JP5920063B2 - Droplet recovery device, droplet discharge unit, and image forming apparatus - Google Patents

Description

  The present invention relates to an ink that is ejected idlely and floats in a mist state when ink droplets are ejected from the ejection holes of a recording head that ejects droplets (ink droplets) in an ink jet recording apparatus to flush the ejection holes. The present invention relates to a droplet recovery device that prevents scattering and adhesion to the periphery of the liquid, a droplet discharge unit including the droplet recovery device, and an image forming apparatus.

  An ink jet recording apparatus known as an image forming apparatus such as a printer, a facsimile machine, a copying machine, a plotter, or a multi-function machine having these functions discharges ink droplets from a recording head to a recording medium such as recording paper. Record text and images. In order to record characters and images stably, a maintenance / recovery operation for maintaining and recovering the performance of the recording head is required. As the maintenance and recovery operation, after ejecting ink droplets, the nozzle surface of the recording head that ejects ink is cleaned using a cleaning member such as a wiper blade. After cleaning, since the meniscus of the nozzle has not yet returned to the normal state, ink droplet ejection that does not contribute to image formation may be performed (empty ejection). By performing the idle discharge toward the idle discharge receptacle, the meniscus is returned to a normal state. At the time of this idle ejection, there is a main droplet that is relatively large and reaches the idle ejection receptacle almost linearly perpendicularly from the nozzle surface of the recording head, and there are those that become fine and mist and float. This mistake leaks out of the empty discharge receptacle, causing the inside of the machine to be contaminated and causing quality deterioration and failure.

  As a conventional solution to this problem, for example, in Patent Document 1, a venturi passage is provided between the recording head and the idle discharge receiver, and an air passage exists between the venturi passage and the reservoir that is the idle discharge receiver. Proposed. That is, as shown in FIG. 4, the flow of air including ink droplets that are ejected idle is throttled in the venturi passage 34, and the flow of ejected ink droplets is accelerated so that the flow between the venturi passage 34 and the reservoir 32 is increased. By the presence of the air passage, ink droplets are pushed into the reservoir assembly container composed of the venturi passage 34 and the reservoir 32 to suppress mist scattering.

  Further, in Patent Document 2, as shown in FIG. 5, a taper is formed so that the liquid storage container 40 that is an empty discharge receptacle protrudes inwardly toward the upper wall 42 facing the recording head 52 so that the facing interval narrows downward. It is disclosed to provide a pair of guide plates 44 and 46 having surfaces. The shape narrowed toward the inside of the container in this way guides the flow of ink droplets to the bottom of the container, prevents the ink droplets falling into the container from flowing out of the container again, and suppresses mist scattering.

  However, in these configurations, since the airflow flows toward the center at the container inlet and the airflow accelerates, the airflow directly goes to the bottom of the container as shown by the straight line a in each figure inside the widely opened container. move on. If the container capacity is large, the airflow will slow down while proceeding to the bottom, and no large updraft will be generated.However, if the container is small, some of the air that has reached the bottom will bounce off the bottom, resulting in curve b. As shown, it goes to the container inlet as an updraft. If this updraft is large, in the configuration of FIG. 4 (FIG. 4), air escapes from the inlet side surface as shown by the curve c through the throttle due to the shape of the venturi passage. In the configuration of Patent Document 2 (FIG. 5), although the shape is more difficult to escape from the entrance than in the configuration of FIG. Due to the air flow c generated due to the container inlet shape spreading upward, the mist is also flown and scattered by the air flow, and the mist is easily scattered to the outside.

  Further, in the configuration disclosed in Patent Document 1, an air passage is formed between the venturi passage and the reservoir, and in the configuration disclosed in Patent Document 2, a slight gap is formed in the upper wall 42. Although air is allowed to escape at portions other than the entrance, the mist is scattered by riding on the airflow e from such an escape place.

  SUMMARY OF THE INVENTION An object of the present invention is to prevent a situation in which mist in an empty discharge receiver that occurs during empty discharge related to ink jet image recording leaks to the outside.

  According to the present invention, the above-described problem is provided with an empty discharge receiving container for storing an empty discharged droplet, and the air is discharged from the inside of the container toward the air flow caused by the droplet discharged and entering the inside from the container inlet. The problem is solved by the fact that the thick end of the peripheral edge of the container inlet opening portion is inclined so as to spread toward the inside of the container so that the mist flows.

  As the thick end of the peripheral edge of the container inlet opening is inclined so as to spread toward the inside of the container, it tries to flow out from the inside of the container toward the air current generated by the liquid that is discharged from the container inlet and enters the inside. Since this mist flows, the mist is pulled by the air current and tries to return to the inside of the container, thereby preventing external leakage.

1 is a schematic configuration diagram of an entire ink jet recording apparatus according to the present invention. 2A and 2B are cross-sectional views schematically showing a droplet recovery apparatus according to the first embodiment, in which FIG. 2A shows the short direction of the recording head, and FIG. 2B shows the long direction of the recording head according to the paper surface. It is sectional drawing in the transversal direction of a recording head which shows the outline of the droplet collection | recovery apparatus concerning 2nd Embodiment. It is sectional drawing which shows the outline of the conventional droplet collection | recovery apparatus. It is sectional drawing which shows the outline of another conventional droplet collection | recovery apparatus.

  An example of the present invention will be described below. FIG. 1 is a schematic configuration diagram of the entire ink jet recording apparatus according to the present invention. The paper 100 loaded on the paper feed tray 101 is transported by the paper feed roller 102 on the transport path indicated by the dotted line in FIG. The sheet 100 transported to the transport path is transported to the belt transport unit 104 via the timing adjustment / skew correction roller pair 103.

  The belt conveyance unit 104 includes a conveyance roller 105 and a tension roller 106 that are driven at a predetermined timing, and an endless conveyance belt 107 that is wound around these rollers. In order to hold the sheet 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 is 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 transported by the separation claw 110 via the transport 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 counterclockwise from the illustrated position passes through the conveyance path 113 and is sent to the tapping roller 115 through the guide member 114. 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. Then, it is sent to the timing adjustment / skew correction roller pair 103.

  The recording head unit 108 is composed of a line type droplet discharge head having a nozzle row in which a plurality of nozzles that discharge 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. Further, the cap 201 of the maintenance / recovery unit 200 also serves as a moisture retaining cap for maintaining the humidity of the recording head 108kc during standby, while the humidity of the recording head 108my is maintained by another moisture retaining cap unit 203. At the time of non-printing, the recording head unit 108 rises, and the maintenance / recovery unit 200 and the moisture retention cap unit 203 move to below the recording heads to perform moisture retention capping.

  FIG. 2 is a cross-sectional view schematically showing the droplet recovery apparatus according to the first embodiment, FIG. 2a is a short direction of the recording head (a direction perpendicular to the longitudinal direction), and FIG. It is shown according to. The inlet 301 of the idle discharge receiver 300 forms a tapered portion 304 that extends downward from the empty discharge receiver upper wall side 302 toward the inner wall 303.

  When ink is ejected from the nozzle hole 109n of the nozzle plate 109 of the recording head to the idle ejection receptacle 300, the surrounding air is pulled by the ink droplet as shown by the curve a, and the air is ejected together with the ink droplet. Flows into 300. The air drawn by the ink droplets goes straight to the bottom 305 as shown by a straight line b, and then bounces around the bottom or turns around to become an upward airflow. The portion that has become mist from the ink droplets accompanying the movement of the airflow moves so as to escape from the edge region of the inlet 301 of the idle discharge receiver 300 together with the air, but proceeds along the tapered portion 304. Therefore, the mist is hardly leaked to the outside and returned to the inside of the empty discharge receiver 300 because it is pulled by the ink droplet that is discharged in an empty manner and the flow of air drawn into it (dotted line f). According to the experiments by the present inventors, when the speed of the ink droplets that are ejected idly is 12 m / s and the wall thickness of the idling receptacle 300 is 3 mm, the lower end edge is scraped by 1 mm from the upper end edge of the inlet, and the tapered portion. By forming 304, ink mist external leakage was clearly reduced.

  Further, a suction hole 308 connected to the suction pump 307 may be provided in the bottom portion 305 of the idle discharge receptacle 300, and a mist or an idle ejected ink that floats inside the idle discharge receptacle due to attenuation of an air flow caused by the idle ejection. The droplets can also be collected from the suction hole 308 to a waste liquid container (not shown) by the suction pump 307. By operating the suction pump 307 during the maintenance / recovery operation, the inside of the empty discharge receiver is in a negative pressure state, and the ink droplets and mist discharged in an empty manner can be constantly collected from the suction hole 308. Incidentally, the suction amount of the suction pump 307 is at least sufficiently higher than the flow rate of the airflow flowing into the idle discharge receptacle. This is because leakage of mist is prevented by the tapered portion 304 of the idle discharge receptacle.

  Note that if the open end of the inlet 301 of the idle discharge receptacle 300 is far away from the nozzle end of the recording head, it is difficult for a downward airflow due to ink droplets to occur at the entrance 301, and from the peripheral end of the idle ejection receptacle 301. Mist is likely to leak. Therefore, the inlet peripheral edge of the idle discharge receptacle 300 is defined so as to correspond between the outermost end of the nozzle hole 109a (the outermost end of the nozzle hole region 109n) and the end portion (distance L) of the nozzle plate 109. Yes.

  FIG. 3 is a cross-sectional view showing an outline of the droplet recovery apparatus according to the second embodiment, and shows the short direction of the recording head along the paper surface. A collision guide 309 is provided inside the idle discharge receiver 300 at a position where it collides with an ink droplet. The collision guide part 309 is attached to the bottom part 305 and tapers upward and protrudes toward the inlet 301. When the ink droplet or the air pulled by the ink droplet hits the inclined portion of the collision guiding portion 309, it does not bounce off the bottom portion 305 and becomes an ascending air current, but becomes an air current that flows and circulates to the side. The ink mist riding on the circulating airflow travels along the tapered portion 304 at the entrance of the idle discharge receiver 300, is pulled by the ink droplets that are idlely ejected, and the flow of air drawn into the ink droplets, and returns to the inside of the idle ejection receptacle 300. The surface of the collision guiding unit 309 may be subjected to water repellent treatment so that the colliding ink droplets can easily flow.

  When a suction hole connected to the suction pump 307 via the suction path is formed not only at the bottom portion 305 but also at the end surface of the taper portion, ink mist that tends to escape to the outside along the taper portion 304 is transferred to the suction path 310 by the suction pump 307. Since it can be recovered, mist scattering can be prevented more reliably. Further, by receiving a suction action from the suction path 310, the air current drawn by the ink droplets that are ejected idle is pulled to the side, and coupled with the presence of the collision guide portion 309, the contact with the bottom portion 305 is weakened.

  2 and 2 describe the case where there are two rows of nozzle holes, but the mist scattering can be suppressed by adopting the same configuration regardless of whether the number of nozzle holes is single or three or more. I was able to.

109 Nozzle plate 300 Empty discharge receptacle 301 Inlet 302 Upper wall side 303 Inner wall 304 Taper part 305 Bottom part 307 Suction pump 308 Suction hole 309 Collision induction part

Japanese Patent No. 3806165 Japanese Patent No. 4421702

Claims (7)

  A container inlet opening part is provided with an empty discharge receiving container for storing the empty discharged liquid droplets, so that mist flowing from the inside of the container flows toward the air current generated by the liquid droplets discharged from the container inlet and entering the inside. An apparatus for recovering liquid droplets, characterized in that the thick end of the periphery is inclined so as to spread toward the inside of the container.   2. The droplet recovery apparatus according to claim 1, wherein a collision guide portion that is tapered toward the inlet of the container is provided at a position on the bottom surface of the empty discharge receiving container that collides with the droplet.   The droplet recovery apparatus according to claim 1, wherein a mist suction port is provided on a bottom surface of the empty discharge receiving container, and a negative pressure is applied to the mist suction port.   The liquid according to any one of claims 1 to 3, wherein a mist suction port is provided at a thick end of the peripheral edge of the container inlet opening, and a negative pressure is applied to the mist suction port. Drop collection device.   A droplet discharge unit comprising: a head that discharges droplets; and the droplet recovery device according to claim 1.   The position of the peripheral edge of the container opening portion corresponds to the space between the outermost end of the nozzle hole region of the head and the end of the nozzle plate in which the nozzle holes are formed. Droplet discharge unit.   An image forming apparatus comprising the droplet collection device according to claim 1.

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