| 摘要 |
PURPOSE:To automatically correct the shift in convergence by passing the signal of the first pattern generator through vertical and horizontal detectors, detecting whether the shift in the convergence is a DC type shift or not from the horizontal and vertical positions at that time and controlling the correction data of a digital convergenece circuit from the detection signal. CONSTITUTION:When the shift in the convergence is generated, an adjusting pattern passing through the detectors 31, 32 is projected not only in one line but also in several lines 35' and 36' successively to improve a detection speed. The output signal of the detectors 31, 32 is supplied to a position memory circuit 33, as the value of a scanning position, for instance, the detector 31 stores La, and the detector 32 stores Lb and supply to the first detection circuit 34. The first detection circuit 34, from the fetched values La, Lb and basic values L0, L1, performs the operation of L0 -La, L1-Lb, and if both are 0, it is decided that the shift in the convergence is not present, if both are equal value, it is decided to be the DC type shift and if both are not equal values, it is decided to be a dynamic shift, and in the case of the DC type shift, an automatic adjustment is performed and in the case of the dynamic shift, the convergence adjustment is carried out again.
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