Patent Application
20070263025
Detailed embodiments of the present invention will be described below with reference to the drawings.
First, description will be given of an ink jet printing apparatus provided with an ink tank in accordance with present invention.
The ink jet printing apparatus is based on a non-impact printing scheme which enables high-speed printing and printing of various print media and which minimizes noise during printing. As shown in
The ink tank T2000 is releasable from the print head 6. The print head 6 ejects ink droplets from ejection ports using electrothermal conversion elements (heaters) formed of heating resistors, piezo elements, or the like. With electrothermal conversion element, ink in nozzle is heated by the element to cause bubbling so that the resulting bubbling energy can be used to eject ink droplet from the ejection port.
A capping device 8 is provided at a home position of the print head 6. The capping device 8 has a cap that covers nozzles in the print head 6 having moved to its home position. This prevents the possible evaporation of ink from the nozzles and the fixation of ink in the nozzles. A suction pump (not shown) is connected to the cap through a tube to introduce a negative pressure into the cap covering the nozzles. This enable ink not contributing to image printing to be sucked and discharged from the nozzles (suction recovering operation). Reference numeral 9 denotes a blade that moves relative to the print head 6 to wipe off a surface of the print head 6 in which ejection ports are formed. The ink not contributing to image printing can also be ejected from the nozzles toward the interior of the cap (preliminary ejection). A cleaning operation for cleaning the nozzles and ink channels in the print head 6 may include the suction recovering operation, the wiping operation, and the preliminary ejecting operation.
To print an image, a printing scan performed by the print head 6 and an operation of conveying the print sheet 5 are repeated. In the printing scan, the print head 6 ejects ink from the ejection ports on the basis of image data while moving in the main scanning direction together with the carriage 1. In the conveying operation, the print sheet 5 is conveyed in the sub-scanning direction by a predetermined amount.
The ink tank T2000 is a liquid housing container that houses liquid ink. As shown in
The container body T2017 is formed of, for example, polypropylene. As shown in
A peripheral edge of the flexible film T2004 is soldered to an opening periphery T2016 of the container body T2017. This forms an ink housing chamber that houses ink, between an inner wall of the container body T2017 and the flexible film T2004. The flexible film T2004 comprises, for example, a film including a thin polypropylene film (thickness: about 20 to 100 μm). The flexible film T2004 is urged outward by the spring T2005 via the plate T2022. This generates a negative pressure in the ink housing chamber. Both the spring T2005 and plate T2022 are formed of, for example, a stainless material. The cover T2018 is set in the opening of the container body T2017 to protect the flexible film T2004, which projects outward. The cover T2018 has an air communicating portion (not shown) that sets the inside of the cover T2018, separated from the ink housing chamber by the flexible film T2004, at the atmospheric pressure.
The ink in the ink housing chamber is fed to the print head 6 through the ink supply port T2002. Consumption of the ink contracts the spring T2005 while flexing the flexible film T2004, to reduce the volume of the ink housing chamber. The plate T2022 has an opening T2027 to avoid interference with the support T2023 described below. Thus, the ink in the ink housing chamber can be consumed until the plate T2022 comes into contact with the container body T2017.
The stirrer T2015 is provided with a supported end supported by the support T2023 and a moving end that can be freely swung. The stirrer T2015 can thus be swung in the main scanning direction, which is shown by an arrow X and in which the carriage 1 moves. The stirrer T2015 is composed of a material (for example, SUS) having a specific gravity greater than that of ink. During a printing operation described below and a stirring operation, the stirrer T2015 is swung by an inertia force resulting from the reciprocation of the carriage 1 to stir the ink in the ink housing chamber. The support T2023 has a retainer T2024 at a tip thereof to prevent the stirrer T2015 from slipping out.
An external apparatus (host apparatus) such as a personal computer (PC) inputs a print signal to the ink jet printing apparatus M1000 (step S1). When the print signal is input, the ink jet printing apparatus M1000 loads the elapsed time T from the end of the last reciprocation of the carriage 1, that is, the elapsed time T from the last stirring of the ink in the ink tank T2000 (step S2). The ink is stirred by the printing operation or the stirring operation, described below. The printing apparatus M1000 or print head comprises a timer that measures the elapsed time T.
If the elapsed time T is shorter than a specified time T1, the printing operation is performed on the basis of the input print signal (step S3). In the printing operation, an image is printed on the print sheet 5 in conjunction with the reciprocation of the carriage on the basis of the input print signal. In this case, the stirrer T2015 swings to stir the ink in the ink housing chamber. The printing operation is repeated on print signals sequentially input by the host apparatus (steps S3 and S4). Once the series of printing operations are finished, the process shifts to step S5 to acquire information correlated with the degree of ink stirring involved in the printing operations. The degree of ink stirring depends on the printing amount of the printing operations. Thus, in this case, the information correlated with the degree of ink stirring involved in the printing operations is information corresponding to the printing amount of the printing operations. Specifically, to obtain the information corresponding to the printing amount of the printing operations, the number of carriage reciprocations, that is, the number of scans, is read. The number of scans may be sequentially counted during the printing operation in step S4 and stored in a storage element provided in the print head. In this case, the printing apparatus can load the contents stored in the storage element.
In step S5, a condition (in this case, the number of carriage movements) for the movement of the carriage made to stir the ink in the ink tank is set in accordance with the number of scans as the printing amount during the printing operation. That is, with a large number of scans, that is, a large printing amount during the printing operation (step S3), the ink stirring during the printing operation is at a relatively high degree. Thus, in this case, the number of reciprocations of the carriage during a stirring operation (step S6) is set at a relatively small value. For example, the number of reciprocations of the carriage during the stirring operation is set at 20. A sufficiently large printing amount eliminates the need for stirring. Thus, in this case, the number of reciprocations of the carriage during the stirring operation is set at 0.
On the other hand, with a small number of scans, that is, a small printing amount during the printing operation (step S3), the ink stirring during the printing operation is at a relatively low degree. Thus, in this case, the number of reciprocations of the carriage during the stirring operation (step S6) is set at a relatively large value. For example, the number of reciprocations of the carriage during the stirring operation is set at 50.
Subsequently, the carriage is reciprocated a set number of times to allow the stirrer T2015 to stir the ink in the ink housing chamber (step S6). At this time, since no image printing operation is performed, the reciprocation of the carriage in step S6 is called a stirring operation.
Thus, the number of reciprocations of the carriage for the stirring operation (step S6) is set in accordance with the degree of ink stirring during the printing operation (step S3). This enables the ink in the ink housing chamber to be stirred using the stirrer T2015. As previously described, if a large number of scans are performed to sufficiently stir the ink during the printing operation (step S3), the stirring operation (step S6) need not be performed.
Now, description will be given of the significance of the stirring operation in steps S5 and S6. If steps S5 and S6 are not provided, then after the printing operation in step S3, the process shifts to a standby state (step S8) without performing any stirring operation. Then, if a printing operation with a very low degree of ink stirring which lasts for a time shorter than a specified time T1, precipitation of pigment in the ink tank gradually progresses. If the use state is repeated without performing any ink stirring operation, then when the ink is used up, dense ink deposited at the bottom of the ink tank is rapidly supplied to the print head to cause inappropriate printing. On the other hand, providing steps S5 and S6 allows a resetting operation to be performed, that is, makes the density of the pigment in the ink tank uniform, every time a printing operation is finished. This enables the ink in the ink tank to be used up without causing inappropriate printing in the above use environment.
After the stirring operation (step S6) is finished, a timer is reset to measure the elapsed time T (step S7). The timer starts measuring the elapsed time T at that point of time. Subsequently, to prevent the evaporation of the ink from the nozzles in the print head 6 and the fixation of the ink in the nozzles, the nozzles are covered by the capping device 8 of the ink jet printing apparatus M1000 (step S8).
On the other hand, if the elapsed time T is longer than the specified time T1 in step S2, then in step S9, the carriage is reciprocated a predetermined number of times to stir the ink in the ink tank (stirring operation) before a printing operation. The nozzles are subsequently cleaned (step S10). During the cleaning operation, a negative pressure is introduced into the cap covering the nozzles of the print head to suck and discharge the ink not contributing to image printing (suction recovering operation) as described above. The suction recovering operation allows a predetermined amount of ink in the ink channel and ink tank to be discharged.
Subsequently, a printing operation (steps S11 and S12) is performed as in the case of steps S3 and S4, previously described. Timer resetting (step S13) and capping (step S14) are then performed as in the case of steps S7 and S8, previously described.
If the elapsed time T from the end of the last carriage movement is short, the precipitation of a pigment component in the ink tank is at a relatively low degree and printing results are thus not virtually affected. Accordingly, if the elapsed time T is shorter than the specified time T1, then as in the case of step S3, a printing operation may be performed without a stirring operation, without posing any problem. In particular, with a large printing operation amount, the ink in the ink tank is sufficiently stirred to enable the inhibition of progress of the precipitation of the pigment component without the need for the stirring operation. On the other hand, with a short elapsed time T and a small printing operation amount, the stirring operation (step S6) is performed after the printing operation (step S3). Thus, the time from the input of a print signal until the end of printing does not include the time required for the stirring operation. Therefore, precipitation of the pigment component of the ink in the ink tank can be alleviated without sacrificing the printing speed.
Further, in place of the number of scans (the number of movements) of the carriage, a dot count value may be used as information corresponding to the printing amount. That is, ink jet printing apparatuses print images by ejecting ink droplets from the print head on the basis of input print signals. Accordingly, the number of ink droplets ejected, that is, the number of dots formed by the ink droplets, corresponds to the printing amount. Thus, the number of ink droplets is counted on the basis of print signals (print data) to obtain a dot count value, which can be used as information corresponding to the printing amount. That is, the number of reciprocations of the carriage during the stirring operation in step S6 can be set in accordance with the dot count value.
Further, the present embodiment adopts information corresponding to the printing amount of printing operations as information correlated with the degree of ink stirring involved in the printing operations. However, the present invention is not limited to this. For example, carriage movement duration, which affects the degree of stirring, may be adopted as information correlated with the degree of ink stirring involved in the printing operations.
The stirrer T2015, provided in the ink tank, moves through the ink tank to stir the ink under an inertia force resulting from the reciprocation of the carriage. Thus, the movement range and moving speed of the stirrer T2015 increase consistently with the magnitude of the inertia force acting on the stirrer T2015. Ink stirring efficiency increases consistently with the movement range and moving speed of the stirrer T2015. Accordingly, if the carriage moves at a high speed, the degree of ink stirring can be increased even with a small number of carriage movements during a printing operation. Thus, the ink stirring efficiency varies depending on the condition for carriage movements.
Thus, in the present embodiment, at step S5A, the ink jet printing apparatus loads a printing amount corresponding to a print signal and a print mode set on a driver (program) that controls the ink jet printing apparatus. Then, on the basis of this information, the number of reciprocations of the carriage during the stirring operation in step S6 is set. That is, the present embodiment acquires information corresponding to the printing amount and information on the print mode, as information correlated with the degree of ink stirring involved in printing operations.
The print mode is set by selecting one of, for example, a high-speed print mode in which the carriage moves at a high speed, a normal print mode in which the carriage moves at a normal speed, and a high-quality print mode in which the carriage moves at a low speed. The moving speeds of the carriage in the high-speed print mode, normal print mode, and high-quality print mode are defined as Va, Vb, and Vc, respectively, and are in the relationship Va>Vb>Vc. The stirring operation amount required after a printing operation in the high-speed print mode (step S3), that is, the number of reciprocations of the carriage during the stirring operation (step S6), is defined as N(a). Similarly, the stirring operation amount required after a printing operation in the normal print mode (step S3) and the stirring operation amount required after a printing operation in the high-quality print mode (step S3) are defined as N(b) and N(c), respectively. The stirring operation amounts are set to be in the relationship N(c)>N(b)>N(a).
Thus, the stirring operation (step S6) can be more efficiently performed by setting the stirring operation amount in accordance with the moving speed of the carriage during the printing operation (carriage moving condition). That is, a sufficient stirring effect can be exerted even with a small value set for the number of reciprocations required to stir the ink.
The present embodiment acquires information corresponding to the printing amount and information on the print mode, as information correlated with the degree of ink stirring involved in printing operations. However, it is possible that with the acquisition of the information corresponding to the printing amount avoided, only the information on the print mode, that is, the information on carriage movement conditions, is acquired.
In the description of the first and second embodiments, the number of carriage movements is set as the condition for carriage movements for the stirring operation. However, in the present invention, the movement condition for the carriage for the stirring operation is not limited to this. The degree of ink stirring varies depending on the moving distance, moving speed, acceleration, and moving time of the carriage. Thus, one of the moving distances, moving speed, acceleration, and moving time of the carriage may be set as the movement condition for the carriage for the stirring operation.
The first and second embodiments adopts the information corresponding to the printing amount of printing operations or the information on the carriage movement conditions (movement count and movement speed), as information correlated with the degree of ink stirring involved in the printing operations. However, the present invention is not limited to this example. For example, if the carriage movement conditions vary depending on the type of the print medium used to print images, the number of carriage reciprocations for ink stirring may be set on the basis of the type of the print medium. That is, information on the type of the print medium is used as information correlated with the degree of ink stirring involved in the printing operation. Moreover, the information on the type of the print medium may be combined with the printing amount, carriage movement conditions, print mode, or the like for the printing operation.
The information correlated with the degree of ink stirring involved in the printing operation includes at least one of the printing amount of the printing operation, the information on the carriage movement condition for the printing operation, the information on the print mode, and the information on the type of the print medium.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2006-130794, filed May 9, 2006, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-130794 | May 2006 | JP | national |
