JP2014217958A - Recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording device capable of performing recording of high quality by carrying out accurate detailed conveyance control over an actually used recording medium in an ink jet printer.SOLUTION: A test pattern with a long cycle is printed through first scanning in ongoing and return ways by utilizing nozzle intervals. A candidate for a correction value is selected therefrom, a test pattern with a short cycle is recorded using values before and after the candidate, and a sensor reads the density of the test pattern. An approximate expression is used for a value obtained by reading the test pattern with the short cycle, and a correction is determined at a value of a minimum resolution unit closest to a peak of an approximated line. Conveyance is carried out using such a correction value so as to record an image where dot deviation is suppressed.

Description

  The present invention relates to a recording apparatus equipped with an inkjet head that ejects ink onto a recording medium.

  2. Description of the Related Art Inkjet recording apparatuses that record ink, ink, and the like by supplying ink from an ink cartridge to an inkjet recording head and ejecting ink droplets from the recording head onto a recording medium have become widespread.

  Such inkjet recording heads are not only small ones used in homes and small offices, but also large ones capable of printing on large recording media exceeding 1 meter wide. Widely adopted.

  In such an ink jet recording apparatus, an ink jet recording head is mounted on a carriage that reciprocates in the width direction of the recording medium, that is, in the main scanning direction, and ink is ejected to the recording medium in the forward path and the backward path. Further, the recording medium is conveyed in a direction perpendicular to the reciprocating direction, that is, in the sub-scanning direction. Recording is performed by repeatedly transporting the recording medium for each amount obtained by dividing the recording head into a plurality of equal parts and ejecting ink while moving the carriage in the main scanning direction. The position of the carriage is read by a sensor mounted on the carriage with a linear scale provided along the moving direction of the carriage to obtain the position of the carriage. In general, a device called a linear encoder is used.

  The amount of movement in the transport direction varies depending on the material and thickness of the recording medium. This is because, depending on the material, the friction with the transport path is small and slips, and when the recording medium is transported while being held between rollers, the recording medium is deformed to cause a slight shift in the transport amount. If this deviation is left, streaks will appear in the recorded image, resulting in poor quality. Therefore, it is necessary to correct the deviation. For example, a test pattern is printed on a recording medium, a deviation amount is obtained from the test pattern, and a correction value corresponding to the deviation amount is input to the recording apparatus. Based on the input correction value, the conveyance amount is changed to eliminate conveyance deviation.

  For example, in Japanese Patent Laid-Open No. 2003-011344, this test pattern is formed by two recording scans. The conveyance amount of the recording medium performed between the two recording scans is varied. The user selects an optimal pattern in which black stripes or white stripes are not visible from the test pattern print result. Then, the correction value is determined based on the carry amount in the selected pattern.

JP 2003-011344 A

  By the way, in the method of forming a test pattern consisting of a plurality of patterns with different carry amounts as described above and selecting the optimum pattern, the user-selectable pattern is set for each minimum carry amount that can be carried. It is necessary to print the pattern. Therefore, in order to print a test pattern, time, paper, and ink for printing selectable patterns are required. That is, a large amount of different patterns must be printed, and a large amount of time, paper, and ink are required.

  SUMMARY An advantage of some aspects of the invention is that it provides a recording apparatus that can adjust the conveyance amount of a recording medium in the sub-scanning direction more precisely, in a short time, and appropriately.

  The recording apparatus of the present invention includes a recording head in which the plurality of nozzles that form dots by ejecting ink onto a recording medium are arranged at equal intervals in the recording medium conveyance direction, a conveyance unit that conveys the recording medium, A carriage that mounts the recording head and reciprocally scans the recording head in a direction intersecting the conveyance direction of the recording medium, and a position that faces the recording head that reciprocally scans along the scanning direction of the recording head. A platen disposed and supporting the recording medium; a sensor mounted on the carriage for detecting the density of an image recorded on the recording medium; and a plurality of the recording medium supported on the platen in a planar shape. A test pattern composed of dots is recorded, the density of the test pattern is detected by the sensor, and the recording is performed based on the detected density. And a control unit that controls the conveyance of the recording medium based on the correction amount obtained by the calculation, and stores the correction amount for the conveyance amount. Correction amount storage means, and the control means comprises a first predetermined number of the dots by changing the nozzle to be used according to the recording position on the recording medium while moving the carriage, The evaluated dot row constituting a part of the test pattern is recorded, the recording medium is transported by a predetermined transport amount without being corrected by the correction amount, and the evaluated dot row is recorded while moving the carriage. The ink is ejected onto the recording medium by the nozzle at a position away from the nozzle serving as a reference among the nozzles by the predetermined conveyance amount, and the evaluated An evaluation dot row composed of a second predetermined number of dots along the dot row and forming a part of the test pattern is recorded, and the evaluated dot row and the evaluation are recorded by the sensor according to the printing position. The recording position obtained by detecting the density of the test pattern composed of dot rows, calculating the recording position where the degree of overlap between the evaluated dot row and the evaluation dot row is greatest based on the detection result, and calculating the recording position The correction amount is calculated from the distance between the nozzle for recording the reference nozzle and the reference nozzle and the predetermined transport amount, and the correction amount obtained by the calculation is stored in the correction amount storage means. To do.

  It is possible to provide a recording apparatus that can perform high-quality recording by optimizing the feeding amount in the conveyance direction of the recording medium and performing more precise and appropriate conveyance control on the recording medium. Further, since the recording area of the test pattern can be reduced, the amount of recording medium used and the amount of ink used can be reduced. It is possible to provide a recording apparatus that can adjust the conveyance amount of the recording medium in the sub-scanning direction more precisely, in a short time, and appropriately.

FIG. 1 is a block diagram of the recording apparatus. FIG. 2 is a schematic diagram of the arrangement of the recording head and the detection sensor mounted on the carriage. FIG. 3 is a diagram for explaining a test pattern and a detection range by the detection means. FIG. 4 is a diagram illustrating the relationship between the nozzle position and the first test pattern. FIG. 5 is a diagram for explaining a test pattern. FIG. 6 is a diagram illustrating a first example of a test pattern recorded on a recording medium. FIG. 7 is a diagram illustrating a second example of the test pattern recorded on the recording medium. FIG. 8 is a diagram for explaining a third example of the test pattern recorded on the recording medium. FIG. 9 is a flowchart for explaining the operation of the first example of test pattern recording and detection. FIG. 10 is a flowchart for explaining the operation of the second example of test pattern recording and detection. FIG. 11 is a flowchart for explaining the operation of the third example of test pattern recording and detection. FIG. 12 is a schematic diagram showing the entire recording apparatus.

Hereinafter, embodiments will be described with reference to the drawings.
First, the entire inkjet printer 1 that is the recording apparatus of the present embodiment will be described with reference to FIG. The inkjet printer 1 includes a rail 2 that extends linearly in the width direction. A carriage 3 reciprocates along the rail 2. An ink jet recording head is mounted on the carriage 3. Since the recording head performs color printing, light cyan, light magenta, and gray are produced by reducing the pigment density of each ink of cyan, magenta, and black to four colors of yellow, cyan, magenta, and black. It is mounted on the carriage 3 corresponding to the color ink. By using light-type ink, the color reproducibility is improved and the recorded image quality can be improved. The cap 4 is sealed so that the recording head does not dry, or the ink is periodically sucked from the inkjet head for maintenance. The transport means for transporting a recording medium such as paper or plastic film includes a number of transport rollers 9 arranged along the rail 2, and transports the recording medium by rotating the transport rollers 9.

  The carriage 3 is connected to an endless belt 5, and the endless belt 5 is connected to a motor 6. The endless belt 5 is wound around a pulley installed at the end of the inkjet printer 1. By driving the motor 6, the endless belt 5 moves, and the carriage 3 also moves at the same time.

  The platen 7 is a flat plate disposed along the rail 2. The platen 7 has a plurality of suction holes on the surface, and can be fixed by sucking the conveyed recording medium through the suction holes. An after guide 8 is provided on the downstream side of the platen 7 in the conveyance direction of the recording medium. The after guide 8 guides the recording medium to be conveyed. A pre-guide is provided on the upstream side of the platen 7 in the conveyance direction of the recording medium. The platen 7, the after guide 8, and the pre guide are provided with heaters and can be heated. The recording medium conveyed by this heating is heated to an appropriate temperature. Heating promotes ink fixing. Further, the platen 7 always supports the recording medium in a flat shape so that a certain quality can be maintained with respect to the test pattern recording.

  The platen 7 is a flat plate made of aluminum. The aluminum flat plate has a flat surface and is provided with suction holes. A groove is provided on the back side, and a heater wire is embedded in the groove to heat the platen 7. Further, the after guide 8 and the pre-guide are made by bending an iron plate, a heater wire is arranged on the back side, and an aluminum sheet is covered and fixed. When a test pattern is recorded by the heater, a constant temperature is maintained so that a constant quality can be maintained with respect to the recording of the strike pattern.

  FIG. 1 is a block diagram of the recording apparatus. The control means 11 is a control means that operates according to a program stored in advance and performs various controls of the entire recording apparatus. The ROM 12 is a non-volatile memory and stores information such as a program of the control unit 11 and initial setting values. The RAM 13 is a work memory used for calculation by the control means 11 or a memory for temporarily storing information. A test pattern is stored in the ROM 12 in advance. This test pattern has a plurality of patterns according to the situation, and the control means 11 reads out and uses the necessary test patterns from the plurality of test patterns according to the situation.

  The transport unit 14 includes a transport roller 9, a motor that drives the transport roller 9, and a drive circuit that drives the motor, and is a unit that transports the recording medium. The conveyance roller 9 is composed of a pair of a driving roller and a pinch roller, and rotates the driving roller with a motor. The pinch roller is pressed by the driving roller and rotates around. The recording medium is conveyed while being sandwiched between the drive roller and the pinch roller. The control circuit 11 controls the drive circuit of the transport unit 14 to drive the motor, rotate the transport roller 9 and transport the recording medium. The conveyance amount is controlled based on the number of rotations of the conveyance roller 9. Therefore, there is a possibility that the actual transport amount is deviated due to deformation when the recording medium is sandwiched, and transport correction is necessary.

  The carriage moving unit 15 moves the carriage 3 fixed to the endless belt 5 along the rail 2. The motor 6 that rotates the endless belt 5 is driven by a drive circuit included in the carriage moving means 15. This drive circuit is controlled by the control means 11. The carriage 3 moves along the rail 2 according to the program of the control means 11.

  The recording means 16 includes a recording head corresponding to the ink color. The recording head performs an ink ejection operation based on the drive signal of the head drive circuit. The head drive circuit operates based on a control signal from the control means 11.

  The linear encoder 17 optically detects a scale of a linear scale arranged linearly along the moving direction of the carriage 3. The linear encoder 17 operates based on a control signal from the control unit 11, AD converts the detection result, and outputs the signal to the control unit 11. By counting this signal, the control means 11 can specify the position of the carriage 3, acquire the position, and perform control according to the position.

  The position of each recording head provided in the carriage 3 can be specified in advance and stored in the ROM 12. A desired image can be recorded by driving the recording head and ejecting ink according to the position of the carriage 3, that is, the recording head.

  The R detection means 18 is an optical sensor that emits red light and detects the reflected light. The G detection means 19 is an optical sensor that emits green light and detects the reflected light. The B detection means 20 is an optical sensor that emits blue light and detects the reflected light. These detection means detect the density of the image recorded on the recording medium in the detection range of each detection means, and output the result to the control means 11. The control unit 11 calculates based on the detection result and varies the ejection timing of the recording head, thereby improving the image quality to be recorded.

  FIG. 2 is a schematic diagram of the arrangement of the recording head and the detection sensor mounted on the carriage. A carriage base 21 is provided at a position facing the platen 7 of the carriage 3. A recording head is fixed to the carriage base 21. The recording head has seven recording heads corresponding to cyan, magenta, yellow, black, light cyan, light magenta, and gray, that is, cyan recording head 22 and magenta recording head. 23, a yellow recording head 24, a black recording head 25, a light cyan recording head 26, a light magenta recording head 27, and a gray recording head 28 are fixed to the carriage base 21. The R detection means 18, the G detection means 19, and the B detection means 20 are arranged in this order along the longitudinal direction of the recording head. The R detection means 18 detects cyan and light cyan colors. Since these two colors use the same pigment as the color material with different concentrations, they can be detected by the same detection means. The same applies to the G detection means 19 for magenta and light magenta colors. The B detection means 20 detects a yellow color. Also, the black color and the gray color are used for detection because the reaction of the B detection means 20 is good among the colors of the light source. The black and gray colors are also the same pigment and have different concentrations.

  FIG. 3 is a diagram for explaining a test pattern and a detection range by the detection means. The B detection means 20 fixed to the carriage base 21 has a detection range 31 within the recording range of the strip-shaped test pattern 30 recorded on the recording medium. The B detection means 20 has a detection range 31 on a line 32 along the main scanning direction. The density is detected by changing the location several times for one test pattern. In the figure, six concentrations are detected. This average value can be taken as a density value. The test pattern is formed in black by the black recording head 25. Since the test pattern is usually recorded on a white recording medium, the contrast is increased and the detection error is reduced.

  FIG. 4 is a diagram illustrating the relationship between the nozzle position and the first test pattern. A number of nozzles 41 that eject ink are provided on the nozzle surface of the recording head 40. All nozzle intervals 49 in the sub-scanning direction are the same interval. A straight line can be drawn by ejecting ink while moving in the moving direction of the carriage 3, that is, in the main scanning direction. For example, ejection can be performed on a dotted line 43 indicating the scanning position of the nozzle 42. The same applies to the other nozzles, and a straight line parallel to the dotted line 43 can be drawn.

  Since the intervals in the sub-scanning direction of the plurality of nozzles 41, i.e., the conveyance direction of the recording medium, are equal, the deviation of the conveyance amount is detected using this interval. This principle will be described. A predetermined pattern is recorded on the recording medium. For example, the carriage 3 is scanned, and first the first basic pattern 44 is recorded from three nozzles with the nozzle 42 at the head. This is a line segment composed of continuous dots for the determined number of dots. After a short interval, dots are formed in the same manner from the three nozzles starting from the nozzle next to the nozzle 42, and the second basic pattern 45 is recorded. After a short interval, the third basic pattern 46 is recorded in the same manner by shifting the nozzle by one. Similarly, the fourth basic pattern 47 and the fifth basic pattern 48 are recorded while shifting. Next, the recording medium is conveyed. The carry amount is an interval between the leading nozzle 56 that records the third basic pattern 46 that is the center of the basic pattern and the leading nozzle 57 that records the evaluation line 50 for evaluating the basic pattern. The evaluation line 50 is formed by three nozzles similarly to the width of the basic pattern.

  If the actual conveyance is equal to the theoretical conveyance amount, the dots by the three nozzles with the nozzle 57 as the head overlap the third basic pattern 46. In practice, however, the majority of the deviation 58 occurs.

  An evaluation line 50 is recorded on each basic pattern, and a first evaluation pattern 51, a second evaluation pattern 52, a third evaluation pattern 53, a fourth evaluation pattern 54, and a fifth evaluation pattern 55 are recorded. The density of these evaluation patterns is detected by a detection means. From the detection result, the tendency of the concentration level can be seen. For example, the pattern with the lowest density indicates that the basic pattern and the evaluation line overlap. If this is the third basic pattern 46, it indicates that the theoretical value and the actual value are almost the same. As shown in the figure, the second evaluation pattern 52 based on the second basic pattern 45 and the evaluation line has the highest density. Since it is low, it can be seen that the transport amount is shifted. A deviation amount can be estimated by obtaining an approximate curve from the density values of the basic pattern and the evaluation pattern, and obtaining an extreme value thereof. Since the theoretical transport amount and the nozzle pitch are known, it can be understood how much the extreme value of the approximate curve has deviated from the theoretical transport amount. If the deviation amount is known, the theoretical conveyance amount and the actual conveyance amount coincide with each other by correcting the deviation amount with respect to the theoretical conveyance amount. The approximate curve is derived by calculation using a statistical method such as the least square method, and the value or expression is stored and used for other calculations.

  In this example, the nozzles are arranged in a single row. However, the nozzles do not necessarily have to be one row, and even if they are arranged in a plurality of rows, recordings in which the intervals between adjacent nozzles in the conveyance direction of the recording medium are equal. If it is a head, it can be handled similarly. For example, if the top of the nozzle is the first, the next is the second, the following 3, 4,... The last, the odd and even numbers are arranged in a straight line, and the first and second. It is only necessary that the intervals in the conveyance direction of the recording medium between the second, third, third and fourth adjacent nozzles are equal.

  FIG. 5 is a diagram for explaining a test pattern. Two types of test patterns are used to obtain the amount of deviation in more detail. FIG. 5A shows the second test pattern, and FIG. 5B shows the first test pattern described above.

  The first test pattern is a pattern in which a recording unit that records dots and a non-recording unit that does not record dots are alternately arranged a plurality of times in the conveyance direction of the recording medium. The second test pattern is a pattern in which a recording unit that records dots and a non-recording unit that does not record dots are alternately arranged a plurality of times in the conveyance direction of the recording medium. The period formed by the recording part is short.

  FIG. 6 is a diagram illustrating a first example of a test pattern recorded on a recording medium. First, a first test pattern is recorded in the main scanning direction. The first test pattern is recorded in an area written as pattern 1 in the drawing. A conveyance amount is used in which the interval between adjacent nozzles is 0.3% of the unit conveyance amount during the theoretical test. The center is theoretically ± 0, and the nozzles used for recording are shifted one by one as the pattern is separated. By doing so, every time one nozzle is separated, the pattern is separated by 0.3% with respect to the unit transport amount. Then, an evaluation line is recorded with respect to these patterns by a nozzle corresponding to a theoretical unit transport amount. The density value for the pattern separated by 0.3% can be acquired, and the deviation amount of the carry amount is calculated therefrom.

  Furthermore, the test pattern is recorded by shifting the actual transport amount by a predetermined amount with the previously obtained shift amount as the center value. Here, the second test pattern is used. That is, the second test pattern is recorded in an area written as pattern 2 in the drawing. After the conveyance, recording is performed to detect the density of the pattern. First, a basic pattern is recorded, and the recording medium is conveyed by a conveyance amount that is changed by a predetermined rate with respect to the unit conveyance amount at the time of the test, and the pattern is recorded for evaluation. As this pattern, a second test pattern having a shorter cycle than the first test pattern is used.

  Specifically, when the actual amount of deviation is deviated and conveyed with the deviation amount obtained previously as the center value, for example, the deviation amount of the center value obtained in increments of 0.3% is assumed to be + 0.3%. In this case, the second test pattern is recorded in increments of 0.1% in the positive and negative directions with respect to the value of + 0.3%. In the figure, a second test pattern of 6 stages is recorded, and if the center value is 0.3%, the conveyance amount is actually increased from 0.0 to + 0.6% in increments of 0.1%. Will be recorded. The density of these patterns can be detected by the detection means, and the amount of deviation with respect to the unit transport amount can be calculated. By doing so, the amount of deviation can be acquired in more detail.

  FIG. 7 is a diagram illustrating a second example of the test pattern recorded on the recording medium. In the first example, it is necessary to record a large amount in the conveyance direction of the recording medium, and a large amount of the recording medium is used. However, in the second example, this can be reduced.

  The first test pattern is recorded three times with different conveyance amounts. A first test pattern is recorded in an area written as pattern A in the drawing. When recording, when the basic pattern is recorded and the recording medium is transported, the transport is −0.2% with respect to the unit transport amount at the time of the theoretical recording medium test, and the theoretical after the transport An evaluation line is recorded by the nozzle corresponding to the unit transport amount during the test. The theoretical transport amount is a transport amount when transported without performing correction or the like during transport.

  In addition, the first test pattern is recorded in an area written as pattern B in the drawing. During recording, when the basic pattern is recorded and the recording medium is transported, it is transported to be -0.1% with respect to the unit transport amount at the time of the theoretical recording medium test, and after the transport, the theoretical pattern is theoretically transported. An evaluation line is recorded by the nozzle corresponding to the unit transport amount during the test. A first test pattern is recorded in an area written as pattern C in the drawing. When recording, when the basic pattern is recorded and the recording medium is transported, the transport is ± 0.0% with respect to the unit transport amount at the time of the theoretical recording medium test. An evaluation line is recorded by a nozzle corresponding to the carry amount.

  By recording the test pattern in this way, it is possible to record a test pattern that has been transported in the same manner as the transport varied by 0.1% with respect to the unit transport amount during the test.

  By detecting the density of the recorded test pattern by the detection means, calculating an approximate curve of density from the detection result, and obtaining the extreme value, the deviation amount with respect to the unit transport amount at the time of the test at which the density is minimum can be estimated. By correcting the carry amount using this estimated value, dots before and after the carry can be overlapped, and an image with good image quality can be obtained. Further, by recording the test pattern in this way, the number of lines to be recorded can be reduced, so that the recording medium can be saved.

  Furthermore, the detection time can be further shortened. First, the density of the test pattern in the area of pattern A is detected, an approximate curve of density is calculated from the detection result, an extreme value is obtained, and a calculation for estimating the conveyance amount at which the density is minimum is performed. When the transport amount estimated here is, for example, + 0.4%, test patterns of + 0.2%, + 0.3%, + 0.5%, and + 0.6%, which are predetermined ranges before and after the transport amount. The concentration of is detected. Thus, after estimating the conveyance amount in advance, the conveyance amount can be calculated from more detailed data by detecting only the density of the test pattern before and after that. Since it is not necessary to detect the density of all test patterns, it is possible to efficiently calculate the optimum deviation amount for the unit transport amount during the test, and from there, calculate the correction amount for the ideal transport amount. Can do.

  FIG. 8 is a diagram for explaining a third example of the test pattern recorded on the recording medium. In the second example, it is necessary to record many test patterns on the recording medium, and the amount of ink used is large, but in the third example, this can be reduced.

  First, a test pattern corresponding to a predetermined range that does not satisfy the maximum range is recorded and detected with respect to the maximum range of deviation detected by the test pattern. Subsequent detailed detection ranges enable detection within the maximum range. First, a test pattern having a large period is recorded, and the density is detected. An approximate curve of the density is calculated from the detection result, an extreme value is obtained, and a calculation for estimating the deviation value of the conveyance amount at which the density is minimum is performed. The test pattern corresponding to the deviation amount of the transport amount before and after the center value is the value of the deviation amount with respect to the unit conveyance amount that can be actually controlled, which is closest to the value of the deviation amount of the unit conveyance amount at the time of the test. Is recorded and its concentration is detected. An approximate curve of density is calculated from the detection result, an extreme value is obtained, and a calculation for estimating a deviation amount with respect to the transport amount at the time of the test at which the density is minimum is performed. The value of the deviation amount relative to the unit conveyance amount at the time of the closest test that can actually be controlled is stored as the final deviation amount value with respect to the calculated deviation amount value, and the recording medium is conveyed based on this value. The conveyance is controlled by correcting the amount. In the case of recording the pattern B, the transfer is performed by shifting the distance between the nozzles by 1/3 with respect to the unit transfer amount at the time of the test, and in the case of the pattern C by shifting the distance by 2/3. A value obtained by equally dividing the inter-nozzle distance becomes a deviation amount with respect to the unit conveyance amount, and enables detailed detection. For example, the unit transport amount is determined so that a one-third distance between the nozzles corresponds to 0.1% of the unit transport amount. If the distance between the nozzles is equally divided and the interval is set so as to correspond to the resolution of the conveyance amount to be obtained, detection using the test pattern can be easily performed.

  In the second example, 21 patterns need to be recorded as shown in FIG. In contrast, in the third example, the correction value can be determined by recording 12 patterns indicated by the solid line in FIG. In some cases, a test pattern can be recorded in a portion indicated by a dotted line. This saves ink during testing. In the third example, the transport amount used for recording is larger than that in the second example, but less than in the first example. Further, in FIG. 8, after recording the pattern A1, the patterns A2 to C are transported and recorded, but after recording the pattern A1 without transporting, the pattern A2 is recorded and transported in the main scanning direction. If the pattern C is conveyed and recorded, the test pattern can be recorded in three stages as in the second example.

FIG. 9 is a flowchart for explaining the operation of the first example of test pattern recording and detection. The control means 11 controls the operation according to the program.
First, in step S1, an initial value for recording the first test pattern is set. Based on the range to be investigated with respect to the theoretical transport amount, the number of patterns to be recorded by the first test pattern and the used nozzles are set. Depending on the width of the recording paper, the test pattern that can be recorded on one line is limited, and it is necessary to record over a plurality of lines.

Next, in step S2, the first test pattern is recorded. This includes basic patterns and evaluation lines.
Next, in step S3, the density of the first test pattern is measured by the detection means for each pattern, and the result is stored in the RAM 13.

Next, in step S4, the recording medium is fed to a position where a new test pattern can be recorded.
Next, in step S5, all patterns are recorded and it is confirmed whether they are detected. This is because the first test pattern is recorded in a plurality of lines depending on circumstances. If all are completed, the process proceeds to step S6, and if not completed, the process proceeds to step S1.

  Next, in step S6, an approximate curve is calculated based on the density data stored in the RAM 13, an extreme value is obtained, and an amount of deviation from the theoretical transport amount at which the density is minimum is calculated. The closest recorded test pattern is the median value of the provisional deviation. Alternatively, the median value of the provisional deviation amount may be the closest to the deviation amount of the controllable conveyance amount of the recording medium.

Next, in step S7, a set value for recording the second test pattern is set around the median value of the provisional deviation amount. That is, the median, the range to be investigated, the number of patterns to be recorded in the second test pattern, the transport amount, and the used nozzle are set.
Next, in step S8, a second test pattern is recorded. After recording the pattern, a predetermined transport amount is transported, and further the pattern is recorded.

Next, in step S9, the density is detected by the detection means in order to detect the degree of pattern overlap. The detected value is stored in the RAM 13 for each changed transport amount.
Next, in step S10, the recording medium is fed to a position where a new test pattern can be recorded.
Next, in step S11, it is determined whether or not the entire survey range has been completed. If not, the process proceeds to step S8, and the second test pattern is recorded using the transport amount at the next stage. If completed, the process proceeds to step S12.

Next, in step S12, an approximate curve is calculated based on the density value of each pattern of the second test pattern to obtain an extreme value. The amount of deviation from the theoretical transport amount at which the density is minimum is obtained. For the amount of deviation, the closest value recorded in the second test pattern is used as the correction value. By using this correction value to correct and carry the carry amount, the carry can be close to the theoretical value.
In step S13, the correction value is set, and the first test pattern, the second test pattern, and the correction value are recorded for confirmation. The process ends.

  Furthermore, the user may confirm a test pattern for confirmation, and manually input a correction value for the conveyance amount from the operation panel according to his / her preference, and correct the conveyance amount based on the input. A test pattern is printed with a shift amount in a minimum resolution unit that can control recording in the sub-scanning direction, a final set value is also determined in the minimum resolution unit, and a test pattern for confirmation is printed. If the user wants to correct the test pattern by looking at it, the user may be able to input a recorrection value from the operation panel and use the recorrection value as a final set value.

FIG. 10 is a flowchart for explaining the operation of the second example of test pattern recording and detection. The control means 11 controls the operation according to the program.
First, in step S20, an initial value for recording the first test pattern is set. Based on the range to be investigated with respect to the theoretical transport amount, the number of patterns to be recorded by the first test pattern and the used nozzles are set. Depending on the width of the recording paper, the test pattern that can be recorded on one line is limited, and it is necessary to record over a plurality of lines.

Next, in step S21, the first test pattern is recorded. This includes basic patterns and evaluation lines.
Next, in step S22, the density of the first test pattern is measured by the detection means for each pattern, and the result is stored in the RAM 13.

Next, in step S23, the recording medium is fed to a position where a new test pattern can be recorded.
Next, in step S24, it is confirmed whether all patterns have been recorded and detected. This is because the first test pattern is recorded in a plurality of lines depending on circumstances. If all are completed, the process proceeds to step S25, and if not completed, the process proceeds to step S20.

Next, in step S25, an approximate curve is calculated based on the density data stored in the RAM 13, an extreme value is obtained, and an amount of deviation from the theoretical transport amount at which the density is minimum is calculated. The closest recorded test pattern is the correction value. By using this correction value to correct and carry the carry amount, the carry can be close to the theoretical value.
Next, in step S26, this correction value is set, and the first test pattern and the correction value are recorded for confirmation. The process ends.

  Here, between step S22 and step S23, an approximate curve is calculated based on the detected density data to obtain an extreme value. Then, the process moves to the next step in order to record only the test patterns before and after the obtained extreme value. Here, it is considered that the adjustment amount other than the adjustment amount for newly recording and detecting the test pattern is completed. In addition, what is regarded as being processed is not used in the calculation. When the process proceeds to step S20, an adjustment amount for recording the first test pattern before and after the obtained extreme value is set and recorded in step S21. Next, the density of the recorded test pattern is detected and stored. At least the test patterns before and after the correction value obtained are recorded, and the density is detected. Further, a test pattern separated by one step may be recorded to detect the density. The more data, the higher the accuracy of the subsequent approximate curve calculation. By doing so, the number of test patterns printed and the number of detections by the sensor is reduced, and a correction value can be obtained in a short time.

  In addition, even if the user confirms the test pattern for confirmation and manually inputs a correction value for the conveyance amount from the operation panel according to his / her preference, the conveyance amount is corrected based on the input. good. A test pattern is printed with a shift amount in a minimum resolution unit that can control recording in the sub-scanning direction, a final set value is also determined in the minimum resolution unit, and a test pattern for confirmation is printed. If the user sees this test pattern and wishes to correct it, the user may be able to input a recorrection value from the operation panel and set the recorrection value as a final set value.

  Even if the measured value has the lowest concentration, it does not necessarily become an extreme value. This is because the measurement includes noise. Therefore, it is necessary to determine the tendency of the measured value from the acquired entire value by calculating the approximate curve. The correction value is finally selected from the transport amount of the recorded test pattern conditions. This is because it is necessary to select from those that can be actually controlled. This is because there is a case where control for realizing the minimum value obtained by calculation cannot be performed. In normal printing, by using the transport amount of the most overlapped dot obtained here, it is possible to transport with an amount that can be actually controlled, and printing with the highest image quality can be achieved.

FIG. 11 is a flowchart for explaining the operation of the third example of test pattern recording and detection. The control means 11 controls the operation according to the program.
First, in step S30, an initial value for recording the first test pattern is set. Based on the range to be investigated with respect to the theoretical transport amount, the number of patterns to be recorded by the first test pattern and the used nozzles are set. Depending on the width of the recording paper, the test pattern that can be recorded on one line is limited, and it is necessary to record over a plurality of lines.

Next, in step S31, the first test pattern is recorded. This includes basic patterns and evaluation lines.
Next, in step S32, the density of the first test pattern is measured by the detection means for each pattern, and the result is stored in the RAM 13.

Next, in step S33, the recording medium is fed to a position where a new test pattern can be recorded. Here, when the second test pattern is recorded next to the first test pattern without feeding, this step S33 is unnecessary.
Next, in step S34, it is confirmed whether all patterns have been recorded and detected. This is because the first test pattern is recorded in a plurality of lines depending on circumstances. If all are completed, the process proceeds to step S35, and if not completed, the process proceeds to step S30.

  Next, in step S35, an approximate curve is calculated based on the density data stored in the RAM 13, an extreme value is obtained, and the amount of deviation from the theoretical transport amount at which the density is minimum is calculated. The closest test pattern recorded is used as the value of the deviation of the transport amount at the center of the detailed detection pattern. Alternatively, a value closest to the shift amount of the controllable conveyance amount of the recording medium may be set as the value of the shift amount. Using this value, the recording range of the second test pattern for calculating the value of the deviation amount with respect to the unit transport amount during the detailed test is calculated.

  Next, in step S36, an initial value for recording the second test pattern is set. The second test pattern including the number of patterns necessary for recording the second test pattern, the used nozzles, and the deviation amount with respect to the unit transport amount based on the range to be investigated with respect to the theoretical transport amount Set the value such as the transport amount when recording. Depending on the width of the recording medium, the test pattern that can be recorded in one line is limited, and it is necessary to record over a plurality of lines. Further, since it is necessary to record the second test pattern for each resolution to be tested, it is necessary to set a value for each resolution. For example, in FIG. 8, it is necessary to set test pattern A1, test pattern A2, test pattern B, and test pattern C, respectively. The first test pattern and the second test pattern may have the same shape. In addition, the cycle of the recording and non-recording portions may be shorter in the second task and pattern than in the first test pattern.

Next, in step S37, the second test pattern is recorded. This includes basic patterns and evaluation lines.
Next, in step S38, the density of the second test pattern is measured by the detection means for each pattern, and the result is stored in the RAM 13.

Next, in step S39, the recording medium is fed to a position where a new test pattern can be recorded.
Next, in step S40, it is confirmed whether all the second patterns have been recorded and detected.
If all are completed, the process proceeds to step S41, and if not completed, the process proceeds to step S36 and the remaining test patterns are recorded.

In step S41, an approximate curve is calculated based on the detected density data, an extreme value is obtained, and a deviation amount from the unit transport amount at the theoretical test at which the density is minimum is calculated. Then, the value of the deviation amount that is closest to the obtained extreme value and can be actually controlled for conveyance is calculated. That is, an approximate curve is obtained by calculation, an extreme value is obtained, the closest value recorded in the test pattern is selected and stored in the RAM 13 as a correction value. Based on this value, the conveyance amount is corrected and calculated, and conveyance control of the recording medium is performed. By carrying out like this, conveyance near a theoretical value can be performed.
Next, in step S26, this correction value is set, and the first test pattern and the correction value are recorded for confirmation. Thereafter, the process ends.

  The present invention can be used for an ink jet printer.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Rail 3 Carriage 4 Cap 5 Endless belt 6 Motor 7 Platen 8 After guide 9 Conveyance roller 11 Control means 12 ROM
13 RAM
16 Recording means 17 Linear encoder 18 R detection means 19 G detection means 20 B detection means

Claims (3)

A recording head in which the plurality of nozzles for forming dots by ejecting ink onto the recording medium are arranged at equal intervals in the conveyance direction of the recording medium;
Conveying means for conveying the recording medium;
A carriage mounted with the recording head and reciprocally scanning the recording head in a direction intersecting the transport direction of the recording medium;
A platen that is disposed at a position facing the recording head that performs the reciprocating scanning along the scanning direction of the recording head, and supports the recording medium;
A sensor mounted on the carriage for detecting the density of an image recorded on the recording medium;
A test pattern composed of a plurality of the dots is recorded on the recording medium that is planarly supported on the platen, the density of the test pattern is detected by the sensor, and the recording medium is transported based on the detected density In a recording apparatus comprising: a control unit that calculates a correction amount with respect to the amount, and controls conveyance of the recording medium based on the correction amount obtained by the calculation.
Correction amount storage means for storing the correction amount with respect to the transport amount;
The control means includes
While moving the carriage, the nozzle to be used is changed in accordance with the recording position on the recording medium, and a dot array to be evaluated which is composed of a first predetermined number of the dots and forms a part of the test pattern is recorded. And
Carrying a predetermined transport amount without correcting the recording medium by the correction amount,
While moving the carriage, the ink is ejected onto the recording medium by the nozzle at a position away from the nozzle serving as a reference among the nozzles that record the evaluated dot row by the predetermined transport amount, An evaluation dot row composed of a second predetermined number of the dots along the evaluated dot row and constituting a part of the test pattern is recorded,
The sensor detects the density of the test pattern consisting of the evaluated dot row and the evaluation dot row according to the recording position,
Based on the detection result, the recording position where the degree of overlap between the evaluated dot row and the evaluation dot row is maximized is calculated, and the nozzle that records the recording position obtained by the calculation and the reference nozzle A recording apparatus, wherein the correction amount is calculated from a distance and the predetermined transport amount, and the correction amount obtained by the calculation is stored in the correction amount storage means. The control means further includes
A second to-be-evaluated device that is different from the to-be-evaluated dot row composed of the first predetermined number of the dots by changing the nozzle to be used according to the recording position on the recording medium while moving the carriage. Record the dot sequence,
Carrying the second carry amount by adding the distance obtained by dividing the distance between the nozzles by N (N is a positive integer) to the predetermined carry amount without correcting the recording medium by the correction amount;
While moving the carriage, the ink on the recording medium is ejected by the nozzle that is separated from the nozzle serving as the second reference among the nozzles that record the second evaluated dot row by the second transport amount. And recording a second evaluation dot row different from the evaluation dot row composed of the second predetermined number of the dots along the second evaluated dot row,
The sensor detects the density of the test pattern composed of the second evaluated dot row and the second evaluation dot row according to the recording position,
Based on the detection result, the recording position where the overlapping degree of the second evaluated dot row and the second evaluation dot row is maximized is calculated, and the nozzle for recording the recording position obtained by the calculation and the nozzle The correction amount is calculated from a distance from a nozzle serving as a second reference and the second transport amount, and the correction amount obtained by the calculation is stored in the correction amount storage means. The recording apparatus according to 1.   The control means determines the recording position for recording the second evaluated dot row based on the correction amount obtained based on the density of the test pattern including the evaluated dot row and the evaluation dot row. The recording apparatus according to claim 2.

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