Display device for photocopiers

Claim 1

A display device for displaying control messages on a photocopier, comprising a microprocessor unit (80) arranged to handle program instructions and including a read only memory (50) permanently loaded with the character codes of said control messages, a multicell display unit, selectively actuated by said microprocessor to cyclically display said messages, a display register connected to said display unit to contain said characters to be displayed, sensing means responsive to predetermined operating conditions of said photocopier for supplying the microprocessor with activations signals, means cyclically shifting the actuation of the cells of said multicell display unit, each cell being of the seven segment type and adapted to be directly actuated by said character codes, and a pointer register (52) being activated by said microprocessor at the occurrence of said signals to select successively and cyclically from said read only memory (50) each character code of the message to be displayed at a predetermined rate, the microprocessor being so programmed as (a) firstly to transfer one selected character code at a time to a buffer register (56) connected between said memory and said display register, (b) to transfer character code from said buffer register to a corresponding location of the display register and then exchange temporarily the contents of all the locations of said display register back to said buffer register, and again (c) to transfer the contents of the buffer register to the display register in locations shifted by one position whereby all character codes of the message to be displayed are shifted successively and cyclically across the locations of the display register.