JP2010131934A - Liquid delivery device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid delivery device constituted to generate no defective delivery of a liquid droplet, even when a bubble is mixed into an ink supply flow channel. <P>SOLUTION: This liquid delivery device includes a liquid delivery head 34 for delivering the liquid droplet from a nozzle, a liquid main tank arranged attachably and detachably in a prescribed position, a head tank for replenished with a liquid from the liquid main tank via a liquid supply route, and for supplying the liquid to the liquid delivery head, and a filter part 100 having a filter chamber 300 built in with a filter 303 for filtrating the liquid supplied to the liquid delivery head 34. In the liquid delivery device, the filter chamber 300 includes a portion 304a for guiding the bubble to the head tank located in an upstream of the filter 303 along a droplet moving direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejection apparatus and an image forming apparatus, and more particularly to a structure for preventing ejection failure due to bubbles generated in a flow path in which droplets move.

  As is well known, a printer, a facsimile machine, a copying machine, and an image forming apparatus provided with a combination of these functions include a liquid ejection apparatus having a recording head composed of a liquid ejection head that ejects liquid droplets such as ink. The configuration used is known.

  In a liquid ejection apparatus, an image is formed by adhering or penetrating droplets ejected from a recording head while conveying a recording medium such as recording paper.

  The target of the recording medium includes not only the recording paper described above but also a material capable of adhering or penetrating liquids such as fibers such as intention, leather and metal, resin, glass, wood and ceramics.

  In an image forming apparatus provided with a liquid discharge device, in order to stabilize the ink discharge operation from the liquid discharge head, the ink in the liquid discharge head is maintained at a predetermined negative pressure (acts on the ink in the liquid discharge head). It is important to keep the pressure to be a predetermined negative pressure). For this reason, in general, an ink supply system that supplies ink to the liquid discharge head is provided with a negative pressure generating means, and ink to which negative pressure is applied by the negative pressure generating means is supplied to the liquid discharge head.

  As such a negative pressure generating means, a configuration in which a negative pressure is formed by utilizing the capillary phenomenon of a sponge-like ink absorber housed in the ink tank, or an ink tank so as to maintain the negative pressure in the ink tank There has been known a configuration provided with a biasing means such as a spring for biasing a flexible member forming at least a part of the ink cartridge to the outside of the ink tank. Further, as another negative pressure generating means, there is also known a configuration in which an ink tank is disposed below the liquid discharge head and a negative pressure is applied to the ink using a water head difference.

  Incidentally, in a general inkjet image forming apparatus, a filter is provided in a flow path between the main tank and the liquid discharge head so that foreign matters and bubbles in the ink do not flow into the liquid discharge head.

  Usually, a filter having a filtration performance that captures almost 100% of foreign matter having a size of several μm is used. For this reason, the filter section has a large fluid resistance.

  In addition, in an off-carriage type inkjet image forming apparatus using a head tank, an ink supply flow path for supplying ink from the main tank to the head tank takes into consideration the routing, assembly, and maintainability in the apparatus. In many cases, a flexible resin tube is used. In many cases, a flexible film is provided as a negative pressure generating means in the head tank. However, as these are used for a long time, air gradually permeates from the outside, and eventually the air enters the head tank. Also in an on-carriage inkjet image forming apparatus, air existing in the main tank, air mixed in the supply channel when the main tank is attached or detached, air dissolved in the ink, etc. pass through the supply channel. As a result, it is accumulated in the filter unit.

  As a configuration for suppressing the accumulation of air in the filter unit, an air release valve means for switching the inside of the head tank to a sealed or open state is provided, and the air in the head tank is separated from the ink supply channel and the exhaust channel. A configuration for discharging is proposed (for example, Patent Document 1). In this configuration, since the air in the head tank is discharged separately from the ink supply flow path and the exhaust flow path, it is possible to prevent the air from accumulating in the head tank.

  Further, as a configuration different from the configuration capable of exhausting as described above, a filter chamber for forming a corner portion toward the upper end portion of the head tank is disposed, and a filter for removing foreign matter so as to cover the filter chamber There has been proposed a configuration in which members are arranged and an ink outlet opening from the head tank to the liquid ejection head is opened at a corner formed in the upper part of the filter chamber (for example, Patent Document 2). In this configuration, bubbles remaining in the filter chamber can be guided to the ink outlet using the buoyancy action.

  Furthermore, as another configuration, a part of the filter chamber is inclined with respect to the horizontal direction between an ink supply path whose one end communicates with the ink cartridge and a through hole which communicates with the ink jet recording head. There has been proposed a configuration in which a filter chamber is formed and a filter plate is disposed so as to cross diagonally so that ink passes through the entire surface of the filter plate (for example, Patent Document 3).

JP-A-2005-169664 JP 2001-277535 A JP 9-216375 A

  However, in the configuration provided with the head tank having the air release valve means disclosed in Patent Document 1, air bubbles mixed in the flow path between the main tank and the head tank are discharged. However, there is a possibility that bubbles that form a film in contact with the filter unit, particularly the filter, from the head tank cannot be easily discharged.

  Further, in the configuration provided with the head tank described in Patent Document 2, bubbles are guided to the outlet of the head tank, so when ink is ejected from the liquid ejection head, the bubbles are generated. Thus, the ink is supplied into the liquid discharge head in preference to the ink in the head tank. For this reason, the ink is not ejected from the nozzles, and an abnormal image may be generated.

  Further, in the configuration disclosed in Patent Document 3, the pressure loss in the filter portion is reduced when the ink flow rate from the ink tank to the recording head is increased. However, when bubbles are mixed, the mixed bubbles are mixed. Stagnate in the filter section. For this reason, the ink does not flow in the stagnant portion of the bubbles, the pressure loss in the disadvantageous other portion increases, and there is a possibility that the ink supply may not be in time.

  An object of the present invention is to prevent the problem of liquid droplet ejection even when bubbles are mixed in the ink supply flow path, in view of the problems in the above-described conventional liquid ejecting apparatus, in particular, problems due to the stagnation of bubbles in the filter section. An object of the present invention is to provide a liquid ejection apparatus having a configuration that can be used and an image forming apparatus using the liquid ejection apparatus.

  In order to achieve this object, the invention according to claim 1 is directed to a liquid discharge head that discharges droplets from a nozzle, a removable liquid main tank disposed at a predetermined position, and a liquid supply path from the liquid main tank. A liquid comprising: a head tank that receives liquid replenishment via a liquid and that supplies a liquid to the liquid discharge head; and a filter unit having a filter chamber in which a filter for filtering the liquid supplied to the liquid discharge head is incorporated. In the ejection device, the filter chamber is provided with a portion for guiding bubbles to a head tank located upstream of the filter in the moving direction of the droplet.

  According to a second aspect of the present invention, in the droplet discharge device according to the first aspect, the filter is welded vertically to the horizontal direction.

  According to a third aspect of the present invention, in the liquid droplet ejection device according to the first aspect, the filter is welded obliquely with respect to the horizontal direction, and the flow path connecting the filter unit and the head tank includes: It has a slope for introducing the mixed bubbles into the head tank.

  According to a fourth aspect of the present invention, in the liquid droplet ejection device according to the third aspect, the flow path connecting the filter and the filter unit and the head tank has an angle of 10 ° to 30 ° with respect to the horizontal direction. It is characterized by that.

  According to a fifth aspect of the present invention, in the liquid ejection device according to any one of the first to fourth aspects, a bubble storage chamber is provided for trapping bubbles in a flow path connecting the filter portion and the nozzle. It is characterized by having.

  A sixth aspect of the present invention is the liquid ejection apparatus according to any one of the first to fifth aspects, wherein the filter is a filter made of a sintered metal fiber nonwoven fabric.

  A seventh aspect of the present invention is the liquid ejection apparatus according to any one of the first to fifth aspects, wherein the filter is a filter made of a metal body formed of a twilled weave.

  According to an eighth aspect of the present invention, in the liquid ejection apparatus according to any one of the first to fifth aspects, the filter is a resin filter.

  According to a ninth aspect of the present invention, in the liquid ejection device according to any one of the first to eighth aspects, the filter is capable of capturing particles having a particle size of 10 μm or more. It is characterized by being.

  A tenth aspect of the present invention is the liquid ejection apparatus according to any one of the first to ninth aspects, further comprising a pressure control means for controlling the atmospheric pressure in the head tank.

  According to an eleventh aspect of the present invention, in the liquid ejection device according to the tenth aspect, the pressure control means includes a packing attached to the opening of the head tank, and a contact configured to be able to contact and separate from the packing. And a pressurizing control unit that pressurizes the contact / separation member to control the atmospheric pressure in the head tank so that the contact / separation member opens or seals the hole of the packing and allows air to enter and exit the head tank. And an air release cap for fixing them.

  According to a twelfth aspect of the present invention, in the liquid ejecting apparatus according to the eleventh aspect, the contact / separation member is a metal ball, and the pressurizing control means is an electromagnetic solenoid lever.

  A thirteenth aspect of the present invention is the liquid ejection apparatus according to the eleventh aspect, wherein the contact / separation member is a metal sphere, and the pressure control means is a non-contact type ferromagnetic material. .

  A fourteenth aspect of the present invention is an image forming apparatus using the liquid discharge apparatus according to any one of the first to thirteenth aspects, wherein ink is used as the liquid.

  According to the present invention, since the bubbles accumulated in the filter unit can be guided to the head tank by the buoyancy, the bubbles that are stagnating in the filter can be kept away from the filter without using an external structure such as a pump. As a result, the movement of the ink can be prevented.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is an external view of an image forming apparatus using a night liquid ejecting apparatus according to the present invention.

  The image forming apparatus shown in FIG. 1 has an apparatus main body 1, a paper feed tray 2 for loading paper mounted on the apparatus main body 1, and a detachably mounted on the apparatus main body 1 to record images ( And a paper discharge tray 3 for stocking the formed paper.

  Further, a cartridge loading for loading an ink cartridge that protrudes from the front surface to the front side of the apparatus main body 1 and is lower than the upper surface is provided at one end side of the front surface of the apparatus main body 1 (side of the paper supply / discharge tray section). The cartridge loading unit 4 has an operation / display unit 5 provided with operation buttons and a display.

  The cartridge loading unit 4 includes a plurality of ink cartridges 10k each containing inks of different color materials, such as black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink. 10c, 10m, and 10y (referred to as “ink cartridge 10” when colors are not distinguished) can be inserted and loaded from the front side of the apparatus main body 1 toward the rear side. Has a front cover (cartridge cover) 6 that can be opened and closed when the ink cartridge 10 is attached and detached.

  Next, the mechanism part of this liquid discharge apparatus will be described with reference to FIGS. 2 is a schematic side view illustrating the outline of the mechanism, and FIG. 3 is an explanatory plan view of the main part.

  In FIG. 3, a carriage 33 is slidably held in a main scanning direction by a guide rod 31 which is a guide member horizontally mounted on the left and right side plates 21A and 21B and a stay 32, and a timing belt is interposed by a main scanning motor (not shown). In FIG. 3, the scanning is moved in the direction indicated by the arrow (carriage main scanning direction).

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

  In FIG. 2, each of the liquid discharge heads 34 has two nozzle rows, one nozzle row of the liquid discharge head 34a is a black (K) droplet, and the other nozzle row is a cyan (C) droplet. In the liquid discharge head 34b, one nozzle row can discharge magenta (M) droplets, and the other nozzle row can discharge yellow (Y) droplets. Ink droplets can also be ejected.

  As an ink jet head constituting the liquid discharge head 34, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. A shape memory alloy actuator using an electrostatic force, an electrostatic actuator using an electrostatic force, and the like provided as pressure generating means for generating a pressure for discharging a droplet can be used.

  Further, the carriage 33 is provided with head tanks 35a and 35b as liquid storage containers composed of the liquid containers according to the present invention for supplying ink of each color corresponding to the nozzle rows of the liquid discharge head 34 (when not distinguished from each other). "Head tank 35"). As described above, the head tank 35 is supplied with ink of each color from the ink cartridge 10 of each color mounted in the cartridge loading unit 4 via the ink supply tube 36 of each color. The cartridge loading 4 is provided with a supply pump unit 24 for feeding ink in the ink cartridge 10.

  On the other hand, as shown in FIG. 2, the sheets 42 are separated one by one from the sheet stacking section 41 as a sheet feeding section for feeding the sheets 42 stacked on the sheet stacking section (pressure plate) 41 of the sheet feeding tray 2. A half paddle (feeding roller) 43 to be fed and a separation pad 44 made of a material having a large friction coefficient are provided opposite to the feeding roller 43, and this separation pad 44 is urged toward the feeding roller 43 side.

  In order to feed the paper 42 fed from the paper feed unit to the lower side of the liquid discharge 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 49 are provided. And a conveying belt 51 which is a conveying means for electrostatically attracting the fed paper 42 and conveying it at a position facing the liquid ejection 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 of FIG. 3 when the transport roller 52 is rotationally driven through timing by a sub-scanning motor (not shown).

  As a paper discharge unit for discharging the paper 42 recorded by the liquid discharge head 34, a separation claw 27 for separating the paper 42 from the transport belt 51, a paper discharge roller 28, and a paper discharge roller 29 are provided. A paper discharge tray 3 is provided below the paper discharge roller 28.

  A duplex unit 38 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 38 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 38 is a manual feed tray 39.

  As shown in FIG. 3, a maintenance / recovery mechanism 81 including a recovery means for maintaining and recovering the nozzle state of the liquid ejection head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction. .

  The maintenance / 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 liquid discharge head 34, and nozzle surfaces. A wiper blade 83 that is a blade member for wiping the ink, and an empty discharge receiver 84 that receives a droplet when performing an empty discharge that discharges a droplet that does not contribute to recording in order to discharge the thickened ink. Yes.

  As shown in FIG. 3, in the non-printing area on the other side in the scanning direction of the carriage 33, the liquid used when performing the idle ejection for ejecting the liquid droplets that do not contribute to the recording in order to discharge the ink that has been thickened during the recording or the like. An empty discharge receiver 88 for receiving droplets is disposed, and the empty discharge receiver 88 is provided with an opening 89 along the nozzle row direction of the liquid discharge head 34.

  In the ink liquid ejecting apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feeding tray 2, and the sheets 42 fed substantially vertically upward are guided by the guide 45, and the transport belt 51 and the counter It is sandwiched between the rollers 46 and conveyed, and 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.

  By driving the liquid ejection head 34 in accordance with the image signal in the process of moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and 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, the carriage 33 moves to the maintenance / recovery mechanism 81 side during printing (recording) standby. When the carriage 33 moves, the liquid ejection head 34 is capped by the caps 82 (a to d). By maintaining the nozzle in a wet state, ejection failure due to ink drying is prevented. Further, with the liquid ejection head 34 being capped by the cap 82, the ink is sucked from the nozzle by a suction pump (not shown) (referred to as “nozzle suction” or “head suction”), and the ink or bubbles that are thickened are discharged. Perform the action. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the liquid ejection head 34 is maintained.

Next, a head tank in this image forming apparatus will be described with reference to FIGS.
4 is a perspective view of the liquid discharge head unit, FIG. 5 is a side view of the same, FIG. 6 is a side view of the head tank body (container body), FIG. 7 is an exploded perspective view of the same, and FIG. FIG. 9 is a schematic perspective view of the container body viewed from the side opposite to FIG. 7, and FIG. 9 is a bottom view of the container body.

  In FIG. 4, the liquid discharge head unit includes one liquid discharge head 34, a head tank 35 for supplying recording liquids of the same color or different colors to the two nozzle rows of the one liquid discharge head 34, and a head tank 35. And a filter unit 101 interposed between the liquid discharge head 34 and flexible cables 102 and 102 for transmitting signals for driving the actuator means of the liquid discharge head 34 are drawn out from the liquid discharge head 34. ing.

  The head tank 35 is formed with ink storage portions 201A and 201B which are recording liquid storage portions on both sides of the tank body 202 (referred to as “ink storage portion 201” when not distinguished from each other. The same applies to the following members). In addition, a flexible film-like member (flexible film-like member) 211 is bonded or sealed to the openings of these ink storage portions 201A and 201B and sealed. Further, a spring (spring) 212 that is an elastic member for urging the film-like member 211 outward is disposed between the tank main body 202 and the film-like member 211 inside the ink containing portions 201A and 201B. These film-like members 211 and elastic members 212 constitute a negative pressure generating mechanism. Further, negative pressure detection levers 213A and 213B that are displaced in accordance with the displacement of the film-like member 211 are attached to the container body 202 so as to be swingable. The film-like member 211 has a bulging portion 211a corresponding to the spring 212 at the center, and is formed in a shape that is substantially Mt. Fuji when viewed from the side.

  The film-like member 211 may have a single-layer structure, but may have a two-layer structure in which different types of first and second layers are laminated, for example, a structure in which polyethylene and nylon film-like members are laminated, or the first layer is silica. It can be set as the structure which formed the vapor deposition layer.

  At the upper part of the tank body 202, an air release passage 203 for opening the ink containing portion 201 to the atmosphere is formed, and air release mechanisms 204A and 204B as pressure control means for opening and closing the air release passage 203 are provided. Yes. A partition wall 205 is provided between the top surface of the ink container 201 and the atmosphere opening passage 203, and a small hole communicating the ink container 201 and the atmosphere opening passage 203 with the partition wall 205. 206 is formed. The small holes 206 form a meniscus due to surface tension even when the head tank 35 is shaken by vibrations during transportation, etc., depending on the viscosity and prescription of the recording liquid stored in the ink storage unit 201, and the recording liquid reaches the atmosphere communication path 203. Has a shape that does not penetrate.

  An ink supply port 207 for supplying ink to the ink storage unit 201 is formed in the tank main body 202, and a tube 36 is connected to the ink supply port 207 by a connecting member 208. In addition, two detection electrodes 216 for detecting ink in the ink containing portion 201 are provided on the upper portion of the container main body 202.

  On the bottom surface of the tank body 202, supply ports 217A and 217B for individually supplying ink from the ink storage portions 201A and 201B to the filter unit 101 are formed at the ends of the ink storage portions 201A and 201B, respectively. In order to arrange the supply ports 217A and 217B in the central portion, the ink containing portions 201A and 201B are formed with bulged portions 218A and 218B that swell in the other containing portion.

  Next, the atmosphere release mechanism in the head tank 35 will be described with reference to FIGS. FIG. 10 is a plan sectional view of the air release mechanism portion, and FIG. 11 is a perspective view of the same.

  The atmosphere release mechanism 204 is integrally provided with a hollow holder attachment portion 221 that forms an atmosphere release path 220 that communicates with the inside and outside of the container body 202 through the atmosphere communication path 203 laterally at the top of the container body 202. .

  A valve seat 223 is held on the outer end surface of the holder mounting portion 221 while being sandwiched between the holder 222 mounted on the holder mounting portion 221 and coil spring 225 is pushed in the air release path 220 in a direction to be pressed against the valve seat 223. A ball 224 as a valve body pressed and energized with is stored. These valve seats 223, balls 224, and coil springs 225 constitute valve means capable of opening and closing the atmosphere release path 220. Note that seal members 226 are interposed on both surfaces of the valve seat 223. In FIG. 10, the atmosphere opening mechanism 204A shows a state where the atmosphere opening path 220 is opened, and the atmosphere opening mechanism 204B shows a state where the atmosphere opening path 220B is closed.

  The holder 222 has a holding portion 232 that holds a mounting portion 231 to be attached to the holder mounting portion 221 and an opening member 241 to be described later, and forms an outlet of the atmosphere opening path 220.

  The holding portion 232 is attached to the holder attachment portion 221 by fitting a notch 222 a (see also FIG. 13) formed on the outer peripheral portion of the attachment portion 231 with a protrusion 221 a provided on the holder attachment portion 221. In addition, a reinforcing rib 231a is formed on the outer peripheral surface of the mounting portion 231 of the holder 222 to compensate for a decrease in strength due to the provision of the notch portion 222a.

  An opening member 241 capable of communicating with the atmosphere through an outlet portion formed by the holding portion 232 is attached to the holding portion 232 of the holder 222 so as to advance and retreat. The opening member 241 presses the ball 224 against the urging force of the coil spring 225 to open the valve means, and opens the atmosphere opening path 220 to the atmosphere through an outlet portion formed by the holding portion 232. Be able to.

  The release member 241 is pressed by a pressing portion 242 that is inserted into the holding portion 232 of the holder 222 and presses the ball 224 constituting the valve means, and an air release pin member 251 that is a member that presses the release member 241 from the outside. And a cover portion 244 that covers an opening (hollow portion) of the holding portion 232 that is an outlet portion of the atmosphere opening passage 220.

  The pressing portion 242 of the opening member 241 cuts out the side surface portion 242 a to secure a flow path for opening to the atmosphere between the inner peripheral surface of the holder 223. Further, the receiving portion 243 of the opening member 241 is formed to have a larger cross-sectional shape than the cross-sectional shape of the air release pin member 251. That is, the area where the air release pin member 251 of the receiving portion 243 can abut is larger than the contact surface of the air release pin member 251. The air release pin member 251 is a member that is advanced and retracted in the direction of the arrow from the apparatus main body side using an electromagnetic solenoid (not shown) or the like.

  Therefore, even if the arrangement position of the head tank 35 is shifted, the air release pin member 251 can reliably contact and press the receiving portion 243 of the release member 241. As a result, the release member 241 can press the ball 224 to set the atmosphere release path 220 to an open state, so that the head tank 35 can be stably and surely released to the atmosphere (opening the ink storage unit 201 to the atmosphere). Can do.

  That is, when the contact area of the opening member that presses and opens the valve and the pressing member that presses the opening member from the outside is the same, the position of the opening member and the pressing member of the liquid container is shifted. The pressing member cannot press the opening member or becomes incomplete, and the valve cannot be opened. Therefore, by making the area of the valve opening member larger than that of the pressing member that presses the opening member from the outside, the pressing member reliably presses the opening member even when the position of the opening member and the pressing member of the liquid container is shifted. To be able to.

  In addition, as described above, the opening member 241 is provided with the cover portion 244 that covers the opening (hollow portion) of the holding portion 232 serving as the exit portion of the atmosphere opening passage 220, so that it presses against the inner peripheral surface of the holding portion 232. It is possible to prevent foreign matter from entering the space between the outer peripheral surface of the portion 242 (flow path portion). In other words, when the outlet portion of the flow path (communication path) is exposed in the liquid container, the peripheral foreign matter easily enters the flow path, and the foreign matter that has entered the flow path seals the flow path. When it adheres to the valve means, the airtightness is lowered.

  Therefore, the opening member that opens the valve means is shaped so as to cover the outlet portion of the flow path, thereby preventing foreign matter from entering the flow path.

  Next, the opening member 241 and the holder 222 are opened by fitting a convex portion 233 formed on the outer peripheral surface of the holding portion 232 of the holder 222 and a concave portion 245 formed on the cover portion 244 of the opening member 241. The opening member 231 which is a member is mounted so as to be movable in a direction in which the ball 225 constituting the valve means is pressed and not detached from the holding portion 232.

  In this configuration, as shown in FIG. 11A, the pressing portion 242 of the opening member 241 is inserted into the holding portion 232 of the holder 222 and pushed in the direction of the arrow, so that the covering portion 244 of the opening member 241 is The protrusion 233 is pushed in while riding on the protrusion 233, whereby the protrusion 233 of the holder 222 is fitted into the recess 245 of the opening member 241 as shown in FIG.

  As a result, when the convex portion 233 of the holder 222 is fitted into the concave portion 245 of the opening member 241, the opening member 241 is prevented from being detached from the holder 222 by being pressed by the urging force of the coil spring 225 and the concave portion 245. It is possible to move in the direction indicated by the arrow by the length of, and the ball 224 which is the valve body can be pushed in and released.

  In this case, the opening member can be moved in a direction in which the valve means is pressed with respect to the part forming the outlet of the communication path, and is mounted in a state where the opening member is not detached from the part forming the outlet of the communication path. For this reason, the convex portion (the convex portion 233) is formed outside the portion that forms the outlet of the communication path, and the concave portion (the concave portion 245) that fits the convex portion is formed inside the opening member. In addition, the configuration in which the relationship between the convex portion and the concave portion is reversed (the same is true in the following embodiments as much as possible in terms of the configuration of the members).

  In the image forming apparatus configured as described above, the atmosphere release pin member 251 is operated by a drive unit (not shown) to open the atmosphere release valve mechanism 204 of the head tank 35, whereby the inside of the head tank 35 is opened to the atmosphere. Put it in a state.

  Then, the ink is supplied from the ink cartridge 10 to the head tank 35 by the supply pump unit 24 and replenished and supplied. At this time, the air in the head tank 35 is discharged through the atmosphere release valve mechanism 204.

  Thereafter, the atmosphere release valve mechanism 204 is closed to shut off the inside of the head tank 35 from the atmosphere release, and the ink in the head tank 35 is discharged from the nozzles with the liquid ejection head 34 capped by the cap 72A of the subsystem 71. By sucking (head sucking), the urging force of the spring 103 is applied to the flexible film-like member 102, so that a negative pressure is generated in the head tank 35.

  The features of the present invention will be described with respect to the configurations of the head tank 35 and the liquid discharge head unit as described above.

  The feature of the present invention resides in the handling of the mixed bubbles in the filter unit. Specifically, the bubbles are not retained in the filter portion so that the movement of the ink is not hindered.

  A configuration for this will be described with reference to FIGS. FIG. 12 is a schematic cross-sectional view of the filter unit, and FIGS. 13 and 14 are explanatory diagrams of states when air bubbles are mixed. Here, in order to simplify the drawing, the structure in the case where the filter unit stores one color will be described. When multicolor droplets are discharged, a plurality of filter chambers are integrally formed in one filter unit.

  In FIG. 12, the filter unit 101 includes a first filter case 301 and a second filter case 302 that form a filter chamber 300 therein.

  Inside the filter chamber 300, a stainless steel filter 303 for filtering the ink supplied to the liquid ejection head 34 is attached at an angle of 10 ° to 30 ° with respect to the horizontal direction.

  A portion where the filter 303 is attached is a part of an ink supply flow path through which ink flows toward the filter chamber 300, and one of the flow paths is an attachment angle of the filter 303 with the filter chamber 300 interposed therebetween 10. It is composed of a passage inclined at ~ 30 °. Here, the supply channel on the upstream side of the filter 303 in the filter chamber 300 is defined as 304a and the supply channel 304b on the downstream side.

  In principle, the filter 303 can be attached to either the first filter case 301 or the second filter case 302. However, when the filter is welded or bonded, dust tends to be generated from the joint portion. Therefore, it is desirable to attach to the first filter case 301.

  For the filter 303, a metal fiber nonwoven fabric sintered body, a twill-folded metal body, a resin mesh, or the like is used. In the case of a mesh structure, a mesh size capable of capturing particles having a particle size of 20 μm or less is set. Has been. As a result, clogging is suppressed by preventing the passage of foreign matters of a certain size or irregular shapes while reducing the movement resistance of liquid such as ink. In the case of a resin filter, troublesome joining work such as welding can be omitted, and workability at the time of assembly or replacement can be improved.

  The filter unit 101 is configured to have a larger cross-sectional area than the ink supply path, and the ink flow rate per unit area in the filter 303 is smaller than the flow rate per unit area in the ink supply path, so that ink can be printed for high-speed printing. Even when the flow rate increases, the pressure loss in the filter unit does not affect the ink supply.

  In such an image forming apparatus, as shown in FIG. 13A, bubbles that enter during replacement of the main tank and bubbles (denoted by reference numeral Bu) caused by dissolved air are supplied to the liquid discharge head 34 by ink. Along with this, the filter chamber 300 may gather.

  Normally, the mixed bubbles Bu are discharged by performing head suction from the nozzles of the liquid discharge head 34 in a state where the liquid discharge head 34 is capped by the cap 72A of the subsystem 71, but the bubbles pass through the filter. A pressure sufficient to destroy the meniscus between the filter and the bubbles is necessary, and the amount of waste ink increases accordingly.

  However, in the filter unit having the configuration used in the present embodiment, after the printing is completed and the ink supply to the liquid ejection head is completed, the bubbles that have reached the filter chamber 300 are timed as shown in FIG. With the passage of time, the buoyancy lifts along the inclined surface of the supply flow path 304a, and finally, it is guided to the head tank 35 as shown in FIG.

  Bubbles guided to the head tank 35 are accumulated on the upper portion of the head tank 35 until the two detection electrodes 216 in the head tank 35 no longer detect ink. Therefore, the supply flow path 304a functions as a structure for guiding bubbles.

  In order to shorten the time until the bubble rises as much as possible, it is better to incline the inclination angle of the filter 303 and the supply flow path 304a. However, as the angle is increased, the height of the filter unit 101 increases, and the liquid discharge This is disadvantageous for downsizing of the entire head unit. In this embodiment, the inclination angle is set within a range of 10 ° to 30 ° due to the relationship between the time required for the bubble rising and the liquid discharge head unit layout.

  Also, when the ink supply is not in time and the nozzle is down, air is drawn from the nozzle. These bubbles also rise due to their own buoyancy and eventually accumulate in the filter chamber 300 through the ink supply path 304b.

  Normally, these bubbles are also discharged by performing head suction from the nozzles of the liquid discharge head 34, but the ink in the common liquid chamber (not shown) in the liquid discharge head 34 and the supply flow path 304b must also be discharged.

  However, in the filter unit configured as described above, as shown in FIGS. 14A, 14B, and 14C, a bubble storage chamber that traps bubbles in the ink supply channel 304b on the downstream side of the filter chamber 300, In other words, it has a part where bubbles are stuck by buoyancy, so even if it causes a nozzle down, the air drawn from the nozzle does not accumulate in the filter chamber, and the head suction for recovering the nozzle down Since the amount of ink is sufficient to fill an individual liquid chamber (not shown) of the liquid discharge head, the amount of waste ink can be minimized. In FIG. 14, an arrow F indicates the direction of ink movement.

  If the bubble storage chamber becomes full of bubbles, the liquid ejection head 34 can only be discharged by performing head suction, but the amount of bubbles mixed in by the nozzle down is the amount of bubbles entering from the upstream side of the filter chamber. Therefore, if the volume of the bubble storage chamber is equal to or larger than the amount of mixed bubbles assumed during the use period of the image forming apparatus, the amount of waste ink can be further reduced.

  Another embodiment related to the filter unit of the present invention is shown in FIGS.

  In FIG. 15, a filter unit (indicated by reference numeral 100 ′ for convenience) includes a first filter case (indicated by reference numeral 301 ′ for convenience) and a second filter case (indicated by reference numeral 302 ′ for convenience). A filter chamber 305 is formed.

  The filter chamber 305 is provided with a filter 303 attached in a vertical direction, and ink supply passages (for convenience, denoted by reference numerals 304a ′ and 304b ′) on the upstream and downstream sides of the ink movement direction with the filter 303 interposed therebetween. Is shown).

  The filter chamber 305 is partitioned with the filter 303 interposed therebetween, and a concave trap portion 305A is provided on the wall surface facing the downstream supply passage 304b '. In FIG. 17, an arrow F indicates the direction of ink movement.

Since the filter unit in this embodiment welds the filter perpendicular to the horizontal direction, the width of the filter unit can be reduced.
As described above, since the image forming apparatus includes the filter unit according to the present invention, even when bubbles enter the ink supply path, the amount of waste ink can be reduced and high speed without causing insufficient ink supply. High-quality images can be formed stably.

  In this configuration, as shown in FIG. 16, the bubbles that have entered the upstream supply passage 304a ′ rise by buoyancy along the supply passage, and the bubbles that have entered the downstream supply passage 304b ′ It rises by buoyancy and stays in the trap portion 305A of the filter chamber 305, and the same action as the case shown in FIGS. 13 and 14 is obtained.

  The image forming apparatus using the liquid ejecting apparatus according to the present invention is not limited to a single printer function, and may have a combined function such as a printer / facsimile / copying, and a liquid container corresponding to the combined function. Of course, it is possible to adopt a configuration adapted to the above form.

1 is an external view of an image forming apparatus using a liquid ejection device according to the present invention. FIG. 2 is a schematic diagram for explaining an internal configuration of the image forming apparatus illustrated in FIG. 1. FIG. 3 is a plan view of the internal configuration shown in FIG. 2. It is a perspective view of a liquid discharge head unit. It is a side view of a liquid discharge head unit. FIG. 5 is a side view of a head tank body used in the liquid ejection head unit shown in FIG. 4. FIG. 7 is a perspective view of the head tank body shown in FIG. 6. It is a perspective view which shows the principal part of the head tank main body seen from the opposite side to FIG. FIG. 7 is a bottom view of the head tank body shown in FIG. 6. It is a top view of the air release mechanism part used for the head tank main body shown in FIG. It is a perspective view of the air release mechanism part shown in FIG. It is a schematic diagram for demonstrating the structure of the filter unit provided in the head tank main body. It is a figure for demonstrating the one aspect | mode with the filter unit shown in FIG. It is a figure for demonstrating the aspect of the rice field in the filter unit shown in FIG. It is a schematic diagram for demonstrating another embodiment of the filter unit shown in FIG. It is a figure for demonstrating the one aspect | mode of the toffee surface unit shown in FIG. It is a schematic diagram for demonstrating another embodiment of the filter unit shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 34 Liquid discharge head 101 Filter unit 204 Atmospheric release valve mechanism 224 Ball | bath 251 Atmospheric release pin 300 Filter chamber 301, 301 '1st filter case 302, 302' 2nd filter case 303 Filter 304a, 304a 'Upstream side Supply passage 304b, 304b 'downstream supply passage

Claims (14)

A liquid discharge head for discharging liquid droplets from a nozzle; a detachable liquid main tank disposed at a predetermined position; and a liquid supply from the liquid main tank via a liquid supply path. In a liquid discharge apparatus comprising: a head tank that supplies liquid; and a filter unit having a filter chamber in which a filter that filters the liquid supplied to the liquid discharge head is built-in,
The liquid ejecting apparatus according to claim 1, wherein the filter chamber is provided with a portion for guiding bubbles to a head tank upstream of the filter in the moving direction of the droplet. The droplet discharge device according to claim 1,
A liquid ejection apparatus, wherein the filter is welded vertically to a horizontal direction. The droplet discharge device according to claim 1,
The filter is welded obliquely with respect to the horizontal direction, and the flow path connecting the filter unit and the head tank has a slope for introducing mixed air bubbles into the head tank. A liquid ejecting apparatus. In the droplet discharge device according to claim 3,
The liquid ejecting apparatus according to claim 1, wherein the filter and the flow path connecting the filter unit and the head tank have an angle of 10 ° to 30 ° with respect to a horizontal direction. The liquid ejection apparatus according to any one of claims 1 to 4,
A liquid ejection apparatus comprising: a bubble accommodating chamber for trapping bubbles in a flow path connecting the filter unit and the nozzle. The liquid ejection apparatus according to any one of claims 1 to 5,
The liquid discharging apparatus according to claim 1, wherein the filter is a filter made of a sintered metal fiber nonwoven fabric.   6. The liquid ejecting apparatus according to claim 1, wherein the filter is a filter made of a metal body formed by a twilling weave. The liquid ejection apparatus according to any one of claims 1 to 5,
The liquid ejection device, wherein the filter is a resin filter. The liquid ejection apparatus according to any one of claims 1 to 8,
The liquid ejecting apparatus, wherein the filter is a filter capable of capturing particles having a particle diameter of 10 μm or more. The liquid ejection device according to any one of claims 1 to 9,
A liquid ejecting apparatus comprising pressure control means for controlling the atmospheric pressure in the head tank. The liquid ejection apparatus according to claim 10, wherein
The pressure control means includes a packing attached to the opening of the head tank, a contact / separation member configured to be able to contact / separate the packing, and the contact / separation member opens or seals the hole of the packing. A liquid ejection device comprising: a pressurizing control unit that pressurizes the contact / separation member to control air pressure in the head tank so that air enters and exits the head tank; and an air release cap that fixes them. apparatus. The liquid ejection apparatus according to claim 11, wherein
The liquid ejecting apparatus according to claim 1, wherein the contact / separation member is a metal sphere, and the pressure control means is an electromagnetic solenoid lever. The liquid ejection apparatus according to claim 11, wherein
The liquid ejecting apparatus according to claim 1, wherein the contact / separation member is a metal sphere, and the pressure control unit is a non-contact type ferromagnetic material.   An image forming apparatus using the liquid ejecting apparatus according to claim 1, wherein ink is used as the liquid.

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