Patent GB-1232146-A (GB)
IPC: G07C3/14
Filed: 1969-03-28
Abstract: 1,232,146. Cathode-ray tube displays. SIEMENS A.G. 28 March, 1969 [29 March, 1968], No. 16354/69. Heading H4T. Upper and lower tolerance limits 5, 6, Fig. 1, for a graph 4 are traced on the screen of a cathode-ray tube displaying the graph (or on the plotting surface of an X, Y recorder) by deflecting the beam (or tracer element) in the Y direction under the control of electrical quantities selected by means controlled by signals derived by amplitude comparison of the X deflection (time-base) voltage with a group of mutually stepped reference voltages. Referring to Fig. 2, the X deflection waveform U x  is fed to a group of amplitude comparators V 1 , V 2 -V n  which also receive respective mutually adjustable references voltages V 1 , V 2 -V n , of increasing amplitude, from potentiometers P 1 , P 2 -P n , the comparators operating to change the polarity of output voltages (pulses) from negative-to-positive as the amplitude of the X deflection becomes equal to the reference voltages. These output voltages E 1 , E 2 -E n  are then supplied to a logic circuit 8 which derives an output Ua at terminal A for controlling a selector switch 10 which, in accordance with the output Ua selects a particular voltage level U<SP>1</SP> 1 , U<SP>1</SP> 2 -U<SP>1</SP> m  derived from potentiometers P<SP>1</SP> 1 , P<SP>1</SP> 2 -P<SP>1</SP> m  or selects the output of a function generator 15 controlled by the X- deflection waveform. The output so selected Uy is then fed to the Y deflection means Ay. The voltage levels U<SP>1</SP> 1 , U<SP>1</SP> 2 -U m  produce the vertical steps in the curve 5 and the function generator 15 is utilized when steps having slopes, e.g. steps 14, or other configurations are rerequired. The arrangement of Fig. 2, designated S in Fig. 3, may be combined with a similar arrangement S<SP>1</SP> which produces an output U<SP>1</SP>y for tracing the lower tolerance limit 6. The two outputs U y , U<SP>1</SP> y  may be fed to separate deflection devices Ay A y <SP>1</SP> or the device Ay may be dispensed with and the outputs Uy and U<SP>1</SP> y  supplied alternatively to the deflection means A y <SP>1</SP> via a switch 13 operating either after an integral number of cycle of U x  (U<SP>1</SP> x ) or operating several lines during such cycle. When the X deflection waveforms U x  and U<SP>1</SP> x  are identical, the switch 12 and the deflection device A x  may be dispensed with. In an alternate manner of operation the tube beam is scanned in line raster fashion with the lines extending in the Y direction and the outputs Uy, U y <SP>1</SP> are amplitude compared in 17, 17<SP>1</SP> with the line scan waveform 19 to produce bright-up signals at 16, 16<SP>1</SP> for the beam intensity control electrodes 20, 20<SP>1</SP>. The bright-up signals may be short duration pulses so that the tracers are produced as light dots or the comparators may be arranged to produce constant output voltages when the upper and lower tolerance limits are exceeded and under shot respectively, so that the area of the screen outside the tolerance limits is emphasized by brightness modulation. Alternatively, instead of supplying the outputs of 16, 16<SP>1</SP> to the beam intensity control electrodes, they may be fed to an exclusive-OR gate 21 and thence via an inverter 22 utilized to control the beam intensity to produce brightness modulation outside the tolerance limits or, without inverter 22 inside such limits.