Patent Application
20080024583
Various features and advantages may be exemplified by reference to the detailed description in conjunction with the figures, wherein elements are not to scale so as to more clearly show the details, wherein like reference numbers indicate like elements throughout the several views, and wherein:
Described herein are various embodiments of a hand-held micro-fluid ejection device for ejecting a fluid onto a substrate surface in a plurality of physical orientations. Also described herein is a method for controlling the geometric accuracy of fluid ejection using a hand-held micro-fluid ejection apparatus.
As used herein, the term “hand-held” means that the relative translational motion between the substrate surface and the micro-fluid ejection device is at least in part continuously manually controlled by a human operator rather than by a mechanical device.
As used herein, the term “relative translational motion” generally refers to an arrangement where the substrate surface remains substantially stationary relative to a fixed external frame of reference while the micro-fluid ejection device is moved over the target area of the substrate surface during fluid ejection. However, in some embodiments the ejection device remains substantially stationary relative to a fixed external frame of reference while the target area of the substrate surface moves relative to the ejection device. In some embodiments both the substrate surface and the ejection device may move relative a fixed external frame of reference.
It should also be noted that a distance between the substrate surface and the micro-fluid ejection device may vary in the direction orthogonal to the translational motion between the substrate surface and the ejection device. In a hand-held micro-fluid ejection device this gap between the substrate surface and the ejection device may be mechanically controlled (such as by a fixed dimension spacer) or the gap may be under continuous manual control of the operator. The term “relative elevational motion” refers to motion between the ejection device and the substrate surface in the direction orthogonal to the relative translational motion.
In order to simplify the discussion and provide illustrations of the apparatus and use thereof according to the disclosed embodiments, the following discussion is directed to a micro-fluid ejection device that is a handheld printing device for ejecting ink onto a substrate or media. It will be appreciated that the disclosure is specifically directed to “micro-fluid ejection devices,” however, the principles and methods described herein may be applied to all pattern imprinting mechanisms including, but not limited to inkjet printers, bubblejet printers, thermal printers (both direct and transfer), electrochromic printers, erosion printers, and so forth. It will be further appreciated that the exemplary embodiments may be applied to any handheld micro-fluid ejection device, such as devices used for ejecting cooling fluids, lubricants, pharmaceuticals, and the like on a wide variety of surfaces.
“Translational motion” of the printing apparatus 10 refers to motion in the either the direction of reference arrow 22 or reference arrow 24 or combinations of those directions. The printing apparatus 10 also contains two position sensors 26A and 26B that may be used to provide positional data regarding the position and translational motion of the printing apparatus 10. In some embodiments position sensors 26A and 26B may be combined into a single position sensor, but employing two position sensors having a spatial separation may be beneficial for detecting rotation of micro-fluid ejection head 16 in the plane established by reference arrows 22 and 24.
The printing apparatus 10 may also include a proximity sensor 28 that measures a gap between the printing apparatus 10 and a printing surface. That is, when the printing apparatus 10 is proximate to a printing surface, the proximity sensor 28 measures displacement of the ejection head 16 from the printing surface in the direction of reference arrow 30 (which is orthogonal to the plane established by reference arrows 22 and 24). A configuration of a printing apparatus (e.g., the printing apparatus 10) that is configured with a position sensor 26A, or with a position sensor 26B, or with a proximity sensor 28, or that is configured with a combination of these sensors, is referred to herein as a printing apparatus with a position sensor system.
The printing apparatus 10 may include a display 32 and a “PRINT” button 34 for activating the printing apparatus 10. The display 32 may be used to portray information regarding the image to be printed or a portion thereof, or to portray the status of the printer, or combinations of the foregoing and similar information. The PRINT button 34 may be pressed to provide a print enable signal to the printing apparatus 10 to place ejection head 16 in an enabled state thereby permitting fluid to be ejected from the ejection head 16 through the nozzles 20. The PRINT button 34 is may be released to remove the print enable signal and place ejection head 16 in a disabled state for blocking the ejection of the fluid.
In one exemplary embodiment, the housing 12 of the printing apparatus 10 may include a power supply 36 and an electronic processor 38. The electronic processor 38 is typically configured to receive measured data from the position sensor system (e.g., position sensor /26A, position sensor 26B, and proximity sensor 28). As used herein, the term “configured to receive” refers to direct or indirect receipt of suitable signals between two elements (e.g., the electronic processor 38 and the position sensor system (e.g., 26A, 26B and 28), either directly or indirectly through one or more intermediate elements, to establish the stated configuration (e.g., the measured data are in the electronic processor).
The electronic processor is further typically configured to place the ejection head 16 in an enabled state or a disabled state depending on the measured data. As used herein, the term “configured to place” refers to direct or indirect transmission of suitable signals between two elements (e.g., the electronic processor 38 and the ejection head 16), either directly or indirectly through one or more intermediate elements, to establish the stated configuration (e.g., the ejection head is in the enabled state or in the disabled state). It is to be understood that placing ejection head 16 in an enabled state or a disabled state may not result in any configuration change in ejection head 16. For example, placing ejection head 16 in an enabled state or in a disabled state may involve setting a condition in the electronic processor 38 (or in another element such as firmware or in software) that enables or disables fluid ejection only.
An on/off button 40 may be provided, and a communication link 42 may be provided to transfer information to be printed from an external source such as a computer or personal digital assistant (PDA) device. Communication link 42 is portrayed in
It should be noted that in many embodiments the boundary lines 66, 68, and 70, as well as the coordinate origin 72 and the horizontal reference axis 74 may be virtual features that may established by the printing apparatus and may not be actually marked on the substrate surface 62. For example, the boundary lines 66, 68, and 70, as well as the coordinate origin 72 and the horizontal reference axis 74 may be explicitly or implicitly defined by the geometric arrangement established in the printing apparatus for how the printed image (e.g., 76) is to be formed by a pattern of droplets. In circumstances where, for example, a horizontal reference axis (e.g., 74) is not actually marked on a substrate surface (e.g., 62) but rather is explicitly or implicitly defined by the geometric arrangement established in the printing apparatus (e.g., 10) for how the printed image (e.g., 76) is to be formed by a pattern of droplets, the term “the substrate surface has a horizontal reference axis” means that a horizontal reference axis is explicitly or implicitly established in the printing apparatus.
It should be noted that while substrate surface 62 is depicted in
The present disclosure describes equipment and methods for hand-held printers (or other hand-held micro-fluid ejection devices) that minimize the potential negative impact of non-optimal ejection head orientations on print quality. In general, an electronic processor monitors selected operational parameters related to orientation (both spatial and dynamic) and blocks print whenever those parameters exceed orientation threshold limits. While this action might initially seem to be counterproductive, dealing with unprinted areas is consistent with the nature of a hand-held printer. For example, if an area of the page to be printed is missed or bypassed by the sweeping motion of the operator's hand, then a print quality defect or void remains on the paper until and unless the operator returns with the printer to repair the void. Adding void areas caused by print blocking to those caused by areas missed does not create an incremental usability challenge as hand-held printer design should generally enable returning the printer to those areas for repair.
Typically in the systems disclosed herein, navigation (the sensing & calculation of position on the page) continues even when printing is blocked. In this way the electronic processor remains continuously active and printing is restarted (unblocked) when operation returns within orientation threshold limits. With a hand-held printer, it is difficult to reacquire absolute position coordinates once navigation is lost. In a case where navigation is lost due to operational excess, the operator typically is notified by some means (indicator light, audio signal, etc) so the page can be restarted or (where possible) the absolute position coordinates may be manually reacquired and printing resumed.
As an example, consider the horizontal velocity component as an orientation that may be monitored and used to control print quality. In hand-held micro-fluid ejection devices, optical navigation requires sampling and processing large amounts of data to determine location. Faster speeds require processing more data for both navigation and print scheduling, so for a given computational capability, there will be a limit to how fast the printer may be moved. For example, a maximum speed of approximately eight in sec may be set as an orientation threshold limit above which printing is blocked. It is better to block printing before navigation fails (which, for example, may occur at ten in sec), so the operator may be notified that slower speeds are required.
As a further example, consider the yaw angle as an orientation that may be monitored and used to control print quality. Excessive yaw introduces inefficiency in hand-held printers because less area is swept by the ejection head as it is moved over the substrate surface. Vertical motion (i.e., +/−90° yaw) sweeps an area only a few pixels wide. To allow for yaw, the buffer of data for pixels to be printed grows rapidly in size as the yaw angle increases. In addition, excessive yaw may move a printer support over recently printed areas of the page which can be smeared by contact with the printer supports. For all these reasons, blocking print may be implemented whenever yaw angle exceeds an orientation threshold limit, such as approximately plus/minus thirty degrees. Note that vertical motion (yaw of 90°) is normal when moving the printer at the end of each hand swath, and printing then is probably not appropriate because of the probability of introducing print defects while changing direction.
Other print motion orientations such as rotation and acceleration may be monitored and printing blocked in a manner similar to that previously described for horizontal velocity and yaw angle. For example a plus/minus thirty degree maximum rotation angle may be established as an orientation threshold limit. To prevent mess and unintended damage, printing may be blocked by establishing an orientation threshold limit for the displacement between the ejection head and the substrate surface. As previously indicated, a proximity sensor may be used to estimate the displacement between the ejection head and substrate surface, and printing may be blocked based upon an orientation where the displacement exceeds the defined orientation threshold limit. That excess may be due to such factors as an irregular support under the paper as might be encountered when printing under adverse conditions such as on a plane or in a car where a flat surface is not available.
Implementation of orientation print blocking may be based on detection of an edge of the substrate surface where the printer would run off the substrate surface onto the underlying surface. Orientation print blocking may be used to prevent creating a mess that might result if printing is initiated in an unexpected print position (for example, at a starting location other than near in the upper left of the page), or if the printer is initially poorly aligned with the vertical axis of the paper.
In addition to orientation control, other operational limits may be similarly managed. For example, to avoid damage to the ejection head, printing may be blocked when sustained printing creates overheating at the micro-fluid ejection head.
It is noted that print blocking may be implemented as an optional function that may be turned off/on by the operator in a printer setup menu. For example, print blocking might be turned off for some parameters if a draft print mode is selected and turned on in better print quality modes. It is further noted that the operator may be unaware that print has been blocked during the job, so a means of notification may be implemented to alert the operator that repair will be required. If alerted whenever printing stops, the operator might return promptly to the place where printed stopped and make more accurate repairs. Various means for alerts are envisioned, including lights, sounds, vibration, and display.
The foregoing descriptions of exemplary embodiments of disclosure have been presented for purposes of illustration and exposition. They are not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the exemplary embodiments and their practical application, and to thereby enable one of ordinary skill in the art to utilize the disclosed embodiments with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the exemplary embodiments as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
