Optical Position Sensor Architecture for Servo Systems

Abstract

System and method for an optical position sensor architecture for use in servo systems. A preferred embodiment comprises a light source configured to produce a light with an intensity dependent upon a control signal, a first light sensor and a second light sensor positioned adjacent to one another, each light sensor configured to produce a current based upon an amount of light incident upon each light sensor. The preferred embodiment also comprises a slotted device coupled to the load and positioned between the light source and the first light sensor and the second light sensor. The slotted device regulates an amount of light striking the first light sensor and the second light sensor based upon a position of the load. The slotted device features a slot that has a radius with a linearly increasing radius as a function of rotation angle so that the optical position sensor has linear behavior.

1 - 10 . (canceled) 
   
   
       11 . A method for generating a feedback control signal for an optical servo system, the method comprising:
 computing the feedback control signal from a difference of a first current produced by a first optical sensor and a second current produced by a second optical sensor; and   computing a light modulation signal for a light source illuminating the first optical sensor and the second optical sensor, wherein the modulation of the light source results in an automatic normalization of the feedback control signal.   
   
   
       12 . The method of  claim 11 , wherein the second computing comprises:
 computing a sum voltage proportional to a sum of the first current and the second current;   subtracting the sum voltage from a reference voltage; and   integrating a difference of the sum voltage and the reference voltage to produce the light modulation signal.   
   
   
       13 . The method of  claim 11 , wherein the light modulation signal is used to drive a light emitting diode (LED) that is used to illuminate the first optical sensor and the second optical sensor. 
   
   
       14 . The method of  claim 11  further comprising prior to the first computing, amplifying the first current and the second current. 
   
   
       15 . The method of  claim 11  further comprising after the second computing, using the light modulation signal to illuminate the light source. 
   
   
       16 . The method of  claim 11 , wherein the light modulating signal is continually computed so that a sum of the first current produced by the first optical sensor and a second current produced by the second optical sensor remains substantially constant. 
   
   
       17 . A display system for displaying images, the display system comprising:
 an array of light modulators configured to create images comprised of pixels by setting each light modulator in the array of light modulators into a state matching a corresponding pixel;   a light source to illuminate the array of light modulators, wherein a light from the light source reflecting off the array of light modulators forms the images on a display;   an aperture positioned in between the light source and the array of light modulators, the aperture configured to modulate the light produced by the light source; and   a servo system coupled to the aperture, the servo system configured to move the aperture into position to modulate the light by a desired amount.   
   
   
       18 . The display system of  claim 17 , wherein the servo system comprises:
 a servo controller coupled to a display system controller, the servo controller configured to translate servo commands issued by the display system controller into commands to move the aperture;   a motor coupled to the servo controller and the aperture, the motor to move the aperture in response to commands from the servo controller; and   an optical position sensor coupled to the aperture, the optical position sensor configured to translate positional information into electrical information.   
   
   
       19 . The display system of  claim 18 , wherein the optical position sensor comprises:
 a second light source configured to produce a light with an intensity dependent upon a control signal;   a first light sensor and a second light sensor positioned adjacent to one another, each light sensor configured to produce a current based upon an amount of light incident upon a detector in each light sensor; and   a slotted device coupled to the aperture and positioned between the second light source and the first light sensor and the second light sensor, the slotted device configured to regulate an amount of light produced by the second light source that strikes the first light sensor and the second light sensor based upon a position of the aperture.   
   
   
       20 . The display system of  claim 19 , wherein the second light source comprises a light-emitting diode. 
   
   
       21 . The display system of  claim 17 , wherein the aperture comprises a plurality of openings to modulate the light produced by the light source by different amounts. 
   
   
       22 . The display system of  claim 17 , wherein the light modulators are movable micromirrors. 
   
   
       23 . The display system of  claim 17 , wherein the light modulators are deformable mirrors.