PURPOSE: To obtain a device inexpensive and high in its image performance by making a plastic lens face a front panel of a cathode-ray tube and hermetically sealing a space with a transparent liquid which is formed by adding a specific amount of antioxidant to polyethylene glycol.
CONSTITUTION: A plastic incident lens 2 is made to face a front panel 1a of a cathode-ray tube 1 through a ring-shaped spacer 3, and they are fixed with O rings 6a. Next, a gap 7 is hermetically sealed with a coolant 8 which is formed by adding antioxidant in the amount of 0.001% to 10% to polyethylene glycol (HO(CH2CHO)nCH2CH2OH). Since the coolant 8 is large in heat capacity so as to facilitate the convection, in this composition, heat radiation is effectively performed through a spacer 3, so that a temperature of the lens 2 is suppressed to be 90°C or less. The antioxidant does not cause the coolant 8 to be changed into yellow, so that a contrast is prevented from dropping. Therefore, a device high in image performance can be manufactured inexpensively with small assembling man-hours.
MURANAKA MASAYUKI
TAKESHITA MASAMICHI
NORO YOSHIHIKO
MORI SHIGERU
