Event-recording devices with identification codes

DETAILED DESCRIPTION The present invention provides a device that can be interrogated to determine its identity and its state.
The state indicates whether one or more particular physical or chemical events have taken place.
In effect, the device records one or more physical or chemical events or states.
The device states used to record the one or more events may be recycled.
The identity of the device allows it to be distinguished from a number of similar devices.
Thus this invention finds particular usefulness in the context of an array of devices that can be probed by a wireless interrogation unit.
The device tells the interrogator who it is and what state it is in.
The devices and interrogation unit may use a logical analysis and reset to determine if an event has occurred.
The interrogator can thus easily identify particular items in an array that have reached one or more particular conditions.
Other devices may be used to sense, record and report multiple physical or chemical events or states.
The multiple physical or chemical events or states may be different physical or chemical events or states or may be the same physical or chemical state or event occurring numerous separate times.
The multiple events or states may occur separately within two interrogations and/or multiple times over numerous interrogations.
In one embodiment for recording multiple events, the recording device assumes multiple distinct states.
Each distinct state may be associated with a particular physical or chemical state or event and can be held until another event occurs.
Each distinct device state may also be reported by the transponder in response to wireless interrogation.
In another embodiment, the multiple device states may be recycled to permit continuous of the device.
In one specific example, the sensor is a temperature sensor and the physical or chemical events or states are exceeding one or more (high or low) threshold temperatures.
A suitable device for this purpose may include a circuit as the recording mechanism and fuses in the circuit as the sensor