The possibility of changing in principle does not mean, however, that frequent use was made of changing the type wheel. Occasionally there were early historical change-type carriers as well, see z. The change of fonts mainly came into question after the frequent use of spherical heads and type wheels. That is why today the non-proportional fonts are still mainly associated with the term typewriter font. These typewriters were often used for small typesetting work as an alternative to the typesetting machines used by printing companies, and the texts they produce also look set rather than typed. Adrian Frutiger adapted a version of his Univers specifically to the Selectric Composer system, which is based on 9 possible thicknesses. These fonts were often variants of Times-like and Helvetica-like fonts. Later there were also typewriters with proportional font, such as the IBM Selectric Composer (1966). Fonts in 15 CPI are also known as micron. The Prestige Elite font So it has 12 CPI and Prestige Pica has 10 CPI, although the Prestige font is not very similar to the Pica font.
Although the Pica font could certainly also be used in a reduced size with 12 CPI, Pica and Elite also refer to the font density, regardless of the font used. But there were also machines with 12 CPI, for which the font Elite was mostly used.
However, the most common standard size was 10 CPI in pica font. Some typewriter manufacturers also supplied mechanical typewriters in other sizes. It was not until the electronic typewriter that three standardized sizes were introduced: 10, 12 and 15 characters per inch (CPI). The font sizes did not differ significantly from one another. There were a number of variants of these basic types, as well as type carriers with special characters - for example for mathematical formulas. The best-known among them are Letter Gothic (a largely sans serif font), Prestige (a serif font with line width contrast ), Quadro (a somewhat angular, largely sans serif font) and Script (a type of cursive font). The later electric and electronic typewriters with inexpensive exchangeable fonts knew other fonts. There are very different typewriter fonts: those with serifs (such as Courier, Pica or Computer Modern Typewriter ), sans serif (such as Lucida Typewriter ) and even a typewriter script called Roma (for the ball-head typewriter from IBM). They therefore usually have a very uniform stroke width and in this respect resemble the Egyptienne.
Typewriter fonts in the form of types must be very robust, especially fine and thin lines are forbidden. Normal fonts, with a narrow i and a wide M, are called proportional fonts. This leads to special adaptations of the forms: a lower case i has to be artificially widened, a capital M has to be narrowed. In a typewriter font, all characters have the same thickness, i.e. 2 types of fractures for the typewriter.1.1 Commonly used non-proportional fonts.