Security means

US4502048A · kind A · utility

Inventor

• Werner Rehm · Heidelberg, DE

Key dates

• Filing date: Nov 13, 1981
• Grant date: Feb 26, 1985
• Expiry date: Nov 13, 2001

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01H2239/032
• WIPO field: Control
• WIPO sector: Instruments

Abstract

A security device having a keyboard with an array of selectively actuable keys which are activated to generate an output code according to a value designated for each of the keys. A series of display units, such as LED's or liquid crystals, display the designated value for each of the keys. Between successive operations of the keyboard, the designated values for each of the keys are randomly scrambled. Each time the keys are actuated, the designated values of the keys are sequentially registered and the sequential values compared to a predetermined access code to determine if the successively actuated values correspond to the predetermined access code.