Abstract: A method for correcting Doppler shift-based speed measurements of a projectile where the correction is based upon a two-parameter model for the projectile speed. In one example application, the method is used for correcting the well-known “cosine” measurement error endemic in Doppler shift-based speed measurements is accomplished by comparing the received projectile speed data with parametric curves that are computed in a low-cost microprocessor, and selecting a set of two parametric curves that bound the received projectile data within a sufficiently narrow parametric range so that the initial projectile speed can be computed with the desired accuracy.

Abstract: Sensing when an inkjet printer is out of ink during printing is disclosed. Buffer color information for a swath to be printed next on a sheet by the printer is evaluated. The printed color information for the swath is then measure as the swath is printed on the sheet. If the printer color information is less than substantially equal to the buffer color information, one or more out-of-ink actions, such as notifying the user and/or aborting printing, are performed. A printer performing such sensing is also disclosed.

Abstract: A printhead scans to form marks in a multirow swath on the medium. A mechanism gives relative motion between the head and medium, orthogonal to the scan. Normal advance of the mechanism is at least several rows. There are variants or preferences: in one, the mechanism steps about a row or less to deliberately misalign successive swaths. There is best no associated data shift or normal advance. In another, the step roughly equalizes graininess between image regions with and without normal advance—e.g. between scans near at least one end of a page, to roughly equalize graininess as to swaths near and far from the end. The step best equals different fractions of a row, respectively, between successive swath pairs; these fractions progressively decrease—as e.g. programmed: paperAdvance=Amplitude*cos(Frequency*nPasses+Phase);. Preferably Amplitude is 7; Frequency is 0.2244; nPasses are increments from zero through 7; and Phase is zero.

Abstract: A misalignment compensation technique for a dot printer is disclosed. This technique first supplies printing instructions to a printhead for energizing printing elements in various groups (primitives) to print a pattern on a medium. The printed pattern is then detected by optical sensors in the printer. Based on the detection, a position offset error for each primitive is determined. These errors are used to generate a separate time correction for each of the primitives such that, when the printer is used normally, the time period for printing a dot will be advanced or delayed for each primitive so as to align the dots printed by the primitives. In another embodiment, alignment data taken by a manufacturing line sensor is stored in a memory on the print cartridge. After the print cartridge is installed in the printer, a second optical test completes the data needed to create timing correction values.

Abstract: Techniques to compensate for random and systematic errors when measuring dot placement errors. Error accumulation due to scan axis irregularities during printhead calibration is minimized by swapping alignment block positions on the print medium from swath to swath. Print media advances during the calibration are minimized by the use of a moving reference instead of a constant reference; adjacent groups of nozzles are used to calibrate the following group. Only a small media advance is needed to print alignment blocks using adjacent nozzle groups one beside the other to be calibrated. To prevent paper slip accumulative errors when using moving references, the order of the groups of nozzles is swapped from one paper advance to the other. This randomizes for small, unavoidable slips when advancing the paper and prevents error accumulation.