JP2009184307A - Image forming apparatus and maintenance method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which shortens a time required for outputting a printing result, starting from a print start command, even when the apparatus makes no printing for a long time while its power is left turned on. <P>SOLUTION: The image forming apparatus carries out a maintenance operation of a head injecting a droplet from a nozzle, the maintenance operation which includes a cleaning operation sucking ink of the nozzle. The apparatus is characterized in that it includes: a measuring means 401 measuring a humidity in the apparatus; an accumulation means 402 accumulating a lapse time from a finishing point of the cleaning operation or a lapse time from a finishing point of image formation, and the lapse time in the case where a humidity level measured by the measuring means 401 is not more than a predetermined value; and a determination means 403 determining whether the maintenance operation is carried out from the accumulated times accumulated by the accumulation 402. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a maintenance method.

  2. Description of the Related Art Inkjet image forming apparatuses print characters and figures by ejecting ink from a large number of nozzles of an inkjet head and printing on paper. Therefore, the ink printed on the paper is required to be fast-drying so that high-speed printing can be performed, while the nozzle is required to have a small diameter so that high-quality output can be performed. It is easy to clog. Further, since it is required to eject smaller droplets, the discharge energy is reduced, and the nozzle is more easily clogged. Therefore, a technique for eliminating and preventing clogging of the nozzles with ink is important.

  Japanese Patent Laid-Open Nos. 2006-095818 and 2006-095819 change the amount of ink discharged at the time of flushing based on time information stored in a storage unit or time information received from an external device when printing is started. A technique for changing the maintenance operation is disclosed.

Japanese Patent Laid-Open No. 2006-159717 discloses a technique for performing a maintenance operation based on an accumulated decap time and an accumulated cap time at the start of printing.
JP 2006-095818 A JP 2006-095819 A JP 2006-159717 A

  In the above prior art, in order to prevent clogging of ink due to drying, a maintenance operation for returning the ink state to normal is performed before printing. However, if the period during which printing is not performed is long despite the power being on, the maintenance operation performed before the printing operation takes time, and there is a problem that printing cannot be performed quickly.

  The present invention has been made in view of the above problems, and can reduce the time from the print start instruction to the output of the print result even when the printing is not performed in the power-on state. An object is to provide a forming apparatus.

  In order to achieve the above object, the present invention provides an image forming apparatus that performs a maintenance operation including a cleaning operation for sucking ink from the nozzles with respect to a head that ejects droplets from the nozzles. A measuring means for measuring the time, and an elapsed time from the end time of the cleaning operation or an elapsed time from the end time of image formation, wherein the elapsed time when the humidity measured by the measuring means is a predetermined value or less is accumulated. And accumulating means for determining whether or not to perform the maintenance operation based on the accumulated time accumulated by the accumulating means.

  Alternatively, the present invention provides a maintenance method for performing a maintenance operation including a cleaning operation for sucking ink from the nozzles on a head that ejects droplets from the nozzles, and a measuring step for measuring humidity in the image forming apparatus; An accumulation step of accumulating the elapsed time from the end time of the cleaning operation or the elapsed time from the end point of image formation, and the elapsed time when the humidity measured by the measurement step is equal to or lower than a predetermined value; And a determination step of determining whether or not to perform the maintenance operation based on the accumulated time accumulated in step (b).

  According to the present invention, it is possible to reduce the time from the print start command to the output of the print result even when the period in which printing is not performed in the power-on state is long.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged view of a main part of an inkjet head of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the main part in the channel-to-channel direction of the inkjet head. FIG. 3 is a top view of a pressure generating chamber in the inkjet head. Hereinafter, the ink jet head of the image forming apparatus according to the present embodiment will be described with reference to FIGS.

  The main part of the inkjet head shown in FIG. 1 includes a frame 101, a flow path plate 102, a nozzle plate 103, a vibration plate 104, a laminated piezoelectric element 105, and a base 106.

  The frame 101 forms an engraving that becomes an ink supply port 114 and a common liquid chamber 107. The frame 101 is made of, for example, a thermosetting resin such as an epoxy resin or polyphenylene sulfite.

  The flow path plate 102 forms a digging that becomes the fluid resistance portion 108 and the pressure generation chamber 109 and a communication port 111 that communicates with the nozzle 110. Further, the engraving that becomes the fluid resistance portion 108 and the pressure generation chamber 109 and the through-hole that becomes the communication port 111 are patterned by an etching method using a silicon single crystal substrate.

  Further, the portion left by the etching method becomes the partition wall 201 (see FIG. 2) of the pressure generating chamber 109. In this ink jet head, a portion for narrowing the etching width is provided, and this is used as the fluid resistance portion 108.

  The nozzle plate 103 forms a large number of nozzles 110 that are fine discharge ports for causing droplets to fly, and is joined to the flow path plate 102. The nozzle plate 103 is formed of a metal material, for example, an Ni plating film by an electroforming method. The inner shape (inner shape) of the nozzle 110 is formed in a horn shape. The internal shape of the nozzle 110 is not limited to the horn shape, and may be a substantially cylindrical shape or a substantially truncated cone shape. The nozzle 110 has a diameter on the ink droplet outlet side of about 20 to 35 μm. The nozzle pitch of each row of nozzles 110 is 150 dpi.

  The ink ejection surface (nozzle surface side) of the nozzle plate 103 is provided with a water repellent treatment layer subjected to a water repellent surface treatment. This ink ejection surface is obtained by PTFE-Ni eutectoid plating, fluororesin electrodeposition coating, vapor-deposited fluororesin (for example, fluorinated pitch, etc.), after application of silicon resin / fluorine resin solvent A water repellent film selected according to the ink physical properties, such as printing, is provided to stabilize the droplet shape and flight characteristics and to obtain high-quality image quality.

  The diaphragm 104 will be described with reference to FIG. The diaphragm 104 includes a thin film diaphragm portion 112, island-shaped convex island portions 113 joined to the laminated piezoelectric element 105, thick film portions including beams joined to the support portions 203, and openings serving as ink supply ports 114. Is formed by stacking two Ni plating films by electroforming. The diaphragm 112 has a thickness of 3 μm and a width of 35 μm (one side).

  The island portion 113 of the vibration plate 104 and the driving portion 202 of the laminated piezoelectric element 105, and the connection between the vibration plate 104 and the frame 101 are bonded by patterning the adhesive layer 115 including a gap material.

  The laminated piezoelectric element 105 will be described with reference to FIG. The laminated piezoelectric element 105 is bonded to the vibration plate 104 via an adhesive layer 115, and has a thickness of 10 to 50 μm / layer of lead zirconate titanate (PZT) and a thickness of several μm / layer of silver. The internal electrode layers made of palladium (AgPd) are alternately stacked. Both ends of each internal electrode layer are connected to external electrodes.

  The laminated piezoelectric element 105 is divided on comb teeth by half-cut dicing, and is used as a drive unit 202 and a support unit 203 (non-drive unit) every two. The outside of the external electrode is divided by a half-cut dicing process, and the length is limited by a process such as a notch, which becomes a plurality of individual electrodes 116. The other is not divided in the dicing process and is conductive and becomes the common electrode 117.

  FPC (Flexible Printed Circuits) 8 is soldered to the individual electrodes 116 of the drive unit 202. The common electrode 117 is joined to the Gnd electrode of the FPC 8 by providing an electrode layer at the end of the laminated piezoelectric element 105. A driver IC is mounted on the FPC 8 to control application of a driving voltage to the driving unit 202.

  The base 106 is made of a barium titanate ceramic, and the multilayered piezoelectric elements 105 are arranged in two rows and joined.

  Next, the droplet discharge operation of the inkjet head in the present invention will be described. When a drive waveform (pulse voltage of 10 to 50 V) is applied to the drive unit 202 according to the recording signal, displacement in the stacking direction occurs in the drive unit 202, and the pressure generation chamber 109 is pressurized via the diaphragm 104. As a result, the pressure rises and droplets are ejected from the nozzle 110.

  When the droplet discharge is completed, the ink pressure in the pressure generating chamber 109 decreases, and a negative pressure is generated in the pressure generating chamber 109 due to the inertia of the ink flow and the discharge process of the drive pulse, and the process proceeds to the ink filling step. At this time, the ink supplied from the ink tank flows into the common liquid chamber 107, passes from the common liquid chamber 107 through the ink supply port 114, passes through the fluid resistance portion 108, and is filled with ink in the pressure generation chamber 109.

  The fluid resistance unit 108 is effective in damping the residual pressure vibration after ejection, but is resistant to the maximum filling (refill) due to surface tension. Therefore, by appropriately using the fluid resistance unit 108, it is possible to balance the decrease in the residual pressure and the refill time, and to shorten the time (drive period) until the transition to the next droplet discharge operation.

  As described above, in the above-described ink jet head, if the viscosity of the ink is high or the quick drying property is high, the ink is quickly dried, and the nozzles are clogged due to the thickening of the ink. In response to the nozzle clogging, the nozzle clogging can be eliminated by performing a maintenance operation such as an idle discharge operation or a cleaning operation.

  Note that the idle ejection operation means that the ink jet head is moved outside the recording area and ink is ejected to the ink absorbing member, and the cleaning operation is that the suction pump applies a negative pressure to each nozzle opening. This means that ink is sucked from the nozzle openings of the inkjet head with a predetermined suction level (suction force, suction amount, suction time, etc.), and the thickened ink in the pressure generating chamber is forcibly discharged.

  Here, the maintenance control of the image forming apparatus in this embodiment will be described with reference to FIG. FIG. 4 is a functional block diagram relating to maintenance control of the image forming apparatus according to the present exemplary embodiment. The maintenance control unit 400 of the image forming apparatus according to the present exemplary embodiment includes a humidity measurement unit 401, an elapsed time accumulation unit 402, a maintenance determination unit 403, and a maintenance unit 404.

  The humidity measuring unit 401 measures the humidity near the nozzles in the image forming apparatus. In addition, the humidity measuring unit 401 outputs the measured humidity to the elapsed time accumulating unit 402.

  The humidity measuring unit 401 measures the humidity in the vicinity of the nozzle. However, the humidity in the apparatus that is not in the vicinity of the nozzle or the humidity outside the apparatus may be measured.

  When the elapsed time accumulating unit 402 acquires the humidity from the humidity measuring unit 401, the elapsed time accumulating unit 402 determines whether the acquired humidity is equal to or less than a predetermined value. If it is determined that the humidity is below a predetermined value, the elapsed time from the end of the cleaning operation or the end of image formation is measured and accumulated. Details of the elapsed time accumulating means 402 will be described later with reference to FIG.

  The maintenance determining unit 403 acquires the accumulated time from the elapsed time accumulating unit 402, and determines the content of the maintenance based on the acquired accumulated time and the predetermined time held. Also, the maintenance determination unit 403 instructs the maintenance unit 404 to perform a maintenance operation based on the determination result. A detailed determination method will be described later with reference to FIG.

  The maintenance unit 404 includes a fine movement unit 405, an idle discharge unit 406, and a cleaning unit 407, and performs a maintenance operation of any one of the fine movement operation, the idle discharge operation, and the cleaning operation based on an instruction from the maintenance determination unit 403.

  When the fine movement means 405 receives an instruction to perform an operation from the maintenance determination means 403, the fine movement means 405 gives a fine vibration to the ink jet head to such an extent as not to discharge.

  Upon receiving an instruction to perform an operation from the maintenance determination unit 403, the idle ejection unit 406 performs an idle ejection operation for ejecting droplets to the non-recording area.

  When the cleaning unit 407 receives an instruction to perform an operation from the maintenance determination unit 403, the cleaning unit 407 performs a cleaning operation of sucking the thickened ink from the nozzle opening by the suction pump. The cleaning unit 407 notifies the elapsed time accumulating unit 402 of a cleaning start notification and a cleaning end notification.

  FIG. 5 is a detailed functional block diagram of the elapsed time accumulating means 402. The elapsed time accumulating unit 402 includes a humidity determining unit 501, an accumulated time calculating unit 502, an accumulated time storage unit 503, and a reset unit 504.

  When the humidity determination unit 501 acquires the humidity from the humidity measurement unit 401, the humidity determination unit 501 compares the acquired humidity with a predetermined value that is held, and determines whether the humidity is equal to or lower than the predetermined value. Next, the humidity determination unit 501 outputs the determination result to the accumulated time calculation unit 502. Here, the held predetermined value is, for example, 70% RH.

  If the cumulative time calculation unit 502 receives an image formation end notification from the image forming unit or a cleaning end notification from the cleaning unit 407 and receives a determination result that the humidity is equal to or lower than the predetermined value from the humidity determination unit 501, the accumulated time calculation unit 502 calculates the elapsed time. Accumulate and calculate the accumulated time. When the accumulated time is accumulated, the accumulated time calculating means 502 outputs the accumulated time to the accumulated time storage means 503. If the cumulative time calculation unit 502 receives a determination result that the humidity is greater than the predetermined value from the humidity determination unit 501, the cumulative time calculation unit 502 does not accumulate the elapsed time.

  When the cumulative time calculation unit 502 receives an instruction to reset the cumulative time from the reset unit 504, the cumulative time calculation unit 502 resets the calculated cumulative time to 0 after completion of image formation or cleaning.

  When the accumulated time storage unit 503 acquires the accumulated time from the accumulated time calculation unit 502, the accumulated time storage unit 503 stores the acquired accumulated time. The stored accumulated time is periodically read to the maintenance determination unit 403.

  When receiving the image formation start notification from the image forming unit or the cleaning start notification from the cleaning unit 407, the reset unit 504 instructs the cumulative time calculation unit 502 to reset the cumulative time.

  Note that the cumulative time storage unit 503 shown in FIG. 5 is not provided, and the cumulative time calculation unit 502 may directly output the cumulative time to the maintenance determination unit 403.

  FIG. 6 is a flowchart of elapsed time accumulation processing in the present embodiment. In step 601, it is determined whether the accumulated time calculation unit 502 has received an image formation end notification from the image forming unit or a cleaning end notification from the cleaning unit 407. If it is determined in step 601 that the image formation end notification or the cleaning end notification has not been received, the accumulated time calculation unit 502 performs the determination in step 601 again.

  If it is determined in step 601 that an image formation end notification or a cleaning end notification has been received, in step 602, the accumulated time calculation unit 502 resets the calculated accumulated time to zero. In step 603, the accumulated time calculation means 502 waits for a predetermined time.

  Next, in step 604, the humidity determination means 501 determines whether the acquired humidity is below a predetermined value. If it is determined in step 604 that the acquired humidity is equal to or less than a predetermined value, in step 605, the accumulated time calculation unit 502 adds the predetermined time to the accumulated time to calculate the accumulated time. If it is determined in step 604 that the acquired humidity is greater than the predetermined value, the process proceeds to step 606.

  In step 606, the reset unit 603 determines whether an image formation start notification or a cleaning start notification has been received. If it is determined in step 606 that an image formation start notification or a cleaning start notification has been received, the reset unit 603 instructs the accumulated time calculation unit 502 to reset the accumulated time, and the process returns to step 601. If it is determined in step 606 that no image formation start notification or cleaning start notification has been received, the process returns to step 603.

  In the present embodiment, the example of performing the process of FIG. 6 in the configuration of FIG. 5 has been described as an example, but the present invention is not necessarily limited to this configuration and process. For example, instead of calculating the cumulative time by waiting for a predetermined time and accumulating the standby predetermined time as in the present embodiment, the actual time from when the humidity falls below a predetermined value until it becomes greater than the predetermined value There is also a method of measuring time and adding the measured time to the accumulated time. In other words, if the elapsed time from the end of image formation or the elapsed time from the end of the cleaning operation and the elapsed time when the humidity is not more than a predetermined value can be accumulated, the configuration and processing of this embodiment are limited. I can't.

  FIG. 7 is a flowchart of the maintenance determination process in the present embodiment. In step 701, the maintenance determination unit 403 determines whether or not the acquired accumulated time is equal to or less than one week (first predetermined time).

  When it is determined in step 701 that the accumulated time is equal to or less than one week (first predetermined time), the maintenance determination unit 403 determines to perform a fine movement operation as a maintenance operation, and performs an operation on the fine movement unit 405. Instruct.

  In step 702, when the fine movement means 405 receives an instruction to perform an operation from the maintenance determination means 403, the fine movement means 405 gives a fine vibration to the ink jet head so as not to discharge. As a result, the ink in the vicinity of the nozzle can be agitated, and the ink can be prevented from drying.

  When it is determined in step 701 that the accumulated time is longer than one week (first predetermined time), in step 703, the maintenance determining unit 403 has a cumulative time of one month (second predetermined time) or less. It is determined whether or not.

  When it is determined in step 703 that the accumulated time is equal to or less than one month (second predetermined time), the maintenance determination unit 403 determines to perform the idle discharge operation as the maintenance operation, and the idle discharge unit 406 operates. To instruct

  In step 704, when the idle ejection unit 406 receives an instruction to perform an operation from the maintenance determination unit 403, an idle ejection operation for ejecting droplets to the non-recording area is performed. As a result, it is possible to eliminate the drying of the ink that cannot be eliminated by the fine movement operation.

  When it is determined in step 703 that the accumulated time is longer than one month (second predetermined time), the maintenance determination unit 403 determines to perform the cleaning operation as the maintenance operation, and instructs the cleaning unit 407 to perform the operation. To do.

  In step 705, when the cleaning unit 407 receives an instruction to perform an operation from the maintenance determination unit 403, the cleaning unit 407 performs a cleaning operation of sucking the thickened ink from the nozzle opening by the suction pump. As a result, it is possible to eliminate the drying of ink that cannot be eliminated by the idle ejection operation.

  Here, the first predetermined time and the second predetermined time are set to one week and one month, respectively, but the first predetermined time and the second predetermined time can be appropriately set according to the characteristics of the ink.

  As described above, according to the embodiment of the present invention, the maintenance operation is periodically performed regardless of the print start instruction, so that even when the printing is not performed in the power-on state, the printing is started from the print start instruction. The time until the result is output can be shortened. Further, according to the present embodiment, the humidity in the apparatus is measured, and the elapsed time from the end of the image formation or the end of the cleaning operation is accumulated, and the elapsed time when the humidity is equal to or less than a predetermined value is accumulated. A maintenance operation without waste can be performed at an appropriate timing according to the environment. Furthermore, according to the present embodiment, when printing is not performed for a long period of time, for example, when printing is not performed for one month or more, it is not necessary to perform a maintenance operation that consumes a large amount of ink at a time as in the prior art. The amount can be reduced.

(Modification)
As a modification of the image forming apparatus in the present embodiment, the number of vibrations of the fine movement operation and the number of discharges of the idle discharge operation can be changed in accordance with the humidity at which the maintenance operation is performed. This modification will be described with reference to FIG.

  FIG. 8 is a diagram illustrating the relationship between the measured humidity, the number of vibrations, and the number of ejections. In the example shown in FIG. 8, the number of vibrations increases to 10, 30, and 50 as the humidity decreases to 50% RH, 30% RH, and 10% RH. Also, the number of ejections increases to 10, 100, and 150 as the humidity decreases to 50% RH, 30% RH, and 10% RH. Accordingly, an appropriate maintenance operation can be performed according to the usage environment of the image forming apparatus, and ink drying can be prevented.

  It is also conceivable to apply a coefficient to the accumulated elapsed time according to the measured humidity. That is, this is a method of accumulating the elapsed time by multiplying the elapsed time by a higher coefficient as the measured humidity is lower. Accordingly, the lower the humidity is, the larger the cumulative time value for accumulating the elapsed time is, and the earlier the timing for entering the maintenance operation, the ink can be prevented from drying.

  The timing at which the maintenance determination unit 403 acquires the accumulated time can be changed as appropriate. At the same time as the elapsed time accumulating unit 402 accumulates the elapsed time, the maintenance determining unit 403 may acquire the accumulated time, or the accumulated time is acquired at a timing different from the timing at which the elapsed time accumulating unit 402 accumulates the elapsed time. May be. For example, since the acquisition interval after the cumulative time exceeds the first predetermined time is longer than the acquisition interval until the cumulative time reaches the first predetermined time, the idle discharge operation is performed more than necessary. You can avoid doing it.

  Further, the maintenance determination unit 403 holds a third predetermined time shorter than the first predetermined time, and determines that the maintenance operation is not performed when the acquired accumulated time is equal to or shorter than the third predetermined time. Also good.

  Further, the maintenance operation may be performed at night using a clock provided in the image forming apparatus. Accordingly, when printing is performed during the day, printing can be performed more quickly.

  In addition, the nozzle surface of the head that can be used in this embodiment or a modification may be coated with a material having water repellency. By being coated, the liquid causing the dirt is repelled and the liquid is suppressed from adhering to the nozzle surface. For this reason, it is possible to prevent the nozzle and the discharge port from being blocked by the particles generated by the solidification of the dirt. Even if the liquid causing the contamination adheres to the nozzle surface, the bonding force is weak.

  In addition, when the surface tension of the ink is low, the ink spreads to the vicinity of the nozzle on a general nozzle surface, and a normal meniscus may not be formed. In such a state, ink ejection bends or non-ejection occurs. However, if the nozzle surface is coated with a material having water repellency, the ink does not spread in the vicinity of the nozzle but stays in the nozzle, so that normal ejection can be performed.

  Formation of the water-repellent film on the nozzle surface may be performed by vacuum deposition, or may be applied by dissolving in a suitable solvent. As for the former, for example, after the inside of the vacuum chamber is evacuated to a predetermined degree of vacuum with a vacuum pump, the water repellent material is vaporized at 400 ° C. and introduced into the vacuum chamber. Next, the vacuum atmosphere is adjusted, and power is supplied from the high-frequency power source to the discharge electrode to cause RF glow discharge. The surface of the orifice of the liquid discharge head is surface-treated in a plasma atmosphere to repel the orifice surface. A water film can be formed. Depending on the material and the degree of vacuum in the vacuum chamber, it is possible to form a water-repellent film at a low temperature of about room temperature to about 200 ° C.

  As for the latter, for example, a water-repellent material can be dissolved in an organic solvent and coated with a jig such as a wire bar or a doctor blade, or can be applied by spin coating with a spin coater or by spraying. It can also be dip coated (dipped) in a container filled with a coating solution.

  As the water repellent material, an organic compound having a fluorine atom, particularly an organic substance having a fluoroalkyl group, an organic silicon compound having a dimethylsiloxane skeleton, and the like can be used.

  As the organic compound having a fluorine atom, fluoroalkylsilane, alkane having a fluoroalkyl group, cambonic acid, alcohol, amine and the like are desirable. Specifically, the fluoroalkylsilane includes heptadecafluoro-1,1,2,2-tetrahydrodecyltrimethoxysilane, heptadecafluoro-1,1,2,2-tetrahydrotrichlorosilane; fluoroalkyl Examples of the alkane having a group include octafluorocyclobutane, perfluoromethylcyclohexane, perfluoro-n-hexane, perfluoro-n-heptane, tetradecafluoro-2-methylpentane, perfluorododecane, perfluoroeucosan; Examples of the carboxylic acid having an alkyl group include perfluorodecanoic acid and perfluorooctanoic acid; examples of the alcohol having a fluoroalkyl group include 3, 3, 4, 4, 5, 5, 5-heptafluoro-2-pentanol; A with a fluoroalkyl group The emissions, heptadecafluoro-1,1,2,2-tetrahydro-decyl amine. Examples of organosilicon compounds having a dimethylsiloxane skeleton include α, w-bis (3-aminopropyl) polydimethylsiloxane, α, w-bis (3-glycidoxypropyl) polydimethylsiloxane, α, w-bis (vinyl). ) Polydimethylsiloxane and the like.

  As another water-repellent material, an organic compound having a silicon atom, particularly an organic compound having an alkylsiloxane group can be used. Examples of the organic compound having an alkylsiloxane group include alkylsiloxane groups having two or more alkylsiloxane groups and cyclic aliphatic epoxy groups in the molecule constituting the alkylsiloxane epoxy resin composition. The high molecular compound containing the structural unit represented by general formula (a) and (b) of these is mentioned.

  The compound having a structure as shown in FIG. 9 also functions as a binder when used in combination with other water-repellent compounds. That is, it improves the workability of the ink-repellent composition and improves the workability as a dry coating film that improves the drying property after evaporation of the solvent.

  The film thickness of the water repellent film is preferably 5 μm or less, more preferably 2 μm or less. When the film thickness exceeds 5 μm, drying of the coating film may be delayed, productivity may be deteriorated, and mechanical durability may be impaired, and peeling may occur when wiping is performed.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the specific embodiment which concerns, In the range of the summary of this invention described in the claim, except the said modification In addition, various modifications and changes can be made.

1 is an enlarged view of a main part of an inkjet head of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view of a main part in a channel-to-channel direction of the inkjet head of the image forming apparatus according to the embodiment of the present invention. 1 is a top view of a pressure generation chamber of an inkjet head of an image forming apparatus according to an embodiment of the present invention. The functional block diagram regarding the maintenance control in a present Example. The detailed functional block diagram of the elapsed time accumulation means in a present Example. The flowchart of the elapsed time accumulation process in a present Example. The flowchart of the maintenance determination process in a present Example. The figure which shows the relationship between the measured humidity in the modification, the frequency | count of vibration, and the frequency | count of discharge. The figure which shows an example of an alkylsiloxane containing epoxy resin.

Explanation of symbols

101 Frame 102 Flow path plate 103 Nozzle plate 104 Vibration plate 105 Multilayer piezoelectric element 106 Base 107 Common liquid chamber 108 Fluid resistance portion 109 Pressure generation chamber 110 Nozzle 111 Communication port 112 Diaphragm portion 113 Island portion 114 Ink supply port 115 Adhesive layer 116 Individual Electrode 117 Common electrode 201 Partition 202 Drive unit 203 Support unit 400 Maintenance control unit 401 Humidity measurement unit 402 Elapsed time accumulation unit 403 Maintenance determination unit 404 Maintenance unit 405 Fine movement unit 406 Ejection unit 407 Cleaning unit 501 Humidity determination unit 502 Accumulation time calculation Means 503 Accumulated time storage means 504 Reset means

Claims (9)

In an image forming apparatus that performs a maintenance operation including a cleaning operation for sucking ink from the nozzles with respect to a head that ejects liquid droplets from the nozzles.
Measuring means for measuring humidity in the image forming apparatus;
An accumulating unit that accumulates an elapsed time from the end time of the cleaning operation or an elapsed time from the end point of image formation when the humidity measured by the measuring unit is a predetermined value or less;
An image forming apparatus comprising: a determination unit that determines whether or not to perform the maintenance operation based on an accumulation time accumulated by the accumulation unit. The image forming apparatus according to claim 1, wherein the determination unit changes a content of a maintenance operation according to the accumulated time. 3. The image forming apparatus according to claim 2, wherein, when the determination unit determines that the accumulated time is equal to or shorter than a first predetermined time, the fine movement operation for finely moving the head is performed as the maintenance operation. When the determination unit determines that the accumulated time is longer than the first predetermined time and equal to or shorter than a second predetermined time, an empty discharge operation for discharging ink is performed as the maintenance operation. The image forming apparatus according to claim 3. The image forming apparatus according to claim 4, wherein the cleaning operation is performed as the maintenance operation when the determination unit determines that the accumulated time is longer than the second predetermined time. 4. The image forming apparatus according to claim 3, wherein in the fine movement operation, the number of vibrations of the fine movement is changed in accordance with the humidity measured by the measuring unit. The image forming apparatus according to claim 4, wherein the idle ejection operation changes the number of ejections in the idle ejection operation according to the humidity measured by the measuring unit. The image forming apparatus according to claim 1, wherein the accumulation unit sets the accumulation time to zero after the cleaning operation is completed or after the image formation is completed. In a maintenance method for performing a maintenance operation including a cleaning operation for sucking the ink of the nozzle on a head that ejects liquid droplets from the nozzle,
A measurement step for measuring the humidity in the image forming apparatus;
An accumulation step of accumulating the elapsed time when the humidity measured by the measurement step is equal to or less than a predetermined value, the elapsed time from the end of the cleaning operation or the elapsed time from the end of image formation;
A determination step of determining whether or not to perform the maintenance operation based on the accumulated time accumulated in the accumulation step.

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