Method and apparatus for non-contacting information transmission

An apparatus for non-contacting information transmission between a data carrier and a data reader which are locationally independent of one another and a brought together for information transmission, comprising:

• at least two planar electrodes provided at a surface of the data carrier;
• at least two planar electrodes in the data reader which are brought together with said at least two planar electrodes of the data reader to form capacitors for information transmission by producing at least one common circuit for the data carrier and the data reader;
• an oscillator in the data reader having outputs connected to said at least two electrodes of the data reader;
• a precision resistor connected between said oscillator and at least one of said at least two electrodes of the data reader;
• an evaluation means connected to said precision resistor for evaluating the information for transmission by a voltage drop across said precision resistor;
• a rectifier arrangement having inputs connected to said at least two planar electrodes in the data carrier;
• a transistor in the data carrier having at least one lead connected to said rectifier arrangement;
• an electronic memory unit connected to said rectifier arrangement and said transistor;
• a clock signal of said oscillator controlling information output from said memory unit in the data carrier.

An apparatus for noncontacting information transmission between a data carrier and a data reader which are locationally independent of one another and are brought together for information transmission, comprising:

• three planar electrodes provided at a surface of the data carrier;
• three planar electrodes in the data reader which are brought together with said three planar electrodes of the data carrier to form capacitors for information transmission by producing at least one common circuit for the data carrier and the data reader;
• an oscillator in the data reader having outputs connected to said three electrodes of the data reader;
• a precision resistor connected between said oscillator and at least one of said three electrodes of the data reader;
• an evaluation means connected to said precision resistor for evaluating the information by a voltage drop across said precision resistor;
• a rectifier arrangement having inputs connected to two of said three planar electrodes in the data carrier;
• a transistor in the data carrier having at least one lead connected to said rectifier arrangement;
• an electronic memory unit connected to said rectifier arrangement and said transistor;
• one of said three electrodes in the data carrier directly connected to a data output of said electronic memory unit by said transistor;
• said oscillator in the data reader having first and second leads directly connected respective first and second ones of said three electrodes in the data reader, a clock signal of said oscillator controlling information output from said memory unit;
• and
• said precision resistor in the data reader connecting one of said first and second leads of said oscillator to a third one of said three electrodes.