| 摘要 |
<p>In the toner density sensor, including: a light emitting element that emits light; a light receiving element that receives reflected light having been emitted from the light emitting part and reflected at a detection target; a light path formed along the front surface of a printed substrate on which the light emitting element and the light receiving element are surface-mounted, the light path having an irradiation path that allows passage of light applied from the light emitting element, and a light receiving path that allows passage of the reflected light; and a diaphragm unit that is formed at this light path and partially narrows the light path, wherein the diaphragm unit is divided into two portions, which are a diaphragm unit upper portion and a diaphragm unit lower portion, and these are disposed in an upper case covering the front surface of the printed substrate and in a lower case covering the rear surface of the printed substrate. In the printed substrate, a through hole is formed for protrusion of the diaphragm unit lower portion from the rear surface to the front surface.</p> |
