JP4488342B2 - Liquid ejecting apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a liquid ejection apparatus and an image forming apparatus.

  As various image forming apparatuses such as a printer, a facsimile, a copying apparatus, a complex machine of these, a plotter, and the like, there are some equipped with a liquid discharge apparatus using a liquid droplet discharge head for discharging liquid droplets of a recording liquid.

  In such an image forming apparatus, when unnecessary foreign matter such as liquid or paper dust adheres to the nozzle surface of the head, the image quality may be deteriorated by bending in the droplet discharge direction. For example, for example, fine droplets (ink mist) other than the droplets involved in recording are generated, or droplets that have landed on a recording medium (also referred to as paper, recording medium, transfer paper, etc.) rebound. As a result, when liquid adheres to the nozzle surface and accumulates around the nozzle, bending in the discharge direction or inability to discharge occurs.

  In this way, unnecessary liquid adhering to the nozzle surface accumulates due to mist generated when droplets are ejected during recording or rebound from the recording medium, and foreign objects such as paper dust also come close to the recording head and paper during recording. It is thought that it adheres when moving relatively. Therefore, the nozzle surface is cleaned by providing a wiper blade that wipes the nozzle surface.

  Further, in an image forming apparatus using a liquid ejection device, the liquid in the liquid path may become thickened due to evaporation of moisture or the like, resulting in nozzle clogging, resulting in unstable ejection or ejection failure. In view of this, a cap for capping the nozzle surface is provided, and the nozzle surface is wiped after the inside of the cap is sucked with a suction pump to suck up the thickened liquid from the nozzle.

As described above, in an image forming apparatus using a liquid discharge apparatus, an apparatus that maintains and recovers the performance of a recording head that discharges a recording liquid is indispensable. As described above, the maintenance device for maintaining and recovering the performance of the head keeps the nozzle surface highly sealed in order to prevent thickening and sticking of the recording liquid in the vicinity of the nozzle due to natural evaporation of the ink that is the recording liquid. Caps such as a moisturizing cap for covering, a suction cap for sucking and discharging the thickened recording liquid from the nozzle (sometimes also used as a moisturizing cap), and a recording liquid adhering to the nozzle surface A wiper blade that is a wiping means for wiping off and removing the ink, and an empty discharge receptacle for discharging the droplets that do not contribute to image formation.
JP 2001-205816 A JP 2003-1839 A JP-A-10-202904

  By the way, even if such a reliability maintaining and recovering mechanism is provided, if the foreign matter such as liquid or paper powder remains on the nozzle surface without being wiped, the liquid will increase in viscosity due to evaporation of water, and this As a result, foreign matter may adhere to and accumulate strongly, and even if it is wiped after being left, it may not be easily removed. In particular, when the liquid contains a dye or auxiliary solvent that tends to thicken or crystallize, the liquid is evaporated from the nozzle, causing a phenomenon that the thickened liquid swells in the vicinity of the nozzle, and the nozzle is blocked by the thickened liquid. , Ejection failure may occur.

In order to solve the problem in the conventional reliability maintaining and recovering apparatus, for example, Patent Document 4 solves the problem that a bubble is caused to grow by a flushing (empty discharge) operation, which may cause a discharge failure. For this reason, it is disclosed that after the cleaning (suction + wiping) is finished, the ink in the head is vibrated to promote the dissolution of bubbles in the ink.
Japanese Patent No. 3293765

Further, in Patent Document 5, in order to surely remove the solidified ink of an ink jet recording head that uses ink that tends to be thickened and formed into a film, a second signal for causing ink to bleed out is generated in the uncleaned area during the cleaning period. It is disclosed that the ink solidified on the surface of the nozzle plate is dissolved by the ink that has been output to the element and exuded, and is reliably removed by cleaning.
JP-A-7-96604

Further, in Patent Document 6, in order to recover the ink thickening at the nozzle tip and the clogging of the nozzle, the energy is such that ink droplets protrude from the orifice plate surface almost simultaneously with wiping the nozzle plate (orifice plate) with a wiping blade. It is disclosed to apply a drive pulse to the generating member.
JP 2003-39689 A

  As a colorant for an ink used in an ink jet recording apparatus as an image forming apparatus, dye ink was mainly used from the viewpoints of good color development and high reliability. There is a tendency to use a pigment ink using a pigment such as carbon black in order to give the recorded image light resistance and water resistance. Also, there is a tendency to increase the ink viscosity for the purpose of increasing the degree of freedom of ink formulation and for preventing bleeding after landing on plain paper.

  When such a high viscosity pigment ink was used, it was confirmed that the viscosity of the ink greatly changed depending on the temperature. For example, an ink having a viscosity of 8 cp in a 22 ° C. environment has a high viscosity exceeding 15 cp at 10 ° C., and a low viscosity of about 5 cp at 32 ° C. According to experiments by the present inventors, it has been clarified that there is a problem that it is difficult to stably wipe such ink.

  That is, the present inventor observed the state of the nozzle surface after printing 500 J6 charts in a 10 ° C. environment. At this time, before starting printing, cleaning (suction recovery + wiping) was performed to clean the nozzle surface, and then printing was performed in the bidirectional printing mode.

  A photograph of this result is shown in FIG. As a result, it was confirmed that mist was accumulated on one side of the nozzle, and that mist was accumulated on the downstream side of the nozzle in relation to the wiping direction. In this case, if the mist is simply generated, as described above, since the printing is performed by bidirectional printing, the mist is generated only in one direction of the wiping direction from the nozzle as shown in FIG. I can't explain the accumulation. Moreover, since the suction recovery is performed immediately before the printing evaluation, it is not a problem of thickening due to water evaporation.

  Presuming from this phenomenon, at first glance, it seems that the seeds (seeds) that generate and deposit mist remain in the vicinity of the nozzle even though they can be wiped cleanly. However, when the experiment was repeated, it was confirmed that the occurrence of this phenomenon was probabilistic, and that the situation changed when the combination of the head and the wiper blade was changed.

  That is, mist deposition occurs stochastically due to subtle differences such as the water repellency of the nozzle surface, the contact angle of the wiper, and the ink state. Since this is a stochastic phenomenon, it is difficult to reduce such a phenomenon by managing specifications. Further, according to experiments, it has been confirmed that this tendency occurs more frequently in pigment inks than dye inks, particularly in pigment inks containing a resin component. On the other hand, even when the same ink jet recording apparatus was printed in a 22 ° C. environment or a 32 ° C. environment, mist deposition as shown in FIG. 13 did not occur. However, the discharge energy is appropriately changed according to the environmental temperature.

  The conventional maintenance / recovery device cannot cope with the phenomenon described above. That is, the one described in Patent Document 4 is for solving the problem caused by the idle discharge, and cannot cope with the stochastic mist accumulation. Further, in the case of the one described in Patent Document 5, ink is oozed out of nozzles that are not wiped, that is, only pressure that breaks the meniscus is generated, and it corresponds to stochastic mist accumulation. Can not do it.

  In the case of the one described in Patent Document 6, when the nozzle surface is wiped by the wiping blade, the drive pulse is applied to the energy generating member almost at the same time as the ink droplets protrude from the nozzle surface. The thickened ink inside is slightly raised and is to be removed by wiping, and it cannot cope with stochastic mist accumulation.

  The present invention has been made in view of the above problems. It is an object of the present invention to provide a liquid ejection apparatus and an image forming apparatus that can reduce the accumulation of mist that occurs probabilistically.

In order to solve the above-described problem, a liquid ejection apparatus according to the present invention includes a fine driving unit that applies a pulsating pressure to a liquid of a head so that a droplet is not ejected, and a temperature detection unit that detects an environmental temperature. provided, when wiping the nozzle surface with a wiping means maintaining and recovering unit, based on the detection result of the temperature detection means, Do added pressure pulsation is Lawah Ipingu when the detected temperature is a predetermined temperature below a predetermined When the temperature exceeds a predetermined temperature, wiping is performed without applying a pulsating pressure .

  An image forming apparatus according to the present invention includes the liquid ejection device according to the present invention.

  According to the liquid ejection apparatus and the image forming apparatus including the same according to the present invention, the nozzle surface is wiped by the wiping means of the maintenance recovery means while applying a pulsating pressure to the liquid of the head only when the environmental temperature is equal to or lower than the predetermined temperature. Therefore, it is possible to reduce the mist accumulation that occurs stochastically, and in particular, it is possible to reduce the mist accumulation that occurs at a low temperature when a high-viscosity recording liquid or a pigment-based recording liquid is used. become.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an image forming apparatus according to the present invention including a maintenance device for a liquid ejection apparatus according to the present invention will be described with reference to FIG. FIG. 1 is an explanatory perspective view of the image forming apparatus as viewed from the front side.

  The image forming apparatus includes an apparatus main body 1, a paper feed tray 2 for loading paper loaded in the apparatus main body 1, and a discharge for stocking paper on which an image is recorded (formed) mounted on the apparatus main body 1. The apparatus main body 1 further includes a cartridge loading portion 6 that protrudes forward from the front surface 4 and is lower than the upper surface 5 on one end side of the front surface 4 of the apparatus main body 1. An operation unit 7 such as operation keys and a display is arranged on the upper surface of the display. A main tank (hereinafter referred to as “ink cartridge”) 10 that is a liquid storage tank as a liquid replenishing unit is replaceably mounted on the cartridge loading unit 6, and has a front cover 8 that can be opened and closed. Yes.

  Next, the mechanism of the image forming apparatus will be described with reference to FIGS. 2 is a schematic configuration diagram for explaining the overall configuration of the mechanism portion, FIG. 3 is a plan view for explaining a main portion of the mechanism portion, and FIG. 3 is a schematic perspective view for explaining a main portion of the mechanism portion.

  A carriage 33 is slidably held in a main scanning direction by a guide rod 31 and a stay 32 which are horizontally mounted on left and right side plates 21A and 21B (see FIG. 3) constituting the frame 21, and is not shown. The motor moves and scans in the direction indicated by the arrow in FIG. 3 (carriage scanning direction: main scanning direction).

  In this carriage 33, a plurality of recording heads 34, which are ink jet heads that are droplet discharge heads for discharging recording droplets (ink droplets), are arranged in a direction crossing a plurality of nozzles in the main scanning direction, and ink It is mounted with the droplet discharge direction facing downward.

  Here, the recording head 34 is composed of a droplet discharge head. For example, the recording head 34 y that discharges yellow (Y) droplets, the recording head 34 m that discharges magenta (M) droplets, and cyan (C). The recording head 34c discharges a black droplet and the recording head 34b discharges a black (Bk) droplet. The “recording head 34” does not distinguish between colors.

  The head configuration is not limited to these examples, and it may be configured using one or a plurality of recording heads having one or a plurality of nozzle rows that eject droplets of one or a plurality of colors.

  The droplet discharge head constituting the recording head 34 includes a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a metal phase caused by a temperature change. A shape memory alloy actuator using a change, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging droplets can be used.

  A driver IC is mounted on the recording head 34 and is connected to a control unit (not shown) via a harness (FPC cable) 22 as shown in FIG.

  In addition, the carriage 33 is equipped with sub tanks 35y, 35m, 35c, and 35k for each color for supplying the recording liquid of each color to each recording head 34 (referred to as “sub tank 35” when colors are not distinguished). Yes. The sub tanks 35y, 35m, 35c, and 35k are configured to supply the recording liquid from the ink cartridges 10 of the above-described colors via the recording liquid supply tube 37 that includes four tubes.

  As shown in FIG. 3, the ink cartridge 10 is accommodated in the cartridge loading unit 6, and the cartridge loading unit 6 is provided with a supply pump unit 23 for feeding the recording liquid in the ink cartridge 10. ing.

  The recording liquid supply tube 37 from the ink cartridge loading unit 6 to the sub tank 35 is fixed and held by the main body side holder 25 on the rear plate 21 </ b> C constituting the frame 21 in the middle of turning. Further, it is fixed on the carriage 33 by the fixing rib 26.

  On the other hand, as a paper feed unit for feeding the papers 42 stacked on the paper stacking unit (bottom plate) 41 of the paper feed tray 3, a half-moon roller (feed) 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.

  As a transport unit for transporting the paper 42 fed from the paper feed unit on the lower side of the recording head 34, a transport belt 51 for transporting the paper 42 by electrostatic adsorption, and a paper feed unit The counter roller 52 for transporting the paper 42 fed through the guide 45 while sandwiching it between the transport belt 51 and the paper 42 fed substantially vertically upward are changed by approximately 90 ° and copied onto the transport belt 51. A conveyance guide 53 for adjusting the pressure and a tip pressure roller 55 urged toward the conveyance belt 51 by a pressing member 54. In addition, a charging roller 56 that is a charging unit for charging the surface of the conveyance belt 51 is provided.

  Here, the conveyance belt 51 is an endless belt, and is configured to be looped around the conveyance roller 57 and the tension roller 58 in the belt conveyance direction of FIG. The charging roller 56 is disposed so as to come into contact with the surface layer of the conveyor belt 51 and to be rotated by the rotation of the conveyor belt 51, and 2.5N is applied to both ends of the shaft as a pressing force.

  In addition, a guide member 61 is disposed on the back side of the conveyor belt 51 so as to correspond to a printing area by the recording head 54. The upper surface of the guide member 61 protrudes closer to the recording head 34 than the tangent line of the two rollers (the conveyance roller 57 and the tension roller 58) that support the conveyance belt 51. As a result, the conveyance belt 51 is pushed up and guided by the upper surface of the guide member 61 in the printing region, so that highly accurate flatness is maintained.

  Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 71 for separating the paper 42 from the transport belt 51, a paper discharge roller 72, and a paper discharge roller 73 are provided. A paper discharge tray 3 is provided below the paper discharge roller 72. Here, the height from between the paper discharge roller 72 and the paper discharge roller 73 to the paper discharge tray 3 is increased to some extent in order to increase the amount that can be stored in the paper discharge tray 3.

  A double-sided paper feeding unit 81 is detachably attached to the back surface of the apparatus body 1. The double-sided paper feeding unit 81 takes in the paper 42 returned by the reverse rotation of the transport belt 51, reverses it, and feeds it again between the counter roller 52 and the transport belt 51. A manual paper feed unit 82 is provided on the upper surface of the duplex paper feed unit 81.

  Further, as shown in FIG. 3, the non-printing area on one side in the scanning direction of the carriage 33 includes the maintenance / recovery device according to the present invention for maintaining and recovering the state of the nozzles of the recording head 34. A maintenance / recovery mechanism (hereinafter referred to as “subsystem”) 91 is provided.

  The subsystem 91 includes caps 92a to 92d for capping each nozzle surface of the recording head 34 (referred to as “cap 92” when not distinguished), and a wiper that is a blade member for wiping the nozzle surface. A blade 93, an empty discharge receiver 94 for receiving droplets for discharging a droplet that does not contribute to recording in order to discharge the thickened recording liquid, and a wiper blade integrally formed with the empty discharge receiver 94. A wiper cleaner 95 which is a cleaning member for removing the recording liquid adhering to 93, and a cleaner roller 96 which constitutes a cleaner means for pressing the wiper blade 93 against the wiper cleaner 95 side when the wiper blade 93 is cleaned are provided.

  Further, as shown in FIG. 3, in the non-printing area on the other side in the scanning direction of the carriage 33, idle ejection for ejecting liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like is performed. An empty discharge receiver 98 for receiving droplets when performing the operation is disposed, and the empty discharge receiver 98 is provided with an opening 99 and the like along the nozzle row direction of the recording head 34.

  In the ink jet recording apparatus configured as described above, the paper 22 is separated and fed from the paper feed tray 2 one by one, and the paper 22 fed substantially vertically upward is guided by the guide 25, and the conveyance belt 31 and the counter roller 32, and the tip is guided by the transport guide 33 and pressed against the transport belt 31 by the tip pressure roller 35, and the transport direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately repeated from the high-voltage power supply to the charging roller 56 by a control circuit (not shown), that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 51 alternates, that is, In the sub-scanning direction, which is the circumferential direction, plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the sheet 42 is electrostatically attracted to the conveyance belt 51, and the sheet 42 is moved in the sub-scanning direction by the circular movement of the conveyance belt 51. Be transported.

  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.

  Further, while waiting for printing (recording), the carriage 33 is moved to the subsystem 91 side, the recording head 34 is capped by the cap 92, and the nozzles are kept in a wet state to prevent ejection failure due to ink drying. In addition, the recording liquid is sucked from the nozzle while the recording head 34 is capped by the cap 92 (referred to as “nozzle suction” or “head suction”), and a recovery operation is performed to discharge the thickened recording liquid and bubbles. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. As a result, the stable ejection performance of the recording head 34 is maintained.

  An outline of the configuration of the subsystem 91 in this image forming apparatus will be described with reference to FIGS. 4 is an explanatory plan view of the main part of the system, FIG. 5 is a schematic schematic configuration diagram of the system, and FIG. 6 is an explanatory diagram on the right side of FIG.

  A frame (maintenance device frame) 111 of this subsystem includes two cap holders 112A and 112B which are cap holding mechanisms, a wiper blade 93 which is a wiping member including an elastic body as a cleaning means, a carriage lock 115, and the like. Are held up and down (movable up and down). Further, an empty discharge receiver 94 is disposed between the wiper blade 93 and the cap holder 112 </ b> A, and the wiper blade 93 is a cleaning member for the empty discharge receiver 94 from the outside of the frame 111 in order to clean the wiper blade 93. A wiper cleaner 118 that is a cleaner means including a cleaner roller 96 that is a cleaning member to be pressed against the wiper cleaner 95 side is swingably held.

  The cap holders 112A and 112B (referred to as “cap holder 112” when not distinguished from each other) hold two caps 92a and 92b and caps 92c and 92d for capping the nozzle surfaces of the two recording heads 34, respectively. Yes.

  Here, a tubing pump (suction pump) 120 as a suction means is connected to the cap 92a held by the cap holder 112A closest to the printing area via a flexible tube 119, and the other caps 92b, 92c, 92d does not connect the tubing pump 120. That is, only the cap 92a is a suction (recovery) and moisturizing cap (hereinafter simply referred to as “suction cap”), and the other caps 92b, 92c, and 92d are all merely moisturizing caps. 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 92a.

  A cam shaft 121 rotatably supported by the frame 111 is disposed below the cap holders 112A and 112B. Cap cams 122A and 122B for raising and lowering the cap holders 112A and 112B are disposed on the cam shaft 121. A wiper cam 124 for raising and lowering the wiper blade 93, a carriage lock cam 125 for raising and lowering the carriage lock 115 via the carriage lock arm 117, and an empty liquid droplet that is idlely discharged in the idle discharge receiver 94. A roller 126 as a rotating body, which is a discharge landing member, and a cleaner cam 128 for swinging the wiper cleaner 118 are provided.

  Here, the cap 92 is moved up and down by the cap cams 122A and 122B. The wiper blade 93 is moved up and down by the wiper cam 124, and the wiper cleaner 118 is advanced when the wiper blade 124 is lowered. Ink adhering to 93 is scraped off into the empty ejection receiver 94.

  The carriage lock 115 is urged upward (in the lock direction) by a compression spring (not shown), and is raised and lowered via a carriage lock arm 117 driven by a carriage lock cam 125.

  In order to rotationally drive the tubing pump 120 and the camshaft 121, the motor gear 132 provided on the motor shaft 131a rotates with the motor 131 and the pump gear 133 provided on the pump shaft 120a of the tubing pump 120 is meshed. An intermediate gear 136 with a one-way clutch 137 is engaged with an intermediate gear 134 integral with 133 via an intermediate gear 135, and the intermediate gear 138 coaxial with the intermediate gear 136 is fixed to the camshaft 121 via the intermediate gear 139. The cam gear 140 is engaged. An intermediate shaft 141 that is a rotation shaft of the intermediate gears 136 and 138 with the clutch 137 is rotatably held by the frame 111.

  The cam shaft 121 is provided with a home position sensor cam 142 for detecting the home position. When the cap 92 comes to the lowermost end by a home position sensor (not shown) provided in the subsystem 91, a home position lever is provided. (Not shown) is activated, the sensor is opened, and the home position of the motor 131 (other than the pump 120) is detected. Note that when the power is turned on, the position moves up and down (up and down) regardless of the position of the cap 92 (cap holder 112), the position is not detected until the movement starts, and the position is determined after detecting the home position of the cap 92 (on the way up). To the bottom end. Thereafter, the carriage moves left and right, returns to the cap position after position detection, and the recording head 34 is capped.

  Next, an example of a droplet discharge head constituting the recording head 34 will be described with reference to FIGS. 7 is a cross-sectional explanatory view along the longitudinal direction of the liquid chamber of the head, and FIG. 8 is an explanatory cross-sectional view along the short direction of the liquid chamber of the head.

  This droplet discharge head has a flow path plate 241 formed of a single crystal silicon substrate, a vibration plate 242 bonded to the lower surface of the flow path plate 241, and a nozzle plate 243 bonded to the upper surface of the flow path plate 241. Thus, the nozzle 245 that discharges ink droplets as droplets is a pressure chamber 246 that is an ink flow path that communicates via the nozzle communication path 245a, and a common liquid chamber 248 for supplying ink to the pressure chamber 246. An ink supply path 247 serving as a fluid resistance portion communicating with the ink supply port 249 is formed.

  Drive means (pressure generating means, actuator means) for pressurizing the ink in the pressurizing chambers 46 corresponding to the pressurizing chambers 246 on the outer surface side (opposite side of the liquid chamber) of the vibration plate 242. A laminated piezoelectric element 252 as an electromechanical conversion element is bonded, and the piezoelectric element 252 is bonded to the base substrate 253. Further, between the piezoelectric elements 252, support columns 254 are provided corresponding to the partition walls 241 a between the pressurizing chambers 246 and 246. Here, the piezoelectric element member is divided into comb-teeth by performing slit processing by half-cut dicing, and each piezoelectric element is formed with a piezoelectric element 252 and a column portion 254. The structure of the support column 254 is the same as that of the piezoelectric element 252, but it is a simple support because no drive voltage is applied.

  Further, the outer peripheral portion of the diaphragm 242 is bonded to the frame member 244 with an adhesive 250 including a gap material. The frame member 244 is formed with a recess serving as a common liquid chamber 248 and an ink supply hole (not shown) for supplying ink to the common liquid chamber 248 from the outside. The frame member 244 is formed of, for example, an epoxy resin or polyphenylene sulfite by injection molding.

  Here, the flow path plate 241 is formed by, for example, subjecting a single crystal silicon substrate having a crystal plane orientation (110) to anisotropic etching using an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), so that the nozzle communication path 245a, The pressurization chamber 246 and the ink supply path 247 are formed with recesses and holes. However, the present invention is not limited to a single crystal silicon substrate, and other stainless steel substrates, photosensitive resins, and the like can also be used.

  The vibration plate 242 is formed of a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). Other metal plates, resin plates, or a joining member between a metal and a resin plate are used. It can also be used. The diaphragm 242 forms a thin portion (diaphragm portion) 255 for facilitating deformation and a thick portion (island convex portion) 256 for joining to the piezoelectric element 252 in a portion corresponding to the pressurizing chamber 246. At the same time, a thick portion 257 is formed at a portion corresponding to the column portion 254 and a joint portion with the frame member 244, and the flat surface side is adhesively joined to the flow path plate 241. Further, the thick part 257 is joined to the column part 254 and the frame member 244 with the adhesive 250. Here, the diaphragm 242 is formed by nickel electroforming having a two-layer structure. In this case, the diaphragm portion 255 has a thickness of 3 μm and a width of 35 μm (one side).

  The nozzle plate 243 forms a nozzle 245 having a diameter of 10 to 35 μm corresponding to each pressurizing chamber 246 and is bonded to the flow path plate 241 with an adhesive. The nozzle plate 243 may be made of a metal such as stainless steel or nickel, a combination of a metal and a resin such as a polyimide resin film, silicon, or a combination thereof. Here, it forms with the Ni plating film | membrane etc. by the electroforming method. Further, the inner shape (inner shape) of the nozzle 243 is formed in a horn shape (may be a substantially columnar shape or a substantially frustum shape), and the hole diameter of the nozzle 245 is about 20 to about the diameter of the ink droplet outlet side. 35 μm. Furthermore, the nozzle pitch of each row was 150 dpi.

  Further, a water repellent treatment layer having a water repellent surface treatment (not shown) is provided on the nozzle surface (surface in the ejection direction: ejection surface) of the nozzle plate 243. Examples of the water-repellent treatment layer include PTFE-Ni eutectoid plating, fluororesin electrodeposition coating, vapor-deposited fluororesin (e.g., fluorinated pitch), silicon resin / fluorine resin A water-repellent treatment film selected according to the ink physical properties such as baking after solvent application is provided to stabilize the ink droplet shape and flight characteristics and to obtain high-quality image quality.

  The piezoelectric element 252 includes a lead zirconate titanate (PZT) piezoelectric layer 261 having a thickness of 10 to 50 μm / layer and an internal electrode layer 262 made of silver and palladium (AgPd) having a thickness of several μm / layer. The internal electrodes 262 are alternately stacked, and are electrically connected to the individual electrodes 263 and the common electrode 264 which are the end electrodes (external electrodes) of the end surfaces alternately. The pressurizing chamber 246 is contracted and expanded by expansion and contraction of the piezoelectric element 252 whose piezoelectric constant is d33. The piezoelectric element 252 expands when a drive signal is applied and is charged, and contracts in the opposite direction when the electric charge charged in the piezoelectric element 252 is discharged.

  Note that the end face electrode on one end face of the piezoelectric element member is divided by dicing by half-cut to form individual electrodes 263, and the end face electrode on the other end face is not divided by the restriction by notching or the like and is divided by all the piezoelectric elements 252. The conductive common electrode 264 becomes conductive.

  The FPC cable 265 is connected to the individual electrode 263 of the piezoelectric element 252 by solder bonding, ACF (anisotropic conductive film) bonding or wire bonding in order to give a drive signal. A drive circuit (driver IC) provided on a relay circuit board (not shown) provided on the carriage 33 for selectively applying a drive waveform to each piezoelectric element 252 is connected to the FPC cable 265. Further, the common electrode 264 is connected to the ground (GND) electrode of the FPC cable 265 by providing an electrode layer at the end of the piezoelectric element.

  In the ink jet head configured as described above, for example, by applying a drive waveform (pulse voltage of 10 to 50 V) to the piezoelectric element 252 in accordance with a recording signal, the piezoelectric element 252 is displaced in the stacking direction and vibrates. The ink in the pressurizing chamber 246 is pressurized through the plate 242 to increase the pressure, and ink droplets are ejected from the nozzles 245.

  Thereafter, the ink pressure in the pressurizing chamber 246 decreases with the end of ink droplet ejection, and a negative pressure is generated in the pressurizing chamber 246 due to the inertia of the ink flow and the discharge process of the driving pulse, and the ink filling process is started. Transition. At this time, ink supplied from an ink tank (not shown) flows into the common liquid chamber 248 and is filled from the common liquid chamber 248 through the ink supply port 249 through the fluid resistance portion 247 into the pressurizing chamber 246.

  In the recording head 34 using this droplet discharge head, two rows of nozzles 45 are provided with a half-pitch shift at a 150 dpi pitch in each row so that printing can be performed with a resolution of 300 dpi in the sub-scanning direction without interlacing. Further, the ink droplet size Mj to be ejected is realized by four drive gradations Mj = 0, 3, 9, and 37 (pl) by the drive waveform applied to the piezoelectric element 252.

  Further, as described above, a relay circuit board for relaying a signal and a drive voltage given from the main circuit board via the cable 22 to connect to the recording head 34 is provided on the carriage 33 described above. A temperature sensor for detecting the environmental temperature is provided on the circuit board. The temperature sensor may be provided on the main body circuit board, but it is preferable to provide the temperature sensor on the relay circuit board on the carriage 33 in order to detect the temperature of the head nozzle surface more accurately.

Next, an outline of the control unit of the image forming apparatus will be described with reference to the block diagram of FIG.
The control unit 280 includes a CPU 281 that controls the entire apparatus, a ROM 282 that stores programs executed by the CPU 281 and other fixed data, a RAM 283 that temporarily stores image data, and the like, while the apparatus is powered off. And a non-volatile memory (NVRAM) 284 for holding data, an image processing for performing various signal processing and rearrangement on image data, and an ASIC 285 for processing input / output signals for controlling the entire apparatus. Yes.

  The control unit 280 also includes an I / F 286 for transmitting and receiving data and signals to and from the host, a head drive control unit 287 and a head driver 288 for controlling the drive of the recording head 34, and a main scanning motor 290. A main scanning motor driving unit 291 for driving the sub-scanning motor 292, a sub-scanning motor driving unit 293 for driving the sub-scanning motor 292, a sub-system driving unit 294 for driving the motor 131 of the sub-system 91, A sub-tank drive unit 295 for driving a drive unit 296 that drives an air release valve 297 for releasing the atmosphere, a temperature sensor 298 for detecting the environmental temperature provided on the carriage 33, and detection electrodes (not shown) of the sub-tank 55. Equipped with I / O 299 for inputting detection signals and detection signals from various sensors (not shown) There. The control unit 280 is connected to an operation panel 300 for inputting and displaying information necessary for the apparatus.

  The control unit 280 receives print data and the like from the host side such as an information processing apparatus such as a personal computer, an image reading apparatus such as an image scanner, and an imaging apparatus such as a digital camera, via the cable or the network by the I / F 286.

  The CPU 281 reads and analyzes the print data in the reception buffer included in the I / F 286, performs necessary image processing, data rearrangement processing, and the like in the ASIC 285, and transfers the image data to the head drive control unit 287. To do. The generation of dot pattern data for image output may be performed by storing font data in the ROM 282, for example, or image data is developed into bitmap data by a host-side printer driver and transferred to this apparatus. You may do it.

  When the head drive control unit 287 receives image data (dot pattern data) corresponding to one row of the recording head 34, the dot pattern data for one row is serialized to the head driver 288 in synchronization with the clock signal. Data is transmitted, and a latch signal is transmitted to the head driver 288 at a predetermined timing.

  The head drive control unit 287 includes a ROM (which can also be configured by a ROM 282) storing pattern data of a drive waveform (drive signal), and a D / A converter for D / A conversion of drive waveform data read from the ROM. A waveform generation circuit including an A converter and a drive waveform generation circuit including an amplifier and the like are included.

  The head driver 288 also receives a clock signal from the head drive controller 287 and serial data as image data, and a latch circuit that latches the register value of the shift register with a latch signal from the head drive controller 287. A level conversion circuit (level shifter) that changes the output value of the latch circuit, an analog switch array (switch means) that is controlled to be turned on / off by the level shifter, and the like, and controls on / off of the analog switch array. As a result, a required waveform included in the drive waveform is selectively applied to the piezoelectric element 252 which is the actuator means of the recording head 34 to drive the head 34.

  Furthermore, the CPU 280 takes in the detection signal of the temperature sensor 298 via the I / O 296 and detects the environmental temperature.

  Here, one or a plurality of driving waveforms (three types for realizing four gradations in the present embodiment) to which a pressure (discharge pressure) for discharging a droplet from the nozzle 245 is applied by applying to the piezoelectric element 252; A drive waveform including a drive waveform (fine drive waveform) to which pulsating pressure is applied to such an extent that ink in the pressurizing chamber 246 is not ejected (fine drive waveform) is generated within one drive cycle. Is selected and applied to the piezoelectric element 252 of the head 34. As described above, drive waveform data for generating such a drive waveform is stored in a ROM or the like, and is generated by performing D / A conversion, amplification, or the like.

  That is, the fine drive means for applying a pulsating pressure to the extent that liquid droplets are not ejected to the liquid of the head is configured by the control unit 280 and the piezoelectric element 252 of the head 34. In this way, by using the fine driving means also as the electromechanical conversion means that is a pressure generating means for ejecting droplets, it is possible to apply the pulsating pressure to the ink during wiping without adding an extra configuration. In addition, thermal type heads that use bubbles generated by heating resistors and electrostatic type heads that use electrostatic force also discharge liquid droplets to liquid separately from pressure generation means (actuator means, drive means) for droplet discharge. It goes without saying that the present invention can be applied by providing means for applying a pressure that pulsates to such an extent that it does not pulsate.

  In addition, one or a plurality of (three types in order to achieve four gradations in this embodiment) discharge driving waveform data for applying a discharge pressure, and a minute pressure for pulsating to the extent that ink in the pressurizing chamber 246 is not discharged. It is also possible to store drive waveform data and select and output pulsation waveform data during wiping.

Next, the wiping operation in the image forming apparatus configured as described above will be described with reference to FIG.
As shown in FIG. 10, the control unit 280 of the image forming apparatus detects the environmental temperature by taking in a detection signal from the temperature sensor 298 when performing the reliability maintenance / recovery operation by the subsystem 91 and performing the wiping operation. Then, it is determined whether or not the detected environmental temperature is equal to or lower than a predetermined temperature. When the detected environmental temperature is equal to or lower than a predetermined temperature, the pressure chamber 256 applies a pulsating pressure that does not discharge droplets to the piezoelectric element 252 of the recording head 34 that is wiped by the head drive control unit 287. A fine driving waveform applied to the recording liquid is selected and applied.

  Then, as described above, the wiping operation for wiping the nozzle surface of the recording head 34 is performed by moving the carriage 33 relative to the wiper blade 93 with the wiper blade 93 raised.

  Specifically, as shown in FIG. 11A, a fine driving waveform is applied to the piezoelectric element of the recording head 34 so that the recording liquid 301 in the pressurizing chamber 246 is white enough not to be discharged as a droplet from the nozzle 245. Pulsate in the direction indicated by the pull arrow. Thereby, the interface of the recording liquid in the nozzle 245 is activated. Wiping is performed by moving the wiper blade 93 in the direction of the arrow relative to the nozzle surface 234a.

  At this time, a meniscus 302 is formed in a pulsating state in the region of the nozzle 245 through which the wiper blade 93 has passed, as shown in FIG. Further, as shown in FIG. 6C, after the wiper blade 93 passes through the nozzle 245, the pulsation is stopped.

  Here, as the pulsation drive waveform, as shown in FIG. 11, the pulsation is given without discharging the droplets with respect to the voltage (discharge voltage) of the discharge drive waveform that gives the pressure (discharge pressure) for discharging the droplets. A drive waveform in which the voltage (pulsation voltage) of the fine drive waveform that gives pressure (pulsation pressure) is 50% is given. The driving waveform was a “pulling waveform (Pull)” based on the resonance period of the individual liquid chamber (pressurizing chamber 246), and the driving frequency was 4 kHz.

  The fine drive waveform is not limited to the “pulling waveform (Pull)”, but care must be taken to prevent the voltage value from being discharged depending on the waveform used. Although the discharge voltage varies depending on the drive waveform depending on how the resonance pressure is used, the fine drive waveform is a similar waveform (the time interval Pw etc. is the same), and a voltage of 30% to 60% of the discharge voltage is a fine drive voltage. It is preferable to make it. It is preferable to set the discharge voltage of the waveform as a reference.

  In this case, if the voltage value of the fine driving waveform exceeds 60% of the ejection voltage, ink is applied to the nozzle surface after wiping due to the pressure through the recording liquid, electrical disturbance, slight difference in contact with the wiper blade, etc. The probability of overflowing is increased, which is not preferable. Conversely, when the voltage value of the fine drive waveform is less than 30% of the ejection voltage, the effect of forming a meniscus at the correct position cannot be expected.

  That is, by setting the pulsating pressure applied to the recording liquid during wiping within a range of 30 to 60% of the discharge pressure, it is possible to prevent the recording liquid from overflowing to the nozzle surface and to stably form a meniscus. Sufficient energy can be applied to the mist, thereby reducing wiping problems such as unwiping, reducing mist accumulation caused by wiping defects, and improving long-term reliability.

  As for the discharge waveform, in order to keep the discharge speed Vj and droplet volume Mj constant, the discharge voltage is changed according to the environmental temperature (so-called temperature compensation), but the fine drive voltage applied during wiping needs to be changed as well. . Since the ink viscosity changes depending on the environmental temperature, changing the input energy in the same way as the discharge voltage is effective in forming the meniscus stably in order to activate the ink interface during wiping. is there.

  According to the experiment of the present invention, it is preferable to change the applied voltage during wiping with respect to the environmental temperature at the same ratio as the temperature compensation of the discharge voltage. That is, it is preferable to set the voltage value of the fine driving waveform so as not to change the ratio between the discharge voltage and the fine driving voltage at each environmental temperature.

  In this way, by controlling the voltage value of the drive waveform for generating the pulsating pressure applied to the recording liquid during wiping according to the detection result of the environmental temperature, the recording liquid overflows on the nozzle surface even if the environmental temperature changes. In order to prevent this from happening and to form a meniscus in a stable manner, sufficient energy can be applied, thereby reducing wiping problems such as unwiping and reducing mist accumulation caused by wiping defects. And long-term reliability can be improved.

Next, specific examples will be described.
(Example ink 1)
Black ink:
KM-9036 (manufactured by Toyo Ink) (self-dispersing pigment) 50% by weight
Glycerin 10% by weight
1,3 butanegio 15% by weight
2-ethyl-1,3-hexanediol 2% by weight
2-pyrrolidone 2% by weight
Surfactant (Specific Example 1-8) 1% by weight
Silicone antifoaming agent KS508 (self-emulsifying type) (manufactured by Shin-Etsu Chemical Co., Ltd.)
0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore size of 1.2 μm to obtain Example Ink 1.
This Example Ink 1 had a viscosity in a 22 ° C. environment of about 7 cp.

(Example ink 2)
Preparation of polymer solution A A 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel was sufficiently purged with nitrogen gas, then 11.2 g of styrene, 2.8 g of acrylic acid, lauryl 12.0 g of methacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer and 0.4 g of mercaptoethanol were mixed and heated to 65 ° C. Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxylethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, azobismethylvalero A mixed solution of 2.4 g of nitrile and 18 g of methyl ethyl ketone was dropped into the flask over 2.5 hours. After dropping, a mixed solution of 0.8 g of azobismethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobismethylvaleronitrile was added and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a concentration of 50%.

Preparation of pigment-containing polymer fine particle aqueous dispersion Polymer solution A 28 g; I. 26 g of Pigment Yellow 97, 13.6 g of a 1 mol / L aqueous potassium hydroxide solution, 20 g of methyl ethyl ketone and 13.6 g of ion-exchanged water were sufficiently stirred, and then kneaded using a roll mill. The obtained paste was put into 200 g of ion-exchanged water and sufficiently stirred, and then methyl ethyl ketone and water were distilled off using an evaporator to obtain an aqueous dispersion of yellow polymer fine particles. The average particle size of the polymer fine particles of the dispersion obtained after the centrifugal separation treatment was 80 nm, and the solid content was 20% by weight.

Yellow ink:
Yellow polymer fine particle dispersion 40% by weight
Glycerin 5% by weight
Diethylene glycol 15% by weight
2,2,4-Trimethyl-1,3-pentanediol 2% by weight
1% by weight of Na salt of surfactant (specific example 2-8)
Silicone defoamer KS531 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, followed by filtration through a membrane filter having an average pore size of 1.2 μm to obtain Example Ink 2.
This ink had a viscosity of about 5.5 cp in a 22 ° C. environment.

(Example ink 3)
Preparation of pigment-containing polymer fine particle aqueous dispersion I. An aqueous dispersion of magenta polymer fine particles was obtained in the same manner except that the pigment red 122 was used. The average particle size of the polymer fine particles of the dispersion obtained after the centrifugal separation treatment was 150 nm, and the solid content was 20% by weight.

Magenta ink:
Dispersion of magenta polymer fine particles 50% by weight
Glycerin 5% by weight
Diethylene glycol 15% by weight
2,2,4-Trimethyl-1,3-pentanediol 2% by weight
1% by weight of Na salt of surfactant (specific example 2-8)
Silicone defoamer KS531 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore size of 1.2 μm to obtain Example Ink 3.
This ink had a viscosity of about 5.5 cp in a 22 ° C. environment.

(Example ink 4)
Preparation of pigment-containing polymer fine particle aqueous dispersion I. An aqueous dispersion of cyan polymer fine particles was obtained in the same manner except that Pigment Blue 15: 3 was used. The average particle size of the polymer fine particles of the dispersion obtained after the centrifugal separation treatment was 115 nm, and the solid content was 20% by weight.

Cyan ink:
Cyan polymer fine particle dispersion 40% by weight
Glycerin 5% by weight
Diethylene glycol 15% by weight
2,2,4-Trimethyl-1,3-pentanediol 2% by weight
1% by weight of Na salt of surfactant (specific example 2-7)
Silicone defoamer KS531 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, followed by filtration with a membrane filter having an average pore size of 1.2 μm to obtain Example Ink 4.
This ink had a viscosity of about 5.5 cp in a 22 ° C. environment.

(Comparative Example Ink 1)
A black ink was produced as Comparative Example Ink 1 in which the viscosity of the environment at 22 ° C. was adjusted to about 3 cp by changing the ratio of glycerin and ion-exchanged water in the black ink of Example ink 1.

(Comparative Example Ink 2)
In the yellow ink of Example ink 2, the ratio of glycerin and ion-exchanged water was changed, and the viscosity in a 22 ° C. environment was adjusted to about 3 cp to produce a yellow ink as Comparative Example Ink 2.

(Comparative Example Ink 3)
In the magenta ink of Example ink 3, the ratio of glycerin and ion-exchanged water was changed, and the viscosity in a 22 ° C. environment was adjusted to about 3 cp to produce magenta ink as Comparative Example Ink 3.

(Comparative Example Ink 4)
In the cyan ink of Example Ink 4, the ratio of glycerin and ion exchange water was changed, and the viscosity in a 22 ° C. environment was adjusted to about 3 cp to prepare a cyan ink as Comparative Example Ink 4.

  Since each ink has a different viscosity in a 22 ° C. environment, the input energy is changed when the printing evaluation is performed by the ink jet recording apparatus. The input energy at which the droplet velocity Vj is Vj = 7 (m / s) was selected for each ink. The droplet velocity Vj is obtained by simple calculation by measuring the time for the droplet to reach 1 mm ahead from pressure generation (= energy input).

  In addition, in the following evaluation, printing is performed by changing the environmental temperature of the ink jet recording apparatus, but for each temperature, the input energy (drive voltage) is set so that the droplet velocity Vj is also Vj = 7 (m / s). Temperature compensation is implemented.

  Therefore, using the ink produced as described above, when performing fine driving wiping (using fine driving wiping) while applying pulsating pressure according to the present invention, the conventional wiping is not used. The evaluation was performed in two ways (when fine driving wiping was not used).

(Evaluation)
After performing nozzle cleaning in each environment of 10 ° C., 15 ° C., 22 ° C., and 30 ° C., 500 J6 charts are printed. Thereafter, the nozzle surface is observed to confirm the mist accumulation state. This was repeated 5 times, and the case where the state of the nozzle surface was the worst was judged by ○, ×, Δ. In addition, (circle): There is no mist, X: There exists mist accumulation clearly, (triangle | delta): The mist exists in some places. The results are shown in Table 1.

  In this case, the material of the wiper blade of the wiping mechanism and the protruding length of the blade are such that no wiping is left in the example ink 1 of 22 ° C. environment.

  As can be seen from the results in Table 1, when fine drive wiping is not used, inks with high viscosity like Example inks 1 to 4 are prone to wiping defects at low temperatures, and if left as they are, nozzles are lowered. There is a high possibility of connection.

  In this case, if the viscosity is lowered as in Comparative Examples 1 to 4, the mist accumulation is relatively reduced, but in terms of images, the inks of Examples 1 to 4 are used in terms of color bleeding and feathering. It will be inferior.

  Further, it can be seen that the mist is more easily deposited in the color inks of the example inks 2 to 4 containing the resin than the black ink of the example ink 1 of the self-dispersing pigment. This is related to the difficulty of wiping when a resin is contained. When the resin is contained, the ink tends to remain so as to be adsorbed to the nozzle during wiping.

  On the other hand, when fine driving wiping of the present invention is performed, mist is hardly deposited even at low temperatures. This is because the ink is activated by the fine driving. Thus, the problem of mist deposition around the nozzle during low temperature wiping is improved.

  Thus, by wiping the nozzle surface with the wiping means of the maintenance / recovery means while applying pulsating pressure to the liquid of the head so that the liquid droplets are not ejected, the meniscus is stably formed, Wiping problems can be reduced, and mist accumulation that occurs stochastically can be reduced, and long-term reliability can be improved. In particular, when a highly viscous recording liquid or a pigment-based recording liquid is used, it is possible to reduce mist deposition that occurs at low temperatures.

  In particular, ink with a viscosity of 5 cp or more in an environment of 22 ° C. has a large viscosity change in the normal printing guarantee range, and it is difficult to stably wipe. However, wiping while applying pulsating pressure to the ink stabilizes the meniscus. Thus, it is possible to reduce wiping problems such as unwiping, and to reduce mist accumulation caused by wiping failure, thereby obtaining high long-term reliability. In addition, since the restriction on the viscosity is reduced, the degree of freedom of ink formulation is increased, and as a result, a high-quality image can be obtained. Furthermore, since it has a high viscosity, it is possible to use ink that suppresses permeation after landing on paper and has good color bleeding and feathering.

  Even when the recording liquid contains a resin dispersant, wiping while applying pulsating pressure to the ink forms a meniscus in a stable manner, thus preventing mist from being deposited due to poor wiping in a low temperature environment. As a result, it is possible to use a recording liquid containing a resin dispersant that can suppress scattering of pigments and the like on the paper surface and improve color development. Thus, the image quality can be improved.

  Further, according to the results of Table 1 and the subsequent examination, the vicinity of 15 ° C. is a gray zone in which mist accumulation due to defective wiping occurs, and if it exceeds 20 ° C., the mist is also removed by conventional wiping (wiping without fine driving). The problem of deposition did not occur significantly.

  Therefore, wiping while applying a pulsating pressure only when the detected environmental temperature is equal to or lower than a predetermined temperature based on the temperature detection result eliminates wasted energy consumption. In this case, the predetermined temperature is preferably 17 ° C., which can surely prevent a wiping failure at a low temperature where mist accumulation due to a wiping failure is likely to occur, and a 22 ° C. environment. Since the wiping conditions set below work effectively, wiping conditions can be easily obtained.

  Conversely, wiping may be performed even in the case of an environmental temperature exceeding a predetermined temperature, that is, while applying a pulsating pressure regardless of the environmental temperature. In this way, it is not necessary to change the processing sequence in the temperature environment, so that debugging is easy and the productivity of the farm is improved. However, the voltage value of the fine drive waveform is preferably temperature compensated as described above.

  The liquid ejection apparatus according to the present invention can be applied to an image forming apparatus such as a facsimile apparatus, a copying apparatus, and a printer / fax / copier multifunction machine in addition to an inkjet printer. Furthermore, the present invention can also be applied to a liquid ejection apparatus that ejects a liquid (recording liquid) other than ink, for example, a resist or a DNA sample in the medical field.

FIG. 2 is a perspective explanatory view seen from the front side showing an example of an image forming apparatus including a liquid ejection apparatus according to the present invention. FIG. 2 is a schematic explanatory diagram illustrating an example of a mechanism unit of the image forming apparatus. It is a schematic plane explanatory drawing of the mechanism part. It is principal part top explanatory drawing of the subsystem containing the maintenance recovery apparatus of the mechanism part. It is a typical schematic block diagram of the system. It is right side explanatory drawing of FIG. FIG. 3 is an explanatory cross-sectional view of a main part along a liquid chamber longitudinal direction showing an example of a recording head of the image forming apparatus. It is sectional explanatory drawing in alignment with the liquid chamber transversal direction of the head. FIG. 2 is a block explanatory diagram illustrating an overview of a control unit of the image forming apparatus. It is a flowchart explaining an example of the process at the time of wiping by the control part. It is explanatory drawing with which it uses for description at the time of fine drive wiping. It is explanatory drawing with which it uses for description of the relationship between an ejection voltage and a fine drive voltage. It is a figure which shows an example of the result of having observed the mode of the nozzle surface after printing 500 sheets of J6 charts in a 10 degreeC environment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 2 ... Paper feed tray 3 ... Paper discharge tray 6 ... Ink cartridge loading part 10 ... Ink cartridge 33 ... Carriage 34 ... Recording head 35 ... Sub tank 51 ... Conveyor belt 91 ... Subsystem 92a-92d ... Cap 93 ... Wiper Blade 94 ... Empty discharge receptacle 95 ... Wiper cleaner 96 ... Cleaner roller 111 ... Maintenance device frame 112A, 112B ... Cap holder 118 ... Wiper liner 119 ... Tube 120 ... Tubing pump 121 ... Cam shaft 122A, 122B ... Cap cam 124 ... Wiper cam 128 ... Cleaner cam 245 ... Nozzle 252 ... Piezoelectric element 287 ... Head drive controller

Claims (2)

In a liquid discharge apparatus comprising: a droplet discharge head for discharging a recording liquid droplet from a nozzle; a cap for capping the nozzle surface of the head; and a maintenance recovery means including a wiping means for wiping the nozzle surface of the head.
Fine driving means for applying a pulsating pressure to the liquid of the head so as not to eject droplets;
Temperature detecting means for detecting the environmental temperature,
When wiping the nozzle surface with a wiping means of the maintaining and recovering unit, based on a detection result of said temperature detecting means, the detection temperature Do applying pressure to said pulsation when the following predetermined given temperature Lawah A liquid ejecting apparatus characterized by performing wiping without applying the pulsating pressure when the temperature exceeds the predetermined temperature .   An image forming apparatus for forming an image by ejecting liquid droplets, comprising the liquid ejecting apparatus according to claim 1.