Image forming apparatus, control method, and program

Abstract

This suppresses unnecessary ink consumption during the head recovery operation. [Solution] A recording head has multiple rows of ejection ports that eject ink supplied from multiple ink tanks. The system detects which ink tank has been replaced from among the multiple ink tanks. As a recovery operation for the recording head after replacement, it performs a suction operation to draw ink from the rows of ejection ports and an ejection operation to eject ink from the recording head. The content of the first ejection operation performed as a recovery operation for the first ink tank that has been replaced is made different from the content of the second ejection operation performed as a recovery operation for the first ink tank when the first ink tank has not been replaced.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, a control method, and a program.

Background Art

[0002] Conventionally, inkjet recording technology has been widely researched and developed because of advantages such as the ability to manufacture printers at a relatively low cost. Image forming apparatuses are widely and commonly used as consumer devices such as printers or multifunction peripherals.

[0003] In an image forming apparatus, in order to maintain the ejection of a recording head in a stable state, maintenance processing for the recording head is appropriately performed. The maintenance processing mainly includes a suction operation for removing bubbles and impurities inside the head by forcibly sucking ink from the ejection port of the recording head, a wiping operation for wiping droplets on the surface of the ejection port, and further a suction operation when replacing an ink tank and a preliminary ejection operation for adjusting the ejection operation prior to actual printing.

[0004] By the way, when sucking ink from the head in maintenance processing, it is common to use a cap capable of performing a suction operation. Further, in order to discharge the ink accumulated in the cap after the suction operation is performed, and further to perform the suction operation only on a specific cap among a plurality of caps, an air communication valve connected by a cap and a tube and capable of opening and closing selection is generally provided.

[0005] Since the ink tank is stationary in the same posture for a long time, components with different specific gravities in the ink, particularly solid components such as pigments, may settle. Therefore, density irregularities may occur in response to the switching from the old ink tank to the new ink tank immediately after the ink tank replacement. Also, when replacing the tank, bubbles may enter the flow path. Therefore, for the replaced ink color, a suction operation and an empty ejection from the ejection port row are performed as recovery operations to avoid this. In the references, measures such as changing the conditions of the suction recovery operation after the ink tank replacement are taken.

Prior Art Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2005-306013 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in a configuration where multiple colors are restored using the same suction cap, even if some ink tanks are replaced, the restoration process is performed on all ink tanks according to the restoration conditions of the ink tank with the highest suction volume. As a result, ink tanks that only require a small amount of restoration, or those that haven't been replaced, may end up consuming more ink than necessary.

[0008] The present invention aims to suppress unnecessary ink consumption during the recovery operation of the recording head. [Means for solving the problem]

[0009] To achieve the object of the present invention, for example, an image forming apparatus according to one embodiment has the following configuration: a recording head having a plurality of rows of discharge ports for discharging ink supplied from a plurality of ink tanks; detection means for detecting which of the plurality of ink tanks has been replaced; and operation control means for performing a suction operation to suck ink from the rows of discharge ports and an discharge operation to discharge ink from the recording head as a recovery operation of the recording head after the replacement, wherein the operation control means makes the content of the first discharge operation performed as a recovery operation in the first ink tank that has been replaced among the plurality of ink tanks different from the content of the second discharge operation performed as a recovery operation in the first ink tank when the first ink tank has not been replaced. [Effects of the Invention]

[0010] This suppresses unnecessary ink consumption during the head recovery operation. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram showing an example of the configuration of an image forming apparatus. [Figure 2] A diagram showing an example of the configuration of a recovery device included in an image forming apparatus. [Figure 3] A diagram showing an example of the hardware configuration of an image forming apparatus. [Figure 4] A flowchart illustrating a typical recovery operation using a recovery device. [Figure 5] A diagram illustrating the recording head and recovery device according to this embodiment. [Figure 6] A flowchart illustrating an example of the process when replacing the ink tank according to this embodiment. [Figure 7] A flowchart showing an example of recovery operation by the image forming apparatus according to this embodiment. [Figure 8] A diagram showing an example of the recovery procedure corresponding to the type of replacement ink tank. [Figure 9] A diagram illustrating the recovery mode in conventional cases. [Figure 10] A diagram illustrating an example of the recovery process in an application example. [Figure 11] A diagram illustrating the conversion between preliminary discharge volume and suction time in application examples. [Modes for carrying out the invention]

[0012] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0013] [Embodiment 1] First, an example of the configuration of the image forming apparatus (inkjet recording apparatus) according to this embodiment will be described with reference to Figures 1 to 4. Figure 1(a) is a perspective view showing an example of the internal configuration of the image forming apparatus according to this embodiment. In the image forming apparatus shown in Figure 1(a), the carriage 101, on which the recording head is mounted, moves back and forth in the X direction of the figure, guided and supported by the guide shaft 104, as the timing belt 103 driven by the carriage (CR) motor 102 moves. The flexible cable 105 electrically connects the substrate of the image forming apparatus body and the recording head while following the movement of the carriage 101. The transport roller pair 106 grips the printing medium 107 and rotates to transport the printing medium 107 in a predetermined direction (Y direction) intersecting the X direction. An image is formed on the printing medium in stages by alternately repeating the main scan, in which the carriage 101 moves in the X direction while the recording head ejects ink supplied from the ink tank according to the print data, and the transport operation accompanying the rotation of the transport roller pair 106.

[0014] Furthermore, a recovery device 108 is provided at one end of the carriage 101's range of motion for performing ejection recovery processing to maintain good ejection function of the recording head. The carriage 101 is also detachably mounted with a recording head and an ink tank (not shown). In this embodiment, a tank holder to which an ink tank is attached is mounted on a holder to which the recording head is integrally attached, and these are mounted together on the carriage 101.

[0015] The ink remaining amount in the ink tank is detected by the value of a so-called dot counter. The dot counter is a counter that counts the amount of ink discharged from the discharge port array. The dot counter can be realized by a control unit described later. The ink discharged from the discharge port array includes the ink discharged from the discharge port array and the ink discharged by suction. The dot counter counts the value obtained by multiplying the number of discharged ink droplets by the volume per droplet and the suction discharge amount (hereinafter referred to as the suction amount). By providing a memory for storing the ink remaining amount in the ink tank (for example, in the ink tank itself) and storing the dot count value, it becomes easy to manage the ink remaining amount in the ink tank. Also, by the control unit described later accessing this memory, it becomes possible to detect whether an ink tank is attached to the image forming apparatus.

[0016] The dot count value managed by the dot counter indicates the value of the consumed ink, and the larger the value, the more ink is in a consumed state. For example, when the image forming apparatus notifies the user of the ink remaining amount in the ink tank, it can notify based on the value obtained by subtracting the dot count value from the total capacity of the ink tank using the dot count value stored in the ink tank.

[0017] FIG. 1(b) is a schematic diagram showing an example of the structure on the image forming element side of the recording head 109 according to the present embodiment. The recording head 109 includes an image forming element row in which 1280 image forming elements (hereinafter also referred to as ejection ports) are arranged in the Y direction at a density of 1200 per inch for each ink color. In the example of FIG. 1(b), an ejection port row 110GY for discharging gray ink, an ejection port row 110PBK for discharging photo black ink, an ejection port row 110C for discharging cyan ink, an ejection port row 110R for discharging red ink, an ejection port row 110M for discharging magenta ink, an ejection port row 110PM for discharging photo magenta ink, an ejection port row 110PC for discharging photo cyan ink, an ejection port row 110Y for discharging yellow ink, an ejection port row 110CO for discharging processing liquid ink, and an ejection port row 110MBK for discharging matte black ink are arranged in the X direction of the recording head 109. Here, the ejection port row is formed by two rows of ejection ports arranged at a density of 600 per inch with the ejection ports shifted by 1 / 1200 inch and arranged in a staggered pattern. By regarding these two rows of ejection ports (hereinafter, Even row and Odd row) as one ejection port row, 1200 dots per inch can be formed on the print medium. The recording head 109 according to the present embodiment is a recording head that discharges ink using thermal energy, and includes an electrothermal converter (not shown) for generating thermal energy inside the ejection port. Note that the method of discharging ink is not limited to the method using thermal energy, and other methods such as a method of discharging ink by a piezoelectric element may be adopted.

[0018] The image forming apparatus according to the present embodiment can form dots at a printing density of 2400 dpi (dot / inch) in the X direction and 1200 dpi in the Y direction by discharging ink while scanning the recording head 109 in the X direction. The amount (discharge amount) of ink droplets discharged from each ejection port is about 4.5 pl. The recording head 109 that discharges ink may be configured independently for each color or may be configured integrally. Also, the types of ink used here are not limited to the inks of the above colors.

[0019] Figure 2(a) is a schematic diagram showing an example of a detailed configuration of the recovery device 108 of the inkjet printer shown in Figure 1. In Figure 2(a), the bearing portion 201 is the bearing portion of the carriage 101 for engaging with the guide shaft 104. The recording head 109 is held in the carriage 101 while connected to the ink tank 213. The cap 202 is a cap that can cover the discharge port surface of the recording head 109 and is movable in the Z direction. The cap 202 is configured to rise by an upward and downward mechanism (not shown) when the carriage 101 is in the home position (on the recovery device) to make close contact with the discharge port surface, and to detach from the discharge port surface when it descends. The suction tube 203 is a tube that communicates with the cap, and the atmospheric communication tube 204 is a tube that communicates with the cap. The atmospheric communication valve mechanism 205 is a valve mechanism and is connected to the atmospheric communication tube 204. This atmospheric communication valve mechanism 205 can be opened and closed by a cam mechanism (not shown). The atmospheric communication tube 204 is generally made of a flexible material such as rubber or resin, and in this embodiment, a rubber atmospheric communication tube 204 is used.

[0020] Pump 206 is a suction pump and forms a tube pump. Pump base 207 is a pump base with a semicircular tube guide surface (not shown) formed on the inside. The roller holder 208 generates negative pressure inside the cap 202 by having two rollers 209 move while squeezing the suction tube 203 in accordance with rotation around the rotation axis 210.

[0021] The blade 211 is held in the blade holder 212. When the cap 202 is in a waiting position in the downward position, the blade holder 212 slides in the +Y direction, causing the blade 211 to contact the discharge port surface and wipe away any remaining ink droplets, paper dust, or other debris from the discharge port surface.

[0022] The cap 202 has a suction port (hereinafter referred to as the suction port) 214 connected to the suction tube 203. The cap 202 also has an atmospheric communication port (hereinafter referred to as the atmospheric communication port) 215 connected to the atmospheric communication tube 204. The inside of the cap 202 is equipped with a porous absorbent material (not shown). The ink that is sucked and discharged by the drive of the suction pump 206 is contained in the waste ink absorbent material (not shown). In this embodiment, a tube pump is used as the suction pump 206, but other types of suction pumps may be used. Figure 2(a) shows an example in which the cap 202 is in a position detached from the discharge port surface as described above.

[0023] The cap 202 for performing the suction operation is configured to perform suction for multiple ink colors simultaneously. In this embodiment, as shown in Figure 2(b), caps 202a and 202b are individually provided for each of the tips 110a and 110b. Similarly, blades 211a and 211b are individually provided for each of the tips 110a and 110b.

[0024] Here, the recovery operation (details to be described later) is configured to recover the five colored ejection port rows 110 of a single chip all at once using a single cap and a single blade, but this is just one example and is not particularly limited to this configuration.

[0025] (Example of an image processing system configuration) Next, the image processing system that performs print control of the image forming apparatus according to this embodiment will be described. Figure 3 is a block diagram showing an example of the hardware configuration of the control system of the image forming apparatus shown in Figure 1.

[0026] First, multi-level image data stored in an image input device 301 such as a scanner or digital camera, or in various storage media such as a hard disk, is input to the image input unit 302. The image input unit 302 is an external host computer connected to the image forming apparatus, and it transfers image information for printing to the image output unit 304, which is the image forming apparatus, via the interface circuit 303. The image input unit 302 is equipped with a CPU 305 and a memory element (ROM 306) necessary for transferring image data. The host computer can take the form of a computer as an information processing device, or it can take the form of an image reader or the like.

[0027] The print control unit 307 includes a CPU 308 and input / output ports 309, and controls the printing operation of the image forming apparatus. The print control unit 307 also includes a memory element (ROM 310) for storing control programs, a RAM 311 which serves as a work area for performing various image processing, and a non-volatile memory (NVRAM 312). The ROM 310 stores the control program for the CPU 308 and various data such as parameters necessary for printing operations. The RAM 311 is used as the work area for the CPU 308 and also temporarily stores various data such as image data received from the image input unit 302 and generated print data. The image forming apparatus forms an image by applying ink to the printing medium from each ejection port of the recording head 109 based on the image data converted by the print control unit 307.

[0028] The print control unit 307 also connects to various motors 318 for operating the carriage 101 and the transport roller pair 106, the suction motor 319, and the respective drive circuits 313, 314, and 315 of the recording head 109 via input / output ports 309. The suction motor 319 is the drive source for operating the suction pump 206, which is used to suck and discharge ink from the recording head 109 as described in Figure 2(a).

[0029] Furthermore, the print control unit 307 can be connected to a set of sensors and their drive circuits, such as a temperature and humidity sensor 321 and its drive circuit 317, which detect the temperature and humidity of the surrounding environment, via the input / output port 309.

[0030] The controller 316 is a controller for controlling the display unit and operation unit 320 of the image forming apparatus according to this embodiment. The controller 316 can accept user input via, for example, a mouse and keyboard, or a touch panel. The controller 316 can also display various information to the user via a display device such as a liquid crystal display.

[0031] The following describes a typical suction recovery operation sequence (suction recovery sequence) by the recovery device when replacing an ink tank, using the configuration of the image forming apparatus according to this embodiment. When executing the suction recovery sequence, first, the inkjet recording head 109 is moved to a position facing the cap 202. Next, the cap 202 is moved to a capping position in contact with the discharge port surface by a means for attaching and detaching the cap 202 to and from the discharge port surface. In the capped state, the cap 202 is pressed against the discharge port surface by a pressing means (not shown) including a spring or the like, configured so that the contact pressure against the discharge port surface is a predetermined value.

[0032] Figure 4 is a flowchart illustrating the operation of the recovery device 108 during suction recovery after the cap 202 has been moved to the capping position described above. First, in S401, the print control unit 307 closes the atmospheric communication valve 205 of the cap. Next, in S402, the print control unit 307 closes the roller 209. In S403, the print control unit 307 selects the recovery conditions necessary for the recovery of the replaced ink tank and starts the suction operation by the suction pump 206, causing ink to be sucked out from the discharge port row of the recording head 109.

[0033] In S404, the printing control unit 307 stops the suction operation of the suction pump 206 when a predetermined amount of ink has been discharged from the ink tank. Next, in S405, the printing control unit 307 opens the atmospheric communication valve 205 to connect the space inside the cap to the atmosphere. Once the space inside the cap is connected to the atmosphere, the negative pressure inside the cap is released, and the suction operation from the discharge port row 110 is completed.

[0034] Incidentally, as mentioned above, the image forming apparatus according to this embodiment has a configuration in which multiple colors are drawn into a single cap. If multiple colors are drawn into the same cap as usual, the inks of the multiple colors will mix together inside the cap, forming a mixed ink that fills the cap and may enter the discharge port. Furthermore, between the time the cap member is separated after the drawing operation and the time the wiping is performed, the mixed ink that has adhered to the discharge port surface of the recording head may enter the discharge port. Also, since the inside of the ink tank is always set to be under negative pressure relative to the discharge port, the mixed ink that has entered the discharge port may further diffuse and flow back into the inside of the head and into the ink tank.

[0035] If image formation is performed while mixed inks have entered the device, a so-called color mixing phenomenon will occur, where one color mixes with other colors in the same cap to form the image. Therefore, it is common practice to prevent color mixing by performing an ink ejection unrelated to recording in order to eject the mixed inks from the ejection port row after a series of suction operations and before starting the recording operation.

[0036] As mentioned above, when the suction operation stops, other colors from the same cap may have entered the discharge port. Therefore, in S406, the print control unit 307 promptly performs a preliminary discharge to eliminate color mixing. In this embodiment, preliminary discharge refers to the discharge of ink droplets from the recording head that are not intended for image formation. Since the ink that has entered the discharge port diffuses inside over time, performing preliminary discharge promptly after the suction stops reduces the number of preliminary discharges required to eliminate color mixing. On the other hand, when the atmospheric communication valve is opened, the cap is filled with ink, so an operation to discharge the ink is also necessary. Therefore, in S407, the print control unit 307 performs an empty suction. After that, in S408, the print control unit 307 opens the cap 202. By performing the preliminary discharge operation to eliminate color mixing in S406 and the empty suction operation in S407 simultaneously, when the cap 202 is opened in S408, the mixed ink that has entered the discharge port has been discharged.

[0037] For example, even if the empty suction in S407 is not performed and the operation to open the cap 202 in S408 is performed first, the color mixing elimination preliminary ejection operation in S406 will still be effective. However, in this case, there is a concern that the mixed ink inside the cap 202 may drip into the machine. Therefore, in this embodiment, S406 and S407 are performed before opening the cap 202.

[0038] In S409, the print control unit 307 wipes the discharge port surface with the wiper 211 to remove any adhering ink. Furthermore, in S410, the print control unit 307 performs a pre-discharge after wiping to remove the mixed ink that was pushed into the discharge port row by the wiper 211 during wiping, thereby ending the suction recovery sequence. Here, the print control unit 307 is assumed to perform the roller release operation in S411 (immediately after S410), but the roller release can be performed at any time after S407. Suction recovery will be completed even if the roller release operation is not performed, but there is a concern that the pump tube may be crushed if it is left compressed, so it is common to release the roller 209 at the end of the recovery sequence.

[0039] When performing dry suction, the amount of ink ejected by pre-discharge and the ink discharge speed are set so that the discharge speed of the ink ejected into the cap 202 is sufficiently faster than the rate at which the ink ejected into the cap 202 fills the cap 202. Since the upper limit of the discharge speed depends on the performance of the pump drive system and is therefore limited, reducing the amount of ink ejected results in fewer constraints on the configuration of the image forming apparatus.

[0040] Note that the order in which S406, which performs the pre-discharge operation to eliminate color mixing, and S407, which performs the empty suction operation, are performed in Figure 4 is not particularly limited and may be performed simultaneously, for example. Considering that the ink in the cap is discharged before the pre-discharge operation, S407 may be executed before S406, which is a more common procedure.

[0041] Thus, in the typical suction recovery process that uses the same suction cap to restore multiple colors, even if some ink tanks are replaced, the recovery process is performed on all ink tanks according to the recovery conditions of the ink tank with the highest suction volume. As a result, ink tanks that only require a small amount of recovery, or those that haven't been replaced, may end up consuming more ink than necessary.

[0042] From this perspective, the image forming apparatus according to this embodiment detects an ink tank that has been replaced and makes the content of the discharge operation performed as a recovery operation in the replaced ink tank different from the content of the discharge operation performed in the ink tank that has not been replaced. The configuration and processing of the image forming apparatus according to this embodiment will be described below with reference to Figures 5 to 9.

[0043] Figure 5 shows an example of the configuration of the recording head and the unit that performs the recovery operation in this configuration. In the example in Figure 5, caps 202a and 202b are arranged to correspond to each chip so that all 10 ink tanks can be recovered using a total of 2 chips, with 5 colors per chip. Here, caps 202a and 202b are equipped with ink tubes 203a and 203b, and pumps 206a and 206b, respectively.

[0044] The ink channel 120 within the print head is an ink channel within the print head that transports ink from the ink tank 110 to the print head ejection port row. In the example shown in Figure 5, the lengths of the ink channels for each color are in the following relationships: 120R < 120PBK = 120C < 120GY = 120M, and 120Y < 120PC = 120CO < 120PM = 120MBK. When the ink tank 110M is replaced, if the ink in the ink channel 120M is discharged to eliminate the difference in ink density between the old and new ink tanks caused by the replacement, the ink in the ink channels of other colors whose ink tanks have not been replaced will also be discharged, resulting in wasted ink.

[0045] Figure 6 is a flowchart showing an example of the process when an ink tank is replaced by an image forming apparatus according to this embodiment. At S601, the print control unit 307 receives an instruction from the user to replace the ink tank. This instruction is obtained, for example, via the controller 316.

[0046] In S602, the print control unit 307 moves the carriage unit to the ink tank replacement position. In S603, the print control unit 307 determines whether the termination conditions have been met after moving to the ink tank replacement position. These termination conditions can be arbitrarily set depending on the conditions and environment, such as the elapsed time (arbitrarily set) from the start of carriage movement, the receipt of a termination instruction from the user, or the detection of the completion of carriage movement by a sensor. Here, the termination conditions are assumed to be the elapsed time from the start of carriage movement or the receipt of a termination instruction from the user. In S604, the print control unit 307 determines that the carriage has moved to the standby position.

[0047] Next, in S605, the print control unit 307 determines whether or not the ink tank has been replaced. If it is determined that the ink tank has been replaced, the process proceeds to S606; if it is determined that the ink tank has not been replaced, the process in Figure 6 ends. In S606, the print control unit 307 turns on the replacement flag for the replaced ink tank color, and the process in Figure 6 ends.

[0048] The control process for the recording head recovery operation (hereinafter sometimes referred to as cleaning operation) performed by the image forming apparatus according to this embodiment will be described below with reference to Figure 7. The process shown in Figure 7 is started, for example, when the user inputs an instruction to start printing or to perform a recovery operation, or when a long period of inactivity (elapsed time) is detected.

[0049] In S701, the print control unit 307 determines whether the cleaning flag for performing cleaning is ON. Here, we will assume that the cleaning flag is ON if at least one ink tank replacement flag is ON. If the cleaning flag is ON, the process proceeds to S702; otherwise, the process shown in Figure 7 ends.

[0050] In S702, the print control unit 307 checks which type of ink tank replacement flag is ON (the type of ink tank that has been replaced) and controls the content of the recovery operation to be performed based on the confirmed information. Here, the print control unit 307 can control (select) the content of the recovery operation by referring to a table that stores information indicating the content of the recovery operation corresponding to the type of ink tank that has been replaced, for example, as shown in Figure 8. For example, in Figure 8, recovery modes B, C, and D are shown as recovery operations to be performed when the ink tank of color R, PBK, or C, or GY or M, among the ink tanks for cap 202a has been replaced. Recovery mode E is applied when all ink tanks of all colors corresponding to cap 202a have been replaced. Recovery mode A for cap 202a in Figure 8 is the recovery operation selected when the ink tank has not been replaced, or when the ink tank has been removed but the same ink tank has been reinstalled. Thus, if the print control unit 307 detects that an ink tank has been replaced, but the replacement ink tank is one that has already been used, it can control the recovery operation so as not to perform the replacement pre-discharge operation described later for that ink tank.

[0051] In the following explanation, we will assume that the GY ink tank has been replaced. When the GY ink tank has been replaced, the print control unit 307 selects recovery mode D according to the table in Figure 8 as the content of the recovery operation to be performed. Since the GY ink has the longest ink path, the most ink is discharged in recovery mode D.

[0052] In Figure 8, the item "Pre-ejection to prevent color mixing" indicates the amount of pre-ejection performed in all ink tanks to eliminate color mixing caused by the drawn-in ink and enable proper printing. "Pre-ejection of all colors" indicates the amount of pre-ejection performed in all ink tanks to prepare the ejection port for printing after wiping. On the other hand, "Pre-ejection for ink tank replacement" indicates the amount of pre-ejection performed only in ink tanks that have been replaced (i.e., set separately from the aforementioned pre-ejection to prevent color mixing and pre-ejection for all colors). Hereafter, pre-ejection performed only in such replaced ink tanks may be referred to as "replaced pre-ejection."

[0053] In the table in Figure 8, when an ink tank has been replaced, a pre-discharge of replaced ink is performed, and when an ink tank has not been replaced, control is performed so that the pre-discharge of replaced ink is not performed. In this way, the print control unit 307 can control the amount of ink discharged from the recording head during the recovery operation when an ink tank has been replaced so that it is greater than the amount of ink discharged from the recording head during the recovery operation when an ink tank has not been replaced.

[0054] In Figure 8, the table is set so that the recovery mode is selected according to the length of the ink flow path. However, the control is not limited to this method, as long as the content of the discharge operation performed as a recovery operation in an ink tank that has been replaced differs from the content of the discharge operation performed in the same ink tank that has not been replaced. For example, the content of the recovery operation may be controlled according to the physical properties of the ink in the replaced ink tank, or the volume of the flow path.

[0055] In S703, the print control unit 307 performs ink suction of a specified amount based on the recovery operation selected in S702. In S704, the print control unit 307 performs preliminary ejection to eliminate color mixing after suction recovery based on the recovery operation selected in S702. Here, since only the GY ink tank has been replaced, only the GY ink tank performs the ink suction operation in recovery mode D and the preliminary ejection operation to eliminate color mixing. At the same time, empty suction is performed in the cap 202.

[0056] In S705, the print control unit 307 separates the cap 202 from the print head. In S706, based on the recovery operation selected in S702, the print control unit 307 pre-discharges only the ink tank of the color whose ink tank was replaced (in this case, GY). As mentioned above, because the GY ink path is long, in recovery mode D, a large amount of pre-discharge is set to eliminate density unevenness between the old and new inks and to eliminate contamination of foreign matter due to the tank replacement. If there are ejection port positions where density unevenness is difficult to eliminate depending on the shape of the ink path, the ejection amount can also be set according to that pattern.

[0057] In S707, the print control unit 307 performs a preliminary ejection of all colors to eliminate mixing of ejected inks with other colors and enable proper printing, based on the recovery operation selected in S702. In S708, the print control unit 307 performs wiping to remove ink that has adhered to the face surface during the preliminary ejection. In S709, the print control unit 307 performs a preliminary ejection to prepare the ejection port for printing after wiping, based on the recovery operation selected in S702. In S710, the print control unit 307 performs a roller release operation. In S711, the print control unit 307 resets the replacement flag for each ink tank and terminates the process shown in Figure 7.

[0058] Thus, the image forming apparatus according to this embodiment can perform a recovery operation in which the amount of ink discharged during the recovery operation of an ink tank that has been replaced differs from the amount of ink discharged during the recovery operation of an ink tank that has not been replaced. By performing such a process, unnecessary ink consumption during the recovery operation of the recording head can be suppressed.

[0059] As described above, the image forming apparatus according to this embodiment can perform a first pre-discharge (e.g., the one in S707), a second pre-discharge (e.g., the one in S708), and a third pre-discharge (e.g., the one in S709) in this order. Here, the second pre-discharge is a pre-discharge that discharges ink only from the ink tank that has been replaced among the multiple ink tanks provided by the image forming apparatus. Here, the first and third pre-discharges are pre-discharges that discharge ink from all the ink tanks provided by the image forming apparatus. In particular, the first pre-discharge is a pre-discharge to eliminate color mixing, and the third pre-discharge is a pre-discharge to prepare the discharge port after wiping. The first and third pre-discharges, which are performed before and after the second pre-discharge, may be performed individually, both may be performed, or neither may be performed.

[0060] Figure 9 is a diagram illustrating a recovery mode in a conventional example for comparison with the process according to this embodiment. In the table shown in Figure 9, the same amount of ink is drawn from all ink tanks. Compared to the process using the table shown in Figure 9, the process using the table shown in Figure 8 can suppress unnecessary ink discharge for PBK, R, C, and M, which correspond to the same cap as GY, by 1.5 seconds when only the GY ink tank is replaced. In a configuration where each color has 1280 nozzles and one drop is 4.5 pl, this represents a reduction in ink consumption equivalent to approximately 150 mg. In this example, since ink is discharged by pre-discharge only for the color of the replaced ink tank, it is possible to suppress the discharge of ink of other colors.

[0061] Although this explanation describes an example where only the GY ink tank is replaced, if multiple ink tanks are replaced, a pre-discharge operation can be performed for those tanks. In that case, the print control unit 307 obtains the value of the item "Pre-discharge Ink Tank Replacement" for all replaced ink tanks in S702, and performs a pre-discharge operation for each ink tank in S706. Furthermore, if all ink tanks of all colors are replaced, the recovery mode E shown in Figure 8 can be selected as the recovery operation, and the recovery time can be shortened by recovering all ink tanks at once with a suction operation.

[0062] The print control unit 307 may also change the content of the recovery operation depending on the number of ink tanks that have been replaced. For example, the print control unit 307 may control the amount of ink discharged during the recovery operation of a replaced ink tank so that when the number of replaced ink tanks is less than a predetermined number (e.g., less than 3), it is greater than when the number of replaced ink tanks is a predetermined number or greater (e.g., a fixed value).

[0063] The type of ink used in the image forming apparatus according to this embodiment is not particularly limited, but for example, an ink containing pigment may be used. When using an ink containing pigment, if the ink tank is left standing in the same position for a long time, components with different specific gravities in the ink, including the pigment, may settle, and density unevenness may become more noticeable after the ink tank is replaced. Even in such cases, the image forming apparatus according to this embodiment makes it possible to eliminate density unevenness while suppressing unnecessary ink consumption.

[0064] (Examples of application) In Figure 8, it was explained that when all ink tanks are replaced, the same pre-discharge is performed for all ink tanks. However, when all ink tanks are replaced, the amount of pre-discharged ink that has been replaced may be set separately for each ink tank.

[0065] Figure 10 is a table showing the reserve discharge amount for each ink tank, which is set separately for each ink tank and used when all ink tanks of all colors are replaced. Here, the reserve discharge amount for each ink tank is set separately in the table as part of the discharge operation when all ink tanks of all colors are replaced. Compared to the process using the table shown in Figure 9, the process using the table shown in Figure 10 can suppress unnecessary ink discharge by 1.0 sec for ink tanks with short flow paths, such as R or Y. In a configuration where each color has 1280 nozzles and one drop is 4.5 pl, this represents a reduction in ink consumption equivalent to approximately 100 mg.

[0066] When all ink tanks are replaced, the ink color with the shortest ink flow path will consume 10,000 ink pulses, as shown in the table in Figure 10. By converting this reserve amount into ink suction time and storing it in the table, the processing load can be reduced, and the processing time during recovery can be shortened. Figure 11 shows an example of a table used for converting such reserve amount to suction time. Here, 10,000 reserve pulses are converted to 0.5 seconds.

[0067] Furthermore, considering that the characteristics differ for each recording head and recovery device, such conversion tables may be created as appropriate. This process suppresses the total amount of ink discharged, and by converting the reserve discharge amount value in the table into a suction time value, the recovery operation can be processed in a short time.

[0068] The disclosures herein include the following image forming apparatus, control method, and program. (Item 1) A recording head having multiple rows of ejection ports that eject ink supplied from multiple ink tanks, A detection means for detecting which of the aforementioned multiple ink tanks has been replaced, As a recovery operation of the recording head after the aforementioned replacement, the operation control means performs a suction operation to draw ink from the ejection port row and an ejection operation to eject ink from the recording head. Equipped with Image forming apparatus, characterized in that the operation control means makes the content of a first discharge operation performed as a recovery operation in the first ink tank among the plurality of ink tanks that has been replaced different from the content of a second discharge operation performed as a recovery operation in the first ink tank when the first ink tank has not been replaced. (Item 2) The image forming apparatus according to item 1, characterized in that the operation control means controls the amount of ink discharged from the recording head of the first ink tank during the first discharge operation to be greater than the amount of ink discharged from the recording head of the first ink tank during the second discharge operation. (Item 3) The image forming apparatus according to item 1 or 2, characterized in that the operation control means individually sets the content of the discharge operation from the recording head in each of the plurality of ink tanks. (Item 4) The image forming apparatus according to any one of items 1 to 3, characterized in that the operation control means further controls the content of the recovery operation based on the number of ink tanks among the plurality of ink tanks that have been replaced by the detection means. (Item 5) The image forming apparatus according to item 4, characterized in that the operation control means controls the amount of ink discharged in the first discharge operation of the first ink tank to be greater than the amount of ink tanks detected as having been replaced by the detection means when the number of ink tanks detected as having been replaced by the detection means is less than a predetermined number. (Item 6) The image forming apparatus according to any one of items 1 to 5, characterized in that the discharge operation for discharging ink from the recording head includes a first pre-discharge that discharges ink from all of the plurality of ink tanks, a second pre-discharge that discharges ink only from the ink tanks among the plurality of ink tanks that have been detected as having been replaced by the detection means, and a third pre-discharge that discharges ink from all of the plurality of ink tanks. (Item 7) The image forming apparatus according to item 6, characterized in that the operation control means controls the ink tank so as not to perform the second preliminary ejection if the replacement ink tank is an ink tank that has already been used, even if the detection means has detected that the ink tank has been replaced. (Item 8) The image forming apparatus according to any one of items 1 to 7, characterized in that the ink contains a pigment. (Item 9) A detection step for detecting which ink tank has been replaced among the multiple ink tanks in a recording head having multiple rows of ejection ports that eject ink supplied from multiple ink tanks, As a recovery operation of the recording head after the aforementioned replacement, the operation control process includes performing a suction operation to draw ink from the ejection port row and an ejection operation to eject ink from the recording head. Equipped with The control method is characterized in that the operation control step makes the content of the first discharge operation performed as a recovery operation in the first ink tank among the plurality of ink tanks that has been replaced different from the content of the second discharge operation performed as a recovery operation in the first ink tank when the first ink tank has not been replaced. (Item 10) A program for causing a computer to function as one of the means of an image forming apparatus described in any one of items 1 through 8.

[0069] (Other examples) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0070] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0071] 101: Carriage, 102: Carriage motor, 103: Timing belt, 104: Guide shaft, 105: Flexible cable, 106: Conveyor roller pair, 107: Printing medium, 108: Recovery device

Claims

1. A recording head having multiple rows of ejection ports that eject ink supplied from multiple ink tanks, A detection means for detecting which of the aforementioned multiple ink tanks has been replaced, As a recovery operation of the recording head after the aforementioned replacement, the operation control means performs a suction operation to draw ink from the ejection port row and an ejection operation to eject ink from the recording head. Equipped with Image forming apparatus, characterized in that the operation control means makes the content of a first discharge operation performed as a recovery operation in the first ink tank among the plurality of ink tanks that has been replaced different from the content of a second discharge operation performed as a recovery operation in the first ink tank when the first ink tank has not been replaced.

2. The image forming apparatus according to claim 1, characterized in that the operation control means controls the amount of ink discharged from the recording head of the first ink tank during the first discharge operation to be greater than the amount of ink discharged from the recording head of the first ink tank during the second discharge operation.

3. The image forming apparatus according to claim 1, characterized in that the operation control means individually sets the content of the discharge operation from the recording head in each of the plurality of ink tanks.

4. The image forming apparatus according to claim 1, characterized in that the operation control means further controls the content of the recovery operation based on the number of ink tanks among the plurality of ink tanks that have been replaced by the detection means.

5. The image forming apparatus according to claim 4, characterized in that the operation control means controls the amount of ink discharged in the first discharge operation of the first ink tank to be greater than the amount of ink tanks detected as having been replaced by the detection means when the number of ink tanks detected as having been replaced by the detection means among the plurality of ink tanks is less than a predetermined number.

6. The image forming apparatus according to claim 1, characterized in that the discharge operation for discharging ink from the recording head includes a first preliminary discharge for discharging ink from all of the plurality of ink tanks, a second preliminary discharge for discharging ink only from the ink tanks among the plurality of ink tanks that have been detected as having been replaced by the detection means, and a third preliminary discharge for discharging ink from all of the plurality of ink tanks.

7. The image forming apparatus according to claim 6, characterized in that the operation control means controls the ink tank so as not to perform the second preliminary ejection if the replacement ink tank is an ink tank that has already been used, even if the ink tank has been detected by the detection means as having been replaced.

8. The image forming apparatus according to claim 1, characterized in that the ink contains a pigment.

9. A detection step for detecting which ink tank has been replaced among the multiple ink tanks in a recording head having multiple rows of ejection ports that eject ink supplied from multiple ink tanks, As a recovery operation of the recording head after the aforementioned replacement, the operation control process includes performing a suction operation to draw ink from the ejection port row and an ejection operation to eject ink from the recording head. Equipped with The control method is characterized in that the operation control step makes the content of the first discharge operation performed as a recovery operation in the first ink tank that has been replaced among the plurality of ink tanks different from the content of the second discharge operation performed as a recovery operation in the first ink tank when the first ink tank has not been replaced.

10. A program for causing a computer to function as one of the means of an image forming apparatus according to any one of claims 1 to 8.

Images