JP2007268946A - Recording position dislocation correcting method for inkjet recording head and inkjet recording device with the function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording device which can correct the inclination or dislocation of the recording head by detecting the inclination or dislocation of the recording head by using a pattern prepared by a simpler control method and varying recording timing in accordance with the result of the detection. <P>SOLUTION: A nozzle to be used for detection is changed according to an object of detection (inclination, horizontal dislocation) by using part of a row of nozzles, and a detection pattern which can be recorded by simple control rather than a complex control is recorded. The reflection density of the detection pattern by sensors is read to correct the density. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording correction method for an ink jet recording apparatus, and more particularly to a method for automatically adjusting a recording position shift caused by a tilt of a recording head used for ink jet recording.

  2. Description of the Related Art In recent years, an ink jet recording apparatus has been known as a method for discharging a liquid such as ink that is generally used. Today's inkjet recording apparatus includes a plurality of recording heads for each color, and is configured to realize color recording by performing recording control on the recording head for each color. When a plurality of recording heads are provided as described above, the recording head tilts due to a shift in the mounting position of the recording head or a tilt of the carriage on which the recording head is mounted, so that the landing position of the ink droplets shifts and the recording quality decreases. There are things to do.

  In order to prevent such deterioration in recording quality, a ruled line is recorded by each recording head, the user selects the most appropriate recording condition from the recording result, and the condition is set by the recording apparatus or the host computer. A method of performing alignment by doing so is known. However, such a conventional method involves a complicated operation of recording, and a user or the like selects a recording condition from the recording result and sets the condition. Therefore, for the purpose of eliminating this troublesome work, a pattern showing optical characteristics corresponding to the amount of deviation between the recording heads is recorded, and the optical characteristics of the pattern are acquired and recorded using an optical characteristic measuring means. A recording apparatus having means for aligning has been proposed (Patent Document 1).

  As a method of recording on a recording medium in an inkjet recording apparatus, a carriage mounted with a recording head is scanned on the recording medium in the main scanning direction, and recording is performed while feeding the recording medium in a sub-scanning direction orthogonal to the main scanning direction. There is known a serial scan type recording apparatus for performing the above. In such a serial scan type recording apparatus, since the recording is performed while alternately repeating the scanning of the carriage and the conveyance of the recording medium, it is important to prevent the recording from being discontinuous in the feeding direction of the recording medium. .

  In addition, in today's inkjet recording heads, the number of ink ejection nozzles (hereinafter, also simply referred to as nozzles) provided in one recording head is increased to form a long nozzle row with a large number of nozzles. With this configuration, a large number of ink droplets can be discharged at the same time, and the recording speed can be increased. Recently, a recording head in which 300 to 1280 nozzles are arranged at 600 dpi (0.042 mm pitch) has been put into practical use.

  FIG. 1 is a diagram showing a recording head having a plurality of nozzles and ruled lines that are recorded by the recording head and parallel to the conveyance direction of the recording medium. FIG. 1A shows a recording head 1 and a plurality of nozzles 2 provided in the recording head, and FIG. 1B shows a recording result by the recording head 1 of FIG. In this figure, since the recording head is attached with no inclination, the ruled line of the recording result has no seam.

  FIG. 2 shows the recording head 1 and the recording result when the recording head 1 is mounted at an angle. FIG. 2A shows the recording head 1 and the plurality of nozzles 2 that are attached at an angle, and FIG. 2B shows the recording result by the recording head 1 of FIG. When the recording head 1 is mounted in an inclined manner as described above, there is a seam in the recording result, and the ruled lines become discontinuous, so that the recording quality is significantly lowered.

  As described above, when the recording head 1 is mounted at an inclination, discontinuity occurs in the recording result, but there is a factor that causes a discontinuity in the recording result other than the recording head 1 mounted at an inclination. That is, when there is a difference in the carriage scanning speed between the first scanning and the second scanning of the recording head by the carriage, the recording result is discontinuous due to the deviation of the landing position of the ink ejected onto the recording medium. May occur. However, since there is almost no difference in the carriage scanning speed between the first scan and the second scan, it is rare that a discontinuity occurs in the print result. On the other hand, with the tendency to increase the number of nozzles of one recording head, the frequency of occurrence of discontinuity in recording results due to the recording head tilting in the plane including the nozzle outlet surface is increasing. As the number of nozzles included in one recording head is increased, the length of the nozzle row is increased, and the discontinuity in the recording result when the recording head is inclined becomes remarkable. This hinders further speeding up of recording. There has been proposed a recording apparatus including a correcting unit that corrects the inclination of the recording head (Patent Document 2).

  In addition, a parallel bar with different inclinations is recorded to create a predetermined pattern, and the optical characteristics of the pattern are acquired using an optical characteristic measuring means, and correction for correcting the inclination of the recording head based on the optical characteristics A recording apparatus provided with means has been proposed (Patent Document 3).

JP 2000-289252 A JP 2001-129983 A JP 2003-039793 A

  However, the correction means for correcting the tilt of the recording head in Patent Document 2 is a mechanical correction and is not suitable for automatic correction. In addition, in the detection of the tilt amount of the recording head in Patent Document 3, since parallel bars having different inclination degrees are recorded, the discharge control during pattern recording becomes complicated.

  Therefore, the present invention detects the tilt amount or the shift amount of the recording head using a pattern that can be created by a simpler control method. It is another object of the present invention to provide an ink jet recording apparatus that can correct the tilt or deviation of the recording head by changing the recording timing according to the detection result.

  For this purpose, the ink jet recording head recording position deviation correction method of the present invention uses a recording head in which a plurality of nozzles are provided in a nozzle row to perform recording by discharging ink from the nozzles onto a recording medium. A correction method for correcting a positional deviation of the recording head to be performed, wherein a plurality of detection patterns having different overlapping amounts are recorded, wherein the first recording and the second recording by the recording head are superimposed. Then, the density of each of the plurality of detection patterns is measured, and the inclination of the recording head is corrected based on the measurement result.

  The ink jet recording apparatus of the present invention uses a recording head in which a plurality of nozzles are provided in a nozzle row, and the recording head is displaced by ejecting ink from the nozzles onto a recording medium. An ink jet recording apparatus having means for correcting the image, wherein the first head recording and the second recording by the recording head are superposed on each other, and a plurality of detection patterns having different superposition amounts are recorded. And a means for measuring the density of each of the plurality of detection patterns and correcting the inclination of the recording head based on the measurement result.

  According to the correction method and the ink jet recording apparatus of the present invention, when correcting the tilt or the lateral position deviation of the recording head, a correction target (inclination) is partially used by partially using a plurality of nozzles provided in the recording head. The pattern is recorded by changing the nozzle used by the lateral shift. The recording at that time can be recorded by simple control. High-quality recording can be realized by correcting the recording head from the density of the recorded pattern.

  Hereinafter, the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to such an embodiment, and may be included in the concept of the present invention described in the claims of this specification. It can be applied to other technologies.

  FIG. 3 is a schematic perspective view showing a main part of the ink jet recording apparatus according to the embodiment of the present invention. The carriage 200 is fixed to the endless belt 201 and is movable along the guide shaft 202. The endless belt 201 is wound around a pulley 203, and a driving shaft of a carriage motor 204 is connected to the pulley 203. Therefore, the carriage 200 is scanned in the main scanning direction (A direction) along the guide shaft 202 by the rotational drive of the carriage motor 204. On the carriage 200, a recording head 1 in which a plurality of ink discharge nozzles are arranged in parallel and an ink tank 205 as a container for storing ink are mounted.

  In the recording head 1, a plurality of ink ejection ports (not shown) (hereinafter also simply referred to as nozzles) arranged in parallel in the conveyance direction of the recording medium P are formed on the surface facing the recording medium P. The recording head 1 is provided with an ink path in communication with each of the plurality of ink discharge ports, and an electrothermal converter that generates thermal energy for ink discharge corresponding to each ink path. Is provided. The electrothermal transducer generates heat by applying an electric pulse in accordance with driving data, thereby causing film boiling in the ink, and ejecting ink from the ejection port as the bubbles are generated. Each ink path is provided with a common liquid chamber that communicates with them in common, and this common liquid chamber is connected to the ink tank 205.

  Further, this apparatus is provided with a linear encoder 206 for detecting the movement position of the carriage. That is, there is a linear scale 207 along the moving direction of the carriage 200, and slits are formed in the linear scale 207 at equal intervals such as 600 pieces per inch. On the other hand, the carriage 200 is provided with, for example, a slit detection unit 208 having a light emitting unit and a light receiving sensor and a signal processing circuit. Accordingly, the encoder 206 outputs a signal indicating ink ejection timing and position information of the carriage 200 as the carriage 200 moves. By ejecting ink for each slit detection, it is possible to execute printing with a resolution of 600 dpi in the main scanning direction.

  Further, the recording medium P is intermittently conveyed in the direction of arrow B perpendicular to the scanning direction of the carriage 200. The recording medium P is supported with a certain tension by being sandwiched between a pair of roller units 209 and 210 provided on the upstream side in the transport direction and a pair of roller units 211 and 212 provided on the downstream side. The recording head 1 is transported in a state where flatness is ensured. Driving force for each of the roller units 209, 210, 211, 212 is applied by a recording medium transport motor (PF motor) (not shown).

  With such a configuration, recording is performed on the entire recording medium P while alternately recording the width corresponding to the arrangement width of the ink discharge ports and the conveyance of the recording medium P as the carriage 200 moves.

  The carriage 200 stops at the home position as necessary at the start of recording or during recording. A cap member 213 for capping the ejection surface side of each head is provided at the home position, and the cap member 213 forcibly absorbs ink from the ejection port and prevents clogging of the ejection port. A suction recovery means (not shown) is connected. Such recovery processing is performed as necessary when the carriage 200 stops at the home position.

  The reading means 107 for confirming the recording state is composed of a pair of a light emitting element such as a lamp or LED and an optical sensor such as a silicon photodiode (SPD), a phototransistor, a charge coupled device (CCD), or a CMOS sensor. Yes. Further, the reading means 107 is fixed to the carriage 200 and is movable in the main scanning direction. In order to check the recording state, the reading medium 107 irradiates the recording medium on which the detection pattern is recorded with the LED and detects the reflected light. Thus, information on discharge failure and uneven density can be obtained.

FIG. 4 is a block diagram showing the configuration of the control system of the ink jet recording apparatus.
When the CPU 100 is a central processing unit and receives recording information from the host device, the CPU 100 executes control of each part of the recording device and data processing. The ROM 101 stores a processing program related to each processing procedure of the CPU 100, and the RAM 102 is used as a work area when the processing procedure is executed. That is, the CPU 100 executes processing such as processing the recording information received from the host device using a peripheral unit such as the RAM 102 and converting it into recording data by the control program stored in the ROM 101. In addition, the CPU 100 outputs the drive data, that is, the recording data and the drive control signal of the electrothermal transducer to the head driver 103. The head driver 103 performs recording by driving the electrothermal transducer of the recording head 1 and ejecting ink based on the input driving data.

  The CPU 100 also controls a carriage drive motor 204 for reciprocating the carriage 200 and a recording medium transport motor 104 for transporting the recording medium P via motor drivers 105 and 106, respectively. The head driver 103 receives an ejection timing signal and position information of the carriage 200 from the encoder 206. The reading means 107 can read the reflection density by measuring the reflected light of the recording medium after recording.

Details of the reading means 107 will be described with reference to FIGS. 5 is a cross-sectional view in which the reading unit 107 is cut in the vertical direction, FIG. 6 is a front view of a light receiving portion of a sensor used in the reading unit 107, and FIG. It is a figure showing the positional relationship of optical related components.
In FIG. 5, reference numerals 110, 111, and 112 denote sensors, and a sensor chip 111 is mounted on the lead frame 112, and the periphery is sealed with a transparent package 110. The flexible substrate 113 is a substrate in which a circuit is formed by printing a copper foil pattern on a polyimide resin. The LED 114 is mounted on the flexible substrate 113. The LED 114 is mounted on the flexible substrate 113. A light shielding plate 116 for preventing the light from the LED 114 from directly entering the lens 115 is provided near the LED 114. These parts are built in the main body of the reading means 107. FIG. 6 shows a sensor chip. The light receiving area 312 is composed of an SPD (silicon photodiode), and light irradiated in this range is converted into a sensor current. In this embodiment, SPD is used, but any element that converts light into current may be used. Therefore, PSD (semiconductor position detector), CCD (charge coupled device), CMOS sensor, phototransistor, or the like may be used. This sensor current is amplified by an electronic circuit (not shown), converted from analog to digital (AD conversion), sent to the CPU 100, and the density of the recording result can be obtained by calculation. In FIG. 7, the light emitted from the LED 114 illuminates the recording medium P after recording. The light reflected from the recording medium P is collected by the lens 115 and forms an image on the sensor chip 111.

  Next, a basic method used in tilt adjustment described later will be described with reference to FIGS. 8, 9, 10, 11, and 12.

  FIG. 8 is a diagram showing the recording head 1, and the registration adjustment between the two recording heads will be described for the sake of simplicity. Reference numerals 1a and 1b denote recording heads, and the recording head 1b is aligned with the recording head 1a which serves as a reference for recording position alignment. At the time of recording position adjustment (hereinafter also referred to as registration adjustment), a detection pattern for registration adjustment is recorded, and the result of reading it by the reading means 107 is used to determine the amount of inclination or displacement (hereinafter, both are simply combined). The recording position deviation is also calculated and adjusted by changing the ink ejection timing. Next, a misregistration detection pattern for detecting the recording misregistration amount will be described with reference to FIGS. FIG. 9 is a diagram showing a misregistration detection pattern recorded by the recording head 1a serving as a reference for recording position alignment. FIG. 9A is a rectangular shape in which ink is printed by ejecting ink for 4 pixels horizontally and 8 pixels vertically. The three detection patterns are arranged in the main scanning direction, and there is a blank of the same size as the pattern between each pattern. Seven similar pattern combinations were recorded in the sub-scanning direction, and the patterns were (b), (c), (d), (e), (f), and (g) in order. Next, the misregistration detection pattern in FIG. 10 will be described. FIG. 10 is a diagram showing a positional deviation detection pattern of the recording head 1b to be matched with the reference recording head 1a, and the pattern of FIG. 10 (d) is the same as the pattern of FIG. 9 (d). The pattern in FIG. 10A is the same dot group as the pattern in FIG. 9A, but the image position is shifted by -3 pixels in the main scanning direction. The pattern shown in FIG. 10B is the same dot group as the pattern shown in FIG. 9B, but the image position is shifted by -2 pixels in the main scanning direction. The pattern of FIG. 10C is the same dot group as the pattern of FIG. 9C, but the image position is shifted by −1 pixel in the main scanning direction. The pattern shown in FIG. 10E is the same dot group as the pattern shown in FIG. 9E, but the image position is shifted by +1 pixel in the main scanning direction. The pattern (f) in FIG. 10 is the same dot group as the pattern (f) in FIG. 9, but the image position is shifted by +2 pixels in the main scanning direction. The pattern (g) in FIG. 10 is the same dot group as the pattern (g) in FIG. 9, but the image position is shifted by +3 pixels in the main scanning direction.

  FIG. 11 is a diagram in which both positional deviation detection patterns are recorded in an overlapping manner, and is a diagram recorded when the positions of the recording heads are not displaced. At this time, in FIG. 11 (d), the dots recorded by the recording head 1a and the dots recorded by the recording head 1b overlap, but FIG. 11 (c) shifts by -1 pixel in the main scanning direction. ing. FIG. 11B is shifted in the main scanning direction by −2 pixels. FIG. 11A is shifted in the main scanning direction by -3 pixels. FIG. 11E is shifted in the main scanning direction by +1 pixel. In FIG. 11F, +2 pixels are shifted in the main scanning direction. FIG. 11G shows a shift of +3 pixels in the main scanning direction.

  The density of the detection pattern is measured using the reading means 107 with the detection pattern thus recorded. If the measurement is performed in the state of FIG. 11, the density of the portion of FIG. 11 (d) where there are many unrecorded portions becomes light, and the portions of FIG. 11 (a) and FIG. Then, the density becomes deeper.

  FIG. 12 is a graph showing the reflection density of the detection pattern. The graph indicated by the solid line is the density distribution of the detection pattern recorded by the recording head without deviation, and the graph indicated by the broken line is the density distribution of the detection pattern recorded by the recording head having deviation. is there. The horizontal axis represents the pattern shift amount, and the vertical axis represents the reflection density. The shift amount of the pattern on the horizontal axis is the shift amount in the main scanning direction and corresponds to the shift amount of the recording position. By reading the shift amount of the detection pattern of the thinnest reflection density, it is possible to know the shift amount of the recording head on which the detected detection pattern is recorded. That is, it can be seen that the recording head that records the pattern of the graph indicated by the broken line is shifted by +1 pixel. In this way, the landing position of the ink droplet can be corrected by changing the recording timing in the main scanning direction during recording based on the pattern density result. In this way, the inclination and lateral position deviation of the recording head are confirmed. Here, the case where the inclination of the recording head is detected more specifically and the case where the lateral position deviation is detected will be described separately.

  Next, a method for detecting the inclination of the recording head according to the present embodiment using the basic deviation amount detection method described above will be described.

  FIG. 13 is a diagram illustrating a recording method when recording a detection pattern according to an embodiment of the present invention when detecting the tilt of the recording head 1. FIG. 13A shows the inclined recording head 1, and FIG. 13B shows the recording result. When normal recording is performed, recording is performed by conveying the recording medium in the sub-scanning direction. In this figure, FIG. 14, and FIG. Expressed as if it moved. A recording head represented by a dotted line in FIG. 13A represents a recording position before the recording head represented by a solid line. When detecting the tilt, a detection pattern similar to that shown in FIG. 11 is formed, but is slightly different from the description of FIG. In the above description, the relation (inclination, misalignment) of the recording head 1b with respect to the recording head 1a has been described. However, when detecting the inclination, the detection pattern shown in FIG. Form. A method of forming a detection pattern when detecting this inclination will be described.

  When detecting the inclination, first, in the recording head for checking the inclination, recording is performed using a predetermined number (four in the example shown in the figure) of ink discharge ports located on the upstream side with respect to the sub-scanning direction. Record). Thereafter, the recording medium is transported by a distance shorter than the length of the ejection port array in the recording head, and recording is again performed using the same number of ink ejection ports positioned on the downstream side with respect to the sub-scanning direction. Record 2). When recording is performed in this manner, the first recording and the second recording overlap with a recording head having no tilt, but when the recording head has a certain tilt, the first recording is performed as shown in FIG. And the second recording do not overlap. In FIG. 13, the first recording and the second recording are adjacent to each other. However, when the recording head has a larger inclination, the interval between the first recording and the second recording is shown. Is separated by the inclination. Such a recording method is applied to detection pattern formation as shown in FIG. That is, it can be applied by forming the pattern shown in FIG. 9 in the first recording and forming the detection pattern shown in FIG. 10 in the second recording so that they overlap each other.

  In this embodiment, the method of shifting the first recording and the second recording at the time of recording the detection pattern is different from the above-described example, but the principle of viewing the displacement of the recording head by the density of the recording result is the same. . FIG. 14A and FIG. 14C are diagrams showing a recording head and a recorded detection pattern when recording a detection pattern for detecting the inclination of the recording head. FIG. 14A shows the case where the recording head is not tilted, and FIG. 14C shows the case where the recording head is tilted. FIGS. 14B and 14D are enlarged views of the detection pattern used in the present embodiment.

  In the case of FIGS. 14A and 14B, the recording head is not inclined. For this reason, in the pattern d, the recording by the ink ejected from the ink ejection port located on the upstream side in the sub-scanning direction in the first recording and the ink ejection located in the downstream in the sub-scanning direction in the second recording. Recording with ink ejected from the outlet is recorded at the same position. As a result of the recording, the first recording and the second recording are substantially overlapped as in the pattern d ′, and there is a large area that is not recorded between the recording unit and the recording unit. The concentration is lowered. On the contrary, in the patterns other than the pattern d in which the positions are shifted in the first recording and the second recording, the non-recorded area decreases with the shift amount, and in the patterns a and g, The area that is not recorded is almost lost, and the density of the recorded result is the highest.

  In the case of FIGS. 14C and 14D, the recording head is tilted. For this reason, the first recording and the second recording in the pattern k, which should overlap if not tilted, are recorded without overlapping, and the portion that is not recorded like the pattern k ′ is almost eliminated and the density of the recording result is increased. . On the other hand, in the first recording and the second recording, recording is performed by shifting the position of the storage head. In patterns other than the pattern k, the first recording and the recording are performed in accordance with the shifted amount. The second recording will gradually overlap. As a result, in the pattern h and the pattern n, the first recording and the second recording substantially overlap each other, so that the area not recorded is the largest and the density of the recording result is the lowest.

  FIG. 15 is a diagram illustrating a recording method for recording a detection pattern when detecting a shift between two recording heads due to the recording head tilt. In this case, the detection pattern is formed by using two recording heads, that is, a reference recording head and a recording head for confirming the deviation. FIG. 15A shows the reference recording head S1 and the confirmation recording head S2 for confirming the deviation, and FIG. 15B shows the recording result of each recording head. In the case of detecting lateral deviation, recording is performed using only a predetermined number of ink ejection ports located at the center of the ejection port array of each recording head in both the reference recording head S1 and the confirmation recording head S2. That is, first, the first recording is performed by a predetermined number of ink discharge ports provided in the central portion of the reference recording head S1, and then the predetermined number of ink discharge ports provided in the central portion of the confirmation recording head S2 at the same position. A second recording is performed. If the confirmation recording head S2 is not displaced from the reference recording head S1, the first recording and the second recording substantially overlap. In the recording result of FIG. 15B, the confirmation recording head S2 is tilted with respect to the reference recording head S1, but is substantially overlapped at the center because there is no lateral shift.

  Such a recording method is applied to detection pattern formation as shown in FIG. That is, it is possible by forming the pattern shown in FIG. 9 in the first recording, forming the detection pattern shown in FIG. 10 in the second recording, and making them overlap. FIG. 16A and FIG. 16C are diagrams showing the recording head and the recorded detection pattern when recording the detection pattern for detecting the deviation of the lateral position of the recording head. FIG. 16A illustrates a case where the recording head is not displaced, and FIG. 16C illustrates a case where the recording head is displaced. FIGS. 16B and 16C are enlarged views of the detection pattern used in the present embodiment.

  In the case of FIGS. 16A and 16B, the position of the recording head 514 serving as a reference and the recording head 515 for confirming the deviation are not shifted. Therefore, in the pattern r, the recording by the ink ejected from the ink ejection port located in the middle part of the nozzle row in the first recording and the ink ejected from the ink ejection port located in the middle part of the nozzle row in the second recording. Is recorded at the same position. As a result of the recording, the first recording and the second recording are substantially overlapped as in the pattern r ′, and there are many unrecorded areas between the recording parts, and as a result, the entire recording part The concentration is lowered. On the other hand, in the patterns other than the pattern r in which the positions are shifted in the first recording and the second recording, the area that is not recorded decreases with the shift amount. In the pattern o and the pattern u, the area not recorded is almost eliminated, and the density of the recorded result is the highest.

  In the case of FIGS. 16C and 16D, the positions of the recording head 514 serving as a reference and the recording head 515 for confirming the displacement are displaced. The first recording and the second recording in the pattern y, which should overlap if they are not shifted, are recorded without overlapping, and the portion that is not recorded like the pattern y ′ is substantially eliminated, and the density of the recording result is increased. On the other hand, in the first recording and the second recording, recording is performed by shifting the position of the storage head. In a pattern other than the pattern y, the first recording and the recording are performed in accordance with the shifted amount. The portion where the second recording gradually overlaps increases. As a result, in the pattern v and the pattern β, the first recording and the second recording substantially overlap each other, so that the area that is not recorded is the largest and the density of the recording result is the lowest.

  The detection pattern formed by such a method is measured by using the reading means 107 to measure the density of the detection pattern, and by confirming the portion with the lowest density, the amount of inclination or the amount of lateral deviation can be known.

  Next, the tilt correction method will be described with reference to FIGS. 17, 18, and 19. In each figure, (a) is a diagram showing the tilt of the head, and (b) is a timing chart in which the nozzles eject ink. For ease of control, three nozzles are grouped into one group, and the nozzles in the group Are discharged at the same timing. (C) is a result of recording vertical ruled lines. FIG. 17 shows the ejection timing of each nozzle and the recording result of the vertical ruled line when the recording head is not inclined. From the timing chart of (b), it can be seen that all nozzles are ejecting at the same timing. 18 and 19 show the ejection timing of each nozzle and the recording result of the vertical ruled lines when the recording head is tilted. In FIG. 19, T indicates the ejection cycle of one nozzle. Three nozzles are grouped from the top in the figure, and the nozzle groups are G1, G2, G3, and G4. The time difference between the discharge timings of the nozzle group G1 and the nozzle group G2 is t1, the time difference between the discharge timings of the nozzle group G1 and the nozzle group G3 is t2, and the time difference between the discharge timings of the nozzle group G1 and the nozzle group G3 is t3. To do.

The recording head is scanned in the main scanning direction by the carriage 200 and records at a discharge frequency of 12 kHz and 600 dpi in the scanning direction. The discharge period T at this time is
T = 1 / Discharge frequency (Hz)
Therefore, the discharge cycle T when the discharge frequency is 12 kHz is
T = 1/12000 (Hz) = 83.33 μsec
It is. T3 for correcting the inclined recording head is
t3 (seconds) = recording head tilt amount (dot) × T
It can be expressed as. The sign t3 is reversed depending on the scanning direction. In the example of FIG. 19, t3> 0 when the recording head scans from left to right and t3 <0 when scanning from right to left. . Here, when t3 is expressed using a discharge frequency (Hz),
t3 (seconds) = print head tilt amount (dot) / ejection frequency (Hz)
Is required. When the recording head tilt amount is 1 dot and the discharge frequency is 12 kHz,
t3 = 1/12000 = 83.33 μsec
When t1 and t2 are expressed using t3,
t1 = t3 / (4-1)
t2 = t3 × 2 / (4-1)
It becomes. And when there are n nozzle groups,
tn (seconds) = head tilt amount (pixels) / ejection frequency (Hz)
t1 = tn / (n-1)
t2 = tn × 2 / (n−1)
t3 = tn × 3 / (n−1)
t4 = tn × 4 / (n−1)
・
・
・
t (n-2) = tn * (n-2) / (n-1)
t (n-1) = tn * (n-1) / (n-1)
In this way, when the number of nozzle groups is n, the deviation time of the discharge timing of the m-th group and the first nozzle group can be expressed by a generalized expression:
tm = tn × m / (n−1)
It can be expressed as.

  FIG. 20 shows the result of recording the vertical ruled lines when the inclined recording head is scanned and corrected by the above correction method, and the recording head is shown as moved for ease of explanation. FIG. 20A shows the tilt of the recording head, and FIG. 20B shows the recording result. 2A and 20A have the same inclination in the recording head, but the vertical ruled lines before correction in FIG. 2B are like the vertical ruled lines in FIG. 20A after correction. You can see that it has been corrected.

  As described above, according to the present embodiment, the nozzles in the nozzle array are partially used, and the nozzles used for detection are changed depending on the object to be detected (tilt, lateral deviation). The detection pattern that can be recorded by is recorded. Then, by reading the reflection density of the detection pattern with a sensor, it is possible to automatically correct the lateral deviation of the recording head and the inclination of the recording head, thereby realizing an ink jet recording apparatus capable of high-quality recording. did it.

FIG. 3 is a diagram illustrating a recording head and ruled lines recorded by the recording head. The recording head and the recording result when the recording head is mounted at an inclination are shown. 1 is a schematic perspective view showing a main part of an ink jet recording apparatus according to an embodiment of the present invention. It is a block diagram which shows the structure of the control system of an ink jet recording apparatus. It is sectional drawing which cut the reading means in the vertical direction. It is a front view of the light-receiving part of the sensor used for the reading means. It is a figure showing the positional relationship of the optical related components in FIG. It is a figure which shows a recording head. It is a figure of the detection pattern used as the reference | standard of recording position alignment. FIG. 6 is a diagram illustrating a positional deviation detection pattern of a recording head that is aligned with a reference recording head. FIG. 11 is a diagram in which the positional deviation detection patterns of FIGS. 9 and 10 are recorded in an overlapping manner. It is the figure which represented the reflection density of the detection pattern in the graph. FIG. 10 is a diagram illustrating a recording method when recording a detection pattern when detecting the tilt of the recording head. FIG. 6 is a diagram of a detection pattern for detecting the inclination of the recording head. FIG. 6 is a diagram illustrating a recording method when recording a detection pattern when detecting a lateral shift of the recording head. FIG. 6 is a diagram of a detection pattern for detecting a lateral shift of a recording head. This is a recording result of ejection timing of each nozzle and a vertical ruled line when there is no inclination of the recording head. It is a recording result of the ejection timing of each nozzle and the vertical ruled line when the recording head is tilted. It is a recording result of the ejection timing of each nozzle and the vertical ruled line when the recording head is tilted. It is a recording result of a vertical ruled line when the inclined recording head is scanned and corrected.

Explanation of symbols

1 Recording head 100 CPU
101 ROM
102 RAM
DESCRIPTION OF SYMBOLS 107 Reading means 200 Carriage 201 Endless belt 202 Guide shaft 203 Pulley 204 Carriage motor 205 Ink tank 206 Linear encoder 209 Roller unit 210 Roller unit 211 Roller unit 212 Roller unit 213 Cap member P Recording medium S1 Reference recording head S2 Confirmation recording head

Claims (5)

A correction method for correcting a positional deviation of the recording head that performs recording by discharging ink from the nozzle onto a recording medium using a recording head provided with a plurality of nozzles in a nozzle row,
A pattern in which the first recording and the second recording by the recording head are superposed, and a plurality of detection patterns having different superposition amounts are recorded,
Measuring the density of each of the plurality of detection patterns, and correcting the inclination of the recording head based on the measurement result;
A method for correcting a recording position deviation of an ink jet recording head.   The method of claim 1, wherein the first recording and the second recording are performed by different nozzles.   The method of claim 2, wherein the different nozzles are a plurality of nozzles provided at both ends of the nozzle row.   4. The recording position shift of the ink jet recording head according to claim 1, wherein the first recording and the second recording are obtained by arranging a plurality of rectangular patterns. 5. Correction method. An inkjet recording apparatus having means for correcting a positional deviation of the recording head that performs recording by ejecting ink from the nozzle onto a recording medium using a recording head in which a plurality of nozzles are provided in a nozzle row. There,
Means for recording a plurality of detection patterns in which the first recording and the second recording by the recording head are superposed, and different superposition amounts;
Means for measuring the density of each of the plurality of detection patterns, and correcting the inclination of the recording head based on the measurement result;
An ink jet recording apparatus comprising:

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