Dust detector for vacuum cleaner

A dust detector for a vacuum cleaner, comprising:

• a dust suction passage for passing dust therethrough;
• a light-emitting element for emitting light into said dust suction passage;
• a light-emitting element cover disposed perpendicular to an axis of said dust suction passage for covering and holding in place said light-emitting element, said light-emitting element cover substantially enclosing said light-emitting element and being transmissive to said emitted light;
• a light-emitting element cover end face exposed to said dust suction passage, said light-emitting element cover end face being flush with an inner wall surface of said dust suction passage and having a diameter equal to or less than the diameter of said light-emitting element;
• a light-detecting element disposed to receive light emitted by said light-emitting element for detecting said light;
• a light-detecting element cover disposed perpendicular to said axis of said dust suction passage for covering and holding in place said light-detecting element, said light-detecting element cover substantially enclosing said light-detector and being transmissive to said emitted light;
• a light-detecting element cover end face exposed to said dust suction passage, said light-detecting element end face being flush with an inner wall surface of said dust suction passage and having a diameter equal to or less than the diameter of said light-detecting element;
• and
• a detector unit, coupled to said light-detecting element, for determining the amount of said dust passing through said dust suction passage, said detector unit being responsive to the intensity of light detected by said light-detecting element.