Surface exposure device for copying apparatus

A device for the optical exposure of an original on copying material which is movably arranged, comprising a housing structure;

• a support surface horizontally slidably provided in one housing wall and made of transparent material, the original being arranged on the support surface;
• an exposure plate provided in the housing structure spaced from the support surface and over which the copying material is moved;
• exposure means arranged between the support surface and the exposure plate and including a lens assembly arranged in the housing structure in position to transmit rays of light carrying an image of the original towards the copying material through the exposure plate;
• a reflector arrangement located between the lens assembly and the support surface and including a plurality of mirrors divided into first and second groups, the two groups being conjointly displaceable and the first group being movable reciprocally in the direction opposed to the direction of travel of the support surface;
• guide means arranged in the housing for guiding the groups of mirrors for conjoint movement parallel to the direction of travel of the support surface;
• and control means connected to the first and second groups of mirrors and the support surface and operable, upon movement of the mirrors, to modify a first ray path between one mirror of the first group and at least one mirror of the second group in a manner equal and opposite to the modification of a second ray path between at least one mirror of the second group and said lens assembly, whereby an image ray extending between the support surface and [one mirror] said lens assembly, produced on exposure of the original, always follows a path of constant length regardless of the position of a mirror with respect to the original, said control means also operable, upon said movement of the mirrors, to move the support surface in the opposite direction to the direction of travel of any of said first and second groups, said support surface, said first and second groups and said copying material satisfying the following relationships,
• Vp=Vo +. Va
• Vb=1/2.multidot.Va wherein Vp is a velocity of transference of the copying material, Vo and Va are velocities of movement of the support surface and the first group, respectively, and Vb is a velocity of movement of the second group.