Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by the process of building-up characters {or image elements} applicable to two or more kinds of printing or marking processes by selective printing from a rotating helical member
Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by the process of building-up characters {or image elements} applicable to two or more kinds of printing or marking processes by selective printing from a rotating helical member