Abstract: X-y positions of a digital pen's tip may be determined by using a calibration parameter to map the x-y positions of the respective centers of images captured by the pen's camera. The calibration parameter may be generated by iteratively calculating estimates of the calibration parameter. Calibration input data may be produced by a user placing the pen tip in a fixed location on a surface, which may be a positionally encoded medium, such as paper, and then rotating the pen and/or moving the opposite end of the pen in various directions to capture multiple images for use in generating the calibration parameter. A user may perform such a calibration procedure without the need for complicated calibration equipment typically used in connection with conventional calibration techniques.

Abstract: An efficient technique is disclosed for determining a portion of a document corresponding to a captured image. When a user employs a pen to create a stroke in a document, images of the document are captured by a camera mounted on the pen. While the location of some of the images will be determined from, for example, an analysis of a pattern on the document that is captured by the image or a pixel-by-pixel comparison of the image with the document, the location of other images will be determined by segmenting the sequence of images into groups that correspond to the shape of the stroke. Information relating to located images in a segment can then be employed to determine the position of unlocated images in the segment. For example, a document search region for an unlocated image can be established based upon the position of a previous located image and a maximum velocity or acceleration of the pen.

Abstract: Disclosed are methods and apparatus for digital control of a head-disk assembly actuator with dynamic velocity compensation. In preferred methods of the invention steps are disclosed in which, the actuator voltage in an HDA is sampled and a velocity error is determined. The voltage applied to the actuator is compensated for the velocity error. Disclosed methods of the invention also include steps for measuring the actual voltage at the actuator motor and alternatively, for calculating the actuator motor voltage using digital processing techniques. A digital voltage command is then provided for applying compensated voltage to the actuator motor. Apparatus for implementing the methods of the invention in a hard drive assembly having an actuator motor is also described.

Abstract: An input device and method for generating electronic ink and/or other inputs is described. The input device may be used in combination with any surface through the use of an improved movement sensing technique for generating data for use in ink related applications and non-ink related applications. Improved motion sensing may be achieved using one or more inertial sensors for detecting movement of the input device by measuring such indicators as velocity, acceleration, and changes in electro-magnetic fields. The input device may include a memory for storing movement data and a transceiver for transmitting data representing movement of the input device to a host computer. Processing of the sensed movement data to generate images representative of hand written strokes may also be performed using a processor within the input device. The input device may be formed in the shape of a pen, and may include an ink cartridge to facilitate movement of the input device in a familiar manner.

Abstract: Disclosed are circuits and circuit architectures for partitioning between a hard disk drive assembly mixed signal spindle motor driver and additional associated digital circuitry.

Abstract: A system and process for determining the location of a captured image from a larger image is described. Using a list of determined locations, the system is able to determine the best or most likely path of a pen tip.

Abstract: A method and system for compressing and displaying a digital ink trace. Raw ink data is smoothed, and sharp points of the smoothed line are found. Curve-fitting is then used to generate a mathematical expression that defines the line segments between adjacent sharp points. The ink trace then is represented by a backbone spline that includes the sharp points and the mathematical expressions for the line segments. Thickness information, such as pressure or acceleration information, is combined with the backbone spline to provide a compressed ink file that represents a contour curve of the original ink trace. A display module uses an algorithm to separate the contour curve into a sequence of straight lines. A set of pixels is then generated for the display of each straight line using a novel antialiasing method. The pixels at the ends of adjacent straight lines are aligned using a weighting algorithm.