Magneto-optic chip with gray-scale capability

• US 4,661,809 A
• Filed: 01/11/1985
• Issued: 04/28/1987
• Est. Priority Date: 05/05/1982
• Status: Expired due to Term

• Current Assignee: Litton Systems Incorporated (Northrop Grumman Corporation)
• Original Assignee: Litton Systems Incorporated (Northrop Grumman Corporation)
• Inventors: Maki, Theodore R., Anderson, Robert H., Ross, William E.
• Primary Examiner(s): Brigance, Gerald L.
• Application Number:
  US06/690,593
• Time in Patent Office: 837 Days
• Field of Search: 340/783, 340/793, 340/795, 340/716, 350/375, 350/376, 350/377, 350/392
• US Class Current: 345/86
• CPC Class Codes: G02F 1/09 based on magneto-optical elements, e.g. exhibiting Faraday effect

Abstract

Methods of operation and details of chip design to realize gray-scale capability in magneto-optic chips. Individual pixels are operated in three states by the addition of a stripped state to the usual stable magnetized states in either direction. Varying thicknesses of film are employed along with stacked identically patterend chips operated in tandem. Pixel divisions are divided into individually-addressible areas of differing sizes which can be operated in different combinations to provide varying levels of brightness through each pixel position.

Claims

1. A magneto-optic chip (42) to achieve gray-scale including a plurality of pixel positions (44);

the magneto-optic chip comprising;

(a) each of the pixel positions including individually-addressable pixel sub-positions (46, 48, 50,

     52);

(b) at least two of said pixel sub-positions having respective areas of different size; and

(c) a first pair of conductors (47,

     49) oriented in a first direction and a second pair of conductors (51,

     53) oriented in a second direction to electrically address individual ones of said different sized pixel sub-positions and place a selected one of said pixel sub-positions in a respective one of three magnetic states, which affect the passage of light therethrough at an associated one of three light levels;

a first magnetic state when magnetized one direction so that the selected pixel sub-position is transparent to light passage, a second magnetic state when magnetized in an opposite direction so that the sub-position is opaque to light passage, and a third magnetic state when demagnetized or stripped out so that the sub-position is both transparent and opaque to light passage, so that an associated amount of light passage through said selected pixel sub-position has one of the three levels of light passage or brightness, and selected pixel sub-positions associated with the respective pixel position develop a desired degree of gray scale at the respective pixel position.

2. The magneto-optic chip of claim 1 in which each pixel position has four individually-addressable pixel sub-positions being of relative area one, two, four, and eight whereby eighty-one levels of brightness can be achieved by using said sub-positions singly or in combination.

3. The magneto-optic chip of claim 2 in which at least first and second

magneto-optic chips, having identically patterned pixel positions and sub-positions, are positioned adjacent to and spaced apart from one another with respective ones of said first magneto-optic chip pixel positions and sub-positions in registration with associated ones of said second magneto-optic chip pixel positions and sub-positions and are driven simultaneously with selected display patterns.