Paper currency validator

In an apparatus for determining the authenticity of paper currency, said apparatus having a conveyor defining a passageway for guiding individual and successive sheets of paper currency in flat condition, said passageway having an inlet for receiving said currency and an outlet for discharging said currency to a storage device, and drive means connected to and selectively driving said conveyor in an upstream direction for moving said received paper currency through the passageway to the storage device or downstream through said inlet;

• security means comprising a light source located along one side edge of said conveyor at said inlet and a light sensor located along the other side edge of said conveyor in opposition to said light source, said light source and sensor operatively arranged in the plane of the currency and transversely to the direction of movement of said currency through said passageway to determine the existence of any foreign object at said inlet after said currency passes said inlet;
• and processing means responsive to the level of the light sensed by said sensor to selectively move said currency forward to said storage device when the level of light is at a first condition or move the currency back out of said inlet when not at said level.