| 摘要 |
1,067,837. Cathode-ray tube circuits &c. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. June 5, 1964 [June 8, 1963], No. 23379/64. Heading H4T. In an arrangement for producing a signal after completion of a process of variable duration in which the process proceeds in accordance with a varying electric signal which tends towards a variable final value, the varying electric signal is converted into a voltage which tends towards a fixed limit value corresponding to the foregoing final value and the voltage is passed to a comparator which issues, or causes to issue, the completion signal when that voltage approaches its limit value. The embodiment relates to the display of characters on the screen of a cathoderay tube (C.R.T.) ZR which contains a beamshaping matrix containing the whole of the characters one of which is chosen by electric deflection means A1, the beam then being directed to the desired portion of the C.R.T. screen by magnetic deflection means A2. Character control data R arrives from a digital computer to be stored in unit S, switching means V successively transferring the stored data to a digital-to-analogue converter D/A with cyclic repetition to reduce flicker of the display. The deflection voltages from the converter are exponential in form and are differentiated in respective circuits N 1 ... N 4 . The outputs of the differentiators are fed to corresponding comparators K each of which issues a signal when the input signal approaches zero. The comparator outputs are tested for coincidence in an AND circuit U the output from which is differentiated by circuit J so as to change monostable circuit fF into its astable state and in that state cause un-blanking of the C.R.T. beam; on the subsequent return to its stable state circuit fF sends a pulse to circuit V to cause the beam control data for the next character to be fed to converter D/A. Thus the operational time for displaying each character is lower the less the beam deflection. |
