Air filter device and video projector using air filter device

A video projector comprising:

• an optical system including a light source lamp having an optical axis, wherein the video projector includes an air inlet, through which air is drawn to cool the optical system, and is capable of being oriented in any projection direction within a range of 360 degrees as long as the optical axis of the light source lamp is horizontal;
• and
• an air filter device arranged in the air inlet, wherein the air filter device includes:
• an air filer that captures dust from intake air;
• and
• a cleaner that cleans the air filter, wherein the cleaner includes:
• a rotation brush that rotates about a rotation axis to remove dust from the air filter while moving along an upstream side of the air filter in a direction parallel to the optical axis of the light source lamp;
• and
• a dust box that receives dust removed from the rotation brush, wherein the dust box is an elongated container, which extends parallel to the rotation axis of the rotation brush, and includes a dust inlet, which opens toward the rotation brush to receive the dust from the rotation brush.