A display device 10 consisting of five cells of seven segments each, is used in a photocopying machine in order to indicate normal operation and certain abnormal situations. The latter are indicated by means of messages in plain language, represented by cyclically moving characters. The messages are stored permanently in an EPROM 50, from which they are extracted as required under the command of a CPU 80 in relation to the corresponding type of abnormality, as detected by a set of sensors 82, 84, 86. A suitable subroutine causes the letters of message to slide along the cells of the display device 10 from right to left.

A copying machine including a visual display medium for visually displaying sentences corresponding to the machine operating status and operator instructions for curing machine malfunctions, such as a paper jam. The copying machine includes a sentence display control section which generates signals, representing the sentence or sentences to be displayed, to a drive section which controls the machine display. A machine status signal determines the sentence display control section signals supplied to the drive section. To overcome limitations imposed on sentence length by the limited machine display size, the sentence display control section is provided with means to divide long sentences into sections and to cause the machine display to display long sentences sequentially in a time division manner. A further feature allows multiple short sentences, each capable of being displayed in its entirety on the machine display, to be displayed in preselected sequences, at predetermined times and for predetermined time intervals.

A display apparatus comprising a display device for displaying a character and one or more special symbols to modify the character, by means of a dot matrix, and a control means for controlling the display device. The special symbols may be an underline sign, a bold face sign, etc. The control means effect alternate display at the same position on the display device, of a desired character and one or more special symbols to modify the desired character.

Control circuit for memory type matrix display with k columns and r rows for k times r display elements, wherein each display element can have one of 2.sup.m brightness levels. This control circuit has a video memory for storing brightness information for the display element of each column. It comprises a column memory for each column. Each column memory including m column shift registers. Each column shift register having an input coupled to a corresponding information input for that column, and an output. A line time shift signal C.sub.s being applied to the shift pulse input of all column shift registers for shifting all column shift registers substantially at the end of each line time. The m output bits thus obtained are sequenced by means of a controlled gate circuit to produce a sequence of output bits at the information output of that column. This gate circuit is controlled such that each output bit lasts a predetermined part of the subsequent video line time.

A radio paging receiver comprises a linear array of display elements, a memory having a plurality of storage locations for storing a received message code therein, and a microprocessor-based decoder. The microprocessor-based decoder is responsive to a received preamble code for detecting a match between an address code and a user's own code to store a message codeword into the memory in response to the detection of the match. A first sequence of characters is read from predetermined storage locations of the memory and fed to the display elements. In succession, a blank which immediately follows the first sequence is detected to read a second sequence of characters from the positions immediately following the detected blank and displayed by clearing the characters of the first sequence.