摘要:
A method for capacitive sensing comprises the steps of tagging a transmitting signal by modulating a sub-carrier on said signal using state of the art modulation techniques; demodulating said subcarrier out of useful/received signal to prove validity of said signal.
摘要:
A method for capacitive sensing comprises the steps of tagging a transmitting signal by modulating a sub-carrier on said signal using state of the art modulation techniques; demodulating said subcarrier out of useful/received signal to prove validity of said signal.
摘要:
A combined seat heater and capacitive occupancy sensor comprises a heater network and a capacitive sensing network. The heater network includes a heating element (10) connected between a first node (21) and a second node (22) to dissipate heat. The capacitive sensing network is connected to the heating element to apply an oscillating current thereto and to derive a capacitive load of the heating element from the voltage resulting on the heating element. The heater network comprises a common mode choke (16) connecting the first and the second node to a third (23) and a fourth (24) node, respectively. The capacitive sensing network further comprises means to sustain the oscillating current in or to drive the oscillating current into the heating element as well as a high-impedance amplifier (32) having an input node operatively connected to the heating element to probe the resulting voltage, and an output node (44) to provide an output signal indicative of the voltage.
摘要:
A combined seat heater and capacitive occupancy sensor comprises a heater network and a capacitive sensing network. The heater network includes a heating element (10) connected between a first node (21) and a second node (22) to dissipate heat. The capacitive sensing network is connected to the heating element to apply an oscillating current thereto and to derive a capacitive load of the heating element from the voltage resulting on the heating element. The heater network comprises a common mode choke (16) connecting the first and the second node to a third (23) and a fourth (24) node, respectively. The capacitive sensing network further comprises means to sustain the oscillating current in or to drive the oscillating current into the heating element as well as a high-impedance amplifier (32) having an input node operatively connected to the heating element to probe the resulting voltage, and an output node (44) to provide an output signal indicative of the voltage.
摘要:
A combined heating and capacitive seat occupant sensing system comprises a common mode choke configured so as to satisfy at least one of a plurality of conditions, which is taken into account by a decision unit of the system in such a way that an influence of the common mode choke on the decision is compensated.
摘要:
A combined seat heater and capacitive occupancy sensor comprises a heating element (10) connected between a first (21) and a second (22) node, and a capacitive sensing network connected to the heating element to apply an oscillating voltage thereto and to derive the capacitive load of the heating element. A common mode choke (16) connects the first and second node to a third (23) and fourth (24) node, respectively. The capacitive sensing network comprises an oscillator (28), AC-coupled to the third and/or the fourth node to drive oscillating voltage into that node, and a transimpedance amplifier (32), which has a first input to receive the oscillating voltage as reference voltage and a second input operatively connected to the heating element. The transimpedance amplifier maintains a voltage on its second input equal to the reference voltage by driving a current into the second input. An output signal (44) indicates the AC component of the current driven into the second input.
摘要:
A combined seat heater and capacitive occupancy sensor comprises a heating element (10) connected between a first (21) and a second (22) node, and a capacitive sensing network connected to the heating element to apply an oscillating voltage thereto and to derive the capacitive load of the heating element. A common mode choke (16) connects the first and second node to a third (23) and fourth (24) node, respectively. The capacitive sensing network comprises an oscillator (28), AC-coupled to the third and/or the fourth node to drive oscillating voltage into that node, and a transimpedance amplifier (32), which has a first input to receive the oscillating voltage as reference voltage and a second input operatively connected to the heating element. The transimpedance amplifier maintains a voltage on its second input equal to the reference voltage by driving a current into the second input. An output signal (44) indicates the AC component of the current driven into the second input.
摘要:
An RFID transceiver unit (10) for detecting an RFID transponder said transceiver unit comprises a transmitter associated with a loop-shaped transmitting antenna (12) for transmitting an electromagnetic excitation field and a receiver associated with a loop-shaped receiving antenna (14). When the RFID transponder (18) is excited by the excitation field (24), the RFID transponder emits an electromagnetic response field, which induces a transponder signal in the receiving antenna. The received signal generated by the receiving antenna in response to an electromagnetic field thus contains the transponder signal. The received signal of the receiving antenna generally contains an interfering signal directly induced by the excitation field in the receiving antenna. The transceiver unit comprises means for attenuating the interfering signal in the received signal.
摘要:
A seat heater, e.g. for a vehicle seat, comprises a heating element (10) for dissipating heat when a heating current flows across it and a temperature sensor (15) for providing a temperature signal indicative of the seat temperature. The seat heater comprises a common mode choke (16) with at least three windings. The heating element is connected in series between a first (16.1) and a second (16.2) thereof so as to be operatively connectable to a power source (12) via the common mode choke. The temperature sensor is connected to a third winding (16.3) of the at least three windings in such a way that the temperature signal may be received, e.g. by a temperature controller of the seat heater, via the third winding of the common mode choke.
摘要:
A capacitive sensing circuit is disclosed, wherein the mixer is directly connected to the sense electrode. The AC transimpedance amplifier in front of the mixer in prior art is removed and replaced by a differential DC transimpedance amplifier respectively integrator.The mixer DC offset voltage or current together with the large amplification factor required after the mixer now would result in an inacceptable DC offset at the output of the signal chain. In order to eliminate the effect of the mixer offset, the amplifying stages after the mixer are AC coupled to the mixer output and one of the signals entering the mixer is phase modulated or amplitude modulated with a known low frequency signal. An additional mixer after the AC coupled amplifying stages is driven with the same low frequency modulating signal, resulting in the wanted DC output signal responsive to the capacitance to be measured.