Patent GB-1328281-A (GB)
Title: Apparatus for producing on the image screen of a display unit  a visual diagrammatic representation of the variation as a  function of time of a series of measured values present in  digital form
IPC: G01R13/34
Filed: 1970-09-11
Abstract: 1328281 CRT display systems SIEMENS AG 11 Sept 1970 [11 Sept 1969] 43670/70 Addition to 1283706 Heading H4T [Also in Division G4] The raster type display system for displaying measurements in a diagrammatic form of the parent Specification 1,283,706 is modified in that the digital data is fed via input output register 9 (Fig. 1) into a shift register 8 of the type which must be shifted at least at a minimum frequency, the shift register having vacancies in which data is not stored. Data is shifted at a frequency equal to the product of the number of bits in a measured value and the line frequency of the display unit and the vacancies are shifted at a rate equal to or above the minimum permissible frequency to synchronize the circulation frequency of the shift register with the image repetition frequency. As described the shift register comprises semi-conductors of the metal oxide or metal insulator type. Address counter 17 controls the shift rate by enabling a first gate 10 to pass the pulses at a lower frequency when vacancies are being fed into register 9, (i.e. during flyback of the electron beam) and by enabling a second gate 11 to pass pulses at a higher frequency when data is being fed to the register. The sequential arriving data in register 9 is used to preset counter 3 which is then counted by pulses from generator 5 down to zero at which time the electron beam is unblocked for the rest of its line scan. Alternatively the electron beam may be unblanked from the start of the line scan until the counter reaches zero. New data may be entered into register 8 to be displayed in the first line of the display unit by extending the loop 8, 9 by an additional one word register which is switched in for one cycle to lengthen the circulation cycle by one line period. The address of the words in the store are then all increased by one and the oldest measured data is erased. Alternatively to display the newest data in the last lines of the display a switch may be included between registers 8 and 9 operated to connect register 8 as a ring store when the oldest measured value is in register 9. The contents of register 9 are then erased and the new data is entered. A number of diagrams may be simultaneously shown on the display using separate shift registers for each diagram. The video signals for each may have different amplitude so that the diagrams are displayed with different brightnesses. To distinguish more easily between diagrams the brightness may be varied under the control of a counter which counts the number of displayed dots and varies the beam intensity accordingly so that for example eleven dots are displayed with full brightness followed by eleven dots of medium brightness. Curves may also be displayed in different colours. One circulating store may be provided for each of series of measured values to be displayed the contents of a continually circulating counter (20, Fig. 3 not shown) being compared with the states of the output registers (21, 22 ...) of the circulating stores to give unblanking output signals (a 1 , a 2  ...) at equality.