초록 ▼

An RF identification system for generating data indicative of an item that is tagged, and one bit of variable data representative of an external stimulus. An ID code reader is provided and an RF identification tag is coupled to the item that is to be monitored and the ID code reader queries the tag.

An RF identification system for generating data indicative of an item that is tagged, and one bit of variable data representative of an external stimulus. An ID code reader is provided and an RF identification tag is coupled to the item that is to be monitored and the ID code reader queries the tag. The tag comprises two RF transponder chips that store a data relating to the item, and an excitation coil coupled thereto. A switch is coupled to the chips and excitation coil, and a capacitor is coupled across the switch. A sensor is coupled to the switch for generating one bit of variable data representative of an external stimulus, such as the pressure in a tire. The ID code reader comprises an exciter and RF excitation coil, and a receiver and an RF receiver coil. The receiver includes phase detection circuitry for detecting a state of the switch by detecting the phase shift between signals received from each of the transponder chips. When the switch is shorted, the effect of the capacitor is nullified. When the switch is is open, then the return signal from the second transponder chip has a small phase shift with respect to the signal from the first transponder chip. The phase detection circuitry detects this phase shift and determines the state of the switch. The system permits the use of an RF identification tag in remote or inaccessible positions to determine the state of a variable (the position of the switch) and store identification data. An example of this is an identification tag in a vehicle tire that stores the tire ID and also enables the reading of a pressure switch to confirm adequate tire pressure.

대표청구항 ▼

[ What is claimed is:] [1.] An RF identification system for generating data indicative of an item that is tagged, and one bit of variable data representative of an external stimulus, said system comprising:an RF identification tag coupled to the item that is to be monitored that comprises:first and

[ What is claimed is:] [1.] An RF identification system for generating data indicative of an item that is tagged, and one bit of variable data representative of an external stimulus, said system comprising:an RF identification tag coupled to the item that is to be monitored that comprises:first and second RF transponder chips that each store data relating to the item that is to be monitored and that each comprise first and second antenna outputs;an excitation coil having one input coupled to respective first antenna outputs of the first and second RF transponder chips;a switch coupled between respective second antenna outputs of the first and second RF transponder chips and coupled to a second input of the excitation coil;a capacitor coupled across the switch; anda sensor coupled to the switch for generating one bit of variable data representative of an external stimulus; andan ID code reader that comprises:an exciter;an RF excitation coil coupled to the exciter;a receiver comprising an RF receiver coil and phase detection circuitry for detecting a state of the switch by detecting the phase shift between signals received from each of the transponder chips.