Patent ID: 12240251

DETAILED DESCRIPTION

Next, an embodiment of the present disclosure will be described while referring to the accompanying drawings, but the present disclosure is not limited to the following embodiments. Further, in the following description components in all drawings that are the same or equivalent are designated with the same reference numerals to avoid duplicating description.

The functions of components disclosed in the present specification can be implemented using circuits or processing circuits configured or programmed to execute the disclosed functions, including a general-purpose processor, a dedicated processor, integrated circuits, application-specific integrated circuits (ASICs), conventional circuits, and/or a combination of these. The processors may be treated as processing circuits since they include transistors and other circuits. In this specification, circuits, units, or means are hardware for executing the given functions or hardware programmed to execute the given functions. This hardware may be hardware disclosed in this specification or other known hardware programmed or configured to implement the given functions. In the case of hardware being a processor treated as a type of circuit, the circuit, means, or unit is a combination of hardware and software, and software is used to configure the hardware and/or processor.

FIG.1is a perspective view showing a printing apparatus1provided with a liquid ejecting device20according to one embodiment. Directions indicated inFIG.1are an up-down direction, left-right direction, and front-rear direction that are each orthogonal to the others. The left-right direction is also a main scanning direction Ds, and the front-rear direction is also a sub scanning direction Df (equivalent to the conveying direction). Thus, the sub scanning direction Df is orthogonal to the main scanning direction Ds. As an alternative, the sub scanning direction Df may be a direction that crosses the main scanning direction Ds. This printing apparatus1is configured to print on a recording medium W. However, the printing apparatus1is not only capable of printing on a recording medium W configured of printing paper or the like but is also capable of printing on a non-permeable medium such as a recording medium W formed of a resin or metal material.

As shown inFIG.1, the printing apparatus1according to the present embodiment is provided with a casing2, operating keys4, a display/input unit5, a tray7, a top cover8, and the liquid ejecting device20. In the present embodiment, the liquid ejecting device20has a carriage3, a medium conveying mechanism9(seeFIG.3) that includes a stage6, two ejection heads10(a first head10A and a second head10B), and a control device71(seeFIGS.3and4). In the following description, the ejection heads10will be simply referred to as heads10.

FIG.2is a plan view showing a sample configuration of the heads10mounted in the carriage3of the printing apparatus1, and a mechanism of the printing apparatus1that supplies ink to these heads10. As shown inFIGS.1and2, the first head10A is provided with a plurality of nozzle rows for ink in the colors yellow (Y), magenta (M), cyan (C), and black (K), for example, often referred to as color ink. These nozzle rows are arranged at regular intervals in the main scanning direction Ds. Each of the nozzle rows includes a plurality of nozzles11arranged at regular intervals along the sub scanning direction Df. The nozzles11eject ink of the corresponding color. The second head10B is configured similarly to the first head10A and has a plurality of nozzles11that eject ink of the same colors as the first head10A. The first head10A and second head10B are arranged at different positions from each other in the sub scanning direction Df. For example, the first head10A is arranged upstream from the second head10B in the sub scanning direction Df. The first head10A and second head10B are arranged such that the downstream ends of nozzle rows in the first head10A overlap the upstream ends of nozzle rows in the second head10B in the sub scanning direction Df.

During printing, the printing apparatus1controls the first head10A and second head10B not to eject ink from some nozzles11in order that the dimension in the sub scanning direction Df of a region printed by the first head10A is equivalent to the dimension in the sub scanning direction Df of the region printed by the second head10B in one movement of the carriage3. Specifically, during printing the first head10A and second head10B are controlled so that the first head10A does not eject ink from nozzles11in its nozzle rows that are further downstream from nozzles11corresponding to the downstream edge of the region being printed by the first head10A, and so that the second head10B does not eject ink from nozzles11in its nozzle rows that are further upstream of nozzles11corresponding to the upstream edge of the region being printed by the second head10B. This control easily ensures that the dimension in the sub scanning direction Df of the region printed by the first head10A matches the dimension in the sub scanning direction Df of the region printed by the second head10B. This control can also prevent a gap from appearing between the region printed by the first head10A and the region printed by the second head10B. Further, the first head10A and second head10B are detachably provided in the carriage3and are replaceable.

The casing2is formed in a box shape, for example. The casing2has an opening2aformed in the front surface thereof. The operating keys4are provided in a location rightward and forward of the casing2. The display/input unit5is disposed in a position to the rear of the operating keys4. The operating keys4receive operations inputted by the user. The display/input unit5is a touchscreen-type display, for example, that displays prescribed information. The display/input unit5may also function as operating keys at prescribed timings. The control device71implements a print function based on input from the operating keys4and display/input unit5or external input via a network interface70described later and controls displays on the display/input unit5.

The carriage3is configured to be capable of reciprocally moving in the main scanning direction Ds. The heads10are supported in the carriage3. Accordingly, the heads10can also reciprocate in the main scanning direction Ds.

The liquid ejecting device20has an ink tank51. The ink tank51is disposed outside the carriage3, for example. The ink tank51has an ink tank for each of the colors yellow (Y), magenta (M), cyan (C), and black (K). A first ink tube52configured of ink channels for each color connects the ink tank for each color with nozzles11in the first head10A that eject ink of the corresponding color. A second ink tube53also configured of ink channels for each color connects the ink tank for each color with nozzles11in the second head10B that eject ink of the corresponding color. The first ink tube52and second ink tube53are flexible tubes that supply ink from the ink tank51to each nozzle to be ejected.

The medium conveying mechanism9has the stage6, which is configured to support the recording medium W. The stage6is configured of a rectangular plate member having a prescribed thickness and a longitudinal dimension oriented in the sub scanning direction Df, for example. The medium conveying mechanism9conveys the stage6in the sub scanning direction Df (i.e., frontward) and in a direction opposite to the sub scanning direction Df (i.e., rearward), and is capable of moving the stage6between a printing position at which printing is performed on the recording medium W and a mounting/detaching position for mounting a recording medium W on the stage6or removing the recording medium W from the stage6. In the printing position, the stage6opposes the heads10. In the mounting/detaching position, the stage6is outside the casing2, enabling the recording medium W to be placed on or removed from the stage6.

Prior to printing, the medium conveying mechanism9moves the stage6that supports the recording medium W in the direction opposite to the sub scanning direction Df. During printing, the medium conveying mechanism9moves the stage6in the sub scanning direction Df (i.e., the conveying direction) in order to convey the recording medium W resting on the stage6in the conveying direction. When printing is complete, the medium conveying mechanism9further moves the stage6in the sub scanning direction Df (i.e., the conveying direction) in order to discharge the recording medium W from the opening2aformed in the front surface of the casing2.

The tray7is provided beneath the stage6. The tray7is configured of a rectangular plate material having a prescribed thickness and a longitudinal dimension oriented in the sub scanning direction Df, for example. When the front edge of the top cover8is lifted upward, the top cover8is configured to pivot upward about the rotatable base edge, thereby exposing the interior of the casing2.

Next, other structures of the printing apparatus1provided with the liquid ejecting device20according to the present embodiment will be described with reference to block diagrams.

FIG.3is a block diagram schematically showing a sample configuration of the printing apparatus1. Note that inFIGS.2and15arrows for the main scanning direction Ds and sub scanning direction Df denote the direction from the upstream side toward the downstream side. In addition to the components described above, the printing apparatus1according to the present embodiment is provided with a network interface70, a control device71configured of a CPU and the like, a storage device75having a memory such as a RAM and a ROM, a head driver IC74, a storage medium reading device77, motor driver ICs30and32, a conveying motor31, and a carriage motor33, as illustrated inFIG.3. The conveying motor31actuates the stage6via the medium conveying mechanism9. When actuated, the stage6conveys the recording medium W in the conveying direction (i.e., the sub scanning direction Df), which is a direction orthogonal to the direction that the carriage3moves (i.e., the main scanning direction Ds). The conveying motor31, stage6, and medium conveying mechanism9are examples of the claimed conveying device. The control device7is an example of the claimed computer of the present disclosure.

FIG.4is a block diagram schematically illustrating a sample configuration of the control device71. As its functional configuration, the control device71has an operating mode setting unit81, an active head selecting unit82, a printing unit83, a control history storing unit84, a cleaning unit85, a color calibrating unit86, and a final print data generating unit87. The control device71can functionally implement the operating mode setting unit81, active head selecting unit82, printing unit83, control history storing unit84, cleaning unit85, color calibrating unit86, and final print data generating unit87described above by executing a prescribed program.

The operating mode setting unit81executes an operating mode setting process for setting the operating mode of the printing apparatus1to one of a plurality of modes including a first mode and a second mode. The second mode is an operating mode for printing images with higher color reproducibility than in the first mode. For example, the operating mode setting unit81stores the current operating mode in the storage device75. The operating mode setting unit81sets the operating mode based on the results of color calibration (described later in greater detail). However, the present disclosure is not limited to this method of setting the operating mode. For example, the operating mode setting unit81may set the operating mode to a mode specified in an operating mode selection command inputted by the user on the display/input unit5or a computer200(described later).

The active head selecting unit82executes an active head selection process for selecting one of the first head10A and second head10B to be the active head used during the second mode. The active head selecting unit82further possesses a first selecting unit82athat executes a first selection process, a second selecting unit82bthat executes a second selection process, a third selecting unit82cthat executes a third selection process, and a fourth selecting unit82dthat executes a fourth selection process.

The printing unit83executes printing processes. The printing unit83also has an ink ejecting unit83a, a conveying unit83c, and a carriage moving unit83d.

The ink ejecting unit83aexecutes an ejection process for controlling the heads10to eject the color inks described above. Specifically, the ink ejecting unit83adirects the head driver IC74to control the operations of actuators in the heads10based on raster data for ejecting ink droplets according to the image being formed on the recording medium W. The heads10eject color ink under control of the head driver IC74. When the operating mode is set to the first mode, the ink ejecting unit83aexecutes a printing operation by ejecting ink from both the first head10A and second head10B. When the operating mode is set to the second mode, the ink ejecting unit83aexecutes a printing operation by ejecting ink from the active head while not ejecting ink from the heads10other than the active head.

The conveying unit83cexecutes a conveying process for driving the conveying motor31that actuates the medium conveying mechanism9to convey the stage6and recording medium W. When the conveying motor31is driven, the recording medium W is first conveyed from the downstream side toward the upstream side in the sub scanning direction Df, and then conveyed from the upstream side toward the downstream side in the sub scanning direction Df. When a printing process is executed, conveyance of the recording medium W toward the downstream side in the sub scanning direction is executed alternately with movements of the carriage3. When the operating mode is set to the first mode, the conveying unit83cconveys the recording medium W a distance equivalent to the dimension in the sub scanning direction Df of a region printed with two heads10(i.e., the first head10A and second head10B) during one movement of the carriage3(a distance of two heads worth). When the operating mode is set to the second mode, the conveying unit83cconveys the recording medium W a distance equivalent to the dimension in the sub scanning direction Df of a region printed with one of the first head10A and second head10B during one movement of the carriage3(a distance of a single head worth).

The carriage moving unit83dexecutes a carriage movement process for moving the carriage3in the main scanning direction Ds. The carriage3is moved in the main scanning direction Ds while the ink ejecting unit83aperforms the ejection process described above. As a result, the heads10mounted in the carriage3also move in the main scanning direction Ds during the ejection process.

The control history storing unit84executes a control history storage process for storing the control history for the first head10A and second head10B in the storage device75. The cleaning unit85executes a cleaning process for discharging ink from the nozzles11. Specifically, the cleaning unit85executes a suction process or a flushing process as the cleaning process. In a suction process, the control device71first caps the nozzles11. To cap the nozzles11with the control device71, the carriage3is moved until the heads10are positioned above the cap, and the cap is raised by a cap raising mechanism, for example. Subsequently, a pump provided in a tube connecting the cap to a waste liquid tank depressurizes the interior of the cap, whereby ink is drawn out from the nozzles11into the cap. By discharging ink from the nozzles11in this way, the control device71can eliminate clogging in the nozzles11. In a flushing process, the cleaning unit85moves the carriage3until the heads10are positioned above an ink receptacle, and the heads10are controlled to eject ink toward the ink receptacle. The discharged ink is conveyed from the ink receptacle to the waste liquid tank.

The color calibrating unit86executes a color calibration process for generating a calibration look-up table (LUT). The final print data generating unit87selects a calibration LUT corresponding to the recording medium W to be used for a printing operation. Setting information included in a print job specifies the recording medium W. Next, the final print data generating unit87creates dot data for each pixel of each ink color from gradation values in print image data included in the print job. The dot data is a halftone, for example, having dot position information and dot size information.

The storage device75stores the program of the present embodiment, and a control program for performing various data processing. The storage device75also temporarily stores print jobs received from an external personal computer such as a computer200or the like via the network interface70. The storage device75also temporarily stores print data for each pass of a printing operation. Note that a pass is an operation for moving the carriage3in the main scanning direction Ds and ejecting ink from the heads10during this movement. The storage device75also stores various data used for selecting the active head in the active head selection process.

The head driver IC74receives commands from the control device71and controls the heads10to eject ink. Similarly, the motor driver IC30receives commands from the control device71to control the drive of the conveying motor31while the motor driver IC32receives commands from the control device71to control the drive of the carriage motor33.

The storage medium reading device77is a device that reads a liquid ejection program from a computer-readable storage medium KB. The storage medium KB may be a flexible disk, a CD (CD-ROM, CD-R, CD-RW, etc.), a DVD (DVD-ROM, DVD-RAM, DVD-R, DVD+R, DVD-RW, DVD+RW, etc.), a Blu-ray Disc, a magnetic disk, an optical disc, or a magneto-optical disc, for example. The storage medium reading device77may also be a device for reading the liquid ejection program from a storage medium such as a USB flash memory. The liquid ejection program read by the storage medium reading device77is saved in the storage device75and executed by the control device71. Note that the liquid ejection program of the present embodiment may be received from the computer200via the network interface70or downloaded from the Internet and may subsequently be saved in the storage device75.

Next, steps in a printing process executed by the printing apparatus1of the present embodiment will be described with reference to flowcharts. The following printing process is performed to print images with high color reproducibility. Therefore, the final print in the printing process is performed after color calibration.

In S1ofFIG.5, the control device71first performs a printing process based on image data for patches, that is, a patch image printing process to print patch images based on the image data for patches.FIG.6shows steps in a patch image printing process for performing printing based on image data for patches. In S11ofFIG.6the control device71receives and acquires a target color to be calibrated via the operating keys4, display/input unit5, computer200or the like. In S12the control device71generates image data for patches that include a sample of the acquired target color, and samples of a plurality of colors close to the target color obtained by varying parameters of the target color slightly. The image data also associates a patch number with the sample of each color close to the target color. The patch numbers are used for identifying the sample colors.

In S13the control device71executes an operating mode setting process for setting the operating mode to the second mode. In S14the control device71executes an active head selection process to select one of the first head10A and second head10B as the active head to be used in the second mode. In the active head selection process, the control device71selects the first head10A or second head10B having the most appropriate ejection properties for printing images with the highest color reproducibility. In this process, the control device71executes at least one of the first through fourth selection process, as illustrated inFIG.7. Before continuing with the patch image printing process ofFIG.6, the content of the first through fourth selection processes will be described below.

FIG.8shows steps in the first selection process executed by the control device71in S21ofFIG.7. In S211ofFIG.8, the control device71reads and acquires control history for the heads10from the storage device75. The control history for the heads10is control history of the control device71that has been stored in the storage device75by the control history storing unit84. The control history includes the execution history of cleaning processes, head replacement time information for calculating the length of time that has elapsed after each of the first head10A and second head10B was replaced, and total ink ejection quantity information for calculating the total quantity of ink that has been ejected, for example.

Based on the control history for the first head10A and second head10B, the control device71selects one of the first head10A and second head10B as the active head. When selecting one of the first head10A and second head10B to be the active head, the control device71gives priority to criteria in the following order: the head10for which the cleaning process has been executed the fewest number of times, the head10for which the least amount of time has elapsed since last being replaced, and the head10from which the least total quantity of ink has been ejected.

More specifically, in S212the control device71first determines whether the difference in the number of times the cleaning process has been executed for each head10is greater than or equal to a prescribed threshold. If the difference in execution times for the cleaning process between the first head10A and second head10B is greater than or equal to the prescribed threshold (S212: YES), in S213the control device71selects the head10having the fewest cleaning process execution times to be the active head.

However, if the difference in execution times for the cleaning process is less than the prescribed threshold (S212: NO), in S214the control device71determines whether the difference in the amount of time that has elapsed after each head10was replaced is greater than or equal to a prescribed threshold. If the difference in elapsed times following replacement of the heads10is greater than or equal to the prescribed threshold (S214: YES), in S215the control device71selects the head10having the shortest elapsed time after last being replaced to be the active head.

However, if the difference in the amount of time that has elapsed after each head10was replaced is less than the prescribed threshold (S214: NO), in S216the control device71determines whether the difference in the total quantity of ejected ink from each head10is greater than or equal to a prescribed threshold. If the difference between total quantities of ejected ink is greater than or equal to the prescribed threshold (S216: YES), in S217the control device71selects the head10having the least total quantity of ejected ink to be the active head.

However, if the difference between total quantities of ejected ink is less than the threshold (S216: NO), the control device71ends the first selection process without selecting an active head in the first selection process. While the criteria for selecting the active head are not limited to those described inFIG.8, the active head should be selected based on at least one of execution history for the cleaning process, head replacement time information, and total ink ejection quantity information.

It should be noted that cleaning is primarily executed when a clean command is received from the user due to clogging occurring in the nozzles11. Hence, a head with a lower cleaning frequency is defined as a head having better ejection properties. Further, since ejection properties of ahead degrade through use, ahead having a shorter elapsed time since its last replacement and a head having the least total quantity of ejected ink is defined as the head having better ejection properties. Accordingly, by selecting an active head based on control history that can affect ejection properties, the control device71can select a head with good ejection properties.

FIG.9shows steps in the second selection process executed by the control device71in S23ofFIG.7. In S231ofFIG.9, the control device71reads and acquires ejection property information from the storage device75indicating ink ejection properties for the nozzles11. This ejection property information indicates variation in the diameters of nozzles11, for example. Ink ejection properties of the nozzles11are measured during manufacturing of the printing apparatus1and stored in the storage device75as ejection property information.

Next, the control device71selects one of the first head10A and second head10to be the active head based on the ejection property information. In other words, in S232the control device71determines whether the difference in ejection properties between the first head10A and second head10B is greater than or equal to a prescribed threshold. If the difference in the ejection properties is greater than or equal to the prescribed threshold (S232: YES), in S233selects the head10having better ejection properties to be the active head based on the ejection property information.

Specifically, in S232the control device71determines whether the difference in variation among the diameters of nozzles11between the first head10A and second head10B is greater than or equal to a prescribed threshold. If the difference in variation among the diameters of nozzles11is greater than or equal to the prescribed threshold (S232: YES), in S233the control device71selects the head10among the first head10A and second head10B having the smallest variation in diameters of nozzles11to be the active head, for example. However, if the difference in variation among the diameters of nozzles11between the first head10A and second head10B is less than the prescribed threshold (S232: NO), the control device71ends the second selection process without selecting an active head. As an alternative to the second selection process described above, in S231the control device71may acquire a minimum droplet quantity ejected from the nozzles11as the ejection property information, determine in S232whether this minimum droplet quantity is greater than or equal to a prescribed threshold, and in S232select the head10having the largest minimum droplet quantity ejected from nozzles11to be the active head.

Sometimes the drive waveforms applied to actuators in nozzles11are adjusted in order to eliminate variation in the size of droplets ejected from nozzles11formed in the heads10. However, if there is a large variation in the diameters of nozzles11in a head10or if the minimum droplet quantity is small (the smaller droplet quantity requires a larger discharge voltage for the nozzle, which may result in too large droplets from other nozzles), the adjustment range may be insufficient, and the head10can be defined as not having good ejection properties. Accordingly, by selecting the active head based on ejection property information indicating ink ejection properties of the nozzles11, as described above, the control device71can select a head10having better ejection properties.

FIG.10shows the third selection process that the control device71executes in S25ofFIG.7. In S251ofFIG.10, the control device71reads and acquires head feature quantities for the first head10A and second head10B from the storage device75. Specifically, in S251the control device71reads and acquires from the storage device75a first representative value for a prescribed first feature quantity in the first head10A, a second representative value for a prescribed second feature quantity in the second head10B, a first individual value for the first feature quantity in the first head10A, and a second individual value for the second feature quantity in the second head10B as the head feature quantities for the first head10A and second head10B.

The first feature quantity and second feature quantity may be feature quantities of the same type. In this case, the first representative value and second representative value may be the same value. As a specific example, in the present embodiment, the first feature quantity and second feature quantity are quantities related to the shape of ink channels, and more specifically the diameter of the nozzles11, the width of ink channels supplying ink to the nozzles11, or the length of the ink channels. Individual values for these feature quantities are measured during manufacturing of the printing apparatus1and stored in the storage device75. The representative values of these feature quantities are values derived from statistical data such as the mean, median, mode, or design values. The ink channel includes the supply manifold, return manifold, and the plurality of individual channels connected to the supply manifold and return manifold.

Next, the control device71selects an active head based on the acquired head feature quantities. Specifically, in S252the control device71determines whether at least one of the divergence of the first individual value from the first representative value and the divergence of the second individual value from the second representative value is greater than or equal to a prescribed threshold. If at least one of the divergences for the first head10A and second head10B is greater than or equal to the prescribed threshold (S252: YES), the control device71selects the head10having the smaller divergence between the individual value and the representative value to be the active head. That is, in S253the control device71selects the first head10A as the active head when the first individual value has a smaller divergence from the first representative value than the second individual value has from the second representative value; and conversely selects the second head10B as the active head when the second individual value has a smaller divergence from the second representative value than the first individual value has from the first representative value. Through this process, the control device71can select the head10having better ejection properties closer to the design values and the like. However, if both the divergence of the first individual value from the first representative value and the divergence of the second individual value from the second representative value are less than the prescribed threshold (S252: NO), the control device71ends the third selection process without selecting an active head.

FIG.11shows steps in the fourth selection process that the control device71executes in S27ofFIG.7. In S271ofFIG.11, the control device71reads and acquires priority levels from the storage device75based on the layout of the first head10A and second head10B in the printing apparatus1. The priority levels are information indicating which head10has priority over the other head10. The priority levels may be preset by the manufacturer of the control device71and stored in the storage device75, for example. These priority levels may be set based on the lengths of the ink tubes, for example. Specifically, when the first ink tube52has a shorter length than the second ink tube53, the priority levels may be set such that the first head10A has a higher priory level than the second head10B. Conversely, if the second ink tube53has a shorter length than the first ink tube52, the priority levels may be set such that the second head10B has a higher priority level than the first head10A. As an alternative to this method, the priority levels may be set based on the layout of the heads10in the conveying direction of the recording medium W. Specifically, the priority levels may be set such that the head10among the first head10A and second head10B positioned on the upstream side in the conveying direction of the recording medium W has a higher priority level than the other head10. As another alternative, the priority levels may be set such that the head10positioned farther from the opening2athrough which the recording medium W is discharged has a higher priority level than the other head10. In the present embodiment, the first head10A is set to have a higher priority level than the second head10B.

In S272the control device71selects one of the first head10A and second head10B to be the active head based on the priority levels. Specifically, in S272the control device71selects the head10having a higher priority level to be the active head. Here, the head10connected to the ink tank51by the shorter ink tube can be defined as a head10having good ejection properties since ink can be smoothly supplied to that head10. Similarly, the head10positioned on the upstream side in the conveying direction of the recording medium W can be defined as a head10having good ejection properties since this head has fewer opportunities of being used in printing and, hence, has less fatigue. Similarly, the head10positioned farthest from the opening2athrough which the recording medium W is discharged can be defined as the head10with better ejection properties since this head10has fewer opportunities for contacting the recording medium W. Hence, by selecting an active head according to priority levels based on the layout of the first head10A and second head10B in the printing apparatus1, more specifically, by selecting a head10having a higher priority level to be an active head, the control device71can select the head10having better ejection properties.

FIG.7shows the active head selection process according to the present embodiment. In this process, the control device71uses in order of precedence the first selection process, the second selection process, the third selection process, and the fourth selection process to select an active head. That is, in this active head selection process the control device71gives priority to the first selection process over the second selection process for selecting the active head, gives priority to the first selection process over the third selection process for selecting the active head, and gives priority to the first selection process over the fourth selection process for selecting the active head. Also in the active head selection process, the control device71gives priority to the second selection process over the third selection process and fourth selection process for selecting the active head and gives priority to the third selection process over the fourth selection process for selecting the active head.

Thus, in S21ofFIG.7the control device71first executes the first selection process for selecting a head10as the active head based on control history. If a head10has been selected as the active head in the first selection process (S22: YES), the control device71ends the active head selection process. However, if a head10was not selected as the active head in the first selection process (S22: NO), in S23the control device71executes the second selection process to select a head10as the active head based on ejection property information. If a head10has been selected as the active head in the second selection process (S24: YES), the control device71ends the active head selection process. However, if a head10has not been selected as the active head in the second selection process (S24: NO), in S25the control device71executes the third selection process to select a head10as the active head based on head feature quantities. If a head10has been selected as the active head in the third selection process (S26: YES), the control device71ends the active head selection process. However, if a head10has not been selected as the active head in the third selection process (S26: NO), in S27the control device71executes the fourth selection process to select a head10as the active head based on priority levels.

In this way, the control device71uses the first selection process, second selection process, third selection process, and fourth selection process in this order of priority to select an active head, thereby selecting a suitable head10for executing image printing with higher color reproducibility. Note that the control device71may select an active head using only one of the first selection process, second selection process, third selection process, and fourth selection process. Alternatively, the control device71may select an active head using any plurality of processes from among the first selection process, second selection process, third selection process, and fourth selection process. Here, if the first selection process is used with priority over the second selection process, third selection process, and fourth selection process to select the active head, the control device71can select a suitable head10for executing image printing with higher color reproducibility. Similarly, if the second selection process is used with priority over the third selection process and fourth selection process to select the active head, the control device71can select a suitable head10for executing image printing with higher color reproducibility. Further, if the third selection process is used with priority over the fourth selection process to select the active head, the control device71can select a suitable head10for executing image printing with higher color reproducibility.

After completing the active head selection process described above in S14ofFIG.6, in S15the control device71executes a printing process for printing patch images based on image data for patches. Since the operating mode has been set to the second mode, as described above, the control device71executes a printing process by ejecting ink from the active head while not ejecting ink from heads10other than the active head. Subsequently, the control device71ends the patch image printing process.

Next, in S2ofFIG.5the control device71executes a color calibration process.FIG.12shows steps in the color calibration process. In S31ofFIG.12, the control device71acquires color replacement content information indicating color replacement content. Prior to the control device71acquiring this color replacement content information, the user checks the printed matter on which the patch images based on the image data for patches have been printed, and determines whether the target color should be calibrated. When determining that the target color should be calibrated, the user selects one of the calibrated colors from among the plurality of sample colors close to the target color and inputs the patch number corresponding to this sample color into the printing apparatus1via the operating keys4, display/input unit5, computer200or the like. Accordingly, the control device71acquires the color replacement content information indicating this color replacement content in S31.

In S32the control device71generates a calibration LUT based on the color replacement content indicated by the acquired color replacement content information. A calibration LUT is data associating input RGB values with output RGB values, for example. In this example, RGB values corresponding to the calibrated color are stored as output RGB values corresponding to the color being calibrated. For colors not being calibrated, the user either does not input values as corresponding output RGB values or the same values as the input RGB values are stored as the output RGB values. The control device71sets the input RGB values to the RGB values for the target color being calibrated. Next, the control device71identifies RGB values for the selected calibrated color based on the patch number and sets these values as the output RGB values for the target color being calibrated. The control device71also calculates output RGB values through interpolation for colors close to the target color being calibrated and associates these calculated values with input RGB values for these colors. Next, the control device71stores the generated calibration LUT in the storage device75and subsequently ends the color calibration process.

Note that both input and output associated in the calibration LUT need not be limited to RGB values. The input and output associated in the calibration LUT may associate any numerical expressions such as RGB values, CMYK values, LCh values, Lab values, or the like. In the present embodiment, the input and output associated in the calibration LUT are RGB values and CMYK values, respectively. In this case, after calculating output RGB values as described above, the control device71converts these output RGB values into CMYK values, and associates the converted CMYK values with the input RGB values to generate calibration LUT. The calibration LUT may store data indicating whether a color corresponding to each input RGB value is a designated replacement color. Next, the control device71stores the generated calibration LUT in the storage device75and subsequently ends the color calibration process. Note that the designated replacement color is a color designated by the user via the operating keys4, display/input unit5, computer200, or the like.

In S3ofFIG.5, the control device71executes a final print data generation process.FIG.13shows steps in the final print data generation process. In S41ofFIG.13, the control device71first receives a print job from the computer200and stores in the storage device75. The print job includes image data representing an image to be printed and setting information specifying the recording medium W to be used for printing. In S42the control device71selects and acquires the calibration LUT generated in the color calibration process according to the setting information included in the print job.

In S43the control device71acquires print image segment data for one head.FIG.15shows a sample print image G that has been divided into image segments. The control device71divides the print image G into image segments along the sub scanning direction Df. Each image segment has a dimension in the sub scanning direction Df equivalent to the region that a single head10prints in one movement of the carriage3(the dimension of a single head). These image segments will be referred to as printing regions An(where n=1, 2, . . . ). In S43the control device71acquires print image segment data for one printing region An(a single head worth) from among unprocessed printing regions Anin order beginning from the top of the image and proceeding in the printing order.

In S44the control device71references the calibration LUT to determine whether the acquired print image segment data includes a designated replacement color. If a designated replacement color is included in the segment data (S44: YES), in S45the control device71sets the printing region Anfor this print image segment data as a replacement target region. In S46the control device71performs a color conversion process on the image data included in the print job while referencing the calibration LUT. The control device71converts RGB values for each pixel in the printing region Aninto corresponding CMYK values using the calibration LUT. However, if the control device71determines in S44that the print image segment data does not include a designated replacement color (S44: NO), the control device71skips S45and simply performs the color conversion process in S46. In other words, when determining that the print image segment data for the printing region Andoes not include a designated replacement color (S44: NO), the control device71converts RGB values for each pixel in the printing region Aninto corresponding CMYK values using the calibration LUT (S45) without setting this printing region Anas a replacement target region.

In S47the control device71determines whether color conversion has been completed for all print image segment data, i.e., for all image segments configuring the print image G. While color conversion has not been completed (S47: NO), the control device71returns to S43to acquire print image segment data for the next printing region An+1and repeats the process in S44through S46on this data. When color conversion has been completed for all print image segment data (S47: YES), in S48the control device71generates print data based on the results of the color conversion and stores the generated print data as final print data in the storage device75. Subsequently, the control device71ends the final print data generation process.

Next, in S4ofFIG.5the control device71executes a final print image printing process for printing the final print image.FIG.14shows steps in the final print image printing process. In S51ofFIG.14, the control device71first acquires the final print data stored in the storage device75.

In S52the control device71determines whether either one of the printing regions Anand An+1(seeFIG.15) for two heads worth of data, beginning from the top of the unprinted data in the sub scanning direction Df and progressing in the printing order, is set as a replacement target region. If neither of the printing regions Anand An+1is set as a replacement target region (S52: NO), in S54the control device71executes the operating mode setting process to set the operating mode to the first mode. In S55the control device71executes an ejection process and a carriage movement process in order to perform printing on the printing regions Anand An+1corresponding to the data read for two heads worth. As described above, the control device71executes a print by ejecting ink from both the first head10A and second head10B when the operating mode is set to the first mode. Hence, by moving the carriage3once in the main scanning direction Ds, the printing apparatus1prints an image equivalent to two heads in the printing regions Anand An+1. In S56the control device71executes a conveying process to convey the recording medium W downstream in the sub scanning direction Df a distance equivalent to two heads worth of printing just completed.

However, if the control device71determines in S52that at least one of the printing regions Anand An+1in the two heads worth of data is set as a replacement target region (S52: YES), in S57the control device71executes the operating mode setting process to set the operating mode to the second mode. In S58the control device71executes an ejection process and a carriage movement process to print the single printing region An, which is the first printing region of the printing regions Anand An+1relative to the printing order, using the active head. Note that when the print image is being printed with the second head10B, in S59the control device71executes a conveying process to convey the recording medium W so that the printing region Anis opposing the second head10B. As described above, the control device71executes a print by ejecting ink from the active head and not from heads10other than the active head while the operating mode is set to the second mode. Hence, by moving the carriage3once in the main scanning direction Ds, the control device71prints an image equivalent to a single head in the printing region An. Next, the control device71executes a conveying process to convey the recording medium W downstream in the sub scanning direction Df a distance equivalent to the single head worth of printing just completed.

In S60the control device71determines whether printing has been completed for the entire final print image. While printing is not complete (S60: NO), the control device71repeats the process described above from S52. Once printing is complete for the entire final print image (S60: YES), the control device71ends the final print image printing process. Through the process described above, regions set as replacement target regions are printed using the active head, while regions not set as replacement target regions are printed using both two heads10. Accordingly, this method can suppress a reduction in throughput while preventing a drop in color reproducibility owing to individual differences in color reproducibility among heads10.

As described above, the printing apparatus1according to the present embodiment is provided with the first head10A having nozzles11that eject ink, the second head10B having nozzles11that eject ink in the same colors as the first head10A, a carriage3that supports the first head10A and second head10B and is capable of reciprocating, the storage device75, and the control device71. The control device71executes an operating mode setting process for setting the operating mode to one of a plurality of modes that include a first mode, and a second mode for performing image printing with higher color reproducibility than that in the first mode; an active head selection process for selecting one of the first head10A and second head10B to be the active head used during the second mode; and a printing process for executing a print by ejecting ink from the first head10A and second head10B when the operating mode is set to the first mode and for executing a print by ejecting ink from the active head but not ejecting ink from heads10other than the active head when the operating mode is set to the second mode. In this way, the control device71can prevent a drop in color reproducibility owing to individual differences in color reproducibility among heads10.

Variations of the Embodiment

While the description has been made in detail with reference to specific embodiments, it would be apparent to those skilled in the art that many modifications and variations may be made thereto.

In the final print image printing process according to the present embodiment described above, the control device71switches the operating mode according to the existence of replacement target regions, but the present disclosure is not limited to this configuration. As an alternative, the user may set the operating mode in print settings, and the control device71may switch the operating mode based on this setting.

In the present embodiment described above, the downstream ends of the nozzle rows in the first head10A overlap the upstream ends of nozzle rows in the second head10B in the sub scanning direction Df, but the present disclosure is not limited to this configuration. As an alternative, the downstream ends of nozzle rows in the first head10A may be arranged to be continuous with the upstream ends of nozzle rows in the second head10B with no overlapping portions in the sub scanning direction Df or may be spaced apart from the upstream ends of nozzle rows in the second head10B.

The printing apparatus1of the present embodiment described above conveys the recording medium W by moving the stage6that supports the recording medium W, but the present disclosure is not limited to this method. As an alternative, the printing apparatus1may convey the recording medium W with conveying rollers.

In the active head selection process of the present embodiment described above, the control device71executes selection processes in order of the first selection process, second selection process, third selection process, and fourth selection process without continuing onto downstream processes once a selection has been made, thereby selecting an active head while giving priority in order of the first selection process, second selection process, third selection process, and fourth selection process. However, the present disclosure is not limited to this method. As an alternative, the control device71may execute the first, second, third, and fourth selection processes concurrently or in succession; weight the results of the selection processes with decreasing weights in order of the first selection process, second selection process, third selection process, and fourth selection process; and select an active head based on these weighted results. As an example, the control device71gives twice the amount of weight to the active head selected in the first selection process than the active head selected in the second selection process. As another example, the control device71gives twice the amount of weight to the active head selected in the first selection process than the active head selected in the third selection process. As another example, the control device71gives twice the amount of weight to the active head selected in the first selection process than the active head selected in the fourth selection process. As another example, the control device71gives twice the amount of weight to the active head selected in the second selection process than the active head selected in the third selection process. As another example, the control device71gives twice the amount of weight to the active head selected in the second selection process than the active head selected in the fourth selection process. As another example, the control device71gives twice the amount of weight to the active head selected in the third selection process than the active head selected in the fourth selection process.

The printing apparatus1may also be configured to eject UV-curable ink from the heads10. In this case, the printing apparatus1may be provided with an ultraviolet irradiation device that irradiates ultraviolet light toward ink droplets that have impacted the recording medium W.

Numerous modifications and other embodiments of the present disclosure would be apparent to those skilled in the art from the foregoing description. Therefore, the foregoing description should be interpreted only as an example and is provided for the purpose of instructing those skilled in the art of the best mode for carrying out the present disclosure. The structural and/or functional details may be substantially altered without departing from the spirit of the present disclosure.