The present invention relates to display systems and, more particularly, to display systems incorporating magneto-optic chips employing Faraday rotation in conjunction with polarized light.
Magneto-optic displays are a phenomenon gaining rapid acceptance. Chips, such as that generally indicated as 10 in FIG. 1, comprise a substrate 12 having a film 14 of a material such as garnet (which will rotate polarized light by the so-called "Faraday effect") which film is divided into posts 16 to form a rectangular pattern of rows (labelled for convenience R1-R6) and columns (labelled for convenience C1-C6). Control wires 18 and 20, respectively, are placed between the columns (designated CC1-CC6) and between the rows (designated CR1-CR6). In this configuration, each post 16 can be addressed individually in the manner of a core memory at the intersection of a column control wire 18 and a row control wire 20. Each post 16 represents a pixel position in the overall display. The material of the film 14 has the effect of rotating polarized light in one direction by Faraday rotation when magnetized in one direction and of rotating polarized light in the opposite direction when magnetized in the opposite direction thus modulating the light passing therethrough. Such chips are discussed in greater detail in co-pending applications Ser. No. 375,329, filed May 5, 1982, by R. H. Anderson, titled IMPROVED MAGNETO-OPTIC IMAGE SCANNING DETECTOR and Ser. No. 375,321, filed May 5, 1982 by R. H. Anderson, W. E. Ross, and T. R. Maki, titled MAGNETO-OPTIC CHIP WITH GRAY-SCALE CAPABILITY, both of which are assigned to the common assignee of this application.
The chip 10 of FIG. 1 can be disposed in a light beam 22 from a source 24 between a polarizer 26 and a polarization analyzer 28 as shown in FIG. 2. The wires 18, 20 are contained in a cable 30 connected to a driver 32. The driver 32 drives the chip 10 to create display information within the posts 16. Light 22 passing through the polarizer 26 is polarized to the axis of polarization of the polarizer 26. This polarized light in passing through the chip 10 is rotated by the film 14 of each individual post 16 clockwise or counter-clockwise depending upon the magnetization thereof as set by the driver 32. The polarization analyzer 28 is positioned with respect to the expected emerging light orientation from the chip 10 so as to create a contrast between areas rotated in one direction and areas rotated in the opposite direction. This contrast can be seen by the observer 34. The specific effect will be discussed later hereinafter.
Such chips and display systems can be viewed directly as shown in FIG. 2 or can be projected through appropriate optics. Another display system to achieve particular effects is shown in my co-pending application Ser. No. 375,322, filed May 5, 1982 titled SWITCHABLE TANDEM MEMORY MAGNETO-OPTIC DISPLAY also assigned to the common assignee of this application.
Particularly in military use, displays having the capability of providing more than just simple messages are desired. Displays are used to impart a wealth of information. One particular feature which would be desirable and not possible by other display systems of the magneto-optic type heretofore is the conveying of depth-of-field information. Also, it is desirable to have a display which can selectively display only information where there is coincidence between two sources of data or, in the alternative, only where there is lack of coincidence between two sources of data. Such features can be used for image processing in military, space, transportation and computer uses, where either the similarities or differences between different images are detectable, such as in moving target indicators, updated inventory listings, extraction of stereo depth information, character recognition in machine-readable documents, and high reliability information processing.
Wherefore, it is the object of the present invention to provide a magneto-optic display generator which will accomplish the foregoing objectives.