DEVELOPER LAYER THICKNESS MEASURING DEVICE, METHOD OF THE SAME, AND METHOD OF MANUFACTURING DEVELOPING DEVICE

PROBLEM TO BE SOLVED: To solve a problem of a conventional device for measuring the layer thickness of a developer of a developing device wherein the measurement data is greatly different from the layer thickness of the developer of the developing device in an image forming apparatus.SOLUTION: This developer layer thickness measuring device 1 used for the developing device 61 includes a developing sleeve 34 that revolves around a magnet roll 51 and holds the developer whose layer thickness is regulated by a blade 67, a guide 52 that is fixed to both ends of the magnet roll 51 and abuts on a photoreceptor 76 disposed in the image forming apparatus 121, and a positioning section 73 used as a positioning reference with respect to the image forming apparatus 121. A first abutting member 2 on which the guide 52 is butted, a second abutting member 3 on which the positioning section 73 is butted, a light source 4 for radiating light towards the developing sleeve 34, and a light receiver 5 for receiving light reflected from the developing sleeve 34 are fixed to a casing 41 of the developer layer thickness measuring device 1. The developer layer thickness measuring device 1 has a controller 7 for calculating the layer thickness of the developer of the developing sleeve 34 based on a signal from the light receiver 5.