Fluid sprinkling – spraying – and diffusing – Distributor continuously moves relative to support during... – Compound motion of distributor or terminal member about...
Reexamination Certificate
2001-04-25
2004-01-13
Mar, Michael (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Distributor continuously moves relative to support during...
Compound motion of distributor or terminal member about...
C239S102200, C239S225100, C239S264000, C347S012000, C347S037000
Reexamination Certificate
active
06676036
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to mechanisms and methods for advancing a fluid ejection system relative to a receiving medium.
2. Description of Related Art
Partial width fluid ejection systems are known to use an advance mechanism that advances a receiving medium relative to a fluid ejector head in a process, or slow scan, direction in conjunction with a carriage that moves along a fast scan direction to facilitate ejecting fluid onto the receiving medium. In a typical fluid ejecting system using this combination of movements between the advance mechanism and the carriage, the advance mechanism moves the receiving medium in a direction perpendicular to the direction of movement of the carriage along the fast scan direction. The carriage houses at least one fluid ejector having a plurality of fluid-ejecting nozzles from which droplets of fluid are placed on the receiving medium in swaths according to the transversing movement of the carriage in the fast scan direction across the receiving medium. The receiving medium advance motion and the carriage motion are coordinated to the extent that the receiving medium advance is stopped while the carriage travels across the receiving medium to place fluid upon the receiving medium.
A variety of configurations have been used to date to provide the dual motions necessary for placing the ejecting fluid upon the receiving medium using a carriage. For example, some known systems use a servo-system including an encoder to accurately move a receiving medium in two modes. The first mode advances the receiving medium a designated distance at the completion of each swath of ejected fluid from the one or more fluid ejector on the carriage. The servo motor provides the first motion mode for advancing the receiving medium. The servo motor provides a second, finer, motion mode to the receiving medium as well. The second, finer, motion mode positions the receiving medium a necessary, though relatively smaller, distance compared to the first advance distance the receiving medium is moved as provided by the servo-motor. The second, finer, motion aligns the recording medium relative to the one or more fluid ejector for receiving second, or subsequent, swaths off fluid ejected from the one or more fluid ejector.
Thus, the dual movements in this servo-motor system require fairly precise co-ordination between the servo-motor and the receiving medium relative to the one or more fluid ejectors. However, servo-motors are prone to deviations in placing the receiving medium, resulting in less accurate placement of fluid upon the receiving medium. Moreover, in those servo-motor printing systems that move the receiving medium in the advance directions in two modes, the accuracy of movement is questionable as well, since it is very difficult to move the receiving medium consistently in the second mode the designated distance W when the distance is an increment perhaps as small as {fraction (1/600)} inch. Moving the recording media such a small distance requires precision media drive rolls, gears, encoders and motors, which add to the cost and complexity of a fluid ejecting system. Moreover, the flexible qualities of recording media render recording media susceptible to positioning variations that are difficult to predict or compensate for, even in a fluid ejecting system that uses high precision elements. A stepper motor could also be used to perform the same dual motions. However, the same or similar problems often occur in stepper motor systems.
Alternatively, some known fluid ejecting systems use a ball and screw carriage advance mechanism, as opposed to the recording media advance mechanism discussed above. The ball and screw carriage advance mechanism is used with a high degree stepping motor that incrementally moves the fluid ejectors when the carriage has completed placing a swath of fluid upon a receiving media. In such a system, the carriage is moved along support rails by operating the ball and screw, to scan the carriage across the receiving medium. The receiving medium remains stationary thoughout the fluid ejecting process. Thus, all the movements in this ball and screw type printing system are by the carriage and fluid ejectors.
A more recent trend among fluid ejecting systems is to use the same general configurations as discussed above, but to increase the number of ejecting nozzles on the fluid ejector while using the same fluid ejector dimensions. The increase in fluid-ejecting nozzles results in a resolution as high as 600 dots per inch (dpi) versus the standard 300 dpi resolution used in earlier fluid ejecting systems. However, the increased number of fluid-ejecting nozzles is not easily achieved. In particular, the precision required for manufacturing fluid-ejecting nozzles has become increasingly more difficult to attain, since an increased number of nozzles is required to provide up to 600 dpi resolution on the same sized fluid-ejector that may have originally provided only enough nozzles for 300 dpi resolution. Thus, the nozzles necessarily become smaller and more difficult to make.
SUMMARY OF THE INVENTION
The above-described prior fluid ejecting systems provide variations of the dual motions along the advance direction needed by the carriage and its fluid ejectors relative to the receiving medium. The servo-motor systems provide movements quickly, but not necessarily accurately. The ball and screw systems provide accuracy but not quickness. Systems increasing the fluid ejecting nozzles on a standard dimensioned fluid ejector result in excess manufacturing and replacement costs.
Accordingly, a need exists for a fluid ejecting system providing a quick, accurate and inexpensive manner of achieving the necessary dual motions of the carriage and its fluid ejector relative to a receiving medium.
In various exemplary embodiments of the fluid ejecting system and methods of this invention, a fluid ejector and carriage are mounted within an interposer frame that is movable along support rails. A separate paper advance mechanism advances the receiving medium a designated distance when a swath is completed. In operation, the receiving medium advances to an initial position for receiving fluid from the fluid ejector, where the fluid ejector is in a first position within the interposer frame. The fluid ejector is biased against a first set of surfaces in the first position by a biasing element. This tends to ensure the fluid is consistently and accurately placed upon the receiving medium as droplets of fluid are ejected from the fluid ejector located in the first position as printing information upon the receiving medium. A spring, for example, may be used as the biasing element. With the fluid ejector in the first position, the carriage travels across the receiving medium, depositing droplets of fluid onto the receiving medium in a swath.
Upon completion of that swath, a position actuator, for example, is energized to urge the fluid ejector to a second position, where the fluid ejector is located against a second set of surfaces. In the second position, the fluid ejector ejects a second swath upon the receiving medium. Thus, whenever the fluid ejector is placed in the second position, the accuracy of placing fluid upon the receiving medium that is achieved is similar to the accuracy achieved by biasing the fluid ejector to the first position. The fluid placement accuracy is achieved regardless of the number, or direction, of swaths being ejected due to consistently placing the fluid ejector against the first and second sets of surfaces corresponding to the first and second positions, respectively.
After a pair of first and second swaths are completed, the receiving medium is advanced to a next position to perform another swath, or pair of swaths, as desired. Thus, the advancing of the receiving medium is easily co-ordinated with the completion of a swath. Moreover, the incremental movement of the fluid-ejector is easily and quickly performed to either of the first and second positions.
Sensors may be used to
Anderson David G.
Carolan Kevin Michael
Zawadzki David T.
Gorman Darren
Mar Michael
Oliff & Berridg,e PLC
Xerox Corporation
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