DEVELOPER CONCENTRATION MEASUREMENT DEVICE FOR WET- TYPE PRINTING MACHINE

摘要

PROBLEM TO BE SOLVED: To provide a developer concentration measurement device for wet type printing machine which can measure the concentration of developer so that it becomes the actual concentration even when the developer is contaminated. SOLUTION: This measuring device includes a housing 50, a developer oil film forming means arranged at the housing 50 so as to form a developer oil film, a light source unit 81 for irradiating the oil film of the selected color developer with color light corresponding to a wavelength area whose light transmissivity is relatively low with respect to the selected color developer and a sensing means 86 provided corresponding to the unit 81 and including a photodetector receiving the light transmitted through the developer oil film. Thus, since the concentration of the developer is measured by irradiating the thin developer oil film with the color light in the wavelength area having the relatively low light transmissivity with respect to the selected color developer, the effect of the other mixed color toner is relatively small.