| 摘要 |
PURPOSE:To make the structure compact and light-weight and to reduce the cost by setting a spring constant to a specific value or smaller to press always a layer thickness control member against a toner carrier with a proper pressure by a spring means. CONSTITUTION:The spring constant of the spring means is set to a very small value smaller than 20g/mm, and the spring constant of each of springs 14 and 15 is set to <=10gf/mm because two springs 14 and 15 are used in the example shown in the figure. Generally, the extent of wear of a layer thickness control member 6 is several mm in maximum, for example, 2-3mm and is slight. Since the extent of displacement of the control member 6 is slight and the spring constant of the spring means which presses this member 6 is small, the change of the pressing force of springs 14 and 15 is very small even if springs 14 and 15 are elongated by wear of the control member 6, and the layer thickness control member 6 is pressed against a developing roll 5 with the same pressure after wear as before wear. |
