Surface position location system and method

Abstract

An electrographic sensor unit and method for determining the position of a user selected position thereon. The electrographic sensor unit includes a layer of a conductive material having an electrical resistivity and a surface, at least three spaced apart contact points electrically interconnected with a layer of conductive material, a processor connected to the spaced apart contacts and disposed to selectively apply a signal to each of the contact points, and a probe assembly, that includes either a stylus of a flexible conductive layer spaced apart from the layer, coupled to the processor with the stylus disposed to be positioned by a user in vicinity of a user selected position on the surface of the layer, or that position being selected with a user's finger on the flexible layer and to receive signals from the layer when the contact points have signals selectively applied thereto. The user selected position is determined by the processor from signals received from the stylus, or flexible layer, each in relation to a similar excitation of different pairs of the contact points under control of the processor. The conductive layer may be either two or three dimensional and may be a closed three dimensional shape. There may also be multiple layers with the processor being able to discern on which of those layers the user selected position is located. Further, provision is made to correct the calculated coordinates of the selected position for variations in contact resistance of each of the contact points individually. Additionally, a nonconductive skin having selected graphics printed thereon, such as a map, can be placed over the layer and the proces-sor further convert the calculated coordinates of the selected position to coordinates that relate to the graphical information printed in the skin, and even electro-nically (e.g., audio or visual) present information to the user relative to the graphical location selected as the selected position.

Description

FIELD OF THE INVENTIONThe present invention relates to a system and method for determining a location selected by a user on a surface and providing information to the user that has been determined to be relative to that location. In particular the present invention relates to position detection devices that are able to detect positions on a surface of two and three dimensional objects that have complex shapes. Additionally it relates to position detection devices in which the object may be turned, rotated or otherwise manipulated relative to the rest of the position detection system. Further, the present invention relates to provision of a ground point on the pointing device to ground the user to the system to minimize noise input to the system processor and potential error in position identification.BACKGROUND OF THE INVENTIONA variety of technologies exist to determine the position of a stylus, or even a finger, placed on a surface. One technology is a grid of horizontal and verti...

AI Technical Summary

Benefits of technology

The present invention also includes a probe assembly with a cable with two conductors. The proximate end conductor is coupled to the processor and the proximate end of the other conductor is connected to a signal neutral point. The stylus in turn is coupled to the cable and incorporates therein the distal ends of two conductors with the distal end of the conductor coupled to the processor disposed to receive signals from the layer when the contact points have signals selectively applied to them and the user positions the stylus in vicinity of a selected point on the surface. The distal end of the other conductor is disposed to be contacted by the user when holding the stylus to connect the user to the signal neutral point. To maximize the probability that the user holds the stylus making contact with the contact point, it is located externally and positioned to be contacted by the user during use of the stylus. Further improve that probability, and to increase the comfort of holding the stylus, an electrically conductive contact of a flexible conductive polymer is placed to encircle the stylus at a position to maximize the user's comfort when holding the stylus.

Problems solved by technology

These technologies are limited to displays or flat surfaces.

Position detectors such as the devices disclosed in the Greanias patents, that use many conductors arranged in a grid, are not well suited to a complex shaped surface of either two or three dimensions.

There are, at a minimum, difficulties in positioning and shaping the conductors to fit the contours of a complex shape.

The use of bar contacts or strings of resistors along substantially the entire edge of an object limits their usefulness on objects where the position on the entire surface needs to be detected.

Any variation in contact resistance or changes in contact resistance due to environmental factors are not accounted for and result in detection errors.

The Meadows device is susceptible to the effects of unwanted phantom styluses coupling to the surface.

These phantom styluses cause detection errors because the changes that they also produce cause changes in the driving circuit.

Such cables for the systems of the prior art would be rather large and cumbersome.

Further, connectors with a large number of contacts are expensive and reduce the overall reliability of any system that requires them.

Contacts that allow rotation, such as slip rings or commutators, become prohibitively complex and expensive as the number of connections rises above a small number.

Additionally, the multiple circuits required to drive grid arrays are complex and costly to manufacture.

Acoustic wave detectors provide a rugged position detection mechanism but are costly to implement.

Light wave detection mechanisms are limited to flat surfaces and are susceptible to dust and insects blocking the light paths.

Each of these acts and interacts with each other causing interference and background noise to each other, depending on the intensity of the background or interfering signal.

Thus, as is well known in devices that utilize an antenna as a device to detect an input signal, these atmospheric signals may interfere with the ability to detect and receive a signal of interest.

That added signal, and the multiple frequencies that it includes is also known to potentially add a level of inaccuracy in such a system, if the desired signal can be detected at all.

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