text: First, a big x-height makes the typeface appear perceptually bigger, aiding legibility when text is viewed at greater than average reading distances or at small sizes, or both. Text on monitors was read at distances 50% greater than on paper, according to ergonomic recommendations of the 1980s. Second, the big x-height provides more pixels for better definition of features in the x-height region, which typically carries more information than ascenders and descenders, thus helping distinguish letter shapes for better recognition.
  […]
  Beyond these global adjustments, generous spacing also prevented some local problems when errors in rasterization and fitting make adjacent letters accidentally merge, as often happened with a popular grotesque sans-serif in early laser printers, when ‘r’ touched a following ’n’ and made a spurious ‘m’, turning words like “fern” into “fem”.
  […]
  At low resolutions, these differentiating details can be obscured, so, we lowered the arch join, cutting more deeply into the shape than in normal grotesque sans-serifs. This also tended to increase the thickness of the arch, further distinguishing ’n’ from ‘o’.
  […]
  When we designed the first Lucida fonts, we chose a slightly dark weight to compensate for erosion around the edges of black letters on white background screens and on write-white laser printers, which visually reduce weight, making text look weak in small sizes. The slightly dark weight made Lucida well adapted to most screen displays for almost 30 years, but printing on 300 dot-per-inch write-black laser printers had a slightly darker tone than we desired.