Ergonomic evaluation of working posture of VDT operation using personal computer with flat panel display.

The aim of this study was to evaluate working conditions using a personal computer with a flat panel display (FPD) in terms of visual and musculoskeletal comfort. Measurements of viewing distance, viewing angle, head angle, neck angle and electromyogram (EMG) activities of the neck, shoulder and back muscles of visual display terminal (VDT) operators were compared at workstations using an FPD and a desktop personal computer (DPC). A notebook personal computer (NPC) with a 10.4 inches FPD, was used in this experiment. Each of 10 healthy subjects performed word processing tasks using both NPC and DPC workstations. Significant differences in the work posture while using the NPC and DPC were seen with viewing distance, viewing angle and head angle. The characteristic features of the work posture using the NPC were a remarkably short viewing distance and a forward inclination of the head. The value of integrated EMG (IEMG) of the neck muscle was greater while using the NPC than when using the DPC. These phenomena were caused by the structure of NPCs; most NPCs have a display and keyboard which cannot be separated and are not adjustable without tilt and swivel mechanisms. VDT devices that cannot be adjusted may potentially make operators assume a poor posture while working, which could cause visual and musculoskeletal disorders. To prevent visual and musculoskeletal problems using NPCs, a more upright head and neck position was recommended. The addition of a mechanism for adjustment of the height of an NPC display would allow a comfortable downward gaze without the loss of correct posture.