Recording device and method of adjusting discharge timing of the same

Abstract

To provide a recording device which can inhibit deterioration of the image quality.SOLUTION: A recording device discharges a liquid to a recording medium to record an image and includes: nozzles configured to discharge the liquid; adjusting means which performs adjustment of discharge timings of the nozzles; acquiring means which acquires discharge states of the nozzles; and selecting means which selects a reference nozzle, which serves as a reference of the adjustment of the discharge timings, from the nozzles based on the acquired result of the acquiring means.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a recording apparatus and a method for adjusting its ejection timing.

Background Art

[0002] As a recording apparatus for recording an image or the like on a recording medium, an inkjet printer that performs a recording operation by ejecting ink from a plurality of nozzles is known. In such a recording apparatus, since ink is ejected from each nozzle, if the ejection timing of each nozzle is deviated, it may lead to a deterioration in image quality.

[0003] As a method for suppressing a deterioration in image quality, a method of adjusting the ejection timing is known in which one of a plurality of recording heads is used as a reference, and the ejection timing of the nozzles of the other recording heads is adjusted to match the ejection timing of the nozzles of the reference recording head. For example, Patent Document 1 discloses a configuration in which a recording head disposed closer to the center is used as a reference for timing adjustment. Further, Patent Document 2 discloses a configuration in which a recording head on the side closer to the action line of the moving force is used as a reference for timing adjustment.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above-described configuration, if a problem occurs in the ejection state of the nozzles of the reference recording head, the timing adjustment may not be performed normally, which may cause a deterioration in image quality.

[0006] In view of the above problems, an object of the present invention is to provide a recording apparatus capable of suppressing a decrease in image quality.

Means for Solving the Problems

[0007] To achieve the above object, a recording apparatus of the present invention is a recording apparatus that discharges a liquid onto a recording medium to record an image, a plurality of nozzles for discharging the liquid, adjusting means for adjusting the discharge timing of the plurality of nozzles, acquiring means for acquiring the discharge state of the nozzles, selecting means for selecting a reference nozzle as a reference for adjusting the discharge timing from among the plurality of nozzles based on the acquisition result of the acquiring means, and is characterized by comprising the above. Also, to achieve the above object, a method for adjusting the discharge timing of a recording apparatus of the present invention is a method for adjusting the discharge timing of a recording apparatus that includes a plurality of nozzles for discharging a liquid and discharges the liquid onto a recording medium to record an image, characterized by selecting a reference nozzle as a reference for adjusting the discharge timing from among the plurality of nozzles based on the discharge state of the plurality of nozzles.

Effects of the Invention

[0008] According to the present invention, a recording apparatus capable of suppressing a decrease in image quality can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0010] Hereinafter, with reference to the drawings, modes for carrying out this invention will be exemplarily and specifically described based on examples. Note that the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. That is, the scope of this invention is not intended to be limited to the following embodiments.

[0011] <Example 1> (Recording Apparatus) The configuration of a recording apparatus 600 according to Embodiment 1 of the present invention will be described. The recording apparatus 600 of Embodiment 1 is a liquid ejection apparatus that ejects ink as a liquid and performs a recording operation on a recording medium such as paper. FIG. 1 is a schematic perspective view showing the configuration of the recording apparatus 600 according to Embodiment 1. The recording apparatus 600 is a color inkjet recording apparatus including four recording heads 201 to 204 and four ink tanks 205 to 208.

[0012] The ink tanks 205 to 208 respectively store four colors of ink: cyan (C), magenta (M), yellow (Y), and black (K), and are configured to be able to supply these four colors of ink to the recording heads 201 to 204. The recording heads 201 to 204 are liquid ejection heads provided corresponding to the four colors of ink and configured to be able to eject the ink supplied from the ink tanks 205 to 208.

[0013] The transport unit that transports the recording medium (recording paper) 107 of the recording apparatus 600 is composed of transport means such as transport rollers 103, an auxiliary roller 104 arranged to face the transport roller 103, and a transport roller 105. The transport roller 103 rotates while sandwiching the recording medium 107 together with the auxiliary roller 104 to transport the recording medium 107, and also plays a role of holding the recording medium 107.

[0014] Further, the recording apparatus 600 includes a carriage 106 on which recording heads 201 to 204 and ink tanks 205 to 208 can be mounted. The carriage 106 is a holding unit configured to be reciprocally movable along a direction intersecting the transport direction of the recording medium 107 while holding the recording heads 201 to 204 and the ink tanks 205 to 208. During the reciprocating movement of the carriage 106, ink is ejected from the recording heads 201 to 204, and thereby an image is recorded on the recording medium 107. During non-recording operations such as during the recovery operation of the recording heads 201 to 204, the carriage 106 is controlled to standby at the position of the home position h shown by the dotted line in FIG. 1.

[0015] In the following description, the main scanning direction (moving direction) of the recording heads 201 to 204 (carriage 106) during the recording operation is described as the X direction, and the direction in which the recording medium 107 is transported at a position facing the recording heads 201 to 204 is described as the Y direction. Also, the direction intersecting the X direction and the Y direction, and the direction in which the recording heads 201 to 204 face the recording medium 107 during the recording operation is described as the Z direction. In the first embodiment, the X direction, the Y direction, and the Z direction are orthogonal to each other.

[0016] The recording heads 201 to 204 waiting at the home position h move in the X direction in FIG. 1 together with the carriage 106 when a recording start command is input, and discharge ink to record an image on the recording medium 107. The home position h is one end in the X direction within the movable range of the recording heads 201 to 204 as shown in FIG. 1. By one movement (scanning) of this recording head, recording is performed on an area having a width corresponding to the array range of the discharge ports of the recording heads 201 to 204. When the recording accompanying one scan of the carriage 106 in the main scanning direction (X direction) is completed, the carriage 106 returns to the home position h. Almost simultaneously therewith, the conveyance roller 103 rotates and the recording medium 107 is conveyed in the sub-scanning direction (Y direction) intersecting the main scanning direction by a distance corresponding to the array range of the discharge ports of the recording heads 201 to 204. After both movements are completed, the recording heads 201 to 204 perform recording again while scanning in the X direction in FIG. 1. By repeating the recording scan of the recording heads 201 to 204 and the conveyance of the recording medium 107 in this way, the recording of the image on the recording medium 107 is completed. The recording operation of discharging ink from the recording heads 201 to 204 is performed based on the control by the control means described later.

[0017] Note that in the above-described operation example, the case of performing so-called one-way recording in which the recording operation is performed only when the recording head scans in the forward direction has been described. However, the present invention is also applicable to those that perform so-called two-way recording in which recording is performed both when the recording head scans in the forward direction and when it scans in the return direction. Also, instead of performing recording on all areas having the width of the array range of the discharge ports, recording may be performed only partially, and recording may be performed by a so-called multi-pass method in which recording is performed by a plurality of carriage scans. Further, in the first embodiment, the configuration of the liquid ejection device in which the ink tanks 205 to 208 and the recording heads 201 to 204 are detachably mounted on the carriage 106 has been shown. However, a form in which a cartridge in which the ink tanks 205 to 208 and the recording heads 201 to 204 are integrated is mounted on the carriage may be adopted. Furthermore, a form in which a multi-color integrated head capable of discharging a plurality of colors of ink from one recording head is mounted on the carriage may be adopted.

[0018] FIG. 2 is a block diagram showing a schematic configuration of a recording control system circuit of the recording apparatus 600 according to the first embodiment. The recording apparatus 600 is connected to a data supply apparatus such as a host computer (hereinafter referred to as host PC) 1200 via an interface 400. Various data transmitted from the data supply apparatus, control signals related to recording, and the like are input to a control unit 500 of the recording apparatus 600.

[0019] The control unit 500 includes a memory 502 which is a storage means for a mask described later, and a CPU 501 (which may be an ASIC) serving as a calculation means. The control unit 500 controls a motor driver 403 to 404 and a head driver 405 to 408 described later according to a control signal input via the interface 400. Further, the control unit 500 processes the input image data.

[0020] The recording apparatus 600 further includes a conveyance motor 401 and a carriage motor 402 as drive sources, and motor drivers 403 and 404 for driving them. The conveyance motor 401 is a motor for rotating a conveyance roller 103 for conveying the recording medium 107. The carriage motor 402 is a motor for reciprocating a carriage 106 on which recording heads 201 to 204 are mounted. The motor driver 403 is a driver for driving the conveyance motor 401, and the motor driver 404 is a driver for driving the carriage motor 402.

[0021] Furthermore, the recording apparatus 600 includes head drivers 405 to 408 for driving the recording heads 201 to 204. In the first embodiment, the head driver 405 drives the recording head 201, the head driver 406 drives the recording head 202, the head driver 407 drives the recording head 203, and the head driver 408 drives the recording head 204.

[0022] ​FIG. 3 is an explanatory diagram of image data processing by an image processing system, and is a functional block diagram showing a schematic configuration for performing image data processing. The image processing system according to the first embodiment includes a recording device 600 and a host PC 1200. The control unit 500 of the recording device 600 processes data transferred from the host PC 1200 in which a printer driver is installed via the interface 400.

[0023] The host PC 1200 receives input image data 1000 from an application. First, a rendering process 1001 is performed at a resolution of 1200 dpi based on the received input image data 1000. Thereby, recording multi-value RGB data 1002 is generated. In the first embodiment, the recording multi-value RGB data 1002 is data with 256 values for each of RGB. The generated recording multi-value RGB data 1002 is transferred to the control unit 500.

[0024] The control unit 500 performs a color conversion process 1007 for converting the recording multi-value RGB data 1002 into multi-value CMYK data 1008. The multi-value CMYK data 1008 is data with 256 values for each of CMYK. Next, the multi-value CMYK data 1008 is quantized (binarized) by a quantization process 1009 (for example, error diffusion method or dither method). Thereby, 2-value CMYK data 1010 with a resolution of 1200 dpi is generated.

[0025] (Adjustment of ejection timing) Next, the adjustment of the ejection timing of the ink in the recording heads 201 to 204 will be described. The recording heads 201 to 204 each have a plurality of nozzles, and ink is ejected from each nozzle. Therefore, if the ejection timing of each nozzle is not appropriate, the image will be misaligned and recorded on the recording medium. In particular, in an inkjet color printer or the like, in order to maintain good image quality, it is necessary that the images of each color formed by a plurality of recording heads be accurately overlapped pixel by pixel, and it is important that the ejection timing of the plurality of nozzles is accurately adjusted.

[0026] Figs. 4(a) to 4(d) are explanatory diagrams of an example of a method for adjusting the ejection timing of ink. Fig. 4(a) shows the state in which ink dots fly from the recording heads 201 to 204 to the recording medium 107. As described above, the recording heads 201 to 204 eject ink dots while the carriage 106 is performing main scanning in the X direction. For example, when it is desired to place the ink dots ejected from the recording heads 201 to 204 at the same position on the recording medium 107, it is necessary to eject the ink dots from each recording head with a time difference corresponding to the scanning speed of the carriage 106. The adjustment of this time difference is expressed as the adjustment of the ejection timing. Also, when the ejection speeds of the ink dots ejected from each recording head are different, or when the direction in which the ink dots are ejected is inclined, it is necessary to adjust the ejection timing accordingly. Hereinafter, examples of the adjustment of the ejection timing will be described.

[0027] Fig. 4(b) shows an example of a pattern for adjusting the ejection timing. The recording head has a plurality of nozzle arrays in which a plurality of nozzles are arranged in the sub-scanning direction (Y direction), and ejects ink dots from each nozzle to generate recording dots on the recording medium. In Fig. 4(b), the recording dots are indicated by circles. Note that although the recording dots are shown as circles in Fig. 4(b) for convenience, they may not be perfect circles as illustrated depending on the characteristics of the recording medium and the like. The ink dot 301 indicated by the hatched circle is the ink dot ejected from the recording head 201, and the ink dot 302 indicated by the non-hatched circle is the ink dot ejected from the recording head 202.

[0028] Figure 4(b) shows patterns for five conditions (conditions 1 to 5) in which the ejection timings of the recording head 201 and the recording head 202 are relatively shifted. Taking the recording head 201 as a reference, in condition 1, the ejection timing of the recording head 202 is the latest, and in condition 5, the ejection timing of the recording head 202 is the earliest. That is, from condition 1 to condition 5, the ejection timing of the recording head 202 relative to the ejection timing of the recording head 201 is gradually advanced. By such a recording method, patterns in which the deviation amounts of the ink dots 301 and 302 in the main scanning direction (X direction) are different from each other are formed.

[0029] In forming such patterns, only the ejection timing of the recording head 202 is changed without changing the ejection timing of the recording head 201. That is, in the first embodiment, the ejection timing of the recording head 202 is adjusted with respect to the ejection timing of the recording head 201. Taking the ejection timing of the recording head 201 as a reference, the ejection timing of the recording head 202 is adjusted as a non-reference. For example, in the patterns for the five conditions shown in Figure 4(b), when it is condition 3, the ink dots 301 and 302 are ejected at substantially the same position, and the deviation amount in the main scanning direction is the smallest. In such a case, the ejection timing of the recording head 202 in condition 3 (more precisely, the difference in the ejection timing of the recording head 202 with respect to the recording head 201) is memorized, and in the next recording operation (printing), recording is performed using that ejection timing. By such an adjustment method, the ejection timings of the recording head 201 and the recording head 202 are adjusted, and a decrease in image quality is suppressed. In the first embodiment, the control unit 500 that controls the operation of each recording head functions as an adjustment means for performing the adjustment of the ejection timing.

[0030] In adjusting the ejection timing using a pattern, it may be configured such that the user selects and inputs the conditions to be adopted from Conditions 1 to 5, or it may be configured such that the pattern is read by an image reading means such as a scanner and the conditions are automatically determined. Also, instead of directly adopting the conditions under which the pattern was generated, it may be configured to obtain optimal conditions from the deviation amount between the ink dots 301 and 302.

[0031] Note that in the above adjustment example, the recording head 201 was described as the reference recording head, but any one of the recording heads 202 to 204 can also be selected as the reference. When selecting the reference recording head, factors such as the stability of the ejection operation, the density of the ejected ink, the position of the recording head, and the line of action of the moving force received by the recording head may be considered. For example, when considering the visibility of the pattern, it is better for the density of the ejected ink to be higher.

[0032] Also, when the recording head 201 is adopted as the reference for adjusting the ejection timing of the recording head 202, the recording head 203 may be adopted as the reference for adjusting the ejection timing of the recording head 204. In this case, as the first adjustment, the ejection timing of the recording head 202 is adjusted based on the recording head 201, and as the second adjustment, the ejection timing of the recording head 204 is adjusted based on the recording head 203. Then, as the third adjustment, the ejection timing of the other one is adjusted based on either the recording head 201 or the recording head 203. In the first to third adjustments, an adjustment pattern is generated each time. At this time, for example, when adjusting the ejection timing of the recording head 203 based on the recording head 201, it is necessary to perform the same adjustment on the recording head 204 as the ejection timing adjustment applied to the recording head 203. That is, the ejection timing of the recording head 204 will be adjusted twice.

[0033] Fig. 4(c) shows an example of the relationship between a reference recording head and a non-reference recording head. In Fig. 4(cc), the recording head from which the arrow extends is non-reference, and the recording head to which the arrow extends is reference. That is, the relationship between the reference recording head and the non-reference recording head is shown in such a way that the ejection timing is adjusted in the direction of the arrow. In the example shown in Fig. 4(c), as described above the ejection timing of recording head 204 is adjusted with recording head 203 as a reference, and the ejection timings of recording heads 202 and 203 are adjusted with recording head 201 as a reference. In this example, as a result, the ejection timings of the nozzles of recording heads 202 to 204 are adjusted to match the ejection timing of the nozzle of recording head 201.

[0034] Fig. 4(d) shows an example of the relationship between a reference recording head and a non-reference recording head, similar to Fig. 4(c). In the example shown in Fig. 4(d), the ejection timings of recording heads 202, 203, and 204 are adjusted with recording head 201 as a reference. In this way, it is also possible to unify the reference recording head and simplify the relationship between the reference and non-reference. Also, in the example of Fig. 4(c), it can be said that the final reference head is recording head 201, similar to the example of Fig. 4(d).

[0035] In this way, by designating a certain recording head as the reference head and adjusting the ejection timings of the other recording heads to match the reference head, it becomes possible to output the image specified by the user on the host PC 1200 or the like with good image quality. It is desirable to perform this adjustment of the ejection timing periodically. This is because the ejection speed may change over time due to deterioration of the drive element of the recording head or the like. Also, when the type of the recording medium changes and its thickness changes, the distance between the recording head and the recording medium changes, so it is important to adjust the ejection timing in order to perform high-quality recording.

[0036] Adjustment of the main scanning speed of carriage 106 and adjustment of the ejection timing are performed based on timing pulses detected using an encoder (not shown). By arranging an encoder over the moving range of carriage 106 and reading it with a sensor, the moving speed of carriage 106 can be detected, and the moving distance in the main scanning direction (X direction) can be detected. Also, in Example 1, the recording apparatus 600 records at 1200 dpi. As the encoder, an encoder having a slit with a resolution of 1200 dpi may be used, or an encoder with a lower resolution may be used while multiplying the encoder signal to make it 1200 dpi. In order to increase the adjustment resolution of the ejection timing, it is desirable that the signal has an even higher resolution, and it is desirable to adjust the timing at 2400 dpi, 4800 dpi, 9600 dpi, etc. For example, when adopting a 9600 dpi signal, the recording head thins out the signal by a factor of 1 / 8 to perform recording at 1200 dpi, and adjusts the ejection timing by shifting the phase.

[0037] (Defects in ejection of recording head) As a defect in an inkjet recording head, there is an ejection defect where ink cannot be ejected normally. The ejection defect occurs, for example, due to clogging of the nozzles of the recording head, adhesion due to evaporation of moisture in the ink present in the nozzles of the recording head, or electrical disconnection of the recording head. Hereinafter, the state in which the recording head falls into such an ejection defect will be described as a non-ejection state.

[0038] In a recording apparatus having a recording head that has fallen into a non-ejecting state, it is difficult to record with good image quality. However, if the number of nozzles that have reached the non-ejecting state is about several, since it is difficult to visually recognize a deterioration in image quality, it is possible to continue using the recording head as it is, or to reduce the deterioration of image quality by performing non-ejecting compensation that complements the non-ejecting nozzles with alternative nozzles. Also, restoring the state of the nozzles by the maintenance operation of the recording apparatus is also cited as one of the countermeasures against ejection failures. However, depending on the non-ejecting interpolation operation or the maintenance operation, the deterioration of image quality cannot be sufficiently suppressed, and when the image quality of the recording medium recorded by the recording apparatus is unacceptable, it is necessary to replace the recording head in the non-ejecting state. However, since replacing the recording head is costly, it is also conceivable to continue using the recording head in the non-ejecting state as it is even in a state where the original image quality cannot be obtained. To cope with the case of continuing to use the recording head in the non-ejecting state, for example, when the recording head for black ink becomes non-ejecting, the remaining recording heads for cyan, magenta, and yellow inks are used for alternative recording, and such a configuration is also disclosed. That is, continuing to use the recording head in the non-ejecting state is not something that is never done.

[0039] However, when the recording head (reference head) that serves as the reference for adjusting the ejection timing becomes non-ejecting and it becomes impossible to record the timing adjustment pattern, it becomes difficult to adjust the ejection timing of the remaining recording heads. As described above, it is desirable to perform the adjustment of the ejection timing periodically, but it becomes difficult to perform the adjustment of the ejection timing after the reference head has become non-ejecting. Then, in addition to the ejection failure of the reference head, it becomes impossible to match the ejection timing of the recording heads other than the reference head, so there is a risk that the image quality will deteriorate further.

[0040] Therefore, in the first embodiment, it was decided to change the reference recording head according to the ejection state of the recording head selected as the reference. For example, when the reference recording head 201 is in a non-ejecting state, the recording head 203 is selected as the reference head and the reference head is changed, so that the ejection timings of at least the recording heads 202, 203, and 204 can be matched.

[0041] (Selection of reference head) The method for selecting a reference head in adjusting the ejection timing according to the first embodiment will be described more specifically. FIGS. 5(a) to 5(c) are explanatory diagrams of the method for selecting a reference head in adjusting the ejection timing of the ink according to the first embodiment. FIG. 5(a) shows the relationship between the reference recording head and the non-reference recording head at the initial setting according to the first embodiment. In the first embodiment, similar to the example shown in FIG. 4(c), the ejection timing of the recording head 204 is adjusted based on the recording head 203, and the ejection timings of the recording head 202 and the recording head 203 are adjusted based on the recording head 201. Therefore, when the recording head 201 is not in a non-ejecting state and can normally print the pattern for timing adjustment, in the first embodiment, the timing adjustment is performed in the same manner as the above-described operation example.

[0042] FIG. 5(b) shows the relationship between the reference recording head and the non-reference recording heads when the reference head selected as the reference head in the initial setting according to Example 1 is in a non-ejecting state. In Example 1, when the recording head 201 set as the reference head in the initial setting is in a non-ejecting state, the recording head 203 is selected as the reference head instead of the recording head 201. At this time, since the recording head 201 is in a non-ejecting state, it is difficult to record the pattern for adjusting the ejection timing. However, formally, the ejection timing is adjusted to match that of the recording head 203, which is the reference head. The arrow shown by the dotted line in FIG. 5(b) and extending from the recording head 201 to the recording head 203 indicates that the ejection timing of the recording head 201 is formally adjusted to match that of the recording head 203. In such a case, in Example 1, similar to the example shown in FIG. 4(d), the ejection timings of the other recording heads (recording heads 201, 202, 204) are adjusted based on one recording head (recording head 203) as the reference.

[0043] FIG. 5(c) shows the selection flow of the reference head in the ejection timing adjustment. The selection process of the reference head will be described along the selection flow in FIG. 5(c). In the selection process of the reference head, first, in step (hereinafter, S) 011, it is determined whether the recording head 201 (the first recording head) is in a non-ejecting state. If YES in S011, that is, if the recording head 201 is in a non-ejecting state and the ejection state is abnormal, the process proceeds to S012. On the other hand, if NO in S011, that is, if the recording head 201 is not in a non-ejecting state and the ejection state is normal, the process proceeds to S014. In S014, the recording head 201 is selected (set) as the reference head, and the selection flow ends. In Example 1, the CPU 501 functions as a determination means for determining the ejection state of the recording head 201 and a selection means for selecting the reference head based on the determination result. to function.

[0044] Regarding whether the recording head is in a non-ejecting state (whether the ejection state is normal or abnormal), for example, when a predetermined number or more of nozzles of the recording head are in a non-ejecting state, the recording head may be considered to be in a non-ejecting state. Or, for example, an operation test of the recording head is performed, and whether recording is being normally performed on the recording medium is confirmed by a scanner or the like, and the CPU 501 determines the ejection state of the recording head based on the presence or absence of printing and the density of the recording pattern. Or, for example, the recording apparatus 600 may be configured such that the user can input that the recording head is in a non-ejecting state.

[0045] Also, there are various factors that cause the recording head to fall into a non-ejecting state. Therefore, as acquisition means for acquiring the ejection state of the nozzles of the recording head, it is preferable to use various known acquisition means such as a scanner for visually checking whether the ink is normally attached to the recording medium and a sensor for detecting a disconnection of the recording head. Also, in the case of a configuration in which the user inputs the ejection state of the recording head, an acquisition unit such as the control unit 500 that acquires the input result can also be the acquisition means. In the first embodiment, based on the acquisition result of such acquisition means, the control unit 500 determines the ejection state of the recording head (nozzle).

[0046] In S012, it is determined whether the recording head 203 (the second recording head) is in a non-ejecting state. If YES in S012, that is, if the recording head 203 is in a non-ejecting state and the ejection state is abnormal, the process proceeds to S013. On the other hand, if NO in S012, that is, if the recording head 203 is not in a non-ejecting state and the ejection state is normal, the process proceeds to S015. In S015, the recording head 203 is selected (set) as the reference head, and the selection flow ends.

[0047] In S013, it is determined whether the recording head 202 (the third recording head) is in a non-ejecting state. If it is YES in S013, that is, if the recording head 202 is in a non-ejecting state and the ejection state is abnormal, the process proceeds to S017. On the other hand, if it is NO in S013, that is, if the recording head 202 is not in a non-ejecting state and the ejection state is normal, the process proceeds to S016. In S016, the recording head 202 is selected (set) as the reference head, and the selection flow ends. Also, in S017, the recording head 204 (the fourth recording head) is selected (set) as the reference head, and the selection flow ends. However, when proceeding to S017, all recording heads other than the recording head 204 are in a non-ejecting state, and the ejection timing cannot be substantially adjusted. Therefore, formally, only the recording head 204 is regarded as the reference head. Also, when proceeding to S017, only one of the recording heads for the four colors of ink can eject normally. Therefore, it may be configured to perform a notification process for notifying the user that three recording heads are in a non-ejecting state and the ejection timing is not adjusted after S017. Similarly, when any recording head is in a non-ejecting state, it may be configured to notify the user that the recording head is in a non-ejecting state. When notifying the user, known notification means such as display on the display and warning sound can be used.

[0048] Through the above selection process, in Example 1, when the recording head 201 is in a non-ejecting state, the recording head 203 and the recording head 202 are searched for recording heads that are not in a non-ejecting state, and the reference head is selected. In this way, by selecting the reference head from the recording heads that are not in a non-ejecting state, it becomes possible to adjust the ejection timing among the recording heads other than the recording head that has become in a non-ejecting state. As a result, according to the configuration of Example 1, even when a recording head becomes in a non-ejecting state, the ejection timing can be adjusted, and a decrease in image quality can be suppressed.

[0049] In Example 1, the CPU 501 as the determination means determines the ejection state of the recording head and selects the reference head based on the determination result. However, the configuration is not limited to this. For example, parameters related to the ejection states of a plurality of recording heads are acquired, the parameters related to the ejection states of each recording head are compared, and the optimal recording head is selected as the reference head from among them.

[0050] <Example 2> Next, Example 2 according to the present invention will be described. Hereinafter, in the description of Example 2, the same components and processes as those in Example 1 are denoted by the same reference numerals and the description thereof is omitted, and only the characteristic configuration of Example 2 will be described.

[0051] FIGS. 6(a) and 6(b) are explanatory views of the configuration of the recording apparatus 600 according to Example 2. FIG. 6(a) shows the nozzle configuration of the recording heads 201 to 204 according to Example 2. FIG. 6(b) is a schematic perspective view showing the relationship between the recording heads 201 to 204 and the recording medium 107 according to Example 2. The recording heads 201 to 204 each have four nozzle rows (a row, b row, c row, d row) arranged side by side in the conveyance direction (X direction). Specifically, the recording head 201 has four nozzle rows 201a, 201b, 201c, and 201d. In the nozzle rows 201a to 201d, a plurality of nozzles are arranged in the width direction (Y direction) of the recording medium 107. Similarly, the recording head 202 has four nozzle rows 202a to 202d, the recording head 203 has four nozzle rows 203a to 203d, and the recording head 204 has four nozzle rows 204a to 204d. As shown in FIG. 6(b), the recording heads 201 to 204 have a sufficient width with respect to the width direction of the recording medium 107. Specifically, in the extending direction (Y direction) of the nozzle rows, the widths of the nozzle rows of the recording heads 201 to 204 are configured to be larger than the width of the largest-width recording medium 107 that can be conveyed by the recording apparatus 600. Therefore, in the recording apparatus 600 according to Example 2, recording can be performed by conveying only the recording medium 107 in the conveyance direction (X direction) while fixing the position of the recording head without moving it.

[0052] (Selection of reference nozzle rows) Figs. 7(a) and 7(b) are explanatory diagrams of a method for selecting a reference nozzle row in adjusting the ink ejection timing according to Embodiment 2. In Embodiment 2, the ink ejection timing is adjusted for each nozzle row even within a single recording head. Fig. 7(a) shows the relationship between the reference nozzle row and non-reference nozzle rows at the initial setting according to Embodiment 2. In each of the recording heads 201 to 204, the nozzle row in column a is set as the reference nozzle row. And between the recording heads, the recording head 201 is set as the reference head for the recording heads 202 to 204. That is, the nozzle row 201a of the recording head 201 serves as a reference for the nozzle rows 201b, 201c, 201d of the recording head 201, the nozzle row 202a of the recording head 202, the nozzle row 203a of the recording head 203, and the nozzle row 204a of the recording head 204. In this example, as a result, the ejection timing of the nozzles in the nozzle row 201a of the recording head 201 is adjusted so that the ejection timings of the nozzles in the nozzle rows other than the nozzle row 201a of the recording head 201 are matched.

[0053] Fig. 7(b) shows a selection flow of the reference nozzle row in the ejection timing adjustment. Along the selection flow in Fig. 7(b), taking the selection process of the reference nozzle row of the recording head 201 as an example, the selection process of the reference nozzle row will be described. In the selection process of the reference nozzle row, first, in S021, it is determined whether the nozzle row 201a (the first nozzle row) is in a non-ejection state. If YES in S021, that is, if the nozzle row 201a is in a non-ejection state and the ejection state is abnormal, the process proceeds to S022. On the other hand, if NO in S021, that is, if the nozzle row 201a is not in a non-ejection state and the ejection state is normal, the process proceeds to S024. In S024, the nozzle row 201a is selected (set) as the reference nozzle row, and the selection flow ends. In Embodiment 2, the CPU 501 functions as a determination means for determining the ejection state of the nozzle row 201a and a selection means for selecting a reference nozzle row based on the determination result.

[0054] In S022, it is determined whether the nozzle row 201b (the second nozzle row) is in a non-ejection state A determination is made. If the answer is YES in S022, that is, if the nozzle row 201b is in a non-ejection state and the ejection state is abnormal, the process proceeds to S023. On the other hand, if the answer is NO in S022, that is, if the nozzle row 201b is not in a non-ejection state and the ejection state is normal, the process proceeds to S025. In S025, the nozzle row 201b is selected (set) as the reference nozzle row, and the selection flow ends.

[0055] In S023, a determination is made as to whether the nozzle row 201c (the third nozzle row) is in a non-ejection state. If the answer is YES in S023, that is, if the nozzle row 201c is in a non-ejection state and the ejection state is abnormal, the process proceeds to S027. On the other hand, if the answer is NO in S023, that is, if the nozzle row 201c is not in a non-ejection state and the ejection state is normal, the process proceeds to S026. In S026, the nozzle row 201c is selected (set) as the reference nozzle row, and the selection flow ends. Also, in S027, the nozzle row 201d (the fourth nozzle row) is selected (set) as the reference nozzle row, and the selection flow ends. When the process proceeds to S027, all nozzle rows other than the nozzle row 201d in the recording head 201 are in a non-ejection state, but the ejection timings of the nozzle rows of other recording heads are adjusted to match the nozzle row 201d.

[0056] In the second embodiment, in each recording head, the above-described selection process of the reference nozzle row is performed. Therefore, there may be a case where the nozzle row to be set as the reference nozzle row among the a column, b column, c column, and d column is different depending on the recording head. That is, in the second embodiment, the column to be used as the reference nozzle row may be different depending on the ink color of each recording head.

[0057] In addition, in Example 2, in addition to the above-described selection process of the reference nozzle rows, the selection process of the reference head shown in FIG. 5(c) is also performed in the same manner, and the reference nozzle row is selected from a total of 16 nozzle rows. In the selection flow of the reference head, for example, when all the nozzle rows 201a to 201d are in a non-ejection state, the recording head 201 may be configured to determine that it is in a non-ejection state. However, the present invention is not limited to such a configuration. For example, without performing the selection process of the reference head, the selection process of the reference nozzle row as shown in FIG. 7(b) may be performed for 16 nozzle rows to select the reference nozzle row.

[0058] Note that the adjustment pattern described in Example 1 records by shifting the ejection timing with respect to a certain reference. However, in Example 2, since there are 15 non-reference nozzle rows, both the number of patterns and the pattern area become larger. Therefore, an adjustment method as disclosed in Japanese Patent Application Laid-Open No. 2015-163475 may be adopted. That is, the distance between the patterns recorded in each row using a certain ejection timing may be measured, and the correction of the ejection timing may be derived based on the error between the ideal pattern interval and the measured pattern interval.

[0059] (Pattern for ejection timing adjustment) FIGS. 8(a) and 8(b) are explanatory views of an example of a pattern for ejection timing adjustment. FIG. 8(a) is an example of a pattern recorded by each nozzle row in adjusting the ejection timing. At the downstream end of the pattern in the conveyance direction (the upper end in FIG. 8(a)), a bar which is a mark for recognizing the start of the pattern is provided. In addition, the black square portions other than the bar indicate the positions of the dots recorded by the nozzle row. A large number of dots are arranged for averaging.

[0060] FIG. 8(b) shows an example in which the pattern shown in FIG. 8(a) is recorded in each nozzle row. In FIG. 8(b), the pattern formed by ejecting ink from the nozzles of nozzle row 201a is expressed as pattern 301a. Similarly, FIG. 8(b) shows pattern 301b corresponding to nozzle row 201b, pattern 301c corresponding to nozzle row 201c, …, and pattern 304 corresponding to nozzle row 204d. That is, FIG. 8(b) shows a total of 16 patterns 301a to 301d, 302a to 302d, 303a to 303d, 304a to 304d corresponding to 16 nozzle rows 201a to 201d, 202a to 202d, 203a to 203d, 204a to 204d.

[0061] When adjusting the ejection timing using the patterns shown in FIGS. 8(a) and 8(b), the recorded pattern is read by a scanner or the like, and the distance between the patterns is measured. The distance between the analyzed patterns is the interval at which the ink dots are actually placed on the paper. On the other hand, the distance between the patterns in the print command held in the memory 502 by the control unit 500 before recording is the ideal distance between the patterns. Since the error between these ideal distances between the patterns and the measured distance between the patterns is the deviation between the image held in the memory in the control unit 500 and the actual dot positions to be output, this deviation can be corrected as the ejection timing. When using this pattern, regardless of whether the recording head or nozzle row is in a non-ejecting state, the same pattern may be recorded, and a reference head or reference nozzle row may be selected during pattern analysis.

[0062] Also in the second embodiment, the determination of whether the recording head or the recording row is non-ejecting may be made by means for separately determining the ejection state, or may be determined based on the fact that the density of the recording pattern is low (or the same density as the paper white).

[0063] In a configuration in which a large number of nozzle rows capable of recording the same color are provided as in the second embodiment, even if a certain nozzle row is in a non-ejecting state, there may be an alternative nozzle row for alternative recording, so it is desirable to perform non-ejecting compensation with the alternative nozzle row.

[0064] With the above selection process, in the second embodiment, when the nozzle row 201a of the recording head 201 is in a non-ejecting state, the nozzle rows 201b and 201c and the nozzle rows that are not in the non-ejecting state are searched for, and a reference nozzle row is selected. In this way, by selecting the reference nozzle row from the nozzle rows that are not in the non-ejecting state, it becomes possible to adjust the ejection timing among the nozzle rows other than the nozzle row that has become in the non-ejecting state. As a result, according to the configuration of the second embodiment, even when a nozzle row becomes in the non-ejecting state, it is possible to adjust the ejection timing and suppress a decrease in image quality.

[0065] In addition, in the first embodiment and the second embodiment, a nozzle row or a recording head including a plurality of nozzles has been used as a reference for adjusting the ejection timing. However, it is also possible to use a single nozzle as a reference and change the reference nozzle according to the ejection state of the nozzle. Even in such a case, the ejection states of the nozzles constituting a plurality of recording heads or a plurality of nozzle rows may be acquired, and the reference nozzle may be selected based on the acquisition result. That is, in the first embodiment and the second embodiment, a plurality of reference nozzles have been set, but a configuration may be adopted in which only one reference nozzle is set.

[0066] Also, in the application of the present invention, the processes described as being performed by one device in the above-described respective embodiments may be executed in a shared manner by a plurality of devices. Alternatively, the processes described as being performed by different devices may be executed by one device. In a computer system, how each function is realized by a hardware configuration can be flexibly changed.

[0067] The disclosure of the present embodiment includes the following configurations and methods. (Configuration 1) A recording apparatus that ejects a liquid onto a recording medium to record an image, a plurality of nozzles that eject a liquid, adjusting means for adjusting the ejection timing of the plurality of nozzles, acquiring means for acquiring the ejection state of the nozzles, Selection means for selecting a reference nozzle as a reference for adjusting the discharge timing from among the plurality of nozzles based on the acquisition result of the acquisition means; A recording apparatus characterized by comprising the same. (Configuration 2) Judgment means for judging whether the discharge state is normal or abnormal based on the acquisition result of the acquisition means is provided; The recording apparatus according to Configuration 1, wherein the selection means selects the reference nozzle based on the judgment result of the judgment means. (Configuration 3) The plurality of nozzles include a first nozzle and a second nozzle; The recording apparatus according to Configuration 2, wherein the selection means selects the first nozzle as the reference nozzle when the determination means determines that the discharge state of the first nozzle is normal, and selects the second nozzle as the reference nozzle when the determination means determines that the discharge state of the first nozzle is abnormal. (Configuration 4) The plurality of nozzle rows include a third nozzle; The recording apparatus according to Configuration 3, wherein the selection means selects the second nozzle as the reference nozzle when the discharge state of the first nozzle is abnormal and the discharge state of the second nozzle is normal, and selects the third nozzle as the reference nozzle when the discharge state of the second nozzle is abnormal. (Configuration 5) The recording apparatus according to any one of Configurations 2 to 4, wherein the determination means determines that the discharge state is abnormal when the nozzle cannot generate a pattern for adjusting the discharge timing. (Configuration 6) The recording apparatus according to any one of Configurations 2 to 4, wherein the determination means determines that the discharge state is abnormal when the nozzle is in a state where it cannot discharge liquid. (Configuration 7) The recording apparatus according to any one of Configurations 2 to 6, further comprising notification means for notifying the user that there is an abnormality in the nozzle when the discharge state is abnormal. (Configuration 8) Comprising a plurality of nozzle rows configured by arranging a plurality of nozzles, The recording apparatus according to any one of Configurations 1 to 7, wherein the selection means selects, as a reference nozzle row, the nozzle row including the reference nozzle. (Configuration 9) Transport means for transporting a recording medium in a transport direction, A recording head in which the plurality of nozzle rows are formed, Comprising, The recording apparatus according to Configuration 8, wherein while the position of the recording head is fixed, the recording medium is transported in the transport direction by the transport means, and liquid is discharged from the recording head onto the recording medium to record an image. (Configuration 10) The recording apparatus according to Configuration 8 or 9, wherein in the extending direction of the nozzle row, the width of the nozzle row is larger than the width of the recording medium. (Configuration 11) Comprising a plurality of recording heads each having a plurality of the nozzles, The recording apparatus according to any one of Configurations 1 to 7, wherein the selection means selects, as a reference head, the recording head including the reference nozzle. (Configuration 12) A transport unit for transporting a recording medium in a transport direction, A holding unit that holds the plurality of recording heads and is movable in a moving direction intersecting the transport direction, Comprising, The recording apparatus according to Configuration 11, wherein while the holding unit is moved in the moving direction, liquid is discharged from the recording head onto the recording medium to record an image. (Method 1) A method for adjusting the discharge timing of a recording apparatus that includes a plurality of nozzles for discharging liquid and discharges liquid onto a recording medium to record an image, A method for adjusting the discharge timing of a recording apparatus, characterized in that a reference nozzle for adjusting the discharge timing is selected from among the plurality of nozzles based on the discharge states of the plurality of nozzles. (Method 2) A method for adjusting the ejection timing of a recording apparatus according to Method 1, which is characterized by determining the ejection states of the plurality of nozzles and changing the reference nozzle to a different nozzle when the ejection states of the nozzle set as the reference nozzle in the initial setting are abnormal.

Explanation of Signs

[0068] 107…Recording medium, 600…Recording apparatus

Claims

1. A recording apparatus that records an image by discharging a liquid onto a recording medium, comprising: a plurality of nozzles that discharge the liquid; adjusting means for adjusting the discharge timing of the plurality of nozzles; acquiring means for acquiring the discharge state of the nozzles; selection means for selecting a reference nozzle as a reference for adjusting the discharge timing from among the plurality of nozzles based on the acquisition result of the acquiring means; A recording apparatus characterized by comprising the above.

2. Determining means for determining whether the discharge state is normal or abnormal based on the acquisition result of the acquisition means is provided, The recording apparatus according to claim 1, wherein the selection means selects the reference nozzle based on the determination result of the determination means.

3. The plurality of nozzles include a first nozzle and a second nozzle, The selection means selects the first nozzle as the reference nozzle when the determination means determines that the discharge state of the first nozzle is normal, and selects the second nozzle as the reference nozzle when the determination means determines that the discharge state of the first nozzle is abnormal. The recording apparatus according to claim 2, characterized by the above.

4. The plurality of nozzle rows include a third nozzle, The selection means selects the second nozzle as the reference nozzle when the discharge state of the first nozzle is abnormal and the discharge state of the second nozzle is normal, and selects the third nozzle as the reference nozzle when the discharge state of the second nozzle is abnormal. The recording apparatus according to claim 3, characterized by the above.

5. The recording apparatus according to claim 2, wherein the determination means determines that the discharge state is abnormal when the nozzle cannot generate a pattern for adjusting the discharge timing.

6. The recording apparatus according to claim 2, wherein the determination means determines that the discharge state is abnormal when the nozzle is in a state where it cannot discharge the liquid.

7. The recording apparatus according to claim 2, further comprising notification means for notifying the user that there is an abnormality in the nozzle when the discharge state is abnormal.

8. A plurality of nozzle rows formed by arranging a plurality of nozzles are provided, The recording apparatus according to claim 1, wherein the selection means selects a nozzle row including the reference nozzle as a reference nozzle row.

9. Transport means for transporting the recording medium in a transport direction; a recording head in which the plurality of nozzle rows are formed; A recording apparatus comprising the above. The recording apparatus according to claim 8, wherein, with the position of the recording head fixed, liquid is discharged from the recording head onto a recording medium while the recording medium is conveyed in the conveying direction by the conveying means to record an image.

10. The recording apparatus according to claim 8, wherein the width of the nozzle array is larger than the width of the recording medium in the extending direction of the nozzle array.

11. comprising a plurality of recording heads each having a plurality of the nozzles, The recording apparatus according to claim 1, wherein the selection means selects a recording head including the reference nozzle as a reference head.

12. a conveying unit that conveys a recording medium in a conveying direction; a holding unit that holds the plurality of recording heads and is movable in a moving direction intersecting the conveying direction; and The recording apparatus according to claim 11, wherein an image is recorded by discharging liquid from the recording head onto the recording medium while moving the holding unit in the moving direction.

13. A method for adjusting the discharge timing of a recording apparatus that includes a plurality of nozzles for discharging liquid and records an image by discharging the liquid onto a recording medium, the method comprising: selecting, based on the discharge states of the plurality of nozzles, a reference nozzle as a reference for adjusting the discharge timing from among the plurality of nozzles.

14. The method for adjusting the discharge timing of a recording apparatus according to claim 13, wherein the discharge states of the plurality of nozzles are determined, and when the discharge state of a nozzle set as the reference nozzle in an initial setting is abnormal, the reference nozzle is changed to a different nozzle.

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