PURPOSE: To simply and surely adjust a display state by providing plural light receiving sections to the door of a front face of a screen and projecting a prescribed adjustment use display pattern on the screen while the door is closed so as to adjust and control a deflection means and/or a drive means of a cathode ray tube.

CONSTITUTION: Each of plural light receiving sections 33 each having red, green and blue color light emitting elements 35A-35C is provided in each of surrounding parts 34 fitted to a door 31 freely opened/closed provided to a front face of a screen SC. Then a prescribed adjustment use display pattern TP1 is projected onto the screen SC while the door 31 is closed to adjust and control deflection means 17, 19 and/or a drive means 11 of a cathode ray tube 12. Thus, the display state on the screen SC is easily adjusted.