A microcontroller uses a combination of several synchronized PWM outputs to generate a low distortion sine wave by summing the PWM outputs and filtering the summed signal. The sine wave is used as a guard voltage. The unknown impedance is measured by impinging the guard voltage on the sense electrode by a transistor connected in common base configuration and then transferring the sense current through the common base connected transistor to a transimpedance amplifier made out of a second transistor connected in common emitter configuration. The output voltage at the collector of the second transistor is measured by an ADC input of the microcontroller. The microcontroller translates the ADC output values into the unknown impedance to be measured by doing a software demodulation of the ADC output values. A reference impedance can be connected in parallel to the unknown impeder to eliminate gain errors of the signal sensing circuit.

A sensor device is provided which includes a pressure-sensitive sensor which changes shape in response to pressing of an operation tool and which detects change in capacitance due to the change in shape, and a barrier which covers at least a part of the pressure-sensitive sensor and which prevents change in capacitance of the pressure-sensitive sensor due to capacitive coupling that occurs with approach between the pressure-sensitive sensor and the operation tool.

An operating device for a motor vehicle includes a plurality of proximity sensors for detecting contactless actuation. The operating device extends in a first plane and the sensors are disposed in that plane, separated from one another and oriented with their detection regions in the same spatial direction. A control and evaluation device is coupled to the sensors for detection of signals from each of the sensors. The sensors are covered with at least one electrically insulating plastic cover and, thus, separated from the detection region. At least one electrically conductive separating device is disposed between the sensors and oriented toward the side facing the detection regions, and directly adjacent to the plastic cover.

A portable electronic device includes a housing, a user input unit configured to detect touch input and push input, and a carrier, on which the user input unit is seated and which is inserted into the housing, wherein the user input unit includes a first input unit, closely disposed on an inner surface of the housing so as to detect touch input, and a second input unit, disposed inside the first input unit in the state of overlapping the first input unit so as to detect push input, the second input unit including a metal spring that changes in shape in response to the push input. The portable electronic device is capable of detecting two types of input and thus of ensuring that is possible to input a sufficient number of user instructions.

A capacitive sensor device comprises a first sensor electrode, a second sensor electrode, and a processing system coupled to the first sensor electrode and the second sensor electrode. The processing system is configured to acquire a first capacitive measurement by emitting and receiving a first electrical signal with the first sensor electrode. The processing system is configured to acquire a second capacitive measurement by emitting and receiving a second electrical signal, wherein one of the first and second sensor electrodes performs the emitting and the other of the first and second sensor electrodes performs the receiving, and wherein the first and second capacitive measurements are non-degenerate. The processing system is configured to determine positional information using the first and second capacitive measurements.

An apparatus, such as a set-top box, includes at least one capacitive touch button with a guard feature that provides, among other things, the ability to detect and reject false touches. According to an exemplary embodiment, the apparatus includes a first conductive element that is capacitively isolated from ground, and a second conductive element that is capacitively isolated from ground and located adjacent to the first conductive element. A first sensor is coupled to the first conductive element and measures a change in capacitance between the first conductive element and ground due to a change in physical environment. A second sensor is coupled to the second conductive element and measures a change in capacitance between the second conductive element and ground due to the change in physical environment. A controller is coupled to the first sensor and the second sensor and determines a difference between the measured changes in capacitance of the first sensor and the second sensor.

A capacitive sensing device includes an antenna electrode for emitting an alternating electric field in response to an alternating voltage caused in the antenna electrode and a control and evaluation circuit configured to maintain the alternating voltage equal to an alternating reference voltage by injecting a current into the antenna electrode and to measure the current. The control and evaluation circuit includes a microcontroller with a digital output for providing a digital signal and a low-pass filter operatively connected to the digital output for generating the alternating reference voltage by low-pass-filtering the digital signal.

A plurality of detection patterns are formed as conductive patterns directly on a back surface of a panel substrate to which an operation object such as a finger comes in proximity from a front surface side thereof. By independently detecting a change in capacitance in the plurality of detection patterns caused by proximity of the operation object from the front surface side, proximity of the operation object to the panel substrate is detected.

An accessory device for use with an electronic user apparatus is disclosed. The electronic user apparatus includes at least one capacitive sensor for detection of at least one control object with respect to a control surface, and at least one apparatus guard placed at an alternating guard potential (V.sub.G), different from a ground potential of the at least one control object, and identical to a potential of the capacitive sensor. The accessory device includes at least one accessory guard capable of being set to the alternating guard potential (V.sub.G) by coupling with the electronic user apparatus.

The present invention relates to a capacitive presence sensor (1) arranged in the gripping lever (L) of a handle of an openable body section (2) of a motor vehicle (V) characterised in that it comprises: a printed circuit (10) including a first surface (101) and a second surface (102), an electrode (E1) including a surface which extends along said first surface (101) and a second electrode (E2) including a surface which extends along said second surface (102); and also in that it comprises: a guard plane (13) made up of a conductive track arranged between the first electrode (E1) and the second electrode (E2), passing through the body (e) of said printed circuit (10) and comprising a first printed surface (130) extending along said first surface (101) of the printed circuit (10) and a second printed surface (131) extending along said second surface of the printed circuit (10).