Patent Application
20050134637
This non-provisional application claims priority under 35 U.S.C. ยง 119(a) on Patent Application No. 03078810.3 filed in The European Patent Office on Dec. 5, 2003, which is herein incorporated by reference.
The present invention relates to a device and a method for handling ink drops, particularly for receiving ink drops from a printhead or a printhead cleaning unit and discharging the ink drops into an ink drop collection tray.
It is known to collect ink drops falling down from a printhead or a printhead cleaning unit in a collection tray. The ink drops fall in a liquid condition and set or become rigid in the collection tray, thereby possibly forming stalagmites. These stalagmites may cause a problem in that they may interfere with the movement of the printhead or the cleaner. An operator must be available to periodically and timely remove the stalagmites.
It is further known to intercept the ink drops falling down from a printhead or a cleaning unit by using a belt conveyor which, in a forward track, runs from a location of receiving ink drops to a location of discharge or delivery of the ink drops to a collection tray or the like. At the location of discharge, the conveyor belt turns in an opposite direction in a backward track with the solidified ink drops being taken along. At the lower side of the conveyor belt, after the turning area, a stationary scraper is provided to engage the ink drops attached to the conveyor belt and scrape them from the conveyor belt. A disadvantage of this known arrangement is that the scraper, in order to function reliably, must engage the belt surface causing the belt surface to experience considerable wear and tear.
In a further known arrangement the ink drops falling down are received by a conveyor belt that circulates about four rollers arranged in a vertical square: one upper roller, one lower roller and two side rollers. Considered in a cross-section of the belt, the upper roller has a concave belt supporting surface and the lower roller has a convex belt supporting surface. The concave portion of the belt forms a trough for the ink drops. By the outward flexing of the belt, as considered in cross-section, towards the convex shape, the ink drops on the belt are loosened in order to fall on the bottom wall of the refuse chamber in which the arrangement is positioned below an ink drop inlet arranged in the upper wall thereof. Although the intention here is to loosen the ink drops by the conversion of the shape of the ink drop support surface, that is the belt, which might result in a simple structure, some ink drops, nonetheless, remain attached to the conveyor belt.
Therefore, there is a need for a device for receiving ink drops from a printhead or a printhead cleaning unit and discharging the ink drops into an ink drop collection tray with improved reliable performance. In addition, there is a need for a method for receiving ink drops from a printhead or a printhead cleaning unit and discharging the ink drops to an ink drop collection tray with improved, reliable performance.
From one aspect, the present invention provides a device for conveying ink drops from a receiving station, where the ink drops originating from a printhead are received, to a discharge station, where the ink drops in a dried condition are discharged, wherein the device includes a conveying surface, for example, a conveying driver or a conveyor belt for conveying the ink drops, the conveyor belt having a belt surface for supporting the ink drops during their conveyance from the receiving station to the discharge station, wherein at the discharge station the conveyor belt is provided with means for loosening at least a leading portion of the dried ink drops by changing the path of movement of the belt surface to a vertical plane.
From another aspect, the present invention provides a method for conveying ink drops from a receiving station, where the ink drops originating from a printhead are received, to a discharge station, where the ink drops in a dried condition are discharged, wherein the method includes the steps of receiving the ink drops on a belt conveyor surface, allowing the ink drops to set on the belt surface so as to form dried ink drops at the discharge station, progressively peeling off a leading portion of the set ink drops from the belt surface by changing the path of movement of the belt surface, loosening the ink drops in their entirety from the belt surface and delivering the ink drops to an ink drop collector. In this way, use can be made of the change in direction of the belt that already has to take place for the backward movement of the belt towards the receiving station. The arrangement may consequently be simple and reliable in operation. Advantageously, use can be made of the more or less flat shape and the rigidity of the ink drops, as they are directed in a vertical plane to the path of the conveyor. The change in the configuration of the belt while running past the discharge station automatically results in a peeling off of the solidified ink drops from the belt.
According to a further development of the device according to the present invention, the means for loosening the ink drops includes the steps of progressively diverging the leading portion of the belt surface from the path of movement of the belt surface. The peeling-off effect is improved in the case where the change in direction is sharp. Thus, the means for loosening the ink drops is achieved by changing the path of movement of the belt surface to a convex turning path, in particular a convex turning path with a turning angle of at least 90 degrees.
Advantageously, the radius of the convex turning path is adjusted to the length of the ink drops on the belt surface. By way of example, the radius of the convex turning path may be less than the length of the ink drops on the belt surface. A typical radius used is between 1-6 mm.
In a further development of the device or method according to the present invention, the drying of the ink drops, which are positioned between the receiving station and the discharge station, is accelerated. This can be realized by providing means positioned below the belt surface supporting the ink drops and may comprise a belt supporting cooling plate. The ink drops can be solidified within a short period of time, during which the belt conveyor may be held stationary for a while after receipt of an ink drop, and then shifted to present an adjacent belt surface to the subsequent ink drops that fall down. In this way it is ensured that the ink drops will be solidified to such an extent that they will be rigid in the vertical plane and the peeling off process will be enhanced.
In yet a further embodiment of the device and method of the present invention, additional means for loosening a trailing portion of the dried ink drops from the belt surface are used. Such means for loosening a trailing portion of the dried ink drops from the belt surface includes a stationary stop engaging the loosened leading portion of the ink drops. In this way it is ensured that under all circumstances the ink drops are peeled off completely from the belt surface.
The present invention will now be described by referring to the accompanying drawings, wherein:
The upper track of the belt 5 is supported on a cooling plate 8, which is adapted to cool the surface 5a of belt 5.
Adjacent to idle roller 7 an ink drop collection tray 9 is arranged, which tray 9 defines a collecting space 11. At its upper side, the tray 9 has a curved deflector wall portion 10, which extends above the upper belt track, at the location of the roller 7.
Below the roller 7 the tray 9 is provided with a stop or abutment plate 12, the upper end 13 of which is spaced below the roller 7 and the lower track of the belt 5.
The device 1 of
In
When the plaques 21 have been solidified to a sufficient extent, the drive roller 6 is activated to drive the upper track of the belt 5 in the direction B. As a result, the plaques 21 are conveyed in the direction B, to arrive at the roller 7. As can be seen in
Upon continued movement of the belt 5, the plaque 21 will be moved by the deflecting wall 10 to rotate in direction D. In some cases, the plaque 21 will be completely separated from the belt surface during this movement. In other cases, a small trailing portion 21b of the ink plaque 21 may remain attached to the belt surface. In this case, the lower surface of the plaque 21 will, as depicted in
| Number | Date | Country | Kind |
|---|---|---|---|
| 03078810.3 | Dec 2003 | EP | regional |
