Reproduction apparatus with microwave detection

A reproduction apparatus for reproducing documents which comprise a base material, said apparatus comprising:

• a platen for forming a scanning area and for positioning the documents on one side thereof;
• scanning means for scanning the scanning area, said scanning means being positioned on one side of said platen;
• means for obtaining a relative movement between the scanning means and the documents in order to allow for said scanning, said scanning means comprising a microwave system for detecting the presence in said base material of particles having some electromagnetic properties which are substantially different from the corresponding electromagnetic properties of said base material,
• said microwave system comprising a number of microwave sources for generating microwaves, a number of microwave emitters for emitting microwaves to the scanning area, a number of microwave receivers for receiving microwaves which are reflected, and a number of microwave detectors for detecting the reflected microwaves,
• the number of microwave emitters, the number of microwave receivers and the number of microwave detectors being greater than or equal to the number of microwave sources,
• the position and number of the microwave emitters and the microwave receivers being such that they can detect the presence of particles having some electromagnetic properties which are substantially different from the corresponding electromagnetic properties of the base material and being incorporated in at least a part of the base material of the documents, irrespective of the position and size of the documents on the scanning area, and
• wherein the microwave system further comprises for each microwave emitter a switching diode so arranged that it can short-circuit the corresponding microwave emitter.

A reproduction apparatus for reproducing documents which comprise a base material, said apparatus comprising:

• a platen for forming a scanning area and for positioning the documents on one side thereof;
• scanning means for scanning the scanning area, said scanning means being positioned on one side of said platen;
• means for obtaining a relative movement between the scanning means and the documents in order to allow for said scanning, said scanning means comprising a microwave system for detecting the presence in said base material of particles having some electromagnetic properties which are substantially different from the corresponding electromagnetic properties of said base material,
• said microwave system comprising a number of microwave sources for generating microwaves, a number of microwave emitters for emitting microwaves to the scanning area, a number of microwave receivers for receiving microwaves which are reflected, and a number of microwave detectors for detecting the reflected microwaves,
• the number of microwave emitters, the number of microwave receivers and the number of microwave detectors being greater than or equal to the number of microwave sources,
• the position and number of the microwave emitters and the microwave receivers being such that they can detect the presence of particles having some electromagnetic properties which are substantially different from the corresponding electromagnetic properties of the base material and being incorporated in at least a part of the base material of the documents, irrespective of the position and size of the documents on the scanning area, and
• wherein the microwave system comprises two transmission systems, one transmission system for transmitting the generated microwaves and reflected microwaves in one polarization, and another transmission system, being decoupled from the first transmission system for transmitting reflected microwaves in a polarization system which is different from or equal to the polarization system of the generated microwaves.