INSTRUMENT FOR MEASURING VERTICAL LANDING DEVIATION QUANTITY

摘要

PURPOSE:To shorten measuring time and correctly execute measurement by providing a DMA controller which reads deflection data from the memory of a horizontal deflection voltage adjusting device and a horizontal deflection voltage generating circuit in a driving circuit. CONSTITUTION:An image display element 50 displays white by a signal outputted from the image display driving circuit 55. in this state, the horizontal deflection voltage adjusting device 56 for the image display element is used and a horizontal deflection voltage is adjusted at every scanning line so that a phosphor is correctly irradiated with respective electronic beams over the whole scanning lines. The image display element driving circuit 55 being the constitution element of the vertical landing deviation quantity measuring instrument of the beam for the image display element is provided with the DMA controller for reading vertical and horizontal deflection data from the memory of the horizontal deflection voltage adjusting device 56 and the horizontal deflection voltage generating circuit. Therefore, labor and time for adjusting the horizontal deflection voltage is saved since the correctly selected phosphor is irradiated with the electronic beam even if a measuring position in a vertical direction is changed.