JP4857663B2 - Transport error inspection method, transport error correction value determination method, printing method, printing system, test sheet manufacturing method, and test sheet - Google Patents

Description

  The present invention relates to a test sheet manufacturing method, a correction value determination method, a printing method, a printing system, and a test sheet.

  In a printing apparatus such as an ink jet printer, a dot forming process that forms ink on a medium (paper, cloth, OHP paper, etc.) by ejecting ink from a moving head and a conveyance process that conveys the medium in the conveyance direction alternately The print image is printed on the medium repeatedly. Such a printing apparatus is provided with a conveyance roller for performing a conveyance process. When the transport roller rotates with a predetermined rotation amount, the medium is transported with a predetermined transport amount.

However, in the transport process, even if the transport roller is rotated by a rotation amount corresponding to the target transport amount (target transport amount), the medium may not be transported by the target transport amount. Therefore, in order to reduce such a transport error, the target transport amount is corrected. Furthermore, since the conveyance error varies depending on the location of the circumferential surface of the conveyance roller used during the conveyance process, a correction value is changed according to the circumferential surface used (see Patent Document 1).
JP 2003-237154 A

When determining the correction value of the carry amount, first, a certain pattern is formed, and after the medium is carried by the carry amount, another pattern is formed. Then, based on the state of the boundary between the two patterns, an interval between the two patterns is determined, and a correction value is determined.
However, when the conveyance amount to be corrected is longer than the length of the nozzle row in the conveyance direction, the two patterns are formed apart from each other, and a boundary cannot be formed between the two patterns. It becomes difficult to determine the interval.

  Accordingly, an object of the present invention is to enable determination of a correction value for correcting the carry amount even when the carry amount to be corrected is longer than the length of the nozzle row in the carry direction. To do.

The main invention for achieving the above object is that a medium to be printed is transported by a transport roller, and ink is ejected from a nozzle row having a plurality of nozzles in the transport direction and moving in a direction crossing the transport direction. A method of printing a pattern and inspecting a transport error by the transport roller in which the length of the peripheral surface of one rotation is longer than the length of the nozzle row in the transport direction, and the nozzle at an arbitrary rotational position of the transport roller A first pattern is formed on the medium by ejecting ink from the nozzles on the upstream side in the transport direction of the row, and the nozzles on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated less than one rotation from the rotation position A second pattern is formed so as to form a boundary with the first pattern of the medium by ejecting ink from the nozzle, and from a nozzle on the upstream side in the transport direction of the nozzle row A third pattern is formed on the medium by ink ejection, and the third pattern is formed by a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by about one rotation from a rotation position for forming the first pattern. By forming a fourth pattern on the medium so as to form a boundary, a transport error detection pattern including the first, second, third, and fourth patterns is formed, and the transport is performed. A rotation angle from a rotation position at which the roller forms the first pattern to a rotation position at which the second pattern is formed and a rotation angle from the rotation position at which the first pattern is formed to the rotation position at which the fourth pattern is formed. A plurality of different conveyance error detection patterns are formed, and the first pattern, the second pattern, and the third pattern in the plurality of inspection patterns are formed. A method of inspecting a transport error, characterized in that the state of the the turn fourth pattern boundary checking the conveyance error of the medium by the conveying roller.
The first, second, third, and fourth patterns are “pattern A”, “inclined pattern B1” that is an upper pattern of pattern B, and lower pattern of pattern B, respectively, in an embodiment that will be described later. It corresponds to “inclination pattern B3” and “pattern C”.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

=== Summary of disclosure ===
At least the following matters will become clear from the description of the present specification and the accompanying drawings.

Transport the medium to a predetermined position in the transport direction,
Forming a first pattern on the medium by nozzles on the upstream side in the transport direction of a nozzle row composed of a plurality of nozzles arranged at predetermined intervals;
After the formation of the first pattern, the medium is transported in the transport direction by a target transport amount that is shorter than the length of the nozzle row in the transport direction,
A second pattern that forms a boundary with the first pattern is formed on the medium by nozzles on the downstream side in the transport direction of the nozzle row, and a third pattern is formed on the medium by nozzles on the upstream side in the transport direction of the nozzle row. And
After the formation of the second pattern, the transport amount of the medium after the formation of the first pattern is longer than the length of the nozzle row in the transport direction so as to be longer than the length of the nozzle row in the transport direction. Transport the medium in the transport direction with a short target transport amount,
Forming a fourth pattern on the medium that forms a boundary with the third pattern by the nozzles on the downstream side in the transport direction of the nozzle row;
A test sheet manufacturing method for correcting a target transport amount.
According to such a test sheet manufacturing method, it is possible to create a test sheet that can detect a transport error when transported according to a target transport amount that is longer than the length of the nozzle row in the transport direction.

  Further, when transporting the medium, it is preferable that the transport roller is rotated, and the length of the nozzle row in the transport direction is shorter than the peripheral surface of the transport roller. This is particularly effective in such a case.

  Further, when transporting the medium, the transport roller is rotated, and the transport amount of the medium performed from the formation of the first pattern to the formation of the third pattern is determined by the transport roller. It is desirable to correspond to approximately one rotation. Thereby, it is possible to create a test sheet for correcting the target carry amount corresponding to one rotation of the carry roller. Note that the transport error that occurs when transporting at a target transport amount corresponding to one rotation of the transport roller is constant regardless of the rotational position of the transport roller.

  In addition, it is preferable that the amount of the medium transport performed from the formation of the first pattern to the formation of the second pattern corresponds to approximately a half rotation of the transport roller. In addition, it is desirable that the nozzle that forms the first pattern and the nozzle that forms the third pattern are common, and the nozzle that forms the second pattern and the nozzle that forms the fourth pattern are common. . Thereby, the boundary between the first pattern and the second pattern and the boundary between the third pattern and the fourth pattern can be formed in the same manner.

  The boundary is formed in a direction that intersects the moving direction of the nozzle row. This makes it possible to create a test sheet that makes it easy to determine the boundary state. In addition, it is preferable that the direction of the boundary between the first pattern and the second pattern intersects the direction of the boundary between the third pattern and the fourth pattern. Thereby, even if there is a difference in the ink ejection speed of the nozzles, it is possible to create a test sheet suitable for correcting the conveyance error.

Transport the medium to a predetermined position in the transport direction,
Forming a first pattern on the medium by nozzles on the upstream side in the transport direction of a nozzle row composed of a plurality of nozzles arranged at predetermined intervals;
After the formation of the first pattern, the medium is transported in the transport direction by a target transport amount that is shorter than the length of the nozzle row in the transport direction,
A second pattern that forms a boundary with the first pattern is formed on the medium by nozzles on the downstream side in the transport direction of the nozzle row, and a third pattern is formed on the medium by nozzles on the upstream side in the transport direction of the nozzle row. And
After the formation of the second pattern, the transport amount of the medium after the formation of the first pattern is longer than the length of the nozzle row in the transport direction so as to be longer than the length of the nozzle row in the transport direction. Transport the medium in the transport direction with a short target transport amount,
Forming a fourth pattern on the medium that forms a boundary with the third pattern by a nozzle on the downstream side in the transport direction of the nozzle row;
A correction value for the target transport amount is determined based on a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern. Method.
According to such a correction value determination method, it is possible to determine a correction value for correcting a target transport amount that is longer than the length of the nozzle row in the transport direction.

  In addition, a plurality of correction patterns including the first pattern to the fourth pattern are formed, and the first correction is performed based on a boundary state between the first pattern and the second pattern among the plurality of correction patterns. A second correction pattern is selected based on a boundary state between the first pattern and the second pattern from the plurality of correction patterns, and the first correction pattern It is desirable to determine the correction value based on the second correction pattern. Thereby, it is possible to determine a correction value for correcting a target transport amount that is longer than the length of the nozzle row in the transport direction.

  It is preferable that a value between a correction value corresponding to the first correction pattern and a correction value corresponding to the second correction pattern is determined as the correction value. Further, the plurality of correction patterns are arranged along a predetermined direction, and when the first correction pattern is selected, the plurality of correction patterns are inspected in order from one direction of the predetermined direction. When selecting the second correction pattern, it is preferable to inspect a plurality of the correction patterns in order from the reverse direction. Thereby, it is possible to determine a correction value capable of accurately correcting the conveyance error.

Transport the medium to a predetermined position in the transport direction,
Forming a first pattern on the medium by nozzles on the upstream side in the transport direction of a nozzle row composed of a plurality of nozzles arranged at predetermined intervals;
After the formation of the first pattern, the medium is transported in the transport direction by a target transport amount that is shorter than the length of the nozzle row in the transport direction,
A second pattern that forms a boundary with the first pattern is formed on the medium by nozzles on the downstream side in the transport direction of the nozzle row, and a third pattern is formed on the medium by nozzles on the upstream side in the transport direction of the nozzle row. And
After the formation of the second pattern, the transport amount of the medium after the formation of the first pattern is longer than the length of the nozzle row in the transport direction so as to be longer than the length of the nozzle row in the transport direction. Transport the medium in the transport direction with a short target transport amount,
Forming a fourth pattern on the medium that forms a boundary with the third pattern by a nozzle on the downstream side in the transport direction of the nozzle row;
Based on the boundary between the first pattern and the second pattern and the boundary between the third pattern and the fourth pattern, a correction value for the target transport amount is determined,
A printing method, wherein when the medium is conveyed for printing, a target conveyance amount is corrected, and the medium is conveyed according to the corrected target conveyance amount.
According to such a printing method, a high quality print image can be obtained.

A transport unit for transporting the medium to a predetermined position in the transport direction;
A controller that transports the medium to the transport unit according to a target transport amount, and that ejects ink from a nozzle row that includes a plurality of nozzles arranged at predetermined intervals;
A printing system comprising:
The controller is
A first pattern is formed on the medium by nozzles on the upstream side in the conveyance direction of the nozzle row,
After the formation of the first pattern, the medium is transported in the transport direction by a target transport amount that is shorter than the length of the nozzle row in the transport direction,
A second pattern that forms a boundary with the first pattern is formed on the medium by nozzles on the downstream side in the transport direction of the nozzle row, and a third pattern is formed on the medium by nozzles on the upstream side in the transport direction of the nozzle row. And
After the formation of the second pattern, the transport amount of the medium after the formation of the first pattern is longer than the length of the nozzle row in the transport direction so as to be longer than the length of the nozzle row in the transport direction. Transport the medium in the transport direction with a short target transport amount,
Forming a fourth pattern on the medium that forms a boundary with the third pattern by the nozzles on the downstream side in the transport direction of the nozzle row;
A printing system characterized by that.
According to such a printing system, it is possible to correct a target transport amount that is longer than the length of the nozzle row in the transport direction.

A first pattern formed on a medium by nozzles on the upstream side in the transport direction of a nozzle row composed of a plurality of nozzles arranged at a predetermined interval;
After the first pattern is formed, the medium is transported in the transport direction by a target transport amount that is shorter than the length of the nozzle array in the transport direction, and is then placed on the medium by a nozzle on the downstream side of the nozzle array in the transport direction. A second pattern formed and forming a boundary with the first pattern;
A third pattern formed by nozzles on the upstream side in the transport direction of the nozzle row when forming the second pattern;
The transport amount of the medium after forming the first pattern after the formation of the second pattern is longer than the length of the nozzle row in the transport direction so as to be longer than the length of the nozzle row in the transport direction. A fourth pattern formed on the medium by a nozzle on the downstream side in the transport direction of the nozzle row and forming a boundary with the third pattern, after transporting the medium in the transport direction with a short target transport amount;
A test sheet characterized by comprising:

  According to such a test sheet, it is possible to detect a transport error when transported according to a target transport amount that is longer than the length of the nozzle row in the transport direction.

=== Configuration of Printing System ===
Next, an embodiment of a printing system will be described with reference to the drawings. However, the description of the following embodiments includes embodiments relating to a computer program and a recording medium on which the computer program is recorded.

  FIG. 1 is an explanatory diagram showing an external configuration of a printing system. The printing system 100 includes a printer 1, a computer 110, a display device 120, an input device 130, and a recording / reproducing device 140. The printer 1 is a printing apparatus that prints an image on a medium such as paper, cloth, or film. The computer 110 is communicably connected to the printer 1 and outputs print data corresponding to the image to be printed to the printer 1 in order to cause the printer 1 to print an image.

  A printer driver is installed in the computer 110. The printer driver is a program for causing the display device 120 to display a user interface and converting image data output from the application program into print data. This printer driver is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM. Alternatively, the printer driver can be downloaded to the computer 110 via the Internet. In addition, this program is comprised from the code | cord | chord for implement | achieving various functions.

  The “printing apparatus” means an apparatus that prints an image on a medium, and corresponds to the printer 1, for example. The “printing control device” means a device that controls the printing device, for example, a computer in which a printer driver is installed. The “printing system” means a system including at least a printing apparatus and a printing control apparatus.

=== Description of the printer ===
<Inkjet printer configuration>
FIG. 2 is a block diagram of the overall configuration of the printer 1. FIG. 3A is a schematic diagram of the overall configuration of the printer 1. FIG. 3B is a cross-sectional view of the overall configuration of the printer 1. Hereinafter, the basic configuration of the printer of this embodiment will be described.

  The printer 1 of this embodiment includes a transport unit 20, a carriage unit 30, a head unit 40, a detector group 50, and a controller 60. The printer 1 that has received print data from the computer 110, which is an external device, controls each unit (the conveyance unit 20, the carriage unit 30, and the head unit 40) by the controller 60. The controller 60 controls each unit based on the print data received from the computer 110 and prints an image on paper. The situation in the printer 1 is monitored by a detector group 50, and the detector group 50 outputs a detection result to the controller 60. The controller 60 controls each unit based on the detection result output from the detector group 50.

  The transport unit 20 is for transporting a medium (for example, paper S) in a predetermined direction (hereinafter referred to as a transport direction). The transport unit 20 includes a paper feed roller 21, a transport motor 22 (also referred to as a PF motor), a transport roller 23, a platen 24, and a paper discharge roller 25. The paper feed roller 21 is a roller for feeding the paper inserted into the paper insertion slot into the printer. The transport roller 23 is a roller that transports the paper S fed by the paper feed roller 21 to a printable area, and is driven by the transport motor 22. The platen 24 supports the paper S being printed. The paper discharge roller 25 is a roller for discharging the paper S to the outside of the printer, and is provided on the downstream side in the transport direction with respect to the printable area.

  The carriage unit 30 is for moving (also referred to as “scanning”) the head in a predetermined direction (hereinafter referred to as a moving direction). The carriage unit 30 includes a carriage 31 and a carriage motor 32 (also referred to as a CR motor). The carriage 31 can reciprocate in the moving direction and is driven by a carriage motor 32. Further, the carriage 31 detachably holds an ink cartridge that stores ink.

  The head unit 40 is for ejecting ink onto paper. The head unit 40 includes a head 41 having a plurality of nozzles. Since the head 41 is provided on the carriage 31, when the carriage 31 moves in the movement direction, the head 41 also moves in the movement direction. Then, by intermittently ejecting ink while the head 41 is moving in the moving direction, dot lines (raster lines) along the moving direction are formed on the paper.

  The detector group 50 includes a linear encoder 51, a rotary encoder 52, a paper detection sensor 53, an optical sensor 54, and the like. The linear encoder 51 detects the position of the carriage 31 in the moving direction. The rotary encoder 52 detects the amount of rotation of the transport roller 23. The paper detection sensor 53 detects the position of the leading edge of the paper being fed. The optical sensor 54 detects the presence or absence of paper by a light emitting unit and a light receiving unit attached to the carriage 31. The optical sensor 54 can detect the position of the edge of the paper while being moved by the carriage 31 to detect the width of the paper. The optical sensor 54 also detects the leading end (the end on the downstream side in the transport direction, also referred to as the upper end) and the rear end (the end on the upstream side in the transport direction, also referred to as the lower end) depending on the situation. it can.

  The controller 60 is a control unit (control unit) for controlling the printer. The controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64. The interface unit 61 transmits and receives data between the computer 110 which is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and includes storage elements such as a RAM and an EEPROM. The CPU 62 controls each unit via the unit control circuit 64 in accordance with a program stored in the memory 63. For example, the CPU 62 commands the target transport amount to the unit control circuit 64, and the unit control circuit 64 drives the transport motor 22 of the transport unit 20 based on this command.

<About printing operation>
FIG. 4 is a flowchart of processing during printing. Each process described below is executed by the controller 60 controlling each unit in accordance with a program stored in the memory 63. This program has a code for executing each process.

  Print command reception (S001): First, the controller 60 receives a print command from the computer 110 via the interface unit 61. This print command is included in the header of print data transmitted from the computer 110. Then, the controller 60 analyzes the contents of various commands included in the received print data, and performs the following paper feed processing / conveyance processing / dot formation processing using each unit.

  Paper Feed Process (S002): The paper feed process is a process for supplying paper to be printed into the printer and positioning the paper at a print start position (also referred to as a cue position). The controller 60 rotates the paper feed roller 21 and sends the paper to be printed to the transport roller 23. Subsequently, the controller 60 rotates the transport roller 23 to position the paper fed from the paper feed roller 21 at the print start position. When the paper is positioned at the print start position, at least some of the nozzles of the head 41 are opposed to the paper.

  Dot Forming Process (S003): The dot forming process is a process for forming dots on paper by intermittently ejecting ink from a head that moves in the moving direction. The controller 60 drives the carriage motor 32 to move the carriage 31 in the movement direction. Then, the controller 60 ejects ink from the head based on the print data while the carriage 31 is moving. When ink droplets ejected from the head 41 land on the paper, dots are formed on the paper. Since ink is intermittently ejected from the moving head 41, a dot row (raster line) composed of a plurality of dots along the moving direction is formed on the paper. This dot formation process is also referred to as “pass”. The n-th dot formation process is also referred to as “pass n”.

  Conveyance process (S004): The conveyance process is a process of moving the paper relative to the head in the conveyance direction. The controller 60 drives the carry motor and rotates the carry roller to carry the paper in the carrying direction. By this carrying process, the head 41 can form dots at positions different from the positions of the dots formed by the previous dot formation process.

  Paper discharge determination (S005): The controller 60 determines whether or not to discharge the paper being printed. If data to be printed remains on the paper being printed, no paper is discharged. Then, the controller 60 alternately repeats the dot formation process and the conveyance process until there is no more data to be printed, and gradually prints an image composed of dots on paper.

  Paper Discharge Process (S006): When there is no more data to be printed on the paper being printed, the controller 60 discharges the paper by rotating the paper discharge roller. The determination of whether or not to discharge paper may be based on a paper discharge command included in the print data.

  Print end determination (S007): Next, the controller 60 determines whether or not to continue printing. If printing is to be performed on the next paper, printing is continued and the paper feeding process for the next paper is started. If printing is not performed on the next paper, the printing operation is terminated.

=== Conveyance error during transport processing and its correction ===
<Conveying paper>
FIG. 5 is an explanatory diagram of the configuration of the transport unit 20. As shown in the drawing, the moving direction of the ink jet head 41 is the left-right direction in the figure, and the paper S is transported from the upstream side to the downstream direction (conveyance direction) intersecting therewith.
The transport unit 20 drives the transport motor 22 by a predetermined drive amount based on a transport command from the controller 60. The conveyance motor 22 generates a driving force in the rotation direction according to the commanded driving amount. The transport motor 22 rotates the transport roller 23 using this driving force. That is, when the transport motor 22 generates a predetermined drive amount, the transport roller 23 rotates by a predetermined rotation amount. When the transport roller 23 rotates with a predetermined rotation amount, the paper is transported with a predetermined transport amount.
The carry amount of the paper is determined according to the rotation amount of the carry roller 23. In the present embodiment, when the transport roller 23 makes one rotation, the paper is transported by 1.25 inches (that is, the peripheral length of the transport roller 23 is 1.25 inches). For this reason, when the transport roller 23 is rotated halfway, the paper is transported by 0.625 inch.
Therefore, if the rotation amount of the conveyance roller 23 can be detected, the conveyance amount of the paper can also be detected. Therefore, a rotary encoder 52 is provided to detect the rotation amount of the transport roller 23.

The rotary encoder 52 includes a scale 521 and a detection unit 522. The scale 521 has a large number of slits provided at predetermined intervals. The scale 521 is provided on the transport roller 23. That is, the scale 521 rotates together when the transport roller 23 rotates. When the transport roller 23 rotates, the slits of the scale 521 sequentially pass through the detection unit 522. The detection unit 522 is provided to face the scale 521 and is fixed to the printer main body side. The rotary encoder 52 outputs a pulse signal every time the slit 521 passes through the detection unit 522. Since the slits 521 sequentially pass through the detection unit 522 according to the rotation amount of the conveyance roller 23, the rotation amount of the conveyance roller 23 is detected based on the output of the rotary encoder 52. For example, when the conveyance amount is 1.25 inches When transporting paper, the controller 60 drives the transport motor 22 until the rotary encoder 52 detects that the transport roller 23 has made one rotation. As described above, the controller 60 drives the carry motor 22 until the rotary encoder 52 detects that the rotation amount is in accordance with the target carry amount (target carry amount), and sets the paper to the target carry amount. Transport.

<About transport error>
Incidentally, the rotary encoder 52 directly detects the rotation amount of the transport roller 23, and strictly speaking, does not detect the transport amount of the paper S. For this reason, when the rotation amount of the transport roller 23 and the transport amount of the paper S do not match, the rotary encoder 52 cannot accurately detect the transport amount of the paper S, and a transport error (detection error) occurs. There are two types of transport errors: DC component transport errors and AC component transport errors.

  The DC component transport error is a certain amount of transport error that occurs when the transport roller rotates once. The DC component transport error is considered to be caused by the circumference of the transport roller 23 being different for each printer due to a manufacturing error or the like. That is, the DC component transport error is a transport error that occurs because the designed peripheral length of the transport roller 23 is different from the actual peripheral length of the transport roller 23. The DC component transport error is constant regardless of the start position when the transport roller makes one rotation.

  The AC component transport error is a transport error according to the location of the peripheral surface of the transport roller used during transport. The AC component transport error varies depending on the location of the peripheral surface of the transport roller used during transport. That is, the AC component transport error varies depending on the rotation position of the transport roller at the start of transport and the transport amount.

  FIG. 6 is a graph for explaining the AC component transport error. The horizontal axis represents the rotation amount of the transport roller 23 from the reference rotation position. The vertical axis represents the cumulative conveyance error. If this graph is differentiated, a transport error that occurs when the transport roller is transporting at the rotational position can be derived. Here, the cumulative transport error at the reference position is zero, and the DC component transport error is also zero.

  When the transport roller 23 rotates 1/4 from the reference position, a transport error of δ_90 occurs, and the paper is transported at 1.25 / 4 inch + δ_90. However, if the transport roller 23 is further rotated by 1/4, a transport error of -δ_90 occurs, and the paper is transported at 1.25 / 4 inch -δ_90.

  There are three possible causes for the AC component transport error, for example.

  First, the influence of the shape of the transport roller can be considered. For example, when the conveyance roller is elliptical or egg-shaped, the distance to the rotation center differs depending on the location of the circumferential surface of the conveyance roller. When the medium is transported at a portion where the distance to the rotation center is long, the transport amount with respect to the rotation amount of the transport roller increases. On the other hand, when the medium is transported at a portion where the distance to the rotation center is short, the transport amount with respect to the rotation amount of the transport roller is reduced.

  Secondly, the eccentricity of the rotation shaft of the transport roller can be considered. Also in this case, the length to the center of rotation differs depending on the location of the peripheral surface of the transport roller. For this reason, even if the rotation amount of the conveyance roller is the same, the conveyance amount varies depending on the location of the circumferential surface of the conveyance roller.

  Thirdly, a discrepancy between the rotation axis of the transport roller and the center of the scale 521 of the rotary encoder 52 can be considered. In this case, the scale 521 rotates eccentrically. As a result, the amount of rotation of the transport roller 23 with respect to the detected pulse signal differs depending on the location of the scale 521 detected by the detection unit 522. For example, when the detected location of the scale 521 is away from the rotation axis of the conveyance roller 23, the rotation amount of the conveyance roller 23 with respect to the detected pulse signal decreases, and the conveyance amount decreases. On the other hand, when the detected location of the scale 521 is close to the rotation axis of the conveyance roller 23, the rotation amount of the conveyance roller 23 with respect to the detected pulse signal increases, and thus the conveyance amount increases.

  Due to the above causes, the AC component transport error is substantially a sine curve as shown in FIG.

<About correction of transport error>
FIG. 7 is a flowchart of correction value setting processing for correcting a transport error. These processes are performed in an inspection process in the manufacturing factory when the printer is manufactured. At this time, the printer to be inspected is connected to an inspection computer in the factory.

First, the printer prints a test sheet for setting correction values (S101). A plurality of correction patterns are formed on this test sheet. This correction pattern is also called a “patch pattern”. Each correction pattern is associated with a specific correction value and has a different shape. This test sheet will be described later.
Next, the inspector inspects the test sheet and selects a correction pattern having an optimum shape from among a plurality of correction patterns in the test sheet (S102). The inspector inputs the selected correction pattern number to a computer connected to the printer. The computer determines a correction value based on the selected correction pattern number (S103), and records the correction value in the memory of the printer (S104).
Thereby, the correction value suitable for each printer is recorded in the memory of each printer for each printer manufactured in the manufacturing factory. The printer having the correction value stored in the memory is packed and shipped.

  When printing is performed by the user who purchased the printer, the controller 60 reads the correction value from the memory, corrects the target carry amount based on the correction value, and carries the carry based on the corrected target carry amount. Process. As a result, the paper is transported according to the target transport amount, so that the quality of the printed image is improved.

=== Reference Example ===
FIG. 8 is an explanatory diagram of printing a test sheet of a reference example. In this reference example, it is assumed that the length of the head in the transport direction is 1.25 inches, which is the same as the length of the peripheral surface of the transport roller 23.
The test sheet of this reference example is for acquiring a correction value for the target transport amount F. Here, the target transport amount F is 1.25 inches, which is the same as the length of the peripheral surface of the transport roller 23. Therefore, this test sheet also detects a transport error (DC component transport error) that occurs when the transport roller 23 makes one rotation.

  The six rectangles on the left side in the drawing indicate the position of the head with respect to the paper during pass 1 to pass 6. The number in the rectangle indicating the position of the head indicates the pass number. In the drawing, the head is depicted as moving, but actually, the position of the head relative to the paper changes as the paper is conveyed. Between pass 1 and pass 2, a transport process of the target transport amount F + 2C is performed. However, when there is a transport error, the paper is not transported according to the target transport amount in the drawing.

  On the right side of the figure, five correction patterns P1 to P5 formed on the test sheet are drawn. Each correction pattern has two block patterns. In one pass, the upper block pattern is formed by the upstream nozzles in the transport direction of the head, and in the next pass, the lower block pattern is formed by the downstream nozzles in the transport direction of the head. For each correction pattern, the target transport amount of the transport process performed from when the upper block pattern is formed to when the lower block pattern is formed differs. For example, in the correction pattern P1, the conveyance process of the target conveyance amount F + 2C is performed while two block patterns are formed, and in the correction pattern P2, the conveyance process of the target conveyance amount F + C is performed. For this reason, each correction pattern has a different interval between two block patterns.

  When two block patterns are formed apart from each other, white stripes are generated at the boundary between the two block patterns. On the other hand, when two block patterns are overlapped, black streaks are generated between the two block patterns.

  If the paper is transported according to the target transport amount, no white or black streaks should occur in the correction pattern P3. However, according to the test sheet in the figure, when the paper is transported with the target transport amount F, the paper is transported shorter than the target transport amount F due to a transport error, and thus black streaks are generated in the correction pattern P3.

When inspecting the test sheet, the inspector pays attention to the boundary between the two block patterns. Then, the inspector selects the correction pattern P2 having neither white stripes nor black stripes as an optimal correction pattern. As a result, “+1” is recorded as the correction value in the memory of the printer.
When printing is performed under the user, the controller 60 corrects the target carry amount to F + C based on the correction value “+1” recorded in the memory when carrying out the carry process with the target carry amount F. If the carrying process is performed with the corrected target carry amount F + C, the paper is carried by the carry amount F because it is carried shorter than the target carry amount due to a carry error. That is, the paper can be transported according to the target transport amount before correction.

=== Configuration of Head of this Embodiment ===
In the above-described reference example, the length of the head in the transport direction is 1.25 inches, which is the same as the length of the peripheral surface of the transport roller 23. However, as will be described below, the length in the transport direction of the head of this embodiment is shorter than the length of the peripheral surface of the transport roller 23.

  FIG. 9 is an explanatory diagram of the nozzle arrangement of the head. Four nozzle rows (A row to D row) are provided on the lower surface of the head 41. Each row is provided with 90 nozzles.

The 90 nozzles in each nozzle row are arranged at an interval (nozzle pitch) of 1/120 inch along the transport direction. The nozzles in the B row are positioned on the upstream side in the transport direction by 1/360 inch with respect to the nozzles in the A row. In addition, the nozzles in the C row and the D row are located on the upstream side in the transport direction by 1/360 inch with respect to the nozzles in the B row.
The nozzles in each nozzle row are assigned a smaller number toward the downstream side in the transport direction (# 1 to # 90). That is, the nozzle # 1 is located downstream of the nozzle # 90 in the transport direction.

  Each nozzle is provided with an ink chamber (not shown) and a piezoelectric element. By driving the piezo element, the ink chamber expands and contracts, and ink droplets are ejected from the nozzles.

  Cyan ink is ejected from the nozzles in the A row, magenta ink is ejected from the nozzles in the B row, yellow ink is ejected from the nozzles in the C row, and black ink is ejected from the nozzles in the D row. However, when printing a test sheet in a printer manufacturing factory, the light magenta ink for inspection is supplied to the B row, and the light magenta ink is ejected from the nozzles of the B row to print the test sheet.

  The width in which a pattern can be formed by one dot forming operation is called “the length of the head in the carrying direction”. That is, “the length of the head in the carrying direction” means the length of the nozzle row that ejects ink, and is expressed as “nozzle pitch × number of nozzles”. The length of the head in the conveyance direction when printing a test sheet means the length of the nozzle row of the B row, and is 0.75 inch (= 1/120 inch × 90).

  For this reason, in this embodiment, the length (0.75 inches) of the head in the conveyance direction is shorter than the length (1.25 inches) of the peripheral surface of the conveyance roller.

=== Countermeasures of this embodiment for various problems ===
<Problems caused by the head length being shorter than the roller circumferential surface length>
FIG. 10A is an explanatory diagram of a problem caused by the head length being shorter than the roller circumferential surface length.
In order to correct the DC component transport error, a block pattern is formed by the nozzles on the upstream side in the transport direction of the head, transport processing for one rotation of the transport roller 23 is performed, and the block is blocked by the nozzles on the downstream side in the transport direction of the head. It is necessary to form a correction pattern by forming a pattern.

  However, when the length of the head in the transport direction is shorter than the length of the peripheral surface of the transport roller, the two block patterns cannot be formed close to each other. For this reason, unlike the reference example, a boundary to be inspected by the inspector cannot be formed between the two block patterns. In addition, although the interval between the two block patterns reflects a transport error, it is difficult to determine the interval between the two block patterns if the two block patterns are separated as shown in the figure. .

FIG. 10B is an explanatory diagram of countermeasures of this embodiment for this problem.
In this embodiment, after the pattern A is formed, the conveyance process for half rotation of the conveyance roller 23 is performed to form the pattern B, and the conveyance process for half rotation of the conveyance roller 23 is further performed to form the pattern C. A correction pattern consisting of patterns A to C is formed. Even this correction pattern has two patterns (Pattern A and Pattern C) before and after the conveyance process for one rotation of the conveyance roller 23 necessary for correcting the conveyance error of the DC component. Yes.

  Furthermore, according to the present embodiment, the pattern A and the pattern B can be formed close to each other, and the pattern B and the pattern C can be formed close to each other. Thereby, it is possible to form a boundary to be inspected by the inspector between the pattern A and the pattern B or between the pattern B and the pattern C. According to the present embodiment, the positional relationship between the pattern A and the pattern B can be inspected based on the boundary between the pattern A and the pattern B, and the pattern B based on the boundary between the pattern B and the pattern C. Since the positional relationship between the pattern A and the pattern C can be inspected, it is possible to indirectly determine the positional relationship between the pattern A and the pattern C.

<Problem of AC component conveyance error of pattern B>
The DC component transport error is constant regardless of the start position when the transport roller makes one rotation. For this reason, the positional relationship between the pattern A and the pattern C formed before and after the conveyance process for one rotation of the conveyance roller is not affected by the rotation position of the conveyance roller when the pattern A is formed.
However, in the present embodiment, after the pattern A is formed, the pattern B is formed before the conveyance roller is rotated once. For this reason, the positional relationship between the pattern A and the pattern B is affected by the rotational position of the transport roller when the pattern A is formed.

FIG. 11A is an explanatory diagram of an AC component transport error when forming each pattern. FIG. 11B is an explanatory diagram of the influence of the formation position of the pattern B due to the AC component transport error.
When the rotation position of the conveyance roller at the time of forming the pattern A is the reference position, the paper can be conveyed without causing an AC component conveyance error when the conveyance roller is rotated halfway. Therefore, the pattern B can be formed without being affected by the AC component transport error.

  On the other hand, in the case where the rotation position of the conveyance roller at the time of forming the pattern A is a position rotated by a quarter of the reference position, the conveyance roller is less than the target conveyance amount due to the influence of the AC component conveyance error when the conveyance roller is rotated halfway. Paper is conveyed by the amount. As a result, the pattern B is formed close to the pattern A. Further, when the transport roller further rotates halfway, the paper is transported by a transport amount larger than the target transport amount due to the influence of the AC component transport error. As a result, the pattern C is formed away from the pattern B.

  Thus, due to the influence of the AC component transport error, the position of the pattern B in FIG. 11B changes vertically (downstream or upstream in the transport direction). (However, since the positional relationship between the pattern A and the pattern C is not affected by the AC component, the positions of the pattern A and the pattern C do not change in FIG. 11B.) When the position of the pattern B in the transport direction changes, the pattern The state of the boundary between A and pattern B and the state of the boundary between pattern B and pattern C also change.

  On the other hand, in the present embodiment, the relative rotation amount of the transport roller 23 can be detected by the rotary encoder 52, but there is no origin sensor that detects that the transport roller 23 is at the reference position. Absolute rotation position is not detected. For this reason, in the present embodiment, it is necessary to determine the correction pattern in an unknown state in which the position of the pattern B changes up and down.

  In this embodiment, in order to determine a correction value for correcting the DC component transport error under such circumstances, a correction pattern having an optimum boundary between the pattern A and the pattern B is selected. A correction pattern having the optimum boundary between the pattern C and the pattern C is selected, and a correction value is determined based on the two selected correction patterns. Thereby, even if the position of the pattern B in the transport direction changes, a correction value corresponding to the DC component transport error can be determined.

<Problem of the shape of the boundary between two patterns>
In the correction pattern of the reference example, a boundary is formed by two block patterns. When viewed microscopically, these two block patterns are composed of a plurality of raster lines in which dots are arranged in the moving direction. Therefore, the boundary between the two block patterns is parallel to the raster line.

  12A and 12B are explanatory diagrams of the vicinity of the boundary between two block patterns. A solid line in the figure indicates a raster line, which is actually formed by arranging dots. In FIG. 12A, black stripes are generated as a result of the two block patterns being formed close to each other. In FIG. 12B, white stripes are generated as a result of the two block patterns being formed apart. Both boundaries are parallel to the raster line. In the reference example described above, the presence of black stripes or white stripes is determined at such a boundary.

  By the way, the raster lines constituting the block pattern may be formed with the position in the transport direction shifted due to the influence of the manufacturing variation of the nozzles, the disturbance of the flying direction of the ink, and the like. As a result, the interval between adjacent raster lines is slightly different for each raster line.

12C and 12D are explanatory diagrams of the vicinity of the boundary when the interval between raster lines varies. In FIG. 12C, two block patterns are formed close to each other, and in FIG. 12D, two block patterns are formed apart from each other.
If there is a variation in the spacing of the raster lines, there will also be places in the block pattern where the raster lines are formed close together and look like black lines, or the raster lines are formed apart and look like white lines. A place may arise. As a result, it becomes difficult to specify the position of the boundary, and even if the position of the boundary can be specified, it is difficult to determine the presence of black and white lines at the boundary between the two block patterns. . In addition, depending on how the position of the raster line in the vicinity of the boundary varies in the conveyance direction, the determination of the presence of black and white stripes at the boundary differs.

12E and 12F are explanatory diagrams of countermeasures of this embodiment for this problem. In FIG. 12E, black stripes are generated as a result of the two patterns being formed close to each other. In FIG. 12F, white stripes are generated as a result of the two patterns being formed apart.
In this embodiment, the direction of the boundary between the two patterns is set to a direction that intersects the transport direction and the movement direction. When viewed macroscopically, in this embodiment, hypotenuses are formed in two patterns (for example, pattern A and pattern B), and a boundary is formed by forming the hypotenuses close to each other.
By forming in this way, the boundary is composed of a plurality of raster lines constituting one pattern and a plurality of raster lines constituting the other pattern. For this reason, even if the position of the raster line in the transport direction varies, it is possible to stably determine the presence of black and white stripes at the boundary. That is, this makes it easier for the inspector to inspect the test sheet.

  Hereinafter, this embodiment will be described in detail.

=== Test Sheet of this Embodiment ===
<About test sheet configuration>
FIG. 13 is an explanatory diagram of the test sheet of the present embodiment.
In the test sheet of the present embodiment, nine correction patterns are formed side by side in the movement direction. Each correction pattern is associated with a specific correction value, and a number indicating the correction value is printed on each correction pattern (on the upper end side of the paper). In the following description, “correction pattern (n)” means a correction pattern associated with a correction value n.

<Configuration of correction pattern>
FIG. 14 is an explanatory diagram of a correction pattern according to this embodiment.
Each correction pattern includes a pattern A, a pattern B, and a pattern C, and has a substantially rectangular shape as a whole.

  The pattern A includes a trapezoid pattern A1 and an inverted trapezoid pattern A2. The trapezoid pattern A1 and the inverted trapezoid pattern A2 are respectively formed at the two corners on the upper side (downstream in the transport direction) of the correction pattern. In the trapezoid pattern A1 and the inverted trapezoid pattern A2, one of the two sides between the upper base and the lower base is perpendicular to the upper base and the lower base, and constitutes one side of the correction pattern. In the trapezoid pattern A1 and the inverted trapezoid pattern A2, the other of the two sides between the upper base and the lower base is a hypotenuse. This hypotenuse is a direction that intersects the transport direction and the movement direction. The hypotenuse of the trapezoid pattern A1 and the hypotenuse of the inverted trapezoid pattern A2 are parallel to each other. The detailed configuration of the pattern A will be described later.

  The pattern B includes an inclined pattern B1, a rectangular pattern B2, and an inclined pattern B3. The inclined pattern B1 is formed above the rectangular pattern B2 and has a parallelogram shape. One side of the parallelogram forms the upper side of the correction pattern. Two parallel sides sandwiching this side are parallel to the oblique sides of the trapezoid pattern A1 and the inverted trapezoid pattern A2. The rectangular pattern B2 is located at the center of the correction pattern. The two sides of the rectangular pattern B2 constitute two sides of the correction pattern. The inclined pattern B3 is formed on the lower side (upstream side in the transport direction) of the rectangular pattern B2 and has a parallelogram shape. One side of the parallelogram forms the lower side of the correction pattern. Two parallel sides sandwiching this side are parallel to the oblique sides of inverted trapezoid pattern C1 and trapezoid pattern C2, which will be described later. When the inclination pattern B1 and the inclination pattern B3 are compared, the inclination direction is reversed. The detailed configuration of the pattern B will be described later.

  The pattern C includes an inverted trapezoid pattern C1 and a trapezoid pattern C2. The inverted trapezoid pattern C1 and the trapezoid pattern C2 are respectively formed at the two corners on the lower side (upstream side in the transport direction) of the correction pattern. In the inverted trapezoid pattern C1 and the trapezoid pattern C2, one of the two sides between the upper base and the lower base constitutes one side of the correction pattern that is not perpendicular to the upper base and the lower base. In the inverted trapezoid pattern C1 and the trapezoid pattern C2, the other of the two sides between the upper base and the lower base is a hypotenuse. This hypotenuse is a direction that intersects the transport direction and the movement direction. The hypotenuse of the inverted trapezoid pattern C1 and the hypotenuse of the trapezoid pattern C2 are parallel to each other. However, the hypotenuses of the inverted trapezoid pattern C1 and the trapezoid pattern C2 are formed in a direction intersecting with the hypotenuses of the trapezoid pattern A1 and the inverted trapezoid pattern A2. The detailed configuration of the pattern C will be described later.

  Between pattern A and pattern B, boundary A1B1, boundary A2B1, and boundary A1B2 are formed. The boundary A1B1 is a boundary formed between the trapezoid pattern A1 of the pattern A and the inclined pattern B1 of the pattern B. The boundary A2B1 is a boundary formed between the inverted trapezoid pattern A2 of the pattern A and the inclined pattern B1 of the pattern B. The boundary A1B2 is a boundary formed between the trapezoid pattern A1 of the pattern A and the rectangular pattern B2 of the pattern B. The boundary A1B1 and the boundary A2B1 are formed along a direction that intersects the transport direction and is formed along a direction that intersects the moving direction. On the other hand, the boundary A1B2 is formed along the moving direction. As will be described later, the inspector pays attention to the boundary A1B1 and the boundary A2B1, but does not pay attention to the boundary A1B2.

  A boundary C1B3, a boundary C2B3, and a boundary C1B2 are formed between the pattern B and the pattern C. The boundary C1B3 is a boundary formed between the inverted trapezoid pattern C1 of the pattern C and the inclined pattern B3 of the pattern B. The boundary C2B3 is a boundary formed between the trapezoid pattern C2 of the pattern C and the inclined pattern B3 of the pattern B. The boundary C1B2 is a boundary formed between the inverted trapezoid pattern C1 of the pattern C and the rectangular pattern B2 of the pattern B. The boundary C1B3 and the boundary C2B3 are formed along a direction that intersects the transport direction and is formed along a direction that intersects the moving direction. However, the directions of the boundary C1B3 and the boundary C2B3 are directions that also intersect the boundary A1B1 and the boundary A2B1. As will be described later, the inspector pays attention to the boundary C1B3 and the boundary C2B3, but does not pay attention to the boundary C1B2.

  In any of the correction patterns, after the pattern A is formed, the paper is transported by a transport amount corresponding to about a half rotation of the transport roller, and a pattern B is formed. However, the target conveyance amount of the conveyance process performed between the formation of the pattern A and the formation of the pattern B is different for each correction pattern. Further, after the pattern B is formed, the paper is transported by a transport amount corresponding to about a half rotation of the transport roller, and a pattern C is formed. However, the target conveyance amount of the conveyance process performed between the formation of the pattern B and the formation of the pattern C is different for each correction pattern. For this reason, the positional relationship of the pattern B with respect to the pattern A and the positional relationship of the pattern C with respect to the pattern B differ depending on each correction pattern. That is, the positional relationship between the pattern A and the pattern C differs depending on each correction pattern.

  As a result, the state of each boundary differs for each correction pattern. At the boundary where the two patterns overlap, the boundary is visually recognized as dark (visible as a black stripe). On the other hand, at the boundary where the two patterns are separated from each other, the boundary is visually recognized as light (visible as a white stripe).

  Next, a method for printing the correction patterns A to C will be described, and then a method for printing all the correction patterns will be described. Each pattern is formed with a resolution of 360 dpi (moving direction) × 240 dpi (conveying direction). Since the diameter of the dots constituting the raster line is 1/240 inch, if a pattern is formed at this resolution, a gap is generated between the raster lines constituting each pattern.

<About the printing method of pattern A>
FIG. 15 is an explanatory diagram of the pattern A printing method. Pattern A is formed by two passes. On the left side of the figure, the position of the head (position of row B) with respect to the paper in the first and second passes is shown. When the pattern A is formed, ink is ejected from the nozzles # 76 to # 87. The nozzles that eject ink are indicated by black circles in the first pass and hatched in the second pass. The head can reciprocate in the moving direction, but when the pattern A is formed, the head moves only in one direction. Here, it is assumed that the pattern A is formed when the head moves from left to right in the drawing.
On the right side of the figure, raster lines constituting the pattern A are shown. The raster line formed by the first pass is shown in black, and the raster line formed by the second pass is shown by hatching.

  In the first pass, ink is ejected from nozzle # 76 to nozzle # 87 when the head reaches a predetermined position in the movement direction. Nozzle # 76 forms a 4/360 inch raster line constituting trapezoid pattern A1 (that is, forms four dots), and forms an inverted trapezoid pattern A2 after a 60/360 inch idle running section. A 96/360 inch raster line is formed (that is, 96 dots are formed). Each nozzle forms a raster line that forms a trapezoidal pattern A1 by forming a raster line that is 8/360 inches longer than the nozzle adjacent to the downstream side in the transport direction. After the 60/360 inch idle running section, A raster line that forms a reverse trapezoid pattern A2 is formed by forming a raster line that is 8/360 inches shorter than the nozzle adjacent to the downstream side in the transport direction. Thereby, when the head reaches a predetermined position in the moving direction, the ejection of ink from the nozzles # 76 to # 87 is stopped.

  After the first pass, a transport process of a target transport amount of 18/4320 inches (1/240 inches) corresponding to half the nozzle pitch is performed. Since the transport amount is very small, the transport error is extremely small (the transport error can be ignored).

  In the second pass, raster lines are formed between the raster lines formed in the first pass. Also in the second pass, when the head reaches a predetermined position in the movement direction, ink is ejected from nozzle # 76 to nozzle # 87. Nozzle # 76 forms an 8/360 inch raster line (that is, forms 8 dots) that forms trapezoid pattern A1, and forms inverted trapezoid pattern A2 after a 60/360 inch idle section. A 92/360 inch raster line is formed (that is, 92 dots are formed). Each nozzle forms a raster line that forms a trapezoidal pattern A1 by forming a raster line that is 8/360 inches longer than the nozzle adjacent to the downstream side in the transport direction. After the 60/360 inch idle running section, A raster line that forms a reverse trapezoid pattern A2 is formed by forming a raster line that is 8/360 inches shorter than the nozzle adjacent to the downstream side in the transport direction. Thereby, when the head reaches a predetermined position in the moving direction, the ejection of ink from the nozzles # 76 to # 87 is stopped.

  The position in the moving direction of the right end of the 24 raster lines constituting the trapezoid pattern A1 gradually changes by 4/360 inches. Thereby, when the trapezoid pattern A1 is viewed macroscopically, a hypotenuse in a direction intersecting both the transport direction and the moving direction is formed. Further, the position in the moving direction of the left end of the 24 raster lines constituting the inverted trapezoid pattern A2 gradually changes by 4/360 inches. As a result, when the inverted trapezoid pattern A2 is viewed macroscopically, a hypotenuse in a direction that intersects both the transport direction and the moving direction is formed.

<About the printing method of pattern B>
FIG. 16 is an explanatory diagram of a pattern B printing method. The pattern B is also formed by two passes. On the left side of the figure, the position of the head (position of row B) with respect to the paper in the first and second passes is shown. When the pattern B is formed, ink is ejected from the nozzles # 1 to # 87. The nozzles that eject ink are indicated by black circles in the first pass and hatched in the second pass. The head can reciprocate in the moving direction, but when the pattern B is formed, the head moves only in one direction. Here, it is assumed that the pattern B is formed when the head moves from left to right in the drawing.
On the right side of the figure, raster lines constituting the pattern B are shown. The raster line formed by the first pass is shown in black, and the raster line formed by the second pass is shown by hatching.

  In the first pass, ink is ejected from nozzle # 13 to nozzle # 75 when the head reaches a predetermined position in the movement direction. The nozzles # 13 to # 75 form a 160/360 inch raster line constituting the rectangular pattern B2. After nozzle # 13 to nozzle # 75 move 4/360 inches after ink is ejected, ink is ejected from nozzle # 1, and nozzle # 1 forms a 60/360 inch raster line. The nozzles # 1 to # 12 form a 60/360 inch raster line by ejecting ink after the nozzle adjacent to the downstream side in the transport direction has moved 8/360 positions after ejecting the ink. . The raster lines formed by the nozzles # 1 to # 12 constitute an inclined pattern B1. Further, after nozzle # 13 to nozzle # 75 have moved 4/360 inches after ink is ejected, ink is ejected from nozzle # 87, and nozzle # 87 forms a 60/360 inch raster line. The nozzles # 76 to # 87 form a 60/360 inch raster line by ejecting ink after the nozzle adjacent to the upstream side in the transport direction has moved 8/360 positions after ejecting the ink. . The raster lines formed by the nozzle # 76 to the nozzle # 87 constitute an inclined pattern B3.

  After the first pass, a transport process of a target transport amount of 18/4320 inches (1/240 inches) corresponding to half the nozzle pitch is performed. Since the transport amount is very small, the transport error is extremely small (the transport error can be ignored).

  In the second pass, raster lines are formed between the raster lines formed in the first pass. Also in the second pass, when the head reaches a predetermined position in the movement direction, ink is ejected from nozzle # 13 to nozzle # 75. The nozzles # 13 to # 75 form a 160/360 inch raster line constituting the rectangular pattern B2. After nozzle # 13 to nozzle # 75 have moved 8/360 inches after ink is ejected, ink is ejected from nozzle # 1, and nozzle # 1 forms a 60/360 inch raster line. The nozzles # 1 to # 12 form a 60/360 inch raster line by ejecting ink after the nozzle adjacent to the downstream side in the transport direction has moved 8/360 positions after ejecting the ink. . The raster lines formed by the nozzles # 1 to # 12 constitute an inclined pattern B1. Further, after nozzle # 13 to nozzle # 75 have moved 8/360 inches after ink is ejected, ink is ejected from nozzle # 87, and nozzle # 87 forms a 60/360 inch raster line. The nozzles # 76 to # 87 form a 60/360 inch raster line by ejecting ink after the nozzle adjacent to the upstream side in the transport direction has moved 8/360 positions after ejecting the ink. . The raster lines formed by the nozzle # 76 to the nozzle # 87 constitute an inclined pattern B3. Since the inclined pattern B3 is formed by the nozzles # 76 to # 87, it is formed by the same nozzle as that forming the pattern A.

  The position in the moving direction of the left end of the 24 raster lines constituting the inclined pattern B1 gradually changes by 4/360 inches. The position in the moving direction of the right end of the 24 raster lines constituting the inclined pattern B1 also gradually changes by 4/360 inches. Thereby, when the inclined pattern B1 is viewed macroscopically, a hypotenuse in a direction intersecting both the transport direction and the moving direction is formed. Similarly, when the inclined pattern B3 is viewed macroscopically, a hypotenuse in the direction intersecting both the transport direction and the moving direction is formed.

<About the printing method of pattern C>
FIG. 17 is an explanatory diagram of a pattern C printing method. The pattern C is also formed by two passes. On the left side of the figure, the position of the head (position of row B) with respect to the paper in the first and second passes is shown. When the pattern C is formed, ink is ejected from the nozzles # 1 to # 12. The nozzles that eject ink are indicated by black circles in the first pass and hatched in the second pass. The head can reciprocate in the moving direction, but when the pattern C is formed, the head moves only in one direction. Here, it is assumed that the pattern C is formed when the head moves from left to right in the drawing.
On the right side of the figure, raster lines constituting the pattern C are shown. The raster line formed by the first pass is shown in black, and the raster line formed by the second pass is shown by hatching.

  In the first pass, ink is ejected from nozzle # 1 to nozzle # 12 when the head reaches a predetermined position in the movement direction. Nozzle # 1 forms a 96/360 inch raster line (that is, forms 96 dots) that constitutes the inverted trapezoid pattern C1, and forms a trapezoid pattern C2 after the 60/360 inch idle section. A 4/360 inch raster line is formed (that is, four dots are formed). Each nozzle forms a raster line that forms a reverse trapezoidal pattern C1 by forming a raster line that is 8/360 inches shorter than the nozzle adjacent to the downstream side in the conveyance direction, and after the 60/360 inch idle running section. A raster line that is 8/360 inches longer than the nozzles adjacent to the downstream side in the transport direction is formed to form a raster line constituting the trapezoid pattern C2. Thereby, when the head reaches a predetermined position in the moving direction, the ejection of ink from the nozzles # 1 to # 12 is stopped.

  After the first pass, a transport process of a target transport amount of 18/4320 inches (1/240 inches) corresponding to half the nozzle pitch is performed. Since the transport amount is very small, the transport error is extremely small (the transport error can be ignored).

  In the second pass, raster lines are formed between the raster lines formed in the first pass. Also in the second pass, when the head reaches a predetermined position in the movement direction, ink is ejected from nozzle # 1 to nozzle # 12. Nozzle # 1 forms a 92/360 inch raster line (that is, 92 dots are formed) constituting the inverted trapezoid pattern C1, and forms a trapezoid pattern C2 after a 60/360 inch idle running section. 8/360 inch raster lines are formed (ie, 8 dots are formed). Each nozzle forms a raster line that forms a reverse trapezoidal pattern C1 by forming a raster line that is 8/360 inches shorter than the nozzle adjacent to the downstream side in the conveyance direction, and after the 60/360 inch idle running section. A raster line that is 8/360 inches longer than the nozzles adjacent to the downstream side in the transport direction is formed to form a raster line constituting the trapezoid pattern C2. Thereby, when the head reaches a predetermined position in the moving direction, the ejection of ink from the nozzles # 1 to # 12 is stopped. Since the pattern C is formed by the nozzles # 1 to # 12, it is formed by the same nozzle as the nozzle that forms the inclined pattern B1 of the pattern B.

  The position of the right end of the 24 raster lines constituting the inverted trapezoidal pattern C1 gradually changes by 4/360 inches. As a result, when the inverted trapezoid pattern C1 is viewed macroscopically, a hypotenuse in a direction that intersects both the transport direction and the moving direction is formed. Also, the position of the left end of the 24 raster lines constituting the trapezoid pattern C2 in the moving direction gradually changes by 4/360 inches. Thereby, when the trapezoid pattern C2 is viewed macroscopically, a hypotenuse in a direction intersecting both the transport direction and the moving direction is formed.

  Note that the 24 raster lines of the inverted trapezoid pattern C1 are shorter toward the upstream side in the transport direction. On the other hand, the 24 raster lines of the trapezoid pattern A1 are longer toward the upstream side in the transport direction. For this reason, when viewed macroscopically, the hypotenuse of the inverted trapezoid pattern C1 is in a direction intersecting with the hypotenuse of the trapezoid pattern A1. Further, the 24 raster lines of the trapezoid pattern C2 are longer toward the upstream side in the transport direction. On the other hand, the 24 raster lines of the inverted trapezoid pattern A2 are shorter toward the upstream side in the transport direction. For this reason, when viewed macroscopically, the hypotenuse of the trapezoid pattern C2 is in a direction intersecting with the hypotenuse of the inverted trapezoid pattern A2.

<Printing method for all correction patterns>
FIG. 18 is an explanatory diagram of a test sheet printing method.
On the right side of the figure, nine correction patterns formed on the test sheet are drawn.
On the left side of the figure, the position of the head (position of row B) with respect to the paper in each pass is shown. In the rectangle indicating the position of the head, two numbers and symbols A to C are entered. The top number shows the pass number. The number in the center indicates the number of the correction pattern formed in the pass. The symbol at the bottom indicates the pattern name formed in the pass. For example, the leftmost rectangle indicates the position of the head with respect to the paper in the first pass (pass 1), and the pattern A of the correction pattern (-8) is formed in the pass.
The upper table in the figure shows the number and pattern name of the correction pattern formed in each pass, and the target carry amount of the carry process performed between the passes. This table also shows that the pattern A of the correction pattern (−8) is formed in the first pass (pass 1). This table also shows that the medium is transported at a target transport amount of 18/4320 inches in the transport process performed between pass 1 and pass 2.

  In pass 1 to pass 18, pattern A of each correction pattern is formed. The pattern A of each correction pattern is formed by two passes. For example, the pattern A of the correction pattern (0) is formed by the pass 9 and the pass 10. Therefore, in the pattern A of the correction pattern (0), the “first pass” in FIG. 15 corresponds to the pass 9 and the “second pass” corresponds to the pass 10. Between the two passes that form the pattern A, a conveyance process with a target conveyance amount of 18/4320 inches is performed. After the formation of the pattern A for a certain correction pattern, a conveyance process with a target conveyance amount of 18/4320 inches is performed, and the pattern A for the next correction pattern is formed. For this reason, the pattern A of a certain correction pattern is formed on the upstream side in the transport direction by 36/4320 inches compared to the pattern A of the correction pattern formed immediately before that.

  After pass 18, until the pass 35, the carrying process of the target carry amount of 132/4320 inches is repeatedly performed. In pass 19 to pass 35, since there is no pattern to be formed, ink ejection and head movement are not performed, and are omitted. Between pass 35 and pass 36, a carrying process of a target carry amount of 142/4320 inches is performed.

  In pass 36 to pass 53, pattern B of each correction pattern is formed. Pattern B of each correction pattern is formed by two passes. For example, the pattern B of the correction pattern (0) is formed by the path 44 and the path 45. Therefore, in the pattern B of the correction pattern (0), the “first pass” in FIG. 16 corresponds to the pass 44, and the “second pass” corresponds to the pass 45. Between the two passes for forming the pattern B, a conveyance process with a target conveyance amount of 18/4320 inches is performed. After the formation of the pattern B for a certain correction pattern, a conveyance process with a target conveyance amount of 20/4320 inches is performed, and the pattern B for the next correction pattern is formed. For this reason, the pattern B of a certain correction pattern is formed on the upstream side in the transport direction by 38/4320 inches compared to the pattern B of the correction pattern formed immediately before that. As a result, the positional relationship between the pattern A and the pattern B of a certain correction pattern is 2/4320 inches apart from the correction pattern formed immediately before that.

  After pass 53, up to pass 70, the carrying process of the target carry amount of 132/4320 inches is repeatedly performed. In pass 54 to pass 70, since there is no pattern to be formed, ink ejection and head movement are not performed, and are omitted. Between pass 70 and pass 71, a transport process with a target transport amount of 126/4320 inches is performed.

  In pass 71 to pass 88, a pattern C of each correction pattern is formed. The pattern C of each correction pattern is formed by two passes. For example, the pattern C of the correction pattern (0) is formed by the path 79 and the path 80. Therefore, in the pattern C of the correction pattern (0), the “first pass” in FIG. 17 corresponds to the pass 79, and the “second pass” corresponds to the pass 80. Between the two passes that form the pattern C, a transport process with a target transport amount of 18/4320 inches is performed. After the pattern C of a certain correction pattern is formed, a conveyance process with a target conveyance amount of 22/4320 inches is performed, and the pattern C of the next correction pattern is formed. For this reason, the pattern C of a certain correction pattern is formed on the upstream side in the transport direction by 40/4320 inches compared to the pattern C of the correction pattern formed immediately before. As a result, the positional relationship between the pattern B and the pattern C of a certain correction pattern is 2/4320 inches apart from the correction pattern formed immediately before that.

=== Characteristics of correction pattern ===
<When there is no DC error and AC component>
FIG. 19 is an explanatory diagram of the state of the correction pattern in the case where there is no DC error and AC component. In FIG. 19, for the sake of explanation, the outline of each pattern is indicated by a line, and the inside of the pattern is blank. However, the actual correction pattern is macroscopically filled as shown in FIG. 13, and microscopically is a pattern composed of raster lines as shown in FIGS. Further, in FIG. 19, the portion where the patterns overlap is painted black.

In the correction pattern (0), all 24 raster lines constituting the trapezoid pattern A1, 24 raster lines constituting the inclined pattern B1, and 24 raster lines constituting the inverted trapezoid pattern A2 are all conveyed. The direction position is the same. In addition, the 24 raster lines constituting the inclined pattern B1 are positioned between the right end of the 24 raster lines constituting the trapezoid pattern A1 and the left end of the 24 raster lines constituting the inverted trapezoid pattern A2. To do. As a result, 24 raster lines constituting the trapezoid pattern A1, 24 raster lines constituting the inclined pattern B1, and 24 raster lines constituting the inverted trapezoid pattern A2 are 24 160/360 inches. Each of them is connected like a raster line. That is, the trapezoid pattern A1 and the inclined pattern B1 are exactly connected, and the inverted trapezoid pattern A2 and the inclined pattern B1 are also closely connected.
For this reason, in the correction pattern (0), the boundary A1B1 and the boundary A2B2 cannot be visually recognized. Similarly, the boundary C1B3 and the boundary C2B3 cannot be visually recognized.

In the correction pattern with a negative number, the pattern B is formed so as to be shifted to the downstream side in the transport direction with respect to the pattern A. That is, the positional relationship between the pattern A and the pattern B of the correction pattern to which a negative number is attached is closer than the positional relationship between the pattern A and the pattern B of the correction pattern (0). As a result, the trapezoid pattern A1 and the inclined pattern B1 are separated, and the inverted trapezoid pattern A2 and the inclined pattern B1 overlap.
For this reason, in the correction pattern with a negative number, the boundary A1B1 is visually recognized as a white stripe, and the boundary A2B1 is visually recognized as a dark stripe, resulting in a black stripe. Similarly, the boundary C1B3 is visually recognized as light and white stripes are generated, and the boundary C2B3 is visually recognized as dark and black stripes are generated.
Furthermore, the pattern A and the pattern B are closer to each other, and the pattern B and the pattern C are closer to each other as the correction pattern with a larger negative number is added. As a result, the trapezoid pattern A1 and the inclined pattern B1 are greatly separated, and the inverted trapezoid pattern A2 and the inclined pattern B1 are greatly overlapped. For this reason, white stripes and black stripes are clearly recognized as the correction pattern with a large negative number is added.

In the correction pattern with a plus number, the pattern B is formed so as to be shifted to the upstream side in the transport direction with respect to the pattern A. In other words, the positional relationship between the pattern A and the pattern B of the correction pattern to which a plus number is attached is far from the positional relationship between the pattern A and the pattern B of the correction pattern (0). As a result, the trapezoid pattern A1 and the inclined pattern B1 overlap, and the inverted trapezoid pattern A2 and the inclined pattern B1 are separated.
For this reason, in the correction pattern to which a plus number is attached, the boundary A1B1 is visually recognized dark and black stripes are generated, and the boundary A2B1 is visually recognized light and white stripes are generated. Similarly, the boundary C1B3 is visually recognized dark and black stripes are generated, and the boundary C2B3 is visually recognized light and white stripes are generated.
Furthermore, the pattern A and the pattern B are far apart, and the pattern B and the pattern C are far apart as the correction pattern with a large plus number is added. As a result, the trapezoid pattern A1 and the inclined pattern B1 are largely overlapped, and the inverted trapezoid pattern A2 and the inclined pattern B1 are greatly separated. For this reason, white stripes and black stripes are clearly recognized as the correction pattern with a large plus number is added.

  In the present embodiment, two boundaries (boundary A1B1 and boundary A2B1) are formed between the pattern A and the pattern B. At the boundary A1B1, the trapezoidal pattern A1 of the pattern A is located upstream of the inclined pattern B1 of the pattern B in the conveying direction, and at the boundary A1B2, the inclined pattern B1 of the pattern B is conveyed more than the inverted trapezoidal pattern A2 of the pattern A. Located upstream in the direction. With this configuration, when the positional relationship between the pattern A and the pattern B changes, both white stripes and black stripes can be generated at the boundary between the patterns A and B. Thereby, the visibility of the inspector is improved.

  Similarly, in the present embodiment, two boundaries (boundary C1B3 and boundary C2B3) are formed between the pattern B and the pattern C. At the boundary C1B3, the inclined pattern B3 of the pattern B is located upstream of the inverted trapezoidal pattern C1 of the pattern C in the transport direction, and at the boundary C2B3, the trapezoidal pattern C2 of the pattern C is transported more than the inclined pattern B3 of the pattern B. Located upstream in the direction. With this configuration, when the positional relationship between the pattern B and the pattern C changes, both white stripes and black stripes can be generated at the boundary between the patterns B and C. Thereby, the visibility of the inspector is improved.

  In the present embodiment, the boundary A1B1 and the boundary A2B1 are parallel. Thereby, even if the positional relationship between the pattern A and the pattern B changes in any direction, the white stripes and the black stripes are generated with the same width, so the visibility of the inspector is good. Similarly, since the boundary C1B3 and the boundary C2B3 are parallel, the visibility of the inspector is good.

<When there is a DC component transport error>
Next, a case where only a DC component error occurs will be described. Here, a case will be described in which paper is transported with a transport amount larger than the target transport amount.

FIG. 20A is an explanatory diagram of the state of the correction pattern (0) when the paper is transported with a transport amount larger than the target transport amount.
Here, since the paper is transported by a transport amount that is larger than the target transport amount, the transport process performed between the pass 10 for forming the pattern A of the correction pattern (0) and the pass 44 for forming the pattern B is performed. The transport amount is larger than the target transport amount. For this reason, the pattern B of the correction pattern (0) is formed shifted to the upstream side in the transport direction as compared with the case where there is no transport error. That is, as a result of transporting more paper than the target transport amount, the positional relationship between the pattern A and the pattern B is separated. As a result, the trapezoid pattern A1 and the inclined pattern B1 overlap, and the inverted trapezoid pattern A2 and the inclined pattern B1 are separated. For this reason, in the correction pattern (0), the boundary A1B1 is visually recognized dark and black stripes are generated, and the boundary A2B1 is visually recognized light and white stripes are generated. Similarly, in the correction pattern (0), the boundary C1B3 is visually recognized as dark and black stripes are generated, and the boundary C2B3 is visually recognized as light and white stripes are generated.
In other words, the boundary of the correction pattern (0) when the paper is transported with a transport amount larger than the target transport amount approximates the boundary of the correction pattern with a positive number when there is no transport error. State.

FIG. 20B is an explanatory diagram of the states of nine correction patterns in this case.
Here, since the paper is transported by a transport amount larger than the target transport amount, the positional relationship between the pattern A and the pattern B of each correction pattern is far from that when there is no transport error. As a result, white stripes and black stripes in the correction patterns with negative numbers are reduced.
If the paper is transported by a transport amount that is, for example, 4/4320 inches larger than the target transport amount during the half rotation of the transport roller 23, the pattern A and the pattern B are more than the correction pattern (0). In the correction pattern (−4) in which the positional relationship approaches 4/4320 inches, the boundary A1B1 and the boundary A2B1 are difficult to see. Similarly, during the half rotation of the transport roller 23, for example, if the paper is transported by a transport amount that is 4/4320 inches larger than the target transport amount, the patterns B and C are more than the correction pattern (0). The boundary C1B3 and the boundary C2B3 become difficult to see in the correction pattern (−4) in which the positional relationship is close to 4/4320 inches.

In other words, when the paper is transported with a transport amount larger than the target transport amount, the correction pattern in which the boundary A1B1 and the boundary A2B1 are difficult to see is a correction pattern with a negative number. Similarly, when the paper is transported with a transport amount larger than the target transport amount, the correction pattern in which the boundary C1B3 and the boundary C2B3 are difficult to see is a correction pattern with a negative number.
On the contrary, when the paper is transported with a transport amount smaller than the target transport amount, the correction pattern in which the boundary A1B1 and the boundary A2B1 are difficult to see becomes a correction pattern with a plus number. Similarly, when the paper is transported with a transport amount smaller than the target transport amount, the correction pattern in which the boundary C1B3 and the boundary C2B3 are difficult to see is a correction pattern with a plus number.

In this way, when only the DC component error occurs, the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are most difficult to see are the same. Further, as the DC component error is larger, the correction pattern in which the boundary is most difficult to see becomes a correction pattern at a position away from the correction pattern (0).
Therefore, when only a DC component error occurs, the number of the correction pattern that is most difficult to see the boundary reflects the DC component transport error, and has a value corresponding to the correction value for correcting the DC component transport error. Also become.

<When there is an AC component error>
Next, a case where only an AC component error occurs will be described. Here, it is assumed that an AC component conveyance error as shown in FIG. 11A occurs, and the rotation position of the conveyance roller at the time of forming the pattern A is a position rotated by ¼ from the reference position. That is, in the conveyance process performed between the formation of the pattern A and the formation of the pattern B, the paper is conveyed by a conveyance amount smaller than the target conveyance amount, and the conveyance performed between the formation of the pattern B and the formation of the pattern C. In the processing, the paper is transported with a transport amount larger than the target transport amount.

FIG. 21A is an explanatory diagram of the state of the correction pattern (0) when an AC component error occurs.
The pattern B for correction (0) is formed after the paper has been transported by a transport amount smaller than the target transport amount, and thus is formed shifted to the downstream side in the transport direction as compared with the case where there is no transport error. Is done. For this reason, the positional relationship between the pattern A and the pattern B approaches. As a result, the trapezoid pattern A1 and the inclined pattern B1 are separated, and the inverted trapezoid pattern A2 and the inclined pattern B1 overlap. For this reason, in the correction pattern (0), the boundary A1B1 is visually recognized as white and a white stripe is generated, and the boundary A2B1 is visually recognized as dark and a black stripe is generated. That is, the upper boundary of the correction pattern (0) in this case is a state that approximates the upper boundary of the correction pattern that is assigned a negative number when there is no conveyance error.

  On the other hand, since the AC component transport error is substantially a sine curve, the transport amount corresponding to the half rotation of the transport roller performed from the formation of pattern B to the formation of pattern C is from the formation of pattern A to the formation of pattern B. A transport error opposite to the transport error included in the transport amount for the half rotation of the transport roller performed until this time is included. For this reason, the positional relationship between the pattern B and the pattern C is separated from the positional relationship between the pattern A and the pattern B. As a result, the inverted trapezoid pattern C1 and the inclined pattern B3 overlap, and the trapezoid pattern C2 and the inclined pattern B3 are separated. For this reason, in the correction pattern (0), the boundary C1B3 is visually recognized dark and black stripes are generated, and the boundary C2B3 is visually recognized light and white stripes are generated. That is, the lower boundary of the correction pattern (0) in this case is in a state that approximates the upper boundary of the correction pattern to which a plus number is assigned when there is no conveyance error.

FIG. 21B is an explanatory diagram of the states of nine correction patterns in this case.
When attention is paid to the positional relationship between the pattern A and the pattern C of each correction pattern, only the AC component error occurs and the DC component error does not occur in this case. Therefore, the positions of the pattern A and the pattern C in FIG. Same as relationship. However, the pattern B is shifted from the pattern A and the pattern C to the downstream side in the transport direction due to the influence of the AC component error.

  Since the positional relationship between the pattern A and the pattern B of each correction pattern is closer than when there is no conveyance error, white stripes and black stripes of the correction patterns with plus numbers are reduced. . On the contrary, since the positional relationship between the patterns B and C of each correction pattern is far from that in the case where there is no conveyance error, white stripes and black stripes of the correction pattern with a negative number are displayed. It is reduced.

  Assume that the position of the pattern B is changed by 4/4320 inches downstream of the pattern A and the pattern C on the downstream side in the transport direction due to the influence of the AC component. In this case, the boundary A1B1 and the boundary A2B1 are hardly visible in the correction pattern (+4) in which the positional relationship between the pattern A and the pattern B is 4/4320 inches away from the correction pattern (0). On the other hand, the boundary C1B3 and the boundary C2B3 are most difficult to see in the correction pattern (−4) in which the positional relationship between the pattern B and the pattern C is closer to the 4/4320 inch than the correction pattern (0).

  In this way, when only an AC component error occurs, the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are the least visible are the correction pattern (0). On the opposite side across. In other words, the correction pattern (0) is positioned between the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are hard to see. Further, as the AC component error is larger, the correction pattern in which the boundary is most difficult to see becomes a correction pattern at a position away from the correction pattern (0).

  When both DC component and AC component errors occur, the state shown in FIG. 20B and the state shown in FIG. 21B are overlapped. That is, in this case, the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are the least visible are sandwiched between correction patterns having numbers corresponding to DC component transport errors. On the other side. In other words, there is a correction pattern with a number corresponding to the DC component transport error between the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are most difficult to see.

<If there is a landing position shift>
FIG. 22 is an explanatory diagram of the ink discharge speed Vm of each nozzle. The ink discharge speed Vm of each nozzle differs due to the influence of head manufacturing variation and the like. Adjacent nozzles have approximate ink discharge speeds, but distant nozzles may have greatly different ink discharge speeds Vm. Here, the nozzles on the downstream side in the transport direction (nozzles near nozzle # 1) have a higher ink ejection speed than the nozzles on the upstream side in the transport direction (nozzles near nozzle # 90).

  When ink is ejected from each nozzle that moves in the moving direction, ink droplets ejected from a nozzle with a fast ink ejection speed land earlier, so dots formed by nozzles with a fast ink ejection speed have a slow ink ejection speed. Compared to the dots formed by the nozzles, they are formed on the upstream side in the movement direction. Therefore, the pattern formed by the nozzles on the downstream side in the transport direction (nozzles near nozzle # 1) is more upstream in the movement direction than the pattern formed by the nozzles on the upstream side in the transport direction (nozzles near nozzle # 90). Located on the side.

FIG. 23A is an explanatory diagram of the state of the correction pattern (0) when the ink discharge speed Vm is different.
The trapezoid pattern A1 and the inverted trapezoid pattern A2 are formed by nozzles (nozzles # 76 to # 86) on the upstream side in the transport direction, and the inclined pattern B1 is formed by nozzles (nozzles # 1 to nozzle # 12) on the downstream side in the transport direction. The For this reason, the trapezoid pattern A1 and the inverted trapezoid pattern A2 are located on the downstream side in the movement direction (on the right side in the drawing) relative to the inclined pattern B1. As a result, the trapezoid pattern A1 and the inclined pattern B1 overlap, and the inverted trapezoid pattern A2 and the inclined pattern B1 are separated. For this reason, in the correction pattern (0), the boundary A1B1 is visually recognized dark and black stripes are generated, and the boundary A2B1 is visually recognized light and white stripes are generated. That is, the boundary A1B1 and the boundary A2B1 of the correction pattern (0) in this case are in a state that approximates the boundary A1B1 and the boundary A2B1 of the correction pattern numbered positively when there is no conveyance error (however, The boundary A1B2 is in a different state).

  On the other hand, the reverse trapezoid pattern C1 and the trapezoid pattern C2 are formed by nozzles (nozzles # 1 to # 12) on the downstream side in the transport direction, and the inclined pattern B3 is formed by nozzles (nozzles # 76 to # 86) on the upstream side in the transport direction. It is formed. For this reason, the inverted trapezoid pattern C1 and the trapezoid pattern C2 are located on the upstream side in the movement direction (on the left side in the drawing) relative to the inclined pattern B3. As a result, the inverted trapezoid pattern C1 and the inclined pattern B3 are separated, and the trapezoid pattern C2 and the inclined pattern B3 overlap. For this reason, in the correction pattern (0), the boundary C1B3 is visually recognized as light and white stripes are generated, and the boundary C2B3 is visually recognized as dark and black stripes are generated. In other words, the boundary C1B3 and the boundary C2B3 of the correction pattern (0) in this case are in a state approximate to the boundary C1B3 and the boundary C2B3 of the correction pattern numbered negatively when there is no conveyance error (however, The boundary C1B2 is in a different state).

  The nozzles that form the pattern A and the nozzles that form the inclined pattern B3 are the same. In each correction pattern, the nozzle that forms the inclined pattern B1 and the nozzle that forms the pattern C are the same. For this reason, the amount of change in the relative positional relationship of the pattern A with respect to the inclined pattern B1 is the same as the amount of change in the relative positional relationship of the inclined pattern B3 with respect to the pattern C. In other words, the pattern C is shifted to the left side with respect to the inclined pattern B3 by the amount that the pattern A is shifted to the right side with respect to the inclined pattern B1.

FIG. 23B is an explanatory diagram of the states of nine correction patterns in this case.
The pattern A of each correction pattern is located on the downstream side in the movement direction (on the right side in the drawing) relative to the inclined pattern B1 of the pattern B. In addition, the inclination pattern B3 of the pattern B of each correction pattern is located on the upstream side in the movement direction (on the right side in the drawing) relative to the pattern C.

In the correction pattern with a negative number, the positional relationship between the pattern A and the pattern B is closer than that of the correction pattern (0). For this reason, in the correction patterns with negative numbers, the black lines at the boundary A1B1 and the white lines at the boundary A2B1 are reduced as compared with the correction pattern (0).
In the correction pattern with a positive number, the positional relationship between the pattern B and the pattern C is farther compared with the correction pattern (0). For this reason, in the correction pattern with a positive number, the white stripe at the boundary C1B3 and the black stripe at the boundary C2B3 are reduced as compared with the correction pattern (0).

  In each correction pattern, the pattern C is displaced to the left with respect to the inclined pattern B3 by the amount that the pattern A is displaced to the right with respect to the inclined pattern B1. For this reason, the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are most difficult to see are on the opposite side across the correction pattern (0). In other words, the correction pattern (0) is positioned between the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are hard to see. For example, in the drawing, the correction pattern (−4) in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern (+4) in which the boundary C1B3 and the boundary C2B3 are most difficult to see are sandwiched by the correction pattern (0). On the other side. As the difference in the ink ejection speeds of the nozzles is larger, the correction pattern that is most difficult to see the boundary is a correction pattern at a position away from the correction pattern (0).

  Note that black streaks occur at the boundary A1B2 of the correction pattern (−4) where the boundary A1B1 and the boundary A2B1 are most difficult to see. Further, white streaks occur at the boundary C1B2 of the correction pattern (+4) where the boundary C1B3 and the boundary C2B3 are most difficult to see. However, as will be described later, the boundary A1B2 and the boundary C1B2 are not used during inspection.

  When a DC component transport error occurs and there is a difference in the ink ejection speed of the nozzles, the state of FIG. 20B and the state of FIG. 23B are overlaid. That is, in this case, the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are the least visible are sandwiched between correction patterns having numbers corresponding to DC component transport errors. On the other side. In other words, there is a correction pattern with a number corresponding to the DC component transport error between the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are most difficult to see.

  In addition, the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see, and the correction in which the boundary C1B3 and the boundary C2B3 are most difficult to see, even when an AC component transport error occurs or there is a difference in the ink ejection speed of the nozzles. The pattern is on the opposite side across the correction pattern with the number corresponding to the DC component transport error. For this reason, even when an AC component transport error occurs and there is a difference in the ink ejection speed of the nozzles, even if the state of FIG. 21B and the state of FIG. The correction pattern in which A2B1 is most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are most difficult to see are on opposite sides of the correction pattern having the number corresponding to the DC component transport error. In other words, also in this case, the correction corresponding to the DC component transport error is intermediate between the correction pattern in which the boundaries A1B1 and A2B1 are most difficult to see and the correction pattern in which the boundaries C1B3 and C2B3 are the least visible. There is a pattern for.

  FIG. 24A is an explanatory diagram of a correction pattern of a comparative example. In the correction pattern of the comparative example, the direction of the oblique side of the inclined pattern B3 is the same as the direction of the oblique side of the inclined pattern B1.

  FIG. 24B is an explanatory diagram of the states of nine correction patterns of the comparative example. Here, for the sake of explanation, there is no conveyance error in the DC component and the AC component, and there is only a difference in the ink ejection speed of the nozzles. As shown in the drawing, in this case, the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are most difficult to see are the same. When an error between the DC component and the AC component occurs in such a state, the DC component is between the correction pattern in which the boundaries A1B1 and A2B1 are most difficult to see and the correction pattern in which the boundaries C1B3 and C2B3 are hard to see. It is not guaranteed that there is a correction pattern having a number corresponding to the transport error.

=== Test sheet inspection method ===
FIG. 25 is a flowchart of a test sheet inspection method. FIG. 26 is an explanatory diagram of a test sheet inspection procedure. Hereinafter, the test sheet inspection method of this embodiment will be described with reference to these drawings.

  First, the inspector sequentially inspects the boundary A1B1 and the boundary A2B1 located on the upper part of the correction pattern (downstream in the transport direction) from the left correction pattern (see S121 in FIG. 25 and circle 1 in FIG. 26). In the correction pattern (−8) to be inspected first, white streaks occur at the boundary A1B1, and black streaks occur at the boundary A2B1. Then, the white stripe on the boundary A1B1 and the black stripe on the boundary A2B1 are reduced as the correction pattern on the right side of the correction pattern (−8). Note that the state of the boundary A1B2 (boundary along the moving direction) is ignored when the upper boundary of the correction pattern is inspected.

  Then, the inspector selects an optimum boundary A1B1 and correction pattern for the boundary A2B1 (see S122 in FIG. 25 and circle 2 in FIG. 26). Here, the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to visually recognize, that is, the correction pattern in which oblique white stripes and black stripes are difficult to see in the upper part of the correction pattern, is used for correcting the optimum boundary A1B1 and boundary A2B1. Selected as a pattern. In this case, the inspector will select the correction pattern (+2). (In the correction pattern on the right side of the correction pattern (+2), black streaks occur at the boundary A1B1 and white streaks occur at the boundary A2B1.) Even if white streaks or black streaks occur at the boundary A1B2. The determination of the optimum boundary A1B1 and boundary A2B1 is not affected at all.

  Next, the inspector inspects the boundary C1B3 and the boundary C2B3 located in the lower part of the correction pattern (upstream in the transport direction) in order from the right correction pattern (see S123 in FIG. 25 and circle 3 in FIG. 26). . In the correction pattern (+8) to be inspected first, a black streak occurs at the boundary C1B3 and a white streak occurs at the boundary C2B3. Then, the black stripe at the boundary C1B3 and the white stripe at the boundary C2B3 are reduced as the correction pattern on the left side of the correction pattern (+8). Note that when the lower boundary of the correction pattern is inspected, the state of the boundary C1B2 (boundary along the moving direction) is ignored.

  Then, the inspector selects the optimum boundary C1B3 and the correction pattern for the boundary C2B3 (see S124 in FIG. 25 and circle 4 in FIG. 26). Here, the correction pattern in which the boundary C1B3 and the boundary C2B3 are most difficult to visually recognize, that is, the correction pattern in which oblique white stripes and black stripes are difficult to see in the upper part of the correction pattern, is used for correcting the optimum boundary C1B3 and boundary C2B3. Selected as a pattern. In this case, the inspector will select the correction pattern (−6). (In the correction pattern on the left side of the correction pattern (−6), white streaks occur at the boundary C1B3 and black streaks occur at the boundary C2B3.) Note that white and black streaks occur at the boundary C1B2. However, the determination of the optimum boundary C1B3 and boundary C2B3 is not affected at all.

  Next, the inspector calculates the median value of the correction pattern number selected in S122 and the correction pattern number selected in S124 (S125). In this case, since the correction pattern (+2) is selected in S122 and the correction pattern (-6) is selected in S124, "-2" is calculated as the median value.

  This median value is a value indicating the DC component transport error. The reason why the correction pattern (−2) for the median number is different from the optimal boundary correction pattern (+2) and the correction pattern (−6) is that the AC component transport error is This is due to the influence of the ink discharge speed of the nozzle. In other words, the median value of the optimum boundary correction pattern number (+2) and the correction pattern number (−6) is the same regardless of the influence of the AC component transport error and the ink ejection speed of the nozzles. , A value indicating a DC component transport error.

Thereafter, the inspector inputs the calculated median value into an inspection computer connected to the printer. The inspection computer determines a correction value based on the input median value (S103), and records the correction value in the memory of the printer (S104). This correction value is for correcting the DC component transport error. That is, this correction value indicates the correction amount when the target transport amount is 1.25 inches for one rotation of the transport roller.
Thereby, the correction value suitable for each printer is recorded in the memory of each printer for each printer manufactured in the manufacturing factory.

  When printing is performed under the user who purchased the printer, the controller 60 corrects the target transport amount for one rotation of the transport roller based on the correction value, and transports based on the corrected target transport amount. Process. As a result, the paper is transported according to the target transport amount, so that the quality of the printed image is improved.

<Inspection method of comparative example>
FIG. 27 is an explanatory diagram of the inspection procedure of the comparative example. In the comparative example, in S123 of the above-described inspection method flow, inspection is performed in order from the left instead of from the right (see circle 3 in the figure). Here, since the AC component transport error is slightly smaller than in FIG. 26, the correction pattern (0) and the correction pattern (+2) are determined when determining the upper boundary A1B1 and the boundary A2B1 of the correction pattern. It is in a state where judgment of superiority or inferiority cannot be made between. Similarly, when determining the lower boundary C1B3 and the boundary C2B3 of the correction pattern, it is in a state in which superiority or inferiority cannot be determined between the correction pattern (−6) and the correction pattern (−4).

  At this time, the direction of the judgment order of the upper boundary of the correction pattern (see circle 1 in the figure) and the direction of the judgment order of the lower boundary of the correction pattern (see circle 3 in the figure) When they are matched, the selected correction pattern is shifted to the left, and the correction pattern (0) and the correction pattern (-6) are selected. As a result, the median value is calculated as “−3”, which is greatly evaluated on the minus side with respect to the actual DC component transport error.

  Therefore, in this embodiment, the upper boundary of the correction pattern is inspected in order from the left in S121, and the lower boundary of the correction pattern is inspected in order from the right in S123, and the inspection order of both is reversed. . Thereby, the median value corresponding to the actual DC component transport error can be calculated. That is, the correction pattern in which the boundary A1B1 and the boundary A2B1 are most difficult to see and the correction pattern in which the boundary C1B3 and the boundary C2B3 are most difficult to see are on the opposite side across the correction pattern having the number corresponding to the DC component transport error. In this embodiment, the median value corresponding to the actual DC component transport error can be calculated by inspecting the boundary between the two in order from the opposite direction.

=== Other Embodiments ===
The above-described embodiment is mainly described for a printer. Among them, a printing apparatus, a recording apparatus, a liquid ejection apparatus, a printing method, a recording method, a liquid ejection method, a printing system, a recording system, and a computer system are included. Needless to say, the disclosure includes a program, a storage medium storing the program, a method for producing a printed material, and the like.

  Moreover, although the printer etc. as one embodiment were demonstrated, said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

<About boundary inspection>
In the above-described embodiment, each boundary of the correction pattern is inspected by an inspector in an inspection process at a printer manufacturing factory. However, the user who purchased the printer may inspect each boundary of the correction pattern by causing the printer to print a test sheet.
A human may be used instead of inspecting each boundary of the correction pattern. For example, the test sheet may be read with a scanner. Further, the controller 60 may inspect the test sheet using the optical sensor 54 provided on the carriage 31 of the printer.

<Regarding the shape of the correction pattern 1>
In the above-described embodiment, the inclined pattern B1 and the inclined pattern B3 are integrally formed as the pattern B. However, it is not limited to such a correction pattern. For example, the inclined pattern B1 and the inclined pattern B3 may be formed separately without forming the rectangular pattern B2.

<About the shape of the correction pattern 2>
In the above-described embodiment, two boundaries (boundary A1B1 and boundary A2B1) are formed between the pattern A and the pattern B, and the relationship between the upstream and downstream in the transport direction of the two patterns is reversed at the two boundaries. ing.
However, it is not limited to this. For example, the inverted trapezoid pattern A2 of the pattern A may be eliminated and the boundary between the pattern A and the pattern B may be one. Further, the trapezoidal pattern C2 of the pattern C may be eliminated, and the boundary between the pattern B and the pattern C may be one. Even in such a case, when the positional relationship between the two patterns changes, one of the white stripes or the black stripes is generated, and the boundary state can be inspected based on this.

<Regarding the shape of the correction pattern 3>
In the above-described embodiment, the boundary between the pattern A and the pattern B is a direction that intersects the transport direction and the movement direction. However, it is not limited to such a correction pattern.

FIG. 28A is an explanatory diagram of a correction pattern according to another embodiment.
This correction pattern A is formed by nozzle # 76 to nozzle # 87 in two passes and is composed of 24 raster lines of 160/360 inches. The pattern B is formed by two passes by the nozzle # 13 to the nozzle # 75, and is composed of 124 raster lines, similarly to the rectangular pattern B2. Pattern C is formed by nozzles # 1 to # 12 in two passes and is composed of 24 raster lines of 160/360 inches.
In this correction pattern, a boundary is formed between the pattern A formed by the nozzles on the upstream side in the transport direction and the upper part of the pattern B formed by the nozzles on the downstream side in the transport direction. In this correction pattern, a boundary is formed between the lower part of the pattern B formed by the nozzles on the upstream side in the transport direction and the pattern C formed by the nozzles on the downstream side in the transport direction.

FIG. 28B is an explanatory diagram of nine correction patterns according to this embodiment. The interval between the pattern A and the pattern C of each correction pattern differs depending on the correction pattern number. Further, the position of the pattern B in the transport direction moves up and down due to the AC component transport error.
Even for such a correction pattern, a correction pattern having an optimum boundary between the pattern A and the pattern B is selected, and a correction pattern having an optimum boundary between the pattern B and the pattern C is selected. If the intermediate value of the selected correction pattern number is calculated, the intermediate value becomes a value indicating the DC component transport error. In this case, the correction pattern (−4) and the correction pattern (0) are selected, the intermediate value is calculated as “−2”, and the correction value corresponding to this value is stored in the memory of the printer. It will be.

=== Summary ===
(1) In the above-described embodiment, the circumferential length of the transport roller is 1.25 inches, and the length of the nozzle row in the transport direction is 0.75 inches (1/120 inches × 90). For this reason, when forming a correction pattern for correcting the target carry amount corresponding to one rotation of the carry roller, the two patterns formed before and after the correction process corresponding to the target carry amount are formed apart from each other. (See FIG. 10A). For this reason, a boundary cannot be formed between the two patterns, and the interval between the two patterns cannot be determined.

  Therefore, in this embodiment, the controller 60 of the printer first transports paper (an example of a medium) to a predetermined position in the transport direction, and uses pattern A (first) by nozzles # 76 to # 87 on the upstream side in the transport direction. One example of one pattern) is formed (see FIG. 10B, FIG. 14, FIG. 15, and FIG. 18). Next, the controller 60 transports the paper in the transport direction with a target transport amount equivalent to about 0.625 inches shorter than the length of the nozzle row in the transport direction (see FIGS. 10B, 14 and 18). Note that the target carry amount at this time varies depending on the correction pattern. Then, the controller 60 forms an inclined pattern B1 that forms a boundary with the pattern A by the nozzles # 1 to # 12 on the downstream side in the carrying direction, and the inclined pattern B3 by the nozzles # 76 to # 87 on the upstream side in the carrying direction. As a result, the pattern B is formed (see FIGS. 10B, 14, 16, and 18). Thereafter, the controller 60 sets the target transport amount corresponding to about 0.625 inch shorter than the length in the transport direction of the nozzle row so that the total transport amount after forming the pattern A is about 1.25 inches. The paper is transported in the transport direction (see FIGS. 10B, 14 and 18). Then, the controller 60 forms a pattern C that forms a boundary with the inclined pattern B3 by the nozzles # 1 to # 12 on the downstream side in the transport direction (see FIGS. 10B, 14, 17, and 18).

  In the test sheet correction pattern thus created, the boundary A1B1 and the boundary A2B1 are formed between the pattern A and the inclined pattern B1, and the boundary C1B3 and the boundary C2B3 are formed between the pattern C and the inclined pattern B3. It is formed (see FIGS. 14 and 19). When the inspector transports the paper with a target transport amount (target transport amount corresponding to one rotation of the transport roller) longer than the length of the nozzle row in the transport direction based on such a boundary state. Can be detected (see FIGS. 19 and 20B). Further, based on such a boundary state, the inspector corrects a target transport amount (target transport amount corresponding to one rotation of the transport roller) longer than the length of the nozzle row in the transport direction. Can be determined.

(2) The above-described embodiment is particularly effective when the paper is transported by rotating the transport roller and the length of the nozzle row in the transport direction is shorter than the circumferential surface of the transport roller 23. is there.
However, the effect of the present embodiment is not limited to this. For example, the conveyance roller may be a belt shape instead of a cylindrical shape. Further, the length of the nozzle row in the transport direction may be longer than the circumferential surface of the transport roller. Even in such a case, it is possible to form a correction pattern suitable for correcting a target transport amount that is longer than the length of the nozzle row in the transport direction.

(3) In the above-described embodiment, the target transport amount to be corrected corresponds to one rotation of the transport roller 23. Thus, even when an AC component transport error occurs, the positional relationship between the pattern A and the pattern C is not affected by the rotational position of the transport roller 23 when the pattern A is formed. For this reason, according to such a correction pattern, even when an AC component transport error occurs, a correction value for correcting the DC component transport error can be determined.
However, the target transport amount to be corrected is not limited to this. For example, the target carry amount to be corrected may be 1.5 rotations of the carry roller 23. Even in such a case, if no AC component transport error occurs, a correction value for correcting the DC component transport error can be determined.

(4) In the above-described embodiment, the conveyance amount of the conveyance process performed from the formation of the pattern A to the formation of the pattern B corresponds to the half rotation of the conveyance roller 23. As a result, the conveyance amount of the conveyance process performed from the formation of the pattern B to the formation of the pattern C also corresponds to the half rotation of the conveyance roller 23. As a result, the boundary between the pattern A and the pattern B and the boundary between the pattern B and the pattern C can be formed in substantially the same shape.
However, the carrying amount of the carrying process performed from the formation of the pattern A to the formation of the pattern B is not limited to this. For example, the conveyance amount of the conveyance process performed from the formation of the pattern A to the formation of the pattern B may be larger than the half rotation of the conveyance roller 23. However, the width of the pattern A in the transport direction and the width of the inclined pattern B1 in the transport direction are shortened, and the visibility of the boundary A1B1 and the boundary A2B1 is worse than the visibility of the boundary C1B3 and the boundary C2B3.

(5) In the above-described embodiment, the nozzles that form the pattern A and the nozzles that form the inclined pattern B3 are nozzle # 76 to nozzle # 87. In the above-described embodiment, the nozzles that form the inclined pattern B1 and the nozzles that form the pattern C are nozzles # 1 to # 12. As a result, the boundary between the pattern A and the pattern B and the boundary between the pattern B and the pattern C can be formed in substantially the same shape.
However, the present invention is not limited to this. For example, the nozzles that form the pattern A may be nozzles # 76 to # 87, and the nozzles that form the inclined pattern B3 may be nozzles # 76 to # 90. However, in this case, the visibility of the boundary A1B1 and the boundary A2B1 is different from the visibility of the boundary C1B3 and the boundary C2B3. On the other hand, in consideration of calculating the median as shown by a circle 5 in FIG. 26 in this embodiment, it is desirable that the visibility of both is equal.

(6) In the above-described embodiment, the boundary between the pattern A and the pattern B and the boundary between the pattern B and the pattern C are both formed in a direction crossing the moving direction (FIGS. 12E, 12F, 13, and 14). reference). This makes it possible to stably determine the presence of black and white stripes at the boundaries even if the raster lines are not uniform in the transport direction and the intervals between the raster lines may be slightly different within each pattern. It can be carried out.
However, for example, as shown in FIG. 28, the boundary may be along the moving direction. Even in such a case, it is possible to form a correction pattern for correcting a target transport amount that is longer than the length of the nozzle row in the transport direction. However, in this case, if there is variation in the spacing between the raster lines that make up each pattern, there will be a place that looks like a white or black streak inside each pattern, so the presence of black or white streak at the boundary is determined. It becomes difficult to do.

(7) In the above-described embodiment, the directions of the boundaries A1B1 and A2B1 and the directions of the boundaries C1B3 and C2B3 intersect (see FIGS. 13 and 14). Thereby, even if there is a difference in the ink ejection speed between the nozzle on the upstream side in the transport direction and the nozzle on the downstream side in the transport direction, a correction value for correcting the transport error of the DC component can be determined.
However, for example, as shown in FIGS. 24A and 24B, the direction of the boundary between the pattern A and the pattern B and the direction of the boundary between the pattern B and the pattern C may be parallel. Even in such a case, if there is no difference in the ink discharge speed between the nozzle on the upstream side in the transport direction and the nozzle on the downstream side in the transport direction, a correction value for correcting the DC component transport error is determined. can do.

(8) It is desirable to include all the constituent elements of the above-described embodiment because all the effects can be obtained. However, if a correction pattern for correcting a target transport amount that is longer than the length of the nozzle row in the transport direction is formed, all the components of the above-described embodiment are not necessarily required.

(9) In the above-described embodiment, after the test sheet is printed, the correction value for the target carry amount is determined based on the upper boundary of the correction pattern and the lower boundary of the correction pattern. Thereby, it is possible to determine a correction value for correcting a target transport amount that is longer than the length of the nozzle row in the transport direction.

(10) In the above-described embodiment, the controller 60 forms a plurality of correction patterns, and the inspector selects the correction patterns for the optimal boundaries A1B1 and A2B1, and corrects the optimal boundaries C1B3 and C2B3. By selecting a pattern, a correction value is determined (see FIG. 25).
However, the method for determining the correction value is not limited to this. For example, if no AC component transport error occurs, the correction value can be determined based only on the correction pattern (0). Specifically, if the correction pattern (0) is in a boundary state as shown in FIG. 20A, it can be seen that the paper is being transported by a transport amount larger than the target transport amount, and therefore the target transport amount is reduced. Such a correction value can be determined.

(11) In the above-described embodiment, the correction pattern number is associated with a predetermined correction value. In the above-described embodiment, the median value of the correction pattern number selected in S122 and the correction pattern number selected in S124 is calculated (see FIG. 25), and correction is performed based on this median value. The value is determined. Thereby, even if there is a difference in AC component transport error or ink ejection speed, a correction value for correcting the DC component transport error can be determined. It is not necessarily limited to the median value. For example, if the value is between the numbers of the selected correction patterns, it is possible to correct the DC component transport error to some extent.

(12) In the above-described embodiment, first, the upper boundary of the correction pattern is inspected in order from the left correction pattern, and then the lower boundary of the correction pattern is inspected in order from the right correction pattern. (See FIGS. 25 and 26). As shown in FIG. 27, when the direction of the judgment order of the upper and lower boundaries of the correction pattern is matched, the selected correction pattern is shifted to the left, and is on the minus side with respect to the actual DC component transport error. It is because it is greatly evaluated.
However, the order of inspection is not limited to this. Even if the inspection is performed as shown in FIG. 27, it is possible to correct the DC component transport error.

(13) After determining the correction value as described above, information regarding the correction value is stored in the memory of the printer that printed the test sheet. When printing is performed by the user who purchased the printer, the controller 60 corrects the target carry amount based on the correction value, and rotates the carry roller according to the corrected target carry amount to carry the paper. To do. As a result, the paper can be transported by the transport amount corresponding to the target transport amount before correction, so that high-quality printing can be performed.

(14) In the above-described embodiment, in the inspection process of the printer manufacturing factory, the printer and the inspection computer are connected, the test sheet is printed by the printer, and the inspector inspects the test sheet and checks the inspection result. The inspection computer stores the correction value in the memory of the printer. However, it is not always necessary to connect the printer to the inspection computer if the test sheet can be printed by the printer alone without connecting the printer to the inspection computer and the inspection result can be directly input to the printer.
Instead of printing a test sheet at the printer manufacturing factory, the test sheet may be printed by the user who purchased the printer to determine the correction value.

(15) It should be noted that the above-described test sheet itself also has the effect of being able to detect a transport error when transported according to a target transport amount that is longer than the length of the nozzle row in the transport direction.

It is explanatory drawing of the whole structure of a printing system. 1 is a block diagram of an overall configuration of a printer 1. FIG. FIG. 3A is a schematic diagram of the overall configuration of the printer 1. FIG. 3B is a cross-sectional view of the overall configuration of the printer 1. It is a flowchart of the process at the time of printing. 4 is an explanatory diagram of a configuration of a transport unit 20. FIG. 6 is a graph for explaining AC component transport error. It is a flowchart of the setting process of the correction value for correct | amending a conveyance error. It is explanatory drawing of printing of the test sheet of a reference example. It is explanatory drawing of the nozzle arrangement | positioning of a head. FIG. 10A is an explanatory diagram of a problem caused by the head length being shorter than the roller circumferential surface length. FIG. 10B is an explanatory diagram of countermeasures of this embodiment for this problem. FIG. 11A is an explanatory diagram of an AC component transport error when forming each pattern. FIG. 11B is an explanatory diagram of the influence of the formation position of the pattern B due to the AC component transport error. 12A and 12B are explanatory diagrams of the vicinity of the boundary between two block patterns. 12C and 12D are explanatory diagrams of the vicinity of the boundary when the interval between raster lines varies. 12E and 12F are explanatory diagrams of measures of the present embodiment. It is explanatory drawing of the test sheet | seat of this embodiment. It is explanatory drawing of the pattern for a correction | amendment of this embodiment. FIG. 6 is an explanatory diagram of a pattern A printing method. FIG. 10 is an explanatory diagram of a pattern B printing method. FIG. 10 is an explanatory diagram of a pattern C printing method. It is explanatory drawing of the printing method of a test sheet. It is explanatory drawing of the state of the pattern for a correction | amendment when a conveyance error has neither a DC component nor an AC component. FIG. 20A is an explanatory diagram of the state of the correction pattern (0) when the paper is transported with a transport amount larger than the target transport amount. FIG. 20B is an explanatory diagram of the states of nine correction patterns in this case. FIG. 21A is an explanatory diagram of the state of the correction pattern (0) when an AC component error occurs. FIG. 21B is an explanatory diagram of the states of nine correction patterns in this case. It is explanatory drawing of the ink discharge speed Vm of each nozzle. FIG. 23A is an explanatory diagram of the state of the correction pattern (0) when the ink discharge speed Vm is different. FIG. 23B is an explanatory diagram of the states of nine correction patterns in this case. FIG. 24A is an explanatory diagram of a correction pattern of a comparative example. FIG. 24B is an explanatory diagram of the states of nine correction patterns of the comparative example. It is a flowchart of the inspection method of a test sheet. It is explanatory drawing of the test procedure of a test sheet. It is explanatory drawing of the test | inspection procedure of a comparative example. FIG. 28A is an explanatory diagram of a correction pattern according to another embodiment. FIG. 28B is an explanatory diagram of nine correction patterns according to this embodiment.

Explanation of symbols

1 printer,
20 transport unit, 21 paper feed roller, 22 transport motor (PF motor),
23 transport roller, 24 platen, 25 discharge roller,
30 Carriage unit, 31 Carriage,
32 Carriage motor (CR motor),
40 head units, 41 heads,
50 detector groups, 51 linear encoder, 52 rotary encoder,
521 scale, 522 detector,
53 Paper detection sensor, 54 Optical sensor,
60 controller, 61 interface unit, 62 CPU,
63 memory, 64 unit control circuit 100 printing system, 110 computer, 120 display device,
130 input device, 140 recording / reproducing device,
A1 trapezoid pattern, A2 reverse trapezoid pattern,
B1 inclined pattern, B2 rectangular pattern, B3 inclined pattern,
C1 reverse trapezoid pattern, C2 trapezoid pattern

Claims (24)

A medium to be printed is transported by a transport roller, and a predetermined pattern is printed by ejecting ink from a nozzle array having a plurality of nozzles in the transport direction and moving in a direction crossing the transport direction. A method for inspecting a transport error caused by the transport roller whose length is longer than the length of the nozzle row in the transport direction,
Forming a first pattern on the medium by ejecting ink from a nozzle on the upstream side in the transport direction of the nozzle row at an arbitrary rotation position of the transport roller;
A second pattern is formed so as to form a boundary with the first pattern of the medium by ejecting ink from a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by one rotation or less from the rotation position. And forming a third pattern on the medium by ejecting ink from nozzles on the upstream side in the transport direction of the nozzle row,
The fourth pattern is formed on the medium so as to form a boundary with the third pattern by a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by about one rotation from a rotational position where the first pattern is formed. By forming into
A conveyance error detection pattern including the first, second, third, and fourth patterns is formed.
The rotation angle of the conveying roller from the rotation position for forming the first pattern to the rotation position for forming the second pattern, and the rotation angle from the rotation position for forming the first pattern to the rotation position for forming the fourth pattern. Form a pattern for detecting multiple transport errors with different angles,
A transport error of the medium by the transport roller is inspected according to a boundary state between the first pattern, the second pattern, the third pattern, and the fourth pattern in the plurality of inspection patterns. Inspection method. It is the inspection method of the conveyance error according to claim 1,
The detection pattern is formed such that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern are in a direction intersecting the transport direction and the movement direction. Inspection method of transport error. The inspection method for transport error according to claim 2,
The detection pattern is formed such that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern intersect with each other. Method. A method for inspecting a conveyance error according to any one of claims 1 to 3,
A transport error inspection method, wherein a transport amount of the medium performed between the formation of the first pattern and the formation of the second pattern corresponds to approximately half a rotation of the transport roller. A method for inspecting a conveyance error according to any one of claims 1 to 3,
Forming the third pattern with a nozzle for forming the first pattern;
A transport error inspection method, wherein the fourth pattern is formed by a nozzle for forming the second pattern. A medium to be printed is transported by a transport roller, and a predetermined pattern is printed by ejecting ink from a nozzle array having a plurality of nozzles in the transport direction and moving in a direction crossing the transport direction. A method of determining a correction value for a transport error by the transport roller whose length is longer than the length of the nozzle row in the transport direction,
Forming a first pattern on the medium by ejecting ink from a nozzle on the upstream side in the transport direction of the nozzle row at an arbitrary rotation position of the transport roller;
A second pattern is formed so as to form a boundary with the first pattern of the medium by ejecting ink from a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by one rotation or less from the rotation position. And forming a third pattern on the medium by ejecting ink from nozzles on the upstream side in the transport direction of the nozzle row,
The fourth pattern is formed on the medium so as to form a boundary with the third pattern by a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by about one rotation from a rotational position where the first pattern is formed. By forming into
A conveyance error detection pattern including the first, second, third, and fourth patterns is formed.
The rotation angle of the conveying roller from the rotation position for forming the first pattern to the rotation position for forming the second pattern, and the rotation angle from the rotation position for forming the first pattern to the rotation position for forming the fourth pattern. Form a pattern for detecting multiple transport errors with different angles,
The conveyance error correction value is determined by determining a conveyance error correction value by the conveyance roller according to a boundary state between the first pattern, the second pattern, the third pattern, and the fourth pattern in the inspection pattern. How to determine the value. A method for determining a correction value for a transport error according to claim 6,
The detection pattern is formed such that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern are in a direction intersecting the transport direction and the movement direction. A method for determining a correction value for a transport error. A method for determining a correction value for a transport error according to claim 7,
The detection pattern is formed so that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern intersect with each other. How to determine the value. A method for determining a correction value for a transport error according to any one of claims 6 to 8,
A first inspection pattern is selected from the plurality of inspection patterns based on a boundary state between the first pattern and the second pattern, and a boundary between the third pattern and the fourth pattern The second correction pattern is selected based on the state of
A method for determining a correction value for a transport error, wherein a correction value is determined based on the first and second inspection patterns. A method for determining a correction value for a transport error according to any one of claims 6 to 8,
A method for determining a correction value for a transport error that corrects a value between a correction value corresponding to the first inspection pattern and a correction value corresponding to the second inspection pattern. A method for determining a correction value for a transport error according to any one of claims 6 to 8,
A plurality of inspection patterns are arranged such that a rotation angle from a rotation position for forming the first pattern of the transport roller to a rotation position for forming the second pattern, and the fourth pattern from the rotation position for forming the first pattern. Formed in the moving direction in order of the rotation angle to the rotation position to be formed,
Based on the inspection direction when selecting the first inspection pattern based on the state of the boundary between the first pattern and the second pattern, and the state of the boundary between the third pattern and the fourth pattern A method for determining a correction value for a transport error, wherein a correction value is determined by inspecting an inspection direction in selecting the second inspection pattern from the same direction. A method for determining a correction value for a transport error according to any one of claims 6 to 8,
A plurality of inspection patterns are arranged such that a rotation angle from a rotation position for forming the first pattern of the transport roller to a rotation position for forming the second pattern, and the fourth pattern from the rotation position for forming the first pattern. Formed in the moving direction in order of the rotation angle to the rotation position to be formed,
Based on the inspection direction when selecting the first inspection pattern based on the state of the boundary between the first pattern and the second pattern, and the state of the boundary between the third pattern and the fourth pattern A method for determining a correction value for a transport error, wherein a correction value is determined by inspecting an inspection direction when selecting the second inspection pattern from a reverse direction. A medium to be printed is transported by a transport roller, and a predetermined pattern is printed by ejecting ink from a nozzle array having a plurality of nozzles in the transport direction and moving in a direction crossing the transport direction. A printing method for determining a correction value of a transport error by the transport roller whose length is longer than the length of the nozzle row in the transport direction, correcting the error by the correction value, and transporting the medium,
Forming a first pattern on the medium by ejecting ink from a nozzle on the upstream side in the transport direction of the nozzle row at an arbitrary rotation position of the transport roller;
A second pattern is formed so as to form a boundary with the first pattern of the medium by ejecting ink from a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by one rotation or less from the rotation position. And forming a third pattern on the medium by ejecting ink from nozzles on the upstream side in the transport direction of the nozzle row,
The fourth pattern is formed on the medium so as to form a boundary with the third pattern by a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by about one rotation from a rotational position where the first pattern is formed. By forming into
A conveyance error detection pattern including the first, second, third, and fourth patterns is formed.
The rotation angle of the conveying roller from the rotation position for forming the first pattern to the rotation position for forming the second pattern, and the rotation angle from the rotation position for forming the first pattern to the rotation position for forming the fourth pattern. Form a pattern for detecting multiple transport errors with different angles,
In the inspection pattern, a correction value for a conveyance error by the conveyance roller is determined according to a boundary state between the first pattern, the second pattern, the third pattern, and the fourth pattern, and the error is corrected by the correction value. And printing the medium. The printing method according to claim 13, comprising:
The detection pattern is formed such that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern are in a direction intersecting the transport direction and the movement direction. Printing method. The printing method according to claim 14, comprising:
The printing method, wherein the detection pattern is formed so that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern intersect with each other. A transport unit having a transport roller for transporting a medium to be printed; a plurality of nozzle arrays that are arranged in the transport direction and move in a direction intersecting the transport direction; and a controller that performs control for ejecting ink from the nozzle arrays. Provided, and the length of the circumferential surface of one rotation of the transport roller is longer than the length of the nozzle row in the transport direction,
The controller is
Forming a first pattern on the medium by ejecting ink from a nozzle on the upstream side in the transport direction of the nozzle row at an arbitrary rotation position of the transport roller;
A boundary with the first pattern of the medium is formed by ejecting ink from a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by one rotation or less from a rotational position where the first pattern is formed. And forming a third pattern on the medium by ejecting ink from nozzles on the upstream side in the transport direction of the nozzle row,
By forming a fourth pattern on the medium so as to form a boundary with the third pattern by a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by approximately one rotation from the rotation position.
A pattern for detecting a transport error including the first, second, third, and fourth patterns is formed.
The rotation angle of the conveying roller from the rotation position for forming the first pattern to the rotation position for forming the second pattern, and the rotation angle from the rotation position for forming the first pattern to the rotation position for forming the fourth pattern. A printing system, wherein the conveyance roller and the nozzle row are controlled so as to form a plurality of conveyance error detection patterns having different angles. The printing system according to claim 16, comprising:
The detection pattern is formed such that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern are in a direction intersecting the transport direction and the movement direction. And printing system. The printing system according to claim 16, comprising:
The printing system according to claim 1, wherein the detection pattern is formed so that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern intersect with each other. A test sheet to be printed is transported by a transport roller, and a predetermined pattern is printed by ejecting ink from a nozzle array having a plurality of nozzles in the transport direction and moving in a direction intersecting the transport direction. A method for producing a test sheet for inspecting a transport error by the transport roller, wherein the length of the peripheral surface is longer than the length of the nozzle row in the transport direction,
Forming a first pattern on the test sheet by ejecting ink from a nozzle on the upstream side in the transport direction of the nozzle row at an arbitrary rotational position of the transport roller;
A boundary with the first pattern of the test sheet is formed by ink ejection from a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by one rotation or less from a rotational position where the first pattern is formed. Forming the second pattern as described above, and forming the third pattern on the test sheet by ejecting ink from the nozzles on the upstream side in the transport direction of the nozzle row,
By forming a fourth pattern on the test sheet so as to form a boundary with the third pattern by a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by about one rotation from the rotation position. ,
A conveyance error detection pattern including the first, second, third, and fourth patterns is formed.
The rotation angle of the conveying roller from the rotation position for forming the first pattern to the rotation position for forming the second pattern, and the rotation angle from the rotation position for forming the first pattern to the rotation position for forming the fourth pattern. A test sheet manufacturing method, comprising: forming a plurality of conveyance error detection patterns with different corners. A test sheet manufacturing method according to claim 19,
The detection pattern is formed such that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern are in a direction intersecting the transport direction and the movement direction. A test sheet manufacturing method. A method for producing a test sheet according to claim 20,
The test pattern is formed so that the boundary between the first pattern and the second pattern and the boundary between the third pattern and the fourth pattern intersect with each other. Method. A predetermined pattern is printed by ejecting ink from a nozzle row that is transported by a transport roller and has a plurality of nozzles in the transport direction and moves in a direction crossing the transport direction, and has a length of the circumference of one rotation. A test sheet used to inspect a transport error by the transport roller, which is longer than the length of the nozzle row in the transport direction,
A first pattern is formed by ink ejection from the nozzles on the upstream side in the transport direction of the nozzle row at an arbitrary rotational position of the transport roller,
A second boundary is formed so as to form a boundary with the first pattern by ejecting ink from a nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by one rotation or less from a rotational position where the first pattern is formed. A pattern is formed, and a third pattern is formed by ink ejection from the nozzles upstream in the transport direction of the nozzle row,
By forming a fourth pattern so as to form a boundary with the third pattern by the nozzle on the downstream side in the transport direction of the nozzle row at a position where the transport roller is rotated by about one rotation from the rotation position,
A conveyance error detection pattern including the first, second, third, and fourth patterns is formed.
The rotation angle of the conveying roller from the rotation position for forming the first pattern to the rotation position for forming the second pattern, and the rotation angle from the rotation position for forming the first pattern to the rotation position for forming the fourth pattern. A test sheet, wherein a plurality of detection patterns with different corners are formed. The test sheet according to claim 22,
The detection pattern is formed such that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern are in a direction intersecting the transport direction and the movement direction. Test sheet. The test sheet according to claim 23, wherein
The test sheet is characterized in that the detection pattern is formed so that a boundary between the first pattern and the second pattern and a boundary between the third pattern and the fourth pattern intersect with each other.