Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2001-12-06
2004-08-31
Meler, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06783200
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording apparatus, and specifically, to an ink jet recording apparatus in which an image is recorded by jetting droplets onto a recording medium based on image information.
2. Description of the Related Art
Japanese Patent Application Laid-Open (JP-A) Nos. 10-6521 and 10-114084 disclose an ink jet recording apparatus which includes a sub-ink tank provided at a recording head, a main tank for supplying ink to the sub-ink tank, and an ink sensor for detecting the amount of ink in the sub-ink tank. When the ink sensor detects that the amount of ink in the sub-ink tank is the lower limit or less, ink is supplied from the main tank to the sub-ink tank.
When other operations are stopped in order to supply ink, efficiency decreases. Therefore, JP-A No. 10-315493 discloses an ink jet image forming apparatus in which the other operations can continue even while ink is supplied. The ink jet image forming apparatus is constructed to supply ink only at a fixed time: before conversion of image data ends or after image formation. Ink supplying occurs during a time period where it is possible to sufficiently fill the sub-ink tank, regardless of whether this time period is during the image data conversion or after the image formation.
JP-A No. 11-227220 discloses an ink jet recording apparatus in which the amount of ink jetted and discharged from a head portion is calculated, and the amount of ink to be supplied is controlled in accordance with the results of the calculation or the results of detecting the level of the ink surface in a sub-ink tank by a float.
JP-A No. 11-58768 discloses an ink jet recording apparatus which includes an ink amount sensor mounted to an ink tank for detecting the amount of ink in the ink tank. When shortage of ink is detected by the ink amount sensor during printing, the number of passes and the number of pages are determined based on the detection results, and ink is supplied to the ink tank after a predetermined printing processing.
JP-A Nos. 10-6521 and 10-114084 do not, however, clearly specify when the amount of ink in the sub-ink tank is detected. Therefore, when ink is to be supplied during a printing processing, it is necessary to slow down or stop the printing processing first and then supply ink in order to maintain print quality. As a result, the printing speed decreases. Further, when the level of the ink in the sub-ink tank does not reach a predetermined position, it is determined that ink in the main tank has run out. This means that ink supply operations are performed more than necessary. Thus, it takes a long time before it is determined that ink in the main tank has run out.
Moreover, in the structure of the ink jet image forming apparatus disclosed in JP-A No. 10-315493, when an insufficient amount of ink is detected during execution of a print job including a plurality of pages, ink can only be supplied during image data conversion. Therefore, a printing operation for a subsequent page may be implemented without a sufficient amount of ink being supplied to the sub-ink tank, and ink may run out before printing of the subsequent pages is finished. Further, ink is supplied after image formation, thereby decreasing the printing speed.
JP-A No. 10-315493 also discloses a structure in which ink is supplied during image formation and ink supplying continues for a predetermined time even after the image formation. In this structure, however, the standby time between printing of a page and printing of a subsequent page becomes long. As a result, a problem arises in that the printing speed decreases.
In the ink jet recording apparatus disclosed in JP-A No. 11-227220, when the amount of ink to be jetted varies with the environment, the amount of ink to be jetted becomes smaller or larger than the amount of ink actually jetted. As a result, the amount of ink supplied varies, and ink cannot be supplied in accordance with preset values. Further, since the amount of ink to be supplied is controlled by the float, ink supplying operations continue even if no ink is in the main tank.
In the ink jet recording apparatus disclosed in JP-A No. 11-58768, the number of pages which can be printed is determined based on the amount of ink in the ink tank, which amount is detected by the ink amount sensor. After a predetermined printing processing is finished, ink is supplied based on the determination result. However, in order to determine the number of pages which can be printed, not only whether the amount of ink in the ink tank is no more than a predetermined amount but also the amount of ink actually remaining in the ink tank need to be detected. Therefore, a problem arises in that the ink amount sensor is expensive. Further, in the case of printing an image which requires an ink amount equal to or larger than the amount of ink actually remaining in the ink tank, a problem of image defects arises since ink is not supplied to the ink tank during printing.
As described above, in the conventional ink jet recording apparatuses, the amount of ink in the ink tank for supplying ink to the recording head is detected, and when the amount is the lower limit or less, a signal indicating shortage of ink in the ink tank is outputted. When the amount of ink in the ink tank is insufficient, ink is supplied from a separate ink supply tank. However, since control of the timing of the ink supplying is insufficient, problems may arise in that image defects are caused due to shortage of ink in the ink tank and the printing speed decreases.
SUMMARY OF THE INVENTION
In order to achieve the above object, a first aspect of the present invention is an ink jet recording apparatus comprising: a recording head including an ink tank for storing ink, the recording head being driven and controlled based on image information so as to jet onto a recording medium ink supplied from the ink tank; detecting means for detecting the amount of ink remaining in the ink tank; supply means including a main tank for storing ink, the supply means supplying ink from the main tank to the ink tank when the recording head is disposed at an ink supplying position; and control means for controlling the supply means so that, when the remaining ink amount detected by the detecting means is above a lower limit, ink is supplied during non-recording time in an amount corresponding to the amount of ink used.
In this structure, when the remaining ink amount detected by the detecting means is above the lower limit of the ink in the ink tank, the control means controls the supply means so that ink is supplied from the main tank to the ink tank, which is disposed at the ink supplying position during non-recording time, in an amount corresponding to the amount of ink used. Non-recording time described herein (or during non-printing operations which will be described later) refers to time other than the time ink is jetted onto the recording medium, and typically refers to the time between recording jobs, the standby time for recording, or the preparation time for recording. Ink may be supplied during a job as long as the ink supply does not delay recording, and the non-recording time may be any length of time as long as it does not delay recording. Namely, ink is supplied to the ink tank during non-recording time in an amount corresponding to the amount of ink which has been used. Thus, the time the ink amount reaches the lower limit can be delayed. Further, image defects caused by shortage of ink, and decreases in the recording speed can be prevented. As a result, it is possible to significantly decrease the probability of recording being interrupted by shortage of ink.
The control means preferably estimates, based on the image information, the amount of ink used. Since jetting of ink by the recording head is controlled based on image information, the amount of ink used can be easily estimated by, for example, counting the number of pixels corresponding to the amount of ink jetted. This structure is simpler than a structure in
Ishize Tatsuhiro
Oda Kazuyuki
Soga Mitsuhide
Suenaga Kouji
Do An H.
Fuji 'Xerox Co., Ltd.
Meler Stephen D.
Morgan & Lewis & Bockius, LLP
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