MXPA99004721A - Surface position location system and method - Google Patents

Abstract

An electrographic sensor unit includes a layer of a conductive material having an electrical resistivity and a surface, at least three spaced apart contact points (12, 14, 16) electrically interconnected with a layer of conductive material, a processor (30) connected to the spaced apart contacts, and a stylus (20) of a flexible conductive 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.

Description

SYSTEM AND METHOD FOR LOCATING THE POSITION OF A SURFACE Field of the Invention The present invention relates to a system and method for determining a location selected by a user on a surface and providing the user with the information that has been determined in relation to that location. In particular, the present invention relates to position detection devices that are capable of detecting positions on a surface of two and three dimensional objects having complex shapes. Additionally, it relates to position detection devices in which the object can be rotated, rotated or otherwise manipulated in relation to the rest of the position detection system. Furthermore, the present invention relates to the provisioning of a grounding point on the indicating device to ground the user to the system, to minimize the noise input to the system processor and potential errors in the identification of the position.

BACKGROUND OF THE INVENTION There are a variety of technologies for determining the position of a stylet, or a finger, placed on a surface. A technology is a mesh of horizontal and vertical wires, which are placed under the surface of a flat splint or on the surface of a visual display device and emit signals indicating the position, which are detected by a stylus. Two devices that use this type of technology are described in U.S. Patents 5,149,919 and 4,686,332 to Greanias, et al. The applications that use these devices are tablets in a drawing (or digitizing) of computer input, and devices for visual representation of touch screen. In another technology, surface acoustic waves are measured at the edges of a glass plate and used to calculate the position on the plate that was selected by a finger or a stylet. Applications include the use of touch screen kiosk visualization devices, where a conductive coating technology could be used. Other technologies still include the use of photosensitive pencils as optical detectors. Additionally, a frame around a flat display device, with an array of light emitters and detectors around the edge of the frame, may be used to detect when the finger or stylus is near the display surface. These technologies are limited to visual or flat surfaces. The position detectors such as the devices described in the Greanias patents, which use many conductors arranged in a mesh, are not very suitable for a surface of complex shape, either bi or three-dimensional. There are, at least, difficulties in the placement and conformation of drivers to adjust the contours in a complex way. Another similar device is a mesh of horizontal and vertical wires placed above and below the surface of a flat visualization device, which utilizes the capacitive coupling of a stylus or finger. In this device, the capacitive coupling transfers signals that indicate the position of one wire to another, which can be used to calculate the position of the coupling. The computer input slats, as well as the mouse replacement plates that point the finger, use this technology. In another technology, a transparent, homogeneous, rectangular conductor is placed on the surface of a visualization device and plate contacts on the edges of the transparent conductor load the conductor. The capacitive coupling of a stylus or a finger to the transparent conductor causes the conductor to discharge while the sensors attached to the plate contacts measure the amount of current drawn through each of the contacts. The analysis of the relationships of the currents extracted from the pairs of contacts on the opposite sides of the rectangle provides a position XY on the panel that was selected by the user. A device of this type is described in the United States Patent 4, 853,498 to Meadows, et al. An application of this device is a touch-screen visual representation device. A similar technology uses a rectangular piece of extremely uniform resistive material with a series of discrete resistors along the edge and which is mounted on a flat surface. A voltage difference is applied to the row of resistors on the opposite sides of the rectangle, and a voltage difference is applied as a time division to the row of resistors on the other two opposite sides. The signals indicating the position are received by a stylus, or by a conductive coating, which can be pressed to contact the surface of the resistive material. A variety of these devices are described in the United States Patent 3,798,370 to Hurst. The devices described in United States Patents 4,853,498 (Meadows et al.) And 3,798,370 (Hurst) lead to a homogeneous, rectangular, resistive coating with plate contacts on a chain of resistors along each edge. These methods depend on the rectangular shape of a rectangle to work with. The shape and placement of the contacts provide the means to the detection portions of the surface within a rectangular subsection of the resistive material of the surface. Other simple forms with plate contacts and resistor chains are also feasible, but of complex shapes that can create areas that can not be distinguished (for example, shapes with concave edges such as a circle or an ellipse can not be accommodated by any of them). the methods of Meadows or Hurst). The use of plate contacts or chains of resistors substantially along the entire edge of an object limits its usefulness to objects where position must be detected over the entire surface. The locations directly below each plate electrode and between each plate electrode or point and the edge of the object are not detectable in those devices. The devices described in the patents Americans 4,853,499 (Meadows et al.) And 3,798,370 (Hurst), do not take into account the effects of contact resistance. The resistance between the contacts and the homogeneous resistive material can be substantial in relation to the strength of the homogeneous material. Additionally, contact resistance can vary from electrode to electrode or change due to mechanical or environmental stresses. Meadows and Hurst devices rely on contacts of known or constant resistance, which restricts the use of materials and contact methods. Any variation in contact resistance or changes in contact resistance due to environmental factors is taken into account by and results in detection errors. In addition, Meadows charges the surface with a capacitively coupled stylus that determines the position by measuring the current drawn from the exciter circuits. The Meadows device requires four receiver circuits to accomplish this. The Meadows device is susceptible to the effects of coupling undesirable phantom stilettos to the surface. Ghost stilettos, such as rings or fingers, can be attached to the reactive surface instead of, or in addition to, the actual stylet. Those phantom stilettos can cause detection errors because the changes they also produce cause changes in the exciter circuit. In applications, where the object contains the mesh that needs to be rotated, or the electronic devices and the object are physically separated from each other, a large number of conductors must be coupled to the system, or between the elements of the systems, through mechanisms of connection that can allow rotation or other movements. Such cables for the systems of the prior art could also be large and embarrassing. In addition, connectors with a large number of contacts are expensive and reduce the total reliability of any system that requires them. Contacts that allow rotation, such as slideable connector rings, become prohibitively complex and expensive, since the number of connections rises above a small number. Additionally, the multiple circuits required to have the mesh arrays are complex and costly to manufacture. Acoustic wave detectors provide a robust position detection mechanism, but their implementation is expensive. The detection mechanisms of light waves are limited to flat surfaces and are susceptible to dust and insects that block the paths of light. It is believed, however, that the present invention solves those problems. In today's modern environments, there are many sources of electromagnetic energy, both natural and artificial. Some examples of such sources of such energy in the earth's atmosphere are static electricity, lightning storms, thermal lighting, outer space radiation, and man-made radio waves. Each of these acts and interacts with each other causing interference and background noise to each other, depending on the intensity of the background noise or interference signal. Thus, as is well known in devices using an antenna as a device for detecting an input signal, those atmospheric signals may interfere with the ability to detect and receive a signal of interest. It is also known that in systems with a manual antenna probe, the human body acts as a larger antenna with a signal from the person holding the probe added to the signal of interest detected by the manual probe. It is also known that this aggregate signal, and the multiple frequencies it includes, potentially add a level of inaccuracy to such a system, if the desired signal can be detected at all. To overcome this undesirable interference, many elaborate circuits have been devised to suppress those interference signals "captured" by the human user that have an impact on the functioning of the system.

Brief Description of the Invention The present invention includes various apparatuses and methods for determining a position selected by a user on an electrographic detection unit. In more general cases, the electrographic detection unit of the present invention includes a layer of a conductive material having an electrical resistivity with K separated contact points, electrically interconnected therewith, a processor connected to the K separate contact points and arranged to selectively apply a signal to N of the K contact points, where N has an integer value of 3 to K, and a probe assembly, which includes a stylet or a flexible conductive layer placed on the layer, coupled to the processor, the stylet is arranged to be positioned by a user in the vicinity of the position on the layer selected by the user, or the user to point a finger on the flexible conductive layer. In turn, the stylus, or the flexible conductive layer receives the signals from the layer when the contact points have signals selectively applied to them by the processor, with the position selected by the user being determinable by the processor from the signals received from the stylus, or the flexible layer, each in relation to a similar excitation of (NJ) pairs different from the K contact points under the control of the processor, where J is an integer of 2 a (Nl). Additionally, where the electrographic detector includes more than one conductive layer, which are each electrically isolated from each other, in the most general sense, M conductive layers, the present invention is also capable of determining which of those layers contain the selected position. by the user. Here, each layer has K separated contact points, electrically interconnected with the corresponding conductive material layer, where N of the K contact points on each layer are used to locate the position selected by the user, and where N has a integer value of three to K. The processor is also arranged to selectively apply a signal to each of the N contact points of each of the M layers and to determine which of the M layers and position coordinates of the selected position. by the user, on one of the corresponding M layers, cooperates with it to determine and release a signal from the position selected by the user on the selected layer of the electrographic detection unit towards the processor. The identification of the selected layer is carried out by sequentially applying the first selected signal of all K contact points on each of the M layers in turn, inhibiting a first signal measured at the position selected by the user for each of the M layers individually with the first measurement, corresponding to each of the M layers that are the signal received by the means for detection and release, when all contact points on that layer have the first selected signal applied to those layer contact points . Next, a second signal measured at the position selected by the user on the layer selected by the user is measured by each of the M layers with each of the K contact points on each of the M layers in open circuit, followed by the subtraction of the second measured signal of the first signal measured by each of the M layers to form M values of the difference. Those M values of the difference are then each compared against a preselected threshold value to determine which of those M values of the difference are greater than the selected threshold and which exceed this by a higher value. The layer associated with the value of the difference that satisfies those conditions is then identified as the layer containing the position selected by the user. Then, once the determination has been made, the coordinates of the position selected by the user on that layer can be determined as discussed above. The present invention includes techniques for compensating the resistance of the contact at each contact point on the conductive layer, as well as the formation of the conductive layer in a bi-or three-dimensional form, which can be opened or closed. In addition, the present invention includes the placement of a conductive coating on the outer surface of the layer, which coating has a graphic representation thereon and the present invention has the ability to convert the position coordinates of the position selected by the user. from the coordinates of the conductive layer, to those of the graphic representation. Such a graphic representation may be that of a map or a globe, or even a mythical map or one of a star or another planet, carrying out this additional step, those graphical coordinates may be used to electronically provide information that has been pre-stored in the memory, in relation to the graphic coordinates selected to the user. In a real application, the present invention can take many forms, from a conductive layer with or without a non-conductive layer on it and a stylus to be used by the user, to select a position on the layer, up to a multi-layer structure with a conductive lower layer, a compressible, non-conductive inner layer and a conductive, flexible upper layer, wherein the user presses the upper layer towards the lower layer and the point at which the upper and lower layers approach, is determined as the position selected by the user. In addition, several designs are proposed in which the drive and measurement signare AC of a selected frequency or CD. The present invention includes a probe assembly with a cable with two conductors. The near end conductor is coupled to the processor and the proximal end of the other conductor is connected to a neutral point of the signal. The stylet in turn is coupled to the cable and incorporates in it the distal ends of two conductors with the distal end of the conductor coupled to the processor positioned to receive signfrom the layer when the contact points have signapplied selectively to them and the user places the stylus in the vicinity of a selected point on the surface. The distal end of the other conductor is positioned to be in contact with the user when holding the stylet to connect the user to the neutral point of the signal. To maximize the likelihood of the user holding the stylet by contacting the point of contact, it is located externally and is positioned to be in contact with the user during the use of the stylet. Further improvement that probably, and with an increase in comfort when holding the stylet, places an electrically conductive contact and a flexible conductive polymer to encircle the stylet in a position to maximize user comfort when holding the stylet.

Thus, to fully explain the scope of the present invention, a detailed discussion of the different modalities is offered in the Description of the Preferred Modalities below. However, it should be kept in mind that this discussion is not an exhaustive discussion and variations on the main themes, presented as part of the present invention, were also considered.

Brief Description of the Figures Figure 1 is a simplified block diagram of a generalized embodiment of the system of the present invention. Figure 2 is an illustration of the location location algorithm of the present invention for a two-dimensional surface shape. Figure 3 is similar to Figure 2, however, the illustration is for a three-dimensional shape. Figure 4 is a block diagram of a first embodiment of the present invention. Figure 5 is a block diagram of a second embodiment of the present invention. Figure 6 is a block diagram of a third embodiment of the present invention. Figure 7 is a block diagram of a fourth embodiment of the present invention.

Figure 8 illustrates the restrictions on the placement of the contact points that allow to determine the position with only three contacts. Figure 9 illustrates three contact points that can not be used to determine the position on the surface. Figure 10 is a partial embodiment, wherein a multi-layer compressible contact surface is described instead of the use of a stylet, for example, in Figure 4. Figure 11 is a schematic representation of one embodiment of the present invention. , adapted to be an interactive balloon that incorporates a spherical conductive surface. Figure 12 is a schematic representation of one embodiment of the present invention, adapted to be an interactive balloon incorporating two semi-spherical conductive surfaces. Figure 13 is a prior art embodiment of how a potential interference signal is suppressed from the user holding the stylus of the antenna. Figure 14a is a simplified diagram of the stylet and the sheathed cable of the present invention. Figure 14b is another embodiment of the stylet and the sheathed cable of the present invention that ground the user of the system of the present invention. Figure 14c is yet another embodiment of the stylus and the sheathed cable of the present invention that ground the user of the system of the present invention.

Figure 14d is a partial sectional view of the stylet design of Figure 14c to illustrate the internal placement of the sheathed cable and the stylet driver fastener.

Description of Preferred Modes The present invention relates to a system and method for determining a location on a bi or three-dimensional surface of any form selected by a user, as well as to provide access to data storage locations or information stored therein. and that is related to that location. More specifically, the present invention determines the location information in the form of coordinates on a system of predefined coordinates. That location information then serves as a location address within the memory of an associated microprocessor subsystem. That location, or address can be used in turn to retrieve previously stored data belonging to the corresponding location on the surface, to store the data belonging to the corresponding location on the surface, to modify the behavior of the system that incorporates the present invention, or to be presented to the user on a conventional visual representation device or printing device. In surfaces of simple form, such as a rectangle, a minimum of three small electrical contacts are necessary, mounted on the edge of the surface. On surfaces of more complex shape, the minimum number of electrical contacts can be increased to allow the system to determine between multiple locations on the surface, such as the one the user is indicating. At each surface configuration, the contacts need to be positioned so that all locations on the surface can be identified individually. Through the use of small contacts and actuator / receiver techniques, the present invention is also able to compensate for differences in the contact resistance of each of the contacts. The differences that can be compensated include differences between the contacts on the same surface, differences between the contacts on one surface versus those on another surface using the same electronic devices, as well as changes in the contact resistance of the individual contacts during the time due to mechanical and environmental efforts. The present invention determines a position selected by a user on the surface by measuring the unique position, indicating the signals with a receiver as discussed below, for two- or three-dimensional objects, the present invention requires only a single receiver circuit. In the different embodiments of the present invention, the stylet does not load with, or negligibly load, the transmitters and a signal level is measured at the point on the surface that is touched by the stylet, instead of the changes in the stylus. exciter circuit, as in the Meadows device. Additionally, potential ghost stilettos, such as fingers and rings, that have a dramatic effect on the prior art operation, have only a negligible load effect on the transmitter of the present invention. Thus, the present invention is immune to phantom stylets. In the present invention, the active surface can be made of a conductive polymer composition (conductive plastic), or a conductive coating or a non-conductive material. This has substantial cost advantages over the prior art, since coated or lined wires are not necessary, and since the surface itself provides the necessary structural support. The devices embodying the present invention could typically include a surface of a molded or vacuum formed conductive polymer composition that does not require any additional structure, thereby resulting in an additional cost only to the carbon-polymer material, or the applied conductive coating. In addition, the formation of the sensitive surface by injection molding makes it possible to easily create complex shapes that are sensitive to touch. The use of a carbon-polymer composite material as an element in the positioning system and structural support, provide a robust and reliable system. Carbon-polymer composite materials are inherently robust, and the system of the present invention employs a single layer of such material, instead of a multiple layer system, wherein the bonding of the layers can deteriorate and the layers separate. A minimum of three contacts are required to drive an entire surface of a single object (for example, a rectangle, circle or ellipsoid). Additional contacts can be used for complex objects or to provide higher resolution for simpler forms, instead of increasing the sensitivity of the circuit. The low number of contacts and therefore the number of wires, leads to a low cost, ease of manufacture, and allows applications of remote or mobile surface (for example, a rotating globe). An advantage of using a conductive polymer material for the surface is that it allows the contacts to be mounted on the back or inside the surface, and thus achieve a 100% active front or external surface. Additionally, the present invention includes unique surface driving techniques that can compensate for unknown and variable contact resistance. The various contact types and mechanical connection mechanisms create contact resistances, which can vary substantially between contacts, and vary over time with mechanical and environmental stresses such as movement, temperature and aging. Other technologies depend on contacts of resistance to known or constant contact, without any change not compensated in the resistance to contact that results in errors in the detection of the position. The present invention allows the use of various mechanisms to compensate for differences and variations in contact resistance. Each of these mechanisms can be used and provides its own advantages. A possible mechanism involves using two electrodes as each contact, with those electrodes being very close and interconnected electrically, but not touching each other. The first of these electrodes in this configuration is linked to the source of actuation of the signal, and the second of those electrodes provides a high impedance feedback path. In this configuration, the drive source of the adjusting signal, so that the signal level at the second electrode is of a desired value, thus providing a known signal level at a point on the surface regardless of the resistance To contact. The drive method, here also provides automatic adjustment of changes in the resistive material with time and temperature, as well as variations in contact resistance.

A second possible mechanism has only one electrode per contact and measures the resistance value of each contact for the resistive material of the surface. In such a system that has three contact points, A, B and C, a signal level measurement is made at point C through a high impedance path, while a signal of a known level is applied between point A and point B. Next, similar measurements are made at point B with the signal applied between point C and point A, and at point A with the signal applied between point B and point C In this way, knowing the positions of the contacts on the surface and the resistivity of the surface material, the resistance to contact between points A, B and C and the material of the surface as discussed below with respect to Figure 6. Additionally, the present invention incorporates the use of a multi-state excitation drive sequence to provide rapid on-the-fly measurement and calibration to improve accuracy. The stylus is used to make several measurements of the signal at a point on the surface of the object selected by the user. A first measurement is made without signals applied to the contacts to determine a baseline CD deviation, and the environmental noise level for the surface, which, for discussion purposes here, is called CD DEVIATION.

A second measurement is made with a signal applied to all contacts to determine the value of the full scale signal, which, for discussion purposes here, is called COMPLETE SCALE. Then another measurement is made by applying a signal to a pair of contacts to create a signal level gradient across the surface between those two points, which, for discussion purposes here, is called the X-axis and the measured value of X. Next, a signal is applied to another pair of contacts to create a signal level gradient in another direction, which, for discussion purposes here, was called the X-axis and the measured value of Y. Then, The following calculations are made by a system to determine the selected location along the X and Y axes defined on the surface. Px = (X - CD DEVIATION) / (COMPLETE SCALE - CD DEFLECTION) (1) P? = (Y - CD DEFLECTION) / ((COMPLETE SCALE - CD DEFLECTION) (2) The current position on the surface, can then be determined from Px and P? Using a mathematical model, or empirically determined, of the gradients of the signal level for the surface material In the present invention, the required basic points (ie the algorithm and the conductive material) have existed for some time.The bases for the algorithm date back centuries. those that are suggested for the surface material here, which have similar electrical properties, have existed for decades.The basis of the algorithm of the present invention is the use of triangulation to determine the location of the point on the surface of the object The triangulation is defined as - * The location of an unknown point, as in navigation, by forming a triangle that has the unknown point and two known points as vertices' '' [The American Heritage Dictionary of the English Language, Third Edi tion). Triangulation is a basic principle of trigonometry and its use to find the location of a point on the surface of an object has been used for centuries. This is used in applications such as celestial navigation, surveying, global positioning system (SPG), and seismology. In the present invention, as in the case of triangulation, the position is determined by measuring the relationship at a point of interest with two known points. The ratio is determined from the signal level received in the stylus by injecting signals of known levels at the first two fixed points at the same time. All points on the surface that could have that level of signal create a line of possible positions. Another relationship is determined using two other fixed points (a different pair of contacts, however, one contact can be one of those that was included in the first pair of contacts) and another signal level received from the stylus. The intersection of two lines of possible positions of the two measurements tells us in this way where the stylus touched the surface. For some surfaces, this may be unique, such as a two-dimensional surface or a hemisphere with the contacts mounted on the edge or at the equator. In theory, any position in three-dimensional space can be uniquely identified by its distance from four known non-coplanar points, while the required number of known points can be reduced in some cases if possible positions in three-dimensional space are restricted. For the purposes of the present invention, the position of interest is restricted to that which is on the surface of the shape of the known surface. For a shape such as a rectangle or circle, a position on the surface can be defined by its distance from three known points on that surface, provided that the known points are all at the edge of the surface shape or are not collinear. For continuous surface spheres or ellipsoid shapes, a position on the surface of the form can be defined by its distance from three known points, provided that the plane defined by the three known points does not include the central point of the form. For a cylindrical shape, a position on the surface can be defined by its distance from three known points, provided that the plane defined by the three known points does not cross the central line of the cylinder. For a relationship to be determined between a contact and a point on the surface, the point must be in the field of view of a pair of contacts. That is, as shown in Figure 8, for any point X is in the field of view for a pair of contacts A and B, the included angle, i, between the vectors drawn between A and B, and A and X, as well as the included angle, Bi, formed by the vectors drawn between B and A, and B and X, must both be less than 90 °. Additionally, the surface must contain electrically conductive material between points A and X and between X and B. Figure 9 illustrates a situation where point X is not in the visual field of points A and B, since the included angle B is greater than 90 °, even when the included angle Ai is less than 90 °. In practice, more contact points can be used due to the finite resolution of the actual measurement devices. Another factor that can increase the number of contacts is the cost. A relationship can be constructed between the resolution of the receiver and transmitter circuits, and the number of contacts between which the signal is applied to the surface for measurements. If more contacts are used that are closer, then the resolution of the transmitter / receiver circuit can be reduced. The use of resistivity in materials to measure distance or position has been common for some years. A first example is the use of rotating or sliding potentiometers to determine the position of a button or slider. The conductive polymers which could be employed by the present invention have been known since at least 1974 when CMI, a first producer of conductive polymeric compounds, was purchased by 3M Company. At least the materials and algorithms used by the present invention have already been available for 20 years, and in total probably more. However, the literature does not teach or suggest the combination of those elements to produce a device similar to that of the present invention, in fact all the teachings of known references are far from this technique. In Figure 1, the basic components of the location location system selected by the user of the present invention are shown. They include two or three dimensional conductive surfaces 10 (e.g., plastic with charge of carbon or a conductive coating applied to a non-conductive surface) having a resistivity selected with three conductive contacts 12, 14 and 16 fixed thereon. Each of the contacts 12, 14 and 16 are connected via the connectors 24, 26 and 28, respectively, to the processor 30. Also connected to the processor 30, the conductor 18 is located with a stylet 20 having a tip 22 fixed to the other end thereof for the user to use to indicate a position on the surface 10 that is of interest to that user. Next, as in Figure 2, when a user selects a point on the surface 10 with the stylet 20, a series of measurements are made as generally described above. First, without any signal applied to the contacts 12, 14 and 16, the processor 30 measures the value of the CD DEFLECTION of the system with the stylus 20.; Next, a signal of equal amplitude is applied to the three contacts 12, 14 and 16, and the processor 30 measures the value of the COMPLETE SCALE signal with the stylet 20; The third measurement is made by applying a signal of the amplitude used in the full scale measurement to one of the three contacts, say the contact 12, with a second contact connected to ground, that is, contact 14, and the measurement of the signal is made with stylus 20, which will be somewhere along an equipotential alignment between those two contacts (ie, line X in Figure 2); A fourth measurement is made by applying the signal to, and connecting to ground, a pair of different contacts, say 12 and 16, and the measurement of the signal is made with the stylet 20, which will be somewhere along the an equipotential line between those two contacts (ie, the line Y in Figure 2), with the position of the stylet 20 being the intersection of the lines X and Y; y The values of Px and PY are then calculated as in equations 1 and 2 above. In the actual operation, each of these steps can be automated by the processor 30, without requiring the user to initiate the specific measurements or to switch the signals. The values of Px and PY can then be used as an address for a memory inside the processor 30, from which information relative to the position indicated with the stylet can be obtained. This same technique can also be used to determine the address in memory, where the data should be stored initially for later retrieval, or as an address on a remote visual representation device that can be activated for any purpose. Each unique position on the surface is defined by a unique combination of values of Px and P ?. From the series of measurements described above, the position of the stylus on the surface can be expressed in terms of Px and PYA which were the so-called equipotential coordinates. Additional calculations can also be made to convert the position of the equipotential coordinates to another coordinate system, if desired. The conversion requires the mapping of a known map of the equipotential coordinates to the desired coordinate system. The map trace can be determined mathematically for an object made of a homogeneous conductive material, or one in which the distribution of the resistivity is known. For objects in which the distribution of resistivity is unknown, the map trace of the equipotential coordinates to the desired coordinates can be determined empirically. In any case, the trace of the map can be stored in the memory of the microprocessors and the conversion calculations carried out by the microprocessor. Figure 3 illustrates the same method to determine the values of Px and P? on the surface that has a definition equation that is continuous over the entire surface, for example, a hemisphere as shown. The surface 10 of the present invention uses materials such as carbon-charged polymers or conductive coatings (for example, Velostat 1840 or 1801 of 3M) which can be easily molded into, or applied to, bi-or three-dimensional surfaces, including surfaces that They have complex shapes. A minimum number of driver circuits and connections between that surface and electronic detection devices will further reduce the complexity in the electronic and mechanical aspects of surface coupling to electronic devices. More specifically, the different embodiments of the present invention are described in the following paragraphs and are illustrated beginning with the Figure. The embodiment, shown in Figure 4, includes a rectangular piece of conductive material such as sheet 100 (eg, a 12 inch x 12 inch x 0.125 inch sheet of a carbon loaded polymer, such as 3M Velostat 1801) . The conductive material may also be composed of a non-conductive material with a conductive coating such as Model 599Y1249 from Spraylat Corp.

Fixed near the edge of the sheet 100, and making electrical contact between them, are the contacts 102, 104 and 106. Connected between the contacts 102, 104 and 106 on the sheet 100 and contacts 126, 128 and 130 of the signal generator 122, respectively, are the electrically conductive wires 108, 110 and 112. The signal generator 122 includes an AC (alternating current) signal generator of 60 KHz 124 which supplies the amplifier 134 with the output terminal without inverting the amplifier 134 connected to three separate terminals (one corresponding to each of the contacts 102, 104 and 106) of the switch 132, and the inverting output terminal of the amplifier 134, connected to three terminals (one corresponding to each of the contacts 102). , 104 and 106) of the switch 136. Next, each of the contacts 126, 128 and 130 are each connected to different terminals of each of the switches 132 and 136. In Figure 4, each one of the switches 132 and 136 are shown in the open position (ie, no signal applied to any of the contacts 126, 128 and 130). In turn, the position of each of the switches 132 and 136 is controlled via wires 138 and 140, respectively, of the microprocessor 142 to allow the microprocessor 142 to select which of the contacts 102, 104 and 106 receives a signal of 60 KHz. through the switch 132 via the associated control cable and which of the contacts 102, 104 and 106 receives an inverted signal of 60 KHz through the switch 136 via the associated control cable. When the 60 KHz AC signal is connected to one or more contacts 102, 104 and 106 that radiate the signal through the conductive material of the sheet 100, and the stile 116 acts as an antenna when it is brought near the surface 100 A signal detected by the stylet 116 is in turn driven to the measurement stage of the signal 120 via the sheathed cable 118. In this embodiment, the stylet 116 is completely passive and could be fabricated simply consisting of a surrounding plastic liner. the end of the cable 118 with 178 end inches of the cable 118, at the distal end of the stylet 116, which has the liner removed to allow the center conductor of the cable 118 to be exposed to receive the radiated signals. In this way, when the tip of the stylet is close to the surface of the conductive material 100, the radiated signal is received by the antenna of the stylet, and provides it as an input signal to the measurement step of the signal 120. The stage signal measurement means 120 includes a demodulator 144 which is connected to the cable 118, wherein the signal received by the stylus 116 is demodulated and the demodulated signal is in turn, presented as a signal level to an analog-to-digital converter (CAD) 146. The CAD 146 then digitizes that signal level and presents it to the microprocessor 142. The use of an AC signal in this mode makes it possible for the stylet 116 to receive the radiated signals from the conducting material of the sheet 100 without being in direct contact with the conductive material of the sheet 100. This allows the conductive material of the sheet 100 to be covered with a layer of a non-conductive material for unavoidable protection against shock e the surface of the sheet 100 with the stylet 116, or for the placement of application-specific graphics on the contact surface, and still allow the stylet 116 to act as an antenna to receive a signal from the sheet 100 at a selected point that must be measured by the measurement step of the signal 120. The microprocessor 142 has the codes to direct the operation of a series of measurements with different contact sets 102, 104 and 106 connected to receive the 60 KHz signal, or the inverted signal of 60 KHz. Once a user has selected a point of interest on the sheet 100, the system of the present invention, performs a series of measurements in rapid succession (for example, time division multiplexing) to determine the location to which the stylus is pointing and to provide the user with the information it is looking for. The first measurement, as explained above, is the one here called SIGNAL Signal, and involves placing switches 132 and 136 in fully open positions. The microprocessor 142 then reads the signal level of the signal measurement stage 120 and assigns that value to the SignalSign and stores that value in the RAM (random access memory) 144. The second measurement, as explained above, is the here called SeñalcoMPETA, which involves connecting a 60 KHz AC signal to all the contacts 102, 104 and 106 at the same time closing the three sets of contacts on the switch 132. The microprocessor 142 then reads the level of the signal of the stage of measurement of the signal 120 and assigns that value to the SignalMPAT and stores the value in the RAM 144. Next, the microprocessor 142 selects a pair of contacts, say 102 and 104, for use in the next measurement. The contact 102, for this discussion, is a point A and is connected to receive the 60 KHz AC signal via the switch 132. The other of those two contacts, the contact 104, which for this discussion is a point B, is connected to receive the 60 KHz AC signal inverted via the switch 136. The third contact 106 is simply connected to the open positions of the switch on both switches 132 and 136. The microprocessor 142 then stores the level of the signal of the stage of measurement 120 in RAM 144 and assigns that value to the so-called RECTIFY-AB. Between the energized contacts 102 and 104, an equipotential map of the signal level 114A could be drawn due to the effect of the distributed resistance in the conductive material of the sheet 100. The equipotential maps of signals such as 114A, 114B and 114C, including the The shape and values of the equipotential signal level lines are stored in the RAM (read only memory) 146. As discussed in Electro agnetics, by John D. Kraus and Keith R. Carver, McGraw-Hill, 1973, pp 266-278, these equipotential signal maps are created by finding the unique solution to the Laplace equation (s2V = 0) that satisfies the limit conditions of the leaf 100 and each pair of contacts. There are many methods to find the solution to the Laplace equation for an object, including, but not limited to, direct mathematical solutions, point-to-point computer modeling, and empirical determinations. For the homogeneous conductive material and simple forms, a direct mathematical solution can be easily obtained. For materials, whose homogeneity, form or placement of the contact does not lend itself to other methods, the empirical determination can be used.

In the method of empirical determination, a coordinate system is chosen and placed on the device. To determine the map for a specific pair of contacts, such as 102 and 104, the contacts are energized in the same way to measure the previous S-N RECTIFY-AB Signal. At each crossing point on the chosen coordinate system, the value of the RECTIFY-AB signal is measured. • If the intersection chosen granularly is sufficiently fine, the equipotential map can be obtained directly by finding the points containing the same measured value. In other circumstances, the equipotential lines can be calculated by interpolating between the measured points. For the third embodiment, microprocessor 144 selects another pair of contacts, such as 102 and 106. Contact 102, which, as discussed above, will again be referred to as point A, is connected to receive the AC signal. 60 KHz via switch 132 and is the only one of the contacts thus connected. The other contact 106, which, for this discussion is referred to as a point C, is connected to the 60 KHz reverse signal via the switch 136. The microprocessor 142 then registers the signal level of the measurement step of the signal 120 and assign that value to the so-called SEND ™ RECTIFY-AO signal The two signals, SEND ™ RECTIFY-AB and RECTIFY-AC / SIGNAL are affected not only by the resistance of the material between the contacts, but also by numerous other factors, including the altitude of the stylet 116 from the surface of the conductive material of the sheet 100, to the attitude or angle of the stylet 116, and changes in the circuits due to environmental changes, aging or other factors. The signal SeñalcoMPETA / is equally affected by the altitude, attitude and changes of the circuit, although it has an equipotential map of constant signals, so the value of the Signal 8MPi, ETA can be used to normalize the values of the Seña ™ RECTIFY-AB and the SEND ™ RECTIFY-AC to remove the effects of altitude, attitude and changes in the circuit using the following formula. Signal NORM = Signal ™ RECTIFY / Signal MP E A (3) The Signal ™ RECTIFY and Signal ETA are affected by certain changes in the circuits that produce a deviation of CD to the final values. Equation 3, if desired, can be modified to remove those effects as shown in equation 4 below. SignalNORM = (Signal RECTIFY _ Signpost IADA) / SignalMP E A - Signal DEVIATED) (4) Applying any of the formulas of equations 3 and 4 to each of the RECÍFICAR-AB and RECAL-AC signals, the normalized signals, NORM-AB and SenaluoRM-Ac signals can be derived. For example, using the signal map 114A and the NMR-AB signal value, the position of the stylus 116 can be solved to a single signal level line, such as 115, between the contacts 102 and 104. Using the predetermined signal map 114B and the value of the NoRM Signal -Ac, another signal level line may be determined on the signal map 114B between the contacts 102 and 106. The position of the stylet 116 is then resolved at the point, P, where the line of the signal level selected by the Signal N0RM- AB at 114A crosses the signal level line selected by the NoRM-Ac Signal at 114B. The use of the resolved point, P, is qualified by the microprocessor 142 by comparing the value of the SigncoMPET with a predetermined threshold level to determine whether the received signal is valid. This threshold is determined in a general way empirically to satisfy the resolution requirements of the application or the user. When the altitude of the stylet 116 from the surface of the conductive material of the sheet 100 is reduced, the received signal is stronger and the resolution of the position is more accurate. Some applications, such as dotted tablets, may desire a specific amplitude threshold to meet the user's operating expectations. In those applications, users do not expect the system to recognize the position of the ss until the tip is in contact with the surface. Other applications may desire a greater or lesser degree of resolution. The application can select the altitude threshold that best fits the requirements. When a threshold of the HANDBOOK signal for a particular application is satisfied, the resolved point, P, is considered valid. The measurements outlined above are done in succession, and each measurement can typically be done within 4 msec, so that the entire sequence is completed in 16 msec. This is important, since the measurement sequence needs to be completed quickly, so that any changes in the ss position between measurements are minimized. Substantially faster sampling times may be used, provided that the capabilities of the signal measuring device are appropriately selected. To support an application that requires a series of locations of the st to be measured in rapid succession, a sampling time that is substantially faster than the movement of the st needs to be chosen. An application that could require the successive detection of the location of the stiletto, could be an electronic trace tablet, where the succession of points could form a line. An application of this type may require sampling times of the order of 200 microseconds.

In the embodiment discussed above, the signal generator 122 produces an AC signal of 60 KHz, however, a DC voltage level could alternatively be used. With a CD signal level instead of the 60 KHz signal, the ability to detect the position of the stylus without making contact between the stylet 116 and the conductive material of the sheet 100 is eliminated. Since the direct contact is made with the stylet and the material, the effects of the altitude and posture of the stylet do not contribute any more to the measurement of the RECALD ™ because the altitude and posture of the stylet are the source of dominant variation in the measurement of the Seña ™ RECTIFY. L elimination of the altitude and posture of the stylet by measurement, reduces, or eliminates, the need to normalize the signaling RECALIF with the signaling P ETA '. Further measurements can also be made (contacts 104 to 106, ie, B to C) to refine / confirm the point at which the stylet 116 should be pointed with a minimum number of measurements. The microprocessor 142 could also be programmed to filter the measurements to dampen the changes made by the movement of the stylet 116 and to increase the resolution. The synchronous detection techniques in the receiver demodulator substantially improve the noise immunity. The received signal is multiplied by the signal transmitted with a FET switch (for example, DG441). The resulting multiplied signal is then integrated to determine the CD component. It is this integrated signal that is presented to the CAD for the conversion. The net effect of multiplication and integration is that only the signals received from the same frequency and phase of the transmitted signal are observed. It is considered that such signals are synchronous with the transmitter, and hence the name of synchronous demodulation. Effective noise immunity is achieved, since, in general, noise sources will not synchronize with the transmitter, and therefore, will not be observed after multiplying and integrating. Only the desired position of the transmitted signal that has been detected by the receiving stylus will be measured. Special techniques can be used to improve accuracy near the edges of a conductive surface. On surfaces of certain shapes, the equipotential lines can be almost parallel near the edges, which tends to reduce the positional accuracy. The distance to the edge can be estimated from the SignalMPET only, since the SignalMPETA tends to fall somewhat near the edge. Applying an estimate of the edge distance to the point determined by the intersection of the two equipotential lines near the edge can help improve positional accuracy in some cases.

In cases where two electrically insulated surfaces end along the same edge, such as the equator in a globe made of isolated North and South hemispheres, improved techniques can be used to improve positional accuracy near the edge. In such cases, the distance from the edge, can be estimated by comparing the SignalMPET of both surfaces, and using the signal ratioMPETA- to SignalCoMPLETA-B to help eliminate the effects of altitude and attitude. Once the position indicated by the user is determined, the system could be used in an application where the information relative to that position has been pre-stored, it will be stored, in the total system. To allow that application, the RAM 144, RAM 146, audio / video card 150 and DC ROMO unit 156 are shown interconnected with the microprocessor 142 via a collective data bus. For example, if the surface 100 has a pattern of an overlay map there may be pre-stored information in the ROM 146 or in a DC (compact disc) in the DC ROM unit 156 that may be provided to the user in audio or visual form via the audio / video card 150 and the speaker 154 or monitor 152. The contact resistance of the connections between the contacts 102, 104 and 106 and the conductive material of the sheet 100 can play a significant role in defining the absolute levels of the signal in the signal maps (114A, 114B and 114C). That resistance to contact affects the absolute value of the signal level, but has only a minor effect on the shape or distribution of the signal lines. In some cases, the contact resistance between a contact and the conductive material of the sheet 100 may be of a similar or higher value to that of the resistance through the conductive material between different contacts. The resistance between a single contact and the conductive material is also subject to changes over time, due to chemical or mechanical factors. The contact resistance of the conductive material can also differ from unit to unit in a manufactured product. To automatically compensate for differences in contact resistance of the conductive material, which is solved in the embodiment of Figure 4, by means of a calculation, another embodiment of the present invention is shown in Figure 5. As can be seen, by comparison of Figures 4 and 5, many of the elements of the two circuit modes are the same and are connected in the same way, in particular the sheet 100, the signal measuring step 120, the microprocessor 142 and associated components, signal generator 124, amplifier 134, and switches 132 and 136. Additional elements in Figure 5, which are described below, have been added to provide automatic compensation for differences of resistance mentioned above. The first difference between the two figures is found in the structure of the contacts fixed to the sheet 100. In Figure 5, said in simple terms, a single contact is replaced as shown in Figure 4 with a pair of contacts connected. A first contact of each connected pair was used as the point at which the signal generator connection was made, while the second contact of the connected pair was used as the point at which the measurements of the signal level were made, and in which the adjustments of the level of the signal that was injected to the first contact in that for connected were made, so that the level of the signal in the measured point is a known level. For example, contact 102 in Figure 4 was replaced with connected pair 202a and 202b in Figure 5. In this embodiment, contact 202a could be a 0.16 cm (0.0625 inch) diameter contact placed at the same point. on the sheet 100 as the contact 102 in Figure 4, the conductive material of the sheet 100 was used as the point of injection of a signal. Similarly, the contact 202b could be a contact of 0.16 cm (0.0625 inches) diameter placed at 0.635 cm (0.25 inches) from contact 202a and used as the point at which the level of the signal at the associated point on leaf 100 was measured.

The second difference of the embodiment of Figure 4 is the connection of the output terminal of each of two amplifiers of the input terminal 220, 224 and 228 (e.g., MC4558) to the contacts 202a, 204a and 20da, respectively. Each of the amplifiers 220, 224 and 228 has the input terminal connected to an output terminal different from the switches 132 and 136. Each of the amplifiers 220, 224 and 228 has the negative input terminal connected to a different input terminal. the contacts * b "of each connected pair attached to the sheet 100 (ie the contacts 202b, 204b and 206b) When the input signal passes through the contact resistance, the level of the signal decreases. contact resistance changes, the level of the signal changes inversely proportional to the change in the resistance of the contact.Therefore, if such change in the level of the input signal is inversely compensated in another way, any change in the level of the contact The signal resulting from a change in the resistance of a contact is denied.The experts in the technique of closed circuit feedback theory will recognize that the contacts, b "of the sheet 100, provide feedback. to the contact drive amplifier "" to "202A, 204a and 206a, so that those amplifiers can detect any decrease in signal level due to contact resistance, and provide the necessary reinforcement to the signal to compensate losses. An alternative mechanism for compensating the contact resistance is to determine the current value of the contact resistance and to adjust the absolute values in the signal map based on any change in the value of the contact resistance. The modality shown in Figure 6 performs that function. Comparing again the embodiments of Figures 4 and 6, several similarities can be noted, which include the sheet 100 with the contacts 102, 104 and 106, the stylet 116 and the sheathed cable 118, the signal measurement stage 120, the microprocessor 142, and the associated components, and the signal generator 122. The new component here is the four-position switch 301, which provides the ability to select which signal should be fed to the input terminal of the demodulator 144 of the measurement of signals 120, under the control of microprocessor 142 via line 302. The four potential sources of signal input are stylus 116 and any of contacts 102, 104 and 106 on sheet 100. For any position on the map of signals between two points, any change in the resistance of any contact through which current flows, will modify the value of the signal observed. For example, for a predetermined, or calculated, signal map, such as 114A between contacts 102 and 104 in Figure 4, a change in contact resistance, at contact 102 will change the absolute values in the signal map, but not the distribution or shape of the signal map. If the contact resistance at 104 had to change to a new measured contact resistance, the microprocessor could adjust the predetermined signal map s calculated to compensate for the change in contact resistance. To measure and calculate the changes in contact resistance in the three contacts 102, 104 and 106 in Figure 6, three additional measurements are made. These measurements can be added to the sequence of measurements of the SignalMPLETA / SefialoESVIADA / Signals RECTIFY-AB / Signal RECTIFYING-AC -For this discussion, the contacts will be given the designation A, B and C for contacts 102, 104 and 106. For the first additional measurement, the microprocessor selects the contact 102 to be connected to the 60 KHz AC signal via the switch 132, and the contact 104 to be connected to the inverted 60 KHz AC signal via the switch 136. The signal measuring device is connected to a fixed place, the contact 106 via the switch 301. The microprocessor then stores the signal level of the measurement stage of the signal in RAM as Signal.

The second additional measurement is made with the contact 102 connected to the AC signal of 60 KHz and the contact 106 connected to the inverted AC signal of 60 KHz. The fixed point, contact 104, is connected to the signal measuring device. The microprocessor then stores the signal level of the signal measurement stage in RAM as SignB. The third measurement is made with the contact 104 connected to the AC signal of 60 KHz and the contact 106 connected to the terminal of the inverted AC signal of 60 KHz of the amplifier 134. The fixed point, contact 102, and connected to the signal measuring device. The microprocessor then stores the level of the signal in the step of measuring signals in RAM as SignA. In this way, the measured signal levels can be defined by equations 5a-5c: Signal = Signal ™ [(X-RAB + RA) / (RA + RAB + RB)] (5a) SignalB = Signal ™ [( And "RAC + RA) / (RA + RAC + RC)] (5b) SignalA = Signal ™ [(Z-RBc + RB) / (RB + RBC + RC)] (5c) where: The Signal ™ is the signal level injected between two contacts, AB RAC and * RBC are the volumetric resistances of the material between contacts A and B, A and C, and B and C, respectively; X, Y and Z define the distribution of the volumetric resistance as observed at the measurement point, between the drive or excitation contacts; and RA, RB and Rc are contact resistances at contacts A, B and C, respectively. The Signal ™, X, Y, Z, RAB, RAC and RBC values are constant values that can be measured and / or calculated by a particular device and stored in the microprocessor's memory. This gives rise to a series of three simultaneous equations with three variables, namely, RA, RB and Re- The microprocessor can then solve those simultaneous equations for the values of RA, RB and Re, and then the microprocessor can adjust the tables of values of the signals based on new values of RA, RB and e An alternative mechanism to excite or drive a pair of contacts and detect a receiver connected to the stylet, is to use the stylus and one of the contacts as a drive mechanism and perform the detection with one of the other contacts. A measurement sequence could be made, where the other contact is selected as the actuation contact and the other contact is selected as the selection contact. An alternative excitation and measurement method is provided by the use of frequency division multiplexing. The methods discussed above include a series of separate measurement steps over time. In a frequency division multiplexing method, pairs of contact points are excited simultaneously with signals of different frequency. Therefore, the signal received by the stylus is a "composite signal of those signals of different frequency and in this way is distributed to the independent multiple signal measuring devices (ie, which are stored by frequency) each of the which measure the corresponding signal simultaneously.The multiple measurement devices in this mode are designed to measure signals within narrow frequency bands.This method of measurement offers the possibility of measuring the position in less time, however, with a detection system , more complicated excitation and measurement of signals Several designs related to the implementation of the present invention can be made to be used in a specific device.To improve resolution, a higher resolution signal generation and measurement scheme can be used. number of contact points can be increased and implemented a better algorithm that uses subsets of the contact points to solve the contacts of the stylus on the different areas of the surface. Another alternative could be the selection of a conductive material and a manufacturing method that would provide a more homogeneous surface resistivity. This increases the resolution and allows calculated signal maps, more than measures. If the material used is not homogeneous, another way of raising the resolution can be carried out by measuring a more extensive signal map that is stored in the memory of the microprocessor. The embodiments described in Figures 4, 5, 6, and 7 include a stylet that is captive of the rest of the detection system due to conductor 118. This conductor can be replaced with a communication link that does not require capturing the stylet to the system with a driver. A low-power FR (Radio Frequency) transmitter could be included or connected to the stylus and connected to a compatible FR receiver to the signal measurement means. The FR transmitter and receiver could then implement the communications link provided by the conductor 118. The present invention can be extended to include other di-or three-dimensional shapes, both with a surface shape whose slope changes uniformly (e.g. a saddle shape) and shapes with sharp edges (eg, a cube or a pyramid) as long as the resistive surface is continuous through those changes of slope and around the edges of the shape. In another embodiment, as shown in Figure 7, the position of stylet 116 on a sphere can be detected. In this embodiment a sphere 400, molded of a conductive material of the same type discussed for each of the other embodiments, has four contacts 401, 402, 403 and 404 connected thereto. To be able to individually distinguish each point on the surface of a closed three-dimensional shape (eg a sphere) the contacts must be placed so that each plane defined by each possible combination of any three of those contact points does not pass through the center of the sphere. How close these imaginary planes can be to the center of the sphere (ie, the location of the contacts) is determined by the resolution of the signal measuring device and the accuracy of the predetermined or calculated equipotential signal map that determines the point towards which the stylus is pointing. The calculation of the position is therefore substantially the same as that discussed with respect to a pair of contacts, so that this discussion and the claims also include this variation. To resolve the position of the stylet 116 on the two-dimensional area of the rectangular sheet 100 in the embodiment of Figure 4, three measurements are required, SeñalcoMPETA / Señáis ™ RECTIFYING-AB, and Señais ™ RECTIFYING-AC, since, as described previously with respect to Figure 2, the equipotential lines for each of the AB and AC measurements can be crossed only at one point. For a sphere like in Figure 7, however, four measurements are required to completely resolve the position. For example, if contact 401 is point A, contact 402 is point B, contact 403 is point C and contact '404 is point D, a measurement of the SignalMPLETA, with the four points excited simultaneously is measurement one, and three measurements must be made of the six possible pair combinations of the four contacts, namely three of the possible Measurements ™ RECTIFY-AB, and Draw ™ RECTIFY-AC, Draw ™ RECTIFY, ADDRESS RECTIFY- BC, Señáis ™ RECTIFY-BD / O SEND ™ RECTIFY-CD • Calculating the three values of the N0RM Signal as in equation (3) above and plotting those values on the applicable signal maps, all the points on the sphere will be solved in a unique way. When two values of the N0RMf Signal are plotted, the equipotential lines intersect in two places on the opposite sides of the sphere. The value of the third SignalN0RM is used to determine which of the two points of intersection is to which the stylus is being pointed. Specifically, if the signal measured at the fourth point were used with the signal from one of the other two points that were used to locate the first two alternative points, that combination could also result in two possible points on the sphere, however, one of those two points could correspond to one of the two points determined previously and is the point that corresponds to the real point of interest on the sphere. An alternative to the use of the stylet as a pointing device or indication is the use of a finger as a pointing device or indication. To enable this, a multi-layer material constructed with an inner layer similar to the conductive material discussed in the above embodiments can be used. Such a surface is illustrated in Figure 10 with the conductive layer 100 on the bottom, and a conductive layer 501 on top (for example, a metal sheet or a thin layer of a conductive polymer), and a non-conductive layer. , compressible, 502 (e.g., silicone rubber or plastic foam) between layers 100 and 501. Outer layer 501 may be metal, or some conductive material. In this configuration, the outer conductive layer 501 replaces the connected stylet 116 as in Figure 4 with the outer layer 501 connected to the signal measurement device by the conductor 118 (for example, see Figure 4). In this way, when the user touches the outer layer 501, it is compressed and the conductive outer layer 501 is closer to the inner conductive layer 502. In that situation, the level of the signal received by the outer layer 501 of the radiated signals on the inner layer 100 is increased in the same way that the level of the signal received by the stylet 116 increases when the altitude of the stylet 116 decreases in relation to the surface 100 in Figure 4. In the embodiment using the surface of the multiple layers, the position of the user's finger could be calculated in the same way as the location of the stylus with a chosen threshold value for the COD signal, in the step of determining the valid signal corresponding to the fully compressed outer layer. As mentioned briefly above with respect to Figure 4, an application of the present invention could be an interactive globe of the earth, the moon, one of the planets, one of the stars, or even an artificial body or planet for an interactive game. Two potential implementations of such a globe are illustrated in Figures 11 and 12. The main differences between the modalities of those figures is that in Figure 11 the conductive surface is a sphere, and in Figure 12 the conductive surface is implemented with two hemispheres . Figure 11 illustrates the system described above with respect to Figure 7 being modified to be a terrestrial globe. Thus, the electronic devices in the lower portion of Figure 11 have the same reference numbers as, and operate in the same manner as described, in Figure 7. In Figure 11 there is a conductive sphere 603 with four contact points 604, 605, 606 and 607 on the inner side of the sphere 603, with each of the contact points connected, respectively, to one of the four insulated conductors of the cable 608 at one end of those conductors. The cable 608 leaves the sphere 603 through a small hole in the bottom of the sphere 603, with the other end of the cable conductors 608 interconnecting with the corresponding sections of the switches 422 and 432. To provide the geographical details of the balloon, two vinyl liners 601 and 602, shown here representing the hemispheres, were placed on the sphere 603. north and south of the earth. In this way when a user uses the stylus 116 to point or point to a location on the globe, the electronic devices determine the coordinates of the selected location as described above in the discussion with respect to Figure 7, since the electronic devices here they are as described there. The only location on the surface of the globe is thus defined by the equipotential coordinates, which can then be traced by the microprocessor 142 (for example, by means of a look-up table) within the coordinates of the globe (for example, longitude and latitude) that corresponds to the selected position on the globe.

A database containing the characteristics of interest in the world, such as locations and names of countries, capitals and populations can be pre-stored in RAM 144 in relation to any coordinate system desired. In this way, when a user selects a point on the globe with the stylus 116, the microprocessor 142 determines the coordinates of that position and allows the retrieval of the information in relation to that position of the database to present them to the user via, for example, the audio / video card 150 and the horn 154. An alternative implementation of the globe is illustrated in Figure 12, wherein the conductive hemispheres 701 and 702, which are electrically isolated from each other, provide the conductive surfaces for the balloon. Here, the hemispheres 701 and 702 are joined with their edges very close to each other with continuous non-conducting spacers, or several rigid spacers (for example, three) fixed to the edges of each of the hemispheres 701 and 702 to maintain the ratio of separation and electrical insulation. Alternatively a non-conductive adhesive may be used between the edges of the hemispheres 701 and 702. Vinyl coatings 601 and 602 are then mounted with the geographic information on the two hemispheres as discussed above with respect to Figure 11.

In this mode each hemisphere has three fixed contact points on each inner edge, with the hemisphere 701 having the contact points 710, 711 and 712, and the hemisphere 702 having the contact points 740, 741 and 742. Here, each hemisphere it is shown with a small hole through the polar cap to allow three insulated conductor wires 730 and 750 to pass through and have one end of each insulated conductor connected to the three points on the inner edge of the corresponding hemisphere. The other end of each of the cables 730 and 750 is, in turn, connected to a separate pair of switches in the signal generator 722. The upper hemisphere 701 has the cable 730 connected to the switches 770 and 771, while the lower hemisphere 702 has cable 750 connected to switches 772 and 773. Comparing Figure 12 with Figure 4, it can be seen that while the embodiment of Figure 4 is for a single surface and Figure 12 is for a pair of surfaces, the only change in the wiring between the signal generator of each mode is the addition of a second pair of switches for the second surface for the mode of Figure 12. The rest of the signal generator in each case is the same, with the amplifier 134 connected to both pairs of switches 770 and 771, and 772 and 773. This is possible because there is only one stylus 116 and only one point on the globe can be selected at a time (ie, the pun selected can only be found on one hemisphere at a time). In this way, each hemisphere is treated as an independent location sensing surface. To make the determination of which of the hemispheres 701 and 702 the user has pointed the stylus 116, the microprocessor 142 is programmed to make a series of measurements. First, as in many of the modalities discussed above, with the stylus 116 pointing to the selected point on one of the hemispheres, the HALF signal and the SADDEF signal are measured for each hemisphere independently, and the difference between those measured values is determined for each hemisphere (ie, SignalMPLET- or? signalSTEVI? D-701 / and SignalMPLETE-7o2 / signalSAVED-702 and stored in BRANCH 144. In summary, the SignalMPLETA is measured by applying the AC signal of 60 KHz to all the contact points on the surface, and the SDS signal will be measured at all the contacts of the corresponding switches in the signal generator 722 for that open surface, once those values of the difference have been determined, each of these values of the difference is compared with a preselected threshold value. The threshold value is determined empirically and typically are the measured values when the tip of the stylus is about 0.254 cm (0.10 inches) from the surface. It is then noted which, if any, of those values of the difference exceeds the threshold and if it is within the greater range of the corresponding seraisphere that is being identified as that to which the stylus 116 is being pointed. Once the hemisphere of interest has been determined, the microprocessor 142 calculates the position selected by the sequence of calculations explained above with respect to Figure 4. In this way, four measurements are made, SignalMPET, DESTROYED signal, LADIES ™ RECTIFY-AB , and Señals ™ RECTIFY-AC on the hemisphere and calculate the values of the NRM-AB and the NRM-Ac signals as in equation 4 with those values that define a unique location on this hemisphere. The unique location provided by the NOR-AB Signal and the. Signal N0RM-Ac, together with the results of the threshold test to determine which hemisphere is of interest to the user, can then be plotted on a location on the globe by means of a look-up table for the selected hemisphere, if necessary, to obtain the longitude and latitude of the selected point, in a standard spherical coordinate system. Next, as discussed with respect to Figure 11, the microprocessor 142 can present the user with information related to the memory via the audio / video card 150 and the horn 154, or by any other desired means (e.g., a printer, monitor, etc.) or combinations of media. In addition to the user acting as an antenna and capturing atmospheric noise and signals as described in the background of the invention above, there is another side effect that can potentially occur if the user is not grounded with respect to the system of the present invention. Since in the present invention the surface toward which the probe points the user, in the AC mode, is radiating a different signal at different coordinates of the surface, a portion of the user's hand, perhaps a finger or thumb, While holding the probe in the desired location, it can pick up a different signal from another location away from the place of interest. In such a situation, the antenna of the probe can potentially be influenced by that second signal capacitively coupled from the surface to the user and then coupled to the antenna of the probe. That secondary signal could result in a modified signal that is being received by the measurement step of the signal 120. That modified signal of the surface could then be processed to identify a location different from the actual location to which the user has pointed the tip of the probe.

For example, assume that the user has pointed the tip of the probe to Chicago on the surface of a balloon of the present invention. By keeping the tip of the probe in place, the user's thumb can extend east and be close to Detroit, while several of the user's fingers extend west of Chicago toward Quincy, Illinois, over the Mississippi River. What could actually happen is that a mixture of signals could be received from the location to which the probe is pointed, along with a signal from each finger and thumb of the user by the measurement step of signal 120 as a resulting average signal in the identification of the selected point as a place between Detroit and Quincy, or even any other place on the surface that is not close to the place selected by the user, perhaps Tokyo. Even worse, the signal received by the antenna of the probe can be too complex as a result of all the signals coupled thereto that the signal measurement stage is unable to identify any place corresponding to the combined signal. By including the mechanism for grounding the user with respect to the system, as discussed below, this potential problem, as well as any influence created by atmospheric noise as discussed in the Background of the Invention will be solved by virtually eliminating the other signals coupled to the antenna of the user's probe.

In each of the embodiments wherein a radiated AC signal is detected by the stylet 116 acting as an antenna (see Figures 4, 5, 6, 7, 11 and 12), the stylet 116 is coupled to the demodulator 144 with a sheathed cable 118. The sheathed cable 118 has been included in an effort to prevent the length of the cable 118 from acting as an antenna, in addition to the stylet 116, and to pick up signals at some distance from, and not emanating from, the surface of interest corresponding (ie, 100, 400, 603, 701 or 702). In prior art situations requiring an antenna at a distal end of a cable to be used as an indicator in the system to locate the point at which the stylus is pointing, the internal circuit configuration of that stylet is very complex. Figure 13 is a schematic representation of such stylet 916 used with the toy storybook SEGA PICO. Note that, even in an industry, the toy industry in this example, where it is imperative to keep costs low so as not to put a price on a product outside the scope of the intended market, a relatively complex circuit has been used. The only favorable saving, in prudent spending, is that the product was probably assembled through low-paid work in a third-world country.

There are several differences that can be observed between this design of the stylet 916 and the stylet 116 of the present invention. First, and above all, is the design of the active circuit of the prior art that includes two transistors, and specifically the design of Cl (integrated circuit), numerous capacitors, inductors and resistors, a power switch and a potentiometer that requires a mounting extensive, as opposed to the passive circuit design of the present invention. In addition to the design of the active circuit, there is a need for a metal frame formed at 920 at the end of the antenna of the stylus 916 to exclude spurious responses that interfere with the signal received from the antenna. There is also an Intensive working step to calibrate the stylus 916 to the system with which it will be used by means of potentiometer 922. Another added cost to the product is the use of a four-wire cable 918, which is necessary to perform various functions : a lining; a line to transport the received signal back to the main product frame; and two wires to bring power to the stylus 920. Finally, there is a power switch 912 that needs to be depressed during use to feed the stylet 916, which may present a problem if the user is intended to be a child, such as the child. case with the SEGA product.

Figure 14a illustrates one embodiment of the combination of the stylet 11 and a sheathed cable 118. In this view, the distal end of the stylet 116 is shown in a dotted outline to illustrate the end of the cable 118 inside the distal end of the stylet 116. In this embodiment, the sheathed cable 118 continues to close to the far distal end of the stylet 116 with the liner intact and then a selected length of the center conductor 802r is exposed to act as the antenna. At the proximal end of the sheathed cable 118, the liner 800 is connected to ground in the measurement step of the signal 120, and the center conductor 802 is connected to the demodulator 144 to provide the input signal thereto. Thus, in this embodiment, a signal that collides along the length of the sheathed cable 118 will not conute to the signal detected by the length of the antenna of the center conductor 802 '. However, if the person holding the stylet 116 also inadvertently acts as an antenna and radiates some of the received signal to the center conductor 802, that signal is added to the desired signal of the surface of interest (eg, the surface 100). ). Then, depending on many factors, including the ability of the demodulator 144 to reject undesirable signal frequencies and noise, the position of the stylet 116 that is ultimately determined by the location system of the present invention may not be as secure as desired. A first embodiment of this aspect of the present invention is illustrated in Figure 14b. In this view, the connections at the proximal end of the sheathed cable 118 are the same as in Figure 14a. At the distal end of the stylet 116, there are some changes that have been made to effect the ground connection of the user when holding the stylus 116 to eliminate the parallel antenna effect inadvertently created by the user holding the stylus 116 near the driver / central antenna 802 '. Here, it can be seen that the distal end of the sheathed cable 118, in addition to having the center conductor 802 exposed, has a portion of the liner 800 'exposed. In addition, the stylet 116 defines a hole 804 therethrough, so that when a user grasps the stylet 116, a portion of one of the user's fingers should extend through the hole 804 and make contact with the liner 800 ', connecting ground the user in this way. A second embodiment of this aspect of the present invention is illustrated in Figures 14c and 14d, with Figure 14d showing a sectional view of the distal end of the stylet 116 to illustrate the internal configuration of this embodiment. In those views, the connections at the proximal end of the sheathed cable 118 are the same as in Figures 14a and 14b. In Figure 14c, the stylet 116 includes three portions: the tip 810; the main body 812; and the conductor fastener 806 extending around the stylet 116 at the user's fastening point. In Figure 14d a portion of the tip 810 and the conductive fastener 806 have been cut to illustrate the internal structure of the distal end of the stylet 116. The internal arrangement is similar to that of Figure 14b, with the exception of the length of the 800 liner. which has been exposed and directed from a spiral connection 808 of the liner 800 'back under the conductor holder 806. In this way, when the user holds the stylet 116 with the conductor holder 806, the user is grounded by the elecal interaction of the conductor fastener 806 and the lining 80Q 'and the connection is spiral 808. Various structures and materials could be used to vary the conductor holder 806 from spring-loaded metal rings to conductive polymers. One such conductive polymer could be a Kraton D-2104 polymer impregnated with carbon (e.g., RTP 2799X66439). Additionally, it is well known to those skilled in the art how point-related data could be stored on any surface that could be employed with the present invention., as would be the query tables to convert a coordinate system for one surface to another coordinate system. Although the discussion of the different embodiments of the present invention presented above deals with a variety of forms and applications for the present invention, the forms and applications discussed do not, of course, constitute an exhaustive list. Such a list could easily be extended to many other forms and applications and the techniques discussed above could easily be extended to each of them. Thus, the present invention is not limited solely to the aspects discussed above, but is limited only by the scope of the claims appended hereto.

Claims (16)

CHAPTER CLAIMEDICATORÍO Having described the invention, it is considered as a novelty and, therefore, the content is claimed in the following: RESIGNATIONS

1. An electrographic detection unit for use in determining the position of a selected point, which is characterized in that it comprises: a layer of a conductive material having an electrical resistivity and a surface; K separate contact points, electrically interconnected with the layer of conductive material; a processor connected to the K separate and controlled contacts to selectively apply a signal to N of the K contact points in relation to a neutral point of the signal, and where N has an integer value of 3 to K; and a probe assembly, including: a cable having a first conductor and a second conductor with the proximal end of a conductor coupled to the processor and the proximal end of the second conductor connected to the neutral point of the signal; and a stylet coupled to the cable, and incorporating therein the distal ends of the first and second conductors with the distal end of the first conductor positioned to receive signals from the layer when the contact points have signals selectively applied to them and the user places the stylet in the vicinity of a point selected by the user on the surface, and with the distal end of the second conductor positioned to make contact with the user when holding the stylus to connect the user to the neutral point of the signal; wherein the position of the stylet in relation to the surface of the layer is determinable by the processor from the signals received from the first stylus conductor each in relation to a similar excitation of J different pairs of the K contact points under the processor control, where J is an integer between 2 and (Nl).

2. The electrographic detection unit according to claim 1, characterized in that: the processor selectively applies signals of CA to one of the K separate contact points selected; the distal end of the first conductor detects the signals radiated from the layer of conductive material as an antenna without making physical contact with the layer; and the distal end of the second conductor when in contact with the user, connects the user to the neutral point of the signal to minimize any noise radiated by the user being received by such distal end of the first conductor and this being delivered to the processor .

3. The electrographic detection unit according to claim 1, characterized in that the stylus further includes an electrically conductive contact, which makes electrical contact with the distal end of the second conductor, and located externally and placed to make contact with the user during the use of such a stylet.

4. The electrographic detection unit according to claim 3, characterized in that the electrically conductive contact is a flexible conductive polymer that surrounds the stylet in a position to maximize user comfort when holding the stylet.

5. An electrographic detection unit for use in determining the position of a selected point, characterized in that it comprises: a layer of a conductive material having an electrical resistivity and a surface; three separate contact points, electrically interconnected with the layer of conductive material; a processor connected to the three separate contacts and placed to selectively apply a signal to each of the three contact points in relation to a neutral point of the signal; and a probe assembly, including: a cable having a first conductor and a second conductor with the proximal end of a conductor coupled to the processor and the proximal end of the second conductor connected to the neutral point of the signal; and a stylet attached to the cable, and incorporating therein the distal ends of the first and second conductors with the distal end of the first conductor positioned to receive signals from the layer when the contact points have signals selectively applied to them and the user places the stylet in the vicinity of a point selected by the user on the surface, and with the distal end of the second conductor placed to make contact with the user when holding the stylus to connect the user to the neutral point of the signal; wherein the position of the stylet in relation to the surface of the layer is determinable by the processor from the signals received from the first stylus conductor, each in relation to a similar excitation of two different pairs of the three low contact points the control of the processor.

6. The electrographic detection unit according to claim 5, characterized in that: the processor selectively applies AC signals to one of the three separate contact points selected; the distal end of the first conductor detects the signals radiated from the layer of conductive material as an antenna without making physical contact with the layer; and the distal end of the second conductor when in contact with the user, connects the user with the neutral point of the signal to minimize any noise radiated by the user that is being received by the distal end of the first conductor and is being delivered to the processor.

The electrographic detection unit according to claim 5, characterized in that the stylus further includes an electrically conductive contact, which makes electrical contact with the distal end of the second conductor, and is located externally and is positioned to make contact with the user. during the use of the stylet.

8. The electrographic detection unit according to claim 7, characterized in that the electrically conductive contact is a flexible conductive polymer that surrounds the stylet in a position to maximize user comfort when holding the stylet.

9. An electrographic detection unit in the form of a balloon for use in determining the position of a point selected by the user on the surface thereof, characterized in that it comprises: a sphere formed of a layer of a conductive material having a resistivity substantially uniform electrical and an external surface; a set of four separate contact points, electrically interconnected with the layer of conductive material of the sphere; a processor connected to the set of four separate contacts and placed to selectively apply a signal to each of the four contact points in relation to a neutral point of the signal; and a probe assembly, including: a cable having a first conductor and a second conductor with the proximal end of a conductor coupled to the processor and the proximal end of the second conductor connected to the neutral point of the signal; and a stylet coupled to the cable, and incorporating therein the distal ends of the first and second conductors with the distal end of the first conductor positioned to receive signals from the layer when the contact points have signals selectively applied to them and the user places the stylet in the vicinity of a point selected by the user on the sphere, and with the distal end of the second conductor positioned to contact the user when holding the stylus to connect the user to the neutral point of the signal; wherein the position of the stylus in relation to the surface of the sphere is determinable from the three signals received from the stylus by the processor, each in relation to a similar excitation of three different pairs of the four contacts on the sphere by the processor.

10. The electrographic detection unit according to claim 9, characterized in that: the processor selectively applies AC signals to the four selected separate contact points; the distal end of the first conductor detects the signals radiated from the layer of conductive material as an antenna without making physical contact with the layer of the sphere; and the distal end of the second conductor when in contact with the user, connects the user with the neutral point of the signal to minimize any noise radiated by the user that is being received by the distal end of the first conductor and is being delivered to the processor,

11. The electrographic detection unit according to claim 9, characterized in that the stylus further includes an electrically conductive contact, which makes electrical contact with the distal end of the second conductor., and is located externally and is positioned to make contact with the user during the use of the stylet.

12. The electrographic detection unit according to claim 11, characterized in that the electrically conductive contact is a flexible conductive polymer that surrounds the stylet in a position to maximize user comfort when the user holds the stylet.

13. An electrographic detection unit for use in determining the position of a selected point, characterized in that it comprises: a first layer of a conductive material having an electrical resistivity and a first surface; a first set of three separate contact points, ip electrically connected to the first layer of conductive material; a second layer of a conductive material having an electrical resistivity and a second surface; a second set of three separate contact points, electrically interconnected with the second layer of conductive material; a processor connected to each of the first or second sets of three separate contacts and placed to selectively apply a signal to each of the three contact points in each of the first and second sets thereof; and a probe assembly, including: a cable having a first conductor and a second conductor with the proximal end of a conductor coupled to the processor and the proximal end of the second conductor connected to the neutral point of the signal; and a stylet coupled to the cable, and incorporating therein the distal ends of the first and second conductors with the distal end of the first conductor positioned to receive signals from the layer with the point selected by the user with the corresponding set of contact points. they have selectively applied signals to them and the user places the stylet in the vicinity of a point selected by the user on one of the first and second surfaces and with the distal end of the second conductor placed to make contact with the user when holding the stylet to connect the user with the neutral point of the signal; wherein the identification of which of the first and second surfaces of the stylet is adjacent is effected by the processor by means of the dependent measurement of two signals of each of the first and second layers received by the stylet, combining the signals of the same layer independently of the signals received from the other layer to form a first and second comparative values with each comparative value associated with one of the first and second different layers, and independently comparing each of the first and second comparative values with a preselected threshold value with the layer associated with one of the first and second comparison values that is larger and that is greater than the threshold of the stiletto layer close to, and therefore an identified layer of the first and second layers; and wherein the position of the stylet in relation to the first or second identified layers is determinable by the processor from the signals received from the stylet, each in relation to a similar excitation of the three contact points on one of the first and second. second identified layers and two different pairs of the three contact points on one of the first and second layers identified under the control of the processor.

The electrographic detection unit according to claim 13, characterized in that: the processor selectively applies AC signals to the four selected separate contact points; the distal end of the first conductor detects the signals radiated from the layer of conductive material as an antenna without making physical contact with the layer of the sphere; and the distal end of the second conductor when in contact with the user, connects the user to the neutral point of the signal to minimize any noise radiated by the user that is being received by the distal end of the first conductor and is being delivered to the user. processor.

15. The electrographic detection unit according to claim 13, characterized in that the stylus further includes an electrically conductive contact, which makes electrical contact with the distal end of the second conductor, and is located externally and is positioned to make contact with the user. during the use of the stylet.

16. The electrographic detection unit according to claim 15, characterized in that the electrically conductive contact is a flexible conductive polymer that surrounds the stylet in a position to maximize user comfort when the user holds the stylet.