GB1283706A - 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 - Google Patents

Abstract

1283706 CRT display systems SIEMENS AG 29 Aug 1969 [29 Aug 1968] 43231/69 Heading H4T [Also in Division G4] Apparatus for producing on a screen of a display unit 1 (Fig. 1) as a function of time a series of measured values in digital form includes a store 4 from which the digital values are cyclically fed via a digital/analogue converter to the display unit. When a new measured value arrives the oldest measured value is erased, the new data being stored in its place. The stored values are preferably sequentially fed to preset a counter 3 which as the electron beam is horizontally deflected under the control of clock pulses is counted down to zero at which time the beam is unblanked. Alternatively, the digital values may be converted to an analogue voltage which is compared with the sawtooth horizontal deflection voltage, at equality the beam being unblanked. Bar diagrams may be obtained by unblanking the beam for the rest of its horizontal scan. The store may be a disc, drum or delay line. In the delay line store of Fig. 3 (not shown), circulating data is read into the store (20) via a gate (G2). When new data is to be read in an address signal is stored in a register (13) and at equality between the register and a counter (17) an output pulse lasting for one word length enables a gate (G1). Preferably, the address register holds the address N - W + 1 where N is the bit capacity of the store and W the word length of the measured value so that after reading of the new data the address counter is at its full count after which it is reset to W so that the addresses of the stored data are switched by one word length. A number of delay line stores may be operated in parallel each store being associated with a preset counter, the outputs from which have different amplitudes so that a number of different brightness may be simultaneously displayed on the screen. Alternatively, the screen may be divided into two upper and two lower quadrants. The data to be displayed in the upper quadrants is first read out to the preset counter, but phase shifted so that the counter is first preset by the data for one quadrant and counted down to control the beam and is then preset by the data for the second quadrant and again counted down to control the beam. The process is then repeated for the lower two quadrants. Measurements may be displayed in colour and scale markings may be indicated on the edge of the screen. The brightness of the display may be made to vary periodically.