| IEE 10000-1819-B | |
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Before the arrival of reliable, easy-to-use LED displays like the Monsanto MAN-1, companies came up with a vast array of impractical methods to display numbers and characters. Projection displays, such as the one shown here, are one of these fringe display types, and were designed to compete directly with the neon filled Nixie tubes that were the leading display of the time. Also known as a "One Plane Readout" or "In Line Display", these devices were invented by IEE in 1956 for use in their proprietary industrial control systems; the devices proved so popular with customers that IEE began producing and selling the displays as a stand-alone product. Projection displays are complex devices with numerous parts, and were expensive to manufacture compared to a Nixie tube. For the modern hobbyist though, projection displays have several significant advantages over shaped cathode displays like Nixie tubes. Projection displays have replaceable bulbs, allowing the color of the displayed number to be changed simply by replacing the bulb with an appropriate LED light source. The digit masks in most projection displays are also replaceable, which allows for many custom display types to be quickly and easily produced. During the Cold War projection displays were quite popular for industrial control systems, since custom symbols and warning messages could be easily added to the digit mask. |
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