| 摘要 |
PROBLEM TO BE SOLVED: To evacuate the inside of a mirror chamber without other external devices and to decrease the loss and whizzing sounds of a motor and the calorific value of this motor by air resistance by executing air inhalation from the inside of the mirror chamber and executing air discharge to the outside of a case. SOLUTION: The air in the mirror chamber 85 is inhaled from the respective outer peripheral parts of a lower thrust washer 1a and an upper thrust washer 2a. This air is discharged outside of the mirror chamber 85 from atm. communicating parts 5a, 7a and 5b, respectively, without passing the inside of a radial dynamic pressure bearing part 67a. As a result, the atm. pressure in the mirror chamber 85 drops gradually. Both end faces of a sleeve 61 which is the air inhalation part of the radial dynamic pressure bearing part 67a are held at the atm. pressure by the atm. communicating parts 5a, 7a and 5b and, therefore, the diversion of the main parts of the conventional dynamic pressure air bearing type optical deflectors as they are is possible without impairing the bearing rigidity in the radial direction. The simple evacuation of the inside of the mirror chamber 85 is thus made possible. |
