Abstract: A method of determining whether the writer of a sign is the same as the writer of a previously written sign at least one characteristic feature of which has been prerecorded comprises: (a) detecting at least one characteristic feature of the written sign; (b) comparing the or each detected feature with the corresponding prerecorded feature (s); (c) generating an acceptance signal if all differences between the detected and the prerecorded features lie within first predetermined limits; (d) if an acceptance signal cannot be generated, obtaining one or more further written signs (up to a predetermined maximum) and repeating steps (a) to (c) with the or each further written signs; (e) if an acceptance signal cannot be generated for the or any of the further written signs, comparing the differences between the characteristic features of each written sign and the corresponding characteristic of the prerecorded sign and, if all the differences fall within second predetermined limits; (f) comparing corresponding cha

Abstract: This invention concerns a prepayment metering system using a card on which information may be stored and from which stored information may be erased. In one form, a number (A) recorded on the card is read at the meter and stored (30) in preparation for the next card insertion. To obtain a further credit at the meter, the card is taken to a terminal station (12) at which the number (A) recorded on the card is read and is subjected to an encryption process under the control of a key and the resulting number (A') is recorded on the card in place of the previous number (A). On the next insertion of the card at the meter (21), the number (A') is read from the card and subjected to a decryption step (22) using the same key, the result of the decryption being compared with the number stored in the register (30) and in the event of a match a credit is issued.

Abstract: In a method of preparing a gravure printing member by excavating materials from the surface by a scanning laser beam or other energy beam, the path of the beam to the surface is periodically intercepted during the scanning by a rotary shutter, the position and speed of the rotary shutter and the relative movement of the scanning system and the surface of the printing member being such that the shutter shadow is substantially stationary relative to the surface of the printing member during its passage across the beam, the protected portions of the surface constituting the walls of the gravure cells.