In the study of visual performance of lighting, almost all of them focus on the influence of the amount of illumination on visual performance, that is, the influence of illumination (brightness) on visual acuity or contrast sensitivity. What is different is that some people study Threshold conditions, and others are relatively close to the real-life conditions to study the threshold conditions. The effect of studying the spectrum of the light source on visual performance is rare. Here, the visual performance for achromatic work, because the recognition of color work, that is, the color rendering of the light source has been generally accepted, has also been one of the main performance indicators of the light source in the market.
A very small number of people involved earlier in this problem are Smith and Rea (1979) who systematically studied the effects of both illumination levels and spectra. The illuminance ranged from 7 to 2000 Ix, using a combination of cold white fluorescent lamps, metal halide lamps and high pressure sodium lamps. In addition to these two variables, their studies also included brightness contrast, the "quality" of visual operations and The age of the subjects was affected. The subjects were divided into two ages (under 30 and 50-60). It is required to find errors in the two contrast (0.8 and 0.3) and 8-dot printed and handwritten digital tables under different lighting conditions. The experimental results show that no matter the lighting level, the age of the testee, the comparison of the work and the print quality, there are statistically significant effects on the performance of the work and the evaluation of the difficulty of the test. Only the spectrum is not statistically significant for the evaluation of the work efficiency or difficulty. Impact.
Later, Berman et al. (1987, 1990) found that the rods on the retina had a significant effect on pupil size and perceived brightness under normal indoor lighting conditions, demonstrating that dark visual spectral content in ambient illumination is a major factor in determining pupil size. And is also the main determinant of perceived white light brightness. They also found two illuminators that provide the same visual brightness of the indirect white light, with the illuminating body with a large dark visual brightness producing a smaller pupil and perceived to be brighter, since the spectral distribution of the illumination can affect the pupil The size of the pupil, and the pupil size is also within a certain range can affect the visual performance. Therefore, it is likely that the spectrum also has a significant effect on the visual effects of non-color jobs. They conducted a series of studies to confirm the above inferences.
When the pupil is shrunk, there may be two opposite effects on the performance of the operation. On the one hand, after the pupil is reduced, the performance of the operation may be improved by reducing the effect of optical aberrations; on the other hand, the pupil refraction may be reduced due to the reduction of the pupil, which may It has a negative impact on job performance. Under the general indoor lighting conditions, these two opposite effects are a problem to be discussed, and the benefits or burdens are generated. Shlaer (1937) pointed out that for a fixed artificial pupil with a diameter of 2 mm, the visual acuity of the high contrast L-ring increases with increasing reticular irradiance (up to about 10.000 Tr). Woodhouse (1975) replaced the L-ring with a vertical grating. He found that when the retinal illumination is fixed, the visual acuity of the grating decreases as the pupil size increases. Liebowitx (1962) examined this problem and found that the visual acuity of the grating remained the largest within a fairly wide pupil size range, which depends on the illumination.
Berman et al. (Berman, 1993, 1994) hypothesized that smaller pupils can improve visual performance even if the retinal illumination of the procedure is reduced. To this end, they conducted two series of experiments. The first series used adults aged 20-40 as the subjects to identify the direction of the L-ring gap, and the opening of the L-ring was a 2-point arc, which was presented under four background brightnesses with four brightness contrasts. Two different light sources are used. One source is rich in dark visual spectrum (hereinafter referred to as rich dark vision), which is blue-green with a squint/bright ratio of 4.31. Another light source is a dark visual spectrum with low content (hereinafter referred to as poor dark vision), which is pink, with a scotopic/visual ratio of 0.24 (in order for the reader to have a quantitative concept, the author gives the darkness of the metal halide lamp) The visual/clear-vision ratio is 1.4, and the scotopic/bright-vision ratio of the high-pressure sodium lamp is about 0.4). In the first experiment, the brightness of the operation is kept the same, while providing the same brightness of the brightness, but different darkness Ambient lighting to change the size of the pupil.
The result is that the accuracy of the L-ring is better with a smaller pupil. However, due to the different colors of the ambient illumination, the accuracy of viewing the L-ring may have the effect of different pupil sizes, and there may be effects of viewing the operation due to the different appearance of the nerve-induced color. Therefore, the second experiment is to reduce the effect of this color, so the two different ambient brightness levels provided by the same light source are used, and the work brightness is constant, by comparing the brightness of the two different environments. The effect of pupil size on L-ring recognition performance. In the third experiment, the brightness of the job was varied to check to what extent the pupil was reduced to offset the effect of reduced brightness. The second series of experiments was conducted by the elderly aged 61-66, using the same procedure as the first series, and the results were the same as in the first series.
In the experiment, the two light sources used are obviously not used for general indoor lighting, but they do produce differences in operational performance. The source of the rich dark spectrum spectrum is lighter than the poor dark vision spectrum, for different brightness contrasts and environments. Brightness, with good work efficiency.
The apparent brightness of the surrounding field of view produced by these two sources was 53 cd/m2 (extracted from Berman, 1993).
The explanation for the above results mainly depends on the effect of pupil size. Especially in a large field of view, the size of the pupil is mainly determined by the reaction of rod-shaped cells, even under bright visual conditions. The larger the reaction of rod cells, the smaller the area of ​​the pupil. For the light source used in the above experiments, the area of ​​the pupil under the dark visual source is 40% smaller than that of the poor vision source. A smaller pupil area has three effects on the image on the retina: it reduces the illumination on the retina; increases the depth of the field of view; and also reduces aberrations. This first effect can be thought of as a reduction in visual performance, but the other two effects can be thought of as improving the quality of the image on the retina and thus improving visual performance. But all of these effects are small and related to the innate quality of the individual's eye's optical system. The experimental conditions are close to the threshold state, for example: small size (2 points arc), low contrast (maximum brightness contrast is 0.4) and short exposure time (200ms). Therefore, it can be considered that the pupil size may have an effect on the performance of small, short-lived, flashing, low-contrast achromatic work.
Nevertheless, these findings are still very meaningful, especially in recent years, the metal halide lamps are better than sodium lamps in intermediate vision conditions, in other words, white light (rich visual spectrum) is better than yellow light (poor visual spectrum). This question, in addition to the sensitivity of peripheral vision is better than central vision, does it also contain the problem of pupil size. This is left to young scholars to solve.
Yang Gongxia, School of Architecture and Urban Planning, Tongji University
led light street housing Co., Ltd. , http://www.cnccasting.com