A dynamic tactile code in which embossed alphabetic symbols represent the
letters of the conventional Roman alphabet and embossed numeric symbols
represent the conventional Arabic numerals. The alphabetic symbols are
divided into four regions, the alphabetic symbols in the first and third
regions being denoted by a circular frame, and the alphabetic symbols in
the second and fourth regions being surrounded by a square frame. At
least some of the alphabetic symbols embody at least a physical
association of their corresponding letter of the Roman alphabet.
Uppercase symbols differentiate from the lowercase symbols by the
placement of a dot centrally located above the lowercase symbol frame.
The numeric symbols are denoted by a diamond-shaped frame. Certain
essential attributes of the font remain constant while other attributes
change as the font's size is changed. In particular, (1) inter-symbol
spacing changes by a non-constant ratio; (2) line width changes by a
non-constant ratio; (3) symbol element ratios changes by a non-constant
ratio; (4) symbol element location changes by non-constant ratios; (5)
symbol shape changes from font size to font size; (6) symbol elements can
be present at some sizes and not present at other sizes or the element
sizes can vary in different, non-constant proportions to each other; and
(7) at one size, the symbol elements remain fixed or vary based on their
location on a visual display, and symbols displayed in the middle of the
display look different than when they are displayed at the side of the
display.
