Abstract: A projector device adapted to project an image-forming beam using a lamp as a light source. The lamp is installed within a rectangular parallelepipedal housing, and an exhaust fan is disposed to the rear of the lamp. The top wall of the housing surrounding the lamp is given an opening pattern asymmetric about the optical axis of the lamp by forming an air inlet opening in a position deviated from the optical axis toward a direction orthogonal to the axis for producing a swirling air current within the housing by operating the exhaust fan. The lamp can be effectively cooled with reduced quantities of air.

Abstract: A projector device adapted to project an image-forming beam using a lamp as a light source. The lamp is installed within a rectangular parallelepipedal housing, and an exhaust fan is disposed to the rear of the lamp. The top wall of the housing surrounding the lamp is given an opening pattern asymmetric about the optical axis of the lamp by forming an air inlet opening in a position deviated from the optical axis toward a direction orthogonal to the axis for producing a swirling air current within the housing by operating the exhaust fan. The lamp can be effectively cooled with reduced quantities of air.

Abstract: The invention provides a projector device adapted to project an image-forming beam using a lamp 5 as a light source. The lamp 5 is installed within a rectangular parallelepipedal housing 41b, and an exhaust fan 40 is disposed to the rear of the lamp 5. The top wall of the housing 41b surrounding the lamp 5 is given an opening pattern asymmetric about the optical axis of the lamp 5 by forming an air inlet opening 45 in a position deviated from the optical axis toward a direction orthogonal to the axis for producing a swirling air current within the housing 41b by operating the exhaust fan 40. The lamp 5 can be effectively cooled with reduced quantities of air.

Abstract: An impeller for use in a centrifugal blower comprises a hub for receiving a driving torque at a central portion thereof, a shroud of a ring-like shape in plane formed with an opening for air intake at the center thereof and opposed to the hub across a required distance therebetween, and a plurality of vane members interposed between the hub and shroud as circumferentially spaced from one another at required intervals, the impeller having an arrangement wherein an leading edge of each vane member has varied angles (inlet angles) with respect to a tangent line thereat thereby conforming to inflow angles of an air flow guided by the vane member at different points of a span between the shroud and hub.

Abstract: A number of vanes 12 are disposed in a peripheral direction of a plurality of supporting disks disposed along a rotary shaft 14 at given intervals. Each vane 12 is disposed at an angular interval as determined by a logistic representation. Thereby the intensity and variations of noise levels at around 8N on the low-frequency side, as well as the noise level caused by rotary first-order sounds, can be reduced.