PURPOSE: To enable electrification status of a particle which flows within a container to be directly detected by forming an air curtain in front of a detection head of a potential sensor.
CONSTITUTION: A potential detection unit 2 is mounted to a drying bath 1 and the unit 2 detects electrification potential of a particle through a window hole 3 which is provided at a peripheral wall of the drying bath 1, where the unit 2 stores a potential sensor 6 into a metal case 4 and forms an air curtain formation part 10 by performing polymerization-adhesion of a middle plate 8 and a front outer plate 9 at a front wall 7, air which is jetted out of an air jet-out hold 12 flows vertically along cut-out window 14 of the middle plate 8 for forming an air curtain at a front side of a detection hole 11, and it is jetted into the drying bath 1 through the window hole 3 from an air jet-out window 13. Then, the potential sensor 6 enables a detection head 23 to face an inside of the detection hole 11 and the particle does not directly contact the detection head 23 even if the particle is allowed to flow within the drying bath 1 due to hot wind, thus enabling the sensor 6 to detect electrification potential of the particle without contacting it.
YAGI SHINJI
SAKAMOTO HIROSHI
POWREX KK