US 5,381,074 AGranted

Self calibrating lighting control system

AssigneeChrysler Corporation

InventorsRobert G. Rudzewicz, Gary B. Flaishans, Michael A. Dahl

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Abstract

A lighting control system with self calibration for employing the entire physical travelling range of a dimmer switch. A lookup table and linear interpolation are used in conjunction with the voltage output of the dimmer switch in order to identify the appropriate duty cycle of a Pulse Width Modulated signal which drives the lamps in the system. Two of the values in the lookup table are default minimum and maximum values of voltage which can be expected from a worst case switch device. The system dynamically determines and stores any new maximum or minimum voltage which is received from the dimmer switch. These dynamically determined minimum and maximum values are used to replace the default values in the lookup table thus calibrating the lookup table. The calibrated lookup will take into account the operating parameters of the actual switch in the vehicle and will therefore always produce a corresponding change in illumination intensity over the entire physical range of the dimmer switch.

Claims20

Dependent claims

A method of controlling illumination intensity of lighting devices in a lighting system having a potentiometer dimmer switch, said method comprising:

reading a voltage from said dimmer switch;
comparing said dimmer voltage to a self calibration maximum voltage, said self calibration maximum voltage being stored in a first memory location of said system;
replacing said self calibration maximum voltage in said first memory location with said dimmer voltage if said dimmer voltage is greater than said self calibration maximum voltage;
comparing said dimmer voltage to a self calibration minimum voltage, said self calibration minimum voltage being stored in a second memory location of said system;
replacing said self calibration minimum voltage in said second memory location with said dimmer voltage if said dimmer voltage is less than said self calibration minimum voltage;
extracting a maximum illumination intensity data from a third memory location;
extracting a minimum illumination intensity data from a fourth memory location;
interpolating an illumination intensity level, using said self calibration maximum and minimum voltages stored in said first memory location and said second memory location, said maximum and said minimum illumination intensity data, and said dimmer voltage;
generating an illumination control signal based upon said illumination intensity level;
and
transmitting said illumination control signal to said lighting devices to control illumination of said lighting devices in proportion thereto.

8 more elements

A lighting system for controlling illumination intensity comprising:

a potentiometer dimmer switch, said dimmer switch generating a dimmer voltage;
a first controller having a microprocessor and at least one memory, said first controller having as an input said dimmer voltage from said dimmer switch, said first controller having as an output an illumination intensity signal;
at least one illumination device, said illumination device having as an input said illumination intensity signal;
a first memory location in said at least one memory, said first memory location containing a self calibration maximum voltage;
a second memory location in said at least one memory, said second memory location containing a self calibration minimum voltage;
a means for replacing said self calibration maximum voltage in said first memory location with said dimmer voltage if said dimmer voltage is greater than said self calibration maximum voltage;
a means for replacing said self calibration minimum voltage in said first memory location with said dimmer voltage if said dimmer voltage is less than said self calibration minimum voltage;
a third memory location in said at least one memory, said third memory location containing a maximum intensity data;
a fourth memory location in said at least one memory, said forth memory location containing a minimum intensity data;
and
a means for determining said illumination intensity signal using said self calibration maximum voltage, said self calibration minimum voltage, said maximum intensity data, said minimum intensity data, and said dimmer voltage.

8 more elements

Dependencies are inferred from the claim text.