To judge the change of ink and water in black ink and the change of an ink of a color other than black and water in consideration that the ratio between reflection intensity at the absorption wavelength of water and reflection intensity at the non-absorption wavelength of water (and ink) changes when water changes and to provide an apparatus for keeping the balance between ink and water by using the judgment method.
Dampening water on the surface of the ink feed roll of an offset press, an emulsified ink film, is irradiated with infrared light N (or M) as reference light of the non-absorption wavelength of water and ink and infrared light W of the absorption wavelength of water, and the reflection signal intensity N1 of the infrared light N (or M) and the reflection signal intensity W1 of the infrared light W are measured by a photoelectric element. The present value N1 by the infrared light N and the infrared light which are being measured is compared with a standard value D1 to judge the increase/decrease of ink and water on the surface of the ink feed roll of the press.
FURUYA NORIFUMI
MOGI MASAO
