Vehicle security system

摘要

A transponder (22) embedded in a key (20) and a reader/exciter coil (26, 46) surrounding the lock cylinder (12, 60) are inductively linked to provide energization to the transponder (22), causing it to emit a digital identification code. A control circuit (28, 56) associated with the coil (26, 46) supplies energising coil current and analyses the emitted code to verify the authenticity of the key (20). The coil (26, 46) and control circuit (28, 56) are contained in a planar multi-layer hardboard printed circuit (18, 40) having high circuit integrity and being very thin for accommodation in the lock assembly. Alternatively, the coil (26, 46) and control circuit (28, 56) are contained in a flexible printed circuit (40). There the coil (46) includes two opposed elongated legs (48a, 48b) which are positioned on opposite sides of the lock cylinder (60) and folded in a way to conform to the cylinder surface, forming in effect a very thin cylindrical coil. An extension on the printed circuit (54) forms a path to the control circuit (56) which is remote from the cylinder (60). $$ $$