When the surrounding environment changes light and dark, the visual state of the human eye also changes. In the bright environment of brightness greater than 3CD/m2, the pupils of human eyes are small, and the visual originated from the center of the orthopedic (central vision). At this time, the human eye can distinguish the details of the object and feel color. This is the bright vision. When the brightness is less than 0.001cd/m2, in order to see the target, the pupil must be enlarged, and the center vision will be transformed into peripheral vision. At this time, although the general shape of the object can be seen, the details cannot be distinguished or the color cannot be distinguished. All objects are blue -gray. This is the dark vision. The state between the visual and dark vision is called the intermediate vision (intermediary vision). The car driver is in this visual state when driving in the suburbs at night.
Spectral lighting efficiency is used to evaluate the sensitivity of people’s eyes to different wavelengths. The sensitivity of different wavelengths of light in the eyes of the person is different. Human eyes have the highest sensitivity to green light, while the sensitivity to red and purple light is much lower. In other words, the green light and red light (or purple light) of the same energy, the visual strength caused by the former in the eyes is much greater than the latter. Studies have shown that the sensitivity of different observer’s eyes to the light of various wavelengths is slightly different, and it also changes over time, the age and health of the observer. Nowadays, everyone is recognized by the relatively average sensitivity of the light of the light of various wavelength A in 1924 by the International Lighting Commission (CIE). This is the efficiency of spectrum light vision, commonly known as seeing functions.
Figure 7.20 The corresponding gray curve V (λ) is the relative sensitivity of human eyes when visual vision. It is called the spectral lighting efficiency of bright vision, and its maximum value is 555nm. The corresponding black curve V ‘(λ) is the relative sensitivity of the human eye when it is secretive. It is called the spectral lighting efficiency of dark vision, and its maximum value is 507nm. The spectral light vision efficiency (or seeing the function) is usually referred to as the visual spectral light vision V (λ).