplet is determined. That is, in the case of “IV”, the correction amount is “0”, and the landing position of the ink droplet is deviated from the ideal position (reference pattern 601) by the acceleration of the carriage 102 around 0 to 20 mm. However, when the carriage 102 reaches a constant speed near 50 mm, the same result as when the reference pattern 601 is printed is obtained, so that there is no deviation between the two. Here, the detection position refers to the distance from the position where the carriage 102 starts to accelerate.

  On the other hand, in the case of “II”, a correction amount for correcting a deviation near 0 to 20 mm in the case of “IV” is determined. As a result, in the vicinity of 0 to 20 mm, the deviation is corrected to some extent as compared with “IV”. However, as the speed becomes constant, the correction amount is shifted. As a matter of course, the difference in deviation in each of the cases “I”, “III”, and “V” also depends on the determined difference in correction amount as described above.

  That is, when printing is performed by ejecting ink droplets while accelerating the carriage 102 in the chart area, the maximum reflection intensity (that is, the entire reflection area (that is, the entire chart area) can be used unless different correction values are used in the chart areas. It can be seen that the ink droplet does not become constant at the ideal position (same as the landing position at the constant speed).

  In the present embodiment, the test recording of the chart is overprinted for each of a plurality of correction values in two cases of constant speed and acceleration of the carriage 102. The aim is to obtain an optimum correction value at each position based on the degree of overlap at each position in the chart.

  FIG. 9 is a flowchart showing the procedure of the correction value acquisition method in the present embodiment. The process illustrated in FIG. 9 is executed by the MPU 211 of the recording apparatus 100, for example. First, the carriage 102 is driven in the forward direction at a constant speed from the BP position shown in FIG. 10, and the reference pattern 601 is printed on the recording medium (S901: an example of the first test recording). In this case, the driving may be performed at a low speed that does not require an acceleration region. However, in actual operation, it is conceivable that the posture of the carriage 102 becomes unstable due to different conditions from the low-speed driving. . Therefore, as shown in FIG. 10, the chart 1001 may be printed near the center of the paper P so that a sufficient acceleration area of the carriage 102 can be secured. As a result, the carriage 102 can be set to the speed of the carriage 102 in the actual operation. The chart 1001 has a sufficient length of 101.6 mm (4 inches) in consideration of the carriage 102 performing accelerated printing in the chart in the subsequent stage. The chart 1001 may be printed by a plurality of scans according to the driving conditions of the recording head 103.

  After recording the reference pattern 601 on the recording medium, the carriage 102 is returned to the BP position, and the adjustment pattern 602 is overprinted on the reference pattern 601 while accelerating again from the predetermined acceleration start position in the forward direction (S902: Example of second test record). At the time of printing in S902, the speed and posture of the carriage 102 change due to acceleration, so that ink droplets land at positions corresponding to the change. As described above, in this embodiment, this overstrike is performed with a plurality of correction values. In this embodiment, in particular, as shown in FIG. 11A, the nozzles of the recording head 103 are divided into five sections in the nozzle row direction, and different correction values are assigned to the respective nozzle sets. By configuring in this way, it is possible to obtain a printing result based on a plurality of correction values by one-time overprinting. FIG. 11B is a diagram conceptually showing a chart when the recording head 103 is scanned by the nozzle row divided into five as shown in FIG. When the printed chart as shown in FIG. 11B overlaps the reference pattern 601, the density change (reflection intensity change) with respect to the detection position is different in each of the parts I to V. FIG. 8 can be said to be a diagram showing a change in reflection intensity of each part as a result of accelerating the recording head 103 divided as shown in FIG.

  While the carriage 102 is scanned over the entire area of the chart 1001 with the reflection intensity of the chart 1001 overlaid in S903, the sensor 501 measures a plurality of locations along the scanning direction on the test chart (S903). FIG. 8 described above shows the result. In the case of “IV”, the correction value is 0. Therefore, when the carriage 102 accelerates to a constant speed state, the same landing position as that of the reference pattern 601 is obtained and the reflection intensity is maximized. On the other hand, the case where the correction value is set strongly is the case of “I” to “III” in FIG. In those cases, at the beginning of the detection position, the correction value results in the same landing position as that of the reference pattern 601 and shows a high reflection intensity. However, when the carriage 102 is in a constant speed state, the correction value acts excessively, the landing position is shifted from the reference pattern 601, and the reflection intensity is reduced.

  Next, the results as shown in FIG. 8 are arranged as a plurality (five in this example) of reflection intensity values corresponding to the reflection intensity detection positions in the chart 1001 (S904). FIG. 12 is a diagram showing five reflection intensity values corresponding to the detection positions. FIG. 12B is a graph showing five reflection intensity values corresponding to the detection position of 30.5 mm in the table shown in FIG.

  In FIG. 12A, detection positions are extracted at intervals of 0.5 inches. That is, assuming that detection positions for 4 inches are extracted, FIG. 12A is an 8 × 5 matrix. Further, the correction value between the detection positions may be constant, for example, an average value between the two detection positions.

  In this embodiment, a correction value that maximizes the reflection intensity at each detection position is specified from the table or graph shown in FIG. 12 (S905). For example, from FIG. 12B, +4 is specified as the correction value at the detection position of 30.5 mm. That is, at each detection position, a correction value that minimizes the deviation from the reference pattern 601 is specified. However, in order to improve accuracy, the correction value may be calculated using a fitting process or the like. good. Between the above-mentioned 4 inches, optimal correction values can be obtained at each of the eight detection positions. Here, between the detection positions, a correction value may be obtained by linear interpolation. Near the end of the chart 1001, the carriage 102 has the same constant speed as when the reference pattern 601 is printed, so the optimum correction value is zero.

  With the process shown in FIG. 9, ink droplets can be landed at the same position as in the case of constant speed even during actual recording in which printing is performed based on data to be printed while the carriage 102 is accelerated. In the recording apparatus 100, the correction value specified from the processing shown in FIG. 9, the predetermined registration adjustment value, and the acceleration parameter used when accelerating from the acceleration start position of the carriage 102 are taken into consideration, and the ink droplets are detected. The final discharge timing is controlled.

  The processing in FIG. 9 may be performed for each acceleration parameter when there are a plurality of acceleration parameters (acceleration, etc.) of the carriage 102. 9 can also be applied when the carriage 102 is decelerated from a constant speed. The processing of FIG. 9 may be performed for each ink color, but an optimum correction value is acquired as a representative of the nozzle row at the right end or the left end of the carriage 102, and the nozzle rows in between (chip 1 and chip 2 in FIG. 4). The correction value may be obtained by interpolation. As a result, the number of processes in FIG. 9 can be reduced.

  According to the present embodiment, since the optimum correction value at each detection position is acquired based on the chart 1001 printed by actually accelerating the carriage 102, it is possible to take into account the posture variation of the carriage 102, the driving conditions, and the like. it can. In addition, since the correction value is acquired according to the relative distance from the acceleration start position of the carriage 102, the width of the paper P does not need to be taken into consideration when acquiring the correction value.

[Example 2]
Ink droplets ejected from the recording head 103 may generate small droplets called satellites different from the main droplets. In this embodiment, a correction value acquisition method that takes into account the influence of satellites will be described.

  Satellites are known to have a slower flight speed than main droplets, and are more susceptible to carriage speed due to the longer flight time to land on the paper surface. In particular, when printing is performed by scanning the carriage 102 in the forward direction and the backward direction, the satellite lands on the opposite side of the main droplet in each direction. Therefore, in the case of bidirectional printing, it can be said that the influence on the satellite positional deviation is extremely large. In other words, when the landing positions of ink droplets with such satellites are aligned in both directions, it is preferable in terms of image that the positions of the ink droplets of the main droplet and satellite are aligned in an average direction.

  For example, when printing is performed while accelerating in the forward direction, droplet groups land as shown in FIG. 13A in the initial acceleration region where the carriage speed is slow. In FIG. 13, the direction from the right side to the left side in the figure is the forward direction. The distance between the satellite and the main droplet decreases as the carriage speed decreases. As the acceleration of the carriage 102 proceeds, the distance between the satellite and the main droplet increases as shown in FIG. On the other hand, assuming that the carriage 102 is scanning at a constant speed in the backward direction, as shown in FIG. 13C, the landing position of the satellite is opposite and the droplet group is landed. That is, in both directions, it can be said that the positional relationship between the main droplet and the satellite changes depending on whether the carriage 102 is being accelerated (or decelerated) or at a constant speed.

  Therefore, in the present embodiment, a correction value that takes into account the change in the positional relationship between the main droplet and the satellite due to the acceleration / deceleration of the carriage 102 is acquired. FIG. 14 is a flowchart showing the procedure of the correction value acquisition method in this embodiment. First, the carriage 102 is scanned in the backward direction at a constant speed, and the reference pattern 601 is printed (S1401). In this embodiment, a chart 1501 is printed as shown in FIG. 15 so that an acceleration region required to reach a constant speed state in actual driving of the carriage 102 can be obtained on the BP side. Next, the adjustment pattern 602 is printed while accelerating the carriage 102 in the forward direction opposite to S1401 (S1402). The processing after S1403 is the same as S903 to S905 in FIG.

  When the chart is printed in this way, the landing position where the reflection intensity is maximized is as shown in FIG. FIG. 16A shows a case where the overlap between the droplet group landed in the initial acceleration state in the forward direction and the droplet group landed in the constant speed state in the backward direction shows the maximum reflection intensity. FIG. 16B shows a case where the overlap between the droplet group landed in the second half of acceleration in the forward direction and the droplet group landed in the constant speed state in the backward direction shows the maximum reflection intensity. . As can be seen from both, the reflection intensity increases as they overlap so that the reciprocal positional relationship of the entire droplet group matches.

  According to this embodiment, it is possible to correct the deviation of the landing positions in both directions in consideration of satellites. Further, since the optimum correction value at each detection position is acquired based on the chart 1501 printed by actually accelerating the carriage 102 in the forward direction, the satellite landing position of the carriage 102 due to the attitude variation of the carriage 102, the driving conditions, etc. Variations can also be taken into account.

Claims (5)

An inkjet recording method for recording on the recording medium by scanning a recording head in a scanning direction that intersects a conveying direction for conveying the recording medium,
A first step of recording on the recording medium a test chart in which the same pattern is repeated in the scanning direction while scanning the recording head at a constant speed;
The ink ejection timing at the time of recording in the first step is corrected by a correction value, and while accelerating the recording head, the test chart is recorded again so as to overlap the test chart recorded in the first step, A second step of performing the recording for each of a plurality of correction values;
After the recording in the second step, the pattern recorded in the first step and the second pattern at the plurality of locations in the scanning direction of the test chart recorded in the second step in the case of each of the plurality of correction values. A third step of detecting the degree of overlap with the pattern recorded by the step;
For each of the plurality of locations, a fourth step of specifying a correction value that maximizes the degree of overlap from the plurality of correction values;
A fifth step of performing recording on the recording medium while accelerating the recording head while ejecting ink at the ink ejection timing corrected by the correction values specified in the fourth step;
An ink jet recording method comprising:   The inkjet recording method according to claim 1, wherein the third step detects the degree of overlap by measuring the density of the test chart recorded on the recording medium. The second step divides the nozzle array of the recording head into a plurality of portions, assigns each of the plurality of correction values to each of the divided portions, and accelerates the recording head to which each of the plurality of correction values is assigned while performing the test. Record charts,
The ink jet recording method according to claim 1, wherein the ink jet recording method is performed.   4. The ink jet recording method according to claim 1, wherein in the second step, the recording head is scanned in a direction opposite to the first step in the scanning direction. 5. An inkjet recording apparatus that performs recording on the recording medium by scanning a recording head in a scanning direction that intersects a conveying direction for conveying the recording medium,
First test recording means for recording on the recording medium a test chart in which the same pattern is repeated in the scanning direction while scanning the recording head at a constant speed;
The ink ejection timing at the time of recording in the first test recording means is corrected with a correction value, and the test chart is again superimposed on the test chart recorded in the first test recording means while accelerating the recording head. And a second test recording means for performing the recording for each of a plurality of correction values,
After the recording in the second test recording means, the correction values are recorded in the first test recording means at a plurality of locations in the scanning direction of the test chart recorded in the second test recording means in the case of each of the plurality of correction values. Detecting means for detecting the degree of overlap between the recorded pattern and the pattern recorded in the second test recording means;
For each of the plurality of locations, a specifying means for specifying a correction value that maximizes the degree of overlap from the plurality of correction values;
Actual recording means for recording on the recording medium while accelerating the recording head while ejecting ink at the ink ejection timing corrected by each correction value specified by the specifying means;
An ink jet recording apparatus comprising:

Images