Inkjet control method and inkjet recording device

Abstract

To prevent each of nozzles from getting clogged in a period of time during which a print request is made and then print processing is completed.SOLUTION: A processor 81 obtains sheet-length information representing a length in a conveying direction of a target sheet to be conveyed by a belt conveying device 23 (S1). The processor 81 selects, as a target sheet flushing, either or both of a first flushing process and a second flushing process, in accordance with the sheet-length information, and makes a nozzle unit 30 execute the target flushing process (S8). The first flushing process is a process for discharging ink toward each of a plurality of opening parts 234 in a region where there is no sheet on a conveying belt 231. The second flushing process is a process for discharging ink to a non-drawing region in the target sheet in parallel with print processing to the target sheet.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an inkjet control method and an inkjet recording apparatus for performing flushing control to prevent nozzle clogging.

Background Art

[0002] An inkjet recording apparatus executes a printing process for forming an image on a sheet by an inkjet method. In the inkjet recording apparatus, it is necessary to prevent clogging of each of a plurality of nozzles. For example, it is known that flushing control is performed when a predetermined time has elapsed since the previous printing process (see, for example, Patent Document 1).

[0003] The flushing control is control for causing the inkjet recording apparatus to execute a flushing process of ejecting ink regardless of the printing process. For example, the flushing control is executed in a situation where the plurality of nozzles are covered with a cap.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, even during the period from when a print request occurs until the printing process ends, it is required to appropriately maintain the viscosity of the ink supplied to each of the nozzles and prevent clogging of each of the nozzles.

[0006] An object of the present invention is to provide an inkjet control method and an inkjet recording apparatus capable of preventing clogging of each nozzle during the period from when a print request occurs until the printing process ends.

Means for Solving the Problem

[0007] An inkjet control method according to one aspect of the present invention is a method for controlling an inkjet recording apparatus including a belt conveyance device and a nozzle unit. The belt conveyance device has an endless conveyance belt in which a plurality of openings each formed of one or more through holes are formed at intervals in the circumferential direction, and conveys a sheet on the conveyance belt by rotating the conveyance belt. The nozzle unit has a plurality of nozzles disposed to face the upper surface of the conveyance belt and a plurality of piezoelectric elements that pressurize ink supplied to the plurality of nozzles to discharge ink from the plurality of nozzles, and can execute a printing process. The printing process is a process of forming an image on the sheet by discharging ink onto the sheet conveyed on the conveyance belt. The inkjet control method includes a processor acquiring sheet length information representing the length in the conveyance direction of a target sheet to be conveyed by the belt conveyance device. Further, the inkjet control method includes the processor selecting one or both of a first flushing process and a second flushing process as a target flushing process according to the sheet length information, and causing the nozzle unit to execute the target flushing process. The first flushing process is a process of discharging ink toward each of the plurality of openings in a region of the conveyance belt where the sheet does not exist. The second flushing process is a process of discharging ink into a non-drawing area that is not drawn on the target sheet in parallel with the printing process on the target sheet.

[0008] An inkjet recording apparatus according to another aspect of the present invention includes the belt conveyance device, the nozzle unit, and the processor that realizes the inkjet control method.

Advantages of the Invention

[0009] According to the present invention, it becomes possible to provide an inkjet control method and an inkjet recording apparatus capable of preventing clogging of each nozzle during the period from when a print request occurs until the print process ends.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are an example of embodying the present invention and do not limit the technical scope of the present invention.

[0012] [Configuration of Inkjet Recording Apparatus 10] The inkjet recording apparatus 10 according to the embodiment is a printer capable of performing printing processing by an inkjet method.

[0013] The printing process is a process of forming an image on the sheet 9 by discharging ink onto the sheet 9. The sheet 9 is a sheet-like image forming medium such as paper or a resin film.

[0014] Note that the inkjet recording apparatus 10 may be a facsimile apparatus, a copying machine, a multifunction machine, or the like capable of performing the printing process by an inkjet method.

[0015] As shown in FIG. 1, the inkjet recording apparatus 10 includes a sheet storage unit 1, a sheet conveyance device 2, a printing unit 3, a plurality of ink supply units 4, and a control device 8.

[0016] The sheet storage unit 1, the sheet conveyance device 2, the printing unit 3, the plurality of ink supply units 4, and the control device 8 are arranged inside the main housing 11. The inkjet recording apparatus 10 further includes an operation device 801 and a display device 802.

[0017] The sheet conveyance device 2 sends out the sheets 9 stored in the sheet storage unit 1 one by one to the conveyance path 20, and further conveys the sheets 9 along the conveyance path 20.

[0018] The sheet conveyance device 2 includes a feeding mechanism 21, a plurality of pairs of conveyance rollers 22, a belt conveyance device 23, a discharge roller pair 24, and the like. The feeding mechanism 21 sends out the sheets 9 from the sheet storage unit 1 to the conveyance path 20. The plurality of pairs of conveyance rollers 22 convey the sheets 9 along the conveyance path 20 and further convey the sheets 9 to the belt conveyance device 23.

[0019] A plurality of pairs of conveying rollers 22 may convey cut paper supplied from a roll paper supply device connected to the front stage of the inkjet recording apparatus 10 to the belt conveying device 23. The roll paper supply device feeds out a roll paper wound in a roll shape, and generates the cut paper by cutting the fed-out paper at a preset length. Further, the roll paper supply device supplies the cut paper to the inkjet recording apparatus 10. The cut paper is an example of the sheet 9.

[0020] The belt conveying device 23 is disposed below the printing unit 3. The belt conveying device 23 includes an endless conveying belt 231 and a plurality of tension rollers 232.

[0021] The plurality of tension rollers 232 rotatably support the conveying belt 231. A motor (not shown) rotates one of the plurality of tension rollers 232 to rotate the conveying belt 231. The belt conveying device 23 conveys the sheet 9 in the conveying direction D0 on the conveying belt 231 by rotating the conveying belt 231.

[0022] The direction orthogonal to the conveying direction D0 is the main scanning direction D1, and the direction along the conveying direction D0 is the sub-scanning direction D2 (see FIG. 1).

[0023] The plurality of pairs of conveying rollers 22 includes a registration roller pair 22a disposed at the front stage of the belt conveying device 23. The registration roller pair 22a is disposed on the upstream side in the conveying direction D0 with respect to the belt conveying device 23.

[0024] The sheet conveying device 2 includes a registration motor 22b that rotates the registration roller pair 22a, and a sheet detection device 220 disposed at the front stage of the registration roller pair 22a.

[0025] The resist roller pair 22a and the resist motor 22b constitute a pre-stage conveyance device 22x that conveys the sheet 9 to the belt conveyance device 23. The sheet detection device 220 detects the sheet 9 at a position upstream in the conveyance direction D0 with respect to the resist roller pair 22a in the conveyance path 20.

[0026] The pre-stage conveyance device 22x can temporarily stop the conveyance of the sheet 9 according to the detection timing of the sheet 9 by the sheet detection device 220, and then convey the sheet 9 to the belt conveyance device 23 at an arbitrary timing.

[0027] The printing unit 3 forms an image on the sheet 9 by discharging inks of a plurality of colors toward the sheet 9 conveyed by the belt conveyance device 23.

[0028] The discharge roller pair 24 is disposed downstream in the conveyance direction D0 from the belt conveyance device 23. The discharge roller pair 24 discharges the sheet 9 on which the image is formed to the outside of the main housing 11. For example, the discharge roller pair 24 sends out the sheet 9 from the main housing 11 to a discharge tray or a post-stage device disposed adjacent to the inkjet recording apparatus 10.

[0029] The plurality of ink supply units 4 supply inks of predetermined colors to the printing unit 3 respectively. For example, the colors of the inks are black, cyan, magenta, and yellow. In this case, the inkjet recording apparatus 10 includes four ink supply units 4.

[0030] [Printing unit 3] The printing unit 3 forms an image on the sheet 9 by discharging ink onto the sheet 9 conveyed by the belt conveyance device 23. The printing unit 3 includes a plurality of nozzle units 30 corresponding to a plurality of ink colors.

[0031] The printing unit 3 includes a plurality of nozzle units 30 corresponding to a plurality of ink colors. The plurality of ink supply units 4 supply ink to the plurality of nozzle units 30.

[0032] In the present embodiment, the printing unit 3 includes four nozzle units 30 corresponding to black, cyan, magenta, and yellow inks.

[0033] Each of the nozzle units 30 has an ink ejection unit 31 (see FIG. 1). The ink ejection unit 31 includes a plurality of nozzles 32 arranged to face the upper surface of the conveyance belt 231 (see FIG. 2). The plurality of nozzles 32 each form an image on the sheet 9 by ejecting ink onto the sheet 9.

[0034] Furthermore, the ink ejection unit 31 includes a plurality of piezoelectric elements 33, a plurality of pressure chambers 35, and a plurality of diaphragms 34. The plurality of piezoelectric elements 33, the plurality of pressure chambers 35, and the plurality of diaphragms 34 are each provided corresponding to the plurality of nozzles 32.

[0035] The plurality of pressure chambers 35 each communicate with the plurality of nozzles 32. The plurality of pressure chambers 35 each form a passage for the ink supplied to the plurality of nozzles 32. The ink in the plurality of pressure chambers 35 is each supplied to the plurality of nozzles 32.

[0036] The plurality of diaphragms 34 each form a part of the partition wall of the plurality of pressure chambers 35. Each of the piezoelectric elements 33 pressurizes the ink in the pressure chamber 35 via each of the diaphragms 34 when a drive signal is supplied.

[0037] The drive signal is a signal whose waveform is adjusted according to the size of the ink droplets to be ejected. The drive signal is supplied from the control device 8 to each of the piezoelectric elements 33.

[0038] That is, each of the piezoelectric elements 33 pressurizes the ink supplied to the plurality of nozzles 32 by being supplied with the drive signal from the control device 8.

[0039] The piezoelectric element 33 to which the drive signal is supplied vibrates with the energy for ejecting ink from the corresponding nozzle 32. That is, each of the piezoelectric elements 33 pressurizes the ink in the pressure chamber 35 to such an extent that the ink is ejected from the nozzle 32 when the drive signal is supplied.

[0040] The ink pressurized by the piezoelectric element 33 to which the drive signal is supplied flows from the pressure chamber 35 into the corresponding nozzle 32 and is further ejected from the nozzle 32.

[0041] That is, the plurality of piezoelectric elements 33 eject ink from the plurality of nozzles 32 by pressurizing the ink supplied to the plurality of nozzles 32. Each of the nozzle units 30 can execute the printing process by ejecting ink onto the sheet 9 conveyed on the conveyance belt 231.

[0042] Each of the nozzle units 30 further includes a unit heater 36 and a unit temperature sensor 37 (see FIG. 2). The unit heater 36 and the unit temperature sensor 37 are disposed in the ink ejection portion 31 of each of the nozzle units 30.

[0043] That is, the inkjet recording apparatus 10 includes a plurality of unit heaters 36 and a plurality of unit temperature sensors 37 corresponding to the plurality of nozzle units 30.

[0044] The unit heater 36 heats the ink ejection portion 31. The unit temperature sensor 37 detects the temperature of the ink ejection portion 31. That is, the unit temperature sensor 37 detects the temperature of the nozzle unit 30 on the nozzle unit 30. For example, the unit temperature sensor 37 is a thermistor.

[0045] The unit temperature sensor 37 is an example of an internal temperature sensor that detects the internal temperature of the inkjet recording apparatus 10.

[0046] When the temperature of the ink decreases, the viscosity of the ink increases. When the viscosity of the ink supplied to each of the nozzles 32 is high, the ejection performance of the ink from each of the nozzles 32 when each of the piezoelectric elements 33 operates deteriorates.

[0047] The unit heater 36 maintains the viscosity of the ink supplied to each of the nozzles 32 in an appropriate state by heating the ink in the ink ejection unit 31.

[0048] Before the print process is started, the unit heater 36 heats the ink in the ink ejection unit 31, thereby shortening the first print time. The first print time is the time from when the inkjet recording apparatus 10 receives a print request until the start of the print process.

[0049] The power supplied to the unit heater 36 is adjusted by feedback control based on the detected temperature of the unit temperature sensor 37.

[0050] The operation device 801 receives a human operation. For example, the operation device 801 includes one or both of a touch panel and one or more operation buttons. The display device 802 can display various information. For example, the display device 802 is a panel display device such as a liquid crystal panel unit.

[0051] [Control Device 8] The control device 8 executes various data processes and controls the devices included in the inkjet recording apparatus 10.

[0052] As shown in FIG. 3, the control device 8 includes a CPU (Central Processing Unit) 81, and peripheral devices such as a RAM (Random Access Memory) 82, a secondary storage device 83, and a signal interface 84. Further, the control device 8 includes a communication device 85 and a heater power supply circuit 86.

[0053] The CPU 81 is a processor that executes various data processing and controls by executing a computer program. The CPU 81 is an example of a processor that controls a plurality of piezoelectric elements 33 and other devices.

[0054] The RAM 82 is a volatile storage device readable by a computer. The RAM 82 primarily stores the computer program executed by the CPU 81 and the data output and referenced during the execution of various processes by the CPU 81.

[0055] The secondary storage device 83 is a non-volatile storage device readable by a computer. The secondary storage device 83 can store and update the computer program and various data. For example, one or both of a flash memory or a hard disk drive are adopted as the secondary storage device 83.

[0056] The signal interface 84 converts the signals output by various sensors into digital data and transmits the converted digital data to the CPU 81. Further, the signal interface 84 converts the control commands output by the CPU 81 into control signals and transmits the control signals to the devices to be controlled.

[0057] The communication device 85 can communicate with a host device (not shown) and other devices. The host device is an information processing device such as a personal computer or a smartphone operated by a user.

[0058] For example, the CPU 81 receives a print job from the host device through the communication device 85. The printing unit 3 forms the image specified by the print job on the sheet 9.

[0059] The heater power supply circuit 86 supplies a unit heater 36 with an amount of power corresponding to the input power command.

[0060] The CPU 81 includes a plurality of processing modules realized by executing the computer program. The plurality of processing modules include a main control unit 8a, a conveyance control unit 8b, a printing control unit 8c, a temperature control unit 8d, and the like.

[0061] The main control unit 8a executes controls such as starting various processes in response to a processing request input through the operation device 801 or the communication device 85, and controls of the display device 802. The processing request includes a print request for requesting execution of the print process.

[0062] The conveyance control unit 8b controls the sheet conveyance device 2. That is, the conveyance control unit 8b controls the supply of the sheet 9 by the feeding mechanism 21, the conveyance of the sheet 9 by the plurality of pairs of conveyance rollers 22 and the belt conveyance device 23, and the discharge of the sheet 9 by the discharge roller pair 24.

[0063] The printing control unit 8c causes the printing unit 3 to execute the printing process in synchronization with the conveyance of the sheet 9 by the sheet conveyance device 2. The printing control unit 8c causes the printing unit 3 to execute the printing process by controlling a plurality of piezoelectric elements 33.

[0064] The temperature control unit 8d controls the power supplied to the unit heater 36 by outputting the signal of the power command to the heater power supply circuit 86 through the signal interface 84.

[0065] Also, each nozzle unit 30 includes a drive circuit 300 that supplies the drive signal to each piezoelectric element 33 (see FIG. 1).

[0066] The drive circuit 300 outputs the drive signal to each piezoelectric element 33 according to the input pressurization command signal. Each nozzle unit 30 forms an image on the sheet 9 with the ink ejected from the plurality of nozzles 32 by supplying the drive signal to the plurality of piezoelectric elements 33 from the drive circuit 300.

[0067] The print control unit 8c outputs a signal of the pressurization command corresponding to the size of the ink droplets to be ejected from each of the nozzles 32 to the drive circuit 300 through the signal interface 84. The print control unit 8c controls each of the piezoelectric elements 33 through the drive circuit 300.

[0068] By the way, in the period from when the print request occurs to when the print process ends, it is required to appropriately maintain the viscosity of the ink supplied to each of the nozzles 32 and prevent clogging of each of the nozzles 32.

[0069] The print control unit 8c executes flushing control (see FIG. 5). The flushing control includes processing for preventing clogging of each of the nozzles 32 in the period from when the print request occurs to when the print process ends.

[0070] A plurality of openings 233 each including one or more through holes 234 are formed at intervals in the circumferential direction on the conveyor belt 231 of the belt conveyor device 23 (see FIG. 4).

[0071] When the plurality of nozzles 32 eject ink when each of the openings 233 passes through a position facing the ink ejection part 31 of each of the nozzle units 30, the ejected ink passes through each of the openings 233.

[0072] The inkjet recording apparatus 10 further includes an ink recovery mechanism 5 that recovers the ink that has passed through each of the openings 233 of the conveyor belt 231 (see FIG. 1).

[0073] For example, the ink recovery mechanism 5 includes an ink tray, a pump, and an ink tank. The ink tray receives the ink that has passed through each of the openings 233. The pump conveys the ink that has fallen into the ink tray by sucking it through a tube. The ink tank stores the ink conveyed by the pump.

[0074] The inkjet recording apparatus 10 further includes a belt position sensor 6 used for detecting the rotational position of the conveyance belt 231. For example, the belt position sensor 6 is a photosensor or a microswitch that detects a detected portion 230 formed on the conveyance belt 231. The photosensor is a reflective or transmissive sensor.

[0075] When the belt position sensor 6 is the photosensor, the detected portion 230 is a through hole or a mirror surface portion formed on the conveyance belt 231. When the belt position sensor 6 is the microswitch, the detected portion 230 is a protrusion formed on the conveyance belt 231.

[0076] The conveyance control unit 8b measures a belt rotation time, which is the rotation time of the conveyance belt 231, starting from the time when the detected portion 230 is detected by the belt position sensor 6.

[0077] Furthermore, the conveyance control unit 8b specifies the proximal end passing timing according to the belt rotation time.

[0078] The proximal end passing timing is the timing when each opening 233 passes through the proximal end of the area on the conveyance belt 231 that conveys the sheet 9. The proximal end is the starting position of the conveyance of the sheet 9 on the conveyance belt 231.

[0079] The conveyance control unit 8b controls the loading of the sheet 9 into the belt conveyance device 23 so that the leading end of the sheet 9 reaches the proximal end on the conveyance belt 231 following the proximal end passing timing. The print control unit 8b controls the loading of the sheet 9 into the belt conveyance device 23 by controlling the preceding conveyance device 22x.

[0080] Also, the print control unit 8c specifies the nozzle passing timing according to the belt rotation time. The nozzle passing timing is the timing when each opening 233 passes through the position facing the ink ejection portion 31 of each nozzle unit 30.

[0081] Here, one or more of the plurality of nozzle units 30 that face any of the plurality of openings 233 at the nozzle passing timing are referred to as target nozzle units. The print control unit 8c causes the target nozzle unit to execute a first flushing process at the nozzle passing timing.

[0082] The first flushing process is a process of discharging ink toward each of the openings 233 in the region where the sheet 9 does not exist on the conveyance belt 231. The first flushing process is, for example, referred to as a line flushing process or the like.

[0083] Furthermore, the print control unit 8c can also cause each of the nozzle units 30 to execute a second flushing process when the sheet 9 is being conveyed by the belt conveyance device 23.

[0084] The second flushing process is a process of discharging ink to a non-drawing area that is not drawn on the sheet 9 in parallel with the printing process on the sheet 9. The second flushing process is, for example, referred to as an in-sheet flushing process or an in-page flushing process.

[0085] The print control unit 8c causes each of the nozzle units 30 to execute the second flushing process so that a plurality of ink dots are formed dispersed over a wide area of the sheet 9. As a result, the plurality of ink dots are formed on the sheet 9 so as not to be conspicuous as much as possible.

[0086] By executing the first flushing process or the second flushing process, highly viscous ink is discharged from the plurality of nozzles 32 of each of the nozzle units 30, and the ink is newly filled. As a result, the viscosity of the ink in the plurality of nozzles 32 is appropriately maintained.

[0087] Incidentally, the inkjet recording apparatus 10 may include a rotary encoder that detects the rotational position of one of the plurality of tension rollers 232. In this case, the conveyance control unit 8b counts the number of encoder pulses, which is the number of output pulses of the rotary encoder, starting from the point in time when the detected unit 230 is detected by the belt position sensor 6.

[0088] The conveyance control unit 8b can specify the base end passage timing according to the number of encoder pulses. Similarly, the print control unit 8c can specify the nozzle passage timing according to the number of encoder pulses.

[0089] [Flushing Control] Hereinafter, an example of the procedure of the flushing control will be described with reference to the flowchart shown in FIG. 5.

[0090] When the main control unit 8a receives the print request through the operation device 801 or the communication device 85, it causes the print control unit 8c to execute the flushing control.

[0091] The flushing control is an example of a process for realizing an inkjet control method for controlling the inkjet recording apparatus 10. The CPU 81 including the print control unit 8c is an example of a processor for realizing the inkjet control method.

[0092] In the following description, S1, S2,... are symbols for identifying each of a plurality of steps in the flushing control. In the flushing control, first, the process of step S1 is executed.

[0093] <Step S1> In step S1, the print control unit 8c acquires sheet length information representing the length of the target sheet 9 in the conveyance direction D0 of the target sheet to be conveyed by the belt conveyance device 23.

[0094] For example, the print control unit 8c acquires the sheet information included in the print request as the sheet length information. The sheet information includes sheet size information representing the vertical size and the horizontal size of the target sheet, and orientation information representing the orientation of the target sheet. The size information may be information representing the standard size of the sheet 9.

[0095] In the above case, the print control unit 8c specifies, as the sheet length information, one of the information on the vertical size and the information on the horizontal size of the target sheet according to the orientation information.

[0096] After executing the process of step S1, the print control unit 8c executes the process of step S2.

[0097] <Step S2> In step S2, the print control unit 8c acquires the unit temperature, which is the detected temperature of the unit temperature sensor 37 of each nozzle unit 30.

[0098] After executing the process of step S2, the print control unit 8c executes the process of step S3.

[0099] <Step S3> In step S3, the print control unit 8c corrects a preset reference length based on the unit temperature.

[0100] The reference length is a length to be compared with the length of the sheet length information. For example, the reference length before correction is approximately the interval between a plurality of openings 233 in the conveyance belt 231. FIG. 6 shows a state in which the sheet 9 having the reference length before correction is conveyed by the belt conveyance device 23. FIG. 7 shows a state in which a sheet 9 longer than the reference length before correction is conveyed by the belt conveyance device 23.

[0101] When the sheet 9 having the reference length before correction is conveyed under the condition that the unit temperature is the reference temperature, the viscosity of the ink in the plurality of nozzles 32 is appropriately maintained only by the first flushing process.

[0102] When the unit temperature is higher than the reference temperature range with the reference temperature as a reference, the print control unit 8c corrects the reference length to be longer. On the other hand, when the unit temperature is lower than the reference temperature range, the print control unit 8c sets the reference length to 0.

[0103] After executing the process of step S3, the print control unit 8c executes the process of step S4.

[0104] Note that the inkjet recording apparatus 10 may include a peripheral temperature sensor that detects the temperature around a plurality of nozzle units 30. In this case, the detected temperature of the peripheral temperature sensor may be used for correcting the reference length instead of the unit temperature. The peripheral temperature sensor is an example of the internal temperature sensor.

[0105] <Step S4> In step S4, the print control unit 8c compares the length of the sheet length information with the reference length. The print control unit 8c selects the following process according to whether the length of the sheet length information is longer than the reference length.

[0106] When the length of the sheet length information is not longer than the reference length, the print control unit 8c executes the process of step S5. On the other hand, when the length of the sheet length information is longer than the reference length, the print control unit 8c executes the process of step S6.

[0107] <Step S5> In step S5, the print control unit 8c selects the first flushing process as the target flushing process among the first flushing process and the second flushing process.

[0108] As described later, the target flushing process is a process performed when the target sheet is conveyed. After executing the process of step S5, the print control unit 8c executes the process of step S8.

[0109] <Step S6> In step S6, the print control unit 8c selects both the first flushing process and the second flushing process as the target flushing process.

[0110] After executing the process of step S6, the print control unit 8c executes the process of step S7.

[0111] Note that in step S6, it is also conceivable that only the second flushing process is selected as the target flushing process.

[0112] That is, in steps S4 to S6, the print control unit 8c selects one or both of the first flushing process and the second flushing process as the target flushing process according to the sheet length information.

[0113] <Step S7> In step S7, the print control unit 8c sets a target area to be subjected to the second flushing process in the entire area of the conveyance direction D0 of the target sheet according to the sheet length information.

[0114] The target area is a series of areas extending from the rear end to the front end side of the target sheet. The target area is a part or all of the area of the target sheet.

[0115] For example, the print control unit 8c sets a longer target area in the conveyance direction D0 when the length of the sheet length information is long than when it is short.

[0116] The process of step S7 is executed when the target flushing process including the second flushing process is selected. After executing the process of step S7, the print control unit 8c executes the process of step S8.

[0117] <Step S8> In step S8, the print control unit 8c causes each nozzle unit 30 to execute the target flushing process selected in step S5 or step S6.

[0118] The print control unit 8c causes each nozzle unit 30 to execute the target flushing process in parallel with the print process corresponding to the print request.

[0119] When the target flushing process includes the first flushing process, the print control unit 8c causes each nozzle unit 30 to execute the first flushing process directed to at least one of the plurality of openings 233 that is closest to the tip of the target sheet.

[0120] When the target flushing process includes the second flushing process, the print control unit 8c causes each nozzle unit 30 to execute the second flushing process directed to the target area of the target sheet.

[0121] After executing the process of step S8, the print control unit 8c executes the process of step S9.

[0122] <Step S9> In step S9, the print control unit 8c selects the next process according to whether the print process corresponding to the print request has ended.

[0123] When the print process corresponding to the print request has ended, the print control unit 8c executes the processes after step S1 for the next target sheet. On the other hand, when the print process corresponding to the print request has ended, the print control unit 8c ends the flushing control.

[0124] By executing the flushing control, the viscosity of the ink supplied to each nozzle 32 of each nozzle unit 30 is properly maintained during the period from when the print request occurs until the print process ends. As a result, clogging of each nozzle 32 is prevented.

[0125] [First Modification Example] Next, a first modification example of the inkjet recording apparatus 10 will be described.

[0126] In this modification example, the inkjet recording apparatus 10 includes a humidity sensor that detects the humidity inside the main housing 11. The humidity sensor is an example of an internal humidity sensor that detects the internal humidity of the inkjet recording apparatus 10.

[0127] In the print control unit 8c in this modification example, in the step S2 of the flushing control, the ambient humidity, which is the detected humidity of the humidity sensor, is acquired.

[0128] Furthermore, in the step S3 of the flushing control, the print control unit 8c in this modification example corrects the reference length according to the ambient humidity.

[0129] For example, in this modification example, when the ambient humidity is higher than a reference humidity range with the reference humidity as a reference, the print control unit 8c corrects the reference length to be longer. On the other hand, when the ambient humidity is lower than the reference humidity range, the print control unit 8c sets the reference length to 0.

[0130] In this modification example, the print control unit 8c may perform both the correction based on the unit temperature and the correction based on the ambient humidity with respect to the correction of the reference length. Also, the print control unit 8c may perform only one of the correction based on the unit temperature and the correction based on the ambient humidity with respect to the correction of the reference length.

[0131] [Second Modification Example] Next, a second modification example of the inkjet recording apparatus 10 will be described with reference to the flowchart shown in FIG. 8.

[0132] In this modification example, the main control unit 8a can set one of two candidate modes as the operation mode according to the mode setting information input through the operation device 801 or the communication device 85.

[0133] The two candidate modes include a first operation mode in which one or both of the first flushing process and the second flushing process are automatically selected as the target flushing process, and a second operation mode in which only the first flushing process is preferentially selected as the target flushing.

[0134] In this modification, when the first operation mode is set as the operation mode, the print control unit 8c executes the flushing control according to the procedure shown in FIG. 5.

[0135] On the other hand, when the second operation mode is set as the operation mode, the print control unit 8c sets a preset upper limit length as the reference length, and then executes the flushing control according to the procedure shown in FIG. 8.

[0136] The print control unit 8c in this application example executes the flushing control according to a procedure in which steps S6a and S6b are added to the procedure shown in FIG. 5.

[0137] The processes of steps S1 to S5 shown in FIG. 8 are the same as the processes of steps S1 to S5 shown in FIG. 5. Hereinafter, the differences between the procedure shown in FIG. 5 and the procedure shown in FIG. 8 in the procedure shown in FIG. 8 will be described.

[0138] <Step S4> In step S4, when the length of the sheet length information is longer than the reference length, the print control unit 8c executes the process of step S6a.

[0139] <Step S6a> In step S6a, the print control unit 8c determines the input status of the instruction corresponding to the second operation mode.

[0140] It is input by the process of step S6b described later, and represents permission or non - permission for execution of the second flushing process.

[0141] When the instruction has not been input yet, the print control unit 8c executes the process of step S6b.

[0142] When the target sheet is the first sheet 9 in the print process corresponding to the print request, the print control unit 8c executes the process of step S6b before starting the print process.

[0143] On the other hand, when the target sheet is the second and subsequent sheets 9 in the print process corresponding to the print request, the print control unit 8c interrupts the print process and then executes the process of step S6b.

[0144] Also, when the instruction indicating permission is input, the print control unit 8c executes the process of step S6. In this case, the print control unit 8c executes the same process as when the first operation mode is set.

[0145] On the other hand, when the instruction indicating non - permission is input, the print control unit 8c executes the process of step S5. As described above, in step S5, the first flushing process is selected as the target flushing process.

[0146] That is, when the instruction indicating non - permission is input, the print control unit 8c selects only the first flushing process as the target flushing process regardless of the content of the sheet length information.

[0147] <Step S6b> In step S6b, the print control unit 8c executes the process of inputting the instruction.

[0148] In step S6b, the print control unit 8c notifies a predetermined message through the display device 802 or the communication device 85. For example, the message includes information indicating that the length of the target sheet is a length that requires the second flushing process. Further, the message may include information indicating that the non - permission of the second flushing process may have an adverse effect on the output image quality.

[0149] Furthermore, in step S6b, the print control unit 8c inputs information on either the permission or the non - permission regarding the second flushing process through the operation device 801 or the communication device 85.

[0150] After executing the process of step S6b, the print control unit 8c executes the processes after step S6a again.

[0151] By adopting this application example, the flushing control reflecting the user's intention is executed. Note that this application example may be applied to the first application example.

[0152] [Supplementary Note of the Invention] Hereinafter, a summary of the invention extracted from the above - described embodiments will be appended. Note that each configuration and each processing function described in the following supplementary note can be arbitrarily combined by making selections.

[0153] [Supplementary Note 1] An ink - jet control method for controlling an ink - jet recording apparatus, the apparatus comprising: a belt conveyor having an endless conveyor belt formed with a plurality of openings each consisting of one or more through - holes at intervals in the circumferential direction, and configured to convey a sheet on the conveyor belt by rotating the conveyor belt; and a nozzle unit having a plurality of nozzles arranged opposite to the upper surface of the conveyor belt and a plurality of piezoelectric elements configured to eject ink from the plurality of nozzles by pressurizing the ink supplied to the plurality of nozzles, and configured to execute a printing process of forming an image on the sheet by ejecting ink onto the sheet conveyed on the conveyor belt. ​The processor obtains sheet length information representing the length of the target sheet in the conveyance direction to be conveyed by the belt conveyance device. The processor selects, as a target flushing process, one or both of a first flushing process of discharging ink toward each of the plurality of openings in the area where the sheet does not exist on the conveyance belt and a second flushing process of discharging ink to a non-drawing area that is not drawn on the target sheet, in parallel with the printing process on the target sheet, according to the sheet length information, and causes the nozzle unit to execute the target flushing process. An inkjet control method including:

[0154] <Appendix 2> When the inkjet recording device includes one or both of an internal temperature sensor that detects the internal temperature and an internal humidity sensor that detects the internal humidity, The processor corrects a reference length according to a detection result of one or both of the internal temperature sensor and the internal humidity sensor, and selects the target flushing process by comparing the length represented by the sheet length information with the corrected reference length. The inkjet control method according to Appendix 1.

[0155] <Appendix 3> When the inkjet recording device includes a heater that heats the nozzle unit and a unit temperature sensor that detects the temperature of the nozzle unit, The processor corrects the reference length using the detected temperature of the unit temperature sensor as the detected temperature of the internal temperature sensor. The inkjet control method according to Appendix 2.

[0156] <Appendix 4> When the processor selects the target flushing process including the second flushing process, the processor sets a target area for the second flushing process in the entire area of the target sheet in the conveyance direction according to the sheet length information. The inkjet control method according to any one of Appendix 1 to Appendix 3.

[0157] <Appendix 5> An endless conveyor belt having a plurality of openings each formed of one or more through holes and spaced apart in the circumferential direction, and a belt conveyor device for conveying a sheet on the conveyor belt by rotating the conveyor belt; A nozzle unit having a plurality of nozzles arranged opposite to the upper surface of the conveyor belt and a plurality of piezoelectric elements for discharging ink from the plurality of nozzles by pressurizing the ink supplied to the plurality of nozzles, and capable of performing a printing process of forming an image on the sheet by discharging ink onto the sheet conveyed on the conveyor belt; An inkjet recording apparatus comprising a processor for realizing the inkjet control method according to any one of Appendices 1 to 4.

Explanation of Signs

[0158] 1: Sheet storage unit 2: Sheet conveyor device 3: Printing unit 4: Ink supply unit 5: Ink recovery mechanism 6: Belt position sensor 8: Control device 10: Inkjet recording apparatus 23: Belt conveyor device 30: Nozzle unit 31: Ink discharge unit 32: Nozzle 33: Piezoelectric element 36: Unit heater 37: Unit temperature sensor 230: Detected part 231: Conveyor belt 233: Opening 234: Through hole

Claims

1. A belt conveyor apparatus having an endless conveyor belt formed with a plurality of openings each consisting of one or more through-holes spaced apart in the circumferential direction, and conveying a sheet on the conveyor belt by rotating the conveyor belt; A nozzle unit having a plurality of nozzles disposed opposite to the upper surface of the conveyor belt and a plurality of piezoelectric elements for discharging ink from the plurality of nozzles by pressurizing the ink supplied to the plurality of nozzles, and capable of executing a printing process of forming an image on the sheet by discharging ink onto the sheet conveyed on the conveyor belt, and an inkjet control method for controlling an inkjet recording apparatus including: A processor obtains sheet length information representing the length in the conveying direction of a target sheet to be conveyed by the belt conveyor apparatus; The processor selects, as a target flushing process, one or both of a first flushing process of discharging ink toward each of the plurality of openings in a region of the conveyor belt where the sheet does not exist and a second flushing process of discharging ink onto a non-drawing region not drawn on the target sheet in parallel with the printing process on the target sheet according to the sheet length information, and causes the nozzle unit to execute the target flushing process. An inkjet control method including:

2. When the inkjet recording apparatus includes one or both of an internal temperature sensor for detecting the internal temperature and an internal humidity sensor for detecting the internal humidity, The processor corrects a reference length according to a detection result of one or both of the internal temperature sensor and the internal humidity sensor, and selects the target flushing process by comparing the length represented by the sheet length information with the corrected reference length. The inkjet control method according to claim 1.

3. When the inkjet recording apparatus includes a heater for heating the nozzle unit and a unit temperature sensor for detecting the temperature of the nozzle unit, The processor corrects the reference length using the detected temperature of the unit temperature sensor as the detected temperature of the internal temperature sensor. The inkjet control method according to claim 2.

4. When the processor selects the target flushing process including the second flushing process, the processor sets a target area to be subjected to the second flushing process among all areas in the conveyance direction of the target sheet according to the sheet length information. The inkjet control method according to any one of claims 1 to 3.

5. A belt conveyance device having an endless conveyance belt in which a plurality of openings each formed of one or more through holes are formed at intervals in the circumferential direction, and conveying a sheet on the conveyance belt by rotating the conveyance belt; A nozzle unit having a plurality of nozzles disposed to face the upper surface of the conveyance belt and a plurality of piezoelectric elements that eject ink from the plurality of nozzles by pressurizing the ink supplied to the plurality of nozzles, and forming an image on the sheet by ejecting ink onto the sheet conveyed on the conveyance belt. An inkjet recording apparatus comprising: a processor that realizes the inkjet control method according to any one of claims 1 to 3. An inkjet recording apparatus comprising: a processor that realizes the inkjet control method according to any one of claims 1 to 3.

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