Patent ID: 7157727

Claim:
A content detecting apparatus for detecting presence and/or absence of a remaining content in a container by means of a signal from a light-receiving part receiving light projected from a light-emitting part, wherein the light-emitting part for projecting light toward the container set in a container setting part and the light-receiving part for receiving the light projected from the light-emitting part are arranged so that optical axes thereof would not accord, the container is provided with a reflecting surface for reflecting the light projected from the light-emitting part to let the projected light reach the light-receiving part when the remaining content is present and with an inclined interface, which is located in a path through which the light projected from the light-emitting part reaches the light-receiving part, for switching a function between permeation and reflection in accordance with presence and/or absence of the remaining content under a condition that the container is properly set in the container setting part, and the inclined interface permeates along the path with the light projected from the light-emitting part when the remaining content is present while the inclined interface reflects the light projected from the light-emitting part in a direction out of the path when the remaining content is absent.