JP5994616B2 - Empty discharge receiver and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly, to an empty discharge receiver provided when flushing ink droplet (droplet) discharge ports of a recording head in an ink jet recording apparatus.

  2. Description of the Related Art As an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, and a multifunction machine having these functions, for example, an ink jet recording apparatus (liquid discharge recording type image forming apparatus) having a recording head for discharging ink droplets is known. . In such a liquid ejection type image forming apparatus, the recording head performs image recording by ejecting ink pressurized in a pressure generating chamber from a nozzle onto a recording material (also referred to as recording medium or paper). For this reason, there is a problem that the ink viscosity rises due to the evaporation of the solvent from the nozzle, the ink solidifies, the dust adheres, and the air bubbles are mixed, resulting in a discharge failure and a recording failure. . Therefore, in order to keep the ejection state of the recording head normal, a maintenance recovery operation is necessary. The maintenance / recovery operation includes wiping and idle discharge after suction of the head, in addition to a discharge recovery operation in which the nozzle of the recording head is sealed with a cap member, and ink is sucked and discharged (head suction) from the nozzle with a negative pressure. Wiping is an operation of wiping with a wiping member residual ink that adheres to the nozzle surface of the recording head and causes the flying state of ink droplets to change. The idle ejection is an operation for ejecting ink droplets that do not contribute to image formation in order to return the meniscus of the nozzle to a normal state after wiping.

  When idle ejection is performed, so-called satellite droplets and mist smaller than the main droplets are generated from the ink droplets in addition to the main droplets that reach the idle ejection receptacle almost linearly. Mist originates from ink droplets, just like main droplets and satellite droplets, but is finer and floats in the air, and its properties differ greatly from main droplets and satellite droplets. This causes the inside of the machine to become contaminated, causing image quality degradation and device failure.

  As a conventional solution to such a problem, for example, in Patent Document 1, an air flow generated by dragging ambient air by ejecting ink droplets is guided to the filter-attached opening wall side of the empty ejection receiver, and then rides on the air flow. It proposes to collect mist with a filter. This prevents mist from splashing outside. However, the configuration disclosed in Patent Document 1 has a problem in that the cost is increased because the filter portion is provided in the idle discharge receiver, and there is a problem that replacement is necessary because there is a lifetime due to filter clogging.

  Here, the ink jet recording apparatus includes a serial type image forming apparatus that forms an image by ejecting ink droplets while the recording head moves in the main scanning direction, and a state in which the recording heads arranged in a line do not move. There is a line-type image forming apparatus that uses a line-type head that ejects ink droplets. In serial type recording devices, the number of heads is small and the number of idle ejections as a whole is small. However, when a line type recording device, especially a large machine, the number of idle ejections until the machine life is large, the replacement frequency increases. . For this reason, if the line type is intended to reduce the size of the idle discharge receptacle, the service life is quickly reached.

  Moreover, even if it guide | induces an airflow to the wall side in the structure of patent document 1, not all the airflow goes to the wall side but there is what rises and flows out from the opening part of an empty discharge receptacle. Mist also flows out of the opening along a gentle air flow. In particular, when the idle discharge receptacle is reduced in size, an upward air flow is immediately generated, and more mist is easily scattered. In general, since only two nozzle rows are arranged in the short direction of the recording head, the influence of the descending air flow due to the idle ejection is strong, and the mist is hardly scattered. On the other hand, in the longitudinal direction of the recording head, only the influence of the descending airflow due to the idle ejection of the nozzles at the end of the many nozzles is caused, and mist is more likely to be scattered than in the lateral direction. Therefore, in the configuration of Patent Document 1, when the airflow is guided to the outside in the longitudinal direction of the head, the mist that does not adhere to the filter rides on the rising airflow as it is, flows out from the end of the opening in the longitudinal direction of the head, and the amount is large. It is.

  Patent Document 2 discloses a fluid confinement system including a direction change structure of ejected ink droplets, and includes an ink direction change surface directed toward an ink storage place through a narrowed guide path, whereby ink particles are formed. It aims to contain. However, the narrowed guide path is formed in the hood that covers the ink storage place as the empty discharge receiving housing, and therefore, the ejected ink droplets collide with the ink direction changing surface in the vicinity of the hood opening, and the circulatory flow of ink airflow It happens in the vicinity. Therefore, even if the stop structure portion is formed on the surface of the hood, it is impossible to avoid the mist from being scattered outside due to the rising airflow, despite the effects described in the literature. In particular, when ink droplets collide a plurality of times in the hood before reaching the ink storage location, the possibility of the occurrence of ascending air current and the accompanying and leakage of mist due to the ascending air current is further increased. And if the system is miniaturized, the generation of ascending airflow and the scattering of mist to the outside increase.

  As described above, in the conventional configuration, mist cannot be completely trapped in the idle discharge receptacle, and much mist is scattered to the outside. It is inevitable that external scattering will be further deteriorated by downsizing the idle discharge receptacle.

  An object of the present invention is to provide an empty discharge receptacle that can minimize the external scattering of mist due to empty discharge even if it is downsized.

  An object of the present invention is to provide an empty discharge receiver for storing droplets discharged from a recording head, including a discharge droplet introduction passage having a passage wall extending from the droplet inlet to the inside of the housing, and a mist for storing a mist airflow. Mist airflow attenuation, which is located downstream of the storage space and in the droplet traveling direction of the discharge droplet introduction passage, is connected to the mist storage space, and has an airflow reflecting surface facing the slope and the discharge droplet collides with it It is solved by comprising a passage.

  According to the present invention, after entering the casing of the empty discharge receptacle through the discharge droplet introduction passage, energy is attenuated while colliding with the slope and the airflow reflection surface in the mist airflow attenuation passage. The mist airflow that has passed through the mist airflow attenuating passage while the energy is attenuated further enters the mist accommodating space and remains in the mist accommodating space and is collected.

1 is a schematic configuration diagram of an entire ink jet recording apparatus according to an example of the present invention. It is a schematic perspective view of the 1-head idle discharge receiver according to an example of the present invention. It is sectional drawing of the idle discharge receptacle in the A cross section of FIG. It is sectional drawing of the idle discharge receptacle in the B cross section of FIG. FIG. 5 is a cross-sectional view corresponding to FIG. 4 for explaining waste liquid recovery of discharged droplets. It is a fragmentary sectional view of the example which provided the obstacle piece in the mist accommodation space. FIG. 7A is a conceptual diagram of an example in which the mist airflow attenuation passage is tapered, and FIG. 7A is a longitudinal section of the idle discharge receiver, and FIG. It is a fragmentary sectional view of the example which provided the ink absorber. It is a schematic perspective view of an example which applies an idle discharge receptacle for line type heads.

  An example of the present invention will be described below. In FIG. 1, the paper 100 stacked on the paper feed tray 101 is transported by a paper feed roller 102 to a transport path indicated by a dotted line. The paper 100 transported to the transport path is transported to the belt transport unit 104 via a timing alignment / skew correction roller (so-called registration roller) pair 103.

  The belt conveyance unit 104 includes a conveyance roller 105 driven at a predetermined timing, a tension roller 106, and an endless conveyance belt 107 wound around these rollers. In order to hold the paper 100 by the belt conveyance unit 104, means by electrostatic adsorption, adsorption by air suction, or other known means can be used. The paper 100 is transported to the belt transport unit 104 and passes under the recording head unit 108 to form an image.

  On the paper 100 on which an image has been formed by the recording head unit 108, undried ink constituting the image is adhered. In order to dry the undried ink, although not shown, a drying mechanism such as a heater or hot air can be provided between the decurler unit 109 and the like. After image formation by the recording head unit 108, the paper 100 is conveyed to the decurler unit 109 and decurled. When the paper 100 that has passed through the decurler unit 109 is discharged as it is, it is conveyed by the separation claw 110 via the conveyance path 111 to the paper discharge roller 112 and discharged. In the case of reverse paper discharge or reverse side printing, the separation claw 110 switched from the illustrated position counterclockwise passes through the conveyance path 113, passes through the guide member 114, and is sent to the tapping roller 115. The paper 100 sent to the tapping roller 115 is conveyed in the reverse direction by the tapping roller 115 whose rotation direction has been switched. In the case of reverse paper discharge, the paper 100 passes through the conveying path 117 via the second separation claw 116. The paper is sent to the paper discharge roller 112 and discharged. When printing on the reverse side, the sheet conveyed in the reverse direction by the tapping roller 115 passes through the conveyance path 119 via the second separation claw 116 and the double-side reversing roller 118 that are switched counterclockwise from the illustrated position. Are sent to the registration roller pair 103.

  The recording head unit 108 is composed of a line type liquid discharge head having a nozzle row in which a plurality of nozzles for discharging ink droplets are arranged in a length corresponding to the paper width. The recording head unit 108 includes a recording head 108my for yellow (Y) and magenta (M), and a recording head 108kc for cyan (C) and black (K). In the recording head unit 108, the respective heads are arranged in a staggered manner in odd and even columns. It should be noted that the recording head can be mounted on the carriage as a serial type image forming apparatus.

  A maintenance / recovery unit 200 is provided to maintain and recover the performance of the recording head unit 108. The maintenance / recovery unit 200 includes a cap 201 for sucking ink of the recording head unit 108, a wiper 202 for wiping off ink adhering to the head when sucked, and an empty discharge receiver 300 for storing empty discharge ink. When performing the maintenance recovery, the recording head unit 108 rises, and the maintenance recovery unit 200 moves below each recording head, and a maintenance recovery operation is performed. The cap 201 of the maintenance / recovery unit 200 also serves as a moisture retention cap that maintains the humidity of the recording head 108 kc during standby, while the humidity of the recording head 108 my is maintained by another moisture retention cap unit 203. At the time of non-printing, the recording head unit 108 rises, and the maintenance / recovery unit 200 and the moisture retaining cap unit 203 move to below each recording head to perform moisture retention capping.

  FIG. 2 is a perspective view of an empty discharge receptacle 300 for one head according to an embodiment of the present invention (a mist collection space is shown in an open state for easy understanding). The mist collection space must be closed when the idle discharge receptacles are arranged alone, but when connecting multiple idle discharge receptacles for a line-type head, as will be described later, By opening the space, the mist collection space can be enlarged. FIG. 3 shows a longitudinal section (section A in FIG. 1) of the idle ejection receiver or recording head, and FIG. 4 shows a section in the short direction (direction perpendicular to the longitudinal direction) (section B in FIG. 1). The empty discharge receiver 300 includes a discharge droplet introduction passage 305, a mist storage space 310, and a mist airflow attenuation passage 306 that connects the mist storage space 310 and the discharge droplet introduction passage 305. The discharge droplet introduction passage 305 has a droplet inlet 303 on the surface of the empty discharge receiver 300 and a passage wall 304 having a wall surface extending from the inlet along the droplet traveling direction. The inner wall surface of the passage wall 304 extends along the liquid droplet traveling direction, but does not have to be strictly parallel to the liquid droplet traveling direction and extends so as not to hinder the liquid droplet traveling. The mist airflow attenuating passage 306 is continuous with the discharge droplet introduction passage on the downstream side in the droplet traveling direction of the discharge droplet introduction passage 305 and is connected to the bottom of the mist accommodating space 310. Further, the mist airflow attenuation passage 306 has an inclined surface 307 on which the ejected liquid droplets and an airflow generated by the ejected liquid droplets hit, and an airflow reflecting surface 308 that realizes reflection attenuation of the mist airflow facing the inclined surface. The slope 307 of the mist airflow attenuation passage 306 is formed integrally with the bottom surface of the casing of the empty discharge receptacle 300, and the airflow reflection surface 308 is formed so as to be connected to the passage wall 304 of the discharge droplet introduction passage.

  An ink droplet 301 as a droplet is ejected downward from the nozzle hole 108b of the nozzle plate 108a of the recording head. The ink droplet 301 passes through the ejection droplet introduction passage 305 while generating an air flow 302. The droplet inlet 303 of the ejection droplet introduction passage 305 should not be greatly opened to prevent backflow, and should be of a size that is just convenient for the ejection of ejected ink droplets. The ink droplet 301 is divided into a main droplet, a satellite droplet, and a mist during idle ejection. As shown in FIG. 5, the main droplet and the satellite droplet hit the inclined surface 307 of the mist airflow attenuation passage 306 and then are recovered through the droplet recovery hole 309 formed in the middle of the inclined surface. The droplet collection hole 309 may be formed at a location closer to the mist accommodating space 310 than the illustrated position, or at the bottom of the mist accommodating space 310. On the other hand, the airflow 302 containing mist collides with the inclined surface 307, attenuates the energy, further collides with the airflow reflecting surface 308, and repeats energy attenuation while hitting both surfaces as it advances through the mist airflow attenuation passage 306, thereby accommodating the mist. Enter space 310. The mist storage space 310 as a trap space is sufficiently wider than the mist airflow attenuation passage 306 and the discharge droplet introduction passage 305 and has a volume larger than the sum of the volumes of these passages. Therefore, the mist airflow attenuated in the mist airflow attenuation passage 306 is further attenuated in energy while being diffused in the mist storage space 310, and the mist drifts in the mist storage space 310 and is trapped. In order to reliably trap drifting mist, as shown in FIG. 6, an obstacle piece 311 as a trap piece may be provided in the mist housing space 310. Note that FIG. 6 depicts only the portion corresponding to the left half of FIG. 4 because the air flow behaves symmetrically when viewed in FIG.

  As a further modification, it is assumed that the mist airflow attenuation passage 306 is formed in a tapered shape that tapers from the discharge droplet introduction passage 305 toward the mist accommodating space 310. FIG. 7A shows a longitudinal section of the empty discharge receiver (DD sectional line of FIG. 7B), and FIG. 7B shows a shorter section of the empty discharge receiver (CC sectional line of FIG. 7A). In addition to the taper on the surface shown in FIG. 7b, the surface shown in FIG. 7a is also tapered. By constricting the mist airflow attenuation passage 306 in a tapered shape, the airflow flowing into the mist housing space 310 is strengthened, and the mist does not easily flow backward. Further, since the taper is also provided in the longitudinal direction, the tapered shapes in the opposite directions can easily collide with each other and promote energy attenuation.

  Also, as shown in FIG. 8, ink absorbers 315 and 316 made of sponge-like urethane or the like may be attached to the inner wall surfaces of the mist airflow attenuation passage 306 and the discharge droplet introduction passage 305. The ink absorbers 315 and 316 may be present only on a part of the wall surface, but may be present on the entire surface. The ink absorbers 315 and 316 can trap not only main droplets and satellite droplets but also mists, and are prevented from floating inside the empty ejection receiver.

  An example in which the idle discharge receiver is applied to the line type head will be described with reference to FIG. An empty discharge receiver 300 having the above-described configuration is provided for each recording head. The mist accommodating spaces 310 of the plurality of empty discharge receptacles 300 are connected in an open state, and the droplet recovery holes 309 are connected by a common conduit 312. The mist housing space 310 is connected to each other to form a large common space, which is in a state close to that of the atmosphere. The end surface 313 of the connected idle discharge receiver is shown in an open state for convenience, but is actually closed, and a filter member may be provided on the end surface in some cases. It is also conceivable that a fan as a suction means is attached in the vicinity of the end surface 313 to which the filter member is attached to forcibly trap the mist on the filter member. The common pipe 312 for collecting the waste liquid is connected to a valve 317, a suction pump 318 as a droplet suction means, and a waste liquid tank 319. Immediately after the idle discharge, the valve 317 is opened, and the ink that flows out to the common pipe 312 through the droplet collection hole 309 is sent to the waste liquid tank 319 and collected by the suction pump 318. Further, the suction pump 318 is connected to the cap 201, and the control of the valve 317 allows the suction pump 318 to selectively perform two functions, that is, the recovery of the empty discharge waste liquid and the suction recovery of the recording head. Yes.

  With the configuration as described above, even a line type liquid discharge head having a large number of recording heads can perform low-cost, high-efficiency, and high-reliability empty discharge collection while suppressing an increase in size.

108a Nozzle plate 108b Nozzle hole 300 Empty discharge receptacle 301 Ink droplet 303 Droplet inlet 304 Passage wall 305 Discharged droplet introduction passage 306 Mist airflow attenuation passage 307 Slope 308 Airflow reflection surface 309 Droplet collection hole 310 Mist accommodation space 311 Obstacle part piece 315, 316 Ink absorber

JP 2009-137227 A JP 2004-114686 A

Claims (11)

  An empty discharge receptacle for storing droplets discharged from a recording head, a discharge droplet introduction passage having a passage wall extending from the droplet inlet to the inside of the housing, a mist storage space, and the discharge droplet introduction Located on the downstream side of the passage in the liquid droplet traveling direction, the mist is connected to the mist housing space, and is configured to include a mist airflow attenuating passage having an inclined surface on which the discharged droplet collides and an airflow reflecting surface facing the inclined surface. Empty discharge receptacle.   The idle discharge receptacle according to claim 1, wherein the mist storage space is larger than a sum of volumes of the discharge droplet introduction passage and the mist airflow attenuation passage.   The idle discharge receptacle according to claim 1 or 2, wherein the mist air flow attenuation passage is tapered from the discharge droplet introduction passage side toward the mist accommodating space side.   The idle discharge receptacle according to any one of claims 1 to 3, wherein the slope of the mist airflow attenuation passage is formed integrally with a bottom surface of the idle discharge receptacle.   The empty discharge receptacle according to any one of claims 1 to 4, wherein a trap piece is provided in the mist accommodation space.   The idle discharge receiver according to claim 1, wherein a filter member is provided on an end surface of the mist housing space.   The idle discharge receiver according to claim 6, wherein suction means is attached to the filter member.   The idle discharge receiver according to claim 1, wherein an ink absorber is attached to an inner wall surface of the discharge droplet introduction passage or the mist airflow attenuation passage.   The idle discharge receiver according to claim 1, further comprising a droplet suction unit for collecting the waste liquid.   The idle discharge receiver according to claim 9, wherein the droplet suction unit is also used for suction recovery of the recording head.   An image forming apparatus comprising the idle discharge receiver according to claim 1.

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