Cooling device for overhead type slide projectors

Claim 1

An overhead type transparency projector adapted to project pictures of transparencies carried in a transparency carrier, said projector comprising: a framework with a base, a lamp house housing a light-source lamp and a first condenser lens spaced from the lamp, the lamp house having an open top end and a lower end thereof fixed to said base, a translucent diffusing plate mounted on an upper portion of said framework above said lamp house, a second condenser lens, and a lens-holder member for holding the periphery of said second condenser lens and fixed to an upper portion of the lamp house so as to extend upwards through said translucent diffusing plate, said lens holder member defining cooling passages between said member and said second condenser lens to permit cooling air to flow therethrough and into said lamp house; supporting means for supporting a transparency above said second condenser lens; and cooling means including a blowing fan, an air-blowing nozzle disposed below said transparency and adjacent to said lens-holder member and oriented obliquely relative to the axis of said second condenser lens and toward said transparency supporting means, a connecting tube extending between the discharge side of said blowing fan and said air-blowing nozzle, and a suction fan in communication with said lamp housing at a point on the opposite side of the light source from the side thereof on which the second condenser lens is positioned, whereby at least a part of the air from said air-blowing nozzle flows to a transparency being carried by said transparency supporting means to cool the transparency, and another part of the air therefrom passes through the passages in said lens-holder member and into said lamp house to cool the second condenser lens and the lamp house.