Sensor
An energy-autonomous sensor for detection of physical environmental parameters, having at least one sensor element, one storage element and one control circuit, with a timer circuit which is activated on reaching a predetermined electrical voltage on the storage element, activates the sensor and the control circuit at predetermined time intervals, and deactivates them after a predetermined operating time, such that this results in a time duration of sensor operation and a sensor operation pause.
1. An energy-autonomous sensor for detection of physical environmental parameters, comprising:
a sensor element for detecting the physical environmental parameters;
a control circuit for encoding the detected physical environmental parameters;
a radio-frequency transmitter producing one of a radio-frequency signal and a radio message to transmit encoded physical environmental parameters and to transmit an ID-number of the sensor;
a timer circuit which activates the control circuit, the sensor element and the radio-frequency transmitter at a predetermined time interval, and deactivates said control circuit and said sensor element and said radio-frequency transmitter after a predetermined period of operation, to define a time duration of operation and a time duration associated with an operational pause; and
a photovoltaic element which is connected to a storage element to supply power to the storage element, the storage element being configured to store electrical energy and being connected to the timer circuit to provide electrical energy to at least one of the timer circuit, the control circuit, the sensor element and the radio-frequency transmitter;
wherein the photovoltaic element is configured such that it is smaller than required for direct operation of the timer circuit, the control circuit, the sensor element and the radio-frequency transmitter.
2. The sensor as claimed in claim 1 , wherein the time duration of the sensor element operation is substantially shorter than the time duration of the operational pause of the sensor element.
3. The sensor as claimed in claim 1 , wherein on each activation of the control circuit, the predetermined time interval for activation of the control circuit is redefined as a function of a charge state of the storage element.
4. The sensor as claimed in claim 1 , wherein the predetermined time interval for activation of the control circuit is redefined as a function of illumination intensity at the photovoltaic element at the time the control circuit is activated.
5. The sensor as claimed in claim 1 , wherein the storage element is at least one of a capacitor and an electrochemical energy store.
6. The sensor as claimed in claim 1 , wherein the sensor element detects moisture or humidity as the physical environmental parameter.
7. The sensor as claimed in claim 1 , further comprising:
at least two electrodes for performing a moisture or humidity measurement via an impedance measurement.