JP2011152688A - Adjustment method of liquid ejector and calculation method of correction value - Google Patents

Abstract

An object of the present invention is to increase the productivity of a liquid ejection apparatus by efficiently setting a correction value.
(A) Each time a transport roller for transporting a medium is rotated by a predetermined amount of rotation, a liquid is discharged to form a plurality of adjustment patterns on the medium, and based on the adjustment pattern,
(B) calculating a plurality of correction values that are correction values for correcting a target transport amount when transporting the medium and are associated with relative positions of the medium and a head that records on the medium; Obtaining a reference correction value based on the plurality of correction values; (C) applying the reference correction value to a liquid ejection apparatus in a mass production stage; and (D) applying the reference correction value. An adjustment method for a liquid discharge apparatus, comprising: forming the adjustment pattern using a liquid discharge apparatus, and updating the reference correction value based on the adjustment pattern.
[Selection] Figure 25

Description

  The present invention relates to a liquid ejection apparatus adjustment method and a correction value calculation method.

Inkjet printers that perform printing by discharging ink are used. In such a printer, a slight manufacturing error may be included between the design time and the manufactured product. In order to cope with the manufacturing error, it is considered to eliminate the manufacturing error by printing a test pattern with a printer and setting a correction value obtained based on the test pattern in the printer 1.

Japanese Patent Laid-Open No. 2-54676

However, with such a method, formation and reading of test patterns and calculation of correction values have to be performed for all printers, which has been a factor in reducing production efficiency. Therefore, even when a correction value is set in the printer, it is desirable to increase the productivity by performing it efficiently.

The present invention has been made in view of such circumstances, and an object thereof is to increase the productivity of a liquid ejection apparatus by efficiently setting a correction value.

The main invention for achieving the above object is:
(A) discharging a liquid each time a conveying roller for conveying a medium is rotated by a predetermined amount of rotation;
Forming a plurality of adjustment patterns on the medium;
Based on the adjustment pattern, a plurality of correction values for correcting a target transport amount when the medium is transported, which are associated with relative positions of the medium and a head for recording on the medium. Calculating,
(B) obtaining a reference correction value based on the plurality of correction values;
(C) applying the reference correction value to the liquid ejection device in the mass production stage;
(D) using the liquid ejection apparatus to which the reference correction value is applied, forming the adjustment pattern, and updating the reference correction value based on the adjustment pattern;
Is a method for adjusting a liquid ejection apparatus including

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

1 is a block diagram of the overall configuration of a printer. FIG. 2A is a schematic diagram of the overall configuration of the printer 1, and FIG. 2B is a cross-sectional view of the overall configuration of the printer 1. FIG. 4 is an explanatory diagram showing the arrangement of nozzles on the lower surface of a head 41. 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 graph (conceptual diagram) of a transport error that occurs when transporting a paper having a size of 101.6 mm × 152.4 mm (4 inches × 6 inches). It is a flowchart until it determines the correction value for correct | amending conveyance amount. FIG. 8A to FIG. 8C are explanatory diagrams of how the correction value is determined. It is explanatory drawing of the mode of printing of the pattern for a measurement. FIG. 10A is a longitudinal sectional view of the scanner 150, and FIG. 10B is a top view of the scanner 150 with the top cover 151 removed. It is a graph of the error of the reading position of a scanner. 12A is an explanatory diagram of the reference sheet SS, and FIG. 12B is an explanatory diagram showing a state in which the test sheet TS and the reference sheet SS are set on the document table glass 152. FIG. It is a flowchart of the correction value calculation process in S103. It is explanatory drawing of a division | segmentation (S131) of an image. FIG. 15A is an explanatory diagram showing how the inclination of the image of the measurement pattern is detected, and FIG. 15B is a graph of the gradation values of the extracted pixels. It is explanatory drawing of the mode of the detection of the inclination at the time of printing of the pattern for a measurement. It is explanatory drawing of the margin amount X. FIG. FIG. 18A is an explanatory diagram of an image range used when calculating the position of the line, and FIG. 18B is an explanatory diagram of calculation of the position of the line. It is explanatory drawing of the position of the calculated line. It is explanatory drawing of calculation of the absolute position of the i-th line of the pattern for a measurement. It is explanatory drawing of the range to which correction value C (i) respond | corresponds. It is explanatory drawing of the table memorize | stored in the memory 63. FIG. It is explanatory drawing of the correction value in a 1st case. It is explanatory drawing of the correction value in a 2nd case. It is explanatory drawing of the correction value in a 3rd case. It is explanatory drawing of the correction value in a 4th case. It is a flowchart explaining the adjustment method of the correction value in a development stage. It is a flowchart explaining the adjustment method of the correction value in a mass production stage. It is a figure explaining the pattern for confirmation.

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

(A) discharging a liquid each time a conveying roller for conveying a medium is rotated by a predetermined amount of rotation;
Forming a plurality of adjustment patterns on the medium;
Based on the adjustment pattern, a plurality of correction values for correcting a target transport amount when the medium is transported, which are associated with relative positions of the medium and a head for recording on the medium. Calculating,
(B) obtaining a reference correction value based on the plurality of correction values;
(C) applying the reference correction value to the liquid ejection device in the mass production stage;
(D) using the liquid ejection apparatus to which the reference correction value is applied, forming the adjustment pattern, and updating the reference correction value based on the adjustment pattern;
Of adjusting a liquid ejection apparatus including
By doing so, it is possible to efficiently set the correction value and increase the productivity of the liquid ejection apparatus.

In this liquid ejection apparatus adjustment method, it is preferable that the reference correction value is an average value of correction values associated with relative positions of the medium and the head. Preferably, applying the reference correction value to the liquid ejection apparatus in the mass production stage includes storing the reference correction value in a memory of the liquid ejection apparatus in the mass production stage. Further, it is preferable that the reference correction value is updated every certain number of liquid ejection devices among the plurality of liquid ejection devices in the mass production stage. Furthermore, it is preferable that the method further includes applying the reference correction value updated after the reference correction value is updated to a liquid ejection apparatus in a mass production stage.
And further, forming a confirmation pattern for confirming a result of applying the reference correction value by discharging the liquid from the liquid ejection device to which the reference correction value is applied,
The confirmation pattern is preferably composed of a plurality of rectangular patterns.
By doing so, it is possible to efficiently set the correction value and increase the productivity of the liquid ejection apparatus.

(A) discharging a liquid each time a conveying roller for conveying a medium is rotated by a predetermined amount of rotation;
Forming a plurality of adjustment patterns on the medium;
Based on the adjustment pattern, a plurality of correction values for correcting a target transport amount when the medium is transported, which are associated with relative positions of the medium and a head for recording on the medium. Calculating,
(B) obtaining a reference correction value based on the plurality of correction values;
Calculation method of correction values including
In the correction value calculation method, (C) the reference correction value is applied to a liquid ejection apparatus in a mass production stage, and (D) the liquid ejection apparatus to which the reference correction value is applied is used. And forming the adjustment pattern and updating the reference correction value based on the adjustment pattern.
By doing so, it is possible to efficiently set the correction value and increase the productivity of the liquid ejection apparatus.

=== Printer configuration ===
<Inkjet printer configuration>
FIG. 1 is a block diagram of the overall configuration of the printer 1. FIG. 2A shows the printer 1
It is the schematic of the whole structure. FIG. 2B is a cross-sectional view of the overall configuration of the printer 1. Hereinafter, a basic configuration of the printer will be described.

The printer 1 includes a transport unit 20, a carriage unit 30, a head unit 40,
It has a detector group 50 and a controller 60. The printer 1 that has received print data from the computer 110 that 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 status inside the printer 1 is monitored by a detector group 50,
The detector group 50 outputs the 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 2.
And 5. 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. 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 paper discharge roller 25 rotates in synchronization with the transport roller 23.

When the transport roller 23 transports the paper S, the paper S is transported by the transport roller 23 and the driven roller 26.
It is sandwiched between. Thereby, the posture of the paper S is stabilized. On the other hand, when the paper discharge roller 25 transports the paper S, the paper S is sandwiched between the paper discharge roller 25 and the driven roller 27. Since the discharge roller 25 is provided on the downstream side in the transport direction from the printing area, the driven roller 27 is
The contact surface with the paper S is configured to be small (see also FIG. 4). For this reason, when the lower end of the paper S passes through the transport roller 23 and the paper S is transported only by the paper discharge roller 25, the posture of the paper S tends to be unstable and the transport characteristics are also likely to change.

The carriage unit 30 moves the head in a predetermined direction (hereinafter referred to as a moving direction) (“
(Also called “scan”). The carriage unit 30 includes a carriage 31 and a carriage motor 32 (also referred to as a CR motor). The carriage 31 is
It can move back and forth in the direction of movement 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. Head unit 40
Comprises 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 rotation amount 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 that 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.

<About nozzle>
FIG. 3 is an explanatory diagram showing the arrangement of nozzles on the lower surface of the head 41. On the lower surface of the head 41, a black ink nozzle group K, a cyan ink nozzle group C, a magenta ink nozzle group M, and a yellow ink nozzle group Y are formed. Each nozzle group includes 90 nozzles that are ejection openings for ejecting ink of each color.

A plurality of nozzles of each nozzle group are arranged at a constant interval (nozzle pitch: k · D) along the transport direction.
). Here, D is the minimum dot pitch in the carrying direction (that is, the interval at the highest resolution of dots formed on the paper S). K is an integer of 1 or more. For example, when the nozzle pitch is 90 dpi (1/90 inch) and the dot pitch in the transport direction is 720 dpi (1/720 inch), k = 8.

The nozzles of each nozzle group are assigned a smaller number as the nozzles on the downstream side (# 1 to ##).
90). That is, the nozzle # 1 is located downstream of the nozzle # 90 in the transport direction.
The optical sensor 54 described above has the nozzle # located on the most upstream side with respect to the position in the paper transport direction.
90 and approximately the same position.

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.

=== Conveying error ===
<Conveying paper>
FIG. 4 is an explanatory diagram of the configuration of the transport unit 20.
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. Here, when the transport roller 23 rotates once, the paper is transported for 1 inch (that is, the circumference of the transport roller 23 is
1 inch). For this reason, when the transport roller 23 rotates 1/4, the paper is transported by 1/4 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. This 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 each time a slit provided in the scale 521 passes through the detection unit 522.
The slits provided in the scale 521 according to the rotation amount of the transport roller 23 are sequentially detected by the detection unit 52.
2, the rotation amount of the transport roller 23 is detected based on the output of the rotary encoder 52. For example, when transporting paper with a transport amount of 1 inch, it is determined that the transport roller 23 has rotated once. The controller 60 drives the carry motor 22 until the type encoder 52 detects it. 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>
By the way, 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 predetermined amount of transport error that occurs when the transport roller rotates once. The DC component transport error is considered to be caused by the fact that the circumference of the transport roller 23 differs for each printer due to manufacturing errors 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 23 rotates once. However, the actual DC component transport error varies depending on the total transport amount of paper due to the influence of paper friction and the like (described later). In other words, the actual DC component transport error varies depending on the relative positional relationship between the paper S and the transport roller 23 (or the paper S and the head 41).

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. 5 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 transport error. If you differentiate this graph,
A transport error that occurs when the transport roller is transporting at the rotational position is 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 1 /
It is conveyed by 4 inches + δ_90. However, if the transport roller 23 further rotates 1/4, -δ_9
A transport error of 0 occurs, and the paper is transported at 1/4 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 mismatch 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, the detected scale 52
When the location of 1 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 the conveyance amount increases.

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

<Conveyance error corrected in the reference example>
FIG. 6 is a graph (conceptual diagram) of a transport error that occurs when transporting a paper having a size of 101.6 mm × 152.4 mm (4 inches × 6 inches). The horizontal axis of the graph indicates the total transport amount of paper. The vertical axis of the graph indicates the transport error. The dotted line in the figure is a graph of the DC component transport error. The AC component transport error can be obtained by subtracting the dotted line value (DC component transport error) in the drawing from the solid line value (total transport error) in the diagram. The AC component transport error is almost a sine curve regardless of the total paper transport amount. On the other hand, the DC component transport error indicated by the dotted line differs depending on the total transport amount of paper due to the influence of paper friction and the like.

As already described, the AC component transport error varies depending on the location of the peripheral surface of the transport roller 23. For this reason, even if the same paper is transported, the transport roller 23 at the start of transport
Since the AC component transport error is different if the rotation position is different, the total transport error (transport error indicated by the solid line in the graph) is different. On the other hand, the DC component transport error is different from the AC component transport error and is not related to the location of the peripheral surface of the transport roller. Therefore, even if the rotational position of the transport roller 23 at the start of transport is different, the transport roller 23 The transport error (DC component transport error) that occurs when the motor rotates once is the same.

Further, when trying to correct the AC component transport error, the controller 60 needs to detect the rotational position of the transport roller 23. However, in order to detect the rotational position of the transport roller 23, it is necessary to further provide an origin sensor in the rotary encoder 52, which increases costs.
Therefore, in the correction of the carry amount of the reference example described below, the carry error of the DC component is corrected.

On the other hand, the DC component transport error varies depending on the total transport amount of the paper (in other words, the relative positional relationship between the paper S and the transport roller 23) (see the dotted line in FIG. 6). For this reason, if more correction values can be prepared according to the position in the transport direction, the transport error can be finely corrected. Therefore, in the reference example, a correction value for correcting the DC component transport error is prepared for each 1/4 inch range, not for each 1 inch range corresponding to one rotation of the transport roller 23. .

=== General Description ===
FIG. 7 is a flowchart for determining a correction value for correcting the carry amount. FIG. 8A to FIG. 8C are explanatory diagrams of how the correction value is determined. These processes are performed in the inspection process of the printer manufacturing factory. Prior to this process, the inspector connects the assembled printer 1 to the computer 110 in the factory. Computer 110 in the factory
Also, a scanner 150 is connected, and a printer driver, a scanner driver, and a correction value acquisition program are installed in advance.

First, the printer driver transmits print data to the printer 1, and the printer 1 prints a measurement pattern (corresponding to an adjustment pattern) on the test sheet TS (S101, FIG. 8).
A). Next, the inspector sets the test sheet TS on the scanner 150, and the scanner driver causes the scanner 150 to read the measurement pattern and acquire image data (S102, FIG. 8B). A reference sheet is set in the scanner 150 together with the test sheet TS, and a reference pattern drawn on the reference sheet is also read together.

Then, the correction value acquisition program analyzes the acquired image data and calculates a correction value (
S103). Then, the correction value acquisition program transmits the correction data to the printer 1 and stores the correction value in the memory 63 of the printer 1 (FIG. 8C). The correction value stored in the printer reflects the conveyance characteristics of each printer.

The printer storing the correction value is packed and delivered to the user. When the user prints an image with the printer, the printer conveys the paper based on the correction value and prints the image on the paper.

=== Printing Pattern for Measurement (S101) ===
First, the measurement pattern printing will be described. Similar to normal printing, the printer 1 alternately repeats a dot formation process for forming dots by ejecting ink from moving nozzles and a transport operation for transporting paper in the transport direction, and the measurement pattern is printed on the paper. Print on. In the following description, the dot formation process is referred to as “pass”, and the nth dot formation process is referred to as “pass n”.

FIG. 9 is an explanatory diagram of how the measurement pattern is printed. The size of the test sheet TS on which the measurement pattern is printed is 101.6 mm × 152.4 mm (4 inches × 6 inches).

On the right side of the figure, a measurement pattern printed on the test sheet TS is shown. The left rectangle in the drawing indicates the position of the head 41 in each pass (relative position with respect to the test sheet TS). For convenience of explanation, the head 41 is depicted as moving with respect to the test sheet TS, but this figure shows the relative positional relationship between the head and the test sheet TS. The test sheet TS is intermittently conveyed in the conveyance direction.

When the test sheet TS continues to be conveyed, the lower end of the test sheet TS passes through the conveyance roller 23. The position of the test sheet TS that faces the most upstream nozzle # 90 when the lower end of the test sheet TS passes the transport roller 23 is indicated by a dotted line in the drawing as an “NIP line”. That is, in the path in which the head 41 is above the NIP line in the figure, printing is performed with the test sheet TS sandwiched between the transport roller 23 and the driven roller 26 (also referred to as “NIP state”). Is called. In the drawing, in a path where the head 41 is below the NIP line, there is no test sheet TS between the transport roller 23 and the driven roller 26 (the test sheet TS is formed only by the paper discharge roller 25 and the driven roller 27). Is in a state of carrying “NIP
In this state, printing is performed.

The measurement pattern includes an identification code and a plurality of lines.
The identification code is an individual identification symbol for identifying each individual printer 1. This identification code is read together when the measurement pattern is read in S102, and is identified by the computer 110 by character recognition by OCR.
Each line is formed along the moving direction. Many lines are formed on the upper end side of the NIP line. Regarding the line on the upper end side from the NIP line, the i-th line in order from the upper end side is referred to as “Li”. In addition, on the lower end side of the NIP line,
Two lines are formed. Of the two lines on the lower end side of the NIP line, the upper end side line is called Lb1, and the lower end side line (lowermost line) is called Lb2. A specific line is formed longer than the other lines. For example, the line L1, the line L13, and the line Lb2 are formed longer than the other lines. These lines are formed as follows.

First, after the test sheet TS is conveyed to a predetermined printing start position, in pass 1, ink droplets are ejected only from the nozzle # 90, and a line L1 is formed. After pass 1, the controller 60 rotates the transport roller 23 by 1/4 to transport the test sheet TS by about 1/4 inch. After transport, in pass 2, ink droplets are ejected only from nozzle # 90, and line L2 is formed. Thereafter, the same operation is repeated, and the lines L1 to L20 are formed at intervals of about 1/4 inch. Thus, the lines L1 to L20 located on the upper end side of the NIP line are formed by the most upstream nozzle # 90 among the nozzles # 1 to # 90. Thereby, as many lines as possible can be formed on the test sheet TS in the NIP state. The lines L1 to L20 are formed only by the nozzle # 90, but in the pass for printing the identification code, the nozzle # 90 is printed when the identification code is printed.
Other nozzles are also used.

After the lower end of the test sheet TS has passed the transport roller 23, in pass n, nozzle # 9
Ink droplets are ejected from only 0, forming a line Lb1. After pass 1, the controller 60 rotates the transport roller 23 once to transport the test sheet TS by about 1 inch.
After transport, in pass n + 1, ink droplets are ejected only from nozzle # 3 to form line Lb2. If nozzle # 1 is used, the distance between line Lb1 and line Lb2 becomes very narrow (about 1/90 inch), and it becomes difficult to measure the distance between line Lb1 and line Lb2 later. . Therefore, here, the line Lb2 and the line Lb2 are formed by forming the line Lb2 using the nozzle # 3 located upstream of the nozzle # 1 in the transport direction.
To make it easier to measure.

By the way, when the test sheet TS is conveyed ideally, the line L1 to the line L2
The spacing between lines at 0 should be exactly 1/4 inch. However, if there is a conveyance error, the line interval does not become 1/4 inch. If the test sheet TS is transported more than the ideal transport amount, the line interval increases. Conversely, when the test sheet TS is transported less than the ideal transport amount, the line interval is narrowed. That is, the interval between two lines reflects a transport error in a transport process performed between a path in which one line is formed and a path in which the other line is formed. Therefore, if you measure the distance between two lines,
It is possible to measure a transport error in a transport process performed between a path in which one line is formed and a path in which the other line is formed.

Similarly, the distance between the line Lb1 and the line Lb2 is such that when the test sheet TS is transported ideally (more precisely, when the ink ejection of the nozzle # 90 and the nozzle # 3 is the same). It should be exactly 3/90 inches. However, if there is a transport error, the line spacing does not become 3/90 inches. For this reason, the distance between the line Lb1 and the line Lb2 is non-N.
It is considered that the transport error in the transport process in the IP state is reflected. For this reason, if the distance between the line Lb1 and the line Lb2 is measured, it is possible to measure the transport error in the transport process in the non-NIP state.

=== Reading Pattern (S102) ===
<Scanner configuration>
First, the configuration of the scanner 150 used for reading the measurement pattern will be described.
FIG. 10A is a longitudinal sectional view of the scanner 150. FIG. 10B is a top view of the scanner 150 with the upper lid 151 removed.

The scanner 150 includes an upper lid 151, a document table glass 152 on which the document 5 is placed, and a reading carriage 153 that moves in the sub-scanning direction while facing the document 5 through the document table glass 152.
A guide unit 154 for guiding the reading carriage 153 in the sub-scanning direction, and the reading carriage 15
3 is provided with a moving mechanism 155 for moving 3 and a scanner controller (not shown) for controlling each part in the scanner 150. The reading carriage 153 receives an exposure lamp 157 for irradiating the original 5 with light, a line sensor 158 for detecting a line image in the main scanning direction (a direction perpendicular to the paper surface in FIG. 10A), and reflected light from the original 5. An optical system 159 for guiding to the line sensor 158 is provided. A broken line inside the reading carriage 153 in the drawing indicates a locus of light.

When reading the image of the original document 5, the operator opens the upper cover 151 and places the original document 5 on the original table glass 1.
52, and the upper lid 151 is closed. The scanner controller then exposes the exposure lamp 157.
The reading carriage 153 is moved in the sub-scanning direction with the light emitted, and the line sensor 158 reads the image on the surface of the document 5. The scanner controller transmits the read image data to the scanner driver of the computer 110, whereby the computer 110 acquires the image data of the document 5.

<Reading position accuracy>
As will be described later, in the reference example, the scanner 150 reads the measurement pattern of the test sheet TS and the reference pattern of the reference sheet with a resolution of 720 dpi (main scanning direction) × 720 dpi (sub-scanning direction). For this reason, in the following description, description will be made on the assumption that an image is read at a resolution of 720 × 720 dpi.

FIG. 11 is a graph of the error in the reading position of the scanner. The horizontal axis of the graph indicates the reading position (theoretical value) (that is, the horizontal axis of the graph indicates the position (theoretical value) of the reading carriage 153). The vertical axis of the graph represents the reading position error (difference between the theoretical value of the reading position and the actual reading position). For example, when the reading carriage 153 is moved by 1 inch (= 25.4 mm), an error of about 60 μm occurs.

If the theoretical value of the reading position matches the actual reading position, a pixel that is 720 pixels away from the pixel indicating the reference position (position where the reading position is zero) in the sub-scanning direction is exactly 1 inch from the reference position. It should show an image at a distant location. However, when an error in the reading position as shown in the graph occurs, a pixel that is 720 pixels away from the pixel that indicates the reference position in the sub-scanning direction is a position that is further 60 μm away from a position that is 1 inch away from the reference position. An image will be shown.

If the slope of the graph is zero, images should be read at equal intervals every 1/720 inch. However, when the slope of the graph is positive, images are read at intervals longer than 1/720 inch. Further, when the slope of the graph is negative, images are read at intervals shorter than 1/720 inch.

As a result, even if the measurement pattern lines are formed at equal intervals, the line images on the image data do not have equal intervals in a state where there is an error in the reading position. in this way,
In a state where there is an error in the reading position, it is impossible to accurately measure the position of the line simply by reading the measurement pattern.
Therefore, in the reference example, when the test sheet TS is set and the measurement pattern is read by the scanner, the reference sheet is set and the reference pattern is also read.

<Reading measurement pattern and reference pattern>
FIG. 12A is an explanatory diagram of the reference sheet SS. FIG. 12B is an explanatory diagram showing a state in which the test sheet TS and the reference sheet SS are set on the platen glass 152.
The size of the reference sheet SS is 10 mm × 300 mm, and the reference sheet SS has a long and thin shape. In the reference sheet SS, a large number of lines are formed as reference patterns at intervals of 36 dpi. Since the reference sheet SS is repeatedly used, it is not a paper but a PET film. The reference pattern is formed with high accuracy by laser processing.

By using a jig (not shown), the test sheet TS and the reference sheet SS are set at predetermined positions on the platen glass 152. The reference sheet SS has a scanner 150 on the long side.
In other words, each line of the reference sheet SS is aligned with the sub-scanning direction of the scanner 150.
Is placed on the platen glass 152 so as to be parallel to the main scanning direction. A test sheet TS is set next to the reference sheet SS. The test sheet TS is set on the platen glass 152 so that the long side is parallel to the sub-scanning direction of the scanner 150, that is, the lines of the measurement pattern are parallel to the main scanning direction.

With the test sheet TS and the reference sheet SS set in this way, the scanner 150 reads the measurement pattern and the reference pattern. At this time, due to the influence of the error in the reading position, the image of the measurement pattern in the reading result becomes a distorted image as compared with the actual measurement pattern. Similarly, the image of the reference pattern is also distorted compared to the actual reference pattern.

Note that the image of the measurement pattern in the reading result is affected not only by the error of the reading position but also by the conveyance error of the printer 1. On the other hand, since the reference pattern is formed at equal intervals regardless of the transport error of the printer, the image of the reference pattern is affected by the error in the reading position of the scanner 150. It is not affected by the error.

Therefore, when calculating the correction value based on the measurement pattern image, the correction value acquisition program cancels the influence of the reading position error in the measurement pattern image based on the reference pattern image.

=== Calculation of Correction Value (S103) ===
Before describing the correction value calculation, the image data acquired from the scanner 150 will be described. The image data is composed of a plurality of pixel data. Each pixel data indicates the gradation value of the corresponding pixel. If the reading error of the scanner is ignored, each pixel corresponds to a size of 1/720 inch × 1/720 inch. Such a pixel as a minimum unit,
Digital image) is configured, and the image data is data indicating such an image.
FIG. 13 is a flowchart of the correction value calculation process in S103. Computer 110
Performs each process according to the correction value acquisition program. That is, the correction value acquisition program has a code for causing the computer 110 to execute each process.

<Image Division (S131)>
First, the computer 110 divides the image indicated by the image data acquired from the scanner 150 into two (S131).
FIG. 14 is an explanatory diagram of image division (S131). On the left side of the drawing, an image indicated by the image data acquired from the scanner is drawn. The divided image is drawn on the right side in the figure. In the following description, the left-right direction (horizontal direction) in the figure is called the x direction, and the up-down direction (vertical direction) in the figure is called the y direction. Each line in the reference pattern image is substantially parallel to the x direction, and each line in the measurement pattern image is substantially parallel to the y direction.
The computer 110 divides the image into two by extracting an image in a predetermined range from the read result image. By dividing the image of the reading result into two, one image shows the image of the reference pattern and the other image shows the image of the measurement pattern. The reason for dividing in this way is that the reference sheet SS and the test sheet TS may be separately inclined and set in the scanner 150, so that the inclination correction (S133) is performed separately.

<Detection of Inclination of Each Image (S132)>
Next, the computer 110 detects the inclination of the image (S132).
FIG. 15A is an explanatory diagram illustrating a state where the inclination of the image of the measurement pattern is detected. The computer 110 extracts, from the image data, the KX2th pixel from the left and the KY1st to JY pixels from the top. Similarly, the computer 110 extracts from the image data the KX3th pixel from the left and the KY1 to JY pixels from the top. Note that the parameter KX2 is set so that the pixel indicating the line L1 is included in the extracted pixels.
, KX3, KY1 and JY are set.
FIG. 15B is a graph of the gradation values of the extracted pixels. The horizontal axis indicates the position of the pixel (Y coordinate). The vertical axis indicates the gradation value of the pixel. The computer 110 obtains the center-of-gravity positions KY2 and KY3 based on the pixel data of the extracted JY pixels.
Then, the computer 110 calculates the inclination θ of the line L1 by the following equation.
θ = tan ⁻¹ {(KY2-KY3) / (KX2-KX3)}
The computer 110 detects not only the inclination of the measurement pattern image but also the inclination of the reference pattern image. Since the method of detecting the inclination of the image of the reference pattern is substantially the same as the above method, the description thereof is omitted.

<Correction of inclination of each image (S133)>
Next, the computer 110 rotates the image based on the tilt θ detected in S132, and corrects the tilt of the image (S133). The measurement pattern image is rotationally corrected based on the inclination result of the measurement pattern image, and the reference pattern image is rotationally corrected based on the inclination result of the reference pattern image.
A bilinear method is used as an algorithm for image rotation processing. Since this algorithm is well known, its description is omitted.

<Detection of tilt during printing (S134)>
Next, the computer 110 detects an inclination (skew) during printing of the measurement pattern (S134). If the lower end of the test sheet passes the transport roller when printing the measurement pattern, the lower end of the test sheet may come into contact with the head 41 and the test sheet may move.
When this happens, the correction value calculated from the measurement pattern becomes inappropriate. Therefore, it is detected whether or not the lower end of the test sheet is in contact with the head 41 by detecting the inclination at the time of printing the measurement pattern.
FIG. 16 is an explanatory diagram of how the inclination is detected when the measurement pattern is printed. First, the computer 110 determines that the left-side interval YL and the right-side interval YR in the line L1 (the top line) and the line Lb1 (the bottom line, the line formed after the lower end passes through the transport roller) Is detected. The computer 110 calculates the difference between the interval YL and the interval YR. If the difference is within the predetermined range, the computer 110 proceeds to the next process (S135). If the difference is outside the predetermined range, an error is determined.

<Calculation of margin amount (S135)>
Next, the computer 110 calculates a margin amount (S135).
FIG. 17 is an explanatory diagram of the margin amount X. The solid rectangle (outer rectangle) in the figure is S13.
3 shows an image after rotation correction. A dotted-line rectangle (inner oblique rectangle) in the figure indicates an image before rotation correction. In order to make the image after rotation correction into a rectangular shape, right-angled triangular margins are added to the four corners of the rotated image when the rotation correction processing of S133 is performed.
If the inclination of the reference sheet SS and the inclination of the test sheet TS are different, the amount of added margin is different, and the position of the measurement pattern line relative to the reference pattern is relative before and after the rotation correction (S133). It will shift to. Therefore, the computer 110
Obtains the margin amount X by the following equation, and subtracts the margin amount X from the line position calculated in S136, thereby preventing the shift of the position of the line of the measurement pattern with respect to the reference pattern.
X = (w cos θ−W ′ / 2) × tan θ

<Calculation of Line Position in Scanner Coordinate System (S136)>
Next, the computer 110 calculates the position of the reference pattern line and the position of the measurement pattern line in the scanner coordinate system (S136).
The scanner coordinate system is a coordinate system when the size of one pixel is 1/720 × 1/720 inch. The scanner 150 has a reading position error, and considering the reading position error, the corresponding actual area of each pixel data is not exactly 1/720 inch × 1/720 inch, but in the scanner coordinate system, The size of the corresponding region (pixel) of each pixel data is 1/720 × 1/720 inch. In addition, the position of the upper left pixel in each image,
The origin of the scanner coordinate system.

FIG. 18A is an explanatory diagram of an image range used when calculating the position of a line. Image data of an image in a range indicated by a dotted line in the figure is used when calculating the position of the line. FIG.
8B is an explanatory diagram of calculation of the position of the line. The horizontal axis indicates the position of the pixel in the y direction (scanner coordinate system). The vertical axis indicates the gradation value of the pixel (the average value of the gradation values of the pixels arranged in the x direction).
The computer 110 obtains the position of the peak value of the gradation value and sets a predetermined range centered on this position as the calculation range. Based on the pixel data of the pixels in this calculation range, the barycentric position of the gradation value is calculated, and this barycentric position is set as the line position.

FIG. 19 is an explanatory diagram of the calculated line positions (note that the positions shown in the figure are made dimensionless by a predetermined calculation). Although the reference pattern is composed of equally spaced lines, the positions of the calculated lines are not evenly spaced when attention is paid to the position of the center of gravity of each line of the reference pattern. This is considered to be due to the influence of the reading position error of the scanner 150.

<Calculation of absolute position of each line of measurement pattern (S137)>
Next, the computer 110 calculates the absolute position of each line of the measurement pattern (S137).
FIG. 20 is an explanatory diagram for calculating the absolute position of the i-th line of the measurement pattern. Here, the i-th line of the measurement pattern is located between the j−1th line of the reference pattern and the j-th line of the reference pattern. In the following description, the position (scanner coordinate system) of the i-th line of the measurement pattern is referred to as “S (i)”, and the position of the j-th line (scanner coordinate system) of the reference pattern is “K (j)”. " Further, the interval (interval in the y direction) between the j−1th line and the jth line of the reference pattern is called “L”, and j−1 of the reference pattern
The interval (interval in the y direction) between the i th line and the i th line of the measurement pattern is expressed as “L (i)
"

First, the computer 110 calculates the ratio H of the interval L (i) to the interval L based on the following equation.
H = L (i) / L
= {S (i) -K (j-1)} / {K (j) -K (j-1)}
By the way, since the actual reference patterns on the reference sheet SS are equally spaced, if the absolute position of the first line of the reference pattern is zero, the position of an arbitrary line of the reference pattern can be calculated. For example, the absolute position of the second line of the reference pattern is 1/36 inch. Therefore, when the absolute position of the jth line of the reference pattern is “J (j)” and the absolute position of the ith line of the measurement pattern is “R (i)”, R ( i) can be calculated.
R (i) = {J (j) −J (j−1)} × H + J (j−1)

Here, a specific procedure for calculating the absolute position of the first line of the measurement pattern in FIG. 19 will be described. First, the computer 110 determines that the first line of the measurement pattern is located between the second line and the third line of the reference pattern based on the value of S (1) (373.768667). To detect. Next, the computer 110 has a ratio H
It is calculated to be 0.40143008 (= (373.7686667-309.613250) / (469.430413-309.613250)). Next, the computer 110 calculates the absolute position R (1) of the first line of the measurement pattern.
1) is 0.98878678 mm (= 0.038928613 inch = {1/36 inch} x 0.40143008 + 1 /
36 inches).

In this way, the computer 110 calculates the absolute position of each line of the measurement pattern.

<Calculation of Correction Value (S138)>
Next, the computer 110 calculates correction values corresponding to a plurality of transport operations performed when the measurement pattern is formed (S138). Each correction value is calculated based on the difference between the theoretical line spacing and the actual line spacing.

The correction value C (i) of the transport operation performed between pass i and pass i + 1 is “6.35 mm”.
(1/4 inch, ie the theoretical distance between line Li and line Li + 1)
+1) −R (i) ”(absolute position of line Li + 1 and actual interval between lines Li). For example, the correction value C (1) of the transport operation performed between pass 1 and pass 2 is 6.3.
5 mm- {R (2) -R (1)}. In this way, the computer 110 calculates the correction value C (1) to the correction value C (19).

However, when the correction value is calculated using the lines Lb1 and Lb2 below the NIP line (upstream in the transport direction), the theoretical distance between the line Lb1 and the line Lb2 is “0.847 m.
m "(= 3/90 inches). In this way, the computer 110
The correction value Cb in the non-NIP state is calculated.

FIG. 21 is an explanatory diagram of a corresponding range of the correction value C (i). If the value obtained by subtracting the correction value C (1) from the initial target carry amount is set as the target in the carrying operation between pass 1 and pass 2 when the measurement pattern is printed, the actual value is obtained. The transport amount is exactly 1/4 inch (= 6.35)
mm). Similarly, if the measurement pattern is printed, pass n
If the value obtained by subtracting the correction value Cb from the initial target transport amount during the transport operation between the path n + 1 and the pass n + 1 is the target, the actual transport amount should be exactly 1 inch.

<Averaging correction values (S139)>
Incidentally, since the rotary encoder 52 of the reference example does not include the origin sensor, the controller 60 can detect the rotation amount of the transport roller 23 but does not detect the rotation position of the transport roller 23. For this reason, the printer 1 cannot guarantee the rotational position of the transport roller 23 at the start of transport. That is, every time printing is performed, the rotational position of the transport roller 23 at the start of transport may be different. On the other hand, the interval between two adjacent ruled lines in the measurement pattern is affected not only by the DC component transport error when transporting at 1/4 inch, but also by the AC component transport error.

Therefore, when correcting the target carry amount, if the correction value C calculated based on the interval between two ruled lines adjacent to each other in the measurement pattern is applied as it is, the carry is caused by the influence of the AC component carry error. The amount may not be corrected correctly. For example, even when a transport operation of a 1/4 inch transport amount is performed between pass 1 and pass 2 as in the case of printing a measurement pattern, the rotation position of the transport roller 23 at the start of transport is If the measurement pattern is different from the printing time, even if the target carry amount is corrected with the correction value C (1), the carry amount is not correctly corrected. if,
If the rotational position of the transport roller 23 at the start of transport differs by 180 degrees compared to when the measurement pattern is printed, the transport amount will not be corrected correctly due to the effect of transport error of the AC component.
Rather, the conveyance error may be worsened.

Therefore, in the reference example, in order to correct only the DC component transport error, a correction amount for correcting the DC component transport error by averaging four correction values C as shown in the following equation. Ca is calculated.
Ca (i) = {C (i-1) + C (i) + C (i + 1) + C (i + 2)} / 4
Here, the reason why the correction value Ca for correcting the DC component transport error can be calculated by the above equation will be described.

As described above, the correction value C (i) of the transport operation performed between pass i and pass i + 1 is “
6.35 mm "(1/4 inch, that is, the theoretical distance between the line Li and the line Li + 1) to" R (i + 1) -R (i) "(the absolute position of the line Li + 1 and the actual distance between the lines Li) Subtracted value. Then, the above equation for calculating the correction value Ca has the following meaning.
Ca (i) = [25.4 mm- {R (i + 3) -R (i-1)}] / 4
That is, the correction value Ca (i) has two lines (line Li +) that should theoretically be 1 inch apart.
3 is a value obtained by dividing a difference between an interval between 3 and the line Li-1) and 1 inch (a conveyance amount for one rotation of the conveyance roller 23) by four. In other words, the correction value Ca (i) is a value corresponding to the interval between the line Li-1 and the line Li + 3 formed after the line is formed and conveyed for 1 inch.
Therefore, the correction value Ca (i) calculated by averaging the four correction values C is not affected by the AC component transport error and is a value reflecting the DC component transport error.

The correction value Ca (2) for the transport operation performed between pass 2 and pass 3 is the correction value C (1
) To C (4) divided by 4 (average value of correction values C (1) to C (4)). In other words, the correction value Ca (2) includes the line L1 formed in pass 1 and the line L
It becomes a value corresponding to the distance from the line L5 formed in the pass 5 after the 1 is formed and conveyed for 1 inch.

In addition, when i-1 is less than or equal to zero when calculating the correction value Ca (i), the correction value C (i−
1) applies C (1). For example, the correction value Ca (1) of the transport operation performed between pass 1 and pass 2 is calculated as {C (1) + C (1) + C (2) + C (3)} / 4. Further, when i + 1 is 20 or more when calculating the correction value Ca (i), C (19) is applied to C (i + 1) for calculating the correction value Ca. Similarly, when i + 2 is 20 or more,
C (19) is applied to C (i + 2). For example, the correction amount Ca (19) of the transport operation performed between pass 19 and pass 20 is {C (18) + C (19) + C (19) + C (19)}
Calculated as / 4.

In this way, the computer 110 calculates the correction value Ca (1) to the correction value Ca (19). Thus, a correction value for correcting the DC component transport error is obtained for each 1/4 inch range.

=== Storage of Correction Value (S104) ===
Next, the computer 110 stores the correction value in the memory 63 of the printer 1 (S
104).
FIG. 22 is an explanatory diagram of a table stored in the memory 63. The correction values stored in the memory 63 are the correction values Ca (1) to Ca (19) in the NIP state and the correction value Cb in the non-NIP state. In addition, boundary position information for indicating the range to which each correction value is applied,
It is stored in the memory 63 in association with each correction value.

The boundary position information associated with the correction value Ca (i) is the measurement pattern line Li + 1.
Is a position corresponding to (theoretical position), and this boundary position information is the correction value Ca (
The boundary of the lower end side of the range which applies i) is shown. The boundary on the upper end side is the correction value Ca (
It can be obtained from the boundary position information associated with i-1). Therefore, for example, the application range of the correction value C (2) is a range between the position of the line L1 and the position of the line L2 (where the nozzle # 90 is located) with respect to the paper S. Note that since the range in which the non-NIP state is set is known, the boundary value information may not be associated with the correction value Cb.

In the printer manufacturing factory, a table reflecting individual characteristics of each printer is stored in the memory 63 for each manufactured printer. And the printer which memorize | stored this table is packed and shipped.

=== Conveying operation during printing under the user ===
When printing is performed under the user who purchased the printer, the controller 60 reads the table from the memory 63, corrects the target transport amount based on the correction value, and performs the transport operation based on the corrected target transport amount. Do. Hereinafter, the state of the conveyance operation at the time of printing under the user will be described.

FIG. 23A is an explanatory diagram of correction values in the first case. In the first case, the position of the nozzle # 90 before the transport operation (relative position with respect to the paper) matches the boundary position on the upper end side of the application range of the correction value Ca (i), and the position of the nozzle # 90 after the transport operation Corresponds to the boundary position on the lower end side of the application range of the correction value Ca (i). In such a case, the controller 60 sets the correction value to Ca (
i), and the transport motor 22 is driven to transport the paper by targeting the value obtained by adding the correction value Ca (i) to the initial target transport amount F.

FIG. 23B is an explanatory diagram of correction values in the second case. In the second case, the position of the nozzle # 90 before and after the transport operation is both within the application range of the correction value Ca (i). In such a case, the controller 60 determines the ratio F / L between the initial target transport amount F and the transport direction length L of the applicable range.
A value obtained by multiplying by Ca (i) is used as a correction value. Then, the controller 60 drives the carry motor 22 with the target value obtained by adding the correction value Ca (i) × (F / L) from the initial target carry amount F to carry the paper.

FIG. 23C is an explanatory diagram of correction values in the third case. In the third case, the position of the nozzle # 90 before the transport operation is within the application range of the correction value Ca (i), and the nozzle # 9 after the transport operation is
The position of 0 is within the application range of the correction value Ca (i + 1). Here, of the target transport amount F, the transport amount within the application range of the correction value Ca (i) is F1, and the transport amount within the application range of the correction value Ca (i + 1) is F2. In such a case, the controller 60 changes Ca (i) to F1 / L.
The sum of the value multiplied by and the value obtained by multiplying Ca (i + 1) by F2 / L is taken as the correction value. Then, the controller 60 targets the value obtained by adding the correction value from the initial target carry amount F to the carry motor 2.
2 is driven to transport the paper.

FIG. 23D is an explanatory diagram of correction values in the fourth case. In the fourth case, the correction value Ca
The paper is conveyed so as to pass through the application range of (i + 1). In such a case, the controller 60 sets the value obtained by multiplying Ca (i) by F1 / L, Ca (i + 1), and Ca (i + 2) to F2.
The sum of the value multiplied by / L is used as a correction value. Then, the controller 60 drives the carry motor 22 with the target value obtained by adding the correction value from the initial target carry amount F to carry the paper.

Thus, when the controller corrects the initial target transport amount F and controls the transport unit based on the corrected target transport amount, the actual transport amount is corrected to become the initial target transport amount F, The DC component transport error is corrected.

By the way, if the correction value is calculated as described above, when the target carry amount F is small, the correction value is also small. If the target transport amount F is small, it is considered that the transport error that occurs when the transport is performed is small. Therefore, if the correction value is calculated as described above, a correction value that matches the transport error that occurs during transport can be calculated. In addition, since the applicable range is set every ¼ inch for each correction value Ca, the DC component transport error that changes in accordance with the relative position between the paper S and the head 41 can be corrected accurately. can do.

Next, a correction value adjustment method in the present embodiment will be described. The correction value adjustment method of the present embodiment includes two stages: a development stage (or an initial stage of mass production) and a mass production stage.

FIG. 12 is a flowchart for explaining a correction value adjustment method in the development stage. FIG.
3 is a flowchart for explaining a correction value adjustment method in the mass production stage. Hereinafter, the correction value adjustment method in the present embodiment will be described with reference to these flowcharts.
First, in the development stage, the correction value determination process described above is performed for a plurality of printers in the development stage, and correction values corresponding to each boundary position information are acquired. For this purpose, the correction value acquisition target printer 1 is connected to the computer 110 via the interface 61 (S20).
2).

Next, the above-described correction value determination process (FIG. 7) is performed (S204). Thereby, a correction value table as shown in FIG. 22 is acquired, and the correction value is stored in the memory 63 of the printer 1. Further, these acquired correction values are also stored in the memory of the computer 110 (S206).

Next, the flow (S
202-S206) is determined (S208). If there is a sampling target printer that has not yet performed the above flow, step S2
Returning to 02, the above flow (S202 to S20) is performed for other sampling target printers.
6) is carried out. By doing in this way, the correction value corresponding to each boundary position information about the plurality of printers 1 in the development stage can be stored in the computer 110.

On the other hand, if it is determined in step S208 that the above-described flow has been performed for all the printers to be sampled in the development stage, the default correction value (the reference correction value is set to the reference correction value) is then determined based on the accumulated correction value. (Corresponding) is calculated (S210). In the present embodiment, the default correction value is an average value of correction values for each of the relative positions of the head and the paper for the plurality of printers 1. In other words, an average value of correction values for each boundary position information is obtained. For example, the correction value C for the theoretical position corresponding to L2
Although a (1) is stored in the memory of the computer 110 as many as the number of printers to be sampled, the average value of these correction values Ca (1) is obtained for the theoretical position corresponding to L2. Similarly, average values are obtained for the correction values Ca (2) to Ca (19) and Cb, respectively. Each correction value is associated with the corresponding boundary position information to be a default correction value.

By doing this, while setting the correction value for each printer in the development stage,
These average correction values can be obtained.

Thus, when the default correction value is obtained based on the printer in the development stage, the correction value of the printer in the mass production stage is set. In the mass production stage, the correction value is obtained for all the printers based on the measurement pattern as described above, and the correction value is not stored in the printer. If this is done for all printers, man-hours increase in the manufacturing process. Therefore, the correction value determination process is performed for several printers manufactured in the mass production process and the correction values are stored in the printer. For other printers, the already determined default correction values are used. Is to be stored. Further, the already determined default correction value is updated with the correction value obtained by the correction value determination process performed every several units.
Specifically, the following operations are performed.

In the mass production stage, first, it is determined whether or not adjustment by the correction value determination process is performed (S302). For example, in the present embodiment, correction value determination processing is performed at a ratio of one for every 100 units, correction values are obtained and adjustment is performed, and the remaining 99 printers are adjusted using default correction values. To be done. At this time, when a serial number is assigned to each printer, it may be determined that, for example, only the last two digits of “01” are adjusted by performing correction value determination processing.

If it is determined in step S302 that adjustment using the test pattern is not performed (
99 out of 100 are targeted), and the default correction value is stored in the printer (
S304).

Then, after the default correction value is stored in the printer, it is determined whether or not the printer can achieve the target level of image quality (S310). Whether or not the target level of image quality has been achieved can be determined again by printing a confirmation pattern and visually checking the confirmation pattern to determine whether or not an appropriate target conveyance amount has been conveyed.

FIG. 26 is a diagram for explaining a confirmation pattern. The confirmation pattern is composed of a plurality of rectangular patterns as shown in the figure. For example, the head moves in the moving direction of the head,
Ink is ejected from nozzles for a certain color. At this time, nozzle # 1 to nozzle # 45
When ink is ejected from all the nozzles, a pattern having a width of 0.5 inch can be formed. Then, after the transport roller is rotated 0.5 inch as the target transport amount,
When ink is ejected from nozzles # 1 to # 45, a 0.5 inch wide pattern can be formed. Thereafter, after the conveying roller is rotated 0.1 inch as a target conveying amount, a pattern is printed by the same operation as described above.

When the rectangular patterns formed in this way overlap each other, only an amount shorter than 0.5 inch is actually conveyed with respect to a target conveyance amount of 0.5 inch.
On the other hand, when these rectangular patterns are formed apart from each other, the actual transport amount is larger than 0.5 inches with respect to the target transport amount of 0.5 inches. Thus, by visually observing these rectangular patterns, it is possible to determine whether or not an appropriate target transport amount has been transported.

Here, the determination is made visually, but it is also possible to read these confirmation patterns using a scanner or the like and make the above determination based on the read data.

In step 310, when the target transport amount is within the specified error range and the image quality has achieved the predetermined target level, this flow ends. On the other hand, if the image quality has not achieved the predetermined target level, step S306 is performed.
Also, in the case where adjustment by the correction value determination process is performed in step S302, step S306 is performed.

In step S306, the correction value determination process described above is performed. The obtained correction value is stored in the memory 63 of the printer 1. Next, the obtained correction value is used, the default correction value is updated, and the updated correction value is stored in the computer 110 (S
308). As a correction value updating method in the present embodiment, the correction value acquired this time is added to the correction value acquired in the development stage for each correction value corresponding to the boundary position information, and an average of these is obtained. Then, this value is stored in the computer as a future default density correction value.
Thereafter, step S310 is executed, but since this has already been described, description thereof is omitted.

By doing this, it is possible to set a default correction value for each printer in the mass production stage, so that it is not necessary to perform correction value determination processing for all printers, thereby improving printer productivity. Can do. Furthermore, the correction value is obtained by performing the above correction value determination process every two or more units, and the default correction value is updated using this correction value. Therefore, the default correction value conforms to the printer in the mass production stage. It can be.

=== Other Embodiments ===
In the above-described embodiment, the printer 1 has been described as the liquid ejecting apparatus. However, the present invention is not limited to this, and other fluids (liquids, liquids in which particles of functional materials are dispersed, gels, and the like) are not limited thereto. Such a fluid can also be embodied in a liquid ejection device that ejects or ejects the fluid. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, gas vaporizer, organic EL manufacturing apparatus (especially polymer EL manufacturing apparatus), display manufacturing apparatus, film formation You may apply the technique similar to the above-mentioned embodiment to the various apparatuses which applied inkjet technology, such as an apparatus and a DNA chip manufacturing apparatus. These methods and manufacturing methods are also within the scope of application.
The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present 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 the head>
In the above-described embodiment, ink is ejected using a piezoelectric element. However, the method for discharging the liquid is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

1 printer, 110 computer,
20 transport unit, 21 paper feed roller, 22 transport motor, 23 transport roller,
24 platen, 25 paper discharge roller, 26 driven roller, 27 driven roller,
30 Carriage unit, 31 Carriage, 32 Carriage motor,
40 head units, 41 heads,
50 detector groups, 51 linear encoders,
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,
150 scanner, 151 top cover, 152 platen glass,
153 reading carriage, 154 guide section, 155 moving mechanism,
157 exposure lamp, 158 line sensor, 159 optical system,
TS test sheet, SS reference sheet

Claims (8)

(A) discharging a liquid each time a conveying roller for conveying a medium is rotated by a predetermined amount of rotation;
Forming a plurality of adjustment patterns on the medium;
Based on the adjustment pattern, a plurality of correction values for correcting a target transport amount when the medium is transported, which are associated with relative positions of the medium and a head for recording on the medium. Calculating,
(B) obtaining a reference correction value based on the plurality of correction values;
(C) applying the reference correction value to the liquid ejection device in the mass production stage;
(D) using the liquid ejection apparatus to which the reference correction value is applied, forming the adjustment pattern, and updating the reference correction value based on the adjustment pattern;
Of adjusting a liquid ejection apparatus including The liquid ejection apparatus adjustment method according to claim 1, wherein the reference correction value is an average value of correction values associated with respective relative positions of the medium and the head. 3. The liquid ejection according to claim 1, wherein applying the reference correction value to the liquid ejection apparatus in the mass production stage includes storing the reference correction value in a memory of the liquid ejection apparatus in the mass production stage. Device adjustment method. The method for adjusting a liquid ejection device according to claim 1, wherein updating the reference correction value is performed every certain number of liquid ejection devices among the plurality of liquid ejection devices in the mass production stage. . The liquid ejection device adjustment method according to claim 1, further comprising applying the updated reference correction value to the liquid ejection device in a mass production stage after updating the reference correction value. further,
Discharging the liquid from the liquid ejection device to which the reference correction value is applied, and forming a confirmation pattern for confirming the result of applying the reference correction value,
The method for adjusting a liquid ejection apparatus according to claim 1, wherein the confirmation pattern includes a plurality of rectangular patterns. (A) discharging a liquid each time a conveying roller for conveying a medium is rotated by a predetermined amount of rotation;
Forming a plurality of adjustment patterns on the medium;
Based on the adjustment pattern, a plurality of correction values for correcting a target transport amount when the medium is transported, which are associated with relative positions of the medium and a head for recording on the medium. Calculating,
(B) obtaining a reference correction value based on the plurality of correction values;
Calculation method of correction values including further,
(C) applying the reference correction value to the liquid ejection device in the mass production stage;
(D) using the liquid ejection apparatus to which the reference correction value is applied, forming the adjustment pattern, and updating the reference correction value based on the adjustment pattern;
The correction value calculation method according to claim 7 including: