| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical sensor capable of precisely detecting a displacement of a detected object with a simple constitution while suppressing size-up and cost-up compared with conventional one, by enhancing resolution in a prescribed photoreceiving area of a photoreceiving part in an optical sensor compared with that in an outside of the area, and to provide a belt drive provided with the optical sensor, and an image forming device provided with the belt drive. SOLUTION: A mask 64 having an opening part of a cross shape is arranged on the photoreceiving face 52a of a photoreceiving element 52 constituting a belt position detecting sensor. Resolution in a peripheral part is lowered in the photoreceiving element 52 while resolution in the vicinity of the central part is maintained, by providing the mask 64, when a conveyer belt 36 is moved width-directionally to generate a wrinkle. Since about 30% of the photoreceiving face 52a is covered with the mask 64, the maximum value of a voltage between the photoreceiving element 52 and a resistance 60 is reduced by 30%. A voltage amplified by an amplifier 61 does not exceed 5 V thereby even when the amplification factor of the amplifier 61 is enlarged about 30%, and signal processing is maintained in a TLT level. |
