Typescript inspection
The machine examination of writing is a criminal procedure to draw conclusions about the typewriter , the author and creation date to draw a document.
Various methods are used to examine typewriter fonts : The font comparison technique provides information about the type of machine and the approximate year of manufacture of a typewriter. Reference lists from the typewriter manufacturers are required for this method. B. are available in the criminal investigation offices.
Furthermore, the wear and tear of the types in the typeface can be recognized and used for a rough chronological classification of a document. The examination of the ribbon color and the chemical composition of the ink allow conclusions to be drawn about the ribbon manufacturer and approximate time of use.
Complex methods that can only be carried out by trained specialists are used for the complete decryption of the machine writing. This involves an analysis of the letter shape, the determination of the ribbon feed direction, the ribbon speed and the impact force.
With the ribbon feed direction and ribbon speed method, it is possible to arrange all texts within a ribbon direction (regardless of the type of typewriter) chronologically and also to assign them very precisely to a certain point on the ribbon. This method is so precise that even missing typescripts can be chronologically arranged and their possible length defined.
This is possible due to the typical functionality of the ribbon drive of a mechanical typewriter. The ribbon is unwound from one spool and rewound onto a second. When the end of the ribbon is reached, the machine switches the transport direction. Since the transport of the ink ribbon takes place while the type is being cut onto the paper, the direction of transport can be derived from the resulting characteristic features in the typeface. The ribbon speed can be determined using the same method. With an increase in the amount of ribbon that has already been wound towards the end of the ribbon, the effective diameter of the driven spool increases. Thus, the effectively transported distance of the ribbon to the ribbon end also increases.
Furthermore, when using purely mechanical machines, each user leaves an individual "fingerprint" in the typeface of the typescripts by varying his or her impact force, whereby machine-written texts can be assigned to their respective author. The supposed anonymity of the typescript was lifted with these special methods.
The above methods are more problematic with electrically driven type lever machines and almost impossible with electronic type wheel typewriters. In the case of younger models in particular, the manufacturing tolerances are so low that there are hardly any differences, if any, between two machines from the same manufacturer, provided that both are in a technically perfect condition. However, it would be possible to differentiate between two machines from different manufacturers. Simply by simply exchanging the type wheel, the typeface can be changed almost completely, especially if different step sizes and fonts are used.
In the case of machines with correctable carbon ribbons, the worn ribbon can be used to determine whether a document was written on a particular machine, provided the ribbon used could be ascertained. In the case of such ribbons, the ink transferred for the print is missing on the ribbon. Banks and law firms therefore use uncorrectable carbon or textile ribbons. For office machines, there is therefore a so-called “bank protection” option. This is a mechanical coding in the receptacle of the ribbon cassette which makes it impossible to insert a correctable tape into a machine with a bank security. Non-correctable carbon ribbons and textile ribbons in ink ribbon cassettes always run at the same speed and only in one direction, which makes an assignment as with mechanical type lever machines impossible.
Individual evidence
- ↑ cf. Dieter Eberwein: Nietzsche's writing ball. A look at Nietzsche's typewriter days through the restoration of the writing ball. Eberwein-Typoskriptverlag, Schauenburg 2005, p. 51 ff.