Obstruction detection system for motorized window shades and method of use

Abstract

An obstruction detection system for motorized window shades is presented having a motor, shade material, a bottom bar, and a motor controller having a microprocessor. The microprocessor is configured to detect when an obstruction has been encountered when closing the motorized window shades. When an obstruction is detected, the microprocessor stops lowering the shade material and the bottom bar thereby preventing further damage or destruction. The system may also be used to report when an unexpected obstruction has been detected.

What is claimed: 
     
         1 . A method of setting the operational limits of a motorized window shade, the steps comprising:
 installing a motorized window shade having a motor, shade material, a bottom bar, and a microprocessor configured to operate the motor;   providing a current sense resistor in electrical connection with the motor and the microprocessor;   lowering the shade material and bottom bar during a learn mode;   detecting that an obstruction has been encountered by the microprocessor while the shade material and bottom bar is being lowered from signals received from the current sense resistor;   setting a bottom limit based upon the location of the detected obstruction.   
     
     
         2 . The method of  claim 1 , further comprising a step of providing an amplifier in electrical connection with the current sense resistor and the microprocessor. 
     
     
         3 . The method of  claim 1 , wherein the obstruction is a window sill.