Patent ID: 8671877

Claim:
A coating apparatus, comprising: a rotary drum having an inside portion for accommodating particles to be treated therein and being driven to rotate about its axis, the rotary drum having, along an axial direction thereof, a first end portion, a second end portion, and a circumferential wall portion between the first end portion and the second end portion; and a measuring unit provided at the second end portion of the rotary drum, wherein the measuring unit includes a light transmitting member arranged at an inner wall of the second end portion of the rotary drum so as to be in contact with a layer of the particles in the inside portion of the rotary drum, and an optical sensor arranged at an outside of the inside portion of the rotary drum so as to measure a property of the particles of the particle layer being in contact with the light transmitting member via the light transmitting member, wherein the second end portion of the rotary drum is coupled to a hollow drive shaft of a rotary drive mechanism that drives the rotary drum to rotate, and an inside of the measuring unit communicates with a hollow portion of the hollow drive shaft.