1.(1) as a semiconductor component, theoretically, the effective service life of LED lamp can reach 50,000 hours, which is much higher than the 15,000 hours of high-pressure sodium lamp.
(2) compared with high-pressure sodium lamp, the color index of LED lamp can reach more than 80, which is quite close to natural light. Under such light, the recognition function of human eyes can be effectively played, so as to ensure road safety.
(3) when the street lamp is turned on, the high-pressure sodium lamp needs a preheating process, and its light from dark to bright takes some time. It not only causes the waste of electric energy, but also affects the effective development of intelligent control. In contrast, LED lights can achieve optimal lighting at the moment they are turned on, and there is no so-called startup time, so it can achieve good intelligent energy-saving control.
(4) from the luminescence mechanism, high pressure sodium lamp USES mercury vapor luminescence. After the light source is abandoned, if it cannot be effectively treated, it will inevitably cause corresponding environmental pollution. LED and other USES solid state lighting, there is no harmful substances to the human body, is a green environmental protection light source.
(5) from the perspective of optical system analysis, the light source of high pressure sodium lamp belongs to omnidirectional luminescence, and more than 50% of the light needs to be reflected by the reflector to illuminate the ground. In the reflection process, it is inevitable to lose part of the light, affecting its utilization rate. LED lamps are unidirectional, and the light can be directly directed, so the utilization rate is relatively high.
(6) in high pressure sodium lamp, the light distribution curve needs to be determined by the reflector, so there are great limitations; In LED street lamps, distributed light source is adopted. Through effective design of various electric light sources, the light source of lamps can present an ideal state, realize reasonable adjustment of light distribution curve, and control the distribution of light. Within the effective irradiation range of lamps, the illumination is relatively uniform.
(7) at the same time, LED lights have a more perfect automatic control system, which can adjust the brightness of lamps according to different time periods and lighting conditions, thus achieving a good energy saving effect.
2.For example, compared with high pressure sodium lamp, LED lamp has low luminous efficiency and poor illumination. LED lamp irradiation is too concentrated, the uniformity of irradiation is relatively poor; LED light attenuation rate is large, the service life is far from the theoretical life. In fact, these views can be illustrated by the following analysis.
First of all, is the so-called "" luminous efficiency, under the condition of current technology, the LED luminous efficiency is not high pressure sodium lamp, it is an indisputable fact that, but high pressure sodium lamp spectrum is concentrated in the yellow area, its colour temperature is low, only 2000-2500 k, and relatively high colour temperature such as LED, LED street light neutral white temperature of 4000-5000 k, temperature of cold white LED 5000-8000 k. At the same time, compared with high pressure sodium lamp, LED lamp has a higher color index. In actual lighting, it is close to natural light and can bring people a comfortable feeling.
The second problem is the "uniformity of illumination". Although the illumination of LED lamp is relatively concentrated, the secondary design of its light path can make the light source of the lamp present an ideal state, realize the reasonable adjustment of light distribution curve and control the distribution of light, so as to realize the uniformity of illumination.
Then there is the problem of "light decay". In the practical application process, the service life of LED lamp will be affected correspondingly due to the long-term high temperature working environment. The service life of LED lamp at different junction temperatures is shown in figure 1. It can be seen that if the junction temperature is increased from 115 to 135, the service life of LED lamp will be reduced from the theoretical 50,000 hours to 20,000 hours.
Under the current technical conditions, it is basically impossible to improve the luminous efficiency of LED lamps in a short time, so the service life of LED lamps can only be extended by strengthening heat dissipation.