LIGHT GATE ARRAY SHUTTER DEVICE
Original Publication Date: 1989-Aug-31
Included in the Prior Art Database: 2004-Apr-05
Xerox Disclosure Journal
The Figure shows a gradient index lens array 2 which has been separated at an intermediate image position to form two sections 2A and 2B. A light gate shutter array device 4 (such as a liquid crystal shutter array) is inserted between the two sections and the sections are reattached to form an optically integral lens array. The shutter array can then be controlled by application of a pre-determined voltage across electrodes 6. The shutter can be made to open or close a desired amount to bring the light output to a uniform level across the width of the array. This uniformity thus improves the uniformity of array ROS or RIS devices which are used in combination with the gradient index lens array. When used with, for example, a ROS device the voltage to be applied across the shutter is determined by scanning a detector past the array ROS device prior to printing. The detector maps out the non-uniform level of each pixel in the array ROS device and the signals are stored in a PROM. Prior to printing, these signals are converted to the required voltage levels which open or close the shutter accordingly. This technique allows for correction to be made at levels other than pixel to pixel correction and can also be used to produce infinite levels of gray shades since the light output of each pixel in an array ROS device can be controlled remotely by the light gate shutters in a continuous fashion.