JP5287054B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus.

  As an ink jet recording apparatus, an apparatus capable of cleaning an ink jet head as required is known. For example, Japanese Patent Application Laid-Open No. 2004-228867 allows an ink other than ink to be clogged with a nozzle (corresponding to a cleaning liquid) that is difficult to cause clogging, and introduces another liquid into the head when not printing. A recording device is disclosed. In this ink jet recording apparatus, the ink jet head is capped to introduce another liquid, and the inside of the cap can be depressurized or pressurized to create a forced flow of the other liquid in the ink jet head. In addition, dirt on the flow path can be washed. Further, as another liquid, a cleaning liquid in which only a dye is removed from the ink is preferable as a liquid that is as close to the ink as possible and does not include a substance that causes clogging.

Patent Document 2 describes that a colorant such as a water-soluble dye is added for the purpose of obtaining visibility of the ink flow path cleaning liquid.
Japanese Patent No. 3597346 JP 2007-313716 A

  As described above, it is known to use a cleaning liquid in order to prevent and eliminate clogging of the nozzles of the inkjet head. However, when a printing operation is performed by the ink jet recording apparatus after the cleaning liquid is introduced into the ink jet head, it is necessary to introduce the ink into the ink jet head and replace it with the cleaning liquid. This operation of replacing the cleaning liquid with ink (ink replacement) is not preferable for quick start of printing of the ink jet recording apparatus and ink saving. As the head becomes larger like a line head and the number of nozzles on the head increases, the replacement operation with ink takes time, and the amount of replacement ink often increases. In particular, if the frequency of introducing the cleaning liquid is increased in order to increase the reliability of the nozzles, the frequency of ink replacement is increased, which hinders the rapid start of printing by the inkjet recording apparatus and the saving of ink.

  In view of the above problems, the object of the present invention is to minimize or eliminate the replacement of the cleaning liquid in the ink jet head with ink even when the cleaning liquid is introduced into the ink jet head. It is an object of the present invention to provide an ink jet recording apparatus capable of performing printing while suppressing the printing to a minimum.

  The present invention provides an inkjet head that forms an image by ejecting ink onto a recording medium, an ink supply unit that supplies ink to the inkjet head, a cleaning liquid supply unit that supplies cleaning liquid to the inkjet head, and an inkjet head Ink replacement determination means for determining whether or not an ink replacement operation for replacing the inside of the inkjet head after cleaning with ink is necessary according to the supply amount of cleaning liquid supplied at the time of cleaning, and the ink replacement operation by the ink replacement determination means Before printing, the ink supply unit is controlled to perform the ink replacement operation.When the ink replacement determination unit determines that the ink replacement is unnecessary, the printing unit Ink replacement control means for controlling not to perform the ink replacement operation An ink jet recording apparatus which.

  In a preferred aspect of the present invention, the cleaning liquid includes a colorant.

  In a preferred aspect of the present invention, the inkjet recording apparatus further includes a cleaning liquid amount setting unit configured to set a cleaning liquid amount supplied by the cleaning liquid supply unit.

  Preferably, the cleaning of the inkjet head by the cleaning liquid supply means can include a plurality of cleaning operations, and the cleaning liquid for calculating a total cleaning liquid supply amount by integrating the cleaning liquid amount for each cleaning operation. The inkjet recording apparatus further comprising supply amount integration means.

  In a preferred aspect of the present invention, the cleaning liquid amount setting unit sets the cleaning liquid amount based on a pause time of the image formation.

  In a preferred aspect of the present invention, the ink replacement control unit sets a replacement ink amount in ink replacement based on a cleaning liquid supply amount supplied from the cleaning liquid supply unit to the inkjet head. is there.

  In a preferred aspect of the present invention, the inkjet head is a line head type inkjet head.

  According to the present invention, there is provided an ink jet recording apparatus capable of performing printing without replacing or minimizing ink when performing a printing operation even when a cleaning liquid is introduced into the ink jet head. Can be provided.

(Specific Embodiment of Inkjet Recording Apparatus of the Present Invention)
A specific embodiment of the ink jet recording apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an aspect of the ink jet recording apparatus of the present invention. As shown in FIG. 1, this ink jet recording apparatus is a line type ink jet recording apparatus. On the apparatus main body 1, an ink ejection unit 2 that performs printing by ejecting ink dots on a recording paper and a recording paper are held. A recording paper supply unit 3 that feeds the recording paper, and a recording paper that conveys the recording paper from the recording paper supply unit 3 to a position printed by the ink ejection unit 2 and conveys the printed recording paper to the recording paper discharge unit 5 A transport unit 4 and a recording paper discharge unit 5 that discharges and holds the printed recording paper are provided. Further, the ink jet recording apparatus includes an ink jet head maintaining unit 6 that cleans and maintains a clean ink jet head, and an ink jet recording apparatus control unit 7 that controls the entire apparatus main body 1 including the ink discharge unit 2. I have. Needless to say, the present invention can also be applied to a serial type ink jet recording apparatus.

  The ink discharge unit 2 includes an inkjet head 21, ink supply means including an ink tank 22, an ink supply line 27, and the like, and cleaning liquid supply means including a cleaning liquid tank 23, a cleaning liquid supply line 28, and the like. In a normal printing operation, the ink ejection unit 2 ejects ink supplied from the ink tank 22 from the nozzles of the inkjet head 21 in accordance with a dot pattern signal from a control unit 72 (described later), and prints an image on a recording sheet. Forming (printing). The cleaning operation and the ink replacement operation of the ink discharge unit 2 will be described together with the ink jet recording apparatus control unit 7.

  The recording sheets held in the recording sheet supply tray 31 of the recording sheet supply unit 3 are pulled out one by one by the drawing roller 32 and are supplied to the recording sheet conveying unit 4 by the supply roller 33.

  The recording paper supplied to the recording paper transport unit 4 is transported onto the transport belt 41 while the upper surface is held by the auxiliary roller 45. The conveyance belt 41 conveys the recording paper in the sub-scanning direction (in the direction from right to left in FIG. 1) in synchronization with the ink ejection operation of the ejection head 21. The conveyor belt 41 is stretched between a driving roller 42 and a driven roller 43, and the rotation operation of the driving roller 42 is controlled by the control unit 72.

  Ink is ejected from the nozzles of the inkjet head 21 of the ink ejection section 2 onto the recording paper on the transport belt 41, and printing with ink is executed. The recording sheet is conveyed while being printed on the conveying belt 41, passes between the driving roller 42 and the auxiliary roller 44, and is conveyed to the recording sheet discharge unit 5. In the recording paper discharge unit 5, the recording paper is discharged onto the recording paper discharge tray 51 through the discharge roller 53 and the auxiliary roller 52.

  The inkjet head maintaining unit 6 has a function of preventing the nozzles from being dried during the printing pause of the inkjet head 21, cleaning dirt and clogging of the inkjet head 21, and maintaining the function of the inkjet head 21 normally. The ink-jet head 21 moves to the upper part of the nozzle cap 62 during printing suspension, the nozzle cap 62 covers the nozzles at the lower part of the ink-jet head 21, and the ink-jet head maintaining unit 6 has a suction pump (not shown) in the ink-jet head 21. Ink is sucked from the nozzles and discharged to the waste liquid tank 61, or drying is prevented. The suction pump is also a component of the ink supply means and the cleaning liquid supply means of the ink discharge unit 2 (details will be described later).

  The ink jet recording apparatus control unit 7 includes a display operation panel 71 and a control unit 72 having a storage device (ROM, RAM) and the like centering on a CPU. The display operation panel 71 serves as both a display panel for notifying the operator of the operation status of the ink jet recording apparatus and an operation panel for the operator to operate. The control unit 72 includes a print control unit that controls the printing operation of the apparatus main body 1 and an inkjet head cleaning / ink replacement control unit (described later) of the ink discharge unit 2. As will be described in detail later, the inkjet head cleaning / ink replacement control unit functionally includes an ink replacement determination unit, an ink supply control unit, a cleaning liquid amount setting unit, a cleaning liquid supply amount calculation unit, and the like.

  The ink replacement determination means determines whether the ink replacement is performed in accordance with the supply amount of the cleaning liquid supplied when the inkjet head 21 is cleaned when printing is started after the inkjet head 21 is cleaned in the inkjet head maintaining unit 6 or the like during the suspension of printing. Has a function of determining whether or not replacement is required. When the ink replacement determination unit determines that the ink replacement is necessary, the ink replacement control unit supplies ink to the inkjet head 21 from the ink supply unit, whereby the cleaning liquid in the inkjet head 21 is replaced with ink. .

  The ink supply means of the ink discharge unit 2 supplies ink to the inkjet head 21 whose nozzles are covered by the inkjet head maintaining unit 6, and before the image forming operation (printing) is started, the cleaning liquid in the inkjet head 21 is removed. Replace with ink. In the ink replacement from the ink supply means, the cleaning liquid is sucked from the ink-jet head 21 through the nozzle cap by the suction pump of the ink-jet head maintaining unit 6, thereby sucking and supplying the ink into the ink-jet head. In this case, the ink suction pump included in the inkjet head maintaining unit 6 is also functionally part of the ink supply means. Note that the configuration of the ink supply unit is not limited to this, and for example, ink may be press-fitted into the inkjet head 21 by a pump or the like from the ink discharge unit 2 side.

  When the ink replacement is completed, the ink-jet head 21 can be separated from the ink-jet head maintaining unit 6 and moved to the image forming position to start printing. When the ink replacement determination unit determines that ink replacement is not necessary, the inkjet head 21 can immediately move to the image forming position and start printing.

  In the inkjet recording apparatus 1 of the present embodiment, the cleaning liquid contains a colorant. As will be described later, in the ink jet recording apparatus 1 of the present embodiment, the interior of the ink jet head 21 may not be replaced with ink after cleaning. However, by including a colorant in the cleaning liquid, it is possible to form an image having a density close to that of the ink even with a mixed liquid of the cleaning liquid and the ink. For this reason, it is preferable that the colorant contained in the cleaning liquid has the same color and brightness as the ink. Further, by including a colorant in the cleaning liquid, as will be described in detail later, it becomes easy for the operator to check the test printed dots by performing test printing after cleaning. But you may use the washing | cleaning liquid which does not contain a coloring agent.

  As the cleaning liquid, conventionally known cleaning liquids, retentive liquids, and the like may be used. When the colorant is included as the cleaning liquid, an ink pigment or dye can be used as the colorant. In this case, from the viewpoint of maintaining the apparatus, the pigment / dye concentration is preferably lower than that of normal ink. That is, as the cleaning liquid, it is preferable to use a liquid obtained by removing or reducing a pigment or a dye from the ink used in the ink jet recording apparatus. Specific examples of the cleaning liquid include an aqueous solution containing a polyhydric alcohol such as glycerin or 1,3 butanediol, an acetylenic diol nonionic surfactant, and a dye used in the ink.

(Inkjet head cleaning operation)
Since the ink discharge unit 2 of the ink jet recording apparatus of the present invention exhibits a special function when shifting from a printing pause to the next printing operation, this point will be described in detail with reference to FIGS. . FIG. 2 is a detailed view of the ink discharge unit 2 in the ink jet recording apparatus shown in FIG. In this embodiment, the ink ejection unit 2 includes four inkjet heads 21a, 21b, 21c, and 21d that can eject four colors of ink separately. The inkjet heads 21a, 21b, 21c, and 21d (these are collectively referred to as the inkjet head 21) include nozzles 29a, 29b, 29c, and 29d, respectively. Each of the nozzles 29a, 29b, 29c, and 29d (these are collectively referred to as the nozzle 29) has a plurality (in some cases, several thousand) of nozzle holes.

  During a normal printing operation, the inkjet head 21 is in a position facing the conveyor belt 41 as shown in FIG. 1, and printing is performed by ejecting ink onto the printing paper conveyed on the conveyor belt 41. The movement of the conveyor belt 41 and the timing of ink ejection from the inkjet head 21 are controlled by the print control unit of the control unit 72. The ink jet heads 21a, 21b, 21c, and 21d are connected to ink tanks 22a, 22b, 22c, and 22d (these are referred to as ink supply lines 27) through ink supply lines 27a, 27b, 27c, and 27d (these are collectively referred to as ink supply lines 27). Are connected to the ink tank 22). During the printing operation, the ink supply valves 24a, 24b, 24c, 24d (these are collectively referred to as the ink supply valve 24) may be opened. In this embodiment, the ink tank 22, the ink supply line 27, the ink supply valve 24, and the suction pump of the above-described ink jet head maintaining unit 6 constitute an ink supply means.

  The inkjet heads 21a, 21b, 21c, and 21d are provided with four cleaning liquid tanks 23a, 23b, 23c, and 23d (via the cleaning liquid supply lines 28a, 28b, 28c, and 28d (collectively referred to as the cleaning liquid supply line 28)). These are collectively connected to the cleaning liquid tank 23). In each of the cleaning liquid tanks 23, cleaning agents containing colorants corresponding to four colors of ink are stored. For example, the cleaning liquid tank 23a connected to the inkjet head 21 to which black ink is supplied contains cleaning liquid containing a black colorant. Then, as described above, the cleaning liquid is supplied to the inkjet head 21 by sucking the cleaning liquid from the inkjet head 21 through the nozzle cap by the suction pump of the inkjet head maintaining unit 6. During the printing operation, the cleaning liquid supply valves 25 a, 25 b, 25 c, and 25 d (these are collectively referred to as the cleaning liquid supply valve 25) are closed, and the cleaning liquid in the cleaning liquid tank 23 does not flow into the inkjet head 21. In this embodiment, the cleaning liquid tank 23, the cleaning liquid supply line 28, and the ink supply valve 24 constitute cleaning liquid supply means.

  When the printing operation is completed and the printing is suspended, the inkjet head 21 moves onto the ink head maintaining unit 6 according to a command from the control unit 72. The nozzle face located below the inkjet head 21 is covered with the nozzle cap 62. At this time, the nozzle 29 may be covered by a single nozzle cap 62 as a whole, but is separately provided for each of the nozzles 29a, 29b, 29c, and 29d arranged in the individual inkjet heads 21a, 21b, 21c, and 21d. The nozzle cap 62 is preferably covered.

  The ink jet head 21 covered with the nozzle cap 62 is cleaned inside the ink jet head 21 including the nozzles 29 by an empty ink discharge operation or a suction operation by a suction pump included in the ink head maintaining unit 6. . In this cleaning, all the ink supply valves 24 in the ink supply line 27 are closed, all the cleaning liquid supply valves 25 in the cleaning liquid supply line 28 are opened, and the cleaning liquid flows into the inkjet head 21 instead of ink. It may be.

  In the cleaning of the inkjet head 21, as described above, the ink supply valve 24 is closed and the cleaning liquid supply valve 25 is opened, and the suction force of the pump provided in the ink head maintaining unit 6 may be used. The cleaning liquid supply line 28 a may be provided with a cleaning liquid supply pump, which may be driven to forcibly introduce the cleaning liquid into the inkjet head 21. In these cleaning steps, the cleaning liquid is preferably used in the minimum necessary for keeping the inkjet head 21 clean, and the control operation that enables this is described below.

(Operation of inkjet head cleaning and ink replacement control system)
In the ink jet recording apparatus 1 of the present embodiment, the ink jet head 21 is in a printing pause state, and the ink jet head 21 is cleaned with the cleaning liquid while the nozzle 29 is covered with the nozzle cap 62 of the ink head maintaining unit 6. Is called. The cleaning of the ink jet head 21 with the cleaning liquid is normally performed as needed (based on an instruction from the operator), but may be performed each time the printing is stopped. In this case, it may be immediately after the nozzle cap 62 is put on the nozzle 29, or just before the inkjet head 21 performs the next printing operation. Further, in the inkjet recording apparatus 1 of the present embodiment, when the inkjet head 21 is changed from the print pause state to the print state, it is determined whether or not the ink in the inkjet head 21 needs to be replaced. The printing operation is started after replacement with a predetermined amount of ink.

  Control of cleaning and ink replacement of the ink discharge unit 2 will be described with reference to FIG. FIG. 3 is a block diagram of an inkjet head cleaning / ink replacement control system according to the present invention.

  A part of the control unit 72 of the inkjet recording apparatus 1 constitutes an inkjet head cleaning / ink replacement control unit of the ink discharge unit 2. The inkjet head cleaning / ink replacement control unit includes a cleaning liquid amount setting unit 101, a cleaning liquid supply control unit 102, a cleaning liquid supply amount calculation unit 105, an ink replacement determination unit 106, and an ink replacement control unit 107. The cleaning liquid amount setting means 101 is an instruction of the inkjet head cleaning from the display operation panel 109 or the control unit 72 of the control unit 72 that controls the printing operation of the apparatus main body 1 and the number of times of cleaning. When the information is received, the cleaning liquid amount of the inkjet head is set. The cleaning liquid amount setting unit 101 selects a cleaning mode from the cleaning mode table stored in the ROM which is the cleaning mode storage unit 112 according to the instruction, and sets the cleaning liquid amount. At that time, the printing pause time measured by the timer 111 is acquired as necessary. Table 1 shows examples of cleaning mode tables that can be used. In addition to the table, the cleaning liquid amount may be set using a predetermined function or a setting value externally input from the display / operation panel 104. Further, as will be described later, the cleaning operation may be performed a plurality of times. In this case, the amount of the cleaning liquid in the second and subsequent cleaning operations is the same as the amount of the cleaning liquid in the first cleaning operation. However, after the second time, it is preferable to be able to change the amount of the cleaning liquid depending on the recovery condition by the first cleaning operation.

洗浄液量設定手段１０１は、設定した洗浄液量を洗浄液供給制御手段１０２に伝達し、洗浄液供給制御手段１０２は、洗浄液供給手段１０７がインクジェットヘッド１０４に所定量の洗浄液を供給するように制御する。洗浄液供給手段１０７の洗浄液供給量の制御は、吸引ポンプによる定量供給や、洗浄液供給バルブ２５の開放時間制御等により実行できる。そして、所定量の洗浄液がインクジェットヘッド１０４に供給されインクジェットヘッド１０４の洗浄が行われる。

The cleaning liquid amount setting means 101 transmits the set cleaning liquid amount to the cleaning liquid supply control means 102, and the cleaning liquid supply control means 102 controls the cleaning liquid supply means 107 to supply a predetermined amount of cleaning liquid to the inkjet head 104. Control of the cleaning liquid supply amount of the cleaning liquid supply means 107 can be performed by quantitative supply using a suction pump, opening time control of the cleaning liquid supply valve 25, or the like. Then, a predetermined amount of cleaning liquid is supplied to the inkjet head 104 and the inkjet head 104 is cleaned.

  With the above-described operation, one inkjet head cleaning operation is completed. Here, it is preferable to evaluate the cleaning result of the inkjet head. The apparatus main body 1 is returned to the standby state of the printing operation, and a test printing instruction is issued automatically by the control program of the printing control unit 110 or artificially from the display operation panel 109.

  When the test printing is executed, for example, when the operator evaluates the test printing result and determines that the cleaning is insufficient, the display operation panel 109 instructs the cleaning liquid amount setting unit 101 to perform the cleaning again, and the above-described inkjet head Repeat the washing. The evaluation of the test print result may be automatically performed by the apparatus main body 1 by measurement with a sensor or the like. If it can be determined that the cleaning effect is sufficient, the cleaning operation of the inkjet head is completed.

  Information on the number of times of cleaning set by the cleaning liquid amount setting means 101 and information on the amount of cleaning liquid for each cleaning time is transmitted to the cleaning liquid supply amount calculating means 105. When the number of times of cleaning is the first time, the cleaning liquid supply amount calculating means 105 uses the transmitted cleaning liquid amount as it is as the cleaning liquid supply amount, and when the number of cleaning times is the second time or later, the transmitted cleaning liquid amount is supplied to the previous cleaning liquid. Add the total amount to the new total amount of cleaning fluid supply. Note that a cleaning liquid amount measuring unit that measures the amount of cleaning liquid actually supplied by the cleaning liquid supply unit 103 may be provided, and the calculation may be performed based on the measured cleaning liquid amount.

  The ink replacement determination unit 106 determines whether or not ink replacement is necessary for the cleaning liquid in the inkjet head 104 based on information on the cleaning liquid supply amount from the cleaning liquid supply amount calculation unit 105. When the ink replacement determination unit 106 determines that the ink replacement is necessary, the ink replacement determination unit 106 instructs the ink replacement control unit 107 to supply ink to the ink supply unit 108. As a result, the ink jet head 104 is replaced with ink.

  Here, the ink replacement control unit 107 sets a replacement ink amount in response to an instruction for ink replacement control. The replacement ink amount is set based on the information on the cleaning liquid supply amount acquired from the cleaning liquid supply amount calculation unit 105. The ink supply means 108 can supply a predetermined amount of ink by quantitative supply by an ink supply pump (not shown), opening time control of the ink supply valve 24, suction time control of a suction pump disposed in the ink jet head maintenance unit, and the like.

  In order to determine whether or not ink replacement is required in the ink replacement determination unit 106 and the replacement ink amount in the ink replacement control unit 107, for example, the storage device stores the relationship between the supply amount of the cleaning liquid, the necessity of ink replacement, and the replacement ink amount. It may be determined or set according to this. Table 2 shows a table representing the relationship between the necessity of ink replacement and the amount of replacement ink. Note that a function using the cleaning liquid supply amount as a parameter may be stored in the cleaning mode storage unit 112, and the cleaning liquid supply amount and the function may be calculated.

インク置換制御手段１０７は、置換インク量を設定したら、この置換インク量に基づいてインク供給手段１０８にインク供給をさせて、インクジェットヘッド１０４のインク置換を実行させる。インク置換においては、インクジェットヘッドのノズルに被せてあるノズルキャップ６２側からインクジェットヘッド内の洗浄液を吸引ポンプで吸引して置換してもよいし、インク供給ライン２７に設けたポンプや、インクタンク２２に設けた加圧装置などにより、インクジェットヘッドにインクを供給して置換してもよい。インク供給手段１０８によるインク置換が終了したら、印刷制御部１１０は、インク置換制御手段１０７からの情報を得て、装置本体１を印刷動作のスタンバイ状態とする。また、表示操作部１０９にその旨の表示をする。

When the replacement ink amount is set, the ink replacement control unit 107 causes the ink supply unit 108 to supply ink based on the replacement ink amount, and causes the ink jet head 104 to perform ink replacement. In the ink replacement, the cleaning liquid in the ink jet head may be replaced with a suction pump from the nozzle cap 62 side that covers the nozzles of the ink jet head, or a pump provided in the ink supply line 27 or the ink tank 22 may be replaced. Ink may be replaced by supplying ink to the ink jet head by a pressurizing device or the like. When the ink replacement by the ink supply unit 108 is completed, the print control unit 110 obtains information from the ink replacement control unit 107 and sets the apparatus main body 1 in a standby state for the printing operation. In addition, a message to that effect is displayed on the display operation unit 109.

  On the other hand, when the ink replacement determination unit 106 determines that the ink replacement is not necessary, the ink replacement determination unit 106 notifies the print control unit 110 of the fact, and the print control unit 110 sets the apparatus main body 1 in a standby state for the printing operation. In addition, a message to that effect is displayed on the display operation unit 109.

  In the ink jet recording apparatus of the present invention, for example, by providing cleaning liquid amount setting means for determining the cleaning liquid amount by using the printing pause period and the installation environment temperature of the ink jet recording apparatus as an index, the environmental condition of the ink jet head and the printing pause history are recorded. Accordingly, the amount of cleaning liquid can be minimized. In addition, there is a process to evaluate the cleaning effect in the cleaning process, and it can be cleaned with a small amount of cleaning liquid, and whether or not cleaning can be performed again can be set based on the evaluation result. Can do.

  Further, by suppressing the amount of cleaning liquid in the cleaning to a small amount, the ink in the ink jet head does not become so thin without causing a problem in the image quality of the printed matter even if the ink in the ink jet head is not replaced. For this reason, only when necessary, the ink can be replaced with a minimum amount of ink, and the amount of ink to be replaced as an ink jet recording apparatus and the replacement time can be suppressed. In response to the demand for high-speed printing, the size of the inkjet head is increased. In particular, in the case of a line head type inkjet head, the amount of ink to be replaced and the replacement time are often problematic in terms of printing production efficiency. The recording apparatus is also suitable for such a line head type ink jet head.

(Ink ejection device cleaning control flow)
The flow of cleaning control of the inkjet head 21 will be described with reference to the flowchart of FIG. Note that FIGS. 1 to 3 are also referred to as appropriate. Cleaning of the inkjet head 21 is performed when the inkjet head 21 has stopped printing and the nozzle 29 is covered with the nozzle cap 62. Cleaning control of the inkjet head 21 is executed by the control unit 72 provided in the apparatus main body 1.

  When the cleaning liquid amount setting means 101 of the control unit 72 receives the cleaning start instruction (step S1), it obtains the pause time of the inkjet head, that is, the time since the last printing operation from the timer or the like (step S2). . In addition, the printing control unit 110 transmits cleaning frequency data together with a cleaning start instruction. The cleaning frequency data refers to the number of times the cleaning is repeated until the inkjet head 21 becomes normal by the cleaning operation of the inkjet head 21 before the start of printing.

  When the cleaning liquid amount setting unit 101 acquires the rest time of the inkjet head, based on this, the cleaning liquid amount setting unit 101 acquires a cleaning mode from a cleaning mode table or the like stored in the cleaning mode storage unit 112 such as a ROM (step S3). In the cleaning mode table, for example, as shown in Table 1, the amount of cleaning liquid to be supplied to the inkjet head is set corresponding to the rest time of the inkjet head.

  The cleaning liquid amount setting unit 101 calculates the amount of cleaning liquid to be supplied to the inkjet head from the acquired cleaning mode, causes the cleaning liquid supply unit 103 to supply a predetermined amount of cleaning liquid via the cleaning liquid supply control unit 102, and Cleaning is executed (step S4).

  The cleaning of the ink jet head by the cleaning liquid supply means 107 is completed based on the cleaning liquid supply time, the supply amount of the cleaning liquid used, and the like. Here, the supply amount of the used cleaning liquid is stored (step S5).

  Thus, the ink jet head is temporarily ready for printing. Therefore, the apparatus main body 1 executes test printing according to an instruction from the print control unit 110 or the display operation panel 109 (step S6). When the operator observes the test print result and determines that there is no problem in image quality and normal printing is possible, the process proceeds to the cleaning liquid supply amount calculation step S8 (YES in step S7), and it is determined that there is a problem in image quality. If there is a problem such as image roughness (dot missing), hue or lightness (darkness) defect due to clogging of some nozzles (NO in step S7), the process returns to step 3 and is washed again. Perform the operation. In the test printing result, if the image is very rough, the inkjet head is considered to be particularly insufficiently cleaned. Therefore, in the acquisition of the cleaning mode in step 3, a mode with a large amount of cleaning liquid is used regardless of the pause time of the inkjet head. It may be selected.

  The cleaning liquid supply amount calculation means 105 calculates and stores the cleaning liquid supply amount, which is the total cleaning liquid amount, from the cleaning frequency data and the supplied cleaning liquid amount (step S8). The calculated cleaning liquid supply amount is the cumulative cleaning liquid amount when there are a plurality of cleaning times.

  Next, the necessity for ink replacement for the cleaning liquid is determined by the ink replacement determination means 103 (step S9). The necessity of ink replacement is determined with reference to the cleaning necessity determination table. In the cleaning necessity determination table, for example, as shown in Table 2, the necessity of cleaning or the amount of ink to be supplied to the inkjet head is set corresponding to the cleaning liquid supply amount calculated in step S8.

  Referring to Table 2, if the cleaning liquid supply amount calculated in Step S8 exceeds a predetermined value (40 ml in the example of Table 2), it is determined that ink replacement is necessary (YES in Step S9). Further, the ink replacement control means 107 obtains the amount of supplied ink necessary for replacement with the cleaning liquid from Table 2.

  The ink replacement control unit 107 transmits an ink replacement instruction for the calculated ink supply amount to the ink supply unit 108 to supply ink to the inkjet head 104 and perform ink replacement (step S10). The ink replacement control unit 107 ends the ink replacement based on, for example, the ink supply time (step S11). Thereafter, printing is performed.

  On the other hand, if the cleaning liquid supply amount calculated in step S8 does not exceed a predetermined value (40 ml in the example of Table 2), the ink replacement determination unit 103 determines that there is no need for ink replacement (No in step S9). Ink replacement operation is not performed. That is, in this case, the ink replacement operation is not performed before printing.

Schematic configuration diagram of an inkjet recording apparatus according to the present invention Configuration diagram of ink ejection apparatus according to the present invention Block diagram of ink jet head cleaning and ink replacement control according to the present invention Flow chart of cleaning control of inkjet head according to the present invention

Explanation of symbols

1: Inkjet recording apparatus (apparatus body)
2: Ink ejection units 21, 21a, 21b, 21c, 21d: Inkjet heads 22, 22a, 22b, 22c, 22d: Ink tanks 23, 23a, 23b, 23c, 23d: Cleaning liquid tanks 24, 24a, 24b, 24c, 24d : Ink supply valves 25, 25a, 25b, 25c, 25d: Cleaning liquid supply valves 27, 27a, 27b, 27c, 27d: Ink supply lines 28, 28a, 28b, 28c, 28d: Cleaning liquid supply lines 29, 29a, 29b, 29c , 29d: Nozzle 3: Recording paper supply unit 31: Recording paper supply tray 32: Drawer roller 33: Supply roller 4: Recording paper conveyance unit 41: Conveying belt 42: Drive roller 43: Driven rollers 44, 45: Auxiliary roller 5: Recording paper discharge unit 51: Recording paper discharge tray 52: Auxiliary Over La 53: paper discharge roller 6: ink jet head maintenance unit 61: waste liquid tank 62: the nozzle cap 7: ink jet recording apparatus control unit 71: display operation panel 72: control unit (CPU)
101: Cleaning liquid amount setting means 102: Cleaning liquid supply control means 103: Cleaning liquid supply means 104: Inkjet head 105: Cleaning liquid supply amount calculation means 106: Ink replacement determination means 107: Ink replacement control means 108: Ink supply means 109: Display operation panel 110: Inkjet head driving means 111: Timer 112: Cleaning mode storage means

Claims (7)

An inkjet head that forms an image by ejecting ink onto a recording medium;
Ink supply means for supplying ink to the inkjet head;
Cleaning liquid supply means for supplying a cleaning liquid to the inkjet head;
An ink replacement determination means for determining whether or not an ink replacement operation for replacing the interior of the inkjet head after cleaning with ink is necessary according to the cleaning liquid supply amount supplied at the time of cleaning the inkjet head;
When the ink replacement determination unit determines that an ink replacement operation is necessary, the ink supply unit is controlled to perform the ink replacement operation before printing, and the ink replacement determination unit determines that ink replacement is unnecessary. An ink replacement control means for controlling not to perform the ink replacement operation before printing,
An ink jet recording apparatus comprising:   The inkjet recording apparatus according to claim 1, wherein the cleaning liquid includes a colorant.   The inkjet recording apparatus according to claim 1, further comprising a cleaning liquid amount setting unit that sets a cleaning liquid amount to be supplied by the cleaning liquid supply unit. Cleaning the inkjet head by the cleaning liquid supply means can include a plurality of cleaning operations,
The inkjet recording according to any one of claims 1 to 3, further comprising a cleaning liquid supply amount integrating unit that calculates the total cleaning liquid supply amount by integrating the cleaning liquid amount for each cleaning operation. apparatus.   5. The ink jet head recording apparatus according to claim 3, wherein the cleaning liquid amount setting unit sets the cleaning liquid amount based on a pause time of the image formation.   The ink replacement control unit sets a replacement ink amount in ink replacement based on a cleaning liquid supply amount supplied from the cleaning liquid supply unit to the inkjet head. The ink jet recording apparatus described in 1.   The inkjet recording apparatus according to claim 1, wherein the inkjet head is a line head type inkjet head.

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