Abstract An illumination installation, in particular for lighting a transparent table or support in step-by-step microfilm camera apparatus, such installation providing for the even illumination of a condenser of an image projecting apparatus. A plurality of lamps are distributed over the surface to be illuminated, the lamps being divided into at least two groups. In certain embodiments the current supply circuit for feeding the lamps is divided into two parallel circuits, each of which contains a resistor, there being an amplifier which scans the voltage drop at the resistors and operates an optical and/or acoustical signal transmitter upon an unbalance of the voltage drops through the respective resistors. In another embodiment, the feeding of current to the lamps is divided into at least two parallel circuits, the passage of current through which is compared by a compensatory current transformer which controls a relay controlling an optical and/or acoustic signal transmitter and/or a switch controlling a further apparatus controlling circuit.
In a uniform illumination system: a source of energizing voltage; three first paths each comprising a plurality of serially connected lamps, each first path having corresponding first and second terminals; a transformer having a secondary winding, and a primary winding that includes first and second serially connected portions respectively wound in phase opposition between third and fourth terminals, the second portion having an intermediate tap; means for connecting the first terminal of each first path to one terminal of the source; means for connecting the junction of the first and second portions to the other terminal of the source; means for connecting the second terminal of one of the first paths to the third terminal of the primary winding; switching means operable in a first position to connect the second terminals of each of the remaining first paths to the intermediate tap of the second portion and operable in a second position to connect the second terminal of only one of such remaining first paths to the fourth terminal of the primary winding; and means coupled to the secondary winding for generating an indication when the secondary winding exhibits an output.
Claim 2
Dependent Claim
191 words
In a uniform illumination system: a source of energizing voltage; three first paths each comprising a plurality of serially connected lamps, each first path having corresponding first and second terminals; a transformer having a secondary winding, and a primary winding that includes first and second serially connected portions respectively wound in phase opposition between third and fourth terminals, the second portion having an intermediate tap; means for connecting the first terminal of each first path to one terminal of the source; means for connecting the junction of the first and second portions to the other terminal of the source; means for connecting the second terminal of one of the first paths to the third terminal of the primary winding; switching means operable in a first position to connect the second terminals of each of the remaining first paths to the intermediate tap of the second portion and operable in a second position to connect the second terminal of only one of such remaining first paths to the fourth terminal of the primary winding; and means coupled to the secondary winding for generating an indication when the secondary winding exhibits an output.
Claim 3
Dependent Claim
28 words
A system as defined in claim 1, in which the resistance of each of the first and second portions is low relative to that of each first path.