ارزیابی ارگونومیک رنگ زمینه ترتیبی یک سیستم طرح ریزی

A field-sequential colour projection system can display colour images using a single panel. Such a system, however, produces characteristic trichromatic separation, or “colour breakup”. Colour breakup is the perceived splitting of the white portions of an image into its red, green, and blue components when the image is projected with the colour sequential method and the viewer’s eyes are moving rapidly. Viewing images containing colour breakup may cause visual fatigue and other symptoms of asthenopia. In this study, the authors examine the various subjective symptoms of asthenopia that can be caused by colour breakup.

Digital light processing (DLP) colour projection systems are already available and increasing their market share. DLP projectors form a binary image by means of a digital micromirror device (DMD). DLP projection systems use either a single chip or three chips to create a colour image. The cheaper and more popular DLP projectors use only a single chip. In a projector with a single chip, the colours are produced by placing a colour filter wheel between the lamp and the chip [6]. The colour filter wheel contains red, green, blue, and sometimes white (clear) filters. The wheel spins very rapidly, creating a sequence of red, green, blue, and white images that are combined into a single full colour image (Fig. 1). This technique is called “field-sequential”. Time sequential RGB images are typically composed of one full colour image every 1/60th of a second. Although the use of a single panel can reduce both projector size and costs, the system’s field-sequential colour projection mechanism can cause the observer to perceive trichromatic separation during times of rapid eye movement [1], [2] and [3].Colour breakup is the perceived splitting of the white portions of an image into its red, green, and blue components when the image is projected with the colour sequential method and the viewer’s eyes are moving rapidly. This trichromatic separation is called “colour breakup” (Fig. 2). Colour breakup is a phenomenon related to the mechanisms of human visual perception. A recent research suggested that colour breakup is perceived because of the imperfections in visual stability. Colour breakup affects visual fatigue in people with congenital nystagmus [4]. And this phenomenon may cause the normal viewer to feel discomfort and even visual fatigue [5].

As in Experiment 1, we extracted the characteristic symptoms of asthenopia caused by colour breakup from Suzumura’s 37 subjective symptoms: Eye fatigue, Eye oppression, Eye pain, Eye heaviness, and Sensitivity to bright light. Five symptoms were also greater when watching colour DLP images compared to monochrome DLP and LCD projector images. In Experiment 2, we examined the effects of colour breakup as manifested characteristic symptoms through various kinds of visual stimuli. The results of Experiment 2 showed that symptom of Sensitivity to bright light were significantly worse when colour DLP was used for viewing slide stimulus than monochrome DLP and LCD projector. The results of these experiments indicate that colour breakup may contribute to specific symptoms of visual fatigue. Among the symptoms of asthenopia, Sensitivity to bright light is characteristic of colour breakup. And four symptoms – Eye fatigue, Eye oppression, Eye pain, and Eye heaviness – were influenced by colour breakup in field-sequential colour projection system. Moreover, the subjects who perceived colour breakup beforehand felt more strongly fatigued and uncomfortable. This result shows that colour breakup is a phenomenon related to the mechanisms of human visual perception. And symptom of asthenopia caused by colour breakup is impossible to solve by training. Characteristic symptoms manifested themselves more clearly when viewing slides, such as the PowerPoint presentations. The slide presentations required that the observer adjust his or her line of sight in order to read the sentence. It is not easy to read movies composed of complex scene. That is to say, the eyes of the subjects were caused to saccadic eye movements horizontally in the slide conditions. Generally, it is known that colour breakup is perceived during fast eye movements, saccade with static [11]. And reading the slide demand repetitive eye movements as saccades and fixations [5]. In this experiment, colour breakup also influenced the observer’s eye movements during fast eye movements. And viewing images containing colour breakup caused symptom of Sensitivity to bright light and other symptoms of asthenopia. As a way to improve projection technology, ergonomic evaluations of display systems have become an important factor for users’ safety. The comfortable use of the field-sequential projection systems requires not only hardware-based technical solutions, such as for frame frequency, but also consideration of the usage and the viewing environment. In this paper, we examined the subjective symptoms of asthenopia in colour breakup. There is a need for more experiential findings that help with the understanding of projection system characteristics. As future work, we will evaluate the effect of viewing various types of field-sequential colour projection system from the viewpoints of safety and amenity and also examine the effects on observers in greater detail.