| 摘要 |
PROBLEM TO BE SOLVED: To detect a thickness of a toner image, with high accuracy.SOLUTION: A carrier for conveying a toner image is irradiated with light. The irradiated light is observed, to measure an incident position of light in a direction perpendicular to a surface of the carrier. A thickness of the toner image is calculated, on the basis of an incident position of first light, which is measured by observing the first light incident on a surface of a toner image, and an incident position of second light, which is measured by observing the second light incident on the surface of the carrier simultaneously with the first light. The first light and the second light are emitted to a position apart in a direction perpendicular to a conveyance direction of the toner image. Irradiation directions of the first and the second light are substantially orthogonal to the direction perpendicular to the conveyance direction of the toner image. |
