تسجيل الدخول

تسجيل

TYPEWRITERS

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  p530-531

2026-08-25

17

TYPEWRITERS

Although the use of typewriters has diminished greatly owing to the development of computer printers, they are still around and still in use. Forensic document examiners are normally asked two questions about typewritten documents: Can the document be traced to a particular machine, and can the make and model of the typewriter be determined? The answer to the first question requires some knowledge about how typewriters operate and how unique characteristics are likely to arise. Older style typewriters generally utilize a standard keyboard. When a key is struck the corresponding raised, metal character mounted on a long stem strikes a ribbon that then leaves an inked imprint of the letter on the paper. As time passes, the metal character may become worn, chipped, bent, or misaligned. This gives rise to reproducible defects that can serve to identify the particular typewriter. Newer model typewriters employ a metal sphere with all of the characters raised on its surface. When a character is struck on the keyboard, the sphere is aligned so that the portion containing that character is lined up with the ribbon. The sphere strikes the ribbon, leaving an inked impression on the paper. Because the characters are all on one sphere and are more rigidly held than if they are on individual stems, these typewriters are less prone to developing wear or misalignments in the typefaces, thus making individualization more difficult. This problem is compounded by the fact that the spheres are easily replaced, so that a comparison of a typewritten document with a particular machine requires the original sphere that typed the document. Determining the make and model of the typewriter that made a document requires that the examiner have a complete library of sample writings of every make and model of typewriter that is available. The font type and size is generally characteristic of particular manufacturer’s models of typewriters, so a questioned, typewritten document can be compared with library entries to determine the make and model used. A typewriting comparison is shown in Figure 1.

FIGURE 1 A typewriter comparison. The arrows point to unusual features of certain letters made by the typewriter in question. The features show up in both the known and questioned typewritings.