| 摘要 |
PURPOSE:To detect inferior printing and identify the contents thereof by calculating fraction defective of a non-image area and an image area in each unit region of a printing surface based on reflection density information of each picture element and comparing the fraction defective with fraction defective distribution values set beforehand. CONSTITUTION:Fraction defectives in a non-image area and image area in each unit region of a printing surface are calculated at a central processing device. Reflection density information is obtained in such a manner that a plurality of light receiving elements 1 of a detection sensor 100 for monitoring the printing surface receive reflected light from the printing surface to generate photocurrent, which is subjected to current-voltage logarithmic conversion at a logarithmic converter 13, which information is divided and converted to digital values and stored for each picture element in a storage device 8. Arithmatic processing is applied to the values and fraction defective matrix area ERR (i) and ERR (i) of non-image and image areas are stored in memories 23,24. The values for each picture element in longitudinal direction and fraction defective distribution values 34 are compared at a defective content identification unit 32 to identify defective contents such as oil leak, stripe-like stain to generate identification signal. |
