Abstract: A keypad in which output keystrokes are determined both from individual switch activation and from the combined activation of adjacent switches. The keypad has a substrate carrying an array of sense elements arranged to change state in response to keypad operation, a flexible cover disposed above the substrate and having an exposed surface defining an array of independent key regions, with combination key regions defined in interstices between adjacent independent key regions. Snap elements provide tactile feedback. Some versions have a touch-sensitive grid rather than a switch matrix.

Abstract: An appliance control panel detects on ON gesture by a user approximately near a set of electrodes in a surface of the appliance, in which the electrodes sense a capacitive coupling to the user. The appliance is turned on in ON in response to the detecting of the ON gesture by the user. A capacitive coupling substantially near a particular one of the set of electrodes by the user is detected to perform a control action.

Abstract: A touch sensor includes a Printed Circuit Board (PCB) that is transparent with respect to light in a visible wavelength band, an upper clad and a lower clad formed on the top face and the bottom face of the PCB, a light source for emitting light to a side of the PCB, and a key top layer disposed on the upper clad.

Abstract: A circuit configuration for a capacitive touch switch contains at least one sensor circuit with a capacitive sensor element which changes its capacitance value when touched, and an evaluation circuit which is supplied with an output signal from the sensor circuit in order to determine whether the capacitive sensor element is actuated or not. The at least one sensor circuit has a capacitance which is connected in parallel with the capacitive sensor element, and a capacitance/frequency converter which is connected to the parallel circuit containing the capacitance and the capacitive sensor element and generates, at its output, a frequency signal whose frequency depends on the total capacitance of the parallel circuit containing the capacitance and the capacitive sensor element. The evaluation circuit may thus use a significant change in the frequency of the output signal from the sensor circuit to deduce, in a simple manner, that the capacitive sensor element has been touched.

Abstract: An apparatus and method for converting a capacitance measured on a sensor element to a digital code. The apparatus may include a switching capacitor as a sensor element of a sensing device, and a sigma-delta modulator coupled to the sensor element to convert a capacitance measured on the sensor element to a digital code. The switching capacitor is in a feedback loop of the sigma-delta modulator. The method may include measuring a capacitance on a sensor element of a sensing device using a sigma-delta modulator, and converting the capacitance measured on the sensor element to a digital code.

Abstract: A input device is provided which includes a clock signal generator that generates a clock signal; a delay unit that has a capacitive sensor where an electrode is formed on a substrate; protective sheets each of which is formed of a dielectric and which are disposed on front and rear surfaces of the capacitive sensor; a logical product unit that transmits an output signal on the basis of a clock signal obtained from the clock signal generator and a delay signal obtained from the delay unit; and a controller that makes a predetermined program executed in accordance with an output signal obtained on the basis of the logical product unit.

Abstract: A keypad assembly for use on a vehicular keyless entry system comprises a selectively concealable keypad coupled to a processor and accessible from the exterior of the vehicle and through which an access code may be manually entered. A mirror assembly is mounted on an exterior surface of the vehicle and includes a base fixedly coupled to the exterior surface and a mirror compartment rotatably coupled to the base and capable of being rotated between an extended, operational position and a folded, retracted position. The keypad is mounted on the base so as to be visible and accessible when the mirror compartment is in its folded retracted position and hidden and inaccessible when the mirror compartment is in it's extended, operational position.

Abstract: A repeated pattern of sensing elements can be used to indicate an unambiguous position along an axis in a sensing region. For example, different-sized sensing elements can be arranged in a repeating pattern, and the relative measures of their respective output signals can be used to identify a position in the sensing region.

Abstract: An input device includes a plurality of input keys arranged in a matrix of three or more rows and three or more columns; electrodes facing parts of or all surfaces of the input keys that surround intersection of rows and columns formed by the arrangement of the input keys; and an input key detecting unit that identifies operated input keys among the plurality of input keys by combinations of the electrodes having a change in electrostatic capacitance. With this structure, the number of electrodes can be less than that of the input keys.

Abstract: Control panel of the touch-switch comprising: an external control board with transparent surface portions, devices for illuminating the transparent surface portions from the inside, capacitive-type detecting or sensing devices on the backside of the control board and adapted to detect the presence, on the front side of the control board. The devices for illuminating comprise a plurality of illumination channels comprised laterally between pairs of opaque septum-like partitions arranged in parallel manner on the backside of the control board. The capacitive-type detecting devices comprise conductive elements applied either on the mutually facing surfaces of contiguous septum-like partitions or on one of the surfaces and a ground not comprised between the septum-like partitions. The illuminating channels are delimited on the front side by the external control board at the transparent surface portions and, on the back side, by support members arranged at the rear side of the septum-like partitions.

Abstract: The gesture-based input device for a user interface of a computer comprises two pairs of electrodes scalable for any screen size wherein the electrodes are arranged to capture the quasi-electrostatic field surrounding the user in order for the graphic user interface to provide different options or tasks to be selected by a user, a platform for supporting a user, a quasi-electrostatic field generator source connected to the platform and a circuitry connected to the electrodes for determining, relative to each of the electrodes, the position of that part of a user supported by the platform, e.g. a user's hand, being closest to the electrodes.

Abstract: An apparatus and method for selecting a keyboard key based on a position of a presence of a conductive object on a sensing device and a pre-defined area of the keyboard key. The apparatus may include a sensing device and a processing device. The sensing device may include a plurality of sensor elements to detect a presence of a conductive object on the sensing device. Multiple keyboard keys are assigned to pre-defined areas of the sensing device. The processing device is coupled to the sensing device using capacitance sensing pins, and may be operable to determine a position of the presence of the conductive object, and to select a keyboard key based on the position of the conductive object and the pre-defined areas of the sensing device.

Abstract: Disclosed herein are a home appliance network system and a method for operating the same. The home appliance network system comprises a plurality of home appliances connected to a network constructed in a home for transmitting and receiving data over the network, and a home server including a device monitoring module for independently storing and updating state information or product information of a specific one of the home appliances based on an input control command. When a user monitors product information of the home appliances to control the home appliances, the home server more rapidly displays the product information, resulting in an improvement in control speed. Further, the home server uses a smaller amount of network system resources, thereby enabling efficient networking to be made.

Abstract: A touch sensors with improved topological equivalence between an equipotential space and a Cartesian space to which the equipotential space will be mapped. The touch sensor comprises a substrate with a touch region, and a set of electrodes that are electrically coupled to the touch region. The touch sensor further comprises a plurality of resistive band segments that frames the touch region. The electrodes are located between the resistive band segments. Each resistive band segment has a resistivity that is intermediate between the resistivity of the electrodes and the resistivity of the touch region, thereby providing a transition between the low resistivity electrodes and the high resistivity touch region, and improving the topological equivalence within the corners of the touch region. At least one of the band segments has a non-uniform linear resistance to provide further improvement to the topological equivalence.

Abstract: When an array of proximity sensors is used as a keyboard, it can provide an ambiguous output if a user's finger overlaps several keys or if liquid is spilled on the keyboard. This ambiguity is reduced by an iterative method that repeatedly measures a detected signal strength associated with each key, compares all the measured signal strengths to find a maximum, determines that the key having the maximum signal strength is the unique user-selected key and then suppresses or ignores signals from all other keys as long as the signal from the selected key remains above some nominal threshold value.

Abstract: A variable capacitance unit is formed between one portion of a human body and an opposed electrode facing it through a casing of a robot toy (electronic device) when the one portion of the human body such as a hand or a finger approaches the surface of the casing of the robot. Since the capacitance of the variable capacitance unit varies according to the facing area and the facing distance of the one portion of the human body and the opposed electrode, it is possible to detect the one portion of the human body approaching or touching the robot toy by detecting this change. Since the opposed electrode forming the touch sensor can be provided within the casing, the touch sensor cannot be seen directly from the outside of the robot toy.

Abstract: An apparatus and a method of driving a touch panel that increases an analog-digital converting range includes a first resistive layer having first and second electrodes formed facing each other along opposing edges of the first resistive layer in a first direction, and a second resistive layer having third and fourth electrodes formed facing each other along opposing edges of the second resistive layer in a second direction. The apparatus also includes a high potential controller for selectively connecting one of the first and third electrodes to a high potential voltage supplied from a high potential voltage source and a low potential controller for selectively connecting one of the second and fourth electrodes to a low potential voltage. Further, a variable resistor is employed for reducing a voltage of the high potential voltage between the high potential controller and the high potential power voltage source.

Abstract: A system and method for allocation of actuators is provided. Electrodes having several voltages are assigned to actuators within correlation regions of the actuators. By varying the voltages, a desired actuation profile for the actuators may be achieved.

Abstract: A cooking stove in which an operation circuit board formed with an electrode pattern is placed on a back surface of a glass top plate so as to suppress the formation of an air layer. The cooking stove includes a display mark and a switch mark provided on a front surface of the glass top plate so as to have a first positional relationship, a case having a display opening corresponding to the display mark with the first positional relationship and an operation circuit board opening corresponding to the switch mark, the case being bonded to the uneven back surface of the glass top plate so that the display opening is positioned at the display mark, and a bonding layer that bonds the back surface of the glass top plate to a part of the operation circuit board in which an electrode pattern is formed, via the operation circuit board opening in the case so that depressed portions of the back surface of the glass top plate are filled with a double coated tape having a foam as a base material.

Abstract: A touch sensing apparatus includes a signal source for generating an alternating current signal, a conductor connected to the signal source, a sensor for receiving a noise generated by a contact of an object. The sensor together with the conductor form a simulated capacitor that results in alternating current signal flowing through the sensor when the sensor is contacted by the object. A detector has a first input end and a second input end. The detector results in voltage differences between the first and second input ends thereof when receiving the alternating current signal output from the sensor, and thus output a signal. A rectifying circuit is used for rectifying the alternating current signal generated by the signal source and simultaneously generating a noise. One end of the rectifier circuit is connected to the signal source and other end of the rectifier circuit is connected to the negative power input end of the detector.

Abstract: An object detection sensor wherein a detection electrode (electrode connected with a detection circuit via a conductor) is not exposed from a surface and an input signal is scarcely reduced when a contact area is small, which is capable of reliably detecting a contact thereof with an object in a manner substantially the same as that in the case of a large contact area even when the contact area is small is provided.

Abstract: A method, system, apparatus, and program product for moving a pointer on a display screen. A ring capable of being worn by a user contains a sensor unit having multiple sensors. When the user activates one of the sensors, the pointer on the display screen moves in a corresponding direction.

Abstract: The method for automatic determination of validity or invalidity of input from miniaturized keypads or keyboards, in which more than one key is operated at the same time, includes designating a number of keys as principal keys and assigning each key neighboring each principal key as nearest neighbor or next nearest neighbor and then testing each signal produced by key operation. The signal is valid if it is produced by operation of only one single key. However testing continues if two or more keys produce the signal. Then the signal is valid when the two or more keys are correlated in an unambiguous principal key-nearest neighbor key relationship. If not, testing continues further and the signal is valid if the plural keys are correlated in an unambiguous principal key-nearest neighbor key-next nearest neighbor key relationship. Otherwise the signal is an invalid key input.

Abstract: A capacitive touch switch system for use in an audio application includes a detecting circuit with a capacitive sensing device and a filtering circuit. The capacitive sensing device senses changes in capacitance. The filtering circuit filters external and/or internal interference that may affect the sensing of a capacitance change and/or the sound quality of an audio device. The capacitive touch switch system may be incorporated into a speaker and/or other components of the audio device. The capacitive touch switch system may control various audio parameters such as volume, bass, treble, balance, channel, and the like.

Abstract: A flexible touch-sense switch includes a force sensitive composite and an at least one proximity sensor. The force sensitive composite includes a plurality of force sensors disposed between a first layer and a second layer of polymide film defining a displacement region. The at least one proximity sensor generates an electromagnetic field that defines a detection region. The force sensitive composite and the at least one proximity sensor are mounted to the first layer of the polymide film for forming a flexible printed circuit board. A control circuit is electrically connected to the force sensitive composite and the at least one proximity sensor for selectively controlling the touch-sense switch activation in response to coincident actuation thereof.

Abstract: A duplex-system digital-data transmitting apparatus includes a digital-data signal source which outputs serial data at a signal output end. The level of the data is converted by a first level converter circuit. The data is supplied to an FSK modulator circuit to be FSK-modulated. Carriers are, for example, at 11 MHz and 13 MHz and correspond to digital signals “1” and “0”, respectively. The modulated signal is amplified by a driver and is coupled to the human body by a capacitor of about 100 pF. When the human body comes into contact with an electrode, the modulated signal transmitted through the human body is amplified by a pre-amplifier, demodulated by a demodulator circuit, and shaped by a comparator. The level of the shaped signal is converted by a second level converter circuit, and the signal is supplied to a serial input end of a receiving unit. Transmission and reception are performed using a half-duplex system.

Abstract: A wastewater fluid level sensing and control system is provided. The system comprises a control panel, a reservoir, at least one pump and a fluid level sensing device. The control panel comprises a housing and user interface input and output devices for use with configuring the operation of the control panel. The control panel may be configured to turn on one or more of the pumps to lower the level of fluid in the reservoir. When the level is above a selectable level, the control panel is operative to cause at least one alarm signal to be output. The control panel may include a touch sensor pad mounted to an inner wall of the housing. Changes in capacitance in the pad as a result of a hand being placed adjacent the sensor on the outside of the housing is operative to cause the control panel to silence the alarm.

Abstract: A touch sensor system and a method of operating the system is provided to detect the touch of a person. An AC power source is provided with an isolated power supply connected to thereto with a DC voltage source output. The DC voltage source is referenced to ground. An impedance limiting circuit is connected to the output of the DC voltage source. An analog-to-digital converter is connected to the impedance limiting circuit. A processor is connected to the analog-to-digital converter with the touch sensor connected to the impedance limiting circuit. The touch sensor is capacitively coupled to the AC power source. The waveform output of touch sensor is monitored and with the waveform output as an OFF reference waveform when the touch sensor is not being touched and the waveform output is stable being calculated and saved.

Abstract: A touch switch apparatus for detecting the presence of an object such as a human appendage, the apparatus having a touch pad and a local control circuit connected to the touch pad and to a controlled device. The touch pad preferable includes a first electrode and a second electrode spaced from and surrounding the first electrode. The control circuit is preferably in integrated circuit form. A signal is provided to the touch pad to generate an electric field thereabout. Introduction of a stimulus near the touch pad disturbs the electric field. The control circuit detects the electric field disturbance in and generates a control signal in response.

Abstract: An input device, which is small-sized and inexpensive in spite of being simple in construction and thin, comprises at least one primary electrode and a plurality of secondary electrodes, both electrodes being formed in the same plane. A position of a dielectric is identified on the basis of differences in electrostatic capacity between the primary electrode and the secondary electrodes, which electrostatic capacity is changed by the dielectric positioned on a surface side of the both electrodes.

Abstract: Capacitive proximity sensing is carried out by detecting a relative change in the capacitance of a “scoop” capacitor formed by a conductor and a surrounding ground plane. The conductor may be a plate provided in the form of an adhesive label printed with conductive ink. Charge is transferred between the “scoop” capacitor and a relatively large “bucket” capacitor, and a voltage of the bucket capacitor is applied to an input threshold switch. A state transition (e.g., from low to high, or high to low) of the input threshold switch is detected and a value (TouchVal) indicative of a number of cycles of charge transfer required to reach the state transition is determined. The presence or absence of an object or body portion in close proximity to or contact with a device can be determined by comparing TouchVal with a predetermined threshold value (TouchOff). TouchOff can be adjusted to take into account environmentally induced (non-touch related) changes in the capacitance of the scoop capacitor.

Abstract: When an array of proximity sensors is used as a keyboard, it can provide an ambiguous output if a user's finger overlaps several keys or if liquid is spilled on the keyboard. This ambiguity is reduced by an iterative method that repeatedly measures a detected signal strength associated with each key, compares all the measured signal strengths to find a maximum, determines that the key having the maximum signal strength is the unique user-selected key and then suppresses or ignores signals from all other keys as long as the signal from the selected key remains above some nominal threshold value.

Abstract: A contact switching arrangement with a flat electrically non-conducting cover which forms a switching area on a top facing the user, and has an underside facing away from the user, at which at least one electrode is arranged and is connected with a switching arrangement for triggering a contact signal when a finger of the user or a similar conducting body approaches. The cover has a light-reflecting, electrically non-conducting film, at least over portions, which acts as a non-conductor. The contact switching arrangement is for use in connection with control panels of electronic devices, for example.

Abstract: A circuit assembly for providing a switch sensor and a capacitive sensor. The circuit assembly has a first pattern of conductive material in a first plane and a second pattern of conductive material in a second plane. An insulating member in an intermediate plane separates the first and second patterns. In a switch sensor area, the insulating member has openings to allow a first conductive element in the first pattern to contact a second conductive element in the second pattern responsive a force being applied to the first conductive element. In the capacitive sensor area, the insulating member maintains spacing between conductive material in the first and second patterns. The circuit assembly also includes a preventative capacitance configuration that limits non-intentional capacitive coupling in the capacitive sensor area.

Abstract: A keypad system (FIG. 2) and corresponding method (FIGS. 3-4) suitable for use in a subscriber device (1) includes a capacitive touchpad 22 for detecting movement within a region, a driver device 12 coupled to the capacitive touchpad, wherein the driver device is for generating a touchpad data signal corresponding to the movement detected by the touchpad; and a controller 14 coupled to the driver device for receiving the touchpad data signal and for resolving the signal to one of a plurality of characters corresponding to the region. A keypad device 16 may be used for generating a key selection signal indicative of the region.

Abstract: A keyboard allowing typists to use approximate QWERTY finger movements on a more compact, collapsible, and portable keyboard. The keyboard size is made more compact by using thin capacitance-responsive surfaces as key switches for the rows above and below the home row. The bottom, space-bar row is also touch-sensitive and is placed on the side of the keyboard facing the typist. The capacitance-responsive surface for the row of keys switches above the home row has a convex profile, and the capacitance-responsive surface for the row of keys switches below the home row has a concave profile, such that the keyboard can fold compactly upon itself. The home row retains depressible key switches in order to provide standard rest positions for the fingers. Characters and commands assigned to the rows above and below the home row are engaged by sliding the fingers over the capacitance-responsive surfaces adjacent to the home row.

Abstract: An authorization control system controlling who may use a device, includes a device for storing personal code data, a signal provider for outputting signals representing the personal code data, a signal delivery interface for receiving signals representing the personal code data, and adapted for wear by a user in proximity to a body of the user, a signal receive interface means, connected to the device, for receiving the signal from the signal delivery interface, a signal processing device, connected to the signal receive delivery interface, for determining a user's authorization for using the device by evaluating the signals and outputting a signal indicative of an evaluation result, a control device connected to the signal processing device, and an actuator for the device coupled to the control device, for allowing the user to use the device based on an output of the control device. Thus, the system allows a person to use the device only after the person has completed a successful authorization check.

Abstract: An electric field proximity detector capable of detecting partially conductive or conductive objects regardless of their impedance to circuit ground. The detector has a sensor with a transmitting electrode, a receiving electrode, and at least one circuit ground electrode preferably arranged in a bulls-eye configuration with the ground electrode between the transmitter and receiver electrodes. With appropriate sizing, upon the approach of an object, a signal received by the receiving electrode decreases, at least until the object is within a threshold distance of the sensor. The size and positioning of the ground electrode further reduces the effects of stray capacitance.

Abstract: An input device having a housing and electronic circuitry for detecting user inputs, and transmitting signals corresponding to those inputs to an electronic device, such as a computer. A sleep mode is provided for the electronic circuitry to conserve power. A hand detection circuit is provided for detecting the proximity of a user's hand to the housing and producing a hand detect signal in response. The hand detect signal will awaken the input device from its sleep mode.

Abstract: Capacitive proximity sensing is carried out by detecting a relative change in the capacitance of a “scoop” capacitor formed by a conductor and a surrounding ground plane. The conductor may be a plate provided in the form of an adhesive label printed with conductive ink. Charge is transferred between the “scoop” capacitor and a relatively large “bucket” capacitor, and a voltage of the bucket capacitor is applied to an input threshold switch. A state transition (e.g., from low to high, or high to low) of the input threshold switch is detected and a value (TouchVal) indicative of a number of cycles of charge transfer required to reach the state transition is determined. The presence or absence of an object or body portion in close proximity to or contact with a device can be determined by comparing TouchVal with a predetermined threshold value (TouchOff). TouchOff can be adjusted to take into account environmentally induced (non-touch related) changes in the capacitance of the scoop capacitor.

Abstract: A loss prevention system (e.g., 200) employs a method and apparatus for reducing the likelihood of losing a portable electronic device (100, 201) that has been inadvertently removed from its retaining device (e.g., 203, 300, 400). The loss prevention system includes the electronic device and its retaining device. The electronic device includes a proximity detector (103) that operates to detect the absence or removal of the device from the retaining device. The electronic device further includes a lost device detection circuit (102) that determines whether the removal was intentional and, if unintentional, alerts the user of the removal. By so alerting the user, the loss prevention system provides rapid feedback to the user after the user's electronic device has inadvertently fallen out of its retaining device, thereby enabling the user to quickly retrieve the device before it gets damaged or taken by someone else.

Abstract: A capacitive touch switch system for use in an audio application includes a detecting circuit with a capacitive sensing device and a filtering circuit. The capacitive sensing device senses changes in capacitance. The filtering circuit filters external and/or internal interference that may affect the sensing of a capacitance change and/or the sound quality of an audio device. The capacitive touch switch system may be incorporated into a speaker and/or other components of the audio device. The capacitive touch switch system may control various audio parameters such as volume, bass, treble, balance, channel, and the like.

Abstract: When a human body touches any of linear electrode array mutually isolated and arranged in X and Y directions of an input device, an inducing signal from wiring of a commercial power supply is transmitted by way of the human body, so that an inducing voltage is generated at the linear electrode to which the human body touches. The input device detects the inducing voltage and outputs the detected inducing voltage to a signal processing section. The signal processing section detects a coordinate where the input device detects the inducing voltage, identifies a frequency of the inducing signal transmitted by way of the human body, and outputs the information to an output terminal.

Abstract: The position of an object, which may be a user's finger, along a body is sensed capacitively. A measurement circuit meters the simultaneous injection of electrical charge into the two ends of the body, which may be shaped as a straight line or as a curve. A computing device computes the ratio of the relative changes in the amount of charge injected into each end of the element. The result of this computation is a one dimensional coordinate number plus a detection state indication, both of which can be fed to another functional element, such as an appliance controller, which interprets the coordinate and detection state as a command or measurement.

Abstract: A capacitive sensor including a first electrode that has at least one conducting surface being disposed for receiving an alternating current signal, and a second electrode that has at least one conducting surface being disposed to generate an input signal for a detecting device. The sensor further includes a middle electrode that has at least one conducting surface placed between the first electrode and the second electrode, as well as being grounded to a ground. The at least one conducting surface of the middle electrode, the at least one conducting surface of the first electrode, and the at least one conducting surface of the second electrode are contained within a holding material holding within itself the first electrode, the second electrode and the middle electrode.

Abstract: In a touch switch with a keypad 2, a tactual feedback of its operation, perceptible to the user, is said to be achieved. For this purpose a transducer 7 is provided, which upon a touching of the keypad 2 impressed a movement on the latter.

Abstract: A touch switch apparatus for detecting the presence of an object such as a human appendage, the apparatus having a touch pad and a local control circuit connected to the touch pad and to a controlled device. The touch pad preferable includes a first electrode and a second electrode spaced from and surrounding the first electrode. The control circuit is preferably in integrated circuit form. A signal is provided to the touch pad to generate an electric field thereabout. Introduction of a stimulus near the touch pad disturbs the electric field. The control circuit detects the electric field disturbance in and generates a control signal in response.

Abstract: A sensor element and a touch switch arrangement have a sensor surface, which engages on the underside of a control surface. The sensor surface is at least partly light-transmitting and is illuminated from below by a LED as the light source. A Funnel-shaped, closed light guide structure is provided, which guides or conducts the light from the LED to the sensor surface or shield against the environment. The light guide structure can additionally have further function(s) such as securing in position or electrical contacting of the sensor surface.

Abstract: Capacitive proximity sensing is carried out by detecting a relative change in the capacitance of a “scoop” capacitor formed by a conductor and a surrounding ground plane. The conductor may be a plate provided in the form of an adhesive label printed with conductive ink. Charge is transferred between the “scoop” capacitor and a relatively large “bucket” capacitor, and a voltage of the bucket capacitor is applied to an input threshold switch. A state transition (e.g., from low to high, or high to low) of the input threshold switch is detected and a value (TouchVal) indicative of a number of cycles of charge transfer required to reach the state transition is determined. The presence or absence of an object or body portion in close proximity to or contact with a device can be determined by comparing TouchVal with a predetermined threshold value (TouchOff).

Abstract: Physical structures respond to proximity or touch, conveying to a reader information such as the identity of the structure or some data associated therewith. In its simplest form, the structure comprises an electrical load and a pair of electrodes connected thereto. The electrodes are spaced apart (by air or other dielectric medium). A signal generator, which acts as a “reader,” is connected to a larger electrode that may be embedded in an environmental surface. When the structure is placed in proximity to the reader electrode, application of the signal results in capacitive coupling between the reader and the electrodes of the structure. The structure is not detected by the reader, however, because the capacitive coupling is comparable for both electrodes, so the load experiences only a small electrical gradient. But if one of the electrodes is grounded, this symmetry is broken and current is drawn through the load.