JP2014046649A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that it takes time, and frequency also increases for a maintenance operation for preventing drying of a suction member in a suction cap.SOLUTION: An image forming apparatus discriminates whether or not paper powder adhesion degree count is equal to or more than a first threshold when drying degree count is equal to or more than a threshold, discriminates whether or not mist adhesion degree count is equal to or more than the first threshold when the paper powder adhesion count is not equal to or more than the first threshold, discharges droplets in a cap 82a from a recording head 34 when the mist adhesion degree count is not equal to or more than the first threshold, and performs a first drying prevention maintenance operation which is a replenishment discharge operation for sucking the inside of the cap 82a by starting actuation of a suction pump 220 simultaneously as discharge or prior to the discharge.

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus provided with a recording head for discharging droplets.

  As an image forming apparatus such as a printer, a facsimile, a copying apparatus, a plotter, and a complex machine of these, for example, a liquid discharge recording type image forming apparatus using a recording head composed of a liquid discharge head (droplet discharge head) for discharging droplets Inkjet recording apparatuses are known.

  In such an image forming apparatus, in order to maintain the ejection stability of the nozzles of the recording head, a suction cap to which a suction unit for capping the nozzle surface is connected, ink drying in the nozzles, and dust mixing into the nozzles are prevented. Therefore, a maintenance / recovery mechanism including a moisturizing cap for capping the nozzle surface and a wiper member (also referred to as a wiper blade, wiping blade, blade, etc.) that wipes and cleans the nozzle surface of the recording head is provided. After discharging the thickened ink from the nozzle into the suction cap, a recovery operation is performed in which the nozzle surface is wiped with a wiper member to form a nozzle meniscus.

  Here, it is known that an absorbing member that absorbs the waste liquid is disposed in the suction cap so that the capped space is kept at high humidity by the moisture of the liquid held in the absorbing member. .

  When a cap having such an absorbing member is used, there is a problem that when the absorbing member is dried, moisture is taken away from the liquid in the nozzle at the time of capping to increase the viscosity, thereby causing a drop ejection failure.

  Therefore, conventionally, when the preliminary discharge amount discharged into the cap reaches a predetermined amount, replenishment discharge into the cap (a discharge amount several to several tens of times the preliminary discharge amount) is performed, and the subsequent operation It is known that old waste liquid (having lost wet components) accumulated in the absorbent body is washed away with a new liquid and discharged by performing suction in the cap (Patent Document 1).

  Further, it is known that a liquid is supplied into a cap when a product time of a decap time when the cap does not capping the nozzle surface reaches a threshold value (Patent Document 2).

JP 2007-230204 A JP 2007-130861 A

  However, in the configuration disclosed in Patent Documents 1 and 2 described above, in-cap drying prevention operation (hereinafter referred to as “in-cap drying prevention maintenance operation”) in order to perform liquid replenishment and suction operation in the cap. There is a problem that becomes longer.

  The present invention has been made in view of the above problems, and an object thereof is to shorten the time required for the cap anti-drying maintenance operation as much as possible without increasing the frequency of the cap anti-drying maintenance operation. .

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A recording head having nozzles for discharging droplets;
A cap member having an absorbing member for capping the nozzle surface of the recording head and absorbing liquid therein;
A suction means for performing suction from the cap member;
Replenishment discharge control means for discharging droplets from the recording head into the cap member and performing replenishment discharge operation for starting driving of the suction means at the same time as discharge or prior to discharge;
A drying degree determining means for determining whether or not a drying degree correlation value correlated with a drying degree in the cap member is equal to or greater than a threshold;
A first threshold value in which at least one of a paper dust adhesion degree correlation value that correlates with the degree of paper dust adhesion to the nozzle surface and a mist adhesion degree correlation value that correlates with the degree of mist adhesion to the nozzle surface is predetermined. First adhesion degree determining means for determining whether or not the above has been reached,
The replenishment / discharge control means performs the replenishment / discharge operation when the dryness degree correlation value is equal to or greater than a threshold value and at least one of the paper dust adhesion degree correlation value and the mist adhesion degree correlation value is less than the first threshold value. The control is performed.

  According to the present invention, the time required for the in-cap drying prevention maintenance operation can be shortened as much as possible without increasing the frequency of the in-cap drying prevention maintenance operation.

FIG. 3 is a side explanatory view illustrating a mechanism unit of an example of an image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part. It is a typical schematic block diagram of the maintenance recovery mechanism in the same apparatus. Similarly it is principal part plane explanatory drawing. It is block explanatory drawing with which the outline | summary of the control part of the apparatus is provided. It is a flowchart explaining the control concerning the maintenance operation | movement by the same control. FIG. 7 is a flowchart that similarly follows FIG. 6. It is a flowchart with which it uses for description of 1st drying prevention maintenance operation (replenishment discharge operation). It is a flowchart with which it uses for description of the process of the replenishment discharge operation of a comparative example. It is a flowchart with which it uses for description of cleaning operation | movement and 2nd drying prevention maintenance operation | movement. It is a flowchart with which it uses for description of paper dust adhesion degree count. It is explanatory drawing similarly. It is a flowchart with which it uses for description of mist adhesion degree count. It is explanatory drawing similarly. It is a flowchart with which it uses for description of dry degree count. It is explanatory drawing similarly. It is explanatory drawing with which it uses for description of an example of parameter X, Y (ratio of the 1st threshold value with respect to a 2nd threshold value) which sets the 1st threshold value of a paper dust adhesion degree and a mist adhesion degree. It is explanatory drawing with which it uses for description of the other example of parameter X, Y (ratio of the 1st threshold value with respect to a 2nd threshold value) which sets the 1st threshold value of a paper dust adhesion degree and a mist adhesion degree.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG. 2 is an explanatory plan view of a main part of the apparatus.

  This image forming apparatus is a serial type ink jet recording apparatus, and a carriage 33 is slidable in a main scanning direction by main and sub guide rods 31 and 32 which are guide members horizontally mounted on the left and right side plates 21A and 21B of the apparatus main body 1. It is held and moved and scanned in the carriage main scanning direction via a timing belt by a main scanning motor described later.

  The carriage 33 is provided with recording heads 34a and 34b composed of liquid ejection heads for ejecting ink droplets of yellow (Y), cyan (C), magenta (M), and black (K). The “recording head 34” is arranged in a sub-scanning direction orthogonal to the main scanning direction, and a droplet discharge direction is directed downward.

  Each of the recording heads 34 has two nozzle rows. One nozzle row of the recording head 34a has black (K) droplets, the other nozzle row has cyan (C) droplets, and the recording head 34b has one nozzle row. One nozzle row ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets.

  Further, the carriage 33 is equipped with head tanks 35a and 35b (referred to as “head tank 35” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 34. In the head tank 35, ink cartridges 10y, 10m, 10c, and 10k, which are main tanks of the respective colors that are detachably attached to the cartridge loading unit 4, are supplied from the ink pumps 24 through the supply tubes 36 of the respective colors. Of ink is replenished.

  On the other hand, as a paper feeding unit for feeding the papers 42 stacked on the paper stacking unit (pressure plate) 41 of the paper feeding tray 2, a half-moon roller (feeding) that separates and feeds the papers 42 one by one from the paper stacking unit 41. A separation pad 44 made of a material having a large friction coefficient is provided facing the paper roller 43) and the paper feed roller 43, and the separation pad 44 is urged toward the paper feed roller 43 side.

  In order to feed the paper 42 fed from the paper feeding unit to the lower side of the recording head 34, a guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressure roller. And a holding belt 48 which is a conveying means for electrostatically attracting the fed paper 42 and conveying it at a position facing the recording head 34.

  The transport belt 51 is an endless belt, and is configured to wrap around the transport roller 52 and the tension roller 53 and circulate in the belt transport direction (sub-scanning direction).

  Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided. The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. The transport belt 51 rotates in the belt transport direction when the transport roller 52 is rotationally driven through timing by a sub-scanning motor described later.

  Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 61 for separating the paper 42 from the conveying belt 51, a paper discharge roller 62, and a spur 63 that is a paper discharge roller. And a paper discharge tray 3 below the paper discharge roller 62.

  A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the conveyance belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyance belt 51. The upper surface of the duplex unit 71 is a manual feed tray 72.

  Further, a maintenance / recovery mechanism 81 for maintaining and recovering the nozzle state of the recording head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction.

  The maintenance and recovery mechanism 81 includes cap members (hereinafter referred to as “caps”) 82a and 82b (hereinafter referred to as “caps 82” when not distinguished from each other) for capping each nozzle surface of the recording head 34, and nozzle surfaces. A wiper member (wiper blade) 83 for wiping the recording medium, an empty discharge receiver 84 for receiving liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid, and a carriage And a carriage lock 87 for locking 33.

  Here, an absorbing member (absorber) 90 that absorbs the discharged liquid waste liquid is disposed in the suction cap 82a.

  A waste liquid tank 100 for storing waste liquid generated by the maintenance recovery operation is mounted on the lower side of the head recovery mechanism 81 in a replaceable manner with respect to the apparatus main body.

  Further, in the non-printing area on the other side of the carriage 33 in the scanning direction, there is an empty space for receiving liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. A discharge receiver 88 is disposed, and the idle discharge receiver 88 includes an opening 89 along the nozzle row direction of the recording head 34.

  In the image forming apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feed tray 2, and the sheets 42 fed substantially vertically upward are guided by the guide member 45, It is sandwiched between the counter roller 46 and conveyed, and further, the leading end is guided by the conveying guide 37 and pressed against the conveying belt 51 by the leading end pressing roller 49, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately repeated with respect to the charging roller 56, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 51 alternates, that is, in a sub-scanning direction that is a circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width.

  When the paper 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  Therefore, by driving the recording head 34 according to the image signal while moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and after the paper 42 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  When performing the maintenance and recovery of the nozzles of the recording head 34, the nozzle 33 moves the carriage 33 to a position facing the maintenance and recovery mechanism 81 that is the home position, performs capping by the cap 82, and performs suction from the nozzles. By performing a maintenance and recovery operation such as idle ejection for ejecting droplets that do not contribute to image formation, image formation by stable droplet ejection can be performed.

Next, the maintenance / recovery mechanism 81 in this image forming apparatus will be described with reference to FIGS. 3 is a schematic schematic configuration diagram of the maintenance and recovery mechanism, and FIG.
In the maintenance / recovery mechanism 81, caps 82 a and 82 b held by the cap holder 212, a wiper member 83 including an elastic body, and a wiper cleaner 86 as a first wiper cleaning unit can be moved up and down on the maintenance device frame 211. (Can move up and down).

  The cap 82 is a box-shaped member having an opening on the side facing the nozzle surface of the recording head 34. The cap 82 has an elastic portion on the upper surface portion of the opening, and the opening of the nozzle can be sealed (capped) by bringing the elastic portion into contact with and closely contacting the nozzle surface. In the cap 82, an absorbent member (not shown) that is a porous sponge-like member is disposed. Accordingly, the capillary force of the absorbing member holds the ink in the cap 82 in a uniform state, and at the same time, the negative pressure discharged when the ink in the cap 82a is discharged by the suction pump 220 described later is transmitted to the entire cap. Can be made.

  A cylindrical empty discharge receiver 84 is disposed between the wiper member 83 and the suction cap 82a. The upper end of the empty discharge receiver 84 on the wiper member 83 side scrapes ink adhering to the wiper member 83. A wiper cleaner portion 85 is formed as a second wiper cleaning means for dropping and removing. When cleaning the wiper member 83, the wiper member 83 is lowered while the wiper member 83 is pressed against the wiper cleaner portion 85 by the wiper cleaner 86, so that the ink adhering to the wiper member 83 is scraped off to the empty ejection receiver 84 side. .

  Further, a tubing pump (suction pump) 220 as suction means is connected to the cap 82a closest to the printing area via a tube 219 made of an elastic member as a tube member, and only the cap 82a is suctioned (recovered). A moisturizing cap (hereinafter simply referred to as “suction cap”) is used, and the cap 82b is a simple moisturizing cap. Therefore, when performing the recovery operation of the recording head 34, the recording head 34 that performs the recovery operation is selectively moved to a position where it can be capped by the suction cap 82a.

  The suction pump 220 generates suction force on the tube 210 by repeatedly pressing and moving the suction tube 219 with a plurality of pressure members.

  On the other hand, below the caps 82a and 82b, the wiper member 83 and the like, a cam shaft 221 rotatably supported by the frame 211 is disposed, and on this cam shaft 221, a cap cam 222 for raising and lowering the cap holder 212, A wiper cam 224 for raising and lowering the wiper member 83, a roller 226 as a rotating body to which droplets discharged in the idle discharge receptacle 84 are applied, a cleaner cam 228 for swinging the wiper cleaner 86, and a carriage lock 87 are provided. A carriage lock cam 229 for raising and lowering is provided.

  In order to rotationally drive the suction pump 220 and the cam shaft 221, the rotation of the maintenance / recovery motor 231 is meshed with the motor gear 232 provided on the motor shaft 231 a and the pump gear 233 provided on the pump shaft 220 a of the suction pump 220. Yes.

  Further, an intermediate gear 236 with a one-way clutch 237 is engaged with an intermediate gear 234 integrated with the pump gear 233 via an intermediate gear 235, and the cam shaft 221 is connected to an intermediate gear 238 coaxial with the intermediate gear 236 via an intermediate gear 239. The cam gear 240 fixed to the mesh is engaged. The intermediate shaft 241 that is the rotation shaft of the intermediate gears 236 and 238 with the clutch 237 is rotatably held by the frame 211.

  In this maintenance / recovery mechanism 81, when removing ink and impurities adhering to the surface (nozzle surface) where the nozzles of the recording head 34 are formed, the motor 231 is driven to raise the wiper member 83 via the wiper cam 224. In this state, by moving the carriage 33 in the main scanning direction, the wiper member 83 wipes the nozzle surface of the recording head 34 to wipe away impurities and the like.

  Further, if the nozzles of the recording head 34 are left exposed to the outside air, the ink in the inside dries and thickens and adheres, and the ink ejection performance is deteriorated. To prevent this, the recording head 34 is prevented. When the nozzle surface is covered with the cap 82, the motor 231 is rotated, the cap 82 is raised via the cap cam 213, and the nozzle surface of the recording head 34 is capped.

  In addition, before and after the recording operation and during the recording operation, ejection of ink droplets that do not contribute to the recording operation (preliminary ejection and idle ejection) is performed on the cap 82a to maintain the nozzle ejection performance.

  Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. FIG. 2 is a block diagram of the control unit.

  The controller 500 also serves as various units such as a replenishment discharge control unit, a drying degree determination unit, a first adhesion degree determination unit, a second adhesion degree determination unit, and a head suction control unit according to the present invention. A CPU 501 that controls the CPU, a program that includes a program that causes the CPU 501 to execute control related to the supply operation and measurement of liquid consumption, a ROM 502 that stores other fixed data, a RAM 503 that temporarily stores image data and the like, A rewritable non-volatile memory 504 for holding data even while the power is cut off, and image processing for performing various signal processing and rearrangement on image data and other input / output signals for controlling the entire apparatus. And an ASIC 505 for processing.

  Further, a print control unit 508 including a data transfer unit for driving and controlling the recording head 34 and a driving signal generating unit, a head driver (driver IC) 509 for driving the recording head 34 provided on the carriage 33 side, An AC bias is applied to the charging roller 56, a main scanning motor 554 that moves and scans the carriage 33, a sub-scanning motor 555 that rotates and moves the conveyor belt 51, a motor drive unit 510 that drives the maintenance / recovery motor 231 of the maintenance / recovery mechanism 81. An AC bias supply unit 511 to supply, a pump drive unit 516 for driving the liquid feeding pump 541, and a communication provided for reading and writing data to and from a nonvolatile memory (here, EEPROM) 521 provided in the ink cartridge 10. A cartridge communication unit 522 to perform is provided.

  The control unit 500 is connected to an operation panel 514 for inputting and displaying information necessary for the apparatus.

  The control unit 500 has an I / F 506 for transmitting and receiving data and signals to and from the host side, an information processing device such as a personal computer, an image reading device such as an image scanner, an imaging device such as a digital camera, and the like. From the host 600 side via the cable or network via the I / F 506.

  Then, the CPU 501 of the control unit 500 reads and analyzes the print data in the reception buffer included in the I / F 506, performs necessary image processing, data rearrangement processing, and the like in the ASIC 505, and prints the image data. The data is transferred from the unit 508 to the head driver 509. Note that the generation of dot pattern data for image output is performed by the printer driver 601 on the host 600 side.

  The print control unit 508 transfers the above-described image data as serial data, and outputs a transfer clock, a latch signal, a control signal, and the like necessary for transferring the image data and confirming the transfer to the head driver 509. Including a D / A converter for D / A converting D / A conversion of drive pulse pattern data stored in the ROM, a voltage signal amplifier, a current amplifier, and the like, and a drive signal or a plurality of drive pulses Is output to the head driver 509.

  The head driver 509 selectively selects a drive pulse that constitutes a drive signal provided from the print control unit 508 based on image data corresponding to one line of the print head 34 that is input serially, and drops droplets on the print head 34. The recording head 34 is driven by applying it to a driving element (for example, a piezoelectric element) that generates energy to be discharged. At this time, by selecting a driving pulse constituting the driving signal, for example, dots having different sizes such as a large droplet, a medium droplet, and a small droplet can be sorted.

  The I / O unit 513 acquires information from various sensor groups 515 mounted on the apparatus, extracts information necessary for controlling the printer, a print control unit 508, a motor drive unit 510, and an AC bias supply unit. Used to control 511.

  The sensor group 515 detects the position of the paper, an optical sensor for detecting the position of the paper, a temperature sensor such as a thermistor for monitoring the temperature and humidity in the machine, a humidity detecting means, a sensor for monitoring the voltage of the charging belt, and detecting the opening and closing of the cover. The I / O unit 513 can process various sensor information.

  In addition, the control unit 500 includes time measuring means 520 that measures time.

  Next, control related to the maintenance operation in the image forming apparatus will be described with reference to the flowcharts of FIGS.

  First, referring to FIG. 6, when a printing operation command is received, a capping release operation for separating the cap 82 from the nozzle surface of the recording head 34 is performed, and then idle ejection (empty ejection before printing) is performed from the recording head 34. After that, the image forming operation is started.

  Then, during image formation (or after completion of image formation), a paper dust adhesion degree count that counts a value (paper dust adhesion degree correlation value) that correlates with the degree of paper dust adhesion in the vicinity of the nozzle as a count value for automatic recovery maintenance. , A mist adhesion degree count that counts a value that correlates with the mist adhesion degree in the vicinity of the nozzle (mist adhesion degree correlation value), a dryness count that counts a value that correlates with the in-cap drying degree (dry degree correlation value) (decap) Update the count).

  Next, it is determined whether or not the paper dust adhesion degree count is equal to or greater than a predetermined second threshold (execution threshold). Here, when the paper dust adhesion degree count is equal to or greater than the second threshold, a cleaning operation as paper dust removal cleaning is performed, and after the paper dust adhesion degree count, the mist adhesion degree count, and the drying degree count are set to “0”. To "".

  If the paper dust adhesion degree count is not equal to or greater than the second threshold value, it is determined whether or not the mist adhesion degree count is equal to or greater than a predetermined second threshold value. When the mist adhesion degree count is equal to or greater than the second execution threshold value, a cleaning operation as mist removal cleaning is performed, and after execution, the paper dust adhesion degree count, the mist adhesion degree count, and the drying degree count are reset to “0”, respectively. .

  On the other hand, if the mist adhesion degree count is not greater than or equal to the second threshold value, the process proceeds to FIG.

  And it is discriminate | determined whether a dryness count is more than a predetermined threshold value.

  At this time, if the dryness count is greater than or equal to the threshold, it is determined whether or not the paper dust adhesion degree count is greater than or equal to a predetermined first threshold. Note that the first threshold value of the paper dust adhesion degree count is a value of X% (less than X = 100) of the second threshold value, for example, a value of 50% of the second threshold value.

  If the paper dust adhesion degree count is not equal to or greater than the first threshold (less than the first threshold), it is determined whether or not the mist adhesion degree count is equal to or greater than a predetermined first threshold. Note that the first threshold value of the mist adhesion degree count is a value of Y% (Y = less than 100) of the second threshold value, for example, a value of 50% of the second threshold value.

  At this time, if the mist adhesion degree count is not equal to or greater than the first threshold (less than the first threshold), the first drying prevention maintenance operation (replenishment discharge operation) is performed. This first drying prevention maintenance operation is a replenishment discharge operation in which droplets are discharged from the recording head 34 into the cap 82a, and the suction pump 220 is started simultaneously with or prior to discharge to suck the inside of the cap 82a. is there.

  That is, the replenishment discharge operation is controlled when the dry degree correlation value in the cap is equal to or greater than the threshold value and at least one of the paper dust adhesion degree and the mist adhesion degree correlation value is less than the first threshold value.

  Thereafter, the dryness count is reset to “0”.

  On the other hand, when the paper dust adhesion degree count is equal to or greater than the first threshold value, or when the mist adhesion degree count is equal to or greater than the first threshold value, the second drying prevention maintenance operation is performed. This second drying prevention maintenance operation is an operation (cleaning operation) including a head suction operation in which the suction pump is operated in a state where the nozzle surface is capped with the cap 82a and the liquid is sucked and discharged from the nozzle.

  Thereafter, the paper dust adhesion degree count, the mist adhesion degree count, and the drying degree count are each reset to “0”.

  When the dryness count is not equal to or greater than the threshold value, it is determined whether or not the image formation is completed, and the above operation is repeated until the image formation is completed. After the image formation is completed, the recording head 34 is capped to perform the printing operation. finish.

  As described above, when both the paper dust adhesion degree count and the mist adhesion degree count are low (less than the first threshold), the first dry prevention maintenance operation with a short maintenance time is performed, thereby preventing the dry prevention maintenance. The time required can be shortened.

  Since the paper dust adhesion degree count and the mist adhesion degree count are low when the first drying prevention maintenance operation is performed, a cleaning operation (automatic recovery maintenance) based on the paper dust adhesion degree or the mist adhesion degree is performed immediately thereafter. No increase in maintenance frequency can be prevented.

  On the other hand, when either the paper dust adhesion degree count or the mist adhesion degree count is high (greater than or equal to the first threshold value), a cleaning operation (also a second drying prevention maintenance operation) is performed.

  After the cleaning operation is performed, the drying degree count, the paper dust adhesion degree count, and the mist adhesion degree count are reset (set to 0). Immediately after that, the cleaning operation based on the paper dust adhesion degree and the mist adhesion degree (automatic recovery maintenance). Can prevent the increase in overall maintenance frequency.

  Next, the first drying prevention maintenance operation (replenishment discharge operation) will be described with reference to the flowchart of FIG.

  In the first drying prevention maintenance operation, after a predetermined time stop process (process time A seconds), an in-cap replenishment discharge process (process time B seconds) for discharging droplets from the recording head 34 into the cap 82a is performed. At this time, the suction pump 220 is started at the same time as the refill discharge in the cap or before the refill discharge, and the suction in the cap (processing time C2 seconds) is performed. The replenishment discharge amount is determined in advance as a droplet amount that can reduce the degree of drying of the absorbing member 90 in the cap 82a.

  The time required for this replenishment discharge operation (first drying prevention maintenance operation) is the longer of (A + B) seconds or C2 seconds.

  Thus, replenishment discharge and suction in the cap are performed in parallel. Thereby, the processing time of the replenishment discharge operation (first drying prevention maintenance operation) can be shortened.

  This point will be described with reference to the flowchart of FIG. 9 showing the process of the comparative example.

  In this comparative example, the cap replenishment discharge process (process time B seconds) for discharging droplets from the recording head 34 into the cap 82a is performed, and then the operation of the suction pump 220 is started to perform suction within the cap (process time C1 seconds). )I do.

  The processing time in this comparative example is (B + C1) seconds.

  Therefore, the processing time of the replenishment discharge operation (first drying prevention maintenance operation) can be shortened by making the longer one of (A + B) seconds or C2 seconds shorter than (B + C1) seconds.

  Next, the cleaning operation will be described with reference to the flowchart of FIG.

  In this cleaning operation, the suction pump 220 is operated in a state where the nozzle surface of the recording head 34 is capped with the cap 82a, and a head suction operation for sucking and discharging liquid from the nozzle into the cap 82a is performed.

  After that, the nozzle surface is wiped by the wiper member 83, and after empty ejection, suction within the cap is performed.

  As described above, in this cleaning operation, when the paper dust adhesion degree count is equal to or greater than the second threshold, when the mist adhesion degree count is equal to or greater than the second threshold, the dryness count is equal to or greater than the threshold. This is executed when the adhesion degree count is equal to or greater than the first threshold value or the mist adhesion degree count is equal to or greater than the first threshold value.

  Thereby, the paper dust and mist adhering to the nozzle surface vicinity can be removed, and drying of the absorption member 90 in the cap 82a can be suppressed.

  Next, the paper dust adhesion degree count will be described with reference to the flowchart of FIG. 11 and the explanatory diagram of FIG.

  Here, information on “number of printed sheets since last time information update”, “paper type”, and “paper vertical length” (paper vertical size length) are acquired. For example, as shown in FIG. A value (degree) obtained by multiplying the determined correction coefficient (paper type coefficient) for each paper type and correction coefficient (paper vertical coefficient) for each paper vertical length (paper vertical size length) is added.

  In this case, the paper is likely to generate paper dust. For example, when the paper type is “recycled paper”, there is a high risk of paper dust generation, so the correction coefficient is set higher than that for “plain paper”. . Similarly, when the paper is long in length, the correction coefficient is set to a high value because there is a large possibility of paper dust being generated.

  Note that the paper type can be acquired from, for example, the paper type selection result of the printing condition by the user. In addition, the vertically long sheet can be acquired by the rotation amount of the conveyance belt or a sensor installed on the sheet conveyance.

  Next, the mist adhesion degree count will be described with reference to the flowchart of FIG. 13 and the explanatory diagram of FIG.

  Here, information on “discharge amount since previous information update” and “temperature / humidity” is acquired, and for example, as shown in FIG. 14, a predetermined correction coefficient ( Add the value (degree) multiplied by the temperature and humidity coefficient.

  In this case, the temperature and humidity are classified into three stages of high temperature and low humidity (HL), medium temperature and medium humidity (MM), and low temperature and low humidity (LL), and the temperature and humidity coefficient is determined respectively (not limited to three levels). . For example, when the air is dry such as in the LL environment, static electricity is likely to be generated on the conveyor belt, and mist is likely to be generated. Therefore, the correction coefficient is set higher than that in the MM environment.

  Next, the dryness count will be described with reference to the flowchart of FIG. 15 and the explanatory diagram of FIG.

  Here, information on “decap time” and “temperature / humidity” is acquired, and, for example, as shown in FIG. 15, the predetermined decap time is multiplied by a correction coefficient (temperature / humidity coefficient) determined in advance according to the temperature / humidity. Add the value (degree).

In this case, similarly to the above, the temperature and humidity are classified into three stages of high temperature and low humidity (HL), medium temperature and medium humidity (MM), and low temperature and low humidity (LL), and the temperature and humidity coefficient is determined respectively (limited to three stages). Not a thing).

  Next, an example of parameters X and Y (ratio of the first threshold value to the second threshold value) for setting the first threshold value of the paper dust adhesion degree and the mist adhesion degree will be described with reference to the explanatory diagram of FIG.

  Here, the parameters X and Y are set as fixed values in advance according to the environmental temperature and humidity. By changing the parameters X and Y according to the environmental temperature and humidity, it is possible to achieve harmony between the suppression of the increase in the frequency of dry prevention maintenance and the dry prevention effect.

  For example, under the condition that the correction coefficient of the dryness count is high, by setting the parameters X and Y to a high ratio, the degree to which the first dry prevention maintenance operation is selected increases and the maintenance time can be reduced.

  In the first anti-drying maintenance operation, only the anti-drying degree count is reset to “0” after the operation is performed. However, since the frequency of the anti-drying maintenance in the cap is high, the maintenance operation to enter next is also the anti-drying maintenance in the cap. Therefore, the cleaning operation does not start immediately, and an increase in maintenance frequency can be prevented.

  Next, other examples of parameters X and Y (ratio of the first threshold value to the second threshold value) for setting the first threshold value of the paper dust adhesion degree and the mist adhesion degree will be described with reference to the explanatory diagram of FIG.

  Here, the parameters X and Y are set by the reference environment (MM environment) and theoretical numerical calculation.

  Even in this case, it is possible to achieve harmony between the suppression of the increase in the frequency of dry prevention maintenance and the dry prevention effect.

  In the present application, the “paper” is not limited to paper, but includes OHP, cloth, glass, a substrate, etc., and means a material to which ink droplets or other liquids can be attached. , Recording media, recording paper, recording paper, and the like. In addition, image formation, recording, printing, printing, and printing are all synonymous.

  The “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. “Formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply causing a droplet to land on the medium). ) Also means.

  The “ink” is not limited to an ink unless otherwise specified, but includes any liquid that can form an image, such as a recording liquid, a fixing processing liquid, or a liquid. Used generically, for example, includes DNA samples, resists, pattern materials, resins, and the like.

  In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  Further, the image forming apparatus includes both a serial type image forming apparatus and a line type image forming apparatus, unless otherwise limited.

10 Ink cartridge (main tank)
33 Carriage 34, 34a, 34b Recording head (liquid ejection head)
35 Head tank 36 Supply tube 81 Maintenance recovery mechanism 82a Cap (for suction)
220 Suction pump (suction means)
500 Control unit

Claims (10)

A recording head having nozzles for discharging droplets;
A cap member having an absorbing member for capping the nozzle surface of the recording head and absorbing liquid therein;
A suction means for performing suction from the cap member;
Replenishment discharge control means for discharging droplets from the recording head into the cap member and performing replenishment discharge operation for starting driving of the suction means at the same time as discharge or prior to discharge;
A drying degree determining means for determining whether or not a drying degree correlation value correlated with a drying degree in the cap member is equal to or greater than a threshold;
A first threshold value in which at least one of a paper dust adhesion degree correlation value that correlates with the degree of paper dust adhesion to the nozzle surface and a mist adhesion degree correlation value that correlates with the degree of mist adhesion to the nozzle surface is predetermined. First adhesion degree determining means for determining whether or not the above has been reached,
The replenishment / discharge control means performs the replenishment / discharge operation when the dryness degree correlation value is equal to or greater than a threshold value and at least one of the paper dust adhesion degree correlation value and the mist adhesion degree correlation value is less than the first threshold value. An image forming apparatus that controls the above. A head suction control means for controlling a head suction operation for operating the suction means in a state where the nozzle surface is capped with the cap member to suck and discharge liquid from the nozzle;
The head suction control unit is configured to perform the head suction when the dryness degree correlation value is equal to or greater than the threshold value, and at least one of the paper dust adhesion degree correlation value and the mist adhesion degree correlation value is equal to or greater than the first threshold value. The image forming apparatus according to claim 1, wherein the operation is controlled. Second adhesion degree determination for determining whether or not at least one of the paper dust adhesion degree correlation value and the mist adhesion degree correlation value is equal to or higher than a predetermined second threshold value with an adhesion degree higher than the first threshold value. Having means,
The head suction control unit controls the head suction operation when at least one of the paper dust adhesion degree correlation value and the mist adhesion degree correlation value is equal to or greater than the second threshold value. Item 3. The image forming apparatus according to Item 2.   The image according to any one of claims 1 to 3, wherein the dryness degree correlation value is a non-capping cumulative time obtained by accumulating a time during which the nozzle surface of the recording head is not capped by the cap member. Forming equipment.   The image forming apparatus according to claim 4, wherein the dryness degree correlation value is a value corrected according to an environmental temperature.   The image forming apparatus according to claim 1, wherein the paper dust adhesion degree correlation value is an accumulated number of printed sheets obtained by accumulating the number of printed sheets or an accumulated amount of feeding obtained by accumulating the amount of feeding of a recording medium.   The image forming apparatus according to claim 6, wherein the paper dust adhesion degree correlation value is a value corrected according to a type of the recording medium.   The image forming apparatus according to claim 1, wherein the mist adhesion degree correlation value is a cumulative droplet discharge amount obtained by accumulating the droplet discharge amount.   The image forming apparatus according to claim 8, wherein the mist adhesion degree correlation value is a value corrected according to an environmental temperature. The first adhesion degree determining means determines whether or not both the paper dust adhesion degree correlation value and the mist adhesion degree correlation value are equal to or higher than the predetermined first threshold value,
The replenishment discharge control means controls the replenishment discharge operation when the dryness degree correlation value is equal to or greater than a threshold value, and the paper dust adhesion degree correlation value and the mist adhesion degree correlation value are less than the respective threshold values,
The head suction control means controls the head suction operation when the dryness degree correlation value is greater than or equal to a threshold value and the paper dust adhesion degree correlation value and the mist adhesion degree correlation value are greater than or equal to the first threshold value, respectively. The image forming apparatus according to claim 2, wherein the image forming apparatus is performed.

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