Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-06-05
2004-06-08
Hsieh, Shih-Wen (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S035000, C347S029000
Reexamination Certificate
active
06746096
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording apparatus and a predischarge control method. More particularly, the invention relates to a recording apparatus that records using an ink jet recording head, and a predischarge control method.
2. Related Background Art
The ink jet recording method is utilized for various kinds of printers, copying machines, facsimile equipment, and others, because it has such advantages as lower noises, lower running cost, easier downsizing of the apparatus, and easier recording of images in colors.
The recording apparatus that adopts this method records on a recording medium, such as paper, cloth, non-woven textile, OHP film, by discharging minute ink droplets from fine discharge ports of the ink jet recording head (hereinafter, referred to as a recording head). As a result, if the recording head is in a state where it is at rest continuously without any recording operation and does not discharge ink for a long time, ink in the ink discharge ports (hereinafter, referred to as discharge ports) is evaporated and dried eventually, hence excessively viscose ink or solidified ink being allowed to clog discharge ports to bring about dot mis-alignment (the phenomenon that ink discharge direction may change) or defective discharges. Here, therefore, in order to eliminate such drawback, the ink jet recording apparatus is provided with recovery means for performing recovery process to recovery the discharge condition of ink.
The ink jet recording apparatus (hereinafter, referred to as a recording apparatus) adopts the structure given below in order to solve the problems of dot mis-alignment and defective ink discharges due to the evaporation and drying of ink in discharge ports.
At first, the recording operation is at rest, a cap covers the discharge port surface of a recording head where discharge ports are formed, thus preventing ink in the discharge ports from being evaporated and dried. Should the viscosity of ink increase so as to allow ink to adhere to the discharge ports firmly with the defective discharges that may occur or should foreign substances adhere to the discharge port surface, the suction pump, which is connected to the inside of the cap, sucks overly viscous ink in the discharge ports or the foreign substances adhering to the discharge port surface to expel them. In this manner, recovery is executed to the normal discharge condition (this is referred to as a suction recovery).
Also, for the recording operation of the recording apparatus that adopts on-demand type ink jet recording method, all the discharge ports provided for one recording head are not necessarily used at all the time, and there exist some unused nozzles that are not used for a certain time or more. Also, for the color recording apparatus, which is provided with plural recording heads corresponding to each color ink, a certain recording head is not used entirely in some cases due to the absence of recording data to be transmitted.
Further, for the serial scan type where the carriage, on which heads are mounted, scans for recording, the carriage is required to scan or stop for a continuously long time in a state where the discharge port surface of a certain head, which is not in used, is uncapped, ink in the discharge ports, from which no ink discharges take place, is evaporated and dried. As a result, the ink discharge performance is degraded, hence inviting the degradation of quality of recorded images eventually.
To prevent such phenomenon, it is generally practiced for the recording apparatus to discharge ink at a designated location at intervals of certain time without regard to recording data so that ink in each nozzle is exhausted for replacement with flesh ink. In this manner, ink discharge condition is maintained appropriately at all the time. The ink discharge operation of the kind is called “predischarge”.
Ink discharged as predischarges is directed to the location defined as the predischarge position, which is arranged in the cap of the recovery unit or arranged separately so as not to allow such ink to splash onto a recording medium or the interior of the recording apparatus to stain it. Lastly, then, ink discharged in such a manner is retained in a waste ink tank. The technique with which to discharge ink in the cap is disclosed in the specifications of Japanese Patent Application Laid-Open No. 59-7053 and Japanese Patent Application Laid-Open No. 04-52219, for example.
In recent years, for the enhancement of quality of recorded images, there has been proposed technique such as to improve the water-resistance by making ink insoluble on a recording medium or prevent spreading thereof on a recording medium with discharge of a specially treated recording capability enhancement liquid (hereinafter, referred to as processing liquid), besides ink, thus improving the quality of recorded images. For the recording apparatus that adopts such technique as this, plural receiving portions are arranged on positions apart from each other to receive ink and processing liquid when predischarges are performed. However, the provision of such plural receiving portions for predischarged ink and processing liquid leads to making the apparatus larger inevitably. Here, therefore, there has been proposed the utilization of the interior of cap as the predischarge position for the purpose of making the recording apparatus smaller.
Also, in recent years, it has been demanded to record images on an elongated recording sheet (banner paper) like a drop curtain. When recording on such an elongated recording sheet, the frequency of predischarges increases during recording operation as compared with recording on a sheet of regular size (A4, legal size, or the like) such as a usual copying sheet. The amount of ink used for predischarges increases accordingly. With the structure arranged to enable predischarges to be performed in the cap, the ink, which is pooled in the cap, should be sucked for removal appropriately (hereinafter, referred to as idle suction), and if the idle suction operates during recording operation, the reduction of throughput is invited.
To solve this problem, there has been proposed in the specification of Japanese Patent Application Laid-Open No. 03-234638 an idle suction of ink remaining in the cap each time when one-page portion of recording is completed, while performing predischarges in the cap.
Also, in the case of serial type recording apparatus where the carriage that has recording head mounted thereon reciprocates in the direction at right angles to the conveying direction of a recording medium, such as paper, it is generally arranged to provide the driving source (motor or the like) that drives mainly the carriage, the driving source that conveys the recording medium, and the driving source that drives recovery means for executing the recovery process to recovery the discharge condition of the recording head, and then, the structure is prepared to drive each of them as required. In recent years, however, along with the downsizing of recording apparatus, there have been made available many kinds of apparatuses that adopt the structure arranged to share a driving source for use of the conveyance of recording medium and the performance of recovery means from the viewpoint of cost down, and use such driving source by switching for the purpose. In the specification of Japanese Patent Application Laid-Open No. 01-82962, for example, it has been disclosed that a recording apparatus is arranged to use a motor dually as the motor to drive the suction pump for performing recovery process of the recording head and as the one to convey paper sheet serving as a recording medium.
However, the adoption of the structure, which is arranged to execute the conveyance control and recovery control by driving one and the same motor as the conventional example described above, has encountered the problems given below in some cases.
For example, in a state where recoding mediums (recording sheets, for instance) are set on a recording
Hamasaki Yuji
Kanda Hidehiko
Sakamoto Atsushi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hsieh Shih-Wen
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