Purity adjusting apparatus using beam position simulation

摘要

Adjustment of an electron beam landing position during thermal expansion of a shadow mask in a color cathode ray tube (CRT) on a production line of color television receivers is performed by calculating an optimum compensation value and converting the compensated data into a coordinate value and displaying it on the screen to decrease the conducting time of the CRT, and improve accuracy and uniformity of purity adjustment. A purity adjusting apparatus includes a time measuring part for measuring the conducting time of a color CRT, a reference drift data calculating part for storing thermal expansion characteristics of a shadow mask of the color CRT, a temperature/brightness measuring part for measuring temperature and brightness of the faceplate of the color CRT, a computing part for calculating compensation value of the beam landing position from the above data, and a display part for displaying an aiming point presuming perfect stabilization against the thermal expansion of the shadow mask from the calculated result on a monitor. Thus, purity can be adjusted in a shorter period and with better accuracy.