Digital signal processed touchscreen system

摘要

Digital signal processed touchscreen system. The invention employs amplitude ramped signals across a touchscreen. The pattern to which the amplitude ramped electric signals are provided may be located on the surface of the touchscreen, or alternatively on the backside of the touchscreen. The signal processing employed by the invention, using digital signal processing techniques, is operable to discern a user's touch and to determine its location. A dielectric, protective surface is used to enable implementation into a wide variety of applications, including those applications that are environmentally rugged and have, until now, been too rugged for prior art touchscreen systems. The invention employs a user generated unbalanced capacitive load generated on the touchscreen to identify the location of the user's touch.

主权项

1. A touchscreen system, comprising:
a dielectric sheet having a frontside and a backside; a resistive pattern that is attached to the backside of the dielectric sheet; a plurality of drive signal circuits that are respectively coupled to a corresponding plurality of communicative coupling points of the resistive pattern on the backside of the dielectric sheet to produce a first pair of two amplitude ramped fields having inversed gradients with respect to each other in a first direction by applying full scale AC signals to a first set of the plurality of communicative coupling points and virtual ground signals to a second set of the plurality of coupling points at a first time and applying the virtual ground signals to the first set of the plurality of communicative coupling points and the full scale AC signals to the second set of the plurality of coupling points at a second time, each of the amplitude ramped fields communicatively coupling through the dielectric sheet to the frontside of the dielectric sheet, the plurality of drive signal circuits being further operable to measure current flow at the plurality of communicative coupling points coupled to the resistive pattern on the backside of the dielectric sheet, the first pair of amplitude ramped fields including:
a first amplitude ramped field extending across the dielectric sheet in the first direction at the first time, anda second amplitude ramped field extending across the dielectric sheet in the first direction at the second time subsequent to the first time; and a digital signal processor that is operable to:
extract a first unbalanced capacitive component of the measured current flow at the plurality of communicative coupling points at the first time and a second unbalanced capacitive component of the measured current flow at the second time; andderive a location in the first direction of the user's interaction or touch on the frontside of the dielectric sheet by deriving a ratio of the first unbalanced capacitive component to a sum of the first unbalanced capacitive component and the second unbalanced capacitive component.