Capacitively coupled identity verification and escort memory apparatus

A system controlled by a datum stored in an escort apparatus, the system comprising a reader apparatus electrically coupled to an electrical ground, wherein:

• the reader comprises
• means supplying an alternating electric voltage to a reader plate during a predetermined interval, and
• signal receiving means receiving signals electrically coupled to the reader plate;
• and wherein
• the escort apparatus comprises
• a communication plate capacitively coupled to the reader plate,
• a bearer plate electrically coupled to a bearer of the escort apparatus, the bearer electrically coupled to the ground,
• charging means coupled to the communication plate, the charging means charging an energy storage capacitor to a predetermined dc voltage responsive to the alternating electric voltage, and
• signaling means electrically powered by the energy storage capacitor subsequent to the predetermined interval to provide a signal representative of the datum to the signal receiving means.

A method of operating a reader apparatus in a system controlled by a datum stored in an escort apparatus carried by a bearer, the reader comprising an electric power supply, a capacitive sensing means measuring a capacitance to an electrical ground of a reader plate, a time-keeping means, a pulse generating means applying a plurality of pulses to the plate, and a signal receiving means;

• the method comprising the steps of:
• a) measuring a first value of the capacitance to the ground of the reader plate at a first time when the bearer is not proximate the reader,
• b) causing the reader apparatus to operate in a low energy consumption mode for a predetermined sleep interval, the interval measured by the time-keeping means;
• c) causing, at the conclusion of the sleep interval, the reader apparatus to measure a second value of the capacitance to the ground of the reader plate;
• d) comparing the first and second capacitance values and repeating step b) if the first and second values differ by less than a predetermined amount, and otherwise
• e) applying a plurality of the pulses to the reader plate;
• f) waiting for a predetermined interrogation interval for a signal from the escort apparatus and, if the signal is received;
• g) reading, with the signal receiving means, the control datum from the escort apparatus.

A system comprising a reader electrically coupled to an electrical ground and an escort apparatus borne by a bearer electrically coupled to the ground, wherein the reader comprises

• a reader plate,
• a source of dc voltage,
• a reader microprocessor operating under control of a first stored program stored in a
• first memory,
• a pulse generating means controlled by the reader microprocessor to generate a charging pulse and a subsequent discharging pulse,
• a charging switch having an open state and a closed state, the charging switch moving from its open to its closed state responsive to the charging pulse, the charging switch connecting the voltage source to the reader plate when in the closed state, the charging switch otherwise disconnecting the voltage source from the reader plate,
• a discharging switch having an open state and a closed state, the discharging switch moving from its open to its closed state responsive to the discharging pulse, the discharging switch connecting the reader plate to a charge measurement means when in its closed state, the discharging switch otherwise not connecting the plate to the charge measurement means, whereby a quantity of charge representative of an apparent capacitance between the reader plate and ground is transferred to the charge measurement means, and
• receiver means receiving signals coupled to the reader plate;
• and wherein the escort apparatus comprises
• bearer plate capacitively coupled to the bearer,
• a communication plate capacitively coupled to the reader plate,
• an escort microprocessor operating under control of a second stored program,
• a non-volatile memory storing a datum, and communication means connected to the communication plate and operating under control of the escort microprocessor to generate a coded representation of the stored datum,
• whereby the coded representative of the stored datum is received by the receiver circuit.