Patent ID: 12227012

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

An exemplary embodiment of the present disclosure is described below with reference to the accompanying drawings.

FIG.1is a cross-sectional view of the entire inkjet printing apparatus according to the present embodiment. Upon receiving a print command sent from a host apparatus, such as a personal computer (PC), a control unit drives a motor21that serves as a drive source for each of mechanisms of the printing apparatus. The motor21is illustrated inFIG.2(described below). The motor21drives a sheet feed mechanism2, an intermediate roller6, a conveyance roller10disposed downstream of the intermediate roller6, and a sheet discharging roller12disposed downstream of the conveyance roller10.

The sheet feed mechanism2conveys print media P stacked on the paper feed tray1so as to push out the print media P, brings the print media P into contact with a separating member4, and separates the print media P one by one. The separated print medium P is conveyed by the sheet feed mechanism2to the intermediate roller6and its paired pinch roller7. When the leading edge of the print medium P passes through the intermediate roller6, the leading edge collides with the circumference of a U-turned paper guide, and the conveyance direction is reversed while following the paper guide. Then, the leading edge reaches the conveyance roller10and its paired pinch roller11. When the leading edge of the print medium P reaches a nip portion of the conveyance roller10, the position of the leading edge is adjusted in accordance with the type of print medium, and the skew of the print medium is corrected. This leading edge position adjustment is also referred to as “leading edge registration”. When the leading edge registration is performed, the conveyance roller10can be driven by the motor21so as to also rotate in a direction in which the print medium P is returned, that is, in the direction opposite to the conveyance direction. In contrast, the intermediate roller6is configured to always rotate in a forward conveyance direction, that is, in a direction in which the print medium P is discharged, regardless of which direction the motor21drives. This two-roller configuration can form a loop of the print medium in front of the conveyance roller10. When the print medium P reaches the conveyance roller10, the motor21reverses its driving direction so as to temporarily rotate the conveyance roller10in the direction in which the print medium P is rewound. Thereafter, the conveyance roller10is rotated again in the forward direction to convey the print medium P in which the print medium P is discharged. In this manner, the leading edge registration is completed. After the leading edge registration is performed, the print medium P is conveyed onto a platen, and the sheet feeding operation is completed.

A printing unit714(refer toFIG.7) that scans in a direction intersecting the direction in which the print medium P is conveyed is disposed above the platen. The printing apparatus according to the present embodiment is a so-called serial type printing apparatus in which the printing unit714scans in a scanning direction (the X direction inFIGS.1to6) that intersects the conveyance direction (the Y direction inFIGS.1to6). During the scanning, ink droplets are discharged from the nozzles (the discharge ports) of a print head717(refer toFIG.7) mounted in a printing unit714onto the print medium P conveyed onto the platen, and an image is printed on the print medium P.

FIGS.13A and13Bare schematic illustrations of the print head717.FIG.13Ais a conceptual diagram of a nozzle surface (a discharge port surface) on which a nozzle array including a plurality of nozzles (discharge ports) for discharging ink is disposed.FIG.13Billustrates the nozzle arrangement in each of nozzle rows. In each of the nozzle row, nozzles are arranged at intervals of 600 dpi in the Y direction inFIGS.13A and13B. Two nozzle rows for each ink color are arranged in a staggered pattern with a shift of 1200 dpi in the Y direction. That is, the printing resolution in the Y direction for each ink color is 1200 dpi.

The print head717includes an ink flow passage (not illustrated) for supplying ink to the nozzles. In addition, each of the nozzles includes a print element that generates energy for discharging ink in the form of droplets. According to the present embodiment, an electrothermal transducer element that converts electric energy into heat energy is used as the print element. However, the print element is not limited thereto, and may be a piezo element.

InFIG.13A, rows a and b are nozzle rows arranged to discharge cyan ink, rows c and d are nozzle rows arranged to discharge magenta ink, and rows e and f are nozzle rows arranged to discharge yellow ink. Similarly, rows g and h are nozzle rows to discharge black ink. Each of the nozzle rows for cyan, magenta, or yellow color ink has 256 nozzles arranged therein, and the nozzle row for black ink has 640 nozzles arranged therein.

A printing operation to print an image is performed by repeating the conveyance by the conveyance roller10described above and the print scan by the printing unit714. According to the present embodiment, a method known as multipass printing method is employed in which a plurality of scans are performed on a unit area of the print medium to complete printing of an image on the unit area. A print scan by the printing unit714is also referred to as a “pass”, and the number of times the print head717scans to complete printing on a predetermined unit area is referred to as the “number of passes”. When the printing of an image is completed, the print medium P is conveyed in the forward conveyance direction by a pair consisting of the sheet discharging roller12and a spur13and is discharged.

FIG.2is a perspective view of a driving mechanism of the inkjet printing apparatus according to the present embodiment. More specifically,FIG.2illustrates the details of the drive transmission mechanism that transmits the drive force of the motor21to the conveyance roller10and the intermediate roller6. According to the present embodiment, both the conveyance roller10and the intermediate roller6are commonly driven by the motor21. This enables reduction in the size and cost of the printing apparatus body.

A gear (not illustrated) attached to the rotating shaft of the motor is connected via an idler gear22to a conveyance input gear23attached to one end of a shaft of the conveyance roller10. A code wheel (not illustrated) with markings is attached to the conveyance input gear23, and the rotation amount of the motor can be detected. By reading the code wheel with an encoder sensor (not illustrated), the rotation amount of the conveyance roller10can be controlled. A conveyance output gear24is attached to the other end of the shaft of the conveyance roller10. The drive force is transmitted from the conveyance output gear24to a sun gear31via an idler gear25. The sun gear31is configured as a clutch gear.

FIG.3is a perspective view of the configuration of the clutch gear illustrated inFIG.2. As illustrated inFIG.3, a spring33is provided inside the sun gear31, and the forward rotation of the sun gear31tightens the spring33, enabling the sun gears31and32to rotate together. In contrast, the reverse rotation of the sun gear31opens the spring33. Therefore, when a load is applied to the sun gear32, the sun gear31and the sun gear32slip from each other and cannot rotate together. A swing arm34is provided on the shaft of the sun gear31, and a planet gear35is attached onto a swing arm34. A swing arm spring36is provided between the planet gear35and the swing arm34so that when the sun gear31rotates, the swing arm34also rotates together due to friction. A step38of a multi-step gear37is meshed with the sun gear32. In addition, a step39of the multi-step gear37is attached at a position where the step39can be meshed with the planet gear35.

Due to the configuration, when the sun gear31rotates in the forward direction (the direction of arrow s), the drive force input to the sun gear31is transmitted to the step38of the multi-step gear37by the sun gear32that rotates together with the sun gear31. In contrast, when the sun gear31rotates in the reverse direction (the direction of arrow t), the swing arm34moves in the direction of arrow u inFIG.3, the planet gear35and the step39of the multi-step gear37are meshed, and the drive force is transmitted to the multi-step gear37. Since the sun gear32is a clutch gear, the sun gear easily slips during reverse rotation and does not interfere with driving. Due to the transmission method, the direction of rotation of the multi-step gear37is the same regardless of whether the sun gear31rotates in the forward or reverse direction.

FIG.4is a perspective view of a recovery mechanism. The recovery mechanism715of the present embodiment is used to ensure the ink discharge performance of the print head717. InFIG.4, a slider40follows the movement of the print head717in the reciprocating direction and can slide in an area outside the print area in which the image is printed. In addition, the slider40is movable in a direction perpendicular to the color ink discharge port surface and the black ink discharge port surface of the print head717, that is, in the direction in which the ink is discharged. Such movement of the slider40enables the caps41and42to move closer to (contact) the discharge port surface of the print head717and away from (separate from) the discharge port surface.

The cap41is used for cyan, magenta, and yellow color ink, and the cap42is used for black ink. A cap holder44and a cap holder45are mounted on the slider40. In addition, in an area that differs from the print area, the slider40is movable in accordance with the movement of the print head717in the direction in which the printing unit714moves and in directions in which the print head717and the cap for each of black and color move closer to and away from each other. The caps41and42have pump tubes51aand51bconnected thereto, respectively, and the pump tubes51aand51bare connected to a pump mechanism including a suction pump that generates negative pressure. By driving the suction pump, a recovery operation can be performed to suck ink from each of the discharge ports via the cap.

FIG.5is a perspective view of the drive transfer construction from the conveyance roller10to the pump mechanism, andFIG.6is a perspective view of the pump mechanism. Pump rollers64are attached to a pump roller holder62. The pump tubes51aand51bextend along one-half the circumference of the inner wall of a pump base60and are rotatably inserted into the pump base60. When the conveyance roller10is reversed due to drive force of the motor21with the print head717capped, the drive force is transmitted to the pump roller holder62via the conveyance output gear24, the idler gear25, and a pump drive gear50. The pump rollers64move cams provided in the pump roller holder62, so that the inner wall of the pump base60and the pump rollers64compress the pump tubes51aand51b. When the reverse driving of the conveyance roller10is continued, a negative pressure is generated inside the pump tubes51aand51b.

When the discharge port surface of the print head717is tightly capped by the caps41and42and a negative pressure is generated, ink can be sucked from the discharge ports of the print head717via the caps41and42. When the discharge port surface is not capped and a negative pressure is generated, a discharge operation (an open suction action) can be performed for sucking and discharging ink accumulated in the cap due to preliminary discharge or the like. In addition, if, in the open suction action, the pump tubes51aand52bare individually compressed, ink suction from the nozzles or an open suction action in the cap can be performed on the caps41and42individually.

When the negative pressure inside the pump tube is released after the suction operation to suck ink is completed, the pump roller holder62is driven to rotate in the opposite direction. That is, the conveyance roller10is rotationally driven in the forward direction. By uncompressing the pump tubes51aand51bthat are compressed by the pump rollers64, the negative pressure inside the pump tubes is released.

FIG.7is a block diagram of the outline of the control configuration according to the present embodiment. A control unit72includes a central processing unit (CPU), a read only memory (ROM), and a random access memory (RAM). The CPU performs various processing in accordance with programs stored in memories, such as a ROM and a RAM. A RAM is a volatile storage that temporarily stores programs and data. A ROM is a nonvolatile storage that stores table data and programs used in each of the processes (described below). As illustrated inFIG.7, the control unit72outputs a motor current control signal to each of motor drivers73and712in accordance with an input from an operation panel71or a connected PC710. Thus, the control unit72controls the operations described below.

A paper feed motor74, which corresponds to the motor21for driving, for example, the above-described conveyance roller10, drives a paper feed and discharge roller unit76via a conveyance drive transmission system75and a drive switching mechanism77in response to a signal input from the motor driver73. In addition, a paper feeding roller unit78and an intermediate roller unit79, which respectively correspond to the above-described conveyance roller10and intermediate roller6, are similarly driven. The paper feed motor74drives the above-described pump tubes of the recovery mechanism.

Furthermore, a printing unit motor713drives the printing unit714in response to a signal input from the motor driver712. A variety of sensors711provided in a paper conveyance unit and the printing unit714detect the position of the print medium P, the number of rotations of the conveyance roller10, the printing position of the printing unit714, and the like. The detected signals are input to the control unit72, which outputs appropriate control signals to the motor drivers73and712.

In addition, the control unit72outputs print data to a head driver716to drive the print head717. The print data includes preliminary discharge data to ensure the discharge performance of the print head717, as well as the image to be printed. According to the present embodiment, a preliminary discharge operation includes the following three types, that is, pre-printing preliminary discharge performed before a printing operation to print an image on a print medium, intra-printing preliminary discharge performed during the printing operation, and intra-standby preliminary discharge in preparation for the input of a subsequent print command. These types of preliminary discharges are performed to discharge ink that has thickened in the vicinity of the discharge ports. According to the present embodiment, the ink is discharged onto the caps. Preliminary discharge of color ink is performed toward the cap41, and preliminary discharge of black ink is performed toward the cap42.

FIG.8is a flowchart relating to the printing operation according to the present embodiment. Hereinafter, a reference numeral starting with the letter “S” indicates “step”. The flow starts when a printing apparatus receives a print command. In S81, a cap opening operation is performed. In S82, the print medium P is fed. During the sheet feeding operation for the print media P, in S83, a first pre-printing preliminary discharge (pre-printing preliminary discharge1) is performed toward the caps41and42. In S84, a printing operation to print an image on the print medium P is performed. In S85, the printing operation is finished. After the image printing operation is started, intra-printing preliminary discharge is performed toward the cap after the printing unit714finishes scanning and before starting the subsequent scanning. After the printing operation is finished, intra-standby preliminary discharge is performed in S86in preparation for reception of the subsequent print command in the cap-open standby state. The intra-standby preliminary discharge is performed at predetermined time intervals. According to the present embodiment, the intervals are two-second intervals. The intra-standby preliminary discharge ensures the discharge performance in the subsequent printing operation even if there is a standby time until a subsequent reception command after the previous image is printed.

The control unit72counts the amount of ink discharged toward the cap, that is, the number of discharged ink droplets, in each of the first pre-printing preliminary discharge performed in S83, the intra-printing preliminary discharge performed in S84, and the intra-standby preliminary discharge performed in S86. Then, the control unit72stores the count result in the RAM of the control unit72. According to the present embodiment, the count value is accumulated, and the accumulated value stored in the RAM is reset when the ink stored in the cap is discharged by an open suction action. In S87, the accumulated value of the amount of ink stored in the cap is calculated and compared with a threshold value X stored in advance. The comparison with the threshold value for the intra-standby preliminary discharge performed at predetermined time intervals is performed immediately before the intra-standby preliminary discharge performed at predetermined time intervals after the intra-standby preliminary discharge performed in S86. If the accumulated value is less than or equal to the threshold value X, the intra-standby preliminary discharge in S86is continued. However, if the accumulated value is greater than the threshold value X, the processing proceeds to S88, where the intra-standby preliminary discharge is stopped. That is, the setting is changed from the setting of performing preliminary discharge at regular time intervals to the setting of not performing preliminary discharge, and the print head717stands by above the caps. The comparison of the accumulated value and the threshold value X in S87is periodically performed until the upper limit of the standby time (described below) is reached or until the subsequent print command is received, and if the accumulated value does not exceed the threshold value, the process of stopping the intra-standby preliminary discharge in S88is skipped.

The threshold value X is a value less than the cap capacity. In addition, it is desirable that the threshold value X be a value less than the cap capacity even if the amount of ink used in second pre-printing preliminary discharge performed when the subsequent print command is received and the amount of ink used in the intra-printing preliminary discharge are added to the threshold value X.

Subsequently, in S89, the printing apparatus stands by for reception of a subsequent print command. In S810, it is determined whether the standby time has exceeded a predetermined upper limit time. According to the present embodiment, “A seconds” is 300 seconds. The reason why the upper limit of the standby time is set in this way is to ensure the ink discharge performance. If the standby time with the cap open is too long, a large amount of ink needs be sucked from the nozzles to recover the ink discharge performance before the subsequent printing. If it is determined that the standby time is less than or equal to A seconds, the standby state is continued. However, if it is determined that the standby time is greater than A seconds, the standby state is terminated, and the processing proceeds to S816, where the cap is brought into tight contact with the print head717and is closed.

If, in S811, a print command is received while the standby time is less than or equal to A seconds, the standby state is terminated, and the processing proceeds to S812. In S812, the sheet feeding operation is performed. In S813, the pre-printing preliminary discharge is performed toward the cap to ensure the ink discharge performance during a subsequent printing operation. Thereafter, in S814, a printing operation is performed.

The conditions for pre-printing preliminary discharge in S813differ in accordance with whether the intra-standby preliminary discharge is continued or stopped in the standby state. When a print command is received without stopping the intra-standby preliminary discharge, the first pre-printing preliminary discharge (pre-printing preliminary discharge1) is performed. When a print command is received in a standby state with intra-standby preliminary discharge stopped, the second pre-printing preliminary discharge (pre-printing preliminary discharge2) is performed. The second pre-printing preliminary discharge is characterized in that the discharge frequency is higher, the number of ink discharge operations is greater, or the discharge energy added to one discharge operation is greater than that of the first pre-printing preliminary discharge. The second pre-printing preliminary discharge corresponds to the event that the intra-standby preliminary discharge is stopped in S88and is intended to improve the state in which the ink has thickened due to absence of intra-standby preliminary discharge. For this reason, the preliminary discharge conditions are determined so that a larger amount of ink is discharged than in the first pre-printing preliminary discharge.

In S815, the printing operation is finished. In S816, the cap is closed. Thus, the series of processes is completed.

As described above, according to the present embodiment, after completion of the printing operation, the intra-standby preliminary discharge is performed at predetermined time intervals until reception of a subsequent print command. At this time, the intra-standby preliminary discharge is stopped at the time when it is determined that the amount of ink in the cap is greater than a predetermined threshold value based on the capacity of the cap.

As a result, the ink can be prevented from spilling out of the cap by continuing the intra-standby preliminary discharge. In addition, when a subsequent print command is received, operations, such as cap opening, can be eliminated and, thus, the downtime can be reduced.

In addition, as illustrated inFIG.9, if the standby time after the end of printing exceeds A seconds, the processing proceed to S817, where in preparation for a subsequent print command, an open suction action may be performed to discharge the ink accumulated in the cap due to the preliminary discharge. By performing the open suction action, the accumulated value that is in the RAM and that indicates the amount of ink in the cap can be reset.

In addition, as illustrated inFIG.10, it may be determined whether the amount of ink accumulated in the cap is less than or equal to a threshold value Y after the end of printing. If it is determined that the amount of ink accumulated in the cap is less than or equal to the threshold value Y, the processing returns to the printing standby operation in S89. If it is determined that the amount of ink accumulated in the cap is greater than the threshold value Y, the open suction action in S817is performed and, thereafter, the cap is closed in S816. At this time, the relationship between the threshold value X and the threshold value Y is X<Y<cap capacity. By setting the threshold value Y in this way and comparing the threshold value Y with the amount of ink in the cap, the open suction action and cap closing can be postponed. As a result, the downtime can be reduced.

Although inFIGS.9and10, the cap is closed after the open suction action is performed, only the open suction action may be performed.

Second Embodiment

FIGS.11A and11Bare cross-sectional views of an inkjet printing apparatus1101according to the second embodiment.

Roll paper1102, which is a print medium, has a width of 24 inches. The roll paper1102is set in a roll paper holder1103. A sensor1104detects the presence or absence of a print medium, and a pinch roller1105nips the roll paper, and a conveyance roller10is disposed to face the pinch roller1105. A conveyance roller1106is disposed downstream in the conveyance direction, and a carriage1107includes the print head717mounted therein. A cutter1108cuts the roll paper after printing is completed.FIG.11Billustrates the roll paper1102that is nipped by the pinch roller1105. The transport drive configuration and recovery mechanism configuration according to the present embodiment are the same as those of the first embodiment.

A series of processes for the printing operation according to the present embodiment is the same as that inFIGS.8to10. However, unlike the printing processes inFIGS.8to10, after end of the printing in S85, the roll paper1102is nipped during a period from the intra-standby preliminary discharge in S86to the end of printing in S815. According to the present embodiment, negative pressure is generated in the cap by reversing the conveyance roller10. For this reason, to perform a cap closing operation to bring the print head717into contact with the cap and the open suction action to discharge ink in the cap, the roll paper1102needs to be released from the nip. As illustrated inFIG.11B, when the roll paper1102is released from the nip, the leading edge of the roll paper is rewound to a position upstream of the sensor1104. To perform the printing operation again after the roll paper1102is released from the nip, it takes time for nipping. For this reason, it is desirable to avoid releasing of the roll paper1102from the nip as much as possible.

In the processes illustrated inFIG.8, since the print medium P is nipped even during the printing standby in S89, the paper feeding operation in S812can be performed immediately after a print command is received in S811. The paper feeding operation here means the operation of conveying the print medium P from the nip position to an area in which the print head717can perform printing.

In contrast, according to the present embodiment, when the roll paper1102is nipped, the caps41and42remain separated from the discharge port surface of the print head717. As illustrated inFIG.14, if the standby time starting from the end of printing is greater than A seconds during the printing standby in S89or when the printing is finished in S815, the processing proceeds to S819, where the nip is released. In S820, the roll paper is rewound until the leading edge of the roll paper reaches a position upstream of the sensor1104. In S817, the motor21is driven to perform an open suction action with the cap separated from the discharge port surface of the print head. Thereafter, in S816, the cap is closed.

Furthermore, according to the present embodiment, as illustrated inFIG.15, the following configuration may be employed. That is, if in S87, it is determined that the accumulated value of the amount of ink stored in the cap is greater than the threshold value X of the cap capacity during intra-standby preliminary discharge in S86, the preliminary discharge is stopped in S88. Thereafter, the processing proceeds to S819, where the nip is released. In S820, the roll paper is rewound until the leading edge of the roll paper reaches a position upstream of the sensor1104. In S817, the motor21is driven to perform an open suction action with the cap separated from the discharge port surface of the print head. In S816, the cap is closed.

As described above, like the first embodiment, the setting is changed so that when the accumulated value of the amount of ink stored in the cap reaches a predetermined threshold value of the cap capacity, the roll paper remains nipped and periodic intra-standby preliminary discharge is not performed. As a result, spillover of ink from the cap can be prevented. Furthermore, according to the present embodiment, when a subsequent print command is received, the downtime can be reduced by eliminating the re-nipping operation required for paper feeding. In addition, by using a threshold value corresponding to the cap capacity, the timing of performing the open suction action is delayed as much as possible, and the nip release and a re-nipping operation required for performing an open suction action are reduced, which further reduces the downtime.

Third Embodiment

The configuration of an inkjet printing apparatus according to the third embodiment is the same as in the second embodiment.FIG.12illustrates the flow of the printing operation according to the present embodiment. The processing up to the end of printing in S1205is the same as that in the second embodiment.

After printing is finished, the roll paper1102remains nipped, and the caps41and42remain separated from the discharge port surface of the print head717in preparation for a subsequent print command. In S1206, it is determined whether the printing apparatus is in a standby mode. The standby mode is described in detail below. Standby mode 1 is an inter-page delay mode, standby mode 2 is an eject cut mode, and standby mode 3 is a user cut mode.

The inter-page delay in standby mode 1 is based on the assumption that a printed subject cut by the cutter1108is dropped into a basket (not illustrated) or the like after the end of printing. In the case of a print medium onto which ink is difficult to fix, such as a film, the area where an image is printed may be rubbed when the printed subject drops, resulting in an image defect, such as disappearance of part of the ink image. To prevent the occurrence of such an image defect, a predetermined wait time is provided between the end of printing and the cutting by the cutter1108to improve the fixability of the ink. A user can set the wait time for the inter-page delay to any value by using the host apparatus or a UI of the printing apparatus (not illustrated).

The eject cut in standby mode 2 is a mode in which the user determines the timing of cutting by the cutter1108after printing is finished. At the timing when the user wants to cut, the user sends an instruction to command the cutting operation from the host apparatus or the UI of the printing apparatus.

The user cut in standby mode 3 is a mode in which if the print medium is of a type that is difficult to cut by the cutter1108, the user manually cuts the print medium. After cutting the print medium, the user inputs information indicating that a cutting operation is finished by using the host apparatus or the UI of the printing apparatus.

In any of standby modes 1 to 3, a standby time is required after printing is finished. For this reason, intra-standby preliminary discharge is performed in preparation for the subsequent print command. In S1206, it is determined whether any of the standby modes 1 to 3 is applied. In S1210, the largest threshold value Z among the applicable standby modes is set as the threshold value for the amount of ink in the cap. For example, let Z1, Z2, and Z3 be the threshold value for inter-page delay in standby mode 1, the threshold value for eject cut in standby mode 2, and the threshold value for user cut in standby mode 3, respectively. Then, Z1>Z2>Z3. Thereafter, in S1211, intra-standby preliminary discharge is performed at predetermined intervals as described above. Subsequently, in S1212, the accumulated value of the amount of ink in the cap stored in the RAM is compared with the threshold value. If it is determined that the accumulated value of the amount of ink in the cap is less than or equal to the threshold value Z, the processing proceeds to S1211, where intra-standby preliminary discharge is continued. However, if it is determined that the accumulated value of the amount of ink in the cap is greater than the threshold value Z, the setting is changed in S1213so that the intra-standby preliminary discharge is stopped.

In contrast, in the case of normal standby that does not correspond to any one of standby modes 1 to 3, the processing proceeds to S1207, where the threshold value of the amount of ink in the cap is set to X. Thereafter, in S1208, intra-standby preliminary discharge is performed at predetermined intervals. In S1209, the accumulated value of the amount of ink in the cap stored in the RAM is compared with the threshold value X. If it is determined that the accumulated value of the amount of ink in the cap is less than or equal to the threshold value X, intra-standby preliminary discharge is continued at predetermined intervals in S1208. However, if the accumulated value of the amount of ink in the cap is greater than the threshold value X, the setting is changed in S1213so that the intra-standby preliminary discharge is stopped.

The relationship between the threshold value X and the threshold value Z is Z<X. The reason for this is that standby modes 1 to 3 have a long standby time and the amount of ink discharged to the cap due to the intra-standby preliminary discharge increases, leading to spillover of ink from the cap. In addition, the number of open suction actions required to prevent spillover of ink from the cap increases, leading to an increase in downtime. Thus, in the case of standby modes 1 to 3, it is desirable to change the setting so that the intra-standby preliminary discharge is stopped as soon as possible.

After stopping the intra-standby preliminary discharge, the printing apparatus stands by for printing with the roll paper being nipped (S1214). In S1215, it is determined whether the standby time is less than or equal to A seconds (300 seconds according to the present embodiment). If it is determined that the standby time is greater than A seconds, the nip is released in S1225, an open suction action is performed in S1226, and the cap is closed in S1227. However, if, in S1216, the print command is received before the standby time becomes greater than A seconds, the paper feeding operation is performed in S1217. Thereafter, in S1218, it is determined whether the previous printing operation corresponds to any one of the standby modes 1 to 3. If the previous printing operation corresponds to any one of the standby modes 1 to 3, the processing proceeds to S1219, where the second pre-printing preliminary discharge is performed into the cap to ensure the discharge performance at the time of subsequent printing. Thereafter, in S1221, a printing operation is performed. In S1222, the printing finishes. However, if the previous printing operation does not correspond to any one of standby modes 1 to 3, third pre-printing preliminary discharge (pre-printing preliminary discharge3) is performed into the cap in S1220. Thereafter, in S1221, a printing operation is performed. In S1222the printing finishes. The relationship among the pre-printing preliminary discharges in terms of the discharge frequency, the number of discharges, or the discharge energy, is as follows: first pre-printing preliminary discharge<second pre-printing preliminary discharge<third pre-printing preliminary discharge.

This is because in the case of standby modes 1 to 3, the time during which the intra-standby preliminary discharge is stopped is long and, thus, the viscosity of the ink around the nozzles increases.

After printing is finished, it is determined whether the amount of ink in the cap is greater than the threshold value X. If it is determined that the amount of ink in the cap is less than or equal to the threshold value X, the processing returns to the standby mode determination process in S1206. However, if it is determined that the amount of ink in the cap is greater than the threshold value X, the processing proceeds to S1224, where it is determined whether the amount of ink in the cap is greater than the threshold value Y. If it is determined that the amount of ink in the cap is less than or equal to the threshold value Y, the processing returns to the print standby process in S1214. However, if it is determined that the amount of ink in the cap is greater than the threshold value Y, the LF nip is released in S1225, the roll paper1102is returned to the position where the leading edge of the roll paper1102has passed the sensor1104, and the printing apparatus goes standby. Thereafter, in S1226, an open suction action is performed by reversing the conveyance roller10with the cap separated from the discharge port surface of the print head717. In S1227, the cap is closed.

As described above, according to the present embodiment, it is determined in which one of standby modes 1 to 3 the printing apparatus is. As a result, the threshold value used for comparison with the amount of ink in the cap can be appropriately set.

Fourth Embodiment

The first to third embodiments have been described with reference to the examples in which the accumulated value of the amount of ink preliminarily discharged into the cap is compared with the threshold value X and, if the accumulated value is greater than the threshold value X, the intra-standby preliminary discharge is stopped. According to the present embodiment, as illustrated inFIG.16, if the accumulated value is greater than a first threshold value, the amount of ink in intra-standby preliminary discharge or the time interval of intra-standby preliminary discharges may be changed. If the accumulated value is greater than a second threshold value, intra-standby preliminary discharge may be stopped.FIG.16is a flowchart obtained by replacing the processes prior to “stand by for printing” inFIGS.8to10with the processes of the present embodiment. After the end of printing in S85, intra-standby preliminary discharge1is performed in S86. During intra-standby preliminary discharge1, 8-droplet preliminary discharge is performed by each of the nozzles at intervals of 2 seconds. In S821, the accumulated value of the amount of ink stored in the cap is calculated before intra-standby preliminary discharge1is performed and is compared with a threshold value X1. If the accumulated value is less than or equal to the threshold value X1, intra-standby preliminary discharge1in S86is continued. However, if the accumulated value is greater than the threshold value X1, the processing proceeds to S822, where intra-standby preliminary discharge2is performed. Intra-standby preliminary discharge2is characterized in that the preliminary discharge interval is greater or the number of preliminary discharges from each nozzle is less than that of intra-standby preliminary discharge1. More specifically, intra-standby preliminary discharge2is 8-droplet preliminary discharge from each of the nozzles at intervals of 4 seconds or 4-droplet preliminary discharge from each nozzle at intervals of 2 seconds. Subsequently, in S87, the accumulated value of the amount of ink stored in the cap is calculated and compared with the threshold value X. If the accumulated value is less than or equal to the threshold value X, intra-standby preliminary discharge2in S822is continued. However, if the accumulated value is greater than the threshold value X, the processing proceeds to S88, where the intra-standby preliminary discharge is stopped. In S89, the printing apparatus stands by for printing. The threshold value X1 is less than the threshold value X.

The subsequent steps are the same as in the first to third embodiments.

As described above, according to the present embodiment, when the accumulated value of the amount of ink preliminary discharged into the cap is greater than the first threshold value, the intra-standby preliminary discharge interval is increased, or the number of droplets of preliminary discharge is reduced. As a result, the time until spillover of ink from the cap can be increased. In addition, spillover of ink from the cap can be prevented by stopping intra-standby preliminary discharge if the accumulated value is greater than the second threshold value.

The present disclosure includes configurations represented by examples of printing apparatuses and printing apparatus control method described below.

Configuration 1

An inkjet printing apparatus includes a print head including a plurality of nozzles, each discharging ink onto a print medium, a cap configured to receive ink discharged from the print head during a preliminary discharge operation, a storing unit configured to store a value corresponding to the amount of ink discharged to the cap during the preliminary discharge operation, and a control unit configured to control the print head to start an intra-standby preliminary discharge operation in which the preliminary discharge operation is performed at predetermined time intervals during a standby period after the print head finishes a printing operation to print an image, continue the intra-standby preliminary discharge operation if an accumulated value of the amount of ink stored in the storing unit is not greater than a threshold value, stop the intra-standby preliminary discharge operation if the accumulated value of the amount of ink is greater than the threshold value, and bring the print head into contact with the cap and terminate the standby period if the standby period exceeds a predetermined time period.

Configuration 2

In the inkjet printing apparatus according to configuration 1, upon receiving a print command relating to a subsequent printing operation during the standby period, the control unit terminates the standby period.

Configuration 3

The inkjet printing apparatus according to Configuration 1 or 2 further includes a conveyance motor and a motor configured to drive a carriage. The intra-standby preliminary discharge operation is started when the conveyance motor and the motor that drives the carriage are not driven for a predetermined time period.

Configuration 4

The inkjet printing apparatus according to any one of Configurations 1 to 3 further includes a discharge unit configured to perform a discharge operation to discharge ink in the cap with the print head not in contact with the cap.

Configuration 5

In the inkjet printing apparatus according to Configuration 4, the discharge unit performs the discharge operation if the standby period exceeds a predetermined time period.

Configuration 6

In the inkjet printing apparatus according to Configuration 4 or 5, if the discharge operation is performed by the discharge unit, the storing unit resets the stored accumulated value.

Configuration 7

In the inkjet printing apparatus according to any one of Configurations 1 to 6, the control unit controls the print head to perform a pre-printing preliminary discharge operation in which ink is discharged into the cap before starting a printing operation subsequent to the printing operation.

Configuration 8

In the inkjet printing apparatus according to Configuration 7, upon receiving a print command after continuously performing the intra-standby preliminary discharge operation, the control unit performs a first pre-printing preliminary discharge operation, and upon receiving a print command after the intra-standby preliminary discharge operation is stopped, the control unit performs a second pre-printing preliminary discharge operation in which an amount of ink to be used is greater than in the first pre-printing preliminary discharge operation.

Configuration 9

In the inkjet printing apparatus according to any one of Configurations 1 to 8, the control unit controls the print head to perform an intra-printing preliminary discharge operation in which ink is discharged into the cap during the printing operation.

Configuration 10

The inkjet printing apparatus according to any one of Configurations 1 to 9 further includes a conveyance roller configured to convey the print medium and a member configured to face the conveyance roller and nip the print medium. The print medium is roll paper, and the intra-standby preliminary discharge operation is performed with the print medium nipped.

Configuration 11

The inkjet printing apparatus according to Configuration 10 further includes a motor configured to function as a drive source for nipping the print medium. The motor is a drive source of a discharge operation to discharge ink in the cap with the print head not in contact with the cap.

Configuration 12

The inkjet printing apparatus according to one of Configurations 1 to 11 further includes a determination unit configured to determine whether the print head is in a normal standby mode, an inter-page delay standby mode, an eject cut standby mode, or a user cut standby mode after the printing operation is finished, and the threshold value is changed on the basis of a result of the determination made by the determination unit.

Configuration 13

In the inkjet printing apparatus according to Configuration 12, the threshold value in each of the inter-page delay standby mode, the eject cut standby mode, and the user cut standby mode is less than in the normal standby mode.

Configuration 14

An inkjet printing apparatus includes a print head including a plurality of nozzles, each discharging ink onto a print medium, a cap configured to receive ink discharged from the print head during a preliminary discharge operation, a storing unit configured to store a value corresponding to the amount of ink discharged to the cap during the preliminary discharge operation, and a control unit configured to control the print head to start an intra-standby preliminary discharge operation in which the preliminary discharge operation is performed at predetermined time intervals during a standby period after the print head finishes a printing operation to print an image and increase the time interval of the intra-standby preliminary discharge operation if an accumulated value of the amount of ink stored in the storing unit is greater than a first threshold value.

Configuration 15

An inkjet printing apparatus includes a print head including a plurality of nozzles, each discharging ink onto a print medium, a cap configured to receive ink discharged from the print head during a preliminary discharge operation, a storing unit configured to store a value corresponding to the amount of ink discharged to the cap during the preliminary discharge operation, and a control unit configured to control the print head to start an intra-standby preliminary discharge operation in which the preliminary discharge operation is performed at predetermined time intervals during a standby period after the print head finishes a printing operation to print an image and decrease the number of droplets of the intra-standby preliminary discharge operation if an accumulated value of the amount of ink stored in the storing unit is greater than a first threshold value.

Configuration 16

A method for controlling a print head is provided. The print head includes a plurality of nozzles, each discharging ink onto a print medium. The method includes starting an intra-standby preliminary discharge operation performed by the print head in which a preliminary discharge operation to discharge ink into a cap is performed at predetermined time intervals during a standby period after the print head finishes a printing operation to print an image, continuing the intra-standby preliminary discharge operation if an accumulated value of the amount of ink stored in a storing unit during the preliminary discharge operation is not greater than a threshold value, stopping the intra-standby preliminary discharge operation if the accumulated value of the amount of ink is greater than the threshold value, and bringing the print head into contact with the cap and terminating the standby period if the standby period exceeds a predetermined time period.

Configuration 17

A method for controlling a print head is provided. The print head includes a plurality of nozzles, each discharging ink onto a print medium. The method includes starting an intra-standby preliminary discharge operation performed by the print head in which a preliminary discharge operation to discharge ink into a cap is performed at predetermined time intervals during a standby period after the print head finishes a printing operation to print an image and increasing the time interval of the intra-standby preliminary discharge operation if an accumulated value of the amount of ink is greater than a threshold value.

Configuration 18

A method for controlling a print head is provided. The print head includes a plurality of nozzles, each discharging ink onto a print medium. The method includes starting an intra-standby preliminary discharge operation performed by the print head in which a preliminary discharge operation to discharge ink into a cap is performed at predetermined time intervals during a standby period after the print head finishes a printing operation to print an image and decreasing the number of droplets of the intra-standby preliminary discharge operation if an accumulated value of the amount of ink is greater than a threshold value.

Embodiment(s) of the present disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.

While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2021-192449 filed Nov. 26, 2021 and No. 2022-166368 filed Oct. 17, 2022, which are hereby incorporated by reference herein in their entirety.