1. Field of the Invention
The present invention relates to a liquid ejection device employing a liquid ejection head for ejecting a liquid, such as an ink or so forth. More specifically, the invention relates to a printing apparatus for performing printing on a printing medium, such as paper, cloth, non-woven fabric, an OHP sheet and so on. The present invention is particularly effective for a printing apparatus which performs printing for a long period or performs continuous printing on a cloth having printing width of 1 m or more. In concrete, the invention is applicable for office use devices, such as a printer, a copy machine, a facsimile and so forth, a mass-production apparatus, such as a textile printing apparatus, a device for driving an article by an ejected liquid, and so forth.
It should be noted that throughout this specification and drawings, the wordings "print" or "record" means not only the operation for adhering ink on a recording medium, such as paper or the like, but also the operation applying an appropriate liquid for a medium in a broader sense, and includes textile printing for applying dye or the like on cloth, and so forth, for example.
2. Description of Related Art
As conventional liquid ejecting devices, there are devices for performing recording by ejecting a liquid or for ejecting a special liquid and utilizing the ejected liquid. In general, since an ejecting portion for ejecting the liquid is quite small, it tends to cause failure of ejection by causing solidification of dye or pigment contained in the liquid or by adhering of foreign matters to make it difficult to effectively use the ejected liquid. For example, in a recording apparatus, failure of ejection of the liquid results in failure of recording. Normally, in order to avoid such problems, forced ejection of the liquid by suction, pressurization or so forth, cleaning of an ejecting region including an ejecting portion, or ejecting gas or liquid to the ejecting portion in the ejecting region is performed at an appropriate intervals as recovery process.
While ejecting liquid to the ejecting portion by a recovering means to solve ink of increased viscosity or solidified ink and so forth, and washing out the adhering matter with the liquid is effective for avoiding failure of ejection, such method may cause sucking of a washing liquid into an ejection nozzle in the vacuum condition to lower ink concentration and thus causes lowering of printing density.
On the other hand, with a recovering means not employing the washing liquid, the ink of increased viscosity may adhere in the vicinity of the nozzle of the ejection head to cause plugging or ink ejection failure.
Moreover, in the case where the liquid is forcedly discharged from the ejecting portion by sucking, if the ejection head having a plurality of ejection nozzles is employed, an internal volume of a cap to be tightly fitted to the ejection head upon suction becomes large to make vacuum control difficult.
Also, in the method simply contacting a sponge onto the ejection head, if the ejection nozzle with a fine nozzle, such as for 400 dpi, it possibly causes foreign matters to be pushed into the nozzle resulting in causing failure.
Furthermore, in order to avoid accumulation of a mist splashing upon ejection of the ink on the surface of the head to block the ejecting orifice to cause ejection failure or to make ejection impossible (referred to as wet non-ejection), it may be considered to wipe off the surface of the head by a blade. However, when industrial operation is continued for a long period, the wiped ink may have no way to be discharged and thus accumulated and increase viscosity. Therefore, the ejection head may be wiped with the blade on which the high viscous ink is adhering to increase possibility of causing ejection failure. Particularly, in the case of a color recording apparatus, mists from four heads can be collected to make this problem, significant.
In addition, since the head and the wiping means are repeatedly worn, it is desired to take a measure for avoiding shortening of the life. Also, it is desired to perform wiping process efficiently to improve throughput in printing operation.
Furthermore, in the construction where a blade formed of an absorbing body is employed, if ejecting operation or wiping operation is not performed for a long period, or the apparatus body is rested for a long period, the blade may be dried completely so that desired wiping effect cannot be achieved and may affect to the ejecting surface of the head by the wiping operation.