| 摘要 |
<p>PURPOSE:To optically detect the light and shade pattern of a printed matter conspicuously by reflecting an emitted infrared light on a matter printed with a magnetic ink and then receiving the reflected light. CONSTITUTION:Infrared light emitted from a light receiving element 1 is projected onto the surface of a passing printed matter 3 and the reflected light is received by a light receiving element 2. Light and shade pattern of the received light is then detected thus detecting the print pattern on the printed matter. When the printed matter 3 is printed with a magnetic ink containing a magnetic material, the spectrum of infrared light emitted from the element 1 partially exhibits high absorptivity for the magnetic material thus providing a higher contrast as compared with an ink containing no magnetic material. Thus detected light and shade pattern is then amplified, converted into a digital signal, and processed before a decision is made. When the data of light and shade pattern inherent to the printed matter is prestored in a microcomputer, for example, and compared with a previously processed data thus allowing comparison of pattern and decision of the presence of magnetic material simultaneously.</p> |
