Effect of inspective direction on visual inspection

Abstract

Visual inspection is still playing a major role in inspection process at production lines, and as a result of this human factor involvement, production decrease is often said to be caused by the fatigue of the inspectors and this physical fatigue of the workers itself imposes a serious issue. The visual fatigue mainly comes from lowering activities of the optical system of the central nerves caused by the monotonous workload of inspection. Ishikawa and Sasaki proposed a new visual inspection method paying attention to visual characteristics, and this method improved detection rate of defective outputs from production lines. This productivity improvement is thought to be brought about from a fact that horizontal eye movement gives less fatigue to the optical system. This paper describes a remarked physiological workload difference upon visual inspectors between horizontal and vertical eye movements by experiments of shifting fixations horizontally and vertically, and it is shown from the experiments that the visual inspection method that uses horizontal movement is far more effective.