| Russian IPV72A-4/5x7 LED Display | |
| Written by AnubisTTP on 2017-04-27 |
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Though the West produced single die segmented LEDs in both strip packages for calculators as well as alphanumeric smart displays like the DL2416, single die 5x7 LED arrays remained elusive. Early LEDs like the 5082-7000 used manually placed individual dies for their complex bitmapped numbers and their modern descendants continue to use individual dies for each dot, though the dies are now placed electronically. HP researchers long suspected that single die bitmap displays would be almost impossible to produce, due to the porous and conductive nature of the mask layer material. This difficult problem was overcome however, in Soviet devices like the IPV72A-4/5x7. Though at first glance the IPV72A would appear to be a bulkier clone of the Western HDSP-2000, a closer look reveals something much more interesting. Each digit in the IPV72A is constructed out of a single die, with 35 separate LED dots formed into its surface. The manufacturer appears to have solved the diffusion problem through an additional mechanical process; each vertical row of LEDs has had a trench milled or etched alongside it to isolate it from adjacent rows. Bond wires are then installed in the normal way to connect each horizontal row, with the single die providing perfect placement of each dot relative to the others in each character. Manufacturing dies of this size without any defective dots is undoubtedly challenging, and it is unknown how long it took Soviet engineers to perfect this process.
Electrically, the IPV72A-4/5x7 is a feature and pin compatible clone of the HDSP-2000 and other HP 16 pin shift register displays. This display can be dropped into most HDSP-2000 based circuits without any modification, but the package dimensions are slightly larger in both dimensions, which must be factored in when preforming a conversion.
Special thanks to Stan Skowronek for donating this unusual part.
Russian made IPV72A-4/5x7 LED display, with 50% of its dots active. The Cyrillic part number for this device is ИПВ72А-4/5х7.
The IPV72A-4/5x7 makes use of an advanced manufacturing process; each digit is made from only a single die with 35 separate active LED areas.
IPV72A-4/5x7 LED display with coin for scale.
IPV72A-4/5x7 LED display block diagram and pinouts. Note the external connection between the two shift registers on pin 6.
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