JP5358166B2 - Method for adjusting conveyance mechanism of image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that even though a transport mechanism of a recording medium of an image formation device is manufactured in the same specification, an adjustment is necessary since there exists an individual difference due to a working tolerance, an attachment error and the like. <P>SOLUTION: The difference between an adjustment amount of the transport part due to the individual difference occurring in a manufacture of a transport direction-adjustment mechanism and the actual transport direction is calculated as a conversion coefficient of an amount of a change to correct the actual adjustment amount. By this way, a proper adjustment is executed in every image formation device, and the transport direction of a recording medium coincides with the direction of the image formation position of a recording head. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for adjusting a conveyance mechanism of a line type image forming apparatus in which a recording head is fixed.

  2. Description of the Related Art Generally, as an image forming apparatus that forms an image by ejecting ink droplets, a so-called inkjet printer, a recording head having a nozzle row length equal to or larger than the recording medium width in a direction orthogonal to the recording medium conveyance direction (recording medium width direction) Line head printers and page printers are known. These recording heads include a recording head having one nozzle row exceeding the recording medium width and a recording head in which a plurality of short recording heads less than the recording medium width are arranged in the width direction of the recording medium. An image forming apparatus that moves the recording head in the width direction of the recording medium with respect to the line head printer is called a serial head printer.

  For example, as described in Patent Document 1, a line head printer (line type image forming apparatus) has an advantage that an image can be recorded at a high speed because there is no need to move the recording head as compared with a serial head printer. On the other hand, since the head position is fixed in the line head printer, the dot recording position (ink landing position) does not change even when the recording medium is inclined.

  This feature includes a problem that uneven color tends to occur when an image is formed by overlapping ink droplets of two or more colors (heavy color printing). As an example, consider a case where two colors of ink droplets are ejected to the same position on a recording medium to form a single dot of heavy color. In a line head printer, if there is a deviation between the straight line connecting two different nozzles that eject ink droplets of two colors and the conveyance direction of the recording paper, there is always a gap between the two color dots on which the image is formed. A landing position deviation proportional to sin θ of the angle between the line segment between the two color nozzles and the straight line in the recording paper conveyance direction occurs.

For this reason, angle adjustment in the recording medium conveyance direction with respect to the arrangement of the recording head after installation or movement of the image forming apparatus or after maintenance or repair after installation is very important for a line head printer. It becomes adjustment. For this reason, most line head printers are provided with a mechanism for adjusting the recording medium conveyance direction with respect to the arrangement of the recording heads (conveyance direction adjusting mechanism).
JP 2005-205828 A

  Even if the above-described line type image forming apparatus is an apparatus manufactured to the same specifications with the same design drawing, there are individual differences due to processing tolerances by the processing apparatus, errors during assembly, and the like. This individual difference also causes a unique machine difference in the conversion coefficient between the adjustment amount by the conveyance direction adjustment mechanism and the actual change amount in the recording paper conveyance direction in the conveyance direction adjustment mechanism.

  In order to cope with the individual differences in the conversion coefficient of the image forming apparatus, a method for calibrating the conveyance direction adjusting mechanism before adjusting the recording medium conveyance direction and an approximation coefficient ignoring the individual differences between the image forming apparatuses. Is used to determine the relationship between the amount of adjustment by the transport direction adjusting mechanism and the amount of change in the actual recording paper transport direction.

  The former method results in an increase in adjustment work in the manufacturing process of the image forming apparatus, resulting in an increase in production cost and production time. Similarly, even in the latter method, if the individual difference of the conveyance direction adjustment mechanism increases, the adjustment error at the time of adjustment of the conveyance angle increases. Therefore, it is necessary to strictly define the processing tolerance of the conveyance direction adjustment mechanism in advance. It led to an increase in cost.

  Accordingly, the present invention provides an image in which the recording medium conveyance direction can be adjusted in the correct direction by adjusting individual differences in the relationship between the adjustment mechanism adjustment amount in the recording medium conveyance direction of the manufactured image forming apparatus and the actual conveyance direction change amount. It is an object of the present invention to provide a method for adjusting a transport mechanism of a forming apparatus.

  In order to achieve the above object, an embodiment according to the present invention provides a conveyance direction adjustment method of a conveyance unit.

  According to the present invention, the recording medium conveyance direction can be adjusted to the correct direction by adjusting the individual difference in the relationship between the adjustment mechanism adjustment amount of the recording medium conveyance direction of the manufactured image forming apparatus and the actual conveyance direction change amount. An adjustment method of a conveyance mechanism of an image forming apparatus can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
The concept of the adjustment method of the conveyance mechanism of the image forming apparatus of the present invention will be described. FIG. 1 is a diagram schematically illustrating a configuration of an ink jet image forming apparatus for realizing a method for adjusting a conveyance mechanism of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating an arrangement relationship between the recording head and the transport mechanism in the image forming apparatus.

  The image forming apparatus 1 mainly includes a plurality of recording heads 10 provided with an upstream ink port 10b and a downstream ink port 10c, a transport unit 30a such as a transport belt, and a transport direction adjusting mechanism 30b. 30 and an ink circulation path 2 for supplying ink to each recording head 10 while circulating the ink.

  The recording head 10 according to the present embodiment includes, for example, a C ink recording head 10d and a K ink recording head assigned to each of four colors (cyan: C, black: K, magenta: M, yellow: Y). 10e, an M ink recording head 10f, and a Y ink recording head 10g.

  These recording heads 10 are short heads in which the nozzle row length (the width of image formation by the nozzles arranged in a row) is less than the width of the recording medium 31, and the plurality of recording heads 10 are arranged in the width direction of the recording medium 31. In addition, the nozzle row length exceeds the width of the recording medium 31, and as shown in FIG.

  In the present embodiment, six short recording heads are arranged in a staggered manner to enable image formation that is greater than the width of the recording medium 31. Of course, one recording head having a length exceeding the width of the recording medium 31 may be used. The recording head 10 ejects ink supplied from the ink circulation path 2 through a plurality of nozzles 10a by driving an actuator constituted by a piezoelectric element. The nozzle 10a forms an image by ejecting ink in the vertical direction on the recording medium 31 conveyed by the conveyance mechanism 30 and passing through the opposite position based on an ejection signal synchronized with the conveyance speed.

  The ink circulation path 2 includes an upstream ink supply path 2a for supplying ink to the recording head 10, and a downstream ink return path 2b for returning the ink discharged from the recording head 10 to the ink supply path (upstream sub tank 15) 2a. Consists of.

  The ink supply path 2a is provided above the nozzle 10a in the gravity direction, and connects the upstream sub tank 15 for supplying ink from the upstream ink port 10b to the recording head 10, and the recording head 10 (upstream ink port 10b) and the upstream sub tank 15. A tube 16a to be supplied, an ink bottle 19 for supplying ink to the upstream sub tank 15, a tube 18 connecting the upstream sub tank 15 and the ink bottle 19 via a valve 20b, and ink supply control for controlling opening and closing of the valve 20b. And a liquid level sensor 20 a provided in the upstream sub tank 15. The upstream air release valve 15 a opens the inside of the upstream sub tank 15 to the atmosphere.

  The ink supplied into the recording head 10 from the ink supply path 2a through the upstream ink port 10b is discharged from the nozzle 10a, and the ink that has not been discharged is discharged from the downstream ink port 10c to the ink return path 2b.

  The ink return path 2b is provided below the nozzle 10a in the gravitational direction, and a downstream sub tank 11 that temporarily stores ink discharged from the downstream ink port 10c without being used by the recording head 10, and the recording head 10 (downstream). A tube 16b connecting the ink port 10c) and the downstream sub tank 11, a pressure regulator 17 and a downstream atmospheric release valve 11a provided in the downstream sub tank 11, a downstream atmospheric release valve 11a provided in the downstream sub tank 11, and the downstream sub tank 11 And the upstream sub-tank 15, a circulation pump 12 and a temperature regulator 13 provided on the path of the tube 16 c, and a filter 14 for removing foreign matters in the circulating ink.

  The ink flowing through the ink circulation path 2 passes through the tube 16a from the upstream sub tank 15 and is supplied to the recording head 10 from the upstream ink port 10b. The ink that has not been ejected from the nozzle 10a is discharged from the downstream ink port 10c, and flows into the downstream sub tank 11 through the tube 16b. The ink in the downstream sub tank 11 is sucked up by the circulation pump 12 and returns to the upstream sub tank 15 through the tube 16c.

  At this time, the ink is adjusted to a temperature suitable for image formation by the temperature adjuster 13 in the process of flowing through the tube 16c. Whether the circulating ink has a temperature suitable for image formation is determined based on the ink temperature measured by the temperature sensor 21. Further, impurities in the ink are filtered by the filter 14 in the process of circulating the ink. The liquid level height of the downstream sub-tank 11 is always maintained at an appropriate level by the liquid level adjuster 11b.

  The head drive controller 50 controls the drive conditions of the recording head 10. The downstream sub-tank 11 is provided with a downstream air release valve 11a for opening the internal space to the atmosphere and a pressure regulator 17 for adjusting the pressure inside the tank. At the time of image formation, the downstream air release valve 11a is open and the internal space is at atmospheric pressure, but the inside of the downstream sub tank 11 can also be sealed by closing this.

  The position of the downstream sub-tank 11 is determined so that an appropriate pressure for image formation is applied to the nozzle 10a due to the water head difference between the downstream sub-tank 11 and the nozzle 10a when the inside of the downstream sub-tank 11 is maintained at atmospheric pressure. When the downstream atmosphere release valve 11a seals the downstream sub tank 11, the pressure regulator 17 is provided in the downstream sub tank 11 so that the pressure applied to the nozzle 10a becomes an appropriate pressure for image formation regardless of the presence or absence of ink circulation. Adjust the air pressure.

  The downstream atmosphere release valve 11a is provided with a filter (not shown) to prevent foreign matters from entering the ink supply path 2 through the downstream atmosphere release valve 11a. A liquid level adjuster 11b is provided at the end of the tube 16c on the downstream sub tank 11 side, and controls the amount of ink flowing from the downstream sub tank 11 toward the tube 16c.

  The liquid level adjuster 11b can use, for example, a floating member that narrows the outlet channel to the tube 16c when the liquid level decreases. When the circulation pump 12 circulates ink at a constant pressure, when the liquid level in the downstream sub-tank 11 is lowered, the floating member that is the liquid level adjuster 11b is lowered, and the outlet flow path to the tube 16c is narrowed. This increases the flow path resistance when the circulation pump 12 sucks ink from the downstream sub tank 11. As a result, the amount of ink sucked from the downstream sub-tank 11 per unit time decreases, and the ink level in the downstream sub-tank 11 rises due to the ink flowing from the recording head 10 side. Thus, even if the liquid level in the downstream sub-tank 11 fluctuates temporarily, it returns to a certain height due to the effect of the liquid level adjuster 11b. As a result, when ink is ejected from the nozzle 10a, the ink in the upstream sub tank 15 is reduced and the liquid level is lowered.

  Further, an upstream atmosphere release valve 15 a that can communicate with the atmosphere is provided at the upper portion of the upstream sub tank 15. The upstream sub-tank 15 is provided with a liquid level sensor 20a for detecting the liquid level height, and the liquid level in the tank is always appropriate in order to maintain an appropriate head value for ink ejection. It is kept at a height. This is because the ink supply controller 20c opens the valve 20b when the liquid level sensor 20a detects a drop in the liquid level in the upstream sub tank 15. Ink is supplied to the upstream sub tank 15 from the ink bottle 19 through the tube 18 from the opening of the valve 20b.

  A filter (not shown) provided in the upstream atmosphere release valve 15a prevents foreign matter from entering the ink supply path 2 through the upstream atmosphere release valve 15a. A valve 20b is provided on the path of the tube 18, and the valve 20b is closed except when the upstream sub tank 15 is replenished with ink from the ink bottle 19.

  When the apparatus is in operation, the inside of the ink bottle 19 is maintained at atmospheric pressure by the atmospheric communication pipe 19 a provided in the ink bottle 19. The upstream atmosphere release valve 15a, the downstream atmosphere release valve 11a, the pressure regulator 17 and the circulation pump 12 are controlled by the circulation controller 21 according to the ink circulation state.

  At the time of ink circulation, the upstream atmosphere release valve 15a is opened, the downstream atmosphere release valve 11a is closed, and the pressure regulator 17 is arranged to adjust the atmospheric pressure in the downstream sub tank 11 so that the ink liquid pressure at the nozzle 10a becomes an appropriate pressure at the time of image formation. Adjust. When the ink is not circulated, the upstream atmosphere release valve 15a is opened and the downstream atmosphere release valve 11a is closed. As described above, at this time, the ink hydraulic pressure in the nozzle 10a is the proper printing pressure. Since the ink circulation circulates through the inside of the recording head 10, the heat generated by driving the recording head 10 is taken away by the ink, and the temperature rise of the recording head 10 is suppressed. Further, air bubbles and foreign matters clogged in the recording head 10 are removed by ink circulation. By these functions, the image forming apparatus 1 can form an image for a long time without deteriorating the recording quality.

A procedure for recording an image on the recording medium 31 by the image forming apparatus 1 will be described below.
First, the transport mechanism 30 receives a recording medium 31 supplied from a recording medium supply unit (not shown), corrects the posture, and then transports the recording medium 31. The transport direction of the transport unit 30 a is adjusted so as to be orthogonal to the nozzle row direction of the recording head 10 by a transport direction adjusting mechanism 30 b described later. The recording head 10 is driven based on a driving condition instructed by the control unit 50, and ejects ink onto the recording medium 31 that passes through a facing position that is approximately 2 mm away from the nozzle 10a. At this time, the transport mechanism 30 forms an image on the recording medium 31 by the recording head 10 ejecting ink based on the ejection signal synchronized with the transport speed for transporting the recording medium 31.

The recording medium 1 on which the image is formed is transferred from the transport mechanism 30 to a discharge mechanism (not shown) and stored in a storage tray or a sorter.
The transport direction adjusting mechanism 30b in the present embodiment includes, for example, a scale and a pointer that indicate a set value of the angle of the transport unit 30a with respect to the recording head 10, and an eccentric pin that is connected to the pointer and changes the angle of the transport unit 30a. Then, when the eccentric pin is rotated, the pointer is linearly displaced on the scale, and the angle of the transport unit 30a changes smoothly. As an adjustment method, the adjuster changes the direction of the transport unit 30a by rotating the eccentric pin while looking at the scale pointed by the pointer. By this adjustment, the conveyance direction of the recording medium 31 is matched with the direction between the nozzles of the two recording heads 10 (for example, the C ink recording head 10d and the Y ink recording head 10g). The adjustment result is confirmed by actually forming a line or the like on the recording medium.

  In the present embodiment, by using a conveyance direction adjustment method to be described later, the relationship between the adjustment amount of the conveyance direction adjustment mechanism 30b and the actual conveyance direction change amount with respect to the conveyance mechanism in the initial state is related to the presence or absence of individual differences in the image forming apparatus. First, the conveyance direction of the recording medium 31 is adjusted to an appropriate direction by two adjustment operations.

  Next, with reference to FIGS. 3A, 3B, 4 and 5A, 5B, the procedure, operation, and operation of the transport direction adjusting method in the transport mechanism of the image forming apparatus of the present embodiment will be described. The effect will be described. FIGS. 3A and 3B are diagrams for explaining the dot position deviation of ink landing due to the difference between the conveyance direction of the recording medium 31 by the conveyance unit 30a and the direction between the nozzles of the recording head. FIG. 4 is a flowchart for explaining the adjustment procedure of the conveyance direction adjustment method in the present embodiment. FIGS. 5A and 5B are diagrams for explaining the transport direction adjusting method in the present embodiment.

  First, the relationship between the carrying direction and the dot position will be described with reference to FIGS. FIGS. 3A and 3B conceptually show an arrangement example in which the recording head 10 and the conveyance unit 30a shown in FIG.

  Here, the direction A is determined by the arrangement of the recording heads 10. In the present embodiment, the plurality of recording heads 10 are arranged in an alternating staggered pattern so as to face one direction. The direction B is the recording medium transport direction in the transport unit in the initial state at the time of shipment or repair completion, or the recording medium transport direction during the adjustment work by the transport direction adjusting mechanism 30b. Has an angle difference θ1.

  Here, the ideal conveyance direction (hereinafter referred to as direction A or adjustment completion direction) for completing the adjustment is determined by the arrangement direction (nozzle row direction) of the recording heads 10, and the conveyance direction of the recording medium in the conveyance unit It is. In the example of the embodiment described below, for example, all the recordings held by the head holding member 40 in order to land an ink droplet at a desired dot position in the transport direction when an image is recorded on the recording medium 31. In the plane where the nozzles 10 a provided in the head 10 exist, the direction is perpendicular to the direction of the nozzle rows between the recording heads 10 (all nozzle rows are in the same direction).

  In other words, when the transport mechanism forms a line by ejecting ink droplets from one nozzle of the recording head of each ink color aligned in a straight line in the adjustment completion direction, the transport mechanism is in a direction that matches the adjustment completion direction. When the recording medium is conveyed to form each ink color line, ink droplets of all colors are overlapped to form dots on the same line. Note that the direction A or the adjustment completion direction is basically one direction, but in actual adjustment, a certain range (angle difference) based on design specifications is allowed.

  3A and 3B, the recording head 10 is installed in the order of the C ink recording head 10d, the K ink recording head 10e, the M ink recording head 10f, and the Y ink recording head 10g in order from the upstream in the transport direction. ing. FIG. 3B focuses on one nozzle 10h of the C ink recording head 10d and the nozzle 10i of the Y ink recording head 10g in the adjustment completion direction in the recording head arrangement shown in FIG. 3A. In this case, the relationship between the dot formation positions formed by the nozzles 10i and the dot positions formed by the nozzles 10h is shown.

  In FIG. 3B, the nozzle interval L0 indicates the distance between the nozzle 10h and the nozzle 10i. Since the head drive control unit 50 drives all the recording heads 10 at an appropriate timing, if the conveyance direction (direction B) of the recording medium is the direction A [adjustment completion direction], the dots ejected from the nozzles 10h and 10i Lands at the same position on the recording medium.

However, in reality, the conveyance direction of the recording medium 31 is the direction B, and when there is an angle difference θ1 between the adjustment completion direction and the dot ejected from the nozzle 10h and the dot ejected from the nozzle 10i. , There is a distance L2 measured perpendicular to the direction B. The following formula 1-1 is established between the distance L0 determined by the installation position of the recording head 10 and the distance L2 between the dot formation positions of the two colors of ink.
L2 = L0 × sin θ1 (Formula 1-1)
By using this relationship, it is possible to obtain information regarding the transport direction at that time from the dot formation position. Also in the information regarding the conveyance direction, the angle difference θ1 is suggested here.

  Next, with reference to FIG. 4 and FIGS. 5 (a) and 5 (b), a conveyance direction adjusting method that is a feature of this embodiment will be described. Note that the direction A [adjustment completion direction], the direction B [recording medium conveyance direction], and the angle difference θ1 shown in FIGS. 5A and 5B correspond to the direction and angle difference shown in FIG.

First, the concept of the conveyance direction adjustment method in the present embodiment will be described.
The adjustment angle of the conveyance unit 30a by the conveyance direction adjustment mechanism 30b has a width (adjustment limit point) of a certain adjustment angle on both the left and right sides with the adjustment completion direction as the center, for example. Here, as shown in FIG. 5A, the adjustment limit point is assumed to be a lower limit upper limit (limit of change in the conveyance angle) of an adjustable range by an eccentric pin of the conveyance direction adjustment mechanism 30b (not shown). The aforementioned angle difference θ1 is between the adjustment completion direction and the adjustment limit point.

  Therefore, by rotating the eccentric pin and adjusting the conveying unit 30a from the angle difference θ1 beyond the direction A (the center of the swing width) until reaching the adjustment limit point in the opposite direction C, the eccentric pin For the adjustment amount 1, the angle difference θ1 and the adjustment angle θ2 from the direction A to the adjustment limit point can be obtained.

  From these relationships, the unit adjustment amount of the eccentric pin with respect to the unit angle at which the transport unit 30a rotates can be obtained. As an example, the number of rotations of the introduction screw for rotating the eccentric pin, which is necessary for changing the unit angle at which the transport unit 30a rotates, for example, 0.1 degree, is one rotation. Here, if it is assumed that the adjustment angle θ2 is 2 degrees, a movement amount (movement distance) necessary for adjustment can be obtained by rotating the introduction screw 20 times. Therefore, if the conveyance unit 30a is adjusted with the obtained movement amount, the conveyance direction rotates so as to return from the direction C of the adjustment limit point θ0 to the direction A, and the conveyance direction of the conveyance unit 30a and the adjustment completion direction are changed. Will match.

Hereinafter, the conveyance direction adjustment method will be described in detail.
[Procedure 1: S1 to S3]
First, after the image forming apparatus is installed (newly installed or moved) or repair of the transport mechanism is completed, a test image (for example, two stripe patterns) is formed on the recording medium 31 in an unadjusted state of the transport mechanism. (Step S1). The test image to be formed is not particularly limited as long as the distance L2 described with reference to FIG. In addition, the test image includes a pattern in which C ink dots and Y ink dots are kept at a certain distance and spread on a recording medium, or a pattern in which a plurality of straight lines are drawn in the transport direction by C ink and Y ink. Can be considered.

Next, the landing of each ink color in the test image formed on the recording medium 31 is analyzed (step S2). In this landing analysis, a test image formed with an image can be read and analyzed by a scanner, or a test image can be observed by a microscope or a magnifier. Such an analysis is performed, the distance L2 is obtained, and the angle difference θ1 (corresponding to the “first angle difference” in the claims) is calculated based on the above-described equation 1-1.
The calculated angle difference θ1 is set as the latest value (determination criterion) of the transport direction adjusting mechanism 30b and is stored in the external adjustment computer or the memory of the control unit 50 (step S3).

  Next, the external adjustment computer or control unit 50 determines whether or not the obtained angle difference θ1 is within a predetermined allowable angle difference θ0 from 0 (the adjustment completion direction A coincides with the conveyance direction). Determine (step S4). If it is determined in this determination that the angle difference θ1 is within the range of 0 to the allowable angle difference θ0 (YES), the conveyance direction adjustment is unnecessary, and the adjustment operation is terminated. On the other hand, when the angle difference θ1 exceeds the allowable angle difference θ0 in this determination (NO), the conveyance direction adjustment described below is necessary. Here, it is assumed that the transport mechanism 30 has not been adjusted, and the transport direction (angle difference θ1) in the transport unit 30a is in the direction B as shown in FIG.

[Procedure 2: S5 to S7]
First, the conveyance direction adjusting mechanism 30b is operated to change the conveyance direction of the conveyance unit 30a from the position of the angle difference θ1 in the direction B to the adjustment limit point on the opposite side beyond the direction A, thereby conveying the recording medium in the conveyance direction. (Step S5). By this operation, the adjustment amount 1 is adjusted, the conveyance direction reaches the adjustment limit point, and reaches the direction C.
Next, the same test image as described above is formed on the recording medium 31 transported by the transport direction adjusting mechanism 30b (step S6). The landing of the imaged test pattern is analyzed (step S7). By this landing analysis, an angle difference θ2 (corresponding to the “second angle difference” in the claims) from the adjustment completion direction A to the adjustment limit point direction C is obtained. In the present embodiment, the operation is performed so that the adjustment amount of the conveyance direction adjustment mechanism 30b is increased. By this operation, the amount of change in the transport direction (the swing width of the transport unit) also increases, so the amount of change in the difference between the landing positions of C ink dots and Y ink dots also increases.

  When the adjustment amount and the change amount increase as described above, the influence of the adjustment error, the landing position observation error, the accidental change in the transport direction, and the like becomes relatively small, and the accuracy of the analysis increases. Therefore, even when the angle difference θ1 is small, it is desirable to change it to the adjustment limit point, and the angle difference based on the maximum possible adjustment amount can be obtained, so that the adjustment accuracy can be improved.

[Procedure 3: S8]
Next, a return adjustment amount 2 (corresponding to the “first adjustment amount” in the claims) for returning the conveyance direction of the conveyance unit 30a from the adjustment limit point to the adjustment completion direction is calculated (step S8). The conveyance direction of the conveyance unit 30a is moved from the direction B to the direction C (adjustment limit angle) by performing the adjustment operation of the adjustment amount 1 described above. The angle θ3 moved by the adjustment amount 1 at this time is the sum of the angle difference θ1 and the angle difference θ2. A conversion coefficient C1 (corresponding to the “first conversion coefficient” in the claims) is obtained from the adjustment amount 1 and the angle θ3 (angle difference θ1 + angle difference θ2). An adjustment amount 2 is calculated by multiplying the calculated conversion coefficient C1 by the angle difference θ2.

Therefore, by using the values of the angle difference θ1, the angle difference θ2, and the adjustment amount 1, a conversion coefficient C1 between the adjustment amount of the conveyance direction adjustment mechanism 30b in the image forming apparatus 1 and the actual conveyance angle change amount is obtained. . The conversion coefficient C1 is obtained by the following formula.
Conversion coefficient C1 = adjustment amount 1 / (angle difference θ1 + angle difference θ2) (Formula 1-2)
When the conversion coefficient C1 is obtained, the adjustment amount 2 executed from the angle difference θ2 can be calculated using the following equation.
Adjustment amount 2 = angle difference θ2 × conversion coefficient C1 (Formula 1-3)
[Procedure 4: S9]
Next, an adjustment operation with the adjustment amount 2 is performed on the conveyance direction adjustment mechanism 30b, and the conveyance direction (direction C) of the conveyance unit 30a is returned from the adjustment limit point to the direction A where adjustment is completed (step S9).
As described above, according to the present embodiment, the conveyance direction adjustment causes the conveyance direction of the recording medium 31 by the conveyance unit 30a and the adjustment completion direction to be the same direction, the accuracy of the landing positions of the respective color inks is increased, and color misregistration is caused. No high quality can form an image.

  Furthermore, by calculating the difference between the adjustment amount in the transport unit due to individual differences that occur during the manufacture of the transport direction adjustment mechanism and the actual transport direction as a conversion factor for the change amount, and correcting the actual adjustment amount, Appropriate adjustment is performed for each image forming apparatus, and the conveyance direction of the recording medium can coincide with the direction A depending on the image forming position of the recording head, and a high-quality image without color misregistration can be formed.

  Further, by calculating the above-described conversion factor for the change amount from the adjustment amount that is as large as possible within the operable range, it is possible to suppress the influence of errors that occur in landing analysis and conveyance angle adjustment. This makes it possible to obtain a substantial adjustment amount with high accuracy. In the above-described embodiment, calculation formulas are presented for the examples of the direction and angle difference shown in FIGS. 5A and 5B in order to easily understand the transport direction adjustment method. However, even if the respective directions and angles are not in the relationship shown in FIGS. 5A and 5B, the same calculation can be performed by determining the sign of which direction the angle and the adjustment amount are positive. is there.

Next, a modification of the first embodiment will be described with reference to the flowchart shown in FIG.
If the conveyance unit 30a is adjusted based on the adjustment amount 1 in step S8 in FIG. 4 described above, the conveyance direction of the recording medium coincides with the direction A. However, it is assumed that the conveyance direction after moving the conveyance unit 30a by the adjustment amount 2 slightly deviates from the direction A due to accidental conveyance abnormality or analysis error at the time of landing analysis. In such a situation, after the adjustment in step 9 in FIG. 4 is completed, the following second adjustment step is incorporated. In the steps shown in FIG. 6, the same steps as those in the steps shown in FIG.

[Procedure 5: S11 to S12]
As shown in FIG. 6, first, in steps 1 to 9, the conveyance direction of the first conveyance unit 30 a is adjusted. Subsequently, after the movement adjustment with the adjustment amount 1 with respect to the conveyance unit 30a is completed, a test image equivalent to the above-described one is formed on the recording medium 31 conveyed to the conveyance mechanism 30 (step S11).

  Next, landing analysis is performed to calculate an angle difference θ4 (corresponding to “third angle difference” in the claims) with respect to the direction A (step S12). It is determined whether or not the calculated angle difference θ4 is within a predetermined allowable angle difference θ0 from 0 (the adjustment completion direction A coincides with the transport direction) (step S13). If it is determined in this determination that the angle difference θ4 is within the range of 0 to the allowable angle difference θ0 (YES), the adjustment operation is terminated because the conveyance direction adjustment is unnecessary.

[Procedure 6: S14]
On the other hand, if the angle difference θ4 exceeds the range of the allowable angle difference θ0 in this determination (NO), the adjustment amount 3 (“Claims” in the claims) is determined based on the angle difference θ4 and the conversion coefficient C1 obtained in step S8. (Corresponding to "second adjustment amount") is calculated (step S14).

[Procedure 7: S15]
Thereafter, the transport direction adjusting mechanism 30b moves the transport unit 30a by the obtained adjustment amount 3 and adjusts the transport direction to the direction A (step S15).

  As described above, according to this modification, after adjusting using the previously calculated conversion coefficient C1, the angle difference is obtained again in the same manner, and the conveyance direction is adjusted again. Can be made to coincide with the direction A in which the color misregistration of the recording head does not occur.

  In the adjustment according to this modification, it is possible to obtain a sufficiently accurate recording medium conveyance direction adjustment result. However, after the adjustment is performed again, a test image equivalent to that described above is formed on the recording medium, and the landing analysis is performed. It is also possible to obtain the angle difference θ in the conveying unit, determine and set it in advance, and repeat the adjustment until it converges within the adjustment range.

[Second Embodiment]
Next, a method for adjusting the transport mechanism of the image forming apparatus according to the second embodiment will be described with reference to the flowchart shown in FIG. In the step shown in FIG. 7, the same step symbols are attached to the same operations as those in the step shown in FIG. 6, and the description of the procedure is omitted.
In the present embodiment, the conversion coefficient is newly calculated and set every time the conveyance direction adjusting mechanism 30b is adjusted. In the first embodiment described above, the conversion coefficient once calculated is repeatedly used.

[Procedure 1-5: S1-S12]
In the transport direction adjusting method of the present embodiment, first, the transport direction of the transport unit 30a is adjusted for the first time as in Steps 1 to 9 in the modified example of the first embodiment described above. Subsequently, after the movement adjustment with the adjustment amount 1 for the transport unit 30a is completed (steps S1-S9), a test image equivalent to the above-described test image is formed on the recording medium 31 transported to the transport mechanism 30 (step S1). S11) After that, landing analysis is performed to calculate the angle difference θ4 with respect to the direction A (step S12) .The calculated angle difference θ4 is set to a predetermined tolerance from 0 (the adjustment completion direction A coincides with the transport direction). It is determined whether or not the angle difference is within the range of θ0 (step S13).
If it is determined in this determination that the angle difference θ4 is within the range of 0 to the allowable angle difference θ0 (YES), the adjustment operation is terminated because the conveyance direction adjustment is unnecessary.

[Procedure 8: S21]
On the other hand, when the angle difference θ4 exceeds the allowable angle difference θ0 in this determination (NO), the angle difference θ2 and the angle are calculated according to the above-described calculation expressions (Expression 1-2) and (Expression 1-3). A conversion coefficient C2 (corresponding to “second conversion coefficient” in the claims) is calculated from the sum of the differences θ4 and the adjustment amount 1, and the adjustment amount 4 (“ (Corresponding to “third adjustment amount”) is calculated (step S21).

[Procedure 9: S22]
Next, the conveyance direction adjustment mechanism 30b moves the conveyance unit 30a by the obtained adjustment amount 4 to adjust the conveyance direction in the direction A and ends (step S22).

Next, the effect | action of the conveyance direction adjustment method of this embodiment is demonstrated.
Generally, the adjustment amount of the conveyance direction adjustment mechanism 30b and the actual change amount of the angle are designed to have a linear linear relationship (proportional relationship). Alternatively, a range in which the two are in a proportional relationship is defined as an adjustable range by the transport direction adjusting mechanism 30b.

  However, the adjustment amount and the actual angle change amount are not necessarily in a linear relationship due to a region exceeding the adjustable range or a manufacturing error or an assembly error of each component of the conveyance direction adjusting mechanism 30b. Absent. For example, FIG. 8 shows an example in which the relationship between the adjustment amount of the conveyance direction adjusting mechanism 30b and the actual change amount in the conveyance direction is not a linear proportional relationship but a proportional relationship expressed by a curve Y.

In this characteristic, when printing (image formation) is performed in two directions m1 and m2 separated from the direction A, which is a preferable conveyance direction for the image forming apparatus 1, and the conversion coefficient is obtained by the above-described method, the conversion coefficient Ca obtained is 8 corresponds to the straight line shown as “a straight line representing the conversion coefficient Ca” in FIG.
Although the straight line by the conversion coefficient Ca approximates the curve Y, in the region close to the direction A, the slope of the curve Y is slightly separated from the straight line representing the conversion coefficient Ca. Therefore, when the transport direction is close to the direction A, the curve Y can be approximated more accurately by using the conversion coefficient Cb newly obtained from the image formation and landing analysis results in the transport directions n1 and n2.

  As described above, according to the present embodiment, in the transport direction adjustment method, the conversion coefficient corresponding to the transport direction change amount to be changed is calculated by recalculating the conversion coefficient every time the transport direction is adjusted. Can be used to calculate the adjustment amount of the conveyance direction adjusting mechanism 30b. Accordingly, the conveyance direction in the conveyance mechanism of the recording medium can be accurately adjusted even for an image forming apparatus having a characteristic in which the adjustment amount of the conveyance direction adjustment mechanism and the actual conveyance angle change amount are not in a linear proportional relationship. be able to.

[Third Embodiment]
Next, a conveyance direction adjustment method according to the third embodiment will be described with reference to a flowchart shown in FIG. This embodiment has a feature that, every time the conveyance direction of the conveyance unit is adjusted by the conveyance direction adjustment mechanism, a corrected conversion coefficient is generated by obtaining a new conversion coefficient and correcting the previous conversion coefficient. Yes. In the step shown in FIG. 9, the same step reference numerals are given to the same operation as the step shown in FIG. 7 described above, and the description of the procedure is omitted.

  The transport direction adjusting method of the present embodiment is similar to steps S1 to S12 in the transport direction adjusting method of the second embodiment shown in FIG. 7, and the transport direction of the transport unit 30a by the first transport direction adjusting mechanism 30b. Adjustments are made.

  Subsequently, it is determined whether or not the calculated angle difference θ4 is within the range of 0 to the allowable angle difference θ0 (step S13). If it is determined in this determination that the angle difference θ4 is within the range of 0 to the allowable angle difference θ0 (YES), the adjustment operation is terminated because the conveyance direction adjustment is unnecessary.

[Procedure 10: S31 to S33]
On the other hand, if the angle difference θ4 exceeds the allowable angle difference θ0 in this determination (NO), the angle difference θ2 and the angle A conversion coefficient C2 is calculated from the sum of the differences θ4 and the adjustment amount 2 (step S31). Using the conversion coefficient C2 and the already calculated conversion coefficient C1, a corrected conversion coefficient C2 ′ (corresponding to “third conversion coefficient” in the claims) is calculated (step S32).

  The corrected conversion coefficient C2 'is, for example, an average value of the conversion coefficient C1 and the conversion coefficient C2. Alternatively, the weights obtained by multiplying the respective distances at which the transport unit 30a is swung, that is, the ratios of these adjustment amounts, are respectively multiplied by the conversion coefficients, and then taking an average value to calculate the corrected conversion coefficient C2 ′. Also good. An adjustment amount 5 (corresponding to the “fourth adjustment amount” in the claims) is calculated from the angle difference θ4 and the conversion coefficient C2 ′ (step S33).

[Procedure 11: S34]
Next, the transport direction adjusting mechanism 30b moves the transport unit 30a by the obtained adjustment amount 5 to adjust the transport direction to the direction A and ends (Step S34).

  As described above, in the present embodiment, the conversion coefficient C2 is first obtained from the angle difference θ2, the angle difference θ4, and the adjustment amount 2, and then, for example, from the average value of the conversion coefficient C1 and the conversion coefficient C2 obtained previously. A corrected conversion coefficient C2 ′ is calculated. Further, the adjustment amount 5 is obtained from the conversion coefficient C2 'and the angle difference θ4.

  When this conveyance direction adjustment method is used, every time adjustment of the conveyance direction is repeated, correction is performed on a newly obtained conversion coefficient, and redundancy is increased. As a result, accidental landing deviation occurs in the adjustment process of the conveyance direction, and even if an incorrect conversion factor is calculated, it has high accuracy while suppressing the adverse effect by having relation with the conversion factor obtained earlier. The conveyance direction can be adjusted.

Next, with reference to FIG. 10, the conveyance direction adjustment method of 4th Embodiment is demonstrated.
In the transport direction adjusting method according to the present embodiment, when a test image is formed, not only the landing analysis target for a test pattern formed by C ink dots and Y ink dots but also K ink dots and M ink dots is used. The test pattern is also subject to impact analysis. Using the test image formed with these ink dots, the angle difference between the current conveyance direction B of the recording medium 31 and the direction A, which is a desirable conveyance direction, is obtained.

A landing analysis method according to the transport direction adjusting method of the present embodiment will be described.
As in FIG. 3B, FIG. 10 shows nozzles 10h that are provided in the C ink recording head 10d, the K ink recording head 10e, the M ink recording head 10f, and the Y ink recording head 10g, and are aligned in the direction A. It is a schematic diagram explaining the printing position of the dots discharged from 10j, 10k, and 10i.

The distances to the K, M, and Y ink dots are measured perpendicular to the direction B with reference to the C ink dots ejected from the nozzle 10h, and are denoted as L21, L22, and L23, respectively. Further, the distances to the nozzles 10j, 10k, and 10i that discharge the K, M, and Y inks with the nozzle 10h as a reference are measured in parallel with the direction A, and are denoted as L11, L12, and L13, respectively. L11, L12, and L13 are design values of the image forming apparatus 1. When L21, L22, and L23 can be measured without incidental shift of landing positions or analysis errors of landing positions, the following equations are established for each.
L21 = L11 × sin (angle difference θ1) Equation (2-1)
L22 = L12 × sin (angle difference θ1) Equation (2-2)
L23 = L13 × sin (angle difference θ1) Equation (2-3)
However, in reality, there are accidental deviations in the landing positions and measurement errors during the landing position analysis. Therefore, in the transport direction adjustment method of the present embodiment, the angle difference θ1 is calculated using all the information of L21, L22, and L23. As this calculation method, for example, the following formula (4-4) or formula (4-5) can be considered.

Angle difference θ1 = Arc sin ((L21 / L11 + L22 / L12 + L23 / L13) / 3)
... Formula (2-4)
Angle difference θ1 = Arc sin (inclination of approximate straight line passing through (L11, L21), (L12, L22), (L13, L23)) (2-5)
According to the transport direction adjusting method of the present embodiment, calculating the angle difference θ1 using M ink dots and K ink dots also increases information redundancy in the calculation. Thus, for example, even when the Y ink recording head 10g is attached to the head holding member 40, even if the Y ink recording head 10g is deviated perpendicularly to the direction A, the influence of erroneous calculation of the angle difference θ1 due to this deviation is reduced, and the conveyance direction is reduced. Adjustment accuracy can be increased.

  In the present embodiment, the desired transport direction A (direction θ1) in which the dot shift determined by the arrangement of the recording heads 10 does not occur is the direction perpendicular to the row direction of the nozzles 10a of the recording head 10, but the present invention is not limited to this. The direction A may form an angle other than a right angle with respect to the row of nozzles 10 a provided in the recording head 10. By using the transport direction adjusting method of the present embodiment, the transport direction B can be efficiently matched with the direction A in which dots of each ink color overlap.

  In each of the embodiments of the present invention described above, an example in which landing analysis is performed using the image formation results of C ink dots and Y ink dots has been described. However, the ink is discharged from at least two nozzles spaced a finite distance in the transport direction. If dots are used, the result of image formation with any combination of colors may be analyzed. In each of the embodiments, the case where image formation is performed with a plurality of colors of ink has been described. However, even if the image is formed from at least two nozzles separated by a finite distance in the transport direction, the image formation of single color ink may be performed. Good.

  Furthermore, although each embodiment demonstrated the example which operates the conveyance direction adjustment mechanism 30b twice or three times and adjusts a conveyance direction, you may repeat an adjustment operation | work 4 times or more. In the present embodiment, the recording head 10 is held by the head holding member 40. However, for example, an image forming apparatus in which a head for multi-color ink is assembled may be used.

  The image forming apparatus to which the present invention is applied is not limited to a line recording system having a plurality of fixed recording heads. For example, the image forming apparatus has a single recording head and prints an image by moving the printing head in the width direction of the recording medium. A serial recording method may be used. You may combine suitably several embodiment mentioned above.

  As described above, even if there is an individual difference in the relationship between the adjustment amount in the recording medium conveyance direction adjustment mechanism of the manufactured image forming apparatus and the actual change amount with respect to the conveyance direction, the conveyance direction adjustment mechanism is By adjusting the conveyance direction (conveyance angle) of the conveyance unit by rotating the conveyance unit, a conveyance mechanism can be formed so as to form a high-quality image in which the recording medium conveyance direction is superimposed on the dots of a plurality of colors without misalignment. Can be adjusted.

The present invention includes the following gist.
(1) At the initial position of the transport unit with respect to the recording head, a test image is printed on a recording medium on the transport unit, and the test image is analyzed, so that the transport direction of the transport unit at the initial position and the transport of the ideal transport unit The first procedure for calculating the first angle difference θ1 with respect to the direction and the maximum adjustment amount 1 that can adjust the transport unit from the initial position are shifted with respect to the recording head. A test image is printed on the recording medium, and the test image is analyzed to calculate a second angle difference θ2 between the transport direction of the transport unit and the transport direction of the ideal transport unit at the adjusted position. The first conversion coefficient C1 is calculated from the procedure 2, the first angle difference, the second angle difference, and the maximum adjustment amount 1, and the first conversion coefficient C1 is calculated from the second angle difference and the first conversion coefficient. Third procedure for calculating the adjustment amount 2 and the transport unit And a fourth procedure for shifting the angle with respect to the recording head by a first adjustment amount of 2.

  (2) Further, after shifting the angle of the conveyance unit with respect to the recording head by the first adjustment amount 2 in the fourth procedure, a test image is printed on the recording medium on the conveyance unit at the position, By analyzing the test image, a fifth procedure for calculating a third angle difference θ4 between the conveyance direction of the conveyance unit and the conveyance direction of the ideal conveyance unit at the adjusted position, and a third angle difference θ4 And a sixth procedure for calculating the second adjustment amount 3 from the conversion coefficient C1, and a seventh procedure for shifting the angle of the transport unit relative to the recording head by the second adjustment amount 3. The adjustment method of the conveyance part as described in (1).

  (3) The second conversion coefficient Cb is newly calculated from the second angle difference θ2, the third angle difference θ4, and the first adjustment amount 1, and the third angle difference and the second conversion coefficient are calculated. The method for adjusting the transport unit according to item (2), further comprising: a sixth procedure for calculating the second adjustment amount 3 from the first step.

  (4) The second conversion coefficient C2 is newly calculated from the second angle difference θ2, the third angle difference θ4, and the first adjustment amount 2, and the first conversion coefficient C1 and the second conversion coefficient are calculated. A new third conversion coefficient C2 ′ is calculated from C2 and a tenth procedure is performed to calculate the second adjustment amount 3 from the third angle difference θ4 and the third conversion coefficient C2 ′. The method for adjusting the conveying section according to item (2).

FIG. 1 is a block diagram illustrating an example of an image forming apparatus using the conveyance direction adjusting method of the present invention. FIG. 2 is a schematic diagram showing the periphery of the recording head and the transport mechanism of the image forming apparatus using the transport direction adjusting method of the present invention. 3A and 3B are diagrams conceptually illustrating an arrangement example in which the recording head and the conveyance unit illustrated in FIG. 2 are looked down from vertically above. FIG. 4 is a flowchart for explaining the procedure of adjusting the conveyance direction in the first embodiment. FIGS. 5A and 5B are diagrams schematically illustrating a procedure for the transport direction adjusting method according to the first embodiment. FIG. 6 is a flowchart for explaining a procedure for adjusting the conveyance direction according to a modification of the first embodiment. FIG. 7 is a flowchart for explaining the procedure of adjusting the conveyance direction according to the second embodiment. FIG. 8 is a diagram illustrating the relationship between the adjustment amount of the conveyance direction adjustment mechanism and the actual conveyance direction change amount according to the second embodiment. FIG. 9 is a flowchart for explaining a procedure of adjusting the conveyance direction in the third embodiment. FIG. 10 is a diagram for explaining the relationship between the landing positions for all of the C, K, M, and Y inks, similarly to the relationship between the landing positions shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Ink supply path, 10 ... Recording head, 10a ... Nozzle, 10b ... Upstream ink port, 10c ... Downstream ink port, 10d ... C ink recording head, 10e ... K ink recording head, 10 ... M Ink recording head, 10g ... Y ink recording head, 10h, 10i, 10j, 10k ... Nozzle, 11 ... Downstream sub tank, 11a ... Downstream air release valve, 11b ... Liquid level regulator, 12 ... Circulating pump, 13 ... Temperature regulator , 14 ... Filter, 15 ... Upstream sub tank, 15a ... Upstream atmospheric release valve, 16a ... Tube, 16b ... Tube, 16c ... Tube, 17 ... Pressure regulator, 18 ... Tube, 19 ... Ink bottle, 19a ... Atmospheric communication pipe, 20a ... Liquid level sensor, 20b ... Valve, 20c ... Ink supply controller, 21 ... Circulation controller, 30 ... Transport mechanism, 30a ... Feeding portion, 30b ... conveying direction adjusting mechanism, 31 ... recording medium, 40 ... head holding member, 50 ... head drive controller.

Claims (10)

In the initial state of the transport unit with respect to the recording head, a test image is formed on the recording medium transported to the transport unit, and the test image is analyzed, so that the transport direction of the transport unit in the initial state and the transport A first procedure for calculating a first angle difference with a predetermined adjustment completion direction of the unit;
The transport unit is moved from the initial state to a second state that is a maximum movement amount to a limit position of the transport direction adjustment range of the transport unit, and in the second state, the recording medium on the transport unit is moved to the second state. A second image for calculating a second angular difference between the conveyance direction of the conveyance unit in the second state after completion of adjustment and the adjustment completion direction by forming a test image and analyzing the test image. And the steps
The first conversion coefficient is calculated from the sum of the first angle difference and the second angle difference and the maximum movement amount, and the first conversion coefficient is calculated from the second angle difference and the first conversion coefficient. A third procedure for calculating the adjustment amount of
A fourth procedure for adjusting the angle of the transport unit with respect to the recording head according to the first adjustment amount;
A method for adjusting the transport direction of the transport unit, comprising: Further, after adjusting the angle of the transport unit with respect to the recording head according to the first adjustment amount, the test image is formed on the recording medium transported to the transport unit, and the test image is analyzed. A fifth procedure for calculating a third angle difference between the conveyance direction of the conveyance unit after the adjustment and the adjustment completion direction;
A sixth procedure for calculating a second adjustment amount from the third angle difference and the first conversion factor;
A seventh procedure for adjusting the angle of the transport unit with respect to the recording head according to the second adjustment amount;
The conveyance direction adjustment method of the conveyance part of Claim 1 characterized by the above-mentioned. Moreover, the transport section and adjust the angle with respect to the first adjustment amount thus recording head, in the state after the adjustment, to form a test image on the recording medium being conveyed by the conveying unit, the test Analyzing the image, and calculating a third angular difference between the conveyance direction of the conveyance unit after the adjustment and the adjustment completion direction;
From the second angle difference, the third angle difference, and the first adjustment amount, a second conversion factor is newly calculated, and from the third angle difference and the second conversion factor, An eighth procedure for calculating a third adjustment amount;
A ninth procedure for adjusting the angle of the transport unit with respect to the recording head according to the third adjustment amount;
The conveyance direction adjustment method of the conveyance part of Claim 1 characterized by the above-mentioned. Further, the angle of the transport unit with respect to the recording head is adjusted according to the first adjustment amount, and after the adjustment, a test image is formed on the recording medium transported by the transport unit, and the test image is analyzed. A fifth procedure for calculating a third angle difference between the conveyance direction of the conveyance unit after the adjustment and the adjustment completion direction;
A second conversion coefficient is newly calculated from the second angle difference , the third angle difference, and the first adjustment amount, and is newly calculated from the first conversion coefficient and the second conversion coefficient. A tenth procedure for calculating a third adjustment coefficient, and calculating a fourth adjustment amount from the third angle difference and the third conversion coefficient;
An eleventh procedure for adjusting the angle of the transport unit with respect to the recording head according to the fourth adjustment amount;
The conveyance direction adjustment method of the conveyance part of Claim 1 characterized by the above-mentioned.   5. The conveyance direction adjustment of the conveyance unit according to claim 4, wherein, in the tenth procedure, the third conversion factor is an average value of the first conversion factor and the second conversion factor. Method.   5. The tenth procedure, wherein the third conversion coefficient is calculated by multiplying the first conversion coefficient and the second conversion coefficient by different coefficients, respectively. The conveyance direction adjustment method of the conveyance part. In the procedure of the first 10, the than the coefficient to be multiplied by the second conversion factor, the transport direction of the transport unit according to claim 6, characterized in that to increase the conversion factor to be multiplied to the first conversion factor Adjustment method.   The coefficient for multiplying the first conversion coefficient and the second conversion coefficient in the tenth procedure is based on a ratio of adjustment amounts used when calculating the respective conversion coefficients. Item 7. The conveyance direction adjustment method of the conveyance unit according to Item 6.   2. The method according to claim 1, wherein the test image in the first procedure is formed by a plurality of recording heads spaced along the recording medium conveyance direction. In an adjustment method for adjusting a transport direction of a transport unit in an image recording apparatus that performs an image with a recording head on a recording medium transported by a transport unit,
When the transport unit is at an initial position arranged with a first angular deviation with respect to the recording head, the test image is recorded on the recording medium transported by the transport unit, and the test image is analyzed. By doing so, the conveyance unit moves between the conveyance direction of the conveyance unit at the initial position and the extending direction of the straight line connecting the plurality of nozzles of the plurality of heads used to form the same line image on the recording medium. A first analysis step for obtaining an angular difference (angular difference) of 1;
A moving step of moving the transport unit from the initial position to a second position within a transport direction adjustment range of the transport unit and having a second angular difference different from the initial position;
When the transport unit is at the second position, the test image is recorded on the recording medium transported by the transport unit, and the test image is analyzed, so that the transport unit at the second position is A second analysis step for obtaining a second angular difference between the recording medium conveyance direction and the extending direction;
A conversion coefficient calculation step for obtaining a conversion coefficient from the first angle difference and the second angle difference and the movement amount from the initial position to the second position;
An adjustment amount calculating step of calculating an angle adjustment amount of the transport unit from the second angle difference and the conversion coefficient;
An adjustment step for adjusting the transport unit based on the angle adjustment amount;
A method for adjusting the transport direction of the transport unit, comprising:

Images