Soviet Opteron 3LS340A1 LED Display  
Written by AnubisTTP on 2017-09-10  



The 3LS340A1 at first glance appears to be a Soviet analog to early US-made bitmapped displays like the MAN2. However, this Soviet display comes with a twist; each of its LED dots is not made from a separate die. Instead, a single semiconductor 'sliver' die is used for each horizontal 5-dot row, allowing the entire device to be manufactured with only seven dies. This likely made assembly of the display much easier, though it probably increased the number of 'dud' dies that had to be discarded during the manufacturing process. One semiconductor bar in each display has been produced with an extra die, to provide the display with a built in decimal point. Much like early Monsanto displays, the 3LS340A1 was made in both clear and red encased versions; the red version is shown here. The plastic encasement is a hollow cap, which is bonded to the ceramic wafer containing the LED dies and pins.

A noteworthy complexity introduced by the use of mulit-dot LED sliver dies is that individual LED dots can not be binned by brightness beforehand to produce a consistent brightness between all dots in a character. In an effort to mitigate this, each dot is connected with a pair of redundant bond wires, which helps to even out brightness irregularities when multiple dots are lit at once.

Special thanks to Stan Skowronek for donating this unusual part.


3LS340A1 LED display
Soviet 3LS340A1 LED display, all dots illuminated.

3LS340A1 LED dies
Soviet 3LS340A1 LED at 30x magnification. Each line of dots is made from a single bar of semiconductor material. Note the multiple bond wires attached to each dot, which help to even out brightness.

Litton LED Display
This diagram of an American prototype sliver LED shows similar use of doubly redundant bond wires for brightness stability.

Sliver LED Display Prototype
This rare photo shows two American prototype sliver LED die arrays. LEDs using multi-dot sliver dies never saw significant use in the United States...most manufacturers threw their energies into optimizing single-dot LED construction instead.

3LS363A LED Display Family
Soviet 3LS340A1 shown with green 3LS363A LED display.

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