Patent ID: 6968073

Claim:
A method of detecting a penetration of a bounding surface of an avoidance zone in a region of space of in a vehicle proximate to an air bag inflator, comprising: a. generating an image signal representative of a first image of said region of space from a first location, wherein said region of space includes the bounding surface of the avoidance zone, and said image signal is generated responsive to an exposure time; b. projecting from a second location a light curtain substantially parallel to and along a first surface, wherein said light curtain has a thickness within a cross-section normal to said first surface, said thickness is adapted so that an intensity of said light curtain within said cross-section is less than a first threshold, said first threshold corresponds to an intensity level that is safe for direct viewing by a human eye, and said first surface is proximate to the bounding surface of said avoidance zone; c. generating an image signal representative of a second image of said region of space from said first location, wherein said region of space is intersected by said light curtain when said light curtain is activated; d. subtracting said first image from said second image so as to form a difference image; e. forming a binned image value of a binned image by accumulating a plurality of pixel values within a region of said difference image; f. repeating the operation of forming said binned image value for a plurality of adjacent regions of said difference image; g. detecting from said binned image a leading edge associated with an image of said light curtain; and h. determining whether or not an object is located in said avoidance zone responsive to a comparison of said leading edge with a reference image signal representing a boundary of said avoidance zone.