| 摘要 |
<p>Recent circuit concepts inject measurement lines, for cutoff and drive control of the cathode current, into each colour channel during the vertical frame blanking period. Owing to the physically dependent exponential beam current characteristic profile as a function of the cathode control voltage (VK), the exponent η of the characteristic profile and the ratio of two cathode components (IK1 and IK2) are in this case used to form control reference values for cutoff and drive control, this process being started in each case from a fixed value of the exponent η or of the ratio of the two cathode currents (IK1 and IK2). However, it has been found that, if a fixed value is assumed for the exponent η or for the ratio of the two cathode currents (IK1 and IK2), it is not possible to achieve an optimum result for displaying monochrome pictures. Thus, according to the invention, the exponent η is defined as a function of the colour tube (1). The aim in this case is to reduce a η-dependent DC voltage offset (u0f) to zero.</p> |
