Abstract:
Touch sensitivity is enabled using a touch system that comprises a panel configured to conduct signals, e.g. by TIR, along detection lines across a touch surface. A signal processor operates in a sequence of repetitions to: generate (70, 71) data samples that represent detected signal energy on the actual detection lines; generate (72, 74) based on the data samples, an interpolated sinogram comprising interpolation samples that represent fictitious detection lines which have a desired location on the touch surface; and reconstruct (75) a signal interaction pattern for the touch surface based on the interpolated sinogram. The signal processor implements an error correction (73) to counteract the influence of a change in validity status for a data sample among the data samples, by identifying interpolation samples affected by the change in validity status, and by setting each identified interpolation sample to a value that maintains a relative signal transmission of the fictitious detection line from a former repetition.
Abstract:
A device implements a method of tracking objects on a touch surface of an FTIR based touch- sensitive apparatus. An interaction map is generated (52) that indicates local changes in interaction on the touch surface. The interaction map is processed (53) for identification of positive and negative peaks that represent a locally increased and decreased interaction in the interaction map, respectively. To suppress the impact of interferences, a dedicated first heuristic and/or second heuristic is applied (54) to identify potentially false peaks among the positive peaks. The first heuristic designates a positive peak as a potentially false peak when the positive peak is deemed to be associated with one or more of the negative peaks. The second heuristic designates a positive peak as a potentially false peak when the positive peak is deemed to be located along one of the movement trajectories. Movement trajectories of all objects deemed to exist on the touch surface at a preceding time point are then updated (56) while taking the potentially false peaks into account.
Abstract:
A signal processor implements a technique for detecting objects on a panel which transmits signals inside the panel such that the objects are allowed to interact with (e.g. attenuate) the signals by contact with a touch surface of the panel. The signal processor operates to define cells that have a given location on the touch surface and are associated with a respective set of intersecting paths for the signals across the touch surface. The signal processor operates to obtain (70) an output signal from a signal detection arrangement that measures a signal property for each path; process (71) the output signal to obtain an interaction value for each path; and determine (73-75) a touch status of a selected cell among the cells by analyzing the distribution of interaction values for at least part of the intersecting paths. The touch status indicates presence or absence of one of the objects in the selected cell.
Abstract:
A device implements a method of tracking objects on a touch surface of an FTIR based touch-sensitive apparatus. The method repeatedly operates to generate (50-52) an interaction pattern that indicates local changes in interaction on the touch surface, identify (53) apparent peaks in the interaction pattern, and update (54) existing movement trajectories based on the apparent peaks. An error suppression process (56) is executed at least intermittently in the method to process the apparent peaks and/or the existing movement trajectories to identify implicated trajectories with a potential tracking problem, define two or more movement propositions for each implicated trajectory, and cause an evaluation of the movement propositions in one or more subsequent repetitions of the method. The error suppression process improves tracking by postponing the final decision on how to track the object of the implicated trajectory until more information is available. It also allows the origin of the tracking problem to subside and/or the object to move away from an area on the touch surface that exhibits interferences.
Abstract:
A signal processor implements a technique for detecting objects on a panel which transmits signals inside the panel such that the objects are allowed to interact with (e.g. attenuate) the signals by contact with a touch surface of the panel. The signal processor operates to define cells that have a given location on the touch surface and are associated with a respective set of intersecting paths for the signals across the touch surface. The signal processor operates to obtain (90) an output signal from a signal detection arrangement that measures a signal property for each path; process (91) the output signal to obtain an interaction value for each path; and generate (93-95') a cell value of a selected cell among the cells as either a robust measure of central tendency (e.g. a median) or a minimum/maximum among the interaction values for the intersecting paths. The signal processor determines (97) presence or absence of an object in the selected cell based on the cell value.
Abstract:
Touch sensitivity is enabled using a touch system that comprises a panel configured to conduct signals, e.g. by TIR, along detection lines across a touch surface. A signal processor operates to generate data samples indicative of transmitted signal energy on parallel detection lines at a number of different angles across the touch surface; process the data samples for generation of interpolated Fourier coefficients (f) at grid points in a regular grid in a Fourier domain; and operate a two-dimensional inverse Fourier transform on the interpolated Fourier coefficients (f) so as to generate an interaction pattern for the touch surface. The interpolated Fourier coefficients (f) are generated sequentially for individual groups of grid points. Each individual group comprises grid points that have equal distance to an origin in the regular grid, e.g. grid points that are mapped onto each other by one or more lines of symmetry (L1-L4) in the regular grid. The group-based processing may improve processing speed and/or reduce the need for data storage.