Issued Patents All Time
Showing 51–75 of 84 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5803503 | Magnetic metallic safeguarding thread with negative writing | Michael Boehm, Walter Schneider, Theodor Burchard | 1998-09-08 |
| 5801857 | Data carrier having an optically variable element and methods for producing it | Christoph Heckenkamp, Gerhard Stenzel | 1998-09-01 |
| 5599047 | Magnetic metallic safeguarding thread with negative writing and a method of making same | Michael Boehm, Walter Schneider, Theodor Burchard | 1997-02-04 |
| 5567276 | Paper of value and a method of producing it | Michael Boehm | 1996-10-22 |
| 5516153 | Security document and a method for producing it | — | 1996-05-14 |
| 5509691 | Security element in the form of threads or strips to be embedded in security documents and a method for producing and testing the same | Wilhelm Ilgmann, Gerhard Schwenk, Gerhard Stenzel | 1996-04-23 |
| 5483602 | Method and apparatus for detecting printed images on documents by testing for the presence in the images of structural elements having defined regularities which are recognizable by the eye and common to a variety of documents | Gerhard Stenzel | 1996-01-09 |
| 5433807 | Method of producing a document with an unforgeable surface relief | Christoph Heckenkamp, Gerhard Stenzel | 1995-07-18 |
| 5354099 | Magnetic metallic safeguarding thread with negative writing | Michael Boehm | 1994-10-11 |
| 5335572 | Method and apparatus for processing sheets of material in register, in particular for making security threads | — | 1994-08-09 |
| 5324079 | Security document having a security thread embedded therein | Wilhelm Ilgmann, Gerhard Schwenk, Gerhard Stenzel | 1994-06-28 |
| 5267754 | Stamp such as a postage stamp and a method for producing it | — | 1993-12-07 |
| 5248544 | Paper of value having an optically variable security element | — | 1993-09-28 |
| 5239902 | Method and apparatus for processing sheets of material in register, in particular for making security threads | — | 1993-08-31 |
| 5176405 | Security document having a security element embedded therein with visually and machine-testable marks | Michael Bohm | 1993-01-05 |
| 5149139 | Stamp such as a postage stamp and a method for producing it | — | 1992-09-22 |
| 5112672 | Security document having an electrically conductive security element embedded therein | Wilhelm Ilgmann, Gerhard Schwenk, Gerhard Stenzel | 1992-05-12 |
| 4988126 | Document with an unforgeable surface | Christoph Heckenkamp, Gerhard Stenzel | 1991-01-29 |
| 4892336 | Antifalsification document having a security thread embedded therein and a method for producing the same | Jürgen Moll, Gerhard Schwenk, Gerhard Stenzel | 1990-01-09 |
| 4783801 | Apparatus for protecting secret information | — | 1988-11-08 |
| 4765656 | Data carrier having an optical authenticity feature and methods for producing and testing said data carrier | Wolfgang Becker, Alexander Hierweger, Hansjurgen Merkle, Erwin Lob, Joseph Lass | 1988-08-23 |
| 4756557 | Security document having a security thread embedded therein and methods for producing and testing the authenticity of the security document | Gerhard Stenzel, Jürgen Moll, Gerhard Schwenk | 1988-07-12 |
| 4691940 | Printed security with hallmarks | Gerhard Stenzel | 1987-09-08 |
| 4650319 | Examining method for the wear-condition of data carriers | Gerhard Stenzel | 1987-03-17 |
| 4598205 | Security paper with authenticity features in the form of substances luminescing only in the invisible region of the optical spectrum and process for testing the same | Gerhard Stenzel | 1986-07-01 |