Method of determining the pen velocity along a graphic tablet, and graphic tablet suitable for carrying out the method
AssigneeU.S. Philips Corporation
InventorKofi Makinwa
Life of this patent
Estimating the term…
Abstract
The invention relates to the determination of the velocity of a conductive pen 102 along a graphic tablet 100. Generation of successive pulses in successive conductors, arranged in a regular pattern in the tablet, produces an electromagnetic signal in a conductive pen situated in the vicinity of the tablet. When the pen is near the writing surface of the tablet, the pen signal exhibits a local maximum which is indicative of the location of the pen. The distance between the edges to both sides of this local maximum constitutes an indication of the velocity of the pen.
Claims25
A method of determining a velocity of a pen in a direction along a graphic tablet, provided with a regular pattern of conductors, comprising:
- measuring an electromagnetic signal caused in the pen by a series, being a succession of elements, each element consisting of successive electric pulses generated in respective conductors and each element of the series causing in the pen a pen signal which is a combination of responses to the pulses of this element, and deriving the pen velocity in said direction from the shape of the pen signal to both sides of a local maximum in the pen signal.
A graphic tablet provided with a pen, comprising:
- a regular pattern of conductors and a first drive unit for generating a first series, being a succession of elements, each element consisting of successive electric pulses in respective conductors, each element of the first series causing in the pen a respective pen signal which is a combination of responses to the pulses of this element, wherein the graphic tablet is provided with a detection unit for deriving a pen velocity in a first direction along the tablet from the shape of the pen signal to both sides of a local maximum in the pen signal.
A method of determining a velocity of a pen in a direction along a graphic tablet having a regular pattern of conductors, comprising:
- applying successive electrical pulses in respective conductors;
- sampling a pen signal arising from capacitive coupling of the pen to the conductors, wherein samples of the pen signal define a signal shape;
- and
- deriving the pen velocity from the signal shape ranging from before to after a local maximum sample value of the samples of the pen signal.
An apparatus for determining a velocity of a pen in a direction along a graphic tablet having a regular pattern of conductors, comprising:
- means for applying successive electrical pulses in respective conductors;
- means for sampling a pen signal arising from capacitive coupling of the pen to the conductors, wherein samples of the pen signal define a signal shape;
- and
- means for deriving the pen velocity from the signal shape ranging from before to after a local maximum of the samples of the pen signal.
A system for determining a velocity of a pen in a direction along a graphic tablet, comprising:
- a regular pattern of conductors;
- a first drive unit coupled to the conductors and arranged to generate successive electrical pulses to the conductors;
- a detection unit coupled to the pen, the detection unit configured and arranged to sample a signal from the pen arising from capacitive coupling of the pen to the conductors, wherein samples of the pen signal define a signal shape, the detection unit further configured to derive the pen velocity from the signal shape ranging from before to after a local maximum sample value of the samples of the pen signal.
Dependencies are inferred from the claim text.