for altering frame speed; for regulating constancy of film speed

Full Title

Projectors or projection-type viewers; Accessories therefor (devices for changing pictures G03B23/00) > Details > Details specially adapted for motion-picture projection (with film moving continuously through the gate G03B41/02) > Driving mechanisms > Mechanisms transmitting motion to film-strip feed; Mechanical linking of shutter and intermittent feed > for altering frame speed; for regulating constancy of film speed