| 摘要 |
1510704 Cathode-ray tube circuits PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 8 April 1975 [11 April 1974] 14352/75 Heading H4T [Also in Division G4] In a scanning electron microscope system, Fig. 4 (not shown), including a deflection system generating a television type raster, and in which image distortion is reduced by deducting a third order term from the scanning signal the third order term is generated by a circuit that is unaffected by the frequency of the scanning signal so that a variable frequency scan can be used. A first pair of transistors 20, 21 produce across their collectors a signal proportional to the signal applied to their bases and the current flowing in common collector load transistor 24, i.e. the square of the scanning signal applied at 32. A similar pair of transistors 22, 23 with common transistor 25, produce the cube of the scanning signal and supply it to output operational amplifier 42 from which it is deducted from the orginal signal in an undisclosed manner. In an alternative embodiment, Fig. 3, the third order term is generated by including between input terminal and output amplifier, a voltage-dependent resistor the voltage across which is proportional to I<SP>x</SP> where x is between 0À25 and 0À4. |
