Light head with interchangeable mixing chambers for high speed enlarger

Claim 1

A light head for a high speed enlarger for projecting an image of a film transparency during the making of a print or enlargement thereof comprising: a housing, a light unit assembly being positioned within the housing and including a projection type light source, a condensing reflector providing a concentrated beam of light, and at least one filter unit movable into and out of said concentrated light beam, a replaceable light mixing chamber positioned adjacent and at one side of said light unit assembly, the light mixing chamber including means defining a light inlet and a light exit, said light inlet being positioned at one side of said mixing chamber and said light exit being positioned at the bottom thereof at approximately right angles to the light inlet, film transparency supporting means carried by said housing and being positioned to receive light transmitted through said light exit for projection of an image through a lens to an easel, said light mixing chamber having its light exit of approximately the same size as the transparency with which it is to be used and positioned with its vertical center line coinciding substantially with the center of the film transparency, said mixing chamber being substantially rectangular and having four reflective diffusing sidewalls and a reflective diffusing flat ceiling sloping relative to said sidewalls, said inlet being located to direct light toward said ceiling, said ceiling forming a main light reflecting surface positioned so as to reflect light entering said light inlet towards said light exit, said exit being located under said ceiling, and light directing means interposed between said light unit assembly and the light inlet, said light inlet being of a size as to allow substantially all light passed by said light directing means to enter the light mixing chamber yet not of a size to permit a substantial amount of light to be reflected from the mixing chamber back towards the light source.