US 6,298,311 B1 · Infrared occupant position detection system and method for a motor vehicle

Abstract

An improved IR occupant position detection system that provides accurate and reliable classification and position information at a speed sufficient to timely inhibit or otherwise control deployment of occupant restraints. A two-dimensional array of IR emitters is selectively activated to periodically illuminate two or more of predetermined viewing planes in the vicinity of a passenger seating area, and the reflected IR energy is detected by a photo-sensitive receiver and analyzed to detect the presence of an occupant, to classify the occupant, and to identify and dynamically track the position of the occupant's head/torso relative to predefined zones of the passenger compartment. Modulating the intensity of the emitted IR beams with a known carrier frequency, band-pass filtering the received signal, and synchronously detecting the filtered signal distinguishes the reflected IR energy from other signals picked up by the IR receiver. Additionally, a two stage adaptive control mechanism compensates for the variation in intensity of the reflected energy with distance between the emitter and the occupant. The emitter is implemented with orthogonal anode and cathode power rails with individual IR LED elements placed at each anode-cathode intersection. Optical dispersion within the package is greatly reduced by an opaque cover layer that effectively forms a well for each LED element.

Claims24

Dependent claims

A system for detecting a position of an occupant of a motor vehicle including an IR transmitter for emitting a beam of IR light through an optical lens for reflection off the occupant, an IR receiver for receiving the reflected IR light and forming an occupant range related input signal therefrom, and a controller coupled to said IR transmitter and IR receiver for determining the position of the occupant from said input signal, an improvement wherein:

the IR transmitter includes an IR light emitting diode for emitting said beam of IR light, and a current source effective when enabled to activate said light emitting diode with a sinusoidal current of predetermined frequency so that the emitted beam of IR light has an intensity that is modulated at said predetermined frequency;
the IR receiver includes a photo-sensitive device that generates a current signal having an occupant range related component at said predetermined frequency and representing the range of said occupant, and a band-pass filter for extracting said occupant range related component from said current signal to form said input signal.

A system for detecting a position of an occupant of a motor vehicle including an IR transmitter for emitting a beam of IR light through an optical lens for reflection off the occupant, an IR receiver for receiving the reflected IR light and forming an occupant range related input signal therefrom, and a controller coupled to said IR transmitter and IR receiver for determining a range of the occupant from said input signal, an improvement wherein:

the IR receiver includes a photo-sensitive device that generates a current signal having an occupant range related component representing the range of said occupant, a circuit for extracting such component from said current signal, and a programmable gain amplifier for amplifying the extracted component to form said input signal;
and
the controller receives the input signal at an input port thereof, and adjusts the gain of said programmable gain amplifier based on a magnitude of the received input signal so as to drive said input signal into a desired input range of said input port.

A system for detecting a position of an occupant of a motor vehicle including an IR transmitter for emitting a beam of IR light through an optical lens for reflection off the occupant, an IR receiver for receiving the reflected IR light and developing an occupant range related input signal therefrom, and a controller coupled to said IR transmitter and IR receiver for determining the position of the occupant from said input signal, an improvement wherein:

the IR transmitter includes an array of IR light emitters that are individually and selectively activated to emit beams of IR light corresponding to respective positions of the activated IR light emitters in said array;
the controller includes:
a microprocessor for requesting activation of a selected IR light emitter, receiving the input signal corresponding to the selected IR light emitter, and determining the occupant position based on a plurality of said input signals;
and
a state machine that operates in response to a requested activation of a selected IR light emitter to enable activation of the selected IR light emitter by the IR transmitter and reception of the reflected IR light by the IR receiver, and to signal the microprocessor that the input signal corresponding to the selected IR light emitter is ready to be received.

2 more elements

A system for detecting a position of an occupant of a motor vehicle including an IR transmitter for emitting a beam of IR light through an optical lens for reflection off the occupant, an IR receiver for receiving the reflected IR light and developing an occupant range related input signal therefrom, and a controller coupled to said IR transmitter and IR receiver for determining the position of the occupant from the input signal, an improvement wherein:

the IR transmitter includes a two-dimensional array of IR light emitting diodes that are individually and selectively activated to emit a beam of IR light corresponding to a position of the activated IR light emitting diode in said array, said array including a first plurality of parallel conductor segments defining columns of said array and a second plurality of parallel conductor segments oriented perpendicular to said first plurality of segments and defining rows of said array, each of said IR light emitting diodes being positioned at a unique intersection of a row and column of said array, and activated when the conductor segments defining such row and column are coupled to a current source.

A system for detecting a position of an occupant of a motor vehicle including an IR transmitter for emitting a beam of IR light through an optical lens for reflection off the occupant, an IR receiver for receiving the reflected IR light and developing an occupant range related input signal therefrom, and a controller coupled to said IR transmitter and IR receiver for determining the position of the occupant relative to a predefined zone of the vehicle, an improvement wherein:

the IR transmitter includes a two-dimensional array of IR light emitters that are individually and selectively activated to emit a beam of IR light corresponding to a position of the activated IR light emitter in said array;
the controller selectively and repeatedly activates each of the IR light emitters in a determined sequence and receives corresponding input signals to identify an emitter array position corresponding to a beam of IR light illuminating a head/torso of the occupant, and to indicate when the identified emitter array position corresponds to a beam of emitted light passing through said predefined zone.

Dependencies are inferred from the claim text.

Infrared occupant position detection system and method for a motor vehicle

Life of this patent

Infrared occupant position detection system and method for a motor vehicle

Life of this patent

Abstract

Claims24