JP2009039958A - Recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a correction value more accurately to correct a deviation by reducing the effect of a satellite when in obtaining the correction value for correcting the tilting deviation causing image defects such as unevenness and streaks from a test pattern. <P>SOLUTION: Information regarding the tilt of a recording head is detected on the basis of the test pattern by recording the test pattern with a scanning rate slower than that in normal recording. Then, a correction value for correcting a dot recording position recorded by the recording head is obtained according to the information, so that the correction is carried out. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a recording apparatus that records an image on a recording medium by ejecting ink from a recording head.

  In recent years, an ink jet recording apparatus is required to have high image quality and high speed. The position where ink ejected from the recording head is recorded on the recording medium in order to reduce image adverse effects such as unevenness and streaks due to mounting accuracy of the recording head and assembly errors of the recording device in response to the demand for higher image quality Techniques for correcting deviations (also referred to as recording positions) are becoming essential.

  In general, when correcting a recording position deviation, a test pattern is recorded on a recording medium, and the recording position deviation is corrected based on a correction value determined by information acquired from the test pattern. Further, the displacement of the recording position to be corrected includes the displacement of the recording position of the dots recorded by the forward scanning and the backward scanning of the recording head, the main scanning direction of the recording position of the dots recorded by the different recording heads, or There are misalignments in the sub-scanning direction.

  Patent Document 1 discloses a technique for recording a test pattern at each carriage speed that can be executed by an ink jet recording apparatus and obtaining a correction value for correcting a shift in recording position in each recording mode. . As described above, by acquiring the correction value from the test pattern recorded at the same carriage speed as that during actual recording, it is possible to correct the displacement of the recording position with high accuracy.

  In addition, the deviation of the recording position to be corrected is caused by the recording position of the upstream dot and the downstream dot in the sub-scanning direction due to the fact that the recording head is mounted inclined with respect to the ink jet recording apparatus. There is a deviation in the main scanning direction. This displacement of the recording position is also referred to as an inclination displacement, and a dot row to be recorded along the sub-scanning direction is recorded with an inclination with respect to the main scanning direction due to the inclination displacement.

In Patent Document 2, in an ink jet recording apparatus that performs recording by driving a recording element in a time-sharing manner, the position of recording data to be read from a recording buffer is determined in accordance with the amount of recording position deviation between upstream dots and downstream dots. A technique for correcting and correcting the tilt deviation is disclosed.
JP 2000-37936 A Japanese Patent Application Laid-Open No. 2004-09489

  In recent years when an image quality of an ink jet recording apparatus is more and more demanded, it is required to correct the displacement of the recording position with high accuracy with respect to the above-described inclination deviation to reduce image adverse effects such as unevenness and streaks. In order to correct a recording position shift such as a tilt shift with high accuracy, it is important to obtain a correction value from the test pattern with as little error as possible.

  By the way, the test pattern for acquiring the correction value of the recording position includes a plurality of patches obtained by shifting one image with respect to the other image among the images recorded by the respective recording operations to be corrected. It is created by recording the amount of deviation. For example, the test pattern for correcting the deviation in the recording position of the forward scan and the backward scan is to record a plurality of images recorded by the forward scan by shifting the plurality of images by a predetermined amount and overlapping each other. Created with.

  Then, the optical characteristics of the test pattern are measured by measuring the reflection optical density of each patch with an optical sensor provided in the ink jet recording apparatus, or by selecting the patch with the highest or lowest recording density by the user visually. Obtain information and obtain correction values. Therefore, in order to correct the recording position shift with high accuracy, the shift amount between the two images needs to be accurately reflected in the optical characteristics in each of the plurality of patches in the test pattern.

  However, in an ink jet recording apparatus, when ink is ejected from a recording head, a small ink droplet is generated along with the ejected ink droplet (main droplet), and this small ink droplet lands on a position near the main droplet on the recording medium. It is known to become a satellite. When these small ink droplets are recorded on a portion of the patch where no image exists, the optical characteristics of the patch are changed, so that an error occurs in the correction value for correcting the recording position deviation, and the recording position deviation occurs. Cannot be corrected with high accuracy.

  Therefore, in the present invention, when acquiring a correction value for correcting an inclination shift causing image adverse effects such as unevenness and streaks from a test pattern, the correction value for correcting the shift is reduced by reducing the influence of the satellite. It is an object of the present invention to provide a recording apparatus that can be obtained accurately.

  The present invention has been made in view of the above-described problems, and is a recording apparatus that scans a recording head for recording dots and records an image on a recording medium, and scans the recording head. A control unit that causes the recording head to record a test pattern for acquiring information relating to the inclination of the recording head with respect to the scanning direction, an acquisition unit that acquires the information based on the test pattern, and the acquisition unit. Correction means for correcting the recording position of the dot based on the acquired information, and the scanning speed of the recording head when recording the test pattern is the scanning speed when recording an image on the recording medium It is characterized by being slower than.

  According to the recording apparatus of the present invention, when acquiring a correction value for correcting an inclination shift from a test pattern, it is possible to reduce the influence of satellites and acquire a more accurate correction value.

  In this specification, “recording” not only forms significant information such as characters and figures, but also forms images, patterns, patterns, etc. on a wide variety of recording media, regardless of significance, or It also represents the case where the medium is processed. It does not matter whether it has been made obvious so that humans can perceive it visually.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Further, the term “ink” should be interpreted broadly in the same way as the definition of “recording” described above. When applied to a recording medium, it forms an image, a pattern, a pattern, etc., or processes the recording medium. It represents a liquid that can be subjected to the treatment. Examples of the ink treatment include solidification or insolubilization of the colorant in the ink applied to the recording medium.

  Further, “recording element” (sometimes referred to as “nozzle”) collectively refers to an ejection port, a liquid path communicating with the ejection port, and an element that generates energy used for ink ejection unless otherwise specified. Shall. In this specification, the ejection port array may be referred to as a printing element array.

[Configuration of recording device]
FIG. 1 is an external perspective view showing an ink jet recording apparatus (hereinafter referred to as a recording apparatus) 1 which is a representative embodiment of the present invention.

  As shown in FIG. 1, the recording apparatus 1 transmits a driving force generated by a carriage motor M1 from a transmission mechanism 4 to a carriage 2 on which a recording head 3 that performs recording by ejecting ink according to an inkjet method is mounted. Is reciprocated in the direction of arrow A (reciprocating scanning). Along with this reciprocal movement, for example, a recording medium P such as recording paper is fed through the paper feeding mechanism 5 and conveyed to a recording position, and recording is performed by ejecting ink from the recording head 3 to the recording medium P at the recording position. I do. Further, in order to maintain the state of the recording head 3 satisfactorily, the carriage 2 is moved to the position of the recovery device 10 and the ejection recovery process of the recording head 3 is intermittently performed.

  In addition to mounting the recording head 3, the carriage 2 of the recording apparatus 1 is mounted with an ink cartridge 6 that stores ink to be supplied to the recording head 3. The ink cartridge 6 is detachable from the carriage 2.

  The recording apparatus 1 is capable of color recording. For this purpose, the carriage 2 is equipped with four ink cartridges containing magenta (M), cyan (C), yellow (Y), and black (K) inks, respectively. is doing. These four ink cartridges can be attached and detached independently.

  The carriage 2 and the recording head 3 can achieve and maintain a required electrical connection by properly contacting the joint surfaces of both members. The recording head 3 generates energy according to the recording signal, thereby performing recording by selectively ejecting ink from a plurality of ejection ports. In particular, the recording head 3 of the present embodiment employs an ink jet system that ejects ink using thermal energy. Therefore, the recording head 3 includes an electrothermal converter (recording element) that converts electrical energy into thermal energy, and generates film boiling by applying the thermal energy to the ink. Then, the ink is ejected from the ejection port using the pressure change caused by the growth and contraction of the bubbles due to the generated film boiling. This electrothermal converter is provided corresponding to each discharge port, and by applying a pulse voltage corresponding to the recording signal to the electrothermal converter corresponding to each discharge port, ink is discharged from the corresponding discharge port. Is done.

  The carriage 2 is connected to a part of the driving belt 7 of the transmission mechanism 4 that transmits the driving force of the carriage motor M1, and is guided and supported so as to be slidable in the direction of arrow A along the guide shaft 13. ing. Accordingly, the carriage 2 reciprocates along the guide shaft 13 by forward and reverse rotations of the carriage motor M1. A scale 8 is provided for indicating the absolute position of the carriage 2 along the direction of movement of the carriage 2 (the direction of arrow A). In this embodiment, the scale 8 uses a transparent PET film with black bars printed at a necessary pitch, one of which is fixed to the chassis 9 and the other is supported by a leaf spring (not shown). Yes.

  Further, eccentric cams (not shown) are provided at both ends of the guide shaft 13, and the guide shaft 13 is moved up and down by transmitting the drive to the eccentric cam via the gear train by driving the carriage lifting motor. Can do. As the guide shaft 13 is raised and lowered, the carriage 2 is raised and lowered in the same manner, so that an optimum gap can be formed even for the sheet material P having different thicknesses.

  In recording the test pattern, the displacement of the two images is controlled in each patch by detecting the position of the carriage using the scale 8 and an encoder. Further, the recording apparatus 1 is provided with a platen (not shown) facing the discharge port surface where the discharge port (not shown) of the recording head 3 is formed.

  Then, the recording apparatus 1 is conveyed onto the platen by reciprocating the carriage 2 on which the recording head 3 is mounted by the driving force of the carriage motor M1 and by giving a recording signal to the recording head 3 to eject ink. Recording is performed over the entire width of the recording medium P.

  Further, in FIG. 1, reference numeral 14 denotes a conveyance roller driven by a conveyance motor M2 to convey the recording medium P, and 15 denotes a pinch roller that abuts the recording medium P against the conveyance roller 14 by a spring (not shown). Reference numeral 16 denotes a pinch roller holder that rotatably supports the pinch roller 15, and reference numeral 17 denotes a conveyance roller gear fixed to one end of the conveyance roller 14. Then, the transport roller 14 is driven by the rotation of the transport motor M2 transmitted to the transport roller gear 17 through an intermediate gear (not shown).

  Furthermore, reference numeral 20 denotes a discharge roller for discharging the recording medium P on which an image has been recorded by the recording head 3 to the outside of the recording apparatus, and is driven by the rotation of the transport motor M2. . The discharge roller 20 abuts on a spur roller (not shown) that presses the recording medium P by a spring (not shown). 22 is a spur holder that rotatably supports the spur roller.

  Furthermore, in the recording apparatus 1, the recording head 3 is placed at a desired position outside the reciprocal movement range (outside the recording area) for the recording operation of the carriage 2 on which the recording head 3 is mounted, for example, at a position corresponding to the home position. A recovery device 10 for recovering the ejection failure is provided.

  The recovery device 10 includes a capping mechanism 11 for capping the ejection port surface of the recording head 3 and a wiping mechanism 12 for cleaning the ejection port surface of the recording head 3. The recovery device 10 forcibly discharges ink from the ejection port by a suction pump or the like in the recovery device in conjunction with the capping of the ejection port surface by the capping mechanism 11, thereby increasing the viscosity in the ink flow path of the recording head 3. The ejection recovery process such as removing the ink and bubbles is performed.

  Further, at the time of non-recording operation or the like, by capping the ejection port surface of the recording head 3 by the capping mechanism 11, the recording head 3 can be protected and ink evaporation and drying can be prevented. On the other hand, the wiping mechanism 12 is disposed in the vicinity of the capping mechanism 11 and wipes ink droplets adhering to the ejection port surface of the recording head 3.

  The capping mechanism 11 and the wiping mechanism 12 can keep the ink ejection state of the recording head 3 normal.

[Control configuration of recording apparatus]
FIG. 2 is a block diagram showing a control configuration of the recording apparatus 1 shown in FIG.

  As shown in FIG. 2, the controller 600 includes an MPU 601, a program corresponding to a control sequence to be described later, a required table, a ROM 602 storing other fixed data, and an application specific integrated circuit (ASIC) 603. The ASIC 603 generates control signals for controlling the carriage motor M1, the transport motor M2, and the recording head 3. The controller 600 also includes a RAM 604 provided with an image data development area, a work area for program execution, and the like, a system bus 605, an A / D converter 606, and the like. The system bus 605 connects the MPU 601, the ASIC 603, and the RAM 604 to each other to exchange data, and the A / D converter 606 inputs analog signals from the sensor group described below to perform A / D conversion, A digital signal is supplied to the MPU 601.

  Reference numeral 610 denotes a computer (or a reader for image reading, a digital camera, or the like) serving as a supply source of image data, and is collectively referred to as a host device. Between the host apparatus 610 and the recording apparatus 1, image data, commands, status signals, and the like are transmitted / received via an interface (I / F) 611.

  Further, reference numeral 620 denotes a switch group, which includes a power switch 621, a print switch 622 for instructing the start of printing, and a recovery switch 623 for receiving a command input by the user. The recovery switch 623 is a switch for instructing start of processing (recovery processing) for maintaining the ink ejection performance of the recording head 3 in a good state. 630 includes a position sensor 631 such as a photocoupler for detecting the home position h, a temperature sensor 632 provided at an appropriate location of the recording apparatus for detecting the environmental temperature, and the like, and detects the apparatus state. It is a sensor group for doing.

  Further, 640 is a carriage motor driver that drives a carriage motor M1 for reciprocating scanning of the carriage 2 in the direction of arrow A, and 642 is a conveyance motor driver that drives a conveyance motor M2 for conveying the recording medium P.

  With the above configuration, the recording apparatus 1 analyzes the command of the recording data transferred via the interface 611 and develops the recording data used for recording in the RAM 602. The print data development area (development buffer) is a two-dimensional rectangular area, and its horizontal size corresponds to the number of pixels corresponding to the printable area in the carriage movement direction (main scanning direction). Further, the vertical size of the development buffer is configured to correspond to the number of pixels in the conveyance direction (sub-scanning direction) of the recording medium recorded by one recording scan of the recording head, and this is secured in the RAM 602.

  In the recording scan, the storage area (print buffer) on the RAM 602 referred to for transferring the recording data to the recording head 3 is also a two-dimensional rectangular area, and its horizontal size is set to pixels corresponding to the recordable area in the main scanning direction. Correspond to the number. Further, the vertical size of the print buffer is configured to correspond to the number of pixels in the sub-scanning direction recorded by one recording scan of the recording head, and this is secured on the storage area of the RAM 602.

  FIG. 3 schematically shows the storage position of the recording data on the print buffer. In the drawing, b0 at address 000 holds print data of a print element with nozzle number 0 of a printhead according to the present embodiment to be described later. The recording data of the next column with nozzle number 0 is held in b1 of the same address 000, and similarly, the data to be recorded in the next column is sequentially held in the horizontal direction of address 000. Yes. Similarly, the recording data of the nozzle number 127 is held at the address 0FE in the same manner as the nozzle number 0.

[Configuration of recording head]
FIG. 4A shows the arrangement of the discharge ports 150 on the discharge port surface 140 of the recording head 3. Each of the ejection port arrays 141, 142, 143, and 144 in which a plurality of ejection ports 150 are arranged has 128 ejection ports 150 arranged therein, and each ejects ink droplets of black, cyan, magenta, and yellow.

  Note that the recording head 3 is not limited to the above-described configuration, and for example, the ejection port arrays 141, 142, 143, and 144 for each color may include two rows in which the ejection ports 150 are alternately arranged in the sub-scanning direction. . Further, the black discharge port array 141 may be longer than the other color discharge port arrays 142, 143, and 144.

  In the following description, an example in which the tilt deviation correction is performed on one ink ejection port array (here, the black ink ejection port array 141) will be described. However, the other ejection port arrays are similarly tilted. Correction can be performed.

  FIG. 4B is a diagram illustrating a configuration of the recording head 3 having the ejection port array 141 including the 128 ejection ports 150. In the figure, the upper side in the figure corresponds to the downstream side in the sub-scanning direction, and nozzle numbers 0 to 127 are virtually assigned to the respective discharge ports 13 of the discharge port array 141 from the downstream side toward the upstream side. Further, 16 discharge ports 13 in the discharge port array 141 are divided into 16 groups from the smallest nozzle number into groups 0 to 7, and blocks 0 to 15 are sequentially arranged from the recording element corresponding to the discharge port having the smallest nozzle number in each group. assign. In this way, an image is recorded by driving the recording elements to which the block numbers are assigned in the order of blocks 0 to 15 in a time-sharing manner.

[Recording of test pattern]
First, an example of the procedure for correcting the tilt deviation will be described with reference to FIG. When this procedure is activated, a recording medium is first set (step S100), and a test pattern for obtaining a correction value is recorded on the recording medium (step S101). Next, the reading operation of each patch of the test pattern recorded on the recording medium is performed by the optical sensor to acquire density information (step S102). Then, based on this density information, information on the tilt deviation is detected (step S103), and a correction value is acquired from this information and stored (updated) in the correction value storage memory 217 (step S104).

  Next, an outline of processing from the test pattern recording in steps S101 to S103 to the detection of information on the tilt deviation in this embodiment will be described.

  FIG. 6 shows an example of the test pattern recorded on the recording medium in step S101. Seven patches 401 to 407 are recorded in the test pattern of this embodiment. FIG. 7 is a diagram illustrating a procedure for recording each of the patches 401 to 407 when recording a test pattern. First, in the first scan of the recording head, two images 411 of 3 dots in the sub-scanning direction × 4 dots in the main scanning direction are recorded at intervals of 4 dots in the main scanning direction by three upstream discharge ports. (FIG. (A)). Then, after the recording medium is conveyed, an image 412 of 3 dots in the sub-scanning direction × 4 dots in the main scanning direction is recorded in the interval between the images 411 by the three downstream discharge ports in the second scan (see FIG. B)). In addition, if the first and second scans are recorded by scanning in different directions, an error is likely to occur in the dot recording position due to the difference in the scanning direction, so the first and second scans are performed by scanning in the same direction. Is desirable. Here, the recording head performs patch recording when scanning from the left side to the right side of the drawing.

  Of the seven patches, the reference patch 404 records the image 412 so as to just fill the interval between the images 411 in the second scan. On the other hand, the patches 405, 406, and 407 record the image 412 while delaying the drive timing of the downstream ejection port in the second scan and varying the drive timing for each. Here, the image 412 is recorded so as to be shifted from the interval between the images 411 by 1/2 pixel, 1 pixel, and 3/2 pixels in the right direction of the main scanning direction. On the other hand, the patches 403, 402, and 401 advance the drive timing of the downstream discharge port 13 in the second scan, and record the image 412 at different drive timings. Here, the image 412 is recorded so as to be shifted from the interval of the image 411 by 1/2 pixel, 1 pixel, and 3/2 pixel in the left direction in the main scanning direction.

  Next, an outline of a procedure until detection of information related to an inclination shift is described based on the test pattern recorded as described above.

  First, FIGS. 8A and 8B show a reference patch 404 when there is a tilt shift, and the arrangement of dots in this patch. As shown in FIG. 5A, when there is a tilt shift, a black stripe 409 and a white stripe 410 are generated in the patch 404. Also, as the arrangement of dots in this patch, as shown in FIG. 5B, the dot overlapped portion (overlapping portion) 413 corresponding to the black stripe 409 and the white stripe 410 and the portion where no dot exists (blank portion). 414 occurs.

  In FIG. 9, in the tilt deviation caused by the recording head being mounted with an inclination with respect to the recording apparatus, the dots 408 recorded by the upstream discharge port and the dots 415 recorded by the downstream discharge port are shown. Indicates placement. As shown in FIG. 9, when a tilt shift occurs, a print position shift (this shift amount is L) occurs between the upstream dot 408 and the downstream dot 415.

  Accordingly, since the patch 404 records the image 412 so as to just fill the interval between the images 411 in the second scan, the main scanning direction of the upstream dot and the downstream dot as shown in FIG. Due to the deviation, dot overlap and blank portions are generated. The patch 404 is a patch having black lines and white lines.

  Next, an outline of a method for detecting information on tilt deviation from a test pattern will be described. Here, it is assumed that the patch 402 of “−2” among the seven patches is detected as the most uniform patch without black stripes and white stripes.

  In the patch 402, the drive timing of the downstream ejection port is advanced in the second scan, and the image 412 is recorded so that one pixel is shifted to the left side in the drawing from the interval between the images 411. Therefore, if there is no tilt deviation, black stripes should appear in the overlapping part of the images 411 and 412 and white stripes should appear in the part where the images 411 and 412 are separated.

  However, since the tilt shift occurs, there is a shift in the main scanning direction (shift amount L) between the upstream dot and the downstream dot. Therefore, the shift amount L corresponds to the interval between the images 411. The patch 402 becomes a uniform patch by offsetting the shift amount of one pixel of the image 412. FIG. 10 shows the patch 402 of “−2” and the dot arrangement of this patch.

  From the above, the shift amount L in the main scanning direction between the upstream dot and the downstream dot is one pixel, and the downstream dot is shifted to the right in the main scanning direction with respect to the upstream dot. It is detected that the inclination is inclined in the clockwise direction. In this way, by selecting a uniform patch from the patches recorded by delaying or driving the discharge port on the downstream side in advance, the amount of displacement and the amount of displacement in the main scanning direction as information on the inclination displacement are selected. The direction can be detected. In this embodiment, by measuring the recording density of each of a plurality of patches using an optical sensor, the patch with the highest recording density can be detected as the most uniform patch without black and white stripes. .

  In the above description, the information regarding the tilt deviation is detected by simply selecting the most uniform patch by the optical sensor. However, the present invention is not limited to this configuration, and various configurations can be adopted as a configuration for detecting information related to tilt deviation. For example, the patch having the highest recording density and the patch having the second highest recording density are selected, and the recording density difference between the two patches is calculated. If the calculated difference is equal to or larger than a predetermined value, the amount of deviation in the main scanning direction of the patch having the highest reflection optical density is detected as information on the inclination deviation, and if it is equal to or smaller than the predetermined value, the deviation in the main scanning direction between the two patches You may make it detect the average value of quantity as information regarding inclination shift. Alternatively, an approximate curve may be obtained by polynomial approximation from the density data of the reflection optical density of each patch, and the shift amount in the main scanning direction may be detected as information related to the tilt shift from the highest value of the approximate curve.

  A method for acquiring a correction value based on the amount of deviation and the direction of deviation detected from the test pattern will be described later. In addition, as described above, since the information about the inclination deviation is acquired by using the optical characteristics of each patch, if the density change occurs in the patch due to the satellite, the information about the inclination deviation and the correction value are affected. It is clear to give.

  With the above configuration, it is possible to detect information about the tilt deviation from the test pattern. In the present embodiment, however, the configuration is such that the carriage scanning speed in the test pattern recording in S102 is slower than that in actual recording. Adopted. Hereinafter, the reason why such a configuration is adopted in the present embodiment will be described.

  FIG. 11 is a diagram illustrating the velocity components in the vertical direction and the horizontal direction for the main droplet 501 and the small ink droplet 502. In the drawing, the vertical velocity component Vm of the main droplet 501 is larger than the vertical velocity component Vs of the small ink droplet. Further, since the main droplets and small ink droplets are ejected while scanning the carriage, the horizontal velocity components of the main droplets 501 and the small ink droplets 502 have a velocity component equal to the scanning velocity of the carriage. That is, the horizontal velocity component Vmh of the main droplet 501 and the horizontal velocity component Vsh of the small ink droplet are equal to the carriage scanning velocity Vc.

  Here, when the distance between the recording head 3 and the recording medium P is X, and the interval between the recording position of the main droplet and the recording position of the small ink droplet is D, the interval D is D = Vc × (X / Vm− X / Vs). That is, it can be seen that the interval D between the recording position of the main droplet 501 and the recording position of the small ink droplet 502 is proportional to the scanning speed Vc of the carriage, and the interval D increases as the scanning speed Vc of the carriage increases.

  FIG. 12 is a diagram showing a dot arrangement when the reference patch 404 is recorded in the above-described tilt deviation correction test pattern at different carriage scanning speeds. In the recording apparatus of the present embodiment, the carriage scanning speed when recording is actually performed is 25 inches / s. FIG. 5A shows a patch based on the same carriage scanning speed (25 inches / s) as during actual recording. This shows the dot arrangement when recording. This figure shows a case where the main droplet 501 and the small ink droplet 502 have landed at positions separated from each other on the recording medium.

  FIG. 5B shows the dot arrangement when a patch is recorded at a carriage scanning speed (12.5 inch / s) slower than the actual recording time. In this figure, the interval between the recording positions of the main droplet and the small ink droplet is closer than in FIG. 12A, and the dot (satellite) of the small ink droplet 502 is formed in the dot of the main droplet 501. Show.

  In FIG. 12A, since the satellite is recorded outside the dod of the main droplet 501 and just in the blank portion of the patch, the reflected optical density of this patch is larger than the reflected optical density of the patch when there is no satellite. become. On the other hand, in FIG. 12B, since the satellite is recorded so as to overlap the inside of the main droplet 501, the reflected optical density of this patch is almost the same as when there is no satellite.

  As described above, since the interval between the main droplet and the satellite becomes smaller as the scanning speed of the carriage becomes slower, in FIG. 12B in which the scanning speed is made slower than the actual recording time, the satellite is inside the dod of the main droplet 501. The effect of changes in the optical characteristics of the patch can be reduced. Therefore, by recording a test pattern at a slower scanning speed than during actual recording, it is possible to detect the information about the tilt deviation by reducing the influence of the satellite, and it is possible to obtain a more accurate correction value. Become.

  In the above description, FIG. 12B in which the scanning speed of the carriage is slower than in actual recording shows the case where the entire satellite is formed in the main droplet dots. However, the scanning speed is faster than in this case, and even when a part of the satellite is formed in the main droplet dot, the effect of patch density change due to the satellite can be reduced, so a more accurate correction value is obtained. It becomes possible to do. Even if the satellite does not overlap with the main droplet dot at all, a more accurate correction value can be obtained. This is because by slowing the scanning speed of the carriage compared to the actual recording time, the scanning state such as vibration reduction during the scanning of the carriage is stabilized and the recording position accuracy of the main droplet can be improved.

  It has been found that a more accurate correction value can be obtained by correcting a deviation in printing position between forward scanning and backward scanning using a test pattern recorded at the same carriage scanning speed as in actual recording. This is because if the scanning speed at the time of actual recording is the same as that at the time of recording the test pattern, the test pattern can be displayed in a state in which various factors such as vibration during carriage scanning shift the dot recording position. This is because recording is performed and correction is performed based on this pattern. On the other hand, the tilt deviation is a deviation of the recording position due to the mounting accuracy and mounting accuracy of the recording head, and is hardly affected by the recording conditions (for example, the scanning speed of the carriage) when recording the test pattern. From the above, it is possible to obtain a more accurate correction value by reducing the influence of the satellite by recording the test pattern for correcting the tilt deviation at a lower scanning speed than the actual recording. It becomes possible.

  In addition, when recording a test pattern for tilt deviation correction, the distance between the recording position of the main droplet and the small ink droplet can be reduced by reducing the distance between the recording head and the recording medium, thereby reducing the influence of the satellite. it can. This is because the interval D between the recording positions of the main droplet and the small ink droplet is expressed by D = Vc × (X / Vm−X / Vs), and this interval D is proportional to the distance X between the recording head and the recording medium. Because. The distance between the recording head and the recording medium can be set by moving the guide shaft 52 up and down by transmitting the drive to the eccentricity via the gear train by driving the carriage lifting motor as described above. .

  In the present embodiment, in addition to the tilt shift correction, in order to correct other recording position shifts, when each test pattern is recorded on the same recording medium, only the pattern for tilt shift correction is actually used. Recording is performed at a slower scanning speed than during recording. For other test patterns for correcting misalignment of the recording position, the scanning speeds at the time of actual recording and test pattern recording are the same. As a result, it is possible to detect information related to tilt deviation and information other than information related to tilt deviation with high accuracy. For example, the recording position shift other than the tilt shift includes, for example, a shift in the recording positions of the odd and even rows of the same color nozzle row in a staggered arrangement, and a shift in the recording positions of the large nozzle row and the small nozzle row having different ejection amounts. There are deviations in the recording positions of forward scanning and backward scanning.

  In FIG. 12, the patch is recorded by scanning in the forward direction. However, when the recording is performed by scanning in the backward direction, only the direction in which the satellite lands on the main droplet is reversed, and the same effect is obtained. It is possible.

  Furthermore, in the above description, the case where the reflection optical density of each patch is measured using an optical sensor has been described, but even when the information on the tilt deviation is detected by the user's visual observation without using the optical sensor, This embodiment is useful. That is, if a test pattern for correcting tilt deviation is recorded at the same scanning speed as that during actual recording, satellites are generated in the blank portion of the patch, and the white stripe corresponding to this blank portion is difficult to be recognized. The detection accuracy may be reduced. On the other hand, if the test pattern is recorded at a slower scanning speed than the actual recording, the satellite is recorded so as to overlap the inside of the main droplet dod, so that the density change in the blank portion is suppressed, It becomes easy to recognize as white stripes. In this way, even when detecting information on the tilt deviation by visual observation by the user, the influence of the satellite can be reduced by recording the test pattern at a slower scanning speed than the actual recording, and more It is possible to acquire an accurate correction value.

[Tilt deviation correction control configuration]
Next, a step of acquiring a correction value based on information on the inclination deviation detected from the test pattern and storing (updating) it in the correction value storage memory 217 (step S104 in FIG. 5), and using this correction value, the inclination deviation is obtained. A process of recording an image after performing the above correction will be described.

  First, an example of a hardware configuration for executing tilt deviation correction is shown below.

  FIG. 13 is an internal block diagram of the ASIC 603. A configuration of time-division driving in which recording elements at discrete positions are sequentially driven will be described with reference to FIG. The data rearrangement circuit 212 is a circuit for rearranging the recording data. This circuit collects the recording data associated with 127 recording elements and held in the print buffer into 7-bit recording data for each block to be recorded substantially simultaneously, and writes the data to the recording memory 213.

  FIG. 14 is a diagram schematically showing the configuration of the recording memory 213. In the figure, recorded data of blocks 0 to 15 are held in order from addresses 0 to F. Block 0 holds b0 data from group 0 to group 7, and similarly block 1 holds b1 data from group 0 to group 7. In addition, the recording memory 213 employs a 3-bank configuration in which 16 blocks of data are 1 bank so that the writing operation and the reading operation are exclusive operations.

  In the recording memory 213, when Bank0 is used for writing, reading is performed from Bank1 and Bank2. When Bank 1 is used for writing, reading is performed from Bank 2 and Bank 0. When Bank 2 is used for writing, reading is performed from Bank 0 and Bank 1. The reason for using 2Bnak at the time of reading will be described later.

  Returning to FIG. 13, the transfer number counter 216 is a counter circuit that counts the number of recording timing signals, and is incremented for each recording timing signal. The transfer counter counts from 0 to 15 and returns to 0. Further, the transfer number counter 216 counts the Bank value of the recording memory 213. When the transfer number counter is counted 16 times, the Bank value is incremented by +1.

  In the block drive order data memory 214, the order of driving the recording elements of block numbers 0 to 15 divided into 16 is recorded at addresses 0 to 15. For example, when driving sequentially from block number 0, block numbers are stored in the order of 0 → 1 → 2 →.

  The recording data transfer circuit 219 increments the transfer count counter 216 with a recording timing signal generated based on, for example, an optical linear encoder as a trigger. The data selection circuit 215 reads from the recording memory 213 recording data corresponding to the value in the block drive order data memory 214 and the Bank value counted by the transfer number counter 216 from the recording timing signal. Then, the recording data is corrected in accordance with the correction value held in the correction value memory 217, and the recording data subjected to the correction is synchronized with the data transfer CLK signal (HD_CLK) generated by the data transfer CLK generator 218. Then, the data is transferred to the recording head 3.

  FIG. 15 shows an example of block drive order data written from address 0 to address 15 in the block drive order data memory 214. In the figure, block data indicating block 0 and block 1 are stored in address 0 and address 1 of the block drive order data memory 214, respectively. Similarly, block data indicating blocks 2 to 15 are sequentially stored from address 2 to address 15.

  The data selection circuit 215 reads block data 0001 (a numerical value indicating the block 1) as a block enable signal from the address 0 of the block drive order data memory 214 using the recording timing signal as a trigger. Then, the recording data corresponding to the block data 0001 is read from the recording memory 213, and the recording data is transferred to the recording head 3.

  Similarly, block data 1011 (a numerical value indicating block 1) is read as a block enable signal from address 1 of the block drive order data memory 214 at the next recording timing signal. Then, the recording data corresponding to the block data 0011 is read from the recording memory 213 and transferred to the recording head 3.

  Similarly, block data is sequentially read from address 2 to address 15 of the block drive order data memory 214 using the next recording timing signal 212 as a trigger. Then, the recording data corresponding to each block data is read from the recording memory 213 and transferred to the recording head 3.

  In this way, the data selection circuit 215 reads the block data set at addresses 0 to 15 in the block drive order data memory 214. Then, recording data corresponding to each block data is read from the recording memory 213 and transferred to the recording head 3 to perform recording for one column.

  FIG. 16 is a drive circuit diagram for driving the recording head 3. The recording head 3 divides and drives 128 recording elements into 16 blocks, and drives the 16 recording elements assigned to the same block. . The recording data signal 313 is sent by serial transfer to the recording head 3 by the HD_CLK signal 314. The recording data signal 313 is received by the 16-bit shift register 301 and then latched at the rising edge of the latch signal 312 by the 16-bit latch 302. The designation of the block is indicated by four block enable signals 310, and the recording element of the designated block developed by the decoder 303 is selected.

  Only the recording element designated by both the block enable signal 310 and the recording data signal 313 is driven by the heater driving pulse signal 311 that has passed through the AND gate 305, and ink droplets are ejected to perform image recording.

  FIG. 17 shows the drive timing of the block enable signal 310. In the divided block selection circuit, the block enable signal 310 can be generated based on the block drive order data stored in the block drive order data memory 214. Therefore, as shown by the block enable signal 310 in the figure, in the divided block selection circuit, the block drive order generated by the block drive order data memory 214 sequentially designates 16 blocks from the block 0 to the block 15. Is set to Therefore, in the forward scanning recording in the unidirectional recording and the bidirectional recording, the block enable signal 310 indicating the driving timing is in the driving order of blocks 0 → 1 → 2 →. It will be driven. The block enable signal 310 is generated so that each block is designated at equal intervals in one cycle.

[Outline of tilt deviation correction]
Next, assuming that the patch 402 of “−2” in FIG. 6 is detected as the most uniform patch, an outline of a method of correcting the tilt deviation at that time will be described.

  In step S103, information related to tilt deviation is detected based on density information measured from each patch. The correction value for correcting the tilt shift according to the shift amount (for one pixel) of the dot arrangement with respect to the main scanning direction detected from the patch 402 in FIG. 6 and the shift direction (right direction in the main scanning direction). Is set in the correction value storage memory 217. The correction value for correcting the tilt deviation is set as a value indicating the number of recording elements for changing the reading position of the recording data for each of the groups 0 to 7. This correction value is set in the form of a table in the correction value storage memory 217 as shown in FIG. 18. In the case of a tilt deviation of “−2”, 0 for the reference group 0 and 0 for the group 1 2 is set. Similarly, the correction value is set to 4 for group 2, 6 for group 3, 8, 8 for group 4, 10 for group 5, 12 for group 6, and 14 for group 7.

  As a method for determining a correction value for each group, there is a method of previously holding a plurality of tables corresponding to information on tilt deviation. Alternatively, the correction value of the reference group 0 may be set to 0, the correction value in the group 7 may be determined from the information regarding the tilt deviation, and the correction value of each group located in the middle may be determined by simple calculation.

  Further, here, the reference for which the correction value is 0 is the group 0, but a group other than the reference group 0 may be used. For example, if group 4 is used as a reference, -8 is set as group 0, -6 is set as group 1, -4 is set as group 2, and -2 is set as group 3. Further, 2 is set as the correction value for group 5, 4 is set for group 6, and 6 is set for group 7.

  Then, the read position of the record data is changed based on the correction information set in the correction value storage memory 217, and an image is recorded based on the record data whose read position is changed.

  FIG. 19 is a diagram showing nozzle numbers, blocks, print data, and dot arrangements assigned to print elements in groups 0 to 7. In the figure, the recording data indicates the timing for reading the recording data in the first to third columns assigned to each recording element, and the dot arrangement is recorded when recording is performed at this timing when there is no tilt deviation. The dot arrangement to be performed is schematically shown.

  In the same figure, as can be seen from the column of recording data, the reading of the recording data is changed for the number of recording elements designated by the correction value from the recording element of block number 0 in each group. For example, correction value 2 is set for group 1, and the read position of the recording data from block 0 to block 1 is changed from the original timing of the first to third columns to the timing of the second to fourth columns. Yes. Similarly, the read position of the recording data up to block 3 in group 2, up to block 5 in group 3, and up to block 7 in group 4 is offset by one column and changed to the timing of the second to fourth columns. Similarly, the reading position of the recording data up to block 9 in group 5, up to block 11 in group 6, and up to block 13 in group 7 is offset by one column and changed to the timing of the second to fourth columns.

  FIG. 20 shows the arrangement of dots recorded by the above-described inclination deviation correction, and the white dots in the figure show the positions of dots recorded when inclination deviation correction is not performed. It is. When the tilt shift occurs, the recorded dot row is tilted with respect to the main scanning direction, and therefore, dots are recorded that deviate from the column that should be originally arranged. In the case of an inclination shift of “−2”, the number of dots that deviate from the original column is two dots from group 0 to block 1 in group 1, and four dots from group 0 to block 3 in group 2. It increases according to the group number. In this way, since the number of dots printed out of the originally arranged column varies from one end to the other end of the recording head in each group, the dot to be offset is determined for each group according to the number of dots. There is a need to.

  Furthermore, even in the same group, the number of dots printed out of the original column changes depending on the amount of inclination deviation. Therefore, for the same group, it is necessary to set a larger correction value as the deviation amount is larger, and to increase the number of recording elements that offset the read position of the recording data.

  In view of this, the tilt deviation correction of the present embodiment is configured such that the read position of the print data assigned to the print elements can be changed in the main scanning direction for each print element. In other words, in the tilt shift correction of the present embodiment, it is possible to determine a dot for changing the print data reading position in accordance with the tilt shift amount.

  For example, in the case of “−2”, the group 2 has four dots from blocks 0 to 3 recorded out of the original column. However, by setting the correction value 2 to the group 2, it is possible to offset the read position of the print data assigned to the print elements of the blocks 0 to 3 by one column. As described above, since the reading position of the recording data allocated to the recording element can be changed for each recording element, the dot position deviating from the original column is offset in the main scanning direction for each group according to the amount of deviation of the inclination deviation. It can be corrected.

  As described above, the number of dots that are recorded out of the original column due to an inclination shift differs depending on the group. However, in the tilt shift correction according to the present embodiment, a correction value is set for each group, and by changing the read position of the print data corresponding to the number of print elements corresponding to the correction value, the image adverse effect due to the tilt shift is reduced. It is reduced.

  In the above description, a case has been shown in which all the dots recorded outside the column that should be originally arranged can be corrected. However, depending on the amount of deviation, there are cases in which it is not possible to correct all the dots recorded outside the original column. In such a case, it is only necessary to set a correction value that maximizes the number of dots that can be corrected, and to perform tilt deviation correction.

  Below, an example of the control procedure which performs inclination shift correction in this embodiment is shown. FIG. 21 is a timing chart showing the timing for reading the recording data from the recording memory 213. In the figure, the cumulative number is a time-axis index representing the number of recording timing signals from the reference. Further, as described above, the transfer number counter value is a value incremented for each recording timing signal by the transfer number counter 216, and returns to 0 when counted from 0 to 15. Furthermore, the number described in the square frame below the trigger signal indicates the block number to be transferred at that timing.

  Here, the square frame painted in light gray indicates the recording data to be recorded in the original first column. The square frame without filling is the recording data that should be recorded in the original second column, and the dark gray is the recording data that should be recorded in the original third column.

  In the case of “−2” tilt deviation, the correction value storage memory 217 stores 0 in group 0, 2 in group 1, 4 in group 2, 6 in group 3, 8 in group 4, 10 in group 5, and group 6 12 and 14 in group 7 are set as correction values for each group. Referring to FIG. 21, in the group 0 in which the correction value 0 is set, the record data of the first column is recorded between the cumulative number 0 to 15. Further, in the group 1 in which the correction value 2 is set, the recording timing is shifted by the cumulative number 2 times, and the recording data of the first column is recorded between the cumulative number 2 and 17.

  Next, a procedure for generating recording data will be described. First, the data selection circuit 215 reads the data of Bank 0 and Bank 2 from the recording memory 213 at the timing of the cumulative number of times 0 to 15. In addition, at the timing from the total number of times 16 to 31, data of Bank1 and Bank0 are read. In addition, at the timing from the total number of times 32 to 47, data of Bank2 and Bank1 are read. In addition, at the timing from the cumulative number 48 to 63, the data of Bank1 and Bank0 are read. Thus, the data selection circuit 215 reads data from two of Banks 0, 1, and 2 according to the cumulative number of times.

  As shown in FIG. 21, for example, when the cumulative number of times is 0, the data of Bank 0 and Bank 2 are read out, so that the recording data of address 0 (Bank 0) and the recording data of address 20 (Bank 2) are read. I do. Similarly, since the data of Bank 1 and Bank 0 are read out at the timing of the cumulative number 22, the address 16 (Bank 1), which is the recording data of the block 6, and the recording data (Bank 0) of the address 6 are read out.

  FIG. 22 is a schematic diagram showing the generation of recording data (transfer data) transferred to the recording head 3 at the timing of the cumulative number 22. In the figure, the recording data b0 to be transferred is recording element data of a block corresponding to the cumulative number of times of group 0. Here, since the number of blocks to be transferred is 6, this corresponds to the recording data of the block 6 of the group 0, that is, the data recorded from the seg 6 of the recording head 3. Further, b7 is data for the recording element in the block 6 of the group 7, that is, data recorded from the seg 118 of the recording head 3.

  FIG. 23 is a flowchart for selecting recording data in the data selection circuit 215. The transfer data generation procedure at the timing of the cumulative number 22 will be described with reference to this flowchart.

  When the recording timing signal is input (S301), the recording data is read from the address 16 of Bank 1 of the third recording memory 213, and the data is temporarily held by the internal first latch means (not shown). (S302). Subsequently, similarly, the recording data is read from the address 6 of Bank 0, and the data is temporarily held in the second latch means (not shown) (S303).

  Next, the correction value of group 0 is compared with the value of the transfer number counter (S304). Here, since the correction value of group 0 is 0 and the condition of 0 ≦ 6 is satisfied as compared with the transfer count 6, the data of b0 at address 16 is held in the third latch means (S305).

  Then, the same processing is executed from group 0 to group 7. For example, in group 4, since the correction value is 8, the number of transfers is 6, and the condition of S304 is not satisfied, the data of b4 at address 6 is held in the third latch means (S306). By performing processing from group 0 to group 7 as described above, transfer data b0 to b7 are completed.

  Returning to FIG. 22, the transfer data b0 to b3 from the group 0 to the group 3 is the recording data that should be originally recorded with the cumulative number 22, that is, the recording data of the second column. On the other hand, the transfer data b4 to b7 of the groups 4 to 7 are the first column recording data to be recorded 16 timings before. The generated recording data is transmitted to the recording head 3 by the recording data transfer circuit 219 together with the HCL generated by the data transfer CLK generator 218.

  FIG. 24 is a schematic diagram showing generation of recording data (transfer data) transferred to the recording head 3 at the timing of the cumulative number 34, which is another timing. Note that at the timing of the cumulative number 34, the recording data at the address 22 and the address 12, which are the recording data of the block 2, are read from the third recording memory 213.

  According to the recording data selection flow chart of FIG. 23, when the correction values for groups 0 to 7 and the transfer count counter value are compared, it is the groups 0 and 1 that satisfy the relationship between the correction value of S304 and the transfer count. . Therefore, the recording data at the address 21 is selected as the transfer data b0 and b1 for the group 0 and the group 1, and the recording data at the address 11 is selected as the transfer data for the group 2 to the group 7.

  As described above, according to the printing apparatus of the present embodiment, the read position of print data to be assigned to print elements can be changed in the main scanning direction for each print element, and image adverse effects due to tilt deviation can be reduced. It becomes.

1 is an external perspective view of an ink jet recording apparatus. FIG. 3 is a block diagram illustrating a control configuration of the ink jet recording apparatus. The figure which shows the storage position of the recording data on a print buffer. FIG. 3 is an explanatory diagram of an ink discharge port surface of a recording head. The flowchart of the process for correct | amending inclination deviation. The figure which shows the test pattern recorded on the recording medium. The figure explaining the recording procedure of a test pattern. The figure which shows a reference | standard patch and its dot arrangement | positioning. The figure explaining the shift | offset | difference of an upstream dot and a downstream dot. The figure which shows a uniform patch and its dot arrangement. The figure explaining the velocity component of a main droplet and a small ink droplet. The figure which shows the relationship between the scanning speed of a carriage, and the position where a satellite generate | occur | produces. The internal block diagram of ASIC. The figure which shows the structure of a recording memory. The figure which shows block drive order data. FIG. 3 is a drive circuit diagram of a recording head. The drive timing diagram of a block enable signal. The figure which shows the correction value set to the correction value storage memory. The figure which shows the nozzle number, block, recording data, and dot arrangement | positioning in inclination shift correction. The figure which shows arrangement | positioning of the dot by inclination shift correction. FIG. 4 is a timing chart for reading recorded data. The figure explaining the production | generation of the data for transfer in the timing of the total number 22 times. FIG. 5 is a flowchart for selecting recorded data. The figure explaining the production | generation of the data for transfer in the timing of the total number of times 34. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 3 Recording head 150 Discharge port 213 Recording memory 501 Main droplet 502 Small ink droplet

Claims (5)

A recording apparatus for recording an image on a recording medium by scanning a recording head for recording dots,
Control means for causing the recording head to record a test pattern for scanning the recording head and acquiring information relating to the inclination of the recording head with respect to the scanning direction;
Obtaining means for obtaining the information based on the test pattern;
Correction means for correcting the recording position of the dots based on the information acquired by the acquisition means;
A recording apparatus, wherein a scanning speed of the recording head when recording the test pattern is slower than a scanning speed when recording an image on the recording medium. Means for setting a distance between the recording head and the recording medium;
The recording apparatus according to claim 1, wherein the distance when the test pattern is recorded is smaller than the distance when an image is recorded on the recording medium. The control means can also record a test pattern for acquiring information other than information related to the tilt,
The scanning speed when recording a test pattern for acquiring information related to the tilt is slower than the scanning speed when recording a test pattern for acquiring information other than information related to the tilt. Item 3. The recording apparatus according to Item 1 or 2.   4. The information other than the information related to the tilt is information related to at least one of the recording element arrays of the recording head or information related to forward scanning and backward scanning of the recording head. Recording device. While the recording head having a recording element array in which a plurality of recording elements are arranged is scanned in the main scanning direction with respect to the recording medium, the recording elements at discrete positions in the recording element array are used as blocks, and time-division driving is performed for each block. A recording device for recording an image by
Storage means for storing recorded data;
Control means for causing the recording head to record a test pattern for scanning the recording head to acquire information relating to the inclination of the recording element array with respect to the main scanning direction;
Means for obtaining the information based on the test pattern;
Reading means capable of reading recording data having different storage positions in the main scanning direction in the storage means in order to drive recording elements belonging to the block substantially simultaneously based on the acquired information;
A recording apparatus, wherein a scanning speed of the recording head when recording the test pattern is slower than a scanning speed when recording an image on the recording medium.

Images