noun
transparency unit
A hardware component, typically in scanners or copiers, for scanning transparent materials like film or slides. Domain-specific computing term.
このスキャナーには透過原稿ユニットが付属している。
This scanner comes with a transparency unit.
Compound of 透過 (transmission, transparency) + 原稿 (manuscript, original copy) + ユニット (unit). The exact historical derivation is uncertain; the term is a modern technical coinage.