Device for measuring concentration of toner in liquid developer, image forming apparatus provided therewith, and method for measuring toner concentration

摘要

Provided are a light-emitting portion 101 having a light-emitting member 104 and a light emergence surface 112a through which light from the light-emitting member 104 emerges, and a light-receiving portion 102 having a light incidence surface 122a through which the light from the light-emitting member 104 enters and a light-receiving member 105 that detects the light entering through the light incidence surface 122a. The light-emitting portion 101 and the light-receiving portion 102 can make relative movement between a measurement position in which the light emergence surface 112a and the light incidence surface 122a make contact with each other and a waiting position in which the light emergence surface 112a is away from the light incidence surface 122a. The light emergence surface 112a is a spherical surface protruding outward, and the light incidence surface 122a is planar in shape. When the light-emitting portion 101 and the light-receiving portion 102 are in the measurement position, the light emergence surface 112a and the light incidence surface 122a make contact with each other at a point.