JP2011131499A - Recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recorder for accurately and appropriately adjusting the amount of recording media to be transferred in a sub-scanning direction. <P>SOLUTION: A plurality of reference patterns P1 in which a bright part L and a dark part D are repeated at a fixed cycle are formed in a main scanning direction of a recording medium. After the transfer of the recording medium, an adjusting pattern P2 in which phases of a bright part and a dark part in a sub-scanning direction are shifted gradually relative to the reference pattern P1 is overlaid on each of the plurality of reference patterns P1 of the recording medium. Therefore, a test pattern image in which optical density varies at a fixed cycle is formed. A low density patch pattern image and a high density patch pattern image are specified from the test pattern. A corrected value of the amount of media to be transferred is calculated based of the shifted amount in the high density patch pattern image and the low density patch pattern image. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus that performs printing by ejecting ink droplets onto a recording medium while moving an ink ejection head in a main scanning direction.

  2. Description of the Related Art Inkjet printing apparatuses are known that have a print adjustment function (discharge dot alignment function). The print adjustment function includes correction in the main scanning direction and correction in the sub-scanning direction. In the correction in the sub-scanning direction, the conveyance amount of the recording medium in the sub-scanning direction is corrected so that the dot landing position in the previous recording scan matches the dot landing position in the recording scan that follows the conveyance of the recording medium. If the conveyance amount correction in the sub-scanning direction is not correctly performed, white lines or black lines occur at regular intervals in the output result of the serial printer.

  The transport amount correction method is performed by, for example, forming a test pattern composed of a plurality of patch patterns. Each patch pattern is formed by two recording scans. The conveyance amount of the recording medium performed between the two recording scans is varied. The user selects an optimal patch pattern in which black stripes or white stripes are not visible from the print result of the test pattern. Then, a correction value is determined based on the carry amount in the selected patch pattern (see Patent Document 1).

JP 2003-011344 A

  By the way, in the method in which a test pattern composed of a plurality of patches with different transport amounts as described above is formed and the user selects an optimal patch pattern, only one patch pattern can be selected by the user. The conveyance amount correction value is determined according to the pattern. For example, even when there are a plurality of patch patterns that are optimal for the user, the conveyance amount correction value corresponding to the selected one patch pattern is determined. For this reason, the adjustment of the conveyance amount is not appropriate, and a case where sufficient print quality cannot be obtained may occur. Further, even when the user mistakenly selects a patch pattern other than the optimum patch pattern, the conveyance amount may not be properly adjusted and sufficient print quality may not be obtained.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a recording apparatus that can adjust the conveyance amount of the recording medium in the sub-scanning direction more precisely and appropriately.

  The present invention includes a main scanning unit that moves a recording head in which a plurality of nozzles that eject ink are arranged in a main scanning direction, a sub scanning unit that conveys a recording medium in a sub scanning direction different from the main scanning direction, A recording apparatus having a conveyance amount adjusting unit for adjusting a conveyance amount of the sub-scanning unit, wherein the recording head is moved by the main scanning unit to form a plurality of dot groups in the main scanning direction, and the recording medium After transporting by the transport amount, sub-scanning is performed on a reference patch pattern image having a reference density by ejecting ink so as to overlap the reference dot group of the dot group and a dot group other than the reference dot group. Image forming means for forming a plurality of patch pattern images having different optical densities from the reference patch pattern image by ejecting ink by shifting the dot position stepwise in the direction; and Patch pattern image selected from a low density patch pattern image having a relatively low optical density and a patch pattern image selected from a high density patch pattern image having a relatively high optical density Based on the positional relationship in which the high-density patch pattern image and the low-density patch pattern image specified by the image specifying means and the reference patch pattern image are formed. And correction value calculation means for calculating a conveyance amount correction value for adjusting the conveyance amount of the sub-scanning means.

  According to the present invention, in the test pattern image, a bright part (low density patch pattern image) and a dark part (high density patch pattern image) are always generated at a constant cycle according to the shift amount. Then, by calculating the carry amount correction value based on the shift amounts of both the bright part and the dark part that occur at a certain period, it is possible to perform more accurate and proper carry amount correction.

1 is a perspective view of a recording apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of control hardware of the recording apparatus in FIG. 1. FIG. 2 is an enlarged view of a recording head of the recording apparatus in FIG. 1. It is a patch pattern schematic enlarged view of a test pattern. (A) is a detailed enlarged view of an example of the test pattern output result when transported properly, (b) is a diagram showing an example of the test pattern output result of (a), (c) 4A is a graph showing an example of optical density characteristics of a test pattern of FIG. (A) is a detailed enlarged view of an example of the test pattern output result when not being conveyed properly, (b) is a diagram showing an example of the test pattern output result of (a), (c) 4A is a graph showing an example of optical density characteristics of a test pattern of FIG. It is a figure for demonstrating the calculation process of the correction value of conveyance amount. It is a flowchart which shows the flow of the manual adjustment process of conveyance amount. It is a flowchart which shows the flow of the patch number input process at the time of a manual adjustment process. It is a figure which shows the example of the screen display at the time of a manual adjustment process. It is a figure which shows the example of the patch number selection at the time of manual adjustment. It is a flowchart which shows the flow of the correction value calculation process at the time of manual adjustment. It is a figure which shows the example of an output result of a test pattern. It is a figure which shows the other example of the output result of a test pattern. It is a figure which shows the further another example of the output result of a test pattern. It is a schematic diagram of the optical sensor for patch density | concentration measurement of other embodiment of this invention. It is a flowchart which shows the flow of the automatic adjustment process of conveyance amount.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the constituent elements described in this embodiment are merely examples, and are not intended to limit the scope of the present invention only to them.

  FIG. 1 is a perspective view of an ink jet recording apparatus as an embodiment of the present invention. The recording apparatus includes a platen 1 on which a recording medium 8 conveyed in the A direction is placed by a conveying roller 7 driven by a conveying motor 2. Two scanning rails (not shown) are spanned above the platen 1 in parallel with the platen 1. A carriage 5 that reciprocates in the B and C directions (direction orthogonal to the A direction) is attached to the scanning rail via a slide bearing (not shown) by a carriage motor 3 and a belt 4.

  A linear scale 6 is arranged along the movement path of the carriage 5. The linear scale 6 is provided with regular slits for detecting the position of the carriage 5 and determining the ink discharge timing. In order to read the slit of the linear scale 6, an optical linear scale sensor (not shown) is mounted on the carriage 5. By counting the pulses output from the optical linear scale sensor, the position of the carriage 5 in the B and C directions is determined. The pulse count is initialized by moving the carriage 5 to the position of a home position (HP) sensor (not shown) at the end of the investigation rail when the power is turned on. A head having a plurality of ink discharge nozzles is mounted on the carriage 5. An optical sensor (reflection type) 9 is mounted on the carriage 5 to detect the end of the recording medium. This recording apparatus is equipped with a cutter (not shown) for cutting the roll paper, and the cutter cuts the paper by moving in the C direction on the platen.

  FIG. 2 shows a schematic block diagram of the control hardware of the ink jet recording apparatus in the embodiment of the present invention. The entire recording apparatus is controlled by the system controller 10 and is controlled by the CPU 18 based on the control program and data stored in the ROM 12. The flash memory 13 is a storage area for storing various parameters and tables, and the RAM 14 provides a work area for the CPU 18. The internal pattern generation unit 11 generates an adjustment pattern and displays a message on the display unit 21 of the operation unit 20 after outputting the test pattern to prompt the user to input. The user inputs a numerical value or the like according to the test pattern from the input unit 21 as an input means. The CPU 18 calculates various adjustment values from the selection values from the input unit 21 and stores them in the storage area of the flash memory 13. When transporting the recording medium, the CPU 18 refers to the adjustment value stored in the flash memory 13 and controls the transport motor 30 via the transport control unit 14 so as to obtain an appropriate transport amount.

When printing an image, the CPU 18 controls the carriage motor 31 via the carriage control unit 15 and refers to the adjustment value stored in the flash memory 13 so that the ink discharge positions coincide with each other. 16, the ink discharge timing of the head 32 is controlled.
In the case of a configuration in which automatic adjustment is performed, the carriage is scanned after the test pattern is output, the density of each patch pattern image is read by the optical sensor 33, and the CPU 18 calculates the adjustment value from the detection value from the sensor control unit 17. Then, it is stored in the storage area of the flash memory 13.

  FIG. 3 is an enlarged view of the recording head used in this embodiment, and has a configuration in which 1200 discharge nozzles are arranged in the sub-scanning direction with a resolution of 1200 dpi. In this description, 600 nozzles on the downstream side in the sheet conveyance direction of the nozzle row used for recording the test pattern are referred to as block 1, and 600 nozzles on the upstream side are referred to as block 2. Here, when paper is optimally transported from the head nozzle position of block 2 to the head nozzle position of block 2, a straight line printed by the eighth nozzle in block 1 and a straight line printed by the eighth nozzle in block 2 The positions in the sub-scanning direction are the same.

  Next, test pattern image forming means will be described.

  FIG. 4 is a schematic enlarged view of each patch pattern image (hereinafter referred to as a patch pattern) in a test pattern image (hereinafter referred to as a test pattern) used in the present embodiment. The test pattern in FIG. 4 is an example when N = 3 (N is an integer) and k (unit of shift amount) = 1. The adjustment pattern will be described with a total of 7 (2N + 1) patch (dot group) configurations shifted stepwise in a range of -3 dots (-N dots) to +3 dots (+ N dots) in units of 1 dot (k dots). . That is, 2N + 1 reference pattern images and adjustment pattern images are recorded. However, the number of patches does not necessarily have to be 7, and the range of the shift amount does not have to be -3 dots to +3 dots in units of 1 dot. These create a pattern according to the range necessary for actual adjustment.

  First, as shown in FIG. 4A, a reference pattern is printed using a predetermined nozzle located in the block 2 on the upstream side in the paper transport direction. That is, the block 2 forms a plurality of reference pattern images in the main scanning direction of the recording medium in which the bright part and the dark part are repeated at a constant cycle in the sub scanning direction. In this example, the discharge of 2 dots at intervals of 4 dots in the sub-scanning direction is repeated up to 600 dots of the block height, and all seven patches arranged in the main search direction of the reference pattern are the same.

Next, the recording medium is transported using a length (600 nozzles) corresponding to half of all nozzle rows (1200 nozzles) as a transport amount. That is, the recording medium on which a plurality of reference patterns are formed is conveyed by a predetermined conveyance amount in the sheet conveyance direction. The transport resolution is a numerical value that depends on the performance of the printing apparatus, but here it is assumed that the paper can be transported at a resolution of 9600 dpi. Under these conditions, the command pulse value (number of nozzles corresponding to half of the nozzle array × nozzle array resolution / conveyance resolution) used to transport an amount corresponding to half the length of all nozzle arrays is as follows: It is as follows.
600 × 25.4 / 1200 / 25.4 × 9600 = 4800

However, the number of nozzles corresponding to half of the nozzle row is 600, the resolution of the nozzle row (nozzle interval) is 1200 dpi, and the resolution of the transport amount is 9600 dpi. The theoretical value of the conveyance amount of the recording medium conveyed by this command pulse value (4800) is as follows.
600 × 25.4 / 1200 = 12.7 [mm]

  Next, after the recording medium is transported by the transport amount of the above-described theoretical value, an adjustment pattern image (reference) shown in FIG. 4B is used using a predetermined nozzle located in the block 1 on the downstream side of the recording head. (Patch pattern image) (hereinafter referred to as an adjustment pattern) (P2) is recorded. In the adjustment pattern, the bright part (L) and the dark part (D) repeat at the same cycle as the reference pattern, and the phases of the bright part and the dark part in the sub-scanning direction are shifted stepwise with respect to the reference pattern (P1). These images are superimposed on each of the plurality of reference patterns of the recording medium. For ease of explanation, when the numbers 1 to 7 corresponding to the shift amounts are assigned to the seven patch patterns, the patch number 4 in the adjustment pattern has the same positional relationship as the reference pattern in the ejection dot position in the sub-scanning direction. To be. The other patches (other than the reference dot group) are printed with a combination of different nozzles in a range of -3 dots to +3 dots in units of 1 dot, thereby forming a pattern relatively shifted from the reference pattern. At this time, although the shift directions of the patch number 1 and the patch number 7 in the sub-scanning direction are opposite to each other, they are formed so as to have the same pattern. Thereby, as will be described later, a test pattern image composed of a plurality of patch pattern images whose optical density changes at a constant cycle is formed.

  FIGS. 5A to 5C are examples of test pattern output results when transported properly (the transport amount correction value is correct). FIG. 5A is a detailed enlarged view of print dots of each patch formed on the recording medium. In patch number 4, the discharge dots of the reference patch and the adjustment patch overlap each other, but in other patches, the position of the discharge dots is shifted in the sub-scanning direction by the shift amount of the adjustment patch. FIG. 5B shows this as an actual output result, which shows that the patch pattern appears darker as the patch patterns at both ends centering on patch number 4 (low-density patch pattern image). In Patch No. 4, since the ejection dots of the reference pattern and the adjustment pattern are overlapped and printed, the white background portion on the recording medium increases, and the appearance becomes brighter. On the other hand, when the printing positions of the ejection dots of the reference pattern and the adjustment pattern are shifted, the white background portion is reduced and the image appears dark. In FIG. 5B, the patch 1 and the patch 7 appear the darkest (high density patch pattern image) because the shift amounts of the ejection dot positions of the reference pattern and the adjustment pattern are the same and are the largest. FIG. 5C is a graph schematically showing the patch number and brightness when the correction value is correct, and the patch 4 is symmetrical with the peak value at a bright place.

  Next, FIG. 6 shows an example in which the transport amount is insufficient by 1 dot. Since one dot is less than the original transport amount, as shown in the enlarged detail view of the patch in FIG. 6A, the patch number 5 overlaps the ejection dots of the reference pattern and the adjustment pattern. Then, the patch number 2 is the largest deviation of the ejection dot position. FIG. 6B shows the output result in this state, which indicates that patch number 5 appears bright and patch number 2 appears dark. Further, FIG. 6 (c) is a graph of this, and the patch number (shift amount) that peaks at a bright place and a dark place is shifted by one in the plus direction as compared with FIG. 5 (c). I understand that.

  In this example, the case where the amount is less than 1 dot has been described, but on the contrary, when the carry amount is increased by 1 dot, the patch number 3 is printed with the reference pattern shifted from the reference pattern, so each peak position is 1 in the minus direction. Shift by one. That is, in the test pattern of the present embodiment, the peak positions of the bright part and the dark part shift to the left and right according to the carry amount, but the interval (cycle) between the bright part and the dark part is constant.

  Next, the conveyance amount correction value calculation process will be described with reference to FIG.

  In the test pattern of the present embodiment, the patch is bright where the value is correct, and the relationship between the bright part and the dark part is always a constant interval. Therefore, it is 1/4 from the patch number (M: hereinafter referred to as an intermediate value) between the bright portion patch number (L: hereinafter referred to as a bright portion value) and the dark portion patch number (D: hereinafter referred to as a dark portion value). The position shifted by the cycle is a patch number indicating a correct correction value (N: hereinafter referred to as a correction value number).

Whether to shift in the plus direction or the minus direction from the intermediate value number (M) is determined by the magnitude relationship between the bright part (L) and the dark part (D) as shown in FIG.
When bright part (L)> dark part (D): plus direction (FIG. 7A)
When bright part (L) <dark part (D): minus direction (FIG. 7B)

In this example of the test pattern, the patch number is in the range of 1 to 7 (shift amount is −3 to +3), so the value of 1/4 period (T / 4) is
1/4 period (T / 4) = (7-1) /4=1.5
It becomes.
Therefore, the intermediate value (M) is
Intermediate value (M) = (Bright value (L) + Dark value (D)) / 2 (1)
The correction value number (N) is
(When L> D)
Correction value number (N) = M + T / 4 (2)
(When L <D)
Correction value number (N) = M−T / 4 (3)
It is calculated by the relational expression.

Next, since the patch number 4 is the center (the shift amount is 0) in this test pattern, the shift amount from the current correction value (hereinafter referred to as a relative correction value (ΔV)) is obtained by correcting the center number. Relative correction value (ΔV) = N-4 (4)
It becomes.

Finally, the correct correction value obtained from the test pattern result is obtained by adding the relative correction value (ΔV) to the current correction value (V) used when printing the test pattern, and the correction value (Vnew) = V + ΔV (5)
It becomes.

  Next, an example by the manual adjustment of the carry amount as the carry amount adjusting means in the present embodiment will be described.

  FIG. 8 is a flowchart showing the flow when manual adjustment is performed. When the user performs adjustment from the operation unit 20 or the like, a test pattern is output with the current correction value (V) (S100). When printing of the test pattern is completed, a message prompting the user to input a patch number is displayed on the display unit 21 of the operation unit 20. The user confirms the test pattern, inputs a patch number from the input unit 22 (S200), and calculates a correction value from the input patch number (S300).

  Details of the patch number input process (S200) as input means and the correction value calculation process (S300) as correction value calculation means will be described below.

  FIG. 9 is a flowchart showing the flow of the patch number input process. The patch number input process identifies a bright area that is a low density patch pattern with a relatively low optical density and a dark area that is a high density patch pattern with a relatively high optical density from a plurality of patch patterns. It is a process to do.

  When the output of the test pattern is completed, a screen for selecting a bright part of the patch pattern is displayed first (S211). This selection process constitutes an image specifying means. FIG. 10A shows an example of the panel display at this time, and the user confirms the output test pattern and inputs a patch number (S212). FIG. 11 shows an example of output status and patch number selection. When a bright place can be specified as one of patch numbers 5 as shown in FIG. 11A, “5” is input only to selection 1 (L1) and the “OK” button is pressed. When a bright place cannot be specified by patch number 5 or patch number 6 as shown in FIG. 11B, “5” is input to selection 1 (L1) and “6” is input to selection 2 (L2). Press the “OK” button. That is, a plurality of images can be selected.

  When the patch number is input, the input value is checked (S213). FIG. 9B is a flowchart showing the flow of the input value check process. First, the number of input values is confirmed (S231). If there is only one input value, the determination is OK as it is (S232), and the processing ends without doing anything. Next, when there are two input values, the relationship between the patch numbers when there are two input values should be adjacent positions due to the characteristics of the test pattern of this embodiment. The position is confirmed (S233). The determination method is based on the absolute value of the difference between the selected patch numbers. If the selected patch is adjacent, the difference is always 1. Furthermore, the relationship between the patch 1 and the patch 7 is considered to be an adjacent position because of the characteristics of the test pattern this time, so that it is also effective when the difference is 6. Therefore, when the absolute value of the difference is 2 to 5, there is a possibility of selection error or input error, so it is determined as NG (S234). If the result of the input value check (S213) is NG, a screen prompting the user to select again is displayed (S214). FIG. 10C shows an example of the panel display at this time. When the “OK” button is pressed, the screen returns to the selection screen (S211) for the bright portion of the patch.

  The processing of S215 to S218 in the patch number input processing flow is processing for selecting a dark portion of the patch, and is the same processing as S211 to S214 of processing for selecting a bright portion.

  Next, the correction value calculation process (S300) will be described with reference to FIGS. 12 and 13 to 16. FIG. In the correction value calculation processing, the amount of shift of the adjustment pattern with respect to the reference pattern in the specified high density patch pattern and low density patch pattern, that is, the carry amount for adjusting the carry amount of the sub-scanning means based on the patch number This is a process for calculating a correction value.

FIG. 12 is a flowchart showing the flow of manual adjustment correction value calculation processing, and FIGS. 13 to 16 show test pattern output result states and patch number selection examples. FIG. 13A shows an example in which one bright part (L1 = 5) and one dark part (D1 = 2) are selected. In the correction value calculation process (S300), first, the number of bright part input values is confirmed (S311). Since only one bright part is selected this time, the bright part value L is fixed at L1 (= 5) (S312). Next, the dark portion value is also confirmed, and since the dark portion has only one input value, the dark portion value D is determined by D1 (= 2) (S316, S317). Since the bright part value (L) and the dark part value (D) are fixed, the intermediate value (M) is calculated using the equation (1) (S330).
M = (5 + 2) /2=3.5

Since the intermediate value (M) is determined, the correction value number (N) is obtained by shifting by a quarter period (S331 to S334). FIG. 13A shows that L (= 5)> D (= 2). Because of the relationship, equation (2) is applied and the correction value number (N) is
N = 3.5 + 1.5 = 5.0
It becomes. Finally, center number correction is performed using equation (4) to calculate a relative correction value (ΔV) (S334).
ΔV = 5.0−4 = 1.0
It becomes.

FIG. 13B shows an example in which two bright portions (L1 = 5, L2 = 6) and one dark portion (D1 = 2) are selected. If there are two selection values, it is first checked whether the selected patch position is adjacent or both ends (S313). In the case of FIG. 13B, since the selection values are adjacent to each other at 5 and 6, in this case, the average value of the two selection values (the average value of the shift amounts of a plurality of selected images) is set as the bright part value (L). (S314). This value is used for calculating the correction value of the carry amount.
L = (Selection value 1 (L1) + Selection value 2 (L2)) / 2 (6)
= (5 + 6) / 2 = 5.5

Since there is only one dark part, D = D1 (= 2), and the intermediate value (M) is determined from equation (1).
M = (5.5 + 2) /2=3.75
The subsequent processing is the same as in the case where there is one selection value. From the relationship of L (= 5.5)> D (= 2), equation (2) is applied and the correction value number (N) is N = 3.75 + 1. .5 = 5.25
Thus, center number correction is performed using equation (4) to calculate a relative correction value (ΔV) (S334).
ΔV = 5.25−4 = 1.25

FIG. 13C shows an example in which one bright part (L1 = 5) and two dark parts (D1 = 1, D2 = 2) are selected. Since there is only one bright part selection, L = L1 (= 5) is determined (S312), and the dark part determines whether the selected patch position is adjacent or both ends as in the case where there are two bright part selection values described above. Confirmation (S318). In the case of FIG. 13C, since the selection value of the dark part is adjacent to 1 and 2, the average value of the two selection values is set as the dark part value (D) (S319).
D = (Selection value 1 (D1) + Selection value 2 (D2)) / 2 (7)
= (1 + 2) / 2 = 1.5
The following similarly calculates the intermediate value (M) from the equation (1),
M = (5 + 1.5) /2=3.25
From the relationship of L (= 5)> D (= 1.5), equation (2) is applied and the correction value number (N) is
N = 3.25 + 1.5 = 4.75
Thus, center number correction is performed using equation (4) to calculate a relative correction value (ΔV) (S334).
ΔV = 4.75−4 = 0.75
It becomes.

FIG. 14 shows an example of a test pattern when the dark part is divided at both ends. First, when confirming the bright portion, since there are two bright portions (L1 = 3, L2 = 4) and adjacent positions in FIG. 14A, from the average value calculation (S314) of the bright portion value, from the equation (6),
L = (3 + 4) /2=3.5
It becomes. Similarly, two bright portions (L1 = 4, L2 = 5) in FIG.
L = (4 + 5) /2=4.5
It becomes. In FIG. 14C, since there is one bright part (L1 = 4), L = 4 as it is.
(S312).

Next, although it is a dark part value, two selection values (D1 = 1, D2 = 7) of the dark part are separated at both ends and cannot be determined (S318, S320). In such a case, the bright part value (L) that has already been confirmed is compared with the patch number at the center of the test pattern (“4” in this case), and the process is switched (S327). In FIG. 14A, the bright part value (L) is 3.5, which is smaller than the center number of 4. This indicates that the pattern is shifted in the negative direction as a whole. Therefore, in consideration of the periodicity of the pattern, the smaller D1 (= 1) is ignored in the dark portion selection value, and the larger D2 (= Only 7) is enabled and processing is performed (S328). As a result, when the bright part value (L) is 3.5 and the dark part value (D) is 7, and the intermediate value (M) is obtained from the expression (1),
M = (3.5 + 7) /2=5.25
The correction value number (N) is applied by the formula (3) from the relationship L (= 3.5) <D (= 7),
N = 5.25-1.5 = 3.75
It becomes. Finally, the center number is corrected using the equation (4) to calculate the relative correction value (ΔV) (S334).
ΔV = 3.75−4 = −0.25
become.

Next, in FIG.14 (b), the bright part value (L) is 4.5 and is larger than 4 of the center number. Since this indicates that the pattern is shifted in the positive direction as a whole, the larger D2 (= 7) in the dark portion selection value is ignored in consideration of the periodicity of the pattern, and the smaller D1. Only (= 1) is enabled and the process (S329) is performed. As a result, when the bright value (L) is 4.5 and the dark value (D) is 1, the intermediate value (M) is obtained from the equation (1).
M = (4.5 + 1) /2=2.75
Then, the correction value number (N) is applied by the formula (2) from the relationship of L (= 4.5)> D (= 1),
N = 2.75 + 1.5 = 4.25
It becomes. Finally, the center number is corrected using equation (4), and the relative correction value (ΔV) is
ΔV = 4.25−4 = 0.25
It becomes.

Next, in FIG. 14C, the bright part value (L) is 4, which matches the center number of 4. Since this indicates that the waveform is not shifted to the left or right, the correction value number (N) is fixed at 4 which is the center number of the patch (S335), and center number correction is performed using equation (4). The relative correction value (ΔV) is
ΔV = 4−4 = ± 0
It becomes.

To summarize the process when the dark value so far is divided at both ends,
(When bright part value (L)> patch center number (4))
Process with the smaller dark area selection value (ignoring the larger one)
(Light part value (L) <patch center number (4))
Process with the larger dark area selection value (ignoring the smaller one)
(When bright part value (L) = patch center number (4))
Processing is performed with correction value number (N) = patch center number (4).

FIG. 15 shows an example of a test pattern when the bright part is divided at both ends. This time, two selection values (L1 = 1 / L2 = 7) of the bright part are separated at both ends and cannot be determined (S313, S315). In this case, the dark portion value is specified before processing. Here, due to the characteristics of this test pattern, if the bright part is divided at both ends, the dark part can be identified without fail. On the contrary, when the dark part is divided at both ends, the bright part can be specified. Therefore, when the dark part is confirmed this time, in FIG. 15A, from the dark part value average value calculation (S319) from the two dark parts (D1 = 3, D2 = 4) (S319),
D = (3 + 4) /2=3.5
It becomes. In FIG. 15B, two dark parts (D1 = 4, D2 = 5) are similarly D = (4 + 5) /2=4.5.
In FIG. 15C, since there is one dark part (D1 = 4), D = 4 as it is.
(S317). Then, this time, the dark portion value (D) and the patch number (4) at the center of the test pattern are compared to switch the processing (S322). In FIG. 15A, the dark part value (D) is 3.5, which is smaller than the center number of 4. Since this indicates that the pattern is shifted in the negative direction as a whole, L1 (= 1) having a smaller selection value of the bright portion is ignored in consideration of the periodicity of the pattern, and L2 having the larger value is selected. Only (= 7) is validated and processed (S323). As a result, the intermediate value (M) from the equation (1) is
M = (7 + 3.5) /2=5.25
From the relationship of L (= 7)> D (= 3.5), the correction value number (N) from the equation (2) is
N = 5.25 + 1.5 = 6.75
From the equation (4), the relative correction value (ΔV) is
ΔV = 6.75−4 = 2.75
become.

Next, in FIG. 15B, the dark part value (D) is 4.5, which is larger than the center number 4. Since this indicates that the pattern is shifted in the positive direction as a whole, the larger L2 (= 7) in the bright portion selection value is ignored, and only the smaller L1 (= 1) is enabled. (S329). Thereafter, similarly, the intermediate value (M) from the equation (1) is
M = (1 + 4.5) /2=2.75
From the relationship of L (= 1)> D (= 4.5), the correction value number (N) is obtained from the equation (3).
N = 2.75-1.5 = 1.25
From the equation (4), the relative correction value (ΔV) is
ΔV = 1.25−4 = −2.75
become.

  Next, in FIG.15 (c), the dark part value (D) is 4 and corresponds to 4 of the center value. In this case, the bright part is divided at both ends, and it cannot be determined whether the waveform is shifted to the left or right. Therefore, since the correction value cannot be specified with this, in this case, an error is displayed on the display unit of the operation unit as an adjustment error (S325), and the process ends (S500).

To summarize the processing when the bright part value is divided at both ends,
(Dark part value (D)> Patch center number (4))
Process with the smaller value of the bright part selection value (ignoring the larger one)
(Dark part value (D <Patch center number (4))
Process with larger value of bright part selection value (ignoring smaller value)
(Dark part value (D = patch center number (4))
Processing is performed with correction value number (N) = patch center number (4).

  The example of manual adjustment in which the user inputs the patch number has been described so far, but the calculation processing of the present invention only needs to be able to specify the light part value (L) and the dark part value (D). For this reason, if the optical sensor 9 mounted on the carriage 5 is configured as a sensor capable of measuring the density of the print patch, automatic adjustment processing can be performed. That is, the optical sensor 9 constitutes image density detection means for detecting the density of the plurality of patch patterns.

  An optical sensor for measuring the density of the patch will be described. FIG. 16 is a schematic diagram for explaining the reflective optical sensor 9. The reflective optical sensor 9 includes a light emitting unit 51 and a light receiving unit 52. Irradiation light in 61 emitted from the light emitting unit 51 is reflected by the surface of the recording medium 8. The light receiving unit 52 detects the amount of light (reflected light intensity) of the reflected light ref 61 reflected from the surface of the recording medium 8. The density of the patch printed at an arbitrary position on the recording medium can be detected by scanning the carriage 5 to which the reflective optical sensor 9 is attached in the main scanning direction and transporting the recording medium in the sub-scanning direction.

  The detected value of the amount of reflected light detected by the optical sensor 9 is processed by the CPU 18 via the sensor control unit 17. Note that the detection of the density of the patch formed on the recording medium 8 does not need to detect the absolute value of the density as long as the relative density can be detected. In addition, it is only necessary to have a detection resolution enough to detect a relative density difference between patches among a plurality of patches printed in a predetermined area described later.

  FIG. 17 is a flowchart for performing automatic adjustment in the present embodiment. The patch reading process (S600) is performed instead of the patch number input process (S200) in the manual adjustment sequence of FIG.

  When the user performs adjustment from the operation unit 20, a test pattern is output (S100). In the case of automatic adjustment, the patch reading process is performed without discharging the paper when the test pattern printing is completed (S600). The flow of this patch reading process is shown in FIG. First, the recording medium is conveyed in accordance with the position in the sub-scanning direction that can be read by the optical sensor 9 mounted on the carriage 5 (S611). Next, the optical sensor 9 scans the patch while scanning the carriage 5 to measure the density of each patch (S612). When scanning of all the patches is completed, the brightest patch (L) and the darkest patch (D) are found (S613). When the pattern reading is completed, the test pattern is discharged (S614). Subsequently, automatic adjustment is performed so that the correction value calculation process (S300) is performed using the bright part value (L) of the brightest patch number and the dark part value (D) of the darkest patch number obtained in the patch measurement process. It may be configured as follows.

2 ... Conveyance motor 8 ... Recording medium 9 ... Optical sensor 21 ... Input part P1 ... Reference pattern P2 ... Adjustment pattern L ... Bright part D ... Dark part

Claims (6)

A main scanning means for moving a recording head in which a plurality of nozzles for ejecting ink are arranged in the main scanning direction; a sub-scanning means for conveying a recording medium in a sub-scanning direction different from the main scanning direction; A recording apparatus having a conveyance amount adjusting means for adjusting a conveyance amount,
After the recording head is moved by the main scanning unit to form a plurality of dot groups in the main scanning direction and the recording medium is conveyed by a predetermined conveyance amount, the ink is overlapped with the reference dot group among the dot groups. The reference patch pattern image of the reference patch pattern image and the optical unit are ejected by gradually shifting the dot position in the sub-scanning direction with respect to a reference patch pattern image having a reference density and a dot group other than the reference dot group. Image forming means for forming a plurality of patch pattern images having different target densities;
Among the plurality of patch pattern images, a patch pattern image selected from a low density patch pattern image having a relatively low optical density and a patch pattern selected from a high density patch pattern image having a relatively high optical density Image specifying means for specifying each of the images,
The conveyance amount of the sub-scanning unit is adjusted by the image specifying unit based on the positional relationship between the specified high-density patch pattern image and the specified low-density patch pattern image and the reference patch pattern image. Correction value calculation means for calculating a conveyance amount correction value for
A recording apparatus comprising:   The recording apparatus according to claim 1, wherein the image specifying unit includes an input unit for a user to select the low-density patch pattern image and the high-density patch pattern image. The input means is formed such that a plurality of each of the low density patch pattern image and the high density patch pattern image can be selected,
When a plurality of the low density patch pattern images and / or high density patch pattern images are selected, the correction value calculation means calculates an average value of shift amounts of the plurality of selected images to calculate the transport amount correction value. The recording apparatus according to claim 2, wherein the recording apparatus is used. Further comprising image density detection means for detecting the density of the plurality of patch pattern images;
The recording apparatus according to claim 1, wherein the image specifying unit specifies the low density patch pattern image and the high density patch pattern image based on a detection value of the image density detection unit.   The test pattern image forming unit records the reference pattern image of 2N + 1 (N is an integer) in the main scanning direction on the recording medium, and after the transport of the recording medium by the sub-scanning unit, On the other hand, the ink discharge position of the adjustment pattern image is gradually shifted in the range of −N dots to + N dots in the sub-scanning direction so as to overlap the area where the reference pattern image is recorded, and 2N + 1 in the main scanning direction. The recording apparatus according to claim 1, wherein the pattern image for adjustment is recorded.   The test pattern image forming unit shifts the ink ejection position in a range of −N × k to + N × k, where the unit of the shift amount in the sub-scanning direction in the adjustment pattern image is k dots (k is an integer). The recording apparatus according to claim 5, wherein 2N + 1 pieces of the adjustment pattern images are recorded in a main scanning direction.