Abstract
Adverse effects may accompany the increased popularity of portable computers (PC-FPDs). This paper evaluated the ergonomic aspects of PC-FPD use in two (2) experiments. The first phase studied the posture, muscle load, complaints and performance of the subjects. Ten subjects performed a text-entry task for 5 minutes using a desktop computer and 4 PC-FPDs of various sizes. Viewing and neck angles were lower and the trunk was more forward inclined while using the PC-FPDs. Muscle activities of the neck extensor during work with PC-FPDs were also higher than for the desktop computer. Increasing discomfort and difficulty of keying validated by decreasing performance with smaller PC-FPDs were noted. The second experiment looked at the effect of FPD tilt on body and eye positions and luminance. Another 10 subjects were asked to transcribe sentences using a 13.3-inch FPD with the screen set at tilt angles from 100 to 140 degrees. The results showed that at a 100-degree tilt, the subjects assumed a relatively upward gaze, longer viewing distance, wider elbow angle and forward trunk inclination with the chair height set the lowest and the computer set farthest from the edge of the table. These findings may be explained by the intent of the subjects to obtain the best viewing parameters. The subjects had the greatest difficult using the computer at this tilt angle. This setting was also least preferred during the experiment. Our studies show the need for ergonomic guidelines specific for PC-FPD use.
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