PURPOSE: To reduce temperature drift or the like of electron rays while cooling generation of heat with good efficiency by providing a radiation fin on the peripheral part of an electromagnetic coil.
CONSTITUTION: A coil 18 wound in layers is molded in resin with good thermal conduction while being insulation-fixed. The peripheral part of said resin mold part is provided with a fin 20. Further, a magnetic path 21 holding an electromagnetic coil is provided with a feed-in opening 22 and a discharge opening 23 of cooling air. Thereby, when cooling air is ventilated from the feed-in opening 22, heat transferred to the resin 19 is discharged through the fin 20 of the resin mold part while holding the temperature of the electronic lenses almost constant. Accordingly, deformation of parts due to heat is reduced thus reducing drift or the like of electron rays so as to improve drawing accuracy and increase reliability.
KUBOTA SHIGEO
TAKAHASHI TOSHIO
OZASA SUSUMU
HOKOTANI YOSHIO
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